Texas power plants buckled under cold weather in February storm, report shows

The Electric Reliability Council Of Texas Inc. in a report released April 6 attributed the majority of power plant outages that occurred during February's deadly winter storm to cold weather from the prolonged Arctic blast that paralyzed generators across Texas.

Cold weather caused 54% of the outages or output reductions, totaling 27,472 MW, from Feb. 14-19, concluded the report, issued as lawmakers debate bills that would mandate power plant weatherization.

The report defines weather-related outages as "explicitly attributed to cold weather conditions." Specific causes include frozen equipment, such as sensing lines, water lines and valves; ice accumulation on wind turbine blades; ice or snow cover on solar panels; flooded equipment from melting snow and ice; and an excess of low-temperature limits for wind turbines.

"Because wind and solar output is typically much lower than the specified nameplate capacity," the report notes, the megawatt capacity numbers used to calculate the outages are "generally much higher than the actual amount of power that would have been available in the absence of the outage."

The height of the power outages came on Tuesday, Feb. 16, at 8 a.m. local time, when a staggering 51,173 MW was unavailable, according to the report. That day, prices soared to the $9,000 MWh cap after utility commissioners issued a controversial regulatory order that increased to cost of electricity.

The amount of capacity that went off the grid "increased sharply as the storm arrived on Sunday and stayed fairly constant from late morning on Monday to mid-day on Wednesday," the report said. Generators continued to go in and out of service over the course of the week, making it "difficult to accurately forecast an end to emergency conditions."

Equipment issues not directly attributed to the Arctic blast contributed to 14% of outages, or 6,986 MW.

Fuel limitations caused 12% of the outages, or 6,124 MW. The storm choked the natural gas supply chain and showed that many natural gas plants did not have backup fuel on site.

And deviations from the frequency that is required to maintain the stability of the grid caused 2% of outages, or 1,260 MW. Power plants automatically or manually tripped off the grid in the early morning hours of Feb. 15 to protect against damage as the gridwide frequency dropped below the required 60 Hz.

Transmission loss contributed to another 2% of outages, or 1,259 MW. Miscellaneous issues not linked to the storm caused 1% of the outages, or 585 MW.

ERCOT did not provide granular, power plant-level data. Woody Rickerson, vice president of grid planning and operations for ERCOT, in an April 6 letter to departing PUC Chairman Arthur D'Andrea, said ERCOT continues to compile data needed to complete a final analysis to be released in August. ERCOT will ask power companies to waive confidentiality for specific outage causes in that report, Rickerson wrote.

The PUC will discuss the report in an April 7 meeting as state lawmakers continue to consider a slate of bills meant to reform the power market to prevent another such disaster.

A Houston Chronicle analysis linked nearly 200 deaths to the storm and the blackouts it caused.