How Do the Weight of Batteries Compare to Tanks in Air-Powered Cars?

[wolram]

http://www.popularmechanics.com/automotive/new_cars/4217016.html

India’s largest automaker is set to start producing the world’s first commercial air-powered vehicle. The Air Car, developed by ex-Formula One engineer Guy Nègre for Luxembourg-based MDI, uses compressed air, as opposed to the gas-and-oxygen explosions of internal-combustion models, to push its engine’s pistons. Some 6000 zero-emissions Air Cars are scheduled to hit Indian streets in August of 2008.

 

[russ_watters]

Of course they're real - they just aren't real good.

We've had threads on this particular haox before, though (your link is 10 months old): Their performance claims are, quite simply, a lie. https://www.physicsforums.com/showthread.php?t=172267&highlight=aircar

[edit] Hey! you posted in that thread!

 

[Pablo70]

You can go to the back of the waiting list then ;-)

Hello,
The citycat air car is coming to North America in 2010, here's the info: citycataircar.com. Tata Motors will be producing the economy model Onecat for the India market in 2009/2010, here's the info: onecataircar.com.
I made these fans sites with the information that I got from the 2008 New York Auto Show. All the other information on the internet is based on the 2006 prototype models with the 90 mile range on air only (or worse, the 2002 prototype that had a range of 7.2 kms/4.3 miles).

This has been a big problem with the information on the Internet regarding the Compressed Air Vehicles from MDI.lu (France).

 

[wolram]

Confused, are they a hoax , are they exaggerating, have they been independently road tested.

Yes Russ, i read an article in a car mag with no performance figures, just a range of models, it just seemed to me the mag would not bother with them if they were totally
bogus.

 

[Mech_Engineer]

Compressed air just isn't a very good way to store energy. First of all, compressing the air is an inefficient proposition, so you lose a lot of energy just in making the compressed gas. Secondly, it's difficult to store a lot of energy in a compressed gas tank without gigantic pressures or huge volumes.

The Air Car we're talking about here for example, uses a 340 liter tank at 4350 psi. That equates to about 10.1 MJ of stored energy, which is equivalent to 0.3 liters of gasoline. I have trouble believing you can get very far on that much energy in a car.

Even assuming the vehicle only weighs 1000lb (453 kg) accelerating it to 60mph would take a bare minimum of 0.16 MJ (not taking into account things like engine and transmission efficiency). That's over 1% of the vehicle's total energy stored, in one acceleration to 60 mph, not including ANY efficiencies or wind resistance.

 

[Pablo70]

I'll be visiting them in France this summer (or sooner)

Hello,
I have plans to visit them in France asap, once I confirm that Guy will be available for interviews and I can drive one of the prototypes around. CNN, BBC, Discovery/Science channel drove these vehicles and reported on their ability to travel 90 miles on air only, so they were willing to put their reputations on MDI's "claims".

However, if the cars are not what they claim to be, I will lead/follow the charge to tar-and-feather them.

Mind you, if they can do even half of what they claim, I will be very happy, and no longer polite to people who say that it's not possible or a scam.

 

[Mech_Engineer]

I'm not saying its a scam at all, I'm sure the cars drive and run off of compressed air.

I personally just don't think compressed air is a very good primary energy source for use in a vehicle.

 

[wolram]

I found this video, i am drawn to believe some of the claims

http://www.youtube.com/watch?v=QmqpGZv0YT4&feature=related

 

[Algr]

I guess the real comparison is with batteries and electric motors. Air tools are stronger then battery powered ones, but the tanks plug into the wall, and are ridiculously huge in comparison to a drill battery. That is the real problem with an air car - miniaturizing the tank.

I know that compressing air creates a lot of waste heat - but so does charging a battery. Which is more efficient?

 

[wolram]

A battery powered car has to overcome the weight of batteries before it does any useful work, the same goes for air powered cars, so how does the weight of batteries compare to the tanks? as i see it air powered cars are all about saving weight ,so as long as the tanks can fit into the car package what the heck, i can not envision an air car towing a caravan far though.