California’s power grid has survived the recent heat wave, but summer is far from over

Noah Berger / AP

A boat crosses Lake Oroville with a smoldering hillside in the background as the Thompson Fire rages in Oroville, California, Wednesday, July 3, 2024. A prolonged heat wave ravaging Northern California has prompted fire warnings and power outages.

By Rob Nikolewski, The San Diego Union-Tribune (TNS)

Tuesday, July 23, 2024 | 02:00 AM

A prolonged heat wave that ravaged much of California earlier this month essentially amounted to a real-time stress test that the state’s power grid managed to withstand. But the head of the agency responsible for keeping the lights on says energy officials are still on high alert as summer progresses.

“We are generally well prepared” to prevent potential power outages, said Elliot Mainzer, president of the California Independent System Operator. “We have taken significant steps to bring new clean energy and capacity onto the system, but we must remain diligent.”

As Independence Day weekend approached, warm weather descended on the Golden State, with residents of Northern California bearing the brunt. Sacramento reached a high of 113 degrees on July 6, setting a city record for that date.

While not as bad, parts of Southern California were also sweating. In the deserts of San Diego County, temperatures hovered around 120 degrees in Borrego Springs and Ocotillo Wells on July 8.

Heat waves strain the electricity grid as households and businesses turn on their air conditioners, putting pressure on grid operators to meet the increasing demand.

To make matters worse, the hot weather lasted for 14 days and affected neighboring states as well.

On July 10, the Western Interconnection, which coordinates electricity between 14 western states (including all of California) plus northern Baja California, British Columbia and Alberta, reached a record peak load of 167,988 megawatts.

But the California Independent System Operator, or CAISO, has not issued Flex Alerts: requests for customers across the state to voluntarily reduce their energy use.

For example, on July 8, CAISO operators had about 55,000 megawatts of supply available to meet an estimated demand of just over 43,000 megawatts – a fairly comfortable cushion of about 12,000 megawatts.

Much of this room for maneuver is due to the capacity added to California’s power grid in recent years.

Since 2022, the state has added nearly 11,600 megawatts of new grid resources, of which 5,800 megawatts come from battery energy storage.

Storage facilities use solar energy generated during the day and discharge it at times when California’s electrical grid is under the greatest strain.

The batteries “did exactly what we expected” during this month’s heat wave, Mainzer told the Union-Tribune. “They charged during the day when there was a lot of sun and put energy back on the grid in the afternoon when the system’s solar output wanes … They were clearly a difference-maker.”

It should be noted that the costs of building storage systems and other grid improvements are passed on to the utilities through monthly bills.

During this month’s heat wave, multiple wildfires broke out in Northern California, but they did not impact major power lines or distribution and transmission infrastructure connected to the grid.

Three years ago, grid operators were less fortunate.

The Bootleg Fire in Oregon in July 2021 destroyed a major transmission line called the California-Oregon Intertie, which carries imported electricity from the Pacific Northwest to California. The fire knocked out about 3,500 megawatts from the system as the area was blanketed by sweltering weather.

“Every event and every set of facts is different,” Mainzer said.

The threat of power outages across the state has become more urgent in recent years.

In August 2020, California experienced its first rolling blackouts in 20 years after oppressive heat nearly overwhelmed the system for two days in a row. The blackouts left some areas without power for up to 2 1/2 hours.

The Golden State narrowly avoided a repeat the following summer. It nearly happened again in September 2022, when persistently high temperatures nearly collapsed the grid. CAISO issued a record 10 straight days of Flex Alerts, then thanked utility customers for helping save the day by reducing power usage from 4 to 9 p.m.

These are critical hours for California’s power grid, as solar production quickly disappears from the grid when the sun goes down. System operators must seamlessly and in real time replace those megawatts of solar with other energy sources to keep the grid from collapsing.

September could be tough for CAISO because the weather is still warm, so customers continue to use their air conditioners. But as fall approaches, the sun sets earlier, which means fewer hours of solar energy available to the energy system.

Other complicating factors?

When forest fires break out, the smoke they release can darken the sky, reducing the sun’s energy.

And if a heat wave spreads to neighboring states, it can lead to a reduction in imports and exports in the electricity market. States under pressure often hold on to the megawatts they already have so they can keep electricity flowing to their own utilities and not have to export it elsewhere.

The system is interconnected and complicated, but Mainzer is cautiously optimistic.

“The fleet of four-hour lithium-ion batteries we have in California is now the largest in the world, outside of China,” he said.

Last year, CAISO issued zero Flex Alerts. Can that be repeated this summer?

“If we have another series of unprecedented circumstances that push the system to its absolute edge — both here in California and in other parts of the West — then it’s possible to call Flex Alerts,” Mainzer said. “I can’t put a probability on it, but it’s certainly a possibility. We always try to minimize it, but it’s one tool in the toolbox.”

CAISO manages the flow of electricity over the power lines for about 80 percent of the state, plus a small portion of Nevada.