The New England states are planning to solicit project proposals to increase the region’s north-to-south transmission capacity, the New England States Committee on Electricity (NESCOE) wrote in a letter to ISO-NE on Oct. 16.

The solicitations would be conducted through ISO-NE’s recently approved longer-term transmission planning (LTTP) process, which sets a framework and default cost-allocation method for transmission procurements to meet long-term needs. Project costs would be regionalized by load unless the states agree to an alternative cost allocation methodology. (See FERC Approves New Pathway for New England Transmission Projects.)

“NESCOE is interested in focusing the first LTTP solicitation on increasing transfer capability within the system to allow more power to flow from Maine to New Hampshire and into southern New England,” the group wrote.

The need for increased north-to-south transfer capability was one of the key high-likelihood concerns identified in ISO-NE’s 2050 Transmission Study, which projected overloads along the Maine-New Hampshire and North-South interfaces starting in 2035.

While the study showed overloads in both summer and winter, the most significant overloads occurred in the winter amid periods of high output from offshore wind resources interconnecting in Maine and New Hampshire. Connecting offshore wind resources from the Gulf of Maine to the grid in Massachusetts, instead of in northern New England, could help alleviate this stress on the grid. (See ISO-NE Analysis Shows Benefits of Shifting OSW Interconnection Points.)

Although offshore wind will require major transmission investments wherever it interconnects, the first LTTP solicitation appears focused on onshore renewables. NESCOE wrote that one of the key objectives of the solicitation will be to facilitate “the integration and deliverability of additional affordable generation resources located in northern Maine.”

“Recent studies, along with the current interconnection queue, indicate that on the order of 3,000 MW of additional generation capacity could potentially be developed in northern Maine. NESCOE is interested in solutions that would facilitate the integration of these resources,” the group added.

Renewable power advocates in New England have long sought to unlock the potential of renewables — onshore wind in particular — in northern Maine, but this part of the region is not directly connected to the ISO-NE grid.

In 2022, Maine selected a proposal from LS Power for a 345 kV line to connect the area to the region’s grid, but the Maine Public Utilities Commission canceled the procurement after the projects’ projected costs increased. The PUC plans separate solicitations for transmission and generation in the area, and a proposal from Avangrid recently received financial backing from the federal government. (See Long Road Still Ahead for Aroostook Transmission Project.)

Alex Lawton of Advanced Energy United expressed his excitement about NESCOE’s announcement and said it is “amazing to see our region being proactive and leading the way on transmission planning.”

He added that northern Maine has “some of the cheapest, most abundant renewable potential” in New England, and unlocking more north-south transmission capacity is “one of the more low-hanging fruit and promising areas for cost-effective transmission in New England.”

Next Steps

NESCOE said it is seeking stakeholder feedback on how best to achieve its goals of increasing north-south transmission capacity and integrating renewables in northern Maine, as well as “any other feedback that may increase the likelihood of a successful solicitation.”

The organization said it is considering a requirement for proposed solutions to “increase the Maine-New Hampshire interface capacity to at least 3,000 MW by 2035 and increase the Surowiec-South interface capacity to at least 3,200 MW by 2035.”

The capacity of the Maine-New Hampshire interface is 2,000 MW, while the more northern Surowiec-South interface has a transfer limit of 1,800 MW.

NESCOE wrote it also is “weighing the tradeoffs of including a requirement for solutions that extend farther north into Maine.”

“While such a requirement would further facilitate the transfer of cost-effective power across these interfaces, NESCOE seeks to avoid an overly prescriptive scope that may hinder the success of a potential [request for proposals] by unduly limiting the pool of bids or by reducing the likelihood of soliciting a cost-effective solution,” the group wrote.

NESCOE will discuss the preliminary scope of the solicitation with stakeholders at the ISO-NE Planning Advisory Committee meeting on Oct. 23, which will be open to the public.