Air Motors

No

Dear GUEST!

The word NO is valuable only for today. We, humans, are very smart and could produce an air powered motor for cars. Everything is possible from Gil.

"We, humans, are very smart and could produce an air powered motor for cars. Everything is possible from Gil."

"Everything is possible" within the limitations of engineering, physics and the laws of thermodynamics which rule out air engines as a viable automotive power source of any consequence.

Perhaps you would like to build a "Neal Tank" air compressor?

Check some threads on CR4, there was quite a few discussions about the effiency of air motors, (not very high). Am not certain, I believe Blink had a few good numbers on this.

There are smaller air motors and it should be quite easy to make a big enough one to move a small car.

The problem would be the "fuel" tank. (bulky and dangerous - I would rather drive with my mother in law in the car than with such a tank).

The free air policy of petrol stations will change dramatically when a lot of users switch over to air.

Now that depends how much wind your mother in law has.

Whats the differance between running a Air pressure tank in your car/boot as against a LPG tank in the same location.

People don't have a problem fitting a pressure tank to their cars, and possilbly the solution would be to use Liquid-Air and not just compressing the gas.

look and the potential energy in LP and compressed air, you should see the difference

"The answer is no, and here is why. Yes there are motors and designs (the principle has been around for many, many years), but all suffer from the same problem - they require MORE petrol to be burnt to produce the air to power the vehicle (remember the air must be compressed using a compressor, hence compressed air) than if you just ran the vehicle the current way with an internal combustion engine."

Not necessarily so. The petrol engine is perhaqps 25 per cent efficient. An electrical compressor- air motor can be much more efficient. Yes, Dept. of Energy says it isn't so, but they ignor the facts. It has been demonstrated that a diesel-pneumatic locomotive was nore efficient than a diedel electric locomotive. The trick is not to throw away the heat generated when the air is compressed. If the compressor is steam cooled, and the steam mixed with the compressed air, the power storage and transwmission is very efficient. (US Patent 5,832,728)

"The energy density of compressed air is 17 Wh/L,"

Would you believe 30W-hr/L? That's a mixture of air and steam at several thousand psi. The back of a van or pick-up truck would accommodate enough "wet air" to drive about 200 miles.

"Powering the compressor off the electrical grid is no better (you are just moving where the fuel gets used to the remote coal power stations, etc)." If that were so, there woulld be no point in electric cars or trains. Granted, it is not "zero-pollution", unless one compresses the air with a wind turbine or such, but the pollution is NIMBY.

"There are a few scams (one in particular) that use an onboard air compressor powered off a petrol engine. This just means that the overall system is even more inefficient due to the fact you have to lug around a large heavy compressor (the extra weight reduces your millage)."

Use one cylinder of the petrol engine as the compressor, no added weight there. Store air, as you would electricity in a hybrid. Air gives you lots of power when you need it (batteries self-destruct if you try to draw too much power). You throw away the heavy transmission, and do not lose efficiency, if you do it right.

There have been air-powered vehicles for more than a century. Chicago had air-powered street cars for a while (no overhead wires). "Everyone" knows air is a loser. The problem is that "everyone" doesn't engage their brains and do it right.

A suitable air motor can be an ordinary IC engine fitted with a new cam and injectors where the spark plugs used to be.

Ok, when considering a steam-cooled air compressor the energy density can be raised from 17 Wh/L to 30Wh/L, the energy density of petrol is still ~9000 Wh/L, with other fuel sources close or lagging behind. The main problem still stands of converting a high energy fuel (petrol, etc) into a low energy fuel (air) and then converting it to motion (to push a vehicle). It doesn't matter how much more efficient the air engine is as it would need to be way over unity to achieve the results of the petrol engine (even taking into account a 75% petrol engine inefficiency). The key point is if you use a high energy fuel (like petrol) and convert it to a low energy fuel (like air) you will always lose.

"If that were so, there would be no point in electric cars or trains. Granted, it is not "zero-pollution", unless one compresses the air with a wind turbine or such, but the pollution is NIMBY."

Exactly, but if you are generating MORE pollution just to reduce local pollution then it is hardly a wide scale solution, those fossil fuels will run out quicker too.

"Use one cylinder of the petrol engine as the compressor, no added weight there. Store air, as you would electricity in a hybrid. Air gives you lots of power when you need it (batteries self-destruct if you try to draw too much power). You throw away the heavy transmission, and do not lose efficiency, if you do it right."

