Fuel Cell

Projects for the

Evil Genius

Evil Genius Series

Bionics for the Evil Genius: 25 Build-it-Yourself MORE Electronic Gadgets for the Evil Genius: Projects

40 NEW Build-it-Yourself Projects

Electronic Circuits for the Evil Genius: 57 Lessons 101 Spy Gadgets for the Evil Genius

with Projects

101 Outer Space Projects for the Evil Genius Electronic Gadgets for the Evil Genius:

123 PIC® Microcontroller Experiments for the Evil 28 Build-it-Yourself Projects

Genius

Electronic Games for the Evil Genius

123 Robotics Experiments for the Evil Genius Electronic Sensors for the Evil Genius:

PC Mods for the Evil Genius: 25 Custom Builds to 54 Electrifying Projects

Turbocharge Your Computer

50 Awesome Auto Projects for the Evil Genius Programming Video Games for the Evil Genius

50 Model Rocket Projects for the Evil Genius Solar Energy Projects for the Evil Genius

51 High-Tech Practical Jokes for the Evil Genius 22 Radio and Receiver Projects for the Evil Genius Fuel Cell Projects for the Evil Genius

25 Home Automation Projects for the Evil Genius Mechatronics for the Evil Genius:

25 Build-it-Yourself Projects

Fuel Cell

Projects for the

Evil Genius

Gavin D. J. Harper

New York

Chicago

San Francisco

Lisbon

London

Madrid

Mexico City

Milan

New Delhi

San Juan

Seoul

Singapore

Sydney

Toronto

Copyright © 2008 by The McGraw-Hill Companies, Inc. All rights reserved. Manufactured in the United States of America. Except as permitted under the United States Copyright Act of 1976, no part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written permission of the publisher.

0-07-159576-7

The material in this eBook also appears in the print version of this title: 0-07-149659-9.

All trademarks are trademarks of their respective owners. Rather than put a trademark symbol after every occurrence of a trademarked name, we use names in an editorial fashion only, and to the benefit of the trademark owner, with no intention of infringement of the trademark. Where such designations appear in this book, they have been printed with initial caps.

McGraw-Hill eBooks are available at special quantity discounts to use as premiums and sales promotions, or for use in corporate training programs.

For more information, please contact George Hoare, Special Sales, at george_hoare@mcgraw-hill.com or (212) 904-4069.

TERMS OF USE

This is a copyrighted work and The McGraw-Hill Companies, Inc. (“McGraw-Hill”) and its licensors reserve all rights in and to the work. Use of this work is subject to these terms. Except as permitted under the Copyright Act of 1976 and the right to store and retrieve one copy of the work, you may not decompile, disassemble, reverse engineer, reproduce, modify, create derivative works based upon, transmit, distribute, disseminate, sell, publish or sublicense the work or any part of it without McGraw-Hill’s prior consent. You may use the work for your own noncommercial and personal use; any other use of the work is strictly prohibited. Your right to use the work may be terminated if you fail to comply with these terms.

THE WORK IS PROVIDED “AS IS.” McGRAW-HILL AND ITS LICENSORS MAKE NO GUARANTEES OR WARRANTIES AS TO THE

ACCURACY, ADEQUACY OR COMPLETENESS OF OR RESULTS TO BE OBTAINED FROM USING THE WORK, INCLUDING ANY

INFORMATION THAT CAN BE ACCESSED THROUGH THE WORK VIA HYPERLINK OR OTHERWISE, AND EXPRESSLY DISCLAIM ANY

WARRANTY, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO IMPLIED WARRANTIES OF MERCHANTABILITY OR

FITNESS FOR A PARTICULAR PURPOSE. McGraw-Hill and its licensors do not warrant or guarantee that the functions contained in the work will meet your requirements or that its operation will be uninterrupted or error free. Neither McGraw-Hill nor its licensors shall be liable to you or anyone else for any inaccuracy, error or omission, regardless of cause, in the work or for any damages resulting therefrom. McGraw-Hill has no responsibility for the content of any information accessed through the work. Under no circumstances shall McGraw-Hill and/or its licensors be liable for any indirect, incidental, special, punitive, consequential or similar damages that result from the use of or inability to use the work, even if any of them has been advised of the possibility of such damages. This limitation of liability shall apply to any claim or cause whatsoever whether such claim or cause arises in contract, tort or otherwise.

DOI: 10.1036/0071496599

About the Author

Gavin D.J. Harper is the

Technology from the Open University, UK.

author of 50 Awesome Auto

He went on to study toward a Master of

Projects for the Evil

Science in Architecture with Advanced

Genius, Build Your Own

Environmental & Energy Studies with the

Car PC, 50 Model Rocket

University of East London at the Centre for

Projects for the Evil

Alternative Technology. He also holds the

Genius, and Solar Energy

Diploma of Vilnius University, Lithuania. He has Projects for the Evil Genius

undertaken further study with the Open University (all from McGraw-Hill),

and with Loughborough University’s Centre for

and has had work mentioned in the journal

Renewable Energy Systems Technology. He is

Science.

currently reading for his Ph.D. into the impacts of Gavin holds a Diploma in Design & Innovation alternative vehicles and fuels at Cardiff

and a Bachelor of Science (Honours) Degree in

University, Wales.

v

Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.

To John, Helen and baby Ella Maeve,

The Bullas Clan

vi

For more information about this title, click here Contents

Foreword

ix

6

Alkaline Fuel Cells

57

Project 14: Making Electricity

Acknowledgments

x

with Alkaline Fuel Cells

59

1

History of Hydrogen and Fuel Cells

1

Project 15: Plotting the IV

2

The Hydrogen Economy

9

Characteristics

of an AFC

63

3

Producing Hydrogen

23

Project 1: Testing for Hydrogen

24

Project 16: Plotting the Power

Curve of an AFC

66

Project 2: Testing for Oxygen

26

Project 17: Comparing the

Project 3: Investigating Acid–Metal

Performance of Different

Reactions

27

Alkaline Electrolytes

67

Project 4: Investigating the Activity of

Project 18: Comparing the

Metals When Producing

Performance of Different

Hydrogen

29

“Hydrogen Carriers”

68

Project 5: Investigating Water

Project 19: Investigating How

Electrolysis

31

Temperature Affects Alkaline

Project 6: Making Fuel from Water

Fuel Cell Performance

68

with a Hoffman Apparatus

33

Project 20: Investigating AFC

4

Hydrogen Storage

37

Poisoning

70

Project 7: Using Hydrogen Storage

Project 21: Investigating the

Tanks with Desktop

AFC’s Need for Oxygen

71

Fuel Cells

37

Project 22: Investigating Different

Project 8: Boyle’s Law and

Gases at the Anode

71

Compressed

Project 23: Investigating the Rate of

Hydrogen Storage

38

Reaction (Oxygen

Project 9: Exploring Charles’ Law

39

Consumption) of an AFC

72

Project 10: Making Your Own “Carbon

7

PEM Fuel Cells

77

Nanotube”

40

Project 24: Disassembling a

Project 11: Generating Hydrogen

Fuel Cell

84

Using the H-Gen

46

Project 25: Changing MEA Platinum

Project 12: Changing the H-Gen Rate

Loading

88

of Reaction

47

Project 26: Experimenting with

5

Platinum Fuel Cells

51

Oxygen and Air

89

Project 13: Build Your Own

Project 27: Building Your Own

Platinum Fuel Cell

51

Mini Fuel Cell

90

vii

8 Direct Methanol Fuel Cells

95

Project 38: Air Travel with

Project 28: Getting to Grips with the

Hydrogen! Building a

Methanol Fuel Cell

98

Hydrogen-Fueled Airship

166

Project 29: Decommissioning and

Project 39: Building a

Recommissioning a

Radio-Controlled

Methanol Fuel Cell

99

Airship

167

Project 30: Building a Band-Aid®

14 More Fun with Hydrogen!

169

Fuel Cell

100

Project 40: Powering a Radio

9 Microbial Fuel Cells

107

Using Hydrogen

169

Project 31: Building Your Own

Project 41: Hydrogen-Fueling

Microbial Fuel Cell

108

Your iPod

171

Project 42: Making Hydrogen

10 High-Temperature Fuel Cells

115

Bubbles

172

11 Scratch-Built Fuel Cells

121

Project 43: Exploding Some

Project 32: Making Your Own MEAs

126

Hydrogen Balloons

173

12 Hydrogen Safety

135

Project 44: Having a Hydrogen

Barbecue

174

13 Hydrogen Transport

141

Project 33: Building a Simple

15 Fuel Cell Competitions

177

Fuel Cell Car

145

Appendix A: Everything You Wanted

Project 34: Building an “Intelligent”

to Know About Hydrogen . . .

Fuel Cell Car

152

and Then Some

185

Project 35: Building a Hydride-Powered

Appendix B: Fuel Cell Acronym Buster

187

Fuel Cell Vehicle

156

Project 36: Building a

Appendix C: Fuel Cell Associations

189

Radio-Controlled Fuel Cell

Epilogue

193

Vehicle

157

Index

195

Project 37: Space Travel with

Hydrogen! Building a

Hydrogen Rocket

164

Contents

viii

Foreword

Global warming, depleting oil supplies, and energy for students in the classroom, for hobbyists, and independence are all topics of discussion at dinner for the everyday person sitting at the kitchen table.

tables around the world. Politicians argue about It was clear that Gavin Harper was just the person how quickly we need to move to renewable energy, to write this book. I invited him to come and

what the interim steps might be, and how we will work in our small laboratory in our back offices in fund the necessary new technology. Hydrogen is

Boulder, Colorado where he would have access

the most abundant, efficient energy storage device to more equipment and some technical

in the universe. Converting that stored energy to assistance.

electricity will be one of the ways we will

Once there, Gavin greeted us daily, showing his

overcome some parts of the looming energy crisis.

cheery disposition and with frequent exclamations However, few people have an understanding of

of joy as he found another unique way to work

how fuel cells actually work. I have anxiously with hydrogen fuel cells. We were all a bit alarmed awaited the printing of Fuel Cell Projects for the when he came out of the back one afternoon

Evil Genius, so I can share it with teachers, my asking for a Band-Aid® because he was sure he

friends, and colleagues around the world.

could make a Band-Aid® methanol fuel cell. My

Victoria Station of the London Underground

staff and I gave the “evil genius” a Band-Aid® and might seem an unlikely beginning point for a book sent him on his way with a wink and a nudge.

on hydrogen fuel cell experiments. But it was there A few minutes later, he came bounding from the

that I met Gavin Harper with his arms full of an back again—this time, to our astonishment, with a assortment of fuel cell equipment and a look of

Band-Aid® methanol fuel cell running a small fan.

adventure on his face. Gavin graciously guided me It is with this amazing sense of wonder, and a

through the streets of London as we searched for delightful sense of humor combined with a clear

an elusive bottle of distilled water so that I could understanding of the workings of fuel cells that tutor him in the finer points of some of the small Fuel Cell Projects for the Evil Genius has been cells I had sent him from Fuel Cell Store. Gavin written. Enjoy—play—discover the future of

was determined to do something about the energy

hydrogen fuel cell energy for yourself, guided by crisis in his unique and meaningful fashion. We

Gavin Harper’s imagination and wisdom.

discussed the infant fuel cell industry, the energy crisis, and, a bit off topic, Willie Nelson. I was Kathleen (Kay) Quinn Larson

immediately struck by Gavin’s sense of wonder

Founder/Director of Marketing

about the world, and encouraged by the enthusiasm and passion with which he was approaching his

Fuel Cell Store

task of writing a book about fuel cell experiments ix

Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.

Acknowledgments

This book would not have come into being without those with an interest to go and see this technology the generous support of Kay Larson of Fuel Cell

“in the metal,” providing a glimpse into the future.

Store. I am overwhelmed by Kay’s unceasing

I’d also like to thank Allan Jones MBE for his

devotion to promoting fuel cell technologies to

time and theosophy on fuel cells, all of which has young people. You’ll see her at many fuel cell

helped to shape my view that hydrogen and fuel

conferences, and if you take part in the International cell technology will enable rapid change in our

Youth Fuel Cell Competition, you are likely to

energy infrastructure.

bump into Kay.

Thanks also to Tony Marmont for doing such a

Also from Fuel Cell Store, I’d like to thank

great job of stimulating research and scholarly

Quinn Larson, Matt Flood, Jason Burch, and last, discourse regarding clean technologies in the UK, but by no means least, Brett Holland for their

and for giving renewable hydrogen a real boost

support and encouragement. It would also be very with his “Hydrogen and Renewables Integration”

wrong not to mention H the cat—a fantastic

2

project. Thank you to Rupert Gammon of Bryte

companion to a week of fuel-cell experimentation!

Energy, the system architect for the HARI project, I also owe a great debt of gratitude to the guys at for sharing his insight about the project.

the PURE Energy Centre in Unst, in the Shetland

Finally, these books would never come into the

Islands—Dr Daniel Aklil D’Halluin, Ross Gazey,

world were it not for the marvelous folks behind Elizabeth Johnson, and Laura Stewart. PURE are

the scenes who make them happen. I am, as ever,

leading the way in the UK with renewable fuel cell indebted to Judy Bass, for giving me the chance to education.

write, providing encouragement, and being tolerant It’s great to visit PURE and see the technology that of my transgressions. Thanks are also due to the we are talking about in this book being implemented fabulous folk at Keyword, notably Andy Baxter,

in the real world “on a desktop scale”—demonstration for taking my text and pictures, and turning them projects like PURE provide a great opportunity for into the book in front of you.

x

Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.

Chapter 1

History of Hydrogen and Fuel Cells

The way that the “hydrogen economy” and fuel cells Some years later, gentleman scientist Robert

seem to be “ahead of the curve,” and “tomorrow’s Boyle (1627–1691), best known for Boyle’s Law

technology,” you would be forgiven for thinking

(which sounds like a dodgy a 1970s cop series,

that they are a recent innovation; however, our

but is in fact one of the “Gas Laws” that we will story starts over 500 years ago.

explore later in Chapter 4 on hydrogen storage)

The history of the fuel cell starts a little while looked at the reaction between iron filings and

before the development of the fuel cell itself. In acids, rediscovering Paracelsus’ earlier experiment.

this chapter, we are going to look at the history of He published his findings in a paper: “New

hydrogen and the fuel cell, which puts the projects experiments touching the relation betwixt flame and we are going to do in the rest of this book into air” in 1671. He called the gas that he produced context. Know that as you work through the projects

“inflammable solution of Mars.”

in the book, you are following in the footsteps of However, the first person to recognize hydrogen

some of the great scientists and engineers mentioned as a substance in its own right was Henry

in this chapter. Become a proficient fuel cell

Cavendish (1731–1810), who in 1766 noted that

scientist and your name could well be added to this the gas was flammable, and that it produced water list in years to come!

The history of hydrogen

The latin name for hydrogen is “hydrogenium,”

which comes from the Greek words hydro meaning water, and genes which means forming.

The first documented production of hydrogen

was carried out by Theophratus Bombastus von

Hohenheim (1493–1591). As this name was a bit

of a mouthful, he was largely known by the name

Paracelsus—para, meaning higher than, and celsus being the name of a very intelligent chap, Aulus Cornelius Celsus, who lived in the first century—

modesty’s a great character trait!

He produced a gas by reacting metals with acids, and we will see a little bit about that in Chapter 3

on hydrogen production. He did not know what it

was that he had produced, although he knew the

Figure 1-1

Paracelsus—discovered hydrogen, but

gas was flammable.

wasn’t sure what he had discovered.

1

Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.

Figure 1-2

Robert Boyle—discovered hydrogen . . .

again.

Figure 1-3

Henry Cavendish—decided hydrogen was

a unique substance.

when it burned. Cavendish called the gas “flammable air” and published his findings in a paper titled “On Factitious Airs.” For his endeavors, he received the Royal Society’s Copley Medal.

The leap that Cavendish made was to identify

hydrogen as being different from any other gas.

He did this by carefully measuring the density of hydrogen, and also looking at how much was

produced when different amounts of metal and

acid reacted. This systematic, thorough inquiry

has earned Cavendish the title of the person who ultimately “discovered” hydrogen; however, this

“flammable gas” was still without a name.

Jacques Charles decided to employ hydrogen

and put it to good use. This is the first time that we see hydrogen in a transport application.

In 1783, ten days after the Montgolfier brothers rose into the air with their hot air balloon, Jacques Charles ascended into the air in his balloon to a height of 550 meters in his balloon “La Charlière.”

History of Hydrogen and Fuel Cells He also discovered Charles’ Law which is essential Figure 1-4

Jacques Alexandre César Charles.

2

History of Hydrogen and Fuel Cells

Figure 1-6

Antoine-Laurent de Lavoisier.

Figure 1-5

“La Charlière”.

by Joseph Priestley. Lavoisier gave the gas the

name hydrogen, which in Greek translates to water-forming.

to know when looking at hydrogen storage. This

The science of chemistry took a dramatic

states that under constant pressure, a gas’s volume leap forward with the work of John Dalton.

will be in proportion to its temperature.

Dalton proposed a theory of atomic structure,

Antoine Lavoisier has been called the father of

and devised the first table of chemical elements, modern chemistry. Among his great accomplishments, where elements were assigned relative atomic

he disproved the “phlogiston theory,” an obsolete weights. This was published in his work,

scientific theory that held that in addition to what A New System of Chemical Philosophy. Far from were then thought of as the four elements—an idea using the common letter symbols which are

dating back to the ancient Greeks—there was an

used to in modern-day chemistry, Dalton

element called phlogiston which was held in devised a series of graphical symbols (as seen in flammable objects, and released in varying

Figure 1-9a).

amounts as things burned.

Dalton devised the symbol for hydrogen consisting Lavoisier also discovered that the constituents of of a circle enclosing a central dot (Figure 1-9b).

water were hydrogen and oxygen, and went a long

Now we use the symbol “H,” with a small

way towards discovering the composition of the

subscript “2,” signifying that hydrogen naturally gases that make up air. He found that when

occurs in a diatomic state. The Russian scientist hydrogen burned in the presence of oxygen, dew

Dmitri Mendeleev (Figure 1-10), made a

was formed. This built upon earlier observations presentation to the Russian Chemical Society,

3

Figure 1-7

Lavoisier’s apparatus for his hydrogen combustion experiment.

Figure 1-9a

John Dalton’s elements in “A New

History of Hydrogen and Fuel Cells Figure 1-8 John Dalton System Of Chemical Philosophy” (1808).

4

History of Hydrogen and Fuel Cells

Fuel cells are believed to be a very modern,

current technology by many people: however,

their origins can be traced back to the work of

Figure 1-9b

Dalton’s symbol for hydrogen.

Sir William Robert Grove (Figure 1-11).

Sir William Robert Grove is widely heralded as

entitled “The Dependence between the Properties the “Father of the Fuel Cell.” He was born in 1811, of the Atomic Weights of the Elements,” in which in Swansea, Wales. A Welsh lawyer who later

he arranged the elements according to their atomic applied himself to the mastery of science, he

mass. In Mendeleev’s periodic table, hydrogen

published a diagram in 1843 and made a primitive adopts the symbol H.

model known as the “Grove Gas Battery.”

Now we move on from the history of hydrogen,

In the journal, Electrochemistry: History and to the history of the fuel cell.

Theory, published in 1896, Wilhelm Ostwald described Grove’s gas battery (Figure 1-12) as “of no practical importance but quite significant for its History of the fuel cell

theoretical interest.”

The Swiss scientist Christian Friedrich Schönbein The recent flurry of activity by the scientific and can be credited with discovering the underpinning engineering community has brought the fuel cell

principles behind the fuel cell’s operation. There into the public eye. Many would believe that the fuel were two schools of thought: the “contact” theory cell was a recent innovation, however, its roots can and the “chemical” theory. The contact theory stated be traced back to as early as 1838.

that physical contact between materials generated the electricity, while the chemical theory stated that it was chemical reactions which generated the electricity. A furious debate ensued in the scientific Figure 1-10

Dmitri Ivanovich Mendeleev—

Figure 1-11

Sir William Robert Grove.

5

Figure 1-12

The Grove Gas Battery.

Figure 1-14

Francis Thomas Bacon.

community, and Grove’s correspondent Schönbein

We now recognize this family of fuel cells as

argued for the chemical theory.

“alkaline fuel cells”—there is a chapter all about The idea of fuel cells never really developed

them later in this book (Chapter 6)!

beyond a laboratory curiosity after this discovery; The first fuel cell vehicle can probably be

it was not really until much later, in 1959, that a accredited to Harry Karl Ihrig, who built a 15 kW

fuel cell with a sizable power output—5 kW—was

fuel cell tractor in 1959 (shown in Figure 1-15) for developed by British engineer, Francis Thomas

Allis-Chalmers. The alkaline fuel cell used had a Bacon (Figure 1-14).

potassium hydroxide electrolyte and produced

Bacon’s fuel cell used a different technology

20 hp power.

than Grove’s earlier design. He used electrodes of General Electric made a bold leap forward in the nickel in a solution of potassium hydroxide,

early 1960s by developing the proton exchange

initially calling his invention the “Bacon Cell.”

membrane fuel cell. This was used in the U.S.

space program in the Gemini V. The PEM fuel cell was based on a Teflon™ (the material that you

History of Hydrogen and Fuel Cells Figure 1-13 Christian Friedrich Schönbein.

Figure 1-15

Harry Ihrig’s fuel cell tractor.

6

History of Hydrogen and Fuel Cells

find on your nonstick frying pans) solid

electrolyte, which was impregnated with acid.

The Apollo, Apollo–Soyuz, Skylab and Shuttle

reverted back to Bacon’s design of an alkaline

fuel cell.

Since these early days of the fuel cell the

number of fuel cell technologies have grown, and our understanding of the material science of fuel cells has improved rapidly.

A number of technology application prototypes

were developed in the 1960s by major vehicle

and fuel manufacturers, to demonstrate how fuel

cells could be used to provide power for transport applications. However, the 1960s was a time of

cheap, plentiful oil when the world was not looking for a solution to future problems. The energy density Figure 1-17

The alkaline “Bacon Cells” used in the

Apollo missions. Image courtesy NASA.

of early fuel cells was not sufficient to allow

practical vehicles to be manufactured beyond

prototypes and demonstration vehicles.

In the beginning of the 1970s, there was a

renewed interest in fuel cells, driven by the wider concern over vehicle emissions, and the damage

that vehicles were doing to the environment.

The oil shocks of the early 1970s highlighted

to the international community the danger of over-reliance on oil as an energy source, and people

began to investigate the alternatives.

Sustained development by vehicle manufacturers

over the course of the 1980s meant that the internal combustion engine’s efficiency and emissions

improved significantly to the point where it continued to be a viable solution. Many improvements were

made as a result of the increased control over

internal combustion engines afforded by new

electronic engine management systems, and lean-

burn engines reduced many harmful emissions.

However, improvements were incremental and the

Figure 1-16

Proton exchange membrane fuel cell in

fundamental technology underpinning our vehicles Gemini V, 1965. Image courtesy NASA.

changed relatively little.

7

In 1993, Ballard Power Systems exhibited a fuel

reliable, it is important that we evil geniuses do not cell bus, which made important improvements on

lose sight of the fact that by creating new, novel previous fuel cell vehicle applications by showing applications for fuel cells, we encourage investment that higher power densities could be achieved with in the fuel cell marketplace, which brings the

fuel cell technology. This has prompted a renaissance technology closer, quicker.

of major interest in fuel cell technologies. In the last Fuel cells are such a cutting edge technology

decade, with an interest in cleaner, greener ways of that applications are being developed for them

doing things, driven by concerns over peak oil,

every week—not just by big, well-funded industry, energy security, and climate change, fuel cells have but equally by teams of college or university

again been in the spotlight as a potential solution to students. A team called Energy Quest plans to race some of our energy dilemmas.

their hydrogen fuel cell powered boat, Triton, in In 2003, the first public hydrogen filling station the near future.

was opened in Reykjavik, Iceland, which serves

Howaldtswerke-Deutsche Werft AG (HDW), a

the three hydrogen buses in the city as part of the German company, has developed the Class 212

CUTE project.

submarine, a nonnuclear submarine that can remain submerged for weeks, without needing to come to

With improvements in the energy density of fuel

the surface because of its PEM fuel cell technology.

cells, it is not only the big vehicles that can now use fuel cell technology, but also much smaller

modes of transportation. In 2005, Intelligent

Energy released the first fuel cell motorcycle,

capable of travelling up to 50 mph, and with a

range of 100 miles in an urban driving cycle. It really doesn’t make sense to transport around

several tons of “dead weight” for one-passenger

journey—with questions over fuel security, we

If you are interested in the history of fuel cells, or may have to adapt, and realize that some of the

maybe even need more information for a school

most sensible solutions to problems aren’t

project or report, there is a rich archive of

technical ones, but societal ones—driving small

information on the Internet containing further

vehicles more fitting for our needs than our wants.

reading, on not just the low-temperature fuel cells So what does the near future hold for fuel cells?

that we will be experimenting with in this book, but also the high-temperature fuel cells, which There are a number of fuel cell projects that are because of their high operating temperatures aren’t close to completion, and appear to be technologically suitable for home experimentation.

feasible in the near term. We can already see a wide The Smithsonians’ history of fuel cells,

range of fuel cell applications that have emerged in comprehensively covers the higher temperature

the past couple of years; and with the experience fuel cells which are not included in this book:

and information learned from demonstration

americanhistory.si.edu/fuelcells/

projects, the next generation of demonstrations will Fuel Cell Store’s history of fuel cells:

have improved upon the current state of the art by employing the knowledge gained. While there is

www.fuelcellstore.com/information/fuel_cell_

further work to be done in the labs by the

history.html

“materials scientists” working on improving the

A history of fuel cell development at Los Alamos chemical process to convert fuel to power and to National Laboratory:

History of Hydrogen and Fuel Cells make fuel cells longer lasting, cheaper, and more www.lanl.gov/orgs/mpa/mpa11/history.htm

8

Chapter 2

The Hydrogen Economy

You’ve heard a little bit so far about the history of hydrogen, and how fuel cells came into being,

but why are we so interested in this gas? What

is so special about it? Before we launch into the experiments, you need to be aware of why we are

doing this, and why fuel cells are the next big

thing for smart evil geniuses to be interested in.

We are going to explore the physical properties of hydrogen gas, and look at how—with fuel cell

technology—hydrogen could become a player in

meeting our future energy needs, and delivering

the sustainable energy revolution.

Hydrogen

Figure 2-1

Hydrogen as it appears in the periodic table.

Take a look at any periodic table, and you will find comprized of two atoms of hydrogen (for those of hydrogen right at the top. It is element “numero you who don’t know Greek, di-is a prefix meaning uno,” the first element in the table and the lightest

“two”).

of all elements. The gas is colorless, tasteless Looking at Figure 2-2, we can see how there are

(although we don’t recommend tasting chemicals!), two atoms that make up diatomic hydrogen. The

and nonmetallic. If you take a peek at the periodic protons in diatomic hydrogen occupy the two

table, you will see hydrogen in the first box to the black dots that represent the central nuclei, while top left (just above lithium). The box that you will the electrons can be in any position in a “cloud”

see will look something like Figure 2-1.

surrounding them. This is because we cannot say

You will see at the top of the box the number

with certainty where exactly the electron will be,

“1”—this is hydrogen’s place in the periodic table.

Beneath the “1”—you’ll see “H,” the chemical

symbol for hydrogen, and beneath this, you’ll see 1.00794 this is how many grams a “mole” of

hydrogen weighs, which makes it the lightest

element.

Hydrogen comprises of one “proton,” and

one “electron” in its most common form

“protium”—hydrogen is a “diatomic” molecule.

This means that naturally occurring hydrogen is

Figure 2-2

Representation of diatomic hydrogen.

9

Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.

but we know the probability of it being a certain in the process. In the process of doing so, they distance from the nucleus. The gradient “probability release energy—“chemical energy.” Where does

cloud” illustrates this.

this energy come from?

At room temperature, hydrogen is a gas; in

Hydrogen and oxygen, as elements, can be

fact, it boils at 20.28 Kelvin which is the same considered to be at a high energy state. When as -252.87∞ Celsius, or -423.17∞ Fahrenheit.

combined together as water, they can be considered One of the problems is in trying to store this

to have a low energy state. In the process of hydrogen in a form that is compact—because even

combining them—whether by combustion or using

though hydrogen doesn’t weigh much, in its gaseous a fuel cell—the chemicals change from a high form, it takes up a very large volume! Chapter 4

to a low energy state, but this energy must go will be looking at different ways of storing

somewhere! (As energy is never created or

hydrogen.

destroyed—only changed from one form to

another). This energy is the energy that manifests To give you an idea, of the difference in volume itself as heat if we burn the hydrogen, or as

between liquid hydrogen and gaseous hydrogen,

electrical energy if we use the hydrogen in a fuel take a look at Figure 2-3. Hydrogen has an

cell. This change in energy states is illustrated in expansion ratio of 1:848. This means that when it Figure 2-4.

is stored as a liquid, a volume of “1 unit” of gas will increase 848 times when allowed to expand

Now, we need to get hydrogen from somewhere.

into a gaseous state.

In the same way we can make water with hydrogen

and oxygen, we can also make hydrogen and oxygen Hydrogen is the most abundant element in the

from water; however, we also need to “input”

universe, however, on Earth, there are only 0.55

energy to disassociate hydrogen from oxygen in

parts per million by volume of hydrogen in our

the process of electrolysis.

atmosphere. Most of the hydrogen on Earth is locked up in the water that makes up our seas, lakes, and Electrolysis is one of the ways that we can

rivers. The chemical formula for water is H O,

produce hydrogen, and we will carry out some

2

which means that water contains two hydrogen

electrolysis experiments later in this book.

atoms and one oxygen atom.

Hydrogen has the potential to be a very clean,

Our fuel cells take hydrogen fuel, and oxygen

green, fuel. In fact, it’s very easy to get into the from the air, and produce water, releasing energy habit of calling it a “fuel”—after all, we use it in The Hydrogen Economy Figure 2-3 The expansion ratio of hydrogen.

10

The Hydrogen Economy

We need to make an input of energy somewhere into the process to produce hydrogen. The only

emissions where the hydrogen is consumed is pure, clean water—no problems so far, but problems can arise if the energy we use to produce the hydrogen comes from “dirty” sources.

“Green” hydrogen

So, there are a number of ways in which we can

produce “green” hydrogen. We can use renewable

energy technologies to produce electricity, and this electricity can then in turn be used to produce

hydrogen gas by a process called electrolysis. We Figure 2-4

Hydrogen and oxygen combine to make

can see this process in Figure 2-5.

water, releasing energy in the process!

Let’s explore some of these different energy

technologies in a little more detail.

“fuel cells.” However, since we can’t easily get hydrogen in its elemental form—we can’t dig it up from the ground—it is better thought of as an

Solar power

“energy carrier,” a bit like electricity is a “carrier”

for energy, but not really a fuel.

We can harness the power of the sun in photovoltaic So, hydrogen can be a “carrier” for “clean

cells. In fact, we can produce electricity using energy” or it can be a carrier for “dirty energy.”

photovoltaic cells and feed this to a separate

Figure 2-5

Hydrogen produced from clean, renewable energy.

11

Figure 2-6

A solar array showing solar power—energy from the sun.

electrolyzer, or, we can use the photovoltaic cells effectively “immersed in water,” to electrolyze the water directly. Some scientists are working on

types of algae that can harness the sun’s energy directly to produce hydrogen. All of these

processes use the sun, which is clean, free and

cheap—our safest nuclear reactor—9.295 × 107

miles away from the Earth, or if you are travelling in a hydrogen-fueled spaceship going at lightspeed (not yet invented, so watch this space), you could be there in 8.31 minutes.

Note: If you are interested in learning more

about solar energy, you might like to check out my other publication, Solar Energy Projects for the Evil Genius (McGraw-Hill).

Wind power

We can also harness the power of the wind, using wind turbines, to produce electricity, which can then be used to produce hydrogen cleanly. Turbines take the movement of the air (which is caused by air rushing from an area of high pressure to an

area of low pressure) and use this force to turn the Figure 2-7

A wind turbine illustrating the power we

The Hydrogen Economy blades of a turbine. As the turbine blades turn, they can harness from the wind.

12

The Hydrogen Economy

drive a generator; sometimes directly, sometimes influence of gravity, make its way back to the seas.

through a gearbox. The power from this generator This forms rivers and streams all over the land. We is then rectified. Once we have this electricity, can capture water when it is at a high point, channel we can feed it into the electricity grid that supplies it through a turbine or waterwheel, and capture

our homes, and then use the power to electrolyze energy from the turbine to produce electricity. In water into hydrogen at times when the wind is

the process of falling from a high location to a blowing, but people aren’t using much electricity low location, the water releases gravitational (as in the still of night when everyone is in bed).

potential energy, and it is this that we capture This makes use of cheap energy to produce our

in a hydrostation. This hydrostation can be used to hydrogen. Additionally, in remote islands or

electrolyze water into hydrogen and oxygen.

isolated locations, hydrogen can be used to

store electricity and even out fluctuations in

load, even when there is no connection to the

Wave/tidal power

electricity grid.

Wave and tidal power are distinctly different;

however, we often class them together as they are Hydro power

“power from the sea.” Tidal power is a process

that is driven by the moon as it orbits the Earth.

The hydrological cycle is where water evaporates The influence of the moon’s gravity on our seas

from the seas and the land, driven by the sun,

causes the water to “bulge”—this forms the tides collects in the clouds, and rains back to the ground which are regular and predictable. Mariners and

(a process called precipitation). When the rain

seafarers will know to a great degree of accuracy lands on the ground, it can land on mountains or when the tide is low or high, and we can use devices hills, (high areas) where it must then, under the submerged in the sea to capture the mass of energy Figure 2-8

Power can be captured from falling water to generate energy.

13

Figure 2-9

Model of a wave energy capture device.

as water rushes from place to place. Wave power, by contrast, is the power in the surface of the

waves—think of surfers riding along waves, and

Figure 2-10

A plume of hot water, driven out of the

the energy and power that waves can exert.

ground by geothermal energy.

Devices that float on the sea or near to the surface can capture these waves to turn the power into

which enables them to take carbon dioxide out of electrical energy and transmit it back to the shore.

the air, combine it with hydrogen and oxygen from In both these instances, when the power reaches

water to make food to nourish the plant, and allow the shore, it can be used to electrolyze water into it to grow. We can take biomass, and turn it into hydrogen and oxygen.

fuels—biodiesel, bioethanol, but we can also

extract the hydrogen directly from biomass, such as the woodchip waste shown in Figure 2-11, using Geothermal power

Geothermal energy, energy from the heat in the

core of the Earth, can be used to raise steam to drive conventional steam turbines to produce

electricity, which can be used to provide hydrogen.

Biomass

All the living things that we are surrounded by—the trees and plants and crops that grow in farmers’

fields—are a mass of biological matter. The sun

The Hydrogen Economy drives a process called photosynthesis in plants, Figure 2-11

Biomass—power from plants.

14

The Hydrogen Economy

gasification and reformation processes, similar to and its chemical structure (CH ), there are four 4

those used to extract hydrogen from fossil fuels. This hydrogen atoms for every carbon atom. Look at

does produce carbon dioxide; however, the only

oil, and the amount of carbon relative to hydrogen carbon dioxide produced is that which has been

increases—take petrol, which contains many

extracted from the atmosphere by the plant as it different lengths of hydrocarbon chain—but we

grew!

can approximate to octane, and you see the ratio of hydrogen to carbon is nearer: 1:2 (C H ) while

8

18

methane is 1:4. Start to look at coal, and the story begins to get even more grim—as coal is largely

“Dirty” hydrogen

comprized of carbon, there is much more carbon dioxide produced than hydrogen.

