Car Powered by Compressed Air

gripperzipper writes "CNN reports that a Korean company created a small car powered by compressed air. ENERGINE created its PHEV, or Pneumatic-Hybrid Electric Vehicle, which uses a two-stroke compressed air engine for start, acceleration, and uphill climbs. The car switches to an electric motor when its speed reaches 20-25 km/h (32-40 mi/h). Although major auto manufacturers have invested heavily in gasoline hybrids, it will be interesting to see if a market will open for this type of vehicle." Update: 04/04 17:18 GMT by T : Reader Tapsu spotted the incongruity here, writing "Interesting post, but the speed conversion has gone wrong way: "20-25 km/h (32-40 mi/h)". ... Thus the correct speed range in miles would be something like 12-15 mi/h."

Say goodbye to free air

[BobPaul (710574)]

I hope it has an external refil port for the compressed air tank. This will be a great way to take advantage of stations that offer "Free Air" (and also, unfortunately, prompt a decrease in the number of stations offering "free air"...)

Re:Say goodbye to free air

[Rei (128717)]

The compressed air from a gas station could barely provide any stored energy.

Compressed air has great power density, but awful energy density. I.e., you can unload power incredibly quickly from it, but can't store much at all. Even batteries store far more energy in a given mass. This sounds like a big step in the wrong direction, honestly.

Re:Say goodbye to free air

[XMyth (266414)]

Yea. A friend of mine recently researched using compressed air to run his house (and subsequently creating a solar powered air pump, using a sun-tracking reflective satellite dish) and eventually came to the same conclusion you just said.

What is interesting about compressed air though, the energy you get out of it is NOT what you have put into it. The energy comes from the ambient temperature of the air. This means that if a compression technique could be found that is efficient enough then you could have a potential self filling energy tank.

Unfortunately, like you said, the air doesn't have *that* much energy. Still thought that concept was interesting though.

Re:Say goodbye to free air

[Moderation abuser (184013)]

Depends on the pressure.

e.g.
http://zebu.uoregon.edu/2001/ph162/l10.html [uoregon.edu]

The MDI aircar proposes 400 atmospheres. They don't have a production model with tanks to hold that though. Energy density is similar to recent (but not cutting edge) batteries.

The problem with compressed air is that it is basically still a heat engine whereas electric motors are not. Electric motors are 90%+ efficient and compressed air motors, well, 40% maybe.

Re:Say goodbye to free air

[pfdietz (33112)]

Efficiency is not a showstopper. Even a very inefficient 'electric' car still can beat a gasoline engine in marginal cost per mile.

Where electric cars (including those that store energy in compressed air) have problems is energy density. The compressed air car could do a bit better there if it also had a resistively heated thermal mass to heat the air before expansion. The thermal mass would be recharged from the wallplug at the same time the air tanks are refilled. Low atomic number materials can store a great deal of thermal energy; LiH heated to a vapor pressure of 1 bar, for example, stores several megajoules per kilogram.

Re:Say goodbye to free air

[Tristandh (723519)]

Well, it only uses compressed air for accelerating and climbing up hills. So it does make sense to use air: short burst of acceleration on air (much power), steady driving on battery (lower power)

Your local station's pump isn't nearly enough

[joetheappleguy (865543)]

The high pressure tank in that vehicle is charged to 300bar, or 4350psi.

That's higher than a SCUBA tank and it requires some heavy duty air compressor rigs to charge it.

I'd hate to be anywhere around that car in a crash or if it catches fire...

Re:Your local station's pump isn't nearly enough

[morzel (62033)]

You've obviously never seen a scuba tank explode [napsd.com].

Energy density on these things may not be that high, but they can release all of it in a fraction of second. On top of that, if it goes, it will send fragments of the tank like shrapnell all over the place. I wouldn't want to be sitting in the car where such a tank explodes.
Or more detailed: I wouldn't want to be sitting in any car where anything explodes (outside the confines of the explosion engine, of course ;-)

Re:Say goodbye to free air

[arivanov (12034)]

Show me a station offering free air at 300 bar. Wanna see one...

