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HISTORY:

Fuel Cells for the Future

By Laura A. Waltemath
Program Coordinator
Fuel Cell Commercialization Group
1800 M Street, NW, Suite 300
Washington, DC 20036
202-296-3471
lwaltema@ttcorp.com


Introduction

Will fuel cells power the future? Many people believe they will. Why? Because they are clean; they are efficient; and they can use many different fuels including renewable ethanol, hydrogen and even landfill gas. According to participants at the International Symposium of Automotive Technology and Automation in Florence, Italy this past June, the fuel cell is the long term replacement for internal combustion engines. The federal government must also believe in fuel cells since the U.S. Department of Energy will be spending $59 million to help industry develop fuel cells to power clean cars and energy efficient buildings.

Fuel cells make electricity by combining a hydrogen rich fuel with oxygen usually from the air in a series of chemical reactions which produce an electric current, water and heat. Because the fuel cell does not bum the fuel, it produces no pollution. This electricity can be used to propel a car or to power our homes and offices.


History of Fuel Cells

The theory of fuel cells has been around for over 150 years. In 1839, English inventor Sir William Grove reasoned from his experiments splitting water into hydrogen and oxygen using an electric current, that it should be possible to react hydrogen with oxygen to produce electricity and water. The term fuel cell was first coined in 1859 when Ludwig Mond and Charles Langer attempted to construct a fuel cell using air and industrial coal gas as the fuel. But, it was not until 1959 that engineer Francis Bacon demonstrated the first fuel cell device, a five-kilowatt fuel cell system, enough to power two homes.

In the 1960?s, the National Aeronautics and Space Administration (NASA) began pursuing practical applications for fuel cells. NASA selected fuel cells as the power generator of choice for its first manned space mission. The fuel cell was selected over


I
batteries, nuclear reactors and solar power for several reasons: compact size;
I
lightweight; high efficiency; ability to operate in zero gravity; emission of only drinkable
water; and ability to operate for the lifetime of the mission, usually seven to fourteen days. NASA continues to use fuel cells to supply electricity and drinking water to today?s Space Shuffle missions.


What is a fuel cell?


Cell Reactions
Figure 1




A fuel cell is similar to a car battery In that they both produce power without combustion or moving parts. But unlike a battery, a fuel cell requires a constant supply of fuel and oxygen to produce power. The fuel cell consists of two electrodes, a negative anode and a positive cathode which are separated from each other by an ion conducting electrolyte. The anode is where the hydrogen atoms from the fuel react to form positive hydrogen ions and negative electrons (e). The hydrogen ions migrate through the electrolyte to the cathode where they combine with oxygen from air to form water (Figure 1). The flow of electrons from the anode to the cathode produces an electric current. The basic fuel cell reactions are:

Anode Reaction:H2 2H + 2e
Cathode Reaction:%02 + 2H* + 2e
Overall Reaction:H2 + 1/2O2 - H20 + electricity

Physically, a fuel cell resembles a sandwich with the electrolyte sandwiched between the two electrodes (Figure 2). The sandwiches are ?stacked? together to make
Figure 2: Sandwich Structure of a
-Fuel Cell

Source: Fuel Cell Handbook, 1989.



a fuel cell. Fuel cells are often referred to as fuel cell stacks. The number of sandwiches determines the voltage of the fuel cell stack


The production of electricity by chemical reaction has a much higher fuel to

electricity conversion efficiency than the production of electricity by burning the fuel. A
fuel cell efficiency can be as high at 80%, which means that 80% of the energy contained in the fuel is extracted and converted to electricity. An internal combustion

engine, such as the engine in a car, has an efficiency of <20% and a natural gas steam turbine power plant has an efficiency of 30-35%. Higher efficiency means that less fuel is needed to produce useful work.



There are several types of fuel cells which are differentiated by their components and their operating characteristics. The major fuel cell types are:

Phosphoric Acid_Fuel Cells Solid PAFC
Solid oxide Euel Lells - SOFO
Molten Carbonate Fuel Cells - MCFC
Proton exchange Membrane Euel Lells PEMFC

The names are derived from the electrolyte component of the fuel cell. The PAFC has
a phosphoric acid electrolyte, the MCFC a molten carbonate electrolyte, and the SOFC


a solid oxide electrolyte. In the PEMFC, the electrodes are submerged in an aqueous,

water-based, medium and a special polymer membrane produces the electric current as the ions pass through it.


