Guest essay by Eric Worrall
Hydrostor has created an interesting innovation in energy storage. The energy is stored as compressed air, in giant underwater balloons.
Hydrostor’s system works in several steps. Electricity is run through a compressor and converted into compressed air. This compressed air is then sent underwater.
“There, we have a whole series of what are effectively balloons, that fill… like lungs under a lake,” he added.
“They fill with air, and when they’re full you stop charging the system and it can sit there indefinitely. When you want power back, again, a valve opens … air comes rushing out, we run through a low pressure turbine called a turbo expander, and that reproduces power back to the grid.”
Energy storage is becoming increasingly important. In the United States, the Office of Electricity Delivery & Energy Reliability states that the development of technology to store electricity so it’s available on whenever it’s needed would be a “major breakthrough in electricity distribution.”
Read more: http://www.cnbc.com/2015/12/09/underwater-balloons-clean-energy-savior.html
This isn’t the first time I’ve heard of storing energy with compressed air. Hydrostor’s innovation is to reduce the cost, by using water pressure to maintain the storage compression, without the need to create high strength pressure containers.
Using water to supply the pressure to collapse the balloons might also improve the efficiency of energy retrieval. By storing the air underwater, and using the water pressure to collapse the balloon, the air would be retrieved at a near constant pressure, until the balloon was empty. Hydrostor claim an efficiency of 60 – 80%.
Hydrostor seem to be aiming at grid stabilisation rather than storing multiple days worth of grid supply, so it seems unlikely this proposal, as it stands, will fully solve the renewable intermittency issue.
Could compressed air storage be scaled up enough to solve intermittency? Even if you had enough renewable capacity to cover 100% of grid requirements, on average, if you wanted to go further than Hydrostor’s current plans, to completely eliminate the need for backup gas turbines for renewables, you would need to store enough energy to maintain full grid supply for at least a day, more likely several days.
My concern is energy stored as compressed air could, in principle at least, be released all at once, in the event of a storage system failure.
Imagine you wanted to store one day worth of energy to supply a major city, in case the wind didn’t blow that day – enough energy to maintain a 1 gigawatt supply to the grid.
To maintain a 1Gw supply of energy for one day, your storage solution would need to store;
1Gw x 1 day
= 1000,000,000 W x 86400 seconds
= 86,400,000,000,000 Joules of energy
= 86.4 TJ.
This amount of energy is the same magnitude as the energy released by Little Boy, the nuclear bomb which destroyed Hiroshima (63 TJ). An abrupt release of 84TJ of energy next to a populated area would cause serious damage.
How would such a release of energy manifest? During the Lake Nyos disaster, when 100,000 tons of volcanic CO2 at the bottom of Lake Nyos was abruptly released, the rising gas created a 25m Tsunami which did extensive damage to the thankfully mostly uninhabited shoreline.
In the case of Lake Nyos, the Tsunami damage was secondary compared to the lethal effect of normal air being displaced over a large geographic area, by an asphyxiating cloud of concentrated CO2. But a large Tsunami smashing into a densely populated coastal city, adjacent to the storage facility, could still cause serious loss of life, even if the gas bubble which created the Tsunami was breathable air.
Risk concerns aside, in my opinion Hydrostor’s solution is still a very interesting innovation. Storing energy underwater, utilising the natural pressure of the water, should substantially reduce the cost of creating storage “balloons”, compared to other schemes for using air pressure for energy storage, by dramatically reducing the required strength and potentially the cost of the materials used to construct the pressure containers.
“Electricity is run through a compressor”
The idea of compressing electricity fascinates me but I thing they mean electricity is used to run a compressor.
Words are important.
Yes, I think this is to be used in conjunction with Wind and Solar to maintain constant energy at night and periods of no wind. I’ve also read of a version where H20 is pumped up into a water tower to power the turbines at night. Energy generated in off peak hours pump the water. To me all these “solutions” are interesting 4th grade science projects, but none of them will ever really compete with the unbelievably efficient and environmentally friendly petroleum. Here is the most idiotic solution I’ve seen. GE puts the wind turbines under water. Basically they are automatic whale sushi makers. Imagine the environmental disaster they things would be.
https://youtu.be/Co0qkWRqTdM
The use of water isn’t a 4th grade pipe dream, it is used extensively. A water tower isn’t enough to make it worthwhile, it is typically done with larger reservoirs.
See https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity
or dozens of scholarly articles on the concept.
wind turbines under water. Basically they are automatic whale sushi makers. Imagine the environmental disaster they things would be.”
Not true, do some research then engage brain before operating mouth or fingers.
This is the value of having a sub-editor actually proof
reading such articles, before publication, Is there such
a process at WUWT. Perhaps we shall be told.