At the moment, most of our hydrogen is produced

using “dirty” methods. Fossil fuels, coal, oil, and Alternatively, we can burn fossil fuels in a

natural gas, are taken and “reformed” into hydrogen.

conventional fossil fuel power station, like the one in However, fossil fuels also contain a high proportion Figure 2-13, and use that electricity for electrolysis.

of carbon. This carbon has to go somewhere—as

However, although this is very undesirable, it is part of the reformation process, the byproduct,

not all totally bad news. Compare producing

“carbon dioxide,” is produced. Carbon dioxide is a hydrogen in this way to burning the fuels directly greenhouse gas which adds to the “greenhouse

in your vehicles and over a range of scattered

effect,” which leads to the problems that we are locations. By producing hydrogen, you are making beginning to witness with global warming and

all of the carbon dioxide in a central location, climate change.

where it can be captured. Once we have separated Coal, oil, and gas can all be taken and turned into and captured the carbon dioxide, we don’t just

hydrogen using a process called steam reformation, have to release it into the atmosphere; we can do which takes the fossil fuels, combines them

clever things with it—like trap it, and contain it.

with steam at pressure and very high temperature, A process called carbon sequestration can be

stripping the carbon, producing carbon dioxide,

used to take carbon dioxide, and inject it deep

and capturing the hydrogen for use in fuel cell

underground, into geological features, where

vehicles. Natural gas contains the highest ratio the CO is trapped and (touch wood) cannot

2

of hydrogen to carbon. If you think about methane escape.

Figure 2-12

Hydrogen produced from dirty fossil fuels.

15

Figure 2-13

Fossil fuel power stations can generate hydrogen to produce electricity.

The large oil and energy interests find this

By forcing carbon dioxide into oil wells which are technology very attractive. The reason for this has nearing the end of their economic life, the carbon less to do with altruism and the preservation of the dioxide can be used to force additional oil to the human race, and more to do with oil and profits.

surface, recovering deposits of oil that would

otherwise go to waste.

Nuclear hydrogen

Some people advocate a hydrogen economy based

upon hydrogen produced en masse by nuclear

power. We can see by looking at Figure 2-15 that nuclear power is used to produce electricity, which in turn is used to convert water to hydrogen by

electrolysis.

Unfortunately, the byproduct of this process

is toxic, radioactive nuclear waste, which takes thousands of years to decay to safe levels—and we still haven’t worked out a permanent solution for what to do with it!

The reason that some people advocate nuclear

power is that no carbon emissions are produced

by the actual process of producing electricity from Figure 2-14

nuclear fuel. However, take into consideration

The products of combustion from fossil

The Hydrogen Economy fuel plants like this could be captured and sequestered.

the massive amounts of concrete and building

16

The Hydrogen Economy

Figure 2-15

Hydrogen produced from nuclear power.

materials needed to build a nuclear plant, consider Furthermore, once their useful life has finished, the carbon dioxide produced in blasting, mining, nuclear power stations, like the one in Figure 2-16, extracting, refining, transporting, storing, and need to be decommissioned—a process which

processing nuclear fuel, and suddenly you realize requires a great amount of money, and a great

that there is an awful lot of hidden carbon dioxide investment of energy—with its associated carbon

in this process.

emissions.

Figure 2-16

Nuclear power stations leave an ugly blot on the landscape.

17

top of the existing shelf, trapping little pockets of The need for cleaner

gas. We can analyze these pockets of gas to find out an abundance of data about what our climate

technologies

was like at different times.

Since the Industrial Revolution, through the oil boom of the 1960s, the human race’s burgeoning

need for energy has resulted in a rise of carbon dioxide emissions globally.

A monitoring station on the Island of Mauna

Loa, in remote Hawaii, has been monitoring

If you want to read more about ice cores, there is the levels of carbon dioxide since the mid-1950s.

a comprehensive and informative article on

The results are displayed as a graph in

Wikipedia: en.wikipedia.org/wiki/Ice_cores

Figure 2-17.

So, why have carbon dioxide emissions recently

It is clear to see that since the 1950s, the level of shot up?

carbon dioxide in our atmosphere has continually The growth of our economies has been founded

and steadily increased.

on cheap oil, and the perception that “the

“But how do we know that there wasn’t this

world’s resources are endless.” As we begin to

much carbon dioxide in the atmosphere before

find resource shortages, we will quickly begin to 1955?” some people counter. Well, in addition to realize that the Earth’s resources are indeed

taking measurements of carbon dioxide from the

finite.

atmosphere, it is also possible to drill great cores Ever since the Industrial Revolution, our demand of ice from the Antarctic. This ice has been formed for fossil fuels, and other resources has grown.

over many, many years, as snow deposited itself on Looking at Figure 2-18, we can see how suddenly

man-made (anthropogenic is a word you will

often hear used) emissions have soared rapidly. In fact, most of these emissions were created in the past century.

Think of all the things that we can do in this

century, which wouldn’t have been possible

last century, or even decades ago. Think about

the massive amount that we use our cars. Mass

production has enabled everyone in the developed world to be able to own a car should they choose.

We have seen the growth in numbers of families

with not just one but many cars. All these vehicles require energy to be made, and in use. Look at

aviation as another growth sector. Fifty years ago, aviation was expensive, for the elite, but now it is possible to fly so incredibly cheaply that the number of flights taken has soared (literally) into The Hydrogen Economy Figure 2-17 CO measurements taken at Mauna Loa.

the sky!

2

18

The Hydrogen Economy

Figure 2-18

Global fossil fuel carbon emissions since the Industrial Revolution.

countries such as China and India, whose economies So what’s the problem?

are growing rapidly. With this rapid growth comes increased demand on resources and energy.

Well, the first one is climate change. If you haven’t And there’s another reason for looking at

already seen Al Gore’s “An Inconvenient Truth,” it hydrogen: you might have noticed that the price of is a great primer on climate change for evil geniuses gas at the pumps has been increasing significantly of all ages. The carbon dioxide that we produce

recently. Chances are that from here onward prices when we burn fossil fuels is one of the gases that aren’t going to come down significantly for any

contributes to a phenomenon called “the greenhouse long period of time.

effect” which produces global warming.

A scientist from the American Petroleum Institute, Looking back to earlier in this chapter, you will Marian King Hubbert, made a prediction in 1956

remember that there are “clean ways” in which we that oil discoveries would follow a bell-shaped

can produce hydrogen, without producing any

curve. Take a look at Figure 2-19, as we are going to carbon dioxide emissions in the process. Of

look through the features of the graph.

course, at the moment, our technologies and

infrastructure are geared towards a carbon-based economy. At the moment, most of our hydrogen

available for use in fuel cells comes from carbon-based fuels, however, with future development of renewable energy resources, the hydrogen

economy offers some attractive prospects for a

Peak oil is an important subject to read up on, for world moving toward a cleaner future.

any budding evil genius interested in fuel cell

technology. Wikipedia carry some good articles

The thing is, it isn’t just the countries that are on this, which I highly recommend:

already developed that are going to require energy.

en.wikipedia.org/wiki/Peak_oil

While the energy demands of America and Europe

en.wikipedia.org/wiki/Hubbert_peak_theory

continue to grow, we must also think of developing 19

production—peak oil—which means from here

forward, oil starts getting a lot harder to find. As a result of the increased effort that needs to be

expended to find new oil, the price will begin to soar. Rather than being cheap and plentiful, oil will start to become more expensive, as it becomes

harder and harder to find and produce. The price begins to rise, and rise, and rise, while the actual amount of oil entering the system begins to

decline. Now, remember, we don’t just need oil for transportation, we also use oil in the production of pharmaceuticals, plastics, paints, and various

finishes, so we don’t want to spend all of our budget of oil on transportation and producing

energy—this could be where hydrogen and fuel

Figure 2-19

Hubbert’s peak oil bell-shaped graph.

cell technology enter the arena.

Hubbert said that for any geographical area—

whether a single oil field, the oil reserves of a Why hydrogen?

state, nation or continent—or ultimately the entire world, the rate at which oil was discovered would The ways that we currently “extract” energy from follow what is called a bell-shaped curve. If you fossil fuels are pretty wasteful. If we look at Figure look at Figure 2-19, you can see that the area

2-20, we can see a range of different devices that enclosed beneath the line sort of resembles a crude we use for producing useful energy from fuels. We drawing of a church bell.

can see that fuel cells, over a whole range of

powers, eclipse the efficiency of even the best

Looking at the beginning of this curve, we see hybrid solutions and turbine applications.

that when oil was initially discovered, it wasn’t produced in great profusion, as people were

still finding applications for it, and investing in infrastructure to produce and refine it. As we slowly discovered how darn useful oil actually was,

people began to consume more of it, which in turn drove the production of oil. With the invention of the internal combustion engine, and the spread of the motor car, our consumption of oil has soared (with a massive increase in carbon emissions as a result). However, this growth is not without limits.

There is a finite amount of oil in the Earth’s crust.

We have found all the oil that is “easy to

discover,” the oil that is in the accessible

places that can be easily and cheaply reached.

Figure 2-20

Technologies for converting energy

We are now approaching the “peak” of oil

compared.

The Hydrogen Economy

20

The Hydrogen Economy

The barrier at the moment is twofold:

●

Technology

●

Price

Fuel cells work well in the lab, but as soon

as we start to take them and put them into

applications, we have to overcome practical

problems concerned with the technology. Our

hydrogen is very light, but it takes up an enormous volume—as a result, we have to look at ways to practically store the hydrogen for use in our

vehicles and other applications. Another is the

lifespan of fuel cells. Everything in this world Figure 2-21

Fuel cell technology trends in vehicles.

wears out sooner or later—the first combustion

engines would have been unreliable affairs—with

the technology being improved over time. With

platinum in fuel cells has being steadily reducing.

fuel cells, the technology is gradually improving.

This and other improvements to the technology will We are coming to the end of the initial “research mean that fuel cells will become cheaper—and

and development” phase, and we are starting to see as they do so, they will become more affordable

fuel cell technology with sufficient durability to be to you and I, finding more applications in the real able to enter commercial applications.

world.

Remember, there aren’t any moving parts with

Look at Figure 2-21, and you will see some of

hydrogen and fuel cells, so there isn’t anything the major technology trends for fuel cell technology mechanical to go wrong. Further improvements

in vehicles. You can see where the technology

need to be made, but step by step, the technology has come from, and where it is expected to go by is getting there. For vehicles in cold climates, 2010.

the cold-start performance of fuel cells has had We looked earlier at all the different possible

to improve, but again this shows signs of

methods of producing hydrogen—as the

improvement. Furthermore, manufacturers are

technology becomes cheaper and more attractive,

learning how to get more power from smaller and

we can envisage an energy economy based on

smaller fuel cells, and we will look at some of the renewable energy and clean energy sources

technology developments in this book. As fuel

generating electricity to produce hydrogen, with cells shrink, there is more room for other vehicle this hydrogen being used as a carrier for the clean components, and hydrogen storage, so we see

energy.

more applications for the technology. Aside from If you look at the Figure 2-22, you can see how

the technology, we need to look at the price. For a prospective hydrogen economy could work.

fuel cells that employ PEM technology, platinum, the catalyst, as we will see, is a very important part Of course, the advantage, as you can see, is that of the chain of events, making the reactions in the with clean energy and hydrogen, carbon dioxide

fuel cell happen. I don’t know if you’ve browsed and toxic pollutants are eliminated from the process, any jewellers recently, but platinum is pretty

with the only things entering and exiting to and expensive stuff. It really isn’t cheap! This is one of from the natural environment being water and

the barriers to the development of fuel cells

oxygen. We can see this in Figure 2-23, hydrogen commercially, but gradually the requirement for

and oxygen being the constituents of water.

21

Figure 2-22

Prospective hydrogen economy.

Work through the projects in this book and you

are working with has the potential to change the will begin to understand the technology, but all the world for the better. When thinking about the

time throughout your experimentation, relate the technology, reading articles in newspapers and

practical things that you are doing to what is

magazines, and talking to your friends and family, happening in the real world outside the lab. Think always keep a sound grasp of the issues—think

about and visualize how the technology that you

about how clean hydrogen can be a force for good, and when you hear of hydrogen being generated

from dirty sources, read between the lines and

think about whether the strategies proposed really Figure 2-23

Hydrogen, oxygen and water.

are environmentally sound.

The Hydrogen Economy

22

Chapter 3

Producing Hydrogen

using supposedly cheap nuclear energy to produce So where do we get

hydrogen—this would leave us with a toxic legacy of waste, and would negate many of the benefits of hydrogen from?

a clean hydrogen economy.

There are a number of ways that we can get our

hydrogen. It is a bit of a myth that hydrogen is a

“fuel”—it isn’t really as there is no such thing as a Biomass gasification

hydrogen mine or a hydrogen well—we can’t just

and reformation

dig it out of the ground or drill for it like oil or gas.

We need to produce it from another primary energy Biomass has proven itself as a relatively clean, source. In this chapter we are going to evaluate some near carbon-neutral source of energy. Agricultural of the different options for producing hydrogen.

waste, organic matter, wood, and other sources of biomass can be heated in a controlled atmosphere without the presence of oxygen. This yields a

Electrolysis

gas—synthesis gas—which is hydrogen-rich as

well as containing carbon monoxide and dioxide.

At school, you might have used a Hoffman

The carbon emissions from this source of energy

apparatus in science class. A Hoffman apparatus

are effectively neutral as the carbon dioxide was has a reservoir of water through which is passed an taken out of the atmosphere in the first place by the electric current. The electric current disassociates growing plants, however, carbon emissions in the the hydrogen from the oxygen in the water. The

production and distribution of biomass cannot be gas bubbles off from the electrodes and is collected ignored. There is also the possibility of sequestering in separate storage containers. It is observed that the carbon produced in the gasification process.

twice as much hydrogen is produced as oxygen.

This could effectively make biomass with hydrogen Taking a little bit of time to think about this, we extraction a “carbon-negative” fuel.

see that the chemical formula for water is H O—this 2

makes sense as we can see that there is twice as much hydrogen in water than oxygen.

Steam reformation

The hydrogen produced by the electrolysis

process is very pure—some fuel cells require a By combining high-temperature steam, and

very pure form of hydrogen so this is ideal.

methane, it is possible to extract hydrogen from The one disadvantage of electrolysis is that signifi-this fossil fuel. Although carbon dioxide is produced, cant amounts of electrical energy are needed for the location is centralized and it opens up the

the process. While this electricity can be generated possibilities for carbon sequestration (although using clean, green renewable energy, there are also bear in mind that this is an unproven technology many champions of a nuclear-hydrogen economy

with no demonstrated long-term safety). The process 23

Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.

is fairly cheap and inexpensive, and the heat produced can also be harnessed (known as cogeneration).

Clean coal?

Cogeneration provides us with lots of low-level

heat which could prove useful in local combined

There are vast tracts of coal throughout the world; heat and power schemes. This method does show a

however, coal is carbon-rich—burning it doesn’t

lot of promise, as it is currently an efficient cheap help global warming, and mining leaves scars on

technology that will work with the existing gas-

the landscape, which can last for generations. There distribution infrastructure; however, the carbon are, however, schemes afoot to look at gasifying emissions are impossible to ignore.

coal, extracting the carbon, and sequestering it.

Photoelectrolysis

Biologically produced

hydrogen

Photoelectrolysis is a relatively new unproven

technology. It involves using solar energy to stimulate There are a number of types of algae that use

a silicon junction similar to a photovoltaic cell, photosynthesis to convert solar energy into

with the distinction that instead of the energy

hydrogen. At the moment, these processes have

being converted to electricity, the silicon junction only been demonstrated on a small scale, but

acts directly on the water where electrolysis occurs.

research in this area is intense. It is expected that This technology shows promise, although much

great strides forward could be made in this area.

development must be done.

Project 1: Testing for Hydrogen

In this chapter, we are going to look at how to

to form water. The mixture is so explosive that just produce hydrogen. But once you’ve produced a

a single spark will make it explode! We can use

gas, how do you know what it is? Here we are

this property to help us test for its presence!

going to show a simple test for hydrogen.

There is a really simple, if a little loud, experiment.

Take a test tube of the gas which you believe to be hydrogen. Take a lighted splint of wood, and

introduce it into the container. The hydrogen should produce a loud squeaky pop as shown in Figure 3-1.

●

Test tube of gas under test

●

Wooden splint

●

Source of flame (e.g., candle)

Method

Hydrogen is a colorless, odorless gas, which is

Project 1: Testing for Hydrogen incredibly flammable, and combines with oxygen Figure 3-1

The test for hydrogen.

24

Project 1: Testing for Hydrogen

Chemical equation for hydrogen burning

(Equation 3-2):

Check out some videos of hydrogen explosions!!!

Look at the *.mpeg “hydrogen gas”

smartweed.olemiss.edu/nmgk12/curriculum/

curr_eighth.htm

State symbols

Here, a balloon full of hydrogen gas is lit!

pk014.k12.sd.us/chemistry/chapter%20two/

Here’s a handy reference of state symbols for

hydrogen_balloon.mpg

you. Remember, we use “l” for water, as it is a

liquid, but when something is dissolved in water, we use the symbol “(aq)” to represent “aqueous

One of the things that you can do is perform this solution.”

experiment near a piece of dry glass that has

(s)

=

solid

been chilled. You should see a frosting on the

(l)

=

liquid

glass—this frosting is water.

(g)

=

gas

(aq)

=

aqueous solution (dissolved in water)

Conclusion

Hydrogen is an explosive gas which will easily

ignite. Its flammability is one of the reasons that However, the astute mathematicians among you

we tend to use helium rather than hydrogen in

will quickly notice that things don’t quite add up.

novelty balloons. When hydrogen burns in air, it Looking at the amounts of hydrogen and oxygen, combines with oxygen and the product is water.

and the amounts of water produced, we appear to

have lost an oxygen atom somewhere, as there are We can write this as a word equation, as in

two atoms in one molecule of hydrogen. Therefore, Equation 3-1

we need to balance the equation. Two lots of Word equation for hydrogen burning (Equation 3.1): hydrogen will combine with one lot of oxygen to

make two lots of water. We can show this by

prefixing the “Hs” with a “2” to denote how many lots. This is shown in Equation 3-3.

We can see that hydrogen (in our test tube), and oxygen (in the air) combine to make water (the

Balanced chemical equation for hydrogen burning

frosting we saw on the glass).

(Equation 3-3):

If we want to be more sophisticated scientists,

we can take this word equation, and turn it into a

“chemical” equation, where we substitute the

words for chemical symbols. You can see in

You are going to come across balance equations

Equation 3-2, how “H” represents hydrogen, and

a lot in this book, so get to grips with them now.

“O” oxygen, with the chemical formula for water

Just remember that the big number in front shows H O. The symbols in brackets after each chemical how many lots of something there are, while the

2

denote the state of the chemical—solid, liquid, gas little subscript numbers show how many atoms

or dissolved in water.

there are of an element in each lot.

25

Project 2: Testing for Oxygen

that you suspect is oxygen right away (Step 3). If the gas is oxygen, the splint will quickly relight (Step 4).

●

Test tube of gas under test

Oxygen factoid

●

Wooden splint

●

Source of flame (e.g., candle)

Oxygen is pH neutral—it will not have any effect on litmus or indicator paper.

Method

Oxygen is the only gas that will support burning, Conclusion

so we can use this property to test for its presence.

To test for oxygen, take a test tube of the gas that We have seen how oxygen is essential for burning you want to test. The procedure for this test is to take place, and how burning is much easier in an illustrated in Figure 3-2

environment of pure oxygen, than in air, which Ensure that the end of the tube is either sealed or contains only 21% oxygen. This is evidenced by

immersed under water to prevent the gas from

the fact that the splint was only glowing in the air; escaping. Now, take a wooden splint and light it however, once inserted into the test tube of oxygen, (Step 1), blow it out (Step 2)—you should make

it began to burn brightly.

sure that the end of the splint glows—there might We will see later on, with our fuel cells, how

be a little wisp of smoke where it is smouldering, they operate much better with pure oxygen than but it should not be lit. Now dip it into the test tube with ordinary air.

Project 2: Testing for Oxygen Figure 3-2 The test for oxygen.

26

Project 3: Investigating Acid–Metal Reactions Project 3: Investigating Acid–Metal Reactions

There are a lot of different ways in which we can tube, swan neck tube, and flask as they are made produce hydrogen—these are going to be investigated from delicate glass.

in this chapter. One way of producing hydrogen,

As your reaction proceeds, use a timer and take

that is convenient using readily accessible

measurements of the volume of gas produced

materials in a laboratory, is by reacting an acid from the marks on the gas jar. Table 3-1 has been with metal. We are going to carry out this

provided for your convenience to note your

experiment to produce hydrogen, and then look at results down.

the chemistry that is taking place.

Conclusion

In a reaction involving a metal, the metal reacts by losing one or more electrons. This loss of electrons

●

is called “oxidization” by chemists; we can rank Thistle tube

metals according to how easily they oxidize; the

●

Swan neck tube

more easily they oxidize, the more active we say

●

Gas jar

that they are. The activity series for metals is

●

Bowl

shown in Figure 3-6. Hydrogen is shown on this

●

Timer

list as a reference point (although remember it is a nonmetal).

Method

At the same time as oxidization is taking place, it is always accompanied by a reduction of You are going to need to set up the apparatus as materials. Reduction is where a chemical gains shown in Figure 3-3. Be careful with the thistle electrons.

Figure 3-3

Producing hydrogen from acid and metal.

27

Table 3-1

Results from acid–metal reaction.

Time Hydrogen

produced

(seconds)

(cm3)

s

cm3

s

cm3

s

cm3

s

cm3

s

cm3

s

cm3

s

cm3

s

cm3

s

cm3

s

cm3

Figure 3-5

LEO the Lion will help you to remember

redox reactions by going GER.

Remember that oxidation is always accompanied

by reduction by using this simple little diagram.

A nice way to remember this is illustrated

So what’s happening here?

in Figure 3-5—this is a diagram you’ll come

into contact with later in this book! Remember

The hydrogen ions in the acid migrate to the metal the words LEO and GER using the simple

surface. Hydrogen ions in the acid accept electrons mnemonic—LEO the Lion goes GER—Loss

from the metal surface (and the metal surface gives Equals Oxidation, Gain Equals Reduction.

up electrons). The hydrogen ions combine with the electrons to make hydrogen atoms. Hydrogen atoms combine to give hydrogen molecules. Remember

from Chapter 2 that with hydrogen it takes

“two atoms to tango,” as it is diatomic. Metal ions hydrate and move away from the metal

surface.

You will notice that the production of hydrogen

gas eventually slows down and halts. As the reactants are consumed, the rate of hydrogen production

declines until all the reactants are used up—and then the reaction stops.

Taking it further

We are going to be hearing a lot in this book

about catalysts, so you might as well get used

Figure 3-4

Reduction, oxidization—like Starsky and

to them sooner rather than later! The production Project 3: Investigating Acid–Metal Reactions Hutch, you can’t have one without the other of hydrogen using zinc and sulfuric acid was

28

Project 4: Investigating the Activity of Metals really quite slow. If we wanted to increase the

Table 3-2

rate of reaction, a good way to do this would

Comparing the reactions with and without

be to use a catalyst, a chemical which facilitates catalysts.

the reaction and enables it to proceed at a

Time

With CuSO

Without CuSO

4

4

faster rate.

(seconds)

catalyst

catalyst

You can add a little copper (II) sulfate to

s

cm3

cm3

your zinc, and that will speed up the rate of

s

cm3

cm3

hydrogen production. You should already

s

cm3

cm3

have some data about the reaction rate of zinc.

s

cm3

cm3

Try adding a little catalyst, and see how it affects s

cm3

cm3

the rate of reaction. Note your results

s

cm3

cm3

in Table 3-2.

s

cm3

cm3

Compare the gas produced over time in Table 3-1

s

cm3

cm3

with Table 3-2 when the catalyst is added . . .

s

cm3

cm3

Interesting?

s

cm3

cm3

Project 4: Investigating the Activity of Metals When Producing Hydrogen

Method

As for the previous project plus different metal samples, e.g.:

●

Magnesium

●

Aluminum/aluminium

Potassium, sodium, lithium, and calcium all react

●

Zinc

violently with dilute sulfuric acid and dilute

●

Iron

hydrochloric acid. It is dangerous to put these

●

Tin

metals into an acid.

●

Lead

29

scraps that are all roughly the same size and have the same surface area. We are going to take

measurements with our timer and graduated gas

jar, and note them in Table 3-3.

We want to try and eliminate as many “stray

variables” as we possibly can, by ensuring that as Conclusion

many things are the same as possible. When

selecting your metal scraps, try and look for

What did you notice? You should have seen

scraps which are as near as possible the same

that some metals produced hydrogen gas

shape and size—as we want to try and ensure that very quickly, while some took their time to

the surface area available for reaction is the same produce gas—the metals reacted with the

for all the metal samples. (This has an impact on acid at different rates, i.e., their reactivity was the rate of reaction.)

different.

We can place metals into what is called a

We are going to repeat the previous project;

“reactivity series”—this allows us to classify how however, this time, we are going to use different vigorously different metals will react with air, metals each time. We want to pick a selection of water, and acids.

Table 3-3

Measure the activity of different metals.

Time

Aluminum/

(seconds)

Magnesium

aluminium

Zinc

Iron

Tin

Lead

s

cm3

cm3

cm3

cm3

cm3

cm3

s

cm3

cm3

cm3

cm3

cm3

cm3

s

cm3

cm3

cm3

cm3

cm3

cm3

s

cm3

cm3

cm3

cm3

cm3

cm3

s

cm3

cm3

cm3

cm3

cm3

cm3

s

cm3

cm3

cm3

cm3

cm3

cm3

s

cm3

cm3

cm3

cm3

cm3

cm3

s

cm3

cm3

cm3

cm3

cm3

cm3

s

cm3

cm3

cm3

cm3

cm3

cm3

s

cm3

cm3

cm3

cm3

cm3

cm3

Project 4: Investigating the Activity of Metals 30

Project 5: Investigating Water Electrolysis

Figure 3-6

The activity series of metals.

Project 5: Investigating Water Electrolysis

●

2 × carbon rods or 2 D cell zinc carbon batteries

●

9 V PP3 cell

●

Wire

●

Small tub

●

Baking soda

●

Gloves

Method

First of all, we need two carbon rods for our

electrodes. If you can get a couple of carbon rods, then great, but if not we can salvage some. We are not going to be using the D cell batteries as

batteries, we only want them for their rods inside!

Take a hacksaw (make sure you wear gloves for

Figure 3-7

Baking soda adds free ions.

31

Figure 3-8

Hydrogen at the cathode, oxygen at the anode.

this bit) and cut the metal casing of the battery.

The carbon rod is in the middle of the battery

So what’s happening here?

surrounded by electrolyte goo. You need to clean Figure 3-8 gives us a guide as to the chemical

the rod, disposing of the spent battery casing, and reactions that are taking place at the anode and the the goo, sensibly.

cathode. We can see that the positively charged ions, Once you have two clean rods, connect them to

the cations, move toward the cathode, while the

either terminal of a 9 V battery using short lengths negatively charged ions, the anions, move toward the of wire. Now immerse them in a solution of water anode. It is the power supply to the electrolyzer that in a small tub.

provides the energy for this movement to take place.

What happens? . . . Very little! The reason is

We can prove that the hydrogen and oxygen are

that ordinary water is a pretty poor conductor of coming from water by summing the chemical

electricity. We need to add some free ions to the reactions that are taking place at the anode and the solution.

cathode. This is shown in Figure 3-9.

This comes in the form of common baking soda.

Add a sprinkle to the solution, and see the bubbles form!

You can capture these bubbles with a test tube,

and test the respective anode and cathode to see if the bubbles are hydrogen or oxygen.

Conclusion

Free ions are necessary in a solution, for electrolysis to take place. In large electrolyzers, we might use a strong alkali-like potassium hydroxide, which is highly caustic.

Project 5: Investigating Water Electrolysis

Figure 3-9

The complete reaction.

32

Project 6: Making Fuel from Water

Project 6: Making Fuel from Water with a Hoffman Apparatus

Producing hydrogen from

renewables

●

Hoffman apparatus

If we want a sustainable energy economy, then we can produce hydrogen from renewable energy

Another way that we can perform electrolysis is

using the process of electrolysis.

with a piece of glassware called a Hoffman

apparatus—this contains a reservoir which we fill with water and something to provide free ions.

There are then two electrodes at the bottom of two PURE Energy Centre

large tubes, which have gas taps fitted to the top of them.

This is one of the things that the PURE Energy

As the water is electrolyzed, the hydrogen and

Centre in Shetland is hoping to demonstrate.

oxygen accumulate in the tubes.

The Shetland Islands have a fantastic wind

Hoffman apparatuses were used in the past as

resource, and the folks at PURE take this wind,

electricity meters when supplies were in D.C. It and turn it into hydrogen. They can then store

was possible to tell the amount of power that had passed through the Hoffman apparatus by looking

at the quantity of gas that had been produced.

Figure 3-10

Hoffman apparatus.

Figure 3-11

The PURE Energy Centre electrolyzer.

33

Figure 3-12

Two 6-kW proven wind turbines.

this as K-type cylinders, and utilize it in a

number of onsite applications, including a fuel

cell car, a hydrogen barbecue, and a 5-kW PEM

fuel cell.

They have a substantial electrolyzer (shown in

Figure 3-11)—this takes spare electricity which is not used for the—offices from the two 6-kW

proven wind turbines. As the power used to

generate the hydrogen is from renewables, no

climate-damaging carbon emissions are produced

in the process.

HARI–The Hydrogen and

Renewables Integration

Project

Another project, where electrolysis is being used to turn renewable energy into hydrogen, is at HARI, based at West Beacon Farm in Leicestershire, UK.

Again, HARI employ an electrolyzer, as seen in

Figure 3-13, to turn the electricity from the portfolio Figure 3-13

Project 6: Making Fuel from Water

The HARI electrolyzer. Image courtesy

of renewables into hydrogen gas.

Dr Rupert Gammon

34

Figure 3-14

System map of the Hydrogen and Renewables Integration Project. Image courtesy Dr Rupert Gammon.

35

r

e

t

a

W

m

o

r

f

l

e

u

F

g

n

i

k

a

M

:

6

t

c

e

j

o

r

P

HARI has a diverse array of onsite renewable

in the onsite stationary fuel cell, or in a proposed generating options, including wind turbines, solar hydrogen vehicle which is currently under

cells, and micro-hydro power. The spare electricity development.

is then converted into hydrogen, which can be used Project 6: Making Fuel from Water

36

Chapter 4

Hydrogen Storage

While the technological problems of developing fuel There are some inherent challenges in storing

cell technology to a stage where it is commercially hydrogen, due to the fact that as a molecule H is 2

viable are being solved one by one, there are still very small. Because of this, it can permeate many a number of other obstacles to the implementation materials that would at first glance seem suitable of a hydrogen economy.

materials for construction of hydrogen storage

In a future hydrogen economy, as well as looking vessels.

at methods to use hydrogen, e.g fuel cells, we

At atmospheric pressure, the size of tank needed also need effective ways to store and transport

to store a quantity of hydrogen, compared to a

hydrogen.

hydrocarbon fuel with the same amount of energy, The thing is that the present sources of energy

means that the hydrogen tank is many times larger that we use have a high energy density by volume than the conventional hydrocarbon tank, so any

at room temperature. An enormous amount of

weight saving as a result of using hydrogen is

energy can be stored in a gallon of petrol for the more than negated.

small size that it takes up. By contrast, the same As a result, there is a lot of investigation into quantity of hydrogen would take up a much larger storing hydrogen in so-called “metal hydrides.”

area—by its nature, it is a gas!

The easiest way to think of hydrides is like a

While hydrogen provides very favorable figures

“hydrogen sponge” which soaks up hydrogen,

when considering “energy per weight,” the figures but then releases it when heated. Metal hydride

for “energy per volume” do not compare as favorably storage cylinders are shown in Figure 4-21

to traditional hydrocarbon fuels.

(page 48).

Project 7: Using Hydrogen Storage Tanks with Desktop Fuel Cells

●

For our hydrogen experiments in this book, we will An empty storage tank is shown in Figure 4-1, and be using small lightweight cylinders.

a full tank in Figure 4-2.

37

Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.

negordyH

desserpmoCFigure 4-1 Empty hydrogen storage tank. Figure 4-2 Full hydrogen storage tank.

dna

waL

Project 8: Boyle’s Law and Compressed Hydrogen

s’

Storage

elyo

If you take a syringe, fill it with air, and put your B

finger firmly over the outlet to prevent any air from escaping, you have trapped a fixed quantity

:

of gas inside that syringe. Now, if you depress the 8

syringe plunger, you are changing the pressure

●

Syringe

t

inside the syringe. You will notice that as you push This is a very, very simple experiment, but it should c

further, it becomes harder to press—this is because help to firmly impress upon you Boyle’s Law.

e

the pressure of your fingers is acting against the Boyle said that if a fixed quantity of gas is at a j

volume of gas trapped inside the syringe. The

fixed temperature, its volume will be inversely

o

volume has decreased, but the pressure has

r proportional to its pressure.

increased.

P

38

Projec

There’s a really natty online simulator, which allows Check out:

t

you to experiment with Boyle’s Law from the comfort www.chem.iastate.edu/group/Greenbowe/sections/

of your web browser.

projectfolder/flashfiles/gaslaw/boyles_law_graph.html 9:

Explori

Project 9: Exploring Charles’ Law

ng

Charle

●

Balloon

put some boiling water in the bowl and immerse the s

●

Freezer/fridge

balloon to allow the boiling water to heat the

’

balloon, and thus the air inside the balloon. Then

●

Boiling water

take it out of the bowl and immediately measure it

●

Bowl

L

around the circumference. Then take the balloon, a

●

Measuring tape

and shut it in the fridge for several minutes. Take it w

The relationship between temperature and the

out and measure it again. Then, put the balloon in volume of a gas is a crucial one for us to understand the freezer and after several minutes, take it out and if we are interested in hydrogen storage, as it

measure it again.

allows us to do clever things to increase the volume You will see that at higher temperatures, the

of gas that we can store within a given space.

sealed volume of gas inside the balloon expands, Charles’ Law states: “At constant pressure, the

and the balloon increases in size, while, when the volume of a given mass of an ideal gas increases balloon is chilled, the balloon contracts. Cryogenic or decreases by the same factor as its temperature storage is one method proposed to store hydrogen increases or decreases.”

for use in fuel cell cars. When hydrogen is stored To demonstrate this, take an ordinary balloon and cryogenically, if we can get it to a temperature of tie it up so that the air cannot escape. We now have 20 Kelvin or –253° C, the gas changes phase into a a fixed volume of gas trapped inside the balloon.

liquid. Unfortunately, there is a loss of energy in Wrap the measuring tape around the balloon and

cooling the hydrogen, which equates to around

measure the circumference at the widest point. Now, 30% of the energy stored.

39

”ebutonaN

no Figure 4-3

b

Cryogenic hydrogen storage tank diagram.

raC You will see in the diagram in Figure 4-3 a

“ cryogenic storage tank of the kind we might find in cars of the future powered by hydrogen.

n

By cooling hydrogen, we can make it more

w

Online simulation is a good way of finding out

dense, and so a fixed volume of gas at room

O

about Charles’ Law. As with Boyle’s Law, there is temperature will take up a smaller space. This is another great online simulator at:

useful to us when looking at how to fit lots of

r

www.chem.iastate.edu/group/Greenbowe/sections/

hydrogen into a small vehicle fuel tank!

u

projectfolder/flashfiles/gaslaw/charles_law.html oY

gn

Project 10: Making Your Own “Carbon Nanotube”

ikaM

:01 ● Drinking straws/paper art straws

●

Hot melt glue gun (optional)

t ● Permanent marker

c ● Large round stickers

ej One of the ways in which we can store hydrogen The building block for our carbon nanotube is a

o is to adsorb it onto another material, as shown in buckyball. The chemical formula for the buckyball r Figure 4-4. Carbon nanotubes are one example of a is C60—this means that if we use two stickers, one P chemical with a high surface area.

either side of a straw to form a representation of a 40

Project

Figure 4-4

Diagram of hydrogen adsorbed onto a surface. The lighter colored smaller circles represent the hydrogen atoms, while the larger, darker circles represent the carbon atoms.

10

carbon atom, we will need 120 stickers to make

:

our C60.

