Project Summary

The MPX Project is an HVDC project proposed by Maine Power Express, LLC and Con Edison Transmission, Inc. (together, “MPX”). The MPX Project includes:

  • A 1,040 MW (± 320kV) AC/DC Converter Station in Southern Aroostook County, ME

  • A 103-mile underground HVDC transmission line, buried in an existing energy corridor to Searsport, ME

  • A 200-mile submarine HVDC transmission line, under the ocean to Boston, MA

  • A DC/AC Converter Station at the east end of Massport Conley Terminal

  • A 1.5-mile 345kV AC transmission line buried between the Converter Station and the existing 345kV K Street Substation in Downtown Boston, MA

  • ISO-NE Queue position #506 with I.3.9 approval and Interconnection Agreement negotiations currently underway.

The MPX Project is the optimal route for connecting stranded wind resources in northern Maine directly to the Boston load center with minimal environmental impact. The MPX Project does not require unsightly transmission towers, utilizes an existing energy corridor, avoids the taking and clearing of lands and has no adverse impact to the marine environment.

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The MPX Project provides access to both superior domestic (Maine) Class I RPS wind resources as well as existing Canadian and Maine hydro via an interconnection with a new transmission line. By creating access to these transmission constrained renewables, more resources will be made available to consumers in Massachusetts.

The MPX Project is an advanced development project with high viability to reaching commercial operation. Nearly 100% of the land-based real estate is under control. The MPX Project will utilize a long-existing energy infrastructure corridor that is far narrower than most electric transmission lines require and is therefore unlikely to create opposition to development. Further, the entire length of the line is to be buried either underground or under the ocean floor.

Importantly, MPX also has received ISO-NE I.3.9 approval for its interconnection to the K Street substation in Boston, MA. The County Line Wind project is currently participating in its System Impact Study with ISO-NE for injection at K Street, by-passing the Cluster Study process.

We expect that the MPX Project will demonstrate clear and obvious “green” benefits to Boston and the population of Massachusetts. Some of the potential benefits include:

  • The MPX Project will connect all segments of the Boston and Massachusetts population, including those that would not normally be able to afford renewables, to an actual physical connection to sources of renewable energy.

  • Potential access to supply Massport and the City of Boston with physical connections to clean energy. This could even support consideration of replacing the burning of bunker fuel by passenger ships in Boston harbor through the creation of shore-to-ship power.

  • Fully meets the objectives of the Green Communities Act and Act to Promote Energy Diversity.

The MPX Project provides significant reliability enhancements for Boston and the metropolitan region. It will provide a large source of clean energy at the Boston load center, provide voltage support and black start capability. 

The MPX Project will also provide economic benefits directly to Maine, and Massachusetts through the construction of the HVDC converter station on the rebuilt Massport pier, undersea installation in Boston Harbor, AC interconnect to K Street Station and the K Street substation upgrade. The insertion of additional energy and capacity will provide an indirect economic benefit to customers based on the impact on energy and capacity market prices. The provision of low cost renewables will result in the best outcome on the pocket books of customers and have the least amount of impact on disposable incomes.    

Over the past several years, MPX has conducted preliminary technical, economic, environmental and regulatory feasibility analysis, including local, state and federal communications and support.