California grid operator calls for voluntary conservation

The California Independent System Operator said in issuing the "Flex Alert" that high temperatures were pushing up energy demand, primarily from air conditioning use, and tightening available power supplies.

"Additional Flex Alerts are also possible through the Labor Day weekend as record-setting temperatures are forecast across much of the West," Cal ISO said.

The grid operator had said Tuesday that the need for voluntary conservation would be likely through the holiday weekend. It said it was taking measures to bring all available energy resources online, including issuing an order restricting maintenance from noon to 10 p.m. daily through Sept. 6.

The peak load for electricity demand in California is projected to exceed 48,000 megawatts on Monday, the highest of the year, the grid operator said.

The afternoon and evening time period for voluntary conservation is when there is most stress on the grid and solar energy production is declining. The primary ways to reduce household energy use are to raise thermostat temperatures, avoid using major appliances and electric car chargers, and turning off lights.

"If weather or grid conditions worsen, the ISO may issue a series of emergency notifications to access additional resources and prepare market participants and the public for potential energy shortages and the need to conserve," Cal ISO said Tuesday.

The heat wave arrived amid concern about California's power grid. In August 2020, a record heat wave caused a surge in power use for air conditioning that overtaxed the grid. That caused two consecutive nights of rolling blackouts, affecting hundreds of thousands of residential and business customers.

Gov. Gavin Newsom has proposed extending the life of the state's last operating nuclear power plant by five years to maintain reliable power supplies in the climate change era. The proposal would keep Pacific Gas & Electric's Diablo Canyon Nuclear Power Plant running beyond a scheduled closing by 2025.

Forecasters, meanwhile, warned of triple-digit temperatures with little overnight relief, as well as elevated risk of wildfires in much of the West.

"The big weather story this week will be a prolonged and possibly record heat wave building across much of the Western U.S. associated with a strong upper level ridge," the National Weather Service wrote.