Exelon’s Proposed Retirement of its Mystic Plant: Ensuring the Attention of ISO-New England

April 3, 2018

Last Thursday, Exelon Generation (Exelon) announced that it had filed with ISO-New England to retire the Mystic Generating Station’s Units 7, 8, 9, and the Jet unit on June 1, 2022.  Exelon noted “absent any regulatory reforms to properly value reliability and regional fuel security, these units will not participate in the Forward Capacity Auction scheduled for February 2019.”  Mystic offers over 2,000 MW of capacity, making it the largest generating station in Massachusetts and one of the largest in New England.   ISO-New England reported that Exelon submitted delisted bids in the Forward Capacity Auction that was conducted in February.

On March 17th at a New England Restructuring Roundtable Meeting, Gordon Van Weile, President & CEO of ISO-New England, opened the door to such regulatory reforms when discussing the fuel security analysis that the ISO had completed.  His presentation noted that the “The ISO can take action through its market design and tariff to procure ‘insurance’ to alleviate, but not eliminate, fuel-security risk.”  More specific references to possible changes were offered in his formal remarks.  In its Press Release announcing the proposed retirement, Exelon indicated that “ISO-NE recently stated that it may propose interim and long-term market rule changes to address system resiliency in light of significant reliability risks identified in ISO-NE’s January 2018 fuel security report.”

The significance of these retirements is exacerbated by the unique reliability attributes of these units.  First, they are located in the Northeast Massachusetts-Boston area, which has been found to be an import-constrained zone in the past and would likely be determined to be again with the retirement of this capacity.   Second while Mystic 8 and 9 are natural gas-fired, they are not connected to the interstate natural gas transmission pipeline network that serves New England. They are directly connected to the Everett LNG terminal.  Therefore, these two CCGTs are not subject to the same natural gas supply constraints that affect the rest of ISO-New England’s natural gas fleet.  This fact was recognized in ISO-NE’s fuel security analysis.

Interestingly, at this same time Exelon also disclosed that it would be purchasing the LNG terminal from ENGIE North America.  The ISO-New England fuel security analysis demonstrated the importance of the continued operation of the Everett LNG terminal to New England electricity supply reliability.  With a sustainable sendout of about .4 Bcf per day, after the volumes delivered to Mystic 8 and 9 are netted out, the Everett LNG terminal can provide about 9% of New England’s interstate delivery capability (excluding the output of the local LNG and propane storage facilities operated by the region’s gas distribution utilities.)

While one might question why Exelon would purchase the LNG terminal if it planned to retire two generating units that utilize about 30 to 40% of its throughput, with the purchase of the LNG terminal Exelon has purchased a natural gas fuel price hedge.[1] The purchase of the Everett LNG Terminal enables Exelon to secure the world-wide price for LNG for natural gas supplies for Mystic 8 and 9.  This will be beneficial during winter high demand periods, but could result in higher fuel prices in other periods unless Exelon is able to secure contracts with LNG suppliers that are based on an Algonquin City Gate (New England natural gas pricing point) netback price.  Conceivably, Exelon has elected to forgo the modest operating margins in many of these other hours to lock in greater margins during winter peak periods.[2]

Also contributing to the significance of the loss of this capacity is that Mystic 7 is dual-fueled (natural gas and residual oil) with a winter capacity rating of 560 MW.  The importance of dual-fuel capability to maintaining reliability was highlighted this winter, where in a two-week period New England oil-fired generation regularly represented upwards of 35% of the regional fuel mix.

ISO-NE will need to evaluate the reliability impacts of these proposed retirements, but cannot prevent the units from retiring.  This announcement would add to the growing list of retirements, which by the early 2020s would represent (with the addition of this 2,000 MW) about 23% New England’s generation capacity.

[1] The current price of natural gas for Mystic 8 and 9 is reported be pegged to the Algonquin City Gate price so that these units are generally ensured access to natural gas, but at a market price.

[2] Reported prices for LNG deliveries to the Everett Terminal in 2017 ranged from $3.03/MMBtu to $4.00/MMBtu from April to October 2017. US DOE, LNG Monthly, January 2018