Via Clean Technica:
The City of Sacramento, California is forging ahead with plans to construct a 400 megawatt battery made entirely out of water. That almost sounds like some kind of high tech miracle but it’s not. Water batteries, aka pumped hydroelectric facilities, use established technology and old fashioned gravity.
Pumped hydro is currently the only utility-scale energy storage technology in common use globally, including in California and the US. Another new pumped hydro project is already in the works for California, so you’re going to hear a lot more about pumped hydro in the future.
Why Pumped Hydro?