Hydrogen storage

We represent carbon as being black, so add a

M

in hydrides

a

permanent marker for coloring the stickers. We

k

will be using straws for bonds.

i

Cut your straws into short lengths that are all the Metal hydrides

n

same. In order to produce a bond, hold the straws g

together in a junction, and then stick a sticker on Metal hydrides were discovered by accident at the either side of the join. Start by making a pentagon Y

Philips Laboratories in Eindhoven, The Netherlands shape, with five protruding pieces of straw. Then o

in 1969. The researchers found that a specific alloy u

begin to turn these additional lengths of straw into exposed to hydrogen gas would absorb the gas like r

hexagons. The completed buckyball will look like a chemical sponge. Like squeezing a sponge causes Figure 4-6.

it to release the water stored within, hydrides can be O

Extending our buckyball further, we can make a

“squeezed” by applying a little heat. The storage of w

carbon nanotube, which is a long tubular structure, water is therefore a reversible process. The

n

that can be used to adsorb hydrogen.

technology of metal hydrides has found widespread

“Carbon

Nanotube”

Figure 4-5

The materials you will need to make your

carbon nanotube.

Figure 4-6

The completed buckyball.

41

application in energy storage in the common

When hydrogen is required, the complex hydrides

“nickel metal hydride” batteries that can be found are heated, releasing the hydrogen.

in many of today’s mobile phones and portable

While complex hydrides offer the benefit of

electronic devices, but in a hydrogen economy

having a low volume, and offer vehicle makers the could these substances find other energy storage opportunity to re-charge on-board, they have the applications—in storing hydrogen? One of the

disadvantage that they have a relatively high weight advantages of metal hydrides is that they can store compared to some other solutions, require high

a very high density of hydrogen at relatively low temperatures for operation, and can suffer from

pressures; however, this comes at the penalty of issues with providing an adequate fuel flow for

mass. Metal hydrides can be seen in Figures 4-8

some applications. As a technology, they can still and 4-9. See how the hydrogen (small circles) is be considered to be in “development.” An example absorbed in the gaps between the large circles

of the structure of a complex hydride can be seen which represent the metal atoms.

in Figures 4-10 and 4-11. In Figure 4-10 the small circles represent hydrogen gas, the large dark

Complex hydrides

circles represent metal atoms, and the light colored dark circles represent additive atoms included to Complex hydrides are more sophisticated than metal improve the performance of the complex hydride.

hydrides, and incorporate additional chemicals to improve the performance of the hydride.

Chemical hydrides

s

Complex hydrides store hydrogen by “locking it

e up” chemically with metals and other substances Chemical hydrides store hydrogen in their

d added to improve the performance of the hydride.

chemical structure—releasing it when exposed to a irdyH

ni

egarotS

negordyHFigure 4-7 Hydrogen storage in carbon nanotubes.

42

Hydrogen

Figure 4-8

S

2D representation of metal hydride.

torage

in

Hydrides

Figure 4-9

3D representation of metal hydride.

Figure 4-10

2D representation of complex hydride.

43

Figure 4-12

2D representation of chemical hydride.

Figure 4-11

3D representation of complex hydride.

sedirdy catalyst, we are going to experiment with chemical their volumetric density and density by mass.

H hydrides later in this book using the H-Gen reactor.

There is also a comparison to some other hydrogen Chemical hydrides can be either liquids or solids.

storage methods.

n They have the potential to offer a low weight and i

For hydrogen to become of practical use in

volume solution—the fact that chemical hydrides

automotive applications, we need to improve our

can be distributed in liquid form opens up the

e

ability to store it. We can see how current

g opportunity of using the existing infrastructure to approaches to storing hydrogen compare to the

a distribute the hydrides. The disadvantage of using energy density of a tank of gasoline in Figure 4-14.

r chemical hydrides is that the spent hydride would We can also see the Department of Energy’s goal

o need to be stored on board the vehicle, and for hydrogen storage, which gives us a realistic t exchanged for fresh reprocessed hydride.

idea of how much the technology is likely to

S Reprocessing hydrides requires infrastructure, improve.

technology, and equipment. Figure 4-12 is a

n

While we probably will not be able to come

representation of a chemical hydride. See how

e

close to the energy density of gasoline, this is not other chemicals act as a “carrier” for the hydrogen.

g

necessarily a problem, as we can circumvent

o

There are such a wide range of hydride storage

issues of energy storage by designing vehicles

r compounds—the array is bewildering! Looking at to be lighter, more aerodynamic, and more fuel-d Figure 4-13 gives you the chemical formulas for efficient, so that they use less energy in the

y some hydrides that have been discovered, plotting first place.

H

44

Hydrogen

Storage

in

Hydri

Figure 4-13

A range of hydrides and their storage capacities.

des

Figure 4-14

Hydrogen storage roadmap.

45

Project 11: Generating Hydrogen Using the H-Gen

neG-H

eht ● H-Gen

●

Sodium borohydride

g

A small container of sodium borohydride, like

n

Figure 4-16

The chemical structure of sodium

i that shown in Figure 4-15, will be more than borohydride.

s sufficient to produce much hydrogen from the U H-Gen for experimentation.

We see, looking at the chemical structure of

need anything special—ordinary tap water will do n sodium borohydride in Figure 4-16, that for every for this one.

e sodium and boron atom, there are four atoms of g

Add about a tenth of a gram of sodium

hydrogen.

o

borohydride. You can use a spatula, for example, r

the item in Figure 4-17. At this point, you won’t d Method

see a thing. Now drop the catalyst into the water.

y

Immediately, you should see small bubbles.

H Take the H-Gen hydrogen generator, and half fill it The end product of this reaction is sodium

with water; it will only take about 15 ml. You don’t g

borate: NaBO . We generate such small quantities 2

n

that there is not a problem getting rid of it down i

the sink.

tareneG

:11

tcejor

Figure 4-17

Spatula used to measure the quantity of

P Figure 4-15 A container of sodium borohydride.

sodium borohydride.

46

Project

12:

Ch

Figure 4-19

Hydrogen produced by the H-Gen

a

Figure 4-18

Diagram showing the H-Gen producing

powering a mini PEM fuel cell.

n

hydrogen gas.

g

hydrides with hydrogen gas. While chemical

i

hydrides have the advantage of being lightweight n

Conclusion

and low-volume, the materials need to be removed g

from the vehicle for regeneration, and the

This simple experiment shows us that there are

associated technologies and infrastructure could t

other ways of generating useful quantities of

prove expensive.

h

hydrogen besides using the electrolysis of water.

e

The next question might be “so why don’t we just use loads of sodium borohydrate to solve our

H

energy crisis? ” Well, we could, as certainly

-

research is being done into vehicles using chemical G

hydrides to power them (see Figure 13-39 for more e

When cleaning the H-Gen, be very sure not to

n

about how this would work). However, chemical

lose the reactors. It is these reactors that make up hydride powered vehicles would require a different the bulk of the cost of the H-Gen unit. If they

R

infrastructure again for refueling—as equipment

break, do not discard them, as they will still work.

a

would be needed to “recharge” the chemical

te

o

Project 12: Changing the H-Gen Rate of Reaction

f

Reac

Introduction

ti

The H-Gen produces enough hydrogen to power

●

H-Gen

o

most fuel cells that produce up to 1.5 W of power.

●

n

Timer

For some, slightly larger, fuel cells, we might need

●

Kettle

more hydrogen, or we might want to produce

●

Ice cubes

hydrogen at a higher rate.

47

In this experiment, we are going to look at the

factors that affect the rate of hydrogen production n in the H-Gen unit.

o

In order to do this experiment, we will need a

i means of regulating the temperature of our water.

t A kettle and ice cubes provide a sound way of c

making varying temperatures of water between

ae 0° C (32° F) and 100° C (212° F).

R

Metal hydrides

fo Using the apparatus shown in Figure 4-20, we can experiment with hydrides, changing the temperature e

of the cylinders on each side, causing the pressure ta on each side to change. The valve in the middle R can be opened or closed to allow the pressure to equalize, or build up in one side.

n

Figure 4-21

Example 1 of metal hydride cylinders.

Figures 4-21 and 4-22 are examples of the

e types of hydride cylinder you could use to store G-hydrogen in for experimentation and work with

H

small-scale fuel cells.

Metal hydrides are one option for storing

e

hydrogen for transport applications; however, the h

technology will need to develop further if it is to t

provide the range that consumers want.

g

At the PURE Energy Centre, they have developed

n

an electric car with hydrogen hybrid drive. A hydride i

cylinder is used to store hydrogen for the vehicle, g

and it is recharged from a supply stored in

n

compressed hydrogen tanks, which we will look

a

at next.

hC

:21

tcejor Figure 4-20 Apparatus for experimenting with metal P hydrides.

Figure 4-22

Example 2 of metal hydride cylinder.

48

Project

12:

Changing

t

Figure 4-23

Figure 4-24

h

PURE Energy Centre fuel cell car fitted

Compressed hydrogen storage at the

e

with metal hydride hydrogen storage.

PURE Energy Centre.

H-

Compressed hydrogen storage

Gen

One of the simplest ways to store hydrogen is to keep it as pressurized gas. Unfortunately, this

R

does have the disadvantage that the gas occupies a a

large volume; however, it is a relatively simple t

approach.

e

Unfortunately, compressing gas requires some

energy, so as fuel cell scientists, we need to be o

aware that the “work” required to compress our

f

hydrogen is going to require some additional

R

energy input, which may affect the economics of

e

running our system.

a

The PURE and HARI projects both use

c

compressed hydrogen storage, in order to store the t

hydrogen they produce from spare renewable

i

energy.

on

At the PURE Centre, the electrolyzer works at a

relatively high pressure, from which it enters the Figure 4-25

Hydrogen compressor at HARI project,

hydrogen storage cylinders.

West Beacon Farm. Image courtesy Dr Rupert Gammon.

49

noitcaeR

fo

etaR

n Figure 4-26 Hydrogen storage at the HARI project, West Beacon Farm. Image courtesy Dr Rupert Gammon.

eG-H At the HARI project, a slightly different By storing hydrogen in this way, the supply of

approach is used, whereby the hydrogen is first

energy can be matched with demand, and spare

e compressed, using the hydrogen compressor shown energy can be used to produce transport fuel.

h in Figure 4-25 and then stored in the hydrogen t cylinders shown in Figure 4-26.

gnignahC

:21

tcejorP

50

Chapter 5

Platinum Fuel Cells

Introduction

instead with a mixture of water and common

table salt.

We saw that Grove’s original fuel cells employed From this simple experiment, you will learn the

platinum electrodes. You can recreate Grove’s

basics of fuel cell technology, which will act as a original gas battery by using a couple of lengths of springboard to allow you to progress onto bigger platinum wire.

and better technologies.

We are going to omit the dangerous sulfuric acid used in Grove’s original experiments, replacing it Project 13: Build Your Own Platinum Fuel Cell

Method

Making the platinum fuel cell

Fill a tumbler with water, and put the tiniest

●

A small tumbler full of distilled water and a pinch sprinkle of salt in it. Common household salt, such of salt

as shown in Figure 5-1, is ideal.

●

Voltmeter

In order to construct the fuel cell, you will need

●

Battery

to cut the platinum wire in half, and wrap it around

●

Connection leads

a thin cylindrical object, such as the probe of a

●

Length of platinum wire

multimeter or a biro refill. This gives us a spiral

●

Battery

that we can immerse in the water, and gives us a large surface area exposed to the water.

Two tightly wound coils of wire, such as those

shown in Figure 5-2, should result.

Now, put the two coils of wire at opposite sides of the glass, and using the crocodile clips on your connection leads, clip the wire to the side of the An old film canister makes a perfect little

glass, immersing it in the water. See Figure 5-3.

container for our platinum fuel cell.

The crocodile clips must provide good electrical contact between the platinum wire and the clip

51

Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.

Figure 5-3

Wires positioned on either side of the

beaker.

itself, as well as supporting the wire and holding it in place (Figure 5-4).

The wire should be covered by the salt water,

but the water should not touch the crocodile clips.

The crocodile clips are made from metal that

Figure 5-1

Common table salt.

is “reactive” and so could form a galvanic cell

(a battery), whereas the platinum will not react, and so any power being produced is as a result of the hydrogen and oxygen, not the reaction of the metals.

Figure 5-4

Close-up of the wires clipped snugly to

Project 13: Build Your Own Platinum Fuel Cell Figure 5-2 Two small coils of platinum wire.

the inside of the container.

52

Project 13: Build Your Own Platinum Fuel Cell Making a fair test

We want to check that the voltage that we are producing from our platinum fuel cell really is as a result of the hydrogen and oxygen produced, not as a result of any galvanic circuit. Therefore, we must measure the voltage between the platinum electrodes immersed in the salt water solution.

Now, using the most sensitive DC voltage setting of your voltmeter, measure the potential across the two electrodes.

It should register zero.

Generating a little hydrogen

(and oxygen)

We are now going to charge our platinum fuel cell, Figure 5-6

connecting the wires to a battery will cause gas to A picture of the completed setup for

electrolysis.

be evolved at the two electrodes. Connect three of the 2 V lead acid batteries in series. We read about this reaction—electrolysis—in Chapter 3.

As can been seen in Figure 5-8, a voltage will

A schematic diagram of the setup can be seen in

register on your meter. Your meter should be set to Figure 5-5, and a picture of the completed setup one of the most sensitive DC voltage settings.

can be seen in Figure 5-6.

Observe the two electrodes during and after

Now, take a voltmeter and connect it across the

electrolysis, and during the process of voltage being two electrodes, as shown in Figure 5-7.

generated. What do you notice about the amount of bubbles being formed at the two electrodes? Are

there more at one than at the other? Take a look at Figure 5-5

Schematic for generating hydrogen and

Figure 5-7

Schematic of voltmeter connected across

oxygen.

the platinum electrodes.

53

Figure 5-8

The platinum fuel cell generating electricity.

Figures 5-9 and 5-10, which are a close-up view

of the two electrodes that were taken during

electrolysis.

As we saw in the experiments on electrolysis,

the positively charged ions—which we call the

cations—go to the cathode, whereas the negatively charged ions, the anions, migrate toward the anode.

When they reach the anode and cathode, they “give up” their charge to the electrode, completing the circuit.

Once we have formed a small amount of gas,

this gas sticks to the electrode, a very primitive form of storage—certainly not enough storage to

do anything useful on a large scale.

Once we have produced hydrogen and oxygen

on the electrodes of the fuel cell, we can then

“release” this imbalance of charge by creating a circuit with the voltmeter.

Then the platinum acts as a catalyst. Its catalytic action allows the hydrogen ions to break up into electrons, which flow through the electrode and the Project 13: Build Your Own Platinum Fuel Cell Figure 5-9a

Close-up of the the oxygen electrode.

54

Project 13: Build Your Own Platinum Fuel Cell Proving that the catalytic

effect of platinum

is required

Platinum is unique because of its catalytic properties.

This is why they use it in car “catalytic converters,”

as well as in many industrial applications.

Unfortunately, it is also very expensive. If only we could use something other than platinum . . . Well, tough! At the moment, we can’t! Try using two

other wires of the same metal and, while you will see electrolysis take place, you will not see any significant voltage when connecting the meter.

Figure 5-9b

Close-up of the hydrogen electrode.

circuit. At the anode, the oxygen bubbles which

If you want to take platinum fuel cells further: cling to the electrode receive electrons from the There are some online movies at:

electrode, and combine with the hydrogen ions that www.geocities.com/fuelcellkit/pics/FCK1.mpg

are in the water to produce water.

www.geocities.com/fuelcellkit/pics/FCK2.mpg

This process is illustrated in Figure 5-10.

www.geocities.com/fuelcellkit/pics/FCK3.mpg

Here is another nice site to check out for platinum fuel cells:

www.scitoys.com/scitoys/scitoys/echem/fuel_cell/

fuel_cell.html

Taking it further

Take a look at Grove’s original gas battery in

Figure 5-11. Grove used multiple cells in his

battery to produce higher voltage. How could you Figure 5-10

Platinum fuel cell electrochemistry.

make a platinum fuel cell with multiple cells? As a Hydrogen is produced at the cathode and oxygen hint, you can obtain safety test tubes, often in at the anode.

chemistry kits for a younger audience. These can 55

Figure 5-11

Grove’s gas battery.

be drilled safely, unlike glass, allowing you

“stacks.” Keep this in mind, and think back to

to experiment and make multiple cells. Later in

Grove’s gas battery when you encounter this

this book, we are going to look at fuel cell

information.

Project 13: Build Your Own Platinum Fuel Cell 56

Chapter 6

Alkaline Fuel Cells

We saw in Chapter 1 how alkaline fuel cells played an important role in the early development of fuel cells, having been developed by Francis Bacon at Cambridge University. In fact, because of their

inventor, you may hear them referred to as “Bacon cells.” As you will know from reading this chapter, alkaline fuel cells, such as those shown in Figure 6-1, were used in early space missions, and are a very well-developed fuel-cell technology.

One of the advantages of a fuel cell in space is that you already have the hydrogen and oxygen,

Figure 6-2

The chemistry of alkaline fuel cells.

and the water is pretty useful for astronauts to drink too!

The chemistry of an alkaline fuel cell differs

the cathode—which means that the water is

slightly from some of the other fuel cells in this produced on the “hydrogen side” rather than the

book. In a PEM fuel cell, it is the protons which

“oxygen side.”

are exchanged through the membrane, while the

If we look at the pairs of chemical reactions

electrons complete the circuit. In an alkaline fuel which are taking place at each electrode (see

cell, it is “hydroxy ions” that make the journey Figure 6-2), we see that:

from electrode to electrode, and the water, which is a product of the combination of hydrogen and

At the anode

oxygen, is produced at the anode, rather than

Hydrogen is oxidized, producing electrons in the process.

At the cathode

Oxygen is reduced, producing “hydroxide ions,”

which migrate across the electrolyte of the alkaline fuel cell.

So reduction and oxidization are happening

at the same time . . . Remember LEO the Lion

going GER?

If you want to look at this in terms of a diagram, Figure 6-1

An early AFC used in the space program.

Figure 6-4 shows the layout of an alkaline fuel

Image courtesy NASA.

cell. Here we can see how the “exhaust” from the 57

Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.

Figure 6-3

Reduction and oxidization (remember LEO the Lion?).

Figure 6-4

Diagrammatic representation of an alkaline fuel cell.

Alkaline Fuel Cells Figure 6-5 The chemical reactions taking place inside an alkaline fuel cell.

58

Project 14: Electricity with Alkaline Fuel Cells fuel cell comes from the anode side of the fuel

how electrons are flowing from the anode, to the cell, rather than the cathode.

cathode, via the circuit. Looking at the cathode, we If we now superimpose the chemical reactions

can see how electrons and oxygen form hydroxyl

that are taking place onto this diagram, we get

ions, which flow across the electrolyte of the

Figure 6-5.

alkaline fuel cell, and recombine with the hydrogen We can see that the hydrogen enters to the top

protons to make H O, or water, which is the output 2

right, the oxygen to the top left, and we can see from the fuel cell.

Project 14: Making Electricity with Alkaline Fuel Cells Now, we are going to get to grips with using a real can only seat properly when they are correctly

alkaline fuel cell. To begin with, we are just going lined up.

to check that we can produce some power from our The anode of the mini alkaline fuel cell is the

fuel cell, and as the chapter goes on, we are going clear outer tub, shown in Figure 6-7.

to perform some simple experiments which will

If you look inside the tub, you will see a square enable us to learn more about the performance of affixed to the bottom of the tub—this is the anode alkaline fuel cells.

electrode, shown in Figure 6-8, and it connects to the anode terminal, which employs a 4-mm banana

plug, also shown in Figure 6-8.

The red plastic piece which came supplied with

the tub is shown in Figure 6-9. This is the mini fuel cell cathode assembly.

●

Alkaline mini fuel cell (Fuel Cell Store P/N:

You will notice that there is a similar piece of 530709)

material on the bottom of the red molding—this is

●

Potassium hydroxide (Fuel Cell Store P/N: 500200) the cathode electrode, as indicated in Figure 6-10.

●

Sodium borohydride (Fuel Cell Store P/N: 560109) The cathode comes with a similar 4-mm banana

●

Multimeter (Fuel Cell Store P/N: 596007)

socket, as shown also in Figure 6-10.

You can see a cross-sectional view of the fuel

cell in Figure 6-11. Notice that the two electrodes are opposite each other.

Thinking about the diagram shown earlier in

Figure 6-5, it should become easy to relate the

●

components of the mini alkaline fuel cell to the Small scoop

diagram. We can envisage the oxygen being drawn

●

Accurate scales

from the center of the fuel cell. However, you will

●

1 liter graduated jug

notice that there is no “hydrogen input tube.” This fuel cell gets its hydrogen fuel from chemicals

The assembled fuel cell, as delivered, should

dissolved in the electrolyte solution.

look something like Figure 6-6. You will notice

that the sockets, and cutouts in the plastic on the You will remember Chapter 4, where we used

top of the fuel cell, ensure that the two components sodium borohydride. Well, we are going to use it 59

Figure 6-6

The assembled mini alkaline fuel cell.

Figure 6-8

Note the location of the anode electrode

Figure 6-7

The mini alkaline fuel cell anode.

and terminal.

Project 14: Electricity with Alkaline Fuel Cells 60

Project 14: Electricity with Alkaline Fuel Cells Figure 6-11

Cross-sectional view of the mini alkaline

fuel cell.

Figure 6-9

The mini alkaline fuel cell cathode

assembly.

again as the source of fuel for our alkaline fuel cell.

You will need a small bottle of sodium boro-

If you are going to order sodium borohydride

hydride, like that in Figure 6-12.

through the post, many countries and states will require that you specify “hazardous materials

Later in this chapter, we are going to experiment postage,” which costs a little extra—be mindful of with some different “hydrogen carriers,” but for this when thinking about how much to order!

the moment, let’s go with what works well! You

will also need a small scoop for the sodium

borohydride.

Figure 6-10

Note the location of the cathode

Figure 6-12

Sodium borohydride, the source of

electrode and terminal.

hydrogen for our AFC.

61

Figure 6-13

Very small scoop, suitable for measuring

sodium borohydride.

Now, remember this is an “alkaline fuel cell,”

but “Where is the alkaline?” I hear you shout—well, Figure 6-15

Do not fill past this line!

it comes in the form of potassium hydroxide.

Figure 6-14 shows a bag of potassium hydroxide.

If you can’t get any of this stuff, then have a play We need to take about 65 cm3 of this to fill our around with some alternative alkalis, as shown in fuel cell.

the later experiments—performance might be a bit impaired, but it will prove the principle.

Now, we need to prepare a 1 M solution of this.

To do this, we need 56 grams of potassium

hydroxide in a measuring jug—56.10564 g/mol—

to which we will add water to make 1 liter.

If you’ve got 65 cm3 of the alkaline electrolyte solution, then it should all work out just fine—but whatever you do, do not fill past the line shown in Figure 6-15. You may need to top up a little bit to reach the line—this is fine, but do not go above it.

Don’t be alarmed, don’t be scared! If the liquid starts looking a bit black the first time you use the fuel cell, it is only a little bit of the carbon coming out of the cloth electrodes—don’t panic,

as this is normal.

Project 14: Electricity with Alkaline Fuel Cells Figure 6-14 Potassium hydroxide.

62

Project 15: Plotting the IV Characteristics of an AFC

Figure 6-17

Schematic for connecting the AFC to the

voltmeter.

Now, simply and straightforwardly, we are going

to put the cathode into the anode pot, and connect the fuel cell to a voltmeter. The setup will look like Figure 6-16, and the schematic is as simple as

Figure 6-16

The alkaline fuel cell connected to the

Figure 6-17.

voltmeter.

There really is nothing to it!

Add a pinch of the sodium borohydride, using

Your alkaline fuel cell should be producing

the small measuring scoop. You don’t need very

power, so set your meter to its most sensitive D.C.

much at all.

voltage setting and look at the reading!

Project 15: Plotting the IV Characteristics of an AFC

●

Alkaline mini fuel cell (Fuel Cell Store P/N:

●

Small scoop

530709)

●

Accurate scales

●

Potassium hydroxide (Fuel Cell Store P/N: 500200)

●

1 liter graduated jug

●

Sodium borohydride (Fuel Cell Store P/N: 560109) In this experiment, we will be setting up the

●

2 × multimeter (Fuel Cell Store P/N: 596007)

alkaline fuel cell exactly as we did in the last

●

Variable resistance

experiment; however, the step that will differ is 63

how we set up the multimeters to monitor the fuel cell’s performance. We will be connecting the fuel cell to a variable load—a variable resistor, and measuring the voltage across the fuel cell, and the current flowing through the load. Each time we

change the variable resistance, we need to disconnect the resistor, and quickly take a reading of the

resistance of the resistor, write it down! Don’t try and remember—it never works. Then, quickly

connect it back in the circuit, read the current and voltage, and write them down too!

In fact, I’m so adamant that writing it down is a good idea that I have even provided you with a

natty little table to write them in (Table 6-1)!

We are going to be plotting a current-voltage

curve for our alkaline fuel cell. To do this, we first need to obtain a series of values. So, you’re going to have to connect everything up as shown in

Figure 6-18. A schematic is shown in Figure 6-19.

Figure 6-18

The alkaline fuel cell measurement

Now, you have two options. The simple way is

setup.

to use a pen and paper. I’ve provided you with a blank graph, so you can give it a go with plotting your points. This is Figure 6-20.

Table 6-1

You will notice that the voltage is across the

Record resistance, current and voltage for your

x-axis of the graph. There is a lesson here—my alkaline fuel cell.

science teacher, Mr Kaufman, used to patrol the

Resistance (R)

Voltage (V)

Current (I)

room, carefully scrutinizing everyone’s neatly

⍀ Ohms

V Volts

A Amps

plotted graphs. There was deadly silence.

Suddenly, the silence would be broken:

⍀

V

A

“Control your bottom, young man,” he’d shout at

⍀

V

A

some unfortunate pupil. It was nothing to do

⍀

V

A

with what the student had eaten for breakfast—it

⍀

V

A

was more to do with the graphs! We always

⍀

V

A

put the thing that we can control at the bottom

⍀

V

A

of the graph. In this case, we are plotting

⍀

V

A

voltage and current, but we are “controlling” the

⍀

V

A

voltage, by using the variable resistor. So, when

⍀

V

A

plotting graphs, remember to “control your

bottom.”

Project 15: Plotting the IV Characteristics of an AFC

64

Project 15: Plotting the IV Characteristics of an AFC

Figure 6-19

Schematic diagram for the alkaline fuel cell measurement setup.

Figure 6-20

Blank graph for plotting IV characteristic

Figure 6-21

Completed graph plotting IV

of the alkaline fuel cell.

characteristic of the alkaline fuel cell.

65

Project 16: Plotting the Power Curve of an AFC

Table 6-2

Voltage, current and power for an alkaline fuel cell Voltage (V)

Current (I)

Power (P)

V Volts

A Amps

W Watts

●

Alkaline mini fuel cell (Fuel Cell Store P/N:

V

A

W

530709)

V

A

W

●

Potassium hydroxide (Fuel Cell Store P/N: 500200) V

A

W

V

A

W

●

Sodium borohydride (Fuel Cell Store P/N: 560109) V

A

W

●

2 × multimeter (Fuel Cell Store P/N: 596007)

V

A

W

●

Variable resistance

We are now going to plot the power curve of our

AFC. You’re provided with a blank set of axes in

●

Small scoop

Figure 6-22 (although bear in mind that as power

●

Accurate scales

changes dramatically as a result of alkaline and

●

1 liter graduated jug

fuel, you may need to redraw different axes with Great news! We are going to take the data from

different scales.) An example of how your power

the last experiment, and process it in a different curve might look is shown in Figure 6-23.

way to learn something else about the characteristics of the alkaline fuel cell.

If you haven’t carried out the previous experiment, I’d suggest you do so now, as we are going to need the data.

Transfer the data about voltage and current to

Table 6-2.

Once you have taken your readings and written

down your series of values, you can compute the

power column in the table. This is really simple.

To find D.C. power, you simply take the voltage

(in volts), and multiply it by the current (in amps), which gives you watts.

Figure 6-22

Blank power curve graph.

Project 16: Plotting the Power Curve of an AFC

66

Project 17: Different Alkaline Electrolytes

Figure 6-23

Example power curve graph.

Project 17: Comparing the Performance of Different Alkaline Electrolytes

for both experiments. For the first experiment, use the sodium hydroxide as the alkali. Prepare a 1 M

solution—you will need to add 40 g of sodium

hydroxide to a beaker, to which you add a liter of water. Use about 65 ml of this to top the fuel cell

●

Alkaline mini fuel cell (Fuel Cell Store P/N:

530709)

up to the fill line. Set the experiment up using the diagram in Figure 6-19. Set the resistor to a value

●

Potassium hydroxide (Fuel Cell Store P/N: 500200) where it registers a flow of current. Wait for the

●

Sodium hydroxide (drain cleaner)

current to stabilize. Note the voltage and current

●

Sodium borohydride (Fuel Cell Store P/N: 560109) produced. Now, repeat the experiment with a 1 M

●

Multimeter (Fuel Cell Store P/N: 596007)

solution of potassium hydroxide.

●

Variable resistor

You can use Table 6-3 to note your results.

In this experiment, we are going to compare the

performance of the alkaline fuel cell using two

Table 6-3

Comparison of AFC alkaline solutions.

different alkaline solutions—potassium hydroxide (which we have been using in the other experiments), Voltage (V)

Current (A)

and sodium hydroxide, which is also known as

NAOH

drain cleaner. In order to make a fair experiment, KOH

we are going to use sodium borohydride as the fuel 67

Project 18: Comparing the Performance of Different

“Hydrogen Carriers”

we are going to thoroughly clean out our fuel cell, and use a methanol solution instead; the other

solution that I recommend testing is ethanol, to compare the performance with methanol. Then you

can try and think of some other likely hydrogen

●

Alkaline mini fuel cell (Fuel Cell Store

carriers, a good suggestion being to crack open the P/N: 530709)

drinks cabinet—no, not for reckless personal

●

Potassium hydroxide (Fuel Cell Store P/N: 500200) consumption, but to power our fuel cell. Drinks

●

Sodium borohydride (Fuel Cell Store P/N: 560109) with a high alcohol content will produce power in

●

Methanol

our fuel cell.

●

Ethanol

●

A well-stocked drinks cabinet

●

Multimeter (Fuel Cell Store P/N: 596007)

Table 6-4

In this experiment, we are going to compare the

Comparison of different hydrogen carriers.

performance of different liquids that we can use as Voltage (V)

Current (A)

hydrogen carriers in our alkaline fuel cell. We are going to use the same potassium hydroxide 1 M

CH O

4

solution in both of our experiments. However,

CH O

6

we are going to run one experiment using the

NaBH4

sodium borohydride (if you did the last couple of experiments, you could use the same results). Then Project 19: Investigating How Temperature Affects Alkaline Fuel Cell Performance

●

Kettle

●

Ice cubes

●

Thermometer

●

Methanol

●

Alkaline mini fuel cell (Fuel Cell Store P/N:

In this experiment, we are going to change the

530709)

temperature of our alkaline fuel cell and see how it

●

Potassium hydroxide (Fuel Cell Store P/N: 500200) affects the performance of the fuel cell. You need a Project 18: Different “Hydrogen Carriers” ● Multimeter (Fuel Cell Store P/N: 596007) large bowl in which you can immerse the bottom of 68

Project 19: Alkaline Fuel Cell Performance

the fuel cell. We are going to use ice and hot water to Table 6-5

control the temperature that the fuel cell is exposed Effect of temperature on AFC performance.

to. We are going to create a range of temperatures Temperature

Voltage (V)

between 0° C (32° F) and 50° C (122° F).

°C/°F

V

°C/°F

V

°C/°F

V

°C/°F

V

°C/°F

V

You should not heat the fuel cell above 50° C

(122° F) as permanent damage to your fuel cell

could result.

temperature reading and note the temperature in

We are going to use 10 ml of methanol solution

Table 6-5. Cross out either Celsius or Fahrenheit, for fuel. First of all, stick the bottle of methanol in depending on what scale you are using. Once

with your ice cubes to prechill the solution.

you have taken your readings, plot them in

Connect the ammeter directly across the terminals Figure 6-25.

of the fuel cell. Use the thermometer to take a

Figure 6-25

Performance graph of AFC at different

Figure 6-24

Insert the thermometer here.

temperatures.

69

Project 20: Investigating AFC Poisoning

In this experiment, we are going to look at the

poisoning of AFC electrolytes. One of the problems with AFC fuel cells is that they are very sensitive to impurities in the air that is supplied to them, as aqueous alkaline solutions will absorb carbon

●

Vinegar

dioxide.

●

Bicarbonate of soda

In this experiment, we are going to look at how

●

Limewater

an aqueous alkaline solution can be “poisoned” by carbon dioxide, but first we need to make some

carbon dioxide.

We are going to make our CO by reacting

2

vinegar with bicarbonate of soda. It will fizz for a bit and produce a gas, which is our “carbon

dioxide” that we are going to use to poison our

●

Erlenmeyer flask (side tap)

electrolyte.

●

Thistle tube with bung

Our alkaline electrolyte that we are going to

●

Swan neck tube

poison is limewater, which is saturated calcium

●

Dish

hydroxide solution.

Figure 6-26

The alkaline limewater reacts with the carbon dioxide.

Project 20: Investigating AFC Poisoning

70

Project 21: Investigating the AFC’s Need for Oxygen Project 21: Investigating the AFC’s Need for Oxygen

●

Alkaline mini fuel cell (Fuel Cell Store P/N:

530709)

●

Potassium hydroxide (Fuel Cell Store P/N: 500200)

●

Sodium borohydride (Fuel Cell Store P/N: 560109)

●

Multimeter (Fuel Cell Store P/N: 596007)

In this experiment, we are going to block the

Figure 6-27

The water blocks oxygen.

passage of oxygen to the fuel cell, and see whether it can continue to function. Set up the fuel cell as in the previous experiments, with either methanol or sodium borohydride as the fuel. Then, to the

inside of the red cathode, add a small amount of Conclusion

distilled water, just enough to cover the cathode electrode. When taking measurements, you should

This proves the need for oxygen, at the cathode, find that the fuel cell ceases to produce power.

for the fuel cell’s reaction to proceed.

Project 22: Investigating Different Gases at the Anode If you have access to a range of different gases, from say a school science department, you can

introduce different gases to the fuel cell’s cathode, and see how the reaction proceeds. The clever

design of the mini fuel cell anode means that you

●

Alkaline mini fuel cell (Fuel Cell Store P/N:

530709)

can take a suitably sized rubber bung, with a hole drilled through to allow a pipe to pass through, and

●

Potassium hydroxide (Fuel Cell Store P/N: 500200) introduce different gases to the fuel cell’s cathode,

●

Sodium borohydride (Fuel Cell Store P/N: 560109) as shown in Figure 6-26.

●

Multimeter (Fuel Cell Store P/N: 596007)

Compare how the AFC performs when using

●

Selection of gases

pure oxygen to using ordinary air. You now know

●

Bung and tube

how to produce carbon dioxide—so try it, and if

71

you have access to any laboratory gases, try them too—try introducing hydrogen to the cathode.

Conclusion

You should conclude that the fuel cell needs oxygen in order to function, and that it performs better when fed with a supply of pure oxygen than when

fed with air.

Figure 6-28

A bung and pipe allow you to introduce

different gases to the AFC’s anode.

Project 23: Investigating the Rate of Reaction (Oxygen Consumption) of an AFC

●

Alkaline mini fuel cell (Fuel Cell Store P/N:

We can use the bung arrangement from the last

530709)

experiment, with a short extension pipe, and a

graduated tube to measure the rate of reaction

●

Potassium hydroxide (Fuel Cell Store P/N: 500200) happening inside the fuel cell. You should be able

●

Sodium borohydride (Fuel Cell Store P/N: 560109) to make a piece of graduated pipe out of an old

●

Multimeter (Fuel Cell Store P/N: 596007)

pipette.

●

Bung and tube

The experiment is as follows. Set up the fuel cell

●

Length of rubber hose

with connection to an ammeter and a variable

●

Pipette

resistance all in series. Now, insert the bung into

●

Variable resistor

the cathode of the fuel cell, ensuring a tight seal.

Then take the piece of pipette and insert it into one

●

Connection wires

end of a piece of rubber tubing, and push the other

●

Stopwatch

over the length of pipe sticking out of the bung.

