Utility-scale battery storage developer Jupiter Power’s 700MW/2,800MWh Trimount battery energy storage system (BESS) in Everett, Massachusetts, US, has been approved by state officials.
The Massachusetts Energy Facilities Siting Board (EFSB) issued its final decision on 27 February. Jupiter is developing the project under the name Trimount ESS LLC.
Trimount is part of a broader redevelopment effort at the former ExxonMobil location in Everett, Middlesex County, Massachusetts.
In January 2024, real estate firm Davis Companies acquired the 100-acre site from ExxonMobil after a lawsuit and settlement with the Conservation Law Foundation (CLF).
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ExxonMobil had to shut down the Everett oil depot due to the agreement, which prohibited the site’s use for storing petroleum products.
After purchasing the site, Davis Companies entered into an agreement with the Massachusetts Attorney General’s Office to handle environmental cleanup and redevelopment of the former tank farm.
Announced on 30 May 2024, this agreement grants liability protection to Davis Companies in return for its commitment to redevelop the contaminated brownfield site. The agreement describes the site as “heavily contaminated with oil” and “industrial chemicals formerly used in the site operations.”
In addition to the Trimount BESS project, Jupiter will construct two substations and underground transmission lines. The BESS equipment will be constructed in a double-stacked arrangement.
Trimount will connect to the local electricity grid through Eversource Energy’s Mystic Substation, a highly prioritised interconnection point listed in ISO New England’s public queue. There are six separate interconnection requests for battery storage projects at the Mystic Substation, totalling over 1.6GW of capacity.
Jupiter also claims it is collaborating with Everett to develop Trimount in a way that aligns with the goal of revitalising the part of the city where it will be located. Everett has historically been a site of negative impacts from fossil fuels.
Jupiter Power proposes replacing this infrastructure with cleaner, sustainable energy solutions, offering benefits such as a more than US$1 billion investment in Everett, increasing annual tax revenues to the city and public schools, creating hundreds of jobs, reducing air pollution, and supporting Massachusetts’ goal of 50% CO2 reduction by 2030 and carbon neutrality by 2050.
Trimount is phase 1 of real estate developer Everett LandCo’s Everett Docklands Innovation District (EDID) Project. Everett Landco is a joint venture (JV) between the Davis Companies and energy infrastructure company Global Partners LP.
According to the EFSB’s decision, Trimount will use China-headquartered BESS manufacturer Hithium’s 5.015MWh BESS units. The units utilise lithium iron phosphate (LFP) battery cells and Jupiter said it used them in a previous Massachusetts project.
The project facility will also feature medium voltage power stations and inverters connected to the BESS. Each power station would be roughly the same size as the BESS enclosures. These power stations would be located on either side of the groups of four BESS units.
While Jupiter did propose several options for fire safety, it also noted that these options are subject to change.
Earlier this year, Jupiter closed US$500 million senior secured green revolving loan and letter of credit facility to support the advancement of its project pipeline across the US, building on a November 2024 US$225 million corporate credit facility.
At the time, Jesse Campbell, Jupiter Power’s Chief Financial Officer, noted: “This additional liquidity launches us into our post-‘One Big Beautiful Bill Act’ (OBBBA) growth phase, supporting not just the major new domestic BESS procurement recently closed but also numerous projects proceeding into construction and major advancement of our development pipeline.”
The company recently entered into a multi-year deal with Sodium-ion (Na-ion) BESS startup Peak Energy. Under this agreement, Peak will supply up to 4.75GWh of Na-ion BESS to Jupiter Power for deployment between 2027 and 2030.
Jupiter Power reports having around 8,000MWh of BESS projects that are either operational, under construction, or under contract, with a development pipeline exceeding 12GW nationwide.
The EFSB is currently holding evidentiary hearings meetings for developer Rhynland Energy’s 180MW Moraga Storage BESS project, which would be located in Oakham.
In summer 2025, Rhynland submitted an application to Massachusetts’ energy regulator for BESS approval. The Town’s authorities have previously amended zoning laws to ban standalone BESS, so Rhynland is now requesting a zoning exemption for the project from the State Department of Public Utilities.
The Energy Storage Summit USA will be held from 24-25 March 2026, in Dallas, TX. It features keynote speeches and panel discussions on topics like FEOC challenges, power demand forecasting, and managing the BESS supply chain. ESN Premium subscribers can get an exclusive discount on ticket prices. For complete information, visit the Energy Storage Summit USA website.
