Massachusetts Launches Record 1.5-GW Storage Tender to Stabilize Grid Supply

• Massachusetts utilities issue a landmark RFP for 1.5 GW of mid-duration energy storage, the first stage in a 5 GW program designed to bolster renewable integration and grid reliability.

Massachusetts took a decisive step toward fortifying its clean-energy transition this week, as the state’s three investor-owned utilities—Unitil, National Grid and Eversource Energy—jointly released a Request for Proposals (RFP) for up to 1.5 GW of mid-duration energy-storage capacity. The tender is the largest of its kind in New England and marks the opening salvo of a broader mandate to secure 5 GW of storage by the end of the decade.

Issued on 31 July 2025, the RFP targets technologies capable of delivering between four and ten hours of discharge—long enough to ride through the evening peak after solar output fades, yet short enough to remain cost-competitive. Successful bidders can lock in 20- to 30-year contracts for the environmental attributes their projects generate, a structure designed to provide bankable revenue certainty and unlock lower financing costs.

Key milestones come fast: a virtual bidder conference is scheduled for 14 August, with complete proposals due on 10 September. An independent evaluator will review submissions, and contract negotiations are expected to begin in early December. Projects must achieve commercial operation no later than 1 January 2030, aligning with the timeline for the state’s next wave of offshore wind and large-scale solar additions.

The solicitation carries strategic weight beyond its headline numbers. By phasing procurements—1.5 GW this year, 1 GW in both 2026 and 2027, and the balance by 2030—the program aims to cultivate a competitive market, absorb lessons learned and drive down prices with each successive round. Developers may propose stand-alone batteries, pumped hydro, compressed-air systems or hybrid plants paired with renewables, provided they meet the duration and interconnection requirements.

State officials argue that mid-duration storage is essential to replace retiring fossil-fuel generators, meet the Commonwealth’s 2050 net-zero target and shield ratepayers from price spikes. Analysts agree the long-term contracts should spur significant private investment, though they caution that permitting and supply-chain hurdles could still dictate the pace of deployment.

With New York and California pursuing similar initiatives, Massachusetts’ tender will be watched closely across the United States as a bellwether for how quickly storage can scale—and at what cost—in a decarbonizing grid.