Why Abandoned Coal Mines Could Become the World’s Biggest Batteries

Abandoned coal mines are being studied as sites for energy storage and heat recovery.

Possible uses include gravity storage, pumped hydro, compressed air storage, and geothermal heat extraction.

Existing mine shafts and tunnels could cut construction needs, but safety and geology remain major hurdles.

The economics and efficiency of each approach are still uncertain, so large-scale deployment is far from guaranteed.