No blackouts, but Californians told to conserve again Friday – and ‘pre-cool’ their homes

California avoided rolling blackouts Thursday but the manager of its power grid issued another Flex Alert for Friday night, urging residents to curtail electricity usage during critical evening hours.

With temperatures expected to hit 110 degrees in greater Sacramento and much of the Central Valley, the California Independent System Operator said a Flex Alert would take effect for a second night in a row, this time from 6 to 9 p.m.

A Flex Alert is a plea for voluntary conservation; residents are urged to turn thermostats to 78 degrees or higher, turn off unnecessary lights and avoid using heavy appliances between 6 and 9 p.m. Those early-evening hours are when the grid is most vulnerable, as solar power diminishes but temperatures remain high.

PG&E Corp. and other utilities urged residents to “pre-cool” their homes earlier in the day by turning their thermostats down or running fans. The idea is to make homes comfortable enough so it won’t be so onerous to turn the thermostats back up when the Flex Alert kicks in later in the day.

Gov. Gavin Newsom has declared a state of the emergency, allowing power generators to ramp up production even if it means exceeding air-pollution standards.

The grid manager said it was able to get through Thursday’s heat despite losing 1,100 megawatts of power unexpectedly. The loss was partially offset by emergency supplies delivered from outside the grid, including power shipped by the Los Angeles Department of Water and Power.

Demand Friday is forecast to peak at 41,334 megawatts, slightly below Thursday’s, but “we wanted to remain cautious,” the Independent System Operator’s chief operating officer, Mark Rothleder, said Thursday evening.

Thursday evening, even as Rothleder was telling reporters that blackouts weren’t likely, PG&E Corp. warned that power could be shut off for 121,000 households and business. PG&E spokeswoman Karly Hernandez said the utility issued the warning so customers “can prepare and plan accordingly” in case the lights went out.

But that increased buffer will be at least partially offset by a significant decrease in hydro power, which normally produces more than 10% of the state’s power, because of the drought. A major power plant at Lake Oroville is expected to go completely offline in August because of low water levels in the reservoir.

This story was originally published June 18, 2021 at 7:22 AM.