SAN FRANCISCO (Map, News) - Mayor Gavin Newsom asked city legislators to delay a vote on a controversial plan to build a new power plant in Potrero Hill that will replace an older, more polluting plant, saying he needs another week to work on an alternative strategy.

The Board of Supervisors was scheduled to vote today on a proposal to borrow $273 million to build natural-gas-burning power plants in The City’s southeast and at the airport, but Supervisor Sophie Maxwell, the legislation’s sponsor, said Monday that she had agreed to the mayor’s request for a postponement.

The state agency charged with ensuring that Californians have reliable electricity supplies, the California Independent Systems Operator confirmed in a May 1 letter to the San Francisco Public Utilities Commission that The City’s plan for the new power plant was “the best mechanism” for retiring the old Potrero power plant. The plan to build the cleaner power plants and take other steps to replace the Mirant plant was approved by the agency in November 2004.

Opposition, to the plan, has grown in recent months, however, with groups including the Sierra Club, the San Francisco Planning and Urban Research public policy nonprofit and the Bay Area Ella Baker Center for Human Rights expressing a desire for a more renewable, less polluting option than a fossil-fuel plant.

Newsom, who agreed in November to fast-track development proposals on Mirant’s land and waive millions of dollars in city fees if the company closed the plant, told The Examiner on Monday that while he wants to close Mirant, he is “desperate” to avoid building new fossil-fuel-burning plants.

“I don’t want to live to regret this decision,” Newsom said. “We may look like fools five years from now.”

Newsom said he will try to come up with an “aggressive” alternative plan to install new technology at the Mirant-owned plant to reduce pollution, increase electricity imports from a plan in the works to bring power into The City through a Transbay Cable, create more electricity from renewable sources and reduce in-city electricity demand.

San Francisco Public Utilities Commission General Manager Ed Harrington told supervisors last week that SFPUC staff hadn’t filed proposals with the California ISO to take different steps to replace the Mirant plant because discussions indicated they would have “no chance of success.”

jupton@sfexaminer.com