13 Oct 05
This is the stuff of science fiction - a car from which the only emission is water so pure you could drink it. No smoke, no harmful gases and barely any noise.
The power comes from a chemical reaction involving hydrogen, the most common element in the universe, and another element that surrounds us, oxygen. The chemical reaction happens in the suitably technically named "proton exchange membrane" (PEM) where it creates energy, which in turn, powers the car - in this case, a Mercedes-Benz A-Class.
The A-Class is, at first glance, much like any other last-generation A-Class - with the exception of some rather large graphics stretching down the side. Inside, all five seats are in place and everything else is just as the regular car, apart from for some funky metal-faced dials in the instrument panel.
Instead of a conventional petrol engine and fuel tank, there are some complicated mechanical components including two high-pressure hydrogen tanks, a large battery, an air compressor and an electric motor. The most complex of all the components, however, is the fuel cell stack.
The fuel cell stack is a made up of multiple PEMs, which, in simple terms, are structured like a sandwich. Each PEM is a thin plastic film, coated on both sides with a catalyst layer that is then stuck between two pieces of graphite paper. A plastic and paper sandwich may not taste very nice (although probably better than those found in a petrol station), but it provides an ideal location for the relatively straightforward chemical reaction that brings hydrogen and oxygen together to create water. Science lesson over, let's get on with the drive.
