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Cheaper Energy From Caverns of Compressed Air

samzenpus posted more than 6 years ago | from the fine-until-the-earth-burps dept.

Earth 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."

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vast? (4, Funny)

Ydna (32354) | more than 6 years ago | (#24039453)

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!

Re:vast? (-1, Troll)

Anonymous Coward | more than 6 years ago | (#24039533)

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 really don't think that the underground caverns would be large enough to contain quite that much air.

If they were to use your mother's vast underground vaginal canals, on the other hand...

I don't believe it... (3, Funny)

AlienIntelligence (1184493) | more than 6 years ago | (#24039573)

I think those guys are full of vast hot air.

Re:vast? (1, Funny)

Anonymous Coward | more than 6 years ago | (#24039679)

That's my colon you insensitive clod...

Re:vast? (5, Funny)

w0mprat (1317953) | more than 6 years ago | (#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!

Re:vast? (1)

nog_lorp (896553) | more than 6 years ago | (#24040139)

You are very wrong on one important point. Vacuum is abundant in the earth's air, the issue is extracting it!

Re:vast? (5, Funny)

srjh (1316705) | more than 6 years ago | (#24040275)

You'll also need to purify the dirty vacuum that is present in the earth's atmosphere.

I suggest a vacuum cleaner for the task. (ducks)

Re:vast? (4, Funny)

PHPfanboy (841183) | more than 6 years ago | (#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".

Re:vast? (1)

sumdumass (711423) | more than 6 years ago | (#24040893)

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:vast? (1)

PFactor (135319) | more than 6 years ago | (#24042637)

Only teenage geeks?

Re:vast? (1)

sumdumass (711423) | more than 6 years ago | (#24045311)

Well, just think of the children..

Re:vast? (2, Funny)

TropicalCoder (898500) | more than 6 years ago | (#24041245)

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.

Untapped reserves (4, Funny)

KlaymenDK (713149) | more than 6 years ago | (#24040605)

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:Untapped reserves (2, Funny)

doug (926) | more than 6 years ago | (#24045351)

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

Re:vast? (0)

Anonymous Coward | more than 6 years ago | (#24041263)

i see a vacume emissions global trading scheme brewing :P

Re:vast? (0)

Chemisor (97276) | more than 6 years ago | (#24041301)

> 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.

Re:vast? (1)

sydbarrett74 (74307) | more than 6 years ago | (#24040347)

Well, then we'll just steal Druidia's atmosphere....

we are pwned by mice? (1)

rootpassbird (1276000) | more than 6 years ago | (#24047079)

Revenge of the mighty jurrassic mice in the year of the rat [wikipedia.org] ?

Re:vast? (1)

thewiz (24994) | more than 6 years ago | (#24047227)

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

How Efficient is It? (3, Insightful)

TheStonepedo (885845) | more than 6 years ago | (#24039503)

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:How Efficient is It? (2, Informative)

tirerim (1108567) | more than 6 years ago | (#24039527)

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.

Re:How Efficient is It? (3, Insightful)

Rakishi (759894) | more than 6 years ago | (#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:How Efficient is It? (2, Funny)

Anomalyst (742352) | more than 6 years ago | (#24043521)

We don't cache energy in your toilet, please don't pee in our pumped storage.

Re:How Efficient is It? (1)

Rei (128717) | more than 6 years ago | (#24045525)

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 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.

Re:How Efficient is It? (3, Insightful)

Simon Brooke (45012) | more than 6 years ago | (#24040739)

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.

Re:How Efficient is It? (1)

jandrese (485) | more than 6 years ago | (#24045491)

As a bonus, you occasionally get "free" energy out of your storage system when it rains.

Re:How Efficient is It? (2, Informative)

Free the Cowards (1280296) | more than 6 years ago | (#24039545)

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? (4, Informative)

WalksOnDirt (704461) | more than 6 years ago | (#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.

Re:How Efficient is It? (1)

Clifton Beach (809210) | more than 6 years ago | (#24041113)

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.

Re:How Efficient is It? (1)

Fzz (153115) | more than 6 years ago | (#24041807)

Or just build Google's datacenter next door, and use the cheap cool air to chill it.

