Taxis that run on fresh air may solve city pollution

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The Independent Online

A car that runs on fresh air and exudes even fresher air might sound like an environmentalist's fantasy.

A car that runs on fresh air and exudes even fresher air might sound like an environmentalist's fantasy.

But there is such a vehicle - and a French company has a contract to build 40,000 of them for the Mexican government, which wants to use them as taxis in Mexico City, the most polluted city on earth. The car's inventor says that in cities it could soon challenge cars powered by conventional fuels.

Guy Negre, a former designer of engines for Formula 1 cars and lightweight aircraft, has been working on his "zero pollution" design for almost 10 years. He believes it is now ready to go into full production.

The power unit burns nothing. It gets its motive power from 300 litres of air, compressed to 300 times atmospheric pressure. Mr Negre says tests indicate that it could run for 120 miles in an urban environment - where speeds of 30mph would be sufficient - but that it could also manage a top speed of up to 60mph.

Recharging the vehicle would simply require a stop at an "air pumping" station, where the tanks would be refilled. The stop would take less than five minutes.

The car runs by releasing the supercompressed air into a piston chamber, driving the piston down. Heated air from outside is then added to the chamber to warm it up, and the mixture is expelled as the piston rises again. The expelled air is passed through carbon filters, meaning that generally it will emerge cleaner than the air that went in.

Mr Negre insists that the "Taxi Zero Pollution", as the car has been dubbed, handles and drives just as well as a normal one. He has licensed the design to a number of companies to build it in different countries: moves are under way to manufacture them in Mexico, South Africa, New Zealand, Australia, New York, Switzerland and France. There are negotiations over a plant for the UK, but nothing has been decided.

Possible difficulties with the project include providing a big enough network of air filling stations, and starting the vehicle if the air tanks are nearly empty, when they might not have enough energy to keep the car going.

Steve Hounsham of the pressure group Transport 2000 said:"This could make a worthwhile contribution to reducing pollution, but that's only one problem that needs to be addressed. It won't reduce congestion, road traffic accidents or pressure on the countryside."