Dive Brief:
- The resource outlook for the Midcontinent Independent System Operator continues to improve, with excess power supplies expected over the next five years, according to a survey discussed at a workshop the grid operator held Thursday.
- MISO members are expected to add 15 GW a year, on average, in accredited summer capacity over the next five years, up from expectations for up to 8.6 GW in annual additions a year ago, according to the latest Organization of MISO States-MISO annual survey. The additions include 4 GW annually in fast-track Expedited Resource Addition Study projects.
- The survey shows utilities are working to “help meet rapidly growing demand,” Michael Carrigan, OMS president and Illinois Commerce Commission commissioner, said at the meeting. He added, however, that “the results reinforce that maintaining reliability is becoming more complex as load growth accelerates, the resource mix evolves and reliability risks increasingly shift towards winter conditions.”
Dive Insight:
The latest OMS-MISO survey marks a turnaround from two years ago, when the survey indicated that MISO faced possible shortfalls starting in 2025. The deficits were projected to grow over the following four years.
Now, it forecasts growing power supply margins, even with loads forecast to grow by 5.1% a year.
The survey indicates that MISO will have excess supplies above its planning reserve margin for the planning year that starts in June 2027 ranging from 4.6 MW to 12.7 MW, depending on the season.
Those surpluses could continue growing. Based on load forecasts from November, the survey indicates MISO’s excess capacity above forecast planning reserve margin requirements — which includes a buffer above expected peak loads — will grow from 11.5 GW in summer 2028 to 39 GW in the summer three years later. However, when considering load forecasts from April, those margins are significantly less, according to the presentation.
In the near term, solar and battery storage make up most of the capacity additions. By 2032, the roughly 100 GW of new supplies will be about 60% wind, solar and batteries and 40% gas-fired generation, according to the presentation.
MISO cautioned that there is uncertainty about the viability of the 87 GW of resources with signed generator interconnection agreements that haven’t been built. The grid operator said it is studying interconnection requests for another 192 GW.
So far this year, 3 GW of nameplate capacity has come online compared with 10.6 GW in all of last year, 7.6 GW in 2024 and 5.6 GW in 2023, according to MISO’s Generator Interconnection Queue Commercial Operation Dates Dashboard. Solar generation accounts for nearly 60% of the total 26.8 GW of capacity over that period.
MISO noted that it is switching to a “direct loss of load” resource accreditation methodology, which it said will value a resource’s contribution to reliability during the highest-risk periods. The change will come into effect for MISO’s 2028/29 planning year.
MISO runs the grid and wholesale power markets in 15 states and the Canadian province of Manitoba.
The OMS-MISO survey has become an increasingly important tool for states, utilities, MISO and stakeholders in understanding changing resource adequacy conditions across the grid operator’s footprint, Carrigan said.
The survey received a 99.5% participation rate, a record, he noted.
