NOV 23

Even if I grant them the efficiency argument, I don't think this is a slam dunk. Batteries are made with lead and acid, or lithium, or other exotic metals and chemicals. Air tanks are not.

In any lifecycle comparison, I'd like to see the mining, transport, production, refinement and disposal of the batteries taken into account. Electric still may win, but until I see those factors analyzed I think we still have an open question.

Assuming your opinion is based on a study you've read it would be nice if you provide us a link to the study or maybe some details that support your opinion,i.e.there are so many variables to compare. I'm not saying you opinion is not valid, just not as helpful or "efficient" as it could be in enlightening us.

Oops!! never mind, sorry Alex, you did leave a link(us old farts always forgetting the reading glasses), I read it, good food for thought.

There are serious applications for compressed air vehicles for which electric vehicles are unsuitable. The largest application is operation in potentially explosive gas environments (mines etc) where currently diesel powered vehicles are the only safe option.

Also, what is to prevent a compressed air tank from being re-charged with an energy source other than electricity? For example hydraulic rams powered by a creek (or any other flowing water) are entirely suitable.

Using wind power to compress air could be an option with 2 benefits: No electricity required at all, so no batteries, inverter losses, etc, and compressed air can be stored so the erratic nature of wind is no such a problem.

This is interesting, it's great to see innovative thinking on the technological side of automobile efficiency. For me, though, it's equally (if not more) important to think about the social innovation in transportation. For instance, when people decide to share a vehicle or car pool they are essentially doubling the efficiency of the car. If you're concerned about emissions and efficiency and there was a way to instantly double the efficiency of your car, wouldn't you do it?

Even if it's less efficiency, a compressed gas chamber build with metal could be more easy to reuse after the life cycle of the car than a battery that you will have to put to garbage. When all cars will be battery-powered, I am sure that there will be a trouble with the production and elimination of batteries.

Sounds like mud slinging to me.You have to remember that reports are not all ways unbiased.The auto industry started down the BEV's,Hydrogen and hybrid path. They invested a lot of money and need to protect there in vestments.User efficiency with time on recharging the BEV or the air tanks will be the end game,minus ones ability to have either or any of the cars available to purchase.If the air car can be recharged within a few minutes and get about a 100 mile range at wide open throttle and reach high way speeds,compared to a BEV that takes hours or hydrogen that cost an arm and a leg, I'm taking the air car. It's all about cost and time.I do understand that high pressure air stations would be required for quick air recharging,but hydrogen requires stations and so does BEV's for long distance travel. As for the efficiency comparison, I not going to argue with facts,CO2 out put can be delt with at the power plant and some good pollution controls.

I think both technologies should be promoted, and when the gasoline engine is extinct, then we can focus on which is better. This sounds like divide and conquer tactics to me.

@ Frederic: The compressed air tanks of MDI's compressed air powered vehicle are made up of carbon fibre and not steel. Steel proves to be too heavy in such an application and is virtually ruled out.

Logan understands this better than anyone. Although I will disagree with his assumption that the gasoline engine will become extinct. Gasoline engine technology will live on as liquid fuel engines because liquid fuel is such an efficient energy carrier. Electricity is an even more efficient energy carrier, just difficult to store in critical quantities right now, unlike liquid fuel which has sufficient energy density for our current activities.

Your blog made me realise how polarised people become. Once an idea is in the pipeline and being successful Most of us clamour for the product. BUT HOLD ON

If you get rid of batteries the cost of production tanks the weight of the car tanks the knock on effect of this weight and cost drop will include suppliers of batteries (no income and no profits) The reduction in tyre strength cheaper tyres ( income drop to the tyre companies etc.) NO POLUTION is the name of the century thats why there is no CONTEST to this Indian Car Company idea Get on board with cheaper transport no oil required if all the moving parts are coated with teflon.

Just nip down to your local Scuba diving store and get kitted out with the most efficient tanks pop it on your bike and you've got rid of road taxes as well.

That is why it won't get out of the stable every one loses money except the owner of the smartest car in the universe.

I've been working on compressed air vehicle designs for around 8 years now. I consider the very best solution comes from a battery-less hybrid air/electric system.

