[sschueller]

We can fill large water dams and store energy easily that way.

This is what Switzerland is focusing on right now to make sure they have enough stored power for January and February when production doesn't suffice the requirements and purchasing electricity from abroad may not be possible.

[Ekaros]

Do we have locations we haven't build those yet? Is there any concerns about building there? Environmental or existing communities? Where to get the water to fill those? Does that have effect downstream? If it is build on existing rivers, is there some minimum amount of water that has to be passed? Or maximum capacity after water has to be passed?

[sschueller]

All valid concerns but if you can find a location that has a small impact on the environment it is hugely beneficial.