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Earth Power

Cheaper Energy From Caverns of Compressed Air 114

Posted by samzenpus
from the fine-until-the-earth-burps dept.
An anonymous reader writes "By using the Earth's vast underground caverns to store compressed air generated by wind farms at night, several U.S. municipalities will be 'going green' by using that stored energy to generate daytime electricity on the cheap. Engineers at a National Lab think compressed air stored in underground caverns could cut in half the cost of electricity."
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Cheaper Energy From Caverns of Compressed Air

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  • vast? (Score:5, Funny)

    by Ydna (32354) * <andrew@NosPam.sweger.net> on Wednesday July 02, 2008 @11:22PM (#24039453) Homepage
    Earth's vast underground caverns? Oh please. If scientists actually tried doing this, it would surely bring about the end of life as we know it. The atmosphere would all be sucked up into these vast caverns leaving nothing but a vast vacuum on the surface. No, thank you!
    • I think those guys are full of vast hot air.

    • Re: (Score:1, Funny)

      by Anonymous Coward

      That's my colon you insensitive clod...

    • Re:vast? (Score:5, Funny)

      by w0mprat (1317953) on Thursday July 03, 2008 @12:41AM (#24039843)
      Your right, such a project would produce unacceptable levels of vacuum emissions into earths atmosphere. But this could be a good thing!: Production of Vacuum tubes and Cathode Ray Tubes in the 20th century used up all the easily available vacuum on earth (mined from the air which contained precious little vacuum! - bringing it down from space is not cost-effective!) humanity had to make do with the transistor and now we have to change to LCD screens since CRTs are no longer profitable to manufacture. But this could change things!
      • by nog_lorp (896553)
        You are very wrong on one important point. Vacuum is abundant in the earth's air, the issue is extracting it!
      • Re:vast? (Score:5, Funny)

        by PHPfanboy (841183) on Thursday July 03, 2008 @03:27AM (#24040497)

        And this is why I have applied for a job at NASA. Think of all the vacuum we could mine from space!!! (Space is also very big but we'll make sure we get mines near to earth, to reduce our transport costs and make it cost effective)

        We'll make a fortune selling vacuum to store in caves and then once we've sold to local authorities and energy companies we can sell to homeowners "A Vacuum for Every Yard" and then as the market becomes educated we can crack the enterprise and SMB market with "A Vacuum on every Desktop".

        P.S.
        I first got the inspiration for this awesome business opportunity idea from the documentary movie "Spaceballs".

        • by sumdumass (711423)

          Hmmm.. Instead of working on a space elevator, maybe we could build a vacuum pipeline so the rocket fuel doesn't contaminate the vacuum. We would have to be careful with them though, they would basically be long tubes and if we had a series of them, then teenage geeks will be wanting to surf pron with them.

        • Re: (Score:3, Funny)

          by TropicalCoder (898500)
          If we could find a way to compress the vacuum to a tiny fraction of its normal size, we could put it in little containers to power a vacuum cleaner. Imagine then - a "green" vacuum cleaner that runs on cans of this compressed vacuum instead of electricity! Instead of plugging in your vacuum cleaner, you just stick in a new can of highly compressed vacuum before you begin to clean the house.
        • by unitron (5733)

          Think of all the vacuum we could mine from space!!!

          But it's almost impossible to bring it back down to Earth because vacuum is massless and therefore weightless. It's like trying to force an inflated beach ball or an inverted empty bottle down to the bottom of a swimming pool.

      • by KlaymenDK (713149) on Thursday July 03, 2008 @04:09AM (#24040605) Journal

        Production ... used up all the easily available vacuum on earth (mined from the air which contained precious little vacuum! - bringing it down from space is not cost-effective!)

        Oh, come off it. There are still plenty of untapped vacuum sources around.

        There's about of cubic foot of the stuff in any PHB cranium, you just need to open the thing and tap it! Granted, you'd need quite a bit of source PHB, but that's easy enough to come by -- and it's renewable.

