34 ms·

Europe's deepest mine to become giant gravity battery

137 points by dithered_djinn 3y ago

hn_throwaway_99 3y ago
I admit in the past I've been skeptical about the use of gravity batteries when they involved things like towers and stacking large weights as their energy density is relatively quite low, but this seems like it makes a ton of sense. That is: 1. The shaft is already dug, so no need to build a tower. 2. As the article points out, many/most of these sites are already well-connected to the grid. 3. Also as pointed out in the article, this could be a boon to depressed areas and help broaden economic value generation. Am I missing something?
- WalterBright 3y ago
  A gravity battery doesn't need a well or a tower. The slope of a hill will do. More or less put railroad tracks up the slope, and have the "car" winched up and down. Just like the ratcheting trolleys that go up and down hills.
  - checker 3y ago
    | Just like the ratcheting trolleys that go up and down hills. https://en.wikipedia.org/wiki/Funicular https://en.wikipedia.org/wiki/Funicular
  - stubish 3y ago
    There was recently an article here about an electric truck that never needs charging. It drives up a hill, collects a load of rock from the mine there, and by the time it has driven back down with the heavy load, regenerative breaking has recharged the battery.
    - bnegreve 3y ago
      Soon we will be hearing of the global flattening.
    - WalterBright 3y ago
      While that makes perfect sense, I have read journalists claiming that Teslas were 110% efficient because of regenerative braking.
      - stubish 3y ago
        A pile of rocks on a hill is a renewable energy source if you are prepared to wait a few billion years for plate tectonics to recharge it.
    - ryukoposting 3y ago
      Would you happen to have a link?
      - roelschroeven 3y ago
        "This massive 45-ton electric dump truck never uses more energy than it generates on its own — here's how that works" https://www.businessinsider.com/edumper-121-ton-electric-dump-truck-2019-8?international=true&r=US&IR=T https://www.businessinsider.com/edumper-121-ton-electric-dum... (You can find more articles if you search for "eDumper")
- deleted 3y ago
  [deleted]
barbegal 3y ago
This must be orders of magnitude more expensive than pumped hydro and I would expect more expensive than lithium batteries. And unless the mine is close to an existing high voltage substation then there will be significant costs hooking it up to the grid. The pilot will be a 2MW generator but you can fit a 2MW inverter and a 2MWh battery into a single shipping container so the scale is really minimal.
- standardUser 3y ago
  > The IIASA analysts noted that mines already have the basic infrastructure for such an endeavour, while also being connected to the power grid. “This significantly reduces the cost and facilities for the implementation of Underground Gravity Energy Storage (UGES) plants,” the study noted. Not that your wholly unsupported naysaying isn't compelling.
  - barbegal 3y ago
    Connected to the grid yes but usually the interconnect is simply enough for running the mine not enough to cover many megawatts of storage capability. The battery storage companies have found that there is an abundance of fields and brownfield sites close to existing substations to place their batteries where the cost of connecting to the grid is minimal.
    - jcrawfordor 3y ago
      The hoist at this mine is 2.5MW, there's typically some ore processing on site, mines end up requiring a lot of ventilation and cooling, dewatering, most of the work vehicles used in deep mines today are electric (and these aren't light battery vehicles but heavy equipment trailing high voltage cables), I think it's very conservative to say that the mine consumed over 5MW when it was fully operational.
    - sophacles 3y ago
      > Connected to the grid yes but usually the interconnect is simply enough for running the mine not enough to cover many megawatts of storage capability Mines can use a LOT of electricity. I found a presentation from EPRI[1] talks about varoius electric vehicles and machines used in underground mining. One slide references a "mining system" that alone draws 5-10Mw. Even if you take that as "the whole mine uses 5-10MW", it means that it's grid connected well enough to handle Mw of storage. [1] EPRI is a respected R&D non-profit in the electricty sector. The slides: http://mydocs.epri.com/docs/publicmeetingmaterials/1203/jkn2sd37zwh/d1_nde_d1-5_butts.pdf http://mydocs.epri.com/docs/publicmeetingmaterials/1203/jkn2... the slide I reference is #14.
fghorow 3y ago
It will be interesting to see how much net energy is able to be stored after the energy cost of de-watering the mine is taken into account. (An interesting tidbit of trivia I learned from miners is that deep underground mines only became feasible after reliable pumping was put in place.[1] Prior to that, they flooded out from groundwater intrusion.) [1] https://en.wikipedia.org/wiki/Flooded_mine https://en.wikipedia.org/wiki/Flooded_mine Edited to add the wikipedia link.
- defrost 3y ago
  Depends on base depth and water table - It's 1.4 km "deep" from the head .. which might be 2.5 km above sea level in Finland (what with all the steep bits and everything). If the bottom is well above sea level and not in line of any underground rivers | streams | lakes it'll stay relatively dry. For interest: https://en.wikipedia.org/wiki/Pyh%C3%A4salmi_Mine https://en.wikipedia.org/wiki/Pyh%C3%A4salmi_Mine The "main level" of the mine is at 1400 meters depth and can be accessed with either the mine hoist or via the access tunnel. The main level houses a cafeteria, washrooms, showers, workshops, storage facilities, as well as a safety area. It is also home to the world's deepest sauna, at 1,410 metres (4,626 ft) underground. Pyhäsalmi Mine has hosted numerous events due to its attraction as a unique location. It has hosted the deepest concert in the world (by Agonizer at 1271 m ) as well as dance performances. The 11 km long spiral-shaped main tunnel has also seen several uphill running and cycling competitions. Pyhäsalmi Mine can be recognized as a filming location for the new sci-fi television series White Wall, premiered in 2020. Ahhhh, Finland, Finland, Finland.
