We've had already a few posts about MDI's Air Car, a vehicle which is powered by stored compressed air. Although we couldn't make it to Nice to interview its creator, Guy Nègre, we could visit MDI's Sales Manager, based in Barcelona. And it was a very enjoyable chat (although we'll need to go to Nice to test the car).

AutoblogGreen: Thanks Mr. Celades for having us here in your office. You have been and are involved in many businesses, so how did you get involved with MDI not even coming from the car industry?

Miguel Celades: I had been interested for long in finding out wether the water-powered car existed. One day, I metioned this to a friend of mine and he told me that I should be stopping looking for that and instead focus on something realistic but groundbreaking. He introduced me to Guy Nègre, the creator of the compressed air engine, back in mid-1998.

ABG: So tell us a little bit about Mr. Nègre and how you met him.

(Continue reading after the jump to find out some history, what MDI is planning for the near future, some highlights on their business model and their agreement with Tata Motors)

If you inflate a balloon and place it on a little toy car frame and then release it, it will race across the room until the balloon deflates. That is essentially the idea of engineer Guy Negre of MDI in . Popular Science magazine reports he is working with an Indian company to put about 6000 Air Cars on Indian streets by August 2008.

In case you've missed the previous stories (see below), Mr. Negre is using a piston-type engine to extract the stored energy in the compressed air to drive the wheels. This makes elegant sense. Why do we combust air with fuel in an engine? To get high pressure, of course! Compressed air at 4350 psi is powerful! And it takes energy to raise air to that pressure level with is actually 290 bar (290 times higher) than atmospheric pressure. Stored gas pressure is like stored energy in a battery. You put it in at one time, and you take it out later. Gasoline and diesel engines put energy in (the fuel) and take it out at the same time.

Compressing air to 290 bar is a relatively straightforward task. Take a reciprocal compressor, power it up, fill the Air Car's tanks in a few minutes, and then drive away. That takes energy, probably electric energy, to get that done. Petroleum use can be avoided but electric use is still needed. The car will even come with it's own on-board compressor. Refilling that way should take about 4 hours.

The range of the vehicle is said to be 125 miles and it has a top speed of 68 mph. I haven't gone through the thermodynamics of the full process but I gotta admit this is a pretty nifty way of circumventing petroleum use. If the compressor is green-powered (solar, water, wind, etc.), the Air Car will be too. And vice versa.

Related:

• A new agreement between Tata Motors and MDI bring the air-car closer to reality
• India's Tata Motors and France's MDI sign agreement to build compressed air-powered cars
• Old video of air-powered car making the rounds at YouTube

[Source: Popular Science, MDI]

Funny how what's old becomes new again, thanks to the archiving power of sites like YouTube. A seven-and-a-half minute video clip from CNN (a global or international version of the news network, by the looks of it) that was posted to YouTube in February just got picked up by MobileMag. The video is of a minicar that runs on compressed air. The technology is the work of Guy Negre, MDI president who used to work on F1 engines and his son Cyril. They have been working on the Air Car in the south of France since 1997 and have over 30 patents on the technology.

Even though the YouTube video was uploaded in February 2006, the original CNN broadcast was from 2004 (The announcer says the vehicles should be on the road by the end of 2004, and the scroll across the bottom speaks of a major suicide bombing at the U.S. military's "Green Zone" in Baghdad). MobileMag is ebullient about the car, which from the video sounds great ($6,000 for a car that can go 110 kmh and doesn't pollute? Sign me up), but the reporter focuses more on calling the car "radical" than on the obvious problems with the car (the cost and energy required to compress the air at home, the range, etc.). While the news is old, it is interesting to see how YouTube can help our collective memory for what kind of car tech was hot in 2004. The Air Car's website from MDI is here.

[Source: YouTube, suggested by Jason Kapadia]