... seeking simple answers to complex problems, and in the process, disrupting the status quo in technology, art and neuroscience.

Thursday, September 18, 2014

Amazing New Air Car - It's NOT About the Air!


09-18-14 - Another radical light car for Paris.  This one is 2100 lbs and uses Air/Hybrid to get 141 MPG.  Are the French on a roll?

01-25-13 - Peugeot Cirtoen to Introduce Compressed Air Hybrid by 2016

09-07-12 AIRPod

09-07-12 Tata AIRPod

07-05-11 - Tata Air Powered Car to be Introduced in India

02-26-09 - Yet one more way to use compressed air for braking recovery from ETH Zurich

First posted 01-19-08:

And it's not even about the car!

(note - whoever owned the MDI page when I posted this blog has diverted it to a new investment group and broken some of the links below. I have redirected them to the French or Guy pages as well as possible for now - thanks to Chris from Future Net.)

Every now and then a an idea comes along that will change the world - and gets mostly ignored. Some of you have heard me talking about this new air powered car from MDI (Moteur Developpment International) in France which is now to be manufactured by Tata Motors of India.

MDI did a press release a few weeks back and it was handled like, well, another press release. The automotive press paraphrased a few paragraphs, but I wonder if they actually THOUGHT ABOUT what they wrote?

And when Tata Motors introduced their more conventional yet inexpensive Nano at the Detroit Auto Show last week, it got amazing coverage, but not ONE mention of this new air car to be manufactured by the very SAME company!

The highly touted Tata Nano is a cute little bug that will get more than 50 MPG - cool. But the MDI OneCat which is about the same size will go more than 3 TIMES farther on the same gallon of fuel! Did no one actually READ the spec sheet on the OneCAT?

To be fair, the objective of the Nano is low price, not mileage. And the OneCat is much lighter, which helps, but surprisingly, that's not the key to it's mileage advantage. Here's how they do it...

As almost everyone knows, the standard internal combustion engine is only about 30% efficient under the very best of conditions. This means 70% of the energy in a gallon of gasoline leaves the car as wasted heat.

The only heat that produces power is that narrow band of highest temperature that causes rapid expansion of air when the spark plug fires. Once the piston reaches the bottom of it's cycle, all the lower temperature energy from that cycle is wasted and must be pumped out the exhaust pipe.

If you add MORE heat at the point of ignition (higher octane), you get more power. But Carnot and his second law of thermodynamics limits us from using any of the heat BELOW the temperature of ignition. THAT is the primary reason for the INefficiency of the internal combustion engine. But what if we COULD use ALL of that heat?

CAT - Compressed Air Technology

Guy Negre of Formula 1 fame and his company, Moteur Developpment International have spent the last 14 years developing a new type of engine for automobiles.

Compressed Air Technology has been described as using air as fuel, but that's not quite right. The air works more like a battery. Guy's design actually uses a carbon-fiber air tank with up to 300 times normal atmospheric pressure driving a piston to give the car a range of 100 Km. You can think of this system as a standard compressor motor and air tank - except it's running backwards. The air tank drives the compressor, instead of the other way around.

So far, no big deal. Any advantage is a matter of strength, weight and volume per unit of energy stored in the "battery" - the carbon-fiber tanks helps some. But if a short range compressed air car is all they had, it wouldn't be very impressive. The next refinement is the key and I now believe it was created in response to the problem of freezing the engine as the air was decompressed. Whenever air pressure drops from 300 Bar to 1, the gas laws say the heat in that original volume is now spread out over a much greater area thus dropping the temperature. Guy's "fix" to this problem had a side-effect that I believe to be the biggest advancement in thermal energy extraction since the invention of the Otto-cycle in 1860! It effectively uses "wasted heat".

Bi-Energy Breakthrough

Guy Negre's brilliant innovation is to add a small fuel burner between the air tank and the motor. The heat from this burner not only keeps the engine from freezing up, it also extends the range for the compressed air tank by increasing the pressure of the air even more on it's way to the motor. Properly insulated, this burner could approach 100% conversion efficiency of the burned fuel. Here's the reason...

Small amounts of heat are not enough to turn over a reciprocating motor. But when you add a compressed air tank, it provides a pressure bias great enough to drive the motor on it's own. Now add the burner. Per the gas laws, the pressure increase is proportional to the heat added - it doesn't require a critical temperature of ignition! You could run it tepid or boiling - ANY heat adds power. It's just a matter of how much.

If you double the burn rate, you'll double the added expansion. Since there's no point of ignition, there's no critical temperature before this energy is extracted. ANY heat added by a burner (or other source) will simply add proportional expansion and energy extraction. Theoretically, most of the energy from a gallon of gasoline (or stack of firewood) could be used to drive the motor.

Check the spec sheet above. I assume these are actual measurements. The OneCAT will go 100 Km on air alone, but another 700 Km on only 10.5 (1.5 Liters per 100 Km x 7) liters of fuel! That works out to almost 157 MPG!

More Than JUST an Amazing New Car

MDI has a good chance of creating an amazingly efficient little car, and that's cool. But what's REALLY exciting are all the other potential industrial applications.

Considering generation and line losses when producing electricity, it may even now be more efficient to run Bi-Energy motors at the site of the application instead of buying electricity. Or we could boost mechanical power from solar heating. Or hot sewer water for that matter! ANY source of heat could be used. It's just a matter of degree and effectiveness.