  - helsinkiandrew 3y ago
    >which might be 2.5 km above sea level in Finland (what with all the steep bits and everything). Steep bits? Are you thinking of Norway :-) there’s no steep bits in Finland, highest point above sea level is 1324M! There was even a Norwegian campaign to gift a mountain for its birthday https://www.bbc.co.uk/news/world-europe-37662811 https://www.bbc.co.uk/news/world-europe-37662811
    - 3y ago
bluenose69 3y ago
The phrase "2 MW of energy" makes no sense based on units. Shouldn't writers (and editors) be required to at least take high school physics or chemistry?
- grdgyredb 3y ago
  I took those things m, and I’m a successful software engineer and founder with an exit. I can never remember anything but joules for energy. Which I think doesn’t matter? And my RV has amp-hours? No fucking idea.
  - Tostino 3y ago
    But are you writing articles about the topic?
    - peddling-brink 3y ago
      Journalists are just failed CEOs.
- meatmanek 3y ago
  As far as I can tell, they mean they can bring up to 2 MW of power online, with nothing said about the energy storage capacity of the site.
- RugnirViking 3y ago
  to be fair they might be somewhat confused by marketing copy. I've worked on installations like this, and its not uncommon for capacities to be specified as something like 50MW battery (4 hours). sometimes the number of hours is written in a different place to the base output capacity. I think it started because originally the idea is that the battery is some number of hours multiple of the production of a generating asset, like on-site wind. In fact capacity payments and stuff in some countries (read: subsidies) can be different based on the number of hours of the battery
XorNot 3y ago
Huh...this is literally the "heavy weight" sort of gravity battery rather then pumping water. I'm...not really convinced this is going to be viable. 2MWh (which is what I assume the article means) is not a lot of power at all (about 40 days of my roof top solar production) - and that's with "the deepest mine in Europe". The basic problem is that your heaviest, cheapest weight is concrete or stone which is only about 2.5 times as dense as water. But the cost you pay for that is you can no longer pump or flow it so by definition you're limited.
- kibwen 3y ago
  I'm not sure that the density of the material itself really matters much; having the weight take up less space doesn't really reduce the overall power of the system very much (the weight is probably not occupying a very large portion of the shaft's height). That said, lead is also dirt-cheap and is more than 11x denser than water. Gravity batteries are cool. They don't make a lot of economic sense by themselves, but they do if the vertical height already exists and doesn't need to be constructed.
  - XorNot 3y ago
    The heavier you make your counterweight, the more strength you need in your cables. The problem is that you could solve this by say, lowering a small pallet of whatever to the bottom of the shaft and moving it sideways out of the way - trading "power" for "energy storage". But if you extend that idea you wind up at "pump a liquid" as the obvious way to do it, since that has essentially no limit on flow-ability. The other problem of course it lead in the first place: 1000kg of lead at 1500m high is about 4kWh of potential energy. 1000kg of Lead-Acid batteries is about 25 kWh of potential energy. I suppose you could put the batteries on a cable for the extra 4kWh but I suspect the complexity isn't worth it.
    - 15457345234 3y ago
      > 1000kg of lead at 1500m high is about 4kWh of potential energy. 1000kg of Lead-Acid batteries is about 25 kWh of potential energy. I suppose you could put the batteries on a cable for the extra 4kWh but I suspect the complexity isn't worth it. That's just so well said. Should be the top comment every single time this dumb idea is surfaced. I'm convinced now people are pulling stunts like this just to make renewables look bad.
tempestn 3y ago
You'd think that in an article specifically about energy storage, in the introductory paragraph, they'd get the units right. > The Pyhäsalmi Mine, roughly 450 kilometres north of Helsinki, is Europe’s deepest zinc and copper mine and holds the potential to store up to 2 MW of energy within its 1,400-metre-deep shafts.
- jcrawfordor 3y ago
  It's frustrating, every article just repeats "2MW capacity." Gravitricity hasn't announced this project themselves yet, hopefully when they do they give the actual storage capacity. But I think 2MWh might be correct - in press elsewhere Gravitricity says 500t over 800m produces 1MWh. This is a deeper depth but not that much, and this is very much an experimental project so I think they might be sticking to 500-750t mass. They anticipate larger systems using multiple masses rather than a single larger one. Still, they've also announced a 4MWh project in the UK, so it's not like they see 2MWh as a limit.
  - alkonaut 3y ago
    It’s a sad reality now, 1Mwh is sloppily called “1MW” when it’s about energy, but “1MW” when it’s about power. It’s just like the ship sailed on 1 kilocalorie.m being called “one calorie” I think we can give up on this one as well.
    - rightbyte 3y ago
      No. Never. kcal and cal atleast is the same unit.
    - fecal_henge 3y ago
      It all gets confusing when integrating power over a strange quantity of time. I wish we had some kind of rational unit to quantify energy
      - ryukoposting 3y ago
        Joules? Maybe you're facetious but it's hard to tell over the internet.
GuB-42 3y ago
Isn't there a better article? - 2 MW of energy MW is a unit of power not energy, maybe they mean 2 MWh, but if that's the case, it is a joke. That's like 30 Teslas cars, or half of a Tesla Megapack, which is a shipping container sized battery. 2 MW of power is not that big either, that's about what you get from a typical wind turbine. - 70TWh of energy At least, we have a proper unit, but I wish they tell us a bit more about how they got a number 7 orders of magnitude larger than the previous one. - A study last year by the International Institute for Applied Systems Analysis (IIASA) What study? Source please
