Talk:Compressed air car

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MDI true or not[edit]


Can MDI be a internet super-hoax? Is There really a engineer named Guy Negrée and a enterprise named MDI? How many "new" external references about it can we find? 12:20, 23 June 2006 (UTC)~

I already checked it with Tata Motors (sent an e-mail); Its definitly not a hoax. KVDP (talk) 15:01, 1 February 2008 (UTC)
It's more than an internet super-hoax, it's a real life super-mega hoax. Guy Negre does exist, but the engineering behind the air car does not exist. Guy Negre was never an F1 engineer, he is a con artist. (talk) 19:43, 16 August 2008 (UTC)

I have three years of mechanical engineering, and even though I did not finish the career, I can easily tell you that this car is a total HOAX. I doubt that a car could possibly go more than two or maybe three blocks on compressed air. But the real killer is the efficiency. Batteries can reach maybe 80% efficiency, and the other 20% is wasted as heat. With compressed air, I seriously doubt you can reach even 15% efficiency. The average efficiency of a water pump is 33% as best, the rest is lost as heat. With compressed air, loses are far much higher since compressing the air generates enormous amounts of heat. Gambori, Saturday November 8, 2008. —Preceding unsigned comment added by Gambori (talkcontribs) 20:54, 8 November 2008 (UTC)

If you look at the energy required to "charge" the cars, it is equivalent to 1/3 of a litre of petrol - in energy equivalency. Therefore it does not seem possible that these cars can travel more than probably 3miles or so. —Preceding unsigned comment added by (talk) 19:41, 9 August 2009 (UTC)

The MDI version is being evaluated by KLM and Air France. Perhaps when they're done, theere will finally be a more reliable source of information than MDI itself about the vehicles.
According to Tony Burden, Dept of Mechanics at the Royal Institute of Technology in Stockholm Sweden, who's an expert in thermodynamics, Mr Nègre's claims of efficiency exceeds even the theoretical maximum possible. [1] This smells of hoax a long way. (talk) 15:02, 18 January 2011 (UTC)

V (talk) 15:31, 17 August 2009 (UTC The airpods that were supposed to be tested by Air France and KLM Engineering starting in Spring 2009 have not yet been delivered to those companies. There was a press conference, but after the press conference the two demo vehicles went back to MDI.

whomever published this is a fool!! what a waste of time putting this together. — Preceding unsigned comment added by (talk) 01:25, 3 April 2012 (UTC)


There is an Australian television series "Beyond Tomorrow", which examine objects and concepts of the future. One of its episodes featured the Air Car, and the link to the episode can be found at: [1]

There is an official website of the vehicle too, at: [2]

It is certainly not a hoax.

I agree. If something appears on TV and has a website, it cannot be a hoax. —Preceding unsigned comment added by (talk) 02:32, 9 July 2008 (UTC)

I agree, the thing exists and has a range of at least 7 km. However, whether it ever makes money for its investors is another matter entirely. So, to that extent it many be a financial scam. Greglocock 21:06, 9 November 2006 (UTC)
Theoretically it can go 7km on flat ground, but it only has to overcome friction, lets see it get up a hill. I could probably get a 9-volt Duracell battery to send a toy 7km if the ground were smooth. 00:07, 22 March 2007 (UTC)
Drag is the main resisting force at higher speeds. (talk) 19:44, 16 August 2008 (UTC)
Pretty much, as anyone who has pulled or pushed a railroad car on a bit of flat track can testify. (talk) 08:37, 25 April 2008 (UTC)

Yes, it IS a big hoax to steal investment money.

I have been in Freiburg to a presentation personally and the could not even answer the simple question on what the Carnot efficiency is. Every gas motor has this. I have studied physics.

Second: If it is a good idea, it would be sufficient to simply patent the principle and the motor would be used not only in cars but everywhere! Is is complete garbage to develop "a new car" around it. Existent car manufacturers will do this much more cost-effectively.

And you cannot manufacture anything without having the principle.

Third: Here, they never said where the energy came from!! As I was getting close to the "meat" they said - well the motor is not ready yet. They said this in France for years before! Forget it please! It is not a hoax, it is a fraud!

Andreas, Freiburg

Are you talking about the efficiency as mentioned here ? That seems to deal with temperatures rather than pressures. Are you sure it's directly relavant? And what kind of people gave the presentation? Marketing?
Your second point is a good one. Existing car manufacturers just love throwing away their own research and investing in unproven technologies</sarcasm>.
It could still be a hoax or fraud, but I find your arguments perhaps even less convincing than theirs. Either way, this talk page is not meant for such discussions. V 15:21, 23 February 2007 (UTC)
Carnot efficiency is very relevant. It is the fundamental way of calculating the efficiency of any energy process involving the expansion of gases Greglocock 23:22, 23 February 2007 (UTC)
Okay. V 00:11, 24 February 2007 (UTC)

I think it's safe to say there's a big grey area between "successful business" and "hoax". Likewise, for an engineer, there's a big difference between "one apparently working model" and "viable manufacturing plan".

I think both sides need to take into account the in-between possibility - that, while compressed air may be a workable method for small vehicle energy storage, these guys may be well-intentioned but opinionated coots, true believers in their own product, who may NOT create a successful business, or even fully understand their own invention. It certainly wouldn't be the first time... (talk) 08:37, 25 April 2008 (UTC)

--- Regarding the Australian show Beyond Tomorrow: the host claims the vehicle has a range of no less than 4300 miles. BBC promised only 200 miles for HDI's very same car, and a study demonstrated it was only 42 miles (see reference in Disadvantages section). This is all over the map. I'm certain this is no hoax, but the specs seem fairly suspicious. — Stimpy talk 01:18, 17 July 2008 (UTC)

Bear in mind that the original ridiculous claims for range on air-power alone have been modified, and that the current claims, while still unproven, are substantially less. Using hysterical TV programs as a source is dubious at best, particularly since the manufacturers own websites are far more conservative. At some point we are going to have to get to grips with the appalling passive safety of these vehicles, but I suppose the fanboys will destroy any rational discussion of that. Whoops, yes they did. It actually doesn't matter, these aircars will never be anything more than a curiousity. Greg Locock (talk) 12:26, 17 July 2008 (UTC)
MDI has updated their web site. Still long on conceptual drawings and speculative specs ( I think it's pretty clear this is a hoax. The SmartCar, at 1800 lbs. with a 1-liter engine, gets around 45 mpg, and could go 20 miles on 1.7 liters of gasoline on the highway; they're claiming 180 km (108 miles) on the equivalent energy in compressed air in a 1200-lb. vehicle, in city driving. If the SmartCar has 25% efficiency, they're positing over 100% efficiency using a proven low-efficiency energy storage medium. More to the point, however, they're now stating that the highway vehicle would be a hybrid, and would achieve 1500 kilometers (900 miles) on 1.8 liters of gasoline. This is clearly perpetual motion country. Wikidondi (talk) 15:34, 18 December 2008 (UTC)wikidondi

Removed from Advantages[edit]

The sentence of the first point "Refueling can be done at home using an air compressor [1]..." is untrue and the website referred to does not claim this. Air cars require pressures of 4,500 psi, a home compressor has a maximum pressure of around 125psi. The car supposedly has a compressor built in, which can be run from mains power (this is claimed by the cited article). 73BlackWhite9 (talk) 20:41, 22 February 2009 (UTC)

I removed this from advantages as nonsensical:

but since no production version of a compressed air powered car is available then any number could be used.

why is this an advantage? Anyone heard of toll roads?

