Fuel Cells - How they work

A fuel cell is a device that uses hydrogen (or hydrogen-rich fuel) and oxygen to create electricity. Fuel cells are more energy-efficient than combustion engines andd the hydrogen used to power them can come from a variety of sources. If pure hydrogen is used as a fuel, fuel cells emit only heat and water, eliminating concerns about air pollutants or greenhouse gases. This site from the U.S. Department of Energy contains an animated Flash illustration of how fuel cells work.