- bunabhucan 3y ago
  >Future GraviStores will store more than 20MWh https://www.marketscreener.com/quote/stock/ABB-LTD-9365000/news/ABB-and-Gravitricity-to-collaborate-on-energy-storage-systems-using-end-of-life-mine-shafts-and-ho-45539581/ https://www.marketscreener.com/quote/stock/ABB-LTD-9365000/n...
  - weebull 3y ago
    In which case, this one is a joke. It stores less than $3,000 worth of electricity (15¢ per kWh).
- usrusr 3y ago
  Part of me certainly hated myself for not stopping to read right there. But it's an interesting approach despite the bad writing: if you fill a 1400m shaft with a dense chain of buckets (my term, they seem to call them vessels) you'll need a surprising low amount of mass throughput for a given amount of power flowing in/out. Because there is just so much in transit at any given point in time. A naive implementation would quickly run into limits in rope strength and the like, but the schematic drawing suggests that the system they suggest consists of a chain of shorter loops, each just carrying whatever low number of vessels is easiest to engineer, and handing them over bucket-brigade style. This sounds complicated, but a similar thing is routinely done by gondola lifts with intermediate stations between separate wire loops (but here, handover could presumably be done simpler and in less maintenance-demanding ways because latency is no goal at all). So you'd design a system that works for three loops in a shaft not much deeper than a deep cellar and then scale it out to a very deep mine. The power in/out is simply the throughput of a single stage times how many of those stages can be stacked in the shaft (or rather: hung to the sides of the shaft on top of each other, they'd certainly not be stacked in the statical sense). And if your battery is ever considered full but you still have extra energy to store, you could always decide to dig more horizontal tunnel, like when the mine was still serving it's original purpose. All you need is room (and transportation) for a larger spoil heap in the sun. Digression: it's hot down there. Could you, with sufficiently insulated pipes, spin up a geothermally powered loop of air where the hot air carries moisture up skyside? If the sand is drier on the way up than it was on the way down while discharging you could theoretically end up with efficiency > 100. (in reality, more energy will certainly be lost to uninvited water finding it's way down, but perhaps this geothermal harvest could help battle the losses to water ingress)
bunabhucan 3y ago
>The decommissioning of mine shafts is a costly and time-consuming process for mining companies. I wonder if that is part of the impetus - make cleanup/decommissioning happen in distant future dollars helps the balance sheet today. https://www.marketscreener.com/quote/stock/ABB-LTD-9365000/news/ABB-and-Gravitricity-to-collaborate-on-energy-storage-systems-using-end-of-life-mine-shafts-and-ho-45539581/ https://www.marketscreener.com/quote/stock/ABB-LTD-9365000/n...
- undersuit 3y ago
  I think that the cost(or even profits) of filling a mine back in after excavation should be considered from the beginning. Hell we could even sell the futures now to recoup the cost of building a mine tomorrow.
  - riffraff 3y ago
    I believe that's how the US superfund was supposed to work (tax miners now so we can use that money to fix the damage they did if they won't) but this is no longer the case.
  - onion2k 3y ago
    Wouldn't that require knowing how far down/across you're going to dig? Most mines have a known seam to begin with, but a lot of exploration and geology work comes later when there's a big hole to work from. There's only so much you can tell at the surface before you start.
    - tialaramex 3y ago
      You can (and a less corrupt industrialized country's government sometimes will) require that they give you the money [or lock it into a fund they don't control] before they get permission to make the hole bigger. You need government inspections (so they can't make it bigger without permission) to make this possible, but those are needed for safety anyway. If you let them, they'll eventually walk away leaving you with a toxic mess and a hole in your budget. The same thing applies for a government securing clean-up funding or a musician securing royalties from a label/ publisher, make sure you get paid first, if you're supposedly getting paid last it will always turn out that whoops, there is no money left, thanks for making us rich, bye.
mhandley 3y ago
Dry sand has a mass of 1600kg/m^3 Potential energy, U = mgh. So the energy required to raise 1m^3 of sand 1400m is 1600 x 1400 x 9.8 = 22MJ = 6.1kWh I've no idea how large their mine galleries are, but lets say they're 3m wide x 2m high - in 500m of gallery, we can store 3000m^3 of sand, so that's 18MWh. I'm sure they've got a lot more space than that, but it just gives some idea of how much sand you're talking about.
- danans 3y ago
  > Potential energy, U = mgh. So the energy required to raise 1m^3 of sand 1400m is 1600 x 1400 x 9.8 = 22MJ = 6.1kWh If you lowered 10 m^3 of sand (61kWh of potential energy), to generate the minimum 100kW power to participate in grid stabilization markets, you'd have to drop that 16000kg of sand for 61kWh/100kW = 0.61hr = 2196 sec. 1400 meters in 2196 seconds is 0.64 m/sec. That seems reasonable, but you'd need a lot of these (so a wide mineshaft) to generate a more meaningful amount of power (like at least 1 MW). Current grid scale batteries are capable of outputting hundreds of MW of power. https://en.wikipedia.org/wiki/Battery_storage_power_station https://en.wikipedia.org/wiki/Battery_storage_power_station > we can store 3000m^3 of sand, so that's 18MWh. > I'm sure they've got a lot more space than that, but it just gives some idea of how much sand you're talking about. They're going to need 3 orders of magnitude more space then because current generation grid scale batteries store GWh of energy, and generally speaking lower cost energy storage competes by offering much higher storage capacity.
