For inner city drivers, a car that uses no gas at all: the Air Car

[ProfessorPlum]

http://theaircar.com/

When you were a kid, did you ever have one of those toy cars that you pumped up with air, then released the pressurized gas to drive the car’s wheels? A European engineer has been taking that basic principle and trying to design an actual car around it. The basic idea is that you have a tank that you fill with pressurized air, then release that pressure in a controlled manner and harness the potential energy of the air pressure to create kinetic movement. A prototype has been made and they are starting to bring a small fleet of these cars into test production. Of course it is small (very small indeed by American standards), but bear in mind that in European cities cars are already extremely small because a) gas is very expensive and b) European cities were not designed with parking in mind.

How far/fast does it go?

“The end product is a light weigh vehicle that can reach speeds up to 220 km/h (even though the legal limit is 120.)” That’s about 120 mph.

“The recharging of the car will be done at gas stations, once the market is developed. To fill the tanks it will take about to 2 to 3 minutes at a price of 1.5 euros. After refilling the car will be ready to driver 200 kilometres. The car also has a small compressor that can be connected to an electrical network (220V or 380V) and will recharged the tanks completely in 3 or 4 minutes.”

The car is lubricated with a single quart of vegetable oil, which is changed about every 30,000 miles.

Pollution? None, as it releases air into the air. The only pollution involved is in the electricity to run the air compressor to recharge the tank.

Safety? One concern with a car with a pressurized gas tank is that it would explode and propel the car in a random direction in case of a crash. This has been dealt with by designing a system that splits open in a defined way in case of a collision, dissipating the air safely.

Here’s something else cool about these cars (pun intended). When air is compressed and then allowed to expand, it cools down. This is called the Joule-Thompson effect, and it is why you pucker to blow and cool down your food. Putting pressure on the air as it passes through your lips causes cooling when it expands. So the air coming out of the car will be cold, and can be used to air condition the passengers.

They are also developing models that have duel fuel systems, switching to liquid fuel if necessary (for example if you run out of air pressure).

It’s still pretty pie-in-the-sky, but it makes me smile to read about it and think that maybe someday urban drivers will used compressed air to get around.

[Skidmore]

If it is possible, then some effin' corporation will start charging

us to breath because they will find a way to buy up the air over a geographical region.

[savemefromdumbya]

1. I WANT ONE!

where do I buy one?

[ProfessorPlum]

3. Me too

they are still in the prototype phase, unfortunately.

[savemefromdumbya]

5. I'm not sure if I like the shape?

[ProfessorPlum]

8. Fairly typical of Eurpean mini-vehicles.

I'm sure most Americans would hate them for being so small.

[savemefromdumbya]

39. I used to have a Citroen

IT wasn't quite as round as that

[n2doc]

66. That is always the friggin case

I have lost track of how many cool things are in the "prototype" category. They always seem stuck there. I wonder why?:eyes:

[Gregorian]

2. Someone, somewhere is compressing air.

So the car doesn't emit pollution, but the place that compresses the air does. One advantage of a central provider is that due to it's increased mass, it is more efficient than lots of little engines that we have in individual cars. Other than that, it's just polishing the same concept we already have.

[ProfessorPlum]

7. Again, agreed

this is also the "problem" with electric plug-in hybrids.

Two points: first, having a few very well regulated energy production plants has got to be less polluting than having millions of internal combustion engines running all the time, in various states of tuning and repair.

Second, if their statistics are true, then they get 200 km from 2-3 minutes of running an air compressor. I think you'd have to burn a lot more gas to move a car 200 km, even a small car like they have, than to power an electric air compressor for 2-3 minutes. Wouldn't you? That efficiency would go a long way to reducing our use of fossil fuels for transportation, even if they were burned at the power plant.

[Gregorian]

15. Those are good points.

Individual systems are almost always in a state of less than peak efficiency. Although with computer control, that isn't as true as it used to be.

But there is another problem that detracts from this whole concept. Entire infrastructures have to be made or altered. Pressure tanks, distribution of compressed air, etc.

But the fact that a centalized system can be more efficient, and eliminate a lot of individual mechanisms is tempting.