  • Governments that impose fuel taxes will be unable to do so because air is free. —Preceding unsigned comment added by (talk) 21:37, 21 February 2008 (UTC)
Well, I suppose the editor was suggesting that a company that has been promising to introduce this innovative technology for 10 years, at an amazingly low price, and yet has conspicuously failed to justify ANY of their performance claims, and that relies on investors for its income, may not be a particularly accurate source for estimated prices. It is hard to see how a vehicle can be sold for around $5000, when for example most electric cars with a reaonable range have prices of $15000 and upwards, excluding batteries. The inability of governments to tax air cars will merely stretch their ingenuity a very little, I agree. Greg Locock (talk) 22:15, 21 February 2008 (UTC)

Not only toll roads, but tax per mile (regular mandatory ododmeter readings)for road use as an alternative road tax. Road construction and maintenance benefits whatever type of vehicle you are driving. The "air car" in pure form is a scientific fraud. The fair thing to do is to have the courage to call it for what it is. From a related wiki article ( the potential energy in a 5 liter/200bar bottle is .16KWH The midi air car has 137 liters at 275 bar (4000psi). 137÷5×275÷200×0.16kwh is about 6KWH. From this electric car converter a purely electric car uses about .2 KWH per mile. If the air car were perfect it would go about 6÷0.2= 30 miles. In the only real public test of the midi car in Paris, it went a little over 4 miles (7km). Basic physics isn't going to change. This compressed air moped with smaller tanks has the same range (talk) 02:38, 7 June 2008 (UTC)David

recent news[edit]

Tata Motors and MDI signed an agreement[3] very recently. Perhaps a place can be found for it in the article. V 02:15, 12 February 2007 (UTC)

MDI Air car[edit]

Should this article be about all air cars and not just the ones from this particular company? --Gbleem 00:37, 3 June 2007 (UTC)

I think it should. At present this article reads like an advertisement for MDI and its products. -- Johnfos 05:24, 25 June 2007 (UTC)
Is Air car a generic term, for what I would be tempted to rename compressed-air car? It seems to me that MDI are using it as a registered name. Frankly, the whole article needs a rewrite anyway, it is far too credulous. Greglocock 05:37, 25 June 2007 (UTC)
Yes, I've added Cleanup and Rewrite tags. -- Johnfos 05:49, 25 June 2007 (UTC)

Just from 20 minutes of research into MDI, MDI is a huge fraud. They are simply here to steal investors money. All their claims are outrageous lies. —Preceding unsigned comment added by (talk) 02:52, 13 January 2009 (UTC)

This article seems to have suffered from editors whose contention with MDI is damaging the impartiality of the article. The observation about the parallel with torpedo technology is gratuitous. -Schlanger (talk) 18:57, 18 December 2014 (UTC)

how so? Torpedoes were using compressed air engines in the late Victorian era, why is that not relevant? Greglocock (talk) 22:41, 18 December 2014 (UTC)
More to the point, torpedoes were using (as MDI are describing) compressed air engines with fuel-fired heaters or reheaters. Andy Dingley (talk) 23:14, 18 December 2014 (UTC)


IMPORTANT NOTICE! I feel that it is only fair that I post this amendment to the matter that I had posted earlier, after working on the problem for some time, I have come to the following conclusion. The MDI air car is NOT a scam. It does work, every bit of data supplied at the MDI air car web-site IS TRUE. The car does work as stated. A 320 litre tank filled with compressed air at 4200 psi (300 bars) WILL power the car at whatever speed is desired for 7 – 8 Hours. The tank CAN be refilled at home using a 4KW compressor in 3 – 4 hours. The end conclusion is that the car is no more dangerous than carrying around a couple of filled scuba tanks in the boot! DDjames 00:38, 20 October 2007 (UTC)

Sorry, you are wrong. The air car does not do what they claim. —Preceding unsigned comment added by (talk) 19:47, 16 August 2008 (UTC)

Rollout timing[edit]

there is NO WAY "early 2008" is reality should be struck

Tata deal for real?[edit]

One of the most seemingly convincing claims for MDI is that they have a deal with Tata Motors. This is repeated endlessly across the web. Well, I was just on the Tata site, and did a search on compressed air. The site has two articles about the use of compressed air in the factories that manufacture ICE- driven cars, but no mention of a current or prospective compressed air-driven car.

This tends to confirm the view, stated elsewhere on this discussion page, that the compressed air car has no potential to be a practical vehicle, due to the low energy density of compressed air, which is limited by the laws of physics, but is simply a way to make money by selling manufacturing licenses. —Preceding unsigned comment added by (talk) 02:17, 16 September 2008 (UTC)

Didn't look very hard did you? Greg Locock (talk) 04:05, 16 September 2008 (UTC)

Two years have passed since that original announcement. The Tata air car was supposed to be out in 2008. Now all Tata talks about is the Nano. Looks to me like MDI's air car failed to make the grade .. even in India. "No its not dead, its resting."ToolmakerSteve (talk) 06:49, 15 May 2009 (UTC)

Took out the part about a deal between Tata and MDI[edit]

I do not believe such a deal exists. I could find no reference to it on the Tata site. The so called "reference" provided simply pointed to another Wiki page, which had a reference which pointed to a third Wiki page, all presumably written by the same shill for MDI.

You can find claims all over the web citing this relationship, but no reliable sources attested by Tata.

I do not doubt that MDI will restore the claim, but the only way to avoid an editing war is to point to a press release on Tata's site announcing the original deal, and if that deal is more than a year old, announcing recent progress. —Preceding unsigned comment added by (talk) 02:28, 16 September 2008 (UTC)


Here is the definition from the article. "Vaporware is a somewhat derogatory term used to describe a software or hardware product that is announced by a developer well in advance of release, but which then fails to emerge after having well exceeded the period of development time that was initially claimed ". The MDI Aircar in particular has been gathering money from licensees for almost 10 years, promising to be in production in two years time continuously over that period. No other air car has made it into production either. NONE of these cars have been tested independently to verify the ridiculous performance claims. If you do a google search for aircar and vaporware you get a reasonable number of hits. Greg Locock (talk) 21:48, 4 October 2008 (UTC)

I have reverted this, as no sources for a characterization of air cars as "vaporware" were supplied. In the absence of those, that characterization seems to be original research -- or a really bad pun. (talk) 16:07, 19 October 2008 (UTC)
I think there is a wiki guideline that could be summarised as 'don't be obtuse'. If something meets a definition then calling it by that word is not an unreasonable thing to do. Failing that, here's some of the many many hits, ignoring reader's comments and forums, ie editorial only
Greg Locock (talk) 23:55, 19 October 2008 (UTC)
Seems the IEEE agrees Greglocock (talk) 01:03, 23 November 2009 (UTC)
Perfect description! However I believe "Vaporware" may be giving them too much credit, that implies that there is actually some intent to create it. In the case of the air car, it is a complete hoax. —Preceding unsigned comment added by (talk) 04:00, 14 October 2009 (UTC)

Article discussion[edit]

Emissions Dubious tag[edit]

Can somebody find a good reference for the statement that it is more efficient to burn fuel in a power station, generate electricity, transmit it to a pump, and compress air in a tank, than it is to fuel a car directly? Given that the power station could be burning brown coal (etc) Greg Locock (talk) 07:49, 14 January 2008 (UTC)