  - 15457345234 3y ago
    Yeah, my surface level evaluation of these projects is that they're just not going to be viable - you have the height but you don't have the volume - mineshafts are by definition narrow - and some sort of automated load/unload system is going to run into issues of complexity and reliability and ease of access for maintenance to whatever's at the bottom end. It's always going to be easier to move water around in an automated fashion, though, so I'm immediately skeptical of any system that isn't some variant of two tanks and a pump/turbine. If you really do want to use gravity as a power source and don't want to go the hydro route you're better off building narrow-gauge train lines up the sides of hills. The lower-impact and lower-output version of that would be aerial ropeways.
boringg 3y ago
Were going to read how this is an unsuccessful endeavor in about 5 years. I haven't seen a lot of great reports on gravity batteries. I wish something like this was highly viable and succesful. Seems like a great simple solution.
- romusha 3y ago
  5 ? I'll give 2. See ya in 2026
- CatWChainsaw 3y ago
  I got a tidbit of amusing that a person named "boring" commented on a gravity mine article.
helsinkiandrew 3y ago
I’m sceptical about this technology, but it seems it is a lot lower cost than batteries (they claim a plant can last 50+ years with 50k+ cycles), can provide bursts of power, and can offset the decommissioning cost of mines. A slightly better article: https://eepower.com/news/gravity-energy-storage-systems-transforming-defunct-mines-into-efficient-energy-producers/ https://eepower.com/news/gravity-energy-storage-systems-tran... The company: https://gravitricity.com/ https://gravitricity.com/
- andruby 3y ago
  I'm curious about the running costs. I expect that heavy moving parts will cause more wear & tear than a LFP grid-scale stationary battery, but I could be wrong.
thecoser42 3y ago
Excellent to hear
Log_out_ 3y ago
There was a plan, to use giant cylinders of landscape as hydraulic batteries. The problem was the cost of excavation or building the cylinder. Then this came along, not even promoted as the future.. https://www.newcivilengineer.com/the-future-of/future-of-tunnelling-how-bots-will-build-tunnels-of-the-future-01-10-2021/ https://www.newcivilengineer.com/the-future-of/future-of-tun... And it's ideal.as in they could turn testsites into batteries. You could have such a battery in an any abandoned quary today. Chip the walls smoth, freeze an ice plug, pump water beneath and use the stored pressure.
aaron695 3y ago
[dead]
chinathrow 3y ago
I've been thinking about a similar system to drop weights into the ocean for a while, like with attached pressurized air tanks to inflate balloons for resurfacing. Not an engineer, so I haven't been able to calculate if any of this would work, at all.
- klabb3 3y ago
  That’s an interesting idea, but pressurizing air needs a lot of energy, and it needs to be pressurized more the deeper you’re going (because of well.. pressure). Not to mention the air volume at depth is much smaller, so you need a lot of air to start lifting, and once it’s buoyant and starts rising, you have a bunch of extra air volume that’s “wasted”.
- shellfishgene 3y ago
  How would you recover energy from that?
effie 3y ago
Another completely misleading article on gravity batteries. All the solid weight stuff is bunk, probably designed to suck out money from naive investors / corrupt state officials. Moving solid weights gives only a very small electric power, so building the proposed solid weight batteries gives units of MW at most, which is uneconomical. Unless it transports a large lake of water up and down a hill like in pumped-storage hydroelectric plants, and can provide tens or hundreds of MW. Such installations are very expensive to build today, because all the low-hanging fruit options seem to have been already built.
- RGamma 3y ago
  > Unless it transports a large lake of water up and down a hill https://gravity-storage.com/ https://gravity-storage.com/ are trying to make compact hydroelectric plants by putting weight on the fluid. Wish someone would give them loads of money :/
- ben_w 3y ago
  These kinds of gravity batteries worry me a little, because when I've seen the economics, they actually look pretty decent… and yet, that economic calculation ignores the other impacts, like them being terrible energy density and thus needing absurd volumes dedicated to them. Most proposals are even worse, as they suggest concrete rather than sand. The monetary cost works out even then, but concrete production currently emits CO2, and the combination of that with the low energy density means they'd have to run for around a century to only be as bad as fossil fuels.
- donquichotte 3y ago
  My thoughts exactly. It makes the engineer in me go mad if I see projects like Energy Vault [1] getting massive funding that could be used to try and develop technologies that make sense. Thankfully there are some people who see through the charade [2]. If you are into this thing and looking for an even more stupid idea to store energy, I present to you the StEnSEA [3]. Rolls right off the tongue, right? It is a hollow concrete sphere that is lowered to the bottom of the lake. Pumps then remove water from it, creating a vacuum. Letting the water back in and using the pumps as generators, the energy is reclaimed. Curiously absent from all documentation of this project is the amount of energy stored. I did some back of the envelope calculations a while back and it is 3.8kWh, for a multi-million-euro prototype! [1] https://www.energyvault.com/ev1 https://www.energyvault.com/ev1 [2] https://www.youtube.com/watch?v=iGGOjD_OtAM https://www.youtube.com/watch?v=iGGOjD_OtAM [3] https://www.iee.fraunhofer.de/de/projekte/suche/2013/stensea.html https://www.iee.fraunhofer.de/de/projekte/suche/2013/stensea...
huqedato 3y ago
"giant battery" - 2MW ? A typo ? They probably meant 2TWh if it is to "to power the planet"
amsterdorn 3y ago
Great, another Energy Vault grift... Hope this doesn't actually get built.