Also, part of the difficulty of solving the transportation energy problem is that even though the majority of users are commuters, there are still those who simply cannot use an alternative to big powerful vehicles. Construction workers, farmers, shipping. It's ugly.

Overall, transportation is just one fraction of the big energy picture. And ultimately, the solution is not of increasing efficiency, but decreasing use. Ie., number of users. Or that dirty word- population.


edit- On question. Why not just generate electricity? An electric motor is far simpler to manufacture than that silly flip-flop engine. And generating electricity is more efficient than compressing air, even if they recapture as much heat as possible. These are just off the top of my head thoughts.

[ProfessorPlum]

18. I'm not sure the infrastructure problem is so big for this tech.

Especially compared to, for example, hydrogen.

Most gas stations already have an air compressor, for example, and with 3-4 minute charging time, could probably be up and running with a couple of compressors very quickly. You probably wouldn't have to distribute compressed air at all, as it surrounds us constantly and can be compressed (the car itself even has its own compressor that can be plugged in) just about anywhere.

Transportation use for oil in this country is the biggest by far, we use well over 50% of our oil use for transportation. So this would be a big win in so far as we use less oil to generate the electricity. So it alleviates the short term oil problem, if not the larger, longer term problem of energy usage for an increasing population.

I don't ever really expect a car of this type to catch on big in America as a whole. But even if it sees some limited use in places where it makes sense, like cities, that would be cool.

[Gregorian]

28. An ordinary compressor won't solve anything here.

It's not an adiabatic process. Compressing air is highly inefficient. This requires a compressor that can regenerate using the heat that is lost in the process of compression.

I hate these energy discussions. They always start out sounding so nice, and ending up in the details. I like simple stuff, myself. :) Bikes rule.

[ProfessorPlum]

32. Please do stick to the simple stuff

I don't think your grasp of thermodynamics is quite what you think it is.

[Wrinkle_In_Time]

49. What a stunning amount of woo-woo nonsense.

All excerpted quotes are from ProfessorPlum, the OP, throughout this thread.

Here’s something else cool about these cars (pun intended). When air is compressed and then allowed to expand, it cools down. This is called the Joule-Thompson effect, and it is why you pucker to blow and cool down your food. Putting pressure on the air as it passes through your lips causes cooling when it expands. So the air coming out of the car will be cold, and can be used to air condition the passengers.

(1) But air heats up when compressed and there is energy expended in compressing it. Since compression machines are not 100% efficient (nor perpetual motion) there is a net increase in heat or entropy. Ergo, ergs.
(2) The cooling effect on food is not because you mouth is a refrigerator, numb-lips, it is due to convection. cf. "wind chill".

Most gas stations already have an air compressor, for example, and with 3-4 minute charging time, could probably be up and running with a couple of compressors very quickly. You probably wouldn't have to distribute compressed air at all, as it surrounds us constantly and can be compressed (the car itself even has its own compressor that can be plugged in) just about anywhere.

(1) How much pressure can an average gas station compressor produce? What is the theoretical pressure rating of the reservoir in such a car and what is its theoretical capacity? How many joules of energy can it store and how far can this propel a vehicle of such weight? {I typed "theorectical" twice in that sentence: I was thinking from whence this theory sprung}.
(2) From where does the car get the energy to run a compressor?

I don't think your grasp of thermodynamics is quite what you think it is.

:rofl: :crazy:

[ProfessorPlum]

72. You are right

Apparently, the Joule-Thomson effect is relatively negligible (though still present) for pursing your lips - convective heat transfer is much more important for cooling your soup, and the JT canard is an old physicist's tale told to me while I was still at the knee. However, the air coming out of this car will be cool indeed, because not only is this air expanding, it is also doing work. So it loses some amount of heat.

You are also correct that air heats up when compressed and that it takes energy to do so. I don't know that I've ever argued otherwise. But it has nothing to do with the efficiency of compression machines - unless you are talking about the compressors inability to do their work isothermally. There will be some adiabatic compression, which will raise the temp as the air is compressed.

The onboard compressor for the car is plugged in to an electrical outlet, as I wrote above, not sure what is funny about that. The car runs the compressor using the same source of energy that you use to post here.

