nearly hundred and fifty years ago, William Grove, an amateur British scientist, discovered that he could produce electricity as a byproduct of the process which mixes hydrogen and oxygen to make water. Now, some British engineers say that his discovery will be the key to smog-free driving in the next century. Ballard Power Systems Incorporated, based in Vancouver, Canada, has been working on the commercial applications of fuel-cell technology for more than a decade. Ballard, which was founded in 1979 as a company conducting research on batteries, is currently a leader in harnessing fuel-cell technology to power automobiles.

Recently, Ballard and the German automaker Daimler Benz ag (from whom Ballard receives support), have together unveiled a new type of electric car powered by fuel-cells.The demonstration vehicle - a compact version of a fuel-cell powered minivan - is due to be released in showrooms all over Europe by September this year. Although the price is yet to be disclosed, analysts expect the cost of the first generation fuel-cell powered cars to be high enough to be beyond the reach of most motorists. The one unattractive feature is the vehicle's box-like shape, derived from a design meant to carry tanks of hydrogen in special roof compartments.

Its appeal lies primarily in the fact that it is absolutely noise and emission-free. It can carry six people at a speed of upto 105 km per hour. It requires refueling after approximately 242 km. According to officials at Ballard, its performance is superior to that of other electric cars.

Fuel-cells function as small generators to produce electricity on board a vehicle. By comparison, more conventional electric cars are powered by batteries that store electricity generated externally. As the hunt for vehicles that pollute less intensifies, other automakers are also taking fuel-cell technology seriously. The us-based General Motors Corporation is developing a car powered by Ballard's fuel-cells. The Ford Motor Company is investing more than us $150 million in a programme to develop 'hybrid electric vehicles' - vehicles which would combine different technologies including fuel-cells and storage batteries.

In its basic form, a fuel-cell comprises two chambers containing two oppositely-charged electrodes, separated by a semi-permeable membrane. Hydrogen gas is introduced into the chamber in which platinum catalysts help split hydrogen molecules into atoms. These are almost immediately ionised because of the electric potential between the electrodes. This means that the single electron in the hydrogen atom is separated from its positively-charged nucleus or proton. The proton then passes through the membrane to combine with oxygen atoms in the opposite chamber to form water. Meanwhile, the electrons in the first chamber are drawn as usable electric current.

In an environment that is not very controlled, a spark could ignite a mixture of hydrogen and oxygen resulting in explosive molecular reactions capable of launching rockets. The utility of fuel-cells lies in their ability to harness efficiently the tremendous energy released by the chemical reaction and converting it into electricity.

In the '60s, fuel-cell technology was used by American astronauts on the Gemini space mission. It provided them with both electricity and water. But fuel-cells were dropped from the Apollo missions which were undertaken later, because they were highly corrosive and messy to handle. Eventually, National Aeronautics and Space Administration auctioned the rights to develop the technology to Canada's department of national defence.

Researchers at Ballard have spent most of the past 12 years making fuel-cells which are smaller and more powerful. The biggest challenge before their becoming commercially-viable lies in reducing their manufacturing costs. Ballard is now experimenting with using less platinum - a rare and expensive metal that coats the electrodes of the fuel-cells. "Now the question is how little we can spray platinum and still achieve the same performance," says Keith Prater, vice president of Ballard.

Greater economy can also be achieved if Ballard could find cheaper materials for the fuel-cells' membrane. Prater says the company recently developed a membrane made of a different polymer. But this polymer, which initially performs well, is all the same prone to eventual chemical breakdown. Still, he notes, "It works fine for 4,000 hours of automobile operation. The main problem is that we still do not know exactly why our new membrane works better, making it difficult to improve upon the discovery."

Prater envisages the mass production of cars powered by fuel-cells as well as other fuel-cell applications. For instance, by the year 2003, there could be mini electrical power plants which could be fitted in the basements of people's homes. "The technical challenge before us is to develop these low-cost and high-value manufacturing processes, apart from convincing automakers that now is the right time to invest," says Prater.