Compressed Air Car

[jollyrgr]

Okay, someone has made a compressed air car.

http://www.businessweek.com/autos/conte ... ries_ssi_5

Now I know that compressing air takes energy. According to the story this car gets about 300km (185 miles) on a tank of air. A tank of air is about 90m3 (about 3175 cubic feet). Specially fitted petro stations can fill the tank in two or three minutes. But a home compressor (either at 220V or 380V) can fill the tank in three or four hours.

So I need to ask the "compressor" experts out there; what is the "wattage" needed to compress 3175 FT3? It seems that something is being overlooked somewhere. Like most schemes this is a "ZERO EMISSION" vehicle. But not really. There is a "tailpipe"somewhere. There is a fuel cost somewhere.

Aside from this I DO like one aspect; the air conditioner. The cold from the escaping air is used for the cooling properties as it expands. R12 is impossible to get or very close to it. R134a is hard to get depending on the year. Still having a leak is expensive to fix. With a leaking compressed air you cannot be accused of having dangerous gasses in the system.

[dacflyer]

i am guessing they might be using a sort of compressor like used for jack hammers etc..they move hi volumes of air and at high pressure..
i wonder what the air pressure is on the car?

also i have seen a blower type of copmpressor...sort of looks like a super charger..uses about a 5 HP motor on it..this one was used at a gas stationhere long ago,, what for i do not have a clue...

[Chris Smith]

Knowing the value of stored Air, it sounds like its full of crap.

[Janitor Tzap]

There was a back issue of Nut's & Volt's from 2006 that had an article about
an Air Powered Car.

Also....
I believe this is the same car that was shown on the Discovery Science Channel in they're Series "Cool Fuels".

Here you go....
http://www.theaircar.com/howitworks.html


Signed: Janitor Tzap

[Chris Smith]

Air like any medium can be used to transfer energy, run a car etc.

Creating the pressure for the air is the real problem exactly like spitting water into Hydrogen and Oxygen. It Takes more energy to split it than you can get back out of it.

It still takes gobs of energy to form a gas for usage and that energy is better used more efficiently in other forms.

Its like saying lets expend huge amounts of energy to find and form water by searching out hydrogen and oxygen in the air, then combining them using the energy,.... but then storing these two elements in the form of water so we can now split back them apart once more into two elements, then recombine them using the energy?

Just start with water in the first place and save your self the looking, hunting, and pecking?

All the air does is provide a high loss driving medium, but the energy needed to make the air usable is better used directly and far more efficiently in other ways.

You can also make a torque convertor out of two room fans facing each other with one on and one off but the loss there is exorbitant and wasteful.

Seal them both up and use oil instead of air and the numbers go up.

Same goes for air driving anything.

Convenient when your near a wall outlet, hose, and compressor but totally impractical while your on the road.

There are no free lunches in physics.

[haklesup]

The value of such a car is as a technology demonstrator. It shows us that it is possible and keeps the media and public excited and aware of the changes that will be necessary to move away from a fossel fuel economy.

Its unlikly that we will have the option of all air powered vehicles but as a component in a multi mode hybrid of some kind, it could be a competitor. Perhaps as an alternative to electric regenerative braking or as a boost for accelerating (gas electric) hybrids with insufficient gas engines.

I see this as similar to a flywheel. A way to temporarily store mechanical energy without the losses associated with conversion to and from electric.

[ecerfoglio]

I see this as similar to a flywheel. A way to temporarily store mechanical energy without the losses associated with conversion to and from electric.

I think it is more like a very BIG spring than a flywheel. It just stores mechanical work (force x distance = pressure x volume)

In ideal (=isothermic) conditions it may work, but as you compress air it heats up, forcing you to compress it into a hot tank. It then cools down, lossing some of the pressure that you put into it

[Chris Smith]

Air is not a practical energy transfer source. It doesn’t compress or carry well, taking exorbitant amounts of energy that has to come from some where just to create and store it, and then pound for pound and volume to square surface area, it is a waste of time.

Its density energy per square area and container weight is a loss.

HP tanks weigh a lot, they are a bomb waiting to go off, and they store about enough energy to travel a mile or so and all for what? [just look at the oxy acetylene tanks]

A capacitor or battery can store dozens of times the amounts of the same energy for less weight, safety and cost.

Air is inefficient in all ways for the storage of energy and that’s why the compressor is always near the air tank in a garage, which is right next to the energy source called the wall socket.

The only reason we use it is for lower pressure applications and the convenience of the air hose.

There are no free lunches in physics and using air for any untethered public transportation is just beating a dead horse.

You still need to come up with the energy needed to make the air work at its completely inefficient ways.

Stick to the electron, it has more energy in it than air could ever have and its easier to make, store, and reuse.

They tried that the last century with gun powder engine/ motors, and compared to gas it was not only a joke but a complete waste of time.

There is no upside to using air for a motor or engine transportation.

[markp]

3,175 cubic feet is 10' by 10' by 31.75'.

You could park a large SUV inside that volume.

How big is this car ?

[haklesup]

3175CF must be uncompressed volume (I couldn't find where you got that #) What PSI would be required to squeeze that into a standard air bottle?

