The German government has a plan for what to do with closed mines, of which coal is no longer needed. Instead of filling the excavated windows, it will turn them into a highly efficient hydroelectric plant.
Almost the whole world is definitely turning away from coal as a raw material for electricity generation, as it emits too much pollution that threatens human life.
The Germans also close their mines, which are no longer useful, but do not intend to overwhelm them because they have a much better idea of their use. As reported by Bloomberg, in 2018, when the government's coal mining subsidies run out, the Prosper-Haniel mine in North Rhine-Westphalia will close. Instead of filling up the windows, they will be transformed into a hydroelectric power plant equipped with pumps.
A new power plant will produce electricity by releasing water that will flow to the lower tank to turn the turbines. Then the water that flows to the bottom of the tank will be pumped back to the upper reservoir for some time.
It will not be the main way to power a nearby city, but rather a spare system used if needed, which will deliver 200 MW of energy. If the project proves successful then more closed mines in the region will be transformed into power plants.