MISO Stays Course on Sharpening Generation Retirement Studies

July 24, 2022 / News & Updates

MISO is all but certain to enact changes to its study process for retiring generators, stakeholders learned last week.

The RTO also continues to maintain that the changes will not introduce resource adequacy considerations into its retirement-study process.

Staff said during a Planning Subcommittee meeting July 19 that they will relax confidentiality rules around retirement data, adhere more strictly to local reliability requirements, and require more notice from resource owners in making their retirement decisions.

MISO will now impose a one-year notice requirement on retiring generation before it begins retirement studies under Attachment Y of its tariff; conduct retirement studies in on a quarterly basis; share with stakeholders the megawatt value of retirement requests systemwide; and discourage reliance on load shed as a valid mitigation option when voltage and thermal violations are uncovered in its steady state analyses. (See MISO Bolstering Generation Retirement Studies Amid Capacity Shortage (

MISO has insisted that ensuring local reliability requirements is a last step, not a measure to secure resource adequacy.

The RTO has been firm that the changes will respect state jurisdictions and not extend generators’ operational lives because of resource-adequacy concerns. Its retirement studies currently focus solely on the transmission system’s reliability.

“The Attachment Y process is about local reliability issues associated with a resource retiring,” MISO’s Andy Witmeier said. “Anything related to larger resource-adequacy concerns should be discussed in the Resource Adequacy Subcommittee.”

Witmeier said MISO doesn’t have the authority to keep generation online over resource-adequacy concerns.

Customized Energy Solutions’ David Sapper, representing MISO load-serving entities, said it wasn’t clear how the grid operator would manage simultaneous studies should it encounter a large cluster of retirement requests. Staff said they will still study retirements individually, not in groups.

But Sapper insisted that MISO would still have to make assumptions about other active retirement requests that stand to impact study outcomes. He pointed to downstate Illinois, where several large generators could retire at the same time.

WEC Energy Group’s Chris Plante called for a transition period before the current 26-week notice is doubled. He said some generation owners have planned around the 26-week notice for years.

“I’d rather deal with this in the stakeholder process than at FERC (,” Plante said of MISO’s future filing of the proposal.

Plante said generation owners face an “incredibly complicated” decision over whether to retire. An unexpected system support resource (SSR) designation, applied by MISO if it determines there are reliability concerns with plans to retire a generating unit, can throw a wrench into plans he said. Plante referenced the yearslong clash and complex refunding process that followed SSR status for the Presque Isle coal plant in Michigan’s Upper Peninsula. (See $23 Million Owed to Ratepayers in Presque Isle SSR Case (–23-million-owed-to-ratepayers-in-presque-isle-ssr-case).)

“The last thing my company wants to do is go through another hotly-contested FERC proceeding over who pays for an SSR,” Plante said.

Stakeholders last week also voiced frustration that MISO no longer posts unsolicited comments from stakeholders as part of meeting materials. During the week’s transmission-planning meetings, some stakeholders said the RTO had previously compiled stakeholder comments and shared them publicly on its meeting webpages, even when it had not opened a stakeholder comment period.

Coalition of Midwest Transmission Customers attorney Jim Dauphinais and Clean Grid Alliance’s Natalie McIntire called it a change in policy and a step back for transparency.

“I think this is especially important now because MISO makes fewer formal feedback requests,” McIntire said.

“I do think it’s incredibly important that comments, whether informal or formal, are attached to presentation materials. I just don’t see the value of not posting stakeholder comments,” said Andy Kowalczyk of activist group 350 New Orleans.

MISO staff said they would further address the issue during an upcoming Steering Committee meeting.