I admit in the past I've been skeptical about the use of gravity batteries when they involved things like towers and stacking large weights as their energy density is relatively quite low, but this seems like it makes a ton of sense. That is: 1. The shaft is already dug, so no need to build a tower. 2. As the article points out, many/most of these sites are already well-connected to the grid. 3. Also as pointed out in the article, this could be a boon to depressed areas and help broaden economic value generation. Am I missing something?

WalterBright 3y ago
A gravity battery doesn't need a well or a tower. The slope of a hill will do. More or less put railroad tracks up the slope, and have the "car" winched up and down. Just like the ratcheting trolleys that go up and down hills.
- checker 3y ago
  | Just like the ratcheting trolleys that go up and down hills. https://en.wikipedia.org/wiki/Funicular https://en.wikipedia.org/wiki/Funicular
- stubish 3y ago
  There was recently an article here about an electric truck that never needs charging. It drives up a hill, collects a load of rock from the mine there, and by the time it has driven back down with the heavy load, regenerative breaking has recharged the battery.
  - bnegreve 3y ago
    Soon we will be hearing of the global flattening.
  - WalterBright 3y ago
    While that makes perfect sense, I have read journalists claiming that Teslas were 110% efficient because of regenerative braking.
    - stubish 3y ago
      A pile of rocks on a hill is a renewable energy source if you are prepared to wait a few billion years for plate tectonics to recharge it.
  - ryukoposting 3y ago
    Would you happen to have a link?
    - roelschroeven 3y ago
      "This massive 45-ton electric dump truck never uses more energy than it generates on its own — here's how that works" https://www.businessinsider.com/edumper-121-ton-electric-dump-truck-2019-8?international=true&r=US&IR=T https://www.businessinsider.com/edumper-121-ton-electric-dum... (You can find more articles if you search for "eDumper")
deleted 3y ago
[deleted]

barbegal 3y ago

This must be orders of magnitude more expensive than pumped hydro and I would expect more expensive than lithium batteries. And unless the mine is close to an existing high voltage substation then there will be significant costs hooking it up to the grid. The pilot will be a 2MW generator but you can fit a 2MW inverter and a 2MWh battery into a single shipping container so the scale is really minimal.

standardUser 3y ago
> The IIASA analysts noted that mines already have the basic infrastructure for such an endeavour, while also being connected to the power grid. “This significantly reduces the cost and facilities for the implementation of Underground Gravity Energy Storage (UGES) plants,” the study noted. Not that your wholly unsupported naysaying isn't compelling.
- barbegal 3y ago
  Connected to the grid yes but usually the interconnect is simply enough for running the mine not enough to cover many megawatts of storage capability. The battery storage companies have found that there is an abundance of fields and brownfield sites close to existing substations to place their batteries where the cost of connecting to the grid is minimal.
  - jcrawfordor 3y ago
    The hoist at this mine is 2.5MW, there's typically some ore processing on site, mines end up requiring a lot of ventilation and cooling, dewatering, most of the work vehicles used in deep mines today are electric (and these aren't light battery vehicles but heavy equipment trailing high voltage cables), I think it's very conservative to say that the mine consumed over 5MW when it was fully operational.
  - sophacles 3y ago
    > Connected to the grid yes but usually the interconnect is simply enough for running the mine not enough to cover many megawatts of storage capability Mines can use a LOT of electricity. I found a presentation from EPRI[1] talks about varoius electric vehicles and machines used in underground mining. One slide references a "mining system" that alone draws 5-10Mw. Even if you take that as "the whole mine uses 5-10MW", it means that it's grid connected well enough to handle Mw of storage. [1] EPRI is a respected R&D non-profit in the electricty sector. The slides: http://mydocs.epri.com/docs/publicmeetingmaterials/1203/jkn2sd37zwh/d1_nde_d1-5_butts.pdf http://mydocs.epri.com/docs/publicmeetingmaterials/1203/jkn2... the slide I reference is #14.

fghorow 3y ago

It will be interesting to see how much net energy is able to be stored after the energy cost of de-watering the mine is taken into account. (An interesting tidbit of trivia I learned from miners is that deep underground mines only became feasible after reliable pumping was put in place.[1] Prior to that, they flooded out from groundwater intrusion.) [1] https://en.wikipedia.org/wiki/Flooded_mine https://en.wikipedia.org/wiki/Flooded_mine Edited to add the wikipedia link.

defrost 3y ago
Depends on base depth and water table - It's 1.4 km "deep" from the head .. which might be 2.5 km above sea level in Finland (what with all the steep bits and everything). If the bottom is well above sea level and not in line of any underground rivers | streams | lakes it'll stay relatively dry. For interest: https://en.wikipedia.org/wiki/Pyh%C3%A4salmi_Mine https://en.wikipedia.org/wiki/Pyh%C3%A4salmi_Mine The "main level" of the mine is at 1400 meters depth and can be accessed with either the mine hoist or via the access tunnel. The main level houses a cafeteria, washrooms, showers, workshops, storage facilities, as well as a safety area. It is also home to the world's deepest sauna, at 1,410 metres (4,626 ft) underground. Pyhäsalmi Mine has hosted numerous events due to its attraction as a unique location. It has hosted the deepest concert in the world (by Agonizer at 1271 m ) as well as dance performances. The 11 km long spiral-shaped main tunnel has also seen several uphill running and cycling competitions. Pyhäsalmi Mine can be recognized as a filming location for the new sci-fi television series White Wall, premiered in 2020. Ahhhh, Finland, Finland, Finland.
- helsinkiandrew 3y ago
  >which might be 2.5 km above sea level in Finland (what with all the steep bits and everything). Steep bits? Are you thinking of Norway :-) there’s no steep bits in Finland, highest point above sea level is 1324M! There was even a Norwegian campaign to gift a mountain for its birthday https://www.bbc.co.uk/news/world-europe-37662811 https://www.bbc.co.uk/news/world-europe-37662811
  - 3y ago

bluenose69 3y ago

The phrase "2 MW of energy" makes no sense based on units. Shouldn't writers (and editors) be required to at least take high school physics or chemistry?