        • Re: (Score:3, Funny)

          by doug (926)

          You're right that the transportation costs are low, but the mining costs are prohibitive. Those PHB skulls are so dense, so they chew up the drill bits like there's no tomorrow.

          I believe that they are more effective as the power source for air turbines. Harnessing all that hot air that they produce to spin a turbine should generate countless megawatts. And it might justify some of the meetings that I've had to go to.

          - doug

      • by Chemisor (97276)

        > bringing it down from space is not cost-effective!)

        Why isn't it? Vacuum compresses very well. You can pack a full year's supply of it into a single thermos bottle.

      • When you look back at it, it is hard to believe that the people in the 1900s were so short sighted and selfish; leaving their children and grandchildren with a vacuum deficiency. Luckily out generation if far more thoughtful and won't mess up the planet for our kids!
    • Well, then we'll just steal Druidia's atmosphere....
    • Revenge of the mighty jurrassic mice in the year of the rat [wikipedia.org]?

    • by thewiz (24994)

      I can't decide whether this idea sucks or blows...

  • by TheStonepedo (885845) on Wednesday July 02, 2008 @11:34PM (#24039503) Homepage Journal

    How far are the turbines from the caves? What happens if the wind that should be generating electricity for the compressors takes the day off and chooses to make an unfashionably late arrival? How much of a boost do the turbines get from the compressed air?
    I'd think with enough losses along the way (steps up/down in voltage at transformers to transmit the power to the compressors, mechanical inefficiencies of the compressors, dependence of the turbines' optimum performance on this assistance) the project, while novel, could take a while to pay for itself. I'm not suggesting that bleeding-edge science should be economically feasible - that should come after the science is established - but that efficiency should be priority number one so that the technology can become competitive with other ways to store potential energy.

    • Re: (Score:3, Informative)

      by tirerim (1108567)
      I think they're mainly suggesting that it would be more efficient than storing the same energy in ordinary chemical batteries, which is the current method for storing energy from natural sources for times of higher demand (or lower production, in the case of solar). Presumably their calculations are based on minimizing the inefficiencies for both batteries and compressed air.
      • by Rakishi (759894) on Wednesday July 02, 2008 @11:57PM (#24039609)

        The current method as I understand it for large scale energy storage is water. Specifically http://en.wikipedia.org/wiki/Pumped_storage [wikipedia.org]

        Compressed air probably less efficient but potentially cheaper to implement.

        • Re: (Score:2, Funny)

          by Anomalyst (742352)
          We don't cache energy in your toilet, please don't pee in our pumped storage.
        • by Rei (128717)

          Compressed air is extremely inefficient -- compressors generally only get 10-20% efficiency. Now, since these compressors would need to be monstrous in scale, they've probably got a bunch of stages and are doing everything possible to recover waste heat, so they'll probably do much better than that, but nonetheless, there's going to be a huge degree of loss here. This isn't a problem for incompressible fluids such as water.

          Batteries (as another poster mentioned) are extremely efficient. Li-ion, for examp

          • ...This isn't a problem for incompressible fluids such as water....

            Water does indeed compress... perhaps not easily, but it does. Search Google... I'm too bored to do so.

            Or ignore that statement... for all intensive purposes (due to the difficulty in compressing water), your point is otherwise valid (and I am just being nitpicky). ;-)

            Batteries (as another poster mentioned) are extremely efficient. Li-ion, for example, ranges from 95%-99.9% depending on the variety and the rate of charge. The problem is not the efficiency of batteries but their cost. One hope is that flow batteries [wikipedia.org] may improve the situation.

            Li-ion have great theoretical efficiencies... but that is all. They dont heat up so much during charging or discharging because of efficiency. And of course, needing to replace them after so many cycles isnt efficient either (and is very cost

            • by Rei (128717)

              Water does indeed compress... perhaps not easily, but it does. Search Google... I'm too bored to do so.

              Water is known as an incompressible fluid. Technically, it does compress a little, but by a small enough amount as to be negligible in most applications.

              And of course, needing to replace them after so many cycles isnt efficient either (and is very costly for situations such as this that would require a lot of battery).

