A fuel cell converts the chemical energy in hydrogen and oxygen into direct current electrical energy by electrochemical reactions. Fuel cells are devices that convert hydrogen gas directly into low-voltage, direct current electricity. The process is essentially the reverse of the electrolytic method of splitting water into hydrogen and oxygen.
To use a fuel cell in an automobile, the direct current electricity feeds into the electric motors that spin the wheels. Electric vehicles can be either all battery, all fuel cell, or a combination of both to provide electricity to the motors. In both battery and fuel cell vehicles, the power for the auto comes from an electric motor.