Contingency plan for Southern California power back on track

California’s energy grid operator announced that two mothballed generators at a natural-gas-powered plant on the Huntington Beach coastline are back in service, a critical piece of the plan to replace power from the shuttered San Onofre nuclear power plant this summer.

San Onofre has been shut down for three months because of equipment issues, and it’s unclear when it will return to operation.

Officials have expressed concern that in the event of a heat wave or transmission outage, parts of Los Angeles County, south Orange County and San Diego County could face power shortages over the summer without the plant’s 2,200 megawatts of energy.

The nuclear plant produces enough electricity for about 1.4 million homes, but on top of that, officials said it provides voltage support that allows power to be imported from elsewhere to serve Southern California.

The two units at the AES Huntington Beach plant — which are being brought temporarily out of retirement — will provide about 440 megawatts to the Los Angeles Basin while giving voltage support to allow power to be imported into the San Diego area, California Independent System Operator spokeswoman Stephanie McCorkle said.

“This is a critical component of the plan for summer should the San Onofre units continue to be offline, or even if there is a partial return to service,” she said.

The contingency plan also includes speeding up transmission upgrades. Customers will be called on to conserve power as well.

The Huntington Beach units may operate through October, when they will have to be shut back down so the new Walnut Creek plant in the city of Industry can take over their emission credits.

Earlier this month, Southern California Edison officials expressed hope that San Onofre could be back online and running at a reduced capacity in June.

But the chairman of theU.S. Nuclear Regulatory Commissionsaid talk of restarting the plant was “premature” because Edison has not yet submitted a plan to the commission, and Edison followed with a statement in which it said there was no timeline for a restart.

San Onofre has been out of service since Jan. 31, when one of the nearly 39,000 steam generator tubes that carry radioactive water for heat transfer to help generate power sprang a leak.

The plant was shut down, and officials later discovered that hundreds of tubes were showing premature wear; apparently the flow of steam caused vibrations that made the tubes rub against each other. More than 1,300 tubes have been taken out of service because of wear.

abby.sewell@latimes.com