Roughly 5,200 MW of power dropped from the grid operated by the Electric Reliability Council Of Texas because of generator outages on Aug. 15, leading to the second emergency alert in a week calling on consumers to reduce their energy use.
Citing confidentiality rules, Dan Woodfin, senior director of system operations for ERCOT, declined on a media call to say which generators, or which type of generation, experienced the unplanned outages. Reserves across the ERCOT grid, which serves most of the state, fell below 2,300 MW and triggered a "level one" alert.
ERCOT throughout the week has seen record demand on its system, after officials in May projected that the reserve margin — the difference between forecast peak demand and total generation capacity, which serves as a buffer to limit the possibility of blackouts — would be 8.6% during the summer. That is well below the target of 13.75%.
Peak load for Aug. 15 was 70,964 MW around 5 p.m., lower than the record levels seen Aug. 13, when consumers used more than 74,000 MW. Aug. 15 temperatures were also slightly cooler than previous days.
"It's not alarming at this point; it's kind of what we expected to see going into the summer," Woodfin said of the Aug. 15 alert.
Generators have been running at high capacity throughout the week, which may have contributed to unplanned outages, Woodfin said. To avoid a possible shortfall, ERCOT has requested that power be imported through "our limited number of ties with other regions," Woodfin said.
Low wind on the system also lowered the power supply, Woodfin said. Wind provided 2,774 MW at peak hour load, according to a wind integration report for Aug. 15. Prices reached the $9,000/MWh cap on Aug. 15 for the third time in the grid operator's history.
The alert lasted for roughly two hours in the afternoon.