●

Thermometer

The end of the pipette can be immersed in a small Project 23: Investigating the Rate of Reaction ● Calculator beaker of water. Figure 6-27 illustrates this.

72

Project 23: Investigating the Rate of Reaction Figure 6-29

The oxygen consumption measurement apparatus.

As the AFC consumes oxygen as a result of the

Now, work out the average of the three

reaction, oxygen will be sucked out of the void

readings, add them together, and divide the

between the cathode and the end of the pipette

total by three.

dipped in the water. As the AFC consumes oxygen, water will be sucked up the pipette allowing us to take measurements of how much oxygen has been

consumed.

You should set the variable resistor so that it

registers a reading on the ammeter—current

does need to be drawn in order for oxygen to be

consumed.

When you dip the pipette pipe in the water, the

end of the tube will be full of air below the level of the water. As the AFC consumes oxygen, the water level in the tube will rise. When it reaches the same height as the water in the beaker, start the stopwatch.

Using the measurements on the pipette tube, we

are going to time how long it takes for a volume of 1 cm3 (1 ml) of gas to be consumed. You can adjust the variable resistor, as the gas is being consumed in order to maintain a constant current flowing

through the fuel cell. Once you have timed the

consumption of 1 cm3 of gas, empty the end of the tube dipped in the water, and repeat the experiment again. Do the experiment three times, and enter the Figure 6-30

Using a stopwatch, you can easily time

values in Table 6-8.

the reaction.

73

Table 6-6

The Ideal Gas Law says that PV = nRT where P

Three readings for time taken to consume 1 cm3

is absolute pressure, V = volume of gas, of oxygen.

n = number of moles, R = the gas constant and Time (s)

T = temperature. We can rearrange this to find out the number of moles of oxygen:

Reading 1

s

N = PV/RT

Reading 2

s

Reading 3

s

Now, we want to know the number of molecules

of oxygen—remember Avogadro’s number? 6.02 ×

1023—multiply this by the figure you obtained for the number of moles.

Next, we want to find the charge, in Coloumbs,

that flowed around the circuit, so remember Q

(charge, coloumbs) = A (current, amps) ×

We’re going to do some sums now, and it

t (time, seconds)—as a hint, remember that you makes it a lot easier if we use “standard form”

might need to convert current readings from mA

for notation. If you are not familiar with

into A.

standard form/scientific notation, use whatever

Now comes the clever bit—you should now

you prefer. If you think you might need to

know:

swot up a bit, Wikipedia is always a good

place to start looking: en.wikipedia.org/wiki/

●

How many molecules of oxygen were used

Scientific_notation.

●

How many electrons flowed around the circuit

Divide the number of electrons that flowed around the circuit by the amount of oxygen molecules

Key data

concerned.

Your figure should come out as around 4!

Now take the thermometer, and note the ambient

temperature of the room. We’re going to need to

Conclusion

convert this into Kelvins, so if you are working in degrees Fahrenheit, convert to degrees Celsius, and From this experiment, we can see that four electrons then once you have the figure in degrees Celsius, are produced for every molecule of oxygen con-add 273 to convert into Kelvins.

sumed. We also learn that consumption of oxygen

Unless you know better (say you are on the

is directly proportional to power produced.

top of a mountain), the atmospheric pressure can be assumed to be 100 kilopascals (100 kPa)

or 1.0 × 105 Pa.

Now, remember we consumed 1 cm3 of

oxygen—we need this figure to be in “meters

cubed,” so 1.0 × 10−6 m3 should do the trick!

If your thirst for knowledge about alkaline fuel Now, the next figure is something you are

cells is truly inexhaustible, you might want to

unlikely to know—it is called the gas constant, check out some of these links, which make good

and it is the number that makes this equation work.

sources of research for science fair projects,

For the SI units that we are using, the constant is reports, essays, you name it!

Project 23: Investigating the Rate of Reaction 8.314472 m3·Pa·K−1·mol−1.

—Contd

74

Project 23: Investigating the Rate of Reaction Apollo Energy Systems—AFC manufacturer

Independent Power—AFC manufacturer

http://www.apolloenergysystems.com/

www.independentpower.biz

Astris Energy—AFC manufacturer

Intensys—AFC manufacturer

www.astris.ca/

www.intensys.com

Cenergie—AFC manufacturer

Homepage of Dr John Varcoe from the University

www.cenergie.com/

of Surrey, who is doing very cool things with

AFCs

ENECO—AFC manufacturer

mypages.surrey.ac.uk/chs1jv/

www.eneco.co.uk/fuelCells.html

75

This page intentionally left blank

Chapter 7

PEM Fuel Cells

What is a PEM fuel cell? Well, it all depends on and metal ions. This makes them very sensitive

who you ask! Some will call them “plastic elec-

to hydrogen that is not pure—and with fuel cells, trolyte membrane” fuel cells, while others will call damage can be expensive to repair!

them “proton exchange membrane” fuel cells.

Whatever you call them, PEM fuel cells are very versatile, with the advantage that they will happily How do PEM fuel cells

work at low temperatures.

work?

This is what makes them useful for our experi-

mentation purposes—we can play with them at

Take a look at Figure 7-1, and we’ll slowly work home at room temperatures, as opposed to some of through the operation of a PEM fuel cell. We can the high-temperature fuel cells in this book which see the cell represented schematically in this

require searing heat for their operation.

diagram.

As with all our fuel cells, electrochemical

reactions are taking place inside them, which release You can see the hydrogen entering on the anode

the energy produced as a result of the oxidation of side of the fuel cell, the oxygen entering on the hydrogen in the form of electricity. This is opposed cathode side of the fuel cell, and the membrane in to releasing it by oxidation in the form of com-the middle. The membrane is coated with catalyst bustion, which is horribly inefficient.

on both sides.

One of the disadvantages of PEM fuel cells is

We are going to break the process down into a

that they are easily poisoned by carbon monoxide, series of steps. In reality, this is a continuous Figure 7-1

The proton exchange.

77

Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.

Figure 7-2

Hydrogen enters the fuel cell.

process which is taking place; however, looking at As this process is happening, the protons are

it in stages, rather than all at once, helps us to migrating across the solid electrolyte PEM mem-understand it.

brane, while the electrons are journeying around We can see, in Figure 7-2, the hydrogen fuel

the circuit (Figure 7-5). They all meet up at the entering the fuel cell.

cathode.

When it reaches the proton exchange membrane,

When they reach the cathode, the catalyst

the catalyst splits it into protons and electrons. The coating helps the oxygen, protons, and electrons protons begin to cross the membrane, while the

to combine to form water, as shown in

electrons make their way around the circuit (see Figure 7-6.

Figure 7-3).

Now, let’s look at the components of the cell,

As this is going on, oxygen is also entering the and get to know the PEM fuel cell by taking one

fuel cell on the cathode side.

apart, and building a small fuel cell kit.

PEM Fuel Cells Figure 7-3 The hydrogen is split into protons and electrons.

78

PEM Fuel Cells

Figure 7-4

Oxygen enters the fuel cell.

Figure 7-5

The electrons make their way around the circuit.

Figure 7-6

The electrons, protons, and oxygen combine to form water.

Now, move to the magnifying glass at the bottom

Let’s start with the

of the image:

membrane

You see the gray line running down the middle—

well, that is our “Nafion™” membrane—think of it The membrane is the particularly clever piece of like a cookie with chocolate chips on both sides.

our PEM fuel cell—so clever, in fact, that I wonder The cookie dough is the special plastic our fuel why they don’t call it a mem-brain!

cell is made from. The gray blobs either side, that In our PEM fuel cell, it is the membrane that

look like chocolate chips, are the gas diffusion does all the hard work, allowing certain reactions layers which are bonded to either side of the

to take place, while preventing others.

Nafion™ membrane. Where the “chocolate chips”

meet the cookie dough, we have our platinum

To understand exactly how it works, let’s take

catalyst. This can be seen more closely in the two a closer look at what happens inside the

magnifying glasses at the top of Figure 7-7—you

membrane.

will see that one magnifying glass concentrates on Take a look at Figure 7-7.

the anode, while one examines the cathode.

OK, starting in the bottom left of Figure 7-7, we Now, our reactions take place at the point

can see what looks like a sandwich. On either side, where the cookie dough (Nafion™), chocolate

we have our electrodes—the anode and the

chips (GDL), platinum catalyst (the small white

cathode, and in the middle, we have a couple of

dots between the chocolate chips and cookie

slices of gas diffusion membrane, and then, the

dough—let’s call these “sprinkles”), and gas meet.

best bit of all, our MEA!

The hydrogen gas comes in at one side, permeates PEM Fuel Cells Figure 7-7 What goes on in the middle of the PEM membrane!

80

PEM Fuel Cells

through the GDL, and the sprinkles (platinum)

catalyze a reaction (and this is where the cookie All you wanted to ever

[analogy] crumbles), where the hydrogen passes

know about sulfonated

through the cookie (Nafion™), the electrons

pass through the chocolate chips (GDL), where

tetrafluorethylene

they are reunited at the other side of the cookie.

copolymers . . .

Now, remember we said there were two sides to

this cookie? (Yes … even Millies make mistakes),

. . . and probably quite

there are more sprinkles (platinum catalyst) on the a lot you didn’t!

other side, so, as our electrons are conducted

through the chocolate chips to meet the cookie

Our PEM fuel cells wouldn’t exist if it weren’t for dough (which protons have just passed through),

rapid advances in polymer technology that allowed the sprinkles catalyze another reaction between the the creation of the “solid electrolyte”.

protons, the electrons and … introducing …

Nafion™ was discovered in the late 1960s by a

oxygen from the other side of the cookie. They all man called Walther Grot at DuPont™. Nafion™

get together to produce water!

has enabled the construction of the PEM fuel cell, Now, clearly we are not using cookies, and

due to its unique chemical properties.

chocolate chips and sprinkles—the materials used in There are a couple of things that fuel cell fans fuel cell construction are much more sophisticated really like about Nafion™:

(unless you evaluate them by taste— don’t try it kids).

Mechanically it is very stable—it’s not going to We’re going to look at the materials used in a

crumble when you look away, it’s flexible and

little more depth!

won’t crack—it’s a little flimsy, but treat it

with respect and it will be reliable.

Chocolate chips

Chemically it is tolerant of a wide range of Well, although it looks like chocolate chips from the chemicals and does not react or degrade

side, in reality, the woven carbon cloth of the GDL is readily (apart from with alkali metals).

more like a closely woven lattice of chocolate sauce.

Thermally it is tolerant of the temperature It needs to have holes to allow the hydrogen to

experiences in PEM fuel cells.

penetrate through to the cookie dough (Nafion™

It is stable to changes in temperature.

membrane); however, it still needs to provide

In Figure 7-8, we can see the Nafion™ unit: the

sufficient surface area and support to the sprinkles top right is the Teflon backbone of the Nafion™

underneath to allow the reactions to take place.

(the same material you find in your nonstick

frying pans), while the bottom right shows the

Sprinkles

sulfonic acid group that allows for the conduction of protons.

We may use slightly different materials for the

sprinkles on each side of the fuel cell. While

It’s hard to pin down the exact nature of Nafion™

hydrogen is relatively easy to split, the oxygen structure, although one suggestion is the cluster is a little more of a challenge. Platinum is a good model shown in Figure 7-9: Look at the sulfonic

material for this application, however, with advances acid groups around the outside.

in material science, we may find more efficient and The SO groups (or sulfonic acid) groups in the

-3

cheaper catalysts to replace the sprinkles on both Nafion™ can jump from one side of the membrane sides of the membrane.

to the other. This allows them to transport protons 81

Figure 7-8

Nafion™ chemical structure.

from one side of our PEM fuel cell to the other—

a crucial facet of the PEM fuel cell’s operation.

What’s also really clever about these little Flow fields

sulfonic acid groups is that they only allow the In some of our smaller fuel cells, we can make do passage of cations—the anions and electrons can

without a fully blown flow field, and get away

just get lost if they think they’re crossing this with a piece of carbon cloth or paper to do the

sulfonated tetrafluorethylene copolymer membrane!

same job—just spread the hydrogen over the

However, as we know, the electrons might have to surface of the MEA, while allowing electrons to be take a slightly more circuitous route (OK, so it’s a transferred from the GDM to the electrodes.

bad pun!), but on their journey, they do useful

work for us.

However, once we start looking at more sophisti-

cated fuel cells, carbon cloth and paper just doesn’t So the sulfonic acid groups act as gatekeepers in cut the mustard—we need to look at more sophisti-our fuel cell, only letting those with proton passports cated methods of spreading the hydrogen thinly

across the border, while the electrons have to take and evenly over the surface of the MEA, on the

the long way home.

anode, and ensuring that sufficient amounts of

I often lay awake wondering where we would be

oxygen come into contact with the MEA on the

without sulfonic acid groups …

cathode side.

PEM Fuel Cells Figure 7-9 Nafion™ cluster model.

82

PEM Fuel Cells

Figure 7-10

Straight flow field.

Figure 7-12

Serpentine flow field.

The type of flow field we select will depend on

The simplest of them all is the straight flow

the flow characteristics that we desire. There is field, which has a place for gas to be input, and ongoing research into how the design of the flow place for excess gas to escape, and a straight grid field can affect the efficiency of the fuel cell, with of lines between the two sides.

scientists working to reconcile two competing

Getting slightly more advanced, in Figure 7-11,

factors—the need to spread hydrogen over the

the interdigitated flow field has interlocking fingers surface of the MEA, while still maintaining good of hydrogen supply and return lines. However,

electrical contact with the surface of the MEA.

these are not connected directly, so the hydrogen There are a few different patterns that we can

must make a path to the MEA before spare hydrogen look at, in Figures 7-10 to 7-13.

can be returned.

Figure 7-11

Interdigitated flow field.

Figure 7-13

Spiral flow field.

83

The serpentine flow field is like a long undulating Of course, manufacturers are developing new

snake—the hydrogen has to make a path forward

variations of these flow fields every day. You might and backward, forward and backward, before it

even like to turn to the project entitled “Making reaches the return. Hopefully, by this time, much Your Own MEAs” on page 126, and look at how

of the hydrogen has had its chance to cross the

you can advance the state of the art in fuel cell MEA’s membrane.

technology.

Finally, another variation is the spiral flow field—it does exactly what it says—spirals in, then spirals out.

Project 24: Disassembling a Fuel Cell

The fuel cell kit will come with a spanner and

Allen key, that fits the fixings used to aid assembly and disassembly. You can see in Figure 7-15 that it is relatively easy to remove the fixings.

●

A dismantleable fuel cell, e.g., Fuel Cell Store P/N: When all four nuts and bolts have been removed,

80044

ensure that you keep them somewhere safe, and have a flat, clean surface to work on, as in Figure 7-16.

●

Supplied Allen key and spanner

By taking apart a fuel cell, we can learn a lot about its construction, which will help us to relate some of the theory, here on the page, to the practical aspects of constructing a fuel cell. If you have any thoughts of scratch building your own fuel cell, it is a good idea to start with a commercially available dismantleable fuel cell, to get to grips with the construction.

However, be warned—although such fuel cells

are designed for being taken apart and reassembled, they can still be damaged if you do not take

sufficient care.

Project 24: Disassembling a Fuel Cell

Figure 7-14 shows us a dismantleable fuel cell.

Figure 7-14

The complete dismantleable fuel cell.

84

Project 24: Disassembling a Fuel Cell

electrode assembly. You now have to decide whether you want to take this component apart—while

educational, you run the risk of damaging the fuel cell at this point if you are not careful.

Carefully remove one electrode and then the next, exposing the MEA. You will be left with three

components, as shown in Figures 7-20 and 7-21.

Ensure that you do not touch the MEA, or the

surfaces that come into contact with it.

The next step is OK if you have spare MEAs, or

Figure 7-15

The supplied Allen key and spanner can

the money to shell out to buy a new one—you can

be used to disassemble the fuel cell.

learn just as much by looking at the pictures.

However, if you do decide to take apart your own MEA, don’t cry when your fuel cell refuses to

Lay the parts out so that you can see what is happen-work afterwards. This is maybe a step to carry out ing as you take the fuel cell apart.

when you’ve had your fun with the dismantleable

When you’ve got all the fixings away, you can

fuel cell and/or worn out the MEA!

carefully remove the plastic end-plates, as shown in Figure 7-17—this will expose the electrode

assembly in the centre of the fuel cell.

If you wish, you can use a scalpel to carefully

Lay out the end-plates and electrode assembly,

deconstruct the MEA—it will render it useless

as in Figure 7-18.

though. Figure 7-22 illustrates the components of The electrode assembly is what is shown in

the MEA well. With one either end, you can see

Figure 7-19—it comprises of two electrodes,

the plastic gaskets that support the MEA, with the the gas diffusion membrane, and the membrane

carbon GDMs either side of the central MEA.

Figure 7-16

The fuel cell with fixings removed.

85

Figure 7-17

Removing the end plate.

Figure 7-18

The end plates and electrode assembly.

Figure 7-19

The electrode assembly.

Figure 7-20

One electrode removed.

Project 24: Disassembling a Fuel Cell

86

Project 24: Disassembling a Fuel Cell

Figure 7-21

Two electrodes removed.

Figure 7-22

The MEA deconstructed.

Figure 7-23

Diagram showing the components of your dismantleable fuel cell.

87

Relate the deconstructed MEA to the earlier

Figure 7-23 may be of help, when

diagrams in the chapter, compare the schematic

considering how the different layers of the PEM

models of the fuel cells earlier in this chapter, and fuel cell go together—providing an exploded

relate it to your practical experience of taking the diagram.

fuel cell apart.

Project 25: Changing MEA Platinum Loading

the GDL. The more platinum, the more sites there are for reactions to take place, and so the output of the fuel cell should be higher.

One way that you can experiment with this is

with the dismantleable fuel cell. The extension kit

●

Dismantleable fuel cell—extension kit (Fuel Cell comes with a couple of extra MEAs, with different Store P/N: 80044)

platinum loadings to the standard one fitted in the The performance of a PEM fuel cell will depend to fuel cell. You can substitute these MEAs, reassemble some extent on the amount of platinum catalyst

the fuel cell, and compare how the cell performs sandwiched between the Nafion™ membrane and

under different conditions.

Project 25: Changing MEA Platinum Loading Figure 7-24 Different membrane electrode assemblies.

88

Project 26: Experimenting with Oxygen and Air Project 26: Experimenting with Oxygen and Air

●

Dismantleable fuel cell with oxygen and air

end-plates (Fuel Cell Store P/N: 80044)

You will realize that oxygen is only a component of the air that we breathe. In fact, our atmosphere is comprised of 78% nitrogen and around 20.95%

oxygen.

It should therefore follow that a fuel cell running on pure oxygen will perform in a superior manner to one running just on air.

We can experiment with this proposition, by

Figure 7-25

Air fuel cell end-plate.

using a dismantleable fuel cell. Remember, with a good experiment, we want to control as many

factors as possible, to reduce the chance of error end-plate with pipe connections, for one with an arising from other sources. In practice, this means open grate that allows easy passage of air.

that we want to keep as much of our fuel cell the same as possible—keeping the same MEA, GDM

When we feed oxygen into a fuel cell, we need

and electrodes, but changing the oxygen to air or to do it under a very small pressure, so we can use vice versa.

an end-plate like Figure 7-26, which has a pair of barbs to feed and return the oxygen to our fuel

When we are running our fuel cell on air, we do

cell.

it at atmospheric pressure. We want to maximize

the amount of air reaching our fuel cell, as it is not Set your fuel cell up with both air and oxygen

being forced under pressure through a pipe. So

end-plates, and take measurements to compare the when running our fuel cell on air, we change the performance of the cells using oxygen and air.

89

Figure 7-26

Oxygen fuel cell end-plate.

Project 27: Building Your Own Mini Fuel Cell

Consumer electronics devices are becoming increas-Fuel cells potentially offer all kinds of exciting ingly miniaturized. You only have to look at the possibilities for powering portable electronic

suitcase mobile phones of the 1980s with bricks

devices.

for handsets, and compare them to today’s phones, which can outsmall a bar of soap for evidence of this trend.

One of the limiting factors in miniaturizing

electronic devices has been the power technology.

●

Mini fuel cell (Fuel Cell Store P/N: 531907)

Early mobile phones were necessarily large—not

only because the electronics inside were big, but also because the batteries needed to power them

were commensurately massive.

Improvements in battery technology, and the

improving energy efficiency of electronic devices is leading to smaller and smaller powerpacks;

●

Pair of hands

however, there is a complex tradeoff with size for

●

Cotton gloves (optional)

operating life. Smaller batteries mean that you can talk for less time on your phone, listen to less The mini fuel cell is a really clever construction.

tunes before having to recharge, or watch less

The manufacturers have used the gasket material to movies on your portable media player before it is keep all the parts of the fuel cell together, with Project 27: Building Your Own Mini Fuel Cell back to the docking station.

simple folding required for assembly.

90

Project 27: Building Your Own Mini Fuel Cell

Figure 7-27

The mini fuel cell laid out.

You can see, the mini fuel cell laid out in all its Start at one end, and work your way along the

glory in Figure 7-27. We can see by the perforated mini fuel cell—the squares of brown adhesive paper metal electrodes looking at the ends. You will see are removable protective coverings for an adhesive that the metal is “dished in” slightly—this is to layer. You need to peel these off one by one, and ensure that it makes good contact with the GDM

fold the fuel cell over in sequence, making sure when the fuel cell is folded. You can see the two you don’t touch any of the sensitive bits of the fuel tiny GDLs moving into the next two squares. This cell, for risk of poisoning the catalyst.

provides electrical contact between the electrodes Cotton gloves will protect the elements of the

and the MEA, while allowing the hydrogen (and

fuel cell that can be damaged, but if you’ve got don’t forget the oxygen) gas to diffuse toward the clumsy fingers like me, you’re going to struggle to MEA .… And finally, our central square is the

peel the adhesive backings from the squares, and membrane electrode assembly—the little patch

you might end up getting in a mess with cotton

where all the exciting reactions take place!

gloves stuck to the sticky bits of the fuel cell.

As you remove the backing paper from the

adhesive layer adjacent to one electrode, fold that section of the fuel cell over, and ensure that the GDM makes good contact with the electrode.

Right! This step is absolutely crucial. Two things you need to remember: do not touch the MEA

under any circumstances. Cotton gloves are a godsend in this respect, although when peeling off the fiddly adhesive backings, they can also be a nightmare—use your judgment and caution. Once

you’ve teased off the adhesive backing from your GDM, you are going to need to line up the flimsy MEA with the square of GDM. Ensure that you get

them to sit directly over each other for optimum performance. Figure 7-30 shows the fiddly job of lining them up.

OK, it’s sharp nails at the ready for the last time!

Tease the final corner of that last adhesive square, and fold the fuel cell over for the last time, leaving Figure 7-28

Peeling the backing paper from the

you with a neatly packaged little square mini

adhesive gasket.

fuel cell.

91

Figure 7-29

The fuel cell once folded.

Figure 7-30

Lining up the MEA.

Project 27: Building Your Own Mini Fuel Cell Figure 7-31 Removing the final adhesive backing.

92

Project 27: Building Your Own Mini Fuel Cell

Figure 7-32

Mini fuel cell next to a quarter for scale.

Once you’ve stuck the fuel cell together with the adhesive squares, you need to ensure that proper contact between all the layers is made. You will see that all around the edge of the mini fuel cell, there are small metal extensions to the electrode.

These are folded over the opposing electrode, nice Figure 7-33

Use a multimeter to check power is

and tightly, to clamp the fuel cell assembly together.

being produced.

Don’t worry, they won’t short out against the

opposite electrode—the plastic end-plates will stop this from happening!

And just to remind you of the wonders of the

mini fuel cell’s miniaturization, check out Figure 7-32, with the fuel cell next to a quarter for a sense of scale. This is what your mini fuel cell should look like when finished. Note the tabs folded over.

Yes! It really does work. To see a video of the

Now, you should be proud of your workmanship.

mini fuel cell powering a “spinner” powered by

Go and test it out! Grab yourself a multimeter, and the hydrogen from the H-Gen generator, check

a source of hydrogen. Hold the end of the hydrogen out my video on YouTube at:

tube close to the small hole in the plastic end-plate www.youtube.com/watch?v=JsWfvUktNuo

of the mini fuel cell, and watch it crank out the volts.

93

This page intentionally left blank

Chapter 8

Direct Methanol Fuel Cells

One of the problems with hydrogen is that it is a little problematic to store. This is a concept that we Attention

will explore in the later chapter on hydrogen storage.

There is another type of fuel cell, which is able to Direct methanol fuel cells require a

utilize methanol as a carrier of hydrogen.

solution of methanol in water, if the

There are a number of advantages to this approach: concentration of methanol is too high you will

methanol has a very high energy density and it can damage the membrane in the fuel cell.

be transported easily using existing infrastructure Manufacturers recommend that you work with

for moving liquid fuels.

concentrations that do not exceed 3%. In practice, One of the problems with hydrogen is that it

this is often a little overcautious, and

requires a massive change of infrastructure. While concentrations around 4% can work

successfully. However, note that concentrations

this is not impossible, it does necessitate a change.

much higher than this will certainly damage

One of the advantages of the methanol fuel cell is your fuel cell, and concentrations over

that the methanol can be stored and transported

3% are not recommended for

using the conventional infrastructure that is used to prolonged use.

move and transport other liquid fuels such as petrol.

Because the methanol can utilize the existing

infrastructure, many believe that methanol will be a good transitionary fuel in the move over to a

hydrogen economy.

First aid guidelines

If you get methanol in contact with your

skin, you will need to wash it off with

copious amounts of water, as methanol is

toxic.

Protect your eyes from splashes from methanol by wearing safety goggles at all times. If you do

Warning! Methanol is TOXIC and highly

inadvertently splash even the tiniest amount of

flammable.

methanol into your eyes, you will need to

thoroughly wash them using clean water or an

Keep methanol away from all sources of ignition.

eyewash station, and contact a doctor immediately Only operate the system in an area that is

or your hospital’s ER department.

sufficiently ventilated to ensure that you are not exposed to high concentrations of methanol

Be careful not to inhale methanol fumes. If you

fumes.

do, open windows, and walk outside and get some

95

Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.

Overlay the chemical reactions that are taking

fresh air. If symptoms persist, consult your doctor place (see Figure 8-3), and we can see water and or your hospital’s ER department.

methanol entering together at the top left, the

Methanol should not be ingested. In the event that protons being stripped of their electrons with

you do accidentally ingest some methanol, drink

carbon dioxide, and water the resulting product.

lots and lots of clear water and consult a doctor The protons pass through the membrane, the same

immediately or your hospital’s ER department.

as in the PEM fuel cell, and the electrons pass

If you feel nauseous, consult your doctor. Tell the round the circuit. On the other side of the diagram, doctor you have been working with methanol, and

things are the same as we are used to seeing with show him the material’s data sheet.

the PEM fuel cell.

We can see that the carbon dioxide is produced

at the anode of the fuel cell.

Direct methanol fuel cell

chemistry

Direct methanol fuel cells directly reform the methanol, extracting the hydrogen, and producing carbon dioxide with the spare carbon in the methanol. We can see methanol fuel cell chemistry in Figure 8-1.

Get a good measuring cylinder, like the one in

Figure 8-4, as you will need to prepare methanol Looking to the diagram in Figure 8-2, we can

solutions of different concentrations.

see how the methanol fuel cell is a membrane fuel cell, just like the PEM fuel cell we looked at in the previous chapter. Functionally, they are very similar.

Figure 8-1

Direct methanol fuel cell chemistry.

Figure 8-2

Direct methanol fuel cell diagram.

Direct Methanol Fuel Cells

96

Direct Methanol Fuel Cells

Figure 8-3

What goes on inside a DMFC?

Figure 8-4

A cylinder suitable for preparing different methanol concentrations.

97

Project 28: Getting to Grips with the Methanol Fuel Cell

●

DMFC fuel cell and load (e.g., DMFC and fan Fuel The correct way to fill the fuel cell is to use a Cell Store P/N: 550307)

squeezy bottle with a narrow spout. Hold the fuel

●

Prepared methanol solution—3% methanol in

cell so that the two holes are angled, insert the distilled water (Fuel Cell Store P/N: 500100)

squeezy bottle into one hole, and squeeze until

there is no air left in the DMFC chamber.

●

Squeezy bottle

If your fuel cell has been stored in a dry atmosNow pour some 3% methanol solution into

phere, you may find its initial performance a little the cell.

disappointing. This is because the membrane needs The cell will take a little time to start up. It is to be hydrated. Try using a little distilled water not unusual for it to be several minutes before the first of all to dampen the membrane, and then fill cell starts producing any power. Once the cell

the cell with some methanol solution.

starts producing power, it will happily run for a The methanol fuel cell has two holes at the top

few hours.

of the assembly. These holes allow you to fill the Once the cells stops producing power, then the

fuel cell with a prepared methanol solution. You methanol has been exhausted. The cell must now

can pour methanol into one hole, and the other

be drained and refilled to start producing power hole will allow air to escape.

again.

Figure 8-5

Closeup of filling the methanol fuel cell.

Figure 8-6

Filling the methanol fuel cell.

Project 28: Getting to Grips with the Methanol Fuel Cell 98

Project 29: Decommissioning and Recommissioning Project 29: Decommissioning and Recommissioning

a Methanol Fuel Cell

●

Direct methanol fuel cell

solution, recharge it a couple of times, and leave it for several minutes.

●

Distilled water

●

1% sulfuric acid

The cell will degrade if it is left without being used. If you find that it will not work even after

●

3% methanol solution

recharging with 3% methanol, then you will need

to recommission the cell.

Introduction

If a methanol fuel cell is not to be used for some time, it should be “decommissioned” and then

“recommissioned” when you are ready to use it

again. This will ensure long life of the cell.

Method

Sulfuric acid is very nasty stuff and precautions should be taken to ensure that you do not get it on Decommissioning

your hands, in your eyes, or ingest it.

Flush the cell out with some distilled water that does not contain methanol. Now, using a small

piece of tape, seal the two holes. This will prevent the cell from drying out.

Prepare some 1% sulfuric acid solution and

Recommissioning

charge the fuel cell as you would do with methanol.

Leave it for a couple of days. Then empty the acid If the cell is to be used again, the tape should be and recharge with a 3% methanol solution. The

removed. First, try the cell with some 3% methanol cell should work again.

99

Project 30: Building a Band-Aid® Fuel Cell

and an idea began to form . . . The result is this project, which is truly a Band-Aid!

Once you’ve gathered all the parts in the list, you should have an array of bits that resemble Figure 8-7.

●

2 nice big Band-Aids®

You need to ensure that you have suitably large

●

Type 316 stainless steel wire cloth (Fuel Cell Store Band-Aids.

P/N: 590663)

Think Rite Aid or Walgreens. These are just your

●

5L DMFC MEA 5cm2 (Fuel Cell Store

bog-standard Band-Aids. Don’t get ones that are

P/N: 590310)

impregnated with aloe vera or any special ointment—

Fuel Cell ● Cotton gloves (Fuel Cell Store P/N: 591463) it will simply gunk up the works. Just get plain old

®

Band-Aids. You want one with a nice big area for

●

3% methanol solution (Fuel Cell Store

the “wound.”

P/N: 500100)

Remember, from the point you start peeling the

●

Multimeter (e.g., Fuel Cell Store P/N: 596107)

adhesive film from the Band-Aid, you need to keep the surfaces that come into contact with the MEA scrupulously clean. At all times when working

with the MEA, you will need to wear cotton gloves as shown in Figure 8-10. This is because the muck on your hands will greatly inhibit the function of the MEA.

●

Scalpel

We are going to make our electrodes from

●

Scissors

stainless steel screen. If you want to get really techie In this experiment, we are going to build a very simple, rough and ready, direct methanol fuel cell with the help of a box of Band-Aids®. I originally published this project in MAKE:zine, and many fuel cell experimenters have found it a simple, easy introduction to fuel cell technology. I really do not think there is a simpler way to scratch-build a

direct methanol fuel cell, and get to grips with the technology.

Before we get stuck into the nitty-gritty of

construction, I must share with you, esteemed

reader, how this project came into being. I had just read on the net, the quote from Lawrence Burns,

the GM vice president for research and

development, who said, “The fuel cell offers a cure, not a Band-Aid.” Shortly after, while going to the Project 30: Building a Band-Aid bathroom, my eyes clapped on a box of Band-Aids, Figure 8-7

The components of the Band-Aid fuel cell.

100

Project 30: Building a Band-Aid

Figure 8-8

A pair of suitably sized Band-Aids.

and heavy about stainless steel fly screen, the

You can make your own, but they are rather difficult material that I used was top-notch stuff. The stainless to assemble—much simpler is to buy one that is

steel was 318 grade, i.e., very high quality! The already made from www.fuelcellstore.com. This is screen was 72 wires per inch in both directions, with what you get for your money: a piece of Nafion™—

each wire being 0.0037 inch. To show you the sort of this posh plastic is technically known as a sulfonated material we are referring to, look at Figure 8-11.

tetrafluorethylene copolymer . . . Let’s look a little more closely at the plastic bag in Figure 8-12.

MEA—the membrane electrode

The large DMFC tells you that the fuel cell is a assembly

direct methanol fuel cell—this is a variant of a proton exchange membrane fuel cell. What it

MEA stands for “membrane electrode

essentially means is that the MEA reforms the

assembly”—this is the bit that “does the works.”

methanol to carbon dioxide and hydrogen without

any external action required. It really is all clever stuff! Looking at the panel on the right-hand side of the label, we can see that the “active area” of

®

Fuel Cell

Figure 8-10

Cotton gloves ensure the MEA is not

Figure 8-9

Unwrapping the Band-Aids.

damaged.

101

Making the Band-Aid fuel cell

Making the Band-Aid fuel cell is a real walk in the park. All you need to do is be sure that you protect the MEA and handle it delicately, and try and ensure all surfaces remain clean.

First of all, you need to cut a rectangle of wire mesh. This should be a little narrower than the

smallest dimension of the wound pad of your

Band-Aid, and longer than the longest dimension

of your Band-Aid. Cut another identical strip.

Figure 8-11

Stainless steel fly screen.

Now, remove the protective covering from one

Band-Aid, as in Figure 8-13, and place the first Fuel Cell

piece of wire mesh so that it sits just inside the wound pad of your Band-Aid. The other end will

®

the fuel cell—that is to say, the bit with the

protrude past the end of your Band-Aid. It should catalyst—is 2.3 cm × 2.3 cm, about an inch square resemble Figure 8-14.

for those using Imperial. The Nafion membrane

itself is significantly larger—5.5 × 5.5 cm square, Now, remove the MEA from the bag carefully

or about 2 inches square.

using cotton gloves (see Figure 8-15).

We can see looking at the details below that the You need to trim the MEA so that it is slightly

anode is coated with a mixture of platinum and

bigger than the wound pad of your Band-Aid, but

ruthenium, 4.0 milligram per cm3 to be exact, while so that there is still a generous border of

the cathode is loaded with 2.0 milligram of platinum.

Band-Aid sticky to hold the assembly together.

The membrane has a built-in gas diffusion layer of The MEA must overlap the wound pad

carbon cloth.

(see Figure 8-16).

Project 30: Building a Band-Aid Figure 8-12 Details of the MEA we are using for the Band-Aid fuel cell project.

102

Project 30: Building a Band-Aid

Figure 8-13

When removing the cover of the

Band-Aid, do not touch the wound pad.

The next shot (Figure 8-17) displays the MEA

Figure 8-15

Getting the MEA out of the bag.

checked for size against a Band-Aid. Note that

“anode” is marked on the MEA—you need to

make a note of on which side “anode” appears the Now take the other strip of wire mesh that you

correct way round on; make a note of this and put cut, and lay it up on the MEA so that the spare

a “+” on the Band-Aid facing the MEA. You might

length of gauze protrudes from the opposite end.

want to use an overhead projector pen to do this.

I found at this point that it was a good idea to Next, lay the MEA on the wire mesh (see

bend the wire gauze back on the Band-Aid, corre-

Figure 8-18), noting orientation. Ensure that the sponding to the side of the MEA the gauze was in overlap of the MEA sticks to the border of Band-contact with. This helped me to remember which

Aid adhesive—you need to isolate each side of the piece of gauze was what electrode.

