Electrolysis of water consumes electricity to produce hydrogen and oxygen. The fuel cell, which was discovered in 1839, uses the opposite principle. It would be more precise to use the plural—fuel cells—because there are several different kinds. The kind most used to equip vehicles is based on the proton exchange membrane technology (PEM).

This fuel cell is comprised of two electrodes separated by an electrolyte, the role of which is to block electrons and allow positive ions (cations) to pass through it. On one of the electrodes, hydrogen is separated into protons and electrons, and in the second one, the protons and electrons react with the oxygen contained in the air. The circulation of the electrons creates an electrical current.

This clean reaction takes place in each of the basic cells that are combined to constitute an energy module of the desired power. A fuel cell is an assembly of several cells in a series or in parallel in a stack, which makes it possible to obtain different voltages and current output.

The electricity produced by the fuel cell running on hydrogen meets a variety of needs: power supply in an isolated region, emergency power supply for strategic sites, and the direct production of electricity in a vehicle, allowing it run cleanly and quietly.