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Transportation Earth Power

Berkeley Engineers Have Some Bad News About Air Cars 278

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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  • Re:"zero fuel"? (Score:3, Informative)

    by AmigaHeretic ( 991368 ) on Saturday November 21, 2009 @03:43PM (#30187034) Journal
    Solar panel on your garage.
  • by Sique ( 173459 ) on Saturday November 21, 2009 @03:46PM (#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.

  • by commodore64_love ( 1445365 ) on Saturday November 21, 2009 @03:52PM (#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.)

  • compressed air uses (Score:5, Informative)

    by stimpleton ( 732392 ) on Saturday November 21, 2009 @03:57PM (#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 DevonBorn ( 975502 ) on Saturday November 21, 2009 @04:13PM (#30187292)

    Yes you can use electric cars there. AC motors with solid state motor controllers and a hermatically sealed contactor shouldn't generate any sparks.

  • by Sique ( 173459 ) on Saturday November 21, 2009 @04:22PM (#30187376) Homepage

    To actually get an asynchronous motor in a car working and to control the speed you need some sophisticated electronics which weren't available when the gas pressure cars were initially developed.

  • by zogger ( 617870 ) on Saturday November 21, 2009 @04:50PM (#30187670) Homepage Journal

    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 fuel sitting there in some traffic jam or at the stop light doing nothing as regards moving from point A to B.

    That's the primary advantage here for short range urban vehicles as regards the environment. If you primarily do long trips, get a well tuned/ well built modern diesel for best mileage/less fuel burnt.

    Nice graphic on this page that shows where the fuel goes with a regular car, idling accounts for almost 1/5th energy wastage today, with extra pollution concentrated then for no real reason. []

  • by Anonymous Coward on Saturday November 21, 2009 @04:54PM (#30187720)

    Steam engines that run on stored steam were used for almost a hundred years. They were useful for relatively short ranges where burning coal would create a safety hazard. They had a tremendous advantage over smaller vehicles because their volume varied as the cube of their linear dimensions. Scaling them down to automobile size would, therefore, not produce a vehicle with much range.

    'Cold' steam engines weren't even that different from regular engines. The steam would stay as steam for a useful amount of time because of a favorable surface area to volume ratio. In fact, almost any regular engine could be operated 'cold'. They were useful where they were necessary but weren't used otherwise.

  • by westlake ( 615356 ) on Saturday November 21, 2009 @05:20PM (#30187950)

    They were first developed to be used in environments where sparks could lead to an explosion

    Compressed air engines were used in sealed, oxygen-deprived, environments: mines, tunnels, refrigerated storage plants and so on.

    They could be quite practical as switch engines.

    Larger and more powerful than you might expect. You'll find some pictures here:


  • Re:"zero fuel"? (Score:3, Informative)

    by bjourne ( 1034822 ) on Saturday November 21, 2009 @05:48PM (#30188188) Homepage Journal
    Wrong []
  • by tomhudson ( 43916 ) <barbara.hudson@b ... u d s o n . c om> on Saturday November 21, 2009 @06:06PM (#30188360) Journal

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

    more than a century ago [].

    A Stanley Steamer set the world record for the fastest mile in an automobile (28.2 seconds) in 1906. []Powered by a steam engine, and did 150 mph back in 1907.

  • by AK Marc ( 707885 ) on Saturday November 21, 2009 @07:48PM (#30189208)
    Uh, no. Hydrogen power is a net loss, due to the greater energy consumed in currently-available hydrogen production methods. Yes, that may change in the future, but for now, even a solar panel on the garage powering an air compressor incurs less energy loss.

    You , sir, are the definition of idiocracy. Where the uninformed feel the need to speak out incorrectly and grossly misinform others.

    Take a solar cell on your roof. Power a compressor hooked up to your air car. Take the same solar cell and the next day charge up an electric car. The third day, use it to crack H2O and capture the H2 and use that to power a car via an IC engine. Which goes farthest? Which goes the shortest distance?

    The laws of thermodynamics require that all things be a net loss. By definition. You need to look at what loss there is.
  • by Waterppk ( 1009237 ) on Saturday November 21, 2009 @08:58PM (#30189708)
    This isn't as simple as you're thinking. Nickel Metal Hydride batteries are manufactured as a paste and rolled or turned into prismatic cells. It's difficult to recover the elements put into the pack.

    Replying directly to your request for a citation, the EPA has a nice page here describing all of the wonderful sickness you can enjoy when you have nickel in your water: []

    Sounds like a great waste of energy to recover the batteries anyways;

    "The recycling process starts by removing the combustible material, such as plastics and insulation, with a gas fired thermal oxidizer. Gases from the thermal oxidizer are sent to the plant's scrubber where they are neutralized to remove pollutants. The process leaves the clean, naked cells, which contain valuable metal content.

    The cells are then chopped into small pieces, which are heated until the metal liquefies. Non-metallic substances are burned off; leaving a black slag on top that is removed with a slag arm. The different alloys settle according to their weights and are skimmed off like cream from raw milk.

    Cadmium is relatively light and vaporizes at high temperatures. In a process that appears like a pan boiling over, a fan blows the cadmium vapor into a large tube, which is cooled with water mist. This causes the vapors to condense and produces cadmium that is 99.95 percent pure.

    Some recyclers do not separate the metals on site but pour the liquid metals directly into what the industry refers to as 'pigs' (65 pounds) or 'hogs' (2000 pounds). The pigs and hogs are then shipped to metal recovery plants. Here, the material is used to produce nickel, chromium and iron re-melt alloy for the manufacturing of stainless steel and other high-end products.

    Current battery recycling methods requires a high amount of energy. It takes six to ten times the amount of energy to reclaim metals from recycled batteries than it would through other means. " []
  • Re:Full of Shit (Score:3, Informative)

    by Alef ( 605149 ) on Sunday November 22, 2009 @08:53AM (#30192636)

    Considering about 15 cents/KWh energy, that's 1.5 cent/hour you save. [...] Now consider some 4 cents/KWh of energy a massive bulk customer like the solar panel factory pays

    I just checked these numbers. They are quite accurate, but interestingly, the difference is made up of almost entirely of taxes. The power company adds less than 10% to the spot price, so bulk seems to have little to do with it.

    In my case the price is 9.33 euro cents per kWh. This is made up of:
    Spot price: 3.81 cents (41%)
    Added by the power company: 0.35 cents (3.7%)
    Taxes and certificates: 5.17 cents (55%)

    When buying in bulk, the interesting figure is the spot price. Where I live, electricity is traded on a public exchange (Nordpool []), so you can easily check the price per MWh at any time.

  • by SlashSim ( 229766 ) on Sunday November 22, 2009 @04:16PM (#30195910)

    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. []

  • Re:Full of Shit (Score:3, Informative)

    by SharpFang ( 651121 ) on Sunday November 22, 2009 @06:37PM (#30197050) Homepage Journal

    I used a table very similar to this one (but yearly instead of monthly) []
    15 US cents seemed to be about the average residential price, 4 cents was the low of the industrial - and considering the massive bulk purchase, the lowest pick seems fair here.
    The $1000 was the first google hit for 100W solar panel.

  • Re:"zero fuel"? (Score:3, Informative)

    by Migraineman ( 632203 ) on Monday November 23, 2009 @11:35AM (#30202458)
    The basic physics experiment is called a Reuben's Tube. [] 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. []

Disks travel in packs.