Air powered engines for cars.... (1 Viewer)

[todd s]

Was just watching a new episode of the show "Beyond Tomorrow". And they showed an Australian & French engine designers who are seperately working on compressed air powered engines. From the prototypes they have working. I can't see how this might not be a extremely viable option for future cars.
The company in France will have a car available next year for around 15k. It could go up to 110mph.

 

[ChristopherDAC]

You can't build a pressure tank which will store enough energy to run a car for very long — if you could, there wouldn't be a problem with hydrogen/propane/natural-gas cars — and even if you did there would be a very big risk of it blowing up like a bomb. The energy capacity [heating value] per unit volume of petrochemical liquid fules is, sadly, almost unmatched; the only thing better is plutonium.

 

[todd s]

Chris, they talked about the pressure. They use a tank that if ruptured wouldn't explode like a regular tank. Also the engine is very, very light. Since the engine doesn't get very hot they can uses some other metal. Also, the engine of the guy from Australia is only a few pounds and can be held in someones hands. The tank lasts a few hundred miles. And that if they had a hybrid. I believe they said on one tank of gas since it refills the air tank it could go from NY to LA. My 3yr old decided to jump on me at that second. So I miss the specifics. I am pissed I wanted to DVR it for my dad..who likes all this stuff.

 

[BrianW]

That Australian engine is pretty ingenious. I'm amazed such a tiny thing can move a vehicle that heavy, that fast. That thing was no bigger around than a small pizza, and only a few inches thick.
Quite true. But with the complexity of internal combustion comes a LOT of extra weight, which, as Todd pointed out, is completely eliminated in the compressed-air vehicles. It's not nearly enough weight loss to fully mitigate the lack of energy density of compressed air vs gasoline, but it's enough (even if barely) to make compressed-air-powered vehicles at least possible.

Mind you, I don't think we'll ever see luxury SUVs using compressed-air engines. But light, quick cars for commuting and grocery-getting are certainly possible. You can even pass the exhaust through the passenger compartment in lieu of having true air conditioning!

 

[Christ Reynolds]

which means, they would never sell in the US.

CJ

 

[Chu Gai]

What independent testing agency has evaluated these claims or is this going to be another one of those stories from the 60's where someone invented a 200 mpg car engine but some car manufacturer, in colusion with the government, stole the idea and burned the plans?

 

[Cees Alons]

... along with the eternal light bulb, eh?
I think these tests were for real. Of course we'll have to wait if they can make a useful (and safe) vehicle for at least two persons. AND a true competitor for the gasoline driven car (not just for a bicycle).


Cees

 

[BrianW]

Chu, that's a good question. The prototypes are real and have been driven by third parties, which is more than I can say for that "self-recharging-battery" guy who cancels demonstrations because the banked curves in the track he reserves presumably ruin the car's suspension.

At least these things really work, and in third-party hands, no less, so I maintain a bit of hope.

Even so, the inventors' claims and goals are quite modest. The inventor of the Australian engine originally wanted a way to power fork lifts and other indoor equipment in order to cut down on emissions in enclosed spaces, like warehouses. Such an environment likely already has air-compression equipment to power tools and such, so keeping an air-powered forklift running would require next to nothing in added infrastructure. Also, range would not be an issue in this envronment.

Will it work for cars? Maybe. But I expect to see it first in forklifts, golf carts, and other "fleet vehicles" that never leave the premises. The French inventor is more ambitious, trying to develop a product for the open road, but even his proposals are modest.

Cees, they're using simple compresses air, not CO2 or N2, so oxygen is already a component in the mix. But the air may have lubricating oil in it, for all I know, which would make allowing it to enter the passenger compartment a bad idea. But they could still run the exhaust through an air-to-air heat exchanger to cool the passenger compartment, though it wouldn't be as efficient. Any way they can reduce weight and power suckification by eliminating the A/C compressor would be a good thing, and cold exhaust is about as good as it gets.

Disclaimer: this post was entered on my phone using a credit-card-sized keyboard. Please excuse any typos.

 

[Chu Gai]

From this website we read...
It'd be interesting to calculate the energy needed vs. that produced.

