> an array of ten 10-ton concrete blocks lifted 10m in the air could power a house for a day

No, that's only 2.7 kWh. Most homes use 10-20 kWh/day. A battery of that size is easily under $1k. Good luck building your ridiculous concrete block system for that.

Batteries are really good. Gravity, not so much. It only works when you can lift & store a tremendous amount of stuff "for free" because nature has done most of the work, e.g. in valleys, mountains, aquifers, caves, etc. If you have to build the whole thing it will never be viable.

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parpfish 2 days ago | parent | next [-]

Batteries are good, but you can’t repair a broken battery with odds and ends you find at the hardware store. If you’re living off grid space isn’t really an issue.

	▲	lawlessone 2 days ago \| parent [-]
		I am not sure you want to repair something holding one ton blocks in the air with odds and ends.

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avalys 2 days ago | parent | prev | next [-]

I’d love to buy a 20 kWh battery for under $1k. Can you give me a link to what you’re thinking of?

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IshKebab 2 days ago | parent | next [-]

Sorry my wording was ambiguous; when I said "that size" I meant 2.7 kWh, which is what the hypothetical concrete blocks might provide.

Nevertheless, you can get a 16 kWh battery (which is enough for most days of a typical house) for only £2k, which is kind of insane really: https://www.fogstar.co.uk/products/fogstar-energy-16kwh-48v-...

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jmpman 2 days ago | parent | prev [-]

People have been able to get their Tesla Model 3 batteries (75kWh iirc) replaced with used battery packs for around $5k, so quite close to what you’re asking.

	▲	lawlessone 2 days ago \| parent [-]
		Do they get much for the old used battery? the materials are still lithium etc are still inside it, they're just no longer in the right places..

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_zoltan_ 2 days ago | parent | prev [-]

where can I get a 20kWh battery for 1k USD?

here in Switzerland 1kWh is 1k CHF.