Still I think this is some kind of Rube Goldberg machine, isn’t it.
Does it do any useful work, or does it just present a loss to the
system, and cost millions to develop and research to “get it right”.
Add in the obligatory phrase …
“with respect to atmospheric CO2 reduction”
… and Lo, the grant moneis will pour in,
….. You Hope !
The idea is to store energy temporarily in a way that is quickly retrievable, rechargeable without wearing out, low cost etc.
Of course there will always be rather large losses of energy in any such multistep conversion…the laws of thermodynamics ensure that.
Pressure from the combustion of fuel and air is what drives the pistons in an IC engine.
Using compressed air to move a piston is the exact same mechanical process — so yes work will be done.
Sorry, Thum, but ALL mechanical systems have parts that wear out, corrode, or break. Repairs to, & periodic replacement of the whole system would be a large cost.
Better off to use the windmills to pump water from the bottom of hydro dams to the lake at the top.
Cheers
Roger
http://www.thedemiseofchristchurch.com
The only thing windmills are good for is pumping water.
Dessie
Windmills can grind corn, too.
Auto – not prepared to defend their efficiency at corn-grinding . . .
DesertYote.
A friend of mine recently told me of a fellow he met who uses a small windmill to compress air into a tank he then uses to run compressed air tools in his shop. Intermittent use and small scale, but perhaps a good “alternative” for locations away from any “grid”.
Methane and carbon dioxide is naturally released from numerous places on the sea floor anyway so there is no need to pump it down and compress it. Volcanic vents and microbial activity produces it. Sometimes it is released from water depths of over 2 kilometres where it will be under considerable pressure.
Why not funnel these gas streams on the way to the surface and place a turbine in the funnel?
That way there is no need for the storage or wasted energy to compress and for pumping.
Well, this is plainly an energy storage scheme.
When air is compressed the temperature of the air rises, significantly. P1V1 over T1 equals P2V2 over T2. The balloons would lose the energy from the increased temperature, in the first place, and rubber is not free, in the second place. I am not putting my life savings into this concept…
So are you saying that widespread implementation of this concept would warm the oceans? Dang, we can’t win for losing!
The solubility of carbon dioxide in water decreases with increased water temperature, so more carbon dioxide will be released to the atmosphere. A no no.
But it would cool the atmosphere.
“…widespread implementation of this concept would warm the oceans…”
Never mind warming the oceans, widespread implementation of this concept would cause widespread displacement of seawater; causing the rising sealevels to rise even faster. It’s worse than we thought!
/sarc
Menicholas,
“But it would cool the atmosphere.”
That’s what I was thinking . . as in low tech AC/refrigeration . . Could come in pretty handy in a remote hospital situation . .
Lois:
More atmo CO2? A yes-yes!
John, that’s all AC is. Compress a gas, let it cool while maintaining constant pressure, then release the pressure.
I know that when I want to remove energy from a hot object I usually put it in bath of cold water. Oh wait…
And when the compressed air is released, it will cool. If it cool enough, ice may form and befoul the system. Might need an air dryer, which takes energy.
Unless the tubes are insulated, if the air in them cools enough, it will form ice on the surface of these tubes, which will put a lot of upwards pull on the tubes. I hope the tubes are well attached to the bottom.
If you read the proposal they intend to run that hot gas thru a heat recovery device and then when the flow is reversed they plan to recover that heat. I am not familiar with anything that can store heat for long periods but someone suggested a tank filled with bricks (and interstitial spaces for gas flow) would work to some extent.
Heat recovery is very common in power plants, but the transfer occurs in real time and not with stored heat.
I do not believe the efficiency claim either.
The big problem is with the laws of Thermodynamics. When you convert one form of energy (electricity) to another (compressed gas) you ALWAYS lose. Conversion efficiency of 50% is generally considered to be fairly good by engineers. So you convert 4 GW of electricity to compressed gas and you now have 2 GW + 2GW of waste heat, and when you convert that back to electricity by running the gas thru turbines you end up with 1 GW of electricity.
So you’d need four times as many solar panels to run this scheme. It’s a joke, or it’s more likely sucker bait for the technically ignorant investors.
Age, and – Office of Electricity Delivery & Energy Reliability states that the development of technology to store electricity so it’s available on whenever it’s needed
In order to have any to store, you must first have an excess. When has this happened.
And air compression is terribly inefficient.
And just how much electrical energy is required for those air pumps to overcome the water pressure that surrounds those deflated submerged balloons?
Orr are they planning to inflate the balloons first …… and then sinking them underwater?
“And just how much electrical energy is required for those air pumps to overcome the water pressure that surrounds those deflated submerged balloons?”
overcoming the pressure is exactly why and how this system works. otherwise, what’s the purpose of storing it under the ocean in the first place. the deeper you go the less amount of compress air you need to store the same amount of energy. the principle here is similar to a hydro-dam. you are in reality storing energy in the water you are displacing.
