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Full Version: a car that runs on air.
Club smart Car > CsC Community Discussions > Auto Talk
The way the Air Car is propelled is fairly straight forward. There are two tanks of compressed air which turn an almost-conventional piston motor and drive system. The system is said to propel the small van to a top speed of around 105km/h.

Tata says the Air Car stores enough compressed air to offer around 300km worth of motoring. Users will then be able to re-gas the car at certain filling stations that are equipped with special tanks of compressed air, in around three to four minutes for around $2. It will also come with its own generator pack which can be used at home capable of re-gassing the tanks in around four hours.

But you can already buy one with a 1000 mile range in the US! At least that what they claimed would happen by now in 2008.
Real problems with air cars, chiefly the fact that anything an air car can do an electric car can do better and much more efficiently. Assuming you start with electricity to compress the air with, air cars can deliver an efficiency of 50-70% according to wikipedia. I suspect even the lower end of that range is optimistic, I deal with a lot of pneumatic systems and despite its many advantages efficiency is not one of them.
In addition regenerative braking is incredibly easy with electric cars and very difficult with air.
Pipe dreams only, and that's not tobacco in it. Or possibly just an attempt to keep the government grants flowing, that I find easier to believe than a practical air car.
Nothing straightforward about that serpentine belt drive system on the front of it! Can't see any kind of tensioning system and would wonder what the parasitic losses would be with all those pulleys. The range would be limited by the crowds of other people on the roads, not to mention the odd cow (I've lived in Bangalore). One of the most important devices on a vehicle there is a good horn. Sounds like a good system to run a barking mad set of air horns, but move a car?
The aircar will be totally unsuitable for sub zero conditions so I guess it won't be seen north of the Arctic circle, summer or winter.
All these dreamers......

It's an interesting topic to compare compressing air, versus charging a battery.

Unless someone is factoring ino the total carbon footprint, and I do mean the embedded carbon as well.... then this conversation goes nowhere.
If anyone has links to all of that, please post.

'Air car' itself is entirely misleading... it might by nuclear, coal, natural gas, oil or hydro-electric...... maybe wind, maybe solar, but not likely en masse.

But do the dreamers of today start us off in a direction that eventually leads to a breakthrough?

I agree, this one is marketing hype. 'Air car' sounds sexy.... 'it runs on air... and sun power'.... WOOT!
Mike T
All my cars run on money.
and plenty of it wink.gif
Or I guess you could trace it back and back.

runs on money, which
runs on my work, which
runs on food, which
runs on agriculture, which
runs on farm equipment, which
runs on fossil fuel.

Full circle! laugh.gif

In the end, it all comes down to the fact that nothing on Earth works without Carbon. I consider that we Humans are fundamentally just Carbon converters, changing fixed Carbon resources into free forms.
Overall efficiency of an air car is much higher (4 - 5 times) than a car running on petrol or diesel.
True about the efficiency being higher than that of a internal combustion car. Wikipedia thinks the overall efficiency of a gasoline car is 14% vs 50-70% for the air car. (A figure I think is kind of optimistic.) However, that is starting with electricity. Starting with a fossil fuel (unfortunately still the predominant energy source for electricity generation) gives a substantial additional loss. Coal fired plants run around 33% (67% is lost), gas-fired cogeneration up to 50% or marginally higher.
Remember, the "air" part of the concept is only an energy transport and storage mechanism, and batteries are much better at that than compressed air. I have some air tools in the shop and they are great with a hose attached, but there is no way I would take them for field work lugging a storage tank along.
And don't forget the regenerative braking part, that boosts the already-higher efficiency of a battery car far higher yet.
The range is the crucial issue, that 300+ km range from an air car is utterly absurd.
The idea of no toxic battery materials and a far greater charge cycle life is very alluring, but simple physics rules out air for anything but very short range uses. Inside transport perhaps, airports, malls etc. If you want an unproven technology that relies on super-strong materials look at flywheels. Much more promising.
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