The basic problem with this car is that it will require extra infrastructure. Not terribly expensive, but quite noisy. Compressing air to 300 bar is not a very quiet affair.

Re:Say goodbye to free air

[michaelhood (667393)]

California auto stations are required to provide [ca.gov] compressed air, water, and a gauge for measuring air pressure to any paying customers at their station. They can be fined if their pumps do not work correctly for more than 5 consecutive days.

Still energy

[Zorilla (791636)]

But does it take more electricity to compress the air into the tank than it does to just run the car on electric power? Sounds like just another degree of separation from energy we'll be getting from oil, anyway.

Re:Still energy

[FluffyPanda (821763)]

Not in china, there you can pay 20 small children and a man with a whip to squeeze balloons all day for less than the cost of a sack of coal.

Re:Still energy

[Havenwar (867124)]

Really strong children.

Re:Still energy

[dabigpaybackski (772131)]

They get that way from hauling sacks of coal.

Re:Still energy

[Havenwar (867124)]

Really big sacks.

Re:Still energy

[homer_ca (144738)]

Yes, but it might be cheaper than a pure electric car because they they can get away with a less powerful motor and power controller. The motor charges up the air tank when the car is idling or braking. Then the compressed air is used for short bursts of extra power when needed like accelerating or climbing hills. Otherwise it's just like a battery electric car with a heavy, expensive battery pack.

Electric cars don't idle or break physical laws.

[TapeCutter (624760)]

When an electric car is standing still the motor does not draw power. Converting energy expended while braking into compressed air has been done on normal trucks and busses for years. Converting the batteries stored energy into compressed air is gaurenteed to loose some of the energy in the conversion and therefore will not last as long. Every time you convert energy you loose some so it makes sense to save the wasted braking energy. There is nothing really "new" about this car except they have taken a common fuel saving technology used on heavy transport fleets and applied it to an electric car. If it works for an electric car it would work for a normal car but with electric cars you can't just get a bigger fuel tank.

Re:Still energy

[by Anonymous Coward]

Why does this type of comment end up in every alternative energy thread, and get modded up as 'Insightful'?

Centralizing the energy generation can take advantage of (a) economies of scale for better efficiency and (b) a varied portfolio of generating sources like hydro. For electric or fuel cell cars, this allows you to take advantage of the network effect of everyone already having electric wires as a means of transporting energy. I agree, compressed air is a bit silly b/c of its poor energy storage, but to knock it because of off-site production is simply wrong.

In this era of high oil prices, why are people so quick to complain about any alternative fuel?

Re:Still energy

[kfg (145172)]

Electric engines have the disadvantage of having little power. . .

Beg pardon? Not to mention the fact that their torque curves are the stuff that give drag racers wet dreams.

The only disadvantage electric motors have over combustion engines of any kind is, well, that they run on electricity, which has to come from somewhere.

Which turns out to be rather inconvenient.

The compressed air booster is just one way of finding some sort of dodge around the whole battery issue, and I'm not convinced it's a good one. A true hybrid seems a better solution to me, although it lacks the politically correct advantage of hiding its energy use and emissions from public view.

Bear in mind that I'm actually quite fond of compressed gas engines and have actually built a few small ones, just for my personal enjoyment and edification, but I haven't, outside of the realm of entertainment, found any problem for which they are the solution.

KFG

Neocons

[MarkusQ (450076)]

Neocons are children who don't want their toys taken away, and won't clean their room because it isn't fun.

Thank you for recognizing that the distinction between the present domanant "neo-conservative" group think party in the US and true conservatives. True conservatives wouldn't have bought the toys in the first place (we're compulsive savers) and wouldn't have let the room get messy for fear of unspecified adverse consequences. True conservatives (I know, I am one) are more likely to avoid doing things because they are fun (on the principle that the more atractive the lure, the more likely it is to be bait).