For instance I found this (unreferenced) "Electricity from fossil fuels burned by public utilities in the USA in 2005 averaged 33.4% efficiency,". The efficiency of the power grid is well known. The efficiency of the air pressurisation process is easily calculable. I shan't put this into the article since apparently multiplying 3 numbers together is OR. SO... unless someone can find a good reference that supports the claim in the article, out she goes. Lest anyone is under any other impression, I fully acknowledge that I think MDI is primarily a financial construct and will never make money for its licensees or make a significant contribution to reducing emissions. Greg Locock (talk) 21:51, 23 January 2008 (UTC)
In any case, for an encyclopedia, there sure is a lot of time spent DEFENDING this technology (references or not), rather than just stating the facts, and leaving it alone. Youdontsmellbad (talk) 05:56, 20 April 2008 (UTC)


Is the PHEV link messed up? --Shanedidona 01:43, 14 August 2006 (UTC)


I've added the section comparison. Although my statements can easily be proven, I havn't found a reference. --Theosch 08:52, 26 January 2007 (UTC)

Cleanup required[edit]

The sentence about Energine: The domain exists but it isn't being served and there is nothing in the Google cache except possibly a Flash video. I suggest removing this sentence a few weeks from now if the site is still down. --Theosch 08:55, 26 January 2007 (UTC)

Merger proposal[edit]

Merge with Compressed-air vehicle?

I suggest this page is merged with the very similar page, Compressed Air Car -- Tones22 (talk) 17:18, 20 March 2008 (UTC)

AGREE. The two articles are very similar -- actually the Compressed-air vehicle article is superior as it reads less like an advert. (talk) 12:59, 31 May 2008 (UTC)
DISAGREE - the vehicles article covers all the various types of vehicle, this one is just for cars. Remove the advert stuff from this article instead. Greg Locock (talk) 23:44, 31 May 2008 (UTC)
You can see compressed air vehicle and improve it. --Mac 13:12, 24 October 2007 (UTC)
Both articles cover very much the same area. In fact, the advantages & disadvantages are for the most part copied verbatim. I suggest the articles be merged and a subsection be added with additional information on compressed-air passenger vehicles. Also, I agree that this article reads like an ad. I have made some changed to the pros & cons, but the entire article is pretty much a mess. — Stimpy talk 00:54, 17 July 2008 (UTC)

I DISAGREE GREATLY. Vehicles refers to any type of vehicle like boats, planes, buses, trains etc. Infact there is already an AIR-BUS in production so definately cannot merge this. —Preceding unsigned comment added by Mercury888 (talkcontribs) 14:19, 17 July 2008 (UTC)

Emission Free? - Cleaned Up[edit]

Regarding - "This confusion arises because hydrogen, electricity, and compressed air, are all energy transfer methods, not actual sources of energy." Electricity is energy, hydrogen can produce energy through combustion or by other means such as a fuel cell, and compressed air has a great deal of kinetic energy; however, it is simply incorrect to call them energy transfer methods. I have therefore deleted the offending sentence. --Darkdaedra 04:20, 20 March 2007 (UTC)

No, you are wrong in this context. I have restored the offending sentence. Greglocock 04:31, 20 March 2007 (UTC)

My big question would be: What is the amount of energy that can realistically be stored using compressed air? Petrol and diesel have a high energy density, so you only need a 50 liter tank for the car to have a useful range. With electrical cars, the problem is that batteries have a low energy density, so you need hundreds of kilos of batteries to achieve sufficient range. It is hard to imagine that you could compress enough air into a 50 or 100 liter barrel to power a car for a significant distance. What kind of pressure would be required to reach an energy content equivalent with 50 liters of petrol?

Slightly hard to work out, but if we assume that all the processes in the air car are 100% efficient (they aren't, by a long chalk) and that a petrol car is about 15% efficient, which is about right, then the equation in Compressed air energy storage implies that the tanks would have to be about 1370 litres, or about six 44 gallon drums!!! That's pretty funny, thanks for asking a good question. Greglocock 04:32, 21 March 2007 (UTC)

The amount of energy that gets one to their place of work constitutes a 'useful range'. You haven't addressed the weight of the vehicle, the driving profile (i.e., SAE, etc) nor aerodynamic drag (CDa) in your calculations. (talk) 22:44, 13 February 2008 (UTC)
And yet I answered the question that was asked. Read for comprehension next time. Greg Locock (talk) 01:14, 14 February 2008 (UTC)

cool stuff[edit]

curiousity :o) if the air is already compressed send it out of something like a water sprinkler? why drive a piston and a crank shaft?

A piston and crankshaft is more efficient - you get more of the energy back if you expand it via a piston and crankshaft. Even modern jet engines are not as efficient as a normal diesel engine, largely because of this. Greglocock 11:19, 25 March 2007 (UTC)

you loose half of the energy due to the expansion in the wrong direction, the fun is in being able to make things rotate, not make things translate. there is no "back" here, you are not driving another cylinder with this expansion in anyway like a car, as i see it... so are you saying putting 2 sticks to move something round is better than applying a continuous torque at it's tip?

The problem is the efficiency of the expansion process. Turbines and so on are unwieldy if you need high expansion ratios, that is ratio of peak pressure to exhaust pressure. There's no doubt that a turbine is a neater solution than a piston and crank, and for small expansion ratios they are the preferred option. Greglocock 00:17, 22 April 2007 (UTC)

this specific case though is as good as a jet of air being pushed out? use it to drive a piston or rotate a wheel.... doesnt matter, that is specifically what the compressed air is for. so you already have a compressed air tank, why not put a tweakable nozzle and jet it out?

The Rotary Pulse Jet describes an engine very similar to what you had in mind. It supplies precompressed air at a pressure of 125 psi and fuel ( either gas or petrol), to the fully sealable combustion chambers at the periphery of a rotor, through a rotary union and then ignites the mixture, a valve to a CDN is then opened allowing the high pressure gases of combustion to exit at high velocity, spinning the rotor around. A small belt driven compressor replenishes the air as it is used, thus the engine can run, for as long as there is fuel in the tank at speeds and for distances comparable with the IC piston engine. Can this description be included in the article under future developments or external links?DDjames 06:06, 13 September 2007 (UTC)

There's a limit to the expansion ratio a nozzle can handle - as the gas speeds up it approaches the speed of sound, shock waves form, and the nozzle chokes. Off hand I seem to remmeber an expansion ratio of two or so is achievable using air exhausting at STP. Greglocock 22:52, 22 April 2007 (UTC)

Some research has been done with scroll expanders. A paper from the University of Southern Illinois said they reached high efficiency at relatively low pressure differences (in an Organic Rankine cycle). פשוט pashute ♫ (talk) 17:52, 13 March 2011 (UTC)


Where are the safety reports for the vehicle? 30 MPa (4500 psi) is no laughing matter. Getting hit at 100km/h would probably cause some pretty intense air to expel from the tank if punctured. Probably safer than a propane tank leaking by a exposed flame... but if one of these tanks even gets a small hole, the pressure would probably be able to cut a hole in someone. Would the material mushroom out, the tank explode, a puncture slice through things, a burst under the car flip/launch the vehicle? - Jasonlouie 17:39, 16 April 2007 (UTC)