It's a good idea in theory but remember the inefficiency of the air conversion which will reduce millage of a hybrid petrol vehicle, not increase it. It is a common mistake made by people who think that they can convert one form of energy into another and get more energy out (which is called over unity) or get free power off an engine by running lots of alternators off the fan belt (which they cannot due to the simple fact that as you pull current out of an alternator it requires more force to turn, hence the engine running it has to work harder and burn more petrol).

"There have been air-powered vehicles for more than a century. Chicago had air-powered street cars for a while (no overhead wires). "Everyone" knows air is a loser. The problem is that "everyone" doesn't engage their brains and do it right.

A suitable air motor can be an ordinary IC engine fitted with a new cam and injectors where the spark plugs used to be."

Unfortunately theory, laws and practical application of air compressors and motors are well known and proven. There is not a great deal that can be done to increase their efficiency, but even if they were 100% efficient they are still a low energy power source. There are far better uses for high energy fuels than to produce clean low energy fuels.

Oh, and electric cars are a better option over compressed air cars. I don't know where you got your facts regarding batteries but the technology has been progressing nicely, and with the addition of supercapacitors (allowing very large current discharge) they may well win out in the end as the most viable clean personal transport to replace the fossil fuel engine (if we can find a way of making and recharging the batteries a bit more environmentally friendly). As for safety, I would say the tank of a burning compressed air car is just as dangerous as the alternatives (batteries, petrol, etc).

"The main problem still stands of converting a high energy fuel (petrol, etc) into a low energy fuel (air) and then converting it to motion (to push a vehicle)."

Let's see if I understand. High energy fuel, petrol, burns in the cylinder, heating low energy fuel, air, which expands, pushing on the piston and converting "it" (sic) to motion, to push the vehicle. I don't see the concept of "low energy fuel." The inefficiency of the petrol engine comes from the Carnot cycle, and heat is thrown away by the radiator and the exhaust. As I see it, air is not a "fuel", it is simply a transmission medium, a spring. No heat is thrown away. Both compression and expansion are essentially adiabatic (isentropic).

Someone should tell Columbus how air is no good for propelling vehicles. He cannot discover America until he gets a diesel engine in his ship.

" It doesn't matter how much more efficient the air engine is as it would need to be way over unity to achieve the results of the petrol engine (even taking into account a 75% petrol engine inefficiency)."

Where does that assertion come from? Is there some concept of thermodynamics I am missing?

"It's a good idea in theory but remember the inefficiency of the air conversion which will reduce millage of a hybrid petrol vehicle, not increase it. "

"Inefficiency of air conversion"??? The point is that the electric motor driving the compressor is more efficient than a petrol motor, and the fuel (coal?) costs less. The compressor can be very efficient, if it is insulated. Last I heard, energy is conserved in a closed system, so if no heat is lost to the environment, compressing air is not lossy. Consider two examples. Big trucks and busses sometimes use air springs. As they travel over bumpy roads, the air is compressed and expanded, but very little energy is lost in the springs; they do not get red hot. Second, Chrysler had a V-8 engine which would run on four cylinders. They simply disabled the exhaust valves and fuel of 4 cylinders, so that air was compressed and expanded in the cylinder, no problem. The Germans demonstrated that a compressor-"steam engine" combination is more efficient than an electric generator-motor. In one case, it was so much more efficient that they claimed 29 per cent fuel saved.

"... the technology has been progressing nicely, and with the addition of supercapacitors (allowing very large current discharge) they may well win out in the end as the most viable clean personal transport to replace the fossil fuel engine (if we can find a way of making and recharging the batteries a bit more environmentally friendly). "

Sure, and an impossibilium flywheel would ber even better. Where can I buy affordable batteries and supercapacitors?

"As for safety, I would say the tank of a burning compressed air car is just as dangerous as the alternatives (batteries, petrol, etc)."

What's to burn? The upholstery? The plastic glove box? Even if you built a huge fire under the air tank (say from a burning gasoline vehicle), there is something called a safety valve to relieve the pressure before it explodes. As noted, air is non-toxic and non-combustible.

When I mention High and Low energy fuel I am trying to show that converting one fuel to another (say petrol to air using a compressor) is turning a high energy fuel into a low energy fuel. Effectively you are taking one form of fuel, passing it thru an inefficient conversion process (remember no process is over unity, that's free energy) and hence losing some of the energy to heat losses, etc and ending up with a fuel that has less energy than the original fuel. Like using a petrol generator to create electricity to power a compressor to create compressed air to power a vehicle, rather than just powering the vehicle on petrol in the first place. The sum of the inefficiency's in all the conversion steps ensure that you always lose more energy than you gain. The fact that I am referring to air as a "fuel" is only to try and simplify the explanation.

