No Such Thing as a Free Ride - Not Even in the Air Car

I recently saw a TV show on green car technologies. I'm always excited to hear about a new one. Surely, one of these days they're going to come up with something that does better than 40 miles per gallon that you can actually buy. One of the featured cars was the "air car" invented by Guy Negre of Motor Development International (MDI). Using compressed air as an energy carrier, it has zero emissions, and is very compatible with renewable energy. They showed pictures of a little girl breathing fresh air, and then someone saying how nay-sayers just don't have the imagination to see such simple solutions. The range for a single tank or charge wasn't bad at 200 km, and with speeds up to 60 mph, it sounded like a viable option. But as the show went on, one of the promoters said something about how an on-board air compressor could be used to refuel the car. Not bad. Just plug it in, and the energy is as clean as your grid. But then, he goes on to say that someday we could run the air compressor off the car to refuel the car - perpetual motion! Apparently they have also discovered a way to overcome the first law of thermodynamics - conservation of energy.

I felt that sinking feeling that you get in the pit of your stomach when you realize something that you really wanted to believe just can't be true. Clearly it must be me who is lacking imagination - to think that we can't get around the basic principles of thermodynamics. In case it's been a while since high school physics, the first law of thermodynamics states that energy cannot be created or destroyed. It simply changes forms, for example from potential energy to kinetic energy. Another way of saying this is that you can't get more energy out of a system than you put into it. So you can't have perpetual motion unless you have no energy losses like friction or heating. If there were no friction between the tires and the road then the car wouldn't move.

Why couldn't they just stick with what is good about the car and not go making ridiculously impossible claims? So then I became suspicious. If they're trying to make it sound like this car runs for free and won't need any external energy source to power it, what else are they lying about? So I did a little bit of web research. Surely something this hot should be all over the place. Right? Well the most recent news headline was from 2008, stating that these cars would be released in 2009 or 2010. Hmmm. The actual title itself was also telling "Air-powered Car Coming to U.S. in 2009 to 2010 at Sub-$18,000, Could Hit 1000-Mile Range." No, that's not a typo. It actually says one thousand mile range. That would be very cool - but who do they think they're fooling?

Finally I found an article that wasn't just reporting the specs from the manufacturer. It was written by someone who actually test-drove a prototype of the MDI 2010 Airpod, published as recently as June 2009. You can find it on the Edmunds Inside Line website. Nick Kurczewski of Green Car Advisor flew to Nice, France for the test-drive. He reported that the car could go up to 30 mph, but that acceleration was "glacial". The air inside the car was not, however. It was very hot since the prototype had not yet incorporated the cooling effects of the decompressed air emissions. Kurczewski didn't get to drive it long enough to test out the range, but MDI claims it to be between 90 and 125 miles. Regardless of how slow the thing is, or what its range is, at least now we know it really exists.

But what happened between June 2009 and now? Why the media silence? Well, it wasn't big news in the U.S., but in December 2009, MDI delivered two AirPods to KLM, the Royal Dutch Airways at Schiphol airport for testing. Around the same time, a team of researchers from UC Berkeley and Stanford published a report concluding that compressed air engines are significantly less efficient than battery operated electric vehicles. This loss of efficiency means that even though there would be no emissions at the car's point of use, if the grid that is used to compress the air is powered by a coal intensive power mix, than it would actually produce more greenhouse gas emissions than a conventional gas-powered car. Bummer. However, if that grid were mostly powered by renewables like solar and wind, the car would do better than a gas-powered car, and is cheaper to produce than a battery electric car. The same report also concludes that a compressed air and combustion hybrid would be feasible and less expensive to produce than battery electric hybrids.

So where does that leave us? It seems that MDI has made some worthy contributions to the search for a more fuel-efficient vehicle, but for now they do not quite have a road-ready, zero emissions vehicle. So I'm annoyed by their over-inflated advertising, but pleased that they're out there working on an alternative to our beloved gas-guzzlers.