In university I learned, that Germanys geographic potential for Pumped #hydropower is exhausted. Now I learn, that people use a cavern as a lower reservoir. Makes me wonder if there is more "hidden" potential.
Article in German:
https://taz.de/Neues-Pumpspeicherkraftwerk/!6134239/
Article in German:
https://taz.de/Neues-Pumpspeicherkraftwerk/!6134239/