The PAFC, MCFC and SOFC are high temperature fuel cells operating at 400F, 1200F, and 1800F respectively (water boils at 2120F). The PEMFC is a low

temperature fuel cell which operates at 176F. The high temperature helps to catalyze the chemical reactions which produce electricity. The PEMFC can operate at a lower
temperature
because it uses special catalysts to drive the reactions.

A fuel cell runs on hydrogen containing fuels. Most of the fuels we are familiar with contain hydrogen including, gasoline; diesel fuel; propane; natural gas; methanol; ethanol; landfill gas; and of course pure hydrogen. A fuel cell may utilize any of these fuels with some fuel cleaning and pre-processing. The cleaning is needed to remove

contaminants, such as heavy metals or sulfur, from the fuel that may reduce the performance of the fuel cell or damage its components. The fuel pre-processing is done by a piece of equipment called a reformer. The reformer extracts hydrogen from


fuels which can then be fed directly into the fuel cell. Natural gas is the most commonly
reformed fuel, but methanol and gasoline can also be reformed.


The PAFC and PEMFC require pure hydrogen fuel, which can be either direct hydrogen or hydrogen from a reformed fuel. The MCFC and SOFC can utilize natural gas, propane, dilute ethanol and methanol directly without reforming. This is because

the high temperature of the MCFC and SOFC allows the fuel to be internally reformed by passing it over a specialized reforming plate located at the top of the fuel cell stack. Some of the newest PEMFCs in development will be able to run on direct methanol which will save the extra reforming step.

How fuel cells will be used?

Fuel cells are a high efficiency and non-polluting alternative to combustion engines. Since fuel cells can be stacked together to give increased levels of power output, fuel cells will have applications ranging from a 1-5 watt unit to power a laptop computer to thousands of watts to power a large industrial complex. Fuel cells applications can be classified as transportation andstationary, to propel a vehicle and to produce electricity and heat.


Transportation Fuel Cells

In transportation applications, a fuel cell will likely be used in transit buses, trucks, cars and even golf carts and possibly locomotives. The PAFC has been demonstrated to operate in transit buses, but the lower temperature PEMFC is considered to be the future of fuel cell vehicles.

Fuel cell vehicles offer a solution to air pollution. A gallon of gasoline burned in an internal combustion engine releases 20 pounds of carbon dioxide, a greenhouse gas. In addition, the internal combustion engine produces nitrogen oxides, an air pollutant responsible for smog formation. Diesel exhaust from buses and trucks contains these same pollutants and particulates, which make the exhaust look black. These particulates cause air pollution and even health problems in people.

The federal government and many states are cracking down on air pollution by requiring a certain number of low emission and zero emission vehicles (LEV and ZEV respectively) to be purchased per year over the next ten to twenty years. Fuel cell vehicles qualify as a zero emission vehicle since their only emission is water. With the

number of vehicles on the road world wide expected to reach one billion by 2010, the potential demand for clean, fuel cell vehicles could be quite large.

Fuel cells also offer the opportunity for using many different fuels including renewable fuels such as ethanol, methanol and hydrogen. As America attempts to curb its import of oil from the Middle East, fuel cells can help to increase the demand for and

supply of renewable and domestically available fuels.





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Stationary Fuel Cells

Depending on its size, a stationary fuel cell may be used to supply power to a radio or an industrial complex. Electric utilities will use large fuel cells for distributed power applications, providing power to many customers, and on-site power applications, where a fuel cell will be sited at a customer to provide dedicated power. Fuel cells will probably never be the only source of electricity, but they will supplement the existing power plants and complement other renewable energy sources. Small fuel cells may be purchased by an individual some day to power a single family home and even smaller fuel cells to power portable computers and electric tools.

Over the next five years, the candidate fuel cells for stationary applications are the PAFC, MCFC, and SOFC and after that, the PEMFC. The high temperature fuel cells, PAFC, SOFC and MCFC, also produce hot water or steam which can provide heating and cooling when sited next to a building or other facility. This application is known as cogeneration and the efficiency of a fuel cell in a cogeneration application can be as high as 80% since both the electrical and thermal energy is being used.

The production of electricity is one of the greatest sources of air pollution. The coal power plants in the Ohio Valley are responsible for acid rain in the Northeast United States. Fuel cell power plants which produce no pollution are a clean alternative to dirty power plants. Fuel cells can also take advantage of abundant, low cost fuels, such as ethanol or landfill gas.

