MISO Coal Retirements are a Growing Reliability Threat

The Midcontinent Independent System Operator (MISO) is one of seven regional transmission organizations (RTOs) tasked with overseeing the reliability of the electricity grid.  MISO, to its credit, has pointed out the reliability challenges it faces as the retirement of power plants, in particular coal-fired plants, is occurring faster than replacement electricity resources can be brought online.  Those replacement resources must provide adequate amounts of accredited generating capacity and essential reliability attributes.

However, MISO and other grid operators need to factor in the impact of six Environmental Protection Agency (EPA) rules that will increase coal plant closures, especially between 2026-2030.  For example, EPA’s Ozone Transport Rule is estimated to cause 23 gigawatts (GW) of retirements nationwide by 2025 according to the agency’s own analysis. Additional closures are to be expected because of the Coal Combustion Residuals Rule, Effluent Limitations Guidelines, an Affordable Clean Energy replacement rule, the Regional Haze Rule, and a new mercury rule.  MISO’s assumed 27 GW of retiring coal capacity during 2022-2030 does not include these rules, even though requiring more emission controls could impact more than half of MISO’s coal fleet.

A successful grid transition is dependent on having not just sufficient generating capacity but also all the necessary reliability attributes.  Fortunately, MISO is paving the way by proposing six reliability attributes: fuel assurance, availability, long duration at high output, rapid startup, ramp up capability, and voltage stability.  However, others responsible for maintaining a reliable grid must take meaningful steps, including the following:

  • NERC needs to assess the impacts of a larger number of coal retirements.  We are hopeful NERC will do this in its upcoming Long Term Reliability Assessment.
  • Utility commissioners and grid operators need to pay more attention to coal retirements and EPA regulations.
  • Grid operators need to identify all the attributes that are necessary for reliability and ensure that markets are designed to provide those attributes.  The Federal Energy Regulatory Commission (FERC) should do more to speed up these efforts.
  • Federal agencies should conduct a formal reliability assessment for rules and policies that could adversely impact grid reliability.
  • EPA should pay careful attention to the concerns of FERC, NERC, grid operators, and utilities; defer to states about how to implement regulations; make regulations flexible and not prescriptive; and provide adequate time for retiring coal capacity to be replaced.

Last, everyone involved needs to act with a sense of urgency because reliability warnings are increasing.