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Forget Better Batteries, Nothing That Exists Or is in Development Can Store Energy as Well, And as Cheaply, as Compressed Air (theconversation.com)
An anonymous reader shares a report: The concept seems simple: you just suck in some air from the atmosphere, compress it using electrically-driven compressors and store the energy in the form of pressurised air. When you need that energy you just let the air out and pass it through a machine that takes the energy from the air and turns an electrical generator. Compressed air energy storage (or CAES), to give it its full name, can involve storing air in steel tanks or in much less expensive containments deep underwater. In some cases, high pressure air can be stored in caverns deep underground, either excavated directly out of hard rock or formed in large salt deposits by so-called "solution mining", where water is pumped in and salty water comes out. Such salt caverns are often used to store natural gas. Compressed air could easily deliver the required scale of storage, but it remains grossly undervalued by policymakers, funding bodies and the energy industry itself. This has stunted the development of the technology and means it is likely that much more expensive and less effective solutions will instead be adopted.
Look up Shingeki no Kyojin for more info on the amazing potential of compressed air. Don't believe me? Watch this.
Hold my beer. I have a plan.
This seems unlikely to replace batteries at the small scale. Even discounting the risks of puncture or leakage in mobile devices like cell phones or computers; the equipment necessary to compress air into containers can likely only be scaled down so far before it loses efficiency.
Plus every air compressor I've ever seen or worked with is pretty loud. Maybe there are ways to reduce the noise; but this ultimately seems like more of a large scale way to store energy produced via solar or wind power than a replacement for traditional batteries.
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There is no “minimum storage pressure” but the economics are poor for anything lower than 50bar. For CAES with tanks, the economics push you towards pressures of 200 - 250 bar. In caverns, the pressure you can use depends on the cavern depth. 120bar is not unusual. For a cavern with 120bar storage pressure that was allowed to swing down to (say) 70bar when “discharged”, you would be storing ~23MJ in each cubic meter of cavern. Thus for 1GWh (3.6 million MJ), you would need 156,000 cubic metres of cavern. That is actually a relatively small salt cavern! If it was a sphere, it would have radius of 33.4m. Surprising as it may seem, most salt caverns in existence are bigger than that!
This is not a quote I find anywhere in TFS, TFA, or in any of the articles linked from TFA.
There are a lot of ways to store wind and solar, all of which are somewhat underutilized. Pumped hydro (where water is pumped uphill) is an alternative, as are giant flywheels spinning in a vacuum with magnets on the rim. There are a lot of alternatives to batteries that are in active use.
NOWHERE, other than in the headline, is the claim made that compressed air is SUPERIOR to any of these other "alternative to batteries" technologies.
NOWHERE is there even a direct comparison made to batteries, other than a passing (and unsubstantiated) reference that "batteries work well for short term storage" with an implicit comparison that CAES is more suited to longer term storage.
Where the heck did this headline come from? Citation needed.
Compressed Air Energy has one major drawback. If there is a problem it could cause an explosion. And unlike from chemical energy storage such explosions cannot be monitored and cutoff as quickly.
I once had a tanker truck drive by me, and at the same time, the tanker had buckled inwards a dent (probably from pressure differences from changing altitude) I needed to stop my car and inspect it, because that little buckle felt like something had hit my car from that pressure wave.
There is a lot of danger in compressed air.
This can be mitigated with proper maintenance and monitoring. But this is the same with nuclear energy, Companies don't want to do it, because it costs money that cuts into its profits, and governments don't want to do it, because the Tax payers need to pay for it.
If something is so important that you feel the need to post it on the internet... It probably isn't that important.
More information from the author of the study...
Turnaround efficiencies are mis-reported for CAES. If you think about pure electricity-in-electricity-out storage, then it is certainly possible to beat 70% even at small scale and at large scale you are likely to get 80% (if you do all the right things with management of heat).
CAES does always involve managing heat but nobody with any sense would store pressurised air hot. Yes air does tend to rise in temperature when you compress it but all of the serious proposals for CAES systems remove the heat from the air before storing the air. For good performance, you store the heat (separately) and use it later on during the air expansion. Apart from the fact that temperatures would weaken or destroy the air containment, they would also mean that you stored a lot less air (by mass) in the same containment. The pressurised air containment is the most expensive part of most CAES systems so you want to work this as hard as you can.
The article is fairly useless.
No numbers at all. Pretty much just, "Hey, they would be a great idea".
Better if they provided at least estimates for:
How much energy to compress?
How much energy when released?
Efficiency?
How long can natural formations reasonable expect to maintain pressure?
