Fuel Cells May Not Be So Clean
April 12, 2000
Fuel cells are perceived as a clean, green replacement for conventional internal combustion engines. However, the fuel-cell powered vehicles most likely to make it market are the ones that do the least to cut emissions of so-called greenhouse gases implicated in global warming, according to Canada's Pembina Institute for Appropriate Development.
Fuel cells generate electricity by reacting hydrogen and oxygen, yielding water as their exhaust. While a fuel cell itself produces no harmful emissions, generating the hydrogen it uses as fuel could cause almost as much damage to the earth's climate as burning gasoline in today's cars, says the report.
Researchers analyzed the life cycle of producing and using fuel cells, including emissions of carbon dioxide, methane and nitrous oxides related to extracting raw materials to produce the hydrogen, process and refine it, transport and distribute it, as well as operate fuel cell vehicles with it.
They found that the net amount of greenhouse gas emissions depends on the method used to produce the hydrogen. For instance, for the main greenhouse gas, carbon dioxide:
- If the hydrogen is produced by electrolysis -- passing a heavy electrical current through water -- the net reduction in emissions over conventional engines would be little more than 4 percent.
- Stripping hydrogen from gasoline through chemical reaction would lead to only modest reductions in carbon dioxide emissions of about 22 percent.
- The cleanest option available today is to strip hydrogen from natural gas, which would cut emissions by about 72 percent.
However, the fuel-cell powered vehicles most likely to make it market are the ones that do the least to cut greenhouse-gas emissions. Gasoline is the most likely source for hydrogen because it would require the least change in the existing fuel distribution system.
Source: "Climate-Friendly Hydrogen Fuel: A Comparison of the Life-cycle Greenhouse Gas Emissions for Selected Fuel Cell Vehicle Hydrogen Production Systems," Pembina Institute and David Suzuki Foundation, March 2000, Pembina Institute for Appropriate Development, Box 7558, Drayton Valley, Alberta Canada T7A 1S7, (780) 542-6272.
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