Gravity Storage Keeps Inspiring New Tech

November 21, 2018

On viewing the above, one reaction is, could this be the core of a downtown skyscraper with offices, condos and shops surrounding?

Greentechmedia:

The energy storage industry is all about incremental improvements, so it’s rare to see a product come to market that does something radically different.

That happened last week when the stealthy Swiss/Southern Californian startup Energy Vault went public with an unusually creative grid storage concept. It devised a six-armed crane that stacks concrete blocks with cheap and abundant grid power, and drops them down to retrieve electricity when needed.

The company pitches this as a durable, trustworthy solution for the thorny problem of storing electricity for long periods of time.

The lithium-ion batteries that account for almost all of new grid storage deployments make economic sense for 4-hour duration, even 6-hour, but they get too expensive for super-long durations. Meanwhile, longer-term storage is getting more valuable as cheap but intermittent wind and solar power continue their rise on the grid.

That mismatch has inspired a cohort of lithium-ion challengers taking aim at the dominant technology’s safety concerns, degradation and duration limitations. So far, this wing of the industry has numerous bankruptcies to show for its labor, with a few survivors that could prove durable.

Energy Vault dispensed with the lengthy lab research required to commercialize new battery tech and drew inspiration instead from the granddaddy of grid storage, pumped hydro.

The shifting of water between higher and lower reservoirs still delivers the vast majority of global grid storage capacity. The problem, at least in the U.S., is that the Bureau of Reclamation and the Army Corps of Engineers have already dammed all the most auspicious sites, and modern regulations to prevent environmental devastation make new siting difficult, if not impossible.

Gravity has many uses, though. Energy Vault elevates giant bricks that eventually come down, releasing potential energy to the grid.

The concept is simple enough, although it depends on intellectual property in materials science, physics and software. The outcome, if it works as described, would be significant.

The system operates at about 90 percent efficiency, and delivers long-duration storage at half the prevailing price on the market today, said CEO and co-founder Robert Piconi.

“We are bringing something to market that, for the first time, will produce baseload power below the cost of fossil fuels, and not just for six hours a day,” Piconi told GTM in an interview. “We’re in a position to accelerate the pace at which the world is going to be able to deploy renewables.”

To do so, Energy Vault must succeed where several mechanical storage startups, with their own takes on seemingly simple technological solutions, have failed.

A full-scale Energy Vault plant, called an Evie, would look like a 35-story crane with six arms, surrounded by thousands of manmade concrete bricks, weighing 35 metric tons each.

That version doesn’t exist yet; the company has only built a demo unit at one-seventh scale, completed in June in Switzerland. The demo is used for testing to hone the design.

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18 Responses to “Gravity Storage Keeps Inspiring New Tech”

    • dumboldguy Says:

      Yes, Chucky—-since PHES has been around for over a century and water (salty or not) for even longer, we’ve heard about it.

  1. dumboldguy Says:

    “…could this be the core of a downtown skyscraper with offices, condos and shops surrounding?”

    Sure could, but maybe not in earthquake country, where 35-ton blocks falling off the high “shelves” would do more damage than cans of soup in a supermarket. And maybe not if the lifting cables ever failed—-news last night was full of the elevator whose cable snapped and dropped a car with 6 people 84 stories before the brakes took hold—-the stored energy in a 35-ton block falling would wipe out a few condos and coffee shops?

    And has anyone given thought to how much CO2 is released during the manufacture of concrete for the blocks? Or that we are still burning coal and fossil fuels to produce much of the electricity that would be stored?

    • rhymeswithgoalie Says:

      It doesn’t have to be concrete blocks, of course. And the whole point of having even inefficient kinetic energy storage is to take advantage of the oversupply parts of the wind generation or the solar duck curve.

      • dumboldguy Says:

        Maybe that’s how we can get rid of those recyclables that China is no longer taking. Compress them into huge cubes and use them in this gravitational Solar Roadway-like farce. When does the stock go on sale?

    • grindupbaker Says:

      On a point regarding fake news “elevator cable snapped and dropped a car with 6 people 84 stories before the brakes took hold” as described is physically impossible because gravity acceleration would overwhelm the service brake, the auxiliary brake and the safeties so it wouldn’t stop until the pit which would kill all occupants, they’d have fallen 95 floors or whatever it was. If a suspension rope failed and the elevator then descended without making its scheduled stops, perhaps faster than its rated speed then it could reach 115% of its correct speed + 1 fps before “the brakes took hold” as you put it. That’s a rare and significant event, happened in Calgary ~8 years ago.

