Voila! A Car Powered By Air

French Duo Says No Combustion, Zero-Emissions Vehicle Runs For Pennies Per Mile

(CBS)  With prices like these, maybe it's time to put some hard thought into what we could be filling up with. The Iranians say they have a solar-powered car. Engineers in the U.S. and Europe say they have tried hydrogen. But, how about air? CBS News correspondent Sheila MacVicar reports.

At their factory in southern France, father-and-son team Guy and Cyril Negre insist air power is no joke.

“It's a different way of thinking cars,” says Cyril.

Plain old air compressed in the tank, they say, cheap and non-polluting. Sound too good to be true?

“This is not a toy car,” says Cyril. “It's a real car. The other thing is it's a very zero emission car. You won't pollute, there won't be emission and the thing also, you have a very economical car.”

A car, says the Negres, that will cost just $2 for every 120 miles.

The Negres have a long love affair with cars. Guy designed a Formula One race car engine. Cyril worked at Bugati. The technology for their car, they say, is relatively simple and safe.

“When you compress the air in the tank, inside of the tank, this is like compressing a spring, and then the tank gives you back the energy of the air when it expands,” says Cyril.

Compressed air in a carbon-fiber tank, something like scuba divers use, drives the pistons and turns the crankshaft. There is no combustion and no gasoline. That's why there's no pollution. You fill it up at an air compressor. It may sound far-fetched, but at his labs on the campus of UCLA, professor Su-Chin Chow is also exploring the power of air.

“The beauty of this concept is air is everywhere and it doesn't generate pollutions. The main problem is the technology to make use of air,” he says.

Trying out the car, MacVicar says “It's a bit like driving a lawn mower.”

The Negres say after years of delays, even skullduggery, they have solved their technical problems.

“You know, it feels pretty solid,” says MacVicar. “It sounds like a lawn mower but it actually feels pretty solid.”

Another year, they say, and they'll be ready for large scale production, with a top speed of 55 miles-an-hour, floating on air.

[chipper777]

I believe it was in 1962 when I was very young and read a weekly reader that they had in grade schools, about France having a white vehicle that looked like an old nash rambler that ran with no tires and floated on aor using big fans. Any chance of anyone coming up with a story on that vehicle again? It looked really neat. They said however that when they pushed the lever forward, the vehicle went backwards and the other way, if the lever was pushed backwards.

[bobfox321]

The biggest stumbling block to fuel cell cars (and maybe air, but beware of the French) are the oil conglomerates and chains. There will be new BILLIONAIRES for he/she that gets us there first. Specially if we can retrofit our existing dirty gas vehicles ! This is a crtical step for the USA so we can stop sending our money for oil which in turn funds terrorism. GO AMERICAN INGENUITY.

[ms38654ob]

paulyn44,

Yes, they call it a hovercraft. There are several in commercial operation, one I believe still travels across the English Channel. The US Marines use them as landing craft too.

They will never be practical for every day use as they are very inefficent, are hard to control and are very noisy.

[RBojji]

Energy appears in various forms and it is incorrect to look at only a car and its pollution- the total cycle of energy production and usage has to be considered. Our civilisation has become a guzzler of energy and whether you take fossil fuel or nuclear energy as primary sources, pollution of earth continues. Hydro-electricity , to my mind seems a safe bet. Solar or hydrogen or compressed air etc have to be checked for the total life cycle of energy required to produce the components themselves, to judge. Hope some day we discover a way of using gravitons within our body cells to float away and appear wherever we want!

[rghay-2009]

Good Technology on the car powered by air.RGhay..

[kesac4650]

The big oil companies can no more stop such things than IBM could stop the personal computer. What will stop it is the cost/convenience factor. Air is compressed with energy derived from fossil fuels. A compressed air tank can only hold so much energy.
Like the old Volkswagen commercial that showed that a Volkswagen can definitely float.
These cars can definitly run, but cannot run indefinitly.

