Inventor promises bottle-o-wind car in a year. Again

They'll be giving them away in France

Can't wait. With government grants available upto around €4K for buying zero emission cars, gouv.fr will actually be paying people to have them. "Free" private transport. Cool!

I think it's a cracking bit of engineering.

Bonne chance mec!

Regenerative braking?

Does it use the engine to fill the tank again when going downhill?

It's a neat idea if it works, but will still suffer from the usual problem of such vehicles: the energy required to heat/cool the interior. Round here we go from -18C on a winter morning, to +40C on a summer day...

Freezing cold engines

While compressing the air makes it become hot, be sure that decompressing it (inside the engine) will make it become freezing cold!

It will surely need some heath/cold distribution system with liquid and a radiator.

In the summer this shouldn't be too much of a problem (in France, at least), as can absorb enough heath energy from the air. It could also used the heat inside the car, doubling as a natural airconditioning.

But in winter time it will freeze your nuts off!

foot powered pump

Combine your gym's step machine with a foot-powered tire pump, and you'd have it made. Charge your car and get fit at the same time. (Provided you didn't have to take more steps to charge it than you'd take walking wherever you're planning to drive.) And, if you keep a foot pump in the car, you'd never run out of "fuel"!

Heating things up

Heat may be an issue... but recharging is simple. Fitness clubs and other spots where spinning classes are taking place may hold the answer to that problem. Hamsters in wheels powering the world, but on a larger, more productive scale!

I just don't believe it

Not a single person has stated the obvious source of unlimited fuel for such a vehicle. One's wife or girlfriend. Surely when you factor in the copious amounts of hot air generated by those graced with marriage or long term relationships, the potential for unlimited, clean fuel means the search for alternative energy to power our vehicles is all but over.

Personally I reckon my wife could power one of these things for 1000km (625m) at least - from a single phone call to one of her friends, and I would assume most chaps more aesthetically pleasing halves could match our mpp with ease (miles per phone call).

Running out of puff

The other problem with air cars is they have a reduction in power output as the air reserve is drawn down. At the end of the 100km the response will be somewhat less than sprightly.

On another sort of related topic, people may be interested in the worlds first rapid fire, breech loading assault rifle. This little baby was approx 50 cal and had a 22 round capacity. It could deliver 20+ accurate aimed rounds per minute from its single barrel. Effective range was 100 metres+

It was so deadly compared to the other weapons of the day that possession of a unit was deemed an automatic death penalty in some regions.

I'm referring of course to the brilliant Girandoni repeating air rifle - http://www.beemans.net/images/Austrian%20airguns.htm

Even today, US SEALS use 9mm air rifles for sniping in Iraq.

@ tanks getting hot

I filled a few thousand scuba tanks back in my diving days, so I have the badge of authority here.

The scuba tanks do get warm and need cooling, but that is only because you're filling them fast (complete fill in 5 minutes or so). If you fill then very slowly, as planned with the onboard comressor, then the tanks won't get hot.

There are two other very good reasons to use slow filling with a small conpressor. Firstly compressor cost/weight/noise and maintenance - pretty obvious. Less obvious is that high output compressors are pretty power hungry and need 3 phase power. Most Indian (and presumably French) houses don't have industrial spec three phase power sockets. Thus, small is beautiful.

Many countries require you to pass an industrial compressor operator's license to fill scuba because high pressure air is as deadly as explosive if handled incorrectly. Would every air car owner need to do the same?

Utterly STUPID concept.

In fact, words cannot begin to express how completely and utterly moronic the very concept of this vehicle is.

Compressed air is by FAR the most expensive and least efficient form of motive power currently in existence.

Manufacturers of large fan compressors currently claim efficiencies of up to 95% when running at maximum capacity at 100PSI - this only applies to the very large compressors when they are actually running above 85% capacity.

These same large compressors drop to well below 50% efficiency when operating at lower outputs.

If the pressure is increased (which is essential for reasonable range and sensible size of pressure vessel), then efficiency also drops through the floor, as then screw compressors (mid-range efficiency) or reciprocating engines (extremely low efficiency) become the only possible techniques.

Add to that the very large losses involved in the transport of compressed air through small diameter nozzles, plus the inevitable leakage, this whole concept can be shown to be exactly the reverse of "Green" motoring.

Once again, a so-called "Green" system has completely ignored the issue of the Prime Mover.

Where do you get the original power from, and can that system be efficient and low-emissions?

One dirty little secret about industrial hydrogen is that most of it comes from electrolysis of hydrocarbons... producing the same carbon monoxide and carbon dioxide that would have been produced if it had simply been burnt.

