As the Chevy Volt nears its release, the buzz around plug-in hybrids has opened the door to cars that run on a multitude of energy sources. Zero Pollution Motors has a car in the works that’s part electric, part pneumatic, and part gasoline powered. Here’s how it works: When parked, the car compresses a carbon-fiber air tank to 4000 psi via an inboard electric powered air compressor, which plugs into a household electrical outlet. The process uses about 2 dollars worth of electricity and takes about 4 hours. The car runs on compressed air when cruising under 35 mph. When exceeding that speed, or when the tanks lose pressure, a small gasoline powered generator powers the air compressor, replenishing the air tank. This system is good for over 100 mpg! The idea is simple, cheap and utilizes no advanced technology. Essentially it’s a plug-in hybrid like the Chevy Volt without the expensive batteries, utilizing an air tank as an alternate means of energy storage. The air-car’s lack of complexity allows the manufacturer to keep the price low—it’s projected have a price tag roughly one third the cost of the Chevy Volt. The gasoline is a means of extending the vehicles range, but is not needed if the car is kept below 35mph and driven short distances before recharging.

When you hear anyone talk of air-cars, understand that air is not a source of fuel. Rather, compressed air is a means of storing kinetic energy, like a rubber band does when twisted. A tank holding compressed air is a method of energy storage, much like a battery. Any car powered by compressed air-driven (pneumatic) engines run on whatever power source was used to compress the air in first place. In most cases, that power source is electricity. An air-car, like an electric car, is really only as green as the electricity used to compress the air tanks initially. If the owner plugs his/her air car into a power grid fed by coal power plants, the air-car indirectly becomes a coal-car.

ZPM’s air car is a brilliant, practical alternative to the plug-in battery powered hybrid. Thankfully, the idea is more than a concept—we could be seeing them stateside in less than 5 years.