Pumpspeicherkraftwerke. We have 31 of them in germany. Which is pretty much the maximum possible because you can’t build them just everywhere. And quick search says these things are economically unsustainable because of the extremely high construction costs but very low revenues. It is wasted money.
My wording was poorly chosen. You are right of course. Its not a waste in that sense. But when better alternatives are available, which will hopefully soon achieve an acceptable level of efficiency, it makes no sense to build more. Apart from the space problem.