OK. You'll still need electricity to provide the compressed air bias, but the rest of the energy would be more efficiently extracted - the hotter, the better. What about recycling the heat from air conditioners to drive their OWN motors? I'm not talking about perpetual motion here. There's no free ride. It's just that the heat is no longer has to be totally wasted. This approach provides an excellent possibility of dramatically increased efficiency in anything that needs a rotating motor and has wasted heat available. (Note - MDI was WAY ahead of me - I just found this link on their site... Further Applications - WOW!)

These ideas are worth more than just a press release.

It's a whole new way of thinking about energy!

More Air Car Energy Links...

Guy Negre Page

MDI and Indranet

Dr Louis Arnoux Interview

Future Net



Others are picking up on using waste heat in this fashion - The VGT RoundEngine


  1. Comments from sci.energy in Google Groups about this post...

    > You're saying it violates the 2nd law:

    There no perpetual motion machine here. I said it DOESN'T violate the 2nd law. It applies it!

    Think of it this way. We have compressed air (at some useful pressure) and at room temperature. The cooling effect (noted above) doesn't occur until the gas expands, which is hopefully in the cylinder creating mechanical energy.

    Now what happens IF you add a modest amount of heat (from any source) to the gas just BEFORE it enters the cylinder? Let's say the heat you add is just enough so that the expanded exhaust comes out at exactly room temperature. In that case, you get the energy from the compressed gas but you ALSO get ALL of the energy from the heat you added (minus mechanical and other losses). This is no magical machine, but it CAN use heat below the temperature of ignition which is MOST of the heat from burning fuel external OR internal.

    But let's say you got that extra heat from your shower drain. All of a sudden the "wasted" heat from your shower is converted into mechanical force. that does NOT violate the 2nd law of thermodynamics. It applies it.

    > I can't see any concept here that wouldn't have been thought of 200
    > years ago when people were struggling to get the most efficiency from
    > their heat engines.

    Ah... but they WEREN"T after efficiency per se. They were just trying to make the damn things work at all. And when something worked at all, they focused on it.

    And they DID apply the concepts of an external combustion engine. It was called a steam engine and worked quite well. It's just that taking water to a vapor required they operate at higher temperatures and pressures. To bad every one got distracted by Otto. We might have very different cars today.

    The difference with MDI is that they can operated at a much wider range of temperatures and pressures and they ARE after efficiency. I don't know if this will work as they say, but I DO see reasons to consider it.

    > They're not proposing ceramic cylinders or fancy fuels, or even new science.

    True. This is the "Otto" distraction I spoke of where the objective is higher octane and temperature. That is exactly my point. What happens when we start thinking about extracting energy BELOW the temperature of combustion? I think it's worth investigating. Apparently, they do too unless this is just some elaborate investment scheme.

    > Just bog standard expansion of hot gasses and bog standard compressed
    > air, the same as is used in industry every day.

    EXACTLY! But this external combustion IS being applied in a way never done before. At least to my knowledge. And that's exciting.

    > When they say in Europe gas consumption in Liter, that means per 100 km.

    The unit in the spec says Liters, not Liters per 100 Km, but I believe you are correct both because of convention and it makes more sense for a 900 lb car. I would have expected no more than a tripling of efficiency. This means the mileage from the fuel component would be 157 MPG instead 1100 MPG. I will correct the error immediately. Thank you.

    > It is still a great efficiency, but it is also a very little car.

    True. But then we should be able to get about 100 MPG for internal combustion if the car stays under 1000 lbs. That's what the X-Prize is all about. Time will tell.

    > Funny how things have a way to turn out not as exciting once you start
    > to crunch the numbers.

    I think it's potentially QUITE exciting. My blog post was NOT about the car as noted by the title. It's about taking a fresh look at EXTERNAL combustion engines for all kinds of uses.

    We need to think OUTSIDE the cylinder.

    Thanks for the useful feedback, Evgnij.

  2. The cooling effect (noted above) doesn't occur until the gas expands, which is hopefully in the cylinder creating mechanical energy.

    When some gas leaves the tank the remaining gas expands to fill the gap. I think this will cool the remaining gas. Calculating how much is probably disappointing but still I think it would.
    There is enough mechanical energy available, you think additional cooling could be used?

  3. At the very least, MDI ( http://www.mdi.lu ) and ZPM ( http://zeropollutionmotors.us ) must present their product concepts via the Auto Xprize.

    Let's see exactly what potential this type of vehicle has as an immediate replacement for our dying internal combustion engine industry.

    Good luck to all Xprize competitors, and may all of the best IDEAS create a paradigm shift in energy and transportation!

  4. Anyone who actually believes the lies promulgated by MDI needs to obtain an education in science, more specifically thermodynamics.
    The air car is a fraud, back to school fellas.

    The air car never did qualify for the X-Prize.
    I guess you need more than words to qualify, that is all they ever had was hot air, never any proof, the reason is that what they claimed was impossible.

  5. Anon,

    I allowed your comment in the interest of free speech, and to update the topic with a comment.

    I too am disappointed in not seeing more development of this technology, but I'm not ready to count it out just because they didn't get an entry in the x-prize.

    There are a lot of factors in a commercial success. Not all of them are optimum at any given time. But the best ideas DO emerge over time. I see no fundamental reasons this can't be made to work, so I'll continue to withhold judgement until I find one.

    If nothing else, I'm impressed someone has built a 1500 lb car, whatever powers it. - Rod

  6. Did they not say that those air cars will be available next year? That was 2008. Look it is 2015 and still nothing. Maybe next year or this is just a scam. Using compressed air as a storage medium is so inefficient and bulky. This is junk science and lies.

  7. Anon, I agree we haven't seen any cars yet, but that doesn't make it junk science or the prototypes wouldn't be driving around. There are lots of practical reasons products don't make it to market. Perhaps this one will in time.