              Almost no multiuse battery variety uses anywhere near as much energy to make as it store

      • by Simon Brooke (45012) <stillyet@googlemail.com> on Thursday July 03, 2008 @04:49AM (#24040739) Homepage Journal

        I think they're mainly suggesting that it would be more efficient than storing the same energy in ordinary chemical batteries, which is the current method for storing energy from natural sources for times of higher demand (or lower production, in the case of solar). Presumably their calculations are based on minimizing the inefficiencies for both batteries and compressed air.

        Pumped storage systems - essentially hydroelectric systems with a top reservoir, a bottom reservoir, and a system of pumps to move water back up to the top reservoir at times of excess generating capacity - are used in the UK at Dinorwig [fhc.co.uk] and at Ffestiniog [fhc.co.uk], and in the US at Luddington, Michigan [consumersenergy.com] (and probably in other places I don't know about). This is a reasonably simple, reasonably efficient system of storing energy at time of surplus production and releasing it at times of peak demand.

        • by jandrese (485)
          As a bonus, you occasionally get "free" energy out of your storage system when it rains.
    • Re: (Score:3, Informative)

      What happens if the wind that should be generating electricity for the compressors takes the day off and chooses to make an unfashionably late arrival?

      You draw power from the grid, which you'll still be connected to.

    • by WalksOnDirt (704461) on Thursday July 03, 2008 @12:15AM (#24039683)

      How Efficient is It?

      If you just throw away the heat generated during the compression, which I think is what is done in current large installations, I have read that you can get about 50% efficiency. The fact that natural gas is used in conjunction with the compressed air to regenerate the stored power confuses the issue, which leads to much higher efficiencies sometimes being claimed.

      Here they are proposing to capture the compression heat and use it (with an "adiabatic generator"), which should help the efficiency. I'm a bit surprised the energy savings are worth enough to cover the capital costs of tapping such a low grade heat source, especially since this is also excess energy that will also need to be stored for later.

      • Surely a heat-exchanger and thermal storage could be used to make it more efficient: Heat generated in compressing the air could later be used to heat the air (increasing the pressure) just before releasing it into the turbine. "Cold" generated as the air expands in the turbine could be used later to cool air before compression to make it more dense.
        • by Fzz (153115)
          Or just build Google's datacenter next door, and use the cheap cool air to chill it.
      • by Thelasko (1196535)

        Here they are proposing to capture the compression heat and use it (with an "adiabatic generator"), which should help the efficiency. I'm a bit surprised the energy savings are worth enough to cover the capital costs of tapping such a low grade heat source, especially since this is also excess energy that will also need to be stored for later.

        As I understand it, they plan to store the heat energy separately, and as heat. I suppose it would be like a big thermos. When they release the compressed air they heat it with this stored heat before it goes to the engine.

        Heating very dense air is more effective at increasing pressure than heating less dense air. The fact that the air is very dense allows them to take advantage of this "low grade heat." It's all ideal gas law stuff. [wikipedia.org] It's also why turbochargers are more effective when they have inte [wikipedia.org]

      • You could take the heat out of the air while compressing it into the caves, then when you let the air out you would make power and get Air Conditioning too.
    • Re: (Score:3, Interesting)

      by kesuki (321456)

      you have a lot of questions but here is the point.

      at night time the wind dies down to the point where wind turbines generate 0 power. the whole point is that they can compress air in existing underground caves, near municipal wind farms, to run them after dark.

      I'm worried about long term side effects, 1200 PSI is a lot of potential energy, and cave systems, even an airtight system as this must be, are underground and usually there are things above it, in this case, prime iowa farmland. if the cave blows a

      • by skiingyac (262641)

        1200 PSI is a lot of potential energy.

        Assuming the cavern has 1000 feet of granite (a medium density rock) above it, the amount of force exerted downward by the rock is also about 1200 PSI. 1000 feet is maybe a little high for natural formations, but an old mine could certainly work well. There are plenty of those, probably not many in Iowa though.

    • by dbIII (701233) on Thursday July 03, 2008 @12:28AM (#24039755)

      How Efficient is It?

