Air Engine Car, Can It Be a Real Alternative to EV?

Did you notice the almost complete lack of engineering information in the article?

The article is just a report of happening, what do you expect? It is not a SAE paper. What is significant is that TAta said it has passed technical proof of concept. I used to think this MDI guy is either doing a con job or he does not know his stuff . Now it does Not seem so.

The idea of producing a zero pollution vehicle is commendable.

Many barriers must be overcome with any new technology.

1) Public perception: Is it 'cute' enough and useful enough?

2) Safety: The smaller the air cylinder, the higher the air pressure must be. Therefore adding concerns during an accident, since rupuring the cylinder in any way will cause an air explosion.

3) Power: How fast can it get up to speed and how far can you go? Will the turbo/compressor/generator also supply all the electrical needs?

4) Fuel?: Where to recharge the air pressure since no infrastructure currently exists for accomplishing this.

5) Maintenance: Again, no infrastructure for maintaining the turbo/compressor, etc.

6) Many more barriers.

Getting past all of these barriers is not an easy task when there are already well established and relatively reliable means for accomplishing the same purposes of getting us from here to there?

It many be an interesting idea, but it is not likely to ever get much beyond a concept vehicle.

That said, the engineering that goes into producing a concept vechicle like this also always has spin-offs. For instance, the turbo/compressor. This is a device that could easily be used in other technologies utilizing a constant air pressure source. And the engineering and manufacturing experiences that are gained by producing a device this small are also transferrable into other devices as well.

So all is not lost, only the final product.

Heard about this recently, but the concept has been discussed several times on CR4 and the concensus is it's a non-starter.

If you take a modest petrol tank 5 UKgal, and 30% efficiency, energy at the wheels is ~ 250 MJ. To get the same energy in compressed air at 200 bar (about the same as an oxygen bottle, as high as you'd want to go) and 70% air motor efficiency, volume needed is ~ 3.5 m³. Not on. You've still got to compress the air, probably using mains electric, so it doesn't save any energy.

And if it was ruptured in a smash, it would be worse than a petrol fire.

I also estimate that if the vessel's a sphere (most economical shape for material) it's about 2m dia, 50mm thick and weighs over 4 tonne.

If anybody thinks it's practical, they should produce some figures.

I reproduce my comment in Gizmag below:

IF air tank is capable of 60ksi as Sam Joy said, then theorectical energy capacity of 100 liter tank is about 24 kWh. Assume a good efficiency car which has Wh/km =100, then the range is 240 km, so the idea of air engine car is realistic .

Also, unlike battery, air tank can be recharged almost instantly and has unlimited charge/discharge cycle.

Also,I think it is a lot easier to make a strong compressed air tank than whatever nanotechnology Lithium air battery.

As to the question of what is power source for the compressed air, it is the same for battery . So, Mr Negre is not so much a "geotrouvetout" .

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The key is how high pressure the compressed air tank can go. If it can go as high as 200ksi, as one reader (who has vast experience with compressed tank) said, then you will have enough storage energy . My calculation, at 100 liter at 200 ksi, teoretical stored energy is about 80kwh . Pelton turbine which can work as air engine has 90% efficiency.

Many commentors have wrong idea, air engine advantage is not that air is free or it is polution free. It is that compressed air and air engine can be possible storage and propulsion mean . Of course , the energy must come from some where, just as in the case for EV.

Tank for 200 bar ( CNG tank) used in NGV (natural gas vehicle) is already well proven. Some say it is even safer than normal petrol tank. With 200ksi tank , it is even safer, because it is so tough even a crash cannot rupture it.

The key question is, whether a 100~200 ksi 100 liter size can be practically made?

Also, the fact that Tata said it has passed the technical proof of concept, so the idea of air engine is not so far fetch.

I suspect you are confusing the tensile strength of the air tank material with the pressure of the air stored inside. Maybe Tata is suffering the same confusion?

You got it wrong! Go read the comment from Sam Joy in the Gizmag article.

Tata has thousands of engineers, who is more likely to be confused?

Must you be so gullible? Sam Joy got this wrong, too. (He also misspelled Thiokol.)

Some basic arithmetic on tank design would easily show why.

Can you show the basic arithmatics?

What kind of units are ksi? Do you mean kpsi (thousand pounds per square inch)?

Yes; in structural work it is often abbreviated as ksi.

