The authors acknowledge the following reviewers:

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3 The authors acknowedge the foowing reviewers: Los Aamos Nationa Laboratory Shimshon Gottesfed Chares F. Keer Steffen MØer-Host Antonio Redondo Office of Advanced Automotive Technoogies, U.S. Department of Energy JoAnn Miiken Los Aamos Nationa Laboratory, an affirmative action/equa opportunity empoyer, is operated by the University of Caifornia for the US Department of Energy under contract W ENG-36. A company names, ogos, and products mentioned herein are trademarks of their respective companies. Reference to any specific company or product is not be construed as an endorsement of said company or product by the Regents of the University of Caifornia, the United States Government, the US Department of Energy, nor any of their empoyees. The Los Aamos Nationa Laboratory strongy supports academic freedom and a researcher s right to pubish; as an institution, however, the Laboratory does not endorse the viewpoint of a pubication or guarantee its technica correctness. LA-UR

4 What s Inside Fue Ces Green Power was written by Sharon Thomas and Marcia Zabowitz at Los Aamos Nationa Laboratory in Los Aamos, New Mexico Designed by Jim Cruz 2. A Brief History 4. The Very Basics and More 5. Some Comparisons 7. The Poymer Eectroyte Membrane Fue Ce 15. Other Types of Fue Ces 19. What About Fue? This pubication has been funded by the Office of Advanced Automotive Technoogies Office of Transportation Technoogies Energy Efficiency and Renewabe Energy U.S. Department of Energy The 3M Foundation For more information: Appications for Fue Ces 24. Hydrogen as A Fue 27. Getting To Ceaner Transportation 28. Oi Reserves, Transportation, and Fue Ces 29. Cimate Change, Greenhouse Gases, and Fue Ces: What is the Link? 32. A Once-In-A-Lifetime Opportunity 1

5 Lamps, burning coa oi and coa gas, it the iving rooms of most homes of the eary 1900 s. But when eectric ight bubs repaced those smoky, smey sources of iumination, homes became brighter, ceaner, and safer. At first ony the weathy coud afford eectric ights. But as the demand went up and the cost went down, more and more of the popuation were abe to afford eectric ighting even though there was penty of coa to continue ighting buidings in the usua way. The better technoogy won. I cannot but regard the experiment as an important one... A Brief History Wiiam Grove writing to Michae Faraday, October 22, 1842 Athough fue ces have been around since 1839, it took 120 years unti NASA demonstrated some of their potentia appications in providing power during space fight. As a resut of these successes, in the 1960s, industry began to recognize the commercia potentia of fue ces, but encountered technica barriers and high investment costs fue ces were not economicay competitive with existing energy technoogies. Since 1984, the Office of Transportation Technoogies at the U.S. Department of Energy has been supporting research and deveopment of fue ce technoogy, and as a resut, hundreds of companies around the word are now working towards making fue ce technoogy pay off. Just as in the commerciaization of the eectric ight bub neary one hundred years ago, today s companies are being driven by technica, economic, and socia forces such as high performance characteristics, reiabiity, durabiity, ow cost, and environmenta benefits. D.S. Scott and W. Hafee. The Coming Hydrogen Age: Preventing Word Cimate Disruption. Internationa Journa of Hydrogen Energy. Vo. 15, No. 10, In 1839, Wiiam Grove, a British jurist and amateur physicist, first discovered the principe of the fue ce. Grove utiized four arge ces, each containing hydrogen and oxygen, to produce eectric power which was then used to spit the water in the smaer upper ce into hydrogen and oxygen.

6 In March 1998, Chicago became the first city in the word to put poution-free, hydrogen fue ce powered buses in their pubic transit system. (Courtesy: Baard Power Systems) The automobie, it is fair to say, changed the industria and socia fabric of the United States and most countries around the gobe. Henry Ford epitomized Yankee ingenuity and the Mode T heped create the open road, new horizons, abundant and inexpensive gasoine...and taipipe exhaust. More peope are driving more cars today than ever before more than 200 miion vehices are on the road in the U.S. aone. But the car has contributed to our air and water poution and forced us to rey on imported oi from the Midde East, heping to create a significant trade imbaance. Today many peope think fue ce technoogy wi pay a pivota roe in a new technoogica renaissance just as the interna combustion engine vehice revoutionized ife at the beginning of the 20th century. Such innovation woud have a goba environmenta and economic impact. In today s word, soving environmenta probems is an investment, not an expense. The first fue ce powered bicyce to compete in the American Tour-de-So. (Courtesy: H-Power) Wiiam Cay Ford, Jr. Chairman and CEO, Ford Motor Company, September 1998 Fue ces are not just aboratory curiosities. Whie there is much work that needs to be done to optimize the fue ce system (remember, the gasoine interna combustion engine is neary 120 years od and sti being improved), hydrogen fue ce vehices are on the road now. Commuters iving in Chicago and Vancouver ride on fue ce buses. You can take a ride around London in a fue ce taxi and even compete in the American Tour de So on a fue ce bicyce. Every major automobie manufacturer in the word is deveoping fue ce vehices. To understand why fue ces have received such attention, we need to compare them to existing energy conversion technoogies. The FutureCar Chaenge, sponsored by the U.S. Department of Energy, presents a unique assignment to students from North America s top engineering schoos: convert a conventiona midsize sedan into a super efficient vehice without sacrificing performance, utiity, and safety. In 1999, the Virginia Tech team entered the competition with a fue ce vehice. The mission of our goba fue ce project center is nothing ess than to make us the eader in commerciay viabe fue ce powered vehices. Harry J. Pearce, Vice Chairman, Board of Directors, Genera Motors. May