Its unclear from the site if they actually built a car yet or just have some good prototype components. Anyway that pee wee car they picture would probably have the equvelent of a 40MPG econobox with a 1.4L 4 cyl gas engine (or smaller). The kind you really only see in europe.

If it does have the range and specs they claim, I can see it being used in golf carts and fork lifts (in the US*). It might cost a little more but the cleaner operating enviornment might be attractive (for green golfers and fume choked forklift operators). Instead of using electricity to charge the tanks, I think a windmill driven comperssor would be a perfect match. With a big enough reserve tank, one wouldn't need wind all the time and of course it would have a conventional power backup.

Remember, going Green doesn't necessarily mean saving any money. Did you catch the part about it having a Hemp fibre body. Definately some Euro-Hippies working here.

*I say in the US because Europe really does have a market for tiny little cars with limited range useful only within city limits. Taxi fleets are traditionally the first point of attack when trying to get transportation tech adapted.

Intuitively, I wouldn't think air to be efficient enough for a transportation application but if these people can make an actual car and match it with a market then hats off to them, the proof is in the pudding. It also could be just another Pop-Sci pipe dream.

There may be no free rides in Physics but sometimes you can buy a ticket with brain power rather than elbow greese. Hands down, gasoline is the clear winner for energy density is almost every race (nuclear notwithstanding) but thats not the point, the point is its probably going to run out (or at least get so expensive as to be for special use only) and we need every option for replacing it on the table so we know which is best ASAP.

As I see it, electric is still the most flexible option and if they can come up with a little better power storage tech, it will end up being the preferred tech. However if the cost of storing more than 10kWh of power dosen't start to come down soon (that battery could cost >$10K), there will be plenty of room for other energy technologies to compete. The biggest drawback to electric as I see it is the occasional battrery replacement cost.

[jollyrgr]

3175CF must be uncompressed volume (I couldn't find where you got that #) What PSI would be required to squeeze that into a standard air bottle?

Go to the link in my posting above. Scroll down about half way through the story where you see a one line paragraph that says "How does it work?" The next paragraph says "90m3 of compressed air is stored in fibre tanks." The conversion factor from 1 cubic meter to cubic feet is:
1cubic meter = 35.3 cubic feet (Google the term "conversion cubic meter to cubic feet" no quotes). 90*35.31 is just over 3175 CF.

Here is more about the car for those interested.
http://www.businessweek.com/autos/conte ... 068744.htm

As far as pressure...
Go here:
http://www.theaircar.com/tecno.html

The pressure is stated here as being 300 bars. I'll save you the trouble. 1 bars = 14.5 psi. I'll save you even more trouble; 4350 PSI.

[Chris Smith]

You always must create the energy, before you store it in the form of air.

Air, is not a great way to store energy.

Air is not a great medium to use for energy.

Liquids have light years over air, electrons have even more, and they always have.

Take one compressed AIR cylinder from any welder at 2000 psi [almost 100#] and still you wont contain enough energy to push even a golf cart more than a few yards.

Even liquid oxygen in the same tank doesn’t have that much more energy and after that, you cant compress a solid.



A bottle standing 5 foot tall, 12 inches in diameter contains air at room pressure equaling 6780
c/ inches or 4 cubic feet of air.

The same tank filled with of liquid oxygen contains 3500 [860:1] cubic feet of air at sea level.

A 100 c/I engine [1.6 liter] consumes air at the rate of 100 c/I per second, or 60,000 c/I per minute at 6000 rpm or 35 c/f of air per minute.[still it has no gain with the out fuel air combustion]

So a tank containing 3500 cf of air will only last with no extra energy out put at the rate of 100 minutes, [standard consumption with zero out put] and then you still need to add in some form of energy to make things work? [Gasoline and air combustion]

This liquid oxygen bottle will only supply air to a 100 cubic inch motor for this amount time but its still ready for some kind of combustion or energy out put,... so with out combustion, there is no extra out put of energy for any time worth mention,.... meaning if the bottle can drag it self along for just a few yards at a time, things would be lucky.

And by no means is this an accurate example of compressed air, newer motors, or any thing else.

It was meant to show the example that air is almost a useless medium for storing energy.

If you want things to move, by pass the air and use that energy directly in a more efficient ways like fluids or electrons to accomplish things.

Even using a error rate of ten times mentioned above, LOX is still a useless form of stored energy, when not combined with either hydrogen or one of its other explosive or reactive constituents.

[GoingFastTurningLeft]

There are no free lunches in physics and using air for any untethered public transportation is just beating a dead horse.

Isaac Newton got a free lunch when that apple fell out of the tree.

[Chris Smith]

Actually he didnt.

Nature had to lift the tree and the apple via the sun, he simply cashed in on the day it fell.

Remember this entire planet is solar driven. [use that energy well]

Air is not a source of energy, its a medium to transport energy, and a poor one at that.

[GoingFastTurningLeft]

Actually he didnt.

Nature had to lift the tree and the apple via the sun, he simply cashed in on the day it fell.

Remember this entire planet is solar driven. [use that energy well]

Air is not a source of energy, its a medium to transport energy, and a poor one at that.

Yes he did. He didn't have to pay for that apple.

Geez....