MEA from each other using the Band-Aid adhesive

Now, use a scalpel to remove a 1-cm square of

®

as a barrier.

the pink bit of Band-Aid from the side that is in Fuel Cell

Figure 8-14

Laying the wire mesh on the first

Band-Aid.

Figure 8-16

Trimming the MEA to size.

103

Figure 8-19

Laying the final layer of wire mesh on

top of the MEA.

Figure 8-17

Checking the MEA for size.

Fuel Cell

contact with the anode side of the MEA

fuel cell dry, and oxygen will permeate through the

®

(see Figures 8-20 and 8-21).

breathable Band-Aid.

Connect the electrodes protruding from either

Testing the Band-Aid fuel cell

end of the Band-Aid to a multimeter, but do not

expect big shakes first time round! DMFC fuel

To test the fuel cell, you will need some 3%

cells take time to “break in.”

methanol solution. Again, you can get this from fuel I found that the voltage that my cell produced

cell stores, unless you know a bit about chemistry or was improved by applying a little light pressure to are friendly with a college lab technician.

the area either side of the methanol top-up point.

To fuel the cell, you will need to introduce

This is because the wire gauze makes better contact methanol solution to the patch of Band-Aid you

with the MEA.

removed on one side. The wound patch will act as a reservoir for the fluid. Keep the other side of the Figure 8-20

Using a scalpel to remove a square from

Project 30: Building a Band-Aid Figure 8-18 Laying the MEA on the wire mesh.

the top layer of the Band-Aid (initial cut).

104

Project 30: Building a Band-Aid

Figure 8-21

Using a scalpel to remove a square from

the top layer of the Band-Aid (completing the cuts).

The future of DMFCs

Figure 8-23

The Band-Aid fuel cell connected to a

You’ll see in our Band-Aid fuel cell that we had a meter.

separate anode and cathode—and it’s important

that the methanol only touches the anode. Well, a company caused CMR has developed an innovative

DMFC fuel cell (see Figure 8-24), which takes

away some of the complexity of separating anodes and cathodes in a DMFC stack.

Web link to CMR fuel cells

www.cmrfuelcells.com/index.php?option=com_

frontpage&Itemid=1

®

Fuel Cell

The CMR DMFC fuel cell is different, in using

selective catalysts on the anode and cathode side.

Their DMFC is fed a bubbled solution of air and

methanol solution. However, because the methanol will only react with the selective catalyst on the anode, and the oxygen will only react with the

selective catalyst on the cathode, no physical

separation is necessary—this is the sort of innovation that is going to reduce the complexity of fuel cells, bring down their price, and help them to reach the consumer electronics market more quickly.

We can carry out many of the same experiments

in the PEM fuel cell chapter, using simple DMFC

fuel cells which we can connect in a circuit, such Figure 8-22

The completed Band-Aid fuel cell.

as that shown in Figure 8-25.

105

Fuel Cell

Figure 8-24

®

CMR’s innovative DMFC fuel cell.

Figure 8-25

DMFC fuel cell suitable for experimentation.

Project 30: Building a Band-Aid

106

Chapter 9

Microbial Fuel Cells

In this book, we have looked mainly at fuel cells which rely on physical, chemical reactions taking Where is the technology

place. In this chapter, we are going to look at a going?

radically different type of fuel cell, which operates in a radically different way—the microbial fuel cell.

Bacteria take in food and produce waste products.

The feedstock for microbial fuel cells is a

Some bacteria take a “fuel” such as glucose, and

“bioconvertible substrate.” This is jargon for a digest the fuel to produce two waste products:

substance that can be converted biologically into carbon dioxide and water, in the presence of

energy for the fuel cell. This can comprise a range oxygen. If you remove the oxygen, the bacteria

of things—sugar (glucose), or biomass feedstocks tend to produce carbon dioxide and protons and

specifically grown for the purpose, such as algae.

neutrons.

Living creatures take food, and metabolize it to Medical science has now progressed to the

provide them with energy. They are oxidizing

point where it can prolong life, or improve the

energy rich, which (reading ahead to LEO the Lion quality of people’s lives by implanting electrical goes GER) implies that they are electron rich.

devices in the body to help assist the function of The process of digestion is a very complex one,

impaired organs. Pacemakers and cochlear implants involving lots of reactions which are catalyzed by are examples of medical devices that are implanted enzymes. This process happens at relatively low

“subdermally,” that is to say, “below the skin.”

temperatures. In the reference section, the paper by These are all candidates that could potentially be Bennetto describes this process as “cold

fueled by microbial fuel cells in the future.

combustion.”

Scientists at Tohoku University have developed

fuel cells which will use blood as a fuel. This

paves the way for medical implants that can be

History of the microbial

powered by the patient, negating the need for

future operations to replace batteries.

fuel cell

NASA estimate that over the duration of a

journey to Mars, taken to be six years, a crew of In 1912, Professor M.C. Potter, at the University of six astronauts could produce up to six tons of solid Durham, managed to extract electricity from

organic waste, with a lot of that being human

E. coli bacteria—this work was duly published in excrement. Clearly in the depths of space, you

the proceedings of the Royal Society, but then was can’t just FedEx it back home to mission control, ignored. It took until 1931 for the idea to be revisited.

so what do you do?

Barnet Cohen took another look at the idea and

managed to produce a number of cells, which,

Well, microbial fuel cells could help to digest

when connected together, produced a potential

this waste to turn it into useful electricity. This difference of 35 volts, albeit at a very low current.

electricity can be used to power the mission, and 107

Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.

through the process of biological digestion, the brewery, which takes the waste products from the output product is easier to process.

beer-making process—sugars, yeasts, and alcohols—

However, microbial fuel cells are also starting to and digests them, producing clean electricity in the find practical applications in the here and now.

process. The output is cleaner waste-water, without Fosters, Australian brewers of “the amber nectar,”

so many of the biologically active components—and have installed a microbial fuel cell in their

free electricity into the bargain!

Project 31: Building Your Own Microbial Fuel Cell The best way to learn about how microbial fuel

cells work is to construct a simple version. This makes an ideal science fair project, and is great because it traverses the disciplines of biology and

●

2 × P-traps (available from a plumber’s merchant or physics.

builder’s store)

●

Short length of waste pipe (4 in/10 cm) to fit P- traps Making the MFC chambers

●

Plastic wrap

●

Agar jelly

For our microbial fuel cell, we need to create two

●

Salt

separate distinct chambers, interlinked by a pipe called a “salt bridge.” There is a wealth of infor-

●

Carbon cloth (available from Fuel Cell Store

mation from different experimenters (shown in the P/N: 590642)

links section), who have constructed MFCs using

●

Copper wire

found items, bottles, plastic tubs, pots, etc. to form

●

Aquarium aerator pump

their two chambers. This is a perfectly acceptable

●

Length of aquarium tube

solution; however, you may find that you encounter

●

“Bubbler” block

difficulty when joining the salt bridge to the sides of the other tubs—often lots of epoxy and or

●

Epoxy resin adhesive

silicone is required, and it is hard to get a good

●

Bung or plug for P-trap top pipe or cooking oil

leak-free join.

If you’ve got a little bit of money in your

experimenter’s budget, nip to your local plumber’s supply outlet, and ask for a couple of P-traps—these are the gadgets that fit underneath your washroom sink, and prevent nasty smells coming up from the

●

Scissors

drain. These provide an easy method of joining the

●

Junior hacksaw (for cutting plastic)

salt bridge to them, as they come with a coupling,

●

Stove

with a rubber gasket to ensure tight, leak-free

Project 31: Building Your Own Microbial Fuel Cell ● Pan joins.

108

Project 31: Building Your Own Microbial Fuel Cell run a bit of tape around as well to secure. Place the tube sealed end down.

Now, put the pan of water on the stove. You are

going to need about 125 ml of agar solution to fill your salt bridge. However, for practicality you may need to make more than this in order to heat evenly in your pan. As a ready reckoner, for every liter of water, you’re going to need about 100 g of agar.

Add the agar once the water is boiling, and then throw in some salt.

When you’re done, and before the solution starts Figure 9-1

Trial assembly of the P-traps and salt

to gelify and set, pour the mixture into the 4 in.

bridge pipe.

100 mm length of tube you just covered with

plastic wrap, and allow it to solidify and set.

When you have allowed the jelly to set completely, To get the best out of a P-trap, you will see if loosen off the clamps on either end of the P-traps, you open them up that there is a plastic pipe

squeeze the ends of the pipe into the fixing, and extending into the cavity inside the trap. To make tighten the clamps up. The rubber gasket trapped as much room as possible for your experiment,

between the big nut and the P-trap will ensure

take a multitool such as a Dremel, and remove this a good seal with no leaks.

plastic protrusion, giving you an empty chamber to work with.

You can see in Figure 9-1 what a neat solution a pair of P-traps and short length of waste pipe make for constructing MFCs.

Making the salt bridge

Our salt bridge separates the reduction and oxi-

dization sides of our microbial fuel cell, while connecting them electrochemically. The salt bridge will allow a flow of ions between the two chambers of our MFC.

It consists of a simple tube, filled with a mixture of salt and agar for gelification. If you’re wondering where to get agar from, it is sometimes used as a vegetarian substitute for gelatin, or you might be using it in the science lab to grow cultures on.

To make the salt bridge, you’ll need to take the short length of pipe, and wrap one end firmly with several layers of plastic wrap to seal it. Ensure that you make a good seal, and use several layers of the wrap pulled taught over the end. You could even

Figure 9-2

Aquarium aerator “air brick.”

109

Making the electrodes

Take two sheets of carbon cloth, and fix a piece of wire to them. An epoxy resin glue is good for this.

You want to ensure that there is conductor to

carbon cloth contact, and that the glue doesn’t

interfere with this interface. The glue is applied over the joint between the carbon cloth and wire, not between it.

Test the connection between the wire and

Figure 9-3

With and without aerator bricks.

electrode using a multimeter set to the resistance setting. The reading should be very low.

in a glass (see Figure 9-3). When the plain pipe Obtaining the bacteria for

has air blown through it, there are a small number your fuel cell

of large bubbles, however, when the aerator brick is added, there are a large number of small bubbles.

You are going to need to find some bacteria for

your fuel cell. You can experiment with different This is important, because it is the surface area cultures of bacteria, but it is essential that when of the bubbles in contact with the water that we are you are collecting them, you preserve your own

trying to maximize to increase the rate of the

health by wearing gloves. You could try collecting reaction.

sediment from a river.

We are going to try to exclude oxygen from our

Powering up your MFC

anode, and in our cathode, we are going to try and create an oxygen-rich environment, using an aquar-Remember that you marked one chamber “A” for

ium aerator—a small pump that blows bubbles into anode and another “C” for cathode. Well, this is an aquarium to keep the little fishies happy!

important now as you are going to need to add the You are going to need to exclude oxygen from

right mixtures to the right chamber.

the anode chamber. There are a couple of ways of To the anode:

doing this. You can get some sort of bung or cap, You are going to add the inoculum—this is our

or another alternative is to float some oil on top of bacterial mix.

the bioconvertable mixture, which will prevent

To the cathode:

oxygen from reaching it. Water and oil are not

miscible, and the oil will just float on top of the We are going to add some electrolyte—salt

water-based solution.

water solution.

The pump forces air down a small piece of

Connect a multimeter to the terminals of your

aquarium tube; however, we also need an additional MFC—a really easy way to do this is to solder

device on the end of the tube called an “air brick.”

some banana plugs onto the ends of your multimeter The air brick (Figure 9-2) is a small piece of

leads, so you can connect them directly to a meter.

porous ceramic that takes the feed of air coming Looking a little closer, we can refer to Figure 9-5

from the aerator, and breaks it up into a plethora of for a diagram of what is going on. Figure 9-5 is a little bubbles. The effect of an aerator brick can simplification of our P-traps and assembly, and it Project 31: Building Your Own Microbial Fuel Cell clearly be seen by looking at the pipe submerged schematically represents the MFC. In our anode

110

Project 31: Building Your Own Microbial Fuel Cell Figure 9-4

The completed microbial fuel cell.

chamber, we have our bacterium, isolated from air and our anode electrode.

Inside, the bacteria are digesting food and, in the process, giving up electrons to the anode terminal.

Figure 9-6

Geobacteraceae bacterium.

The anode is “gaining” electrodes; therefore, a

process of reduction is happening at this electrode.

Here, oxygen is being bubbled through an

The bacterium that we use in this fuel cell

electrolyte solution.

(Figure 9-6) must be a mediatorless bacterium, as At the other electrode, we are bubbling oxygen

we did not add any additional chemicals to “mediate”

through an electrolyte. The cathode electrode is the transfer of electrons from the bacterium to the losing electrons, therefore “loss equals oxidation.”

electrode.

Remember LEO the Lion goes GER? Loss of

Electrons is Oxidation, and Gain Equals Reduction.

So by losing electrons to the electrode, the process of oxidation is occurring. The electrons then make their way around the circuit to the cathode.

Figure 9-7

LEO the Lion goes GER—a great way to

remember “Loss of Electrons Equals Oxidation” and Figure 9-5

Diagram of the microbial fuel cell.

“Gain Equals Reduction”

111

microbial fuel cells make for very successful

science fair projects, and being so new, there is exciting research that can be done by amateurs.

I urge you to take a look at Abbie Groff’s award-winning microbial fuel cell research. When I began reading around this subject, Abbie Groff’s work

shaped a lot of my direction with this project:

www.geocities.com/abigail_groff/

Here are some of Abbie’s press cuttings, resulting from her forays into the world of microbial fuel cells—discover something new and this could

Figure 9-8

The reduction–oxidation cycle.

be you!

www.engr.psu.edu/ce/enve/mfc-

Logan_files/PDFs/Student%20MFC%20papers/

So we can see how the reduction–oxidation cycle

Abbie%20Groff4.pdf

is complete, with one electrode reducing, while the other is oxidizing. The salt bridge provides a

Sikander Porter-Gill’s project also makes for

means for ions to flow between the two chambers

interesting reading:

while isolating the two solutions.

www.engr.psu.edu/ce/enve/mfc-

Mediatorless microbes transfer electrons directly Logan_files/PDFs/Student%20MFC%20papers/

to the electrode, without the need for an electron MFC-Sikandar.pdf

shuttle.

Erik A. Zielke also has some interesting work:

www.engr.psu.edu/ce/enve/mfc-

Other students’ fuel cells

Logan_files/PDFs/Student%20MFC%20papers/

Engr_499_final_zielke.pdf

There are a plethora of good microbial fuel cell Penn State University has a fantastic microbial

projects on the Internet. To all intents and purposes, fuel cells resource page (www.engr.psu.edu/ce/

enve/mfc-Logan_files/mfc-Logan.html), and if you build an MFC like the one featured here, they want to hear from you! If you get a successful MFC

project, send some details to blogan@psu.edu

Microbial fuel cells—with

mediator

Mediatorless microbes transfer electrons directly to the electrode, without the need for an electron

shuttle. The MFC we have created is a mediatorless microbial fuel cell because there isn’t an additional chemical to “mediate” between microbes and

Project 31: Building Your Own Microbial Fuel Cell Figure 9-9 Mediatorless transfer.

electrodes (Figure 9-9).

112

Project 31: Building Your Own Microbial Fuel Cell University kit, yeast is used as the bacterium, and methylene blue is used as the mediator, shuttling electrons between the bacteria and the electrodes.

Reading University has published information

about their microbial fuel cell in the online journal, Bioscience-Explained. You can download this information from www.bioscience-explained.

org/EN1.1/pdf/FulcelEN.pdf

Further Investigation

Figure 9-10

Mediator MFC.

●

H.P. Bennetto (1990) Elecricity generation

from micro-organisms: www.ncbe.reading.

There is another type of microbial fuel cell—the ac.uk/NCBE/MATERIALS/MICROBIOLOGY/

mediator MFC, where an additional chemical acts

PDF/bennetto.pdf

to shuttle the electrons from the microbes to the

●

H. Liu and B.E. Logan (2004) Electricity

MFC. This is illustrated in Figure 9-10.

generation using an air-cathode single chamber

Reading University’s National Centre for

microbial fuel cell in the presence and absence

of a proton exchange membrane: www.engr.psu.

Biotechnology Research has produced a very

edu/ce/enve/publications/2004-Liu&Logan-

compact microbial fuel cell kit. The kit is based on ES&T.pdf

the principles discussed in Peter Bennetto’s paper (1990).

Look at Figure 9-10—this is what happens inside

a fuel cell which requires a mediator. In the Reading 113

This page intentionally left blank

Chapter 10

High Temperature Fuel Cells

In this book so far, we have chosen experiments

High-temperature fuel cells can be used in

which can be performed with relative safety at

stacks, like the stacks we saw in the PEM fuel cell.

home. The type of fuel cells that we have looked at In Figure 10-1, we see a solid oxide fuel cell stack—

can be classed as “low-temperature fuel cells”;

the stack is made up of a sandwich of platters,

however, there is another class of fuel cells

a separator plate, followed by an anode plate, an that is suited towards different applications—

electrolyte plate and a cathode plate. The sequence

“high-temperature fuel cells.”

then repeats. Fuel is supplied through a central pipe, with additional air being supplied by the two Take a look at Table 10-1. Here we can see the

pipes either side of the center.

five main classes of fuel cells. Note that in this table, we group DMFCs with PEM fuel cells, as

Of course, because high-temperature fuel cells

both operate on a membrane principle.

require additional support equipment, the inventory of components required to support a high-Unfortunately, because they operate at high

temperature fuel cell extends beyond the stack

temperature, it is not practical to construct or exper-itself. We can see in Figure 10-2 a small 1-kW

iment with them, but we do at least owe them the solid oxide fuel cell stack (the same one as we saw duty to discuss them, so that your knowledge of

in Figure 10-1), in the lab with its associate support fuel cell technology is complete.

equipment.

Table 10-1

Comparison of fuel cell technologies.

Molten

Phosphonic acid

carbonate

Solid oxide

PEM fuel cell

Alkaline fuel cell

fuel cell

fuel cell

fuel cell

Electrolyte

H+ ions in a

OH− ions in a KOH

H+ ions in a H PO

CO− ions in

O− ions in a

3

4

3

polymer

solution

solution

a molten

ceramic

membrane

carbonate matrix

with

eutectic

free oxide ions

—

—

Ability to reform

fuels internally?

Oxidant: air

—

Purified

—

—

—

Oxidant:O

—

—

2

Ideal operational

65–85° C

90–260° C

190–210° C

650–700° C

700–1000° C

temperature

150–180° F

190–500° F

370–410° F

1200–1300° F

1350–1850° F

System efficiency

25%–35%

32%–40%

35%–45%

40%–50%

45%–55%

contaminated by:

CO, S, NH

CO, CO S, NH

CO, S

S

S

3

2

3

115

Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.

Figure 10-2

Solid oxide fuel cell stack and support

equipment in the lab. Image courtesy Technology Figure 10-1

Solid oxide fuel cell stack.

Management Inc.

Image courtesy Technology Management Inc.

Also, because of the high temperatures associated with high-temperature fuel cells (it’s all in the name!), there is a certain amount of support

equipment that means that for very small amounts of power, high-temperature fuel cells just aren’t economical. To give you an example, high-temperature fuel cells don’t get a lot smaller than the device shown in Figure 10-3, a 1-kW solid

oxide fuel cell stack with support circuitry.

We are going to take a look at three high-

temperature fuel cell types, and briefly cover some aspects of the technology.

Phosphoric acid fuel cells

In a phosphoric acid fuel cell (PAFC), the electrolyte is retained by a matrix of silicon carbide, which keeps the highly concentrated phosphoric acid

in place.

Figure 10-3

1-kW solid oxide fuel cell stack.

High Temperature Fuel Cells

116

High Temperature Fuel Cells

If you are still interested in phosphoric acid fuel cells, and want to find out more, you could check out some of these top Web links as a springboard to further information:

www.fctec.com/fctec_types_pafc.asp

www.nfcrc.uci.edu/EnergyTutorial/pafc.html

Figure 10-4

Phosphoric acid fuel cell chemistry.

www.fossil.energy.gov/programs/powersystems/

fuelcells/fuelscells_phosacid.html

americanhistory.si.edu/fuelcells/phos/pafcmain.htm The reason for the high temperatures of phosphoric Molten carbonate

acid fuel cells is that at lower temperatures,

phosphoric acid proves to be a poor conductor of fuel cells

ions. Furthermore, at lower temperatures, the fuel cell is more readily poisoned by carbon monoxide.

Molten carbonate fuel cells also operate at very high temperatures. Their electrolyte is a molten Also, phosphoric acid solidifies at 40∞ C or

carbonate salt mixture, suspended on a ceramic

104∞ F, which means that cold-starting of PAFCs

matrix. In current MCFC fuel cells, two mixtures can be rather tricky. To eliminate this operation of carbonates are currently used: lithium carbonate complexity, PAFCs are usually used in applications, and potassium carbonate, or lithium carbonate and e.g., in buildings, where they can be installed

sodium carbonate.

and operate continuously without the need for

cold-starting.

As a result of the high temperatures that MCFCs

operate at, it is not necessary to use platinum as a In addition to building integrated PAFCs, promise catalyst; instead, other cheaper metals, such as has also been shown in utility-scale applications nonprecious metals, can be used.

where PAFCs can be used as mini power stations,

producing supplemental power for the grid.

Additional heat produced from the PAFC

operation must be removed. This can be done by

incorporating coolant channels into the coolant

stack—not unlike the coolant channels that run

through the internal combustion engine in your car.

Either liquid or gas can be passed through these channels to cool the PAFC.

Phosphoric acid fuel cells are one of the most

mature fuel cell technologies. They are very well understood, and used in commercial operations at a number of sites.

Figure 10-5

Molten carbonate fuel cell chemistry.

117

Molten carbonate fuel cells can reach very high

efficiencies—even higher when waste heat produced Solid oxide fuel cells

by the fuel cell is captured. This heat can be used for other processes or heating, which means more As a result of the very high temperatures that they useful energy is delivered to the application and operate at, solid oxide fuel cells are primarily less is wasted.

suited towards stationary applications. The gases Other fuels can also be internally reformed,

that are produced by SOFCs are so hot that, on

which presents flexibility in the range of fuels that their own, they can be used to power a gas turbine.

can be used.

Further low-grade heat can then be recovered after As a result of the high temperatures, MCFCs are

the turbine for heating purposes.

resistant to poisoning by carbon monoxide and

SOFCs must run at very high temperatures, as carbon dioxide. However, sulfur in fuels still

the materials they are made from only become

presents a problem and must be scrubbed from the electronically and ionically active at very high fuel before it is supplied to the MCFC.

temperatures.

As a result of the high temperatures required,

Like the MCFCs, because of the high

these cells take some time to start up, and require temperatures required, these cells take some time some thermal shielding or insulation to be added to to start up, and require some thermal shielding or the cell to ensure that it operates efficiently.

insulation to be added to the cell to ensure that it One of the problems that needs to be surmounted

operates efficiently.

at the moment is the durability of MCFCs: some of As a result of the very high temperatures

the materials that they use in the electrolyte are highly that SOFCs operate at, poisoning of the fuel

corrosive, and as a result of this, and the fact that cell by carbon monoxide is not an issue. However, these cells are operating at a very high temperature, sulfur must be scrubbed from the fuel supply as

premature component failure can result.

SOFCs are still susceptible to sulfur poisoning.

If you want to learn more about molten carbonate fuel cells, the following are some super links to sites with high-quality content that you might like to check out:

www.fctec.com/fctec_types_mcfc.asp

www.fuelcellmarkets.com/fuel_cell_markets/mol

ten _carbonate_fuel_cells_mcfc/

www.fossil.energy.gov/programs/powersystems/

fuelcells/fuelcells_moltencarb.html

en.wikipedia.org/wiki/Molten-

carbonate_fuel_cell

dodfuelcell.cecer.army.mil/molten.html

americanhistory.si.edu/fuelcells/mc/mcfcmain.htm www.nfcrc.uci.edu/EnergyTutorial/mcfc.html

High Temperature Fuel Cells

Figure 10-6

Solid oxide fuel cell chemistry.

118

High Temperature Fuel Cells

As a result of the solid oxide fuel cell’s tolerance to poisoning, and its ability to reform fuels within the fuel cell, it is suited to a wide range of

different hydrogen-containing fuel sources.

Shared with the molten carbonate fuel cell, one

There is a wealth of material about solid oxide

of the advantages of the solid oxide fuel cell is that fuel cells on the Web. Here are some links to

it can reform fuels in situ, which means that we pages with high-quality information:

can supply it with a supply of natural gas direct www.svec.uh.edu/SOFC.html

from the gas pipeline, and it will reform the gas www.fossil.energy.gov/programs/powersystems/

itself, with no need for an intermediate stage.

fuelcells/fuelcells_solidoxide.html

This provides additional flexibility for some

www.iit.edu/~smart/garrear/fuelcells.htm

applications.

www.azom.com/details.asp?ArticleID=919

119

This page intentionally left blank

Chapter 11

Scratch-Built Fuel Cells

If you have got this far in the book, the chances are common places. Until you get confidence with

you now have the armory of knowledge required to building fuel cells, it’s probably a good idea to start thinking about building your own fuel cells start from one of these template layouts, using

from scratch. In this chapter, we are going to look stock components to begin with, and then fabricating at some of the skills required to build membrane new components as you gain in confidence. This

fuel cells.

has the benefit of you being able to take dimensions If you haven’t already had the chance, take a

from the old components as patterns, modifying

peek at the chapter on direct methanol fuel cells parameters one by one, and seeing what effect

(Chapter 8), and the project “Build Your Own

it has on the fuel cell’s performance.

Band-Aid® Fuel Cell.” It was in devizing this

project that I began to realize how simple fuel cells really are—simply a sandwich of components in

the right order, made from the right materials.

Scratch-built fuel cell

Although the construction is fairly simple, the

skill of manufacturing fuel cells is to ensure that components

all components are optimized—this is the challenge of manufacturers, who every day are working on

End-plates

ways to make fuel cells smaller and cheaper.

In this chapter, we are going to briefly explore The job of the end-plates in a fuel cell is to be some of the tools, techniques, and materials of

rigid enough to firmly support the internal compo-scratch-built fuel cell fabrication. The ease of nents of the fuel cell, to provide a fixing for the building your own fuel cells from scratch is that hydrogen and oxygen supply connections, and to

many of the components are available as premade

provide a surface for the fixings that secure the off-the-shelf items, if you don’t want to totally fuel cell sandwich together to screw down on.

start from scratch, but as you gain skills, experience, A wide variety of materials are suitable for

and confidence, you can begin to build more compo-end-plate construction. You might want to consider nents and vary the balance between off-the-shelf using an electrically insulating material for the and homemade—to the point where you can then

end-plate, to ensure that it doesn’t provide a path start from raw materials and turn out commercial-for stray electrons to short on. Fiberglass sheet is grade fuel cells.

an ideal material to produce end-plates from, as it We are going to start at the ends of our fuel cell is strong, robust, and can be easily worked. Some and work our way in.

plastics are suitable for end-plate construction, It is possible to make fuel cells in a variety of however, you must ensure that they are sufficiently shapes and sizes, however, there are some

rigid, as a material with too much bend will not components available which follow a standard

provide the mechanical support the MEA needs

sizing, and have holes and membrane areas in

through the center of the stack.

121

Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.

The end-plate also needs to have a suitable

fixing for hydrogen and oxygen supplies and

return feeds. A simpler construction of fuel cell will use hydrogen and air, in which case pipes for oxygen do not need to be provided. If you think

back to the fuel cells you have been using in the chapter on PEM fuel cells, they all have their

integral fixings molded as part of the plastic end-plate. However, if you are working from a fiber-

glass sheet, you will need to find a way to affix a connection to the plate.

You will see that the end-plate in Figure 11-2

has four holes at the corners for fixings, and two connections for hydrogen and return gas at the top in the center of the plate.

Figure 11-1

Fiberglass sheet suitable for end-plate

The positioning of your holes and gas feeds can

fabrication.

differ slightly—this is just an example. As end-

plates are one of the easier parts of the fuel cell You want to ensure that the material does not

stack to manufacture, it is probably best to design bend significantly, as you want pressure to be

them around any available flow fields, rather than spread from the screws or clamps at the outside of the other way around.

the cell, to the center of the cell, where the end-If you haven’t got the facilities, or you haven’t plates maintain the electrodes’ contact with

got the patience to sit and make your own end-

the MEA.

plates, the Fuel Cell Store sells some ready-

manufactured end-plates, with holes in the right If producing your end-plates sounds like too

much trouble, Fuel Cell Store sell a set of end-

plates with mounting components for a 10 cm ×

10 cm fuel cell stack–Part No: 590300.

To produce an end-plate, start with a fiberglass sheet, such as that shown in Figure 11-1. The Fuel Cell Store sells a garolite (fiberglass and epoxy) sheet that is suitable for end-plate construction.

Their stock number is 72043001.

The end-plate needs to have holes for nuts and

bolts to be inserted through, which are then tightened to provide pressure on the stack. Another alternative Scratch-Built Fuel Cells is to use a threaded rod with nuts on either end.

Figure 11-2

An example end-plate.

122

Scratch-Built Fuel Cells

The hydrogen distribution design remains similar for both types of fuel cell—you take the hydrogen from a common point which feeds from the barbed

tube connector at the end of the fuel cell, and using a flow field channeled in the graphite, you provide a passage for the hydrogen to spread over the surface of the MEA. You can see an example hydrogen

flow field plate in Figure 11-4.

Notice how there are four holes on the outside of the plate at each corner: these are to provide the manner of fixing the fuel cell together, with bolts passing through all the plates and the entire assembly. Meanwhile, you will notice two small holes

at the top of the plate—these are to connect the serpentine pattern, which we can see below, to two Figure 11-3

Gas connection.

common channels which provide connection to the

hydrogen feed.

places for their ready-made flow fields. The

If your fuel cell is to run on hydrogen and oxygen, end-plate kit comes with barbs for gas already

you will want to take a similar pattern to Figure fitted, and a set of eight insulated fixings to hold 11-4, but with the holes positioned in a different the fuel cell together. The stock number is 590300.

place for an oxygen feed. This will then take a

There are a number of different fixings for gas

supply of oxygen, attached to a barb fixed in the connections. It is important that you can make a opposite end-plate in a different position, and

good leak-proof joint between the “barb”—the bit distribute the oxygen over the opposite side of the that sticks out to interface with the pipe, and the MEA to the hydrogen.

end-plate. Some barbs will simply screw into the end-plate, while others may require some epoxy or other form of adhesive.

Graphite flow fields

The next component inbetween your end-plates

is the flow fields. It is the flow fields that take the gases from the common feeds machined

throughout your fuel cell stack, and distribute

them evenly over the MEA. In addition to the

mechanical function of helping distribute the gas, and providing physical support to the MEA, they

also have the electrical function of providing a contact to the gas diffusion membrane to allow the power to flow!

You need to make a decision as to whether your

fuel cell is to run on hydrogen and air, or hydrogen and oxygen.

Figure 11-4

Hydrogen flow field plate.

123

You can buy ready-machined flow field plates

which take the hassle out of making your own.

They are available from Fuel Cell Store—this Web link will show you all their ready-made plates:

www.fuelcellstore. com/cgi-bin/tornado/

view=NavPage/cat=58.

If you are building a single-cell fuel cell, you will require one anode plate, with channels on one side, and one cathode plate, with channels on one side. However, if you are making a fuel cell stack, you will need to employ “bipolar plates.” A bipolar plate has the channels cut out on one side for

hydrogen and the channels cut out on the other

side for oxygen (or air). It acts as an electrical Figure 11-5

Flow field plate suitable for a hydrogen-

conductor, allowing power to be transmitted down air fuel cell.

the length of the fuel cell stack, while also providing a method to keep the hydrogen and oxygen gases

separate. The bipolar plates fit in between the end anode plate and the end cathode plate.

If your fuel cell is to run on hydrogen and air, If you are looking at producing your own flow

you will use straight plates on the “oxygen side” to field plates, you will need to start with a plain allow air from outside the fuel cell to flow along carbon block, cut to the dimensions of your fuel the straight channels to make contact with the

cell. In terms of thickness, you need to allow

MEA. There are no tubes, the air enters the fuel enough material to be moved when you are milling cell at the bottom and leaves at the top. Natural the channels for the gas to flow through. If you convection currents created by the generation of look at Figure 11-6, you will see a plain carbon any excess heat can help to increase the circulation plate suitable for the purpose.

of air. A straight plate is shown in Figure 11-5.

You can buy blanks ready for your own machining

Additionally, you could experiment with forced

and treatment, or you can cut your own from a

ventilation, attaching a fan to one side of the stack block of graphite. Before cutting slices, square to increase the throughput of air.

(or rectangle) from your raw block of graphite,

ensure that you check the sides for parallelism.

Graphite is a lovely material to work with—it’s

really nice and soft to mill into, so you don’t need especially flash equipment to cut the flow channels into it. Consider when working with your graphite that a little bit of water will aid the cutting process and keep the workpiece cool. Graphite is a good

lubricant, so you won’t need cutting fluid—just

If you want some ideas for different patterns for something to keep the dust down and remove

your flow fields, take a peek back at Figures 7-10

the heat.

for straight, Figure 7-11 for interdigitated,

Figure 7-12 for serpentine, and Figure 7-13 for

When drilling or milling the graphite plate, set spiral—for inspiration.

your drill or mill to the slowest speed possible.

Scratch-Built Fuel Cells

124

Scratch-Built Fuel Cells

becomes a tiresome exercise—there’s also a

distinct possibility that if making the flow-fields manually, there will be some operator error then, and they might not all line up correctly.

The pièce de resistance of manufacturing flow fields is to invest in a CNC cutting machine. CNC

stands for computer numerical control—it’s the lazy man’s solution, as it allows you to create a design in a computer-aided design package, and send it to the machine, which will then mill the material as dictated by the pattern.

Increasingly, you will find CNC machines in

well-equipped schools and college design and

technology departments, so if you’re friendly with a teacher or technician, you may be able to

Figure 11-6

Plain graphite plate suitable for flow field manufacture some flow fields.

construction.

Alternatively, there are some fairly simple CNC

kits, such as from Parallax, which is a simple CNC

You do not need to work at high speed when

machine for light hobby work. It is eminently suited machining graphite.

for this kind of work, which is very lightweight.

The machine is much more affordable, by a number When considering tools, you have a number of

of orders of magnitude, than commercial CNC

options. Probably the simplest is to use one of the machines, and will find other applications in an handheld multifunction tools, such as the Dremel Evil Genius’s workshop!

Multi, which offer a wide range of heads and attach-ments for different purposes. This will enable you You need to ensure a good interface between the

to manually route out a groove in the carbon—you graphite flow field and the MEA, so you want to

can then drill your holes using a small bench-top ensure that the surface of your flow field is as pillar drill.

smooth as possible. Wet and dry paper is a good

If you’ve got access to a more sophisticated work-way to remove imperfections—start with coarser

shop, you could consider using a milling machine, grits working down to a 600 grit. One thing is

to enable you to make accurate straight lines for essential—work with a flat-bottomed sanding

your serpentine pattern. For those of you who are block, as it is absolutely critical that parallelism now lost, with a milling machine, you can clamp

is maintained on either side of the flow field

the workpiece on a flat bed, and you have a number plate.

of controls—if you think of the old Etch A Sketch machines, you have two knobs: an X and a Y, and

they allow you to draw lines with the cutting tool.

Membrane electrode assemblies

The difference is that you can also start and stop the line by raising the milling bit, Z.

In a membrane-based fuel cell, it is the assembly Now, this is all well and good for single flow

of membrane as gas diffusion electrodes that you fields; however, if you are building a fuel cell will understand does all of the work. It is at the stack, the chances are you will quickly find this junction between membrane, platinum, and electrode 125

Figure 11-8

Always remember to handle MEAs with

cotton gloves.

Figure 11-7

An off-the-shelf MEA.

that the chemical reactions vital to the fuel cell’s gives wider scope for experimentation and new

operation take place. We saw in the chapter on PEM

learning.

fuel cells how this happens.