It has indeed been shown that a tank of compressed air, when released all at once, has enough energy to take it through a brick wall, and still have enough energy to cause a significant dent in metal. Shadowedmist 03:53, 27 May 2007 (UTC)
A 1500psi release (without combustion) can obliterate an entire room and collapse the ceiling and floor. This car uses a 4500psi tank. The driver of this car has a death wish. -- 07:08, 31 May 2007 (UTC)
They mentioned on the Beyond Tomorrow video that carbon fiber tanks split but do not release shrapnel and are therefore safer than aluminum tanks. --Gbleem 00:36, 3 June 2007 (UTC)
Even though the material does not release shrapnel the force of the air being released would still be much more lethal than hitting another type of fuel such as battery cells, petroleum gas, or even propane, (minus the heat source to ignite). Even on Mythbusters a 3000 psi Oxygen tank smashed through a brick wall and nearly a second brick wall. Unless there are significant safety measures that can prevent this, it will never meet safety standards to be on the road. -- Jasonlouie (talk) 05:59, 20 March 2008 (UTC)

pro IC POV ??[edit]

I'm tempted to put a POV tag on this article, since the last time I visited this page, the section on the comparative green house gas emissions of air cars and IC engines has been rewritten; I presume by IC adherents. I believe that the fact that 78% of French electricity in France is generated by nuclear means, would be a significant factor in reducing total green house gas emissions if the air car was widely adopted in France. The French could expand her nuclear power production to total replace the need to burn fossil fuels. You might dislike nuclear power and there are disadvantages to its use ( you might decide you prefer green house gases to radioactice waste), but to just delete this section smacks o dishonsety.Koonan the almost civilised 11:33, 27 June 2007 (UTC)

I'd stick a POV tag on it anyway, since it reads like an ad. But to answer your question -why would the emissions status of a very small market, globally, be considered significant? The marginal electricity used, even in France, (that is, the extra electricity generated specifically for this application) is likely to be fossil fuelled. Greglocock 12:32, 27 June 2007 (UTC)
Actually with the French propensity for energy security, I'd suspect that they'd build more reactors. However that point could be made rather than just ignore the fact that emissions could be reduced. Yes France is a special case, but this is the market in which context MDI is designing for, what would make sense for this market, high "clean" electricity production, and its train network that mitigates against the need for long distance car journeys means that the aircar could be viable in this market. To highlight the point that the aircar would only be viable in such special circumstances could actually be a used as a put down. As to the significance of reducing greenhouse gases in a small market, every little reduction in overall emissions helps. POV wise I must admit that I'd like this project to come to fruition and work, even if just in niche markets, however I'm not going to hold my breath, nor will I be surprised if the whole project ends in failure. What I really don't understand is what seems to be the active dislike that the project seems to inspire in some editors.Koonan the almost civilised 14:26, 27 June 2007 (UTC)
Active dislike? Yes, I actively dislike articles that support projects that stink of investor-manipulation, based on an idea that cannot live up to the hype. Predicting a 200km range on the basis of one vehicle that got to 7 km is absurd. Since the licenses have been sold worldwide I see no reason to limit analysis of emissions to France.Greglocock 23:01, 27 June 2007 (UTC)
I've just stumbled into this page, and my response is also "active dislike". This article is based on unsubstantiated claims by one self-interested party. Is "wishful thinking" enough justification to be in Wikipedia? NO. There appears to be a fundamental problem of density of energy storage; I'd like to see a reference to some comparison with batteries and with H2 fuel cells. Also there is a serious problem of the INEFFICIENCY of converting electricity to compressed air, as mentioned by an environmentalist in [1], though I haven't seen a reference with numbers yet. So the "active dislike" comes from not wishing to join in this unsubstantiated self-delusion. If there is a reference that can prove otherwise, that would be great, but without that...ToolmakerSteve (talk) 06:03, 15 May 2009 (UTC)

Generic Air Car Rewrite[edit]

It appears, from the bit and pieces that I've seen, that there are two possibilities for air-powered cars. Therefore, in rewriting this article, it can start out in a much more generic fashion, with more details following, specific to each kind of technology.

The first kind is MDI's CAT technology. Developed by Guy, in Nice, France. We've seen some prototypes, and heard that the Indian car maker Tata intends to start making some.

The second kind, taking up half of this Beyond Tomorrow clip, comes from Melbourne, Australia, and was developed by Angelo Di Pietro. A Google search tells me that the company EngineAir R&D is running with this idea. From the video clip, and the website (and other places), there's a lot of info to fill out this article with info on this 2nd type of compressed-air technology. Especially, discussion of how the rotary engine works, how it's different from an IC engine or from MDI's engine, and how wear & tear aren't as much issues with this engine.

Now, Angelo's rotary engine prototype is a trolley (small industrial truck, similar to a forklift) as opposed to something that looks like a production car, but it still looks like a possible way of using compressed-air innovations to operate future automobiles. Doran Routhe 05:39, 15 July 2007 (UTC) DDjames 07:21, 13 September 2007 (UTC)

I agree That this idea seems feasible but...[edit]

I do not know much about engineering so I would have needed extensive help. I had a similar idea but my idea was to use an electric motor to get up to speed and for slower speeds. My idea was to have an air intake behind the front grille and once the car generated enough wind from its speed it would kick in the compressed air tank, and would then work similar to the non IC engine. Filling the compressed air tanks from the front air intake, I believe that with the proper sub method this would not only keep the air tank full but the turbine in the engine might also keep the battery charged up.

I welcome your thoughts. If you believe my idea is utter tripe say so politely. On the other hand if you think it has potential spread it around.

--Ghaulx (talk) 03:41, 26 January 2008 (UTC)

Sadly that will not work. That is, it will always take more power to force the air into the tank, than you will get from the air to propel the vehicle. The basic reason is known as 2LOT. Greg Locock (talk) 05:31, 26 January 2008 (UTC)
"My idea was..." Believe it or not, this isn't a forum. There are green/alternative energy sites that are the appropriate place to discuss such ideas.ToolmakerSteve (talk) 06:07, 15 May 2009 (UTC)

inefficiently in advantages?[edit]

Seems to me efficiently fits better. "There is already infrastructure in place for creating massive amounts of compressed air inefficiently" —Preceding unsigned comment added by (talk) 06:27, 26 February 2008 (UTC) vs. mdi[edit]

this is a copy from Griminis talk page
Please, visit, in the home you will find an important news where this point catches on: '...This being said any affirmation of fraud can be criminal and constitutes a serious fault of the truth of which the viability is being studied by our lawyers at this moment.'.

I think this is not the place for this discussion. User:Grimini 29 February 2008 (Talk | contribs)

I agree wikipedia is not the place to discus if the accusations are true or not. But mentioning that MDI accuses Celades is not the same as saying the accusations are true. Instead of removing the reference to the accusation, you could've added something like:
"In response to the statements made by MDI, a notice has appeared on the AirCar website disputing MDI's claims."
Next time, use the talk page of the article.V (talk) 17:35, 1 March 2008 (UTC)
That link is currently broken, try this one. Grimini, you have not explained why that sourced information should not appear on this article. Until you do so I will reinsert it. Greg Locock (talk) 03:35, 9 March 2008 (UTC)
I believe that it is only in the interest of fairness that this dispute be mentioned in the article, though only by a sentence or so. I have inserted the statement that the two firms are locked in a bitter dispute. I did add sources referring to both sides of the dispute. If anyone cares to look further into the particular nature of the dispute then they can view the links. Piercetp (talk) 20:13, 26 July 2008 (UTC)



  • Compressed air not subject to fuel tax at present (one taxing method would apply also to electric cars by taxing the electricity used for compression or charging).