      So, “dropped a car 84 stories” is complete rubbish and I’ve seen a lot of this in the media last few years, though you bunch and Greenman haven’t noticed this “fake news” stuff. I’ve dubbed this phenomenon “fake news”. Watch out for it.

      • dumboldguy Says:

        Fail to see what’s so “fake” about something that DID happen, and scared some people to death. Perhaps the details were a bit off in the quick (read “sensational”) reports that the MSM often gives—-it appears that it was not in total free-fall, only some cables snapped, etc. So what? You’re a big #’s guy—-what would be the “explosive power” in tons of TNT for a 35 ton block of “rubbish” falling from 35 stories up?

        And got a link for the Calgary incident? Can’t locate it.

        https://www.washingtonpost.com/nation/2018/11/19/i-believed-we-were-going-die-an-elevator-chicago-skyscraper-fell-floors-requiring-dramatic-rescue-six-people/?utm_term=.2bb5a85dd648

        https://6abc.com/6-people-rescued-after-falling-84-floors-in-chicago-elevator/4724008/

        • grindupbaker Says:

          This is important dumboldguy, not semantics like you incorrectly assume. You’re having a dyslexic moment but it’ll pass. I pointed out rather clearly that fake news is everywhere and the thoughtful, the impartial, need to keep their brain honed and always to be challenging what’s presented as facts (do you spot the relevance to climate science ?) so you responded by pointing me to the same lie another couple of times and informing me that those massive misrepresentations are “the details were a bit off”. The direct correlation to tactics of the coal/oil shills is thick in the air.

          It isn’t necessary that fake news be utterly brain dead like that of the coal/oil shills and much of Donald Trump’s imbecilic stuff. Earth’s ecosphere really has been much warmer than at present and innumerable other irrelevant prevarications.

          “an-elevator-chicago-skyscraper-fell-floors” – lie
          “6-people-rescued-after-falling-84-floors-in-chicago-elevator” – lie

          The point I was making was entirely about the blatant fake news aspect of the incident you described, not the incident itself (the occupants should receive generous but fair monetary compensation for any injuries or stress-related issues). No Calgary detail available, I deleted all company files from my computer when I retired January, company policy. I don’t recall whether the car was occupied, if not there’ll be no news story and the AEDARSA Alberta Web site is the only place that might have it, but it’s old. I’m unfamiliar with their site (I was in Toronto then Vancouver). Well the Calgary incident is not at https://www.aedarsa.com/el_am_rope/elevating-devices/. Enough time on that, back to pretend debate with the coal/oil shill-fuckwits (and now, massively-annoyingly, distractingly and time-wastingly, pretend debate also with the tin-foil-hat nutters and their bull shit +8.7 degrees GMST in 7 years or +4.7 degrees GMST in “I suppose 10 to 20 years”).

          • dumboldguy Says:

            Has GupB overdosed on the fumes while sniffing his perfumed sleeve hanky? Is his Demented Rooster suit too tight around the collar and interfering with the blood flow to his brain? Is that why he is demonstrating some OCD here and going off on the topic of fake news while we’re trying to discuss gravity storage?

            This is IMPORTANT? Really? And how can I be “incorrect” when GupB is the one who is going into semantics, not me—-I was merely making a small aside about reports of elevator cars falling down elevator shafts, with the real emphasis on 35 ton blocks of concrete doing the same. I know what point you were making about “fake news”, but how can you label the news reports “lies”?

            If anyone is” incorrect” here, it’s GupB meandering off into saying I’m having a dyslexic moment—he really doesn’t know what he’s talking about—can you give some evidence for that opinion, GupB? What dyslexic symptoms did I display in my comment?

            To complete his strange rant, GupB says “I’ve seen a lot of this in the media last few years, though you bunch and Greenman haven’t noticed this “fake news” stuff. I’ve dubbed this phenomenon “fake news”. Watch out for it”. Is he really serious? Does he actually think that Greenman, myself, and any Crockers with IQ’s over 100 do NOT know about “fake news”? Or that he is the one who named it?.

            (And speaking of fake news, did Calgary ever happen? Are YOU guilty of spreading fake news?)