Me thinks ya’ll are ignoring a basic scientific fact about water pressure as associated with the depth of the column of water.
How Changing Depth Affects Pressure
http://www.dummies.com/how-to/content/how-changing-depth-affects-pressure.html
When you pump air into that “under water” balloon, …… will it increase in diameter …. or just “squashed” in length and width?
Curious minds would like to know?
What kind of anchors were they planning to use to keep these balloons on the bottom?
You can steal the adiabatic heat of compression (which is what you are describing) to do useful work like heat a working fluid.
You can also use thermal energy captured elsewhere to increase the pressure of the stored air after it is exhausted into an intermediate plenum — thus increasing the pressure and useful work without causing the main pressure vessel to increase in temperature.
Might work in MN others with access to lakes and oceans. Interesting but highly inefficient, seriously doubt their 60-80% efficiency projection.
You’re not the only one William! Compressor losses, thermal losses, head losses going down the feed pipes, head losses coming back up the feed pipes and finally turbine losses.
One of the problems Oregon has had with it “Wave Energy” projects is the Old Man of the North Pacific.
how deep are these placed and how will the infrastructure to run it be made storm proof? let alone the placement of the solar panels in areas where the
sun actually shines? Long way from say, Lakeview
to Coos Bay…(about 240miles) …
when I was young I was really into the idea of renewable energy. I figured out you could run a dessicant HVAC system with almost no energy BUT…then I kind of took a step back at what I’d thought of and realized it was freakishly large. For large static systems, space isn’t a problem…but it really starts to become a problem when you’re talking about storing a month of energy for the US (300 TW for electrical generation alone).
You quickly notice that the cost of the secondary systems are much higher than the costs of some of the energy producing systems…why pay 2 million for a high efficiency system when a low efficiency system along with much higher generating capability is cheaper. The cheapest way I could think of to store energy…was to basically double output and store it at around half efficiency. Basically convert the excess to hydrogen and store it in metal lined, bored out tunnels. Because of the ridiculous costs of inverters and fuel cells…turns out its a lot easier to just make more hydrogen and set fire to it to drive turbines and industrial processes.
Now if you’re being realistic, anti-carbon types should be BEGGING for fracking to cover loads like this, since natural gas is abundant, storable, transferrable, safer than hydrogen, etc. With an energy storage system you need to be able to account for the daily/weekly/monthly/seasonal swings in production. For wind this means you need a ridiculously large storage…like a week to a month. And the wind system would need to be able to refill that system so it would need just a bit more excess production than normal (but not too much). So a 1GW/Day load would require 15-30 GW of storage.
Now if you did the same thing with nuclear, it gets a lot simpler. Because nuclear power’s output is much more reliable, you’re not even storing enough power for a single day, you just need enough storage to cover the difference between average daily production and average daily load (assuming you’re running the reactor at around 90% of max to do that so you have reserves). Even a single day’s worth of energy storage would be sufficient to cover that difference between production and peak load for half a week…and even if the storage system ran dry, they could switch off parts of the grid and meet around 75% of peak load.
Thorium!!
According to a study of ADEME (Agence de l’Environnement et de la Maîtrise de l’Energie), France can go 80% or even 100% renewable with a very small price increase.
Of course, this is only for electricity (which is already mostly carbon free and also clean in France).
Of course, this is assuming an extrapolated price decrease.
Of course, this is assuming the rest of Europe keeps enough fossils to keep French lights on.
It is less funny when you know you have paid for such crap.
I know a great way to store energy. Lets bury trees 2km underground for a million years & turn them into coal & methane.
…This amount of energy is the same magnitude as the energy released by Little Boy, the nuclear bomb which destroyed Hiroshima (63 TJ). An abrupt release of 84TJ of energy next to a populated area would cause serious damage….
ANY method of storing enough energy to operate a modern civilisation is going to have very great potential dangers. This doesn’t seem to figure in green propaganda at all….
+10001
Energy storage is DANGEROUS.
The three safest things are uranium, coal and hydrocarbons, in that order.
Yes I can well believe that,
here is a picture of Uranium.
A man is holding it with just
some rubber gloves on.
It can’t be as dangerous as
some “greenies” would have
us believe, can it ?
Just don’t explode it, or eat it !
I remember an idea that was circulating back in the 80’s. Seems some guy had a bright idea that we could giant gyroscopes in cars, spin them up, and then used the stored energy to drive the car.
