A severe winter storm in December 2022 that caused a wave of unplanned power plant outages across the eastern US underscored the need to weatherize generating units and improve coordination with the natural gas sector, according to preliminary findings from a joint inquiry.

The cold weather event forced more than 70,000 MW of generating capacity offline as most of the US Midwest, mid-Atlantic, Northeast and Southeast experienced sub-freezing temperatures over the Christmas holiday weekend. Gas-fired generators accounted for the bulk of the outages.

The extreme weather event was the fifth wide-area winter storm in 11 years to prompt a joint inquiry by staff of the Federal Energy Regulatory Commission and North American Electric Reliability Corp.

Initial findings from the joint inquiry into the storm, presented by staff at FERC's June 15 monthly open meeting, echo those from inquiries into the root causes of deadly Texas blackouts in February 2021 and similar but less severe cold weather events in 2011, 2014 and 2018.

"We're finding that unplanned generating unit outages continue to be the primary challenge that we see in all of these events," Heather Polzin, an attorney adviser and reliability coordinator in FERC's Office of Enforcement, said during a presentation at the meeting.

'A reliability gap'

The top three causes of unexpected generator outages across all five events were mechanical and electrical issues, equipment freezing, and fuel supply issues, according to the presentation.

"We're seeing the same three causes, so therefore we think that it makes all the sense in the world to continue full steam ahead on implementing prior recommendations," Polzin said.

In February, FERC approved new weatherization standards for generators and transmission operators in response to the Texas blackouts. The standards require generators to implement freeze protection measures and transmission operators to minimize power cuts to critical loads such as gas supply facilities during rotating customer outages.

However, the reliability of the natural gas system remains a concern, FERC acting Chairman Willie Phillips told reporters following the June 15 meeting. Dry natural gas production in the Lower 48 dropped 16% from Dec. 21 to Dec. 24, 2022, with the Marcellus and Utica shale regions experiencing declines of between 22% and 54% over that period, according to the staff presentation.

In contrast to the US power sector, the nation's natural gas supply system is not overseen by a federal agency tasked with ensuring its reliability, Phillips noted.

"I believe this is a reliability gap," Phillips said. "I, once again, call for some entity to have responsibility for the gas system's reliability. It doesn't have to be FERC, but someone needs to have responsibility for that."

The inquiry team is still quantifying the causes and impacts of facility outages during the December 2022 cold weather event, dubbed Winter Storm Elliott, and will likely present findings from a final report at a future commission meeting, FERC staff reported.

In the wake of the Texas blackouts, the North American Energy Standards Board has been convening regular meetings with industry stakeholders as part of a gas-electric harmonization forum. The forum has highlighted what some participants described as a "disconnect" between how wholesale power markets operate and natural gas supplies are scheduled. A final report from the forum is expected later this year and may include recommendations for federal legislation.

Commissioners highlight forecasting, market design challenges

During FERC's June 15 meeting, Commissioner Allison Clements said the December 2022 storm illustrated how extreme cold weather events are becoming more difficult to predict.

NERC's 2022 winter reliability assessment did not identify any concerns for the 13-state PJM Interconnection LLC region and noted that PJM's installed capacity is almost three times its reserve requirement. The reliability analysis only assumed approximately 18 GW of unplanned generation losses in PJM under a worst-case scenario, but PJM experienced 46 GW of unplanned outages at the height of the storm, Clements observed.

"To me, it shows that reserve margins are an increasingly inadequate tool to predict winter sufficiency," Clements said.

PJM also underestimated its peak load by 8% on Dec. 23, 2022, and by 9% the following day. A temperature drop of 29 degrees F over 12 hours in some areas Dec. 23, 2022, surpassed the previous PJM record of a 22-degree drop during a 2014 polar vortex.

Clements said the wide-area cold event also demonstrated the value of interregional electric transmission capability. PJM's ability to import power from the neighboring Midcontinent ISO region helped it avoid the need to implement rotating grid outages, Clements said.

Commissioner Mark Christie called the June 15 presentation a "perfect segue" into a forum scheduled for directly after the meeting on the future of the PJM capacity market.

"It's fine to mandate weatherization, but you can't separate that issue from the issue of market design, and how do you pay for it?" Christie said. "Weatherization requires capital expenditures. Energy markets don't compensate for capital expenditures — that's what the capacity market was set up to do."

In addition to the PJM capacity market forum, FERC has also scheduled a June 20 gas-electric forum in Portland, Maine, to explore potential solutions for shoring up grid reliability in the New England region.

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