  • Governments would either lose tax income or have to adapt their taxation strategies.

Discuss. -- (talk) 12:06, 18 June 2008 (UTC)

the government could tax stations that provides the quick 3 minute fillup. Therefore the stations would charge consumers a bit more for compressing the air. —Preceding unsigned comment added by Mercury888 (talkcontribs) 11:52, 9 July 2008 (UTC)

These are not inherent pros/cons of the technology, so I don't think relevant to this article.ToolmakerSteve (talk) 06:10, 15 May 2009 (UTC)


see WP:DEADREF - the wayback machine is an acceptable source for a dead webpage. The link in question is [4]. Obviously there is no practical use for a car with a range of 7.22 km, therefore all we need is a reliable source for a measured range of more than 7.22 km. Otherwise it remains as a gross disadvantage.Greg Locock (talk) 12:15, 14 July 2008 (UTC)

The efcf papers are largely by Dr. Ulf Bossel (Ph.D. from UC Berkeley, Dipl. Ing. from ETH Zurich). Not a student. Greg Locock (talk) 02:50, 15 July 2008 (UTC)

Fuel assisted air cars[edit]

Many of the exaggerated performance claims that are being made assume that some fuel is being burnt in the engine. Surely this no longer qualifies them as pure air cars, and renders much of the wittering about emissions free at the tailpipe etc irrelevant. So I think this article should clarify exactly what claims are made for pure compressed air cars, and those which might be described as internal combustion engine/pneumatic hybrids. Any objections? Greg Locock (talk) 23:10, 15 July 2008 (UTC)

an obvious disadvantage compared to the electric car[edit]

is that electricity is an all-use energy nowadays. you power your stereo, your lights, anything. I think that is an obvious extra disadvantage as the electric car wouldn't need extra power sources. I guess there are may even be sources supporting it to be included in the article. --Leladax (talk) 14:54, 22 July 2008 (UTC)

Um, no. Unless you believe an electric car is somehow plugged in WHILE you are driving. An electric car uses a battery to store power; an air car uses compressed air. Both cars plug-in while parked, in order to re-charge their form of storage. But more importantly, WE AREN'T SUPPOSED TO BE DOING ORIGINAL RESEARCH HERE: anything you think might be worth saying, GO FIND SOME RELIABLE SOURCE AND QUOTE IT!!! Hint: If you can't find such a source, that should be a clue.ToolmakerSteve (talk) 06:15, 15 May 2009 (UTC)


"The rate of self-discharge is very low opposed to batteries that deplete their charge slowly over time. Therefore, the vehicle may be left unused for longer periods of time than electric cars."

This directly contradicts the fact that air is heated when it is compressed, and will quickly cool down, losing a significant amount of energy in a matter of hours.

Also, "Lower initial cost than battery electric vehicles when mass produced. One estimate is €3,000 less." Is completely rediculous. Anyone who's layed up carbon fiber knows how expensive and labor intensive it is. (talk) 19:53, 16 August 2008 (UTC)


The article uses both Euros and Dollars. It should be more consistent and only use one. I'd recommend Dollars because the car market is larger in America than it is in Europe. Plus this is an English article and the US and UK more prominently use the English language than the EU countries, but neither use the Euro. (talk) 15:06, 27 October 2008 (UTC)

Emission Output[edit]

I quote "zero-emission power sources such as wind." The article is comparing different power production in different regions. However, the section neglects to include the indirect emissions from the manufacturing, fabrication, installation and maintenance of wind power sources. I believe this section is misleading, to the point where the statement makes the assertion that wind power has no direct or indirect emissions, of which is a factual misrepresentation. —Preceding unsigned comment added by Frahnie (talkcontribs) 04:30, 21 November 2008 (UTC)

Well, go for it. Any note of realism is welcome on this awful article. Greglocock (talk) 04:56, 21 November 2008 (UTC)

Seems slightly confusing towards the end, in the last/concluding paragraph; when it starts talking about efficiency again.... emissions and efficiency arent the same thing...Heligan (talk) 19:57, 8 February 2011 (UTC)

Once upon a time there was a guy named LAVOISIER....[edit]

In Nature nothing can be created, nothing can be destroyed and everything can be transformed. That is particularly true when the issue is energy. In other words, in order to move the vehicle you must spend energy. This energy will come from compressed air. Right ? So the energy to compress the air will always be greater than the energy used to move the car. When you compress air you develop heat. This is a loss of energy. When you release the air it will move whatever engine you will use and there will be attrition... more energy loss. That is not to mention the resistance of air against the advancing vehicle... What is going to be the size of the air tank ? How much energy will be wasted to input the air at the required pressure ? Compressed air vehicles are pure fiction. It would be much more profitable to build steel striped roads and run electric cars on them. That would be for long distances and high speeds. For short trips and low speed you can run on batteries. Forget about that joke of air compressed cars. —Preceding unsigned comment added by (talk) 18:46, 24 February 2009 (UTC)

In any vehicle, the energy used to move the vehicle is less than the energy used by the vehicle. Nothing is 100% efficient, not gasoline, not deisel, not batteries.--RLent (talk) 17:49, 14 May 2009 (UTC)

But in this case the car actually requires two engines: 1) a compressor, 2) the actual compressed air motor. Since their efficiences get multiplied together (both are probably less than 50%) it makes the whole ordeal extremely wasteful of energy. Why not instead store the energy used for the compressor in a battery, and instead of powering a compressor, power an electric motor? (talk) 04:03, 14 October 2009 (UTC)
Also, gasoline and diesel have FAR greater energy densities than compressed air, and batteries to a certain degree also - as both fossil fuels and power cells undergo chemical reactions rather than just a release of pressure (which for ICEs is itself an integral part of the cycle and can be enhanced with water injection...). I've seen the equipment used for compressing air into SCUBA tanks (similar tech level to what would be used in cars, and believe me they don't make things made to be carried on the back of someone going for a swim any heavier than they need be). It's not drastically high-powered, and it doesn't have to run all that long. It does involve either running off 3-phase industrial power (because domestic supplies tend to max out at ~3kW unless you have something wired in specially) or using a diesel rig, but in neither case would the motors involved be something I'd consider using to actually power a road vehicle - even a light motorcycle of any worthwhile speed - if they were cut loose from their hard standing. Certainly, the power exerted over the length of time needed for a fill, multiplied by the number of tanks you could sensibly fit into the floorpan of a small car, with even perfect efficiency, wouldn't carry you more than 25 miles even at low speed. Without actually turning the air to liquid, and thereby having all the extra problems of supercooling on its release (without even the aid of it being instantly heated up by combustion as per LPG), you just can't cram enough stored physical energy in there. A battery car will wipe the floor with it, as would even a flywheel based one. ICEs are over the horizon and far away. Plus you STILL have to expend the energy - electrical off a grid, or with a little diesel genny - to compress it in the first place, so the emissions are just displaced rather than eradicated... and discounting CO2, even modern fuel burning car engines don't put out a huge amount of nasties into their immediate environment (and then the world), the way generators can and do. The only way this would be in any way viable is if it was used as a buffering method for renewables; there's a ready storage medium (atmosphere) waiting to be sucked into a large, heavy, stationary tank on an electrically (or for wind power, even mechanically) driven compressor, which has a completely separate generator outlet on the other end, ready to supply on-demand power for your home/electric car, or even ready-compressed air to go into the onboard reservoirs of a SLOW, SHORT RANGE local utility vehicle.
I mean. Seriously. The guys on the Gadget Show on TV this week were going nutzo over driving an air powered car .... it didn't get over about 7-8mph and they weren't allowed to ride it more than about a mile in total. I wonder why? If your tech was that good, wouldn't you want everyone to have a go and ride it til it quit? And it's been in production for... what... not much longer than steam engines? (EG mining engines ... mind that mine tracks don't tend to go that far, or very fast). But in that time we've had steamers that can hit over 100mph, electric vehicles like the tesla, fuel cells even. How come untested prototypes and working models that would be embarrassed by a Segway or child's electric skateboard are all we've got? Wake up. (talk) 18:12, 27 May 2010 (UTC)

