How a Fuel Cell Works

The electrochemical reactions of a fuel cell begin when hydrogen enters one side of the fuel cell (the anode), where it is separated into an electron and a hydrogen ion.

In the case of one type of fuel cell—a proton-exhange membrane, or PEM—the ions move through a membrane (the cathode) to combine with oxygen on the other side, making water. Meanwhile, since electrons cannot pass through the membrane, they are forced to take an external route through the cathode, creating an electrical circuit that carries them through the electric motor.

As they pass through the motor, the electrons transfer power from the fuel cell to the motor. The motor, in turn, drives the wheels of the car.

The controlled reaction of hydrogen and oxygen that occurs in a fuel cell is much more efficient than the typical burning (or combustion) process of a standard vehicle engine. As a result, fuel cell vehicles are expected to be two to three times more efficient than conventional cars and light trucks.

Furthermore, because the only end products are electricity, water, and some heat, the reaction is pollution-free.

View an animation of how fuel cells work here.

Sources
Daniel Sperling. Future Drive: Electric Vehicles and Sustainable Transportation. Washington, D.C.: Island Press, 1995.
D.H. Swan, B.E. Dickson, and M.P. Arikara. "Proton Exchange Membrane Fuel Cell Characterization for Electric Vehicle Applications." Proceedings of the Advancements in Electric and Hybrid Vehicle Technology Conference. Detroit, February 28-March 3, 1994. SAE Technical Paper Series no. 940296.

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