This one-kilowatt portable Ballard fuel cell generator demonstration unit is a fully automated power system which converts hydrogen fuel and oxygen from air directly into DC electricity. Water is the only byproduct of the reaction. It operates at low pressures, provides reliable, clean, quiet and efficient power and is small enough to be carried to wherever power is needed. (Photo courtesy Ballard Power Systems).

There's been an explosion in the number and type of fuel cells - either in production, in testing or in design. Fuel cell and vehicle manufacturers around the world are confidently predicting virtually zero-polluting, fuel-cell powered models entering the mainstream market perhaps as early as 2005 - and certainly by 2010. (See SILICON CHIP May 2002).

This month, we're looking at the various types of fuel cells, how they work and how they differ from one another. We even look at some which are still very much in the "concept" stage but which show great promise.