Keaton PetersTwo major transmission planning initiatives are underway to take full advantage of renewable energy being generated in Maine. ISO New England, the regional grid operator, has issued a Request for Proposals (RFP) while Maine’s Public Utilities Commission is soliciting information for a complementary program aimed at developing northern Maine’s renewable energy potential and reducing bottlenecks on the electric grid.
ISO New England issued the 2025 Longer-Term Transmission Planning RFP. This competitive solicitation intends to strengthen connections between northern and southern New England while facilitating the integration of additional renewable energy generation from Maine. Simultaneously, the Maine Public Utilities Commission (MPUC) issued its second Request for Information (RFI) for the Northern Maine Renewable Energy Development Program in early April.
These parallel initiatives form the next step in a coordinated regional approach to addressing New England’s aging transmission infrastructure and growing clean energy needs. With states throughout the Northeast pursuing aggressive decarbonization goals, transmission constraints on the grid’s ability to transport all that new power have become a critical bottleneck limiting renewable energy’s effectiveness.
A key challenge for both planning processes involves coordinating between transmission infrastructure and generation development. Without sufficient transmission capacity, renewable generation projects cannot deliver their power to population centers, while transmission projects need assured generation to justify their significant capital investments.
The ISO New England solicitation focuses on two primary objectives identified by the New England States Committee on Electricity: increasing the Maine-New Hampshire interface capacity to at least 3,000 megawatts and expanding the Surowiec-South interface capacity to at least 3,200 megawatts by 2035. Additionally, the RFP requires development of new infrastructure near Pittsfield, Maine capable of accommodating at least 1,200 megawatts (MW) of onshore wind interconnection.
Qualified transmission project sponsors have until Sept. 30 to submit proposals, each requiring a $100,000 study deposit. The competitive process follows a FERC-approved long-term transmission planning process that received federal approval in July 2024. After evaluating the proposals, ISO-NE may select a preferred solution as early as September 2026.
Maine’s complementary effort comes after state legislators amended the Northern Maine Renewable Energy Development Program in 2023, requiring the commission to conduct a procurement for both transmission and generation projects. The amendments specifically mandate development of transmission infrastructure capable of connecting at least 1,200 MW of renewable energy from Northern Maine to the ISO-NE system. The Maine PUC is directed to approve a contract or contracts for selected transmission infrastructure and generation proposals.
“These legislative changes significantly expand the scope and importance of the Northern Maine Procurement,” noted the MPUC in its RFI. The commission’s solicitation seeks stakeholder input on critical questions including the sequencing of Maine’s procurement with ISO-NE’s regional planning process, options for multi-state participation and strategies to simultaneously manage transmission and generation development.
Maine’s inquiry also focuses on potential obstacles to development, including federal permitting timelines, interconnection processes, regional cost allocation and impacts from recent federal executive orders affecting energy development and trade relations.
Potential transmission and renewable energy developers have until June 2 to provide initial comments and submit interest forms to the MPUC, with supplemental comments accepted through Sept. 30.
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