RAG’s Prosper Haniel coal mine could produce hydropower in the not too distant future. North-Rhine Westphalia State Governor Hannelore Kraft has declared her support for a project that would convert the Prosper Haniel coal mine into a pumped storage facility. There has been a longstanding idea to convert mine shafts to hydro chutes and produce green power.The mine would become a type of battery, it would use excess wind or solar energy to pump water from a reservoir at the depths of the mine to another reservoir above the shafts. When wind or solar fails to meet demand, the water would be released, falling some 1,300 m to electricity-generating turbines.A 2014 article on Grist.org said the mine could store up to about 990,000 m3 of H2O, “roughly the volume of the Empire State Building.” That could produce a 200 MW capacity, enough to power more than 400,000 homes, Bloomberg reported.Prosper Haniel is expected to be exhausted as a coal mine in 2018, when federal subsidies for the industry expire. Other mines could follow this reincarnation as the coal mining region of North-Rhine Westphalia intends to double its production of renewable energy to 30% by 2025, Bloomberg stated.