Other than the problems with catastrophic failure modes, it wasn’t too bad an idea, so long as you intend to drive only in a straight line.
plenty of gyroscopes in transport
car 1910
monorail train 1909
http://chestofbooks.com/reference/Wonder-Book-Of-Knowledge/images/A-Monorail-Gyroscope-Car.jpg
sorry missed a bit
with 2 contra-rotating gyroscopes there’s no problem with steering
Let’s go back to the idea as to why someone would need to store the energy.
There may well be a number of valid reasons to try to do this in certain places and conditions, but if the reason is solely to try to account for the fact that solar/wind is intermittent and unreliable and grossly more expensive to produce and therefore needs a backup……………
Yes Matthew, just another way to raise the overall cost.
I thought, when I first read the title of the post, they were going to have the balloons physically hooked to cables and geared to a turbine driven by the upward buoyancy, the pressure would be released at the surface, and the airless balloon then sunk and refilled.
Actually, there is a simple need to store power generated off-peak to satisfy subsequent peak demand. When I was a kid there was a serious proposal to create a pumped hydro storage facility at Storm King mountain near Newburgh,NY. The environmentalists killed it. http://harvardforest.fas.harvard.edu/sites/harvardforest.fas.harvard.edu/files/publications/pdfs/Stillman_Issues_1966.pdf
Wind and solar amplify the simple need many times, driving up costs of all power generation.
This idea, like the railway storage method (aresnorthamerica.com), while interesting are not tried and proven like pumped hydro. All are limited by geography. The amount of space required is another issue. Maintenance of the underwater section is another question I have.
Oh boy! Our grandkids can be minimum wage hard hat divers.
safest job in the world, (sarc), & think of the kudos earned by being employed in such a planet friendly career. But could we trust eco-fascist politicians to ensure the workers compensation insurance was adequate?
Interesting, TRM. Anything involving railroads is interesting to me. There would be some technical challenges, but the footprint is small and there are many abandoned lines in the mountains near me that could be used. The pdf for the idea is here:
http://s3.amazonaws.com/siteninja/site-ninja1-com/1406585308/original/PRESS_KIT_ARES_AUGUST2014.pdf
IOW, they are lifting the oceans with air, causing man-made sea level rise. Will someone think of the children I mean, the shores?
What about the sea creature who will bump into the balloon?
What about the danger when a balloon collapses? What about the toxicity of the destroyed balloon?
On a more immediate note, what about the secondhand pollution from whatever these people are consuming?
They could have HUNDREDS of cubic kilometers of balloons and not appreciably raise sea level:
Volume of the oceans 1.37 Billion cubic kilometers
The volume increase needed to raise sea level 1 millimeter is approximately 350 cubic kilometers
Take a sphere 6371.000001km (radius of earth at sea level plus 1 mm) and subtract a sphere of radius 6371 km — you get 510 cubic kilometers — multiply by 70% surface area — 350
“They could have HUNDREDS of cubic kilometers of balloons and not appreciably raise sea level”
Obviously!
I was making with the funny.
Tides, locations issues, connection to the grid, salinity issues and corrosion. It seems a very expensive solution for a very small benefit.
all true, and all perfect to what the Malthusian globalist want.
A similiar system is used at Kinzua reservoir in Pa. They blasted the top off of a mountain, and during the night when they have excess electricity available they pump water out of the lake up the hill into the storage reservoir. During the day, they run the water in reverse through the turbines to create electricity without flooding the down river residents. Is blowing the top off of a mountain worse than destroying the habitat on the bottom of a lake? I dunno.
Ameren Missouri has a similar system which has had more than it’s share of problems and environmental impacts.
http://www.stltoday.com/business/local/more-trouble-for-ameren-missouri-s-taum-sauk-hydroelectric-plant/article_3e850e06-2ce1-11e1-b336-0019bb30f31a.html
Do all these ‘green’ projects enjoy exclusion from environmental impacts?
I believe there is no “green” project (zero, nada, nil) that could survive the kind of scrutiny “greens” direct at non-“green” technologies.
During the sane days of the California water projects this was done at Shaver Lake, in the mountains East of the Central Valley. Think it was built in the ’30s. I’ve been there many times.
n’t the best use of renewables be to run a coal gasification plant … store the gas use it later …
So now they want to litter the ocean floor with giant balloons made out of Hydrocarbons ?? Not to mention it would be highly inefficient !
I have not yet amassed enough sarcasm for this article, but I am working on it.
. . Well,I haven’t got all day ya know !! LOL
There is a large drop in eff. due to heat loss when compressing the air. It is also poor performance in a turbine. It would probably be better to pump water up a hill and then run a turbine as it drains back during off hours. There is no compression loss this way and the increase mass of the fluid through the turbine would result in much higher energy recovery.
