Legal & Regulatory

ERCOT Confident Generators Deficient During Uri Freeze Debacle Ready for Winter

The vast majority of 324 electric generation units and transmission facilities in Texas have fully met or “go beyond” new state winter weatherization requirements, the Electric Reliability Council of Texas (ERCOT) said in a final readiness report filed with the Public Utility Commission of Texas (PUCT) on Jan. 18.

Onsite inspections at 302 generation units during December—representing 85% of the outage-related megawatt-hours lost during Winter Storm Uri last February—show that 299 generation units had “cleared all deficiencies,” the grid operator said. All 22 transmission facilities inspected also cleared deficiencies.

“We are confident these 321 inspected facilities either meet or go beyond the new requirements from the Commission and we will continue to work with the other 3 facilities [which represent 532 MW, 0.4% of ERCOT’s total generation fleet] to ensure they correct remaining deficiencies,” Woody Rickerson, ERCOT’s vice president of System Planning and Weatherization, said in a statement late on Tuesday. “Our teams spent thousands of hours preparing for and conducting these 324 on-site inspections to ensure the electric grid is prepared for winter.” 

More Stringent Checks

ERCOT said state-mandated inspections at the 302 generator resources conducted between Dec. 2 and Dec. 22 included a review of mandatory winter weather readiness reports, as well as a physical inspection to determine the accuracy of these reports. Generator winter weather readiness reports, prepared by generator owners or operators, consist of a completed report template, a checklist of specific items evaluated, and documentary evidence, including photographs.

In general, these inspections demonstrate that the owners of generation and transmission infrastructure in the ERCOT region have taken the Commission’s weatherization mandate seriously and have demonstrated good faith in complying with the rule’s requirements,” ERCOT noted. “In fact, many generation entities and TSPs [transmission service providers] adopted winter weatherization measures that go above and beyond these requirements.”

While ERCOT did not reveal which generators it inspected, it said it identified “potential deficiencies” at only 10 units, a total of 2.2 GW. As of Jan. 17, “all but three of these deficiencies have been addressed.”

ERCOT also monitored compliance associated with “good clause” assertions, which are essentially legally permitted detailed justifications declared by grid entities for failing to comply with one or more of the weatherization requirements. “In total, 312 of the readiness reports submitted by 127 generation entities included a total of 532 good-cause assertions, although only 244 of the readiness reports actually asserted noncompliance with one or more of the sub-requirements of the rule.”

ERCOT noted a large number of these assertions stemmed from non-applicability of certain requirements. “[F]or example, many wind generation owners have asserted good cause for non-compliance with the sub-requirements to confirm operability of air moisture prevention systems or to install windbreaks at the facility because these improvements are not relevant to wind turbines,” it explained.

While 427 of the 532 good-clause generator assertions had been “resolved or closed out” as of Jan. 17, 45 good-clause assertions are still pending. ERCOT, meanwhile, called on the PUCT to evaluate 60 good-clause assertions because “it disagreed with the assertion” or “did not provide sufficient information to justify the assertion.” For entities that have already proposed a required compliance plan, compliance dates are “within the first quarter of 2022,” it said.

In addition, ERCOT conducted similar inspections at 22 transmission provider–owned substations. Inspections identified “potential deficiencies” at six facilities, but most were “generally minor items, such as cabinet heaters out of service or missing weather stripping on cabinet doors on the day of inspection.” All deficiencies have since been resolved, ERCOT said.

ERCOT’s Evolving Weatherization Spot Check Program

ERCOT established a winter weatherization “spot check” program following the February 2011 cold weather event and, until the winter of 2019/2020, it typically visited 75 to 80 generating units per year to assess their readiness for the upcoming winter season. But for winter 2020/2021, owing mainly to the COVID-19 pandemic, that program was conducted remotely.

The latest checks stem from an evolving range of requirements. After the February 2011 event, ERCOT’s spot checks were based on PUCT rules and ERCOT Nodal Protocols, and included a “comprehensive” checklist based on guidelines and data from the North American Electric Reliability Corp. (NERC), mainly focused on a generator’s previously experienced freeze issues. For example, inspections included a review of maintenance records for freeze protection measures such as heat tracing, insulation, and instrument air systems, as well as for dual-fuel units.

But after the 2014 Polar Vortex event, “knowledge and identification of facility critical components became a point of emphasis, including maintenance of heat tracing and insulation systems associated with those critical components, as well as tracking heat tracing test records,” notes the Federal Energy Regulatory Commission (FERC) and NERC’s November 2021–released joint report on the February 2021 outages in Texas and the South Central U.S. “After the January 2018 event, ERCOT prioritized incorporating instrument air systems into the weatherization programs,” it said.

