The short answer is with great difficulty. According to analysis of the historical records, California Independent System Operator (CAISO) was on the brink of invoking rolling blackouts during an extensive heatwave on 6 Sept 2022 and was saved, barely, by an emergency alert sent to some 27 million California residents to curtail power use in neck-of-time. As reported by Ivan Penn on a 25 Sept 202 article in The New York Times, it was a scary day in Folsom, California, outside Sacramento, where CAISO is located. Excerpts from the article with editing and abbreviations follows.
As Sept. 6 arrived, Elliot Mainzer, CAISO’s CEO, knew he was facing one of his toughest days. His meteorologists, and others, were forecasting record heat. With overnight lows in the 80s in much of the state, it did not take long for temperatures to surge into the 100s F, with Sacramento setting a record high of 116 F degrees for the day.
On a 9 am conference call CAISO informed California Gov. Gavin Newsom that it was projecting a new peak of 51,276 MW, higher than the 50,270 MW prior peak set 16 years earlier. CAISO was projecting “some significant shortfalls” for the day.
At 4:57 pm, CAISO demand hit 52,061 MW — nearly 4% higher than the prior record.
Mainzer recalled, “The sheer temperatures that were going on outside just kept pushing the load. It was just going up and up and up. We’re also facing sunset” – that’s when solar generation rapidly falls off.
About 5:17 pm, CAISO declared level 3 emergency alert and told utilities to prepare to cut off power to hundreds of thousands of customers.
At 5:40 pm, CAISO informed Newsom that “we were deep into the emergency … one step away from rotating outages.”
That’s when Newsom ordered emergency warnings to be sent to 27 million cellphones urging people to curtail power use or else.
Within minutes, demand dropped by more than 2,000 MW and rotating outages were avoided. Both Newsom and Mainzer were spared awkward, if not career limiting headlines.