What are fuel cells?
Fuel cells are devices that use a chemical reaction to produce an electric current at very high efficiencies. They are frequently compared to batteries where the chemicals needed for the reactions are stored within the battery itself. Fuel cells differ in that they are connected to a source of fuel, almost always molecular hydrogen. Hydrogen is combined with oxygen from the air to produce water and electric current; electrons flow between the cathode and anode of the fuel cell through an external circuit and while positive chemical ions flow in the opposite direction within the fuel cell itself. Fuel cells are categorized by the substance used for ionic flow in the fuel cell; phosphoric acid (PAFC) proton exchange membranes (PEMFC), solid oxide (SOFC), molten carbonate (MCFC), etc.
Fuel cells are an electrochemical energy conversion device. Fuel cells are similar to batteries except that the chemicals they require can be replenished. In effect, fuel cells do not have a finite life (like batteries) and will continue to produce energy unless the device breaks down or the chemicals required are no longer available.