7 Where the Action in Fue Ces is Today Aied Signa Vovo Baard DaimerChryser Detroit Edison DuPont She Ford Genera Motors Honda Mazda Georgetown University Case Western Reserve University Los Aamos Nationa Laboratory Motoroa Penn State University Princeton University Ros-Royce Argonne Nationa Laboratory Sanyo DAIS Siemens British Gas Pug Power University of Michigan Texas A&M University ARCO Epyx Internationa Fue Ces H-Power Energy Partners Hydrogen Burner W.L. Gore A.D. Litte Institute of Gas Technoogy Vairex Eectrochem Giner Jet Propusion Laboratory Toyota University of Caifornia Exxon Westinghouse Renaut 3M Nissan BMW PSA Peugeot Citroën Texaco University of Forida Tokyo Eectric Power (This is just a partia ist) Hydrogen Anode (-) Oxygen Carnot Cyce vs. Fue Ces T he theoretica thermodynamic derivation of Carnot Cyce shows that even under idea conditions, a heat engine cannot convert a the heat energy suppied to it into mechanica energy; some of the heat energy is rejected. In an interna combustion engine, the engine accepts heat from a source at a high temperature (T 1 ), converts part of the energy into mechanica work and rejects the remainder to a heat sink at a ow temperature (T 2 ). The greater the temperature difference between source and sink, the greater the efficiency, Maximum Efficiency = (T 1 T 2 ) / T 1 where the temperatures T 1 and T 2 are given in degrees Kevin. Because fue ces convert chemica energy directy to eectrica energy, this process does not invove conversion of heat to mechanica energy. Therefore, fue ce efficiencies can exceed the Carnot imit even when operating at reativey ow temperatures, for exampe, 80 C. The Very Basics Catayst Eectrons Protons Cathode (+) Water Membrane/ Eectroyte A fue ce is an eectrochemica energy conversion device. It is two to three times more efficient than an interna combustion engine in converting fue to power. A fue ce produces eectricity, water, and heat using fue and oxygen in the air. Water is the ony emission when hydrogen is the fue. As hydrogen fows into the fue ce on the anode side, a patinum catayst faciitates the separation of the hydrogen gas into eectrons and protons (hydrogen ions). The hydrogen ions pass through the membrane (the center of the fue ce) and, again with the hep of a patinum catayst, combine with oxygen and eectrons on the cathode side, producing water. The eectrons, which cannot pass through the membrane, fow from the anode to the cathode through an externa circuit containing a motor or other eectric oad, which consumes the power generated by the ce. The votage from one singe ce is about 0.7 vots just about enough for a ight bub much ess a car. When the ces are stacked in series, the operating votage increases to 0.7 vots mutipied by the number of ces stacked.

