Fuel cells
A fuel cell is essentially a battery using an external fuel supply, connected to an electric motor. Electrodes within the cell house a catalytic reaction where the fuel and oxidant are electrochemically transformed, producing DC power, water and heat. Hydrogen is the cleanest and most efficient fuel for a fuel cell-powered vehicle in the long term but several other fuels are being investigated as shorter-term hydrogen carriers.
Methanol powered fuel cells should reduce greenhouse gas (GHG) emissions substantially, perhaps as much as 50% when fully optimized. If the methanol fuel is produced from cellulose, the reductions can be even greater.
Studies have demonstrated that fuel cells have the potential to more than double vehicle fuel efficiency levels achieved by internal combustion engines. At the same time, they have the potential to virtually eliminate many conventional pollutants. Carbon monoxide and Volatile Oraginc Compounds (VOCs), for example, are almost entirely eliminated in fuel cells. Further, since fuel cells operate at much lower temperatures than internal combustion engines, NOx emissions are extremely low.
Costs remain extremely high-far from competitive even with natural gas or methanol-fueled vehicles. Current research is focused on improving fuel cell size, lowering costs and developing efficient, compact and responsive on-board fuel reformers that would provide the needed hydrogen.
Automobiles powered by fuel cells have been demonstrated and a small number are in operation worldwide, but widespread commercialization is not expected for several years. DaimlerChrysler has announced its intention to begin producing fuel cell vehicles by about 2004; Honda may do so in the same approximate time frame. Over the longer term, fuel cells could offer the auto industry near-zero emission vehicles with long ranges, good performance and rapid refueling.
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| Fuel cell bus |
The Chicago Transit Authority (CTA) successfully operated three zero-emission fuel cell buses in a demonstration project to test the viability of the technology in heavy urban use.
Currently high costs and the lack of a fueling infrastructure are the largest obstacles mobile fuel cell technologies must overcome. Engineering challenges include reducing the size and weight of the unit to levels appropriate for vehicles. The use of gasoline as a fuel would greatly increase the prospects for fuel cells, but current reformers require very low, virtually zero sulfur gasoline.
Hy-wire
General Motors unveiled its Hy-wire concept car during the 2002 Paris Motor Show. The vehicle combines hydrogen fuel cell power with drive-by-wire technology, using high-tech electronics to control the car instead of mechanical cables. GM hopes to have these cars on the streets by the next decade.
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