What are the long term prospects of hydrogen replacing petrol as the fuel which powers the family car? In Australia, one research team has modified an ordinary car to run on hydrogen. The car performs well in traffic, even under freeway conditions, and produces very few pollutants. Storing the hydrogen gas is a problem, since even under pressure, it takes up a lot of space. Another group is looking at various metallic alloys which, under slight pressure, will combine with hydrogen, thus storing it conveniently for later release. Producing the hydrogen cheaply and efficiently is another problem. One group is looking at a photo-chemical process which uses light to break down water molecules, thus releasing hydrogen. Another is using a method which is rather like a cross between a photo-voltaic cell and a solar water heater. The objective, in both cases, is to produce hydrogen from sunlight and water.
