MDI air car

[Mainer in Exile]

I've heard they are developing a hybrid car which has a generator aboard to charge the batteries.

Jandra

Chevrolet is working on that concept, they are calling the car the "Volt". The idea is not new; shade-tree mechanics were building cars like this in the early '70s. I remember reading an article in one of the home mechanics magazines about a project involving an electric motor and a small, petrol powered generator. The concept got lost because of perceived losses converting petrol to electricity to run the motor. There are indeed losses, but, as far as I know, you can make a petrol engine run more efficiently if it is made to run at a constant rpm, rather than going up and down through the revs as with a conventional petrol car.

[Slow Down]

Martin- you are thinking with a narrow mind. With a slight modification this new technology will be superior to battery storage (even silicon salt batteries). The tanks will also last longer than batteries do before needing to be replaced.

[solarcooker]

The air-powered car. Someone brought this up on a MySpace science forum, a while back. I looked up the info on this and the claims were incredibly out of line with reality. You couldn't store enough compressed air for 5 minutes of running down the road, let alone the claims of over a 100 mile range. High pressure air tanks are very heavy, too. They have to be. At 3000 lbs. per sq. in., figure out how much total pressure there is on just one air tank. It would be like riding with a bomb in your car - waiting for the first crash.

The Tata car was two years away (estimate) last I looked. If there WAS such a technology, and it was feasible, why wouldn't they have at least one prototype running around to demonstrate it? Why? It doesn't work. It never did.

It's like the new, revolutionary, electric car that has a generator which spins while the car is moving, which recharges the batteries, which run the motor, .......

[The Riff-Raff Element]

The Tata car was two years away (estimate) last I looked. If there WAS such a technology, and it was feasible, why wouldn't they have at least one prototype running around to demonstrate it? Why? It doesn't work. It never did.

But they do have a prototype. Several. And Air France have just taken some on a six month evaluation to see whether they would be suitable for their airside vehicles fleet, which you can read about on the Air France site: http://corporate.airfrance.com/no_cache ... BackPid]=2

The tanks do not need to be too heavy: modern materials technology sees to that, and driving around with a tank of compressed air on board seems no more insane than sitting in a car laden with LPG or gasoline.

The physics of the idea work and the base technolgy of making a piston move with compressed air has been around for years - I believe that millitary torpedoes make use of it.

This is just an engineering problem now. It will be interesting to see how it develops.

[solarcooker]

Thanks for the link. Those babies look pretty small, and not something that's meant for highway use, but around an airport, where they could be kept charged(with air), they could really be practical. Interesting. I wonder how loud they are? Air motors tend to be hard to "muffle", since the "exhaust" comes out in a steady flow.

[Rod in Japan]

Small, short-range vehicles that use locally-sourced fuels don't need to be hugely efficient or crash-proof. They are enormously desirable since they promote the localization of energy sourcing, human scale solutions, and responsible driving, both in terms of purpose and execution.

However 'lossy' the technology is, if you're powering the car with 'waste' wind for example, it's going to be no more lossy than pumping oil from the ground and shipping it half way around the world and refining it, to burn it at 30% efficiency in petrol engine.

With a battery-powered car, the cost of sourcing the materials and in manufacturing and recycling is likely to be high compared with an air powered car.

It's a cool idea. It looks as if Americans are going to be forced to 'invest' in GM and the other makers of true and tested gasoline vehicles of a kind that apparently nobody wants, in the form of a national bailout. If GM had come up with something that even poor people could afford, perhaps the story would have been different.

[DominicJ]

Dont overlook the lack of an ignition source in vehicles that drive around airport fueling stations either.

The military uses a lot of weird and wonderful ideas, however what the military uses to ram a torpedo into a ship isnt that relevent to driving to work and back on the M25.

A vehicle that can carry a luggage train a mile, stop, then drive back is of little use to anyone but an airport, it certainly doesnt have a 400 mile range and never ever will whilst still being a usable vehicle.

There are two renewable energy cars, ones an E100,000 sports car, the other is a bicycle helmet made almost entirely of carbon fibre.
Neither even remotely resembles a SEAT Ibiza and never will.


Petrol is used to fuel vehicles because it is 40x as energy dense as the best batteries we currently have, if it were really possible to cheaply compress large amounts of air and use it drive cars, we wouldnt have bothered with petrol.

