An old Kentucky coal mine will soon be turned into a pumped hydro “water battery” in an ambitious renewable clean energy scheme. Hydropower developer Rye Development is transforming a strip mine in southeastern Kentucky’s Bell County into the Lewis Ridge pumped storage project. While a lithium-ion battery holds power for a few hours, pumped hydro storage can hold energy long-term. It works by pumping water uphill to a reservoir during low-demand times, then releasing it downhill to run turbines when electricity needs are high. Open systems release stored water one way into the local waterway. Closed-loop systems, such as Lewis Ridge, recycle the water endless times.