Flex Alert extended to 10 p.m. as California heat wave threatens blackouts, energy ‘deficits’

The managers of California’s power grid issued another Flex Alert for Monday and warned that blackouts were possible later in the day as a punishing heat wave sends electricity consumption into near-record territory.

The Labor Day Flex Alert was in effect from 4 to 10 p.m., an hour longer than usual, underscoring the increasingly dicey conditions on the electricity grid as the heat wave intensifies.

Elliot Mainzer, chief executive of the Independent System Operator, said Sunday the grid was looking at significant shortfalls in electricity in the days ahead.

“We are looking at deficits for tomorrow, Monday, in the 2,000 to 4,000 megawatt range between the hours of 5 p.m. and 10 p.m.,” he told reporters. That could take as many as 3 million households offline.

“Obviously the chances of ... of interruption of electrical service are higher than they have been so far.”

The Independent System Operator, which manages the state’s power grid, put a Flex Alert in effect for Monday afternoon and evening, marking the sixth straight day of begging Californians to turn up their thermostats and ramp down their energy use to prevent blackouts.

But Mainzer said it’s almost a certainty that stronger measures will be needed in the coming days to avoid rolling blackouts of the sort California experienced in 2020. Those include power curtailments for commercial and industrial customers who have so-called interruptible rates, in which they receive cheaper power but agree to have their energy use curbed during crunch times.

Mark Rothleder, the ISO’s chief operating officer, said Californians have done an admirable job so far of responding to the Flex Alerts. “We are going to need people to step up and sustain those efforts,” Mainzer said.

Energy demand was expected to peak sometime Monday evening at 48,817 megawatts.

The biggest crunch on the power grid is expected Tuesday, when temperatures in the Sacramento Valley could reach 115 degrees. Mainzer said electricity demand could top out at 50,099 megawatts.

That would be just shy of the record 50,270 megawatts consumed July 24, 2006. The state avoided blackouts that day, but California’s power portfolio has changed considerably in the past 15 years, creating new areas of vulnerability.

In particular, California’s increasing reliance on solar power and other renewable sources has made the grid susceptible to blackouts in the early evening, when solar panels go dark but the weather stays hot. The state had two straight nights of rolling blackouts in August 2020 and nearly had a repeat during the July 2021 heat wave.

During a Flex Alert, Californians are urged to cool off their homes ahead of time and then turn up thermostats to 78 degrees. They also are asked to defer using heavy appliances.

“We know this has been a long haul,” Mainzer said, “and it’s going to get more difficult.”

Temperatures are expected to stay well above 100 degrees in the capital region for the bulk of the week after the National Weather Service extended its excessive heat warning through Thursday night.

In addition, air quality managers issued the year’s fourth Spare the Air alert for Monday, as the heat is expected to keep ozone levels unhealthy for sensitive groups. Before the heat wave, the region had just one alert day in 2022.

This story was originally published September 4, 2022 at 12:50 PM with the headline "Flex Alert extended to 10 p.m. as California heat wave threatens blackouts, energy ‘deficits’."