What About Compressed Air Cars?

one small issue with compressed air. . . BOOM! It's allot of energy being held in a volitle form. It would make car accidents allot worse. And trying to protect the air tanks against impact may just make the care less efficient by adding too much weight.

I agree the aircar is an interesting idea with great potential, but I think we have to start seriously considering banning the private automobile on public roads. The real energy savings will come from more compact cities and bicycles.

"one small issue with compressed air. . . BOOM!"

The same can be said of gasoline cars, y'know, and yet people drive them.

I think it wouldn't be too easy to create air tanks that can withstand quite a bit without any technological breakthrough in that area.

It's also probably possible - like with hydrogen tanks - to make it so that when they rupture they don't explode but just empty really fast.

emptying really fast is what an explosion is.
air cars sound nifty.
i would still ride my bike though.

"emptying really fast is what an explosion is."

Obviously I meant emptying in a controlled manner.

Ken Heronheart,

Where are you living that this is a viable option?

nothalo

Compressed air, or nitrogen, has several advantages over hydrogen.

• Compressed air is easier to contain. Hydrogen is so small that just by leaving a hydrogen tank sit it looses hydrogen.
• There is already infrastructure in place for creating massive amounts of compressed air (check your local home center for air compressors)
• Compressed air is not a fire hazard, only a rapid depressurization hazard (this can be mitigated by using carbon fiber tanks like firemen do)
• Air turbine technology, closely related to steam turbine technology, is a practice over 50 years old. It is simple to achieve with low tech materials. This would mean that developing countries, and rapidly growing countries like China and India, could easily implement a less polluting means of personal transportation than an internal combustion engine automobile.

Hydrogen is only being used as an energy storage medium. Compressed air, batteries or wound up rubber bands can do the same. I for one do not want to jump on the hydrogen band wagon just because the buy product of the energy transfer is water. What about the byproducts of creating a hydrogen car in the first palace? All of the heavy metals that need to go in to the fuel cell. all of the new materials that need to go into the hydrogen production units.

http://www.theaircar.com/

http://quasiturbine.promci.qc.ca/
has a nice little compressed air engine.

>Ken Heronheart,

>Where are you living that this is a viable option?

>nothalo

Do you mean politically viable or technically viable? I live in rural Wisconsin. Technically, I think it's quite viable. Obviously, a lot of people would have to move closer to their jobs and a lot of jobs would have to move closer to their people but it can be done. Before cars were so heavily subsidized, small rural communities were much more vibrant places which were able to supply jobs and commerce to their residents and near residents. Even now it's possible for me to call a cab if I really, really need to go somewhere that I can't reach by bicycle. If we as a society were to stop subsidizing private automobiles, we could afford a truly impressive public transit system.

Politically, it would be very difficult, but if no replacement for cheap oil is found, then it will eventually have to happen. If we humans are serious about not degrading our enviroment then we need to start now. The energy and material costs of far-flung suburbs are simply too high.

Anybody got stats on the energy density and power densities of this compressed-air engine? It's nice to talk about how cool this thing is but unless we see some actual numbers, we don't have much to make any real comparisons to. How far can it drive on a given charge of how many watts? How much power does the drive train deliver? etc.

Anybody got answers? I'd apprecaite them.

BTW, the Energine website is pretty useless unless you can read Korean. The english translation is terrible and all the useful stats and numbers are still in Korean even on the English language page.

The How Stuff Works link above describes a French non-hydbrid compressed air car that drives up to 124 miles on a compressed air 'fill-up' that can be recharged by a compressor at home. Top speed is only 60 mph and the range is still about half of what you would need to be commercially viable. The hybrid application may be better as it should give you extended range but I still dont see anything on how far it can go on how much charge etc.

I'm still waiting for these numbers too Jesse.

This model

http://www.treehugger.com/files/2005/01/minicat_air_pow.php

Has a range of 300 km and runs on air only, but it seems pretty small.