      Not very. The point however is to even out the load and fill the peaks, it's just another form of pump storage I suppose for places where you can't just conveniently pump water uphill. Despite the nuke lobby cry that it is all about base load the real problems are the peaks. With base load generation you have a whole lot of power being generated at night that isn't being used by anything and what is being used is lighting which mucks up the power factor. Running great big motors (like pumps) at night or resistance heating is what is usually done.

      To sum up - a lot of energy is wasted but you get to fill the peaks without needing base load generation capacity equal to peak load requirements.

      Sometimes wasting the energy is not a big deal. The ideal centuries old application for a windmill is to move enough water into a tank over the course of a week or two for use over the next week or two. With a long enough timeframe in the design it really doesn't matter if you have a few windless days or for solar a sudden cold snap. Compressed air however is a very inefficient way to store energy.

      • by gormanw (1321203)
        why not conserve energy through green roofs, better windows, hybrids and the like? i think we spend so much time looking for "novel" solutions when real and cost effective solutions are at our finger tips. I read a lot about green roofs. The best place I found was http://www.cleanerairforcities.blogspot.com/ [blogspot.com] I also read a great series of articles about hybrids and solar, as well as costs and benefits at http://www.economicefficiency.blogspot.com/ [blogspot.com] Conserve first, innovate in parallel!
    • by jo42 (227475)

      This needs a "whatcouldpossiblygowrong" tag:

      1) How are all the leaks going to get plugged? Cost effectively?

      2) How are the caverns going to get pressure tested? What if they blow?

      3) What idiot thought this dumb idea up?

      • Re: (Score:1, Funny)

        /me runs off to patent 'Cavern Glue!'

        Cavern Glue...! Do you have a leaky Cavern?
        Try Cavern Glue!
        It fills gaps! Cavern Glue!
        It seals openings! Cavern Glue!
        Cavern Glue! will make your Cavern impermeable or your money back!*

        *Cavern Glue! guarantee does not apply to Helium and
        other certain Noble Gasses. Please see website for list
        of gasses excluded. Core samples must be submitted
        with claims.

        [Rule of seven =) ]

      • by trout007 (975317)
        The way to safely pressure test something is to use a liquid. That way there is little potential energy and when it starts to leak the pressure safely drops. So you just need to fill the whole cave with water first to test it. Or why not just get a big ass plastic bag and sink it to the bottom of the gulf of mexico in a couple of thousand of feet of water. Then you can fill the bag with air and with the outisde water pressure the force on the bag would be very little. You just have to anchor it so it doesn
    • by burni (930725)
      [compress air]
      you have to transfer the heat produced, either you will get a drop in compressorefficiency

      [decompress air]

      when you release preassurized gas through an air regulator, the gas temperature will
      drop down, this is how refrigerators work.
      This air has to be reheated before it is lead into turbines, its done by burning (fossil) fuel.
      Either you would drop the efficiency to a degree where this is not feasible

      The temperature would be so low that you have high equipment costs for the turbines,
      or simply da
      • [decompress air] when you release preassurized gas through an air regulator, the gas temperature will drop down, this is how refrigerators work. [...] The temperature would be so low that you have high equipment costs for the turbines, or simply damaged turbines.

        Surely there's a simple way to put this cooling to work: given that the cooling happens during daytime hours, you could build a series of Ben & Jerry's factories alongside these air storage facilities. And at night you could cook breakfast for all B&J's workers using the heat generated while filling the caverns.

        HAL.

        • Nononono! Even better idea! Cook TV dinners at night, freeze then during the day. This would be soooooooooooo efficient -- all that energy that would have otherwise have been used by cookers and freezers gives way to an incidental side-effect of the storage process.

          Please forward my Nobel Prize c/o my employers.

          HAL.

    • by pla (258480)
      I'd think with enough losses along the way

      You can say that about any energy storage mechanism, from capacitors to compressed air to iron-pine-cones-on-a-chain.