--MarkusQ

Re:Neocons

[gad_zuki! (70830)]

True conservatives? Is that like the true christians? Looks like to me appealing to the idealized form while ignoring the reality of what these beliefs have done historically (remember true conservatives also defended segregation,etc) is nothing more than a way to fight cognitive dissonance.

If rapid depressurization is any indication...

[Capt'n Hector (650760)]

...this thing is gunna be loud.

New?

[Cyno01 (573917)]

Havn't they had something like this comercialy avalible in France for a while IIRC? Its has a ridiculously strong carbon fiber airtank that's presurised at home by a compressor using off the grid electricity. Its basically a small comuter car, but it has decent range and speed.

Re:New?

[by Anonymous Coward]

Do you mean the MDI air car [theaircar.com] ?

Re:New?

[imr (106517)]

This comment talks about him and his car in fact:
MDI car made by Guy Negre [slashdot.org]
No surprise it's italian, iirc he was working in Nice near the itlian border and the car lobby in france is too strong.

Re:New?

[ksp (203038)]

One really cool thing (IMHO) about the French/Italian "air car" is the electrical system:
Technical details [theaircar.com]
Using a radio transmission system, each electrical component receives signals with a microcontroller. Thus only one cable is needed for the whole car. So, instead of wiring each component (headlights, dashboard lights, lights inside the car, etc), one cable connects all electrical parts in the car. The most obvious advantages are the ease of installation and repair and the removal of the approximately 22 kg of wires no longer necessary. Whats more, the entire system becomes an anti-theft alarm as soon as the key is removed from the car.

Perfect for us!

[Dancin_Santa (265275)]

This website provides the perfect fuel for this car.

But I'm probably just repeating the first several dozen comments...

Wrong conversion

[evn (686927)]

when its speed reaches 20-25 km/h (32-40 mi/h).

The car swtiches to electric when it reaches 25 km/hr according to the Energine website which is actually more like 15 miles per hour [google.com].

Re:Wrong conversion

[skurk (78980)]

It seems like the author has switched km/h and mi/h around:

32 km/h [google.com] = 19.88 mi/h
40 km/h [google.com] = 24.85 mi/h

Don't Crash!

[nacturation (646836)]

From the manual:

"Should you find yourself approaching the state of being in an accident, please yourself to duck so as to avoid looking at your previously attached body before the shrapnel took off your head." (Safety tips, Appendix A, P.232)

Nothing But Hot Air

[pressesc (873084)]

Here [pressesc.com] is another take on the same story, but with a little bit more science. The bottom line is there's no such thing as free energy... or lunch. You don't get owt for nowt. CNN needs to learn science

Two sides to every story...

[SSChicken (872688)]

First off, like someone said, that the energy it takes to compress the air can be inefficient and still polute the air if the energy to compress came from fossil fuels/coal. Secondly, while it is an "Engineering Marvel" to drive up a hill using compressed air, it's very dangerous. For any of you who have ever worked on high pressure AC systems, any pressure higher than 500psi or so can be deadly if anything at all goes wrong. It's not like a battery, where a little acid can spill if it's broken. Nor is it like gasoline, cars are built to prevent explosions, and the worst case scenario is lots of fire. If you puncture a high pressure tank or lines, you have a disaster on your hands; theres no avoiding it. Besides, the entire problem with a gas induction engine is that they are horribly inefficient anyways unless they are running at their optimal RPM.

Conversion Factors

[Ray Radlein (711289)]

The car switches to an electric motor when its speed reaches 20-25 km/h (32-40 mi/h).

Now we know why this car keeps crashing into Mars.

Flux capicitor optional?

[EdZ (755139)]

It switches to electric at 25, what happens at 80?

French

[deafff (604798)]

There are french cars that run completely on compressed air around for years.

http://www.gizmo.com.au/go/3523/ [gizmo.com.au]

slashdot, wake the fsck up.

Come on, READ the article.

[ihavnoid (749312)]

This compressed air engine isn't directly related to a environment-friendly fuel. The fuel of the car itself isn't compressed air - it's electricity, the battery. Electric cars, or hybrid cars, have the problem that they can't obtain high torque instantly. However, compressed air does give high torque. The idea is to store compressed air in a tank, and use it as a booster when high torque is needed. The air will be compressed later on with another compressor.

