Compressed Air Cars

[larryj54]

This is a technology that fascinates me. Older than the electric light bulb, compressed air is in my opinion sheer GENIUS if for nothing else urban run abouts; although Tata will be making a 6 passenger minivan.

Sooo easy to roll out infrastructure, gas stations already have compressors, and need only upgrade.. Quik Marts could easily get in this game. And one of the proposed methods of recharge is swap out cylinders @ stations, much like you swap for a new tank of propane for your gas grille.

Think of it as an electric car that stores electricity as compressed air. Lighter motor than electrics, simple mechanically; no ignition or fuel systems, clean as "air", lower maintenance, super simple filling infrastructure, easily implemented at home.

Clincher: Scented fills.. Mountain Pine, Lemony Citrus, Spring flowers, Pizza, cinnamon rolls, Brut (by faberge).

[Clev]

Unfortunately, it has the same infrastructure problem as EVs. The ZPM MDI Air Car stores enough compressed air to generate 22kWh of equivalent propulsion. A standard gas station pump, which probably draws no more than 110V at 15 amps, would take 13 hours to fill that tank, IF the compressor operated at 100% efficiency and at maximum power for the circuit.

This means much larger compressors, using much higher amperage. Begins to sound a lot like the same infrastructure problem that EVs have, doesn't it?

BTW, a Tesla-like pack of 18650's with supporting circuitry and rackage weighs about 373 pounds for 22kWh.

[larryj54]

wel theres a number of ways to look at this.. batteries have a finite recharge life.. how's that cell phone and laptop "on time" working for ya after a year of ownership? The air cylinder has an infinite life span (in effect).. and a partial battery charge counts down the life of the battery the same as a full charge.. one could grab a few thousand CF of air like they do a $10 partial fill @ the gas pump.

Then there is the fact that air compressors are old tech and utterly understood.. yeah.. upgrade capacity.. so? Easy to do.. no big EPA permits to worry about like fuel tanks..

@ Home you CAN trade time for capacity and let the car slow pressurize overnite.. so while there are always trade offs, compressed air has MANY virtues.. clean, well understood, simple, low maintenance, effective.

And keep in mind the pre-charged quick swap cylinder idea.
(and scented refils)

[Ryland]

Originally Posted by larryj54

compressed air has MANY virtues.. clean, well understood, simple, low maintenance, effective.

If you think compressed air is low matinece then you have never rebuilt an air compressor, and last I checked no one had figured out a good way to make compressed air cars work in cool climets, they just freeze up!
the only advantage that I have seen is that the air storage tank requires just common meterials like carbon fiber and kevlar to be built, unlike batteries that can be made out of lead and a water based acid and are 99% recycled at the end of their life.

[larryj54]

Originally Posted by Ryland

If you think compressed air is low matinece then you have never rebuilt an air compressor, and last I checked no one had figured out a good way to make compressed air cars work in cool climets, they just freeze up!
the only advantage that I have seen is that the air storage tank requires just common meterials like carbon fiber and kevlar to be built, unlike batteries that can be made out of lead and a water based acid and are 99% recycled at the end of their life.

Air motor compared to an overhead Cam, fuel injected, catalytic converted, water cooled, Engine computer controlled internal combustion engine??? Yeah.. an air motor is cave man simple compared to that.

As to cold climate? Every mode of motorized vehicle has some issue with cold.. what exactly is the bugaboo with compressed air? Frozen air? How's the diesel jelling problem in cold weather? Or maybe frozen gas lines due to water in fuel with gas cars? Or just dead batteries. Hmm how's them batteries in the electric cars gonna like 5 deg winters?

If one WANTS to nit pick problems we can condemn every technology.. every human endeavor. I remain as I started.. compressed air pneumatics are by comparison cave man simple, reliable, and low maintenance. And yeah, I have a decent amount of experience with pneumatic industrial machinery.

Lemme know when every auto mechanic on the planet rejects his air tools.

[TestDrive]

Originally Posted by larryj54

As to cold climate? Every mode of motorized vehicle has some issue with cold.. what exactly is the bugaboo with compressed air? Frozen air?

Frozen water that originated as humidity in the air that was compressed.

[Ryland]

the problem with cold weather and air cars is the same problem as you get with ice forming on the outside of your propane tanks when you run your jet engine, or any kind of torch, or compressed air tool, the expanding air has a cooling affect and the radiator on a compressed air car is there to keep the engine warm as the air can cool it down to -15F and cause it to ice up, also metal starts to act funny when it's that cold, oil thickens and air in the tank condenses and just like how you have to add air to your tires in the winter the pressure in your 12,000psi tank of air will also drop, after all one of the most common ways to compress gases to that kind of pressure is to cool them as a common household 125psi air compressor can't just be turned up or let run longer.

[TestDrive]

Great summary, Ryland.

[larryj54]

Originally Posted by Ryland

the problem with cold weather and air cars is the same problem as you get with ice forming on the outside of your propane tanks when you run your jet engine, or any kind of torch, or compressed air tool, the expanding air has a cooling affect and the radiator on a compressed air car is there to keep the engine warm as the air can cool it down to -15F and cause it to ice up, also metal starts to act funny when it's that cold, oil thickens and air in the tank condenses and just like how you have to add air to your tires in the winter the pressure in your 12,000psi tank of air will also drop, after all one of the most common ways to compress gases to that kind of pressure is to cool them as a common household 125psi air compressor can't just be turned up or let run longer.

Valid critiques all, if we were talking about an all or nothing impositon of a one technology strategy upon all people. Just as solar cells are an excellent power alternative in the desert southwest, but not so great in the sullen gray skies of Puget Sound, so too Compressed air cars are not an all around answer.. but in places where benefits outweigh limitations, I still maintain its a great alternative to the IC car and more easily built out infrastructure wise than any other tech other than electric plug ins; and there you have a treasure trove of downsides to pick at. Cost, weight, environmental nastys of battery chemistry, disposal issues. Yin & yang

Still #1 unassailable benefit to air cars: Scented refills!

[Vwbeamer]

My personal opinion is that the whole air car thing is a scam to get investors. Compressed air is ineffective way to store energy.

Ever use an air grinder? you have to have a 5 hp compressor to run the thing and it burns a lot of energy. A simple hand held electric grinder will do the same work cheaper.

Now i know the pressure is supposed to be a lot higher, around 300 bar. But air compressed is hot air, when air cools it will contract, so pressure is lost as the tank cools.

This would be cool if it's true, but I'm naturally skeptical of this idea.

I could see it being used as regenerative braking. where a cylinder is used to compress sir while braking, and then the air flow is reversed and used to drive the cylinder.