More California blackouts? PG&E issues warning as ISO goes to Stage 2 alert on power grid

A day removed from the first round of rolling blackouts to hit the state since the 2001 energy crisis, California’s power grid manager said it didn’t think more outages were likely this weekend but PG&E Corp. warned its customers of the possibility of shutoffs.

LATEST UPDATES: SECOND NIGHT OF ROLLING BLACKOUTS ORDERED

The California Independent System Operator, which runs the electricity grid, issued a Stage 2 alert Saturday night, which means the state’s major utilities would begin taking power away from its “interruptible” customers — those that agree to forego electricity in crunch periods in exchange for discounts. That’s the last step before declaring a Stage 3 emergency and imposing rolling blackouts.

Just two hours earlier, the ISO tweeted that it didn’t anticipate having serious problems.

PG&E had said it thought more blackouts were possible as early as 5 p.m. Although the 5 p.m. prediction came and went without any difficulties, it was clear the electricity grid remained in fragile condition as California battled a major heat wave.

Meanwhile, the demand for electricity is expected to rise again Monday and Tuesday.

While the high temperature this weekend was expected to be 107 degrees, the thermometer will hit 110 on Tuesday, according to the National Weather Service.

“Every time the temperature goes up a degree or two, it affects the grid,” ISO spokeswoman Anne Gonzales said.

Although peak demand Saturday was expected to top 45,000 megawatts — nearly as much as Friday evening’s peak — Gonzales said the supply situation had become more favorable. Two big generators that had been out of service Friday, including one that “unexpectedly tripped offline,” have returned to duty, she said. That added a combined 1,250 megawatts of power to the grid, she said.

The ISO, based in Folsom, declared a Stage 3 emergency at 6:36 p.m. Friday. That meant the grid was running dangerously low on reserve power and the participating utilities — starting with PG&E Corp., Southern California Edison and San Diego Gas & Electric — had to start imposing rolling, one-hour blackouts to blocks of customers. The alert officially ended at 8:39 p.m. but utilities such as PG&E said it took longer than that to restore some of their customers.

In all, the grid had to “shed” about 1,000 megawatts of demand to keep the entire system from failing. That meant, according to the ISO’s calculations, as many as 150,000 homes and businesses were shut off at a time. PG&E said as many as 250,000 of its customers were shut off at one time or another. Southern California Edison said 132,000 of its customers were affected.

Gonzales said it could have been worse, except that neighboring grid systems — from within the state and from other states — were able to deliver more than 800 megawatts of “emergency assistance” to the ISO. If not for that 11th-hour aid, tens of thousands of additional customers would have been taken offline.

SMUD, the Sacramento Municipal Utility District, as well as other municipal agencies like Roseville’s city-run utility, Modesto and Turlock irrigation districts and the Los Angeles Department of Water and Power (LADWP) aren’t part of the ISO and weren’t affected by the rolling blackouts.

The ISO said demand Saturday was expected to peak at more than 46,000 megawatts, sometime around 5:30 p.m. The expected peak demand Sunday, when it’s supposed to be a couple of degrees cooler, is 44,000 megawatts.

ISO officials acknowledged that forecasting has become trickier because of office shutdowns during the pandemic. Gonzales said the agency believes Friday night’s outages were strictly a matter of excessive heat.

This story was originally published August 15, 2020 at 10:42 AM with the headline "More California blackouts? PG&E issues warning as ISO goes to Stage 2 alert on power grid."