Compressed air car

A French auto company, Moteur Developpement International (MDI), promises that the first air car will soon hit the road. Originally Called the MiniCAT, the lightweight compact vehicle was fueled by air instead of gasoline....the latest version is called OneCAT. Because it doesn't burn gas, the car emits no pollution. Its designers boast that the vehicle will be "the world's cleanest car."

Forbes
Christopher Steiner

Frenchman Guy Negre has test Aircars zipping around the French Riviera near the company's offices outside of Nice. They come in bright colors, can go 70mph and have a range of 125 miles on flat roads. The motor uses a whoosh of air to push its two pistons up and down. Exhaust from the engine consists of harmless atmospheric air, cold enough to serve as air-conditioning on a hot day. But don't try to tow a trailer with one of these things. The engine can't top 75 horsepower.

India's Tata Motors paid MDI $28 million a year ago for the right to build and sell Tata-branded Aircars in India. MDI is shipping a prototype to Tata this summer. Tata will either reproduce that car or, more likely, install the MDI technology in one of its existing cars, such as its recently unveiled Nano. A U.S. company called Zero Pollution Motors has purchased a license from MDI to build an Aircar factory in the States.

The absence of combustion allows MDI to use a lean aluminum engine casing. MDI's engine weighs 80 pounds, a third the weight of the powerhouse in a Toyota (nyse: TM - news - people ) Corolla. The fuel is air compressed to 4,350 pounds per square inch, or 300 times the pressure of the air you breathe. Negre insists that despite the enormous pressure, the tank, in a collision, would split down its sides, harmlessly expelling the air in a giant phoomp.



Now for the drawbacks. The car's limited range would require plenty of fill-ups at compressed-air service stations, except those don't exist. Drivers could fill up at home by plugging in the car's onboard compressor, but that would take four hours. The Aircar weighs only 1,873 pounds (unfueled) and might not meet the safety regulations of the U.S. Negre says he can upgrade the safety features: "If we want to be in the U.S., we will have to pass, and that's what we plan on doing."

Negre, a 67-year-old mechanical engineer, worked on Renault's F1 racing-design crew in the 1980s and 1990s and pioneered the use of magnesium in pistons, dropping their weight in his F1 car from 250 grams to 135 grams, letting his Renault team squeeze 16,000 revolutions per minute out of an engine that previously topped out at 12,000. Negre became fixated on a green car, and in 1991 he founded MDI with $36,000 in venture money.

A compressed-air engine is mechanically like the internal combustion engine, in that the pistons pump up and down. In an internal combustion engine a mixture of air and gasoline is forced into each cylinder and ignited by a spark. In an air car, compressed air is released from a storage tank into each cylinder, but through a heater. This is because of the physical quality of compressed air, which releases energy when expanding and becomes cool.

The compressed air engine has a "green" drawback, because the energy used to compress air is immense. It can only be termed green if that energy comes from a renewable source. A semiretired California engineer, Tom Hanson who has designed his own air car the ZEVair, uses an electrically powered compressor at home. The compressor refills the ZEVair's tank while the vehicle is parked overnight in a garage. As a side benefit, he says, the heat the air compression process releases can be used to heat the home!

The MiniCAT had a top speed of 70mph and a range of 125 miles on one tank of compressed air. The new OneCAT, unveiled at the New York International Auto Show, will come in two versions; a 2-door, 3-seat economy/utility model (for $5,000-$6,000) shown here:



This version will be produced and sold in France and elsewhere. The other model will be developed by Zero Pollution Motors in the US and will be a 6-seat, 4-door family-size version. This will have a top speed of 90mph and 100 miles per gallon (equivalent) engine efficiency, with zero-CO2 emissions.

In India Tata Motors will support further development and refinement of MDI’s technology, its application and licencing for the India market. Under the Tata Motors-MDI pact, the Tatas are slated to deploy MDI’s air-powered engine technology in its own cars. And of course the very small car Nano is the right size and weight for the compressed air engine.