Exelon Corporation will retire its 1,700-MW Mystic River 8 and 9 power generating facility when a cost-of-service agreement spanning June 1, 2022, through May 31, 2024, expires.
The announcement comes the same week the Federal Energy Regulatory Commission denied a complaint by Exelon subsidiary Constellation Mystic Power, LLC challenging the ISO New England Inc.'s planning process for replacing the Boston-area natural gas-fired facility. The retirement of Mystic 8 and 9 will not affect plans to retire by May 31, 2021, two oil- and gas-fired peaking units — Mystic Unit 7 and Mystic Jet — at the same facility, Exelon said in an Aug. 21 news release.
"We appreciate FERC's consideration of our complaint that challenged the process ISO-NE is using to replace Mystic's reliability benefits to Boston, and while we disagree with their order, we accept it," Exelon said.
The company said it has not decided to retire the nearby Everett Liquefied Natural Gas Facility and is "hopeful" that the import terminal will continue to operate following Mystic's retirement.
"Everett is strategically located, with interconnections to two interstate pipelines and a natural gas distribution system, and a large LNG trucking operation," Exelon said. "Marketers and utilities in the Northeast have relied on LNG from Everett for decades as an integral peaking fuel to supplement their pipeline supplies."
While they are set to retire in 2024, Mystic 8 and 9 are authorized to recover nearly all of the Everett LNG facility's fixed operating costs under its cost-of-service agreement. According to a FERC order authorizing the arrangement, Mystic 8 and 9 account for approximately 31% of the LNG terminal's capacity. Through the first half of the year, the Everett facility imported 18.4 Bcf of natural gas, according to U.S. Department of Energy data.
Exelon, which acquired the Mystic facility through its merger with Constellation in 2012, had previously expressed hope that Mystic 8 and 9 could continue to operate beyond 2024 under an ISO-NE winter fuel security program.
However, the regional grid operator ultimately decided the facility, which dates back to World War II, should be replaced through a transmission solution submitted jointly by National Grid USA and Eversource Energy. The $49 million plan, dubbed the Ready Path Solution, will see Eversource utility NSTAR Electric Co. install new equipment at its North Cambridge substation while National Grid subsidiary New England Power Co. upgrades three substations in Tewksbury, Amesbury and Haverhill by October 2023.
The New England region will lose a large source of planet-warming greenhouse gas emissions when Mystic 8 and 9 retire. Combined carbon dioxide emissions from the units totaled roughly 3 million tons in 2016 and 2017 before declining to just below 1 million tons in 2019, when Mystic 8 and 9 operated at a 14% capacity factor, according to S&P Global Market Intelligence data.
