[maybe yes, maybe no ~ctm]
From Quartz
Thanks to the modern electric grid, you have access to electricity whenever you want. But the grid only works when electricity is generated in the same amounts as it is consumed. That said, it’s impossible to get the balance right all the time. So operators make grids more flexible by adding ways to store excess electricity for when production drops or consumption rises.
About 96% of the world’s energy-storage capacity comes in the form of one technology: pumped hydro. Whenever generation exceeds demand, the excess electricity is used to pump water up a dam. When demand exceeds generation, that water is allowed to fall—thanks to gravity—and the potential energy turns turbines to produce electricity.
But pumped-hydro storage requires particular geographies, with access to water and to reservoirs at different altitudes. It’s the reason that about three-quarters of all pumped hydro storage has been built in only 10 countries. The trouble is the world needs to add a lot more energy storage, if we are to continue to add the intermittent solar and wind power necessary to cut our dependence on fossil fuels.
A startup called Energy Vault thinks it has a viable alternative to pumped-hydro: Instead of using water and dams, the startup uses concrete blocks and cranes. It has been operating in stealth mode until today (Aug. 18), when its existence will be announced at Kent Presents, an ideas festival in Connecticut.
Concrete plan
The science underlying Energy Vault’s technology is simple. When you lift something against gravity, you store energy in it. When you later let it fall, you can retrieve that energy. Because concrete is a lot denser than water, lifting a block of concrete requires—and can, therefore, store—a lot more energy than an equal-sized tank of water.
Bill Gross, a long-time US entrepreneur, and Andrea Pedretti, a serial Swiss inventor, developed the Energy Vault system that applies this science. Here’s how it works: A 120-meter (nearly 400-foot) tall, six-armed crane stands in the middle. In the discharged state, concrete cylinders weighing 35 metric tons each are neatly stacked around the crane far below the crane arms. When there is excess solar or wind power, a computer algorithm directs one or more crane arms to locate a concrete block, with the help of a camera attached to the crane arm’s trolley.
Once the crane arm locates and hooks onto a concrete block, a motor starts, powered by the excess electricity on the grid, and lifts the block off the ground. Wind could cause the block to move like a pendulum, but the crane’s trolley is programmed to counter the movement. As a result, it can smoothly lift the block, and then place it on top of another stack of blocks—higher up off the ground.
The system is “fully charged” when the crane has created a tower of concrete blocks around it. The total energy that can be stored in the tower is 20 megawatt-hours (MWh), enough to power 2,000 Swiss homes for a whole day.
When the grid is running low, the motors spring back into action—except now, instead of consuming electricity, the motor is driven in reverse by the gravitational energy, and thus generates electricity.
Read the rest of the story here
Company Website
H/T HotScot
If it is too windy for the wind turbines to operate safely, it is too windy to operate a crane…
I’ve long thought gravity could be used in more creative ways.
This idea is sort of like the gravity light.
https://www.shell.com/energy-and-innovation/make-the-future/turning-gravity-into-light.html?gclid=CjwKCAiA8rnfBRB3EiwAhrhBGk54Wagxgqk0g9vu2medjhYt7nPhPE3mslhiZC-rBqcdMh3-Jh9XbRoCr2EQAvD_BwE&gclsrc=aw.ds
Taken to an extreme scale it could be quite impressive.
Brilliant invention. It uses the idea of material strength and gravity to produce energy. Now if we could only get a non polluting stove and source of energy for those 3 billion people who are forced to cook with dung, wood, charcoal, and other biomass.
My friend in Pahrump, NV, said this:
“There is already a plan in place near Pahrump to pull a train load of boulders up a long slope and then let it coast back downhill to recover the stored energy. If what I have heard is true, the BLM has already granted permission for this project to take place on public land to the southeast of Pahrump.”
Pahrump is about 50 mile from the Ivanpah solar generator.
The Ivanpah solar power facility???
