[rjmunro]

> solar and wind are now cheaper than hydro in many places.

It's not possible to run a country entirely on wind and solar, you need backup for when it isn't windy or sunny.

It is possible to run a country entirely on Hydro. The lake on a hydro electric dam will last for a while - in some cases several months - between needing to be topped up by rainfall.

[jantissler]

Batteries exist.

[lenkite]

Batteries need to be manufactured or imported at expense.

[archagon]

Heh, OP even described a battery in the form of a lake!