Also, the dams silt up over time anyways, so unless you dredge them they are not very good at generating power if the river generates enough silt. Pumped hydro

Also, the dams silt up over time anyways, so unless you dredge them they are not very good at generating power if the river generates enough silt. Pumped hydro is more promising in this regard; they don't have to be in the river course itself, so do not run into silting issues, or block fish migration, or any of many other negatives. And because they are basically only required to be battery storage in hours, days or weeks rather than a main source of power generation, they can also be much smaller.