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Europe's deepest mine to become giant gravity battery

independent.co.uk

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Re: Europe's deepest mine to become giant gravity battery

#81

Post by Kon5ole »

GuB-42 wrote: post #25

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 mo…

>Isn't there a better article? >maybe they mean 2 MWh, but if that's the case, it is a joke.

There are tons of equally bad articles about this story, which is sad to see. Quality journalism might not be dead but it sure is outnumbered!

However, reading about the proposed mechanism I might charitably interpret it as being able to deliver 2MW peak power, for however long it has available sand.

So an interesting aspect of this is how much area is available for sand, not just how tall the shaft is. If it has sand for 10 hours of operation it can store 20 MWh, if it has sand for 100 hours it stores 200MWh.

Many questions remain, but if it is more efficient than generating hydrogen, and takes less space than pumped hydro (or can be made in areas unsuitable for pumped hydro) there might be a point to it.

Re: Europe's deepest mine to become giant gravity battery

#82

Post by mnw21cam »

XorNot wrote: post #40
kibwen wrote: post #20

Earlier quoted context omitted.

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…

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 o…

The difference is that 1000kg of lead costs ~US$2000, and lasts forever, but 1000kg of lead-acid batteries costs ~US$9000, but only lasts for 10 years.

Re: Europe's deepest mine to become giant gravity battery

#83

Post by RGamma »

effie wrote: post #80

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-stor…

> Unless it transports a large lake of water up and down a hill

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 :/

Re: Europe's deepest mine to become giant gravity battery

#84

Post by ben_w »

effie wrote: post #80

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-stor…

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.

Re: Europe's deepest mine to become giant gravity battery

#85

Post by XorNot »

ZeroGravitas wrote: post #71
pfdietz wrote: post #36

Earlier quoted context omitted.

You might be surprised at the enormous numbers of sites that are potentially suitable for pumped hydro, if you go looking for them in areas with vertical relief. https://re100.eng.anu.edu.au/global/ "ANU has identified 616,000 potential sites around the world." (note that not all countries are included in this because of lack of geographical elevation data) A place like Nevada has an enormous surfeit of opportunities…

I doubt any pumped storage project can beat solar and battery hybrid projects these days, especially in sunny places like Nevada. People get very laser focused on the storage part, but energy you generate is entirely fungible with energy that you've stored so pumped hydro needs to compete with generation too. edit: looking further into this to try to put some rough numbers on it, the 5 years it'll take to dig the hol…

I'm pretty pessimistic on storage these days, but I will admit that after running some back of the envelope numbers I'm actually a lot more optimistic about chemical batteries then any of the physical storage schemes.

Pumped hydro has a recharge problem - if your reservoir is much larger then your pump, you can't recharge the system in the time of cheapest energy (daytime when solar is active) before you'll be discharging again. The "roughly 4 hours" output of batteries lines up a lot better with this.

It's still too expensive, but when you plug that into the fact batteries can go in anywhere there's space, and they look a lot more attractive and definitely way faster to build. If Sodium-Ion batteries can be made to work and hit the right price point, things could change pretty dramatically though that's pinning hope on an unproven future technology.

Re: Europe's deepest mine to become giant gravity battery

#86

Post by XorNot »

mnw21cam wrote: post #82
XorNot wrote: post #40

Earlier quoted context omitted.

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 o…

The difference is that 1000kg of lead costs ~US$2000, and lasts forever, but 1000kg of lead-acid batteries costs ~US$9000, but only lasts for 10 years.

The mechanical equipment and supporting plant equipment to turn that 1000kg of lead into a power storage system is not free, does not last forever, and experiences mechanical wear and tear - in fact it likely needs constant maintenance on a cycle of weeks to months.

Whereas those Lead-Acid batteries will do their thing for 10 years, then can be recycled into new Lead-Acid batteries and do it again. The support equipment is all solid-state electronics (though still about a 20 year reasonable lifespan).

Re: Europe's deepest mine to become giant gravity battery

#87

Post by cderpz »

GuB-42 wrote: post #25

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 mo…

They probably mean 2MW peak output/input with the chain at maximum weight and velocity.

Re: Europe's deepest mine to become giant gravity battery

#88

Post by donquichotte »

effie wrote: post #80

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-stor…

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

[2] https://www.youtube.com/watch?v=iGGOjD_OtAM

[3] https://www.iee.fraunhofer.de/de/projekte/suche/2013/stensea...

Re: Europe's deepest mine to become giant gravity battery

#89

Post by ryukoposting »

fecal_henge wrote: post #60
alkonaut wrote: post #23

Earlier quoted context omitted.

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.

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

Joules? Maybe you're facetious but it's hard to tell over the internet.

Re: Europe's deepest mine to become giant gravity battery

#90

Post by ryukoposting »

stubish wrote: post #42
WalterBright wrote: post #22

Earlier quoted context omitted.

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.

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.

Would you happen to have a link?
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