I suspect that the air-electric hybrid will be the best way to do this; after all, we already have electric cars that are close to having useable ranges (and they already have really good performance), so with a compressed air drivetrain added the specs should become very interesting.

Regarding compressed air energy content:

You can compare a container of compressed air with an equivalent volume fully-charged Li-ion battery. If the air pressure is 5000 psi (like many scuba tanks), then they contain the same energy. If you need a formula, try this:

W=Vo*Patm*[(Vf/Vo-1)-ln(Vf/Vo)]

where:
W=energy
Vo=uncompressed air volume
Vf=compressed air volume
Patm=pressure of 1 atmosphere

If the air pressure is 5000 psi (like many scuba tanks)

Isn't that 3000 psi, or 200 bar?

The following is from www.theaircar.com

Compressed air tanks

One of the most frequently asked questions is about the safety of the compressed air storage tanks. These tanks hold 90 cubic metres of air compressed to 300 bars. Many people ask whether this system is dangerous in case of an accident and if there is a risk of explosion. The answer is NO. Why? Because these are the same tanks used to carry the liquid gas used by buses for public transport. The tanks enjoy the same technology developed to contain natural gas. They are designed and officially approved to carry an explosive product: methane gas.

In the case of a major accident, where the tanks are ruptured, they would not explode since they are not metal. Instead they would crack, as they are made of carbon fibre. An elongated crack would appear in the tank, without exploding, and the air would simply escape, producing a loud but harmless noise. Of course, since this technology is licenced to transport an inflammable and explosive gas (Natural gas), it is perfectly capable inoffensive and non-flammable air.

It is fitting, therefore, that MDI has reached an agreement with the European leader in aerospace technology Airbus Industries for the manufacture of the compressed air storage tanks. With a remote supervision arrangement, Airbus Industries oversees the making of the storage tanks at each MDI factory. The coiled carbon fibre technology used in the construction of the tanks is complex and requires a substantial quality control process which the multinational company, home of the Airbus aircraft, will provide for our vehicles.
Arriba

Okay, kinda corny but I watched mythbusters on discovery a while back where they were (dis)proving elements of the movie "Jaws". The climax of the show was trying to blow up a (fake) shark by shooting a bullet into a scuba tank. To cut to the chase, no explosion - though the tank did go airborn and ping around the container they were conducting the experiment in. Perhaps pressured air tanks are safer than expected.

The problem with CA is that the devices that capture air for storage are notoriously inefficient and that devices that convert the CA to mechanical energy are no better. The whole CA concept from an energy in to useful energy out is dismal. Better off with electrical motors.

The Air car from the french inventory is a scam. Let's face it, the man has been working on it for 15 years. The car was to go commercial any day now has been a statement since 1995.

There is no practicle evidence to support all the hype.

The ranges are supposed to be about 200 miles on a 60 gallon tank. The advante is you can use a rotary engine that uses an air lubricant.

There is an issue with expanding air - it cools, which reduces expected volume by 20%. I am working on a technique for a rotary engine to handle both combustion and compressed air. That way the engine can get heated, and increase the effiency.

The problem with the combustion engine combination is that it needs lubricant.

By the way a compressed air tank is designed to crack not shatter. The idea is to prevent shards from flying in every direction.

How many types of air engines are out there? I know of rotary and piston in different configurations. Who makes engines availble on the open market?

There are basically 4 types, which can be broken into 2 groups.

Piston and non piston.
Piston can be configured in a standard 5 or 6 cylinder block, or the pistons can be placed in a circle creating a rotary engine.

Another option is to have a central mass that allows air to pass only when it is in certain positions. There are less moving parts but it is less efficient, because the air needs to fill a larger space (higher Torque less HP).

The other option I have seen is that the air travels in a space in the central axis, and as it spins it lets the air flow. It is different in that the air is not filling a chamber around the axis. It is filling a small void in the axis itself and as it spins it finds an oppening for it to escape. This is the engine that is supposed to be 100% better than all the rest.

Piston can convert 30%-40% of stored energy to mechanical.

