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Aug 27 2012

Green car really sucks

An Indian car manufacturer hopes to sell a new air-powered car that runs cheap and has zero emissions.

The Airpod’s technology was originally created in France at Motor Development International but has since been bought buy Tata in hopes to bring it to the Indian consumer car market. With virtually zero emissions and at the cost of about a penny per kilometer, it is definitely one of the most environmentally and economically friendly vehicles in the world.

And how do you refuel it?

The tank holds about 175 liters of compressed air that can be filled at special stations or by activating the on-board electric motor to suck air in from the outside.

Yeah, the refueling method sucks (*groan*), but at a market price of only $10,000, it could sure put a crimp in the sale of all those pricey hybrids. You still need a source of electricity from somewhere, so it’s not, perhaps, totally green, but still, it’s a cool idea.

30 comments

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  1. 1
    Lofty

    Efficiency isn’t its strong suit. Even a trace of moisture in the compressed air can ice up the motor. At least air conditioning would be cheap, just run the exhaust pipe into the cab!
    The wikipedia article on compressed air cars gives a good summary of where they are at.

    1. 1.1
      Usernames are smart

      Not so sure. That air might contain oil and othe contaminants.

      My air compressor has a warning sticker admonishing the operator to not breathe the outgassed air when decompressing the tank.

  2. 2
    John Morales

    Well, I guess it’s easier to steal electricity than to steal liquid fuels. ;)

    (I note they will maybe sell once they are actually available for sale)

    As for virtually zero emissions, that ignores the emission costs of generating electricity. Indian power plants are not the cleanest in the world.

    1. 2.1
      left0ver1under

      Indian power plants may not be the ideal, but in countries with abundant hydroelectic and nuclear power, it’s a good option. The estimated amount of electricity needed to recharge the cars is low compared to gas, even if it requires a significant amount of electricity to do it.

      The car is a much better option in a congested city because it won’t add to the pollution. It’s also a three wheeled vehicle, which means it’s rated the same as a motorcycle, not a car, so a car license isn’t required. People may not want to drive it because it’s “uncool”, but as an in-city taxi, it would be a winner.

      1. steve oberski

        Actually the car is literally quite cool due to the adiabatic cooling effect of a decompressing gas.

  3. 3
    Zugswang

    I remember first hearing about this maybe 5 or 6 years ago, and thought it was such a cool idea. I imagined a future development that would allow me to pressurize the car with a bike pump in emergencies, and driving around in a car that sounded like a slowly deflating tire was strangely intriguing to me.

  4. 4
    DaveL

    They don’t say how highly pressurized the reservoir is, but if we assume something reasonable like 1 MPa, that’s a maximum of 0.175m^3 * 10^9 Pa = 1.75e8 J, which at 100% conversion efficiency would work out to about 65 hp for 1 hour – which doesn’t strike me as a whole lot.

    1. 4.1
      DaveL

      Found a reference that claims the reservoir is pressurized to 248 bar – 24.8 MPa.

      1. Coragyps

        Around 3500 psi, for those of us that grew up here on the wrong side of the tracks. “Refueling” that scares the livin’ crap out of me…..

      2. steve oberski

        Well if you are a scuba diver you would routinely strap that to your back and jump over the side of a boat.

      3. chris

        With the best will in the world, a scuba diver doesn’t have to deal with India’s notoriously free-form approach to driving (and jury-rigging). Interesting concept but one to evaluate from a safe distance…

  5. 5
    blf

    This is the French Airpod car, which The Grauniad reported on back in 2008 (including the deal with Tata), On the road with the Airpod air-powered car:

    … French auto engineer Guy Negre … claims to have developed a car powered by compressed air: one that produces a fraction of the carbon emissions of a standard engine, reaches speeds of 30mph-plus, that can travel 65 miles on a one-minute recharge and, best of all, costs from just over £3,000.

    … While Negre’s air cars have similar carbon emissions to electric cars (it all depends how the electricity to power the pumps that fill their air tanks is generated), he argues that air-power is a superior technology. “Compared to electric cars, air-powered cars cost a fraction of the price to buy, they don’t need expensive batteries to be replaced every five years or so and crucially they take only a fraction of the time to recharge.”