[kestrel91316]

23. Ok, you've convinced me. It's just TOO HARD to come up with an

alternative. I guess we should all just throw up our hands and quit, then lay down and die.

[Gregorian]

29. We could be going backwards.

I'm not a naysayer. I just know enough thermodynamics to make me sound like one. The second law of thermodynamics is easy to overlook.

[kestrel91316]

54. Thermodynamics MUST NOT be our only consideration.

Renewability and avoidance of foreign entanglements have to be considered also.

The end goal is NOT maximum energy efficiency. It's maximum sustainability and independence.

[ProfessorPlum]

25. What do you mean?

Generate electricity in your car? We already do that with our internal combustion engines and alternators.

Generating electricity is not efficient at all, especially if you are using heated air to move mechanical parts, a la internal combustion engines.

Some recommend fuel cells for converting hydrogen to electricity to move a car, but generating the hydrogen is extremely inefficient as well.

Not sure what your point is, here.

[Gregorian]

26. Oh, I meant generating electricity in lieu of compressed air.

Why compress air at all? Of course, the energy ultimately has to come from something. And storage is an issue. But I still say that working on energy conversion is the real issue. Because that something is what is generating the power to compress air. The next step is fuel cells or batteries to store it with, or compressed air. So storeage is the issue here.

[ProfessorPlum]

30. You compress air to run this particular car

that's why, if you owned this car, you would compress air.

Do you actually have a point? Storage is not an issue, you store the compressed air in the car.

Better means for generating the electricity to compress the air are always welcome, of course. You seem to have run off the rails here.

[Gregorian]

33. If the energy to compress the air is generated of grid.

If efficiency can be ignored, then we're home free. Compress air. But it isn't. We're plugging into the coal fired, fission reactor generated, petroleum fueled electrical outlet. And that is worse than doing what we're doing now. Just burning gasoline. In the overall picture.

[ProfessorPlum]

35. you've slipped from incoherence into total innanity

Assume just for the moment that we replaced regular cars with cars like this, but they were no more efficient. You can make several (correct, in my opinion) arguments that they would be more efficient overall, but let's just ignore that.

The bottom line is, burning less petroleum and burning more coal (or using more nuclear power, or wind, or solar, or geothermal, or tidal, or (Zeus willing) fusion power) helps us in the short term because it alleviates the oil problem. Our coal supplies will last much longer than our oil will.

In the long term, if we use more renewable energy sources to generate the electricity, so much the better. But that's not the problem this car seeks to address.

Oh, also, it relieves air pollution from urban centers and concentrates it in the vicinity of powerplants.

[Gregorian]

38. I take it you are selling these cars?

Why else would you take to personal attacks on me?

I still want to know what kind of professor you are.

[donbrunton]

68. Actually

Here\'s a sailboat that uses wind and solar power to produce hydrogen for fuel.

http://www.haveblue.com/xv1/index.htm

Not sure what you are on about... Denmark for instance - produces 23 percent of their nation\'s power needs from Wind.

[rock]

14. Maybe that place is at a dam, using hydro-pressure

if you will.

[Gregorian]

16. That's great. For a planet of one billion.

People argue that hydro is a terrible ecological design. And it is, to a degree. But it's a far cry from mining coal or producing co2 emmissions.

A hydro dam, compressing air would be wonderful.

One problem with compressing air is the basic thermodynamics. They'd have to recapture the heat, in order to do it efficiently.

So a hydro dam would be better used for just generating electricity.

In fact, off the top of my head, I don't see what the advantage of compressing air, in the first place, is.

[ProfessorPlum]

22. Again, see my post above

the energy they use to get their 200 km out of 3-4 minutes of air compressor time is used much more efficiently than the Carnot-limited internal combustion engines we have now. It's the temperature difference between the exploding gas and the exhaust gas that kills us for efficiency on our current cars.

This design uses nearly all of the potential energy created by compressing the gas for motion. And that efficiency is what wins out for this.

Plus, centralized power production.