 

[Garrett Lundy]

Who wants to ride a motorcycle that sounds like a deflating balloon? This will also spell the end of gas stations 'free air' machines.

 

[Jay H]

What if you put up a 60' mast on your automobile. Maybe then it will be air powered! I can see it now, schooners and tall ships backup up at the Lincoln Tunnel going into Madhatten because the cars wont fit!

Jay

 

[todd s]

Granted it may never work for most passenger or commercial vehicles. But, if they can substitute even a 5% of petroleum based vehicles in the US by using this process. That would at least make a small, small dent in US gas usage.

 

[Chu Gai]

That's why we need numbers, measurements, and studies. Not so easy to maintain -100C for a period of time.

 

[BrianW]

Okay, I must be missing something. What does maintaining -100C have to do with it?

 

[Chu Gai]

Read my quote above.

 

[Scott McGillivray]

Cool (literally).

-100 degrees? Ha...no problem. Send those cars up here to Saskatchewan and we will charge them up for free!

 

[Philip Hamm]

LOL!

 

[BrianW]

Chu, lowering the temperature may help to get the air in the tank, but once it's in the tank, you just cap it off and let the temperature rise, which builds usable pressure. Once the gas is in the tank, it doesn't need to be maintained at a low temperature. Indeed, doing so would prevent pressure from building (4500 psi isn't child's play), which would preclude it from doing any work.

You get re-refrigeration of the gas by releasing it and allowing it to expand, which is useful in a Sterling-cycle engine (or simple heat pump, as your quote describes), but it doesn't have to be kept cold in order to come out of the tank cold.

Again, what am I missing?

 

[Chu Gai]

According to what I read Brian, the air in the tank is at a temperature of -100C and 4500 psi. So let's say you've gone to your local chilly air high pressure station and tell the guy 'fill 'er up'. Now you go and park the car and eventually, the temperature rises to say 80.6F or 27C. A cool day for those in Florida, right? So let's calculate the pressure in that tank now.

4500 psi (300K/173K) = 7800 psi

That's a hell of a lot of pressure especially if the tank is going to be big enough to power some sort of vehicle for any reasonable distance. And that driver better hope that the roads aren't too bumpy because it's not easy designing fittings and couplings that will survive the bumps of roads. Then what happens once somebody broadsides you and that tank ruptures? Is the air going to harmlessly release into the atmosphere or do you now have a little mini rocket careening down the road? How much energy did it cost to cool that gas down and how much will it cost to manufacture and maintain the infrastructure?

It's been 4 years or so since that quote that I yanked appeared. More than enough time I think to illustrate a practical working concept that is safe and is comparable to conventional transportation. Also, more than enough time to have generated some data on costs. Myself, I think these people may have more interest in obtaining funding from people with more money than they know what to do with. Kind of like Toyota dropping 10 million on cold fusion.

If you want to harness air for energy then there's no better place to start than putting those propeller towers near every local, state, and national building that's got politicians and let's not forget the lawyers and Walter Cronkite while we're at it.

 

[BrianW]

Chu, thanks for going to the trouble. I read the quote, but I didn't click on the link when I asked what I was missing. (I was at work, so I couldn't surf.)

I wouldn't want to drive around with a 4500 psi tank, much less a 7800 psi tank. So 4500 psi is the cold pressure, and they intend to keep it cold?

Wow. I think that's just dumb. (You seem to agree, yes?) I understand that using cryo would increase the energy density of a compressed gas, and every little bit helps, but I don't think such a system will ever be safe or practical.

The systems demonstrated on Beyond Tomorrow were simple, ambient-temperature compressed-air systems with carbon-fiber tanks. Like I said, they were relatively modest prototypes. Cees nailed it with his "bicycle replacement" comment. These are better than that, but not by very much, IMO. CJ's comment that they won't sell in the US until they can make a luxury SUV is, unfortunately, probably on the mark as well.

Personally, I drive a high-mileage, 2-passenger commuter car every day to work. If I could replace it with a compressed-air vehicle that could go 60mph and ran 100 miles per refill (and I could refill it over night with a compressor at home), I'd seriously consider doing so.

But then, I'm not like other people.