New England Clean Energy Connect - NECEC

The New England Clean Energy Connect (NECEC) is a high-voltage direct current (HVDC) transmission project designed to deliver up to 1,200 megawatts (MW) of renewable hydroelectric power from Québec, Canada, to the New England power grid in Lewiston, Maine. The project is a partnership between Avangrid, a subsidiary of Iberdrola, and Hydro-Québec. The project is expected to be operational by 2025 or early 2026.

Transmission Line and Route

The NECEC transmission line spans approximately 207 miles. The line is rated at 320 kV DC and is designed for a transmission capacity of 1,200 MW. The route includes 54 miles of new HVDC transmission corridor, primarily supported by single-pole, self-weathering steel structures with an average height of 100 feet, within a 150-foot cleared width in a 300-foot right-of-way. The remaining route upgrades about 91 miles of existing transmission lines to accommodate the new power flow.

Converter and Substations

A new converter station, known as the Merrill Road Converter Station, is being constructed in Lewiston, Maine. This facility occupies a 10.71-acre pad and is adjacent to the transmission corridor. The converter station is responsible for converting the incoming 320 kV DC power to 345 kV AC for integration into the New England grid. Additional substation upgrades are being made at Fickett Road in Pownal and at existing substations in Coopers Mills, Larrabee Road, Maine Yankee, Surowiec, and Raven Farm. The project also includes the installation of a second 345/115 kV transformer at Larrabee Road and two 300 MVAR STATCOMs at Buxton to enhance voltage stability and dynamic regulation.

Technical and Environmental Features

The HVDC line uses voltage source converter (VSC) technology, which provides dynamic voltage regulation and improves grid stability. The project’s design minimizes environmental impact by routing about 70% of the line along existing power corridors. The right-of-way is managed to limit vegetation clearing and erosion, with special attention to stormwater management and sediment control, especially in areas with steep slopes or sensitive water crossings. The project is expected to reduce annual carbon emissions by approximately 3.1 million metric tons and supply clean electricity to about 1.2 million homes in New England.

Current Status and Challenges

The New England Clean Energy Connect (NECEC) project has experienced significant legal and regulatory challenges, including a statewide referendum in Maine that sought to halt the project and multiple court cases that temporarily suspended construction. In late 2021 and throughout 2022, construction was paused due to a legal injunction while the Maine Supreme Judicial Court reviewed the constitutionality of the referendum that aimed to block the project.

However, in August 2022, the Maine Supreme Judicial Court ruled that the referendum was unconstitutional because it retroactively targeted a project that had already received its permits and begun construction. This decision allowed construction to resume, and the project moved forward with renewed momentum. Since then, Avangrid and its partners have continued work on the transmission line, converter station, and associated grid upgrades. As of 2025, the project is in the final stages of construction and is on track for commercial operation by the end of 2025.

Grid Integration and Upgrades

The NECEC interconnection is between the Appalaches substation in Québec and the Larrabee Road substation in Maine. The project includes upgrades to the regional grid, such as a new 345 kV AC line between Coopers Mills and Maine Yankee, and various circuit breaker and line rating enhancements to support the increased power flow and maintain system reliability.