Now, combine the compressed air engine with an hybrid car. You get an hybrid car with instant high torque when needed.

Old News

[pklong (323451)]

This is old news. The Frenchies have been there and done it [bbc.co.uk].

It's even been tried in African [bbc.co.uk] (same company).

The company's own website seems to have gone. I would be suprised if this wasn't because the company has also gone out of business.

Why does it only get on Slashdot when it's an American company?

Units are the problem...

[TigerX (859482)]

The author of the post got the units backwards...

The line should read:

The car switches to an electric motor when its speed reaches 20-25 mi/h (32-40 km/h).

It's probably already obsolete

[panurge (573432)]

If the Toshiba announcement about a better traction battery is correct. Electric motors can have practically an ideal torque/rpm curve, but the current demands for high starting torque are a problem. The holy grail is a battery which has effectively an enormous surface to the electrodes without corresponding fragility, and so can be quickly recharged and discharged. (Traction batteries currently have a long service life but relatively slow charge and discharge. Starter batteries have a fast discharge for starting but are fragile and do not deep discharge well). Such a battery would completely supersede the inefficient compress air/decompress air cycle. So whichever compressed air tools division of this Korean manufacturer came up with this job preservation scheme - forget it and retrain as battery engineers.

Hum: Mexico is on the system for years...

[zijus (754409)]

I can spot posts on the net at least from year 2000 about Mexico city running taxis and public buses on compressed air.

• here [bbc.co.uk]
• here [tidepool.org]

Am I missing the point ?

Z.

Already Been Done!

[phobos13013 (813040)]

A completely compressed air vehicle has been made before and is a production model called the air car by a company MDI [theaircar.com] in italy. They have produced models for street use, you can see a video of it here [motordeaire.com].

The Explosion Factor

[beej (82035)]

Someone mentioned the problems of having a (scuba) tank of compressed air sitting in the hot sun...yes, it can be a problem, obviously, if the air heats and expands above the pressure rating of the tank. I am assuming they thought of this and would make the tank adequately strong. (With scuba, the shop fills your tank to the limit, and then the hot sun gives you another 1000 psi and your burst disc goes. This is less than the five-thirds working pressure they push your tank to when they hydro [wikipedia.org] it--I'm sure the tanks on the cars would have some kind of overpressure relief like a burst disc.)

The French air car article [gizmag.com] points out, "In the case of an accident with air tank breakage, there would be no explosion or shattering because the tanks are not metallic but made of glass fibre. The tanks would crack longitudinally, and the air would escape, causing a strong buzzing sound with no dangerous factor."

Well.

It's great to know that it's a carbon fiber tank so it won't turn into a screaming cloud of schrapnel [wahoo2001.com], but isn't there another issue at work here?

Now, I don't know exactly where on that tiny car the tank is, but I'd assume it's under the seat someplace.

The volume of that car is what...two cubic meters? What happens when you instantly put 90 cubic meters of air inside it? (Or under it?)

Have a look at this rather larger car [diveshop-pr.com] for an example. Look, ma! No fragmentation thanks to a steel tank, but all that air introduced to an enclosed space jiffy-pops a car like a cheap paper cup.

I'm more than willing to admit there's more to carbon-fiber tanks than I know. Maybe there's some property that prevents them from releasing all that energy in less than, say, 10 seconds, no matter how badly crushed. But I'm officially skeptical.

They say there's enough energy in a scuba tank to lift a hook-and-ladder fire truck 20 meters in the air. That's exactly the sort of energy I don't want released near me in a short timeframe. Gasoline is good in comparison because it doesn't tend to do this when the tank is ruptured.

Then again, a compressed air tank explosion might be just what I need to get ahead in today's Bay Area traffic. Up yours, Fastrak!

Are you serious? I'll assume you are...

[cfalcon (779563)]

I hear they're almost as volatile as tanks filled with explosive refined hydrocarbons!