I have not seen any engines prefabricated, but there are some plans available.
Most compressed air engines do not need a transmision, just a flow control. My guess is they are trying to find a balance for HP and torque.

Since they are designed to be small at 20lbs or less, most vehicles will get 2 or 4.

I am an emerging inventor-
entrepreneur that is working
on developing an elecro pnuematic drivetrain system.

I originally conceived the idea back in 1992... but there
was no one talking about eliminating gasoline as a fuel
source back then, and I was
made fun of by my piers.

I have started a cycle company
to act as sort of a proving ground for the system I have been working on designing.
Once I get a light wieght prototype to work satisfactorily on a recumbent
trike and possibly on a custom motorcycle... I will
move into the auto industry.

We Americans criticize the Muslims for the violence that has ensued over a bunch of stupid political cartoons...
But have you ever thought about how the oil industry would react if someone like you or me were to market a disposable automobile that doesn't use gasoline?

I am walking on egg shells
hoping to gain wealth and fame
for my efforts... but I would hate to have to bear the full
wrath of the oil industry alone.

I am an emerging inventor- entrepreneur that is working on developing an elecro pnuematic drivetrain system. I originally conceived the idea back in 1992... but there was no one talking about eliminating gasoline as a fuel source back then, and I was made fun of by my piers. I have started a cycle company to act as sort of a proving ground for the system I have been working on designing. Once I get a light wieght prototype to work satisfactorily on a recumbent trike and possibly on a custom motorcycle... I will move into the auto industry. We Americans criticize the Muslims for the violence that has ensued over a bunch of stupid political cartoons... But have you ever thought about how the oil industry would react if someone like you or me were to market a disposable automobile that doesn't use gasoline? I am walking on egg shells hoping to gain wealth and fame for my efforts... but I would hate to have to bear the full wrath of the oil industry alone.

I am an emerging inventor- entrepreneur that is working on developing an elecro pnuematic drivetrain system. I originally conceived the idea back in 1992... but there was no one talking about eliminating gasoline as a fuel source back then, and I was made fun of by my piers. I have started a cycle company to act as sort of a proving ground for the system I have been working on designing. Once I get a light wieght prototype to work satisfactorily on a recumbent trike and possibly on a custom motorcycle... I will move into the auto industry. We Americans criticize the Muslims for the violence that has ensued over a bunch of stupid political cartoons... But have you ever thought about how the oil industry would react if someone like you or me were to market a disposable automobile that doesn't use gasoline? I am walking on egg shells hoping to gain wealth and fame for my efforts... but I would hate to have to bear the full wrath of the oil industry alone.

Korean Air Car!

Ive seen test of a propane tank put in a fire after witch it released its presure without exposion. just a large flame for some secounds. in the case of air that would not even happen. i would like a air car :)

I would like to tell Mr. Carl Stone that comparing the Danish cartoons insulting Prophet Mohamed (PBUH) to him inventing or "were to market a disposable automobile that doesn't use gasoline?" is not a fair comparison.
Not all Muslims are rich because of oil and not everyone who exports oil is Muslim.
Years ago, during a psychology class I took, our professor told us that gasoline engine manufacturers in the United States bought off an inventor who got a patent for an engine that ran on wood chips!!!!!!!
Why do you think I found this blog? I am VERY interested in the world losing interest in petroleum. When that happens, America will get off our case and leave us alone.
Maybe then we'll finally realize that we have to do real work and produce as God intended for people to do.
As for Muslims getting angry, most people in the West would never know what it feels like unless someone insults the Pope or maybe claim that the Holocaust didn't just happen to the Jews (which is a historical fact, by the way)...
So, PLEASE, go on and invent what you're trying to invent. You'd be doing the world a favor. And before worrying about countries in the Middle East, worry about companies in America who in the first quarter of 2006 made $8 billion profits off of petroleum!

Look its simple -

1)

You won't keep private cars out of the city/urban ares without better, faster and reliable public transport.

That is A LONG WAY FROM NOW.

