Compressed Air Cars

Instapundit is talking about compressed air cars.  The big problem with this technology is you’re essentially driving with a bomb under your car.  Gasoline contains a lot of energy, but it won’t explode under normal conditions.  You’ll get a hell of a blaze, but not an explosion.   Any compressed gas technology is going to have the fundamental problem of an explosion hazard, not because of the gas within being explosive, but because of the tremendous amount of energy being stored up in the tank.  See this summary of a dive shop explosion that occurred when the tank failed.

Also, the net greenhouse gas savings here would be negligible, since it will take copious amounts of electricity to operate the fill up stations and compressors.  This energy, if it comes from burning coal, will just shift the greenhouses gases to the power companies.   But still, this technology is more promising than the ones that involve reacting light metals with water to produce hydrogen.

5 Responses to “Compressed Air Cars”

  1. GeorgeH says:

    The scuba shop was blown up by one 80 cubic foot tank. The tanks in the car hold 3178 cubic feet according to the Business Week Article referenced by Instapundit.

    That is just under 40 (39.7825) times as much. Have a wreck, and your remains are going to the moon.

    Hydrogen sounds safer and I have no interest in buying a 4 wheel Hindenburg.

  2. Jim W says:

    People have been driving around with heated nitrous oxide tanks in their cars for decades with only the rarest accidents. The technology to do this safely existed about 40 years ago and has been in widespread use since. Pressure release valves have been a mature technology since the early days of the steam age.

    GM had a car that stored energy by running an air compressor off the accessory belts and then using the compressed air for a performance boost, but it never got into production.

  3. Jim W says:

    And I should point out that the only guy injured in that accident was standing next to the tank. Everyone else was PUSHED back. As powerful as it is, compressed air explosions are powerful deflagrations at worst. Once you are missed by the container fragments, you are pretty much home free. Since any compressed air tank would be on the other side of steel body panels, occupants of the vheicles would be jarred but probably not injured.

  4. Sebastian says:

    Aren’t nitrous bottles generally kind of small? We’re talking bottles with enough energy stored up in them to take a car, presumably, several hundred miles. Having that energy released in a short amount of time seems like it would be pretty ugly.

  5. Jim W says:

    That is a good point. Nitrous and other compressed air type systems are generally built around the idea that the compressed substance would be used to burn fuel. I admit I was mostly thinking of such systems.

    The only system I can think of that works by riding down a decompression gradient is a steam engine and that involves combustion to create the compressed gas in the engine from boiling water. If we store the entire trip worth of fuel as super-compressed gas instead of as room temperature water, that takes the explosive danger of a steam engine and multiplies it a million fold.

    Now that I think about it more, this seems like an obviously bad idea.

    It also raises the question of what we will burn to put the compressed air in the tank in the first place- I’m guessing we burn hydrocarbons. And the pressure of the gas will steadily decrease as we use it, so we would need some power source to heat the air tank as it empties.