PG&E Corporation's (PG&E) 404-megawatt (MW) Units 1 and 2 at the Helms Pumped Storage hydropower station in California has been shut for planned reasons from March 1, 2009. The 1,212 MW Helms station is located near Fresno in Fresno county. There are three 404 MW Units 1-3 at the station. Unit 3 was shut on September 28, 2008 for planned reasons. All of the other units are available for service. PG&E's subsidiary Pacific Gas and Electric Company owns and operates the station.
The Helms station was commissioned in 1984.
One MW is sufficient to power about 700 homes in California.
Pumped storage plants store and produce power by moving water between reservoirs at different elevations.
During low demand and low power cost, the plant uses electricity from the grid to pump water into the higher reservoir whereas during higher demand and prices, the station releases the water back into the lower reservoir through a turbine, generating energy.