MISO says it is contemplating creating a seasonal design for its resource adequacy construct to manage potential reliability risks outside of the summer months.

“Patterns of risk may already be shifting out of peak load periods,” Jessica Harrison, MISO director of research and development, told stakeholders during a Resource Adequacy Subcommittee teleconference Wednesday.

MISO has said its current annual resource adequacy construct and yearly loss-of-load expectation (LOLE) study may not be enough to address the reliability risks it encounters throughout the planning year.

An evolving fleet is nudging MISO’s loss-of-load risk to periods outside of the typical summer peak, the RTO said. It is increasingly encountering resources that have different capabilities depending on the season and a “notable increase in aging baseload units operating sub-annually.”

Harrison said MISO’s reliability risk also “increases noticeably in winter when accounting for seasonal patterns in outages.” She said the RTO’s analyses of 2018 data have found a “moderate” risk of loss of load in all of January and some days in February, in addition to the expected moderate to severe reliability risks in the summer months.

Harrison characterized the analyses as “initial” to determine whether “something other than an annual forced outage rate makes sense” in MISO’s LOLE study.

WPPI Energy’s Steve Leovy pressed MISO to provide a “comprehensive” loss-of-load analysis that proves a clear shift to risks outside of summer.

“The history of maximum generation events isn’t satisfactory. … MISO still hasn’t shown an analysis that shows a resource adequacy risk in non-summer seasons,” Leovy said. “I believe, in MISO’s mind, they’ve already decided there’s a risk. We shouldn’t be at a place yet where MISO proposes seasonal changes. And I’m very afraid that we’re already there, and we’re going to skip over a demonstration.”

Harrison said MISO’s initial studies don’t yet provide a full justification for seasonality.

“However, we are starting to see some indicators,” Harrison said, adding that stakeholders should expect more MISO analyses on seasonality in resource adequacy.

“We’re trying to understand needs before we move into design,” she said, adding that MISO also “has to keep the pace up” in reacting to industry change.

Customized Energy Solutions’ David Sapper urged MISO to conduct its future analyses by giving some consideration to low load levels brought on by an economic depression triggered by COVID-19.

MISO’s second annual Forward Report, released in March, concluded that it must soon break out its annual LOLE study and Planning Resource Auction by season. (See MISO Forward Report Stresses Near-term Change.) The RTO said it could begin making filings to move toward a seasonal resource adequacy construct late this year and in 2021.

Johannes Pfeifenberger, a principal of The Brattle Group, said multiple organized markets have turned to a seasonal resource adequacy construct, with NYISO’s two-season capacity market implemented the earliest in 1999. CAISO enforced monthly resource adequacy requirements for load-serving entities starting in 2004.

He said PJM in 2016 attempted to implement a year-round availability requirement while maintaining a summer reliability benchmark.

“That’s not really working well for some seasonal resources,” Pfeifenberger said of PJM’s treatment. “They’ve left it up to seasonal resources to figure out how they’re going to provide a year-round product.”

Pfeifenberger said even non-market entities like Southern Co. and the Tennessee Valley Authority have “migrated somewhat to winter reserve markets.” He said Alabama Power shifted to winter peaking in 2011 and now uses a 25% winter planning reserve margin compared to a 15% summer planning reserve margin.