In distributed generation applications, a fuel cell can be sited inside city limits, a feat that cannot be met by any other generation technology. This is because the fuel
cell
is clean, it is quiet (at 30 feet it is only as noisy as a room air conditioner), and is small. A 3.0-megawatt (MW) MCFC, capable of providing power for 2000 homes, is
about
the size of a tennis court. A 200-kilowatt (kW) PAFC, which weighs 40,000 pounds, can be sited in the parking lot of a hospital or school, and can be transported from site to site on a flat-bed truck.


Although fuel cells offer many benefits over conventional technologies, there are barriers to the use of fuel cells. Some of these barriers may take several years to overcome and delay the widespread use of fuel cells.


What are the barriers to fuel cells?

Since fuel cells are a relatively new technology, there are a lot of questions and
concerns
about their reliability, how well they will perform, and durability, how long they will last. And because fuel cells are new, the production capacity for making fuel cells
is low and as a result their price is very high.


Barriers to Fuel Cell Vehicles

In order for a fuel cell vehicle to be able to compete with a gasoline internal combustion engine vehicle, it must be reliable, durable, economic, practical, safe and easy to use and to maintain. Like a car battery, a fuel cell will degrade over time and need to be replaced. How long a fuel cell will last before it needs to be replaced it yet unknown. And unlike a car battery that can be purchased for usually less than $100 a replacement fuel cell may cost over $1000 (if we assume a fuel cell replacement cost is $5OlkW and a vehicle is equipped with a 30 kW fuel cell, which is equivalent to a 36 horsepower engine). An internal combustion engine has an operating lifetime of about 5,000 hours (if you averaged 40 miles per hour over that 5,000 hours, the engine would have a lifetime of 200,000 miles) which should be the target for a fuel cell vehicle.

Based on the fuel cell replacement cost it is obvious that fuel cells vehicles are expensive at this time. Early economics indicate that a fuel cell vehicle may cost between $4000 and $15,000 more than a comparable, conventional vehicle. The early prototype fuel cell vehicles cost more than $100,000. The fuel cell is not the only expensive component, but the fuel reformer, if needed, is an additional cost over a conventional vehicle as is any special fuel storage system which will be required if hydrogen is to be stored on-board the vehicle.

Performance is also an issue for fuel cell vehicles. Start time and response time will likely be longer for a fuel cell vehicle. This is because some fuel cells will need to heat to a certain temperature before enough power is produced to move the vehicle.

Fuel cells may not be able to respond as quickly for acceleration and changes in
speed.

It may also take time for vehicle operators to become comfortable with a new technology. Mechanics will need to be trained to work on fuel cell vehicles and it is unlikely that the average car owner will work on their own fuel cell vehicle.

In terms of competition, even though fuel cell vehicles are non-polluting, car manufacturers are responding to stricter environmental regulations with higher

efficiency and lower emissions gasoline fueled vehicles. The alternatively fueled internal combustion engine vehicles, such as those running on compressed natural gas, ethanol or liquefied petroleum gas, and the electric vehicles will be also be tough competition for fuel cells as low or no emission vehicles.

On-going research and development by fuel cell manufacturers and automakers is addressing these barriers. The technology is expected to improve in reliability and durability and decrease in cost over time.





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Fuel cells for stationary power applications have some of the same barriers as fuel cell vehicles. Fuel cell power plants range in price from $3,000/kW for a PAFC to

$1 ,500lkW for a MCFC. Other fuel cell power plants will fall somewhere in that range. By comparison, a natural gas steam turbine is priced between $200-400/kW. The high price of the power plant will be translated into higher electricity costs for customers.

Fuel cell power plants will need to have lifetime, reliability and durability comparable with the other generation technologies.


When will we be able to buy a fuel cell car?

In 1994, Daimler-Benz, parent company of Mercedes Benz, unveiled their first fuel cell vehicle, a minivan named NECAR, new electric vehicle. The NECAR has a 42-kW (equivalent to 50 horsepower) PEMFC built by Ballard Power Systems (Vancouver, British Columbia, Canada) which runs on hydrogen carried on-board the vehicle. In


May of 1997, Daimler-Benz introduced the NEBUS (new electric bus) which also
utilizes the Ballard fuel cell.

To solidify its lead in the race for a fuel cell vehicle, Daimler-Benz recently invested over $140 million in Ballard Power Systems to jointly develop and
commercialize
fuel cell vehicles within ten years. Daimler-Benz will introduce a prototype A-class subcompact car with a direct methanol fuel cell at the October Tokyo Motor Show. Within two years, Daimler-Benz expects to introduce the world?s first all-wheel drive fuel cell car.