The chemical coating of an MEA is very sensitive It is possible to buy the MEA as a ready-fabricated to pollutants and very fragile. For this reason, when component, however, by making your own, you

handling MEAs—shop bought, or making your

gain a greater degree of control over the materials own—always ensure that you wear fine, clean cotton used in the performance of your MEA, you

gloves as they ensure that you will not damage the can make custom sizes, and are able to produce

MEA. Handle them carefully, as they are very deli-MEAs at cheaper cost. Also, by making your

cate, and try and hold them around the edges if

own, it is possible to have much greater control possible, rather than making contact with the black over the coating process—this additional flexibility central portion.

Project 32: Making Your Own MEAs

For the hardcore fuel cell experimenter, you might An MEA consists of a proton exchange mem-want to have a go at making your own MEAs. In order brane, Nafion™ from Du Pont is commonly used.

to do this, you are going to need some pretty sophis-This is sandwiched between either a cloth or paper ticated materials and some relatively cheap tools.

impregnated with carbon. This forms our GDL or

To recap for those that have forgotten our little gas diffusion layer. To recap, the GDL allows our journey down PEM avenue, MEA stands for

gas and water to move to and from the platinum

Project 32: Making Your Own MEAs Membrane Electrode Assembly.

catalyst.

126

Project 32: Making Your Own MEAs

post, resist the urge to get it out and start playing with it, as it is easily damaged.

You can obtain both Nafion sheet, and Nafion

membrane from Fuel Cell Store—this website link

takes you to all their Nafion™ products:

www.fuelcellstore.com/cgi-bin/tornado/

view=NavPage/cat=97

If you can do this at a school or college chemistry lab, then use a fume cupboard—this will ensure

that you are not harmed by the vapors from the

boiling hydrogen peroxide or sulfuric acid.

However, if you do not have a fume cupboard,

ensure that you do this activity outside in a well-ventilated area to ensure your safety. Make sure that you wear protective clothing while carrying Figure 11-9

A bottle of Nafion™ solution.

out this activity—some thick acid-proof gloves or gauntlets will ensure that your hands and arms

don’t come into contact with boiling acid. Ensure We will be using Nafion™ solution in the

that you are wearing safety specs, use a protective construction of our own MEAs—this can be

apron, and ensure you are wearing fairly thick

purchased in a variety of percentage solutions.

clothing to cover up your arms and legs.

You will also need some Nafion™ membrane

In the event of a splash, turn off the heat, and go in sheet form. Remember, when it arrives in the

indoors immediately, take the affected piece of

clothing off, and use water to make sure that no chemical is in contact with your skin for too long.

You will need to prepare your Nafion membrane for use in your fuel cell. You will need a double-boiler, sometimes called a Bain Marie, which you will not be using again for food, as we’re going to be using some nasty chemicals in it.

You can make a Bain Marie simply from labo-

ratory glassware—it just consists of a larger pot which can be heated to the point of water boiling, with a smaller pot inside which is heated indirectly by the hot water. The intermediate step of heating the water gives you finer control over the temperature, and a more even distribution of heat, which Figure 11-10

A sample of Nafion™ membrane.

is useful in this application.

127

It is also handy if you have a setup where you

fully immersed in the water, as its tendency will be can heat two pots at the same time, as this will to float up.

allow you to begin to bring another bath up to

Towards the end of the hour, you need to bring

temperature, while the one the MEA is currently in another pot—this time with 3% peroxide

is coming to the end of its cycle.

solution—up to temperature (176∞ F or 80∞ C

again). Transfer the membrane from one pot to the next, and maintain the temperature for an hour.

The membrane may be tricky to transfer—being

transparent it’s hard to see, and you’ll probably find it slippery to handle. There are three golden rules:

Warning: a metal Bain Marie is not suitable for

this experiment—you need to ensure that you are

1. Don’t drop the membrane.

using glass or something inert which will not

2. Don’t puncture or scratch the membrane.

react with the hydrogen peroxide or

3. Don’t use a metal object to retrieve the

sulfuric acid.

membrane.

Take the pot you used for the initial distilled

You will also need a thermometer capable of

water bath, and transfer a quantity of sulfuric acid measuring relatively high temperatures—don’t be

into this pot. Bring it up to the temperature of tempted to use a standard glass thermometer—dip

176∞ F or 80∞ C.

the end in the hot, boiling water, and you will

Take the membrane out of the hydrogen peroxide,

certainly have damaged your thermometer—it might and allow as much of the fluid to drip from the

even crack, leaving the mercury or alcohol to leak membrane as you can, and then immerse the

out. One place you could start your search for

membrane in the sulfuric acid. Use the glass rod high-temperature thermometers is online, looking again to ensure that the membrane sits below the at supply stores for home sweet or candy makers.

surface of the hot liquid. Once this has been heated You are going to need to cut a uniformly sized

for an hour, we will be washing the membrane in piece of Nafion™ for each MEA in your fuel cell

three distilled water baths at 176∞ F or 80∞ C.

stack.

Once this process is complete, allow the membrane to dry—ensure that it doesn’t come into contact

Cut your carbon cloth or paper, so that it is slightly with anything metallic, and ensure that the air can smaller than the Nafion™ membrane, giving it a

get to it.

border which can be used to mount the membrane

as part of a larger sheet of gasket.

To prepare the membrane, you will need 3%

hydrogen peroxide solution, sulfuric acid, and

plenty of distilled water.

We will be filling the larger pan of the Bain Marie Remember when you are finished with your

with water, which we will bring to the boil. The sulfuric acid to dispose of it in a sensible,

smaller pan which sits inside the pan will start off responsible manner. Do not store it in any kind of with distilled water. You need to immerse the MEA generic container that could be mistaken for a

in this water, at a temperature of 176∞ F or 80∞ C

food item or cleaning product—make sure you

to hydrate the membrane for a period of around an store it responsibly in a clearly labeled container.

Project 32: Making Your Own MEAs hour. Use a glass rod to ensure that the MEA is 128

Project 32: Making Your Own MEAs

Preparing the GDL

Remember the gas diffusion layer? Well, you’re

going to have a choice of either using carbon

paper, as shown in Figure 11-11, or carbon cloth, as shown in Figure 11-12.

The gas diffusion layer is a carbon impregnated

cloth or paper, with a high concentration of platinum which acts as a catalyst. For the home fuel cell experimenter, there are a number of ways that we can prepare the GDL.

For a range of GDL materials, check out Fuel

Cell Store’s page at: www.fuelcellstore.com/

cgi-bin/tornado/view=NavPage/cat=56

We’re going to discuss a few different options

Figure 11-12

A sample of e-Tek gas diffusion layer.

for transferring the catalyst to the carbon cloth or paper.

You’re also going to need some platinum catalyst and easy to buy ready-prepared mixtures of carbon to deposit on the interface between your GDL and and platinum powder for your catalyst. This can be the Nafion™ membrane. In this respect, you have

applied to your GDL. You can get jars of anode

an array of options open to you. It is quite handy and cathode paste with varying compositions of

catalysts, which can be applied to your GDL.

Remember, for repeatability, always make fine

measurements of the quantities of chemicals that you are using, so that you can manufacture similar fuel cells in the future. Compare different loadings of platinum catalyst to see how it affects the performance of your fuel cell.

Figure 11-11

A sample of carbon paper.

Figure 11-13

Jars of anode and cathode pastes.

129

measured amounts of platinum compound into

your MEA.

The platinum printing process was developed by

W. Willis in 1873. For fuel cells, it is perfect as it deposits a layer of platinum black onto the MEA—

this is especially useful as platinum black is one of the best forms of platinum for our application.

You won’t find platinum printing kits in your

standard photo shop, as the process is now largely used for art prints, or prints with a very high resale value. However, there are a couple of online

vendors that sell the chemicals for this process.

Figure 11-14

Fine scales for carefully measuring

chemical quantities.

Here is a great source of platinum printing kits, High-voltage deposition

and all the chemicals you need to platinum print are also available individually:

One way in that it is possible to transfer platinum www.photographersformulary.com

to the GDL is through high-voltage vaporization of fine platinum leaf. By passing a very high voltage Follow the instructions in the kit (which may

through a fine wire or leaf of platinum, it is possible differ depending on the supplier). You will need to to vaporize it, and small pieces of platinum will coat your pieces of GDL as if they were photo-be deposited on any adjacent surfaces that are

graphic paper, but rather than enlarging an image close by.

onto them, I suggest:

There are a couple of books that discuss making

●

Leaving them out in the sun for UV

devices to vaporize fine wire in detail:

exposure

●

If you have a UV light box (say for etching

Two books that I can highly recommend:

printed circuit boards), you can use this to

Gordon Mc Comb’s Gadgeteers Goldmine—

expose the piece of GDL.

Gordon Mc Comb, McGraw-Hill, New York

Remember, photographic paper takes a negative

Electronic Gadgets for the Evil Genius— Robert image, and reverses it, so for areas of high-density Ianinni, McGraw-Hill, New York

black, we need to expose the GDL to bright white light. Once you’ve made the exposure, don’t forget that you’ll need to process your GDL using the Platinotype—photochemical

chemicals in the kit, in order to fix the platinum deposition

black.

Platinum is firmly embedded in the history of

Throughout the processing, keep a keen eye on

photography, and as such, platinum printing, while what side you applied the platinum to, as the fuel being expensive, does furnish the potential fuel cell cell will only work if the platinum is in contact Project 32: Making Your Own MEAs builder with a method of accurately depositing with the Nafion™ membrane.

130

Project 32: Making Your Own MEAs

The Fuel Cell Store sells a pair of aluminum

Electroplating

plates suitable for hot-pressing your MEA—the

stock number is 590163.

Another option available to you is to electroplate You will now need to coat your GDL with some

platinum onto your GDL. To do this, you connect

Nafion™ solution. Remember Figure 11-9? Ensure

the GDL to the negative terminal of a power supply, that you do not get any metal in contact with the a piece of platinum scrap to the positive, and

Nafion™—you can get cheap plastic brushes for

immerse the two objects in a solution of platinum coating pastries with egg or kiddies’ art-brushes.

salts.

Just coat one side of the GDL (the side with the www.caswellplating.com sells a wide range of

platinum on)—you don’t need to saturate the

home electroplating kits and accessories; however, carbon cloth or paper, but just ensure that the

they do not supply kits specifically for platinum surface is coated.

plating. Their website has a useful forum, with lots You’re also going to need an oven thermometer,

of information about electroplating with different of the type you use to check that your turkey is at metals, and this would be a good place to start if the right temperature.

you want to investigate platinum electroplating.

Remember that we said earlier what a fantastic

If you have bought the above-mentioned platino-

lubricant graphite was—well, we’re going to need type process kit, you should have some potassium some graphite powder now (see Figure 11-16), to

tetrachloroplatinate included in the kit—this is a ensure that the Nafion™ doesn’t stick to the plates platinum salt, and all you need now is some platinum we are using to clamp the assembly together. This for the anode, which could be a piece of platinum is just like greasing a pan when we are cooking.

leaf.

Rub the graphite into the surfaces of the plates, Platinum leaf

You can transfer platinum leaf very easily to carbon cloth or paper, by simply holding the leaf against the GDL and rubbing hard on the back with a

pointed but not sharp object (e.g., the wrong end of a ballpoint pen).

Putting it all together ...

Once you’ve impregnated your GDL with platinum,

and prepared your Nafion™ membrane, the next

step is to assemble your MEA.

To do this, you are going to need a couple of

stiff sheets of metal and some clamps to apply

pressure between the two sheets. You might find

that you can get a ready-made assembly from a

paper-making kit—the key is, you need to ensure

that the materials are happy being heated in

the oven.

Figure 11-15

Graphite powder.

131

Figure 11-18

Home-built fuel cell (note electrodes and

sandwich construction).

Figure 11-16

Home-built fuel cell (note fixings and

Now bake …

tube barbs).

Using the oven thermometer to check the temper-

which will be in contact with the clamped MEA

ature is accurate (never rely on the temperature assembly.

indications on your oven dial—they’re not accurate Graphite powder is available in small bottles

enough), bake at 194∞ F or 90∞ C for an hour, and from Fuel Cell Store—the stock number is 590263.

then slowly over the course of the next half an

hour, turn the knob on your oven up to 266∞ F or We’re now going to assemble the MEA—this is

130∞ C. After the sandwich has been in for an hour a bit like putting a burger together. First, place the and a half, whip the lot out, tighten the clamps first piece of GDL platinum side up in the center even more (using tea towels and oven gloves to

of one of the plates. Lay the Nafion™ membrane

avoid serious burns). Now, put the sandwich back over this, ensuring that it overlaps on all sides, and in your oven, and whack the temperature control up then lay the final piece of GDL on top, platinum to its maximum. Watch the oven thermometer

side down. Carefully place the final plate on top, carefully—we want to get the oven up to 266∞ F or graphite side in contact with the piece of GDL, and 130∞ C, but no more! Maintain this temperature for firmly clamp this assembly together.

a couple of minutes. Then switch your oven off,

remove the clamped assembly, and leave it to cool on a trivet until it reaches ambient temperature.

Gaskets

You will need to mount your MEA in a gasket,

which will ensure a good interface between the

MEA and adjacent flow fields, and will also

prevent it from diffusing from one side to the

other. Look for a thin silicone rubber sheet—you will need to cut two pieces, one for either side of the MEA, and use a silicone glue to run a thin

Project 32: Making Your Own MEAs Figure 11-17 Home-built fuel cell, side view.

bead of adhesive around the overlapping piece of 132

Project 32: Making Your Own MEAs

Nafion™ membrane. Remember, your gasket will

need a hole in the middle which is the same size as Fixing it all together

your GDL, holes in the corners to allow the nuts You are going to need some fixings to hold your

and bolts or threaded rods to pass through, and

fuel cell together—you can either use nuts and

holes where the hydrogen (and oxygen if present) bolts, or threaded rods. However, the key is to

gas supply lines are.

remember to insulate the portion of the thread inside Fuel Cell Store sells a range of different materials the fuel cell, to prevent it shorting electrodes and that can be used to manufacture gaskets for your flow fields. This can be simply accomplished with MEA. Look on their website at www.fuelcellstore.

some heat-shrink tubing.

com/cgi-bin/tornado/view=NavPage/cat=62, and

you will see that they sell Teflon, rubber, silicone and Mylar—all suitable materials for different fuel Further reading

cell gasketing applications.

●

Hurley, P., Build Your Own Fuel Cells, Wheelock Mountain Publications Wheelock, VT.

Electrodes

This is an invaluable reference for those wishing You’re going to need a metal electrode at either to take this even further. It expands upon methods end of your fuel cell assembly to tap off the power.

of platinum deposition and constructing MEAs in

There are a couple of ways of doing this. You can much more detail than is within the scope of this use metal end-plates, however, this requires that book, and is a mine of useful information for further you pay great attention to insulating the fixings research.

used to hold your fuel cell together, or you can simply insert a sheet of metal between the end-plate and the flow field at each end.

133

This page intentionally left blank

Chapter 12

Hydrogen Safety

a height. Diesel burns were also responsible for Dangerous hydrogen?

a lot of injury.

The fact that hydrogen is so light means that

Safety concerns or flimsy

when it is lit, it burns “up and away” from you.

myth?

Contrast this to say, petrol, where fumes are heavy, and creep along the ground—the number of car

As with any technology, there is generally a fair mechanics who have received injury from fires

share of urban myths and legends that circulate, igniting petrol vapors that have slowly accumulated which aren’t true, don’t give us useful information, in pits is testament to this. Whereas with hydrogen, and end up cultivating a distrust or fear of a certain so long as there is sufficient ventilation, and room technology.

for it to escape, it will rise up and dissipate.

However, when designing buildings to house

It is the same with hydrogen and fuel cells. In

hydrogen equipment they must not have a “sealed

this chapter, we are going to debunk and demystify cap,” as rising hydrogen can accumulate here.

some of the half-truths surrounding hydrogen, and It’s easy to read into the name of “the hydrogen restore some confidence in the technology. This is bomb” the notion that hydrogen is dangerous.

going to be followed by a coverage of some of the We have all seen the devastating mushroom clouds health and safety aspects you should be aware of that nuclear weapons leave in their wake. Since

when experimenting with hydrogen.

then, the hydrogen bomb has done nothing for the Hydrogen is safe, but with any form of chemical

good name of hydrogen, linking a potential savior or experimentation, it is important to treat all proof our energy future with dangerous nuclear tech-cedures with due care and respect.

nology. The hydrogen bomb contained tritium,

radically different from the hydrogen that would be Hydrogen has got a bit of a bad press from many

used in the hydrogen economy. Tritium is an isotope different sources. For many years, graceful,

of hydrogen, and the sophistication and technology lighter-than-air airships, filled with hydrogen gas, required to make an atomic bomb just isn’t

graced the skies. Following the Hindenburg disaster, accessible. The mechanism that a hydrogen bomb

the airship dropped into relative obscurity. The uses to create its massive devastation involves the hydrogen gas that it was filled with is often blamed fusion of hydrogen atoms, something which is

as the culprit, but the hydrogen burned upward. In quite different from the chemical processes that fact, this is one of the inherent safety features of take place when burning hydrogen, and so the two hydrogen. Because hydrogen burns “upwards” it

should not be confused.

would not have affected the canvas below; however, it has been proved that it was in fact the silver Furthermore, a number of accidents in space

coating of the ship that caused the most damage—

have become linked in the public mind with

this coating was covered with powdered aluminum.

hydrogen—this just isn’t fair!

Testament to this was the fact that out of 37 casu-The Apollo 13 mission in space seems to have

alties, 35 died from jumping to the ground from

mysteriously become associated with hydrogen in

135

Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.

Figure 12-1

The Hindenburg disaster.

many people’s minds—this is another urban myth.

and explosive. I don’t know how much you know

In 1970, on April 11th, NASA launched the

about astronauts, but they don’t get on so well

13th Apollo mission. During the flight, some fans without a supply of oxygen. Luckily, mission

inside one of the ship’s oxygen tanks were turned control were able to work out a solution for the on, and there was a short circuit, setting the fan on astronauts in space, and in true prototype experiment fire. As a result, the oxygen tanks were weakened fashion, duct tape was employed to stick things

together. (See Figure 12-3.) Contrary to popular belief, hydrogen and fuel cells were not in any way y

related to this disaster.

t

While the Apollo 13 mission can be shown not to

e

cast a slur on hydrogen or fuel cell technology, the f

mission does provide a fantastic endorsement for duct aS

tape (a marvelous product!) which saved the day at the last minute by assisting the astronauts in making n

a jerry-rig fix, which safely returned them home.

e

Duct tape is long overdue a presidential Medal of g

Freedom for outstanding service to the world!

o

The Challenger disaster in 1986 also linked

r

hydrogen with safety, and has led many to believe dy

that hydrogen technologies cannot be safe. However, H Figure 12-2 The hydrogen bomb.

NASA have concluded that the disaster was not

136

H

There is a lot of work going into developing

y

strong, robust hydrogen storage tanks that, in the d

case of vehicles, can withstand even the most

r

catastrophic crashes. Sure, hydrogen has the

o

potential to explode, but drivers of petrol vehicles g

have happily exposed themselves to the same risks e

for many decades. Following extensive crash

n

testing, BMW concluded that in a 55-mph impact,

S

hydrogen vehicles are no more dangerous than

a

carbon-based vehicles.

f

One of the considerations that manufacturers

e

take into account is that there can be no accumu-t

lation of hydrogen in the vehicle should a leak

y

develop.

Figure 12-3

Jerry-rigged solution which saved the

astronauts of Apollo 13.

But what if hydrogen leaks from your car?

Research has shown that if hydrogen leaks from a vehicle tank at a rate of 3000 cubic feet per minute and is lit, the temperature inside the vehicle does caused in any way by hydrogen, instead it was

not climb any more than 1 or 2 degrees—vehicles

caused by faulty “O-rings.”

get hotter than this sitting in the sun!

Fortunately, all of these instances do not relate This is because hydrogen produces little radiant to how hydrogen would be used in a hydrogen

heat. When a carbon-based fuel burns, particles

economy, and any speculation arising from these

of hot carbon (soot) transfer heat to the

events can be discounted as hysterical overreaction.

surroundings—with hydrogen there is no soot and

so less radiant heat transferred.

Hydrogen is already used extensively in industry, where safe methods for the transportation and

Hydrogen safety

storage of hydrogen have been developed.

in vehicles

The recent Buncefield Oil Depot disaster in the

UK, and countless other accidents around the

Any fuel which embodies a lot of energy in a small world involving oil, have highlighted the dangerous space has the potential to cause danger. If we fill nature and shortcomings of storing hydrocarbon

up a car with petrol, we take a calculated risk, but fuels—storing hydrogen would be no more

everything is done to reduce that risk. Filling a car dangerous.

with hydrogen would involve no more risk.

One of the problems with hydrogen is that it

One of the things about hydrogen is that it is

burns with a colorless flame—this means that we

lighter than air. This means that if you spill some, can’t always clearly see a hydrogen fire. If you rather than landing on the ground, it disperses

suspect a hydrogen fire, do not try to approach it, and floats to the sky. This is quite an advantage, and do not try to identify it by “feeling” heat.

when you come to consider how much petrol and

The correct method is to take a long-handled

diesel has polluted our watercourses. Furthermore, broom, and waft the bristles of the broom around you won’t stain your clothes with hydrogen as it where you suspect there is a hydrogen flame.

just disperses.

If hydrogen is burning, the bristles on the end

137

gases or fuels, that you are working in an area that is well ventilated to allow any gases that are

produced to escape, preventing build-up, and

explosion hazards.

Make sure you keep all bottles of chemicals

clearly labeled and never assume that the label is right. Always treat chemicals as an “unknown

quantity”—a clear liquid could be tap water, but then it could also be concentrated acid!

Figure 12-4

Identifying a hydrogen fire with a broom.

of the brush will catch light (see Figure 12-4).

If you identify a fire, quickly pull the broom away, and call the fire brigade. If you can safely isolate the supply of gas, without getting anywhere near If you are working with the small quantities of

the flame, for example, by a remote valve, or gas hydrogen produced by a little PEM electrolyzer,

shutoff safety system, do so.

this isn’t going to happen, but if you start using hydrogen from a cylinder, or from a laboratory

tap, or working with larger quantities of hydrogen Running your experiments

without proper ventilation, beware!

safely

In the event that a person is asphyxiated by

inhalation of hydrogen gas:

In order to avoid accidents and run a safe

The person should be moved to an area of

experimentation area, if you have any stored

ordinary atmosphere, ensuring that you do not

flammable gas, in bottles, and/or hydrides, make endanger yourself in the process. Open windows,

sure that they are stored correctly and labeled with provide as much ventilation and access to air as possible, while making sure not to switch on

a suitable label, such as that shown in Figure 12-5.

any electrical appliances or cause any sources

Make sure that whenever you are carrying out

of ignition.

experiments with hydrogen, methanol, or other

ytefaS

negordyHFigure 12-5 Clear labeling is essential. Figure 12-6 No smoking.

138

Hydrogen

Safety

Figure 12-9

A hydrogen safety sensor. Image

courtesy Fuelcellstore.com.

of rather fetching styles, and in a variety of

exciting colors—white! They also have the side-

effect of making you look incredibly purposeful

Figure 12-7

Lab coat.

and professional in your experimentation, which is to be encouraged at all costs, as people will not then bother to distract you for chores or menial Finally, something that should seem incredibly

tasks, if you seem to be deep in the throes of

obvious: there should be no smoking. Reinforce

making some discovery which could qualify you

this message by photocopying Figure 12-6 and

for the next Nobel prize.

displaying it around your working area.

The other thing which is a must-have, both for

For some of the experiments in this manual, you

“the look” and safety is a pair of safety glasses.

are going to be using methanol, alkalines, and

You only get one set of eyes, and if you flick

sodium borohydride. These will all get on your

something nasty in them, you could damage or

clothes and skin, and irritate or poison you if you impair your vision permanently, so make sure you are not careful, so do the sensible thing, and get wear them when working with chemicals, setting

yourself a lab coat. They are available in a variety light to things, or cutting materials—where bits of material are liable to fly off and hurt you!

If you start getting serious about fuel cell

experimentation, and decide to invest in large

PEM electrolyzers, or regularly work with cylinders of hydrogen, or, if you are a school or university, you might like to consider investing in a gas

detection system. Fuel Cell Store sell a hydrogen safety sensor, currently retailing at just over

$100 (Part No. 570150), which could be a good

investment as you get more serious about the hobby.

Figure 12-8

Safety glasses—a must, and they make

you look cool.

Above all, use your commonsense, and stay safe.

139

This page intentionally left blank

Chapter 13

Hydrogen Transport

petrol or diesel, but in a more limited capacity, Fuel cell cars

some vehicles will burn LPG, biodiesel, or

bioethanol.

To appreciate the differences between fuel cell

While the effects of releasing carbon into the

vehicles and other types of vehicles, we have to atmosphere can be mitigated by using different

understand some of the energy transfers that are fuels such as biomass or biogas, it does not change taking place. Ultimately, when we are talking

the fact that the petrol engine, being a heat engine, about transport, we need to produce mechanical

is horribly inefficient, and converts not a lot of the energy to turn the wheels of the car and make the chemical energy embodied in the fuel into actual thing go; however, although internal combustion

delivered power.

engines can produce mechanical power directly,

they only do so efficiently over a narrow power In addition, there is another good reason for

band, whereas electric motors produce a high

rejecting the internal combustion engine. Look at torque over a wide power band. This is why car

all the different byproducts that pollute our

manufacturers are looking into hybrid vehicles to environment that come out of your exhaust pipe.

combine the strengths of both the power density

Furthermore, by burning fuel with air, a cocktail that can be stored in fuels for the internal combustion of nasty gases is released, which contains not only engine, and the efficiency over a range of loads of CO , but also NO and SO , as well as

2

X

X

the electric motor. See how battery vehicles and particulates.

fuel cells fit into this energy conversion sequence In addition, internal combustion engines only

in Figures 13-1 and 13-2.

really have a usable efficiency within a narrow

Cars today tend to use four-stroke, internal

power band. This means that we need a gearbox

combustion engines. These engines either burn

which adds further weight to the vehicle, and a

Figure 13-1

Production of electrical power.

Figure 13-2

Production of mechanical power.

141

Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.

to “charge up,” and then can only run for a short amount of time.

Hydrogen sidesteps these problems with battery

technology—a car can be fueled in around five

minutes, and then the vast amount of power stored in the lighter-than-air hydrogen gas is converted to electrical energy, which in turn drives a

conventional electric motor.

This gives us the best of both worlds—an

energy-dense power source, with an efficient

Figure 13-3

The internal combustion engine

producer of kinetic energy.

produces all sorts of nasty emissions.

There are already a large array of hydrogen

fuel cell concept cars. A quick browse of any

manufacturer’s website will yield their particular clutch to engage and disengage the gearbox from

implementation of fuel cell technology; however, the engine. All in all, this is not very satisfactory.

most of these are based on the same fuel cell

technologies from only a handful of suppliers.

One criticism that people often have of fuel cell We can take a look at the “fuel cell cars gallery”

vehicles is that there is an argument for using

at the end of this chapter for more details.

fossil fuels to produce hydrogen. You, in effect, create a “long tailpipe” with all your vehicle’s emissions coming from a centrally located, large tailpipe—the power station’s chimney! This is a

Fuel cell vehicle

compelling reason why we need to look to clean,

technology

green sources of energy, in order to make sure that our future transport options have a reduced

When we look at a fuel cell vehicle, we notice that environmental impact.

there are a number of significant differences.

Electric motors fit a vehicle’s requirements

First and most apparent is under the hood—no

t much more closely. At low rpm, they produce the internal combustion engine, just a fuel cell and r most torque—this is when a vehicle requires the electric motor!

o extra energy to get it started. In addition to this, p regenerative braking can be used, where kinetic s energy from the car’s forward motion can be n recovered by using the motor as a brake, generating a energy in the process which can be used to charge r batteries and produce hydrogen.

T

The limitation for electric vehicles has always

n been the battery technology. Batteries are heavy, e storing not a lot of energy for their weight. By g contrast, hydrocarbon fuels provide a lot of energy o for their weight, and hydrogen produces a fantastic r amount of energy for its weight.

dy In addition to this, users have always favored H convenience—a battery car takes a long time Figure 13-4

Under the hood of a fuel cell car.

142

H

Iceland, which has committed itself to a hydrogen y

economy, opened the world’s first hydrogen filling d

station in Reykjavik in April 2003. Hydrogen is

r

produced onsite by electrolysis. The station

o

provides hydrogen for a fleet of hydrogen-powered g

buses. Interestingly, there is no roof to this fueling e

station—this has been done to prevent the potentially n

explosive build-up of hydrogen which could

T

accumulate.

r

A number of vehicle manufacturers have

a

announced their intentions to develop, or currently n

Figure 13-5

Hydrogen storage tanks under the seat

have hydrogen fuel cell powered vehicles.

s

of a car.

That list includes: The Ford Motor Group, which

p

incorporates Volvo, Mazda, and Jaguar; General

o

Secondly, a little more complexity needs to go

r

Motors (responsible for producing Vauxhall cars

into the engineering of the fuel tanks—rather

t

in the UK); Honda; BMW; Nissan; and Hyundai.

than a fairly simple metal can, more complex

Nearly all of the major car manufacturers are

arrangements need to be made for storing hydrogen.

now showing demonstration models of fuel cell

We explored some of these in the earlier chapter cars at world motor shows. While there are no fuel on storing hydrogen.

cell cars available to the general public at this time, Thirdly, when we come to fill the car, rather

the technology is certainly reaching maturity—

than using a simple nozzle, we have a more

manufacturers predict that we can expect to see

complicated coupling that allows transfer of the fuel cell models launched around 2010 for general hydrogen under pressure.

sale. However, one of the main barriers to

widespread adoption is the lack of hydrogen filling stations, which will be an obvious concern for

consumers.

At its North American headquarters in Torrance,

California, Honda are exhibiting their “Home

Energy Station,” a package that promises to offer combined heat and power for the home, as well as providing a source of clean hydrogen for powering Honda fuel cell vehicles.

One of the main barriers to innovation is the cost of the exotic materials required to manufacture the fuel cells. The platinum used for catalysts is

expensive, so current research is focusing around trying to eliminate, or at least reduce, the amount of platinum inherent in the design of fuel cells.

There are already promising results—as recently

as 2002, fuel cells had a platinum content of

£600 per kW output; however, we now have cells

containing around £20 per kW output. Further

Figure 13-6

A hydrogen coupling on a car.

advances will doubtless be made.

143

Figure 13-7

A specially constructed hydrogen

filling station.

For long-distance, low-occupancy journeys,

motorbikes present a more efficient solution for personal transport than cars. What is the sense in transporting over a ton of vehicle, to move

a person who weighs 80 kg?

A number of manufacturers have launched

small bikes and mopeds powered by fuel cells.

Particularly promising is the ENV fuel cell bike, which offers a stylish alternative to conventional Figure 13-8

ENV fuel cell bike.

petrol bikes.

In Europe, there are a number of countries trying out fuel cell buses as a clean alternative for public the technology is under test and development, and transport. While they have not been widely adopted, shows much promise for the future.

tropsnarT

negordy Figure 13-9 A London bus—powered by hydrogen. Image courtesy Ballard.

H

144

Pr

Project 33: Building a Simple Fuel Cell Car

ojec

In this experiment, we will be building a simple

●

Hydrogen and oxygen 30-ml cylinders (Fuel Cell

t

fuel cell car, which you can use as a base for

Store Part No: 7110307)

3

experimentation to investigate the science of fuel 3

cell vehicles. This car is of a very simple design,

:

and functional rather than aesthetic. There are

competitions for fuel cell vehicles such as this, and B

there is a lot of potential for flexibility in the u

design of fuel cell cars. Once you have built this i

simple model, you should have a grasp of the basic

●

Box of matches

l

principles of fuel cell vehicles. Use this project as

●

Philips screwdriver

d

a springboard for experimentation, and try and

i

●

Craft knife

enhance the performance of this simple model—

ng

make it more lightweight, add bearings, reduce

friction, improve balance, improve contact with the a

road–the list of engineering topics where this

simple vehicle can take you is endless.

Si

You can purchase a kit (Figure 13-10) from Fuel

m

Cell Store, which contains all the fuel cell and p

mechanical components needed to produce a simple l

fuel cell car. The kit comes with wheels, tires, axles, e

gears—everything except the chassis and storage of hydrogen—so this is a good way to get started.

Fu

●

Fuel cell car competition kit (Fuel Cell Store Part e

No: 7110303) containing:

l

●

Reversible fuel cell

●

Small motor with wires

Ce

●

Motor mount

l

●

4 small screws for motor mount

l

●

1 small screw to secure motor

C

●

Tubing

a

●

4 wheel hubs

r

●

4 O-ring tires

●

Generous selection of small gears

●

2 axles

●

Corrugated plastic, correx or corroflute

Figure 13-10

Kit of components for the simple fuel

cell car.

145

raC

lleC

le Figure 13-11 The components for the simple fuel cell car.

uF

Once everything is out of the box, and you lay it The first step is to take the plastic wheel hubs e out, it should look something like Figure 13-11.

(there should be four of them) and the rubber

l I tell you to get corrugated plastic for a reason.

O-rings out of the box. It is a simple matter of p It is perfectly possible to buy corrugated card or pushing the O-rings onto the plastic hubs to form m foamboard, or thin plastic, or any other manner of the finished wheels. (Take a peek at Figure 13-12.) i materials from which to make your fuel cell car The next stage is to assemble the motor into its S base. However, by its nature, corrugated plastic is metal mounting cage. The motor has a circular

very lightweight, yet stiff and rigid. It also has the a

protrusion at one end, which supports the rotating useful property that the plastic tubes created by the shaft. The metal cage has a circle to match this at corrugations provide a very convenient means of g

one end. The motor should be mounted with the

n anchoring your axles, and remove all the complexity shaft pointing through that hole, as shown in

i of bearings and axle mounting. As you experiment, Figure 13-13.

d and decide to work with different materials—without Once you have done this, look at the back of the l the corrugations—small lengths of drinking straw motor. You will see that the bottom of the metal i can be used instead to hold the axles in place.

u

cage protrudes past the back of the motor. You will B

:33

tcejorP Figure 13-12 Assemble the wheel hubs and O-ring tires. Figure 13-13 Insert the motor in the cage.

146

P

sheet of plastic, using a marker rule and set-square, r

or you can photocopy this page and use it to mark o

directly onto the plastic.

j

Now mark out the plastic, and it should look

ec

like Figure 13-17.

t

The best way to cut corrugated plastic is to use a sharp craft knife and a cutting board. Because 3

some of the cuts are internal, a pair of scissors will 3

not really be suitable. You will see that rectangles of

:

material will need to be removed from the board—

this is to provide space for our wheels. Do this first B

as this is the easiest step. Now, see the little ui

rectangle which is off-center. Cut through both

Figure 13-14

Fold the tab to secure the motor.

l

layers of plastic, and remove this piece of plastic d

from the board—this is waste and can be discarded.

also notice on the plastic backing of the motor that i

there are two small holes. Firstly, you should be able Now, with the “H” shape in the centre, we need

n

to gently bend this piece of metal over the back of to be careful. We are not removing this piece of g

the motor, so that the small hole in the center aligns plastic, but we do need to bend it in order to

a

with the small hole on the back of the motor.

support our fuel cell. Cut through both layers of the “H” marked in bold.

It is then simply a matter of taking the smallest S

screw supplied in the box, and anchoring the motor Now, one of the properties of corrugated plastic i

to the cage by securing it, as shown in Figure 13-15.

is that if we want to make nice, clean folds,

m

we can cut through one layer of plastic, but leave p

Now, we come to manufacturing the chassis. For

the other. So, along the dotted lines, carefully use l

this, you will need a small piece of corrugated plastic your craft knife to cut through one side of the

e

which is 115 mm by 175 mm. One of the things that plastic but not the other.

you need to ensure is that the “corrugations,” or lines F

in the plastic, run across the short side of the plastic.