I thought most knowledgeable people were already disgusted with its poor overall efficiency and low capacity factor. [According to Wikipedia, the facility’s overall energy conversion efficiency = energy output / intercepted solar energy = 1,045,967 MW*h/yr / 6,621,720 MW*h/yr = 0.15796 or less than 16 percent.]
Why are they now looking for ways to further make it infeasible (I understand Ivanpah’s electricity cost is more that $0.20/kWh output, but I don’t know if that is an LCOE cost that takes into account the $2.2 BILLION cost of the boondoggle).
“The trouble is the world needs to add a lot more energy storage, if we are to continue to add the intermittent solar and wind power necessary to cut our dependence on fossil fuels.”
Umm, let’s just stop wasting limited resources building and installing less efficient and more expensive power sources.
Taking ugly to a new level.
So a small town of 10,000 homes would require five of these concrete monstrosities, per day.
Before taking into consideration that these ugly monstrosities are forty stories tall and only fulfill one purpose.
Oh!
Great, a concrete trickle charged latent energy source that only works off of excess electricity produced by wind mills and solar sources. Sources that rarely produce more than 25% of their baseplate capacity.
Wonderful!
Forty story tall stacked concrete lincoln logs with giant cranes, surrounded by thousands of desolate acres of land with wind mills and solar arrays crowding out humans and wildlife.
“The total energy that can be stored in the tower is 20 megawatt-hours (MWh), enough to power 2,000 Swiss homes for a whole day”
Apparently the Swiss homes use very little power, like 417W in average. According to worlddata.info it seems to be 788kW per capita on average. So more like 1,000 homes.
Crabby calculations all in all, as one must assume that these storage device probably need to be giant as lakes and cost trillions, as we need months of storage if “wind” is taking over most of the production.
As a child I had these kind of wheat dreams too.
+!!
You’re not thinking fourth dimensionally. They could be forty storey tall apartment blocks filled with climate refugees. Two birds with one stone.
Come, come, fellows. This whole thread is a joke, is it not?
Off by a factor of 10. Your town will need 50 of these monstrosities.
Huh?
5 x 2000 = 10,000.
Such tower is enough for roughly 220 houses, not 2000.
Extra idea, free.
Have a small reservoir of water nearby. Build a tank around the concrete blocks. Fill it with water so when the blocks are down, so they are buoyant and easier to lift while some parts of them are still under water. Empty the tank before the cycle when the weights come down. Adds another control mechanism because you can pump and recover energy from the water system like it is a mini hydro system for short term fast response load following. This is knee jerk inventing, so be kind. Geoff.
Geoff,
Are you saying your free idea was “knee jerk inventing”, or that the stack of blocks idea was “knee jerk inventing”?
SR
The free idea was, in the way of “Never give a sucker and even break”, though the basic concrete block proposal is trivial and insignificant when compared to larger concepts like “Why do so many greens oppose nuclear powered electricity while promoting windmills?” or “Why is there an innate impulse that drives people to align with the stupidity of the green movement?” Geoff
Concrete (Portland cement) production is just behind fossil fuel in anthropogenic CO2 emissions.
So sure, let make a many megatonnes of new concrete blocks to SaveThePlanet.
We can use steel instead. Also produces oodles of CO2 being manufactured. Come to think of it, all that concrete has got to be reinforced. With steel rods. And those cranes must be built of pretty fancy steel.
So how much solar and wind energy is really used and how much is wasted? We don’t know. All we do is quote peaks but we don’t know how much is actually used because we can’t toggle between fossil fuel and renewable generated sources efficiently enough to measure. No? I see this as a viable solution for niche applications and has advantages over current batteries. The low tech simplicity and cost makes it ideal for third world applications where 24X7 availability isn’t an issue. Bury some of it and put a building over the top and you help mitigate the weather and earthquake issues. Local materials could be used for the dead weight. Unfortunately I don’t see anyone caring about providing electricity to those that don’t have it.
Oh come on, seriously?
