NEW YORK - Calpine Corp reduced the 600-megawatt Otay Mesa natural gas fired power plant in California for planned and unplanned reasons by Sunday afternoon, the California ISO said in a report.

The Otay Mesa combined cycle station, which entered service in October 2009, is located in San Diego.

The plant generates power for Sempra Energy's San Diego Gas & Electric utility under a 10-year tolling agreement for the full output of the plant. SDG&E supplies the natural gas fuel and takes the power from the plant.

Combined-cycle technology uses natural gas to turn a combustion turbine to generate electricity and then uses the hot gas leaving the combustion turbine to heat water to produce steam to turn a steam turbine and generate more power.

One MW powers about 700 homes in California.

Calpine, of Houston, owns and operates nearly 25,000 MW of generation in the United States and Canada. (Reporting by Scott DiSavino; Editing by John Picinich)