Re:How Efficient is It? (1)

Thelasko (1196535) | more than 6 years ago | (#24043023)

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 intercoolers. [wikipedia.org]

Re:How Efficient is It? (1)

wooferhound (546132) | more than 6 years ago | (#24045171)

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:How Efficient is It? (2, Interesting)

kesuki (321456) | more than 6 years ago | (#24039735)

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 gasket, you probably don't lose much, unless it happens to take the hill the windmill was on with it.

worse still, if you take down a farmhouse loaded full of farmers and get sued.. yeah the risk is low, and it saves using coal... oh and BTW because the power comes from the grid, the wind farm can be in one place, the cave system turbines in another location... (eg: using the same turbines to fill the caves as to create power at night)

but still, I'd feel safer with a atomic power plant in my backyard than a giant cave system being used to compress and store air to make power at night time.

Re:How Efficient is It? (1)

skiingyac (262641) | more than 6 years ago | (#24041751)

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? (3, Insightful)

dbIII (701233) | more than 6 years ago | (#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.

Re:How Efficient is It? (0)

Anonymous Coward | more than 6 years ago | (#24044103)

There's a better way to store excess generated energy during the night -- Car batteries. As the manufacture of plug-in hybrids ramps up there will be an ever increasing electricity drain from the grid as people charge their cars at night. These batteries may even be able to give back during the day to cover "peak" times, as Google has been experimenting with.

Re:How Efficient is It? (0)

Anonymous Coward | more than 6 years ago | (#24044267)

You are forgetting that storage of the electricity adds to the cost. Windmills have difficulty getting competative as it is, and even the most efficient pumped storage schemes are likely to cause a loss of 10%-20% of the energy or more.

Also, cheaper energy storage doesn't just benefit wind power. It could allow traditionally baseload plants like nuclear and coal to be used for load following the, letting them operate at full capacity during off-peak hours, selling the energy at the higher prices during peak.

Therefore cheaper energy storage schemes will not make wind power more competative, as it benefits the baseload plants like nuclear and coal just as much as it benefits wind and solar.

The fundamental issue with wind and solar is the price. Enthusiasts like to quote their price per-watt as measured during peak output. Taking into consideration that capacity factors can be as low as 30% ( as compared to 80%-90% for nuclear and coal ) this typically underestimates their costs by a factor of 3 or so.

Heck, even nano-solar's so far unconfirmed claim of hoping to achieve $1 per watt for solar cells is not very impressive when you consider that about half the cost is in converters and storage, giving you $2 per watt, and that capacity factors will likely be lessthan 30%, giving an average price of about $6 per watt.

Re:How Efficient is It? (0)

jo42 (227475) | more than 6 years ago | (#24039951)

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:How Efficient is It? (2, Funny)

AlienIntelligence (1184493) | more than 6 years ago | (#24040427)

/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 =) ]

Re:How Efficient is It? (1)

burni (930725) | more than 6 years ago | (#24040481)

[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 damaged turbines.

These are the odds, but on the other hand it works,
there is one plant in germany which I know which is operational since round about 2ys.

Re:How Efficient is It? (1)

Half-pint HAL (718102) | more than 6 years ago | (#24041011)

[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.

Re:How Efficient is It? (1)

Half-pint HAL (718102) | more than 6 years ago | (#24041139)

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.

Re:How Efficient is It? (1)

pla (258480) | more than 6 years ago | (#24041469)

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 any large-scale implementations of the idea, but cavern-based compressed air storage of energy has existed since (at least) the 1960s.

And conceptually, this doesn't differ drastically from pumping water uphill, except that you need a cave instead of a reservoir.

Re:How Efficient is It? (1)

White Yeti (927387) | more than 6 years ago | (#24042861)

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? (1, Insightful)

Anonymous Coward | more than 6 years ago | (#24039529)

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:Why air? (2, Insightful)

srjh (1316705) | more than 6 years ago | (#24039601)

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 the fact that you can't extract electrical power from heat alone - you also need a cold reservoir).

Re:Why air? (2, Insightful)

liquidpele (663430) | more than 6 years ago | (#24039629)

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:Why air? (0)

Anonymous Coward | more than 6 years ago | (#24039709)

It is incredibly easy to use gravity to store energy. Ever walk up a flight of stairs?