The air car is working[edit]

The air car is working on the same basis as CAES (Compressed air energy storage) power plants that already work for 20 years.The MDI air car also works but not as you believe just compressing the air ( and heating it ) in the air tanks and then just puting the compressed air to drive the air motor.There is the possibility to improve the thermodynamic efficiency by some tricks.The technology already exists. By the 2006 Internationale Salon for Inventions and New Technologies in Bruxelles an invention of Mr.Ion G. Nemes from, called by the author "The Regenerative Isotherme"-the way to achive "Active Energy Storage" was awarded by Gold Medal. The patented (RO-120353 B1) procedure is working like this: during the compression of a gas in one insulated , pressured tank, the gas is simultaneous cooled by some heat exchangers and the cold side od a heat pump achieving an isotherme which virtualy compress the gas for free : whole compression energy is recovered as heat.The extracted heat is stored in other good insulated device containing salts, vaxes or bitumen or other materials with high latent melting heat, melting them by the hot side of the heat pump.The own heat of the heat pump is also added and stored in the heat storing melted stoff.By the time of use the stored heat,it is used to heat the compressed gas inside the tank, by transfer tubing and by engine itself.If the expansion is an isothermic one, the whole heat is conversed into mechanic work .So the efficiency of the "Active Energy Storage Car" reaches virtually 100%.The technology is also very useful in the energy storage domain including peak power plants and wind energy storage .If the primary energy comes from wind or solar station , the car is also 100% clean and economic worthy.There is also an older patented (RO-116494 B)invention of the same author :the thermo-hydro-pneumatic (THP) engine, where the cooling and exhaust heat of any engine is recovered by a similar procedure to cool a monoatomic compressed gas inside one tank during the compression phase and to move the compression heat , using an absorption heat pump driven by the cooling heat , to an other tank to heat the already isothermic compressed gas (in prior cycle) before overheating it by the exhaust heat of the engine in order to expand and produce work.This engine was patented in 1992 and sent in 1993 to all carmakers ,institutes and publications like : Mercedes Benz, Ford , Wolkswagen,MAN,Combustion Institute , University of Wien,and magazines like Auto Bild ,Car Design & Technology ,etc. but nobody wanted to learn more about the invention.Let see what the future will bring ! —Preceding unsigned comment added by (talk) 18:30, 11 March 2009 (UTC)

Gaaah! What we need are REFERENCES, not discussions of whether this works or not.ToolmakerSteve (talk) 06:18, 15 May 2009 (UTC)
Great idea, and you can burn gasoline to heat the compressed air ! Wait... (talk) 04:06, 14 October 2009 (UTC)
Also, you used too many words, and in your effort to sound credible, sound like a retard. Please 1) Take a thermodynamics class. 2) Draw a schematic and T-s diagram of the cycle because you obviously can't explain it in words. 3) Realize that the efficiency doesn't approach 100%, but rather 40%. (talk) 04:10, 14 October 2009 (UTC)

Advantage: lighter weight -- I can't find any reference that backs up this assertion.[edit]

I note that both air vehicle articles cite (without reference) the claim that compressed air cars are lighter weight. I haven't been able to find any verification of this. After all, a given vehicle must be compared against one with comparable abilities. So the correct comparison is to a LIMITED RANGE vehicle, whether all-electric or gasoline. Similarly, how much torque does this air car generate? Compare to a gas engine with same torque. Looks to me like this car is competing with other mini-cars, that are also lightweight. Bottom line: should the 'lighter weight' claim be removed as unverified? I see that MDI's air cars use lightweight construction approaches, but that seems independent of their use of compressed air...ToolmakerSteve (talk) 06:56, 15 May 2009 (UTC)

Reduced cost of production 'by about 20%' isn't sufficiently proven[edit]

I've removed 'by about 20%' from the reduced cost of production advantage, because the cited reference is MDI. That's not a good enough source to be that specific. I think the basic point of the systems that are eliminated is worth retaining .. though whether that OVERALL reduces the cost of the car is debatable. Especially now that Tata's Nano is a reality, demonstrating what can be done to make a low-cost conventional car. ToolmakerSteve (talk) 07:06, 15 May 2009 (UTC)

A summary[edit]

I have been looking into the issue of compressed air cars, my conclusions are that their validity is borderline.

I rather get the impression that air car developers are not so much fraudsters as over enthusiatic inventors who have wooed investors with claims that they seriously believed they could achieve, but have had trouble actually achieving due to unforssen difficulties. None of these difficulties have been total show stoppers, and so they continue to keep trying to fix the one last bit that will get them 'on the road'. As such, I would say that people who have not relised the investment they hoped for have been foolhardy investors rather than being conned. On the other hand I no nothing about what 'concrete' data was presented to potential investors.

Just to run through the issues:

1) It seems that Guy Negre was inspired by F1 racing teams who typically use a compressed air bottle for thier power tools, in particlar for the pistols used to change tyres and for starting the engines. A single compressed air bottle of high pressure air is enougth to power their tools over a whole race weekend, and provide air at higher than normal pressure for airtools. The motivation appears to be that it is simple, more reliable, and more portable than a high pressure compressor. However, whilst the tools that F1 mechanics use pack a high power in a small lightweight handheld device, they are used very breifly, there is nothing about F1's use of compressed air bottles that demonstrates it's praticality as a source of energy for motor vehicles.

2) Air cars do not seem to compete against convential cars, but against electric cars with rechargable batteries. In both cases the only ecological advantage per se of using air is that there is no harmful pollutants released in the environment where they are used. This is important for congested urban traffic areas and indoor use (where battery powwered vehicles are also deployed), but in both cases the overall emissions must take into account what was required to generate the energy used to compress the air in the forst place.

3) Comparing air cars with rechargable battery cars, using air to store the energy does not appear to have particular advantages. Compressed air can have a specific energy/weight ratio of around 40 to 70Wh/Kg, the higher figure assuming very high pressure lighweight carbon fibre based tanks of novel (and unproven) design. That figure is roughly equivalent to lead acid batteries, and is quite significant as it means that even for a modest performance/range vehicle, the air tanks provide the bulk of the weight, several hundred Kg. And in this situation youare working 'uphill', as carrying more energy means that you require more energy to accelerate the car, an important factor in a vehicle intended for urban/indoor use. Many electric vehicles use NiCad batteries, which have roughly twice the energy density. Lithium batteries have about three times the energy denisty but are also very expensive which limits their use, however the deployment of hybrid cars has led to major manufacturers taking steps to drive down the cost of mass produced high performance traction batteries. With better batteries the vehicle can carry the same energy with significantly less weight, hence improving the acceleration, range and efficicieny to the extent that it could carry even less energy to achieve the same performance, and reduce the structural requirements. Or in other words, doubling the energy density could yield e.g. a threefold increase in range. Air does not offer the same potential. Stored energy can be increased by increasing air pressure, but quoted pressures are allready at limits that are raising serious safty concerns. Even ignoring safty concerns, the weight of the air increases (air compressed to 100 times normal pressure weighs 100 times normal weight), plus one can saftly assume that at least a small weight increses will be required in the tanks to support the higher pressures. So significant gains in in overall energy density cannot be achieved.

