# Car that runs on compressed air !!



## Helena (May 10, 2002)

On TV the other day at my daugthers house saw a program about a car that runs on compressed air and gets about 125 miles on a fill up..don't know the size of the fill up..or if you buy the air at a station for $2. It was a decent size car..4 cy cost about $7,000 and up to the 6 cy engines. I was amazed at this. I would buy one in a heart beat if they become common in our areaa but the concern would be when traveling would their be enough "air stations" on a trip to supply you with air. Anyone hear or know about this car !!???:sing:


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## WisJim (Jan 14, 2004)

Compressing air takes LOTS of energy, and the figuring that I did some time ago shows that this is not a very efficient way to power a vehicle. Of course, the promoters of air-powered cars don't tell you this. Air powered cars got quite a bit of publicity a few months ago.


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## wy_white_wolf (Oct 14, 2004)

http://www.homesteadingtoday.com/showthread.php?t=261817&highlight=compressed+air

TMK they haven't advanced any in the last 8 years or so.


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## farminghandyman (Mar 4, 2005)

I can not see how this is even a consideration, 

I use a lot of air tools and it takes a 5 hp air compressor to run a small sander that would be less than 1/4 hp if electric, 

I have yet to see how compressed air is efficient, (I know it or the way some tools operate they work better than electric units, (impact wrenches, is one example),

and yes I use it in the shop, but have never figured out how it could work out in a Car.


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## Jim-mi (May 15, 2002)

I well know how my C.H. compressor makes my inverter grunt on start up. . . .
So yes what is the electric 'cost' to 'fill up' a tank....??

sounds good . . but there still ain't no free lunches.......


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## georgec (Jul 9, 2007)

I can see this working if you have a very efficient compressor. Most compressors are not built for efficiency, they are loud, and put out a bunch of heat.

I think the ideal would be to have a wind turbine driven air compressor.


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## MELOC (Sep 26, 2005)

i think one air powered car i saw was a hybrid of sorts that used gasoline to heat the air when higher speed was required. the burning gas was used to heat and expand the air causing the engine to run at a higher rpm. during normal operation at lower speeds, i think the hot exhaust was used to expand the cooler air feeding the engine, so some of the heat was recycled. i wish i could find a link to that car, it was a pretty interesting read.


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## wy_white_wolf (Oct 14, 2004)

While I do know of a few wind driven compressors I don't know of one that can put out 4500psi

That's about 30 times what the normal household compressor can handle.


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## MELOC (Sep 26, 2005)

ok, i may have fuzzy memory of the recycled heat being used for power, but i think this is the engine i was thinking about.


http://zeropollutionmotors.us/?page_id=64


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## Ross (May 9, 2002)

Don't some torpedos run on compressed air? Different critter sure but the task of powering one of those would demand efficiency in the running if not the charging. I always thought it was a neat idea to power a car with compressed air but the charging did present a problem. I remember an idea I had as a kid. Sink a cylinder with a huge unbreakable bag into the deep ocean. The air from the bag gets pushed into the cylinder through a one way valve. Once the bag is empty and the bottle charged, a weight drops off and the whole thing floats to the surface for use. OK so that might sound a bit nutty but it was a big step up from the rubber band car


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## Jim-mi (May 15, 2002)

Yes on compressed air for the torpedos.....
Whats that tank of air for welding hold 2000# . .I think.......

So how many of you guys have a compressor --at home-- that will give ya tha kind of pressure . .??


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## MELOC (Sep 26, 2005)

it depends on how many beans i eat...but that's not really environmentally friendly.


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## georgec (Jul 9, 2007)

wy_white_wolf said:


> While I do know of a few wind driven compressors I don't know of one that can put out 4500psi
> 
> That's about 30 times what the normal household compressor can handle.


I'm not saying that you can buy one. I'm just saying that it would be a great way to go. A zero emissions car.

The pressure is no big deal. Scuba compressors go up to 5000psi. You can buy home units.