[agnim]

Good point, Ashlay; we should delude ourselves and ignore the potentially polluting source of the energy used to compress the air in the first place.

Seems like the whole french thingy is just a lot of hot/compressed air; but is that new with the fwench? LOL

[crtoo]

Great Idea. I have been waiting to see someone, somewhere use their brains to invent something that we can use that is free. MAYBE, the fist stages will use fuels INDIRECTLY to charge the batteries, but, that is really narrow thinking. From this point someone can work on the solar end to charge the batteries, and once the auto is moving, with a set of reducing gears a second generator can charge the batteries. Guess what after that it is all free of fuels and polution free, except for the production, paint, wax, soap, old batteries, waste metals and rubber left on the highways, sewars, land fills, etc. What happened to the generation that is supposed to "think out of the box"? This article should get people to push the auto industries to build earth bound vehicles free of polutants and a car that regenerates its own energy. The hydro concept is expensive and earth bound and uses a non renewable source-forget it.

[joeydog7]

CAR DRIVEN BY AIR ?? NICE, BUT OUR LOUSY, STINKEN COOKED GOVERNMENT, WILL FIND SOMEWAY TO KEEP IT OFF THE MARKET,,,,,,

[webdepot]

I have been touting this man's invention for the past two years.. I love all the naysayers comments which amount to: "well, it's not really running on air, it's running on the fossil fuels that compressed the air".. Technically correct and no arguement here, however, electricity is mass produced at the power plant and I would venture to guess the pollution at the power plant that equates to 2 bucks of electricity is very considerably less than the pollution my car produces now on a half tank of gasoline not to mention the fact, electricity is also used at the refineries to produce the polluting gasoline in the first place.
What is interesting though from this manufacturer's website is this: the inventor will be making his money by sellinng production licenses around the world. He has apportioned each country into zones, so he knows how many licences each country will have.
If you look at the map of liceneces currently sold, many european, middle east and south american countries are already sold out... the U.S., not one licence has been sold..
For my current driving needs, this vehicle would suit me just fine and although I consider the body design less than appealing, I would proudly thumb my nose at all the gas stations I pass in my daily travels...
Instead of denigrating a forward thinking inventor and his product, how about giving credit where credit is due..

[webdepot]

In response to the naysayers and carrying my previous post a bit further, lets look at ALL the polluting sources that go into getting your gasoline.... we can start here:
1-electricity used to get the oil out of the ground (and the polluting source of that electricity)
2-the pollution generated by the ships and trucks used to move the raw and finished products from point a to point b.
3-the electricity used to refine the crude into a finished product.
4-the pollution caused by burning the finished product..
I wonder, how many cars could be powered by the electricity used to produce gasoline..
This is, at the very least, a start in the right direction.. This vehicle eliminates the pollution from item 4... next is to tackle one of the remaining three steps and so on down the line..
Of course, for the naysayers again, a wind turbine or two in my back yard used to run the air compressor would make my use of the vehicle totally non-polluting, now wouldn't it??

Yes, anxiously waiting for the technology to come to the U.S.. I think it sould have been invented years ago but the oil companies were too greedy for that to happen. Now we have higher gas prices and the prospect still doesn't good

[webdepot]

This same gentleman is also working on a hybrid combo of combustion and air driven engines.. At city speeds, the car would run on air, at highway speeds, the car would run on combustible fuels (gasoline, ethynol, etc.)...
He is, once again though, thinking ahead as the car, when being powered by combustion, will also be replenishing the air tanks.. How cool is that??

[xxeroid]

It's cute, but is it practical? We now know it sounds like a lawn mower. My question is, how far will this thing travel on a tank of air before you have to refill it.

[cantshutup]

Please see WHO KILLED THE ELECTRIC CAR? A car that runs on air is wonderful, but we already had an electric car which was killed by GM, the government, and the Oil/Automotive industry. When the oil corporations realized there was supposedly still 3 trillion barrals of oil still in the ground, they helped kill the electric car. Everything is about profit with these people and there won't be alternatives in America while they can still make a profit and still control our lives.

