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Transportation Earth Power

Berkeley Engineers Have Some Bad News About Air Cars 278

Posted by timothy
from the puff-the-magic-dragon-was-involved dept.
cheeks5965 writes "We've argued before over compressed air vehicles, a.k.a. air cars. Air cars are an enchanting idea, providing mobility with zero fuel consumption or environmental impacts. The NYTimes' Green Inc. blog reports that the reality is less rosy. New research from UC Berkeley and ICF International puts a period at the end of the discussion, showing that compressed air is a very poor fuel, storing less than 1% of the energy in gasoline; air cars won't get you far, with a range of just 29 miles in typical city driving; and despite appearing green the vehicles are worse for the environment, with twice the carbon footprint as gasoline vehicles, from producing the electricity used to compress the air. Given these barriers, manufacturer claims should definitely be taken with a grain of salt."
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Berkeley Engineers Have Some Bad News About Air Cars

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  • "zero fuel"? (Score:2, Insightful)

    by oldhack (1037484)
    How would you compress the air in the first place?
    • Re: (Score:3, Informative)

      by AmigaHeretic (991368)
      Solar panel on your garage.
      • Re: (Score:3, Insightful)

        by oldhack (1037484)
        Does it involve an electric middle stage? If so, electric energy storage would be more efficient, I'm guesssing?
        • by westlake (615356)

          Does it involve an electric middle stage?

          How can you compress air efficiently and economically without a mechanical compresor?

          • Heat it with a large pile of burning coal? You can add some water to the air to enhance the effect.

            Alternatively, you could acoustically excite the air in a resonant chamber, and pick off the high pressure gas at the peaks of the standing waves. Technically that's a mechanical method, but not of the typical piston or rotary type.
            • by Hadlock (143607)

              Can you point me to an example of an acoustic air compressor? I'd love to see the implementation of that idea.

              • Re: (Score:3, Informative)

                by Migraineman (632203)
                The basic physics experiment is called a Reuben's Tube. [wikipedia.org] Build one with only a single orifice at a high-pressure resonance point, install a check valve, and collect the pressurized gas in a tank. Here's another concept. [aip.org]
      • by ChipMonk (711367)
        And that's even less efficient than solar on the car itself. Remember, no energy conversion is 100% efficient. The fewer conversion stages the better.
    • One way to compress air for near free would be to have pneumatic braking
      at all off ramps on highways, and at all stop lights as they go red.

      Regenerative braking in hybrids work in a similar but electrical manner.

  • by jandrese (485) <kensama@vt.edu> on Saturday November 21, 2009 @02:34PM (#30186974) Homepage Journal
    There appear to be two primary advanages of these cars: They're cheap to make and they don't directly pollute the city air. If the power plant is downwind they could actually improve the air quality in the city. You also get "free" AC, although heating the car is an issue. Since these are primarily targeted at cities like Mumbai the cooling is more important anyway.
    • by wizardforce (1005805) on Saturday November 21, 2009 @02:38PM (#30187008) Journal

      What benefits do these air powered cars have that aren't significantly exceeded by electric vehicles?
      The range of these cars is 1/5 of electric cars *and* is less efficient.

      • by Sique (173459) on Saturday November 21, 2009 @02:46PM (#30187062) Homepage

        They were first developed to be used in environments, where sparks could lead to an explosion (e.g. chemical plants or refineries). There you can't use electric cars.

      • What benefits do these air powered cars have that aren't significantly exceeded by electric vehicles? The range of these cars is 1/5 of electric cars *and* is less efficient.

        You don't have to strip mine for Lithium. After a few years there are no dead batteries left over to throw away/try to recycle.

      • by jandrese (485)
        The very first advantage I listed: They're cheap to make. The biggest barrier to the adoption of electric vehicles has always been the cost of the batteries.
    • Re: (Score:3, Insightful)

      by Jeremy Erwin (2054)

      To power the air compressors, you'd need more power plants. Many more, since compressed air isn't efficient. Moreover, the compressors themselves would be dirty, so "free A/C" would be unhealthy.

    • by digitig (1056110)
      Yep, they can shift the pollution from somewhere rich people want to go to somewhere where only poor people are. Makes for a sound economic investment, at least.
  • Problem solved. Now you not only get energy from the potential energy of the compression, but also from the fuel itself.

