> Just need to pump some water back upstream In this situation, you'd simply never let the water flow through in the first place. This amounts to releasing wa

> Just need to pump some water back upstream In this situation, you'd simply never let the water flow through in the first place. This amounts to releasing water while generating energy, only to pump it back. The net result is just a lot of wasted energy. Pumped hydro requires two reservoirs. There's no way around it.