However, I have much more confidence that sustainable ways of generating free hydrogen can be found compared to the idea of generating huge amounts of compressed air!

Historic note

Not really new. The use of compressed air as motive power was widely used in Paris between 1880 and 1910 for powering tramcars in a system attributed to Mekarski. The trams used to weigh about 11 tonnes and carried up to 9 high and low pressure air bottles. They used a bouillotte containing water at 155C at 200atmospheres to warm the air as it was released into the pistons and extend the range. Gawd help us if they use that on board these little cars - should go like a bomb!!!

Mine's the anorak with the notepad and pencil ..............

Safety

I think a highly compressed air tank has to be a greater safety risk than a tank of petrol.. surely.. what if a car such as this crashed into a small child's face, what would become of the mother, pram and benefits?

Its a nice idea but..

As others have said its a wonderful idea until you crash.

To quote the BBC website:

Mr Negre says there's no issue with safety - if the air-car crashes the air tanks won't shatter - they will split with a very loud bang. "The biggest risk is to the ears."

Gonads!

Fixed air compressors and their tanks in an industrial setting are very tightly controlled for a reason, there is a hell of a lot of energy stored in there and it can do nasty things like blow walls out, not just give you ringing in the ears.

I've used full size gas cylinders in lab settings in the past, they have to be treated with respect. Even just opening the valve a fraction without a regulator attached can cause such delights as ruptured eardrums, or can kill you with a gas embolism if a high pressure jet impinges on the skin.

Its a good idea for stationary emergency power generation, but for vehicle use, I don't think so

Paris, because even she's not that stupid

Stunning lack of research

"Away from France or Switzerland, the air car would be essentially a very inefficient fossil-fuelled one; wasting energy unnecessarily in electricity generation/transmission in all likelihood and at the compressor for certain. It would make more sense in terms of carbon emissions to just burn the fossil fuel on board in a conventional small car:"

Did you do any research for this Lewis, or just write what you imagined might possibly be something close to accurate?

Hydrocarbon based electricity generation and transfer is several times as efficient as an internal combustion engine. ICEs are generally in the region of 35% efficient, a modern gas turbine power plant is >85% efficient.

The compressor and the air driven engine will reduce that efficiency, but I'd be surprised if drops below 50% overall.

None of which means it's a good idea, but try to contain your rants against things to facts rather than imagination.

External combustion

If the air has to be heated, then this becomes an external combustion engine. Why not carry the gas as something that is liquid at room temperature, like water, to save on the compression losses, then heat that to its gaseous state and use that to drive the pistons, or a turbine. You can use anything to heat it, ethanol, methanol, diesel, even coal. You could call it a "steam engine"

Mine's the dirty blue overall next to the shovel and oil-can.

External combustion, pt 2

If this air car will only work efficiently if the air is heated, then let's get rid of the air altogether and use a Stirling engine. This uses pairs of cylinders, one heated and the other kept cooler. These are used in Africa for pumps, where a wood fire is lit under the hot cylinder and the cold cylinder is air cooled.

In a car you could use multicylinders, water cooling and any portable fuel - ethanol, methanol, LNG, Hydrogen, waste oil - even a fluidized bed coal burner. Unlike the air car these would run more efficiently in winter and the heat from the cold cylinder could be used for heating the car, though warm-up times might get a bit long.

Why aren't they already used? Long warm up times, (minutes rather than seconds) difficult changing the speed, so better suited to constant speed applications like pumps or generators. So, put a generator on one, a battery under the hood, and electric motors on the wheels, though then you introduce conversion losses, so back to square one.

To the yawning AC:

Nuclear, etc - lovely. Where are we going to build them? Your back garden?

But anyway, please consider this:

The efficiency ratings given by air compressor manufacturers are for Electrical Energy to Compressed Air Energy.

Thus, a compressed-air driven motor has the following loss stages:

1) Electricity Generation and Transmission

2) Compressed Air Generation (needs large power machines for >50% efficiency)

3) Compressed Air Transmission (pressure differential losses through the hose)

4) Compressed Air Storage (leakage)

5) Compressed Air Engine (normal rules apply to expansion engines)

Compare this to a Hydrogen car (assuming electrolysis of water)

1) Electricity Generation and Transmission.

2) Hydrogen Generation (can be done slowly by low-power machines)

3) Hydrogen Storage

4) Hydrogen Combustion Engine

The difference is clear - not to mention that a hydrogen car could have considerably greater range than any reasonable compressed-air powered vehicle.