grdgyredb 3y ago
I took those things m, and I’m a successful software engineer and founder with an exit. I can never remember anything but joules for energy. Which I think doesn’t matter? And my RV has amp-hours? No fucking idea.
- Tostino 3y ago
  But are you writing articles about the topic?
  - peddling-brink 3y ago
    Journalists are just failed CEOs.
meatmanek 3y ago
As far as I can tell, they mean they can bring up to 2 MW of power online, with nothing said about the energy storage capacity of the site.
RugnirViking 3y ago
to be fair they might be somewhat confused by marketing copy. I've worked on installations like this, and its not uncommon for capacities to be specified as something like 50MW battery (4 hours). sometimes the number of hours is written in a different place to the base output capacity. I think it started because originally the idea is that the battery is some number of hours multiple of the production of a generating asset, like on-site wind. In fact capacity payments and stuff in some countries (read: subsidies) can be different based on the number of hours of the battery

XorNot 3y ago

Huh...this is literally the "heavy weight" sort of gravity battery rather then pumping water. I'm...not really convinced this is going to be viable. 2MWh (which is what I assume the article means) is not a lot of power at all (about 40 days of my roof top solar production) - and that's with "the deepest mine in Europe". The basic problem is that your heaviest, cheapest weight is concrete or stone which is only about 2.5 times as dense as water. But the cost you pay for that is you can no longer pump or flow it so by definition you're limited.

kibwen 3y ago
I'm not sure that the density of the material itself really matters much; having the weight take up less space doesn't really reduce the overall power of the system very much (the weight is probably not occupying a very large portion of the shaft's height). That said, lead is also dirt-cheap and is more than 11x denser than water. Gravity batteries are cool. They don't make a lot of economic sense by themselves, but they do if the vertical height already exists and doesn't need to be constructed.
- XorNot 3y ago
  The heavier you make your counterweight, the more strength you need in your cables. The problem is that you could solve this by say, lowering a small pallet of whatever to the bottom of the shaft and moving it sideways out of the way - trading "power" for "energy storage". But if you extend that idea you wind up at "pump a liquid" as the obvious way to do it, since that has essentially no limit on flow-ability. The other problem of course it lead in the first place: 1000kg of lead at 1500m high is about 4kWh of potential energy. 1000kg of Lead-Acid batteries is about 25 kWh of potential energy. I suppose you could put the batteries on a cable for the extra 4kWh but I suspect the complexity isn't worth it.
  - 15457345234 3y ago
    > 1000kg of lead at 1500m high is about 4kWh of potential energy. 1000kg of Lead-Acid batteries is about 25 kWh of potential energy. I suppose you could put the batteries on a cable for the extra 4kWh but I suspect the complexity isn't worth it. That's just so well said. Should be the top comment every single time this dumb idea is surfaced. I'm convinced now people are pulling stunts like this just to make renewables look bad.

tempestn 3y ago

You'd think that in an article specifically about energy storage, in the introductory paragraph, they'd get the units right. > The Pyhäsalmi Mine, roughly 450 kilometres north of Helsinki, is Europe’s deepest zinc and copper mine and holds the potential to store up to 2 MW of energy within its 1,400-metre-deep shafts.

jcrawfordor 3y ago
It's frustrating, every article just repeats "2MW capacity." Gravitricity hasn't announced this project themselves yet, hopefully when they do they give the actual storage capacity. But I think 2MWh might be correct - in press elsewhere Gravitricity says 500t over 800m produces 1MWh. This is a deeper depth but not that much, and this is very much an experimental project so I think they might be sticking to 500-750t mass. They anticipate larger systems using multiple masses rather than a single larger one. Still, they've also announced a 4MWh project in the UK, so it's not like they see 2MWh as a limit.
- alkonaut 3y ago
  It’s a sad reality now, 1Mwh is sloppily called “1MW” when it’s about energy, but “1MW” when it’s about power. It’s just like the ship sailed on 1 kilocalorie.m being called “one calorie” I think we can give up on this one as well.
  - rightbyte 3y ago
    No. Never. kcal and cal atleast is the same unit.
  - fecal_henge 3y ago
    It all gets confusing when integrating power over a strange quantity of time. I wish we had some kind of rational unit to quantify energy
    - ryukoposting 3y ago
      Joules? Maybe you're facetious but it's hard to tell over the internet.

