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Fuel Cells

A hydrogen fuel cell vehicle is an electric vehicle that gets its energy from hydrogen gas.

How a Fuel Cell Works. A catalyst is used in a fuel cell to trigger a reaction that strips the electrons from hydrogen. After separation, the electrons are conducted on an anode (negative electrode). The electrons are attracted to the cathode (positive electrode), but they cannot flow through the proton exchange membrane (also known as polymer electrolyte membrane or PEM) with the hydrogen ions (protons). The PEM only accepts protons. The electrons are routed through an external circuit, which includes an electric motor. Electricity is the flow of electrons, so the motor is powered as the electrons move toward the cathode (positive electrode). Upon returning to the fuel cell they reconnect with the hydrogen ions and join with oxygen to form water (H2O) and heat. Water and heat are the only exhaust by-products of a fuel cell. Fuel cells are used in stacks to increase voltage.

Types of Fuel Cells. Various types of fuel cell membranes perform the function of extracting the electrons somewhat differently. However, the end result is the movement of electrons which is electricity. Currently several fuel cell types are under development for different applications from vehicles to power plants: PEM, direct methanol, alkaline, phosphoric acid, molten carbonate, solid oxide, and regenerative. PEM technology appears to be the most promising for automobiles.