> from renewable sources like solar and wind in order to lift a heavy weight

Solar is very relevant to Finland 

notgeld

> The disused mine will be fitted with a gravity battery, which uses excess energy from renewable sources like solar and wind in order to lift a heavy weight. During periods of low production, the weight is released and used to power a turbine as it drops.

This is really elegant actually. I guess without mines it wouldn't really be possible. Another point for [diggers](https://stacker.news/items/412336).

> A study last year by the International Institute for Applied Systems Analysis (IIASA) estimated that gravity batteries in abandoned underground mines could store up to 70TWh of energy – enough to meet global electricity demands.

That's enough for a *day* of global electricity demand. Annually we do [nearly 23000 TWh](https://www.iea.org/reports/electricity-information-overview/electricity-consumption).