Once all the excess plastic has been removed, the u

This is essential as, as mentioned before, we will be final blank chassis should look like Figure 13-19.

e

using these corrugations to mount our axles.

The first step is to screw the motor and its

l

Refer to the cutting diagram for the next step.

mounting to the board. If you transferred all the C

The diagram is printed to scale, so you can either measurements, you should see four small crosses.

e

transfer the measurements manually onto your

These are the center-points where we will locate l

the screws to hold our motor mount down. The

l

small self-tapping screws bit readily into the

plastic, and do not need any predrilling or center C

punching. You need to locate the motor, so that the a

shaft is hovering over the slot which we cut all the r

way through, as shown in Figure 13-20.

Now, we need to select some appropriate gearing

for our vehicle. A compromise will have to be made here. Our motor provides a certain amount of

“torque”, that is to say, “turning force,” and with a Figure 13-15

A screw secures the motor in the cage.

fixed amount of power, it will run at a certain speed.

147

Figure 13-16

Cutting diagram for the chassis.

Project

33:

B

Figure 13-17

The plastic chassis marked out ready

Figure 13-19

The plastic chassis cut-out.

u

for cutting.

il

We want to optimize the relationship between speed then engages with a gear with 60 teeth—the output d

and torque when transferring the power of the motor speed will be one sixth of the original speed, but in

to the wheels on the ground. We can use gear ratios the turning force will be six times higher. We can g

to take the speed of the motor, and reduce the speed, see how speed and power will be affected simply

but improve the torque. This gives our vehicle

by counting the teeth on the gears, and comparing a

pulling power. However, remember, we trade torque the ratios. We can see some different arrangements for speed. Make the vehicle too powerful, and it will of gears in Figure 13-21.

S

only go very slowly. Make the vehicle too fast, and Your first fuel cell car is going to have simple i

it may not have sufficient power to climb even the m

gearing—a small spur gear driving a larger gear

slightest incline, or navigate a rough surface. In p

which will drive the axle which powers the wheels.

addition, we can use compound gear ratios. We will l

Select the smallest gear from the assortment—the not be using them in this model; however, it is

e

something you should be aware of. We can use

F

gears to turn gears in effect, reducing or increasing u

the ratio each time.

e

If a shaft spins at a set speed and it has a gear l

with 10 teeth on the end, this gear with ten teeth Cell

Car

Figure 13-18

Use a sharp craft knife to cut through

Figure 13-20

Motor mounted with shaft above

both layers of the plastic.

gear-slot.

149

raC

l Figure 13-21 Combine the gears to make different ratios.

le one with the least teeth, and push it onto the shaft You may find that the axle supplied is a little too C of the motor, as shown in Figure 13-22.

tight for the gear, so in this instance we can use a l

small drill to enlarge the hole to a suitable size for Now, we are going to install the fuel cell—

e

the axle.

remember, we cut the board on one side of the

u “H”. . . well, fold the flaps up to provide support Next, push the axle down the channel, through

F for the fuel cell, as shown in Figure 13-23.

the hole in the gear, and onto the other side of the plastic, and out the other side. It should look

e

Now, you can either use a little sticky tape, or something like Figure 13-27.

l even some double-sided tape on the flaps, in order p to fix your fuel cell in place, like the image in Now for attaching the wheels. First start with the m Figure 13-24. The hole is the correct size for you to front wheels. Again, you may find that you need to i wedge the fuel cell into place, with the hole drill out the wheels slightly. Another labor-saving S gripping around the bottom of the cell providing way to make things fit is to heat the plastic to additional support.

soften it, allowing the axle to slide in. The way to a

Next, we are going to mount the rear axle and

do this is to heat the axle till it is hot, and push it into the plastic wheel. This will cool to make a g gear wheel. Take one of the medium-sized single very firm fit. Make sure you heat the axle and push n gears, and hold it in the rectangular slot. The i correct-sized gear will allow the hole through the d gear to align with one of the rectangular channels l in the corrugated plastic, as shown in Figure 13-25.

iuB

:33

tcejor Figure 13-22 The smallest gear should be a push-fit P on the motor shaft.

Figure 13-23

Fold the fuel cell support flaps up.

150

Project

33:

Building

a

Figure 13-24

Fuel cell mounted in position.

S

Figure 13-26

Use a small drill to enlarge the axle

i

it into the wheel, not vice versa, for a good result.

hole.

m

See Figure 13-28 for comparison.

p

Once all of the wheels are attached, connect the l

motor to the terminals of the fuel cell, and using e

short lengths of hosing, connect the fuel cell to the Fuel

Ce

Figure 13-27

Axle and large gear wheel installed.

ll

Car

Figure 13-25

Align the axle hole with the corrugated

plastic holes.

Figure 13-28

Heat the axle not the wheel.

151

raC

lleC

leuF

”tneg

Figure 13-30

Simple fuel cell car complete (side view).

illet Figure 13-29 Simple fuel cell car complete And there you have it! Our completed fuel cell

n (front view).

car! See Figures 13-29 and 13-30 for how the

I

finished model should look.

“ respective hydrogen and oxygen tanks, being sure You will now need to follow the procedure for

to put a small plug in any unused ports in the fuel charging the fuel cell with distilled water, and filling na cell. You will find that a small piece of double-the tanks, then creating hydrogen and oxygen using sided tape or sticky tape will be sufficient to

electrolysis. You will then generate sufficient

g anchor the storage tanks in their correct position.

hydrogen to run the car for a small distance.

nidl Project 34: Building an “Intelligent” Fuel Cell Car iuB

:

gearbox and steering system, which allows the car 43

to change direction when it bumps into obstacles.

Take some foamboard, make a small enclosure with t

walls 4 in-high, and your intelligent fuel cell car

●

Intelligent fuel cell lab (Fuel Cell Store

c

will happily trundle around crashing into walls, and Part No. 550190)

e

then reversing in a different direction.

j

If you just want a fuel cell car that you can play o and experiment with out of the box, then the Get the components for the car out of the box

r intelligent fuel cell car is just the ticket! It provides (Figure 13-31a), and they should look like Figure P a ready-made chassis, and it has a clever differential 13-31b.

152

P

The first step is to press the wheels onto the stubs r

protruding from the plastic chassis—your car will look o

like Figure 13-33. None of the wheels are “driven”—

j

the action takes place in the little black box in the e

center of the car, which provides all the power.

ct

Next, connect up your tanks to the fuel cell—

you should be used to this procedure by now!

34

The chassis comes with a special area to clip the

:

tanks and the fuel cell to it. Install them now.

You’re likely to have a little bit of distilled water B

splashing about, so install the cover over the motor u

mechanism to prevent it from getting wet, as shown il

in Figure 13-35.

d

Now, a handy plug is provided to charge the car

i

from the supplied battery pack. When you are

n

using the PEM fuel cell in the electrolyzer mode, g

you will need to connect the leads from the plug a

to the fuel cell, as shown in Figure 13-36.

n

Figure 13-31a

However, when you want the car to “go,” you

Intelligent fuel cell car in the box.

will need to connect the motor unit to the fuel cell,

“

as shown in Figure 13-37.

In

And that’s everything complete! Ladies and

t

gentlemen . . . The intelligent fuel cell car is in e

Figure 13-38.

lligent”

Fuel

Cell

Car

Figure 13-31b

Intelligent fuel cell car components.

153

raC

lleC

leuF

”tn

Figure 13-34

Fuel cells and tanks installed.

egilletn Figure 13-32 Wheels installed.

I“

na

gnidliuB

:43

tcejorP Figure 13-33 Fuel cells and tanks plumbing. Figure 13-35 Splash cover installed over the motor.

154

Project

34:

Buildi

Figure 13-36

Fuel cell connected to the battery slot.

ng

an

Figure 13-37

Fuel cell connected to the motor.

“Intelligent”

Fuel

Cell

Car

Figure 13-38

The complete “intelligent” fuel cell car.

155

e

Project 35: Building a Hydride-Powered

lc

Fuel Cell Vehicle

iheV

into the water. As hydrogen is produced, hold the storage part of the gas cylinder over the fizzing l

pill to capture hydrogen. Wait as a little hydrogen l

builds up under the cap, and then press it

eC

firmly home.

●

Simple or intelligent fuel cell car (see above)

You should be able to power your fuel cell

l ● H-Gen hydrogen generator

e

vehicle from the hydrogen, which is being released

●

Sodium borohydride

u

from the hydride.

F

Another approach that has been investigated for

fuel cell vehicles is to use hydrides for storing de hydrogen. This has the advantage that hydrides are r easier to store than hydrogen gas; however, there is e an associated weight penalty.

wo It has been speculated that vehicles could be P “fueled” with a hydride, which is reformed onboard

-e the vehicle using a catalyst. Once the catalyst d exhausts the supply of hydrogen from the hydride, i the spent fuel is returned to a holding tank. This The limiting factor is now the fuel cell’s supply of r spent fuel could then be offloaded from the vehicle d

oxygen. As we have seen, fuel cells can function y at a filling station, and regenerated chemically to on air, but the performance is likely to be fairly H its previous state, ready for the next customer. The poor, and your fuel cell may not produce enough

hydrogen would have to be separated from the

power to move your vehicle.

a liquid hydride, then any heat produced from the g reforming process would be extracted using a heat n exchanger, with the hydrogen being fed to a fuel i cell to produce electrical power, which would then dl power electric motors. A schematic of this process i is shown in Figure 13-39.

uB Remember the H-Gen that we used in the chapter on storing hydrogen (Chapter 4)? Well,

: let’s try powering our fuel cell vehicle from 53 hydrides!

Produce hydrogen and oxygen as you normally

t would by electrolysis. Save the oxygen in the ce storage tank but open the hydrogen tank, and j allow it to vent so there is no hydrogen gas. Now, o put a little sodium borohydride in the distilled rP water, and drop the catalyst pill from the H-Gen Figure 13-39

Schematic of hydride vehicle.

156

Pro

Project 36: Building a Radio-Controlled Fuel Cell Vehicle ject

In this project, we are going to convert a radio-3

controlled (RC) car to run on fuel cell power!

6

We are going to take an off-the-shelf car and

:

soup it up, to run it from clean, green hydrogen B

power.

●

u

A radio-controlled car

We can’t simply connect our fuel cell directly.

i

●

PEM fuel cell (the type used in the last two

l

The reason for this is that the motors we used in experiments is suitable)

d

the previous two projects were small low-voltage i

●

Hydrogen storage tank

motors. They are quite happy to run from the

n

●

low voltage produced by a single-cell fuel cell; g

Oxygen storage tank

however, the needs of even a small RC car are a

●

DC-DC convertor

a

little more demanding. We are going to boost the

●

Short lengths of wire

voltage using a DC-DC converter. Remember the

R

●

Small piece of corrugated plastic, correx,

a

characteristics of fuel cells that we discovered?

or corroflute

d

They tend to produce a fair amount of current, but i

●

Double-sided tape

the cell voltage is the limitation. Well, a DC-DC

o

converter helps us get around this limitation by

-C

sacrificing current for voltage. We are going to use o

a small DC-DC convertor to boost the single-cell n

power of our fuel cell up to a voltage suitable for tr

powering a little RC car.

o

When you have selected your vehicle, assemble

ll

●

Electrician’s screwdriver

all your components, and you should have

e

something that looks a little like Figure 13-40.

d

Now, it must feel like Christmas come early—open F

the box of your RC car, and take out the car. The u

handset controller will be powered by ordinary

el

batteries, so now would be a good time to fit some.

The battery compartment of your RC car will

C

most likely have a screw to secure it, so take a el

small screwdriver, remove the screw and open up

l

When choosing a radio-controlled vehicle, you

the battery compartment of your RC car.

need to look for something small that will run on V

I recommend that you use solid wire for

4.5 V—larger radio-controlled vehicles require a e

attachment rather than flexible wire—there are a lot of juice, and have large battery packs—our

h

couple of reasons for this—it makes the next step i

small fuel cell will wimp out at the sight of them, c

easier, and furthermore, it allows you to “bend

so look for something a little more modest that

l

your wire to shape,” making sure that it doesn’t runs from either AA or AAA batteries.

e

snag the wheels of your RC vehicle.

157

You need to locate the two single terminals.

e

One will be a spring (this is the negative) while the lc

other will be a flat plate (the positive)—the

i

polarity and way that the batteries are inserted h

should be clearly labeled inside the compartment.

e

Ignore the double terminals—these are just used to V

make a contact path between the batteries. The

l

dotted white line shows the path that the electricity l

would normally flow between the batteries.

eC

We are going to be “piggy backing” onto the

battery terminals—if you are only going to use the le

car for this project, then you might consider a

u

permanent method of attachment. As a rule, it will F

be hard to solder wires onto your battery contacts if they are made of stainless steel, so you might de

look at conductive glues which do a similar job to l

solder, but without the heat (and they take a little l

longer to cure).

or

The method which I have found is best for

t Figure 13-40 Components for RC fuel cell car.

attaching wires is to use a very fine electrician’s no

screwdriver and lever the battery terminal forward C-oidaR

a

gnidliuB

:63

tcejorP Figure 13-41 RC car and handset.

158

Project

You could always check for a good contact now

3

using a wall-wart power supply (but make sure

6:

it’s set to the right polarity, or else you will fry the electronics of your vehicle.) It’s probably

B

easier to do this now as a fault-finding exercise u

than to wait until everything is assembled.

i

Figure 13-42

RC car battery compartment—terminals

l

labeled.

ding

a little, then try and slide the solid core wire in the Now flip the car over, and you should end up

a

space between the terminal and the plastic of the with something like Figure 13-44.

car body. This will be a tight fit, and should be Now, to power our little automotive beastie,

R

sufficient to reliably hold the wire in place.

we are going to need the previously mentioned

ad

Once you have made a good electrical contact,

DC-DC converter. If you want to take the hassle

i

shut and screw back the battery compartment,

out of things, you can just buy a little board

o

trapping your wire in the space between the battery off-the-shelf (the Fuel Cell Store do one—part

-C

flap and door. (If the worst comes to the worst, and number listed above). However, if you’re a

o

you can’t find a way out for your wires, you could dab hand with the soldering iron, look at

n

always use a small needle file to file a small

Figure 13-45 to see how you can make your

tr

groove to allow your wires to pass through.)

own.

olled

Fuel

Cell

Vehicl

Figure 13-43

e

Underside of the RC car with wires

Figure 13-44

RC car with power wires.

leading to the battery compartment.

159

elciheV

lleC

leuF

de

Figure 13-45

DC-DC converter board schematic.

llo If you have some skill with hobby electronics, a DC-DC converter board is very easy to make, as an r

integrated circuit removes many discrete components.

tno You will see, either on the schematic or the Car roofs tend to be curvy streamlined affairs—

C- PCB, depending on what option you have selected, great for aerodynamics in the real world at high o that there is very clearly an IN and an OUT.

speed, but not a good surface for mounting fuel

i The DC-DC converter is polarity sensitive, so cells! We, however, are going to take a small sheet d make sure that you get things the right way round!

of corrugated plastic—lightweight and strong—and aR It should seem fairly obvious that the OUT end use it at a platform for affixing our components.

connects to the wires coming from under our

First of all, we are going to cover it in double-a RC car, while the IN end leads to the fuel cell.

sided tape, on both sides, in order to provide a g In the shop bought board, you just need to take an sticky surface to easily mount our components.

n electrician’s screwdriver, and secure the stripped The beauty of using double-sided tape is that a

i ends of the wire in their terminal blocks.

strong tape should provide sufficient mechanical dliuB

:63

tcejorP Figure 13-46 DC-DC converter board from the Fuel Cell Store.

160

P

from the double-sided tape on the opposite site of r

the plastic, and stick the assembly on the roof of o

your car. Now, taking the tubes, connect up

je

your fuel cell to the tanks—you should know the

c

drill by now!

t

Once you have connected up the DC-DC

3

inverter, fuel cell, and car battery terminals, you 6

can think about mounting the equipment on your

:

vehicle. Double-sided tape is relatively easy to B

use, and generally won’t damage the vehicle

u

underneath if you want to change things around.

i

For mounting the DC-DC convertor, you could

ld

employ a similar approach, or alternatively you

i

Figure 13-47

Cover the plastic platform with double-

could mount it using Blu-Tack.

n

sided tape.

g

Make sure that the wires are kept out of the way from any wheels so that they do not snag.

a

support for all the components while you experi-

The finished vehicle is shown in Figures 13-49

R

ment, but is weak enough that should you wish to and 13-50—it’s not going to win any awards for

a

use the components (and the RC car) again, you

automotive design brilliance, but it is certainly one di

can easily disassemble them with a little care—and of the greenest cars on the block.

o

they won’t be damaged.

If you wanted to get more advanced, you could

-C

Now we come to the powerhouse for our teeny

consider removing the vehicle components from its o

motor! Remove the backing from the double-sided

enclosure and constructing a new body, but this is n

tape, and position your hydrogen tank, oxygen

purely an aesthetic issue—the function of the car tr

tank, and fuel cell on the sticky surface. This will will remain the same! If you do decide to go down o

hold everything in place. Now, remove the backing this route, you will be confronted by similar issues lled

Fuel

Cell

Vehicle

Figure 13-48

The hydrogen fuel cell power unit.

161

to the major automotive manufacturers—where

e

to mount the hydrogen storage tanks, which are

lc

somewhat big and bulky.

i

Once your vehicle is complete, follow the

he

procedures in the PEM fuel cell chapter (Chapter 7) V

for charging your fuel cell with distilled water, producing hydrogen by electrolysis, and then

l

connect the DC-DC convertor back for some

le

rip-roaring racing action!

C

You could consider building an obstacle course

l

for your car and seeing how well it performs.

e

Remember, the challenge isn’t just to stay on the u

road, but also to stop distilled water from slopping F

out of the rooftop storage tanks, as these are

d

providing the pressure for the hydrogen (and

e

oxygen) underneath.

ll

You will find that your vehicle performs much

o

better on smooth surfaces. Small RC cars do not

r Figure 13-49 The completed RC fuel cell car always perform very well on carpeted surfaces.

t (top view).

n

Also, if you stick to tiled and laminated surfaces, o

it is easier to wipe up any distilled water that is C

spilt in a major collision!

-oidaR

a

gnidliuB

:63

tcejor Figure 13-50 The completed RC fuel cell car P (side view).

Figure 13-51

Choose smooth surfaces, not carpet.

162

Fu

Fuel cell planes

Union, where one of the engines was powered by

e

hydrogen that was stored onboard cryogenically.

l

And now, we move swiftly on from fuel cells on

The aircraft was a Tu154 airliner that had been

C

the road to fuel cells in the sky—we are going to specially adapted.

e

have a look at some of the different ways that

Hydrogen is a fuel that is well suited to use in l

hydrogen could be used in the future to transport aircraft due to its tremendous energy—by weight; l

us from place to place.

however, as a result of its poor energy density by P

At the moment, the aviation industry is growing

volume, it is apparent that future aircraft fueled l

at an unprecendented rate. It’s now possible to fly by hydrogen will require tanks that are four times an

cheaply and comfortably—a dream that only

bigger than those employed on current aircraft.

e

50 years ago was out of reach for many people.

NASA introduced fuel cells to flying with its

s

However, this boom in aviation and travel comes

Helios prototype unmanned plane. The plane could at a cost—a carbon cost. Airplanes produce vast

provide a substitute for expensive satellites, by quantities of carbon dioxide, as their jet engines orbiting the earth, unmanned, powered by clean,

ooze out the emissions from burning hydrocarbon

green energy from the sun during the day, its large kerosene. If we are to look to a future beyond oil, wing structure being covered in photovoltaic cells, we need to look at other alternatives that can

while producing hydrogen from spare power. Then, parachute us into the 21st century.

during the night when the sun is hidden away, the Using hydrogen in the air isn’t a new phenomenon.

reserves of hydrogen generated during the day are The Russian airplane company, Tupolev, successfully converted to electrical energy to drive the plane’s flew a tri-jet airliner in 1988 in the former Soviet propellers and maintain flight during the night.

Figure 13-52

NASA Helios prototype. Image courtesy NASA.

163

A little later in this chapter, we are going to look at lighter-than-air travel, but next, let’s blast off into outer space!

If you want to read some more about

hydrogen-powered planes, the following are

a good selection of Web links:

www.flug-revue.rotor.com/FRheft/FRH9809/

FR9809k.htm

!

www.bl.uk/collections/patents/greenaircraft.html ne

www.nasa.gov/centers/dryden/history/pastprojects/

g

Erast/helios.html

ord

Project 37: Space Travel with Hydrogen!

yH

Building a Hydrogen Rocket

htiw

l ● Manganese (IV) oxide

e

●

Tesla coil

v ● Zinc scraps

●

Awl

a ● Hydrochloric acid (4.0 mol l−1)

r

You’ve seen how metal scraps and acid can be

T ● Hydrogen peroxide (3%)

used to produce hydrogen—well, in this

experiment, we are also going to use manganese

●

2 × boiling tubes

e

oxide and hydrogen peroxide to produce oxygen.

c ● 2 × rubber bungs

Alternatively, if you haven’t got that sort of stuff a

or

hanging around, you can produce hydrogen and

p

oxygen using your PEM electrolyzer.

S ● PEM electrolyzer

●

Power source

:7

and

3

●

Gloves

t ● Safety specs

c

If you aren’t sure where to get a Tesla coil from,

●

Microbore tubing

e

talk to a good science lab technician at a school j ● Cork lid

or college, or check out Bob Iannini’s Electronic o

Gadgets for the Evil Genius, McGraw-Hill, 2004,

●

Paperclip

r

which comes with some fab ideas for

P

high-voltage electric-spark-making mayhem!

●

Plastic pastettes

164

Pr

Making a suitable bung

Preparing for launch

oj

You will need to take a rubber bung that fits

Using the two boiling tubes full of hydrogen and e

your boiling tubes, and drill a small hole in

oxygen, fill a small pastette half with hydrogen c

it using an awl or a small drill, through which

and half with oxygen. Leave about an inch of

t

you can insert some microbore nylon tubing.

water in the bottom. This helps to seal the gases You will use this bung to help you collect the

inside the tube, and furthermore provides a reaction 3

gases generated by the chemical reactions.

mass to produce some meaningful thrust.

7

Alternatively, if you are using your PEM

:

electrolyzer, you will need some microbore tube

Launching the hydrogen-fueled

“epoxied” into the end of the standard rubber

S

rocket

p

tubing, in order to squeeze the tube into the

a

opening of the pastette.

Hold the sparking end of the Tesla coil near to the c

base of the pastette where the gas meets the water.

e

After several sparks, you will hear a loud pop, and Producing hydrogen

your pastette will fly off the end of the paperclip, Tr

Take a clean boiling tube, and drop in a couple of soaring into the sunset . . . well, not quite! At least a

small pieces of zinc and a little 4.0 mol l−1 of over the other side of the room!

v

hydrochloric acid, so that there is about two

If all that seems like a little bit too much hard e

inches of fluid in the tube. The hydrogen gas

work, Estes, the model rocket company, now sell a l

will bubble. Using a similar bung to that described hydrogen rocket kit, where hydrogen produced by

above, you will be able to displace some of the

the process of electrolysis is used to launch a small w

water in the pastette.

rocket from a launch pad. The solution comes

it

ready-made—with this book, you now understand

h

the science!

Producing oxygen

Hy

On the tip of the spatula, take a small quantity d

of manganese (IV) oxide and place it in

r

a boiling tube. Now add 3% hydrogen peroxide.

o

You should have about 2 inches or so of

g

fluid in the bottom of the tube. Now quickly

e

stopper the tube with a bung—it will have

n

a small length of tube attached. Insert the

!

tube into the pastette.

Building a launch pad

You need a small rod to launch your

hydrogen rocket, so take a small paperclip,

straighten it out, and stick it into a large

cork lid from a jar. The pipette can then

slide onto the rod.

Figure 13-53

Pipette hydrogen rocket.

165

If you want to go beyond hydrogen, and explore

more aspects of amateur rocketry, check out my

book 50 Model Rocket Projects for the Evil

Genius, McGraw-Hill, 2006.

!negordyHFigure 13-54 Estes hydrogen rocket kit.

ht

Project 38: Air Travel with Hydrogen! Building a iw

Hydrogen-fueled Airship

le

As much as this experiment is about building an

v

airship, it is also about learning as regards the a

density of hydrogen gas relative to air.

r

We can produce hydrogen, using any of the

T

methods in this book, to fill a sealed envelope of

●

Fuel cell mini-PEM (Fuel Cell Store P/N:531907)

lightweight material. You could use an off-the-shelf r ● Small plastic propeller

helium balloon, filled with hydrogen, or you could i

●

Small, efficient motor (e.g., pager motor)

A

make your own envelope from Mylar which can be

●

Length of plastic tubing

easily heat-sealed with a household iron. Take a

:

tube from the balloon, and epoxy it to one of the

●

Sheet of Mylar

8

mini fuel cells we encountered in Chapter 7. The or

3

power from this PEM fuel cell can be used to feed

●

Mylar helium balloon

a small electric motor, which in turn can be used to t

turn a model toy propeller to create a moving (if c

somewhat erratic) blimp!

ej

You will find that, as hydrogen is consumed to

o

power your motor, the blimp will gradually lose

r

height, so our blimp will only make short flights.

P ● Household iron

But you can always recharge your blimp by

166

P

entry point of the pipe is well sealed to prevent the r

escape of hydrogen. A little dab of glue (or the o

ubiquitous duct tape) goes a long way to keeping j

things snug.

ec

Remember, if you find that you are not getting

t

sufficient push from your propeller, try reversing the polarity of the motor and see what effect

3

that has.

9

The fuel cell, motor, and propeller can all be

:

mounted on the tail of the balloon, using a few dabs of hot melt glue, or even tape.

Bu

Compensate for the buoyancy of the hydrogen

i

by adding a little plasticine or modelling clay

l

to the bottom of the balloon.

ding

a

Figure 13-55

A home filled, powered blimp from

R

a standard helium balloon.

adi

Helium is generally used as the gas of choice for o

making some more hydrogen with your PEM fuel

filling balloons rather than hydrogen as it is

-

cell, making sure to anchor the blimp down when

nonflammable; however, hydrogen has more

C

lifting power, at the expense of being slightly

filling it, so it doesn’t go drifting off.

o

more dangerous! If you are going to fly a

n

Helium balloons come with a handy hole and

hydrogen balloon, think very carefully about the t

one-way valve for insertion of a nozzle; however, areas you fly it in, and ensure that there are no r

you will have to make sure, when fixing your

sources of ignition present.

o

hydrogen supply pipe for your fuel cell that the lled

Ai

Project 39: Building a Radio-Controlled Airship

rship

If you want to take the last experiment further, from base control using radio control. You will be you might like to consider the possibility of

using hydrogen for its lifting power, and the

building an airship that you can control and steer actual motors will be powered by batteries in the 167

radio control kits; however, you might like to

consider how a DC-DC convertor could be used to

p power some of the lower-powered kits. Also, i remember, these kits are designed to work with h helium, as it is generally seen as safer (it doesn’t s

www.johnjohn.co.uk/shop/html/model_

explode). If you are going to use hydrogen

r

radiocontrol_blimp.html

in these blimp kits, think very carefully about i

www.hobbytron.com/mach3_rc_blimp.html

where you are going to fly them, as you don’t

A want to be causing fireballs, do you? Make sure store.makezine.com/ProductDetails.asp?Product

Code=MKBLIMPKIT

you stay away from areas where there could be a

d naked flame, or other source of ignition.

ellortnoC-oidaR

a

gnidliuB

:93

tcejorP

168

Chapter 14

More Fun with Hydrogen!

In this chapter, we are going to explore some

are presented more as an illustration of what can different things that you can do with hydrogen—

be done than as practical objects to use every day; some of these projects are good for demonstration, however, as the technology gains momentum,

showing and proving that hydrogen has genuine

expect some of the ideas in this chapter to become applications in the real world. These experiments mainstream.

Project 40: Powering a Radio Using Hydrogen

You need to find a cheap radio, which takes two

or three AA or AAA batteries, i.e., its power

supply requirements are between 3 and 4.5 V. Start small, and look for a radio which has minimal

power consumption requirements, as this way, your

●

100 µF capacitor

tiny store of hydrogen will last a little longer!

●

100 pF capacitor

The circuit diagram shown in Figure 14-1 is for

●

1mH inductor

our ubiquitous DC-DC converter, which takes our

low-voltage power from the fuel cell, and transforms

●

1N5819 diode

it to a higher voltage output suitable for powering

●

274 K resistor (1% tolerance)

electrical devices—in this case, our radio.

●

100 K resistor (1% tolerance)

You are going to need to investigate the battery

●

100 µF capacitor

compartment of your radio, and work out where to

●

USB socket

connect the output from the DC-DC converter. Look

●

MAX 630 CPA integrated circuit

at the path that the circuit makes in the battery Yet another application for our fabulous DC-DC

compartment. It is usual to have a single metal

converter featured in the radio-controlled

plate covering one battery terminal for where the fuel cell car project—why not use a fuel cell radio circuit connects to the battery pack, and a double to power some tunes? Imagine the scene—you’re

plate which covers two adjacent battery terminals, stuck on a remote island, with your fuel cell

where a connection is being made between batteries.

experimenter’s kit, a solar panel, and an old

The positive terminal will likely be a flat plate and radio, but your favorite music is played at

the negative terminal will probably be a spring.

two in the morning when it’s dark and the

While it may seem like folly to power a

solar cell won’t work! Simple—use the fuel cell

radio from an expensive fuel cell, electronics

as a battery to store energy made during the day manufacturers are actually looking toward fuel

for use at night!

cells to make the next generation of electronics 169

Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.

negordyH

g Figure 14-1 Hydrogen-powered radio schematic.

nisU

devices which run for longer. There are limitations o

with battery technology—batteries are fairly

i

heavy and bulky, and they only last for a certain d

amount of time. So to get round these limitations, aR

manufacturers are looking at integrating fuel cells into mobile devices, along with replaceable “fuel a

cartridges” containing hydrogen or methanol

acting as a hydrogen carrier.

gnirew Figure 14-2 Hydrogen-powered radio connected up.

o

I’ve uploaded a short video of this setup to

P

YouTube, which can be accessed at:

www.youtube.com/watch?v=CRhM0ixrmRA

:04

tcejorP

170

Pr

Project 41: Hydrogen-Fueling your iPod‘

ojec

●

MAX 630 CPA integrated circuit

t

or

4

●

DC-DC converter (preassembled) (Fuel Cell Store

1

Part Number: 590709)

:

●

iPod Shuffle or similar USB MP3 player

●

Voller hydrogen generator (Fuel Cell Store Part

Number: 72035001)

●

Hydrogen 100 µF capacitor

H

In this project, we are going to be using our

y

●

100 pF capacitor

ubiquitous DC-DC converter to power an iPod.

d

●

1 mH inductor

Rather than hack the iPod and invalidate the

r

●

1N5819 diode

o

warranty, we are going to get a USB PCB mounted

g

●

274 K resistor (1% tolerance)

socket, and solder the power outputs from our

e

●

100 K resistor (1% tolerance)

DC-DC converter. Ensure that you get the wires

n

around the right way as iPods—as with other solid

●

100 µF capacitor

-

state electrical devices—are polarity sensitive, and F

●

USB socket

ueling

your

iPod‘

Figure 14-3

Hydrogen-powered iPod diagram.

171

You will also need to purchase a USB socket,

which is used to connect the MP3 player to the

DC-DC converter. Again, refer to Figure 14-3, and ensure that you connect the inverter to the socket with the correct polarity, or else you risk damaging your MP3 player.

Another option for powering your portable

electronics in remote places is the Voller hydrogen generator (shown in Figure 14-4)—a fuel-cell

based generator, which runs on hydrogen, and

which provides a USB power output, a 110 V or

230 V (depending on the model) line power output and a 12 V car accessory socket.

s Figure 14-4 Voller hydrogen generator.

e

The technology is currently out of the reach of

l

the average consumer; however, for certain remote b if you get the wires the wrong way round, you will applications the cost is justified, and with advances b end up with friedTunes rather than iTunes™.

in fuel cell technology, expect to see the price drop u

In this project, we are going to use an iPod

significantly in the next several years.

B shuffle, as they are cheap and have a much lower Many major electronics manufacturers are also

current draw than the larger hard-disk based iPods.

n

investigating the possibility of including fuel cell e There are a number of other USB MP3 players, technology directly as part of their devices. In the g and others may work equally well; however, it is next few years, you could be plugging a methanol o impossible to obtain data on the power consumption cartridge into your laptop, portable media player, r for all devices.

or mobile phone rather than a battery charger, to d

You will need to assemble the circuit as shown

provide long-life power for your electronic

y in the diagram, or purchase the ready-assembled devices, over and above that possible with present H printed circuit board from the Fuel Cell Store.

battery technologies.

gnik

Project 42: Making Hydrogen Bubbles

aM

:

●

Metal (e.g., magnesium ribbon)

2

●

Washing-up liquid, detergent, or soap solution

4

●

Bowl

t

A fun experiment is to produce some

c ● Bung

e

hydrogen—in the example shown in Figure 14-5,

●

Thistle tube

j

we are using the acid-metal method to produce

o ● Erlenmeyer flask with side tap

hydrogen relatively quickly. As the hydrogen is

r ● Swan neck tube

produced, and bubbles through the water in the

P ● Acid (e.g., dilute hydrochloric acid) bowl, the hydrogen will form bubbles, which,

172

Project

43:

Expl

Figure 14-5

Making hydrogen bubbles.

odi

being lighter than air, will float. These can then be easy, fun experiment, which shows that hydrogen

n

ignited with a splint. It’s another nice, quick and is lighter than air.

g

Som

Project 43: Exploding Some Hydrogen Balloons

e

Hydroge

●

Latex balloons

n

●

Matches

B

●

Method of generating hydrogen and oxygen

(discussed earlier in the book)

al

Launching exploding hydrogen balloons into the

l

air is a fun way of learning about the science of o

“stoichiometry.” Remember, chemical reactions

o

work best when the reactants are present in the

n

correct quantities. The ideal mixture of hydrogen s

to oxygen is 2:1—we learn this because the product of the complete combustion of hydrogen is H O.

2

You can use the formula for the volume of a

sphere, combined with measurements around the

balloon’s circumference, to make rough

Figure 14-6

Exploding hydrogen balloons.

173

approximations of the volumes of gas you are

however you ignite the balloons, make sure you

filling the balloons with.

maintain a safe distance!

If we have too much hydrogen present, then

One possible method of “remote detonation” is

when the balloon is ignited, it will have to get to use a simple model rocket igniter taped to the oxygen from the surrounding air, providing less of balloon. If you want to read more about model

a bang. However, get the mixture of hydrogen

rocket igniter ignition systems, check out my book and oxygen just right, and a very loud bang will 50 Model Rocket Projects for the Evil Genius, ensue.

McGraw-Hill, 2006.

My former science teacher, Bob Spary, would

If you want to watch exploding hydrogen

release balloons filled with the correct

balloons from the comfort of your armchair, take a eu mixture—and a long length of burning string look at the following cool YouTube videos:

c as a fuse over our school sports field, while the www.youtube.com/watch?v=7UoFNdp0UYg

e school soccer team practiced—and the ensuing www.youtube.com/watch?v=MMB2VR0087w

b bang never failed to make them jump out r of their skin!

www.youtube.com/watch?v=p3LUHAr12qI

a

You might like to consider wearing a pair of ear www.youtube.com/watch?v=kknU6cpKWL0

B defenders if you have sensitive ears, and, remember, www.youtube.com/watch?v=UUDy9heD6h8

negord Project 44: Having a Hydrogen Barbecue yH

are only putting the carbon dioxide back into the a

air that the tree consumed when it was growing.

g

However, if you really want to bring your carbon n

emissions down to zero, consider having a

i

hydrogen-fueled barbecue!

●

Hydro-Que (Fuel Cell Store P/N: 551005)

va ● Source of hydrogen

H

As a conscious environmentalist, no doubt

carbon emissions will be your biggest concern

: when you go out back in the yard to have a 4 grill—not whether the sausages are burnt or not!

