California’s grid operator forecasts an energy deficit of 2,000 to 4,000 megawatts on Monday “and the highest likelihood of rotating outages that we’ve seen so far”, said Elliot Mainzer, its chief executive officer.

“This multi-day event is going to get much more intense,” he said in a press conference on Sunday. “It is game-on – and time for continued focus.”

The threat to the power system is another reminder of how grids have become vulnerable in the face of extreme weather as they transition from fossil fuels to renewable energy. California has retired many of its older natural-gas fired power plants, leaving the state increasingly reliant on solar farms that go dark late in the day as demand for electricity peaks. At the same time, the state is enduring its worst drought in 1,200 years, sapping hydropower production.

Mainzer, who heads the California Independent System Operator, thanked electrical consumers for conserving during the days-long heat wave, but said significant additional reductions were needed in the late-afternoon and evening hours – as well as access to all of the tools that the state and utilities have established for such conditions “in order to avoid broader interruptions of service”.

A grid emergency watch is in effect for Sunday night as well as Monday. Demand for electricity on Tuesday is expected to near 50.1 gigawatts, just shy of the all-time record of 50.2 gigawatts set in 2006. The grid operator expects additional calls for reducing energy use with record-breaking temperatures lasting at least through to Friday, Caiso said in a statement late Sunday. 

Heat and wildfires

Blisteringly hot temperatures and a rash of wildfires are posing a twin threat to California’s power grid as a heat wave smothering the region peaks in the days ahead.

Much of California is under an excessive heat warning for the next four days, with temperatures in Sacramento forecast to crest Tuesday at 45.6°C, sending demand for electricity to run air conditioners to near record highs.

The fight to keep power flowing in the most populous US state is complicated by wildfires near Los Angeles and San Diego that are threatening transmission lines and power plants, though there had been no major interruptions as of Sunday afternoon, Mainzer said. BM