(I guess it could be called kilopounds/square inch....)

I have been following the air powered car and TATA in particular since about 2006 (see previous threads on CR4 on the subject). When I read this article I considered starting a new thread on CR4 myself, but then decided to have a cup of tea and calmed down a bit.

As you can probably guess my response is less than favorable regarding air-powered cars for many scientifically-valid reasons (see numerous pages of previous threads on CR4 on the subject). I have mentioned the word 'scam' a number of times (with facts and figures to back that up).

Here are some links (including facts and figures) dating back to 2006 (in no particular order)

Link 1

Link 2

Link 3

Link 4

Link 5

Link 6

etc, etc, etc.

Short answer is no. Waste of time and more polluting compared to other technologies including the existing internal combustion.

Please see my reply#19.

This is a joke.

Where does the efficiency of the system go over 100%; because that's the only way this can ever work. That, or Divine intervention is the only way this will ever be practical.

Buy one of these:

Where did you see anyone said or imply over 100% efficiency?

Hi Lyn,

A lot of times, your photos show on my screen as a thin vertical line. What browser do you use? Do you use the CR4 editor Insert/Edit Image button, or do you direct copy and paste?

Me too. Beats me. How's that look?

If I get right on top of the line with my cursor, I can right-click save it as an image. When I open the saved image in a photo-editing program, it's fine.

Hmmm - bicycle tire pump - a laborious process to be sure

Sometimes emotions seem to get the best of us.

As interesting as the concept of an air powered vehicle may seem, the physical necessities required of it would make it impracticible in safety, weight, cost and engineering efforts. All duly commented on within CR4 and within the comments on the linked article.

I can appreciate that there are many things that we may wish for, but not all of them can have the hope of fruition.

pls see my reply #19

Many people commented that air car is not possible on the basis that compressed air energy density is low, about 0.2 MJ/L at 300 bar. But energy density of compressed air is a function of pressure. As I said, at pressure of 60ksi, energy of a 100 L tank is 22kwh, at adiabatic expansion. In actual air engine application, it is not adiabatic, some energy will be absorbed from environment, so energy available will be more.

The key obstacle is whether compressed air tank 100L size can be made to withstand tens of ksi pressure or even higher.

My calculation, a tank , 2 cm wall , 100L size , made of CArbon nanotube composite is about is about 30 kg .

Graphene has even higher tensile strength, 130,000 MPa (!!) vs steel of 500 MPa. So, if graphene composite is available, such tank is possible. A simple linear approximation , 100 cm steel wall can be reduced to less than 1 cm thick using graphene !

Another point, that compressing air is inefficient, that is due to the fact that in ordinary air compression , compression heat loss is not recovered. In dedicated large scale air compression for automotive use , this compression heat will be recovered.

That's is why my conclusion: the possibility for air car is not so far fetch.

this compression heat will be recovered.

Not all will be recovered, there will still be losses, plus there are inefficiently throughout the system.

When you get down to it and go beyond gizmo or wherever you picked up the article. it would not only be far fetched, but unlikely as well.

So are you saying your and Tata's claims are based on the use of exotic materials which might not appear for many years, if ever? You might as well say that nuclear reactors small enough to power a car will be built, and we'll never need to refuel.

And even if these materials are developed, do you think it's likely the drivers will install in their garage a compressor capable of 60 ksi = 4000 bar?

He's already made up his mind. Don't confuse him with the facts.

Please argue with fact, it does add value to discussion with statement like , he is confused, he is gullable etc...

I would love to hear different viewpoint based on fact and figure.

I am saying, the fact that Tata said it has passed technical proof of concept is very significant. I am sure Tata's automotive engineers experience is no less than any others.

Whether it is 4000 bar or 100 bar, it is just relative. 10 odd years ago , if you heard 1 terabyte memory , gigahert processing power in your shirt pocket is ludicrous.

Anyway, one reader who work with compressed tank already said 60ksi is quite standard.

What some people redicule in 2006 may become reality soon .

"Whether it is 4000 bar or 100 bar, it is just relative. 10 odd years ago , if you heard 1 terabyte memory , gigahert processing power in your shirt pocket is ludicrous."

People have been building compressed air powered vehicles for many years. Some technological advancements, such as stronger/lighter materials, offer improvements in the implementation, but the physics haven't changed. Compressing air (or any gas) to use as a power source is inefficient.