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The performance of a single-chamber solid oxide fuel cell was studied using a ceria-based solid electrolyte at temperatures below 773 kelvin. Electromotive forces of ~900 millivolts were generated from the cell in a flowing mixture of ethane or propane and air, where the solid electrolyte functioned as a purely ionic conductor. The electrode-reaction resistance was negligibly small in the total internal resistances of the cell. The resulting peak power density reached 403 and 101 milliwatts per square centimeter at 773 and 623 kelvin, respectively.
Fuel cells are widely viewed as a promising source of low-emission power generation for vehicles. There is great controversy over which fuel should be used. Polymer electrolyte fuel cells (PEFCs) exhibit high power densities at low temperatures (~353 K), but they require hydrogen as the fuel, which is impractical in terms of storage and handling. An external reformer can be used to convert alcohols and hydrocarbons into hydrogen, but their portability is inferior. There have been recent successes with solid oxide fuel cells (SOFCs), which perform well between 823 and 973 K using methane (1) and n-butane (2) directly as the fuels. A further reduction in the operating temperature of SOFCs and an enhancement in their thermal and mechanical shock resistance would make...