I think that an air tank is going to have a much longer life span than a lead acid battery. Air tanks dont lose their charge by just setting. Air tanks need no maintenance.


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## georgec (Jul 9, 2007)

There might have been some WWII topedos that used compressed air. The current torpedos use a special fuel that provides its own oxygen.


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## watcher (Sep 4, 2006)

georgec said:


> I'm not saying that you can buy one. I'm just saying that it would be a great way to go. A zero emissions car.
> 
> The pressure is no big deal. Scuba compressors go up to 5000psi. You can buy home units.


"The pressure is no big deal." Ahh. . .wrong! 

Check out the following three links to see what I mean. A bit of a warning, the last link has a bit of graphic stuff so you might want to skip it.

http://www.scubaengineer.com/tank_servicingx.htm

http://www.thescubaguide.com/gear/tanks/safety.aspx

http://biobug.org/scuba/scubatank/




georgec said:


> I think that an air tank is going to have a much longer life span than a lead acid battery. Air tanks dont lose their charge by just setting. Air tanks need no maintenance.


You need to talk to a SCUBA diver.


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## wy_white_wolf (Oct 14, 2004)

georgec said:


> .....I think that an air tank is going to have a much longer life span than a lead acid battery. Air tanks dont lose their charge by just setting. Air tanks need no maintenance.


If they are so maintenance free and safe why all the required testing and push for tougher standards?



> Most countries require tanks to be checked on a regular basis, see gas cylinder. This usually consists of an internal visual inspection and a hydrostatic test. In the United States, a visual inspection is NOT required every year (This is an industrial standard that is not DOT required), and a hydrostatic every five years. In European Union countries a visual inspection is required every 2.5 years, and a hydrostatic every five years. In Norway a hydrostatic (including a visual inspection) is required 3 years after production date, then every 2 years.
> 
> Legislation in Australia requires that cylinders are hydrostatically tested every twelve months, regardless.
> 
> http://en.wikipedia.org/wiki/Diving_cylinder#Manufacture_and_testing


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## WisJim (Jan 14, 2004)

I am cleaning out my desk at work, and found some info on the cost of compressed air at industrial plants. It is a major expense, and they are always looking for ways to use less compressed air and produce it more efficiently. As a ROUGH guideline, a 2004 report said the the range of 18 to 30 cents per thousand cubic feet is a commonly used value for cost of compressed air. The overall efficiency of a compressed air system can be as low as 10% to 15%, so that to operate a 1hp air motor at 100 psi requires 7 to 8hp at the air compressor. Higher pressures get less efficient to produce. Oh, and they were using 5 cents a kilowatt hour for electricity cost. A home compressor would probably be less efficient, and the cost of electricity would be higher.


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## georgec (Jul 9, 2007)

wy_white_wolf said:


> If they are so maintenance free and safe why all the required testing and push for tougher standards?


When I was in PA I had to have my car inspected every year.


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## georgec (Jul 9, 2007)

watcher said:


> "The pressure is no big deal." Ahh. . .wrong!
> 
> 
> You need to talk to a SCUBA diver.


When I said "the pressure is not big deal" I was responding to white wolfs comment that he didn't know of a home compressor that could do 4500psi. I found several sorces for home Scuba filling stations.

I am a certified Scuba diver.


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## Jim-mi (May 15, 2002)

George, I'm curious as to what it costs to get your tanks charged up at the "dive" shop . . .??


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## georgec (Jul 9, 2007)

Jim-mi said:


> George, I'm curious as to what it costs to get your tanks charged up at the "dive" shop . . .??


We don't have a dive shop here in town, but the Fire Dept. will fill them for a $5 donation. I think that's about what dive shops charge too.


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## georgec (Jul 9, 2007)

When you think about a simple way of storing energy, you can't get any simpler than compressed air. It's a tank, no parts to replace, to fluids to fill. They will last forever (as long as you used dry air). What other method of storing energy has that going for it. The closest thing I can think of would be a huge capacitor.


