Texas, California gird for power shortfalls as heat bakes West Texas

[BERKELEY] Electric grid operators in California and Texas are struggling to keep up with crushing demand for power this week as a sprawling heat wave smothers the western US.

Heat watches and warnings stretch for more than 1,500 miles (2,400 kilometers), from Northern Montana to Southern California. Temperatures are forecast to reach 108 degrees Fahrenheit (42 degrees Celsius) in Sacramento later this week, according to the National Weather Service. Dallas could hit a sultry 98.

Texas grid operators said they didn't expect power shortfalls Tuesday night. But they're asking residents to cut back on electricity use through Friday to avoid blackouts because so many plants are down for repairs. California officials warned that power demand could outstrip supply later in the week.

"These are really hot temperatures, and there is really no break for the potential record heat until Sunday," said Bob Oravec, a forecaster with the US Weather Prediction Center.

The searing weather marks the first heat-related stress tests of the year for US grids as a historic drought grips the western half of the nation. It comes nearly one year after California's rolling blackouts last summer and four months after Texas's energy crisis in February, when a deep freeze paralysed power plants, blacked out much of the state and left more than 150 people dead.

In California, power supplies could be tightest on Thursday, when demand could top 43 gigawatts, or about 3.4 gigawatts more than projected supplies, according to the California Independent System Operator, which manages most of the state's power grid.

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Though it often relies on electricity from neighboring states during heat waves, this week's heat is expected to stretch clear to the Canadian border, limiting imports, the operator said.

Officials in California have ordered utilities to line up extra power supplies and giant batteries to prepare for this summer, but they warn the system could still face shortfalls.

By Tuesday afternoon, the Texas grid operator said the grid remained stable despite crushing demand. It reported having about 3.4 gigawatts of power reserves, representing a extra-supply margin of about 10 per cent.

The Electric Reliability Council of Texas said it would call the first stage of a grid emergency should reserves fall below 2.3 gigawatts and would start rolling blackouts if they fell below 1 gigawatt.

The tight supply conditions came after generating plants with as much as 10.6 gigawatts of capacity - enough to power about 2.1 million homes - were unexpectedly down for repairs amid elevated demand. About two-thirds of those out of service are natural gas, coal and nuclear plants. The rest are wind and solar, the grid operator said.

Texas grid officials are struggling to learn why so many plants unexpectedly broke down. The number of generators out of commission is triple what they expect for this time of year.

"This is very concerning," Warren Lasher, a senior director at Ercot, said during a briefing Monday. "It's not clear why we are seeing so many units offline." Wind and solar farms both tend to crank out more power during warmer months in Texas.

But their output ebbs and flows throughout the day. That can leave the supplies tight at several points. It includes the early afternoon - when the heat builds and the wind sags - and at sunset, when the light recedes and takes the solar with it.

Texas lawmakers recently approved power market overhauls. Measures included requiring plants ensure they can operate in extreme weather and provisions for state-backed financial assistance to the grid operator as well as utilities hit by soaring wholesale electricity prices.

"Everything that needed to be done was done to fix the power grid in Texas," Republican Governor Greg Abbott told reporters last week while signing the legislation into law.

Houston reached 100 degrees June 13, the earliest that mark has been reached in a decade, according to the weather service. That may signal an unusually hot summer coming as the city normally doesn't endure such heat until August.

In the West, heat warnings and watches from Phoenix to Northern California will be in place through Saturday evening, the weather service said Tuesday. Temperatures in California's Central Valley could rise to 113 later this week. Parts of Arizona could reach 118.

The drought engulfing much of the region is only making things worse. Drought can drive up temperatures because the sun's energy goes directly into heating the air rather than evaporating moisture in the soil. This in turn dries the air and fuels more drought.

BLOOMBERG