The Air Car

[loftyendeavors]

Check it out...
And so the inevitable questions arise: What are the possibilities for incorporating this compressed air technology into our e-bikes?
It seems that there are many people working on this technology,
Here are some of the links that I've found:
http://www.theaircar.com/
http://www.engineair.com.au/airmotor.htm
http://www.psiautomation.com

And, the news story:
http://rawstory.com/news/2007/Air_car_runs_on_compressed_air_0104.html
BBC News is reporting that a French company has developed a pollution-free car which runs on compressed air. India's Tata Motors has the car under production and it may be on sale in Europe and India by the end of the year.

The air car, also known as the Mini-CAT or City Cat, can be refueled in minutes from an air compressor at specially equipped gas stations and can go 200 km on a 1.5 euro fill-up -- roughly 125 miles for $3. The top speed will be almost 70 mph and the cost of the vehicle as low as $7000.

The car features a fibreglass body and a revolutionary electrical system and is completely computer-controlled. It is powered by the expansion of compressed air, using no combustion at all, and the exhaust is entirely clean and cool enough for use in the internal air conditioning system.

Tata Motors is known for its interest in innovation and has been selling compressed gas buses since 2000. It is currently working on producing the world's cheapest car, which will be almost 100% plastic and will sell in India for about $2500.

Tata is also expanding into the world market. It acquired Korea's Daweoo in 2004 and is now the top bidder to purchase the originally British Jaguar and Land Rover lines from the United States' troubled Ford Motor Company.

The following video is from BBC's BBC World, broadcast on January 04, 2008

 

[ngocthach1130]

I dunno, sound like they run very high pressure tank on those thing. Our bike is pretty much bare frame. Those car will have protection wall and enclosure. Us will be like sitting on a time bomb. Some accident and we get blasted sky high. Or maybe the valve broke and we have a rocket strap to our bike. Another problem i see might be rapid release of the pressurized air. Might cause frost bite from the waste down since we literally straddle the bike, as well as the tank(probably).

Cold nuts goes well on ice cream. Can't say the same for the other one.

 

[safe]

If you are going to go to effort to compress a gas, then why not make it hydrogen?

With hydrogen you also get many times more power out of it when you use it in a fuel cell.

All these compressed gas ideas fall apart in accidents... I just would rather have my power source wrapped into a battery so that if you get into a crash it might leak a little, but it wouldn't cause any serious problems.

 

[Drunkskunk]

Sounds safer than Lipo.

Coal mine trains have been running compressed air since the begining of last century. If you get the pressure high enough, its as energy dense as batteries, so why not?

 

[knightmb]

I don't know how much has changed since early 2004 when I first heard about this, but from last I remember, the numbers didn't exactly work out. A while back, this was a big topic, so myself and some others starting doing the simple math to figure out how much energy you can store in a tank and how much you could extract safely. I remember running into a problem about how fast/far these vehicles would go because of certain pressure requirements to cover X amount of distance at X amount of speed.

Kind of like with our e-bikes, you want to go faster than 50MPH and all of sudden it takes a lot more battery power because of air friction. The main problem we stumbled among and never could get a response from the manufacturer/company at the time that was selling came to how much pressure are you storing in the tank, what size is it, and how efficient the extracting process was at using that energy.

If I ever find all that math work and such I'll post it up, but to sum it all up, the idea was good, it's just to implement the speed and distance would take pressures that rival nuclear submarines in miles of deep water to achieve.

 

[Dr. Shock]

As I recall from high shcool physics, the more you compress a gas, the more heat (i.e. wasted energy) you generate. If you can capture the heat and use it for something else maybe it could pencil out, but there seems to be some basic limitations on efficiency for compressed air.

 

[loftyendeavors]

Yeah I'd be very curious to know what kind of range you could expect out of a small air cylinder, and how many lbs it would weigh when fully charged. In terms of the hydrogen comment, it seems that this technology would allow you to simplify the process a bit. With a hydrogen fuel cell, the hydrogen would generate electricity in order to drive a standard electric motor, however, with this pneumatic engine, you may be able to go directly from stored power source to engine with no steps in-between.
Any more thoughts? I think this technology might be great in an e-scooter/motorcycle.

 

[Drunkskunk]

it had been a while since I read this. here's the article I found, apparently, they were doing this in the 1800s.
http://www.dself.dsl.pipex.com/MUSEUM/TRANSPORT/comprair/comprair.htm

But even more intresting, is an article on Air powered bicycles from 1902! (and other oddities) http://www.dself.dsl.pipex.com/MUSEUM/TRANSPORT/oddbike/oddbike.htm


As I understand it, Air power is prefered to electric anywhere a vehicle has to operate in a flamible enviroment.

