Millions of customers across the central and south-central United States lost electricity and heat this week amid freezing weather due to a blast of cold air from the Arctic that coincided with historic generation losses across thermal and renewable assets, system operators reported.
While most of the West was spared, outages—some lasting several days—were reported in Oregon (see related story) and southeast New Mexico, while some Colorado utilities issued conservation requests to their customers.
The brunt of the outages and suffering, however, was in Texas. The Electric Reliability Council of Texas on Feb. 17 reported up to 46,000 MW of lost generation due to the extreme cold, with 28,000 MW of losses from thermal generation and 18,000 MW from wind and solar. The majority of losses was due to nonweatherized infrastructure, which resulted in natural gas wells and pipelines, components at gas-fired power plants, and wind turbines becoming frozen as the temperature plummeted, infrastructure operators said. The 1,280-MW Unit 1 of the South Texas Project nuclear station on Feb. 15 also briefly stopped generating power due to a cold-weather failure of a feedwater pump line.
At the peak of the freeze on Feb. 15, the system operator instructed utilities to shed 16,500 MW of customer load.
"We know millions of people are suffering," ERCOT President Bill Magness said in a Feb. 17 statement. "We have no other priority than getting them electricity. No other priority."
ERCOT in a tweet at about 10:30 a.m. on Feb. 19 said the full system had been restored.
A Feb. 16 report from the U.S. Department of Energy said natural gas production in the U.S. south-central region was down by 6.3 Bcf per day because of "wellhead freeze-offs and natural gas processing plant outages caused by extreme cold."
Southwest Power Pool in the early hours of Feb. 16 declared an Energy Emergency Alert Level 3 for its 14-state balancing authority area, which includes Xcel Energy subsidiary Southwestern Public Service in New Mexico and across the Texas border. The emergency alert was downgraded to a Level 1 the following day. SPP in a Feb. 18 grid-conditions update said it would remain in a period of "conservative operations" until 10 p.m. Central time on Feb. 20.
"While grid conditions have improved, we anticipate load and generation fluctuation over the next 48 hours, and conditions could change rapidly," the update said.
SPS initiated controlled outages from around 6:45 a.m. Central time until around 11 a.m. on Feb. 15, affecting 10,000 customers in New Mexico, company spokesman Wes Reeves told California Energy Markets in an email. The company was directed by SPP on Feb. 16 to initiate another round of outages, but Reeves was unable to share exact numbers of customers affected. Power was restored to all customers by noon on Feb. 16, and there were no additional outages, he said Feb. 17.
In addition to SPP and ERCOT, the Midcontinent Independent System Operator also directed load shedding in response to the winter weather.
Elsewhere in the West, northern Colorado's Platte River Power Authority and Mountain Parks Electric on Feb. 14 issued separate conservation requests.
The unprecedented cold weather impacted wind and solar availability and caused a natural gas shortage, PRPA said in a Feb. 14 statement. The utility relied on other generation resources to avoid outages.
"Basically, because our natural gas supply was diverted for home heating purposes, approximately 40 percent of our generating capacity was not available from Sunday afternoon through early Monday afternoon," PRPA spokesman Steve Roalstad said in an email to CEM. "We used our hydro, coal-fired assets and available market purchases, along with reduced demand from our customers, to ensure system reliability throughout the weekend."
MPE, a member cooperative of Tri-State Generation and Transmission Association, also issued a call for conservation on Feb. 14, but three hours after releasing the request, the utility reported no further system constraints.
In response to the outages, the California Independent System Operator on Feb. 16 sent a series of tweets urging customers to voluntarily conserve energy in the evening hours "to help ease stressed grid conditions in the Midwest, Texas and the Southeast." Grid conditions in California are stable, the ISO said.
CAISO on Feb. 17 said in follow-up tweets that it was requesting energy conservation to "ease demand for natural gas that can be used in other states in the Midwest and Southeast for heating."
The Federal Energy Regulatory Commission and the North American Electric Reliability Corporation on Feb. 16 said they would jointly investigate "the operations of the bulk-power system" in light of the widespread outages affecting millions of customers.
"In the days ahead, we will be examining the root causes of these reliability events, but, for now, the focus must remain on restoring power as quickly as possible and keeping people safe during this incredibly challenging situation," FERC Chairman Richard Glick said in a separate Feb. 15 statement.