[The Riff-Raff Element]

Dont overlook the lack of an ignition source in vehicles that drive around airport fueling stations either.

The military uses a lot of weird and wonderful ideas, however what the military uses to ram a torpedo into a ship isnt that relevent to driving to work and back on the M25.

A vehicle that can carry a luggage train a mile, stop, then drive back is of little use to anyone but an airport, it certainly doesnt have a 400 mile range and never ever will whilst still being a usable vehicle.

There are two renewable energy cars, ones an E100,000 sports car, the other is a bicycle helmet made almost entirely of carbon fibre.
Neither even remotely resembles a SEAT Ibiza and never will.


Petrol is used to fuel vehicles because it is 40x as energy dense as the best batteries we currently have, if it were really possible to cheaply compress large amounts of air and use it drive cars, we wouldnt have bothered with petrol.

I can just imagine the conversations a couple of hundred years ago: "If it were really possible to refine rock oil and make it move carts, no one would ever have bothered with horses!"

The really good reason why we used petrol (and I speak from 15 years experience in the oil industry) is because it is (or rather was) cheap. And the technology to use it was relatively simple, in terms of producing it from crude, transporting it and tapping into the energy source it represented.

But the world shifts: oil is approaching a point were it is no longer tenable as a mass transportation fuel for reasons of economy, environment and geopolitical reality (those who want the oil have to buy it from those who have it and don't just want money for it) plus technolgy and materials advance.

100kg of air compressed to 300 barg (which is easy with existing materials and compressor technology) represents a potential power source of 10 horsepower delivered for two hours. The trick is to convert it usefully to motive power. Compressing air is a potentially ideal way to collect and store diffuse or surplus electric power from solar or wind or conventional sorces.

Internal combustion engines do not represent an ignition hazard on airports - or oil refineries for that matter - because the spark is entirely enclosed. I don't think that an air powered car is "the" answer because there isn't a single answer, but it could quite easily be part of a portfolio of approaches. The utilty for transporting people in urban environments is self evident, though they would be unlikely to be useful for longer distance commutes. That's what trains and telecommuting are for

[DominicJ]

Except air cars arent new, the idea of an air engine is 200 years old, rock oil was new. Realising we could crack it into smaller, more reactive molecules was a big breakthrough, whats the comparable breakthrough with air cars? Why hav they suddenly become more viable than they were in 1910?

Hardly impressive power obtainable (14kwh), about 1.4 litres of petrol, and how much energy is required to compress the tank?

Oil may be becoming untenable, but that doesnt mean that the technologies that lost out are suddenly better, especialy if your plans are harvesting that power from current waste.

Compressed air was abandoned as an idea because of several flaws, they havent been corrected or even mentioned, so the technology is no different than it was previously.

This differs from Battery Electric Vehicles, which have solved the range issue, to a degree, by having a £50,000 battery fitted, or by losing a wheel, having a 100 mile range and by being designed for minimal air resistance first and only and still being twice the price of a petrol supermini.

[DominicJ]

It would appear they have announced the tradeoffs.
50mile range, no safety equipment, glued together fibre glass.
Presumably it only gets worse from there.
Thats the TATA one.

Might do well in India, no chance it'll be legal in the western world

[The Riff-Raff Element]

Except air cars arent new, the idea of an air engine is 200 years old, rock oil was new. Realising we could crack it into smaller, more reactive molecules was a big breakthrough, whats the comparable breakthrough with air cars? Why hav they suddenly become more viable than they were in 1910?

Hardly impressive power obtainable (14kwh), about 1.4 litres of petrol, and how much energy is required to compress the tank?

Oil may be becoming untenable, but that doesnt mean that the technologies that lost out are suddenly better, especialy if your plans are harvesting that power from current waste.

Compressed air was abandoned as an idea because of several flaws, they havent been corrected or even mentioned, so the technology is no different than it was previously.

This differs from Battery Electric Vehicles, which have solved the range issue, to a degree, by having a £50,000 battery fitted, or by losing a wheel, having a 100 mile range and by being designed for minimal air resistance first and only and still being twice the price of a petrol supermini.

