MISO at ‘elevated risk’ of blackouts this summer, warns grid monitor

The Midcontinent Independent Systems Operator (MISO) is at risk of running low on electricity this summer, according to the North American Electric Reliability Corporation (NERC) 2025 summer reliability assessment. This assessment covers the period from June through September and is consistent with the findings of the alarming 2024 assessment covering the next 10 years.

MISO will see an “elevated” risk of shortfalls this summer, with the retirement of 1,575 MW of natural gas and coal-fired generation since last summer contributing to “less dispatchable generation” in the region. NERC pulls no punches in pointing out that MISO’s grid instability is due to “the decline in dispatchable generation and the increasing share that solar and wind resources have in meeting demand.”

MISO’s increasing reliance on intermittent, weather-dependent solar power has shifted the highest energy shortfall risk from July to August. This is because solar generation diminishes earlier in the day during late summer, leaving just intermittent wind power and a “more limited amount of dispatchable resources.”

The details of MISO’s predicament is worrisome, to put it lightly:

The performance of wind and solar generators during periods of high electricity demand is a key factor in determining whether system operators need to employ operating mitigations, such as maximum generation declarations and energy emergencies; MISO has over 31,000 MW of installed wind capacity and 18,245 MW of installed solar capacity; however, the historically based on-peak capacity contribution is 5,616 MW and 9,123 MW, respectively.

Since last summer, over 1,400 MW of thermal generating capacity has been retired in MISO, and the new generation that has been added is predominantly solar (8,080 MW nameplate/4,140 MW on-peak).

Let’s do some napkin math: in peak conditions, wind generates electricity for 18% of its capacity (5,616 MW divided by 31,000 MW) and solar generates electricity 50% of the time (9,123 MW divided by 18,245 MW). When it really counts, wind and solar don’t show up to work.

As wind and solar grow as a proportion of the electricity generation resources that grids use, operators “face challenges in meeting higher demand this summer with a resource mix that, in general, has less flexibility and more variability.” Now, who could have predicted that?

Other grids at an elevated risk this summer include NPCC-New England, Southwest Power Pool (SPP), and ERCOT, the grid that serves Texas. SPP is at risk of blackouts “if above-normal peak demand periods coincide with low wind output and high generator forced outages,” with known challenges including “managing wind energy fluctuations.”

ERCOT’s heavy reliance on solar has created an exacerbated risk of “emergency conditions in the evening hours when solar generation ramps down and loads remain elevated.” No one should need reminding about the 2021 Winter Storm Uri that caused 24 million Texans to suffer through four days of rolling blackouts and killed 246 Texans.

The 10-year outlook suggests that MISO will see a “high” risk of shortfalls in the next 10 years, which may occur during “normal peak conditions” rather than an “elevated” risk where shortfalls may occur in extreme conditions like heat waves.

Instead of rushing to close down reliable, dispatchable coal and natural gas, MISO needs to plan a generation mix that replaces baseload-for-baseload, like nuclear plants, rather than intermittent sources like wind and solar.