In addition, ERCOT has over the past few years required each “surveyed” generating entity to submit an annual declaration stating that it has or will complete all weather preparations required by its weatherization plan for critical equipment. Before Winter Storm Uri unleashed its three-day, statewide freeze on Feb. 14, 2021, 96% of 153 generators surveyed within ERCOT had declared a winter readiness completion. Seven entities even reported “outstanding winter preparations for 18 natural gas-fired generating units, including protections as critical as heat trace repair and replacement, windbreaks, and insulation of transmitter sensing lines, that were not expected to be completed until as late as December 23, 2020,” the report notes.

A Brief Assessment of Generator Debacles During Uri

Still, in what is perhaps the most sobering recent reliability crisis in the U.S., Winter Storm Uri’s unprecedented reach disabled an average 34,000 MW of unplanned generation losses across ERCOT for more than two consecutive days, from 7:00 a.m. February 15 to 1:00 p.m. February 17—equivalent to nearly half of its all-time winter peak electric load of 69,871 MW. Meticulously chronicling factors that led to the event, NERC and FERC’s report suggests ERCOT—like the Southwest Power Pool (SPP) and the Midcontinent Independent System Operator (MISO), which also suffered widespread generator outages—knew the arctic front was expected.

Though three grid operators issued cold weather preparation notices to their generation and transmission operators from Feb. 8 through Feb. 20, 2021, a total of 1,045 individual generating units—58% natural gas-fired, 27% wind, 6% percent coal-fired, 2% solar, 7% other fuels, and less than 1% nuclear—across the three regions experienced 4,124 outages, derates, or failures to start, the report says. Of those outages, derates, and failures to start, 75% were caused by either freezing issues (44.2 %) or fuel issues (31.4 %), the report says. Of the 44.2% of outages and derates caused by freezing issues, 21% were caused by “mechanical or electrical issues.”

Incremental Unplanned Generating Unit Outages, Derates, and Failures to Start, Total Event Area: by Cause, by Fuel Type, and by MW of Nameplate Capacity. Source: FERC/NERC

“Despite multiple prior recommendations by FERC and NERC, as well as annual reminders via Regional Entity workshops, that generating units take actions to prepare for the winter (and providing detailed suggestions for winterization), 49 generating units in SPP (15%, 1,944 MW of nameplate capacity), 26 in ERCOT (7%, 3,675 MW), and three units in MISO South (4%, 854 MW), still did not have any winterization plans, and 81% of the freeze-related generating unit outages occurred at temperatures above the unit’s stated ambient design temperature,” the report stressed. Generating units that experienced freeze-related outages above the unit’s stated ambient design temperature represented about 63,000 MW of nameplate capacity, it said.

How Did Generators Prepare for Winter Storm Uri?

According to the  Federal Energy Regulatory Commission’s (FERC’s) and the North American Electric Reliability Corp.’s (NERC’s) November 2021–released joint report on the February 2021 outages in Texas and the South Central U.S., many generators took steps to ensure they would remain in operation during the severely cold period.

Wind Generators. In ERCOT and SPP, wind generators performed annual service and winterization checks, canceling planned maintenance, ordering additional nitrogen to maintain the hydraulic braking system, checking operational conditions of critical heating systems, and generally activating emergency response teams.

Solar Units. Teams prepared inverters by checking the functionality of heaters, ensuring adequate temperature settings and functioning alarms, and activating emergency response teams.

Natural Gas Generators. Along with deploying emergency plans and adding personnel, gas generators checked natural gas inventories and placed fuel commodity orders in advanced. They also tested heating supplies and protective equipment; installed temporary heat tracing, tarps, and insulation to prevent equipment from freezing; verified pumps were running; and checked temperature gauges. In addition, actions included placing snow removal equipment and portable generators connected to batteries on site; opening water valves and low-point drains; checking that freeze protection panels were in service and all circuits were energized; and, for dual-fuel units, filling condensate systems to prepare for water injection usage if required to change to fuel oil. Some generators also had their lube oil cooling water pumps “placed in continuous service when the temperature is expected to be 25 degrees or less for at least eight hours,” the report says.

Oil-Fired Units. Oil-fired units also performed maintenance, checked heat tracing, and checked temperature gauges. “In addition, they prepared by insulating critical control valves, test-starting black start diesel units, procuring extra fuel oil and filling fuel and storage tanks onsite, staging additional diesel heaters and barriers/wind breaks, and verifying pumps, heaters and igniters were operational. Dual-fuel generators that would normally burn natural gas also burned a mixture of gas and oil to conserve gas,” the report says.

