Pumped storage hydro (PSH) is a mature technology that includes pumping water from a lower reservoir to a higher one where it is stored until needed. When released, the water from the upper reservoir flows back down through a turbine and generates electricity. There are various configurations of this technology, including open-loop (when one or more of the reservoirs are connected to a natural body of water) and closed loop (when both reservoirs are separate from natural waterways). Existing turbine technologies also offer different features and capabilities, including fixed speed, advanced speed, and ternary.