May 26, 2009

Air Powered Car Idea Zooms Ahead

Forget electric, one motor company is focusing on air to power vehicles.

By early 2011, Zero Pollution Motors will try to bring a car to the United States that's powered by both compressed air and a small conventional engine.

ZPM Chief Executive Shiva Vencat said the vehicle could cost between $18,000 and $20,000.

The idea is gaining momentum in other countries. The French startup, Motor Development International, which licensed the technology to ZPM, unveiled a new air-powered car at the Geneva Auto Show in March.

Engineering experts warn that although the new technology sounds great, it is clouded by the fact that compressing air is notoriously energy intensive.

"Air compressors are one of the least efficient machines to convert electricity to work," said Harold Kung, professor of chemical and biological engineering at Northwestern University. "Why not use the electricity directly, as in electric cars? From an energy utilization point of view, the compressed (air) car does not make sense."

ZPM says the "air cars" plug into a wall outlet, and allow an on-board compressor to pressurize the car's air tank which takes about four hours.
The car relies entirely on the air tank and emits only cold air at speeds less than 35 miles per hour.

However, at faster speeds, a conventionally fueled engine runs a heater that warms the air and speeds its release. The engine also refills the air tank, extending the range and speed.

French race car engineer Guy Negre, head of Motor Development International developed the technology, and has licensed the technology to Indian car giant Tata Motors and others.

ZPM's Vencat said the technology is similar to the internal-combustion engines in conventional cars. The obvious difference is the fuel source.

"Every single car you see out there, except an electric car, is a compressed-air car," he said. "It takes air in the chamber and it pushes the piston, and the only way you push the piston is through pressure."

James Van de Ven, a mechanical engineering assistant professor at Worcester Polytechnic Institute, said air compressors allow you to recover only 25 to 30 percent of the energy used to compress the air.

He warns the rest of the energy is lost through heat, air leakage, and other forms of waste.

He said air compressors are far from the efficiencies of other alternative-fuel powertrains, like those found in hybrid-electric cars.

George Haley, business professor at the University of New Haven, said another obstacle to air powered cars is U.S. safety regulations due to the car's tiny size and light weight.

Vencat said he receives criticism, "from the whole wide world" and doesn't care.

"The big difference is that the (Chevrolet) Volt needs the battery," Vencat said.

The Volt's massive lithium-ion battery is a big part of the reason it is expected to cost about $40,000 when it goes on sale late next year.

He said it may take a bit to mass produce the vehicle, but he's already taking orders.

"You know, we've got a lot of people who wanted the car yesterday," he said.


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