It's a great solution if you happen to have the right geography for it. Not everyone does. And many countries have built out most of the suitable hydro sites already.

Agree 100% check this baby out :-)
https://www.verbund.com/en-at/about-verbund/visitors-centres/kaprun
This should be a template. Every lake or river can do something similar (at scale)
In Kaprun they used nature to help them out, it's brilliant.