[Gregorian]

31. But the Carnot cycle is not eliminated in this.

It's either in the car, or at a central location. I love the idea of compressed air. I've had it on my mind for many years. As regenerative braking, or perhaps storeage. It's not an efficient thing. But it beats what we have for braking now. If done properly, it might be an efficient means of energy storeage. I'm too lazy to do thermodynamic calculations on it. Not to mention I don't know how anymore. First law, second law stuff. It really is an easy one to figure out.

But it's energy conversion that is the issue. How are we compressing air. If we put our money into electrical energy storeage, it's far better than goofing with compressed air.

[Name removed]

34. Deleted message

Message removed by moderator. Click here to review the message board rules.

[Gregorian]

36. I was hoping to avoid personal conflict.

And what kind of professor are you? I do happen to have a degree in mechanical engineering, for what that is worth. Admittedly not much.

All I will say is that I am looking at the entire system. Not just the car.

[ProfessorPlum]

37. You do that.

Have a wonderful day.

[kestrel91316]

21. Easy solution: home solar panel with battery for storage of electricity,

when you come home from work, plug the thing into the battery system. They cold even make it DC rather than AC so you wouldn't need an inverter. Or you could have a windmill rather than a solar panel. It CAN'T require very much electricity to run an air compressor 4-5 minutes..........

Hell, you could rig up a stationary bike-powered generator for the batteries and get your exercise while generating power to pump up your car. How cool is THAT???

Some naysayers are SOOOOOO unimaginative.

[Gregorian]

27. I totally agree.

But skip the compressed air, and stop at electricity. The only difference is the storeage. It's not that simple. And it's not just storeage. It's a complex collection of things. We can make it simple by doing what you're saying. Solar panels and compressed air. That works. No problem. It solves a portion of the transportation problem.

[file83]

73. How much do tanks of compressed air weigh?

I'll venture a guess that they weigh a lot less than a bank of 16-20 large batteries that store electricity. Extra weight = less efficiency.

[TheFarseer]

4. huh?

Is the car kind of 'farting' to get around? This one sounds pretty questionable, but I am enjoying your series in alternative energy cars. Got any more?

[ProfessorPlum]

10. That's all for me for today

But I could post the link about making synthetic oil out of the remains from turkey butchering. That's a pretty cool story.

[TheFarseer]

11. oh, I'm all over that one!

I've even written Congressmen to tell them about it. Seems like one would go really well with all the meatpacking plants around my state. Haven't seen any new articles about it for a couple years. Wonder how Changing World Technologies is doing these days?

[ProfessorPlum]

12. Ever since I read that James "World War IV" Woolsey had

joined their board, I've written them off as lost.

Still, I'd love to hear more about it.

[snooper2]

13. there are videos

at the link you can watch...go to the press section

[in_cog_ni_to]

6. I'm buying stock in Vegtable Oil.

:7 That's a cute, cute car.

[Skidmore]

9. You know, it should would be nice to see some oil executives

in the unemployment line with me.

[Sherman A1]

17. Great Idea

I posted something about the air car a couple of years ago here on the DU and was almost booed off the board, because it would require "so much" energy to fill the compressed air tank that it would generate no savings according to the respondents at that time. An open minded crowd they were not...

[ProfessorPlum]

19. What was your DU name back then?

I wonder if I saw that post . . .

[wovenpaint]

24. I remember that post

and I remember this car!
I'll have to go check out the Aircar website again as to when they'll get here in the USA-back then it was planned for 2007....when they get here, I want one!
Oh, the compressed air availability thing, check your gas station to see if you can fill your tires.

[Mugu]

42. I believe that you will find that a standard compressor

does not have anywhere near enough pressure. They are talking thousands of PSI not hundreds.

And anybody that doesn’t believe that you can suck-up tons of electrical energy in 3 or 4 minutes think again. I’m building a giant Tesla coil that will use 240 volts at 100 amps. It would use more, but 100 amps is all I have in the barn. I expect it to make my electric meter spin like a meat-slicer, but what an incredible show.

Regards,

Mugu

[lonestarnot]

20. Wooohooo can pick it up to park it! Just like Mr. Bean!

[Gregorian]

40. This car is a con-job.

Read the posts at this link, and you'll realize what I was trying to tell you in my replies to this subject.

http://science.slashdot.org/article.pl?sid=05/04/03/2335206

Here are just two of the replies in that link.


