Reliability Success Story: Extreme Weather Event Mitigation

Over the past several years the Texas Interconnection—through the joint efforts of the Public Utility Commission of Texas (PUCT), the Electric Reliability Council of Texas (ERCOT), and a wide range of other stakeholders—has made excellent progress at improving the reliability and resilience of the Bulk Power System (BPS). Repeated, major cold weather events (most notably Winter Storm Uri in 2021) prompted overhaul of rules to implement changes for improved reliability and resilience in the face of extreme weather events, at both state and federal levels.

When the Electric Reliability Organization (ERO) Enterprise (the North American Electric Reliability Corporation (NERC) and its Regional Entities) was first established, there wasn’t much of a role for Regions to verify that registered entities had implemented quality winterization plans. After the 2011 winter storm, voluntary generator winter readiness site visits were initiated in ERCOT and NERC made guidelines available to entities. Additionally, there were new state rules requiring entities to file attestations that they were prepared for the winter.

In 2018, a major winter event affecting Louisiana and Arkansas prompted the Federal Energy Regulatory Commission (FERC) to order NERC to develop mandatory cold weather Reliability Standards. The development of new NERC Reliability Standards is usually a lengthy process, so they still were not in place in February 2021.

Winter Storm Uri was a turning point for electric reliability. Much of the North American Bulk Power System (BPS) suffered impacts to some degree, with Texas being especially hard hit. At the time, the National Weather Service issued winter storm warnings for all 254 Texas counties (the first time that had ever happened) and parts of the state spent hundreds of hours below freezing temperatures. Even before the coldest temperatures hit, Texas was already feeling the effects of a series of smaller-scale winter events that all culminated in the major outages that we saw. In the lead-up to the worst of the cold snaps, a lot of natural gas wells were preemptively “shut-in” in anticipation of the cold weather; and many wind turbines developed icing or reached cold-weather limits. Much equipment was already out of service, creating tight reserve margins, and when the worst of the cold hit, significant amounts of generation failed while demand skyrocketed. A third of the entire generation fleet in Texas was affected, especially natural gas and wind generation, but all fuel types suffered losses. At one point around a quarter of the total generation in Texas was offline or derated due to weather-related issues, while another quarter of the fleet was impacted by other mechanical and fuel-related problems (that may well also be weather-related). Firm-load shed was needed to keep the grid from collapse, and emergency conditions lasted five days. The February 2021 Cold Weather Outages in Texas and the South Central United States | FERC, NERC, and Regional Entity Staff Report gives additional details.

After Uri, it was determined that nearly two out of three Texans went without power at some point, many for multiple days. The damages reached $300 billion and tragically hundreds of people died as a consequence of not having electricity to heat their homes. Since then decisive actions were taken to prevent a recurrence of the weather-related equipment failures, as well as other problems with communications and demand management programs. 

NERC’s cold weather Reliability Standards, packaged together in project 2019-06, in development since FERC ordered them in 2018, were approved and implemented. These Standards for the first time created mandatory reporting requirements for registered entities to have cold weather response plans subject to regulatory assessment. Furthermore, generators were now required to provide cold weather operating data to Reliability Coordinators (RCs) like ERCOT. While these draft Standards were being prepared, FERC, NERC, and the Regions published the report mentioned above, along with a list of twenty-eight recommendations based on lessons learned from Uri. These recommendations prompted another Standards project to add detailed expectations for winterization, 2021-07 Extreme Cold Weather Grid Operations, Preparedness, and Coordination.

Compared to project 2019-06, project 2021-07 and its associated Reliability Standard EOP-012 moved forward at a rapid pace, going into effect on October 1, 2024—a little over a year after project 2019-06 was implemented. In its final approval, FERC issued another series of directives to NERC to tighten up requirements even further, which brings us to the current project 2024-03 Revisions to EOP-012, which is currently being reviewed by FERC.

While these new Standards were being introduced at a national level, Texas leveraged its unique position as the only single-state interconnection to move forward quickly on reforms at the state level. The first state legislation approved to address winterization came following a series of hearings in the Spring of 2021, Senate Bill 3. This led to development of PUCT Substantive Rule 16 TAC 25-55 that took effect in two phases, the first in October 2021 and the second in September 2022. This new rule expanded the already existing weatherization attestation requirements for generators with new, clearer criteria backed up by an ERCOT-run inspection program. It also extended weatherization requirements to transmission as well as generation, for both extreme summer heat as well as winter conditions. The state-level requirements in Texas and the NERC Standards both reflect significant contributions of industry stakeholders into rulemaking processes to produce achievable improvements.

NERC has also been involved with coordination between the electric and gas industries to improve communication and coordination. While NERC has no jurisdictional authority to implement rules for natural gas supply and transportation, the State of Texas does and addressed natural gas weatherization in Senate Bill 3. The Railroad Commission of Texas (RRC) implemented new rules for the natural gas industry in Texas. First, they established 16 Texas Administrative Rule No.3.65 to develop an electric supply chain map in partnership with the PUCT that identifies all gas facilities critical to electric generation. Additionally, Rule No. 3.66 establishes requirements for those critical gas facilities to meet reporting and weatherization requirements similar to the PUCT weatherization rules for generators and transmission providers.  The RRC conducts natural gas facility weatherization inspections to verify the work in the field.

Since these new rules administered by the PUCT and RRC took effect, over 10,000 facility inspections have been performed, confirming facility owners’ efforts to improve weatherization. NERC and the Regions are rolling out their approved winterization standards and providing advisory assistance to generator owners to prepare. While Texas hasn’t had cold weather on par with Uri since implementing these rules, in 2024, Winter Storms Enzo and Heather both tested the effectiveness of weatherization programs. Natural gas and generation rode through with minimal issues. Ensuring electric reliability requires constant vigilance from all stakeholders but with these and other mitigations at the national and state level, our grids are better prepared today for extreme weather.