 

[loftyendeavors]

These engines seem to be avaliable now and put out some pretty impressive power, however I'm not sure about how much compressed air it consumes and how fast. Maybe someone less mathematically challenged than myself would be able to enlighten us on the subject?
Which one would you choose for an e-bike, e-scooter or velomobile application?
http://www.psiautomation.com/motor-select.cfm

 

[loftyendeavors]

And I wonder what kind of controller would be required?
Also, it seems that the safety concerns could be mostly overcome by using a carbon-fibre compressed air tanks which fracture instead of acting like a rocket as would a steel one.

 

[fechter]

The controller could just be a valve that you open and close. There would need to be some kind of pressure regulator, which could also act as the throttle. A heat exchanger between the throttle and motor would help re-heat the air to increase its volume.

An air tool motor might not perfrom well in this application. It would have enough power, but I don't think the efficiency would very good (short range). I remember seeing very large air motors used on mining equipment. Those had some serious horsepower. Air power might be good for a dragster since there's no real limit on how fast you can discharge.

As I recall, that air car had a specially designed motor that minimized losses.

I also recall seeing an air powered bike that used long pistons connected directly to the pedal cranks like a steam engine. This would look really goofy, but would be hard to beat for efficiency. I wish I could find the picture of it.

One interesting aspect of air power is when the motor is heavily loaded or near stall, the efficiency actually increases.

 

[monster]

with the hydrogen comment he means that you could get twice the energy density by first using the gas in the air motor and then piping it to a fuel cell to capture its chemical potential. this could be an air/fuel cell hybrid. i think air tools are used in flammable environments instead of batteries because electric motors have sparks on the brush contacts which could cause explosion, and not because they are better efficiency.

 

[EMF]

If you are going to go to effort to compress a gas, then why not make it hydrogen?

With hydrogen you also get many times more power out of it when you use it in a fuel cell.

All these compressed gas ideas fall apart in accidents... I just would rather have my power source wrapped into a battery so that if you get into a crash it might leak a little, but it wouldn't cause any serious problems.

If you have a wreck, I would rather be in an air car than in a car with a tank full of hydrogen. Also, I would be paranoid to part the thing in my garage without some sort of detection and air ventilation system etc.

I have been following this air car for years. It's a great idea. The stuff coming out of the tailpipe ( air 0 is cleaner than the air we breath. It's such a good idea, when he first got started, he was receiving death threats and warned to drop the idea. For some reason, he kept going. I think the car only needs one quart of oil and I don't know if you ever even have to change the oil.

Hydrogen is a nightmare IMHO and I also think it's a boondoggle in that it is costly to produce and the infrastructure is going to be needed to be in place prior to acceptance. Say hello to your new masters!

The thing we need is to "get a way from the pump". Do we really want to belly up toanother pump system (hydrogen) and be at the mercy of some big companies again? I don't! I am tired of some yahoo metering out my fuel to me. I'd rather put a plug in my car and charge up at home. At least when I could. Even though this is on a meter, they can't mess with it as much as a new subsystem of energy, whining about cost, "research" monies and such. Plus, we can be sure the government will belly up to the bar with a nice hydrogen tax if we all get on that bandwagon. I can see the Department of Hydrogen Safety popping up real quick with a bunch of worthless inspectors, that never leave their desks. Also, I'm sure my homeowners insurance would be a lot more due to having a hydrogen car. :lol:

Sadly, we wont see these air cars in the US anytime soon, as I think they use a glue construction method to hold them together and this wont fly in the US.

 

[Drunkskunk]

The thing with Hydrogen is that it takes more energy to produce than the hydrogen contains if burned, and using in a fuel cell is actualy less efficent than burning it.

The emmisions from the tailpipe on Hydrogen are cleaner, but it emmisions from the power used to put it in the tank off set any advantage of it as a better fuel sorce. Before it becomes a viable fuel sorce, there needs to be a cheap, energy efficent way to crack it.

But I like the idea of using the pressure to run a pre-motor before it gets to a fuel cell.

 

[JRP3]

I have to say that I always find these air car articles very frustrating, "they run on air!" Of course they really run on air that was compressed using electricity, with all the associated losses. Frictional losses during compression and frictional losses when decompressed. Seems like a terribly inefficient use of electricity to me, plus the wear and maintenance on 2 motors, the compressor and the "decompressor" or drive motor. EV's are much more elegant, at least to me.

 

[Link]

I have to say that I always find these air car articles very frustrating, "they run on air!" Of course they really run on air that was compressed using electricity, with all the associated losses. Frictional losses during compression and frictional losses when decompressed. Seems like a terribly inefficient use of electricity to me, plus the wear and maintenance on 2 motors, the compressor and the "decompressor" or drive motor. EV's are much more elegant, at least to me.

Well, I did read something about a freaky compressor tank that kept itself full. No outrageous claims of perpetual motion, but a heat pumping process. I think the important thing was that the compressor was inside the tank, and so was able to recapture its own energy (plus the thermal energy of the air it pumped in) to keep it running. I would imagine that it would work terribly in cold weather. Perhaps some sort of pneumatic/electric hybrid 8)?

If I get the stuff, I'll make one, just to see if it works. If not, oh well.