How much volume required for X power on the grind, for how long?
Locations for natural formations?
etc.
When Fascism comes to America, it will call itself Anti-Fascism, and tell you to give up your guns.
All you have to do is observe the heat cast off by such a process from compressor to storage to know this to be a dubious claim. The greater the storage pressure, the worse the efficiency becomes. Never mind the challenges, expense, and hazards involved in implementing and maintaining pressure bottles. If you're free to concern yourself solely with energy density, as in this case with HPA then, you might as well bring nuclear fission--the gold standard for energy density--back on the table.
Two of my imaginary friends reproduced once
When you release compressed air, it cools the environment. It's the nature of it, and air conditioning.
https://www.youtube.com/c/BrendaEM
Vaporware. Quite literally so.
We used to have a Bill of Rights. Now, with the rights gone, all we have left is the bill.
Saw a pie chart a day or 2 ago that shows natural gas and coal are about equal now in the US market. And since natural gas is now cheaper than coal to build and run, US use of coal will continue to diminish. That, BTW, is the absolutely best way to replace polluting sources, by replacing them with cheaper things that don't pollute. IOW, don't pass a law against something, pass a law that helps create cheaper but cleaner resources and no, that doesn't mean subsidize something, because that is just the people paying more for something through taxes. No, REALLY make it cheaper - make something that is intrinsically cheaper. That's now natural gas. Hopefully some smart guy will build the 90% efficient solar cell, and these guys will perfect their air compression technique and we'll get 100% clean power.
What's the best way to move from coal to natural gas outside the USA? By fracking the F out of the oceans of natural gas reserves that the USA has, and selling it to the furriners... Its a win-win - they get cheaper electricity and the world gets less CO2 and other nasty shit in the air. Trump just did that by harrassing Angela Merkle, the German prime minister, into canceling her country's gas pipeline to Russia, and instead building liquified natural gas seaports for import of LNG by ships from... the USA. We better get to fracking every square inch if we want to reduce pollution.
Having worked with a lot of air compressors over the years I was suspicious of this as an efficient way to convert energy into a storage medium. After a quick Google I found a blurb on a manufacturer's website that up to 90% of electricity used to run a compressor is converted into heat.
https://www.quincycompressor.com/the-benefits-of-efficient-air-compressors/
I'd imagine that large-scale compressors are more efficient, and there would be some heat capture employed to utilize the energy lost there, but can this really compete?
I worked on a project doing exactly this about 5 years ago. The company, called SustainX, i believe is gone and disbanded. There are probably others too. They basically took a giant marine diesel engine and modified it become an air compressor in storage mode, and an expander in retrieval mode. They had solved some of the technical challenges of doing it in a thermodyanically efficient way. Something about isothermal and adiabatic. I forget the details but they have some elaborate mechanism for *both* the compression and expansion of the gas to extract a lot more usable energy. The big problem was storage. They used a giant tank array for their test system. They really wanted to deploy it globally but it turns out there's only a few locations in the entire word that have suitable geology for underground storage. So since tanks were relatively expensive and the geology wasn't prevalent, the company didn't sell anything and folded. Cool idea and very technically savvy company though.
Scott
Huh? We're talking about energy storage, not machine shop tools.
When considering safety, it's always good to look to people who have being doing it safely for decades, and see what's involved. The big presses have to store energy at very high PSI in order to operate. Their inspection procedures are non-trivial. Not very practical if you don't have the right kind of rock to use for storing vast quantities of energy.
Socialism: a lie told by totalitarians and believed by fools.
Small nukes can create a large cavern with fused glass walls
in a word, your nemesis will be *evaporation*, both in terms of desalination effort and water mass loss
I'd be nervous, though, about any storage in steel containers as that goes very bad when it goes (a few hundred PSI is one thing, but a few thousand PSI is another).
Shoot. There goes my plan to create a vast energy storage system based on 100,000 Harbor Freight 10-gallon air compressors strung together with hoses and extension cords. I'll have to use my 20% off coupon for something else.
I guess this idea will never get off the ground, since there aren't any engineers capable of figuring out a better solution.
People who say "sheeple" have about as much sophistication as an AOL user, and in fact are probably actually AOL users.
You're talking about a liquid under pressure. Pressurize liquids store very little energy, because they are largely uncompressable. You may have noticed, no one is talking about pressurizing (liquid) water to store energy.
You're talking about a liquid under pressure. Pressurize liquids store very little energy, because they are largely uncompressable.