4

Burning gas in the garden is a source of carbon

t emissions. Patio heaters and gas grills are the c enemy of the environmentalist, as they are taking e precious fossil fuel resources and squandering j them needlessly.

or If you are burning wood, worry not if the wood Figure 14-7

The Hydro-Que hydrogen barbecue.

P comes from a sustainably managed source, as you Image courtesy Fuel Cell Store.

174

Project

44:

H

Figure 14-8

Regulator valve and flash arrestor.

a

Image courtesy Fuel Cell Store.

vin

The Hydro-Que is a barbecue grill especially

g

modified to accept hydrogen gas as its fuel

input.

a

Remember, at the moment, most hydrogen gas

H

available commercially comes from fossil-fuel

Figure 14-9

PURE Energy Centre hydrogen

y

resources that are reformed by steam-cracking, so barbecue.

d

at the moment, the reduced environmental impact

r

of having a hydrogen barbecue is more of a

o

symbolic one than a practical one. However, we

hydrogen upstream of the barbecue in the tank

g

can look forward to the day when hydrogen is

or hydride.

en

produced by electrolysis using clean, renewable

So now you’ve eliminated all the carbon

energy. The Hydro-Que hydrogen barbecue is

emissions from your barbecue, all you have got to B

pictured in Figure 14-7.

worry about is the environmental impact of meat

a

Note on the side of the Hydro-Que the gas

production!

r

regulator and flash arrestor. The regulator allows If you’re around in the Shetland Islands, check

b

you to vary how much hydrogen is burned, and

out the PURE Energy Centre, where they have

e

thus how much heat is produced by the barbecue.

c

converted a standard barbecue to run on hydrogen u

The flash arrestor prevents the flame from

with some clever pengineering—check out their

e

traveling back down the pipe and igniting the

fuel cells, and pop by for a sausage!

175

This page intentionally left blank

Chapter 15

Fuel Cell Competitions

If you are interested in taking some of the projects in this book further, there are a number of competitions Contact details for the IYFCC

worldwide open to young people. Competitions are a great way to make use of your skills—hone and

refine them, and receive recognition for things that Kay Larson: Director

you have learned. Throughout this book, I’ve flagged kay@iyfcc.com

up exciting projects which you might like to develop Quinn Larson: Student contact and travel

further for science fairs—another great way of

quinn@iyfcc.com

showcasing your knowledge and educating your

Bridget Shannon: Sponsor contact

peers about the hydrogen future.

bridget@iyfcc.com

This chapter gives details of all the competitions Phone: 303-237-3834

that are accessible to young people at the time of going to press; however, stay in touch with your Fax: 303-237-7810

National Fuel Cell Association, and keep your eyes Address:

peeled for more—as with growing awareness of

PO Box 4038

hydrogen and fuel cell science, there are sure to be Boulder, CO 80306

new competitions in the future!

The great thing about this competition is that it High school competitions

tests your knowledge of fuel cells on so many

levels—there is a theoretical element to the

competition, in the form of a “quiz bowl,” and

International Youth Fuel Cell

there are some practical, constructional challenges, Competition (IYFCC)

where you can apply things that you have learned in this book to build a fuel cell car, and a timepiece The international youth fuel cell competition is powered by fuel cell.

open to young people from around the world. Each country is allowed to select up to three teams to enter the competition—a good starting point would be to contact your National Fuel Cell Association, some addresses of which are listed in the back of this book, to find out about your national entry procedure.

The competition is open to students between the

ages of 15 and 18, and an official team consists of Go to the official IYFCC. website for further

two entrants.

information: www.iyfcc.com

177

Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.

practice fuel cell with the new fuel cell at the competition. We do not recommend you travel on

Fuel cell car—things to think

an airplane with the fuel cell unless you check it in about

checked baggage. The motor will be the same one

provided in the competition kit. You will have

Think about the power-to-weight ratio of your

access to a new motor at the competition, or you vehicle—the power produced by the supplied fuel

may continue to use the one provided in the

cell is fixed—you cannot change that! (But what

competition kit. You may use any other parts included you can do is ensure that your vehicle is as light in the practice kit, but you are not required to do so.

as possible!) Also consider the torque and speed 2.

Are there any prohibited items?

produced by your motor—match the power

You may not use hydrides or compressed hydrogen

available from your motor as closely as possible storage. You may not use additional motors or fuel with the load, the wheels!

cells other than those required. If you are unsure about a component, please contact Kay Larson for approval of questionable components (see the

IYFCC Contact Details box).

Fuel cell timepiece—things to

3.

What are we allowed to bring with us?

think about

You may bring a car that is completely built.

However, remember that you will need to replace the Think back to the experiments where we

fuel cell and in doing so, you might need to make produced hydrogen using a PEM fuel cell as an

some adjustments to your car at the competition.

electrolyser, and when we took hydrogen and

4.

What will you provide for us to use to make

oxygen and converted them using the fuel cell

adjustments?

into electrical power—what did you notice about

the reaction when a fixed amount of power was

There is a picture on the website that includes all of consumed or produced? Was the gas produced

the tools and materials that will be available to you s

at a steady rate or did it vary? Think about the at the competition. Each team will have access to n

properties of hydrogen—it is lighter than air.

all of the tools and materials. Your car may be

o

Could you trigger a physical action using the

completely built, and you might not need to use any i

lightness of hydrogen gas once a given amount

of the tools or materials. They are available for you t

has accumulated? Think about the airships in the in the event that you need to make major changes, i

chapter on hydrogen transport—think about the

or if you prefer to build your car at the competition t

formula used to calculate how much hydrogen is

using these materials.

e

required to lift a given weight. Think about

5.

How much time will we have to work on our car p

electrical power from a fuel cell—could that be

at the competition?

mo used to trigger an action? How could you feed You will have a work day, which is about eight

C

hydrogen to a fuel cell, once a given amount has hours. You can divide your time however you

been produced by an electrolyzer?

choose between working on your car, your

l

timepiece, or studying for the quiz bowl.

l Car competition

e

Timepiece competition

C 1. What components are we required to use on the car?

1.

What components are we required to use on the le

You must use the fuel cell provided at the

timepiece?

u

competition. It may have more power than the one The only component you are required to use is the F

you receive in the practice kit. You must replace the fuel cell you will receive at the competition.

178

F

2.

Are there any prohibited items?

you want to work on your timepiece, your car, or u

You may not use anything that has a timing device studying for the Quiz Bowl.

e

in it. The intent of the competition is that the use of l

hydrogen production and/or storage must be the

Rules and guidelines for the

element that determines the length of time.

C

quiz bowl

e

3.

What do you mean by “something must happen”

l

at exactly two minutes?

Purpose

l

At two minutes, there must be some noticeable and predicted event. It could be that something happens The purpose of the International Youth Fuel Cell C

at two minutes. It can also be that something stops Competition Quiz Bowl is to encourage the study

o

happening at two minutes.

of fuel cell technology, and to acknowledge the

m

acceptance of scientific principles as a global

4.

Can we use the fuel cell in electrolyzer mode p

only if we want to for this competition?

educational standard.

et

Yes, you can use the fuel cell just as an electrolyzer i

making hydrogen in this competion.

Matches

t

5.

Can we make hydrogen before the two minutes

i

The competition will consist of preliminary rounds begin?

o

and a final round. Teams in the final round will be n

Yes, you will have 10 minutes to prepare your

determined by a double elimination tournament

s

timepiece before your timing begins. You may

format. Teams will be chosen at random for the

use as much of this time as you like to produce

preliminary round of questioning, except that

hydrogen.

teams from the same country will not compete

6.

How much of the timepiece can we build before against each other in the preliminary round. After we come?

the first round, teams from the same country may You may bring a completed timepiece with you.

compete against one another.

Please remember that you will be required to

change the fuel cell to a new fuel cell at the

competition, and this fuel cell may be more

Rules for the quiz bowl

powerful than the one in the practice kit. Be

prepared to make adjustments.

1.

Two types of questions will be used: toss-up and 7.

What will you provide for us to use to make

bonus questions. A toss-up question may be

adjustments?

answered by any member of either team that

is playing. The toss-up question must be answered There is a picture on the website that includes all correctly, in order for a team to be offered

of the tools and materials that will be available to a bonus question.

you at the competition. Each team will have access to all of the tools and materials. Your car may be 2.

No team will have more than one opportunity

completely built, and you might not need to use any to answer a toss-up question.

of the tools or materials. They are available for you 3.

Questions are either multiple-choice or short

in the event that you need to make major changes, answer. The only acceptable answer to a

or if you prefer to build your car at the competition multiple-choice question is the one read by

using these materials.

the moderator.

8.

How much time will we have to make

4.

Once read in its entirety, a question will not be adjustments at the competition?

reread.

You will have a work day, which is about eight

5.

On toss-up questions, the first player on either team hours. You may determine how much of this time

to activate the lock-out buzzer system wins the right 179

to answer the question. No player may buzz in until Timing begins after the moderator has completed

after the moderator has identified the subject area reading the toss-up question.

of the question, e.g., physical science.

14. A student who has buzzed in on a toss-up question 6. Before answering the questions, the team member must answer the question promptly after being

must be verbally recognized by the moderator

verbally recognized by the moderator or scientific or scientific judge. (Before the match, this

judge. After recognizing a student, the moderator person will be identified.) If not recognized,

will allow for a natural pause (up to three seconds), it is treated as a nonanswer and the moderator

but if the moderator determines that stalling

will not indicate whether the answer was right

occurred, the team loses its opportunity to answer or wrong.

the question and it is offered to the opposing team, 7. No consultation is allowed on toss-up questions.

if eligible.

8. Should a player answer a toss-up question before 15. After a team member has answered a toss-up

being verbally recognized, or should consultation question correctly, the team is given the opportunity among any of the team members occur, any answer

to answer a bonus question. The team will have

given does not count (the moderator does not say 30 seconds to begin to give its answer to the bonus whether the answer given was correct or incorrect), question. Consultation among team members is

and the team loses the right to answer the toss-up allowed on bonus questions.

question. The question is then offered to the

16. On a bonus question, the signal “5 SECONDS” will opposing team.

be given by the timekeeper after 25 seconds of the 9. On a toss-up question, the first answer given is the allowed 30 seconds have expired. Additionally, the only one that counts. However, if a student gives timekeeper will indicate the end of the 30-second both a letter answer and a scientific answer, both bonus period by saying “TIME.” If the team captain parts must be correct.

has not begun the response before the timekeeper calls “TIME,” the answer does not count. If the

10. If the answer to a toss-up question is wrong and the team captain has begun the response, he or she

question was completely read, the other team is

may complete the answer.

given the opportunity to answer the toss-up

sn

question, unless time expires before the second

o

team has buzzed in. The second team is allowed a Scoring

i

full 10 seconds to buzz in after the first team has t

answered incorrectly or has answered without being 17. Toss-up questions are worth four points, and bonus i

recognized, unless time expires.

questions are worth 10 points.

t 11. The answer to the bonus question must come from 18. If a toss-up question is interrupted, the student e

the team’s captain. Moderators should ignore an

recognized, and the answer correct, the team will p

answer from anyone but the captain on the bonus

receive four points. If the answer is incorrect, four m

question.

points are added to the opposing team’s score, the o

question is reread in its entirety, and the opposing C Timing rules

team has an opportunity to answer the toss-up

question with the chance to answer the bonus

l 12. The match is played until either the time expires or question if correct.

l

all the toss-up questions have been read. Regional e

19. The double interrupt—if a toss-up question is competitions will have two 10-minute halves with a C

interrupted, the student has been verbally

two-minute break. Each half begins with a toss-up recognized and the answer is incorrect, four points question.

l

are added to the opposing team’s score. The

e 13. After reading a toss-up question, the moderator will question is then reread in its entirety. However, u

allow 10 seconds for the two teams to respond

if a student on the opposing team interrupts the F

before proceeding to the next toss-up question.

rereading of the question, the player is verbally 180

F

recognized and gives an incorrect answer. Four

All challenges must be made before the next

u

points are added to the other team’s score. The

question is begun. The scientific judge and the

e

moderator will give the correct answer and move on moderator may consult during the match regarding l

to the next toss-up question.

responses. All decisions made by the judges

20. If the moderator inadvertently gives an answer to are final.

C

a toss-up question without giving either team a

24. Should a question arise during a competition, the e

chance to respond, no points are awarded and the competition and the clock will be stopped until the l

moderator goes on to the next toss-up question.

question is resolved. Once the question has been l

21. If a toss-up question is interrupted, the student is resolved, the match will continue from that point.

C

not recognized and blurts out an answer, the result Should the moderator decide that some time was

o

is a nonanswer. No penalty points are awarded to lost due to the interruption, the moderator has the m

the opposing team. The moderator will not indicate right to put the appropriate amount of time back p

whether the answer was right or wrong and the

on the clock.

e

question is reread in its entirety to the

When time runs out

t

opposing team.

i

22. If the moderator inadvertently gives the answer to 25. If the question has been completely read, but t

a toss-up question before allowing the second team neither team has buzzed in, the game or half is over.

i

to respond (after an incorrect answer, or an answer o

26. If the question has been completely read, a student given without the team member having been

n

has buzzed in and is recognized before answering, recognized), the next toss-up question will be read s

and gives a correct answer, the team gets to answer to the second team in place of the inadvertently the bonus question. The half or game is then over.

answered question.

27. If the question has been completely read, a student Summary of Scoring:

has buzzed in and is recognized before answering, but gives the wrong answer or answers before being Type of Question

Points Awarded

verbally recognized, the game or half is over.

Toss-up

+4 points, and eligible

28. If the question has been completely read, a student for bonus

has buzzed in and time is called before the student Bonus

+10 points

has been recognized, the moderator or scientific Incorrectly answered

+4 points to opposing

judge will verbally recognize the student. If the team

student gives a correct answer, the team gets to answer the bonus question. If an incorrect answer is Interrupted toss-up

+4 points to opposing

given or the student answers before being verbally team

recognized, the game or half is over.

Unrecognized and

If the question has NOT been read completely interrupted toss-up

+0 points

before time runs out:

Unrecognized toss-up

+0 points

29. If the question has not been completely read by the moderator and neither team has buzzed in

Challenges

(interrupted), the game or half is over.

30. If a team member buzzes in before time is called, 23. Challenges to questions and responses will be interrupting the reading of the question, is verbally permitted. Team members may also challenge a

recognized, and answers the question correctly, the ruling, the score, or a protocol issue. A challenge team gets to answer the bonus question. The half or can only be made by a team member who is actively game is then over.

competing. A challenge may not be made by the

31. If a team member buzzes in before time is called, coach, alternate, or by anyone else in the audience.

interrupting the reading of the question, and is 181

verbally recognized, but answers the question

Rules for the end of a single or double

incorrectly, penalty points are awarded, the question elimination match

is reread for the other team, which is then given the chance to answer both the toss-up question

51. If the score is tied in a single or double elimination and, if correct, the bonus question before the

match at the end of the regulation time period, a contest or half is over.

series of five toss-up questions will be used to break 32. If a team member buzzes in before time is called, is the tie. Interrupt penalties are in effect. Round robin not verbally recognized, and blurts out the answer, matches may end in a tie, as explained in rule

the answer is not accepted but no penalty points are 15 above.

awarded. The question is read in its entirety for the other team which, if it answers correctly, is also Miscellaneous science bowl rules

given a chance to answer the bonus question before the contest or half ends.

52. No one in the audience may communicate with

participants during the match; communication will result in a warning, and if the problem persists could Rules for entering the final round

result in an ejection from the competition room.

33. In the event that the required number of teams 53. If someone in the audience shouts out an answer, from each division is not clearly identifiable

the question will be thrown out (as will the person),

[resolution is necessary only between teams tied for and the moderator will proceed to the next question.

last position(s) to advance to the single or double 54. Prior to each match, the two team coaches will elimination], a tie-break procedure in the following introduce themselves to each other and will sit

order will be used:

together in the back row of the competition room.

a)

Head to head won/loss record

55. No notes may be brought to the competition.

b)

Fewest losses

Nothing may be written before the clock starts.

c)

If two teams are still tied, there will be a five Scratch paper will be provided at the beginning of s

toss-up question run-off (interrupt penalty in

each match, and collected at half-time and at the n

effect). No bonus questions will be used during

conclusion of the match.

o

this segment of the competition. If still tied,

56. Calculators are not permitted.

i

another five toss-up question run-off will be

57. Members of the audience, including the coaches, t

used, etc. until the advancing team is

will not write down the questions or answers the i

determined.

moderator reads, or use any electronic recording or t

d)

If more than two teams are tied, each team, in

transmitting device, including digital cameras

e

separate rooms, will be given a series of 10

during the match. At the nationals, coaches will be p

toss-up questions (no bonus questions will be

provided with a team score sheet to track the

m

used during this segment of the competition).

number of questions answered by each individual

o

The usual 10 seconds will be allowed for a

student on their team. No one else in the

C

competitor to buzz in after the question is

competition room is permitted to make notes of any completely read. There are no interrupt

kind during the active competition. If this occurs, l

penalties but also no reason to interrupt since

the individual(s) will be asked to leave the

le

all 10 questions will be read. Scoring will be

competition room.

C

based on the number of questions right minus

the number wrong. If two or more teams are

l

still tied, procedure (iii) or (iv), as appropriate, Hydrogen student design contest

e

will be used until the advancing teams are

u

determined.

The hydrogen student design contest is an annual F

[. . .]

competition that takes students with a knowledge 182

F

of fuel cell technology, and gets them to apply this u

knowledge to a design problem. The contest

e

focuses on practical applications utilizing

l

hydrogen and fuel cells.

C

More info about the DOE Science Bowl can be

e

found at:

l

www.scied.science.doe.gov/nsb/index.html

l

C

Further information is available from:

o

www.hydrogencontest.org/

m

Fuel Cell Box (Germany)

p

The rules vary every year as different challenges e

are set annually.

A national competition to raise awareness about

t

fuel cell technology among schoolchildren in

i

Germany called “Fuel Cell Box” may be of

t

Department of Energy National

interest to you. Further information, in German, is i

Science Bowl (United States)

available from www.fuelcellbox.de.

on

The DOE National Science Bowl includes an event

s

in the finals—the “Hydrogen Fuel Cell Model Car

Challenge.” For this, apply principles that you have learned from the chapter on hydrogen transport

(Chapter 13).

183

This page intentionally left blank

Appendix

A

Everything You Wanted to Know

About Hydrogen ... and Then Some

Chemical series

Nonmetals

Data

Value

Group

Period, Block 1, 1, s

Boiling point

20.28 K (−252.87Њ C,

Electron configuration

1s1

− 423.17Њ F)

Electrons per shell

1

Triple point

13.8033 K, 7.042 kPa

Appearance

Colorless

Critical point

32.97 K, 1.293 MPa

Heat of fusion (H )

0.117 kJ·mol−1

2

Gas* (m3)

Liquid (liter)

Weight (kg)

Heat of vaporization (H ) 0.904 kJ·mol−1

2

1

1.163

0.0898

Heat capacity

28.836 J·mol−1·K−1

0.856

1

0.0709

(25° C) (H )

2

12.126

14.104

1

Thermal conductivity

180.5 mW·m−1·K–1

(300 K)

*m3 at 981 mbar and 15° C

Speed of sound

(gas, 27Њ C) 1310 m/s

Data

Value

CAS registry number

1333-74-0 (H )

2

Density

0.08988 kg/nm3

Crystal structure

hexagonal

Upper heating value

12.745 MJ/nm3

Oxidation states

1, −1

Lower heating value

10.783 MJ/nm3

Electronegativity

2.20 (Pauling scale)

Ignition energy

0.02 MJ

Ionization energies

1st: 1312.0 kJ/mol

Ignition temperature

520Њ C

Atomic radius

25 pm

Lower ignition level

(gas concentration in air)

Atomic radius (calc.)

53 pm (Bohr radius)

4.1 Vol%

Covalent radius

37 pm

Upper ignition level

(gas concentration in air)

Van der Waals radius

120 pm

72.5 Vol%

Flame rate

2.7 m/s

Melting point

14.01 K (−259.14Њ C,

− 434.45Њ F)

185

Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.

Hydrogen density compared to other fuels:

..

Hydrogen

Gasoline

Diesel

Natural gas

Methanol

. Density (kg/l)

0.0000898

0.702

0.855

0.00071

0.799

Density (kg/m3)

0.0898

702

855

0.71

799

n Energy density (MJ/kg)

120

42.7

41.9

50.4

19.9

eg Energy density (MJ/l)

0.01006

31.2

36.5

0.00361

15.9

o Energy density (MJ/m3)

10783

31200

36500

36.1

18000

r Energy density (kWh/kg)

33.3

11.86

11.64

14

5.53

d Energy density (kWh/m3)

2.79

8666.67

10138.88 10.02

4420

y All numbers are at lower heating value and at atmospheric pressure and normal temperature.

H

tuobA

wonK

ot

detnaW

uoy

gnihtyrevE

186

Appendix B

Fuel Cell Acronym Buster

In the world of fuel cells, they love to abbreviate FCEV fuel cell electric vehicle

things! You will come across some of these

GHG greenhouse gas

acronyms in this book, while others you will find H hydrogen

are used in conversation and other books when

2

looking at fuel cells and their applications. This HC hydrocarbons

handy little guide should help to debunk the TLAs ICE internal combustion engine

(Three Letter Acronyms) into something a little

LPG liquefied petroleum gas

more intelligible.

MCFC molten carbonate fuel cell

AFC alkaline fuel cell

MEA membrane electrode assembly

AFV alternative fuel vehicle

MeOH methanol

BEV battery electric vehicle

NABH sodium borohydride or sodium

4

CH OH methanol

3

tetrahydroborate

CH CH OH ethanol

3

2

NO oxides of nitrogen

x

CHP combined heat and power

O oxygen

2

CNG compressed natural gas

PAFC phosphoric acid fuel cell

CO carbon monoxide

PEFM polymer electrolyte fuel cell

CO carbon dioxide

2

PEM proton exchange membrane or polymer

DMFC direct methanol fuel cell

electrolyte membrane

FC fuel cell

PEMFC PEM (see above) fuel cell

FCEV fuel cell electric vehicle

Pd palladium

GDE gas diffusion electrode (See GDM)

Pt platinum

GDM gas diffusion media/membrane (See GDE) SOFC solid oxide fuel cell

FC fuel cell

URFC unitized regenerative fuel cell

187

Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.

This page intentionally left blank

Appendix C

Fuel Cell Associations

If you are interested in finding out what schools, Fuel Cell Europe

colleges, and universities run courses in your area, Fuel Cell Europe

or if you are interested in work experience and

World Fuel Cell Council e.V.

want to find a suitable company, or if you are

Frankfurter Strasse 10-14,

simply interested in what’s happening with

hydrogen in your area, contact your local hydrogen D-65760 Eschborn

association, where they will be more than happy to Germany

give you information to further your interest in www.fuelcelleurope.org

hydrogen and fuel cells.

Fuel Cells UK

Europe

Synnogy Ltd

1 Aldwincle Road

European Hydrogen Association

Thorpe Waterville

Gulledelle 98

Northants NN14 3ED

1200 Bruxelles

Tel: 44 (0)1832 720007

Belgium

E-mail: info@fuelcellsuk.org

Tel: 32 2 763 25 61

www.fuelcellsuk.org

Fax: 32 2 772 50 44

German Fuel Cell Association

E-mail: info@h2euro.org

Unter den Eichen 87

www.h2euro.org

12205 Berlin

French Hydrogen Association

Germany

Tel: (49-700) 49376 835 (hydrotel)

Association Française de l’Hydrogène

Fax: (49-700) 49376 329 (hydrofax)

28, rue Saint-Dominique

E-mail: h2@dwv-info.de

75007 Paris

Tel: 33 (0)1 53 59 02 11

Norwegian Hydrogen Forum

Fax: 33 (0)1 45 55 40 33

radix.ife.no/nhf/

E-mail: info@afh2.org

Polish Hydrogen and Fuel Cell Association

www.afh2.org/

Polskie Stowarzyszenie Wodoru i Ogniw

Paliwowych

molenda@uci.agh.edu.pl or

hydrogen@agh.edu.pl

E-mail: www.hydrogen.edu.pl

189

Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.

Scottish Hydrogen and Fuel Cell Association

Hydrogen and Fuel Cells Canada

Brunel Building

4250 Wesbrook Mall

James Watt Avenue

Vancouver, B.C. V6T 1W5

Scottish Enterprise Technology Park

Tel: 604-822-9178

East Kilbride

Fax: 604-822-8106

G75 0QD

E-mail: admin@h2fcc.ca

Scotland

National Hydrogen Association

Tel: 44 7949 965 908

Main Office:

www.shfca.org.uk

1800 M St NW, Suite 300 North

Spanish Hydrogen Association

Washington, DC 20036-5802

Asociación Española del Hidrógeno

U.S.A.

Head Office:

Tel: 202-223-5547

c/o Isaac Newton, 1

Fax: 202-223-5537

PTM. Tres Cantos

Western U.S. Office

28760 Madrid

35 Seacape Drive

Spain

Sausalito, CA 94965

CIF: G-83319731

Tel: 415-381-7225

Tel: 34.654.80.20.50

Fax: 415-381-7234

Fax 34.91.771.0854

E-mail:infoWestUS@ttcorp.com

E-mail: info@aeh2.org (about AeH2)

www.hydrogenassociation.org/

E-mail: aeh.web@ariema.com (about this website)

aeh2.org/en/index.htm

North Carolina Sustainable Energy Association NCSEA

America

PO Box 6465

Raleigh, NC 27628-6465

American Hydrogen Association

Tel: 919-832-7601

2350 W. Shangri La

E-mail: ncsea@mindspring.com

Phoenix, AZ 85028

www.ncsustainableenergy.org/

Tel: (602) 328-4238

Fuel Cells Texas

c/o Good Company Associates Inc.

816 Congress Avenue, Ste. 1400

Austin, TX 78701

Tel: (512) 279-0750

Fax: (512) 279-0760

Fuel Cell Associations www.fuelcellstexas.org/

190

Fuel Cell Associations

Asia

Oceania

China Association for

National Hydrogen Association of Australia

Hydrogen Energy (CAHE)

13 Mount Huon CCT

Room 710

Glen Alpine

No. 86 Xueyuan Nanlu

Campbelltown

Beijing

New South Wales 2560

100081

Australia

China

Tel: 61 2 9603 7967

Tel: (86-10) 62180145

Fax: 61 2 9603 8861

Fax: (86-10) 62180142

www.hydrogen.org.au/nhaa/

191

This page intentionally left blank

Epilogue

What does the future hold for fuel cells? Why

It’s also going to enable us to use increased

don’t I ask you the same question? You’re the one amounts of renewable energy as part of our energy with this book in your hand, a head full of great generation portfolio—we can only produce solar

ideas, and a desk full of fuel cell equipment—go power when the sun shines, and wind power when

and create the next generation of sustainably

the wind blows, but we need mechanisms to store

powered inventions, gadgets, and gizmos.

it when it’s being produced but not used. Again, Fuel cells have already undeniably helped to

fuel cells are very helpful here as they enable us to shape the world—they’ve helped us in our quest

“mop up” spare energy when a surplus is being

to conquer the mysteries of space, by producing

produced, and store it as hydrogen later to

electricity to power space capsules, while providing be used as a transport fuel, or converted into

water for astronauts to drink. They’ve also helped us electricity.

subjugate the oceans, allowing submarines to stay At the PURE Energy Centre, Shetland, UK and

underwater for weeks on end.

the HARI project, West Beacon Farm, UK, they

The challenge now, as the technology finds

are doing just that—learning by experiment, just more applications, is to vanquish our addiction to as you’re doing with this book, how to use

carbon-based fuels. It’s a bad habit which we’ve hydrogen produced from renewables to meet

acquired over the past couple of centuries, but one their energy needs.

that we need to kick quickly, as we have limited The technology is developing every day,

resources, and are faced by the problems of

and every person that joins the army of

environmental degradation, photochemical smog,

scientists, engineers, technologists, and

and the threat of climate change—all nasty side-effects product designers working to bring fuel cells

of an infatuation with coal and oil.

onto the market and into the mainstream,

The fuel cell will enable a cleaner economy—

helps the movement gain a little bit of

based on hydrogen, not carbon—facilitating a

momentum.

transition to greener technologies and new models The future is bright for hydrogen—Hjaltland

for providing power and energy services. Fuel cell Housing Association, along with the PURE Energy

technology is going to release consumers of power Centre and Fuel Cells Scotland, have released

from the shackles, and inefficiency of centralized plans for the world’s first off-grid fuel cell houses.

thermal generation (where the bulk of the input

The houses will have wind turbines in their yard to energy is wasted as heat) to new modes of

produce power, and will turn this power into

decentralized generation, where the heat produced hydrogen which can be used to meet the homes’

from an energy conversion process is used to

energy needs.

good effect—to heat your home or to warm your

community’s swimming pool, rather than being

This sort of development provides a blueprint

wasted into the atmosphere in plumes of

for clean homes around the world, and could be

smoke.

coming to a block near you.

193

Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.

price, or that games console that a couple of

Christmases ago was at a premium price, but now

has dropped in price and is a bit more affordable?

It’s all proof that there is a relentless drive to engineer the cost out of technology to make it

accessible to a wider marketplace. Fifty years ago, it would have been inconceivable for every one of the world’s large corporations to have a computer.

Today, they are on the desk of every employee,

and furthermore—with initiatives like “One Laptop Architects drawing for Hjaltland Housing Association Per Child”—the technology is even accessible to

fuel cell homes. Image courtesy PURE Energy Centre the developing world. The same will happen with

fuel cells. Problems are surmounted, cheaper ways Don’t let people put you off fuel cells by saying to make better products are found, and the

that they are expensive and will never be affordable—

products become ubiquitous.

remember that big TV your Pa wanted a few years

So watch out . . . fuel cells may be coming to a ago, but was a touch on the pricey side . . . that he home near you. In fact . . . they already have!

bought last week because it was a third of the

Epilogue

194

Index

Page numbers for figures and tables are given in bold energy production, 20–21, 20

A

equations, balanced, 25

alkaline fuel cell, 6, 7, 7, 74

alkaline solutions for, 67

F

chemistry of, 57, 57, 58, 59

flow fields, 82–81, 83, 123–125, 123, 124, 125

hydrogen carriers for, 68

fossil fuels, 15–16, 23, 24

IV measurement of, 63–64, 64, 65

fuel cell

making electricity with, 59–63

alkaline ( see alkaline fuel cell)

oxygen and, 71–74, 73

applications, practical, 6–8, 6, 7, 107, 142–144, 144, poisoning, 70, 70

163–164, 169–172, 170, 174–175, 174, 175, 193

power curve of, 66, 67

associations, 189–191

temperature and, 68–69

classification, 115

competitions, 177–183

B

disassembly, 84–85, 85, 86, 87

Bacon, Francis, 6, 6, 57

efficiency, 20–21, 20

Bacon Cell. See alkaline fuel cell

high temperature, 115–119, 116, 117, 118

biomass, 14–15, 23

history of, 1, 5–8, 6

Boyle, Robert, 1, 2

membrane ( see direct methanol fuel cell; PEM fuel cell) Boyle’s Law, 38, 39

methanol ( see direct methanol fuel cell) microbial ( see microbial fuel cell)

miniature, 90–91, 91, 92, 93, 93

C

molten carbonate, 117–118, 117

carbon dioxide, 15–16, 15, 16, 17–19, 18, 19

PEM ( see PEM fuel cell)

carbon emissions, 23–24. See also carbon dioxide phosphoric acid, 116–117, 117

carbon nanotube, 40–41, 42

platinum, 51–56, 53, 54, 55

carbon sequestration, 15–16, 23

scratch-built ( see scratch-built fuel cell) catalyst, 28–29, 54–55, 78, 80, 80, 88, 129

solid oxide, 118–119, 118

Cavendish, Henry, 1–2, 2

fuel cell vehicle

Charles, Jacques, 2, 2

hydrides powered, 156, 156

Charles’ Law, 2–3, 39–40

intelligent, 152–153, 154, 155

chemical hydride, 42, 43, 44, 44

radio-controlled, 157–162, 160, 161, 162

coal, 24

simple, 145–147, 146, 147, 148, 149, 149, 150, 151, 152, 152

complex hydride, 43, 44

technology, 21, 142–144, 143

cryogenic storage, 39–40, 40

vs. internal combustion engine, 141–142, 141, 142

D

G

Dalton, John, 3, 3

gas diffusion layer, 80–81, 80, 126

direct methanol fuel cell, 106

making your own, 129–131

activating, 98, 98

GDL. See gas diffusion layer

advantages of, 95

geothermal power, 14, 14

Band-Aid®, 100–105, 104, 105

Grove, Sir William Robert, 5, 5, 6, 51, 55, 56

chemistry of, 96, 96, 97

decommissioning, 99

H

recommissioning, 99

DMFC. See direct methanol fuel cell

HARI (Hydrogen and Renewables Integration Project), 34, 35, 36, 48

H-Gen, 46–48

E

high temperature fuel cell, 115–119, 116, 117, 118

electrolysis, 10, 11, 17, 23

Hoffman apparatus, 33, 33

using baking soda, 31–32, 32

hydrides, 41–45, 42, 43, 44

using a Hoffman apparatus, 33, 33

hydrogen, 9–11, 9, 10

using platinum, 53–55, 53, 54

density, 186

using renewable resources, 33–34, 35, 36

economy, 21–22, 22

195

Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.

hydrogen ( cont. )

history of, 1–5

O

production of ( see hydrogen production) oxidation, 27–28, 28, 57, 58, 59, 111–112, 111, 112

safety, 135–139

oxygen

storage of, 10, 37, 39–41, 40, 42, 44, 137

and fuel cells, 71–74, 73, 89

testing for, 24

pure, 26, 71–72, 89

transport ( see fuel cell vehicle; hydrogen air travel; hydrogen testing for, 26, 26

space travel)

See also fuel cell

P

hydrogen air travel

airship, 166–168, 167

Paracelsus, 1, 1

planes, 163, 163

Peak oil, 19, 20

hydrogen production

PEM fuel cell, 6–7, 7, 77

by acid-metal reactions, 27–30, 27

disassembly, 84–85, 85, 86, 87

“dirty”, 15, 15–17, 16, 17, 23–24

mechanism of action, 77–81, 77, 78, 79, 80

“green”, 10–15, 23, 24, 33–34, 35, 36, 45–46

miniature, 90–91, 91, 92, 93, 93

using platinum, 51–55, 53, 54

platinum catalyst effect on, 88, 88

hydrogen space travel, 164–165, 165, 166

phosphoric acid fuel cell, 116–117, 117

hydro power, 13

photoelectrolysis, 24

plastic electrolyte membrane fuel cell. See PEM

fuel cell

I

proton exchange membrane fuel cell. See PEM fuel cell Ihrig, Harry, 6, 6

PURE Energy Centre, 33–34, 48–49

L

R

Lavoisier, Antoine, 3, 3

reduction, 27–28, 28, 57, 58, 59, 111–112, 111, 112

M

S

MEA. See membrane electrode assembly

Schönbein, Christian, 5–6, 6

membrane electrode assembly (MEA), 87, 125–126

scratch-built fuel cell

making a, 126–128

end plates for, 121–123

platinum loading and, 88, 88

flow fields for, 123–125

Mendeleev, Dmitri, 3, 5, 5

gas diffusion layer for, 129–131

metal hydride, 37, 41, 43, 44, 45

membrane electrode assemblies for, 125–128, 131–133

metals, activity series of, 31

solar power, 11–12, 23, 35

microbial fuel cell, 107

solid oxide fuel cell, 118–119, 118

future of, 107–108

steam reformation, 15, 23–24

history of, 107

with mediator, 112–113, 113

T

without mediator, 108–112, 111, 112

molten carbonate fuel cell, 117–118, 117

tidal power, 13–14

N

W

NafionTM, 80, 80–82, 82, 101, 126–127, 127

wave power, 13–14, 14

nuclear power, 16

wind power, 12–13, 34, 34, 35

xednI

196

Table of Contents

Chapter 1

Chapter 2

Chapter 3

Chapter 4

Chapter 5

Chapter 6

Chapter 7

Chapter 8

Chapter 9

Chapter 10

Chapter 11

Chapter 12

Chapter 13

Chapter 14

Chapter 15