February Power Outages: Reviewing the Causes

The rolling outages of February 2 were the result of unusually harsh winter weather, with sustained temperatures well below freezing and, in many areas, high winds and sleet. As a result of the extreme cold, the Electric Reliability Council of Texas (ERCOT) grid experienced unprecedented winter demand for electricity. Below are some key findings already known about these events.

Severe Weather Was the Culprit
The widespread and sustained extreme freezing temperatures of February 2 resulted in the highest winter electricity demand in the history of ERCOT. Extreme cold temperatures lead to extremely high load. Importantly, February 2-4 saw the coldest sustained temperatures in Texas in 20 years. From mechanical failures to pressure drops in natural gas supply lines to inoperable equipment, each reported cause of a generation outage or reduction in output was related to the severe cold. The weather conditions combined to cause problems with control systems used, such as plant transmitters, transducers, or valves that compromised larger power plant operational capability, according to ERCOT President and CEO Trip Doggett. Even with appropriate winterization efforts implemented by generation owners, this cold and wind chill significantly hampered operations.

Many Types of Power Plants Were Affected
Coal, natural gas and wind power plants were among the more than 50 generating units affected by the severe cold weather. As Doggett noted in an interview with the Texas Tribune, “It was multiple owners; it was multiple fuel technologies.” The outages were not limited specifically to coal. It included a number of gas units as well.

Plants Were Affected Throughout the State
During the extreme cold weather from February 2-4, cities all across Texas experienced morning temperatures below freezing, with many having high winds and precipitation. As a result, power plants were affected throughout the state, and the power supply was constrained from North Texas to the Rio Grande Valley all the way to El Paso. Notably, plants affected were operated by both competitive and regulated owners. The regulatory status of any particular owner was not a contributing factor.

Rolling Outage Protocols Successfully Protected the Grid
ERCOT and utilities have rules governing times when the region is faced with an unexpected shortage of electricity. The rolling outage protocols are designed to prevent the entire grid from failing. The protocols attempt to minimize the impact on individual consumers while ensuring the electric grid remains stable, resulting in no further harm. Rolling outages in Texas are rare.

There Are Lessons to Be Learned
ERCOT, the PUC, the Railroad Commission, legislators, the industry and other stakeholders are also beginning to closely examine the outages of February 2. This is an important and valuable exercise for examining what can be done better in the future.

Click here to download a PDF of this issue paper.

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