After all it’s really just the change in sea level caused by the air bags that’s storing your energy. You alternately can inflate the bags when the tide is low…the recover the higher pressure at high tide. This would provide additional energy over and above what went in. ( you would need a high tidal area to make it most useful)
You can pressurise gaz slowly with huge liquid pistons. No air turbine.
The buoyancy of the balloons would be huge. I can’t see how they could be practically anchored and supported. A very modest 1000 cubic meter balloon (10 meters cubed) would have a lift force of 2,200,000 pounds.
I was actually expecting this article to leverage that fact. I was imagining steel tanks connected via cables to a pulley/generator. You pump air into the tanks to grant them buoyancy and let the lift crank a generator as they rise to the surface over X time (gear ratios, depth, etc, would need calculation and calibration, obviously… maybe not even possible. Just a thought experiment prior to actually doing real engineering. 🙂
The crank could also be spring loaded so that as you start releasing the air at the top, it starts spinning in the opposite direction, generating power on the way back down. once it’s back at rest, you can pump air in again to prime it.
No $ per MWh – my bet is the storage costs are about $1000/MWh, ($1/kWh). So ‘perfect’ for the green energy industrial complex, which seeks to make people freeze in the dark. The limit of what you can charge for electricity is based on the alternatives to the grid, which is about $0.20 / kWh in the US (home based natural gas to electricity). With the grid controlled by politics instead of physics, people/companies simply unplug and make their own, as is happening world wide in places like Germany, California, Ontario, etc.
And what about anchoring really big storage balloons in quite deep water? That’s one gigantic anchor or a major drilling operation into what presumably must be hard rock. I suppose a huge mat or platform with tethering cables could be covered with thousand of tons of sand and rock with dredging equipment but that would be a feat too.
And there’s only about half pound of air pressure gained per foot of depth. For example, 200 feet deep gives roughly 100 pounds per square inch of pressure and that’s not much in industrial terms.
At scale, as the article mentions, there are serious safety concerns in case of failure. At least the balloons are invisible and quiet except for air compressors. These waste energy through Inefficiency and the as far as I know unavoidable heating of the air being compressed.
The utility and practicality of this clever idea remains to be seen.
Storage vessels need not be balloons. Cylinders or domes with open bottoms would work as well. Anchoring might be interesting.
If the bottom of the storage vessel was open, wouldn’t the air dissolve into the water – albeit slowly?
Not enough to matter.
Sly
Anchoring probably will be a problem.
The ‘lift’ – the force trying to ‘un-anchor’ the system is obviously related to the size of the container [balloon, dome, whatever].
Looking at shipping, ships have anchors that hold he end of their anchor chains. It is the hundreds of tonnes [for a big ship] of weight in the chain that – tends to – hold the ship in position.
[except in high winds. I tell my masters to leave anchorages, unless well-sheltered, very early, and make for the open sea. Do not get caught on a lee shore.
Ever.]
One of my ships did that, some years ago, and caused $40,000,000 of damage to a sophisticated, and nearly new, ship. Nobody hurt, fortunately, and no pollution – bunker tanks located protectively.
But $40,000,000 – not chump change . . .
Corrosion – at depth – will not be as big a problem as it is on ships at the surface, where there is heat and moisture. . . .
Saying that, but expert analysis will be needed.
At the surface, on ships, we get the dreaded steel-worm – rust.
Rust eats ships.
Auto
Auto, you said: “Anchoring probably will be a problem.” Personally, I would to change that to: “Anchoring WILL be a problem.” I was docked in Nassau several years ago over Christmas when the (US aircraft carrier) ‘Eisenhower’ came down from Norfolk. They arrived on a Saturday and anchored off Paradise Island for the weekend. The next day the shore patrol came to town to shuffle all the sailors back to the ship. She was dragging anchor! If the US Navy can’t solve the anchoring problem I would be surprised if anyone else has.
Another potential problem is protecting the air bags from marine growth. Unless the technology has changed in the last several years, any decent antifouling coating either contains some rather nasty chemicals or has to be replaced fairly often.
Open bottoms would ensure that the air was saturated with water. Then as the air cooled as it decompresses that water would condense out, blocking the hose to the surface. If the pressure drop was high enough, problems with ice forming would be have to be solved.
Where is 80-90% of energy in the form wasted heat from the compression processes going to be stored? Likewise, how will it be reheated when released? And no mention of the massive air dryers required to prevent the whole system from turning into a giant block of ice (air contains water vapor that would need to be removed).
My thoughts exactly. OTOH, one advantage of the underwater balloon storage is that the pressure is pretty much constant, so it should be possible to have a heat storage unit to absorb that during compression and release during expansion – probably want to make it out of a series of phase change materials to keep the temperatures at each stage more or less constant.
stephana
Pumping WATER uphill, then letting the WATER run back downhill is a long-working solution that does, in fact, work.
