Stifling Heat in Texas and California Squeezes Power Grids

(Bloomberg) -- Heat waves in Texas and California are threatening to push electrical grids to the brink, prompting the specter of blackouts yet again in the two most populous U.S. states.

In Texas, officials are asking customers to conserve power as generating plants with a combined capacity of 11,000 megawatts -- or enough to run about 2.2 million homes -- are down for repairs amid the heat. California’s grid, meanwhile, is being swamped with demand as temperatures are forecast to exceed 110 degrees Fahrenheit (43 Celsius) in the coming days.

The searing weather marks the first heat-related stress tests of the year for U.S. power grids as a historic drought grips the western half of the nation. It comes 10 months after California resorted to rolling blackouts last summer, briefly plunging more than a million people into darkness. In February, much of Texas was left without power for days during a frigid winter storm that paralyzed power plants and left than 100 people dead.

While California officials said they’re confident they could keep the lights on this week, Texas grid operators are struggling to determine why so many plants are down during a heat wave.

“We will be conducting a thorough analysis with generation owners to determine why so many units are out of service,” Woody Rickerson, a vice president for the Electric Reliability Council of Texas, said in a statement. “This is unusual for this early in the summer season.”

The generators out of service include one of the two units at the 2.3-gigawatt Comanche Peak nuclear plant near Dallas, which was taken offline over the weekend after a radiation monitor malfunctioned, according to the U.S. Nuclear Regulatory Commission.

Spot power at Ercot’s North hub, which includes Dallas, surged 2,600% to average $848.89 a megawatt-hour as of 2:15 p.m. Eastern time, according to data compiled by Wood Mackenzie.

In the U.S. West, heat warnings and watches from Phoenix to Northern California will be in place through Saturday evening, the National Weather Service said Monday. Temperatures in California’s Central Valley could rise to 113 between Thursday and Saturday. Parts of Arizona could hit 119.

California has ordered utilities to line up extra power supplies and giant batteries to prepare for this summer, but officials warn the system could still face shortfalls. Grid operators said Monday that they don’t expect to call for blackouts during this week’s heat.

Read More: Blackouts Threaten U.S. West This Summer as Heat Awaits

While cooling demand will surge, the heat comes just before the summer solstice, making sunlight available for longer to power the region’s solar farms. It also helps that wind output in California tends to be strong in June, and even though a drought has left hydropower dams depleted, it’s still early enough in the season that they will be able to shore up supplies, according to energy consultancy Wood Mackenzie Ltd.

Day-ahead power prices in Southern California jumped 123% to average $64.44 a megawatt-hour for on-peak hours, the most since Feb. 18, according to the firm’s data.

Afternoon temperatures this week could reach 110 degrees to 119 degrees in Arizona, south and west of Phoenix, the weather service said. The inland valleys near San Diego may reach 106. Officials warned that people should stay indoors if possible.

In Southern California, the weather service also warned of elevated wildfire risk in Santa Barbara County through Tuesday morning due to high winds and drying vegetation. In response, Edison International’s Southern California Edison said that it may need to cut power to 5,160 customers in the county to prevent live wires from sparking blazes, according to a post on its website.

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