Heat wave puts Southern California power grid under pressure

With a heat wave bearing down on Southern California, officials from San Diego Gas & Electric and the managers of the state’s electric grid are working to make sure the power system doesn’t wilt.

A high pressure system is forecast to send temperatures as high as 117 degrees in the desert and well over 100 degrees in places such as Escondido, Ramona and Santee by Friday. Temperatures are expected to dip a bit on Saturday but seasonal conditions are not expected to return until the middle of next week.

SDG&E officials say adequate electric supplies have been secured in anticipation of the heat wave and the California Independent System Operator (CAISO) has not issued a Flex Alert — a call for consumers to voluntarily conserve electricity when there is a predicted shortage of energy supply.

But CAISO on Thursday did issue a Restricted Maintenance Operations notice, which orders delays on any planned maintenance of power plant and transmission facilities to make sure all available resources are available in case they are needed.

“We have no major transmission or generation outages at this time,” said Steven Greenlee, senior public information officer for CAISO. “But wildfires are always our concern. That can change things in just a matter of minutes.”

CAISO oversees the operation of about 80 percent of the state's electric power system and electricity market.

As a precautionary measure, SDG&E has canceled scheduled maintenance work in fire-prone areas and asked customers to cut back on energy use.

“We’ve secured enough resources and we’re fully prepared to meet the system demand (Friday) but it’s always a good idea, particularly when these hot weather events come, that everyone help conserve energy where they can,” said SDG&E spokesman Joe Britton.

Among some of the things customers can do to reduce energy consumption, Britton said, include:

  • instead of air conditioning, use ceiling fans or portable fans
  • pre-cool your home by running the AC in the morning and turning it off before leaving for work
  • close drapes and blinds to keep the sun from warming up rooms
  • run appliances and swimming pool pumps after 9 p.m.

SDG&E has declared Friday a “Reduce Your Use” day, in which customers on the Reduce Your Use Rewards program can receive a credit on their monthly bills by cutting back on energy use between 2 p.m. and 6 p.m. Friday. About 80,000 SDG&E customers have signed up for the plan, Britton said.

With low humidity and dry conditions expected to persist, SDG&E has put its heli-tanker, the Erickson Aircrane, on standby. The aircrane holds up to 2,650 gallons of water or fire suppressant — the equivalent of five fire engines.

The summer outlook

CAISO issued four Flex Alerts in 2017, with two coming in late June. The system operator has yet to issue a Flex Alert this year but Greenlee cautions that does not necessarily mean the summer of 2018 is shaping up to be more manageable than the summer of 2017.

“It's too early to tell,” Greenlee said. “We got through June without the heat waves. We were pleased to see that but we've got a long way to go … Our biggest worry is in late summer and August and September.”

In May, CAISO released its summer assessment and predicted “an extremely low probability” the system operator will be forced to initiate rotating power outages.

But at the same time, it anticipated capacity would be tight in high-load periods this summer and found a 50 percent probability of declaring a Stage 2 Emergency for at least one hour this summer.

A Stage 2 Emergency means demand is outpacing supply, forcing CAISO to dip into its electricity reserves.

Peak demand this summer is expected to be about the same as last year.

CAISO projects 51,947 megawatts of generation will be available to serve demand this summer. Under typical summertime conditions, the peak demand is anticipated to be 46,625 megawatts in 2018. Last year’s peak load was 50,116 megawatts, recorded on Sept. 1.

However, by late summer hydroelectric production is expected to be down by about 1,300 megawatts compared to 2017. The winter of 2016-2017 was especially wet in California but the California Department of Water Resources on April 2 of this year reported the water content of the snowpack was just 51 percent of average.

The summer assessment expects electricity supplies to be adequate during daytime hours, largely due to the high production of solar power across the state. However, solar production falls off when the sun goes down and energy users come home from work, turn on their air conditioners and use appliances that suck up a lot of power, such as washer/dryers.

“Hydroelectric production is a very flexible resource,” Greenlee said. “It is valuable to us as grid operators because, especially in the late afternoons, we can call upon that to follow demand that may be changing quickly.”

The system has added 692 megawatts of generation since last year — the vast majority from renewable sources, including 60 percent from solar.

But natural gas-powered generation has dropped by about 837 megawatts since last summer, due to plant retirements.

That loss may be somewhat offset by a recommendation by the Energy Division at the California Public Utilities Commission to increase the natural gas storage volume at the Aliso Canyon Storage Facility in Los Angeles County.

The Energy Division calls for raising storage volume at Aliso Canyon from 24.6 billion cubic feet of gas to 34 billion cubic feet at the site.

One billion cubic feet is enough to fuel about 5 million homes in the U.S. for one day.

A massive leak was discovered at Aliso Canyon in October 2015 but not permanently contained until February 2016, forcing the evacuation of more than 8,000 households in the Porter Ranch neighborhood.

All told, about 100,000 metric tons of methane were emitted. According to a UC Davis study, the total greenhouse gas pollution equaled the emissions of a half-million cars driven for a year.

rob.nikolewski@sduniontribune.com

(619) 293-1251 Twitter: @robnikolewski

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