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Finnish City Inaugurates 1 MW/100 MWh Sand Battery

(cleantechnica.com)
190 points erwinmatijsen | 3 comments | 03 Sep 25 06:00 UTC | HN request time: 0.221s | source
1. bjoli ◴[03 Sep 25 08:49 UTC] No.45113573[source]▶
90% roundtrip efficiency is pretty darn cool. I am not an engineer, but is it the high temperature difference that makes that possible?
replies(2): >>45113692 #>>45113760 #
2. smokel ◴[03 Sep 25 09:07 UTC] No.45113692[source]▶
That's only in heat transfer, that does not include generating electricity from it.
3. IshKebab ◴[03 Sep 25 09:17 UTC] No.45113760[source]▶
I think they're talking about thermal efficiency (since this is a thermal battery, not an electrical battery). 90% of the heat they put in, they get out again. Probably all you need is good insulation.