Fuel Cells convert an electrochemical reaction to electticity. There are applications that are sationary, portable and those used in transportation. All Fuel Cells are composed of an anode, cathode and electrolyte and are typically characterized by the composition of he electrolyte. The most common is the Proton Exchange Membrane (PEM). Others are Phospheric Acid (PAFC), Solid Oxide (SOFC), Molten Carbonate (MCFC) and Direct Methane (DMFC).