You might find it informative to read about the biggest presses. The 1500 HP motors don't make nearly enough power to operate the press directly: they accumulate the energy in pressure accumulator bottles until there's enough in storage to operate the press once. it's a "hydro-pneumatic" system.
It's the only example I can think of where energy is routinely stored and discharged at thousands of PSI, and safely. Scuba tanks store air at a reasonable fraction of that pressure, but they aren't used for power (so limited fill/discharge rate) and they do blow up from time to time.
Socialism: a lie told by totalitarians and believed by fools.
Air is free and renewable, and doesn't need to be transported from where it is pumped from the ground over thousands of miles, and it doesn't need to be refined.
Other than the infrastructure, there is little resource cost, since it's not (yet) a commodity.
Now, does this make the article right? I'm not qualified to say that. But this guy is a professor of Dynamics, and is far more qualified than me.
In terms of storage of energy, and what you have to do to get there, it sounds like nobody is saying it's cheaper/more energy dense than gasoline, they're saying you can generate it and store it cheaply, and tie it in with other sources to smooth out the power generation and consumption.
By the time you're talking about tech with a long-life, over time it seems entirely reasonable the incremental cost at the end of that life is pretty damned small once you have it up and running.
You also get the added benefit you can fill your compressed air with pretty much any energy source, and save that power for later. Link a couple of sources together, and the usual whining about "but what about when it's dark outside" goes away.
I'm all for gasoline, and I use it twice a day, but it's not really a reversible process. I want a solar-powered machine that generates liquid fuel from atmospheric water and CO2.
Gas is less polluting than coal, but it's still not clean. It could be regarded as the less of two evils, just a stopgap until truly sustainable and non-polluting technologies are more viable.
Even better, that company owner probably doesn't appreciate the difference between 14 psi (Hyperloop) and 14,000 psi (energy storage to power a city). He can try using the same type of materials for both and see what happens.
For scale, dynamite (TNT) will create a pressure wave of around 500 psi @ 2 meters. A truck bomb will destroy a building 50 meters away with a 100 psi pressure wave.
#MeToo
Light travels faster than sound. This is why some people appear bright until you hear them speak.........
What you describe is the value proposition for plant-based ethanol. It's a complicated machine, yes, but that's what it does.
(And no I don't mean corn. Whatever idiot thought we should make fuel-hooch out of that needs to reconsider their career choices.)
I believe that with adiabatic compressed air storage http://energystorage.org/advanced-adiabatic-compressed-air-energy-storage-aa-caes the design goal is about 70% round trip energy efficiency, which is comparable with, just slightly lower than, li-ion battery systems once you factor in thermal-management energy requirements of the latter. That is, if you have a big li-ion batter bank in a container, you have to heat and cool it depending on the season and climate etc.
Retaining 70% of generated wind energy and PV energy for off-hours use is a very economically valid prospect. If thinking continent-wide, just build 42% more wind farms and PV arrays than you otherwise would need and you're golden. That's cheap as borscht.
Where are we going and why are we in a handbasket?
Every time you compress air, it is heated. The heat is lost energy. Every time you release air pressure, the air is cooled. More lost energy. No mention by the author, no analysis of the amount of lost energy. Bullshit article.
"Eve of Destruction", it's not just for old hippies anymore...
Someone proposed putting a large bag of air under lake Ontario and filling that. I can't find the study. Best places are either next to a large city (Toronto), nuclear plant (Pickering or Darlington) or wind generation. The sealed bag meant they could use clean, low humidity air. Not sure how they solved the heat problem (compressing the air makes it hot, if you lose the heat then you lose a high percentage of your energy. Ontario doesn't have the political competence to make this viable though. Maybe it would work on the US East coast?
Would Carbon Dioxide make more sense? It turns to liquid around 800PSI, so the stored volume is greater and it doesn't require increasing the pressure to store more energy (just increase the volume).
Finally, when you extract it you can make La Croix sparking soda's for an entire town's water supply at no cost.
Some drink at the fountain of knowledge. Others just gargle.
This assumes an adiabatic process. That means that you cannot loose any heat form the compressed air. So the storage tank would have to be insulated in a vacuum Dewar not practical or very expensive. A system that stores compressed air in a non adiabatic way, just about all the systems in existence, are only about 25% efficient. This really sucks compared to batteries.
I like the idea of deep water storage for places where that's convenient. I realize this probably isn't a huge issue considering the actual forces involved, but I'm not too fond on the idea of pumping water out of caves and then over-pressurizing them. Although if we get enough pressure then we might have the opportunity to set a new record.
