Massachusetts utility company signs 4.5 GWh energy storage contract, boosting 2030 energy storage target

Massachusetts Utility Companies Sign 4.5 GWh Energy Storage Contracts

Massachusetts recently achieved significant progress in energy storage deployment. Three utility companies—Eversource Energy, National Grid, and Unitil—have submitted long-term contracts for three large-scale energy storage projects to state regulators, with a total capacity of 1,068 MW/4,472 MWh. These projects are planned to be operational by 2030 and will greatly enhance grid flexibility and clean energy integration capacity in the New England region.

Industry Background

The U.S. energy storage market is in a rapid expansion phase. According to data from the U.S. Energy Information Administration (EIA), national utility-scale energy storage installed capacity exceeded 15 GW in 2025, and Massachusetts is striving to become the energy storage leader on the East Coast. The state set a goal in 2025 to deploy 5 GW of energy storage by 2030, and further proposed in early 2026 to add another 5 GW of non-emitting resources by 2035, totaling 15 GW of clean capacity. The 4.5 GWh projects signed this time are a key step toward achieving this goal.

Energy storage systems play a core role in power grids with increasing penetration of renewable energy. They can provide peak capacity, alleviate transmission congestion, improve power supply reliability, and help integrate intermittent solar and wind energy. Especially in the New England region, as old thermal power units are gradually retired, energy storage becomes an important alternative to fossil fuel peaking plants.

Current Development Updates

The three projects under these contracts are:

• Trimount: Developed by Jupiter Power, located at a former oil terminal site in Everett, north of Boston, with a capacity of 700 MW/2,800 MWh. Of this, 200 MW is allocated to Unitil's Massachusetts subsidiary and 500 MW to National Grid. The project will connect to the grid via the Mystic substation and is expected to become the largest energy storage facility in New England.
• Energizar: Developed by Flatiron Energy, located on a former industrial site in Chelsea, with a capacity of 250 MW/1,000 MWh. The project is expected to be operational in the second quarter of 2027 and will help utilize local renewable energy more efficiently.
• Salt Cod: Also developed by Flatiron Energy, located at the site of the former Montaup power plant in Somerset, which was a coal and oil-fired power plant that closed in 2010. Capacity is 168 MW/672 MWh, planned to be operational by the end of 2028.These three projects all come from the first round of bidding for transmission-level energy storage projects, which sought a total of 1,500 MW of battery capacity. The fourth project—Rhynland Energy's 200 MW River Mill Storage—although it passed the preliminary selection, has not yet signed a long-term contract. The second round of bidding will seek 250-300 MW of distribution network-level energy storage projects, and the third and subsequent rounds will cumulatively procure an additional 3,500 MW before July 2030.

Financial analysis shows that these projects will slightly reduce the average monthly electricity bills for most users over the next 5 to 15 years, reflecting the economic benefits of energy storage for end users.

Impact on the Energy System These large-scale energy storage projects will fundamentally change the operation mode of the power system in the New England region.

• Energy Supply: Energy storage systems can charge during low-price periods and discharge during peak hours, replacing natural gas peaking plants and reducing reliance on fossil fuels. The Boston area, where the Trimount project is located, faces severe transmission bottlenecks, and energy storage can directly alleviate this pressure.
• Grid Stability: Large batteries can provide rapid frequency and voltage regulation, enhancing system resilience. Especially when large amounts of renewable energy are integrated into the grid, the fast response capability of energy storage is crucial for maintaining grid stability.
• Electricity Costs: By peak shaving and valley filling, energy storage can reduce overall electricity costs. Analysis indicates that these projects will have a moderately positive impact on electricity prices over the next 15 years.
• Carbon Emission Reduction: Replacing fossil fuel peaking units will directly reduce carbon emissions, helping Massachusetts achieve its net-zero emissions goal by 2045.

Notably, the site selection for the Salt Cod project is symbolic: building an energy storage project at a retired coal-fired power plant demonstrates the physical path of energy transition. Previously, an Italian company planned to build a submarine cable manufacturing plant there, but it was canceled due to uncertainties in the U.S. offshore wind industry. The energy storage project, however, has proceeded smoothly, reflecting the divergent fates of different clean energy technologies.

Challenges Ahead Despite the bright prospects, the expansion of energy storage in Massachusetts still faces multiple challenges.- Transmission Network Constraints: The grid infrastructure in New England is aging, and upgrades are lagging behind the growth of renewables and energy storage. ISO New England needs to accelerate grid planning to accommodate large-scale storage integration. - Project Financing Pressure: Despite support from long-term contracts, energy storage projects still require substantial initial capital investment. Rising interest rates and supply chain fluctuations may increase financing costs. - Policy Uncertainty: Federal tax incentives for clean energy face risks of changes, which could affect project economics. For example, the U.S. Department of Energy's loan program for storage manufacturing has advanced slowly amid political disagreements. - Raw Material Supply: Price volatility and geopolitical risks for key battery materials such as lithium and cobalt remain concerns. Although Massachusetts projects use lithium-ion battery technology, the development of diversified technology pathways (e.g., zinc-based batteries) still requires time. - Technological Maturity: Long-duration energy storage technologies for more than 4 hours have not yet been commercialized at scale, and Massachusetts' post-2035 goals may rely on longer-duration storage solutions.In the future, energy storage will deeply integrate with electric vehicles, smart grids, and distributed photovoltaics, forming a highly flexible, low-carbon power system. Massachusetts is playing a pioneering role in this transformation, and its experience deserves attention from the global energy industry.