Fuel cell

Fuel cell, device that produces electricity through the chemical reaction between 2 substances. The most common type is powered by the reaction between hydrogen and oxygen. Two porous electrodes are immersed into an electrolyte (usually an alkali). Through oxidation, hydrogen is supplied to the anode, and oxygen is allowed to diffuse through the cathode. At the anode, hydrogen gives up electrons to form hydrogen (H⁺) ions, which react with hydroxyl (OH⁻) ions in the solution to give water. The electrons pass around the external circuit to the cathode, where they react with oxygen and water to form more hydroxyl ions. The overall reaction is therefore the combination of hydrogen and oxygen to form water. The electric potential created is up to 1 volt. An ordinary battery is a type of fuel cell, but its electrodes are eaten away during use, whereas true fuel cells have an extremely long life and provide more power relative to their weight than other sources of electricity. Though fuel cells are theoretically more efficient than other generators, they are still very expensive and are only used for special purposes. The Apollo spacecraft use fuel cells to supply electricity. Scientists are working to produce fuel cells that can used low-cost fuels, such as gasoline or diesel fuel, which would make them practicable for domestic use.