  • by AmigaHeretic (991368) on Saturday November 21, 2009 @02:40PM (#30187018) Journal

    and despite appearing green the vehicles are worse for the environment

    Compressed air is just a medium in which to store energy. The energy could come from solar panels on your garage. It compresses the air. The air powers you car. Zero emitions.

    This is opposed to batteries which really aren't good for the environment, but all those Prius owners don't really seem to care about Lithum strip mines while patting themselves on their backs.

    Hydrogen is yet another method of storing energy.

    Just compressing air from solar, wind power, etc gives Zero emissions no matter if the efficiency is only 1% or 100%

    • by Gerafix (1028986) on Saturday November 21, 2009 @02:49PM (#30187100)
      Bullshit. There's no such thing as zero emissions unless you're knee deep in shit in the middle of the wilderness, burning wood for heat. Killing wild animals with your bare hands or tools you hobbled together yourself. Living in a hut made of shrubs down by the river.

      Those solar panels, wind turbines, penis pumps etc had to be manufactured somehow and that manufacturing process creates emissions. "Carbon offsets" is a joke, wake up people! Any emission is an emission.

      • by AmigaHeretic (991368) on Saturday November 21, 2009 @02:53PM (#30187136) Journal

        "Carbon offsets" is a joke, wake up people! Any emission is an emission.

        I hold all my farts in sir!

      • Any emission is an emission.

        Including those of the nocturnal and manual variety... slashdotters, I'm directing this at you. Your body is NOT an amusement park.

      • by gandhi_2 (1108023)

        >>penis pumps...

        It's okay. I bought a carbon credit!

    • by mrboyd (1211932)

      Just compressing air from solar, wind power, etc gives Zero emissions no matter if the efficiency is only 1% or 100%

      Well it does matter if we need to cover 3 football field with solar panel for every person who wants to commute in an air car. We're going to run out of space. Anyway, 2010 is around the corner and my flying car running on recycled garbage should theoretically be available shortly.

    • by commodore64_love (1445365) on Saturday November 21, 2009 @02:52PM (#30187116) Journal

      >>>all those Prius owners don't really seem to care about Lithum strip mines

      Prius cars don't use lithium. They use nickle and hydride, and when disposed are no more harmful than throwing-away coins and water. (Although recycling the metal would be better.)

      • by Rockoon (1252108)
        Nickel and water eh?

        Do realize that nickel is toxic to marine life?
        • Re: (Score:3, Interesting)

          by iroll (717924)

          Citation? I did a little googling, and it doesn't appear to be a hot topic by any standard. The biggest problems with nickel seem to be in its production, not its disposal, and I didn't see any references to nickel toxicity itself.

          Plus, we're talking about battery disposal here. The odds are much better that they'd be dumped in landfills than that they'd be dumped in rivers, lakes, and oceans. With landfills, you'd be more worried about aquifer pollution, and I didn't see much concern there, either.

      • by daemonc (145175)

        I'm guessing the parent actually knew that, since he mentioned strip mining, which is the most common way to produce nickel.

        Lithium, on the other hand, is extracted from saltwater.

      • by MeatBag PussRocket (1475317) on Saturday November 21, 2009 @05:58PM (#30188816)

        i'm curious as to how much thought you're really given to this, above and beyond the 'mythbusters' level. firstly, you're right, Priora are not built with lithium batteries, though you should wish that they were. Lithium is NOT stripmined, Lithium salts are extracted from the water of mineral springs, brine pools and brine deposits. The metal is produced electrolytically from a mixture of fused lithium and potassium chloride. Nickel on the other hand IS strip-mined and while their disposal may not be all that bad, the production of nickel batteries is extremely harmful to the environment. IIRC there is a mine in Canada used for the production of Prius batteries, if thats the one i'm thinking it is, there is a 60 mile dead zone around it which contains about as much life as the surface of the moon.

        there are of course problems with most forms of energy storage, the trick is finding ways to manage those problems.

        • Re: (Score:3, Informative)

          by SlashSim (229766)

          The nickel mine you are thinking about is probably Inco's mine in Sudbury Ontario. There is indeed a dead zone, but it is not a strip mine, the mine is underground. The dead zone is the result of acid fallout from the smelter. After killing off the area, and facing criticism, Inco built what was then the world's largest smokestack in the early seventies. The smelter still belches sulfur compounds, but now they are dispersed over a much larger area.