      I think we can safely presume that the engineers involved in this project took such issues under consideration and didn't choose to use Playschool's My First Wind Turbine. ;-)


      I'm not suggesting that bleeding-edge science should be economically feasible

      This doesn't really count as "bleeding edge"... I don't know if the world has ever seen an
    • What happens if the wind that should be generating electricity for the compressors takes the day off and chooses to make an unfashionably late arrival?

      The whole process is reversible (with some losses): they just use the compressed air to turn the turbine blades!

  • Why air? (Score:1, Insightful)

    by Anonymous Coward

    I'd think geothermal or tidal power generation would be much better personally, harnessing an easily recyclable process seems like a much better idea. I've often wondered if the pressure of the ocean at extreme depths could make mechanical generational of power viable using simply the pressure of the ocean itself.

    • Re: (Score:2, Insightful)

      by srjh (1316705)
      This doesn't compete with geothermal or tidal generation, so it's not necessarily any "better" or "worse". It's really more of an energy storage method (like a battery) that may even be useful as a supplement to something like geothermal generation. Store the energy at night when demand is low, and release it during the day when demand is high, and you'll smooth out variations in the power supply.

      Also, you need a pressure difference to extract energy, just a high pressure is not good enough (similar to th
    • Re: (Score:3, Insightful)

      by liquidpele (663430)
      Umm... perhpas I'm falling for a Troll, but using "pressure" for energy would be like using gravity for energy. If you find a way, let me know!
      • Re: (Score:3, Informative)

        by dbIII (701233)

        would be like using gravity for energy. If you find a way, let me know!

        Easy:

        1/ Lift musical instrument high into the air.

        2/ Let go.

        3/ Voila - energy from gravity!

        • Re: (Score:3, Insightful)

          by liquidpele (663430)
          perhaps I should expand on my comment...

          If the poster meant using the pressure in the ocean to *store* energy (for instance, compress air down there) to then convert back to electrical (or whatever), that's possible but it would be even harder than storing huge amounts of pressurized air in up here since you still have to build a container and ensure it's integrity (which is why the cave idea is interesting).

          However, I was assuming the poster wanted to use the pressure to induce some kind of perpetual
        • Re:Why air? (Score:4, Funny)

          by jollyreaper (513215) on Thursday July 03, 2008 @08:07AM (#24041585)

          Easy:

          1/ Lift musical instrument high into the air.

          2/ Let go.

          3/ Viola - energy from gravity!

          Corrected.

      • by jonnythan (79727)

        Lots of places already use gravity as a form of energy storage.

        During the night at some hydro plants, where energy demand is low but supply is relatively consistent, they use the excess energy to pump water to a reservoir at the top of a hill.

        Then, during the day, they let that water flow down the hill and spin a turbine.

        • Actually, hydroelectric as practiced by forming large lakes from rivers is entirely about using gravity for energy storage. The main difference with pumping the water back into the reservoir is that you have more control of how much you're storing. The reservoir itself is an energy store from the start. You're storing the energy that would have allowed that water to flow downstream by putting earth and concrete in its way.

      • by Wormholio (729552)

        Umm... perhpas I'm falling for a Troll, but using "pressure" for energy would be like using gravity for energy. If you find a way, let me know!

        How about letting water, pulled downward by gravity, turn a wheel or turbine?

    • by Wormholio (729552)

      I'd think geothermal or tidal power generation would be much better personally, harnessing an easily recyclable process seems like a much better idea.

      But the area where this is to be used may not have geothermal or an ocean nearby. The natural resource they do make use of is wind, and caverns in which to store the presurized air. So it's still harnessing a natural process/resource.

  • ...for that new movie with Brendan Fraser and the dinosaurs?
  • Not really new news? (Score:5, Informative)

    by inflex (123318) on Thursday July 03, 2008 @12:16AM (#24039693) Homepage Journal

    This has been done on large scales by a couple of power plants in the past.