In the recent past I spent several months examining compressed air usage at a particular industrial site, and found possible cost savings in electricity bills alone of over £15,000 pa.

It's simply the most expensive motive power currently used in industry.

Compressed Air is only used in industry where no other motive force makes sense:

- High linear accelerations (rams are much faster than motors)

- High static torques (eg wheelnut drivers)

- Need to pressurise containers (eg food sterilisers)

- Sensitive atmospheres (eg explosive)

Some quite weird assumptions here ...

Internal combustion engine driven with compressed air is still internal combustion engine, sans combustion. Valve train alone takes significant portion of the energy used. 20-50% depending on the source, internal friction and transmission losses are most of the rest.

But the efficiency would be better as there's less cooling needed, let's be generous and use doubled efficiency, that is about 40%.

Compressing air is very lossy job, that 85% given holds to very large amounts of air to very low pressures, no or low need for cooling. Putting small amount of air to very high pressure needs more energy to cooling than is stored as potential energy in compressed air. So efficiency is much below 50% in that one stage. Let's use that 50% as an absolute maximum.

Unfortunately efficiency won't get any better if done in a long time, you just don't need external coolers.

So we got overall efficiency of 50%*40% = 20%, while combination of battery+ electric motor+gearbox reaches effortlessy 60% and the source is the same: electricity.

Fuel to electricity efficiency in turbine isn't near 85%, even 50% would be a good achievement, but you could use the remaining energy for heating, thus raising the overall efficiency.

If you combine that with 20%, you'd get a 10% fuel to movement efficiency, compared to 20% of internal combustion engine.

Lesson learned: converting energy is almost every time a major loss in efficiency and should be avoided at (almost) any cost. Those losses cumulate and the chain fuel->heat-> electricity->movement->compressed air-> piston engine is losing 90% of the energy the fuel had, to conversions. "Environmentally friendly" means nothing with losses like that when said of the last phase.

You could use a windmill to run a mechanical compressor via gears to make the compressed air, that would be much more efficient, but very slow. On the other hand, losing 50% of something free and non-polluting isn't much of a loss.

Still cheap to drive

I’ve wanted one of these since I first saw them on Beyond Tomorrow and year or two ago. The only reason I want one is because they’d be cheap to operate. I could fill the thing for free at work with our compressors. That would bring my cost per mile pretty close to zero. I rarely drive more than 100km per day and if I’m going farther than that I’m usually transporting stuff that weighs a ton or so, so I’ve got my pickup for that. So an air powered car would be perfect for someone like me assuming they aren’t too expensive to purchase once they become available.

Check out my Sub-Woofer

I can't wait for one of the 'fully-sick' guys down the road to install some sub-woofers into one. I know in the past they have drilled through 2x car computers, and almost 1 LPG tank.

I figure a carbon-fiber tank won't give them a warning.

Aslo, when they figure out that the brake system can help create the heat needed to expand the air from the tank, it won't be an invertion, just them stealing the idea from the register posts.

*However i'm not so sure I'd ever want to be associated with the project.

Efficient carbon

Efficiency is a complicated subject - not least because different people mean different things by the word. Claiming internal combustion engines have an average of 35% efficiency is odd, given a four-stroke engine can't theoretically be more than 25% efficient (one out of four strokes produce energy, the other three use it). Unless you're trying to include 2-stroke engines in there .. but the numbers aren't there, especially for transport, and their efficiency suffers elsewhere anyway.

But I'm more concerned about this zinger:

"In France, to be sure, you can use grid power which comes mostly from nuclear generators and thus is nearly carbon-free"

From whoa to go (commissioning through mining through transport through decommissioning) your average fission nuclear power plant is about 75% of fossil fuel consumption, and consequently 'carbon emitting', as a coal-fired power plant. The myth that 'nuclear is nearly carbon-free' isn't one we should be perpetuating.

Anyhoo, what I really like about this (and similar) approaches is that it makes it possible for us little people to set up our own energy supply line - using home-scale wind or solar systems we can manage ourselves, incidentally removing us from the 'consumer' approach to energy.

Rocket car?

The one thing no-one has mentioned is what happens if the valve comes off the cylinder in a prang. Would the thrust of the escaping gas be sufficient to transform the car into an aeroplane, I wonder? A few rough calculations suggest that the thrust from a large aperture in the tank would be well in excess of the vehicle weight, so probably yes it would, if the thrust were downward. Even if it didn't leave the ground, it would still be a dangerous and uncontrollable missile.