Energy officials brace for another summer without San Onofre

Energy officials expect to get through another summer without blackouts even if the San Onofre nuclear plant remains shuttered -- but damaging fires in the months ahead could undermine that prediction.

An assessment released Monday by the California Independent System Operator, which oversees most of the state’s power grid, projected that power supply will be slightly tighter this summer than last in Southern California.

That is largely because two retired units at a gas-fired plant in Huntington Beach that were brought online last summer to help replace the power generated by San Onofre will not be available this summer.

Instead, the units are being converted to “synchronous condensers,” which provide voltage support to facilitate importing more power from outside the region. That project is expected to be online by the end of June.

Between that project and other transmission upgrades, the report projected that even during a 1-in-10-year heat wave, the Southern California region will still have a 6% reserve margin -- above the 3% margin that could lead to localized outages.

But the report cautioned, “If critical high-voltage transmission lines are out of service, due to wildfires ... deficient voltage levels may occur under peak load conditions that could trigger localized customer outages.”

“I’m pretty concerned” about the fire danger, CAISO Chief Executive Steve Berberich said. “... There’s just a whole lot of transmission that runs into Southern California through remote areas where those fires usually occur.”

In 2007, CAISO declared an energy emergency because of wildfires that took out transmission lines around San Diego. The recent wildfires in the Inland Empire and Ventura County did not threaten transmission lines.

Energy officials credit conservation by customers during some of the hottest days last summer with helping to keep the lights on and asked that customers again heed calls for conservation this summer.

San Onofre has been offline for more than a year because of equipment issues. Last week, plant operator Southern California Edison raised the possibility that it could retire the plant for good if federal regulators do not give the go-ahead on a proposal to bring one unit back online at partial power.

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Twitter: @sewella

abby.sewell@latimes.com