"Someone should tell Columbus how air is no good for propelling vehicles. He cannot discover America until he gets a diesel engine in his ship."

He is long dead, and there is a difference between a compressed air engine running on bottled air that needs to be compressed somehow and a sailing ship's sails which capture the wind. It is not an apples to apples comparison and you know that.

"Where does that assertion come from? Is there some concept of thermodynamics I am missing?"

See comments above regarding conversion inefficiencies between (say petrol) and compressed air. Any gains in air engine efficiency over petrol engine efficiency are dwarfed by the inefficient energy conversion of air (when compared to just using petrol). As I have mentioned before, if we can harness the air and compress it more efficiently then the air motor becomes a much better prospect compared to other options.

""Inefficiency of air conversion"??? The point is that the electric motor driving the compressor is more efficient than a petrol motor, and the fuel (coal?) costs less"

No it isn't when you take into account the electricity needed to power the electric motor.

"The Germans demonstrated that a compressor-"steam engine" combination is more efficient than an electric generator-motor. In one case, it was so much more efficient that they claimed 29 per cent fuel saved."

This is something completely different. This is regarding a coal/steam engine replacing the petrol engine, not a compressed air engine replacing the petrol engine. A case of not a apples to apples comparison.

"Sure, and an impossibilium flywheel would ber even better. Where can I buy affordable batteries and supercapacitors?"

That's rather pessimistic. Developments continue but as I have said before, the technology has a long way to go and some new ways of thinking are necessary. Lets ignore electric vehicles for the moment (they require a thread of their very own) as it detracts form the discussion of compressed air VS petrol, and I certanly wouldn't advise replacing petrol vehicles with the current electric ones as an attempt to save either gas, money or the environment.

"What's to burn? The upholstery? The plastic glove box? Even if you built a huge fire under the air tank (say from a burning gasoline vehicle), there is something called a safety valve to relieve the pressure before it explodes. As noted, air is non-toxic and non-combustible."

No, I meant the potential of the tank turning into a missile, dangerous release of air pressure causing shrapnel damage, etc. These are only points and certainly don't detract from a compressed air vehicle, I only made the point to show that there are dangers the same as any other fuel engine.

Look, the key point is that the air car idea doesn't work using existing thinking. Powering the compressor from the grid using coal, gas, nuclear, hydro, etc just isn't a good idea, having an onboard compressor powered from a petrol engine is hopelessly worse. There are far better uses for this high energy fuel than converting it to a lower energy compressed air. IF however we can find a way to produce compressed air more efficiently so that the overall system efficiency (from fuel extraction right thru to conversion to motion), which must be considered as a whole when assessing to ensure an apples to apples comparison, is almost or as good as the current petrol engine then the air powered car is by far the best, most environmentally friendly and safe alternative to the petrol engine or any other fuel engine. This is the only real big problem with the air car - how to efficiently create the compressed air. If we can find a way to solve this then we have a world-changing form of transport that can replace the existing petrol engine.

"This is the only real big problem with the air car - how to efficiently create the compressed air. If we can find a way to solve this then we have a world-changing form of transport that can replace the existing petrol engine."

We seem to agree on the above.

Let's back off and look at the problem a different way.

Problem: How to win the automotive xprize, $10 Million?

Needed: four seat automobile, complete with air bags, radio, etc., which can get 100 miles per gallon of gasoline or "equivalent", can do 0-60 in 12, can go 100 mph, meet emissions requirements, go 200 miles unrefueled, be mass produced for under $80,000, etc. Fuel is supplied by the race committee and is petrol, biofuels, CH4, or electricity.

My Prius represents the state of the art and can get half way there, about 50 mpg. To get to 100 mpg, the engine would have to be twice as efficient, about 50 %. That's nothing I know how to do. Clearly, using an IC engine in the car will not win the $10 Million. The alternative is some sort of electrical propulsion.

I assume the "gasoline equivalent" is about 35 kW-hr of electricity = 1 gallon gasoline. (They have all sorts of arcame formulas which take into consideration the pollution from coal generation, etc.) The 200 mile range could be accomplished with 70 kW-hr ("two gallons") if the car is twice as efficient as my Prius, about 50+% from plug to wheel.

