The state’s power grid operator triggered its emergency operations on Wednesday evening, allowing it to call on all available power generation to stay ahead of demand — and bringing it a step closer to a worst-case scenario of ordering rotating power outages.

If the Electric Reliability Council of Texas takes that step, the location and duration of power outages would be controlled by individual electric utilities. For example, CPS Energy President and CEO Rudy Garza in San Antonio said last month when conditions looked tight that outages would last between 10 and 15 minutes for their customers.

Representatives for other utilities said the duration of power outages and whether they would rotate would depend on what they hear from ERCOT, which calculates how much demand must be reduced to keep the grid from failing.

Outages would likely be necessary for only a few hours if ERCOT required them on Wednesday night because demand typically falls and wind generation typically rises after sunset. Texas can produce more wind power than any other state.

ERCOT has asked Texans to conserve energy 10 times this month because of the high demand for power as excessive heat has gripped the state. On Wednesday, wind power was forecast to be low.

The afternoon and evening hours tend to be tightest as people return home from work and crank down their thermostats. Solar power generation, which has grown significantly in recent years in Texas, also dwindles as the sun sets.

Grid operators asked power users to cut back their electricity consumption between 6 p.m. and 9 p.m. Wednesday. Power customers can conserve by turning up thermostats a few degrees and refraining from using large appliances such as washing machines and clothes dryers during this period.

ERCOT said it was calling on large power users to reduce their consumption and asking other major U.S. grids to provide what help they could. The ERCOT grid, which serves most of the state, has limited connections to the larger grids that serve the rest of the nation.

The state has broken its power demand record 10 times so far this summer because of economic and population growth and the punishing heat.

Rolling outages remain a rare last resort. ERCOT has not called for them since the devastating February 2021 winter storm, when power was cut to millions of homes over days while extremely cold weather persisted. More than 200 people died.

During that storm, the initial plan to cut power for short periods was abandoned when numerous power generators suddenly failed amid days of subfreezing temperatures, requiring the widespread shutdown of power for days.

People with generators should not use them indoors because they emit deadly carbon monoxide.

You can follow Texas grid conditions here and sign up for emergency alerts here.

Disclosure: CPS Energy has been a financial supporter of The Texas Tribune, a nonprofit, nonpartisan news organization that is funded in part by donations from members, foundations and corporate sponsors. Financial supporters play no role in the Tribune’s journalism. Find a complete list of them here.

This article originally appeared in The Texas Tribune at https://www.texastribune.org/2023/09/06/texas-ercot-power-grid-rolling-blackouts/. The Texas Tribune is a member-supported, nonpartisan newsroom informing and engaging Texans on state politics and policy. Learn more at texastribune.org.