major rivers never stop flowing In a drought - one has clear...

major rivers never stop flowing

In a drought - one has clear skies and lots of sun

so a river can steadily load up a centrifuge and once it is fully loaded, they take very little power to keep at top storage level.

the point about rivers is that gravity reloads the force for you

so that the energy you pinch up stream - is reloaded a little way down the river again and can be freshly harvested