Car to run on compressed air heated by gas; >100 mpg, 90 mph

Hmmm, I’d read an article about a guy that had converted a regular gas engined car to run on compressed air only.
At the time he said all the major oil companies were out to get him to stop him from putting them out of business.

Two concerns that were brought in the CNN article (which I don’t know how valid they were) is that A) the safety of the super light frames and B) supposedly the compression is higher than in even industrial settings and requires a significant amount of energy to compress which may make it less efficient than claimed.

I guess that is/could be a concern.
I know that back in the early 60’s some drag racers had figured out that using compressed air meant you could regulate your air/fuel mixture more precisely.
However, there were extreme concerns about what would happen during a crash.
IE huge bomb.

Yeah, I watched a special on alternate fuels a while back that featured this project. The thing that they don’t include in their efficiency figures is the (fairly considerable) amount of energy needed to compress the air in the first place. Taking that into account, it’s apparently somewhat less efficient than a regular electric car. The light frame is also an issue–the test vehicle is really more like a go-kart than a car, and critics question how much those fuel efficiency figures would drop if you put that system in a chassis that would actually be legal for street use.

In the special that I saw, the inventor was waxing ecstatic about how the car recharges the air tanks while its moving, and how eventually they hoped to be able to get it so that it would never need to get compressed air from external sources at all. I was like “Perpetual motion… good luck with that.” The guy seemed a little nutty.

Gotta love how the expert they quote poopooes the whole thing by saying he “doubts it could get more than 75 mpg”.

Come on, that’s still triple what the average American model car gets right now, right? How DARE they only triple the average, why, Detroit might as well ignore them!

Huh? The actual quote is:

So he is just saying that 100 mpg would be good, not dismissing it, just the opposite of what you suggested.

But I think there are some serious issues here, considering that the fuel-burning heater is only supplementary to a compressed air tank that is in effect another fuel component:

  1. A very high pressure tank is clearly dangerous in a collision. 4,500 PSI sounds a bit dicy to me.

  2. The energy cost to pressurize the tank may be too great to be economical.

  3. They don’t mention a driving range for the compressed air tank. Presumably when the tank is exhausted, the tiny fuel burning heater wouldn’t do enough on its own to move the car.

Edit: Oops, missed the 800 mile range. That’s fine for point 3, then :)

  1. No performance measurements are even suggested. Even with that ultralight car (which itself can be very dangerous in a collision or in high winds), who knows how long it takes to get to 60 mph?

So basically, great, if it really works, but until it works in an advanced prototype with measurable numbers, it’s just hype.

The one I read about in Reader’s Digest years ago was a converted 1976? Ford LTD station wagon. (these things were huge)
The guy was saying that “power is available instantly, unlike in a normal gasoline engined car”, he goes on to say “not knowing this, during my intial test drive I floored it, and found myself with the front tires 2 feet off the ground”.
This is as mentioned above a full-sized car weighing in at around 4000 lb, so, whatever this guy did (allegedly) 15-20 years ago, the “new” air powered car they are working on isn’t nearly as powerful.
The article didn’t mention range or fuel economy, so I don’t know really how feasible this would have been.
He did mention something about using the air conditioner compressor to some how provide the compressed air the car ran on, so it was a sorta perpetual motion thing going on.

Why why do all the new alternate fuel cars have to be so goddamn ugly?

Their mileage estimate does not figure in the energy necessary to compress the air. Fail.


The difference is that this version is going for range. It is certainly feasible to produce that kind of power from an air tank compressed to 4500 PSI (racing cars using nitrous oxide produce similar pressure at combustion)… for a few seconds. Then you’d have no more air. If they want it to last longer, they need to regulate the output a bit more.

Even then, the numbers seem pretty dicey. 340 liters of air at 4500 PSI is the equivalent of about 18 million foot-pounds of energy. One horsepower is 550 foot-pounds of energy per second. They claim that their car has a maximum output of 75 horsepower, but that air tank can only put out 75 horsepower for ~7 minutes before it is empty. Of course, a car is not always operating at peak horsepower, but in order to cover 125 miles*, the car would have to be putting out no more than 5 hp at 65 mph. And that’s assuming that you are only driving a constant 65 mph–any starting and stopping would use more horsepower, and dramatically decrease that range.

That’s not factoring in their heating system, but it’s also assuming that their pneumatic engine is 100% efficient in its energy conversion, which it isn’t (air-powered motors are typically somewhat less efficient than internal combustion engines). Honestly, I’m skeptical that even their little go-kart chassis gets anywhere near the performance and efficiency they attribute to it–even ignoring the amount of energy needed to fill the tank–and I doubt they’d ever make it work in a car that was street legal in the US.

That’s assuming that they can ever pass crash testing with a 340 liter, ~4500 PSI air tank mounted in the car, which they probably can’t. That thing would turn a car into confetti if it ever got into a serious accident. Did anyone see the episode of Mythbusters where they used C4 to rupture a diving cylinder, and it exploded with enough force to bow out the sides of a steel shipping container? That tank had only about half the capacity as the one they are using in this car, and was only pressurized to 3000 PSI.

And speaking of pressure, they indicate that the compressor for filling that tank will be built into the car, but compressors capable of producing over 4500 PSI are very large (some dive tank compressors are as big as a car, though I have seen paintball compressors that are “only” the size of a desk) and very expensive (~$5000 to 10,000). So again: very skeptical.

I’m all in favor of wacky alternative fuel experimentation, but I think this particular guy is a snake oil salesman. Much of what he claims that his car can do is far too good to be true, by a lot.

*Note that while they seem to indicate that the car has a range of 800 miles, I’m pretty sure that’s just how long a tank of fuel will last. The air tank will probably require multiple refillings over the course of 800 miles, the actual range (before you have to park for four hours and re-pressurize) of the similar air-powered car that is being produced in India is only about 125 miles.

Umm, what’s wrong with batteries?

Like, I’m quite happy not having a giant tank of compressed air under my ass waiting to explode the moment bird shit hits my car.

Finally, cars that explode huge like in the movies, every time they wreck!

wishful thinking

Mainly that they have low energy density, so they’re big and heavy, take a while to charge, and eventually have to be replaced.

If they could just improve the energy density enough, they could get to the point where refueling would just be a matter of swapping out the battery pack for a precharged one, but battery technology advances rather slowly.

You don’t see the Tron influence in that design? Get into the future, man.

That’s because the battery people WANT your batteries to fail so you will buy more. I read that somewhere…could be a conspiracy theory?

Planned obsolescence? Never heard of it.

Planned obsolescence was supposed to be phased out by now.