4) Service station recharging of air vehicles is potentially quick, assuming the station has a large reserve of air to draw on. Batteries cannot be recharged quickly, however much instant energy is on hand. Theoreticaly it would be possible to 'recharge' an electric vehicle in less than a minute if the battery were detachable and could be e.g. swapped out from underneath using something like a fork lift, but I have never come across any serious proposals for such a scheme apart from a home pizza business who use electric bikes and have reserve batteries on charge that the riders can swap in when they ome in for fresh deliveries.

Project Better Place is building such a system. Also there are batteries that can be 'recharged' at the same speed as a gas tank, but they are not much used.

5) Home recharging is primarily limited by the limits of the domestic energy supply, which is small compared to the energy requirements of even lightweight vehicles, so several hours charging time will always be inevitable. If home charging of either type of vehicle became commonplace, it would be no suprise to see legislation comeing into place to restrict this. Not because of tax issues (they are easily resolved by our ever ingeneous politicians), but because of the overload it will present on the electricity network itself, both generating and distribution. The amount of energy people use in their cars often matches or exceeds domestic energy consumption, and a rapid wide scale adoption of home charged vehicles would send the whole system in tilt. A similar scenario has allready presented itself with the rapidly increasing deployment of air conditioning systems. Goverments have counteracted the AC problem by subsidising the adoption of photovoltaic cells, which inject energy into the system locally with peak production neatly matching peak AC consumption. Such a soltion would not be so easy with vehicles, however air is potentially easier to deal with as far as 'service stations' are concerned, as they can charge air tanks at convenient times and 'load shed' (switch off) as required by the network operators (allthough of course battery change stations could also do this).

6) Allthougth high pressure air tanks made of carbon fibre will certainly not be cheap, it would appear from the pricing that is being touted around that air vehchles could have a great cost saving as rechargable batteries capable of deep charge/discharge cycles are not at all cheap, and are the primary reason behind the high cost of battery powwered cars. In addition, batteries wear out with each cycle and with age, whereas an air tank could potenitally have the same lifespan as the vehicle.

7) Battery powwered vehicles are a well proven technology. Simple vehicles with just batteries and DC motors have been in widescale use in industry for decades. In the UK, house to house milk deliveries using electric vehicles took over from the horse and cart. Modern electronic technology allows more efficient use of motors, and refinements such as regenerative braking are being added. Batteries, likewise, are being continually improved. Air powered cars are a very much emergent technology. Allthougth essentially simple, there are major hurdles. In particular, the expanding air requires heat to be drawn in from the ambient to allow it's temperture to rise. Many early experiments with air cars suffered from simply freezing up. Current solutions for air powered vehicles propose solutions to this problem. Guy Negre uses a multi cylinder approach, but that seems to just increase the thermal mass and delay the onset of the problem more than resolve it, for a given energy out at the wheels, a given amount of energy must be drawn in from ambient heat, and if you draw too much in a small space, the temperature plumments. It would appear that this is THE major problem with air powered cars at present. Indeed it is noticable that whilst air cars have been demonstrated doing short stints, I have never come accross a situation where a journalist or the public have been invited to take a car for a non stop test run, underlining the possibility that air cars are still unable of sustained running and require time to 'warm up' after even short stints. The theory is further support by Guy Negres latest engines which use hydrocarbon fuel to warm up the cyclinders, essentially making it a competitor of hybrid cars.

So I see the whole air car issue of being a technology that could potentially have some small advantages over battery cars and possible over hybrid cars for urban use, but at the same time it is a technology that it is still under development and may not actually surpass they actual battery/hybrid vehicles. It will certainly not offer world shattering changes, at best a small step forward in certain niche vehicles.

I think the main article needs a complete re-write in order to put air cars in the perspective of their potential application and advantages, showing how they can fit into the scale of other vehicles. Fundamental to this would be a correctly calculated and referenced table showing the power to weight ratios and other factors which would make it clear just what air cars would be competing against if the technology was made to work.

The probelem is that the various air car promoters are strongly averse to releasing such information. Please sign your posts in future. Greglocock (talk) 01:29, 22 September 2009 (UTC)
In addition to being rewritten, the article should be added to the category "Internet and Media Hoaxes." (talk) 03:20, 22 October 2009 (UTC)

Well to wheel efficiency[edit]

The article claims well to wheel efficiency of a combustion car is 20%. The pump to wheel efficiency of a conventional car is less than this, and the source listed was blank. Can someone find a source for this? (talk) 01:21, 8 February 2010 (UTC) kara shopnere was here —Preceding unsigned comment added by (talk) 16:16, 22 March 2010 (UTC)

Misleading assessment of spark ignition engines[edit]

This text is technically inaccurate and misleading:

"However the modern internal combustion engine has only around 15% percent[2] engine efficiency and requires a significantly more massive engine so these numbers may be somewhat misleading."

This is the reference used:

However, the article does not describe engine efficiency, it describe the overall automobile's efficiency on an overall use scale. Also will compressed-air engines require drivetrains? Will they power accessories? Will the driven turbine have imperfect thermal efficiency? Will the initial compressor have imperfect thermal efficiency? Will the plant producing the electricity to run the compressor have imperfect thermal efficiency? Probably yes on all counts, so many of the same spark-ignition losses also apply to compressed-air engines, and has some new ones thrown in as well. So you can't use a figure of 15% efficiency, *that* is somewhat misleading. I'm removing that line. —Preceding unsigned comment added by (talk) 22:14, 30 August 2010 (UTC)

I agree. In order for that section to be useful it would have to present a lot more analysiss, which would be OR or synthesis. Greglocock (talk) 23:09, 30 August 2010 (UTC)

Compressor efficiency[edit]

In the disadvantage section it is claimed that it takes 93kWhr to store 14.3kWhr of energy into the 300 bar 300 liter tanks. This is a bogus statement. Technically true for a single stage 1 bar to 300 bar compressor, but nobody does this. Industrial 300 bar compressors are 3,4, or even 5 stages. With intercoolers between stages, they are much more efficient than 14.3/93 = 15%. For typical high pressure compressors, efficiency is in the 50-60% range, so it would take about 26kWhr to fill a 300 liter 300 bar tank, not the 93kWhr claimed in main article. —Preceding unsigned comment added by (talk) 21:53, 3 September 2010 (UTC)

I fully agree with the previous comment. Most of the 250/300 bar compressors used for scuba/diving have 3 to 5 stages and reach an efficiency close to 55 % (compressors with an electric motor from Nuvair, Bauer, Coltri, ..). Abaca 22:25, 6 September 2010 (UTC) —Preceding unsigned comment added by ABACA (talkcontribs)

