Air-Powered Cars

Azanian writes: "Here is an interesting article about a French-designed 'compressed-air' powered car being unveiled in Johannesburg (South Africa) later this week. The first of these 'alternative-energy' zero-emission cars are scheduled to roll of the production line in June 2001." It ain't a hover car, but it looks interesting (a full day's driving on 3 hours of air compression, with dramatically less power consumption). Sounds almost too good. Course the auto companies keep this out of our hands like they do with the engine powered by water *grin*.

Comments

Better technology

[mr.ska]

As some other poster mentioned, power density is a real problem here. A compressed gas just doesn't have a lot of energy stored in it compared to liquids or solids.

If you want an air-powered car, I think they guys at TriTec Power have a better solution with their power unit that can be adapted for just about any vehicle. It doesn't run on air per se, but it can run on any expanding gas. Steam (made by combusting diesel, gas, hydrogen, whatever), compressed air, liquid nitrogen... anything. Just imagine how much farther you could go with a tank of liquid nitrogen in your trunk expanding. I don't know the figures for N2, but for our old friend H20, it expands by a factor of 1700 times going from liquid to gas. That's nearly 6x what you'd get compressing a gas to 300 atmospheres.

For the record, assuming their claims of 200km per "tank" and 130km/h, I'd be right there getting one if they came here. Just think how damned quiet it could be. Yeah.

The downsides of an air powered car:

[OlympicSponsor]

1) The constant farting sound of air blowing out the back end
2) Can't steer, car just flys around the room
3) High internal pressure means that exiting car too rapidly causes "explosive decompression"
4) After car has run for several hours, outer surface gets all wrinkly

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An abstained vote is a vote for Bush and Gore.

Re:I'd like to believe this, but I don't.

[dbarclay10]

It doesn't say in the article, but I imagine there's more than a cubic metre - probably more like 1.5 or 2. They also don't say what pressure the air is stored at.

There is one thing to keep in mind - we've all been spoilt by e-Press e-Releases. This company already has two factories making these things, and the African government has already bought a budle of 'em. They'll be there before the year's end, by the sounds of it. This is obviously *not* vapourware.

Anothing thing to keep in mind is the industry that we're talking about. The "computer" industry is still very immature, and it acts that way - look at Rambus, look at Intel, look at Microsoft. For most other industries, to even *try* to bullshit your customers(especially governments) would spell instant death. And don't think that governments don't know exactly what's going on ;) The auto industry is, however, fairly mature despite its relative youth(only going back a couple of hundred years at most, if you count the first steam-engine tests and such).

The BBC could be mis-reporting that these vehicles will get 10hrs at 80km/h off one fill-up, but I doubt it.

Dave
'Round the firewall,
Out the modem,
Through the router,
Down the wire,

Another link

[fishie]

The link in the article didn't work, but here's another about the same thing. At a price tag of $10,000 I'd have to consider it for a commute to work car. And at a price of 30 cents for 120 miles??? You know the oil companies hate to hear about this stuff. So does OPEC. :)

Re:Another link

[FreeUser]

Sure it will. Check out this link. Bush is known for his big oil contributors, he will stop all forms of advancement in the alternative energy fuels when given the word of big oil.

The same thing happened when Reagan was elected. All research into Solar Power a Argonne Natl. Laboratory was killed almost immediately and remained dead throughout their administrations. In many respects the Reagan/Bush administration was to alternative power as Microsoft was to Computer Science -- they slowed the technological development down for at least 10 years or so.

The other post was correct -- any career politician will be a whore to the contributor with the biggest check, but historically the Republicans have been the worst offendors when it comes to fossil fuels vs. alternative energy, with the Reagan/Bush administrations being the worst offendors by far.

Sometimes true, BUT

[OlympicSponsor]

Relocating the emissions can be a good thing, even if they (temporarily) increase. Right now, all the emissions are from "non-point sources"--meaning from cars that are zooming around everywhere. But if all the emissions could be centralized into a few power plants, it's a LOT easier to apply some emission reducing technology to the problem. Just think about the logistics (and legalistics) of making all car drivers install some kind of filter or post-processor compared to doing the same for a few power plant owners.

Furthermore, it modularizes the problem. Instead of having to come up with an engine for a car (which has to be small, high-power, light, and various other characteristics that vary by car) you can extract all those issues to the power plant where size, weight, cost, etc aren't as important. Imagine, for simplicity, that we were all driving electric cars but that our electric infrastructure was coal-based. Just replace those coal-plants with fusion plants (or solar, or whatever) and the change is transparent to the rest of society.

This is just like putting wrapper calls around malloc/free--you have all the same memory management issues to deal with, but in only one location.
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An abstained vote is a vote for Bush and Gore.

Hot air

[gattaca]

If it was a hot air car, I could run it off my boss - finally, turning him into a useful resource. More generally, We could power entire public transportation systems simply by holding regular meetings to discuss great new e-commerce ideas with venture capitalists.

I'd like to believe this, but I don't.

[Skinny Rob]

Well I'm skeptical. It comes down, as always, to the dull and tedious issue of energy density. My back-of-envelope scribblings tell me a cubic metre of air at 300 bar stores about 30 megajoules. That's only 8 kWh. I don't see that little energy lasting any longer than about half an hour: nowhere near the endurance figures mentioned in the article.

Piece de resistance

[Tau Zero]

I learned it in an engineering class -- something like 1/2 or 2/3 or all the energy put in is lost to resistance.

Over the line of your homework examples, maybe. In real life energy is money, and power companies work very hard to keep losses down. The power transformers which convert one voltage to another are upwards of 97% efficient.

Power lines are a lot more efficient than you think, too. I'm having a bitch of a time locating the resistivity of typical aluminum transmission wire (AskJeeves is turning out to be useless), but if we assume that the lengthwise resistivity of the alloy as used would be about 3 times that of pure Al or about 8 micro-ohm meters, the wire has a cross-sectional area of 10 square cm and it carries a current of 50 amps at a voltage of 500,000 volts (25 megawatts) for 160 kilometers, we see that:

• The resistance is 8e(-6)/1e(-3) = 8e(-3) ohms/meter, or about 1300 ohms over 160 km.
• Total voltage drop is 1300 ohms * 50 amps = 65,000 volts.
• This is 13% of the total, not 2/3 or even 1/3.

If I had a line that was leaving about 3 megawatts undelivered, I'd want to lay thicker wire; at $.05/KWH, that's about $150/hour it's costing me. That's $3600/day, $25000/week, $1.3 million a year. You can recoup some pretty steep capital costs with that kind of return on investment, especially if you are amortizing over the kind of time-frames typical of a regulated public utility.
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