2)

Frumpy looking new age/tech devices like CA power cars, Electric cars, whatever can't be homely looking period. Sorry about being completely green only excites "Egg Heads" and that is not what drives popular culture.

Cars are very much an extention of your personality. If you view a car as another applances like your toaster, then I guess you can live with boring looking and driving cars like the Pirus and Honda Insight.

I drive a 4 cylinder turbocharged car that will show its tailights to many V8 powered cars. Which I enjoy and I do use that power where it beylongs on racing tracks. But I do goose it to get on the freeway and on occasion visit 100mph for a short period of time.

That's why shows like Top Gear are so popular in Europe and here in American.

Lexus has introduced a hybrid powered GS450H and its faster than the gas version, while delivering a 20% improvement in MPG.

Those are the kinds of things that push "green tech" forward. Not funky looking things that only excite nerds and egg heads.

CA can work as was stated, I drive trucks for a living and tankers haul compressed air with no ill effects.

Given that many of you 4 wheels cut-off trucks at any given moment, Im surpised nothing has happens already.

Get your heads out of those text books. Life is about LIVING it, not reading about it.

after reading everbodys views on this site. i think that atleast there is something being done to get away from the use of oil. ive been working on a comppresed air engine since the 70s. i tryed getting help from big auto companys but iam a nobody .you need alot of money to make it happen. there is a lot of smart people out there and i feel that the way things will change is if they let it. i wish i had the money to build my engine .and if i did would it make it to the open market.now that the government is fighting pollution everone is coming out with there ideas i hope you good luck.

Air Engine technology has been around for over 100 years. If you want to know where to go, know where you have been. The secret to the air engine is efficientcy. The second secret is self fueling. Only one low pressure cylinder can be required for this. (T1&P1CAN=T2&P2)Be careful not to step on the toes of the automakers. They will rebuke with bad intensions. Air engines can and have been built that were good designs. Principals of expansion are completely different than that of combustion. Learn that and your eyes will be opened. The "Boom" theory is unjustafied. No one ever died from a blast of compressed air. But many have burned from gasoline tank explosions.

Am a student of mechanical engineering, and am interested in doing some project on compressed air engine. The problem is am not getting sufficient information and ideas about the project. so please help me as soon as possible.

after reading all the opinion, I think air engine is a explosive innovation if we can market it from the small vehicle or toy like skateboard before the technology is practical for Auto. But May I know who ever build a self-fueling system. (air engine 0r air compressor) Plaese share with us your opinion.

My car in an fourteen year old ethanol car. It is very economic: I sometimes can find 1 liter of ethanol at R$ 1,27 that is equivalent at little more than US$ 0.57 per liter. And with this fifty seven cents of ETHANOL here in Brazil I can ride over 11 km. It could improve if we consider that the aerodinamics of 14 yrs old cars are not good

And uau how it runs . I do have an Old 1.6 engine but in this month in a 4000 km trip I traveled with higher 160 at 170 km/h speed. It was incredible. It could be better if we consider that the 14 yrs old cars are steel carburated cars.

And the smell, ha the smell it's too good. It seems that we are preparing a very good hot drink. (those ones that we put fire).
So I don't understand why the people don't use more alchool cars.

I f anyone knows of or hears of an air motor that produces enough torque to power a small car please let me know thanks Tom
tom_walsh_rn@hotmail.com

What a great idea! Just think of the pollution levels dropping world wide, less oil spillage throughout the oceans, a very green idea indeed! Unfortunately the technology won't be administered in the United States due to the fact that the petroleum industry still lobbies congress and the senate, always to have their way! For once I'd love to see our great U.S. do something for it's people and for the planet Earth before it's too late. Enough already with the price gouging of the oil industry, enough with their billion dollars in quarter earnings each and every quarter. Give the public what they want and need, greener, cost efficient vehicles!!!!!!!!

"one small issue with compressed air. . . BOOM! "

the tanks that hold the air are made of fiber. The tanks won't explode like metal ones would. They would just make a loud sound when they cracked. Do some reaserch.

