The Air Car?

Until a few days ago I had no idea that people were playing with the idea of using compressed air to power vehicles. Now it looks like we may see some within the next few years. Add in a hybrid gas engine to compress more air and compressed air vehicles might go further than just city driving.

But even if just for the city, and particularly if power sources come increasingly from solar and wind, the idea just might be a life saver not only for those living in very polluted cityscapes, but also for the rest of us as air pollution is a global problem.

And the idea isn't limited to cars. The video below highlights both a rather conventional but all-aluminum piston engine from France, and a much smaller rotary engine design from Australia. The latter shows much promise for small vehicles, but also for recreation vehicles, lawnmowers, golf carts and much more. Take a look:

Compressed Air Vehicles

Hat tip: Barry Ritholtz at The Big Picture

See also: Compressed-Air Car at Wikipedia

OK.. Now that I've got some all hyped up, let's let the naysayers have a say. I just did a bit of after-the-postup Googling and found that Celsius blog ran this thing about a year ago. In Nov, Celsius reader Mark offered this up:

November 9th, 2007
This car is for the naive. The energy density of compressed air at 300 Bar, the pressure at which it is advertised for the MDI car, is 4 MJ/Kg. The energy density of gasoline is 47 MJ/Kg, almost 12 times greater than compressed air.

On the only published test they did, the car got only 4.5 miles on a full tank of air. In order to get the range of a normal car, the air tanks in such a car would have to be the size of a moving truck. Even then, the filling up process will take hours, which, like electric cars, means that they will not be practical solutions for transportation. As for heating the car, well I’m not sure how you heat a car with compressed air, but if you can, you will need to drain the energy from the tanks to do it. With fossil fuel cars, heat is a waste product so no energy penalty is required to heat the vehicle. This is a significant, perhaps fundamental, stumbling block to all-electric or all-air cars in cold climates, range and power aside.

This is no breakthrough.

And earlier:

Eric says:
April 4th, 2007
I first read about this car in about 1995. It was then due to go into production “within a year”. It still is. I don’t see any sign of progress whatsover. You may even note that the FAQ on the website of www.theaircar.com hasn’t even been udpated since 2005! (Where as usual it indicates that the car is just around the corner!). I remember when this car was called the ZEV, when it was called Air Car, when it became the CAT.. I’m sorry. But I just don’t believe in it any more.
ps. I’m an engineer and I know that technically it works.

But other Celsius readers are more hopeful

John Gauthier says:
May 30th, 2007
I’m an engineer, and a skeptic. I pulled out my thermodynamics textbook and checked the math. I confirmed that they can produce the energy that they advertised (about 41 MJoules per 300 liter tank).

While it sounds too good to be true, you have to consider what they have working for them. Yes, the energy density is a lot lower than that of gasoline, but their tank is about four times as large as the average gasoline tank and the energy efficiency of the engine is a lot higher than a combustion engine, which discards an incredible amount of energy as heat.

As far as the naysayers that continue to discredit the idea of using power from the electric grid to charge the car with a compressor, it’s a lot better alternative than personally pumping hundreds of pounds of CO2 into the atmosphere every year. Besides, you can take advantage of power sources that don’t produce CO2 that are only practical on a large scale, like nuclear power.

Hope springs eternal! Where does reality lie?

Comments

[Amanda Walton Gaston]

I found your blog while researching the idea of coal converting to oil for my article, and really enjoy your blog writings and reviews. I wish there was a way to run a car on air to get the power and mileage, or on electric for power and mileage. My husband and I just recently sold our suburban home and took our three kids, bought and RV and are travelling Canada while running our business and homeschooling our kids learning and advocating to Go Green with environmental awareness as well as the economics of it. Although we stay in the Provincial Parks from 3 weeks to 3 months using our truck as little as possible biking or hiking many kms to sustain ourselves and try to keep the gas usage for pulling our trailer to the next spot. I've been seeking out trying to find the best way to go green with an RV and the best idea so far I've seen was the Earthroamer Xpedia which is very environmentally friendly, something we will be looking into further as we are doing this for approx 2 years, seeking out the best place to purchase land then start building our home totally off the grid and as environmental friendly as we possibly can.
Isn't it disappointing when you come upon something that seemed like a great breakthrough just to find out huge corporations have sunk next to nothing into a better development and why...how much moeny will everyone in these oil loving industries make if we became a majority green society?

[SJC]

Air electric hybrids are possible. Air can recapture a lot of regenerative energy without a lot of batteries nor super capacitors. Just a small amount of batteries and a motor with a compressor and expander can capture energy and use it on take off.

[joe]

One thing i've noticed is that nobody talks about conserving the heat of compression by insulating the air tank(s). It also seems possible to build a steam/compressed air hybrid system, in which the heat of compression is used to heat water to steam when charging. The heat of steam to water condensation could be used to help maintain air pressure and avoid freezing problems. This system could take advantage of the waste heat produced by a small gas or diesel engine (cogeneration)and regenerative braking.