Pumped Hydro Is the Best Form of Grid Energy Storage

In the U.S., hydroelectric is 6% of our energy production, and we only have capacity for about 50%. "There's only so many locations of blah, blah, blah" in the world that can produce this kind of power. In closed loop pumped hydro, you don't need a river but two reservoirs of water with a good head. You could also just fully make it a close loop - like you could close it off.