ISO New England issued its first competitive solicitation for new transmission resources in the region.
The grid operator issued a request for proposals, or RFP, Dec. 20 to address reliability concerns in the Boston area that are expected to occur after Exelon Corp.'s 1,700-MW Mystic River 8 and 9 units retire in 2024. The issuance of the RFP had been expected in late 2019 or early 2020.
The RFP will be conducted in two stages. In the first phase, qualified transmission project sponsors will have until March 4, 2020, to submit their proposals. Within about six months, the independent system operator will determine which proposals have passed phase one and ask project sponsors to submit a more detailed phase two proposal. The timeline as outlined in the RFP indicates it would be more than a year later when a preliminary phase two solution is identified.
Two incumbent transmission providers in the Greater Boston area, Eversource Energy through its NSTAR Electric Co. unit and National Grid USA through its New England Power Co. unit, will have to jointly submit a phase one backstop transmission proposal, according to the RFP announcement.
Much of the ISO's analyses, such as needs assessments, are considered critical energy infrastructure information, and access to them is restricted. A publicly available addendum, issued in October, to the ISO's Boston 2028 Needs Assessment explains that in an outage disrupting service in the Boston area, the Mystic 8 and 9 units are among the first to be brought online to re-energize the broader grid.
"The Mystic 8 and 9 generators play a key role helping to regulate system voltages by utilizing the dynamic reactive capability of the generators during the energization of transmission facilities," the addendum says.
Along with the transmission solution, ISO New England is looking for a dynamic reactive device, directly interconnected into one of five locations, to help with system restoration after the Mystic units are retired.
The two gas-fired Mystic units are relatively new, in operation only since 2003, but they are not economical to operate. They are being kept in operation for fuel security purposes under a cost-of-service agreement approved in December 2018 by the Federal Energy Regulatory Commission. Exelon, which supplies the Mystic units with gas from the adjacent Everett liquefied natural gas import facility, which it also owns, had previously said it would shut the plant in mid-2022.