ISO New England Picks a .2 Billion CMP and Eversource Line to Carry 1,200 MW of Aroostook Wind South
- Capacity & Wholesale Markets News Policy & Markets
Marin Holt
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- 8 minutes read
- Project Cost: $2.2 billion
- Wind Interconnection Enabled: 1,200 MW
- Line Rebuilt: 170 miles across four segments
- Competing Bids: six, from $960 million to over $4 billion
- Target In-Service: late 2032
ISO New England named a $2.2 billion Central Maine Power and Eversource proposal its preliminary preferred solution on July 31, 2026. It is the first pick in the region’s Longer-Term Transmission Planning process. The project would rebuild about 170 miles of existing line across four segments in Maine, running from southern New Hampshire to Pittsfield. It opens the north of the state to at least 1,200 MW of new onshore wind in Aroostook County. Service could start in late 2032.
The grid operator chose the CMP and Eversource bid from six proposals. The field ran from $960 million to more than $4 billion. The winner therefore sits near the middle on price, not at the bottom. CMP is an Avangrid subsidiary. Eversource serves load in the southern New England states where the power lands.
The solicitation traces back to the New England States Committee on Electricity and its 2050 Transmission Study. NESCOE directed ISO New England to issue the request for proposals, which went out on April 1, 2025. That makes this a state-driven procurement, not a reliability fix the operator ordered on its own. Six states agreed on the need first. Then they asked the ISO to run the competition.
The design leans on corridors that already exist. Crews would rebuild lines in place instead of buying new land or cutting wide new paths through Maine timberland. That choice matters in a state that killed the New England Clean Energy Connect corridor at referendum in 2021 and then fought over it in court for years.
“This isn’t one project that is an answer to one specific need,” CMP spokesperson Jon Breed said. “This is all six states looking at the regional grid and determining what is the best way forward.”
Why It Matters
Customers across six states pay for this line. They start paying well before a turbine spins in Aroostook County. The 1,200 MW figure is interconnection headroom, not signed generation. New England has built transmission ahead of supply before, and it has also watched that supply fail to arrive.
The 30-day NESCOE window is the decision point to watch. It is the last clean moment for a state to object to who pays what, before the ISO starts writing contracts. Load-serving entities in Connecticut, Massachusetts and Rhode Island should model their share now. Waiting for the final report costs them the objection.
What Happens Next
ISO New England published a draft evaluation report with its technical analysis and cost-benefit case. A public comment period follows, then a final report. NESCOE then gets 30 days to terminate the solicitation or to demand a different cost allocation. If the states do neither, the ISO signs agreements with the sponsors and starts the added technical studies.
The project still needs permits and a case before the Maine Public Utilities Commission. “There’s still a lot of permitting that needs to happen,” said Eliza Donoghue, executive director of the Maine Renewable Energy Association. “We are still very much in the early stages.”
Critical Perspective
The $2.2 billion bid sits in the middle of a field that started at $960 million. That is a gap of more than $1.2 billion between the winner and the cheapest offer, on a bill that six states’ customers pay. ISO New England has published a draft evaluation report, and the burden it carries is to explain what the extra $1.2 billion buys. Cost-benefit scoring can justify a pricier build. It has to show the work, because the comment period is the only window in which anyone can contest that arithmetic.
The 1,200 MW of Aroostook County wind is also headroom, not signed generation. No developer has committed to fill it. Maine has been here before: voters killed the New England Clean Energy Connect corridor at referendum in 2021, and the litigation ran for years after. Rebuilding existing corridors instead of cutting new ones is a direct answer to that history, and it is the smartest part of this proposal. It does not remove the Maine Public Utilities Commission case or the permits still ahead.
Then there is the clock. A late 2032 in-service date is more than six years out for a project whose sponsors have not yet signed agreements with the ISO. Eliza Donoghue of the Maine Renewable Energy Association put it plainly: the process is still in its early stages. So the question for NESCOE in its 30-day window is not whether the region needs the line. It is what customers hold if the wind never arrives and 1,200 MW of paid-for headroom sits empty in 2033.
