Intern Spotlight: An Investigation of Texas’ 2021 Blackouts

The Blackout Zone 

In early February of 2021, the state of Texas experienced a series of severe winter storms, bringing record low temperatures, sleet, and ice. The cold snap caused numerous unplanned outages from February 8th through the 20th, impacting more than 4.5 million people in Texas [3]. The blackouts resulted in extreme shortages of food, water, heat, and at least 250 deaths [4]. 

During the event, there were 4,124 outages/derates that impacted 1,045 generating units with 58% of the outages in gas generating units, 27% in wind generating units, 6% in coal generating units, 2% in solar generating units, <1% in nuclear generating units, and 7% in other generating units. Freezing issues caused by the cold snap caused 44% of these outages, while 31% were due to fuel issues, 21% were caused by mechanical/electrical issues, 2% by transmission system issues, and 2% by other causes [1].

Issues began to occur on February 7th, as unplanned outages at natural gas wellheads occurred and, later that week, wind turbines began to experience issues as their wind blades and nacelles began freezing due to extreme temperatures, precipitation, and natural gas fueling issues. 

Both of these occurrences, coupled with rising loads, significantly strained the Electric Reliability Council of Texas (ERCOT) and Southwest Power Pool (SPP), two individual electric grid operators. By the 14th, derates and unplanned outages rose and ultimately caused ERCOT’s Physical Responsive Capability (PRC) to decrease below acceptable levels. ERCOT began having issues balancing loads with generation needs and experienced averages of 34,000 MW outages. ERCOT operators ordered multiple load sheds, peaking at 20,000 MW on February 15th at 7 pm [1]. 

Key Takeaway: Energy Storage and Grid Resilience 

These occurrences provide a somber reminder of how important operating reserves are in unplanned events, acting as a potentially life-saving buffer of available power that can respond to fluctuations of demand and generation. 

During unplanned environmental events, weather-dependent renewable energy resources can struggle to provide the level of operating reserves necessary for energy generation. The maximum production capacity of renewables may be reduced by environmental conditions, creating shortages during periods of high demand. 

"Increasing preparedness for unplanned events is essential as more renewables are integrated into existing energy grids."

Renewable generation sources generate power intermittently, characterized by periods of high and low production requiring energy storage systems and efficient long-term grid planning. 

Increasing preparedness for unplanned events, such as the Texas winter storms, is especially important as more renewables are integrated into existing energy grids.  Storage batteries and the further innovation of long-lasting and lifetime capacities can also aid grid reliability through lower renewable energy generation times and increased efficiency during unplanned events [2].

1. https://www.nerc.com/pa/rrm/ea/Documents/February_2021_Cold_Weather_Report.pdf
2. https://titanwnc.com/2025/04/top-5-challenges-in-the-solar-industry-and-how-to-overcome-them/
3. https://www.texastribune.org/2021/02/16/texas-wind-turbines-frozen/
4. https://www.texasstandard.org/stories/texas-freeze-winter-storm-2021-death-count/