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

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

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

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

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.

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

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 ;-)

Still energy

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

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

Really strong children.

Re:Still energy

Really big sacks.

Re:Still energy

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.

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

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

New?

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?

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?

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!

This website provides the perfect fuel for this car.

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

Wrong conversion

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].

Don't Crash!

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

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

Conversion Factors

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.

Already Been Done!

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

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...

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

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

[ 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.

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).