Cheaper Energy From Caverns of Compressed Air 114
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."
vast? (Score:5, Funny)
I don't believe it... (Score:2, Funny)
I think those guys are full of vast hot air.
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That's my colon you insensitive clod...
Re:vast? (Score:5, Funny)
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Re:vast? (Score:5, Funny)
I suggest a vacuum cleaner for the task. (ducks)
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Re:vast? (Score:5, Funny)
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".
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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.
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Well, just think of the children..
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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.
Untapped reserves (Score:5, Funny)
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.
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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
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> 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.
Ignorant past generations (Score:2)
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we are pwned by mice? (Score:1)
Revenge of the mighty jurrassic mice in the year of the rat [wikipedia.org]?
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I can't decide whether this idea sucks or blows...
How Efficient is It? (Score:4, Insightful)
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.
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Re:How Efficient is It? (Score:4, Insightful)
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.
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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
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...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
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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
Re:How Efficient is It? (Score:4, Insightful)
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.
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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.
Re:How Efficient is It? (Score:5, Informative)
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.
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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]
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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
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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.
Re:How Efficient is It? (Score:4, Insightful)
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.
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Also comparing photovoltaics to large base load thermal is pointless - solar can produce thermal power as well and that's what you would use to generate gigawatts instead of those expensive photovoltaics which are ideal for small installations off the grid instead.
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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?
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/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 =) ]
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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
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[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.
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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.
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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
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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)
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.
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Also, you need a pressure difference to extract energy, just a high pressure is not good enough (similar to th
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Easy:
1/ Lift musical instrument high into the air.
2/ Let go.
3/ Voila - energy from gravity!
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Re:Why air? (Score:4, Funny)
Easy:
1/ Lift musical instrument high into the air.
2/ Let go.
3/ Viola - energy from gravity!
Corrected.
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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.
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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.
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How about letting water, pulled downward by gravity, turn a wheel or turbine?
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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.
Is this just a promo... (Score:1)
Not really new news? (Score:5, Informative)
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)
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
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Not bad, but it differs slightly from my memory:
through caverns measureless to man
down to a sunless sea
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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?
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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)
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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??
Maybe not such a good idea (Score:2)
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?
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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)
So, is it that only benefit here, cheaper energy costs, comes about because they're buying the
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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.
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Yes it is energy efficient. (Score:2)
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,
It won't be long until plug-in hybrids... (Score:1)
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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
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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 FOOLS!!! (Score:2)
You've deflated the Earth!!!
How long will it last? (Score:2)
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You mean cave-outs.
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Dual-Use for long-distance air-conditioning? (Score:2)
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Hmmm (Score:4, Funny)
Why not just put carbon dioxide down there, and burn more coal?
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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.
I get it now (Score:2)
And what about the ecosystems... (Score:2)
..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.
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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.
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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.
The rock is air tight now... (Score:2)
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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.
Trade-offs (Score:1)
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
Cave Fart (Score:1)
Many Solutions to Many Problems (Score:2)
It seems to me that EVERYTHING has a consequence (Score:1)
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...
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You seem to be confusing energy generation with energy storage. Collected energy (say, your beloved solar energy) would be used to compress air, which would be stored. When more energy is needed than is instantaneously available, that compressed air would be utilized.
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I was under the impression that you would use the compressed air to power a turbine during times of low wind, and use excess power generated by wind turbines (or other renewable forms) to compress the air.
Essentially, a giant underground gas-battery.
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I'm glad you're not President.
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Thankfully there is abundant sunshine at night, when people want to turn on lights and watch their huge plasma TVs. Well, there is in some places in summer, but I doubt you will get hot there without large amounts of Vodka.
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Nah. The Earth lights it farts and we call them volcanic eruptions.