Massachusetts Utilities Sign Deals for 4.5 GWh of Battery Storage
Three Massachusetts utilities have locked in long-term contracts for a combined 1,068 MW and 4,472 MWh of battery storage capacity, Utility Dive reports, marking one of the largest storage buildouts in New England to date.
Market Impact
Eversource Energy, National Grid and Unitil filed the agreements with developers Jupiter Power and Flatiron Energy last week, according to the utilities and the Massachusetts Department of Energy Resources. The projects are slated to come online by 2030 and are expected to deliver clean peaking capacity while easing transmission congestion in Greater Boston and southeastern Massachusetts.
Jupiter Power’s Trimount project is the largest of the three, a 700 MW/2,800 MWh installation planned for 20 acres at a former oil terminal in Everett, connecting to the nearby Mystic substation. National Grid’s Massachusetts subsidiaries have contracted for 500 MW of that capacity, with Unitil’s Fitchburg Gas & Electric Light subsidiary taking the remaining 200 MW.
Flatiron Energy’s two projects round out the group: the 250 MW/1,000 MWh Energizar in Chelsea, targeting a second-quarter 2027 start, and the 168 MW/672 MWh Salt Cod, planned for an 11-acre section of the shuttered Montaup Power Plant site in Somerset, with operations expected by late 2028. Montaup, a coal- and oil-fired plant, closed in 2010. A fourth project from the same solicitation, Rhynland Energy’s 200 MW River Mill Storage, has not yet secured a utility contract.
Financial filings with the Massachusetts Department of Public Utilities indicate the deals will modestly lower most customers’ bills over the next five to 15 years. The contracts stem from the first round of a state solicitation targeting up to 1,500 MW of transmission-connected storage, part of Massachusetts’ broader push to deploy 5 GW of storage by 2030 and, per Gov. Maura Healey’s plans announced earlier this year, another 5 GW by 2035.
What It Means for Subcontractors
- Civil and site-prep crews should watch for bid packages tied to Jupiter Power’s 20-acre Everett site and Flatiron’s 11-acre Somerset site, both former fossil fuel properties requiring remediation and substation interconnection work before 2027-2028 in-service dates.
- Electrical and E&I contractors can target the Mystic substation interconnection for Trimount, given the 700 MW project’s scale and National Grid/Unitil’s combined 700 MW capacity commitment.
- Mechanical and battery-integration subs should track Flatiron’s Chelsea and Somerset builds, with Energizar targeting Q2 2027 startup and Salt Cod targeting late 2028, both timelines that set procurement windows over the next 12 to 18 months.
- Firms in other states can use this RFP structure, a transmission-connected first round followed by a 250-300 MW distribution-connected second solicitation, as a model for anticipating similar utility storage procurements as MDER seeks 3,500 MW more by July 2030.
