Houston — The Public Utility Commission of Texas' newest member will hear on April 7 about what caused half the Electric Reliability Council of Texas' generation fleet to go offline during the Feb. 14 winter storm, which cut power to more than 4 million customers.
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ERCOT on April 6 filed at the PUC a "preliminary report on causes of generator outages and derates" for Feb. 14-19 (Project No. 51878). A generation outage occurs when a generator stops working. A derate is when a generator produces less than it normally can, due to issues such as reduced natural gas pressure.
The PUC's meeting April 7 will be a first for Will McAdams, who was appointed April 2 by Texas Governor Greg Abbott to serve as a member. McAdams joins PUC Chairman Arthur D'Andrea, who has resigned pending the appointment of his replacement. An Abbott spokesman on April 6 said D'Andrea will continue to serve with McAdams as a colleague.
McAdams is president of the Associated Builders and Contractors of Texas, having previously worked for more than 10 years for the state, most recently as adviser for business and regulated industries for Dennis Bonnen, who was speaker of the House from 2019 to 2021.
At the peak of the February winter storm, around 8 am CT Feb. 16, in terms of unavailable generation capacity, when 51.2 GW of ERCOT's maximum 107.5 GW was offline, 54% was offline due to weather-related issues, 15% was offline before the event, 14% was offline due to equipment issues (not weather-related), 12% was offline due to fuel limitations, 2% each was offline due to transmission loss and frequency issues, and 1% was offline for other reasons.
The "weather related" category included issues specifically attributed to the cold, such as frozen equipment (frozen sensing lines, frozen water lines, frozen valves, ice accumulation on wind turbine blades, snow-covered solar panels and flooded equipment due to ice or snow melt.
Equipment, fuel issues
Equipment issues included failures not explicitly related to cold weather, such as control system failures or excessive turbine vibrations.
Fuel limitations occurred because of a lack of fuel, low gas pressure, contaminated fuel, fuel supply instability or less efficient alternative fuels (e.g., fuel oil rather than natural gas). Some coal-fired generation owners have mentioned that their supply was wet or frozen and therefore could not be used.
"While it may seem that weatherization of power plants should be the priority, we can infer from the price of gas that available supply was being fully utilized," said Morris Greenberg, senior manager for North American power at S&P Global Platts Analytics. "As a result, had more gas-fired power plants been able to run, the loss due to fuel shortage would have increased. So fuel supply should be a priority as well."
Giuliano Bordignon, a Platts Analytics power market analyst, said, "The 6,124 MW of fuel limitations at the peak of outages/derates are clearly associated to thermal plants rather than renewables, and most likely gas."
Damaged transmission lines can interrupt the ability of generation to supply the grid, and the frozen, icy conditions might well have impeded efforts to repair connections.
When the frequency on the grid deviates too much or too erratically from 60 Hertz, generation can be required to trip offline to prevent substantial damage.