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## Jim-mi (May 15, 2002)

Fire dept . . . that makes sense . . .they have the compressor so as to fill all the tanks for the fire fighters...........
I have some good friends at a local fire dept . . .gotta drop by and look at their compressor ........

But it would be almost the same filling that "Big" capacitor . . a very big grunt load starting that charger. 

again . .there ain't no free lunch......


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## Jim-mi (May 15, 2002)

In going to a 'birthday party' late to day I saw my long time friend who is the head honcho at a nearby volunteer fire dept.. Asked about filling the guys air tanks.
I was told that another fire dept. truck from many miles away very often comes out to a fire scene to fill --'on site'-- the air tanks the guys are using.
The tanks are only good for 20 minutes.
I'm talking about that air bottle that you see strapped on a fire fighters back .

All this from what we all have at 'home' . . a $40,000 compressor mounted on a truck.


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## MELOC (Sep 26, 2005)

i think the big push is for a cleaner fuel source locally. there are areas, like urban areas, than really could use a break from air pollution. that is the big selling point of compressed air. no, we can't get away from the fact that the pollution will be put in other areas. the electricity to run the compressors will need to come from somewhere. there are some glimmers of hope. if i am not mistaken, most electricity in the USA is produced from fuel that comes from the USA. at least those dollars can stay at home instead of being shipped to people who hate us. here is another hypothetical boon...perhaps the demand for electricity to run the compressors can be fit into a schedule or system that makes it feasible to design alternative systems. maybe it will result in having the demand to support oversizing alternatives like wind and solar combined with enough fossil fuel back-up to run modern, hybrid grid power. if "x" percentage of fossil fuel consumed by cars was converted to wild or solar, and even if there was no net gain by removing current fossil fueled domestic electricity (the hypothetical back-up of the off peak alternative production) at least we would have that.


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## watcher (Sep 4, 2006)

One thing I don't think we have discussed here yet is the terrible efficiency of this. I don't have the exact numbers but let's assume things are reasonably efficient. Let's say you have 80% efficient an electric motor running a 50% efficient air compressor (I don't think you can find one of these) storing air for an 70% efficient air motor (again I don't think you can find one) and you start out with 1,000 units. This means for your 1,000 units of energy you get 280 units of work (1,000 * 0.8 * 0.5 * 0.7 = 280) If the compressor is as bad as suggested (20%) its even worse at 112 units.

I'm sure someone here could tell us how efficient batteries and motors are as well as crank the numbers using a battery operated car.


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## mnn2501 (Apr 2, 2008)

There will always be people tell us that we can't do this or that because....... 

Look at how efficent gas powered engines were in the early 1900's, look at how explosive gasoline is. I am sure the horse and buggy lobby was pointing all of this out back then.

The fact of the matter is, any new "fuel" or "engine" is going to be ineffiecent and dangerous until we start using it, and then the technology will advance and it will become more efficent and less dangerous as we improve on it year after year, decade after decade.

I don't know what the ultimate answer to energy and driving will end up being, but standing around pointing out all the drawbacks of everything isn't helping one bit.


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## CamM (Dec 6, 2008)

mnn2501 said:


> There will always be people tell us that we can't do this or that because.......
> 
> Look at how efficent gas powered engines were in the early 1900's, look at how explosive gasoline is. I am sure the horse and buggy lobby was pointing all of this out back then.
> 
> ...


Yeah. Don't solar panels only have an efficiency of 15 to 20%? I doubt wind power's much better. Technology improves.


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## DMD Farms (Jun 8, 2008)

I have been looking at these things mostly on you tube.....once you see just what they are doing it looks pretty good....to bad India got them before we did....they have onboard compressors that can refill in a few hours pluged into 120....add a wind turbine and charge overnight...it would work for me.
http://www.mdi.lu/english/index.php


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