By Amanda Durish Cook

CARMEL, Ind. — MISO will delay until next year its proposal to implement a more open-ended approach to its generator retirement process while it looks into possible modeling implications stemming from the change.

MISO adviser Joe Reddoch last week said the RTO will file the plan with FERC in March instead of by the end of the year, giving it time to evaluate whether the more flexible retirement rules will affect its generator availability modeling assumptions used in planning studies.

Reddoch said the new process is “designed to address both temporary and permanent shutdown scenarios,” and asked for stakeholder opinions on the plan through Dec. 5.

Under the proposal, MISO would announce retirements and rescind interconnection rights only after a generator fails to return from a 36-month suspension period or if an asset owner announces a retirement date before the three years are up, Reddoch said during a Nov. 15 Planning Advisory Committee meeting. Owners will also no longer be required to supply the RTO with an estimated return-to-service date when suspending their units. Suspensions lasting fewer than two months and planned generator outages will not be subject to the new process.

Earlier this year, MISO proposed to reduce its Attachment Y process to a catch-all “economic shutdown” status that no longer recognizes temporary suspensions. The RTO has since dropped that term and tripled the amount of time granted for changing a retirement decision, but it still proposes to combine its separate suspension and retirement procedures into a single process. (See “MISO Moves Toward Singular Attachment Y Status,” MISO PAC Briefs: June 14, 2017.)

The RTO last month received two retirement notices under the existing process, representing more than 1,000 MW of capacity. The RTO typically receives a maximum of four retirement and suspension notices per month, and the combined requests rarely exceed 1,000 MW. MISO has already approved the retirement of 735 MW of capacity for the first five months of 2018. Since 2005, MISO has approved 164 retirement notices and issued 10 system support resource agreements.