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Air-powered Autos

Zero-emission driving may be more than hot air.
September 19, 2002

Guy Negre, an engineer from the little town of Carros, France, discovered a breath of fresh air, both literally and figuratively. During his career designing formula one engines he became familiar with isotherm dynamics, a process that creates power by expanding air at an almost constant temperature. Negre theorized that by heating and expanding super-cooled compressed air he could power a nonpolluting car. Six years and four prototypes later, it would appear he’s done it.

Negre’s company, Motor Development International (MDI), created what it calls the Compressed Air Technology (CAT) car by combining a lightweight automobile body with a new type of small rear-mounted engine. The 1,500-pound frame is made from aluminum and fiberglass with four very light, steel-reinforced thermoplastic air tanks attached to the undercarriage of the car. The engine measures only one-foot square and weighs just 70 pounds, but because it propels a relatively light vehicle, it can run at 55 mph. 

Negre, who was interviewed through an interpreter, explains that, in the tanks, the air is both cooled to minus 100 degrees Centigrade and compressed to 4,500 pounds per square inch. Then it’s injected into a small chamber between the tanks and pistons, where it’s heated up by ambient outside air that forces it to expand into a larger chamber situated between the small chamber and the pistons. That heat exchange between the two chambers, he continues, creates the propulsion that drives the up-and-down strokes of the engine’s four pistons. Finally, the air is passed through carbon filters like those in scuba diving tanks and expelled as pollutant-free exhaust. The dynamic is not unlike that of a spring that takes in energy when it’s compressed and gives it back when it expands.

The big plusses of the air-powered car, according to Negre, are super-efficient energy consumption as well as minimum pollution and maximum affordability. Though the car seats five, it will go from zero to 50 mph in seven seconds-certainly adequate acceleration for an urban vehicle like a taxi. What’s more, with fully loaded air tanks, it will take passengers about 120 miles at an average of 30 mph-again, about the right capacity for urban drivers who don’t want to fill up too often. 

Charging the car with air is fairly easy-it takes four hours using a household electric outlet or three minutes using special compressed air stations that MDI sells for about $100,000. Obviously, the vehicle also drastically reduces pollution-it takes in polluted outside air, filters it, and expels cleaner air as exhaust. All that for a price tag of between $10,000 and $14,000. 

According to Michael Baltierra, a reporter for ABC News, “we tested the car and it ran quite well. The only major problem that we noticed,” he continues, “was that it was quite noisy-[but Negre] said this was something that would be fixed in later models.” According to Shiva Vencat, vice president of the U.S. wholly owned subsidiary of MDI, Baltierra tested the car in June, 2000. At the time, Vencat explains, the car “was not a finished productour engine was attached to the car but did not have the body shell all the way around it to muffle the noise.” Since then, he says they have encased the engine to make it run more quietly.   

So far MDI has produced prototypes of four different models: the taxi, van, family car, and pickup. A fifth model, a compact version of the car called a mini, is being introduced at the Paris Auto Show this fall. Commercial versions of all models will start production in the first half of 2003.

According to Vencat, the company is private and has more than 300 investors. Nevertheless, he adds, capitalization is largely bootstrapped-Negre himself funded about 75% of the company.

Rather than building a large centralized facility to manufacture hundreds of thousands of cars, MDI franchises will build hundreds of smaller plants that will produce thousands of cars and sell them locally.

The plants are modeled on the first plant now under construction in Carros. For their $10 million investment, licensees get a turnkey plant package. “Everything is included” for a franchise, says Vencat. “It’s a little bit like running a McDonalds. You get all your equipment, all your raw materials, you do your thing, and you sell it.” Negre estimates that each plant can produce from 2,500 to 5,000 cars a year.

The concept has proven quite appealing, especially to countries outside the United States. Thus far, Negre says MDI has issued 32 licenses in 12 countries such as South Africa, Mexico, Spain and Australia. He says 28 more licenses are pending; the licensees have been signed and now have 30 days to come through with payment.

Enrique Koppel, who owns a chain of apparel stores in Mexico, has purchased licenses to produce the car for the entire country. The prospect of selling an air-powered car appeals to him, he says, because “it’s supposed to be very low cost, easy to build, and you can charge it in three minutes.” Koppel says he will “open as many factories as we can if the demand is there” and plans to sell the cars for use as taxis and delivery vehicles.

As to distribution in the United States, Baltierra observes that, “the car seems ideal for urban environments-it’s small and does not go very fast.” But, he adds, “it’s unclear if this would appeal to major markets like the U.S.” Vencat, however, is negotiating with interested parties in both Florida and California.

Though some CAT models are meant for individual consumers, don’t expect to see many in your neighbors’ driveways right away. Vencat says most of the early adopters will be businesses like taxi services that want to replace their combustion-based fleets of cars with low-cost, non-polluting vehicles. With the compressed air station, explains Vencat, “fleet owners can quickly fill the cars up. It can service 8 to 10 cars an hour.”

While it’s a safe bet that the CAT line of cars will not be setting any land speed records, they may promise to be a viable and environmentally correct means of mass transportation, especially in urban areas with high pollution. What remains to be seen is whether they can compete with gas-powered vehicles for the consumer market. For this to happen, Baltierra believes, “the automotive industry has to get behind this car, and it seems that right now it is not.” If traditional carmakers do decide to distribute the car, however, it would really help what is now a maverick automotive movement in its infancy quickly get up to speed. 

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