          Much of the area still looks like a moonscape.

          http://en.wiki [wikipedia.org]

    • Re: (Score:3, Insightful)

      <blockquote>Compressed air is just a medium in which to store energy. The energy could come from solar panels on your garage. It compresses the air. The air powers you car. Zero emitions.</blockquote>

      It said 'worse for the environment'. Using more energy is worse for the environment and will continue to be until ALL our energy comes from clean sources.

      <blockquote>This is opposed to batteries which really aren't good for the environment, but all those Prius owners don't really seem to care
    • by DarkOx (621550)

      Your are correct but its pretty tough though I think possible to get enough energy for transportation out of storage. In general, and this has been known for a long long time, so I am not sure why this is news compressed gas is a poor energy store. I am referring to compressed gas where the recovered energy will be from allowing it to expand not from a fuel gas like liquidated natural gas or something.

      Because solar is only so productive if its going to be the input energy for transportation than the stora

    • by russotto (537200)

      This is opposed to batteries which really aren't good for the environment, but all those Prius owners don't really seem to care about Lithum strip mines while patting themselves on their backs.

      That's because they know there's no lithium in the Prius batteries.

    • Re: (Score:3, Insightful)

      by Kymermosst (33885)

      Compressed air is just a medium in which to store energy. The energy could come from solar panels on your garage. It compresses the air. The air powers you car. Zero emitions.

      Okay, smart guy. Explain to us the zero-emissions process for manufacturing those solar panels, your air compressor, and your air car.

      We're waiting.

    • by Gordonjcp (186804)

      The energy could come from solar panels on your garage. It compresses the air.

      How big is your garage? A 1kW solar panel is about 2.5m by 1.5m, or about the size of two slightly taller than standard doors. My compressor draws 3kW from an ordinary wall socket, so by the time you add in the inefficiency of the inverter you're probably looking at four such panels - an area 5m by 3m - to comfortably run that. I suspect that my compressor, with its 200-litre receiver that it can get up to about 150psi before

  • by presidenteloco (659168) on Saturday November 21, 2009 @02:43PM (#30187044)

    The significant fact about electric (or hydrogen fuel cell), or electrically compressed air vehicles
    is that electricity (and hence hydrogen via electrolysis, or compressed air tanks) can be generated
    in all manner of relatively or completely "green" ways, whereas fossil-fuel transportation is
    at least presently restricted to getting its fuel by digging up stored carbon from the Earth at
    unsustainable rates.

    So electric vehicles (or hydrogen fuel cell, or even relatively inefficient compressed air) vehicles,
    are stepping stones on the path to a non-GHG producing future energy system.

    So the "green-ness" or carbon footprint of these electrically based technologies should be
    measured with two separate baselines:

    1. What would their carbon footprint be if all electricity was generated with carbon-neutral generation
    methods such as wind/solar/geothermal/hydro/wave/nuclear.

    2. What is the carbon footprint assuming the US continues to maintain arguably the most carbon-dirty
    electrical generating mix in the world.

    Measured in this light, it can be seen that the complete issue is changing the electrical power source for the
    US, in parallel with adopting one or multiple forms of transportation technology that is electrically based.
    Either change without the other does not work. Both are necessary for effective improvement in emissions
    reduction of transportation.

    • So the "green-ness" or carbon footprint of these electrically based technologies should be measured with two separate baselines:

      1. What would their carbon footprint be if all electricity was generated with carbon-neutral generation methods such as wind/solar/geothermal/hydro/wave/nuclear.

      No. That's a totally useless basis for comparison. If I can have 'free' energy (from a carbon-footprint POV), then I can propose any old idiotic idea and can label it 'green'. If I get to disregard efficiency, then I mi

      • by russotto (537200)

        No. That's a totally useless basis for comparison. If I can have 'free' energy (from a carbon-footprint POV), then I can propose any old idiotic idea and can label it 'green'.

        Exactly. For instance, I use the "free energy" to synthesize 2,2,4-trimethylpentane from CO2 and water, then burn the stuff in an ordinary gasoline car.

      • I didn't actually say that efficiency doesn't matter.
        Because obviously it impacts the amount of electrical generating capacity you have to build
        for a certain amount of transportation utility.

