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. 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. Natural gas generation rose 14% over the same period, while generation from solar, wind and hydropower declined. During Fern, petroleum became the predominant energy source, beginning around midday Jan. 24 and lasting until early Jan. 26, EIA said. 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.