Re:Are you serious? I'll assume you are...

[Zemran (3101)]

[ A hole in a compressed air tank equals instant explosion. ]

Err, no. A hole of any size equals a leak and a loss of pressure. I am not sure which science friction books (pun intended) you have been reading but I have suffered many leaks in high pressure air tanks and in only one case was it dangerous. That was when a friend dropped his tank on the side of the pool and the regulator valve broke off and the tank left the scene rapidly. The type of gas was irrelevant as any high pressure tank would have taken the same trip. Do you think we would be allowed to strap these things to our backs if they were as dangerous as you say?

Petrol vapour on the other hand is very explosive so even an empty petrol tank can explode.

No, they're not.

[Gordonjcp (186804)]

Lots of cars and vans in the UK and EU are powered by LPG. They're not dangerous. The tank can't burst, and there is a check valve on the outlet regulator block similar to the valve on the gas meter in your house that prevents gas escaping if the outlet is left open.

They are far safer in a fire, too. If there is an overpressure in the cylinder, the gas is slowly vented, where it burns. With a petrol tank, as the fuel heats up the pressure rises until the tank bursts (because they're either plastic or thin steel).

Re:there are propane powered buses

[ColaMan (37550)]

Pressure of a propane tank at 100 deg F is 175PSI - this is a pressure that can be easily managed.
Take note too, that any major pressure loss on a propane tank will instantly drop the temperature of the remaining liquid in the tank (as it boils), resulting in less pressure - check a Pressure-Temperature chart for propane [glacierbay.com] sometime.

Compressed air at a few thousand PSI is a lot more trouble to deal with in an accident.

Re:Let's get this out of the way.

[dabigpaybackski (772131)]

Tanks made of truly modern materials are a hell of a lot stronger and safer (and corrosion-resistant) than the usual steel or aluminum. I'm not saying that such high-pressure tanks are completely safe--they aren't--but it's something to consider.

Imagine what could be done with an advanced plastic tank that deforms in a severe vehicle crash or other incident, instead of shredding like a metal one. For an added safety measure, should a puncture occur, an inner membrane flows out of the hole(s)like a ballo

Re:Rocket scientists wrote this one!!!!

[anagama (611277)]

In my (unsucessful) haste to be the first to point this error out, I missed pointing out the cause of the problem. There are roughly 1.6 km/mile. To convert km/hr to m/h, divide, do not multiply km * 1.6 (20*1.6=32).

AirCON not Aircar

[dbowden (249149)]

Yeah -- I've been watching this guy for a couple years, and have come to the conclusion that he's a complete con-artist.

If you read the website carefully, you'll note that the specifications he displays here http://www.theaircar.com/models.html [theaircar.com] for the various models (range, top speed, refuel rates, etc) are all based on theoretical measurements made by guessing how much improvement he can get from changing a number of things in his current design. The current design has been tested for a total of 7.2 km. He gets his 200-300km range by extrapolating based on his guesses. See http://www.theaircar.com/tests.html [theaircar.com] (scroll down to "Mileage comparison between the taxi in development and the final car") for the true specifications, and note that after the top row, they're all extrapolations. He's basically saying he should get x% increase from this change, and y% from that change, and that means the "improved" engine will get (x+y)% better performance.

His site hasn't changed in at least a year -- meaning those figures haven't been updates with actual test results, and I don't think they ever will be. It's real easy to guess how much improvement various changes may make. It's not so easy to get that improvement out of them.

Next, note that he's selling "licenses" to build factories to produce the car. This is his real goal: Grab some $$ from investors before they find out he has no real product. He's a lot like the guys selling free energy based on concepts that violate the laws of thermodynamics, but will have a working model "real soon now".

Go ahead and watch this guy -- it's entertainment at least, -- but don't give him any of your money until he can back up his specifications with real world tests.

Re:Not the first Aircar...

[sxpert (139117)]

the dude that invented that vehicle (Guy Nègre, whom that I talked to at the paris car show a couple years ago) received death threats from unknown people that called him at night and stuff...