        My main point was that assessing the environmental impact of an electrically-based technology
        based on today's way of generating the electricity is misleading and shortsighted, especially when
        we already have much of the technology we need to shift the electrical generation method. We just
        need to make the morally necessar

  • by MoellerPlesset2 (1419023) on Saturday November 21, 2009 @02:43PM (#30187046)
    Not on debunking this, because it's a completely ridiculous idea that anyone who's taken even introductory engineering thermodynamics should be able to debunk. Rather, they should get credit for going the extra mile and actually getting a paper out of the thing (and media attention!).

    I mean really. There's perfectly good reasons why we're not using compressed air as a 'fuel', and it's not that we hadn't thought of it. The idea (and applications) have been around since the 19th century.
    • by bmajik (96670) <matt@mattevans.org> on Saturday November 21, 2009 @03:14PM (#30187304) Homepage Journal

      The problem of humanity is one of the capture, storage, and application of energy.

      Gasoline is a fantastic medium for energy storage: it's a better battery than any battery we know how to cheaply produce and service, and that's why we use it. But the energy capture function for gasoline [getting the energy into the gasoline] sucks. And the energy dispersal/application of gasoline has some environmentalists pretty upset.

      Nature gives us many ways to store energy now and release it later. The chemical combustion of gasoline is one such mechanism. The desire of a compressed gas to push forcefully against its container is another such mechanism. The strong nuclear bindig energy is a particulary potent and pervasive mechanism. The specific heat of water is yet another.

      The fundamental mechanisms of energy storage have been known about for a long time. Taken as a complete system to let humanity accomplish some goal, we are concerned with how we capture the energy, how much of it we can store [and at what cost], and how easy it is to get it back out in a form condusive to the sort of work we want to do with it.

      As technology changes we must continually re-evaluate the end-to-end story for a particular aqcuisition/storage/application energy cycle. We may find that we are willing to tolerate a 100 fold decrease in energy storage performance for a 200 fold increase in acquisition efficiency and a qualitative improvement in application performance.

      For instance, if i live in arizona and i have a sterling-engine powered air compressor that pumps my 50G tank to 100psi after 12 hours of sunlight, and this lets me go about 10 miles with no consumption of anything other than sunlight... I'm interested. If i commute 5 miles each way, I can get to work and back using nothing but solar energy. And unlike with PV panels and electrical batteries, a guy with a pipe threading die and a welder could build refueling system in his garage, out of stuff that has zero environmental impact whatsoever.

      I think that's cool. I'm obviously playing fast and loose with the numbers. Since the kJ/m^2 of solar radiation is known at gridsquares all over north america, you could actually make some ballpark efficiency guesses about peices of the process and plug in real numbers to my hypothetical example. Even if reality is 1 mile @ 30mph after 8 hrs of sunlight.. that fits _some_ usage profile.

      It used to be that every farm in North Dakota [where I live] had a windmill powering the farm. Then they disappeared and became an anachronism paying homage to a bygone era. Now windmills are dotting the countryside again. It didn't get windier here.

      What changed?

      The physics of energy capture, storage, and dispersion have always been the same; our efficiency and the context of the problem space continue to change. As such we must constantly re-evaluate what we did in the past against the realities of today.

  • Cold Steam Engine? (Score:3, Interesting)

    by Banichi (1255242) on Saturday November 21, 2009 @02:53PM (#30187126)

    It occurs to me that a compressed air vehicle could be compared to a "cold" steam engine.

    Have there been any scientific advances that could make steam engines in general viable for car sized engines?

  • I didn't realize that nuclear powerplants were a 'carbon' problem. Or windmills, or the liquid salt solar panels on my roof...

    However, i do agree that they are dreadfully inefficient. But they are cheap, reliable, and would shine in in-town commutes or grocery runs in the suburbs.

    • by dr2chase (653338)
      That is, these are the lamest excuse anyone has yet concocted for not riding a bicycle.
  • compressed air uses (Score:5, Informative)

    by stimpleton (732392) on Saturday November 21, 2009 @02:57PM (#30187174)
    I did an apprenticeship in Motor Mechanics for 4 years when I left school 25 years ago. I recall a question to the tutor back then about compressed air to drive a car. Here was his answer: Compressed air is not good as a primary driving medium, it is only good as a buffer(the storage tank) or where electricity might add risk. Examples being driving air tools in a pit below ground. By its nature, compressed air must pass thru constricted orifices. There is tremendous loss of pressure over distance. I recall our workshop compressor...very different from what you buy at a hardware store. Huge tank, dual motors, each on three phase power. The newbies job was to empty the water and oil traps from the Air Intake system. About 20 litres per day and about 200 mls of oil like fluid(The atmosphere in the workshop back then was a haze of car fumes and dust). We had 4 electric hoists and one compressed air hoist too. The air hoist could lift many times the wieght of the electric.

