The Potrero power plant could be shut down entirely by the end of February, the Guardian has learned. According to a report prepared for the Dec. 15 meeting of the California Independent System Operator (Cal-ISO) Board of Governors, an energy regulatory body, the aging power plant will soon be released from a Reliability Must-Run (RMR) contract requiring its continued operation for grid-reliability purposes.
“The ISO will provide an RMR termination notice to Mirant at the end of this month or in early January,” the report states, “which would terminate the RMR agreement by February 28, 2011.”
In August of 2009, San Francisco City Attorney Dennis Herrera reached an accord with Mirant Potrero LLC, the company that owns and operates the Potrero Power Plant, to shut down the plant by Dec. 31, 2010. Although the company agreed to the terms of shuttering the plant by the end of this year, there was a catch -- the Cal-ISO would first have to terminate Mirant Potrero’s RMR contract. Apparently, that won’t happen till early next year, but this latest Cal-ISO report marks the first time the agency has committed to a specific date.
The Potrero power plant won’t be a necessary power source for San Francisco now that a new energy transmission line has been installed. The Trans Bay Cable, a 53-mile submarine power line that can transmit 400 megawatts of electricity from a Pittsburg substation to San Francisco, became fully operational on Nov. 23.
“The Trans Bay Cable finished its testing successfully and was put into successful service,” spokesperson P.J. Johnston told the Guardian. Meanwhile, a PG&E re-cabling project deemed important to San Francisco’s electricity reliability was completed Dec. 5.
“Having both of these projects completed and proven operationally reliable were the two key conditions for enabling the ISO to release the entire Potrero power plant from its reliability must-run contract obligation,” the Cal-ISO report notes.
Removing the Potero power plant from service will benefit San Francisco’s air quality, particularly in the city’s southeastern neighborhoods.