If you multiply the efficency of charging batteries, discharging batteries, running the electric motor, and transmitting the motor output to the wheels, the overall system efficeincy is probably good enough. The problem is the batteries, weight and cost. Lead-acid batteries are too heavy. Fancy high-tech batteries are too expensive. Even the electric motor and its controller, if you ask for a quote on a new one, is very expensive.

Golly, is there some other way to store electrical energy and get mechanical energy, rotating wheels, out?

Yes. Use the electricity to compress air. Use the compressed air to drive the wheels. However, any engineering text on the subject of compressed air will tell you the overall system efficiency, energy in to energy out, will be too low, perhaps only 15 per cent. Why? The compressor is cooled, throwing away a lot of heat to warm the atmosphere, and the cool compressed air will get colder when it expands, limiting the expansion ratio. (The "air car" referenced by several messages exhausts at several degrees below zero, which may not be friendly to the car following, as the driver can't see well in fog and snow) Of course, when one runs the numbers, it seems like stupid engineering. It won't do.

But do the textbook writers know that it can't be done, or only that Tata Motors can't do it?

First, do not thow away energy (heat) compressing the air. Insulate the compressor and use no intercooler stages. Consider a common diesel engine with a 30:1 compression ratio. Use it as a compressor, driven by an electric motor. Cool the compressor with water, letting it phase change to steam, and, for convenience, store the steam and compressed air together at about 300-350C. (Liguid water cannot exist at 350C, no matter what the pressure) The combined pressure of the two mixed gasses is a few thousand psi, about 3200 for the steam alone. Apart from the losses in the electric motor, we still have 90+% of the input energy stored (comparable to batteries). Now run the compressed gasses though an expander, to drive the wheels. As the air expands, doing work, it cools, and the steam condenses, releasing the heat of vaporization to reheat the air. The exhaust, assuming a 30:1 expansion ratio, is the same as the input, air and water at ambient temperature. The only energy lost is from friction. Well, you can't just wish away friction. How do you know it won't be excessive?

I stongly support the thesis that a page of data is worth a ream of analysis. It so happens we have data.

"The German Diesel-Pneumatic Hybrid Locomotive, 1930

Just before technical journals stopped reporting on compressed air locomotives, they carried stories on a 1200 horsepower full-size above-ground locomotive that had been developed in Germany. An on-board compressor was run by a diesel engine, and the air engine drove the locomotive's wheels. Waste heat from the diesel engine was transferred to the air engine where it became fuel again. By conserving heat in this way, the train's range-between-fill-ups was increased 26%."

The data was generated in a competitive test to determine the best way to transmit the rotary output of a diesel engine to a locomotive's wheels. Using the same diesel engine, they tried mechanical transmissions, hydraulic transmissions, a generator-motor transmission (the universal choice today), and a compressor-air motor transmission. The compressor-motor loco won, was most efficent. Clearly the frictional losses were less than other methods of power transmission. (Note, the German engineers did watch their heat budget, and we presume they cooled the compressor with water/steam, although they did not describe that aspect, perhaps regarding it as a trade secret) Thus we have real world confirmation that the compressor-motor combination can be highly efficient.

It is a relatively trivial step (still patentable, see US Patent 5,832,728) to separate the compressor and the motor (expander) by storage tanks. The prime mover (diesel, electric motor, wind turbine) need not be in/on the vehicle. As long as the storage tanks are well insulated, no problem these days, there will be little energy lost between the rotary energy in and the rotary energy out.

I conclude that the overall system, plug to wheel, can be efficient enough to win the prize, and the cost of components (converted IC engines, storage tanks, no catalytic converter or radiator) is low enough to allow mass production at a reasonable (much less than $80,000) price. The vehicle will also out-perform an electric car, or even an IC car, in acceleration and top speed since the power output (rate of energy flow) can be very high, if need be. Against an electric car, even a Tesla, it wins. In a short race, acceration wins. In a long race, the rapid recharge (minutes vs. hours) wins.

By the way, it would be interesting to discuss why the diesel-electric locomotive, the loser in the contest, is the preferred engineering solution today. Shucks, diesel fuel is cheap.

An observation: 99 per cent (approx.) of good ideas are not adopted.

are there any gains that can be created with the use of super cooling of the electric motor, or using high temp superconductors?

<<are there any gains that can be created with the use of super cooling of the electric motor, or using high temp superconductors?>>

Yes, of course, if you have $millions and a few years to find the parts. The US Navy has a program to develop same for ships. Meanwhile, you can't afford it.

