Variable Currents

Hydro generators are currently a bit overpowered as currents are plentiful and the generators provide consistent good power. To give it a niche, it’d be nice if currents varied in strength over long periods of time (to differentiate it from variable solar energy). I personally believe this would encourage more strategizing and usage of different power systems which fill different niches. (i.e., solar is predictable but variable and weak, thermal is limited but consistent and decent, hydro could be unpredictable and variable but decent, and bio is decent and on demand but requires player intervention.)