    Negre previously designed racing engines for Renault and has devoted the last 13 years to developing compressed air technology at his factory in Carros, outside Nice, in southern France. …

    The cars are made of fibreglass, which is lighter and 10 times stronger than steel, claims Negre. The compressed air is stored at high pressure in shatter-proof thermoplastic tanks surrounded by a carbon-fibre shell. (The same tanks used to contain the fuel in gas-powered buses.) The air is released through pistons in the engine, which drive the wheels. Unlike conventional internal combustion engines, air-powered engines run very cold and thick ice quickly forms on the engine. This means that the only feature that comes for free in the air car will be air-conditioning.

    Each car has an onboard pump that can refill the tank overnight. But Negre has also developed a high-pressure air pump — imagine a heavy-duty version of the tyre pumps found on a garage forecourt — that can fill the tanks in less than a minute. These could be powered by clean electricity — hydro, wind or solar — making the air car completely pollution-free. Even if carbon-generated electricity is used, CO2 emissions are still only 10% of a petrol engine’s, claims Negre.

    But perhaps the most credible endorsement of air power comes from a £30m deal the makers recently signed with Indian car giant Tata to license the technology in Asia for use in the ultra-cheap Nano. Negre has also signed deals to manufacture the car in the US, Latin America, and several European countries…

    Although I live in that general area of France, I’ve never seen one.

  6. 6
    Marcus Ranum

    Putting a little fart-flapper on the exhaust pipe would be wrong, wouldn’t it?

    1. 6.1
      lorn

      And … Marcus Ranum wins the thread. LOL.
      If it’s wrong I don’t want to be right.

      The lack of sound from electric and air powered vehicles represents a significant risk to pedestrians and bikers. Some sort of noisemaker would be useful.

      A duck call rigged to sound when you goose the engine (sorry) would also be an option.

      A calliope, or brass fanfare, would lower mileage but give you distinctive theme music for your arrival.

  7. 7
    machintelligence

    Compressed air is not a particularly efficient storage medium. My shop air compressor takes about 4 minutes to get a 100 liter tank to 8 bar. The motor draws about 14 amps at 120 volts when it is at the end of its cycle. You are looking at long charge times and lots of electricity. Also, the tank had better be spun fiberglass or kevlar, because I would hate to see the results of a metal tank failure.

    1. 7.1
      Artor

      Yeah- a high pressure tank is frightening in it’s failure. My sister saw a scuba tank tip over and knock it’s regulator off. It took off like a rocket, shot through a cement block wall, and landed in a field 200 yards away.

    2. 7.2
      left0ver1under

      The tanks are made of carbon fibre which will crack, not shatter, if there were a catastrophic failure.

      There is also a “plate” separating the tanks from the passenger compartment, preventing any burst of compressed air from injuring occupants.

  8. 8
    Nemo

    I saw a treatment of this on the Discovery Channel (IIRC) that was really sad; they essentially made it out to be a perpetual motion machine. In reality, it’s not obviously superior to a conventional battery-driven electric car.

    1. 8.1
      kagekiri

      Well, it might reduce the need for massive, toxic, deteriorating batteries, which are the current problem with electric cars in my mind. Of course, it still seems to have batteries for its electric motor….so yeah.

      Pedal/running car time? At least it’d reduce our obesity problem.

      1. Usernames are smart

        Er, not really. My hybrids batteries developed a fault and had to be replaced. They were recycled by the dealer.

    2. 8.2
      jaranath

      Last time I dug into a chain email about a Tata compressed-air car project, that’s pretty much what it was: A mix of urban legend, concept car tinkering and third-party scamming. I don’t remember what I found on energy densities at the time but IIRC (maybe wrong!), compressed air or other gas is not a viable energy source for nearly any car, even highly specialized designs like this one. If I can find any of the sources I used back then I’ll post ‘em.

      1. Dalillama, Schmott Guy

        Pretty much this. The endurance of these things compares unfavorably with that of a human-powered jetpack. These guys have been swearing that it’ll work at least since they were supposed to go on sale back in 2007, when I first heard of them. About once a year, some news outlet will find it and make a bit of a fuss, but there’s nothing there.