A German air car manufacturer used carbon fibre tanks to hold the comrpessed air, this means in case of a explosion the tank will only shatter into small fibres and not metallic shards.

Let me help you guys out. The problem I find with all these blog sites is that everybody has an opinion, but nobody has done the actual math to determine whether a particular solution is or is not feasible. Anybody familiar with the concept of the electric car will know that the major limiting factor is energy density, meaning we don't have batteries light enough or small enough to store the required energy to drive very far. From Tesla motor's website, a small, very efficient sports car has been developed with can travel 250 miles on a single charge. The batteries store 45 kWH of energy, or 162 million Joules (kg*m^2/s^2). If we want comparable performance from compressed air, we need to know how much energy we can store in a tank. As of now, the highest pressure rated tanks I can find on the market store compressed gas at 10000psi, or roughly 70 million pascals (Newtons per square meter). 1 Newton equals 1 kg*m/s^2. The energy in a tank is measured as the pressure times the volume. So how much volume do we need to achieve an equivalent 45 kWH of energy to drive our 250 miles?

Energy = Pressure*Volume

Pressure = 70 million kg*m/s^2
Energy = 162 million kg*m^2/s^2
Volume = Energy / Pressure

So the required volume for the tank is 162/70 cubic meters, or 2,300 litres, or 600 gallons, meaning the tank is as big as your car. This is assuming 100% efficiency, there will of course be losses due to friction and cooling as the gas expands. So as far as I can tell, unless you want to tow a 600 gallon tank of compressed air at 10000 psi behind your car (IE a huge accident waiting to happen), this isn't going to work. This is why air is being used to power wagons in fruit markets, not cars on public roads. The little wagons don't need to drive as far, or as fast.

I agree with J wholeheartedly. Engineers have been working on this issue (energy storage vs. weight and volume) for a long time. Fuel cell technology seems to be the best approach that has come down the pike in a long time as far as weight vs. energy.
Compressed air on the other hand, was abandoned long ago by all but the most technically inept. The efficiencies of air motors are extremely low, and the storage of energy is likewise abysmal when you take size and weight into account.
The main thing that most of these posts seem to overlook is that you have to take the air compressor itself into account. These are not all that efficient, and take a lot of electricity to run. You're converting that electricity through inefficient means into stored energy in the form of compressed air, then (also inefficiently) converting the compressed air into torque to move the car. The car is hauling a huge tank around which also kills the concept. If you just use the electricity to power the car, you're skipping several extremely inefficient conversions.
By the way... the electricity isn't free, and it isn't clean. It comes from coal and it comes from oil, and it comes from nuclear reactors. These industries aren't engaged in conspiracies to stop air and electric cars... they're probably dancing a jig at the thought of all those inefficiencies piled into our energy consumption.
To sum up, the single most efficient means of storing and transporting energy that we currently possess (in any volume) is gasoline. Hopefully, as fuel cell technology moves forward, this can change, but until then... there's no such thing as a free lunch.

Wow! good information everyone! See you in the patent lines...oh and by the way, those two brothers that flew, they were crazy to try it dont you think? Sometimes what you dont know is more of an asset than what you do...
All you crazy garage mechanics like me, keep tweekin those ideas and make it work, race you to the finish!

If the Air Car is a hoax, then they sure fooled Beyond Tomorrow into featuring it in a story: http://www.youtube.com/watch?v=QmqpGZv0YT4

I agree, whatever the solution is, the design of it needs to be aesthetically pleasing and functional for it to perform in the market place. It also needs to be priced at a level to insure market saturation.

Presumably, the whole point behind designing such products is to save the environment, yet companies continue to price them out of reach of the average Joe. Microsoft has proven that low-cost junk (PC's) gain greater market share than high-priced art (Mac's).

If inventors were really interested in saving the environment, then they wouldn't price their products out of the market, in fact they would just advertise the plans for building their product free of charge to the world. This is obviously not the case, so therefore people care more about their pocketbooks than they do about the environment.

