Thread by @JesseJenkins

IMPORTANT NOTE for journalists and others reporting on this ERCOT generator outage data & #TexasBlackout #TexasFreeze:

ERCOT's reporting method for wind capacity outages overstates the impact of wind outages on reliability by about 4x.

Here's why...

https://twitter.com/JesseJenkins/status/1367879882043252738

The outages reported for wind in this report are based on reductions from the "Seasonal Max MW," which is the maxim rated capacity of the wind farm in the winter. But ERCOT wisely does NOT count on wind farms to produce 100% of their output (the wind is inconstant. Duh).

As the Winter "Seasonal Assessment of Resource Adequacy for the ERCOT Region" report details, ERCOT 'de-rates' wind during winter peak load events to account for its variability. The derate differs for wind in different regions, but the average derate is ~25% of the max capacity.

Here is the full SARA report ercot.com/content/wcm/li…

ERCOT also considers extreme low wind periods in their planning, and the system should be resilient to such events. That counts on as little as 1,791 MW of wind output.

In sum: ERCOT is never planning on 100% of wind farm output to help meet winter peak demands. They count on about 1/4 of the wind capacity on average, and should be reslient to as little as about 6% in extreme cases. So the outage report overstates impact of losing wind by >4x.