At the peak of Winter Storm Elliott in late December, 24% of the PJM Interconnection’s generating capacity was unexpectedly offline, with gas-fired power plants making up about 70% of the unplanned outages, the grid operator said in a report released Monday.
“This level of generation outages was unprecedented and not anticipated,” PJM said.
Generators that failed to meet their capacity obligations during Winter Storm Elliott face about $1.8 billion in non-performance charges, representing 45% of the nearly $4 billion in capacity revenue for this capacity year, according to the report.
For the roughly 750 resources facing the penalties, the non-performance charges represent 83% of the nearly $2.2 billion they earned in capacity payments for the year, PJM said. Power plant owners are challenging the penalties at the Federal Energy Regulatory Commission.
Resources that provided more power than their obligations receive bonus payments from the penalties.
PJM said that on average 80% of bonus megawatts were produced by generation, 10% came from net imports from outside its footprint, 5% were produced by energy efficiency resources, and 5% were produced by demand response and “price responsive demand” resources.
Nuclear power plants received 34.5% of the bonus pool for generators, followed by gas at 29.2%, coal at 17.3% and wind at 13.7%.
Along with gas-fired power plants, load management programs performed poorly during Winter Storm Elliott.
Curtailment service providers told PJM they could reduce load by 4,336 MW on Dec. 23 and by 7,400 MW the following day, according to the report. However, they only delivered load cuts of 1,100 MW and 2,400 MW during the two days.
“The significant difference between the data provided to PJM about load curtailment capability and the actual performance clearly identify an opportunity and need to improve the rules and processes regarding load management capability estimates,” the grid operator said.
Most power plant outages were caused by equipment failures, likely resulting from the extreme cold on Dec. 23 and 24, though a lack of gas supply was also a factor, according to PJM, which runs the grid and wholesale power markets in 13 Mid-Atlantic and Midwest states and the District of Columbia.
PJM offered 30 recommendations in response to operations during Winter Storm Elliott. Some are being addressed in its Critical Issue Fast Path – Resource Adequacy process that the grid operator expects will lead to a proposal to revise its capacity market by October.
“While PJM and its members were able to maintain reliability during Winter Storm Elliott, the increasing volatility of weather patterns and reliance on gas generation underscore the need to advance the performance of operations, planning and markets for the increasing risk presented by the winter season,” the grid operator said.
PJM is considering setting summer and winter accreditation values for thermal power plants to better reflect their performance during those seasons, according to a Monday presentation. The estimated accreditation value for the thermal fleet for 2026/27 is 95% in the summer and 78% in the winter, PJM staff said.
In the winter, the estimated value for gas-fired combined cycle and combustion turbine units is 76% and 63%, respectively.
During Winter Storm Elliott, PJM was a net exporter of power, except for a brief period on Dec. 24, according to the report.
PJM exported power to the Tennessee Valley Authority, Duke Carolinas and Duke Energy Progress, and Louisville Gas and Electric and Kentucky Utilities when they were experiencing rolling blackouts, the grid operator said. Without those exports, the blackouts would likely have been more extensive, according to PJM.