Policy & Regulation

NERC: Generation forced-outage rates continue to increase

The regulatory authority’s 2024 State of Reliability report indicates that aging coal plants are increasingly unreliable due to reduced maintenance investment and abnormal cycling in response to rapid resource mix changes.
NERC: Generation forced-outage rates continue to increase

Conventional and wind generation forced-outage metrics remain at historically high levels, exceeding rates for all years prior to 2021, according to the North American Electric Reliability Corporation’s 2024 State of Reliability released last week. The annual NERC report reviews the previous year’s grid performance.

Despite no major events comparable to Winter Storms Uri (2021) or Elliott (2022), the weighted equivalent forced-outage rates (WEFOR) of baseload coal and cycled natural gas units remained high in 2023, the report noted. WEFOR measures the probability that a group of units will not meet their generating requirements because of forced outages or forced derates, according to NERC. The weighting gives larger units more impact to the metric than smaller units.

Although coal-fired generation experienced a large decrease in WEFOR in 2023 (12% in 2023 versus 13.9% in 2022), it remains above pre-2021 rates. While the age of coal units slightly correlates with WEFOR, NERC noted maintenance and reduced service hours have a greater impact than forced outages.

The regulatory body said industry statements suggest that “reduced investment in maintenance and abnormal cycling, which are being adopted primarily in response to rapid changes in the resource mix, are negatively impacting baseload coal unit performance.” Analysis shows that coal units operating below 60% capacity face higher outage rates, NERC said.

The WEFOR for wind generation increased to 18.9% in 2023 from 18.1% in 2022. This rise is concerning given the recent growth in wind generation, NERC said.

In 2024, new and expanded reporting requirements for both conventional and renewable generation were implemented. This would enable more comprehensive future analyses and assessments of both inverter-based resources and conventional generating units.

See the 2024 State of Reliability here.

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