Re:Why air? (2, Informative)

dbIII (701233) | more than 6 years ago | (#24039789)

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:Why air? (2, Insightful)

liquidpele (663430) | more than 6 years ago | (#24039867)

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 motion for creating energy, which is just funny.

Re:Why air? (3, Funny)

jollyreaper (513215) | more than 6 years ago | (#24041585)

Easy:

1/ Lift musical instrument high into the air.

2/ Let go.

3/ Viola - energy from gravity!

Corrected.

Re:Why air? (1)

jonnythan (79727) | more than 6 years ago | (#24042387)

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.

Re:Why air? (1)

mr_mischief (456295) | more than 6 years ago | (#24044869)

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.

Re:Why air? (1)

Wormholio (729552) | more than 6 years ago | (#24043497)

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?

Re:Why air? (1)

Wormholio (729552) | more than 6 years ago | (#24044965)

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.

watch your step (0)

Anonymous Coward | more than 6 years ago | (#24039543)

Underground caverns where newfangled energy producing technology has been introduced might not be the optimum place to own real estate. [foxnews.com]

Fuck it (-1, Offtopic)

Anonymous Coward | more than 6 years ago | (#24039621)

This is why capitalism is my dog and vermillion flounder crescent formerly/.

even easier (0)

ILuvRamen (1026668) | more than 6 years ago | (#24039647)

Yeah well if you stand out in the sun for 10 seconds in black clothes, you get hot. It doesn't get much easier than that. Why drill into the earth when we're being bombarded by unbelievable amount of solar energy right here on the surface. If I was president, almost all funding would go to developing solar hydraulic towers and more effective solar panels. Plus, compressed air runs out. The sun won't for quite a while.

Re:even easier (1)

bluemonq (812827) | more than 6 years ago | (#24039671)

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.

Re:even easier (1)

Microlith (54737) | more than 6 years ago | (#24039675)

Plus, compressed air runs out.

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.

Re:even easier (1)

hardburn (141468) | more than 6 years ago | (#24039871)

I'm glad you're not President.

Re:even easier (1)

servognome (738846) | more than 6 years ago | (#24040127)

Though it does seem like one of his speeches, I mean with the whole standing out in the sun with black clothes gets you hot insight.

Is this just a promo... (1)

Sethumme (1313479) | more than 6 years ago | (#24039649)

...for that new movie with Brendan Fraser and the dinosaurs?

Kubla Khan (5, Funny)

lazyDog86 (1191443) | more than 6 years ago | (#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

Re:Kubla Khan (1)

White Yeti (927387) | more than 6 years ago | (#24042971)

Huh. After reading all the above comments, I read yours as "a stately pressure dome".

Re:Kubla Khan (1)

dmatos (232892) | more than 6 years ago | (#24043209)

Not bad, but it differs slightly from my memory:

through caverns measureless to man
down to a sunless sea

Re:Kubla Khan (1)

lazyDog86 (1191443) | more than 6 years ago | (#24045393)

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?

Flatulence (4, Funny)

riceboy50 (631755) | more than 6 years ago | (#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

Not quite (0)

Anonymous Coward | more than 6 years ago | (#24039803)

It is the rest of us that have to duck, not you.

Re:Flatulence (0)

Anonymous Coward | more than 6 years ago | (#24039933)

Pro tip: don't put the punch line as the subject.

Re:Flatulence (0)

Anonymous Coward | more than 6 years ago | (#24042219)

Well, riceboy50, I for one am glad you are not beanboy! Then we could just hook up that turbine to your ass and let the good times roll.

Re:Flatulence (1)

xtracto (837672) | more than 6 years ago | (#24042679)

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 (1)

steelfood (895457) | more than 6 years ago | (#24039807)

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?

Re:Maybe not such a good idea (1)

Paltin (983254) | more than 6 years ago | (#24047981)

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.

Caverns (1)

mrv00t (858087) | more than 6 years ago | (#24039827)

Caverns of Compressed Air

Earth is farting?

Re:Caverns (1, Funny)

Anonymous Coward | more than 6 years ago | (#24043807)

Nah. The Earth lights it farts and we call them volcanic eruptions.

