California remains in the grip of an intense heat wave, but so far has managed to avoid further rotating outages.
Over the weekend, hundreds of thousands of Californians were temporarily left without electricity as utilities pre-emptively cut energy supplies as temperatures and electrical demand soared.
On Friday, Aug. 14, California’s grid operator, the California Independent System Operator (CAISO), declared a Stage 3 electrical emergency that lasted a little over two hours, with rotating outages throughout the state for about the first hour. A second Stage 3 emergency was declared Saturday night for twenty minutes.
The grid operator on Aug. 16 announced a Flex Alert that remained in effect through Aug. 19. The alert calls for consumers to take voluntary conservation measures to reduce electricity use.
On Monday, CAISO declared a Stage 2 emergency and said it anticipated rotating outages, and dispatched 900 megawatts of demand response. But demand was lower than expected as a result of cloud cover and conservation, and the Stage 2 emergency was canceled without implementing outages.
The Stage 2 emergency was reinstated on Tuesday, and again power outages were avoided due to lower than expected demand, along with additional imports and wind generation. CAISO also renewed its voluntary Flex Alert. Conservation efforts continued through Wednesday, which again meant power outages were avoided.
“We are grateful to families and businesses across the state that answered the call to reduce electricity use during a crucial time on the grid,” Steve Berberich, president and CEO of CAISO, said in a statement on Monday. He also warned that the heat wave was not expected to abate until Wednesday evening and that consumers should continue to conserve energy.
Additional steps taken by the CAISO were to use the Capacity Procurement Mechanism to procure additional power supply for several days and to suspend virtual trading for the week to avoid adverse impacts on reliability from such trades.
The grid operator issues a Stage 2 emergency after it has taken mitigating actions but is no longer able to provide its expected energy requirements. A Stage 2 declaration allows the ISO to intervene in the wholesale power market, such as by ordering power plants online.
CAISO issues a Stage 3 emergency when it is unable to meet minimum contingency reserve requirements and outages are either imminent or in progress.
As of Thursday morning, CAISO’s forecast peak demand was 46,313 MW against 47,137 MW of available capacity. The grid operator forecast Friday’s peak demand to be 45,094 MW. Historical peak demand on the CAISO system reached 50,270 MW on July 24, 2006.
Ensuring capacity
Meanwhile, California Gov. Gavin Newsom on Monday, Aug. 17, signed an emergency proclamation to free up energy capacity.
One of the key provisions of the proclamation was a temporary suspension of rules that require ships docked in California ports to use ship-to-shore power instead of their auxiliary generators. The governor’s emergency declaration was needed to suspend that rule.
In announcing the emergency proclamation, Newsom also said he had sent a letter to CAISO, the California Public Utilities Commission, and the California Energy Commission demanding an investigation into “the service disruptions that occurred over the weekend and the energy agencies’ failure to predict and mitigate them.”
Calling the blackouts “unacceptable and unbefitting of the nation’s largest and most innovative state,” Newsom said the agencies failed to anticipate the event and to take necessary actions to ensure reliable power supplies.
“We’re doing everything we can,” Reiko Kerr, senior assistant general manager for power at LADWP, said.
In addition to issuing mandatory demand response measures and requests for customers to conserve energy, LADWP’s efforts included starting up idled gas-fired plants, offering excess capacity to CAISO on a recallable basis in case the public power utility suddenly needed that energy, and working to reduce the electrical demand of the city’s water pumps, which Kerr said was a “challenge because of wildfires in our backyard.”
“Typically, we are long power,” Kerr said, meaning the utility has its own generation and has more than enough power to meet its demand.
It also helped that LADWP is about 20% below peak demand levels because people are home during the COVID-19 crisis and high demand centers such as schools, universities, major sports venues like the Staples Center, and industrial customers are mostly idle. Even the Los Angeles airport is not up to full capacity, Kerr said.
In the end, “what saved the day was our dispatchable gas units,” Kerr said. “When you need them, you need them.”
In part, some of those units were available because of a deal LADWP struck with the California Water Resources Control Board. Originally some of the utility’s coastal gas-fired plants were scheduled to be decommissioned in 2020 because of once through cooling (OTC) regulations restricting the use of ocean water to cool power plants. But LADWP negotiated an agreement with the water board that allows OTC units at one of its plants to operate until 2024 while OTC units at two other plants can run until 2029.
San Diego Gas & Electric on Monday said it was prepared to begin rotating outages to more than 100,000 customers based on CAISO demand forecasts, but “conditions improved steadily throughout the day” and outages were averted in San Diego and southern Orange, “in part, thanks to local residents and businesses heeding the call to cut back on energy usage.”
Coordinating supply in Northern California
One of California’s other large public power utilities, the Sacramento Municipal Utility District (SMUD), along with the Balancing Authority of Northern California (BANC), has implemented restricted maintenance operations and “utilized all generation resources available to support electric demand,” Mark Willis, SMUD’s director of grid operations, said via email.
“We called upon all Load Management Programs, dispatchable and non-dispatchable. We made direct appeals to our commercial and residential customers to conserve energy between 1PM and 9PM,” Willis said. “We also coordinated with neighboring utilities to ensure adequate power supply.”
SMUD is also providing emergency assistance to neighboring balancing authorities, including the CAISO. And while SMUD is not subject to CAISO orders calling for rotating outages, the public power utility participates in CAISO’s energy imbalance market and makes all its resources available to the market.
“So far, SMUD has not had to implement rotating outages, and we expect to be able to serve customer demand, barring loss of transmission or generation resources during the heat wave,” Willis said.
In Northern California, Pacific Gas and Electric said customers’ responses for calls to conserve energy helped avert the need for rotating outages for the third day in a row. The utility noted, however, that its meteorologists are forecasting the heat wave to continue through Thursday.