Ford Motor Company announced in April 1997 that it has plans to build a prototype fuel cell vehicle in a collaborative research project with the U.S. Department

of Energy. The objectives of the project is to achieve very high fuel efficiency and very low emission levels while maintaining the passenger comfort, performance, safety and affordability. The fuel cell will utilize a direct hydrogen fuel stored on-board the vehicle. Fuel cell suppliers for the project include Ballard Power Systems, and Mechanical Technologies, lnc. and International Fuel Cells which are both American fuel cell


manufacturers.
Other auto manufacturers are also investigating fuel cell vehicles including,

Chrysler, General Motors, Toyota. Chrysler is developing a fuel cell vehicle which will
run on reformed gasoline, thereby eliminating the fuel infrastructure problem.

Even with prototype fuel cell vehicles on the road today, fuel cell vehicles aren?t expected to be available for as long as 15 years. Part of the reason is the cost of the vehicle. Another reason is the fuel. The current fuel infrastructure is built for gasoline.


In order for fuels such as methanol, ethanol or hydrogen to be available for fuel cell vehicles, new infrastructure must be developed, which will take time.

Where are the fuel cell power plants?

Stationary fuel cells are farther along in terms of commercial availability than their transportation counter parts. Over 100 PAFC stationary power plants are being used today around the world to provide electricity and hot water to hospitals and other large facilities. One of the PAFC power plants recently recorded 9,500 hours of continuous operation and 30,000 cumulative operation time, the longest of any fuel cell to date. Two molten carbonate fuel cell demonstration projects were completed in 1997. A 250-kW MCFC power plant was demonstrated for five months at the Miramar Naval Air Station near San Diego, California. The plant produced both electrical power and steam for the station. A 2.0-MW MCFC power plant was demonstrated for 10 months at a distribution substation site owned and operated by the City of Santa Clara, California Municipal Electric Utility.

In an alternative application of a stationary fuel cell, a 200-kW PAFC has been sited at a landfill in Groton, Connecticut. The fuel cell utilizes the gases produced by
the landfill to generate electricity. The landfill gas is cleaned up to remove potentially

damaging compounds and reformed to produce hydrogen. Whenboth the electricity
and heat are used, the fuel cell can recover more than 80% of energy contained in the landfill gas. An Environmental Protection Agency sponsored studied showed that as
many as 1,700 landfills in the US are ideally suited for alandfill gas fuel cell. The MCFC and SOFC are also candidate fuel cells for landfill applications.

PAFC are commercially available today, and the MCFC and SOFC are expected to be available by 200-2002, and the PEMFC beyond 2002.




References

A.J. Appieby, F.R. Foulkes, Fuel Cell Handbook, Van Nostrand Reinhold, New York,
NY, 1989.

Hirschenhofer, J.H., Stauffer, D.B., Engleman, R.R. Fuel Cells, A Handbook (Revision
3).
Prepared by Gilbert/Commonwealth, Inc. for the U.S. Department of Energy under contract DE-ACOI ~88FE61 684,1994.

Cannon,
James S., Harnessing Hydrogen. The Key to Sustainable Transportation, Inform, lnc, New York, NY, 1995.

What is a Fuel Cell?, factsheet of the Fuel Cell Commercialization Group, 1996.

Siuru, William D., ?Groton?s Tidy Machine,? Public Power Magazine, March-April 1997, pp 8-9.
?Pena Promotes Fuel Cell R&D Initiative?, The Energy Daily, June 24,1997.

?Ballard Power Systems Reports First Quarter 1997 Results? Ballard Power System, press release, (Vancouver, British Columbia, May 28, 1997).

?Ford and DOE Team-up To Build Fuel Cell Vehicle? Ford Motor Company, press release, (Dearborn, Michigan, April 21, 1997).

?Daimler Says Fuel Cell Car Ahead of Schedule? Daimler-Benz AG, press release, (Stuttgart, Germany, May 28, 1997).

?IFC Fuel Cell Sets World Record; Runs 9,500 Hours Nonstop? International Fuel Cells, press release, (South Windsor, Connecticut, May 22, 1997).

?No Clear Winner Seen Emerging in ?Green? Car Race?, press release, (London, England, June 23, 1997).

?Fuel Cell Power Plant Complete Successful Test? Fuel Cell Commercialization Group, press release, (Washington, DC, June 20, 1997).

?M-C Power Completes Initial Test of Cogeneration Fuel Cell Power Plant at NAS Miramar?, M-C Power Corporation, press release, (Burr Ridge, Illinois, June 16, 1997).
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