Round-trip energy efficiency is reported to be > 80% for pumped-hydro energy storage. Ecological, space, and financial efficiency are more variable. http://en

Round-trip energy efficiency is reported to be > 80% for pumped-hydro energy storage. Ecological, space, and financial efficiency are more variable. http://energystorage.org/energy-storage/technologies/pumped-hydroelectric-storage http://energystorage.org/energy-storage/technologies/pumped-...