GuB-42 3y ago

Isn't there a better article? - 2 MW of energy MW is a unit of power not energy, maybe they mean 2 MWh, but if that's the case, it is a joke. That's like 30 Teslas cars, or half of a Tesla Megapack, which is a shipping container sized battery. 2 MW of power is not that big either, that's about what you get from a typical wind turbine. - 70TWh of energy At least, we have a proper unit, but I wish they tell us a bit more about how they got a number 7 orders of magnitude larger than the previous one. - A study last year by the International Institute for Applied Systems Analysis (IIASA) What study? Source please

bunabhucan 3y ago
>Future GraviStores will store more than 20MWh https://www.marketscreener.com/quote/stock/ABB-LTD-9365000/news/ABB-and-Gravitricity-to-collaborate-on-energy-storage-systems-using-end-of-life-mine-shafts-and-ho-45539581/ https://www.marketscreener.com/quote/stock/ABB-LTD-9365000/n...
- weebull 3y ago
  In which case, this one is a joke. It stores less than $3,000 worth of electricity (15¢ per kWh).
usrusr 3y ago
Part of me certainly hated myself for not stopping to read right there. But it's an interesting approach despite the bad writing: if you fill a 1400m shaft with a dense chain of buckets (my term, they seem to call them vessels) you'll need a surprising low amount of mass throughput for a given amount of power flowing in/out. Because there is just so much in transit at any given point in time. A naive implementation would quickly run into limits in rope strength and the like, but the schematic drawing suggests that the system they suggest consists of a chain of shorter loops, each just carrying whatever low number of vessels is easiest to engineer, and handing them over bucket-brigade style. This sounds complicated, but a similar thing is routinely done by gondola lifts with intermediate stations between separate wire loops (but here, handover could presumably be done simpler and in less maintenance-demanding ways because latency is no goal at all). So you'd design a system that works for three loops in a shaft not much deeper than a deep cellar and then scale it out to a very deep mine. The power in/out is simply the throughput of a single stage times how many of those stages can be stacked in the shaft (or rather: hung to the sides of the shaft on top of each other, they'd certainly not be stacked in the statical sense). And if your battery is ever considered full but you still have extra energy to store, you could always decide to dig more horizontal tunnel, like when the mine was still serving it's original purpose. All you need is room (and transportation) for a larger spoil heap in the sun. Digression: it's hot down there. Could you, with sufficiently insulated pipes, spin up a geothermally powered loop of air where the hot air carries moisture up skyside? If the sand is drier on the way up than it was on the way down while discharging you could theoretically end up with efficiency > 100. (in reality, more energy will certainly be lost to uninvited water finding it's way down, but perhaps this geothermal harvest could help battle the losses to water ingress)

bunabhucan 3y ago

>The decommissioning of mine shafts is a costly and time-consuming process for mining companies. I wonder if that is part of the impetus - make cleanup/decommissioning happen in distant future dollars helps the balance sheet today. https://www.marketscreener.com/quote/stock/ABB-LTD-9365000/news/ABB-and-Gravitricity-to-collaborate-on-energy-storage-systems-using-end-of-life-mine-shafts-and-ho-45539581/ https://www.marketscreener.com/quote/stock/ABB-LTD-9365000/n...

undersuit 3y ago
I think that the cost(or even profits) of filling a mine back in after excavation should be considered from the beginning. Hell we could even sell the futures now to recoup the cost of building a mine tomorrow.
- riffraff 3y ago
  I believe that's how the US superfund was supposed to work (tax miners now so we can use that money to fix the damage they did if they won't) but this is no longer the case.
- onion2k 3y ago
  Wouldn't that require knowing how far down/across you're going to dig? Most mines have a known seam to begin with, but a lot of exploration and geology work comes later when there's a big hole to work from. There's only so much you can tell at the surface before you start.
  - tialaramex 3y ago
    You can (and a less corrupt industrialized country's government sometimes will) require that they give you the money [or lock it into a fund they don't control] before they get permission to make the hole bigger. You need government inspections (so they can't make it bigger without permission) to make this possible, but those are needed for safety anyway. If you let them, they'll eventually walk away leaving you with a toxic mess and a hole in your budget. The same thing applies for a government securing clean-up funding or a musician securing royalties from a label/ publisher, make sure you get paid first, if you're supposedly getting paid last it will always turn out that whoops, there is no money left, thanks for making us rich, bye.

mhandley 3y ago

Dry sand has a mass of 1600kg/m^3 Potential energy, U = mgh. So the energy required to raise 1m^3 of sand 1400m is 1600 x 1400 x 9.8 = 22MJ = 6.1kWh I've no idea how large their mine galleries are, but lets say they're 3m wide x 2m high - in 500m of gallery, we can store 3000m^3 of sand, so that's 18MWh. I'm sure they've got a lot more space than that, but it just gives some idea of how much sand you're talking about.

danans 3y ago
> Potential energy, U = mgh. So the energy required to raise 1m^3 of sand 1400m is 1600 x 1400 x 9.8 = 22MJ = 6.1kWh If you lowered 10 m^3 of sand (61kWh of potential energy), to generate the minimum 100kW power to participate in grid stabilization markets, you'd have to drop that 16000kg of sand for 61kWh/100kW = 0.61hr = 2196 sec. 1400 meters in 2196 seconds is 0.64 m/sec. That seems reasonable, but you'd need a lot of these (so a wide mineshaft) to generate a more meaningful amount of power (like at least 1 MW). Current grid scale batteries are capable of outputting hundreds of MW of power. https://en.wikipedia.org/wiki/Battery_storage_power_station https://en.wikipedia.org/wiki/Battery_storage_power_station > we can store 3000m^3 of sand, so that's 18MWh. > I'm sure they've got a lot more space than that, but it just gives some idea of how much sand you're talking about. They're going to need 3 orders of magnitude more space then because current generation grid scale batteries store GWh of energy, and generally speaking lower cost energy storage competes by offering much higher storage capacity.
- 15457345234 3y ago
  Yeah, my surface level evaluation of these projects is that they're just not going to be viable - you have the height but you don't have the volume - mineshafts are by definition narrow - and some sort of automated load/unload system is going to run into issues of complexity and reliability and ease of access for maintenance to whatever's at the bottom end. It's always going to be easier to move water around in an automated fashion, though, so I'm immediately skeptical of any system that isn't some variant of two tanks and a pump/turbine. If you really do want to use gravity as a power source and don't want to go the hydro route you're better off building narrow-gauge train lines up the sides of hills. The lower-impact and lower-output version of that would be aerial ropeways.

