Blow it out your tailpipe. No, really.

The BBC website has just run a story about a car that runs on compressed air. This is an pretty cool vehicle, if the article is anything to go by:

[The car] "will be driven by compressed air stored in carbon-fibre tanks built into the chassis. The tanks can be filled with air from a compressor in just three minutes - much quicker than a battery car. Alternatively, it can be plugged into the mains for four hours and an on-board compressor will do the job.

"For long journeys the compressed air driving the pistons can be boosted by a fuel burner which heats the air so it expands and increases the pressure on the pistons. The burner will use all kinds of liquid fuel.

"The designers say on long journeys the car will do the equivalent of 120mpg. In town, running on air, it will be cheaper than that."

The company's website, Air Car Factories, is a little vague on the specifics of the cars, but it does give a brief history of compressed-air vehicles, including 19th century pneumatic locamotives and a 1930s car. There's also a form to fill out for more information and to be allowed first crack at purchasing a car. Unfortunately for people in the US who are interested, the only firm licensed to sell the car is limited to India, but the designer, Guy Negre, "hopes to persuade hundreds of investors to set up their own factories, making the car from 80% locally-sourced materials."

The idea is certainly intriguing. Who wouldn't want a car that produces no emissions and can be filled up using the tire pump at a gas station? A few dollars for a couple of minutes to fill up an air tank is a lot cheaper than $40 or $50 for a tank of gas, after all. There are, of course, disadvantages. Wikipedia has a list of them, including some major concerns with efficiency compared to electric motors and the fact that it still takes energy to compress air in the first place. The current air tank technology is also still in need of improvement, and for anyone in a cold climate, you're currently out of luck - since the engine doesn't create heat, you'll need a seperate heat pump if you want to keep warm.

I won't be trading in my current car for one of these just yet, even though I'd love to have something more environmentally-friendly. (I also think the Air Car is pretty unattractive, not to mention the tiny little tires would be difficult to replace if you got a flat.) But the technology, if it can be made more efficient, certainly merits attention.