[webdepot]

xxeroid-
Acording to their website, current capacity allows about 200km (120) miles) on a tank of air.. not yet ready for the long haul highway trip, but very practical for the around town trips to the doctor, grocer, church, etc. and since approximately half the drivers today put in less than a hundred miles per day, would go far toward reducing pollution, even at it is currently available.

[selrach_us]

Agrim

I gusee we should throw out the concept of vacinnation because the French invented the concept Louis Pasteur. Sounds a bit gingoistic.
Heck we are already burning the fossil fuels at generating stations.

The question is:
Would the increased fossil fuels needed to power air compression be more or less that the fossil fuels being burned by millions of people throughout the world in their individual cars?

Only some scientific calculations can answer that.

[webdepot]

cantshutup-
I read that article too... sad that the continued investment/development was dropped, but there were also practical reasons for it's death.
1- The batteries are hughly expensive.
2- like all batteries, they had a finite life span as to how many times they could sustain a full recharge.
3- weight, batteries are heavy..
Even with these shortcomings though, I think the avenue should continue to be pursued. You never know when a breakthrough may come forth.
I'm sure the oil industry (of which both Bush and Cheney have a heavy involvement) will also try to thwart this vehicle.. you can't sell shares in air. LOL... Their options would seem to be limited though... although I guess they could refuse to install the high capacity air compressors (needed to refill these cars) at their franchised dealers.. but would only spawn a new industry of "air stations".

[cacee13601]

with a top speed of 55 mph its useless cuz the speed on I 81 in NY is 65 and nobody does the speed limit any more so when you get into an accident youd be liable for driving too slow

[webdepot]

cacee13601-
That's funny... I dive 81 frequently myself... it is far from level, but rather a continual gyration of up and down hills... and while loaded tractor trailers may get up to 75-80 on the downhills, they struggle to do 50 on the up hills, so your arguement on liability is BS and you know it...
I suppose if the ONLY driving you do is on the interstate, then yea, maybe this car in its current state of development is not for you.. for my needs though, which is mostly in town driving, it suits the need perfectly... for those longer trips, the second family car could be used.. or you could rent one on the money you save on gasoline.
Like any invention, or any product for that matter, it is not for everyone... but for those that can make use of a new product, it can be very rewarding.

[pafaib]

Ok here is the thing these cars wont be out for a loong loong time. Because these big oil companies wont let these cars come out because it will hurt thier multi-billion income.

[pafaib]

Ok here is the thing these cars wont be out for a loong loong time. Because these big oil companies wont let these cars come out because it will hurt thier multi-billion income.

[pafaib]

Ok here is the thing these cars wont be out for a loong loong time. Because these big oil companies wont let these cars come out because it will hurt thier multi-billion income.

[dbstevens]

The comments about the limitations of this invention are valid, but let's not forget that this is an introduction of something new. Like any such new application, improvements would come with time. We shouldn't expect the first such vehicles to be practical. Electric cars were first introduced in the 1800's and they're only now in production in any meaningful manner. That's because consumers made it clear they wanted them...so the suppression of the electric car was defeated. Development of clean, inexpensive technology will continue if we make it known that we WANT this.

Wo what we should do is to keep communicating about this, spreading the word and insisting on the development of such technology. We have a new weapon to fight suppression such as what happened with the electric car....the internet and our collective voice. So let's keep this idea alive and let the "powers that be" know that we will not stand for suppression of beneficial technology and that we insist on environmentally safe technology. This world does not belong to government and big business, it belongs to us.

[talsian]

Okay, did some research. range is 200-300 km (about 150 mile average). 3 mins to recharge at air pump, all night if hooked up to standard electrical outlet, 4 hours with special souped up outlet. Price not set yet. Cool enough. Put a solar panel on your roof and become carbon neutral.