boringg 3y ago

Were going to read how this is an unsuccessful endeavor in about 5 years. I haven't seen a lot of great reports on gravity batteries. I wish something like this was highly viable and succesful. Seems like a great simple solution.

romusha 3y ago
5 ? I'll give 2. See ya in 2026
CatWChainsaw 3y ago
I got a tidbit of amusing that a person named "boring" commented on a gravity mine article.

helsinkiandrew 3y ago

I’m sceptical about this technology, but it seems it is a lot lower cost than batteries (they claim a plant can last 50+ years with 50k+ cycles), can provide bursts of power, and can offset the decommissioning cost of mines. A slightly better article: https://eepower.com/news/gravity-energy-storage-systems-transforming-defunct-mines-into-efficient-energy-producers/ https://eepower.com/news/gravity-energy-storage-systems-tran... The company: https://gravitricity.com/ https://gravitricity.com/

andruby 3y ago
I'm curious about the running costs. I expect that heavy moving parts will cause more wear & tear than a LFP grid-scale stationary battery, but I could be wrong.

thecoser42 3y ago

Excellent to hear

Log_out_ 3y ago

There was a plan, to use giant cylinders of landscape as hydraulic batteries. The problem was the cost of excavation or building the cylinder. Then this came along, not even promoted as the future.. https://www.newcivilengineer.com/the-future-of/future-of-tunnelling-how-bots-will-build-tunnels-of-the-future-01-10-2021/ https://www.newcivilengineer.com/the-future-of/future-of-tun... And it's ideal.as in they could turn testsites into batteries. You could have such a battery in an any abandoned quary today. Chip the walls smoth, freeze an ice plug, pump water beneath and use the stored pressure.

aaron695 3y ago

[dead]

chinathrow 3y ago

I've been thinking about a similar system to drop weights into the ocean for a while, like with attached pressurized air tanks to inflate balloons for resurfacing. Not an engineer, so I haven't been able to calculate if any of this would work, at all.

klabb3 3y ago
That’s an interesting idea, but pressurizing air needs a lot of energy, and it needs to be pressurized more the deeper you’re going (because of well.. pressure). Not to mention the air volume at depth is much smaller, so you need a lot of air to start lifting, and once it’s buoyant and starts rising, you have a bunch of extra air volume that’s “wasted”.
shellfishgene 3y ago
How would you recover energy from that?

effie 3y ago

Another completely misleading article on gravity batteries. All the solid weight stuff is bunk, probably designed to suck out money from naive investors / corrupt state officials. Moving solid weights gives only a very small electric power, so building the proposed solid weight batteries gives units of MW at most, which is uneconomical. Unless it transports a large lake of water up and down a hill like in pumped-storage hydroelectric plants, and can provide tens or hundreds of MW. Such installations are very expensive to build today, because all the low-hanging fruit options seem to have been already built.

RGamma 3y ago
> Unless it transports a large lake of water up and down a hill https://gravity-storage.com/ https://gravity-storage.com/ are trying to make compact hydroelectric plants by putting weight on the fluid. Wish someone would give them loads of money :/
ben_w 3y ago
These kinds of gravity batteries worry me a little, because when I've seen the economics, they actually look pretty decent… and yet, that economic calculation ignores the other impacts, like them being terrible energy density and thus needing absurd volumes dedicated to them. Most proposals are even worse, as they suggest concrete rather than sand. The monetary cost works out even then, but concrete production currently emits CO2, and the combination of that with the low energy density means they'd have to run for around a century to only be as bad as fossil fuels.
donquichotte 3y ago
My thoughts exactly. It makes the engineer in me go mad if I see projects like Energy Vault [1] getting massive funding that could be used to try and develop technologies that make sense. Thankfully there are some people who see through the charade [2]. If you are into this thing and looking for an even more stupid idea to store energy, I present to you the StEnSEA [3]. Rolls right off the tongue, right? It is a hollow concrete sphere that is lowered to the bottom of the lake. Pumps then remove water from it, creating a vacuum. Letting the water back in and using the pumps as generators, the energy is reclaimed. Curiously absent from all documentation of this project is the amount of energy stored. I did some back of the envelope calculations a while back and it is 3.8kWh, for a multi-million-euro prototype! [1] https://www.energyvault.com/ev1 https://www.energyvault.com/ev1 [2] https://www.youtube.com/watch?v=iGGOjD_OtAM https://www.youtube.com/watch?v=iGGOjD_OtAM [3] https://www.iee.fraunhofer.de/de/projekte/suche/2013/stensea.html https://www.iee.fraunhofer.de/de/projekte/suche/2013/stensea...

huqedato 3y ago

"giant battery" - 2MW ? A typo ? They probably meant 2TWh if it is to "to power the planet"

amsterdorn 3y ago

Great, another Energy Vault grift... Hope this doesn't actually get built.