The possibilities opened up by the fuel cell are extremely exciting for research teams around the world. Vehicles with hydrogen-powered fuel cells offer excellent conditions for environmentally friendly mobility that conserves resources.

Mercedes-Benz was the first manufacturer to recognise the tremendous promise of the fuel cell. As far back as 1994 the first-ever fuel-cell-powered vehicle was unveiled to the public. NECAR1 was based on the platform of the MB 100 van. Since then, DaimlerChrysler developers from a wide array of technical disciplines have been working to achieve the series production maturity of a technology which has twice the efficiency of a conventionally-powered vehicle for the same energy consumption.

The process that takes place in a fuel cell is known as cold combustion: hydrogen reacts with airborne oxygen to form water in a controlled chemical process that generates electrical power. The chemical energy contained in the hydrogen is therefore converted directly into electricity. Fuel cells are very efficient in energy terms, as the energy can be utilised to better effect that in an internal combustion engine.

The fuel cell has a sandwich-like construction. At its centre there is a thin plastic membrane, the so-called proton exchange membrane or PEM (Polymer Electrolyte Membrane). On each side this is coated with a thin catalytic layer, usually of platinum, and a gas-permeable electrode of graphite paper. Gas ducts are machined into the outer layers, which are known as bipolar plates. Hydrogen enters through the duct on one side, oxygen on the other. The platinum catalyst breaks the hydrogen down into one electron and one proton. The positively charged protons are able to pass through the PEM, but not the negatively charged electrons. A potential difference (voltage) is therefore built up between the two graphite paper electrodes. A direct current flows if the two electrodes are connected. The end product of this electrochemical reaction is pure water (H2O), because the protons combine with the oxygen after passing through the PEM.