Ecofriendly? (2, Insightful)

FrostDust (1009075) | more than 6 years ago | (#24040021)

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 energy when it's cheaper, and storing it for use when paying for this energy is more expensive?

Re:Ecofriendly? (1)

FlatWhatson (802600) | more than 6 years ago | (#24040231)

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.

Re:Ecofriendly? (1)

confused one (671304) | more than 6 years ago | (#24047015)

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.

It won't be long until plug-in hybrids... (0)

WoTG (610710) | more than 6 years ago | (#24040363)

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 future doesn't work very well at night. So, for the overall grid, the peak aren't going to be as dramatic.

Re:It won't be long until plug-in hybrids... (1)

Half-pint HAL (718102) | more than 6 years ago | (#24041047)

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 storage heaters. It's also the reason why the showers in some low-end hotels and campsites are only properly hot in the morning. It also helped support the rise in shift-working: the overtime may be expensive, but the machines run cheaply.

HAL.

You FOOLS!!! (1)

SurturZ (54334) | more than 6 years ago | (#24040447)

You've deflated the Earth!!!

How long will it last? (1)

n3tcat (664243) | more than 6 years ago | (#24040455)

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:How long will it last? (2, Funny)

dsvilko (217134) | more than 6 years ago | (#24040901)

You mean cave-outs.

Re:How long will it last? (1)

khallow (566160) | more than 6 years ago | (#24040915)

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.

Dual-Use for long-distance air-conditioning? (1)

GroeFaZ (850443) | more than 6 years ago | (#24040631)

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?

Re:Dual-Use for long-distance air-conditioning? (1)

Thelasko (1196535) | more than 6 years ago | (#24043203)

They plan to heat the air before they let it expand. It allows them to extract more energy.

Hmmm (3, Funny)

bagsc (254194) | more than 6 years ago | (#24041155)

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

Re:Hmmm (1)

mr_mischief (456295) | more than 6 years ago | (#24044989)

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 (1)

Bromskloss (750445) | more than 6 years ago | (#24041255)

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!

And what about the ecosystems... (1)

brunes69 (86786) | more than 6 years ago | (#24041933)

..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.

Re:And what about the ecosystems... (1)

mr_mischief (456295) | more than 6 years ago | (#24045025)

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.

Re:And what about the ecosystems... (1)

djchristensen (472087) | more than 6 years ago | (#24049283)

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... (1)

Thelasko (1196535) | more than 6 years ago | (#24043327)

will it still be after you compress the air?

Re:The rock is air tight now... (1)

mr_mischief (456295) | more than 6 years ago | (#24045063)

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 (1)

sabt-pestnu (967671) | more than 6 years ago | (#24045159)

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 fuel more efficiently"... but then why not treat the fuel that way ALL the time? Because you don't have the "excess" compressed air? But you're using power (the night-time wind generation) to create that excess.

The only case I can see where this actually buys you anything is if your wind generation at night is also in excess of your needs at night. I'll grant you "generation minimums" (below which the cost of restarting the gas/coal/whatever generators becomes an issue), which might help the wind power be "an excess".

Cave Fart (1)

wooferhound (546132) | more than 6 years ago | (#24045289)

My instantaneous reaction is . . . Caverns Leak . . .

Many Solutions to Many Problems (1)

MountainLogic (92466) | more than 6 years ago | (#24046039)

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, compressed air, chemical batteries, or in the case of thermal solar thermal storage (heat up a really big tank of sodium metal) - it is all a matter of creating "capacitance" in the system, 3) The best way to manage a non-ideal supply curve is to alter your demand curve. There are many big energy user such as ice plants, chemical plants, water pumping, and other industrial plants that can be interrupted on short notice or be scheduled to change the shape of the demand curve. Also, expect to start seeing appliance that will get cues from the utility company to postpone their demand until power is cheaper.

Please, Someone, Think About the Bat Children (0)

Anonymous Coward | more than 6 years ago | (#24047949)

This doesn't seem like a good thing for all the critters living in those caverns.

Why do I have to smack the Preview and Submit buttons about ten times each before slashdot finally takes the post now?

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