By Eileen O'Grady
Jan 7 Below-freezing temperatures across Texas pushed power use to a new winter record Tuesday, but the state avoided a repeat of Monday's power emergency as generating supplies improved.
Electric demand reached 57,277 megawatts in the hour ended at 8 a.m. CST (1400 GMT) on Tuesday, slightly above the 57,265 MW record set in February 2011 during a prolonged cold spell, according to the website for the Electric Reliability Council of Texas (ERCOT), the state's primary grid.
Sufficient generation and higher wind output from West Texas wind farms boosted the state's electric supply Tuesday compared to Monday when the grid operator declared an emergency as power plants shut unexpectedly, reducing supply.
Real-time power prices Tuesday morning across ERCOT indicated that power supplies were sufficient to meet the high demand. Prices ranged from $25 to $600 per megawatt-hour as demand peaked, down from Monday morning when prices hit the $5,000 price cap for about one hour.
ERCOT was able to avert rolling outages Monday by importing power and implementing demand response programs to curb rising demand.
The grid operator ended its call for power conservation Tuesday.
"The system appears to be in good shape today; we have sufficient generation online to meet demand," said ERCOT spokeswoman Robbie Searcy. "We appreciate the fact that people did conserve energy and helped us get through some tight periods this week and we appreciate all the work the generators have done to make their facilities available."
Monday's power emergency lasted less than three hours, but was reminiscent of February 2011 when ERCOT was forced to implement rolling outages for several hours after dozens of power plants were knocked offline or were unable to start due to frigid weather and strong winds across the state.
One of the state's largest power plants, Luminant's Comanche Peak 1 nuclear reactor, is operating at 72 percent of capacity for a second day.
Monday's events are sure to complicate the debate about the need for more generation in Texas, which has divided the Public Utility Commission and raised concern among state lawmakers.
Electric supplies on Monday tightened after more than 3,700 megawatts of generation was forced to shut overnight Sunday and early Monday, Dan Woodfin, ERCOT's director of system operations, told reporters. The forced outages came on top of nearly 10,000 MW of generation that was already shut for the season or for planned maintenance, he said.
Woodfin said about 1,800 MW of the 3,700 MW of the forced outages were weather-related, including two large power plants in north central Texas that he declined to name.
In a notice posted Tuesday detailing the previous day's supply problem, ERCOT said one power plant totaling 474 MW shut unexpectedly at about midnight.
At 6:04 a.m. Monday as power demand was rising, another power plant totaling 464 MW shut, followed by a third plant of 892 MW which shut at 6:31 a.m.
At 8:11, another "sudden loss of generation" occurred totaling 901 MW, dropping the grid's frequency 59.855 Hz, ERCOT said.
Power demand has surpassed the grid agency's winter forecast of less than 50,000 MW under normal weather conditions.
One megawatt can power about 500 homes in mild weather and about 200 homes during high-demand summer months, ERCOT said.
Power producers in Texas include Luminant, a unit of privately held Energy Future Holdings, NRG Energy , Calpine Corp, NextEra Energy and Exelon Corp.