"Our two-party system is like a bowl of shit looking at itself in a mirror." - Lewis Black
The answer lies in the phrase "economies of scale." There is almost NOTHING that you can do in your home, and have it be more efficient than the industrial version of the same. From baking bread to energy storage... industry has you beat. Solar power, wind power, battery storage, compressed air storage, geothermal... the list just keeps going... This is why as much as I love solar, I'll probably never have it on my house. The industry will find a way to do it better than I can, and I'm OK with that. Healthcare realized this fact decades ago.
Which has more power: the hammer, or the anvil?
I was curious about efficiency myself, and google and this page (http://energystorage.org/compressed-air-energy-storage-caes) suggests that straightforward energy storage as compressed air is about 42% efficient, increasing to 55% efficient if you can use the waste heat.
If you can store the heat separately to make the process adiabatic, then the efficiency climbs to ~70% - but then you've got the additional cost and complexity of trying to store energy as heat, which is arguably a much more challenging task.
For comparison a Li-ion battery is about 99% efficient, and pumped water is generally in the 60%-80% range, with some claims approaching 90%.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
Chemical engineer here.
So you know nothing of mechanical engineering then. But you do have "engineer disease": the belief that expertise in one field magically grants you expertise in another.
Hydraulic presses have been used for a long time. The hydraulics are used for exerting force not storing energy.
Yes, this one works differently than the one you saw once walking to chem lab.
Yes, I read the pdf you linked; no, I did not see anything about using liquid to store energy.
The PDF you "read" says:
The press force is generated by a hydro-pneumatic pressure system
consisting of four pre-filler bottles, two horizontal reciprocating pumps
driven by 1,500 H.P. motors, and four forged alloy steel pressure
accumulator bottles.
They aren't storing energy using liquid, obviously, which is why it's a hydro-pneumatic pressure system. You can find footage on YouTube of this beast operating. It pumps up pressure for some time before it's ready. It will use normal hydraulics to fast-fill the cylinders until first contact with the workpiece, then add stored power for the actual pressing.
It's an amazing piece of 50s tech, rebuilt in 74 with for very precise operation. If you've flown in a Boeing airliner, you've sat near to an aluminum frame piece forged by one of these presses.
Fun fact:
The hydro-pneumatic pressure system contains four accumulator
bottles maintaining a pressure of 4,500 pounds per square inch.
Each pressure bottle was forged in one piece by Mesta from a
195 ton alloy steel ingot.
Just the forging done to create this press was freaking impressive. It also shows what's involved in making a safe way to store 4500 PSI if you don't have a cavern handy.
Socialism: a lie told by totalitarians and believed by fools.
They only let you use that 20% off coupon for 1 item, no matter how much begging and pleading you do. Wait, maybe if each engineer had their own coupon...
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Except they got promoted. It's pretty much a requirement to win the Presidency, between Iowa's first -in-the-nation caucus and the great corn states' electoral votes.
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Great Gods fellow sentient being! Don't post things like that to a open forum! Now I have to go cower in the corner of a dark room till it passes.
I read at +2. If your post doesn't reach that level I will not see or respond to it.
it can be a little better than that, where compressed air is 15% efficient. in other words 85% of energy is wasted. those of us who work in industrial engineering know that fact. it's a lousy energy storage system, to thing some "greenie" would advocate it is hilarious.
Well, there goes my idea of a Beowulf cluster of compressed air tanks.
No, it definitely isn't. A process that sheds heat when done quickly, will still shed heat when done slowly. You might be thinking isothermal (constant temperature), in which case doing it slowly enough is one way to accomplish the goal. There's a lot of confusion between the two, but they're completely different concepts.
Adiabatic basically means "inside a well-insulated container" - it doesn't care how much the temperature changes, so long as no heat enters or leaves. In the case of compressed air storage, it sounds like the normal adiabatic process is to siphon off the heat generated by compression, store it separately in a medium that can store the same amount of heat with a much smaller temperature change and/or volume than the air, and then use it to re-heat the air as the pressure is released.
The Carnot cycle, basis of the internal combustion engine, actually contains two isothermal stages, in which pressure and volume change inversely (PV=constant) as heat is added and removed, and two reversible adiabatic stages where the gas changes temperature while expanding or contracting, without any external thermal transfer.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
1-You seem to think the American electric utility is 100% government owned. It's not. Try googling "Weakest Link" for the consequences of this public/private system. 2-Americans are subject to constant propaganda of "Government Bad, Corporations Good!". You should know that Governments work for you while Corporations want to take your money.
You should know that Governments work for you while Corporations want to take your money.
You my friend, do not live in Nebraska. It ain't for everyone.