FERC-NERC staff find “unprecedented” outages from Winter Storm Elliott
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FERC-NERC staff find “unprecedented” outages from Winter Storm Elliott

Incremental unplanned generating outages reached an unprecedented 90,500 MW during the Christmas 2022 storm that caused widespread power outages in the Eastern U.S.

Source: December 2022 Winter Storm Elliott Grid Operations: Key Findings and Recommendations.

The outage total represented 13% of the U.S. portion of the anticipated resources in the Eastern Interconnection and was significantly higher than the 61,800 MW lost during 2021’s Winter Storm Uri, according to a sobering report presented late last week to the Federal Energy Regulatory Commission (FERC) by FERC and North American Electric Reliability Corporation (NERC) staff.

According to the report, 1,702 generating units experienced 3,565 outages, derates or failures to start. 825 of the units were natural gas-fired generators.

Staff reported that 55 percent of the generating unit issues were caused by freezing issues (31%) and fuel issues (24% – Natural gas fuel issues represented 20% and all other fuel issues were 4%).

41% of outages were indicated by generator owners to be caused by mechanical/electrical issues, which staff found to be correlated with subfreezing temperatures. Those that were attributed to having “Mechanical/Electrical Issues” increased with decreasing ambient temperatures.

Additionally, nearly 80 percent of the generating units failed to perform at temperatures above their own documented minimum operating temperatures.

Source: December 2022 Winter Storm Elliott Grid Operations: Key Findings and Recommendations.

Several electric grid operators had to shed firm load to maintain system reliability, with a total of 5,000 MW shed at different times

During the storm, named “Winter Storm Elliott,” the Tennessee Valley Authority (TVA) balancing authority (BA) experienced the most severe impact, enduring almost eight hours of load shedding, and 3,000 MW at its worst point.

Duke Energy Carolinas (DEC) and Duke Energy Progress (DEP) BAs collectively shed load for three hours, with a maximum reduction of 1.9 GW. The Louisville Gas and Electric–Kentucky Utilities (LGE-KU) BA faced approximately four hours of load shedding, with a peak reduction of 300 MW.

Dominion Energy South Carolina and Santee Cooper BAs shed 94 MW and 86 MW for 9 and 17 minutes, respectively.

According to the report, dry natural gas production in the lower 48 states dropped 16 percent from December 21 to December 24.

Natural gas pipeline pressures dropped largely because of freeze-related production declines in production of Marcellus (23 percent) and Utica (54 percent) shales, as well as other natural gas infrastructure freeze- and equipment-related problems. These included wellhead freeze-offs, processing plant disruptions and poor road conditions which prevented maintenance.

Consolidated Edison (ConEd), which serves the greater New York Metropolitan area, “faced reliability-threatening low pressures on its delivery pipelines, forcing it to declare an emergency and use its own liquefied natural gas facility to maintain service.”

63 natural gas-fired generator outages or derates, a total of 10,038 MW, were due to firm gas transportation curtailments during the storm.

11 key recommendations

The report outlines 11 key recommendations to prevent similar events during extreme winter weather.

These recommendations include cold weather reliability enhancements for power generators, natural gas infrastructure, gas-electric coordination and electric grid operations.

The report calls for robust monitoring of current cold weather reliability standards, an independent technical review of cold-related outages and the establishment of reliability rules for natural gas infrastructure through legislative or regulatory measures.

Additionally, the report recommends enhanced communication during extreme cold weather events among gas and electric grid operators and gas distribution companies. An independent research group should assess the need for additional gas infrastructure to support grid reliability and gas utilities’ requirements, the report recommends.

“It’s abundantly clear that we must make major improvements to the cold-weather reliability of both the natural gas and electricity production and grid systems,” FERC Chairman Willie Phillips said in a statement. “I have said repeatedly: Someone – it doesn’t have to be FERC – must have authority to establish and enforce natural gas reliability standards. And some recommendations from the 2021 Uri report are still not implemented. Please get that done. It shouldn’t take five winter storms in 11 years to show us the gravity of the situation we find ourselves in.”

The report stems from an inquiry initiated by FERC and NERC staff shortly after Winter Storm Elliott.

The final report is expected to be published later this fall.