BUT!
The premise requires a few things – It needs absolutely that the electric energy to pump the water uphill is available at all (first!), that this energy is not needed someplace else (after all, when a generator has to run to create the electricity to run the turbo-pump backwards for 6 hours, that generator cannot power anything else. Then, the water has to be available – a dry river cannot be pumped uphill. Then, the high-level storage facility (hundreds if not thousands of acres of land as you point out) has to be available at the same location as the river and the excess cheap power.
So, the vast Niagara River hydrostorage “lakes” below the Niagara Falls are near ideal. Water power already available, and those generators NOT needed at night, a river with no drought-reduced flow nor flooding problems. But even then, there was tremendous legal and enviro pressure against even these “little” artificial lakes because one edge of one lake on one side of the river flooded an old Indian burial ground. And both sides of the river (Canadian and New York) needed large excavations and tremendous earth dikes to make the lakes.
Air-fed turbines (to get power out) and air-pressure fans (to pressurize the air and pump it below the water level) are notoriously inefficient – either way – compared to water pumps and water-powered generator turbines.
Basically, I don’t believe their numbers can be matched in practice. I could be proved wrong. But I will NOT believe a sales pitch for government money until they show test results using their own money and their own turbo-pumps into their own balloon under their own lake.
Great, I like it.
Here is another picture of stored solar energy ….
http://ostseis.anl.gov/images/photos/TS-Open_pit_Suncor-600.jpg
Yes that’s true Buster, still there is rather a lot of those oil sands. That picture represents just the Suncor workings at that one site. The whole field is ginormous and though to hold more than all the shale put together. Then there’s coal, gazillions of tons of the stuff, but still it will eventually all run out in a many hundreds or thousands of years perhaps.
But recently we hear from both Russian and US scientists of the discovery of Abiotic Oil and Gas, produced from primary elements, cleaved from Carbonate Rock, and Water molecules under extreme pressures and temperatures, deep in the subduction zones of the Earth’s Crust. Such is the source for those very deep high pressure oil wells now being found below Carboniferous geological layers, it is postulated.
Again the Earth’s core is thought to have immeasurably huge amounts of elemental Carbon, and with Hydrogen from subducted rock strata, we have all the ingredients to naturally and sustainably create oil and gas, ad infinitum. It is claimed that the Deepwater Horizon well which blew out in the Caribbean was one such attempt to access the deep oil and gas. They may have succeeded in tapping the “mother lode”, but they couldn’t control it, and it took five months, to seal the well up permanently again.The Russians have similar deep wells, which they are able to control.
The oil sands may run dry,
and the coal bed be mined out,
but peak oil and gas, perhaps not.
And stored CO2 (not that it matters).
There are two compressed air grid storage facilities. 280MW Germany 1978, 110MW Alabama 1991. Both are solution mined salt caverns, airtight by definition. Much cheaper than submerged balloons.
There are no others even though there are lots of thick salt strata that coild be used, for a simple reason. The round trip efficiency is less than pumped hyro. Turbine and compression heat losses. So Hydrostor is another technically possible but commercially infeasible idea, more expensive than what was already tried and abandoned.
As has been mentioned earlier, this process will produce huge amounts of heat, which will be released to the ocean.
Then, on recovery, there will be a lot of heat absorbed when the compressed air is used back on land.
This seems like a giant scheme to move heat from the atmosphere into the ocean, and heat both up. Remind me again just what fundamental problem we are trying to solve here – ah, yes, the heating of the atmosphere and the ocean…
And sea level rise. Poor Kiribati just can’t win with these green idiots.
Why not use depleted oil and gas wells? A natural gas field on the North Slope of Alaska has pressures of over 20,000 lbs.
You don’t need the power generated up there. Oil reservoirs underground are not really “voids” unlike a full-sized salt cavern (which is a huge single hole in the ground created by years of dissolving salt by water pumped underground, then evaporating the salt out topside into the sunlight. That makes a huge hole tens of thousands of cubic meters in size. A oil field is near-solid rock, with the oil “squeezed” towards the pump suction through very, very tiny individual cracks in the rock by the tons of pressure of the rock thousands fo feet above. Even after pumping out tons of oil, there just isn’t any real “holes” in the rock to fill back with air then release the air back to the turbine. In any event, 70 – 90% of the oil remains below in an economically-empty, ready for later drilling with different techniques, so even after the oil-filled rock is pumped dry, there is little room below.
Thanks so much for using the Hiroshima unit of measure to explain energy requirements in your example.
Conceptualizing a Joule is pretty hard but Mythbusters blowing up a huge truck in the middle of a lake, that I can do.
Makes me think of how wavepower seems a great idea until you see that in practice the sudden turbulence can have so much power that it destroys your wavepower rig.