Compressed air has great power density, but awful energy density. I.e., you can unload power incredibly quickly from it, but can't store much at all. Even batteries store far more energy in a given mass. This sounds like a big step in the wrong direction, honestly.



The problem with compressed air is that it is basically still a heat engine whereas electric motors are not. Electric motors are 90%+ efficient and compressed air motors, well, 40% maybe.


The bottom line is, the fuel for this car is not compressed air. It's electricity that is used to compress that air.

[ProfessorPlum]

41. First of all, that's a different car

This one is not from Korea.

Second of all, there are also lots of comments on that same thread that support the use of compressed air in this setting.

Third of all, who ever said the "fuel" for this car is compressed air? If you want to get technical, the energy for the car ultimately comes from the sun.

fourth of all, you are an odd bird. I just think it's a cool concept, and I'll leave the technical details to the people who are trying to make it a commercial success. If they fail, oh well. If they succeed, hooray. What's your problem, exactly?

[Gregorian]

43. It IS a cool car.

As an engineer, I don't do things that are unfeasible. And I have actually worked as a professional engineer for some years. Along with being in cardiology among other things. So I'm not just an anonymous idiot in cyberland. Maybe I don't express myself so that I come across professionally.

Many of the comments on that board are by inexperienced people. I pulled out the couple that exemplify the thermodynamics involved.

Simply put, when a conversion step is used, inefficiency and loss is encountered. Like one of the posters said, why not just add hydraulic motors to each wheel. His point was- why compress air, when one can use the electricity it takes to compress the air, to just simply power a motor? Now when one looks at just the car, it's elegant. It's great. No exhaust. Regenerative breaking. But there are details that kill it. That doesn't mean they aren't pushing the marketing like crazy. I'm sure they are. And we might even see these contraptions. But the future is not in air compressed cars.

In my own shop, I do things that might not make sense. I'm not selling them. I'm not trying to solve world problems.

[OPERATIONMINDCRIME]

44. 200 Kilometers At What, 3 Miles An Hour?

I'm disappointed they didn't reference a distance/speed relationship.

[ProfessorPlum]

47. The radius is about 200 km, probably slightly less if you do it

at top speed, which is, if you read carefully, 120 mph.

So, in theory, you could use up all of your air pressure in an hour if you had it floored at 120 mph the whole time, and would have gone about 200 km.

Or, you could drive at a realistic speed, say 60 mph for two hours, and go about the same distance.

Or, you could use it in a city, as intended, and go about 10 miles in as many hours as it took, and still have pressure left over when you got home.

As you suspect, driving at top speed would increase friction and probably reduce your total distance on one tank.

[OPERATIONMINDCRIME]

50. That's Pure Speculation. I Was Kinda More Looking For Facts.

And I don't know why, but I have such a hard time believing a car that small could hold enough air to drive 200 kilometers at any speed.

I'm also concerned about safety. If the check valve goes the full pressure is released sending the car hurling into god knows what.

[Name removed]

51. Deleted message

Message removed by moderator. Click here to review the message board rules.

[OPERATIONMINDCRIME]

53. Know What Would Be Nice Little DU'er? Maybe If They

actually had that information readily available on their friggin site.

See, I did go to the site Mr. Wrong Lee Assumptive, and I couldn't find a damn thing on a distance vs speed comparison. And the only link that seemed viable, the mileage and thermodynamics link, was a page not friggin found.

So quit your preachin. If you have the answer say it. If you don't, then you don't.

[NuttyFluffers]

55. todo para ti, aqui'

right above the building pic on the left column, and nearby on the right the 200-300km (or 8hr of city driving - the other stuff theProf was talking about just takes but a little math). it's just the very next page, under "the car" link. though, the page layout could be more bold-tastic. for a ecofriendly city car 220km/h is pretty bitchin' top speed. the cheapness in fueling is pretty nice, too. if only i could get one here. i wonder what the shipping dues would be...

http://www.theaircar.com/thecar.html

[ProfessorPlum]

56. Gracias

Though it is true, much of that site is in espanol.

