A few three-wheelers will soon start plying in the capital using a fuel mix of compressed natural gas (CNG) with hydrogen, seen as a renewable and clean fuel of the future, IndianOil officials said.

They, however, added that large-scale conversion of vehicles to use hydrogen fuel might not be a commercial proposition at present.

"This would be our first commercial experience of using hydrogen in vehicles. So far our work has been restricted to laboratories and small-scale trials," an IndianOil official said.

"The idea is to improve the thermal (combustion) efficiency of CNG and bring down the level of nitrogen-oxide emission through the blend of hydrogen," the official told IANS.

The move to commercialise the use of hydrogen blended with CNG will begin Sep 10 when Petroleum Minister Mani Shankar Aiyar inaugurates the first dispenser at IndianOil's research and development centre here.

IndianOil officials said India is among the few countries collaborating with international agencies and institutions to tap the potential of hydrogen fuel for vehicles as an alternative to petrol and diesel.

Under a UNIDO-funded project by the Indian Institute of Technology (IIT) Delhi, some automobile manufacturers are studying to put pure hydrogen-powered vehicles on the roads in one year, they said.

Several similar experiments are on in the country to test the efficacy of hydrogen fuel cell vehicles, be it two, three or four-wheelers.

Currently the high cost and inconvenience of recharging hydrogen fuel cells are seen as the major deterrents but experts are confident that in a decade they will have the answer.

"We are also planning to join hands with some of the international organisations like the University of Alberta and national laboratories in Norway and Iceland to tap renewable sources to produce hydrogen fuel," an official said.

"In fact, Iceland, which is looking at producing hydrogen fuel from geothermal energy sources, is planning to switch to largely hydrogen-driven vehicles by 2014, and fully switch to them by 2050."

Indian Oil is also planning collaboration with Reva Electric Car Co and Mahindra and Mahindra on hydrogen fuel cell vehicles, which are deemed to be three times more efficient and less polluting than diesel or petrol-driven vehicles.

IndianOil, meanwhile, is banking on the petroleum ministry to set up more CNG-hydrogen fuel dispensers here to help more vehicles switch to the new green fuel in phases and thereby further reduce the atmospheric pollution.

IndianOil has also been experimenting with the use of hydrogen-blended CNG in Ambassador cars and mini-buses.

The higher the content of hydrogen in CNG, the better its energy efficiency. The company is studying a blend of 10-30 percent hydrogen in CNG, though it can go up to 50 percent, the official added.

Over the next one year, IndianOil and the automobile companies will conduct experiments to gauge the results before the commercial launch of more vehicles on the roads using the new green fuel.