[slabslab99]

No, it's not new. Using the release of compressed air has been demonstrated many times before, but perhaps not this close to a commercial model. In fact, there was a beautiful demo at the Hybrid-Electric Auto Show in St. Louis 1976. There have also been demonstrations of the air powered cars that use liquid air, instead of compressed gas. The air motors are not particularly efficient, do not have a very long life, and they can be very noisy. Air motors are comonly used in industry where there is already a source of compressed air and where they do not want to run electric power. Vane-type motors have low efficiency. I suppose it has to be taken into consideration that there is no chemistry/batteries to dispose of. It is a simple technology.

[anomalous4--2008]

The 55-mph top speed need not be a limitation depending on the kind of driving the owner does. For errand-running about town or a short commute to work, this car would be ideal.

I know this from my own experience. I live out on the edge of the suburbs where public transportation is nonexistent, and my "car" is a motor scooter. I'll ride anywhere within 20 miles (limited by the ability of my 50+-year-old rear end to tolerate the uncomfortable seat) as long as it's entirely on city streets or back roads, the streets are dry, and I don't have much to carry.

For longer trips, trips that require highway driving, include heavy or bulky loads, or trips in bad weather, I pay a friend a few dollars to give me a lift, and I coordinate trips as much as possible with him so as to minimize the inconvenience.

With my driving habits, I'd be more than willing to consider an air-powered car. It would remove the bad-weather and carrying-capacity limitations, extend my range somewhat, and cause far less inconvenience for my friend. Since I'm already accustomed to city-street and backroad driving, not being able to drive on the highway wouldn't be all that serious an issue.

As far as I'm concerned, the only real limitation is the absence of "fueling" stations. Get those in place, give me a few thousand dollars, and get in line behind me!

[slabslab99]

This is really an old idea recycled to gain new attention. Consider a scuba tank containing about 80 cu ft at 200 bar only has the potential to return little more than 1 hp for 1 sec. And this is at 100% efficiency. I dohbt you could achieve 30% w/adiabatic expansion. You could use larger 240 cu ft tanks, 300 cu ft tanks, etc. These may offer a higher energy per pound mass. You need a lot of highly compressed air just to run to the store and back - I don't think anyone realizes this. At least they do use motors that are more efficient than vane-type. Another problem is that it is complicated extracting all the energy from a system when the pressure is constantly dropping, then to a transmission with torque/rpm demands that go up and down. The article makes it sound like you fill up your tank like a big tire then drive off. They do give you a clue - $2 worth of electricity. That's a ton of electricity at .10 cents per kw hr. It's easy to compare this to the cost of gasoline, but that's not an accurate comparison. Besides that, someone still needs to invest a lot of $ in the high pressure compressor, and the other expensive apparatus to remove H2O from the air or the tank will have a bunch of water in it. Not cheap. By the time you get through doing all this - no wonder engineers have consistently chosen electric. There are still other technologies which have been otherwise rejected, that are superior to the compressed air stuff. Besides, it's not really zero emissions.

[slabslab99]

Correction - 2 mins, not 1 sec.

[slabslab99]

I keep going over the numbers on this and I can't see how they can claim the range they do, as mentioned in previous posts. Anyone who makes comments about Cheney conspiracies and Big Oil probably believes in alien abductions. You could consult with any number of other engineers on this. I worked through ideal cases using ten scuba tanks of woven construction which are safest and lightest and won't corrode but are very, very expensive. Larger tanks contain more energy per unit mass but more smaller tanks can be switched to maintain relatively higher system pressures. The hype in this is plain stupid. Forget about driving on the highway at even 55mph. It's ridiculous. Even a 700kg car would exhaust one 80 cu ft tank getting up to speed. Ten tanks would allow you to putt around a while but is still impractical. Believe me, this idea has been around a long time and it just plain fails again and again. At the University there are references to this being done even before 1976. It does work and it is interesting and there is nothing to prevent you from doing this yourself. A variable displacement air motor would work best but I don't know who makes one for this application. Even using a hydrostatic transmission with fluid power being simply charged by the compressed air in accumulators would be better than this.

