Late last week, the Maine Public Utilities Commission (MPUC) opened an inquiry and issued a request for comment from energy storage developers by June 9 to support a forthcoming procurement for up to 200 MW of transmission-level energy storage projects in Maine. As described below, comments received through this inquiry will shape a forthcoming Request for Proposals.
Relevant Background
Maine has established statutory goals for installed energy storage capacity of 300 MW by 2025 and 400 MW by 2030. According to the Maine Governor's Energy Office (GEO), these targets represent "some of the most ambitious in the country given the relative size of the state's electricity load with 400 megawatts representing nearly 20 percent of Maine's peak demand in 2021." Consistent with those statutory goals, a 2023 Maine law directed the GEO to evaluate and recommend designs for a cost-effective procurement of 200 MW of utility-scale energy storage systems and directed the MPUC to determine whether the program design recommended by GEO will achieve statutory objectives. GEO recently submitted its recommendation to the MPUC, specifically encouraging: a procurement that relies on an upfront incentive and pay for performance mechanism; separate Requests for Proposals (RFP) for transmission-level and distribution-level storage projects; and that the MPUC first conduct an RFP for transmission-level storage projects.
Request for Comment
In furtherance of the GEO's recommendation, the MPUC requests comments on several items for the purposes of developing the RFP for transmission-level energy storage projects. Specifically, a Notice of Inquiry (NOI, available in Docket No. 2025-00148) requests comments addressing the following categories:
- ISO-NE Interconnection-Related Realities – Commenters are asked to explain how current backlog, cluster-study timing, and FERC Order 2023 reforms affect project viability, costs, and timelines for potential storage development.
- Market Externalities and Federal Credits – Commenters are asked to describe how market externalities, including tariffs and federal tax credits, may impact future bids. The GEO recommended that bidders be required to indicate what tax credits they anticipate receiving as part of the bidding process.
- Realistic Commercial Operation Dates – Commenters are asked to predict realistic commercial operation dates given an illustrative procurement award date of January 1, 2026, and to define how that timeline could be impacted by storage technology and project size and location.
- Ratepayer Benefits – The GEO recommendation provides that energy storage will "reduce energy costs for Maine people and businesses, increase the resilience of Maine's electricity grid, and support Maine's clean energy and climate goals." Commenters are asked to provide information on ratepayer benefits (e.g., peak shaving, deferral of transmission upgrades, etc.) and how those benefits should be monetized or incentivized.
- Evaluation Framework for Benefits – Commenters are invited to propose an evaluation method for ratepayer benefits that address (a) geographic value; (b) contribution to grid reliability; (c) performance required by contract during peak hours; (d) avoided transmission/distribution costs; and (e) other benefits that could flow from a transmission-level storage project.
- Prescriptive vs. Open-Ended Incentive Structures – The MPUC invites comments on whether the RFP should be "prescriptive with respect to incentives or whether a bidder should propose their won incentive structure." And if pay-for-performance mechanisms are used, the MPUC asks commenters to describe whether the RFP should require a "third party to call times when the project should be required to perform," or if compliance with pay-for-performance mechanisms should be evaluated in a different way.
- Lessons from Neighboring States – Commenters are invited to comment on other northeastern state storage procurement programs and their potential applicability or suitability to Maine.
- Commercially Available Technologies – The MPUC asks commenters to describe which types of storage technologies should be considered commercially available and whether the RFP should impose a strict technology list (e.g., lithium-ion, iron air, flow batteries, etc.) or remain open-ended. The GEO recommended that bidders should be required to address the commercial availability of their proposed technology and that bidders should be given flexibility to demonstrate readiness based on commercial deployments in other jurisdictions, successful pre-commercial deployments, or reference to certain commercial readiness designations.
The NOI also invites comments on areas for additional study, including: data necessary for decision making; specific ways in which energy storage can address utility needs for resiliency or reliability; and several other topic areas.
Foley Hoag has been deeply involved in the development of energy storage projects throughout New England and New York and will be closely following this process in Maine.
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