Man's innovation, when will it end? What's done is done, but we shouldn't be boring new holes, rather horizontal and vertical dams for the use of. If we were tenants, we would have been evicted a long time ago.
Jaymack
https://www.businessinsider.co.za/gravitricity-plan-to-turn-south-african-mine-shafts-into-grid-batteries-2019-10