Energy Vault Gravity Based Energy Storage

This has been an ongoing, though infrequent topic in other corners of the engineering fora, but I’d rather talk about it here on SE. Here are some of the links associated with it with most recent news first:

Energy Vault, Atlas Renewable and China Tianying Announce $100 Million Transaction With Further Upsized Pipe, Licensing and Royalty Agreement, and Initial 100MWh Project to Drive Decarbonization in China

Gravity-based energy storage tower developer notches a customer order

Not all that technical, but entertaining commentary:

I am surprised at just about every update to this company that isn’t about it cancelling contracts and folding. The concept just seems so overly complicated to me for gravity based energy storage,

I have seen it mentioned, and watched (well skipped through, reading the captions) the 2nd video. They mention several so-called drawbacks and think pumped hydro would work better: that the concrete blocks are expensive-ish (and concrete releases a lot of CO2 at its start of life), trouble could arise trying to use the system in high wind conditions due to cranes and cables being buffeted…maybe some others.

They don’t mention the big drawbacks of pumped hydro:
you need more footprint (acres of land) to build impoundments (because water is less dense, thus less energy content per acre-foot or whatever measure you want), major leakage of water could be catastrophic to downstream communities, and the amount of concrete you need to build a retaining structure for the water would likely be similar (kWh to kWh) for either one.

It does seem more complex, and it seems limited in the surge power it could provide due to dead time (the time required to cycle the cranes to new positions and start dropping another block).

Yeah he glosses over the negatives of traditional stored hydro for sure. He co-opted this idea using hydro rather than blocks though by suggesting basically a massive pit, filled with water, and holding tanks above ground.


There are a ton of complications with that as well, but where would the fun be if there weren’t?

Maybe locate them over abandoned mines or something similar if possible? If the water doesn’t become contaminated somehow, could you forego sealing the chamber it and let it exchange into the ground water to whatever depth the water table sits?

Locating over mines? Hmm, maybe. But you’d have to line the mine walls, otherwise the water would keep eroding the walls until the whole thing collapses into a sinkhole. Benefit - the sinkhole would be a new lake, you could plant fish in it.

Also he shows “water tanks” on some kind of scaffold. A fairly inefficient way to impound the water, on a material needed basis. Why not a large concrete tank? Or better, a lined earthen dam? Oh yeah, not a lot of naturally occurring sites with enough vertical drop to make it economical, and it ties up a lot of acreage.

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This idea overcomes some of the disadvantages of his scaffold over a pit idea:

Some issues surrounding its application as well - like how do you manufacture and install a rolling diaphragm that big?

Woah, yeah. That concept art makes it looks immense beyond what anyone would accept.

I forget where I saw it mentioned, but I do recall someone questioning why they were using traditional cranes to make cylindrical towers where gantry cranes constructing large cubical structures would abate a lot of the potential downfall of the planned design like wind, crane mobility, and overall tower safety.

So, if an ice storm welded the concrete blocks together . . .

Or, an earthquake toppled the tower . . .

I see several opportunities for Murphy’s Law on this.

There was an energy storage idea I saw several years ago that involved an electrified rail line up a hill. With a rai yard at the top and bottom of the hill. Energy storage was by moving heavy loads up and down the hill .
I guess that didn’t gain much traction either.

You mean this one? Sounds like they might still be in business…but their last news posted on their website was in Oct. 2020…

I actually have a gravity based energy storage device in my home:


Until very recently it has worked quite well!

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I’ll give you three guesses what’s in the tower in this picture.

An arrowslit?

I assume an old water tower if that is an old converted utility building.

Sewer pump?

Hydraulic accumulator (at least, it did until it was replaced with the one inside this nearby tower - subsequently supplemented by the one you can see outside the tower).

So…water hydraulics for dam/waterworks valvegear?

The Pump House

As linked by Latexman, it runs the lock gates and lifting bridges around Bristol Harbour.

There’s a little exhibition in the Underfall Yard showing how it works. A nice touch there is the accumulator, where you’re invited to stand on top of a platform to take the place of the 70 tonnes or so of scrap iron that pressurises the system.

That’s pretty cool.

At one point I considered a monster concrete block in my back yard to store energy. Simple. Brute force. Then I did the math on how much energy it could store… I was shocked at how little.