Fuel cell

A device that converts the energy of a chemical reaction directly into electrical energy. It produces electricity from external supplies of fuel (such as hydrogen on the anode side) and oxidant (such as oxygen on the cathode side). These react in the presence of an electrolyte. A fuel cell can operate virtually continuously as long as the necessary flows are maintained. Fuel cells differ from batteries in that they consume reactant, which must be replenished, while batteries store electrical energy chemically in a closed system. One great advantage of fuel cells is that they generate electricity with very little pollution – much of the hydrogen and oxygen used in generating electricity ultimately combine to form water. Fuel cells are being developed as power sources for motor vehicles, as well as stationary power sources.