The worst part about compressed air vehicles as the referenced study indicates is the low efficiency of the compression and decompression stages. It releases a lot of heat/cold energy. In fact, compressed air engines produce far more cold energy than movement. When it gets to the comparitive stage (stored energy into movement), electric vehicles are certainly very efficient but when it comes to energy storage, are far from environmentally friendly.

Here's a concept for combining the two systems and eliminating the worst of each: We now have extremely efficient thermoelectric cells. Place the thermoelectric cells so that one side is exposed to the waste heat normally generated from electric motors that drive the vehicle. On the other side of these cells, simply release compressed air to chill them. The air can be passed by a series of thermoelectric cells and thus bring efficiency levels as high as possible. Meanwhile, the electric power generated by the thermoelectric cells drive the electric motors directly. The higher the demand for movement, the greater the cold energy produced, but also the greater the heat produced by the electric motors. Precisely what we want to maintain maximum efficiency without a need for batteries at all levels of movement demand. Any additional sources of heat or cold within the vehicle (whether considered "waste" or not) may also be used to further increase the electricity generated by the combination of released compressed air and thermoelectric cells.

Compressing air is another inefficient stage, but this also can benefit from the use of thermolectric cells to return most of the normally wasted heat energy into electric energy and thus effectively recycled. However, a solid state efficient air compressor can be created that simply uses differences in temperature to directly compress air without movement of anything but the air itself. It uses multiple stages where each stage raises the air pressure and thus is limited in pressure only by the storage tanks themselves.

Yet another "problem" with compessed air vehicles is the amount of stored energy in a limited sized tank. I've got a concept for getting around this one. Use a series of tanks where each tank is within the other and only slightly smaller. With each stage comes the ability to increase the pressure in relation to the strength of the tank wall. Thus, if we use 4 tanks, the energy capacity of the tanks is relative to the size of the external tank multiplied by average pressure, which in turn is related to midway between the pressure of the innermost tank and the outmost tank.

If we are to make widespread use of compressed air as an energy medium, then we need to decrease any effect of burst pipes. This can be done by providing redudancy through multiple parallel pipes and a pressure sensing / switchover system so that a burst pipeline may be repaired without interrupting supply.

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I've been working on a compressed air vehicle design for eight years now. The best design combined an electric motor drive with pneumatic energy storage and is more efficient than either pneumatic or electric vehicles. How? We now have extremely efficient thermelectric cells. Place them near the electric motors so that one side is exposed to the "waste" heat from the electric motors. On the other side of the thermoelectric cells, simply release compressed air to chill. There is no need for batteries. Electricity may be generated on demand.

I also have concept designs of a method of multipying the compressed air energy capacity from a given sized tank, either within a vehicle or otherwise. Another "problem" for compressed air systems is the ineffeciency of the compressor stage. I've got a concept for an air compressor that has no moving parts and uses only difference in temperature to directly compress air.

Yet another "problem" with compressed air energy systems is the possibility that a burst pipe will interrupt supply. A system of multiple redundant pipes with pressure sensing and switchover can handle this.

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if the car is inefficient then it shouldnt have even been made! it is a waiste of money if they start to seel these cars! if it worked then it would have been another story.

Is this article about the current latest model of the air car being less efficient than the current latest model of an electric car ?

Because if that is so, it shouldn't have even been published.

We expect both technologies to improve as we continue research into them. We don't know which one will end up being the most efficient. Unless you are reporting newly discovered theoretical limits to either technology then direct comparisons are of very limited value.

After reading your article, i've been on MDI website and they publish a warning about the paper that is referenced in this page :
http://www.mdi.lu/english/actualite.php

December 08 2009
Panic of traditional car lobby?

During the last week of November 2009, a study by the University of California at Berkeley concluded that compressed air vehicles from MDI were more expensive and more polluting than a conventional vehicle.

This study published by the Environmental Research Letters
(http://www.iop.org/EJ/abstract.../4/044011/) contains errors so big that its purpose is not scientific but is an act of bashing, pure and simple.
The response of MDI can be read here http://www.mdi.lu/charge.php?n...stakes.pdf

do the math a large 50 liter tank at 200 bar 2901 psi is only 1.5 kw or 3600 kj not enough stored energy to do much , my electric car stores 24 kw for 60 miles trip .

just simple math.