I wish I were an inventor, I wish I knew more about mechanical things, then I would spread my inventions across the world. But I'm just a dreamer trying to find the right product that does the job in the best possible way.

I would assume everyone who reads and posts here in treehugger was interested in preserving the environment and encourage folk to keep up the good fight, but more often I see comments from people dismissing or debunking this or that invention. But the I also realize that people who "DO" are probably too busy doing to waste time posting on forums like this.

I'm just so tired of reading posts from armchair intellectuals who have nothing better to do than offer non-constructive opinions. You're either part of the solution or part of the problem, if you're part of the solution then great, chip in and help, if you're part of the problem then please step aside and stay out of the way, the rest of us are trying to save your hide.

Thank you.

Having stylish cars and long range capability are great wishes. However, the world output of oil has peaked. In a few years we will all be begging for nuclear power plants and innovative means of transportation like air cars. Air cars are not met for long distance service. They are met for local transportation and will be the wave of the future. You will drive your air car in the city and a gas powered car for trips out of town.

Incidentally, the air car tanks won’t explode, just crack open. In case of an accident the computer can detect within one microsecond that a rupture has occurred and then pop relief values on the tanks within 10 milliseconds. Even if there were no safety devices, the air car is enormously safer than a gas powered car.

The car's 100% real and safe. I created a fan website (CATvolution.com) to help raise awareness of the Air Cars and bring them to North America.

It's not affiliated with MDI of France (mdi.lu), and all volunteer participation.

I guess I am just an egghead. I have never purchased a vehicle because it "looked" good or because it could accellerate to "warp 9" speed. I have always looked for the functional, efficient, utilitarian vehicle. My vehicle is not an extension of my groin; it is a tool to get me from point A to point B efficiently, carry my butt and sundries, and do all that without unnecessarily endangering me or anyone else on the road. I don't need a machine to enhance my machiso. My ego is stroked when I find a way to do such things without poluting the atmosphere, ground, and/or water. Until all of us change our attitudes about our "environmental household," we will all be sucking in the exhaust of the guy in front of us on the road. I can hardly wait for these cars to become available to the American driver.

I went looking to see if this particular idea had been bumped around, or was even feasable, and found this site. Thanks to all for the information. I was thinking to build myself a trike, that would use compressed air, I only need it to go about 30 miles on a charge (I'd settle for 10 right now) to be very useful where I live. I know almost everyone is thinking about getting something like this to market to the general public, has big ideas, that will require lots of capital. I actually think that if you built something like this and started actually using it and spreading the message by word of mouth, not looking to get everyone in the auto industry on board with this and make a killing in the marketplace, you would be better off - or at least the result would be better off. Just build something that works and improve it a little bit at a time and you may find better, longer lasting results. The trouble I see is that if you do it for profit, you will see someone take your idea and cut you out of the profits.

I want to do this just for my own use, so I am independent of big oil. I am not that concerned for the "green-ness" of the solution, although that would be a real plus. I just want to be able to get into town on occasion.

I was also wondering if solar power could be used to power a compressor sufficiently to get the tanks compressed. certainly you can charge a car battery over time, would that be able to slowly compress a tank of air? I would be willing to invest a sunstantial amount in wind or solar power to get a compressor working just for my own use. say 20- 30 K for starters. I know this will not solve the worlds problems, but I also dont believe that the incentive to find a solution on a large scale is there. But if you start off with just one working model (like when autos were first invented) I think you will find the groundswell that a multi billion dollar corporation wont give you, they have too many fingers in the pot (including the governments fingers) and their interests are not yours. Money tends to get in the way of reason. I suspect those of you working on this are planning on giving your aircar power windows, doorlocks, etc... I believe You are thinking WAY too big. All I've been looking for is some way to get 30 miles - kind of like a bike, but perhaps a bit more easy on the commuter. And then a way to generate my own air pressure for the tank. If you really can go 300 KM in one tank, I need to be able to do about 1/5 of that. Plenty for a simple commute vehicle to get me and perhaps a few minor posessions or a second person around. I'd like to see if I could Start with simple and cheap and go from there. I will continue to look for ideas, since I see I am not the only one thinking along these lines. Thank you all for your ideas and I look foreward to hearing more about air powered cars.