Concrete has a density of about 150 lbs per cubic foot and water is about 62 lbs per cubic foot. So the rhetoric about concrete being able to store so much more energy is really only about 2.5 to 1. Take a look at the scale of pumped hydro and you’ll suddenly realize that even with a 2.5 to 1 density advantage, this system still needs an AWFUL lot of concrete in an AWFUL lot of towers to get to grid scale.
There’s a second claim in the article, which is that there are only 10 countries that have built pumped hydro storage. I haven’t fact checked that, but it is most likely one of those things that is technically accurate and totally misleading. Every hydro electric dam is also a hydro storage facility without pumping. In a grid with multiple sources, the flow rate from the dam is ratcheted down when other sources are over producing, and the water backs up behind the dam for use later. No loss from pumping the water uphill because you simply didn’t let it down hill in the first place. When other sources under produce, the hydro dam is simply ratcheted back up to fill the gap.
Novel idea, kudos to them for that. But a stunning leap in energy storage it isn’t, and doubtful that it will be economical.
Hey I know! Blocks of gold! 1200 lbs per cubic foot, now we’re getting a decent density advantage, nearly 200 to 1! Plus we have lots that costs nothing to get. We just stop storing it as bricks in Fort Knox and instead store the same bricks in one of these contraptions.
There may be a security risk I haven’t quite figured out yet….
sigh. 20 to 1. Effing fat fingers.
Hi David – getting close.
https://inhabitat.com/startup-is-turning-old-mine-shafts-into-power-generators-using-giant-weights
In South Africa we have been extracting gold from 4 km deep shafts – after refining the gold we could just lower it back down the shafts to where it came from and generate oodles of lovely gold plated power. Security would be OK too,
Beat of all the infrastructure is already in place.
cheers edi
The solution to an expensive inefficient environmentally destructive unreliable ‘renewable’ energy generator is to add an expensive inefficient environmentally destructive ‘storage’ system?
Yup. Sounds like a plan.
If the solar and wind guys had been paid on the basis of Firm on demand power when required they would have figured this minor problem out by now. Concrete blocks, hydraulic accumalators or flywheels…this isn’t rocket science either. And wasting precious state of the art batteries for grid storage is really stupid, not to mention expensive and wasteful.
Unfortunately, the market got saturated with subsidies and priority access to the grid with solar and wind. Because these types of renewables are low density and non reliable, these means the dams are spilling water as they have to ramp up and down, or the coal/gas baseload gets shuffled off to the spot market at next to worthless rates. That was a fundamental error that rewarded all non firm renewables with firm prices and grid access while making baseload pay the price. Should be the other way around, without any subsidy. Necessity is the mother of invention.
So who wants a bunch of these 400′ towers scattered around the city? One for every 2,000 homes? How ugly would that be? Even though they are made out of concrete they can’t be cheap to build! Creative idea but just plain ugly. Who wants one of those in their neighborhood?
Call it art and all the wannabe snobberies will clamor to have one!!!
Well we can come up with all sorts of storage ideas. How about hydrolyzing water and storing the hydrogen on a high peak. Recombine with oxygen in fuel cells and let the resulting water flow down hill through a turbine. You get a three for: heat to drive a turbine, water to drive a turbine and electricity from the fuel cells. Yes, I’m just pulling this out of my … you know.
I’m not any kind of boffin like you lot, but work in a power station and am interested in the subjects raised on this site. Bear, I can’t find fault with “hydrolyzing water” theory. As you say, split the water when there is over generation and use the hydrogen as fuel.
The fault is the same for all storage methods: Inefficient thermodynamics, scalability, cost to build and maintain…
You know me, I’ve done too many engineering projects to not run at least some back-of-the-envelope calculations. The problem that I see is friction at the pulleys.
Each pulley in such a system adds about 10% to the force otherwise needed. Now, these blocks weigh 35 tonnes, so you’re gonna need maybe 5 pulleys at the top sheave and 5 pulleys at the hook end.