Hi Jack. I'm glad that I'm not at the airport.(ha,ha) Good point! Existing thinking is starting the ball rooling again. The more we can all work together, the quicker we will have a product that will help us all. We can use wind or forced air on the vehicles to get a turbine to power the compressor to power the motor. I know a lot of people are still in the dark ages and don't believe it is possible, but we can do it. Keep up the good thinking and we will do it. Thanks. PentaPower.

Yes,

http://green.yahoo.com/blog/ecogeek/66/air-car-ready-for-mass-production.html

http://www.businessweek.com/autos/content/mar2007/bw20070319_949435.htm?campaign_id=rss_topDiscussed

Read the full article. MIDI is selling licenses for others to build the air powered cars. TATA bought a pig in a poke and has yet to realize a profit. Guy Negre is the one scamming others by selling contracts to build the air cars. A very savvy promoter/scammer.

The OP was "Is There a air powered motor that could replaced a small car engine?"

There may be a lot of reasons why it's a bad idea, but it does exist.

The OP was "Is There a air powered motor that could replaced a small car engine?"

The answer is still NO.

It could physically/mecanically if you will.

Operationally it would not as most other responses state.

Thank You bhankiii

A French inventor build such a motor and equipped a car which is now build in series in India by Tata. This is an example how different considerations lead to different results.

It is quite clear that there are problems with the efficiency but there are positive aspects concerning pollution in cities which costs much more in health care.

Efficiency is only one side of the transportation problem. We have to look broader.

I believe you are talking about the French "The Air Car". See previous threads regarding the product (dating back to 2005 I believe), its technology and a breakdown on system efficiency (including the use of an onboard petrol motor-powered compressor to produce the air).

It is quite clear that there are problems with the efficiency but there are positive aspects concerning pollution in cities which costs much more in health care.

Certainly, if you only consider grid-powered compressors at the refilling stations, and the power stations are somewhere far, far away (and hence someone else's problem). Unfortunately producing more pollution somewhere else rather than some pollution locally is rather short-sighted (but brilliant when viewed from a political point of view). Unfortunately this line of thinking will catch up to us in the end.

Air-powered cars are not the answer unless we can somehow compress the air without using petrol and coal (remember, due to the conversion efficiency we use more of these than we gain from the air we create, meaning we are back to square one). Perhaps creating an artificial tornado (in someone else's backyard of course) as a giant air compressor. Thing is if you can do that then you use wind turbines to generate electricity to power more efficient electric cars (then all you have to worry about is battery recycling).

<hmmmmm>

"Thing is if you can do that then you use wind turbines to generate electricity to power more efficient electric cars (then all you have to worry about is battery recycling)."

An air car is a better deal than an electric car. If you use wind turbines to charge your electric car, you don't go far on a calm day. It is not practical to store electricity in batteries to charge other batteries. Look at the economics. If you want a four-passenger car to go 200 miles unrefueled (x-prize specs), you will have to spend 200-300 thousand dollars for the batteries, and they will have a limited life. And if you want to build a million battery powered cars, the evironmentalists and metal markets will go ape trying to supply a million tons of toxic materials.

Air is easily stored, and one uses tanks of either steel (cheap and plentiful) or carbon fiber (benign, non-rusting). Air tanks don't explode; they leak, and leaked air is neither toxic nor combustible. Would firemen wear them if they were likely to blow up?

I could take a mini-van or extended cab pick-up truck and convert it to air easily. The IC engine could be conveted to air. As a petrol engine, the brake mean effective pressure is a few hundred psi at best, while the stored air will be over 1000 psi, so sprightly performance is available. (You should get 200 miles range out of about 80 cubic feet of tanks) Usually, one will inject only a little air (at about 300C) to get maximum expansion, so the exhaust will be cool. If the compression ratio (something like 30:1) and expansion ratio are the same, it is a reversible, therefore efficient, process, thermodynamically. You start with ambient temperature air and water, compress them, expand them, and exhaust ambient temperature air and distilled water. No heat is lost; the only losses are from friction. You will want an electric motor (or wind turbine) of about 10 kW to drive the compressor (for recharging overnight), which might be expensive, but the whole system will be much cheaper than an all-electric vehicle, and the air tanks won't need periodic replacement. (You would need a larger than 10 kW motor for an all-electric car, so the cost of driving the compressor is not an issue) If you have an infrastructure of "gas (air)" stations, with large storage tanks, a car could be recharged as quickly as you can pour gasoline into a gas tank, so long range driving is practical. (A battery car is, on average, no faster than a bicycle over ranges of a few hundred miles, because it usually takes hours to recharge the batteries, and since each car requires a wired parking space, the infrastructure requirements are much greater)

The French air car (the Midi) is entered in the alternate x-prize contest (2 seats, 100 miles), but I doubt it will win, as they are not efficient enough, thermodynamically. The trick is not wasting heat energy.

