• Oct 24th 2008 at 8:52AM
  • 7
One of France's most prestigious auto magazines, L'Auto Journal, has published a very skeptical and critical report about Guy Nègre's MDI compressed air car, whether we call it the AirCar or FlowAir. The article (not available online) makes quite a number of arguments against MDI and the whole idea.

First of all, L'Auto Journal focuses on the technology. Yes, the engine is quite revolutionary in how it uses the power of air but how about storing the compressed air? In order to store the energy equivalent of 1 liter of gasoline, we need 150 liters of air. When compared to a small Hyundai I10, MDI's largest model, the OneFlow Air, doesn't perform that well: At 50 km/h (30 mph), the I10 only needs a single liter of fuel to drive for 34 km (22 miles) - that's 150 out of the available 190 liters in the canisters of the OneFlow Air - yet it weights double. The numbers don't add up and L'Auto Journal claims the OneFlow Air will barely get 100 km of range. And there's more... (after the jump)

[Source: L'Auto Journal]

When it comes to the possibility of making the car bi-fuel, that is, adding a device that heats the air to improve its range, MDIs figures state that using both compressed air and some kind of fuel, we get 2 l/100 km but when we run out of compressed air, the consumption figures climb up to 3.5l/100km, which you could get with the Lupo 3L and which aren't that far from the 3.8 l/100 km (highway) of the Kia Picanto (the I10's sibling) diesel version. Of course, don't forget to add that our real world driving conditions are quite variable and so actual figures are likely to be even worse.

How about the possibilities of recharging the car? Yes, you can use a standard compressor, but it takes 4 hours. Nègre announces 3-stage compressors (like the ones used for scuba diving) that should be available everywhere but can you count on your regular gas station having these compressors? Add in the fact that, at least for France, no government aid has been planned for this car and compare the situation to the growing recharging networks for EVs - which are already on the road.

Last but not least there are homologation issues. Although a model was seen bearing official plates, no word has been said on how a car driven with a joystick, the AirPod, could even be homologated as a NEV - when there isn't even literature on how to homologate a car that isn't driven with a steering wheel.

Conclusion: Although can get excited about MDI and its compressed air models, too many questions remain unanswered for L'Auto Journal. And many others.

[Source: L'Auto Journal #762]


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  • 7 Comments
      • 6 Years Ago
      I agree with gnomaedh!

      We can always state problems. It is so easy to assign blame; yet contributing to the solution process is what we need! The Air Engine is not perfect; but neither are the Combustion Engine or the Electrical Hybrids.

      What we need to do is focus on solving the problem rather than simply stating it! If we listened to all the naysayers of this world then nothing would have been invented and we would still be living in the stone-ages! I think that the time has come for us to start RUNNING ON AIR!

      Boom
      http://runingonair.blogspot.com/
      • 6 Years Ago
      Even though the French article was sceptical, they seem to have accepted at face value the MDI claims as the range of their cars. I don't believe that MDI has ever run any of their prototypes to anywhere near the range they claim.

      The only test report they issued showed the car running out of air after only 7.22km. The 120 mile range was then calculated assuming a whole series of improvements such as "double the range by reducing weight by 2", "better engine efficiency, so we'll double it again", etc....., The end result is that they went from an observed operating range of less than 5 miles and somehow turned that into 120 mile range.

      If MDI were really as close to production as they claim, then they would have fully functional (or nearly so) prototypes.

      But every year since 2000 we see the same basic performance claims, with an announced plan to go into production in 12-24 months.

      WHy has no auto magazine ever been allowed to test drive a prototype car?
      • 6 Years Ago
      Why not use the Air engine as an electrical generator in a REV? Best of both worlds. Are there technological limits for this set up? Has anyone explored it? You would never need to use any gas, hydrogen etc... All you would consume is the electricity needed to compress the gas. Sure there may not be a great 'consumer' business model (or one at all), but it would be a great for the people selling the cars and great for me because I like keeping my money when I can :P.
        • 6 Years Ago
        To make a good "range extender" we need something that is smaller and has much greater range than batteries, otherwise we'd just use more batteries. Unfortunately, this air engine and its large high pressure tanks just don't meet that standard.
      • 6 Years Ago
      Gentlemen, the real question is whether or not compressed air as an energy medium can effectively replace fossil fuels: http://www.thefuture.net.nz/energy.htm
      Let's perhaps consider the potential for a severe shortage of oil within the next few year... just imagine... Now, what can we replace this with ASAP?

      Arguments are just lovely, but stay focussed on the real problem... declining fuel availability with increasing demand.

      gnomaedh,
      http://flowair.blogspot.com

      • 6 Years Ago
      I agree that the numbers don't work. I was once a big fan of air power, but I did the math myself. The energy storage of compressed air is rather low when compared to moving a vehicle.
        • 6 Years Ago
        You all keep forgeting compress air, is common media for storing energy. Imagine unused power making compress air, then sending down pipe to our homes, and use it instead of elec. Check your history, France did this once already. This is the solution for not being able to transmit elec a far distance, where copress air is limitless.