The total force required to use the pulley system is 1.1 per pulley, raised to the tenth power, or about three times the force required in a friction-free situation.
Next, you have the inefficiencies in the winch and transmission. Each of those is on the order of 95% efficient on a good day, combined maybe 90%. So it looks like it will take on the order of four times the force to lift the block up. That’s 25% efficiency.
Now, we could reduce that by using heavier wire rope … but then the energy needed to bend the wire rope at the pulleys goes way up.
So … let’s be generous and figure we can lift the blocks at 50% efficiency. However, that’s not the end. The pulleys sap energy on the way down just as they do on the way up. If it’s 50% to lift it, it will be on that order of magnitude when it goes down … so throughput efficiency is likely on the order of 25%.
Now, are those numbers solid? By no means. It’s a back-of-the-envelope calculation designed to see where a problem might lie. But I’ve doubled the one-way calculated efficiency to allow for that in part. If the one-way efficiency actually is 25%, overall throughput efficiency will be much lower.
In any case, these numbers indicate that there MAY be a real problem with the efficiency of the system.
Finally, what do they claim the efficiency of the system is?
90 percent!
90% … gotta tell you, I’m not buying that for a minute. The motor/generator plus the transmission alone would make the throughput efficiency much less than that. It’s very unlikely that the motor/transmission/winch combo has greater than 90% efficiency. If you have that going both in and out, which you would, that would give a total throughput efficiency of 82% … and that’s with frictionless pulleys and friction-free wire rope …
Regards to all on a smoky, smoky day. Carr fire smoke still covers central California.
w.
Willis,
Excellent treatise. I mentioned motor and pulley efficiencies, but with no napkin to hand. Accepting at face value your dismal figures for the weight system: Knowing that pumped water systems are currently in use, what do you reckon is the efficiency of that approach? Obviously the turbine generators have been developed for along time in hydroelectric dams, which as we know provide significant cheap power in good locations. But it seems to me pumping water uphill must incur some major losses.
While pumped hydro can have an efficiency as high as 70%-75%, I think you are probably right about the inefficiency of the pulley sheaves in this proposed contraption. They may even get too hot to work proper due to all the heat being generated in the friction. If it is that inefficient, even say 50% round trip, that is a lot of thermal heat being created in the sheave/rope/transmission losses both ways full time. The motor/generator will have its own losses, at best 91%-92% overall efficiencies for that, also both ways so there is at least 20% off the top in a super efficient motor/generation system and electrical wire/transformers that we already have. If you can’t get a total 70%-75% round trip efficiency, it probably isn’t worth doing.
Since this is a thought exercise now, and fun to think about, perhaps floating hollow concrete blocks up a narrow pipe in a pumped water column could kill a few birds with one stone, in that a buoyant cement block gets a lift up for fairly efficient inputs just pumping water in and after buoyant displacement for lifting the concrete blocks, that water power is recaptured, but now you have the heavy concrete block at the top of the tower. Then the concrete block can be utilized in a reverse hydraulic gravity pump/generator the same way, and cool the hydraulic oil. Just thinking of how a canal lock works at the Panama Canal is really staggering how much dead weight of a massive loaded ship can be lifted with ease. Of course, they are utilizing a higher head water to work both ways, so is ‘free’ in that sense, although I wonder if there is still something here that improve efficiencies with these concrete blocks up to 75% efficiency, if we just tinker and modify things around a bit? There is no free lunch, but maybe some dessert. Doesn’t hurt to think…
Willis, I think I figured this one out, we build Eco-friendly cable-car systems on the tops of all significant mountains (especially volcanoes … they are potential energy ‘renewables’) and get useless unemployed greenies to fill the cars with rocks, then release the car under gravity to let a cable turn a pulley attached to a generator.
Presto!
Perhaps if they use a synthetic line something like a PowerPro that fishermen use for salmon, most of the bending and unbending inefficiencies go away? That Power pro is petty strong stuff, and very supple, it must be a close to as strong as steel. For regular crane hoisting, efficiencies don’t really matter and steel is the way to go, but maybe where efficiency counts they’ll use something else.