            No Calgary detail available, I deleted all company files from my computer when I retired January, company policy. I don’t recall whether the car was occupied, if not there’ll be no news story and the AEDARSA Alberta Web site is the only place that might have it, but it’s old. I’m unfamiliar with their site (I was in Toronto then Vancouver). Well the Calgary incident is not at https://www.aedarsa.com/el_am_rope/elevating-devices/. Enough time on that, back to pretend debate with the coal/oil shill-fuckwits (and now, massively-annoyingly, distractingly and time-wastingly, pretend debate also with the tin-foil-hat nutters and their bull shit +8.7 degrees GMST in 7 years or +4.7 degrees GMST in “I suppose 10 to 20 years”).

  2. Earl Mardle Says:

    The bottom half/third/quarter would be progressively less effective so presumably the stack would not ever be fully unloaded and I wonder at what point the inefficiency would outweigh the value of the recovered energy. I can also see some fairly massive wear and tear on the cables.

    • grindupbaker Says:

      Wear on the steel wire rope would not likely be an important factor because it’s winding drum rather than traction. Elevators with ropes use traction which means that the rope is intentionally crushed by the sheave or is pulled hard between 2 sheaves. For the crushing method it’s usually a U-groove with an undercut that pinches the rope, else the rope would just slip on the sheave and not move when the sheave turned. The non-crushing method has the ropes double-wrapped with an idling sheave to increase the arc of traction. This method is less wearing. Elevator wire ropes lasted 20 – 50 years but it seems to me that “they just don’t make them like they did”, it’s all getting lighter and more disposable. Anyway, 20 – 50 years for traction and a winding drum machine (like this concrete block effort) would not need friction for traction so the only wear would be that the outer rope radius on the sheave is larger than the inner rope radius so on each sheave travel the outer strands are stretched and the inner strands are compressed. I don’t have statistics for winding drum machines like the concrete block effort because they aren’t at all common because not permitted for passengers, only freight and most of those by far are hydraulic. I never inspected any cranes but those professionals would know. I would be surprised if crane wire ropes had a life span <50 years unless they bash or twist the ropes a lot, so I'm thinking 40-100 years depending on whether they buy Bethlehem Steel or some Chinese effort to lower the battery cost. I think legal costs fighting spurious lawsuits from dumboldguy who keeps standing under them and then sues because he gets headaches and loss of appetite would be their biggest battery cost.

  3. rsmurf Says:

    Glad he is spending his money on this stuff. But I still don’t trust him since the time he was in court and they asked him how many copies of his windows software he sold, and he said they didn’t keep track of that!

  4. Keith McClary Says:

    I would like to see that working in a gusty wind. How would they lower the hooks so precisely (and on both sides at once)?

    • Brent Jensen-Schmidt Says:

      Just moving those very heavy blocks in and out would make them pendulums, which would swing for a ‘long’ time. Cute idea with the odd problem.

  5. rhymeswithgoalie Says:

    The take-home shouldn’t be this particular design, but the classic fast and expensive in front of the big and slow, like retail space backed up by a big warehouse or fast RAM backed up by a slow disk drive, or human-access cash tills backed up by a vault.

  6. grindupbaker Says:

    I’m not convinced that this complex scheme is warranted rather than the traditional method of simply pumping water up hill and running it down again, just to halve the footprint by using a solid that’s 2.4x as heavy as water. I’m with the poetrywithgoalie except that video obviously doesn’t have that take-home because it’s an advert. It’s off-peak and on-generation energy storage and densification, which will be required.

  7. Canman Says:

    This storage system can actually be easily be compared to pumped hydro (as far as potential energy due to gravity is concerned).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). How much water do you have to lift that 200 meters to run a 100 watt light bulb 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.

    And, … if that’s not enough, I’ve just run across a subthread by jack of all trades, Willis Eschenbach, concerning frictional losses in the cranes. If he’s right, the whole system is completely impractical at 25% to 30% efficiency:

    https://wattsupwiththat.com/2018/11/16/stacking-concrete-blocks-is-a-surprisingly-efficient-way-to-store-energy/#comment-2520748

    • grindupbaker Says:

      Yep. A person not into calculations has an idea of the magnitude of heat energy versus potential energy if they ever drove a motor vehicle. You apply the brakes to stop while barreling down a hill and the energy goes into heating the brake/wheel assembly. Rarely do they get hot enough to smell burning except on very long steep hills. Massive trucks not using the Jake brake do the same on down hills and the heat doesn’t even melt the asphalt so not much heat energy from a massive amount of potential energy, just as you calculated (correctly for the 100 watt light bulb for an hour with 100% turbine efficiency).


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