    I think compressed air cars will serve a specialist role, operating in specific roles. Whether there is commercial visbility, I do not know. Aside from the modern buzzword of "Footprint", the technology to compress air is as old as stem and pistons. That wont change. Even on high tech air craft carriers, the landing restraints have huge hoary old compressed air pistons dampenening the jets planes. The tech below deck, keeps the ram clean and applies some lubricant periodically....just as would happen in steam train days.
  • by heffrey (229704) on Saturday November 21, 2009 @03:05PM (#30187236)

    Slashdot - news for idiots, stuff that's obvious

  • No kidding? (Score:5, Insightful)

    by Brett Buck (811747) on Saturday November 21, 2009 @03:07PM (#30187250)

    This is a surprise to someone? Who ever though this *could* work? Certainly not anyone with any knowledge of thermodynamics. The only compressed -gas systems that even have a chance of working are those that store the working fluid as a liquid, meaning it has to be able to be liquified at room temperature at a reasonable pressure (few hundred PSI at most). Otherwise the tanks are huge and heavy (meaning it will barely move under power) or they are small and heavy (meaning it has no range). Two excellent working fluid for this purpose are - wait for it - CO2 and Freon! Oops.

              Brett

    • by hitmark (640295)

      if one really look into thermodynamics, one can just as well sit down and wait for the universe to die...

  • by jcr (53032) <jcr.mac@com> on Saturday November 21, 2009 @03:07PM (#30187254) Journal

    Compressing air can be done with any source of mechanical energy. Put a windmill on your roof, gear it down, and have it drive the compressor directly.

    Come to think of it, having a sizable amount of compressed air storage in one's house would be handy. Great for dusting.

    -jcr

    • Re: (Score:3, Insightful)

      by WaXHeLL (452463)

      Sounds like a tech geek's way of looking at it.

      Most people would say -- having a sizable amount of compressed air storage in one's house is great all around -- for your pneumatic power tools.

    • by Cyberllama (113628) on Saturday November 21, 2009 @03:53PM (#30187704)

      But you could just as easily have that windmill power a turbine to generate electricity to charge the battery in your electric car and get a far higher energy density leading to more mileage per charge and per each day's wind. I think that's the point that's being made. There's lots of clean ways that can generate energy -- any of which can be used to compress air, but why add that extra unnecessary step in the middle when it's just an added inefficiency?

    • Compressing air can be done with any source of mechanical energy. Put a windmill on your roof, gear it down, and have it drive the compressor directly

      Translate this into practical terms.

      Give me an estimate of the air car's speed, range, weight of cargo, weight of passengers.

      Tell me how long it will take to refill the tank.

  • 1. Install windmills at the recharge stations.

    2. Place compressors inside the turbine housing instead of electrical generators.

    3. Install large storage tanks at the recharge station.

    4. Let windmill run for a few days to build up a decent head and some reserve, then use electric compressors to compensate for low-production days.

    You can even price compressed air based on production? On calm days, it's more expensive, on windy days it's cheaper.

  • I remember early prototypes of this when I was a kid, called Air Jammers [virtualtoychest.com]. You'd pump them up, then give them a push and a one-cylinder engine would move them along. Of course being a budding Slashdotter, I removed the air motor and connected it to a can of Freon (when you could still buy it) and made it really run fast.
  • Ummm... duh? The marketing for these vehicles was never targeted at physics professors, was it? The people behind it targeted the market that they knew would be vulnerable to the pitch: people who don't "know science" and understand the constraints of the physical world.

    I had an unscientific (and religion-spewing) friend get all excited when he heard about these, and tried to infect me with his excitement. I firmly declined. I recognized what he was too delusional to see, that there was nothing at all s

    • Yes, but now there's a white paper from a recognized university (one which has a name associated with greeness) that you can point them to. Let them know that the Tata they have been reading about in Popular Science won't really get 1000 mile on a tank of air* like the marketing information would have them believe.

