Fuel Cell

fuel cell, any of a class of devices that convert the chemical energy of a fuel directly into electricity by electrochemical reactions. A fuel cell resembles a battery in many respects, but it can supply electrical energy over a much longer period of time. This is because a fuel cell is continuously supplied with fuel and air (or oxygen) from an external source, whereas a battery contains only a limited amount of fuel material and oxidant that are depleted with use. For this reason fuel cells have been used for decades in space probes, satellites, and manned spacecraft. Around the world thousands of stationary fuel cell systems have been installed in utility power plants, hospitals, schools, hotels, and office buildings for both primary and backup power; many waste-treatment plants use fuel cell technology to generate power from the methane gas produced by decomposing garbage. Numerous municipalities in Japan, Europe, and the United States lease fuel cell vehicles for public transportation and for use by service personnel. Personal fuel cell vehicles were first sold in Germany in 2004.

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The United States government and several state governments, most notably California, have launched programs to encourage the development and use of hydrogen fuel cells in transportation and other applications. While the technology has proven to be workable, efforts to make it commercially competitive have been less successful because of concern with the explosive power of hydrogen, the relatively low energy density of hydrogen, and the high cost of platinum catalysts used to create an electric current by separating electrons from hydrogen atoms.