9 Comments

I love how whenever someone looks at "gravity storage" in any detail, the conclusion always is that it's just a much worse version of pumped hydro

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Great analysis. Versions of this philosophy is happening all over the place, CCS, DAC, etc. "But don't worry about the costs or inefficiencies, we've got to get on this now!" Now, referring to government grants & subsidies.

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It's always sucking off the Govt teat in this situation.

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Your numbers are correct. And you did the criticism without saying how long it would take to match the embodied energy of the materials needed to make a gravity battery. Build a better building in the first place is the correct answer. I can't figure out why not burning energy is not considered a better strategy building more power sources, even renewable ones.

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I could never have figured out the embodied carbon for anything but the block, (6.3 tonnes or so) but I bet the couple of hundred meters of cable alone will be greater than that.

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Try using rails instead similar to how the mining trucks that are electric work. Heavy object goes down hill and charges the motor, object gets removed and then goes back up. Mass = 100,000 kg (using lead, tungsten, or similar dense material)Height = 500 m (typical mine shaft or skyscraper height) [ PE = 100,000 \times 9.81 \times 500 = 490,500,000 \text{ Joules} (or 490.5 MJ) ]

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If you made the weights only 3-4’ deep and tall, and twice as heavy.

If you used rock instead of concrete.

If you put them into elevator shafts that are planned to be 3-4’ deeper.

If you powered them with the excess heat of the building.

That’s off the top. The numbers can be changed a lot.

If there are 10 elevator shafts: = 450 kWh by Lloyd’s numbers.

No lithium (although natrium is the future).

My point is that making scenarios and tweaking everything can result in really big differences. I’m sure you all know that …

My other point is that there is a place for saying ‘maybe’ in most cases. At least some aspects of most ideas are useful.

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I think that another reason why someone would want to do this is to take energy generation within the company. Corporations will take any chance they get to slim the outgoings in order to generate a profit. And while this isn't enough to be meaningful, it's a step in them being able to cut one of the outgoings to the electric company and grid. Being an American, I think that I have a slightly different viewpoint on the bloat that encompasses buying electricity. Not only do I pay a premium to purchase green power (and it's not terribly transparent where my power is coming from, and I use the least egregiously ambiguous green power company), I pay more for transmission and 'being tied to the grid" than I do for the power I'm using. I think that I would be less annoyed about this if there were improvements to the system that were improvements and less maintaining an aging infrastructure. The call to solar is strong, but it's a large upfront investment, and both my location and my roof aren't conducive to panels. So I 'get' the idea that any way you can not pay someone else for your electricity is attractive.

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"And while this isn't enough to be meaningful, it's a step in them being able to cut one of the outgoings to the electric company and grid."

Cutting unnecessary costs, without cutting quality (yes, on sometimes on a relative basis) is always a good thing. I doubt that the cost of building and provisioning the gravity shaft, under the Total Cost of Ownership (Lloyd doesn't mention maintenance but it surly exists), is worth the $5/day number that Lloyd quotes.

In fact, I'm guessing that they are "paying" for the price of the PR splash (e.g., "Look what we did! Give us a plum!".

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