      *and 8-10 gallons of gasoline

  • by zogger (617870)

    These are designed to remove the *concentration* of exhaust gases from fuel burning from crowded urban areas. It isn't really that there are that much less overall emissions, just relocate where the emissions occur (although something can be said for having emissions controls at the generating plant). There's a lot of stop and go traffic, etc, most vehicles today sit at idle or run at some lower less efficient speed in city traffic. Air cars and electric cars shut completely off at "idle" and aren't wasting

  • What bothers me is that the "air car" guy got so much attention for so long. This thing has been in development since 1991, "close to production" since 2003, and the guy has been able to get enough money to build multiple good-looking prototypes. It's starting to look like a long-running scam like the Keely motor or the Moller flying car. The thermodynamics just don't make sense.

    In the only publicized test, the vehicle had a range of 7.22 km.

    Much is made of the connection between these guys and Tata,

    • Actually, they shouldn't team up - unless I get a cut of the funds raised. Those two seem to have pulled off one of the greatest money making schemes of all time. Together, they might approach Wall Street levels of shysterism.

  • unless you use solar or wind power for the electricity you will be using mostly coal burned electrical power. But nobody talks bad about hybrids. Actually my economy car costs less and uses less gas than a hybrid and is more friendly to the environment than a plug-in hybrid unless they are using renewable green electricity to power the plug-in hybrid.

    I think the car that ran on used french fry oil was the best idea yet, but once that catches on fast food places will charge a lot for used french fry oil.

  • The simple fact is, that electric cars are by far the only efficient means of moving. The ONLY real issue is the storage. Once that is licked (and great strides have been made over the last 15 years), then it is over for idea like the air car, gas cars, or even hydrogen.
  • The US produces 80% of its power from fossil fuels, and the cars are twice as bad as burning fossil fuel direct. BUT in more enlightened places 70% of the power is from renewables, so only 30% can be from fossil fuels max. So the production of compressed air is over twice as efficient, and these vehicles start to make sense. Said country (take New Zealand as an example) doesn't need to import massive quantities of expensive batteries to power the cars. Beware US-centric energy statistics; they only apply to

  • No kidding compressed air is crap for automobiles.When something manages to have worse volumetric energy density [xtronics.com] than lead acid batteries, plus nearly as bad gravimetric energy density even when you aren't factoring the weight of the container vessel, you know you have a loser there.

  • by athlon02 (201713)

    Actually admitting that a "green" energy source may not be as green as they thought. Wish more hybrid owners understood that... that battery must be disposed of eventually. As I understand it, hybrids aren't as green as people think. So much of the "green movement" is a total sham b/c it focuses narrowly on supposed benefits while ignoring reality & even data that contradicts the claims made.

  • by Cormophyte (1318065) on Saturday November 21, 2009 @04:21PM (#30187956)

    "...Air Cars" is an amazingly deceptive headline :(

  • Of course if you use electricity for compressing the air, you get a worse footprint.
    Even with solar batteries (which consume a lot of energy to produce).

    But put the engine in reverse and you have it pumping air, which can be achieved using a windmill. Without transforming it to electricity, just wind -> rotation -> pump -> pressure.

    Pure Steampunk.

  • Manufacturers claims? Is there even manufacturers??
  • > New research from UC Berkeley and ICF International puts a period at the end
    > of the discussion...

    New research my ass. A back-of-the-envelope calculation by anyone who passed first year physics suffices.

  • by kothmac (1609535) on Saturday November 21, 2009 @04:28PM (#30188024)
    I thought this was going to be a story crushing my hopes of owning a flying car.
  • by Lemming Mark (849014) on Sunday November 22, 2009 @12:39AM (#30191236) Homepage

    I own an air guitar and it's actually pretty sweet - I can make like I'm rocking out wherever I am. Whereas an air car ... I don't see the market. You're at a party and the music's pumping and you just decide to "air drive" to the shops? Not cool.

  • Blows... (Score:3, Insightful)

    by w0mprat (1317953) on Sunday November 22, 2009 @02:12AM (#30191664)
    .. the wind does, that is.

    Using a mechanical air pump driven by the wind makes massive sense to me, it is patently obvious. This method alone makes air power a win.

    How we generate energy now for air cars now makes no sense, is patently stupid. Fossil fuel -> heat energy -> mechanical energy -> electricity over a lossy inefficient grid -> pumping compressed air -> filling up your car.

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