The state should have enough power supply to meet peak demand this summer, but San Diego and southern Orange counties are a concern because of the closure of the San Onofre Nuclear Generating Station, the California Independent System Operator reported Friday.

Heat waves, combined with unexpected power plant outages, or wildfires that threaten transmission lines, could present challenges to energy reliability in the region, according to Cal-ISO, which regulates the flow of power around the state.

The San Onofre Nuclear Generating Station, shut down since 2012 and now being decommissioned. Photo courtesy Southern California Edison

The agency said it will count on customers reducing their power use when a Flex Alert is issued.

“We know it is an inconvenience, but if the ISO issues a Flex Alert asking for conservation it is because the grid is under a lot of stress and we need to immediately reduce power demand,” said ISO President and CEO Steve Berberich. “Voluntary conservation is better than people losing power when demand outstrips supply.”

Flex Alerts tips and TV commercials are online at the Cal-ISO website. Flex Alert notifications are available via the phone app ISO Today.

The nuclear plant along the northern San Diego County coastline has been inoperative since January 2012, when a small, non-injury leak was detected. The facility’s operator and majority owner, Southern California Edison, decided in June 2013 to retire the two reactors instead of trying to restart them.

System-wide peak electric demand is expected to reach 47,351 megawatts this summer, which is 646 megawatts more than 2013. The all-time record instantaneous peak demand was 50,270 megawatts in 2006.

The ISO projects that the demand will be covered by 53,950 megawatts of available power capacity, more than 3,000 megawatts more than last summer.

The agency said operating energy reserve margins are good for normal conditions at 24 percent, but could fall to about 14 percent during extremes. That is still above the threshold that puts customers at risk of power outages, which is triggered when reserves drop to 3 percent.

— City News Service

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Chris Jennewein

Chris Jennewein is Editor & Publisher of Times of San Diego.