Spectra or Dyneema are the names of this material. Claims to be many times stronger than steel. Its is expensive.
Scotty, that might help … but I don’t think it will make the problem go away. What I’d like to see but haven’t found is anything resembling an engineering-level study of the actual efficiency. They claim 90% round-trip efficiency, but I’m not seeing how that is even remotely possible. That would imply that the entire motor/transmission/winch/cable/pulley efficiency is sqrt(0.9) = 0.95, and that’s not happening.
w.
Willis, I find your efficiency figures to be startling. I have no idea if they’re right. I find it hard to believe that anyone making a serious proposal like this and claiming to be expirimenting on it would be unaware of frictional losses. They did give an estimate. I would assume it included things like this. But I suppose stranger things have happened (e.g. hockey stick).
Thanks, Canman. I found their efficiency figures to be startling. They claim net 90%. For that to be true, they’d have to achieve 95% storing the energy and 95% releasing it.
However, I don’t believe that just the motor-generator / transmission / winch part of the system can achieve a 95% efficiency. To do that, each of the three parts would have to achieve 98% efficiency … not happening. And that is NOT including the frictional losses in the flexing of the cable and the turning of the pulleys …
Real-world large electric motors are at around 92% efficiency.
Winches have three types of gears—worm, spur, and planetary. The most efficient are spur gears, at about 75% transfer efficiency (transmission plus winch). See here for details.
That gives a total efficiency for the two of 70%. HOWEVER, that’s 30% loss going in and 30% loss going out. This gives a combined efficiency of about 50% …
Now, if you went to ultra-high efficiency motors and gears you might get 80% for the combined system, which would give you 80% * 80% = 64% for the combined system … not including cable and pulley losses.
So I have no clue where their claim of 90% efficiency comes from.
My best to you,
w.
I remember a Popular Mechanics article back in the day when I was young (pre-teen — 50 years ago) and my father read it avidly. It suggested a huge flywheel be installed under the house to capture wind power. When needed the motor that powered the flywheel would draw energy from it, reversing the generating process. I never saw that implemented either.
It has been done. There are flywheel energy storage systems. As a matter of fact every electrical grid is a huge flywheel storage system. The rotating masses of the turbines and generators are crucial for system stability since it buys time to take action when there is a failure, or at least time to limit a failure to a part of the grid.
This was what actually caused the system-wide failure in South Australia. Wind turbines have asynchronous generators because they are cheaper, but this means that their rotating mass is useless. So when there was too much wind power and too little conventional power in the grid there was no longer enough rotating mass (=time) to do anything when there was a largish point failure and the whole system went down.
Sounds like someone has been playing Minecraft a little too much.
Bruce of Newcastle
Tetris.
‘The trouble is the world needs to add a lot more energy storage, if we are to continue to add the intermittent solar and wind power necessary to cut our dependence on fossil fuels.’
Wut? Storage does NOT fix wind/solar intermittency. Storage is a fake solution; it solves nothing.
It doesn’t have to be a tower of blocks, it could be a hole in the ground, any hole in the ground will do, for example a vertical shaft. -The dreadfully nasty deep mining coal industry has lots of relevant experience in this regard.
A hole in the ground solves the wind problem and the visual intrusion, but now we may have problems with ground water ingress.
OK, It doesn’t have to be solid concrete blocks (like the gold idea, but lead works too) into a hole in the ground, it could be a compressible fluid into a deep high pressure reservoir. A gas with a phase change to liquid under pressure would be good. – That dreadful nasty oil industry has lots of relevant experience in this regard.
Is it 1st April already?
I have read about using compressed gas as an energy storage device.
What about instead of storing excess energy what about using it productively to say melt aluminum when energy demand is low and shutting down the plant when energy supplies are low.
Plants could easily be designed to take advantage of differing production rates.
“Plants could easily be designed to take advantage of differing production rates.”
