ISO-NE releases summary of proposals submitted under longer-term transmission planning effort

ISO New England has released summaries of the six proposals received as part of the longer-term transmission planning effort initiated by the New England States Committee on Electricity (NESCOE). At the direction of NESCOE, the ISO issued the request for proposals (RFP) in March, and proposals were due by Sept. 30.

The goal of the RFP is to upgrade the transmission system between northern Maine, where land-based wind generation is expected to increase, and more populous regions of southern New England, where demand for electricity is highest.

Six proposals were submitted in total, by four lead qualified transmission project sponsors. Three proposals focus primarily on alternating current transmission, and three primarily on high-voltage direct current transmission. All proposals claim to meet the targets for increased transfers from Maine to southern New England and support the interconnection to the regional transmission system of 1,200 megawatts of new generation in northern Maine. In line with RFP requirements, all project sponsors will be kept confidential through the selection process. Each proposal provides estimated costs and outlines a strategy for cost containment if expenses exceed estimates.

The proposal submissions are the latest phase of a process that began in 2020 with NESCOE’s New England States’ Vision for a Clean, Affordable, and Reliable 21^st Century Regional Electric Grid, which called on the ISO to incorporate a longer-term transmission planning process in its system planning efforts. The first phase created the longer-term transmission study process, which helped initiate the ISO’s landmark 2050 Transmission Study. This pioneering study outlined transmission needs and potential upgrade roadmaps — and their associated costs — designed to support reliability through the clean energy transition. The RFP seeks to address needs, identified by NESCOE, that relate to findings from this study.

The ISO will assess proposals based on various factors, including cost versus benefit to the region and additional evaluation priorities identified by NESCOE. The ISO will provide updates on the process, as appropriate, through the Planning Advisory Committee, and a preferred solution may be identified by September 2026.