Coal-Fired Units. Finally, coal-fired units across all regions, like other generators, placed and inspected insulation, added heaters around critical components (such as at coal mills), and brought in additional operations and maintenance personnel to prepare for and respond to the event. In ERCOT, generators also “prepared by coating coal cars to prevent coal from sticking due to freezing and maintaining water flow through piping in offline systems,” the report says. To obtain maximum performance from coal units located in Texas, generators also worked with the Texas Commission on Environmental Quality to relax emissions constraints on Feb. 15. In SPP, an entity reportedly started auxiliary boilers early for additional building heat. And in MISO South, preparations included inspecting heat tracing and insulation, installing wind breaks, and checking inventory of ice melt, the report says.

What Does Texas’s New Mandatory Weatherization Rule Require? 

In the devastating winter storm’s aftermath, Texas acted aggressively to address grid reliability deficiencies uncovered by the debacle. After nearly four months of investigation, repeated legislative hearings, and political contention about why the complex event occurred, Texas legislators proposed reforms, including at ERCOT, as well as for mandatory generator weatherization.

Texas Gov. Greg Abbott, who had deemed these measures as “emergency items” for the 87th session, signed SB 3 on June 8, 2021. SB 3 essentially directed the PUCT to adopt, within a tight six-month timeframe, new reliability standards that will apply to municipal entities, co-ops, qualifying facilities, power generation companies, and otherwise exempt wholesale generators that participate in ERCOT.

After a rapidly rolled-out request for information, which garnered a range of comments from the state’s generators and a handful of hearings, the PUCT ultimately proposed a first phase of winterization rulemaking on Aug. 26, 2021. The final first-phase rule, which took into account some stakeholder input, followed shortly afterward on Oct. 26, 2021. The PUCT has said the second phase of rule-making will target “the creation of a more comprehensive, year-round set of weather emergency preparedness reliability standards that will be informed by ERCOT’s ongoing weather study.”

The PUCT told POWER that the final weatherization rule “translates established industry best practices into specific actions backed with inspections and the power of significantly increased financial penalties.” Still, it acknowledged that its generator readiness standards were drawn up at least in part by Quanta Technologies more than 10 years ago. Requirements for TSPs, meanwhile, were drawn from a FERC and NERC 2011 analysis of the Feb. 1–5, 2011, cold snap.

Despite criticism that the rulemaking may not yet be effective enough, the final rule has required quick implementation of a suite of measures—by Dec. 1, 2021—by generators within ERCOT. These include:

  • Implementing weather emergency preparation measures to ensure sustained operation of all “cold weather critical components.” These include weatherization, onsite fuel security, staffing plans, operational readiness, and structural preparations; secure sufficient chemicals, auxiliary fuels, and other materials; and personnel required to operate the resource.
  • Installing adequate wind breaks for resources susceptible to outages or derates caused by wind.
  • Enclosing sensors for cold weather–critical components.
  • Inspecting thermal insulation for damage or degradation and repairing damaged or degraded insulation.
  • Confirming the operability of instrument air moisture prevention systems.
  • Conducting maintenance of freeze protection components for all applicable equipment, including fuel delivery systems controlled by the generation entity—“the failure of which could cause an outage or derate,” the rule notes—and establishing a schedule for testing of such freeze protection components on a monthly basis from November through March.
  • Installing monitoring systems for cold weather critical components, including circuitry providing freeze protection or preventing instrument air moisture.
  • Providing training on winter-weather preparations and operations to relevant operational personnel.
  • Determining minimum design temperature or minimum experienced operating temperature, and other operating limitations based on temperature, precipitation, humidity, wind speed, and wind direction.

The rule specifies that generators must detail their efforts to achieve the above in an ERCOT form (a draft form is here), and accompany it with a “notarized attestation.” The rule, meanwhile, directs ERCOT to conduct inspections by prioritizing its inspection schedule based on “risk level”—including whether a generation resource is critical for electric grid reliability; has experienced a forced outage, forced derate, or failure to start related to weather emergency conditions; or has other vulnerabilities related to weather emergency conditions.

Some aspects of the rule remain murky, however, including penalties. ERCOT on Tuesday said the PUCT will determine any potential enforcement actions resulting from the inspections. “Last year, the Texas Legislature increased the maximum penalties for violating weatherization rules to $1,000,000 per day per violation,” it noted.

Sonal Patel is a POWER senior associate editor (@sonalcpatel@POWERmagazine).

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