[slabslab99]

Again, take the time to price an air system, even a Haskel amplifier if you already have large shop air available, then the downstream apparatus. It may cost more than the car itself. It requires final scrubbers that need replacement/replenishment. The air doesn't have to be as clean as a scuba charge, but you can't just pump air into the tank. And if you don't want to buy a system yourself, who do you think is going to, then charge you just $2 to "fill up" your car? Good grief. Try to get a scuba tank filled for $2. Check with the fire dept and see if they can even get a truckload of Scott AirPacks filled for $2 each. Maybe the cost is kept artificially high because of another conspiracy. There are at least four other serious drawbacks with this idea that haven't even been mentioned, yet.

[jw218389]

HALLIBURTON and Exxon will stop this!

Bush/Cheney/666 Inc. will stop this because it is anti-Saudi American ;-)

Godspeed to compressed air! You would have better luck flying to the moon...

[nothappyatall]

A few problems;

1)A small leak in the system, your air is gone

2)Imagine the pressure inside that tank, ever seen a picture of someone near an air compressor tank that blew up from a weak seem? I have, it took the top half of his head clean off.

3) There is NO "zero emissions" the emissions are simply transferred to the power plant which has to generate the power for the air compressor to fill the tank.

[dhague]

This is a lot like the stories of "pollution free" electric cars.

A compressed air car is anything but pollution free, since it takes energy to compress the air in the first place. Since some kind of power plant is necessary to produce the energy to drive the air compressor, we're still talking about a power plant that either burns some fuel or produces reactor waste.

It probably wouldn't be particularly silent, either. Compressed air makes a racket running through any kind of pipes and valves. It's mostly the moving parts in a gasoline engine that you hear, and those wouldn't be much quieter running on compressed air.

There are many facets of this challenge to consider, a signficant one being pollution and this one is not free of them (compressed air production and significant noise). Although an admirable effort, the ultimate solution will need to include consideration of all aspects from the molecular to the universal scale, including pollutant considerations. Hydrogen has promise, but solar energy seems the simplest, most readily available and abundant alternative. It can provide the most efficient form of energy known to mankind with minimal impacts. Once a solar energy collection infrastructure is developed and in place, energy production could be self-supported from collection through delivery. This scalable solution could provide a major attack against terrorism by localizing and providing self-supporting energy collection and distribution. Using the existing energy grid to support this model versus being primary energy source and delivery mechanism would remove the vulnerability of dependence on larger points of failure, reliability on foreign and domestic fossil fuels, and significantly reduce pollution.

[prelgovisk]

One way to improve the use of compressed air in transportation is already feasible. A brake system connected to an internal compressor can partially recharge the compressed air tank every time the brake pedal is used.

Compressed air as a power source is more feasible than the critics make out. It was widely used before Edison and some of the old technology could easily be updated for use in power transmission. And not just in cars, but for use in factories and homes. Energy to compress air need not come from oil or giant electric plants at all. There are mechanical ways of compressing air and even solar, though slow, will work. Got a bicycle pump or an Exercycle you can hook up to a compressor? Cancel your gym membership and recharge your car yourself!

I doubt if we would be fighting in Iraq now if our cars were powered by air. That should be factored into the %u201Ccost effectiveness.%u201D It seems the cost effectiveness of an oil based transportation system is not so good.

The only real problem is that it is hard to get a monopoly on compressed air, so big business will oppose it.
Maybe we need to use our collective anger against terrorism to decentralize and de-monopolize energy. Air power is a step in that direction. It is a step worth taking. Give air a chance!

[tulcak]

There are always naysayers... people who can't imagine anything other than the status quo... we've always used petroleum - so anything else must be impossible... there are too many problems with the new technology, so let's not try it. I guess we should wait until its too late...