Wouldn’t you just need to use scale-appropriate construction methods? I mean, I’ve seen the windmills up close, as my brother-in-law works on them. They’re fairly flimsy, and can’t handle side forces very well. For collecting wave power, I’d envision concrete dam-like constructions made to withstand some serious waves.
Underwater balloons sound impractical.
But, if one insists on pursuing an energy storage system, I suggest trying a system of motor-generators that would lift huge weights to store potential energy.
This system would bypass the problems of explosions or flooding.
It would be identical to the system of the weights that run old grandfather clocks.
The weights could run straight up and down in a structure or up the side of a mountain on rails.
However, like windmills, this system has a poor ratio of the amount of raw materials needed to build it, compared to the number of watts generated.
Losses would occur dependent on the efficiency of the motor-generators and in the gearing.
Nuclear energy is the best option for minimal CO2 emissions, if the world insists on CO2 being “the problem”.
I vote to try thorium.
I see now that there is a rail system by ARES in Southern California.
It seems like a great waste of space for little power, like windmills.
I estimate that the most efficient system for gravity storage would be straight up and down.
There are some areas of the western slope of the Sierras where a 10,000′ change in elevation should be practical. A 10,000 ton train would require about 100MWHr to haul up that 10,000 foot hill. Figuring rolling resistance at about 0.2% of weight and a 4% incline should give about 90% mechanical energy recovery. Then assuming 90% electrical/mechanical and mechanical/electrical conversion efficiency will give a round trip efficiency on the order of 70%.
The idea looks OK from a simple technical perspective, but I have severe doubts about the economic practicality.
On a historical perspective, the first run of an electrically auled freight train on the Milwaukee Road’s line over the continental divide resulted in more power being returned on the downhill portion than consumed going uphill (Butte i quite a bit higher in elevation than Three Forks). This run took place in late 1915.
erikemagnuson:
ARES (Tehachapi Train) claims an efficiency of 86%.
This link says “near 80%”.
http://www.aresnorthamerica.com/grid-scale-energy-storage
kbray,
The ARES proposal is basically an electrified railroad and my back of the envelope estimates were based on that. The ARES website claims a bit over 78% round trip efficiency – the 0.9×0.9×0.9 estimate comes out at a bit over 72%, which is a bit closer to 78% than 85%… I’d expect the efficiency to be better than a compressed air storage system with no associated thermal storage.
erikemagnuson,
I agree that the gravity railroad is likely the most efficient storage system, as almost 100% of the stored potential is forced back through the electric motor when it changes direction. The only losses I see are in the motors, generators, and friction.
Hydro pumping would probably be less efficient due to water power transfer losses on the turbine blades and losses in the up-pumping added to the electrical losses in the motors, generators, and friction.
The compressed air storage system has a plethora of losses and for me is a non-starter.
But if these energy storage systems are being pursued to smooth out the power from wind and solar, it’s just “putting lipstick on a pig”.
My neighbor just put up 11 solar panels with less than 3KW output thinking he is going to save the planet.
Trying to run an all electric / zero carbon household on 3KW is not going to work very well. Fortunately he is still tied to the grid.
However to sum up, in my opinion, modern nuclear power is the only practical way as of today to generate enough 24/7 reliable electrical power to satisfy the needs of the planet to run all our machines, heat our homes, and melt our steel, with minimal CO2 production. (and personally I don’t think CO2 is a problem to begin with)
Wind, solar, and energy storage is just “screwing around” trying to get to that “zero carbon” goal.
Pump water storage has good efficiency. Getting very close to 100% round-trip efficiency is NOT the issue here. The issues are cost of building, keeping in shape, risks, peek power, capacity…
The comparison of “efficiency” as energy in at 8:00 energy out at 10:00 is a non issue when it is quite good already.
The issue is efficiency as total energy in vs. total energy out. This includes the energy to build stuff, including part of the energy to build the tools and the energy to raise cattle to feed the people who built the storage system and tools used for raising cattle to feed the people and the energy used to make the energy storage system used to build tools to make a tractor to feed the cattle to feed the worker who built tools used to produce lubricant oil for the train used in the storage system (each in proportion of the production consumed, of course).
“(and personally I don’t think CO2 is a problem to begin with)”
No, but chemically energetic linked carbon geopolitics is.
Pumped Hydro. ≈ 72% round trip Efficiency & uses approx 36% more power to pump the water uphill than it generates running down.
