31–40 of 118 posts
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.
Earlier quoted context omitted.
Allow me to support the completely unsupported naysaying: https://cleantechnica.com/2024/01/16/gravity-storage-101-or-... Cliff's Notes: any currently-considered form of gravity storage that isn't pumped hydro is orders of magnitude more expensive and more stupid than a Tesla Megapack. Michael Barnard's abrasive tone aside, is he wrong?
They aren't building it from scratch.
Earlier quoted context omitted.
> 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.
Allow me to support the completely unsupported naysaying: https://cleantechnica.com/2024/01/16/gravity-storage-101-or-... Cliff's Notes: any currently-considered form of gravity storage that isn't pumped hydro is orders of magnitude more expensive and more stupid than a Tesla Megapack. Michael Barnard's abrasive tone aside, is he wrong?
> The alternative idea is to put a lot of sand on a single elevator with huge winches that just goes up and down in a big, deep mine shaft. This one at least has the potential to be viable.
Earlier quoted context omitted.
Allow me to support the completely unsupported naysaying: https://cleantechnica.com/2024/01/16/gravity-storage-101-or-... Cliff's Notes: any currently-considered form of gravity storage that isn't pumped hydro is orders of magnitude more expensive and more stupid than a Tesla Megapack. Michael Barnard's abrasive tone aside, is he wrong?
From your link: > The alternative idea is to put a lot of sand on a single elevator with huge winches that just goes up and down in a big, deep mine shaft. This one at least has the potential to be viable.
Earlier quoted context omitted.
> 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.
Allow me to support the completely unsupported naysaying: https://cleantechnica.com/2024/01/16/gravity-storage-101-or-... Cliff's Notes: any currently-considered form of gravity storage that isn't pumped hydro is orders of magnitude more expensive and more stupid than a Tesla Megapack. Michael Barnard's abrasive tone aside, is he wrong?
Fengning Pumped Storage Power Station stores 40 GWh and cost 2 billion or 20 Wh/USD
Tesla megapack 2 stores 3.8 Mwh = Costs 1.5 million, or approximately 2.6 Wh/USD
It seems like pumped hydro is about an order of magnitude cheaper.
https://en.wikipedia.org/wiki/Fengning_Pumped_Storage_Power_...
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.
You might be surprised how few sites are suitable for pumped hydro and how costly it is to build. I can easily see this being both cheaper and more efficient. Most pumped hydro installations outside of northern Europe end up requiring large dams to create a big enough impoundment uphill. A direct weight solution should have better conversion efficiency as well, Gravitricity quotes 80% which is on the high end of pump…
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 for pumped hydro, due to the Basin and Range geography. Here's a project going forward right now. Look how tiny the basins are for the energy stored:
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 i…
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.
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…
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 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.