8 How do Fue Ces Compare to Interna Combustion Engines and Batteries? W hat interna combustion engines, batteries, and fue ces have in common is their purpose: a are devices that convert energy from one form to another. As a starting point, et s consider the interna combustion engine used to power virtuay a of the cars driven on U.S. highways today. These engines run on noisy, high temperature exposions resuting from the reease of chemica energy by burning fue with oxygen from the air. Interna combustion engines, as we as conventiona utiity power pants, change chemica energy of fue to therma energy to generate mechanica and, in the case of a power pant, eectrica energy. Fue ces and batteries are eectrochemica devices, and by their very nature have a more efficient conversion process: chemica energy is converted directy to eectrica energy. Interna combustion engines are ess efficient because they incude the conversion of therma to mechanica energy, which is imited by the Carnot Cyce. If cars were powered by eectricity generated from direct hydrogen fue ces, there woud be no combustion invoved. In an automotive fue ce, hydrogen and oxygen undergo a reativey coo, eectrochemica reaction that directy produces eectrica energy. This eectricity woud be used by motors, incuding one or more connected to axes used to power the whees of the vehice. The direct hydrogen fue ce vehice wi have no emissions even during iding this is especiay important during city rush hours. There are some simiarities to an interna combustion engine, however. There is sti a need for a fue tank and oxygen is sti suppied from the air. Many peope incorrecty assume that a eectric vehices (EVs) are powered by batteries. Actuay, an EV is a vehice with an eectric drive train powered by either an on-board battery or fue ce. Batteries and fue ces are simiar in that they both convert chemica energy into eectricity very efficienty and they both require minima maintenance because neither has any moving parts. However, unike a fue ce, the reactants in a battery are stored internay and, when used up, the battery must be either recharged or repaced. In a battery-powered EV, rechargeabe batteries are used. With a fue ce powered EV, the fue is stored externay in the vehice s Hydrogen is suppied to the Fue Ces Fue Ces Hydrogen Tank Chemica Energy (gaseous fow) Hydrogen Fue Ce Car Oxygen from the air and hydrogen combine in the fue ces to generate eectricity that is sent to the traction inverter modue Air is suppied to the fue ces by turbocompressor Eectrica Energy fue tank and air is obtained from the atmosphere. As ong as the vehice s tank contains fue, the fue ce wi produce energy in the form of eectricity and heat. The choice of eectrochemica device, battery or fue ce, depends upon use. For arger scae appications, fue ces have severa advantages over batteries incuding smaer size, ighter weight, quick refueing, and onger range. The poymer eectroyte membrane (PEM) fue ce is one in a famiy of five distinct types of fue ces. The PEM fue ce, under consideration by vehice manufacturers around the word as an aternative to the interna combustion engine, wi be used to iustrate the science and technoogy of fue ces. Eectric Motor/ Transaxe Mechanica Energy The traction inverter modue converts the eectricity for use by the eectric motor/ transaxes Traction Inverter Modue Turbocompressor The eectric motor/ transaxe converts the eectric energy into the mechanica energy which turns the whees The P2000, from Ford Motor Company, is a zero-emission vehice that utiizes a direct hydrogen poymer eectroyte fue ce. (Courtesy of Ford Motor Co.) 5

9 References: Bi McKibben, A Specia Moment in History. The Atantic Monthy, May, James J. MacKenzie, Oi as a Finite Resource: When is Goba Production Likey to Peak? Word Resources Institute, March Coin Campbe and Jean H. Laherrère The End of Cheap Oi. Scientific American, March Busting Through with Baard. Financia Times Energy Word. Number Five, Winter Jacques Lesie. The Dawn of the Hydrogen Age. Wired. October, McGraw-Hi Dictionary of Scientific and Technica Terms Motor Vehice Facts and Figures. American Automobie Manufacturers Association Resources: Word Resources Institute Internationa Fue Ces United Nations Framework Convention on Cimate Change Linkages inkages/ Environmenta Protection Agency, Aternative Fues U.S. Fue Ce Counci Fue Ces CF 2 CF CF 2 O CF 2 CF CF 3 O CF 2 CF 2 SO - 3 H + Chemica structure of membrane materia; Nafion TM by DuPont Definitions: Eectrochemica reaction: A reaction invoving the transfer of eectrons from one chemica substance to another. Fue ce: An eectrochemica device that continuousy converts the chemica energy of externay suppied fue and oxidant directy to eectrica energy. Oxidant: A chemica, such as oxygen, that consumes eectrons in an eectrochemica reaction. Eectroyte: A substance composed of positive and negative ions, Ion: An atom that has acquired an eectrica charge by the oss or gain of eectrons. 1 micron = 10-6 m, 10-4 cm, 10-3 or mm = 1 m Poymer: A substance made of giant moecues formed by the union of simpe moecues (monomers). Therma: Pertaining to heat Structure of Poymer Eectroyte Membranes T he poymer eectroyte membrane is a soid, organic poymer, usuay poy[perfuorosufonic] acid. A typica membrane materia, such as Nafion TM, consists of three regions: (1) the Tefon-ike, fuorocarbon backbone, hundreds of repeating CF 2 CF CF 2 units in ength, (2) the side chains, O CF 2 CF O CF 2 CF 2, which connect the moecuar backbone to the third region, (3) the ion custers consisting of sufonic acid ions, SO 3 - The negative ions, SO - 3, are permanenty attached to the side chain and cannot move. However, when the membrane becomes hydrated by absorbing water, the hydrogen ions become mobie. Ion movement occurs by protons, bonded to water moecues, hopping from SO - 3 site to SO - 3 site within the membrane. Because of this mechanism, the soid hydrated eectroyte is an exceent conductor ctor of hydrogen ions. Future Opportunities Poymer eectroyte membrane fue ces are imited by the temperature erature range over which water is a iquid. The membrane must contain water so that the hydrogen ions can carry the charge within the membrane. mbrane e. Operating poy- mer eectroyte membrane fue ces at temperatures exceeding 100 C is possibe under pressurized conditions, required to keep the water in a iquid state, but shortens the ife of the ce. Currenty, poymer eectroyte membranes cost about $100/square foot. Costs are expected to decrease eas significanty ific nty as the consumer demand for poymer eectro- yte membrane fue ces increases. Remaining Chaenges: es: H +. producing membranes not imited by the temperature range of iquid water, possiby based on another mechanism for protonic conduction reducing membrane cost by deveoping different membrane chemistries