By the way, using liquid air is a loser. Again, the thermodynamic efficiency is poor. It takes energy to liquify the air. It takes energy to vaporize the liquid air, which means either burning fuel or having huge heat exchangers to use the heat from ambient air. The exhaust will be cold. Such a vehicle will leave a cloud of fog or snow behind it, which will provide lots of employment for tort lawyers..

The electric car is still not an ideal solution due to the batteries and the fact you still need to charge them using high energy fossil fuels. I am following developments closely and hopefully we will have an environmentally sound solution in the future, but we still haven't got one yet.

With regard to energy storage don't forget that battery energy density storage is an order of magnitude (or more) greater than air.

In the mean time we are still left with petrol vehicles (or perhaps push bikes). I have this odd feeling that the solution in our life-times is going to be switching to a more environmentally friendly fuel (perhaps methane gas hydrates), rather than electric, air, hydrogen or any of the other alternatives proposed. It just seems like the thing we humans would do when gas prices rise to unbearable levels.

But before then, actually have a look at the french air car website closely and our comments on CR4 regarding the technology. I am not an expert on the air compression side but their are glaring problems with the rest of the system as a whole. There may be something there that you may find useful if you wanted to try and further develop the concept of an air-powered car. The air-powered car may use a very low energy fuel (compressed air) but at least its an environmentally friendly vehicle alternative. Perhaps it could be the answer IF we can find a way to naturally produce compressed air without burning high energy fuels (no, wind farms are not the answer, there are better uses for that high energy fuel=electricity). Perhaps geothermal power plant waste heat or a man-made tornado, etc could be the answer (although that could be harnessed to produce electricity, so perhaps the waste from that process could be used).

If we cannot find a viable solution to producing the air then compressed air will stay where it actually works, in the industrial factories and plants.

A French inventor build such a motor and equipped a car which is now build in series in India by Tata.

Originally, they announced plans to produce such a car in 2008. Last I heard they were saying 2009. I have seen no indication that it is in series production. Do you have an article indicating sales numbers?

For your information Tata's grand mother was French lady. May be she brought it with her.

Check Quasiturbine.com

FYI the old Quasiturbine co. went out of business and sold off everything. Apparently the buyers have taken advantage of the new 'climate' for air power and have given the Quasiturbine a new lease on life.

Never the less air powered vehicles have more disadvantages than other power systems.

Air power is a non starter (literally) due to low energy.

What I would think could be more effective is a small turbine,
which is supposed to be a relatively efficient combustion engine,
driving a small electric generator, up in the 90's for efficiency.

The turbine can burn low grade fuel, e..g paraffin etc. and, matched
to the generator, provide steady (efficient) output to a floated battery.

The whole being greater than the parts due to their respective efficiency.

One day (if not done before) I would like to give this a go; if only for
my own transport. I am talking very small scale here, and small turbines
are becoming available now. Or is there a better way?

jt.

I used to be indecisive but now, I'm not so sure.

This is an appealing idea, and one I'd considered for my plug-in hybrid. Current small turbines (APU size) are thermally inefficient, however. They are also costly. Thus in the 5 - 100 Kw range, diesel generators are commonly seen. In aircraft, where weight of an APU is as important as its efficiency, turbines are common. I considered using the turbine from one of these, but even a common modern tech gasoline engine was more efficient and far less costly, even if the gasoline engine is purchased new, and the turbine is purchased used.

However, I'd love to pursue the idea further, if I had time. I suspect that a turbine built specifically for good thermal efficiency at a fixed output speed and load could be a light, compact, and more reliable alternative to a piston engine. Of course, a major issue would be emission control. Diesels now require awkward, complex systems to meet current standards. I suspect that getting a turbine to meet the standards set for road vehicles would be far more difficult.

If I recall, the Chrysler turbine car was about half as efficient, overall, as a gasoline engine powered car. It got, if I remember, about 10 mpg overall, but very good efficiency at cruise. The main problem was high consumption at idle and low speeds/loads. I note, from this article, that Chrysler claimed about double the efficiency at cruise of a standard engine of the day.