[indymike1959]

I noticed the total lack of any reference to the distance this car would travel at an urban cruising speed of around 40 mph with a prectical onboard supply of compressed air. And how would carbon fiber tanks resct to a collision? I suspect that anyone who has ever blown up a balloon, then let it fly will see the folly of such a power source as compressed air. Perhaps that is the answer: take a couple thousand balloons, blow them up, connect them to the "engine" in this car, and let er rip! lol

[indymike1959]

I noticed the total lack of any reference to the distance this car would travel at an urban cruising speed of around 40 mph with a prectical onboard supply of compressed air. And how would carbon fiber tanks resct to a collision? I suspect that anyone who has ever blown up a balloon, then let it fly will see the folly of such a power source as compressed air. Perhaps that is the answer: take a couple thousand balloons, blow them up, connect them to the "engine" in this car, and let er rip! lol

[cbsnewsblog]

newster1 -
The 3 "problems" you list apply to any fuel based system, but even more so with today's vehicles:
1)A small leak in the system, your "fuel" is gone
2)Imagine the pressure or "combustable fuel" inside that tank. Remember Ford's Pinto, and most recently, the Crown Victoria?
3) There is NO "zero emissions" the emissions are simply transferred to the power plant. It's just a fraction of the carcinigens released from today's petroleum powered cars AND the plants which manufacture the fuel.

Clean fuel technology can overcome all of these today.

[donrobertso1]

I like the idea. It's simple. And for those naysayers worried about pollution, a SMALL windmill would pump the air pressure at zero emissions. It's a solution that perhaps will never happen, but, there is something there for someone.

I also have an idea shared with me by an old buddy recently passed away. Roy Moody, died last February at 89, 1917-2006. Old Roy used to tell me you could run a deisel-like engine on water.

Here was his thinking, and it's sound enough for someone to tinker with. Water under pressure converts to steam, and steam expands. So instead of deisel fuel, use water. It sounds like there's a conservation of energy problem, but if you think long and hard enough about it (I had to think about it for ten years) there isn't. Water exists in both steam form and liquid form in the same environment. It's a balancing act for water.

I'm telling you, we don't need the oil. And I'm also telling you, we need the environment. It's a question of engineering coupled with some mighty fine philosophy.

Enjoy, but don't trash the place.

Don Robertson, The American Philosopher
Limestone, Maine

An Illustrated Philosophy Primer for Young Readers
Precious Life - Empirical Knowledge
The Grand Unifying Theory & The Theory of Time
http://www.geocities.com/donaldwrobertson/index.html
Art Auctions:
http://www.artbyus.com/auctions.php?a=6&b=4807

[webdepot]

To all the world reknowned mechanical engineers that have posted to this thread, it is the thinking of goons like you that are keeping the USA down.
There is only one poster that appears (based on the facts he/she presented) who bothered to find this company's website and get an education..
The naysayers can now get your heads out of your butts: http://www.theaircar.com ... read and learn... every question posted here has been answered at the web site (which is poorly designed and difficult to navigate, click every link and be patient).
As for the genious comparing this vehicle's air tanks and performance to scuba gear, you are comparing apples and oranges... not even close..
When ruptured, the air tanks do not explode and are, in fact, the same style of air tank that is currently in use in UPS's natural gas vehicle fleet.
"there is no such thing as zero pollution"... sorry, this vehicle is zero pollution... it is not the fault of the car or the manufacturer that we can't produce electricity without pollution, but the vehicle itself is zero air pollution. The air that is exhausted is actually cleaner and cooler than the air that went in and since there is no caustic by-products that would be produced in conventional gasoline cars, it's lubricant (1 litre of Wesson oil) is good for 30 - 40 thousand miles.

[captain1246]

Air power tools and machinery have been in use for years. A compressed powered car should be a natural.