I suppose that is the reason plants take such extensive precautions to ensure an uninterrupted power supply.
Generally speaking process industries handling large volumes of very hot substances (steel, aluminum, glass) do not take kindly to power interruptions. The most extreme case is a float glass factory which in practice has to be completely rebuilt after a power failure.
How about a fast breeder react….
Never mind..
It looks like it would be more practical and usable in a lot more locations than the ARES giant domino and rail system:
This is essentially a gravity-battery. I admit its a cute idea, but I can now envisage more poor home state of Texas covered in these monstrosities as well as those wind farms up on the hills. Its one thing to build a wind farm over a corn field, and quite another to ruin beautiful rugged landscape. But I can see another use for these cement blocks…they can program the computers to cover up all the dead eagles and bats the wind farms are leaving about.
I think I will keep my bet on coming up with better chemical battery storage over this idea. There is just too much to go wrong…think way one of our 200″ MPH tornadoes could do to all these loose blocks… (You don’t believe me, go watch some you-tubes of cars and trucks flying about some of the big tornadoes).
Speaking of gravity-battery storage…there are a lot more locations for hydro than you might imagine, assuming costs are no object (so let’s call it green and costs don’t matter anymore). You just need to build a large sea-water storage area in an estuary, let the tides partially fill it and use “excess power” to pour more sea water into it. Then, when tides are lower you can let the water out through turbines. Yeah, lots of problems, but it would work near almost any coast…until the hurricane hits at least.
Hey! I know, let’s build nuclear power plants that run all the time and don’t have these issues… They can be hardened against hurricanes and tornadoes, and they don’t kill all the birds or bats either. OK, silly idea.
yeah, I HATE what they’ve done to Texas… other places too, but I live in Texas and it’s horrible. In 20 years they’ll have big contracts to take them all down because a younger generation of kids will have grown up to detest the sight of the folly of the Government-subsidy farms.
Robert of Texas
I think some con man in Wales attempted something like this. I understand the British government eventually threw the idea out.
Hopefully this scheme has been proto-typed. Concrete blocks have alot of friction and are not easy to move around. If they have prototyped this and upscaled it in tests then the data should speak for itself. Otherwise it sounds like a pipe dream… just an experienced EE speaking.
This system can be easily compared to pumped hydro storage, which is currently the most economical form of energy storage. The amounts of energy storage are proportional to the density of the material and how high it is lifted.
One little realized aspect of hydro storage is the astounding amounts of water that are used. Take Hoover Dam, which has a hydrolic head of almost 200 meters (about 600 feet — perhaps a third higher than a 40 story building). How much water do you have to lift that 200 meters to run a 100 watt lightbulb for an hour? I come up with about 180 kg or 50 gallons. That makes 500 gallons per kilowatt hour.
Now cement is about three times as dense as water and iron about 8 times as dense — well within an order of magnitude. Of course you can increase energy stored by increasing lift height. By any measure, you’re talking huge amounts of material.
You are very close at 100 watts theocratically where gravity is 9.81 before all losses. (98.1 watts)
So a teeny bit less = 69 watts net (after losses) for 180 L water dropping 200 M over an hour x Water to Wire (WTW) efficiency.
180 Kg/litre /3600 seconds/hour=.05 Liter per sec Flow x Head x 6.9 WTW losses
.0005 lps x 200 M x 6.9 (all losses in WTW). =69 watts per hour Net
But I suspect you forgot the losses, so almost exact in theory: a bit less at 69 watts in practise for 180 Kg of water falling 200 M over an hour with losses.
” theocratically”
Dang, I knew this was a religion.
Dang autocorrect…this fancy new Apple MacBook Pro…I wish it could read my mind, and is so handy 99% of the time. It even still looks real close re-reading after you point it out. Nah, gravity isn’t a religion..lol at least for most of us.
While searching for the ARES system on YouTube, I ran across this offbeat similar system:
Since when does a “wind Farm” produce “extra” energy ?