Sep. 6—California's badly strained power grid appeared to escape rolling blackouts Monday but will be tested like never before Tuesday, officials warned, as they urged the public to ramp up conservation efforts or face the prospects of losing power during a historic heat wave that isn't done roasting the state.
The expected energy load driven largely by air conditioning demand has taxed the state's power supplies, and Tuesday is anticipated to be expected to be worse than Monday.
Officials have asked residents to cut their electricity use from 4 to 9 p.m. Tuesday — the seventh straight day of such requests, known as Flex Alerts. They have also declared that emergency operations are possible on Tuesday — something that also occurred Monday, as the grid moved through the first few stages of emergency but then canceled the notices around 9 p.m. as grid conditions stabilized.
Electrical demand is expected to be the highest ever on Tuesday, California Independent System Operator President and CEO Elliot Mainzer said Monday at a news conference.
"Right now our goal is to not see that number," he said.
To keep demand from exceeding the state's supply, Mainzer stressed that consumers would need to increase their electrical saving efforts 2 to 3 times what they did in the early days of the historic heat wave.
On Tuesday, the state is predicting a 51,000 megawatt load. Officials issued an emergency energy watch for 5 to 9 p.m., a step that encourages market providers to offer supplemental energy or savings, or both.
A PG&E spokesperson said in an email Monday evening that "the potential for rotating outages has increased significantly," but the state hasn't directed the company to cut power anywhere yet. Rotating shut-offs could occur, typically for one to two hours, in blocks, PG&E said.
A spate of small-scale power outages, including in the Napa County, Vacaville, Moraga and Pleasant Hill areas, hit the region Monday. Over 22,000 homes and businesses in the Bay Area were affected by these unplanned outages as of 6 p.m. Monday, according to a PG&E spokesperson. The main issue was transformers: They need time to cool down, and typically do so overnight when temperatures drop, but during a heat wave when temperatures are high around the clock, transformers may fail. This type of blackout is different from state-ordered rotating outages or public safety power shutoffs to prevent wildfires.
State power demand appeared to peak just short of 49,000 megawatts on Monday — a very high figure, but supplies and conservation programs were able to meet the demand and avert rolling blackouts.
So far the Flex Alerts have worked, as state residents have saved 600 to 700 megawatts in recent days. State regulators have asked consumers to avoid running appliances, set thermostats to 78 degrees or higher and turn off all unnecessary lights during those peak hours.
As resources dipped low Monday, the state moved to a Stage 2 emergency from 6:30 to 9 p.m., which allowed it to tap into emergency power reserves as well as electricity from last-minute imports and generators. Mainzer estimated the state has about 3,000 megawatts as backup, which provides a small "buffer."
If a Stage 3 is reached and power must be cut — something that is highly unlikely late Monday evening but could be a possibility again Tuesday — state regulators will ask utilities to determine the best way to drop their usage, probably rotating across systems, hopefully for short durations, Mainzer said.
The highest electrical load ever drained by Californians was 50,270 megawatts on July 24, 2006.
Fortunately, the Pacific Northwest has avoided the heat spell, which has allowed California to import some power from that region. Utilities have agreements to share power during emergencies, Mainzer said.
California grid operators are monitoring wildfires to make sure they don't damage generators or transmission wires. Several generators are already offline, tightening electrical supplies.
This week's heat wave is expected to last through Friday with daytime temperatures forecast to be 10 to 20 degrees above normal. Some cities, including Fairfield and Livermore, hit highs of greater than 110 degrees. The National Weather Service extended an excessive heat warning and heat advisory through 8 p.m. Thursday. Conditions are dangerous to those vulnerable to heat and without access to cooling and hydration.
State officials suggest consumers precool their homes with air conditioning early in the day, when electrical demand is not as high.
Severin Borenstein, a UC Berkeley professor of energy and member of the ISO's governing board, noted on Twitter that it wouldn't take that much for the public to avert blackouts.
"Today looks tough tomorrow looks really tough," Borenstein tweeted Monday. "But reducing system demand by even 10% would virtually eliminate any concerns."
San Francisco Chronicle staff writer Mallory Moench contributed to this report.
Matthias Gafni is a San Francisco Chronicle staff writer. Email: email@example.com Twitter: @mgafni
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