I have intimate knowledge of the Dinorwig pumped storage station ‘Electric Mountain’; The station has six 300MW generators, giving it a total capacity of 1.6GW. for ~7 hrs.
http://www.fhc.co.uk/dinorwig.htm
https://en.wikipedia.org/wiki/Dinorwig_Power_Station
Britain currently has 4 operating major pumped storage schemes –
Total Storage Capacity = 23•279 GWh
Total Generating Capacity = 2•764GW. The UKs total pumped storage can only supply 4•6% of max demand for 6hrs then 0.8% for 4hrs. Full recovery time is approx 17hrs of surplus power. _
You could dam & flood every valley in Britain and not have a days worth of storage…& the construction costs are eye watering.
https://en.wikipedia.org/wiki/Dinorwig_Power_Station
Bovine excrement, as usual from WP.
With link to https://en.wikipedia.org/wiki/Base_load_power_plant which says
Note “used” not “limited to”.
Kbray,
The major source of loss on a typical electric railroad is in the catenary or third rail, though the electrifications are designed for lowest overall cost of providing transportation. A power storage RR would presumably be built to give lowest cost of stored energy.
One other thing came to mind – the ARES proposal is a specialized type of Railroad. I wonder if the folks at ARES have ever been in touch with people experienced with the track and mechanical aspects of keeping a railroad running.
simple-touriste,
I agree that some of these schemes use way too many resources for what they give back.
That’s the problem along with the political component.
saveenergy,
Thanks for the info about Dinorwig.
I’m surprised that it can drain that big reservoir in only 6-7 hours and takes 17 hours to refill.
It seems like a lot of effort and resources for not much return.
It does function as a buffer for the grid, but such a cost.
erikemagnuson,
I understand the third rail losses. Definitely distance related.
I watched some of the ARES animations and the plan looks too complicated with 90 degree rotations of the trains and stacking against each other. Too many mechanical problems with that process. Firm believer in keeping it simple. Agree and hope they have access to real railroad folks with experience.
I wish them good luck with that.
“I understand the third rail losses. Definitely distance related.”
Why not use an efficient 25 kV standard overhead cable?
(Not safe for the idiots trying to still cables, though.)
“I’m surprised that it can drain that big reservoir in only 6-7 hours and takes 17 hours to refill.
It seems like a lot of effort and resources for not much return.”
No, it’s by design.
Some stations in Europe have been modified (at great cost) so that they could be emptied faster. The ability to inject lots of power is valuable. The ability to do it at any time on short notice is even more valuable.
Think of a big nuclear power plant being attacked by
aliensjellyfishes. Or mud. Or oil spill. Or anything. It happens. Rarely, but it does. Then the plant, not one reactor, has to stop. (It may have a back-up lake but it is not intended for normal operation.) Several GW maybe be missing with no prior notice.You want to have a big reserve of backup with the ability to inject power at any time, not for long period. You also have other thermal plants online (possibly including other nuclear plant not at full power) with the ability to power up in less than a few hours.
The cost of these gigantic accumulators with a capacity of few hours at maximum power may be stunning (about as much as nuclear power plant capable for running 10 months per year with a relatively small fuel cost), but it they may still be economically viable.
Diversity is essential: diversity of reliable plants at different places ready to take over.
https://en.wikipedia.org/wiki/Hydraulic_power_network
peter: not hydraulic pressured water,
more like this:
http://www.gravitybattery.info
T*delta S losses alone will make air compression highly inefficient, but the adiabatic heating losses will also cut energy efficiency. I haven’t done the calculations which are straight forward, but this comment from the Bonneville Power Administration essentially says it all:
Compressed air is often called the “fourth utility,” after electricity, natural gas and water. For many businesses, compressed air is a vital input to their production process. However, too often, compressed air systems are highly inefficient, resulting in significant wasted energy (and cost).
• Is compressed air free?
No, compressed air is not free. Although “it’s only air,” compressed air is actually very expensive because only 10 to 20 percent of the electric energy input reaches the point of end-use. The remaining input energy converts to wasted heat or is lost through leakage. For example, to generate 5 CFM it takes 1 HP!
http://webcache.googleusercontent.com/search?q=cache:0vgLbgHaOeUJ:www.bpa.gov/ee/sectors/industrial/documents/ca_2006-3_tipsheetcaefficiencymeasures.doc+&cd=3&hl=en&ct=clnk&gl=us
This is why it would almost always be most efficient to give away surplus energy to subscribers and let them find a way to put the energy to use at the premises/factory. A battery might be charged or water or floor slab heated for instance.
Most mass storage schemes waste significant amounts of energy: in the range of 20-80%, but simple low-tech solutions are available for sinking oversupply in many small increments and would reduce capital outlays for those proposed large low-efficiency schemes.
This is of course exactly the concept used by electric night storage heaters. These are little more than a pile of bricks in a metal case with a fan inside.
Lol, and most industrials know this. The plant I worked in used compressed air to run tools and to blow dust off of our clothes, and to air up tires. For the large machines, electric motors and gasoline were used, lol.