TEPCO owns 160 hydroelectric power stations and its total capacity is 8,520 MW. Although hydroelectric power was once a main source of energy, the ratio of hydroelectric to thermal power has been reversed since 1959, and it accounts for approximately 7% of TEPCO's electricity output. Despite its comparatively low output, pumped storage power plants play a critical role in meeting daily peaks in demand as a means of producing electrical power in a short period of time and their outputs cover 75% of total hydroelectric power output.