  9. 9
    Tx Skeptic

    Some other factors to consider –

    - weight of the ‘fuel’ (air)
    175 L @ 3500 psi should be ~ 119 lbs, the equivalent of about 19.5 gal of gas

    - Volume of ‘fuel’
    175 liters is about 46 gal, quite large for such a tiny car

    -weight of tank
    unknown, but must be pretty damn strong to hold that pressure & volume, so even if some kind of fiberglass & kevlar, it would still be significant

    -weight of ‘engine’
    A big plus here as it should be pretty darn simple & light compared to a gas engine, and air control might be able to eliminate a transmission.

    That much air would scare the crap out of me if a tank failed, I’d sure want some quality safety testing on the tanks.

  10. 10
    bcoppola

    Tata will rue the day they turned down my rubberband-propelled car.

  11. 11
    Zeke Hoskin

    Are there no physicists? In the first place, much of the work compressing gas is wasted in heating it, and none of that waste heat is recoverable unless the compressing station is equipped with quite a lot of extra equipment, in which case maybe half of it can be captured. Then when the gas expands, it cools, reducing efficiency hugely and requiring some heat source. In the second place, air above a couple of MPa at room temperature doesn’t behave anything like an ideal gas, and the idea of getting extra energy storage by compressing it further is like the idea of storing energy by compressing water.
    Compressed-air tools work fine because a relatively large reservoir of air at a relatively low pressure is allowed to heat and cool through a relatively small range. The compressed-air car is a scam that should not take in anybody who has been exposed to elementary thermodynamics and can be bothered to do a little math.

  12. 12
    katkinkate

    It’s greenness depends on the source of the electricity.

    1. 12.1
      Midnight Rambler

      Not only that, but the efficiency of the conversion. I have a hard time believing that compressing air is an efficient way of storing energy.

      1. TheGrumpyAntitheist

        Yeah, well, the thing that makes it attractive is more the usability of it. Fossil fuels, biodiesel, ethanol, etc are all inefficient in regards to energy out vs. energy put in for production. Fossil fuels, of course, have the advantage that the majority of the energy investment happened inside the Earth for millions of years.

        The thing is that batteries are definitely a more efficient storage and delivery mechanism, they’re expensive to produce, the capacity is eminently poor in comparison to what is actually desirable, and the charge times are so long as to make it completely unusable. Sure, there’s the concept of hot-swappable battery packs, but you can’t really scale that up very well to higher volume. An air compressor, at least, can fill you up in relatively short order, and it’s a technology that is widely available and well understood. It’s not the end-all solution (I’d hope no one is selling it like that), but it’s a pragmatic stopgap at least.

        This is also why I think fuel cells (should that technology advance far enough) will still be preferable in the mid-to-long term over any battery technology that will exist within my lifetime. This compressed air bit is much the same kind of stopgap as hybrids, IMO, except that it’s more accessible to people who don’t have the money to afford a gas-electric, plug-in extended range, or dare I say, a diesel-electric hybrid (the last of which will probably never exist simply because of the cost)

    2. 12.2
      Usernames are smart

      That’s what solar panels, hydro, and wind turbines are for!

  13. 13
    Eidolon

    From the world of scuba diving…

    The standard aluminum 80 cubic foot tank at 3000 psi (206 bar) holds about 2260 litres of compressed air. That air weighs about 5 lbs (2.5 kg). These tanks are safe if maintained and inspected properly so that part of the air powered car is kind of a non-issue.

    The compressor required to produce this high pressure air is neither simple nor inexpensive. Further, there needs to be a substantial reservoir to allow a fill in a reasonable amount of time. You are not going to fill this off your Craftsman compressor. Then there is the real problem of energy density. Cars burn gasoline for a lot of reasons, chief of which is the high energy density. Dilute the gasoline with alcohol and you get a less effective fuel. Compressed air might seem kind of impressive, but there is really not a lot of energy to be had compared to almost any IC engine.This might work, but doesn’t seem very workable.

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