Talk:Compressed-air car

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)~

It sounds like Bullshit to me.

I already checked it with Tata Motors (sent an e-mail); Its definitly not a hoax. KVDP (talk) 15:01, 1 February 2008 (UTC)

Removed from Advantages

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.

Emissions Dubious tag

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)

Clarification

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, 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. 24.17.29.190 00:07, 22 March 2007 (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)

PHEV

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

Comparison

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

The sentence about Energine: The domain energine.com 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)

aircar

The compressed air car is a much desired development in the search for an alternative cleaner, non-polluting form of motivating power that can be used in transportation. For the past 150 years the IC Piston engine, working on the Otto cycle and first invented in 1866 by Nicholaus Otto, has been the mainstay of personal and commercial road transport. Yet with all the billions of dollars spent on trying to improve the performance of the IC Piston engine, every working sequence of the engine being examined and tested with the latest computer technology and simulations, by millions of people around the world, it is amply clear that if a solution is to be found for a more efficient engine, it won’t be based on IC piston technology. Even with all the 21st. Century innovations and improvements, such as MPFI, double overhead cams, multiple exhaust and inlet valves etc., the IC piston engine efficiency remains at 20%! Think of it, an amazing and unacceptable 80% of the energy in the fuel used is wasted, by comparison, rockets and jets have an efficiency of 70% and better or are more than two and a half times as efficient as piston engine cars, they are also, relatively, pollution free. Unfortunately, both turbines and rockets require or have required until this date, continuous combustion to deliver this order of efficiency. When used in road transport they are therefore very fuel inefficient using about 8 – 10 times the fuel used by a piston engine of similar size. The compressed air car comes as a welcome and audacious challenge to IC Piston technology, it is an almost viable technology. The Compressed air car engine does work, for those of you who have doubts, you can check out this link on model airplanes that use compressed CO2 to run a piston engine. http://blacksheepsquadron.com/index.html Of course one has to take into account that CO2 is far denser than air and would therefore work better as a compression agent, however the point is that the compressed air engine technology is viable, or as I had previously stated, almost viable. The reason I say this is that a tank of compressed air with a capacity of 340 litres, (taken from the MDI Car specifications web-site) the compressed air would last for a maximum of 2 minutes. You can perform the calculations for yourself. A tank holding 340 litres corresponds to a cube with 2.25 ft sides. This tank is filled with compressed air at 4500 psi or 300 bars approx. The optimum rpm of the engine is 4500rpm, compressed air engine tend to perform best at a given rpm. Now if the cylinder capacity is about 8 cu ins. then at 4500 rpm, the engine would use 4500/60 = 75 x 8 = 600 cu ins in one second and 36,000 cu ins in one minute. The capacity of the tank is 27 x 27 x 27 cu ins or 19,683 cu ins. But the piston needs only about 500 psi to work, so to get an accurate figure we have to divide 36,000/9 = 4000. So the tank will last for 19,683/4000 = 5 minutes approx. The point is that it often takes five minutes just to get the car out of the garage also once you use all that compressed air there is no way to re-charge the compressed air, so after about 4 –5 minutes you have to go to a service station and recharge. To recharge air at 4500 psi takes about a compressor working at 500 KW! 500KW, is enough to supply electricity to a fairly large town. The longer range of 200km – 300 km is only achievable when an IC piston engine is onboard. Again to recompress the air with an onboard motor would take at least 3 – 4 kours. So while it is a wonderful technology, it is far from viable at the moment. DDjames 14:35, 12 September 2007 (UTC)

recent news

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)

Emission Free? - Cleaned Up

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. http://www-formal.stanford.edu/jmc/progress/hydrogen.html 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. 66.225.251.176 (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

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 http://www.geocities.com/rotarypulsejet 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)

Safety?

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. --128.135.60.4 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)

MDI Air car

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)

pro IC POV ??

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)

Generic Air Car Rewrite

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)

Amendment

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)

Merge to Compressed air vehicle

You can see compressed air vehicle and improve it. --Mac 13:12, 24 October 2007 (UTC)

Rollout timing

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

I agree That this idea seems feasible but...

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)