This looks like original research. If you can find a source for these claim, then we could just replace it. Until then, I think giving the original poster a few days to come up with a reference is okay. 018 (talk) 02:09, 7 September 2010 (UTC)

eg 200 bar, 10 litres, 3.3 minutes, 11 kW. so for 300 bar 300 litres, 5 minutes that'd be at least 1.5*30*10/3/5*11=330 kW, even if the power only increases proportional to pressure. That's a 400 hp unit, I think the electricity grid will notice either way. Greglocock (talk) 04:29, 7 September 2010 (UTC)
A 300 l / 300 bar air tank contains 90 m3 (perfect gas) and about 81 m3 of air (due to "Van der Waals forces"). It means about 13 kW (47 MJ) of energy (assuming isothermal compression/expansion, W = P2V2 x Ln P1/P2).
A multi-stage 300 bar scuba air compressor (Coltri MCH13 for instance) provides an air throughput of 13 m3/h (215 l/s) with a 4 kW electric motor.
Hence, it takes 81/13 = 6h 12mn to fill the 300 l air tank at 300 bar.
Assuming a continuous 4 kWh power consumption during 6H 12mn --> 25 kW input energy.
Resulting energy conversion efficiency: 13 kW/25 kW = 52 % much better than the 15% given in the article.
Practically, the real electric consumption is a little bit lower due to the fact that at low air pressure (first compression phase) the compressor uses less than 4 kW.
For a "Coltri MCH13 ET" description see : Abaca 22:43, 8 September 2010 (UTC) —Preceding unsigned comment added by ABACA (talkcontribs)
Please sign your posts, and maintain thread order. You have confused work and power units therefore I am not going to check your figures. When you have sorted that out, please estimate the electrical power required to fill the 300 litre tank to 300 bar in 5 minutes. Is it substantially different to my estimate of 330 kW? Greglocock (talk) 23:25, 8 September 2010 (UTC)
Greglocock, there is no reason to fill something in 5 minutes to get the efficiency. Also, I don't really want to include values from a 200 bar compressor with calculations that inflate it to 300. Changing the units and estimating the efficiency is one thing, but actually guessing what would happen when a different final pressure was reached is another. How do you know the efficiency is the same from 200 to 300 on the compressor? 018 (talk) 19:28, 9 September 2010 (UTC)
Are you the same editor as ABACA? I suggest you reread WHY this section of talk was started, it was all to do with the claim in the article that a 1MW compressor was needed, so time is important. Greglocock (talk) 23:40, 9 September 2010 (UTC)

Independent of how much energy the compressor needs to compress this amount of air : it will -in real life- not be possible to get back the 14.3 kWh stored in the tanks. To get it all back you need an isothermal expansion - which means that either you need a very slow expansion (impossible for this application), or a continuous upheating DURING the expansion process (in the expansion cylinder!). To do this without supplementary heat sources (eg burning sth), you would have to use heat exchangers with the surrounding air. Unfortunately, it is technically impossible to build an heat exchanger with the needed specs that could deliver this amount of power to the (small) cylinder(s) due to mechanical and geometrical constraints. The expansion process of MDI will at most be adiabatic, which means that they will get roughly around 7-8 kWh out of a 300l / 300 bar tank. —Preceding unsigned comment added by (talk) 20:25, 3 February 2011 (UTC)

Swedish representative for MDI air cars has been murdered and dismembered[edit]

The Swedish representative for MDI Air Cars, Ms Eva Magnusson from Nora, Sweden, has been found murdered and dismembered[2] under mystical circumstances[3]. She was the Swedish representative for MDI Cars as early as 2001 when she collected up to 5 million Euro from investors to build a Swedish air car factory.[4] [5] (talk) 14:51, 18 January 2011 (UTC)

The name of the Swedish company drawing investors to invest in MDI Aircar factories was 'Zero Pollution Svenska AB'. Eva was also running a company named U21 Partner AB (talk) 15:19, 18 January 2011 (UTC)
You mean mysterious? Mystical is something like magic, but then again... פשוט pashute ♫ (talk) 17:14, 13 March 2011 (UTC)

Pneumatic combustion hybrids[edit]

Including these is misleading since the cost will be roughly that of a normal car PLUS the air engine and tanks. Greglocock (talk) 22:12, 8 March 2011 (UTC)

Proe's Ericsson cycle engine system with compressed air tank[edit]

Can someone mention the Proe's Ericsson cycle engine system in the article ? This system has several huge advantages over the conventional compressed air system when used with vehicles:

  • when using the system in combination with a compressed air tank, the vehicle can be started immediatelly, as opposed to ie a Stirling engine vehicle (which requires a 10-15min warm-up time)
  • compared to a regular compressed air vehicle system with just a compressed air tank, the vehicle has far greater range, as (most of) the fuel can be a liquid or solid fuel which is more energy dense and doesn't need a tank
  • the fuel can be biofuel (for example wood pellets, see wood pellet stove) so that emissions are extremely low to non-existant (if trees are replanted), and the amount of smoke produced is minor aswell (the first part of the trip is even run on compressed air which is completely smokeless).

(Note that wood pellet stoves are probably the most practical as the pellets can be fed automatically, and they also burn extremely efficiently -only the required amount of pellets are administered per turn-) (talk) 09:15, 31 May 2013 (UTC)

Wording (clarification)[edit]

Article says:

Conversely, when air is compressed to fill the tank it heats up: as the stored air cools, its pressure decreases and available energy decreases. It is difficult to cool the tank efficiently while charging and thus it would either take a long time to fill the tank, or less energy is stored.

Could someone explain: a* 'it heats up' - the tank or the air (or both)? b* 'as the stored air cools' - you just said it heats up. When does it cool, after it was heated up? c* 'It is difficult to cool the tank efficiently' - wait a minute. Why do we want to cool the tank? d* 'or less energy is stored' - if I cool the tank more energy can stored? But isn't cooling the tank - taking away energy?

Or perhaps just explain it in a different way? (If you do, please tell me here, thanks!)

Thanks! -- (My birthday, 8 Adar2 5771) פשוט pashute ♫ (talk) 17:27, 13 March 2011 (UTC) (edited) 15:47, 14 March 2011 (UTC)

I will try to explain!

a* Basic law of energy says it cannot be created or destroyed, only transferred. When volume is constant (this is the case in AirCar's tank; it is not a balloon), air temperature and so the tank temperature have to go up when pressure is increased. That is why they have inter-coolers in air compressors.

b* Law of thermodynamics: hot tank will have to lose heat to cooler air outside, like a hot cup of tea becoming cold.

c* Depending on temperature difference, exact shape of the air tank, breeze around the tank and so on, the rate at which the air tank and so the air inside cools will change.

d* When air cools, (heat) energy is lost to ambient air.

Someone missed the key issue: compressible fluids are very dangerous to handle at that pressure of 4,500 psi; leakages will kill. Most of the hydraulic excavators using incompressible fluids like oil as the medium go up to 4,500 psi without danger. To pack the energy needed for a vehicle with 4 people to travel say 100 or 200 miles in an air tank is an engineering marvel needing light weight but strong material for the tank. What about the weight of the air itself at that pressure? Agreed there is no pollution in the city where this car drives through, but pollution may need to be created in the electricity generating station elsewhere: the rider is what if such stations are also based on renewable energy sources like wind, solar, hydro and so on. Welcome to 22nd century, it is a bit early though.

signed: rama1946 5 Jun 2012

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