All this may sound like a sci-fi fantasy but humankind is closer to achieving such a goal than ever before. We've read about electrolysis in school, how a hydrogen atom is split into electrons and protons to generate electricity. This very reaction can also take place inside a vehicle and generate electric power to run it.

But, as of now, running cars on water through electrolysis is still quite a long way off. At present, solar photovoltaic cells are being explored to generate hydrogen (which in turn would generate electricity) from water. But the amount of energy used to break the water molecules to get the hydrogen atoms (which in turn are reacted to generate electricity) is far more than the energy generated by these atoms to run the car. But once the price and size of solar cells comes down drastically, it would be worth considering water as a source of energy for cars.

What automobile majors across the world are working on in a big way and what appears to be the technology of the next millennium is a fuel cell. As the term implies, a fuel cell car runs on both a fuel and a cell. Unlike a battery, a fuel cell does not run down or require charging. It produces energy in the form of electricity and heat as long as fuel is supplied. And since the fuel cell relies on chemistry and not on combustion (as in the case of today's cars), emissions are much smaller as compared to emissions from even the cleanest of fuels used by internal combustion vehicles.

If a fuel cell vehicle runs on hydrogen, the exhaust pipe will emit only steam. But its quite difficult to store and refill hydrogen. Moreover, it can be generated onboard with the help of a fuel reformer. With a fuel reformer, the fuel cell system can also utilise hydrogen from any hydrocarbon such as methanol, natural gas and even petrol! Methanol and natural gas are typically used to produce hydrogen to run a fuel cell vehicle. These vehicles are equally clean though they do emit a negligible amount of carbon dioxide along with some steam.

A fuel cell consists of two electrodes sandwiched around an electrolyte. Oxygen passes over one electrode and hydrogen over the other, generating electricity, water and heat. Given the difficulties in procuring hydrogen in `pure' form and in storing it, much research is going into developing it onboard. Interestingly, India's Tata Energy Research Institute (TERI) has been doing research on fuel cells for the last 15 years. According to Ajay Mathur, dean, Energy, Environment and Technology, auto majors have to still overcome some hurdles before fuel cells can become commercially viable.

Earlier it was the weight of the fuel cell but now the biggest impediment is its cost.

Though the prices of fuel cells still vary, a fuel cell power plant could come for around $3,000 per kilowatt. Clearly, fuel cells will have to be much cheaper to become commercially viable in vehicles. Conventional car engines cost about $3,000 to manufacture. Even though more research is needed to bing the cost of fuel cells down, DaimlerChrysler has pledged to have a viable, commercial fuel cell vehicle available in 2004. Studies by General Motors and Ford have noted that fuel cell car engines could be built for about the same price as an internal combustion engine.

At this year's Frankfurt Motor Show, Mercedes-Benz had showcased its all-new A-class that runs on a fuel cell. The A-classes used methanol to generate hydrogen onboard. The electric motor in this model is located at front, beneath the engine hood while the methanol tank is accommodated in the rear of the vehicle. A fuel cell vehicle has considerable advantages over even an electric vehicle (EV). Firstly, the acceleration characteristics are as good as that of an internal combustion engine; whereas in the case of an EV, acceleration drops quite considerably. What's more, fuel cell vehicles can be refueled quickly and could go longer between refuelings.

The first fuel cell was built in 1839 by Sir William Grove, a Welsh judge and scientist. But serious interest in the fuel cell arose only in the '60s. Canada, Japan, Germany and the US are aggressively promoting fuel cell development with tax credits, low-interest loans and grants to drive down costs. In August 1997, Toyota showcased its methanol driven fuel-cell version of its RAV4 sport-utility vehicle. DiamlerChrysler has invested Canadian $450 million in Canada's Ballard Power Systems for development of fuel cell vehicles. The auto major has already unveiled four fuel cell vehicles, including the Mercedes A-class mentioned above. DaimlerChrysler also has a fuel cell bus. Ballard has fuel cell buses running in Canada and Chicago. Almost all other automakers researching fuel cell cars are incorporating Ballard fuel cell engines.

Interestingly, some time during the early part of this century, there were equal number of electric and internal combustion engine vehicles. Somewhere in the '20s electric cars started losing out to internal combustion engines. According to Mathur, until 1928, a third of cars in the world ran on electricity until fossil fuels -- petrol and diesel -- were promoted in a big way. ``If that had not happened and instead investment in infrastructure was geared towards electric cars, there would not have been so much hue and cry over vehicular pollution,'' adds Mathur. So once capital and infrastructure get locked in one particular technology, it automatically gets promoted over the others. In the context of India, Mathur feels that the government will have to take the lead in setting its priorities. ``The fuel cell technology, like other clean alternatives, is driven by regulations,'' says Mathur, adding that the government should set a clear target on what environmental quality it wants to achieve and by when. Buthis view is that before cars, it would be worth considering fuel cell buses.

More importantly, policy makers will have to pay heed to this technology, and fast, for fuel cell vehicles are truly the vehicles of the future. In another three to five years, fuel cell vehicles will begin to hit the roads of the developed world. If we want to bring our social costs down and curb pollution, we can't afford to be far behind.