ERCOT's new Monthly Outlook for Resource Adequacy shows risk in December

The Electric Reliability Council of Texas on Oct. 2 released a new Monthly Outlook for Resource Adequacy report for December, which shows some risk of a supply shortfall.

December 2023 has the following highest chances of issuing an Energy Emergency Alert, both for the hour ending at 8 am CT:

• With expected weather, ERCOT has a 5.4% chance of issuing an EEA and a 4.3% chance of having to order rotating outages.
• With weather similar to the late December 2022 winter storm, ERCOT has a 17.9% chance of ordering an EEA and a 14.4% chance of having to order rotating outages.

"Under typical grid conditions, the deterministic scenario indicates that there should be sufficient generating capacity available to serve the expected peakload at hour ending at 8 am," the report states.

The National Weather Service's forecast for November, December and January indicates even chances of near-normal temperatures across Texas.

Expressed as a percentage of peakload, December's reserve margin would by 30.7% for the peak hour. The PUC has historically targeted 13.75% as ERCOT's reserve margin to ensure a capacity-related supply shortfall occurs no more than one day in 10 years, but the PUC is working with ERCOT to update that metric.

For the peak hour ending at 8 am in December, ERCOT expects to have 92.4 GW of capacity available for reserves, including 75.5 GW of thermal, 14.3 GW of intermittent renewables, 1.1 GW of energy storage and 539 MW of hydro and biomass generation.

ERCOT set an all-time peakload record of 85.4 GW on August 10. ERCOT's December record is 73.9 GW set Dec. 23, 2022.

Releases two months in advance

ERCOT plans to release each MORA on the first day of the month for the operating month two month later, or on the first weekday after the first day if that occurs on the weekend. The MORA replaces the four-times-a-year Seasonal Assessment of Resource Adequacy, of which the last, for October and November, was released Sept. 19.

"Our goal is to manage a reliable grid under all situations," said Kristi Hobbs, ERCOT vice president for system planning and weatherization. "The MORA report provides a more frequent advance look at resource adequacy with a focus on the likelihood of capacity shortage events for each month."

ERCOT said updates may be issued after the initial release and recommended checking its resource adequacy web page after mid-month for any revisions.

The Public Utility Commission of Texas directed ERCOT to provide more frequent resource adequacy assessments in the wake of the deadly mid-February 2021 winter storm that left about 4 million customers in ERCOT in the dark, some for days.

ERCOT said the new report contains the following information:

• Capacity Available for Operating Reserves, a probabilistic asse3ssment of hourly risks of how much capacity would be available during extreme circumstances
• Two "typical grid conditions" scenarios: one for peak demand hour (hour ending at 8 am) and minimum demand hour (hour ending at 5 pm)
• A new measure for tracking how much ERCOT relies upon dispatchable resources for expected monthly peakload.

The highest risk hour is just before solar production ramp-up.