As it stares down its footprint’s supply crunch, MISO is proposing to revise its generator retirement studies to include more notice, relaxed confidentiality rules, and stiffer adherence to local reliability requirements.

However, staff was firm during Tuesday’s Planning Subcommittee that the changes will not add resource adequacy considerations to MISO’s existing study process.

The grid operator announced last month that it was considering bulking up the studies under its Attachment Y process that determine whether retiring generation needs to stay online longer under a system support resource agreement. (See Capacity Shortage Prompts MISO to Consider Broadened Retirement Studies.) Presently, the retirement studies focus solely on the transmission system’s reliability, not resource adequacy; MISO does not have the jurisdictional authority to extend generators’ operational lives because of resource adequacy concerns.

The RTO’s Sydney Yeadon said staff seek to “mitigate some challenges” with escalating retirement notices coming from its membership.

She said MISO will impose a one-year notice requirement on retiring generation before MISO begins Attachment Y studies, a six-month extension of current practices.

“More time is needed to conduct more in-depth studies,” Yeadon said. She said the yearlong warning will give staff “greater visibility of the near-term resource mix.”

Anticipating more generation retirements, MISO also proposed to conduct retirement studies in batches on a quarterly basis instead of when the requests are received.

MISO’s Andy Witmeier said a quarterly kickoff of retirement studies will help staff better manage their workload. He said the RTO is never certain of how many retirement or suspension requests it will receive at any given time.

“We need more time in order to do the analysis,” he said.  

The doubled notice time and quarterly cadence will allow MISO to conduct stability studies on a more frequent basis. Yeadon said the extra studies are necessary as the amount of retiring baseload generation picks up.

The grid operator will also begin sharing the systemwide number and megawatt value of retirement requests, Yeadon said. She said MISO “obviously” won’t share the details of individual retirement requests.

Attachment Y notices are currently confidential unless an owner waives recission rights and places a unit directly into retirement, the generator doesn’t return to service when the recission period ends, or MISO evaluates the resource as a possible system support resource.

The RTO also plans to alter the customary mitigation practices used in the retirement study process’ steady state analyses. Staff allows load shed as a mitigation option when voltage and thermal violations are uncovered but going forward, staff wants to lessen wean reliance on load shed.

Stakeholders debated whether MISO’s proposed limits on load-shed mitigation amount a change rooted in resource adequacy concerns.

“We’re just trying to ensure reliability with the practices we have,” Yeadon said.

“That’s going to get litigated, I’m sure,” replied Customized Energy Solutions’ David Sapper, representing MISO load-serving entities.  

Witmeier said it’s not MISO’s purview to dictate when generation retires and that the grid operator is merely focusing on local reliability requirements.

“The enhancements that we’re proposing here are [an] improvement to the process,” he said.

Stakeholders asked whether MISO is considering further changes to its retirement studies to hang onto the capacity it has.  

“I feel like there’s been a lot of stakeholder discussion around this, and I wonder if MISO internally has been discussing some kind of joint forum on it,” Clean Grid Alliance’s Natalie McIntire said.

Witmeier said no such workshop is on the horizon for now. He said the stakeholder-led Resource Adequacy Subcommittee could pursue future discussions on Attachment Y process, but it hasn’t yet.  

MISO considers the issue a planning matter, though stakeholders have called for improving the Attachment Y process, given the topic’s implications to the footprint’s resource adequacy.

“We don’t want to slow down the improvements that we see could be done now,” Witmeier said.

“This is a step in the right direction, but it doesn’t go far enough,” Prairie Power’s Karl Kohlrus said of the study process changes.

Kohlrus said he’s concerned that staff isn’t reflecting all future baseload retirements in their transmission-planning models. He said MISO hasn’t yet accounted for all announced baseload retirements or impacts stemming from Illinois’ Climate and Equitable Jobs Act.

“I’m concerned that there’s no place for MISO to do accurate modeling … It’s kind of scary as a planner that you’re studying a future that won’t exist,” he said.

Staff said they will update planning models with the latest retirements later this year.

MISO Independent Market Monitor’s Michael Chiasson also said the RTO’s retirement and suspension practices have a loophole where a unit can remain on an extended outage for years without being pressured to designate its unit as either suspended or retired. Chiasson said resource owners who don’t want to replace their capacity are essentially allowed to “tie up interconnection” points with nonoperational units.

“I see a couple of examples here and there, not huge amounts … It’s not really widespread at this point,” Chiasson added. But he said as MISO reassesses its current retirement study practices, “it’s a good time” to also address the gap.

Coal Retirements Mounting 

Coal advocate America’s Power said it has tallied announced coal retirements in MISO at 19.3 GW in the 2022-2027 timeframe and 27.3 GW by 2030. The group said if utility announcements pan out, 35% of MISO’s current coal fleet will retire within the next five years, with half of the fleet idled by 2030.

America’s Power said its estimates don’t factor in coal retirements that might be spurred by reinvigorated federal regulations. The group said those regulations could lead to more than 30 GW of MISO’s existing coal capacity installing selective catalytic reduction and/or flue gas desulfurization.

“We are concerned that these facts about future coal retirements might not have received the attention they deserve,” the group said in a late April memo circulated within MISO.

America’s Power also said the coal generation that will retire over the next five years supplied an annual average of 16 percent of MISO’s energy during 2019-2021 with an average capacity factor of slightly more than 50%.