ISO-NE selects preliminary preferred solution for longer-term transmission effort

After several months of evaluation, ISO New England has selected the preliminary preferred longer-term transmission solution for the 2025 request for proposals (RFP) to address needs that the New England States Committee on Electricity (NESCOE) identified in connection with the 2050 Transmission Study.

The ISO issued the RFP at NESCOE’s direction. The preliminary preferred solution, submitted by Central Maine Power (CMP) and Eversource, would 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.

The ISO assessed proposals based on various factors, including meeting the requirements of the RFP, technical feasibility, the cost and benefit to the region, and additional evaluation priorities identified by NESCOE. The request and evaluation process are in accordance with Phase 2 of the longer-term transmission planning (LTTP) process.

The ISO’s draft report details the results of all technical analyses, cost-benefit calculations, and the basis for the selection of the preliminary preferred solution. After a comment period, the ISO will confirm the preferred (i.e., no longer preliminary) solution with the publication of a final report. Within 30 days of the final report being posted, NESCOE may choose to:

1) terminate the 2025 LTTP RFP process, or

2) proceed with an alternative cost allocation for the project.

If the ISO does not receive a written communication with either of the above points within 30 days of the final report’s publication, the ISO will proceed with the next steps. These next steps include signing agreements with the project sponsors and further rigorous technical analysis by the ISO that is required of any new project connecting to the system.

The ISO will provide updates on the process, as appropriate, through the Planning Advisory Committee.