 

[monster]

your right a bout the whole hydrogen economy swiz thing. its just another thing to be addicted to gas today, hydrogen tomorrow. unless we can electrolysis the stuff from wind power in our back garden.

 

[rgody]

Here you can see an air-bicycle.
The inventor is from Uruguay.
http://www.youtube.com/watch?v=2hI4C9UTr8I

I agree is not the best in efficiency but if you can recharge in a pump station for free is not a bad Idea.

Regards

Rodrigo Godoy
Viña del Mar - Chile

 

[Toorbough ULL-Zeveigh]

I agree is not the best in efficiency but if you can recharge in a pump station for free is not a bad Idea.

Regards

Rodrigo Godoy
Viña del Mar - Chile

I don't know what it's like in the rest of the world, but around here free gas station air compressors have almost completely disappeared.
Even if you can find one they are always in a state of disrepair (at least always when I need one).
The only place with well maintained, fully functioning compressors are the Esso self-serve gas stations & that's becuz they charge 50¢ for about a minutes use.
This vending machine approach seems to be the growing trend with a few others now doing the same.

 

[mcstar]

A little research on the "air car" reveals that their tanks are rated to a maximum pressure of 300bars. This translates to a little over 4000psi. That's in the realm of dive compressors which can reach around 3000psi or so. This is not easy to do. It requires at a minimum, a $5000+ multi stage compressor rig with at least a 5hp engine (some are electric motors rated at 5-10hp). Many commercial units have many times that hp rating. These compressors can charge a single scuba tank (10liter) in about 1/2 an hour. The tanks they are using are 400l tanks. This means it will take around 400/10*.5hr = 20hours to recharge the tanks using a 5HP dive compressor as the charge source. It makes sense, 5HP is only about 4KW of power/hour. Multiple by that times 15-20 and you start to get within the range of what it takes to push a car sized object 100mi at 50+mph. To get around this complication, scuba diving outfits have complicated multi bank recharge stations that essentially just hold a large volume of compressed gas to allow for quicker rechareges. So you can image an "air pressure station" being composed of a seires of huge steel tanks connected to a power-gen sized diesel engine running compressors 24/7. This engine/compressor would have it's own losses and power requirements. I suppose you could try to make it as clean as possible. But you are still having to pay someone for the costs involved in building/maintaining/operating that station. Sounds little better than what we have now.

 

[Drunkskunk]

mcstar, I think you hit on a key point here. Air tankes are just storage. since its an inert fuel source, it can only store the amount of power it took to compress the air into there originaly. if it takes 5000 watts to put 5000PSI in a car size tank, you would only have that much potential power, minus all the lost energy that comresssing air causes, so say 4000 watts potential, and then realize that using it won't be close to 100% efficent, and will decrease as the pressure drops, so maybe only 2000 watts available for a 5000 watt investment.

But the advantage here is you could convert wind, tidal, or any other source into stored power without some of the drawbacks of electrical storage.

 

[mcstar]

Yes, exactly! From a practical standpoint, all these claims must be balanced with reality. Compressed air is stored energy much the same way that H2 is just stored energy. Since H2 quickly bonds to O2 when allowed to mix with it (even at relatively low temperatures), we must expend at least the amount of energy it released when it bound to the 02 to begin with to have any quantitiy of useable H2. That means that at best, (iow 100% efficient process) H2, and compressed air represent types of exotic batteries...NOT ENERGY SOURCES.

 

[Dr. Shock]

Really, compressed air technology is just a subset of steam technology. When modellers make miniature steam engines, they usually drive them with compressed air. Perhaps you could make a really small steam engine to charge the tanks at a constant rate, and then use the tanks as batteries. There's no getting around it though, you have to burn something somewhere (even if it is hydrogen in the sun) to get power.

 

[Mathurin]

Nice thing about the air car is cost, if you compare it to an equivalent EV it should costs less then the battery pack alone. Tanks should be good for ~25 years? With a hydrostat every 5 years? And since battery cost is ~10X more then electricity used to charge an EV, so even if it would take ~4X more electricity to run the equivalent air car... And while neither could use long range as claim to fame, but the air car has the advantage that it could also use stuff that burns to make it go, while the EV would need another motor to do it. Also the heat generated during charge isn't all loss as with the EV, since keeping it in the tanks as much as possible lets the motor get better eff for it. Also the exhaust on the air car will be freezing cold, most likely the most powerful AC you'll ever see while in the EV you're gonna want windows that open.

I first read about it in '94 in Science & Vie magazine, there were just a handful of people working on the project, and by now afaik there's still only a handful of people working on this project and they're still running around in prototypes. They've obviously evolved tho, their motors arn't converted car burners anymore they seem to be 100% custom made 4 stage thingies with a fancy gas powered preheater after the intercooler (interwarmer?) and the ability to use gas to run them directly and so on... Also Tata motors invested a few million in the technology last year so there's probably something to it... But in the end you still can't buy one.

 

[disadvantage]

Hopefully the inventors fixed the problem that Mickey & Goofy found. :lol: