PG&E Calif. Helms 3 hydro unit back

NEW YORK, July 2 (Reuters) - The 404-megawatt Unit 3 at PG&E Corp's (PCG.N: Quote, Profile, Research) Helms hydropower station in California returned to service on Wednesday, a spokesman for the company said Thursday.

The unit had shut by about Sept. 28 for planned maintenance.

The 1,212 MW Helms pumped storage hydropower station, which entered service in 1984, is located near Fresno, in Fresno County. There are three 404 MW units at the station.

One MW powers about 700 homes in California.

All of the other units remained available for service.

Pumped storage plants store and produce electricity to supply peak power demands by moving water between reservoirs at different elevations.

At times of low demand and low power cost, the plant uses electricity from the grid to pump water into the higher reservoir. When demand and prices are higher, the station releases the water back into the lower reservoir through a turbine, generating energy.

PG&E's regulated Pacific Gas and Electric Co subsidiary owns and operates the station.

PG&E, of San Francisco, owns and operates more than 6,200 MW of generating capacity, markets energy commodities and transmits and distributes electricity to almost 5.3 million customers and natural gas to 4.2 million customers in northern California. (Reporting by Scott DiSavino; Editing by Walter Bagley)