The American Hydrogen Association is a national organization, dedicated to educating the public about the potential of hydrogen as a fuel. Hydrogen can be made from sustainable energy sources. AHA recognizes that rapid depletion of oil and other fossil fuels is a serious problem for our society. Research and development of sustainable energy systems is essential to our survival in the near term, because demand for fossil fuels is already outstripping supplies. America imports over half of the crude oil it wastefully consumes.
The transition to sustainable energy sources is yet possible because of three factors:
In the longer term, only sustainable energy will be available to us. Biomass conversion to gas, solar, wind and other sustainable sources have tremendous potential to meet our needs, but must be developed now. Massive energy transitions take decades and we have no time to lose.
I'm glad you asked. A fuel cell is probably one of the greatest inventions of the past two centuries, that's what!
Simply put, a fuel cell is like a battery. Except, a fuel cell has its reactants continuously added from outside the fuel cell. By feeding a fuel through one porous electrode, electrons are stripped from the fuel and make their way through the external circuit. The remaining positive ions travel through the electrolyte to the other porous electrode, where they combine with oxygen ions, formed when the free electron combines with oxygen fed in at that electrode. The electric "pressure" of the free electrons, flowing through an external circuit is the voltage.
The fuel cell also produces water (in the case of hydrogen fuel) or water and carbon dioxide (in the case of hydrocarbon fuel such as methane or methanol).
In any case, the products are generally harmless and non-polluting, and efficiencies of 70 to 80 percent are possible in fuel cell systems. Most air pollution is caused by inefficient internal combustion engines in mobile vehicles, such as cars and trucks. If all these engines could be replaced with fuel cells and electric motors tomorrow, the efficiency of fuel use would at least double! By being about two times as efficient, the fuel cells would require only of the fuel, although they would do the same amount of useful work. All of this energy is eventually released to the atmosphere as heat, so thermal pollution generated would be one half of the internal combustion engine's.
For the benefit of the non-experts among us, fuel cells are named for their electrolytes. The electrolytes are the media through which the ions pass from one electrode to the other.
There are many possible electrolytes. Six of the most promising have received the major research efforts to date. These are:
In the alkaline fuel cell, the electrolyte is potassium hydroxide (KOH) in anaqueous (water) solution. The AFC is being used for the Space Shuttle Orbiter and was used in the earlier manned Apollo space flights. They are expensive and require pure oxygen.
PAFC's are now in use for electric power generation. IFC is manufacturing 57 to 200 kW units for power generation. A 375 kW unit has been built by Westinghouse. Other PAFC leaders include Energy Partners, Ford, Dow Chemical, as well as Japanese firms.
PAFC's are also being developed for transportation. The fuel cells are used together with batteries (i.e. hybrid) by H Power Corporation. PAFC buses, using methanol with on-board reformers were completed in 1993.
Energy Research Corporation and M-C Power Corporation are making important strides toward commercialization of molten carbonate fuel cells. Stacks have been tested, and small demonstration plans are expected in a couple of years.
Solid oxide fuel cells, which operate at high temperature, hold a promise of high fuel efficiency, high power density and low cost. SOFC's can be of tubular or planar construction. For tubular SOFC's, Westinghouse has completed hours of operation, and is in the process of scaling up the size of the units. Ceramatics is a leader in planar SOFC's, which are expected to have low cost, high performance and high reliability.
Polymer electrolyte fuel cells have great promise for transportation, because of their high power density (kW/pound) and high energy density (kW-hours/pound).
They utilize hydrogen that is obtained from methanol, ethanol, or natural gas.
By Kim Kinoshita
The Office of Transportation Technologies, Electric/Hybrid Propulsion Division of the U.S. Department of Energy (DOE) is supporting programs to develop fuel for transportation applications. The DOE Program Manager is Dr. Pandit Patil. A document entitled "Multi-Year National Program Plan for Fuel Cells in Transportation" is being published which describes the details of the plans to accelerate Reasearch and Development on fuel cells for successful implementation by the transportation sector. This Program Plan outlines a comprehensive proposal for cost-shared effort among government, industry, and universities.
Currently, there are three programs underway (the prime contractor is noted in parenthesis): (I) Fuel Cell Bus Program (H-Power Corporation), (ii) Proton-Exchange Membrane Fuel Cell Program (Allison Gas Turbine Division of General Motors Corporation), and (iii) Reformer Research for Fuel Flexibility in Fuel Cells (Arthur D. Little, Inc.).
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