A Texas wind farm at sunset along U.S. Route 377. Credit: Edward A. Ornelas for the San Antonio Report

For the second time this week, Texas’ electrical grid operator asked for people to conserve power to avoid blackouts. 

On Thursday, the Electric Reliability Council of Texas, or ERCOT, issued a level 1 “energy emergency alert,” calling for voluntary conservation measures. The alert lasted approximately two hours roughly between 3 and 5 p.m. 

In a media call, Dan Woodfin, senior director of system operations at ERCOT, said that the low power reserves Thursday were a result of high demand, lower wind power output on the system than at other times this week, and generators and wind and solar supplies that are shut down or not operating at full capacity.  

“If you’re not using something, turn it off and unplug it during this alert,” Woodfin said. “It would really help at this time.”

ERCOT officials had asked for people to set thermostats 2 to 3 degrees higher than normal, unplug unused appliances, avoid using heavy-duty appliances like washers and dryers, and to turn off pool pumps for a few hours. The alert also allowed ERCOT to call upon all available power supplies, including other power grids to which ERCOT connects.

One factor driving the need for conservation was the approximately 5,200 megawatts of generation capacity from power plants, solar arrays, and wind farms that were not producing power Thursday afternoon, Woodfin said. That was caused by a variety of factors that differs for each unit, he said. He was not able to specify which or how many power plants and other generation sources add up to that 5,200 megawatts.

One megawatt can power about 200 homes on a hot Texas summer day, according to ERCOT. As of 4:30 p.m., demand on the entire gird was nearly 71,000 megawatts, shy of the record-high 74,531 megawatts set on Tuesday, when ERCOT issued its previous energy emergency alert. 

ERCOT coordinates the flow of electricity in Texas’ electricity market, where prices are mostly set by supply and demand. Since earlier this year, the grid operator has been predicting tighter-than-usual margins this summer. 

ERCOT has not issued such calls for conservation since January 2014. 

Brendan Gibbons is a former senior reporter at the San Antonio Report. He is an environmental journalist for Oil & Gas Watch.