[nebrjack]

Good concept with potential. However one wet blanket item: gas taxes. Most of our road mainteanace and construction is funded by the taxes we pay on each galon of gas that we purchase. There will have to be thought given to replacing those maintenace/construction funds before there is wide spread use of either air powered or electric vehicles.

[webdepot]

LOL.. hey nebrjack... do you really think our government, of either party, will have any difficulty at all in coming up with innovative ways to tax the air that is used to propel a vehicle... silly...!!

[slabslab99]

You can get nasty about it if you want, but that won't change the facts. The danger to the US if anything, is from too many that barely made it through high school and not enough educated engineers. I know you would prefer NOT to be confused by the facts, but at least one person took the time to deliberate on this idea because of keen interest and actual experience. You can get nasty if that's what you do.
The comparison was made to scuba tanks because the article itself mentions that. Also, because you don't know - 1) scuba tanks are non-shat themselves 2) woven tanks are very expensive, especially cf.
The engineers here DID visit the website and actually studied the numbers presented there which webdepot probably found confusing.
It is the website that adds to the practical doubt more than anything else, in fact. Revisit the site and read beneath Actual Tested Prototype. No one doubts that it actually works.
The engineer(s) are simply stating they doubt the practicality of it. A long list of other problems have not even been mentioned. Go buy one - who's stopping you?

[slabslab99]

Not sure it's even possible to have an intelligent discussion of this car idea. Many are looking carefully at it from all directions - the good and the bad, only to be called names and be charged with standing in the way of progress. Good grief. I can list a dozen ideas which newpapers took and ran with. Uneducated people got excited about them, but the ideas were full of holes. They simply faded away. I guess all those were really good ideas but bad engineers killed them. How many people still believe there was a 100mpg carburator, or that magnets on your gasline could increase mileage, but couldn't be told otherwise. These guys in France can be admired, and again the car does work. But I'm not impressed by cavemen that read soemthing on a website then start screaming vulgar names at others, then expect to be treated like they know what they're talking about. Is that what makes the US great? Apparently.

[slabslab99]

BTW - the fact that the exhaust air is cool demonstrates the adiabatic nature of this expansion. You don't want adiabatic expansion. That is a big source of inefficiency because it represents wasted energy that can be used for propulsion. It is energy that was used to compress the air. That's why the bigger system is better, in fact, it has to be quite large or a lot of energy will be wasted.
When the air is compressed it gets hot, so the tanks cannot be filled rapidly unless they deliberately over pressurize and stress the vessels. When the gas expands it cools. Switching back and forth between numerous smaller vessels would help, but this adds to the cost and complexity.
Crack a high pressure tank wide open and let the valve just dump the charge as fast as it can. It will be covered in frost. It is a virtual refrigeration cycle and something that the French developers still have to overcome.

[slabslab99]

BTW - just because a tank is no-shat doesn't mean it isn't dangerous. It only means it isn't expected to produce shrapnel. A burst high pressure tank will still blow the roof of a house off and they have. You have to overdesign, taking into consideration the heat these tanks can be exposed to, sudden shocks such as in a collision, too paid filling, etc.
These French guys don't have some magic cf tanks. They're the same ones you can buy now. They're just not cheap. Even though they are already being produced in good quantities for the aerospace industry. NONE of this changes the dynamics of the propulsion system.

[slabslab99]

I sincerely wish these French developers good luck. But, for all of you that think this is such a good idea and that anyone who brings up practical problems based on knowledge and experience - I have just one question for you.
Where the hell were you for the past several decades while AMERICAN entrepreneurs and small companies spent tons of money and time in garages and basements to develop and test the compressed air idea, flywheels, countless electric car ideas, fluid power hybrids and so many other ideas? They worked hard and smart, and I guarantee you they weren't web droids that disliked engineering. They took enormous chances, and continue to do so. Where were you?
You read about this stuff on CBSNEWS and just start attacking engineers - that scares me more than anything, that YOU might be lurking as America's big problem.