[OPERATIONMINDCRIME]

57. Ummmm Try Again There Buddy. Read That Page Too.

I see no details of a speed vs mileage study there. Sorry.

[ProfessorPlum]

58. Dude, (or Dudette), what aren't you getting?

You can go approx. 200 km on a tank of air. You can do that at any speed you want, with a top speed of about 200 km/hour.

That's what they claim. You probably can go a little farther if you go slower, that's just the physics of friction.

I have no idea if it's true or not, but clearly something is not computing for you.

CAn you ask a more specific question? Maybe that would help.

[OPERATIONMINDCRIME]

59. Sure. Point Me To Where It Explicitly Says That You Can Go 200 km

on a tank of air Regardless of speed. I didn't see that claim. But my apologies if I overlooked it.

If it wasn't overlooked, and you are basing this once again on assumption, then that is of no relevance to me.

[ProfessorPlum]

61. The assumption is that what is found on the website has some

relationship to reality. I can't vouch for that one way or another, having never seen these cars in action.

They claim 200 km per tank. Can we assume that that is under normal driving conditions (probably city driving, as these seem clearly designed for urban Europeans)? Or is that too much of an assumption for you?

What is your hypothesis? That if you start to get up to high speeds, the air just leaks out so quickly in an uncontrolled fashion that you go significantly less far than if you crept along?

[OPERATIONMINDCRIME]

62. So You Have Been Offering Merely Assumption Then Outside Of Fact.

That's what I thought.

All I wanted was some factual data on how other conditions affect the mileage, such as speed. They offer none. You keep claiming I should take it at face value and assume broadly that it is 200km no matter what. That is silly. I'm a fan of facts, not assumption, sorry.

You say it can be assumed under normal city driving conditions. Ok, great. But I don't give a fuck about city driving. I'm concerned about typical normal driving, which for many americans involves these things called highways. There's also wind out there on them highways. Wonder how wind affects the mileage. Also pesky things like rain and different terrain. Those things might come into play. Oh yeah, then there's that pesky concept of friction you were talking about. Oh how the world could be better off without friction, but alas, it is here to stay. If only I had some data on how friction affects this car's performance. Sighhhhh.

Assume all you want. I think this is an extremely intriguing concept car and as such want to explore its potential. To do such I need factual data, not snarky assumption. So your comments have done little to help me out. Oh well. Goodnight now.

[ProfessorPlum]

64. Relax, Captain Queeg.

Why don't you write an email to the company, I'm sure they'd be happy to answer all of your questions. I just think it's a cool idea that people might be interested to read a bit about.

Yes, I'm assuming that what they've put on their website is more or less true, but I've stated all along that total distance probably decreases with increasing speed. How much? Your guess is as good as mine, but I'm assuming that it doesn't diminish a whole heck of a lot if you are driving at half the top speed, or what they've put on their website is a big lie. Maybe it is. Who knows?

Wind, rough terrain, and increasing friction will reduce how far the car goes, as it does with normal cars. Is this affect more or less with this car than with normal cars? Again, I wouldn't care to guess, but if I had to, it's probably within the normal losses of other automobiles, as the system of axles and driveshafts are probably not too far off from what is already used.

Next time, take a chill pill, dude. I didn't invent and test the damn thing. I just thought you'd like to know about it.

[muriel_volestrangler]

71. Analysis by l’Ecole des Mines

The translation into English looks a little clunky, but the basics are there:

The actual efficiencies that have been measured are in the low range. Those levels of efficiencies require significant improvements in order to reach the forecasted efficiencies of the baseline system presented in the previous paragraphs.

In conclusion, the global concept of CAT cars using compressed air permits to drive small urban vehicles. The design of the 3-stage 34p01-4 engine of MDI permits to forecast a possible autonomy corresponding to urban usage (between 117 to 146km (73 to 91miles)) taking into account typical speeds from 20 to 50km/hr (12.4mp/hr to 31mp/hr). At high speed, the autonomy will be lower.