A fifth generation turbine, however, (I just learned from the linked page) was said to achieve 22 mpg in the EPA cycle (although if this is the highway cycle, that is not very good for the light [by today's standards] M body car in which it was installed). The efficiency numbers per stage provided indicate an overall efficiency of about 50%, but this assumes that the engine block does not radiate heat, and assumes no loss in the 10:1 reduction gearing that would have to be considered part of the engine to bring speeds down to ICE levels. However, the 22 mpg figure does not support that efficiency so high was achieved in practice.

The same ideas in a hybrid, however, would eliminate the idle/low load and lag issues. If I had time and/or loads of money...

I wonder what happened to the GM turbine-powered over-the-road trucks.

This isn't a small scale, but isn't the Abrams M1 Tank uses these same principals for its turbine?

The Compressed Air Car, developed by Motor Development International (MDI) Founder Guy Negre, might be the best thing to happen to the motor engine, and people all over the world.

The $12,700 CityCAT, one of the planned Air Car models, reaches 68 mph, goes for a range of 125 miles. It will take only a few minutes for the CityCAT to refuel at gas stations equipped with custom air compressor units. MDI says it should cost only around $2 to fill the car up with 340 li ters of air!

The Air Car will be starting production soon, thanks to India 's TATA Motors.

My prediction #1. Guy Negre will be remembered as one of the greatest confidence men of all time.

Prediction #2. The Air Car can not be demonstrated to go 125 mile on 340 liters equal to approx. 12 cubic feet of compressed air at any pressure.

Prediction #3. TATA will never produce a thousand air cars.

Make your choice and place your bet!

Please look at previous threads regarding "theaircar" for more information. The claims they make do not match what is physically possible (unless you believe in over unity).

Thanks Guys for all the information on this question I guess it would take alot of air to move a motor of that size. I have alot of Ideas but no education in any of the fields. Like this one That Just Hit me. What If you took a V-6 Gas motor and took 2 of the cylinders and used them for the air compressor motor to air up the tanks and the other 4 cylinders took and shot high compressed air in them,What Yall Think?

sounds good anyway...lol

Sounds like what they used to do with VW Engines.

remove the sparkplug, and use 2 cylinders as the compressor, the other 2 as the motor.

Someone sent me an email a couple of weeks ago showing a series of vehicles (car and truck) now built in India that is air powered. Google that and see what comes up.

Kyoto: "Someone sent me an email a couple of weeks ago showing a series of vehicles (car and truck) now built in India that is air powered. Google that and see what comes up."

Pretty promotional photos. Guy Negre has to sell his first one to the public. Tata motors MAY have a few short range models for testisting and promotion purposes. Don't expect full blown production and Air Cars for sale any time soon.

Do a search on CR4 and Google for Guy Negre, Air Cars, Air Motors, etc.

Look for the Neal Tank while your's at it.

Hello DJCharlie50

There are two problems:

1. Pollution where the air is compressed
2. Low stored energy in compressed or liquid air.

If you did not mind (1) above, and trailed a very long hose from your car all the way from the compressor station, it is quite a good idea, although efficiency is low.

But I just hate the thought of tangles, and driving back in reverse, the way you went, to reel in that very long hose.

Kind Regards....

Pollution where the air is compressed? Is Compressed air Pollution if it is I didnt know that. And why cant they mount a compressor pump on the motor?

Hello again DJCharlie50

Do the full Maths.

I am assuming that you truly want proper answers to your above questions, so here they are:

Air Motor technology is NOT efficient, nor can it ever be:

Pollution occurs at the compressor station, in the form of heat at the compressor, as that air in your tank, or long hose, needs to be cooled before it may be used, and that cooling wastes the heat energy, by radiating it away in the form of hot air or water.

Add to that, the pollution at Power station, losses in transformers and distribution lines, and the losses are not additive, but multiplied against each other.

Simple Example:

Energy loss in mining coal (huge) & loss in storage & loss in transport to coal-fired power station & loss in storage & loss in heating boiler & environmental issues with smoke and ash & loss in boiler & loss in pipework to turbine & loss in turbine & loss in Alternator & loss in Power Station transformer & loss in High-Voltage transmission lines & loss in switchyard connections & loss in HV - MV transformer & loss in MV distribution system & loss in switchgear & loss in MV to LV transformer & loss in cabling network to compressor station meter & loss in meter, switchboard & loss in wiring to compressor & loss in starter for compressor & loss in compressor & loss in Air motor......

