Agencies assess power system performance during February freeze

September 24, 2021, 12:00PMNuclear News
Snow covering grounds of the Texas Capitol on February 15, 2021.

To prevent future winter storms from causing the kind of widespread, lethal power outages wrought by February’s frigid blast through Texas and other states, the electric and natural gas industries need to bolster their winterization and cold weather preparedness and coordination, a just-released preliminary report from the Federal Energy Regulatory Commission and North American Electric Reliability Corporation concludes.

The two agencies had announced on February 16 that they planned to open a joint inquiry to identify problems with the performance of the bulk power system during the storm and to offer solutions. A team of FERC and NERC staff members presented the report at a FERC meeting on September 23.

A presentation of the report, February 2021 Cold Weather Grid Operations: Preliminary Findings and Recommendations, is available.

FERC/NERC findings: Unofficially dubbed Winter Storm Uri, the mid-February arctic assault—the costliest U.S. winter storm event on record, at $20.4 billion—triggered the loss of 61,800 MW of electric generation, as 1,045 individual generating units experienced 4,124 outages, derates, or failures to start, according to the report. Natural gas production was severely reduced, with the largest effects felt in Texas, Oklahoma, and Louisiana, where combined daily production declined to an estimated 20 billion cubic feet per day—a drop of more than 50 percent compared to average production from February 1 to 5.

The report points to the freezing of generator components and fuel issues as the top two causes of generator outages, derates, and failures to start. While the causes identified affected generating units across all fuel types, 57 percent of the 1,045 units were natural gas–fired units that primarily faced fuel-supply challenges.

Only one nuclear unit succumbed to Uri: STP Nuclear Operating Company’s South Texas Project-1. On February 15, STP reported an automatic trip to the Nuclear Regulatory Commission that was caused, the company said, by a cold weather-induced failure of a feedwater pressure sensing line.

Attention, generators: The preliminary report makes nine key recommendations, including revising reliability standards to require generator owners to take a number of actions, including the following:

  • Identify and protect cold weather–critical components.
  • Build new units or retrofit existing units to operate to specific ambient temperatures and weather based on extreme temperature and weather data.
  • Account for the effects of wind and precipitation in winterization plans.
  • Develop corrective action plans after freeze-related outages.
  • Ensure that the system operator is aware of the operating limitations in the generating fleet so that mitigation actions can be planned.

The report also recommends that generator owners be given the opportunity for compensation and recovery of the costs of building or retrofitting to operate to a specific temperature, and that Congress, state legislatures, and jurisdictional regulators require gas facilities to prepare and follow cold weather preparedness plans.

What they’re saying: “This is a wake-up call for all of us,” declared FERC chairman Richard Glick. “There was a similar inquiry after Texas experienced extreme cold weather in 2011, but those recommendations were not acted on. We can’t allow this to happen again. This time, we must take these recommendations seriously, and act decisively, to ensure the bulk power system doesn’t fail the next time extreme weather hits. I cannot, and will not, allow this to become yet another report that serves no purpose other than to gather dust on the shelf.”

NERC president and chief executive officer Jim Robb stated, “These preliminary findings provide clear and comprehensive insight into what happened on the grid during the February freeze, and our joint recommendations provide a road map for what actions need to be taken next in order to prevent a repeat occurrence. Our coordinated efforts—across both the electric and natural gas industries—will provide the way ahead. NERC and FERC are committed to working together to make this happen.”

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