Well, the Babylonians experimented with rock oil as fuel for lamps (olive oil was better since it didn't smoke) and it was used for caulking ships for three thousand years before the basic refining processes were developed. New technology, in other words, applied to existing knowledge.

I can hardly claim to be an expert but as I understand the big advance was in the use of carbon fibres in compressed air storage which considerably reduced the weight. What flaws were you thinking of? Don't you think 10hp sufficient for a light, urban transport?

Harvesting compression from waste power is not "my" plan, just an illustration of one way in which power generated from difuse sources can be stored for future use. Compression is pretty effcient: depends on the set up but for a small riciprocating compressor on a domestic setup I'd guess at 1.2 or 1.3 to 1.

I confess I find your attitude a little confusing: given that you seem to accept that we cannot forever depend on oil fired transport, what do you suggest would be better than testing and developing alternative technologies with a view to our all continuing to be able to move around? Or should we all be considering horse ownership?

[MKG]

I have a design for a motive unit which runs on hot air and crossed fingers. Anyone fancy investing?

Seriously, though - everyone laughed at Clive Sinclair's C5. He laughed all the way to the bank when he sold the battery technology on. The vehicle was merely a platform for publicity. I believe the air car to be a non-starter, but I suppose that spin-off benefits may certainly make the research worthwhile.

[DominicJ]

New technology in hydrocarbons was, in my view at least, a little bigger than the leap of carbon fibre storage tanks.

"I confess I find your attitude a little confusing: given that you seem to accept that we cannot forever depend on oil fired transport, what do you suggest would be better than testing and developing alternative technologies with a view to our all continuing to be able to move around? Or should we all be considering horse ownership?"

I would suggest considering alternatives and discarding the failures. Compressed air technology is that (a failure) in spades.
It might make headway in some areas, but I cant see it replacing diesel trucks, whereas there is already an electric heavy goods vehicle with a 100mile range, its expensive, but it exists.

It jut seems mad to me that we have a technology that is proven to work batteries, and one that is proven not to (even the claimed performance is poor)


"I believe the air car to be a non-starter, but I suppose that spin-off benefits may certainly make the research worthwhile."

Quite possible, but its a low tech battery, it might, in some situations, be useful for harvesting day time solar or sporadic wind for a steady electricity supply, but I cant see it replacing pumped storage for that.

I wouldnt sit in that and go round the M60 in december, maybe I'm weird.

[The Riff-Raff Element]

Quite possible, but its a low tech battery, it might, in some situations, be useful for harvesting day time solar or sporadic wind for a steady electricity supply, but I cant see it replacing pumped storage for that.

Actually, I reckon this could become the most useful application, using this kind of technology domestically to store solar / wind power, which, as you say, is sparodic and then releasing pressure to turn an alternator when power is actully needed. With modern control technology it could work rather well.

Pumped storage is, after all, only possible where geography allows.

I don't think anyone is pretending that compressed air vehicles could ever really work to replace 40 tonne freight lorries, though something will have to: battery science is improving, but a 100 mile range is still a long way from the several hundreds actually desired. And it is still expensive. These are not, of course, insoluble problems, though they are potentially costly to resolve. But I'd maintain it is worth exploring further to what extent air could be used in small urban transports, and it is never wise to put all your eggs in one basket.

Oil refineries are just big kettles and expensive plumbing. The really clever bits were the develpment of the pipestill for continuous distillation, reforming for aromatics, alkylation and catalytic cracking of gasoils, all of which date back over 60 years: very little new has come along since then. From a chemist's point of view I reckon carbon fibres were far more clever.

[solarcooker]

Another thing to keep in mind with using compressed air. When you compress a gas, it gets very hot, which raises the pressure. Then when it drops back to room temperature, all that energy is lost, and the pressure drops. There really isn't a good way to reclaim that energy, in most cases. That hurts the argument that you can just hook up to an air compressor and fill the tank. You lose half the pressure as it cools down, unless the tank is insulated, and you take off right away. If you wait until it cools, and then "top off" the tank, then the expanding air quickly freezes any water vapor in the valves and lines, and clogs up the system as it leaves the tank. When you compress air, you add all the water vapor in it also.

If you aren't using solar or wind to power the air compressor, the efficiency is not that good. The car may not pollute, but the power plant does. (Not trying to be negative. I've just worked with compressed air)