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The Potrero Generating Station was a natural gas and diesel burning electricity generating station owned by Mirant and located on a site in Potrero Point, San Francisco, California. The plant's primary power source was a 206 MW, natural gas burning steam turbine providing baseload power and referred to as "Unit 3". In addition, three 52 MW peaking power diesel generators provided additional power during times of highest consumption. Since the closure of the Hunters Point Power Plant in 2006, Potrero was the last remaining fossil fuel power plant within the confines of San Francisco, with capacity to provide approximately 1/3 of the City's peak electrical power needs. On Dec. 21, 2010, San Francisco Mayor Gavin Newsom announced that the Potrero plant would cease operations by the end of the year. In a press conference announcing the closure, Newsom stated that "this is a monumental step towards cleaner air, environmental justice and our future of renewable energy and healthier communities."〔("San Francisco's Potrero power plant to shut down Dec. 31" ), San Francisco Business Times BizTalk blog, Dec. 21, 2010.〕 The plant was shut down in January 2011, and the property is being considered for redevelopment. ==History and capacity== The Potrero power station was located at a site in Potrero Point originally used by San Francisco Gas Light, a provider of gas for cooking and lighting in the late 19th century. Circa 1890 they constructed a small electrical generator at the site, which was the first power plant for the company that would later become Pacific Gas and Electric. Unit 3 was constructed in 1965, making it one of the oldest power plants still operated in California until its closure. The peaking units 4, 5, and 6 were constructed in 1976. Unit 3, the primary power generator, consisted of an eight story natural gas powered boiler that produced superheated high pressure steam. San Francisco Bay water was purified and heated to produce high pressure steam. This steam was run through a turbine that subsequently turned a 206 MW generator made by Westinghouse. The steam that exited the turbine was then cooled to allow it to condense back into water. The cooling water used in this process operated on a once-through exchange with San Francisco Bay. At full power approximately 10 m3/s (226 million gallons per day)〔(SF City Attorney description of Potrero )〕 of water were pumped from the subsurface of the Bay, passed through screens and filters to remove debris and prevent biological uptake. The cooling water then passed through the condenser to cool steam used to power the steam turbine. The water was returned to the Bay at about 10 C warmer, usually no warmer than 30 C (86 F).〔California Environmental Protection Agency. San Francisco Bay Regional Water Quality Control Board. ("Waste Discharge Requirements for Mirant Potrero, LLC, Potrero Power Plant." ) Order No. R2-2006-0032; NPDES Permit No. CA0005657. May 10, 2006.〕 In addition to the main unit, three 52 MW diesel powered peaking generators could be brought online in four minutes and to peak load in ten minutes notice to meet extra electricity demands as specified by the California Independent System Operator. They were generally operated for only a few hours at a time, usually during peak power consumption in the afternoon. In total, they were generally utilized less than 200 hours per year, though they could be online longer if Unit 3 was offline for an extended period (for example due to maintenance). Fuel for these generators was stored on site and was delivered by tanker truck, though in the past it was delivered directly by ship. There were three large fuel storage tanks at the Potrero facility. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Potrero Generating Station」の詳細全文を読む スポンサード リンク
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