To move the project from the design stage to the manufacturing process, a lot of development work is needed in order to reach the level of efficiencies required for the forecasted autonomy.

http://www.theaircar.com/Mines_reports.html

That was back in 2003. The lack of new info on the web site (I've seen it a few times over the past few years) makes me think they have significant problems developing the prototype - whether financial or technical, I don't know. There did at least have a meeting for interested investors in April 2005, so something's happened since the report. But I think the bottom line is that the compressed air is for urban use - the site itself says

Two technologies have been developed to meet different needs:

* Single energy compressed air engines
* Dual energy compressed air plus fuel engines

The single energy engines will be available in both Minicats and Citycats. These engines have been conceived for city use, where the maximum speed is 50 km/h and where MDI believes polluting will soon be prohibited. It is already possible see examples of this in some places, such as London, where you want to enter the city center with gasoline powered vehicles, you must pay a fee.

The duel energy engine, on the other hand, has been conceived as much for the city as the open road and will be available in all MDI vehicles. The engines will work exclusively with compressed air while it is running under 50 km/h in urban areas. But when the car is used outside urban areas at speeds over 50 km/h, the engines will switch to fuel mode. The engine will be able to use gasoline, gas oil, bio diesel, gas, liquidized gas, ecological fuel, alcohol, etc.

[ProfessorPlum]

63. Again, most things that go

become less efficient the faster they go.

Is your hypothesis that this kind of system would be drastically less efficient at higher speeds? Compared to, say, an internal combustion engine?

PS. Why so angry? Let go your hate, Luke.

[ProfessorPlum]

60. Or, here's another way to look at it

You can drive for about 2 hours at about the legal limit on one tank of air. About 60 mph for two hours.

Or you can go about 4 hours at 30 mph.

Doesn't make sense that the distance you go is relatively independent of speed? After all, a given amount of expanding air would drive the axles a certain distance, and except for loses to friction, you'd go about the same distance?

[annabanana]

45. I LOVE it!. . .The Fart Car!

(but without that embarrassing odor)

[ProfessorPlum]

52. Classy . . . .

.

[sweetheart]

46. KR ugly prototype

but cool idea, really cool indeed.

[silvershadow]

48. i posted a link to this a few weeks ago..according to their website

they are looking for investors. Large shares of the company for a reasonable price. I say we get together and start a group to invest and bring these cars to the US.

[MercutioATC]

65. No way this thing meets U.S. crash standards.

Even if it IS economically feasible in the rest of the world, it won't happen here.

[Orsino]

67. Do you realize that this car's emissions...

...contain over 350 ppm of carbon dioxide--a known greenhouse gas contributing to global warming?

[The Stranger]

69. That's not really true. It doesn't CREATE CO2, merely stores it, then

releases it and uses the pressure energy for locomotion.

It does not combust fossil fuels and thereby EMIT carbon dioxide.

[Orsino]

70. It IS true.

However, I intended it as a joke: the atmosphere already contains over 350 ppm of carbon dioxide, and therefore, so will the compressed air released.

[jmowreader]

74. Thinking out loud

//On edit: I better throw in here that the Compressed Gas Association---you didn't think there wouldn't be one--has set 2500psi as the "standard" for storage of compressed gases, except for acetylene which tends to spontaneously explode if you take it much over 250. There's probably a real good clear reason for this standard--strength of the storage cylinders, compressor efficiency, something. Just suffice it to say that if you go to a welding store right now and buy tanks of any four random gases, and none of them are acetylene, they'll all be at 2500psi.//

Forget the "cost of the electricity to compress the air."

Compressors that are big enough to refuel this car don't run on electricity; they're diesels.

Yes, it's Thinking Out Loud Time!

First, this isn't "new, untried technology." In fact, it is a very common technology--it's how they start large jet engines. Compressed air is fed into the engine, which spins it fast enough to catch when they inject and ignite fuel. The difference here is that once the jet engine is running on fuel they turn the air off, but this engine runs on fed air. (The other way to turn air power into mechanical power is by impact, but a car that sounds like a jackhammer would not be popular.)

So let me see...we need some kind of a device to hold air that needs to be light, strong and capacious. Something like...say, a scuba diver's fiberglass air cylinder. (And with a little door under the trunk lid, you could rig it so the air cylinder is removable. All of a sudden the Scuba Shop industry in this great land of ours is rubbing its collective hands together and drooling. They ALREADY sell air!)