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

  • Kubla Khan (Score:5, Funny)

    by lazyDog86 (1191443) on Thursday July 03, 2008 @12:17AM (#24039697)
    In Xanadu did Kubla Khan
    a stately pleasure dome decree
    where Aleph, the sacred river ran
    down to caverns measureless to man...
    from memory, apologies to Coleridge

    Those words were famously written after an opium-induced hallucination, as was this plan
    • Huh. After reading all the above comments, I read yours as "a stately pressure dome".
    • by dmatos (232892)

      Not bad, but it differs slightly from my memory:

      through caverns measureless to man
      down to a sunless sea

      • down to a sunless sea

        Of course, I forgot the sunless sea. Seems to be clear support for tidal power, but I'm left wondering why "sunless?" What problem did Coleridge have with solar power?

        • by dmatos (232892)

          Sadly, until we manage to curtail our fossil fuel use, the clouds of smog prevent the sun from reaching the sea.

  • Flatulence (Score:5, Funny)

    by riceboy50 (631755) on Thursday July 03, 2008 @12:24AM (#24039733)
    Yeah, I keep a lot of compressed air in my cavern. It's so powerful that sometimes I can't contain it any longer and it escapes. /ducks
    • by xtracto (837672) *

      AAAAhhh!! so the energy farms shown in the matrix were really obtaining the energy from pumping that kind of compressed energy...

      Why did Neo had to be unplug from the head then??

  • I can just imagine some poor hiker being blasted into the sky walking or climbing over one of these pressurized caverns, just because the engineers had missed a hole somewhere inside the main cavern.

    It'd be ideal if they could spray some kind of airtight lining along the walls, but that wouldn't be too eco-friendly, would it?

    • by Paltin (983254)

      Err. Two things: First, the cavern's aren't really caverns. They generally look for a layer of porous rock capped by non-porous rock. So they actually pump the air into the voidspace in the right sedimentary layer (usually a sandstone). Second, the 'caverns' are generally very deep. If there is significant leaking, it won't have much of an effect on the surface; too much dirt between there and here.

  • Ecofriendly? (Score:2, Insightful)

    by FrostDust (1009075)
    Maybe I didn't understand the article well enough, but it just seems to me like they're using energy to compress air in caverns during the night, then using that air to make energy production during the day more efficient. Unless they're violating thermodynamics here, the amount of energy gained by using this compressed air system can't be more than the amount of energy used to compress this air into the caverns.

    So, is it that only benefit here, cheaper energy costs, comes about because they're buying the
    • Think of it more as load-balancing...

      They're not creating any more energy (thermodynamics, as you mentioned), but simply storing any excess produced for use during times of high load.

      This is similar to existing methods used, eg. hydro-electric dams that use their excess energy to pump water back up the river.

      It's like putting your change in a piggy bank, instead of throwing it in the gutter.
    • Where something like this makes the most sense is when used in conjunction with something like wind power. At night, when power usage is lower you can use the excess energy from the wind turbines to pump air into the cavern. Then during the day as the output from the wind turbines varies and doesn't meet demand you can use the stored energy to even out or supplement the energy production.
    • A similar system is used quite frequently today where water is pumped uphill into a reservoir at night, and then run through a hydro-electric plant during the day.

      It isn't just that electricity costs more during the day though. With a traditional (coal or nuclear) power plant, it is less energy efficient to run at reduced capacity compared to running at full capacity (I think it has to do with the pressure in the steam chambers). You also waste a fair bit of energy to starting and stopping a plant. However,

  • Interesting idea, but IMHO, these will be obsolete fairly soon. Plug-in hybrid cars are right around the corner, and they're going to use up a lot of off-peak power - I think. I've never seen the math, but I imagine that moving a car 20 miles on batteries is equivalent to a whole lot of light bulbs, computers, and TV hours. That's the exact same target power that compressed air, and gravity storage (i.e. pump water uphill) are meant to store for peak time. Also, solar power, the other power plant of the
    • Yes, but coal, gas, oil and nuclear power plants all must continue to run overnight. Most of these use steam turbines and reheating partially cooled water is a lot less efficient than keeping it on the boil. Starting a turbine up from static takes a lot more energy than keeping it moving. It also takes in the order of weeks to stop or start a nuclear reactor.

