Making the grid more climate resilient: Report on February 2021 cold weather outages in Texas and south-central US highlights challenges – Energy and natural resources

The November 16, 2021 report on the February 2021 cold weather outages in Texas and the south-central United States1 (Report) by staff of the Federal Energy Regulatory Commission (FERC), North American Electric Reliability Corporation (NERC) and certain regional entities recognized by NERC2(Regional Entities) describes the extreme cold event (event) that occurred between February 8 and 20, 2021, and its impact on the reliability of the bulk electrical system (BES or grid) in Texas and downtown -south of the United States.

During the event, extremely cold temperatures and freezing precipitation caused 1,045 individual BES generating units (with a combined nominal capacity of 192,818 MW) in Texas and the south-central United States to experience 4 124 failures, downgrades or startup failures. Each affected individual production unit could, and in many cases, had multiple failures due to the same or different causes.

To get an idea of ​​the significance of the production unit failures during the event, including already planned or unplanned production, the Electric Reliability Council of Texas (ERCOT) estimated that 34,000 MW of production were on average unavailable (based on planned capacity) for more than two consecutive days. , from 7 a.m. on February 15 to 1 p.m. on February 17, or nearly half of ERCOT’s peak electrical load in winter of 69,871 MW.

The event was the fourth cold-related event in the past 10 years to compromise BES reliability and, with a combined manual firm load shedding of 23,418 MW, the largest controlled load shedding event in state history. -United. In each of the four BES events, planned and unplanned generator set failures resulted in energy emergencies and, in 2011,3 2014 and 2021 triggered the need to remove the firm BES load. The unplanned production outages that escalated during the event were more than four times greater than the previous largest event.

The main findings of the report include (added emphasis):

  • From February 8 to 20, in the event area, a total of 1,045 individual production units – 58% natural gas, 27% wind, 6% coal, 2% solar, 7% other fuels and less 1% nuclear – experienced 4,124 outages, decommissions or failed start-ups. Among these failures, downgrades and startup failures, 75% were caused by either freezing problems (44.2%) or fuel problems (31.4%).
  • Natural gas supply problems caused the majority, 87%, of the 31.4% of outages and downgrades due to fuel problems and caused the start-up of 27.3% of all outages, downgrades and failures during the event.
  • In addition to the 44.2% of outages and downgrades caused by freezing issues, the 21% caused by “mechanical / electrical problems” also indicated a relationship with cold temperatures– As temperatures decreased, the number of generator sets taken out of service or decommissioned due to mechanical / electrical problems increased.
  • Despite several prior recommendations from FERC and NERC, as well as annual reminders in various Regional Entity workshops, that production units take steps to prepare for winter (and detailed suggestions provided for overwintering) , 49 SPP production units (15% or 1,944 MW of nominal capacity), 26 ERCOT units (7% or 3,675 MW) and 3 MISO Sud units (4% or 854 MW) still had no wintering plans, and 81% of frost-related production unit failures occurred at temperatures above the design ambient temperature specified for the unit. Generating units that experienced freeze-related failures above the unit’s stated ambient design temperature represented approximately 63,000 MW of rated capacity.

The report’s recommendations include proposed revisions to mandatory electricity reliability standards (reliability standards) and policy actions to mitigate the production and distribution of natural gas.

The proposed revisions to the reliability standards introduced by the report would require:

  • Generator owners (GO) to identify and protect critical components in cold weather;
  • OG to modernize existing production units and require new production units to be built to operate at specific ambient and weather temperatures based on extreme temperature and weather data and account for the effects of precipitation and the cooling effect the wind ;
  • GOs or generator operators (GOPs) to conduct annual training on wintering plans;
  • GOs experiencing freeze-related failures to develop corrective action plans;
  • GOs or GOPs to provide the applicable balancing authority (BA) with the percentage of the total generating unit capacity that the BA can rely on during “expected local cold weather”; and
  • GOs to account for the effects of precipitation and the accelerated cooling effect of the wind when providing temperature data to BAs.

However, the report also recommends that: FERC, NERC and regional entities organize a joint technical conference to discuss how to improve winter readiness of production units before the revisions to the recently approved reliability standards become effective. ; and GO / GOP freeze protection plans include certain periods of inspection and maintenance (eg, before and after winter and before specific cold weather episodes).

With respect to natural gas supplies (the second most common cause of unplanned outages and downgrades), the report recommends that Congress, state legislatures, and regulators with jurisdiction over gas infrastructure facilities natural require these facilities to implement and maintain cold weather preparedness plans; that natural gas infrastructure facilities take voluntary measures to prepare for cold weather; and that GOs / GOPs identify the reliability risks associated with their natural gas contracts so that they can provide BAs with the percentage of total production unit capacity that the BA can rely on during ‘local cold weather’ foreseen ” ; and, to address the recurring challenges arising from the interdependence of gas-electricity infrastructure, that FERC consider establishing a forum to identify concrete actions to improve the reliability of the natural gas infrastructure system needed to support the BES.

As a result of the event, Texas passed Senate Bill 3 (SB3) and, as required under it, the Texas Public Services Commission (PUCT) passed4 regulations required to withstand the weathering of power generation at ERCOT, and the Texas Railroad Commission (RRC) has adopted5 new regulations concerning the Critical Designation of Natural Gas Infrastructures and customers.

It is clearly too early to say whether these new requirements will be effective in preventing the impacts of other extreme weather events like The Event, and, of course, other regulators may need to take similar action for the BES to avoid events. similar in the future. .


1 Report assumes familiarity with electrical transmission system and production unit operations, but includes related material for other readers. The FERC report and related news releases can be viewed here.

2 Namely, Midwest Reliability Organization, Northeast Power Coordinating Council, ReliabilityFirst Corporation, SERC Corporation, Texas Reliability Entity, and Western Electricity Coordinating Council.

3 For which a joint FERC / NERC report has also been prepared and is available here.

4 The PUCT adopted the final regulation, the new 16 Texas Administrative Code (TAC) §25.55, on October 21, 2021; see here.

5 The RRC adopted a new regulation, 16 TAC §3.65, on November 30, 2021; see here.

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