California’s power grid stood up to a recent heat wave but summer is far from over

A persistent heat wave that scorched most of California earlier this month essentially amounted to a real-time stress test that the state’s electric grid managed to withstand. But the head of the organization responsible for keeping the lights on says energy officials are still on alert as the summer wears on.

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

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

Though not as severe, parts of Southern California sweltered as well. 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 electric grid because homes and businesses crank up their air conditioners, putting pressure on system operators to meet the surge in demand.

To make matters worse, the hot weather lasted 14 days and bled into neighboring states.

On July 10, the Western Interconnection that helps coordinate electricity between 14 states in the West (including all of California) plus northern Baja California, British Columbia and Alberta hit an all-time record of 167,988 megawatts for peak load.

But the California Independent System Operator, known as the CAISO for short, did not resort to issuing any Flex Alerts — requests of customers across the state to voluntarily reduce their energy use.

On July 8, for example, CAISO operators had about 55,000 megawatts of supply on hand to meet an estimated demand of just over 43,000 megawatts — a fairly comfortable cushion of  around 12,000 megawatts.

The elbow room was due in large part to capacity that’s been added to California’s grid in recent years.

The state has added nearly 11,600 megawatts of new grid resources since 2022. Of that amount, energy storage from batteries accounts for 5,800 megawatts.

Storage facilities take solar power generated during the day and discharge the electricity when California’s power system is under the most stress.

The batteries “did exactly what we expected them to do” during this month’s heat wave, Mainzer told the Union-Tribune. “They charged during the day when solar is abundant and put energy back onto the grid in the afternoon when solar production is rolling off the system … They were clearly a difference maker.”

It should be noted that the costs of building storage systems — and other grid enhancements — are passed on to utility customers in their monthly bills.

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

System operators were not so lucky three years ago.