What happened in 2021
February 10-20, 2021. A prolonged cold snap across the central US. Texas hit -2°F in places. The grid experienced the worst outage in state history: around 4.5 million customers lost power, most for days. Water systems failed without power. 246 deaths were attributed to the storm. Wholesale electricity hit the $9,000/MWh cap for days in a row.
Why: roughly half the state's generation capacity went offline. Natural gas plants lost supply because wellheads froze. Wind turbines iced. Nuclear plants tripped on frozen water intakes. Coal plants had coal pile freezing issues. ERCOT's reserve margin — already thin — evaporated. Rolling blackouts became "firm load shed" as the grid operator scrambled to keep the whole thing from crashing.
What's changed
Weatherization requirements
SB 3 (2021) requires power plants and natural gas facilities to weatherize against extreme cold. The PUC set specific standards. Compliance is inspected and enforced, with fines for non-compliance. This is the single biggest reliability fix from 2021.
Reserve margin rules
ERCOT is required to plan for more conservative reserve margins and to use longer-duration demand forecasts. The Texas Energy Fund was created to incentivize dispatchable (natural gas, battery storage) capacity.
Communication with the natural gas industry
Gas producers and pipelines were not classified as "critical infrastructure" before 2021, so they were cut off during load shed — which cut off the fuel supply to the gas plants trying to generate. SB 3 created a new critical infrastructure designation and coordination requirements.
Price caps
The $9,000/MWh offer cap is still in place, but residential pass-through of wholesale spot prices was restricted. The plans that generated five-figure monthly bills (certain indexed products) were effectively banned for residential customers.
What hasn't changed
Texas is still an island
ERCOT isn't meaningfully interconnected with the rest of the US grid. A future extreme event still can't easily import capacity. There are some small DC interties and a few market-coupling proposals, but nothing at scale.
Reserve margins are still thin
Texas electricity demand is growing faster than new generation is being built — driven by population growth, EV adoption, and industrial/data-center demand. ERCOT's most recent Seasonal Assessment of Resource Adequacy continues to flag tight reserve margins during peak summer and winter.
Renewable variability
Texas is the largest wind and near-largest solar producer in the US. Renewables are critical for summer peak (solar happens to align with AC demand). But winter peaks often happen at dawn when solar is near zero and demand for heating is high. Wind is better correlated with winter peak but still variable.
Where it nets out
The grid is more reliable than it was in 2020. Weatherization is real. Uri is less likely to repeat as-is. But Texas continues to run tight margins, and a second-of-its-kind extreme weather event would still stress the system. The state is investing in more dispatchable capacity through the Texas Energy Fund, but those plants take years to build.
For you as a customer: a generator, a battery system, or at minimum a warm-weather emergency kit (blankets, water, flashlights, phone battery) is reasonable insurance in Texas in 2026.