Winter Storm Fern stress-tested the grid. How did the generating fleet perform?
- Coal and natural gas generation increased sharply during Winter Storm Fern, offsetting declines in wind, solar and hydropower as sustained cold pushed electricity demand higher.
- Regional fuel constraints shaped operations, with New England relying heavily on oil-fired and fuel-switching units while other regions prepared emergency tools to preserve reliability.
- ERCOT managed the Texas grid during Fern without issuing an Energy Emergency Alert or experiencing systemwide outages, relying on weatherization, increased reserves, and recent market design changes, the grid operator said.
Winter Storm Fern delivered the kind of cold that grid operators and generators dread, driving up electricity demand, squeezing fuel systems and forcing regions to lean hard on dispatchable resources that can run when wind and solar output dips.
So how did North America’s generating fleet perform during Fern as wintry conditions continue to grip large swaths of the U.S., with additional cold weather forecast to move into parts of the East Coast this weekend?
“It’s still probably a little early to tell,” NERC’s John Moura said during a media briefing Thursday as the cold persisted in parts of the country. “But what I will say is, you know, as we’re looking at the data, both on the electricity generation performance, but also the gas performance, things are holding up.”
The dispatch response was clear in the federal data. In the week ending Jan. 25, coal-fired generation in the Lower 48 states increased 31% from the prior week as Fern affected large portions of the country, according to the U.S. Energy Information Administration (EIA). Natural gas generation rose 14% over the same period, while generation from solar, wind and hydropower declined.
Coal’s share of total Lower 48 generation climbed to 21% during that week, up from 17% the previous week, EIA said, while natural gas contributed 38% and nuclear was about 18%.
In New England, the fuel picture turned more extreme. Although petroleum accounts for less than 1% of total U.S. utility-scale generation, the region leans on oil-fired units during winter peaks when cold weather drives demand and natural gas availability tightens. During Fern, petroleum became the predominant energy source, beginning around midday Jan. 24 and lasting until early Jan. 26, EIA said.
EIA noted that New England holds a disproportionate share of the nation’s petroleum-fired capacity and that petroleum-fired generation reached almost 8.0 GW between Jan. 25 and Jan. 26, exceeding the capacity from units that predominantly use petroleum. That indicates fuel-switching units contributed as well, including a sizable portion of the region’s natural gas fleet that can burn distillate fuel oil when gas is too costly or unavailable.
ISO New England is now bracing for the next phase: sustained high demand as the cold lingers, and the operational challenge of replenishing stored fuels. The grid operator said it plans to publish updated 21-day forecasts each morning through the weekend, rather than its typical weekly cadence, to reflect heightened uncertainty.
ISO New England also said it will request a two-week extension of the existing U.S. Department of Energy order under Section 202(c) of the Federal Power Act. The order, which allows all available resources, including those subject to emissions or other permit limits, to operate if needed, currently expires Jan. 31. ISO New England said it will ask DOE to extend it through Feb. 14.
Further south and west, Texas avoided the kind of systemwide emergency that still looms over winter planning after 2021. In a post-event report dated Jan. 28, ERCOT said it managed the statewide grid through Fern without calling for conservation, without issuing an Energy Emergency Alert, and without any systemwide outages tied to grid conditions.
The grid operator said it leaned on mandatory weatherization, increased reserves, earlier operational actions and a market design change implemented in December 2025 that incorporates batteries into real-time co-optimization.
Some outages did occur in Texas, ERCOT said, but they were localized and tied to ice and downed lines rather than bulk system failures.
In PJM’s footprint, the operational posture included preparing for a tool that, until recently, sat mostly outside the normal reliability playbook: directing certain customer-owned backup generation at data centers and other large-load sites to operate under emergency conditions.
On Jan. 26, DOE issued an emergency order to PJM under Section 202(c) authorizing PJM to direct identified backup generation resources to operate as a last resort before an Energy Emergency Alert Level 3 is declared, or during an EEA 3.
PJM said in an update that the expedited federal process for emergency orders tied to backup generators could help as a last resort if the generation fleet or transmission system experiences major outages, and that it has been working with DOE to identify data center customers who have volunteered to transition to backup generation if needed.
NERC, which highlighted winter energy risks in its 2025-2026 Winter Reliability Assessment, is watching Fern as a real-world stress test of fuel and performance assumptions.
Moura said Thursday that the storm has already produced some operational surprises, including curtailments of interconnections between New England and Canada.
He also pointed to forced outages, noting that a detailed accounting will come later.
“We’ve had a good amount of generators that have been forced out, offline,” he said. “We will come to find those.”
Still, Moura said there is evidence that winterization investments and standards have improved performance compared with prior years.
“What we have done is put a number of NERC standards in place, and there’s been a lot of PUC action on winterization,” he said. “Billions of dollars in winterization have been invested in winterizing the generation fleet, and some of that seems to have worked.”
Coal’s role during Fern sits at the center of a larger debate about reliability through the energy transition, and Moura addressed it directly when asked whether coal provided primary support during the event.
“I think it’s an essential part of the portfolio today,” he said, while also noting the fleet’s limitations, including higher forced outage rates in winter conditions and challenges such as frozen coal piles.