We need a device to turn compressed air power into rotational power. Wheel motors? Check. You could put wheel studs on four 5hp wheel motors, bolt the tires to the wheel motors, and have plenty of power to push a little car all over town. Up them to 15hp wheel motors and you've got about as much horsepower as a classic VW Bug has...in a smaller, lighter design. That would be plenty quick to get around town in.

We need a device to regulate the amount of air each motor gets--also not a problem; we've had power-actuated ball valves in industrial settings for decades. They're required for automation. Stick a little computer between the gas pedal and the valve automators, and you can get really cute here--running the inner wheel slower on turns, that sort of thing.

Now for reality. Air systems leak. Period. You're certainly not going to hurt anyone with a little air leaking out of places...but you won't get the mileage you thought you were going to get. And if the commie bastard who routed all the lines on my car gets to route the air lines on an Air Car, you'll never find half of them when it comes time to replace them.

Air systems are also full of moisture. We've had high-pressure air on vehicles for decades because the brake systems on big trucks are all air-over-hydraulic. You deal with water in your air in two ways--an air-water separator in the system, and draining the tanks every night. You remember baclk when we discussed the International CXT pickup--the medium truck with a pickup bed? I said one of the things that would keep it out of the average Joe's garage was the prospect of maintaining the air brakes. Well...now we're not just talking air BRAKES, we're talking air EVERYTHING.

Some people will do all the things you need to do to maintain a large pneumatic system like an Air Car. Others won't. And considering the fact that I've lost countless sales because the thing they wanted needed to have four screws put into it and (1) they didn't have a screwdriver nor did they want to purchase one and (2) driving four screws into a pine board is too much work for them, I think the "won't do" crowd is far larger than the "will do."

[ProfessorPlum]

76. I would advise you not to buy one

if you ever live in a European urban center.

[jmowreader]

77. I have lived in a European urban center

Six years in Berlin counts as "living in a European urban center."

I didn't have a car at all. It wasn't necessary. Public transportation there is excellent.

If I did own a car, it would only be for things like serious shopping trips. This excludes the AirCar from consideration because it's got no cargo space to speak of. In Europe I'd definitely be looking at diesels, which run on B100 biodiesel just fine.

The AirCar would be excellent if you lived somewhere like Bernau or Wuensdorf, which are low-population towns (hence restricted public transport) that are kinda spread out. As long as it didn't leak air.

[BrightKnight]

75. biodesel from high-oil (50%+) algae is the only serious solution

This zero emissions wind-up toy is amusing but not a serious solution to the problem.

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http://www.unh.edu/p2/biodiesel/article_alge.html

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Hydrogen is another amusing zero emissions idea that won't work:

"So, highly pressurized to 250 atmospheres, hydrogen's volumetric energy density is only 7.2% of that of biodiesel. ...hydrogen vehicle would need a fuel tank roughly 14 times as large to yield the same driving range..."A large truck with a 175 gallon would require 2,360 gallons of hydrogen.

Using PV to generate hydrogen won't work because it would require enough energy to power 3 households per car.

Generating and compressing Hydrogen are inefficient.

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Many species of algae including Botryococcus braunii and CCMP647 have lipid (oil) contents of greater than 50%. They actually achieved 90% lipid content with Botryococcus braunii in a laboratory. There are suitable salt water and fresh water species. The algae doubles in volume every 2 to 7 days. One could produce 5k to 15k gallons of refined fuel per acre. Ethanol from corn by contrast only produces 320 gallons of fuel per acre.

All of the carbon to make the fuel comes from the atmosphere. It would be possible to increase the productivity by aerating the tanks with CO2 from power plants. The algae could be fed with effluence.

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[ThoughtCriminal]

78. I've seen compressed air locomotives

They have been around since the 19th century. They used to use them in mines and other areas where any kind of combustion was dangerous.

One problem - if you've ever lived near place that uses an air compressor you know - the noise is deafening. Are there any air compressors that are reasonably quiet.

[mom cat]

79. Great idea! There is enough hot air in DC to fuel the whole country!