      Even before the big push for renewables were overgenerating significantly at night. The low cost of night-time electricity gave rise to fire-brick stor

      • by Grishnakh (216268)

        You're missing the point. In the near future, there's not going to be excess generation at night, because the demand is going to be much, much higher: everyone's going to be recharging their electric cars in their garages at night while they're sleeping.

  • You've deflated the Earth!!!

  • I don't really know much about earth or soil sciences, but just off the top of my head, would this not cause destabilization in the ground above the surface of these caverns? I'm just thinking about things like cave-ins and whatnot.
    • Re: (Score:2, Funny)

      by dsvilko (217134)

      You mean cave-outs.

    • by khallow (566160)
      The pressure of the gas would support the weight of the rock above. I imagine as long as the bubble of gas is horizontal, pancake shaped (much as what would happen if it were injected just below a flat impermeable layer of rock) then the low density of the gas won't be sufficient to cause it to migrate towards the surface.
  • As gas expands, it cools. Assuming the compressed gas has enough time to cool considerably before it's released again, couldn't this also be used like a reverse long-distance heating to save more energy during summer months?
    • by Thelasko (1196535)
      They plan to heat the air before they let it expand. It allows them to extract more energy.
  • Hmmm (Score:4, Funny)

    by bagsc (254194) on Thursday July 03, 2008 @06:41AM (#24041155) Journal

    Why not just put carbon dioxide down there, and burn more coal?

    • It's probably because this doesn't require us to burn more coal and separate out the carbon dioxide. This is meant to store excess energy so we can use less production capacity more efficiently, and it uses whole air.

  • Wind puffs during night turn the turbines, which compress air and store it underground. The stored air can then turn the turbines to regenerate the night puffs during the day, when people are awake and can appreciate them! Profit!
  • ..that thrive in these caverns? Who knows what kind of impact it would have on the earth as a whole if we eliminate dozens/hundreds of subterranian life forms with this plan.

    This could possibly be the most short-sighted plan yet.

    • How about if we start with deep mines and the refilled strip mines once they are done producing? That way, they're man-made holes to start with. Then we can move on to places where we took oil and gas out of the ground, perhaps, which according to traditional wisdom also won't have anything growing.

      • Who's traditional wisdom? There are very few places on earth that are not loaded with microorganisms. Even fresh basalt rock on the bottom of the ocean (where "fresh" means something like 20,000 years old) is full of microorganisms. I doubt very much that oil and gas fields are sterile.

  • will it still be after you compress the air?
    • If they use the spaces they took natural gas and oil out of, they should be reasonably able to withstand the pressure. 1200 PSI really isn't that much pressure for a thick layer of rock.

  • Without having read TFA, I imagined they were simply using the compressed air to power a generator... sort of like putting a pinwheel in front of the nozzle from a balloon. Which wouldn't have been so much more efficient, really.

    It's more interesting than that, though. They're using the compressed air as the input to (natural gas)-powered turbines, saving on the energy that would have been used to run the compressors.

    I'm still not sure where the energy savings comes in, though. The article says "uses fue

  • My instantaneous reaction is . . . Caverns Leak . . .
  • The problem being addresses is the intermittent nature some renewable power sources (e.g., wind & solar). In some cases the delivery curve from some sources will match your demand curve and then you have a win. Of course sometimes it does not match the demand curve so you have three options: 1) add more distributed capacity to handle any peak needs so that even if one hears has clouds or no wind the rest make up for that (very high capital cost), 2) create a storage medium such as pumped water, compre
  • Newton's Laws and the Laws of Thermodynamics and whatnot. What are the long-term effects of all these?
    Using tidal energy will give us lower tides.
    Use enough solar power and the Earth gets less heat.
    Use enough wind and weather patterns change.
    Energy and matter are both finite, and every system favors entropy.

    Seems to me we can't really escape it and every option has the potential to adversely affect the entire planet, whether people acknowledge it or not.
    Anyone who says otherwise is selling something...

If a 6600 used paper tape instead of core memory, it would use up tape at about 30 miles/second. -- Grishman, Assembly Language Programming

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