Car Powered by Compressed Air 409
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."
New? (Score:5, Informative)
Re:Say goodbye to free air (Score:2, Informative)
Your local station's pump isn't nearly enough (Score:3, Informative)
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...
French (Score:3, Informative)
http://www.gizmo.com.au/go/3523/ [gizmo.com.au]
slashdot, wake the fsck up.
Re:Say goodbye to free air (Score:5, Informative)
Come on, READ the article. (Score:4, Informative)
Now, combine the compressed air engine with an hybrid car. You get an hybrid car with instant high torque when needed.
No, they're not. (Score:5, Informative)
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).
Same car, car, one year ago, in France (Score:2, Informative)
Site of the company in English: http://www.theaircar.com/Lucerne.html [theaircar.com]
Re:Still energy (Score:5, Informative)
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
Re:Still energy (Score:2, Informative)
Re:Say goodbye to free air (Score:2, Informative)
Hum: Mexico is on the system for years... (Score:3, Informative)
I can spot posts on the net at least from year 2000 about Mexico city running taxis and public buses on compressed air.
Am I missing the point ?
Z.
Re:New? (Score:3, Informative)
Re:Your local station's pump isn't nearly enough (Score:1, Informative)
Electric cars don't idle or break physical laws. (Score:5, Informative)
Re:Are you serious? I'll assume you are... (Score:5, Informative)
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.
Re:Let's get this out of the way. (Score:3, Informative)
On the other hand petrol tank design and placement has received a lot of consideration and is no longer such a danger as it was 20 years ago. So it is no longer the large tank that presents the major danger but the system itself.
I could not find a link but several years ago on the A40 in England there was a multi car accident in which most people died in the resulting fire rather than the crash. All the petrol gets dumped on the road and all the cars burnt. People could not escape in time especially those in the rear of 2 door cars.
Re:Your local station's pump isn't nearly enough (Score:3, Informative)
The practical fact is, even if you did suddenly get an explosive rupture of a liquid hydrogen tank, it'd freeze everything nearby before suddenly heading straight up once it turned gaseous.
Secondly, in terms of molar volume, the amount of hydrogen in the tank would be so large as to actually displace all the oxygen from the immediate vicinity.
But the real thing is the buoyancy, as I say. Burning hydrogen makes a perfectly vertical flame. It's not like gas, which pools and spills.
Also, hydrogen doesn't have any soot in it. Soot is what radiates most of the heat from a carbon-based flame. You can get very close to a hydrogen flame without being burned at all, because it does not radiate heat, it conducts and convects it.
Re:Your local station's pump isn't nearly enough (Score:3, Informative)
No, it's not. Hydrogen-oxygen mixtures are explosive, though.
Besides, in the event of an accident, I'd rather have a gas flame that burns more or less localized than be drenched in burning liquid hydrocarbon (the vapors of which are no less dangerous than hydrogen). There are good arguments against using hydrogen as a fuel for vehicles, but safety isn't one of them.
Re:there are propane powered buses (Score:4, Informative)
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:New? (Score:5, Informative)
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? (Score:5, Informative)
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.
Re:Your local station's pump isn't nearly enough (Score:5, Informative)
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
100% compressed-air powered car already exists... (Score:3, Informative)
It doesn't use any fuel at all, only compressed air, and the features are good:
Weight: 750 kg
Maximum speed: 110 kmh
Mileage: 200 - 300 km
Maximum load: 500 Kg
Recharging time: 4 hours (Mains connector)
Recharging time: 3 minutes (Air station)
The Explosion Factor (Score:5, Informative)
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!
Re:Say goodbye to free air (Score:5, Informative)
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:Your local station's pump isn't nearly enough (Score:1, Informative)
The biggest danger a tank of liquid hydrogen presents is that of freezing your hand to the tank as it vents.
Re:Say goodbye to free air (Score:4, Informative)
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.
Large trucks start with compressed air (Score:3, Informative)
"Jake" brake. (Score:3, Informative)
The "air" in a Jake brake is exhaust and, as you say, is limited by the compression ratio of the engine (not to mention choking it). The system I saw ran off the drive shaft and engaged when you hit the brake so the engines compression ratio was not a limiting factor. The inertia of the bus was used to drive an air compressor that in turn slows the bus down (ie: the compressor rather than the engine was "Jake"). When I saw the system I thought it was a good idea and assumed it had taken off, maybe it didn't, maybe it died because of cost/benifit. Popular or not the idea is nothing new, so put the "WRONG stick" down before you hurt yourself.
Re:Are you serious? I'll assume you are... (Score:2, Informative)
Actually, if you want a petrol tank to explode it pretty much has to be empty. Liquid petrol does not burn, drop a match in a completely full tank and it'll go out. Drop one in a tank of a petrol vapour/oxygen mix and you'd better be running...
Conversion problems? (Score:3, Informative)
25 km/h = 15.625 mi/h, not 40 mi/h
Guess someone goofed up on the metric system once again :)
Re:The Explosion Factor (Score:3, Informative)
> Now, I don't know exactly where on that tiny car the tank is, but I'd assume it's under the seat someplace.
In the prototypes, it was apparently under the chassis [theaircar.com] (look at the third picture). I suppose the separation would prevent the air from entering the passengers' area.
> 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?)
Maybe the car will be lifted up a bit, but remember the tank is supposed to crack and let the air escape, not rupture all at once. As a side note, MDI says the technology employed for their tanks is the same as the one used for natural gas-powered buses [theaircar.com] (and while I ride one of these everyday, I've still not heard of any injuries caused by a gas tank rupture, though in all honesty those buses have their tank on the roof, so they're less likely to be broken in a crash)
> Gasoline is good in comparison because it doesn't tend to do this when the tank is ruptured.
Well, sure but it *can* take fire, and there have been casualties because of crash-induced blazes. Also, every kind of energy has its dangers : an electric car obviously carries a risk of electrocution, for instance. I think drastic safety regulations should be enough to reduce the risks to nearly nil.
(obligatory disclaimer : the inventor of that air-compressed car is a friend of a friend. Still, I'm not associated with him in any way and in fact have never met him personally. I just think his idea is pretty good)
Re:Say goodbye to free air (Score:3, Informative)
Typically, the tanks are some sort of high-tensile metal with 15-20 layers of kevlar wrapped around them. They can be shot with a bullet and not release their contents. So, safety considerations of the tank are less important than a thin metal tank full of a combustible material, such as gasoline.
Re:No, they're not. (Score:3, Informative)