Before I go any further. Are there any possible "environmental" consequences to using compressed air? Like if used on a large scale politicians or other "advocates" of some sort, may begin to become concerned that with all that air locked up in tanks, there wont be enough for people to breathe or that a massive release of compressed air brought on by some potential global catastrophy might expand the Ozone hole or something wierd like that?

Regarding compressed air car range I saw that the Eolo Car has a 200mile range and takes 10 minutes to recharge (or recompress) at a 110volt outlet. I usually spend 10 minutes at a gas station filling up anyway. So range is not much of a deal. Plus, I own a small service company in Houston and a small compressed air van would be awesome. I could even charge customers less for a service call!

Let's all try to apply what we learned in high school physics and science classes...you did take those, right? When energy is transformed multiple times, the losses add up. When you look at the energy balance from an initial source to the final application, you have losses (due to the third law of thermodynamics) at every point in the process where energy is converted or transformed. When someone suggests building a compressed air automobile that uses an on-board compressor to charge a tank which then empties through a piston or turbine engine to move the car forward, there is NO KNOWN technology that is going to be more efficient than current gasoline engines when all else is equal in the design of the auto. The air cars proposed are all very small, light and otherwise completely UNEQUAL to the cars most people desire...a roomy, safe, luxurious car with gadgets and widgets and air conditioning and leather...and you get the point.

Ok. First of all, check out the Di Pietro rotary compressed air engine at www.engineair.com.au Here are a few responses to many of these comments. To the very first comment: yes, compressed air would explode if released quickly. However, if kept in a carbon fiber tank (which is environmentally friendly, recyclable and very strong) if the tank is breached it fractures and creates a seam. The tank will not fly off in large chunks. Instead, the tank will stay in the same place and the air will hiss out. NO EXPLOSION! In response to the comment previous to mine by MEguy, this is in no way true. The only transfer of energy with compressed air is the electricity to compress the air. NOTHING MORE. Compressed air is extremely efficient because in the Di Pietro engine only 1 PSI of pressure is needed to virtually cancel out friction in the engine. Also, it has a very high constant torque due to the design of the engine. The problem with gasoline is that it releases far more heat than actual kinetic energy, and it needs a large engine, sometimes weighing over 1000 lbs. The Di Pietro engine is made of light aluminum and other light materials, and it does not create heat or vibration which could cause heat to be created. In order to get the crude oil to automobile grade gasoline, it needs to go through stages that add up the costs. There are many efficient alternatives to oil, one of which is the electric engine. The Tesla Roadster, a $90K electric coupe could go from 0-60 in 3.9 seconds at a fuel equivalent of 130 mpg. It could drive for 250 miles on one charge and it had all the bells and whistles of a $90K gasoline coupe. One last thing on compressed air is that it is way more efficient than gasoline yet it has NO EXHAUST!! The only emission is air. Pure, clean, reusable air. Although electricity is necessary to compress the air, that electricity can be created safely and in environmentally friendly ways, such as hydroelectric dams, wind farms, and solar panels.

Hi Guys, nice discussion.
Sorry that I'm not going to give you any light about the subject. I'm going to send you a link for the most interesting online and free pdf I have ever seen about compressed air: http://www.atlascopco.com/ukus/Images/Compressed%20Air%20Manual%206th%20Edition_tcm19-327409.pdf

This is offered by Atlas Copco which I believe to be the leader company in compressed air.
Its a very easy reading but quite long and a bit technical.

It contains all the answers you are looking for about the energy balance, heat recovery, compressed air and the amount of energy in it.

Did you know that only 4% of the energy goes into compressing the air, but you can recover up to 94% which is converted in heat. Check out chapter 3.4.

Good reading to you all, I'll be checking it out my self.