Weatherizing Generating Units

Weather Preparedness

MISO readies itself for extreme weather by reflecting on past events and applying best practices in continual preparation for the future.

MISO reports extreme weather events in detail. It also conducts an annual Generator Winterization Survey each September to gather data on preparedness for the upcoming winter.

On a more granular scale, MISO runs a weekly Coal/Fuel Oil and Consumables Data Request to identify any supply issues for generators using coal, oil and petcoke.


Weatherizing Generating Units

MISO urges asset owners to weatherize generating units from extreme weather conditions per the recommendations of the North American Electric Reliability Corporation (NERC).

Severe winter weather can cause icing and other mechanical problems for electricity generating units. Winter weather events in 2011, 2014 and 2021 caused units to trip, de-rate or fail to start entirely due to frigid temperatures and high winds. MISO urges asset owners to ensure that generating units are adequately weatherized. This will help reduce forced generation outages that can jeopardize grid reliability.

FERC/NERC Final Report - February 2021 Cold Weather Event

South Central U.S., FERC, NERC and NERC’s regional entities issued a final report examining the impact the February 2021 freeze had on the bulk electric system. The report found a combination of freezing issues (44.2 percent) and fuel issues (31.4 percent) caused 75.6 percent of the unplanned generating unit outages, derates and failures to start. The report lists 28 specific recommendations including enhanced winterization standards for generator operators

Key takeaways from MISO’s February 2021 Arctic Event Report are consistent with the findings from the FERC/NERC report, including:

·        The need for increased generator winterization requirements

·        The need for gas industry winterization and the importance of coordination across the electric and gas industries

·        The need for good situational awareness leading up to and during events (including enhanced weather, load, and outage forecasting

·        More flexibility and coordination of load shed protocols during winter events, given the recognition that extreme weather events are becoming more frequent and have the potential to take a major toll on public safety

Additional Information

NERC’s other weatherization-related recommendations address subjects such as maintenance and inspection practices; fuel-switching procedures; and winter operations training for unit operators, among other things. Find NERC's presentation on the 2022 winter storm Elliott event on the FERC website


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