Note there are other losses, but the above summary would be the major points of energy loss....

To all the above, when multiplied out as % losses, remember that all the above had to be once made, installed, maintained and eventually replaced.

Now....Do you see that using an air Motor, itself very inefficient, when all the "supply losses" are taken into account, that your air motor may reach 3%.

Yes!! Three percent energy efficiency in a car.

So the Energy input to your 40HP car is really 1320 HP or close to that figure.

Your second Question:

Yes, a compressor pump could be mounted on the motor. What is it going to run from = the compressor pump motive force?

If you run it from the air motor, it is going to drop the total efficiency below 1%.

That would mean the energy input would be 4000 HP, to obtain an output of 40HP.

If you run it from a petrol-powered motor, that motor is going to have to put out 100HP for each 15HP the air motor puts out = hardly efficient, as there would be an immediate nett loss of energy, as you may surely see. (Energy input is over 6 times energy output)

But then you need to factor in the energy losses from the oil surveying, well-drilling etc, oil well intake pipe, right through the long supply chain of shipping, tankage, refinery, tankers, storage losses etc, to getting that petrol into your on-car tank, plus the energy cost of moving the mass of that petrol along in your car, and those energy losses are also larger that for the coal-fired system listed above.

In all these "energy-saving" thoughts, please remember to do the correct maths, for the full chain of events.

Most 'experimenters' in the field of "alternative energy' including the "air motors" and other "gadgets" promoters, do not bother to do the maths, because the results would immediately show that their "sometimes profitable (To the sellers only) attachment to a motor", is just a swindle.

Remember: Do the Maths, on the full energy chain, and you cannot go wrong.

Trust you have a better understanding of why the air motor in a car, is not, nor can it ever be, a practical energy-efficient solution.

Kind Regards....

<<Air Motor technology is NOT efficient, nor can it ever be:

Pollution occurs at the compressor station, in the form of heat at the compressor, as that air in your tank, or long hose, needs to be cooled before it may be used, and that cooling wastes the heat energy, by radiating it away in the form of hot air or water.>>

Someone hasn't been reading. The whole point is the heat from the compressor need not be wasted nor does the air have to be cooled before it is used.

As for the other pollution at the compressor station, one must compare with other forms of energy. For example, one could argue that using gasoline causes uranium pollution, as the wars waged to secure the gasoline spread uranium over the landscape. Let's see, we maintain a trillion dollar military, burning huge amounts of fuel in aircraft and ships, to maintain a supply of oil, so shouldn't those costs be considered in evaluating gasoline autos?

How about we just look at the simple economics, the price of 70 kW-hrs of electricity vs. two gallons of gasoline? Also, I can gererate compressed air directly with a wind turbine. How many gallons of gasoline can you make with a wind turbine?

Hi Esbuk, this is PentaPower and I say 'Bravo, well put!' Others don't seem to realize that change is inevitable. We are advancing on the 'enemy lines' we will not surrender. If more people would use their minds constructively, instead of denying the fact that we can produce anything that we really put our minds to, we could get things done a little quicker. Keep up the good work. PentaPower.

So there will never be a good resource to replace gasoline or another words to go green on car because of manufactoring of the products just to go green you would still be polluting.

Hello again DJCharlie50

Yes, you are correct in that observation.

All manufacturing processes are polluting, as are all transport processes.

The thing we need to do, is minimise those pollutions and losses.

It was calculated back in the early 1970's, in the Article in "Scientific American", that use of a bicycle was the most efficient and least polluting form of transport.

The bicycle is over twice as efficient as walking.

That has not changed, but we cannot move vast amounts of food and other goods by bicycle.

Because the most efficient motors are electric, and the electric wheel is the most efficient powered vehicle to ground surface wheel, much present and future research needs to be done into electricity on-board storage, and methods of improvement in solar power generation, to charge those on-board storage batteries.

Chemical methods of energy storage = batteries, petrol, diesel and the like, are far more efficient methods and safer than trying the "on-board Supercapacitor" system, where catastrophic failure of the storage device would render the immediate vicinity into a very large crater.

Sure there are dangers (and Pollution) with storage batteries, petrol, diesel, but the attendant risks are well-known, and may be allowed for.

Pollution is always going to be with us, and a major effort should always be made to minimise it.

Kind Regards....