Workers watch the installation of the first pole of Central Maine Power’s hydropower transmission corridor near The Forks in February. Associated Press/Robert F. Bukaty

A heated dispute between Central Maine Power’s parent company and rival energy giant NextEra is threatening to delay the completion of CMP’s controversial 145-mile transmission corridor.

CMP’s parent – Avangrid, which is itself the subsidiary of Spanish energy giant Iberdrola – has been locked in a bitter disagreement with Florida-based NextEra Energy, which it accuses of intentionally obstructing the transmission project by failing to perform a necessary safety upgrade of a piece of equipment at the nuclear power plant in Seabrook, New Hampshire. Until NextEra upgrades this circuit breaker in Seabrook, CMP can’t connect its $1 billion New England Clean Energy Connect line and the 1,200 megawatts of Quebec hydropower it would carry to New England’s primary electricity grid.

“NextEra’s actions and inactions reflect NextEra’s intentional efforts to interfere with the interconnection of the NECEC Project,” Avangrid said in a complaint filed with federal authorities Oct. 13, in which it says continued delays might jeopardize the project’s May 31, 2023, go-live date.

“NextEra has taken every opportunity, both in the open and behind the scenes, to oppose, delay and derail the NECEC Project, all to benefit its existing fossil and nuclear generation located in Maine and New Hampshire and its renewable projects in Maine,” the filing before the Federal Energy Regulatory Commission states. “In doing so, NextEra is purposely trying to thwart the goals of Maine and Massachusetts to obtain more renewable power, which will have a negative impact to the climate and to the people of the region.”

NextEra, which owns the 822-megawatt W.F. Wyman oil-fired power station on Cousin’s Island in Yarmouth, has dismissed Avangrid’s complaints as a baseless effort to “cast aspersions and false allegations against Seabrook and its affiliates in an effort to color the outcome of the contractual dispute.”

David Littell, an energy attorney who formerly served as a Maine public utilities commissioner and head of the state Department of Environmental Protection, said these kinds of bare-knuckled disputes between big energy companies are common as they seek advantages over one another, but that they usually occur outside the public eye.

“These are two behemoths in this area and such companies know a lot of sophisticated moves and procedures in the regulatory and technical realms which they can use as a layered defense or offense against one another, or to swat smaller players away or put them out of business,” Littell said. “But typically these things happen quietly and one side loses and limps away to fight another day.”

The dispute has been anything but quiet, and the stakes are high for both companies.

The NECEC project aims to bridge a transmission gap separating Hydro-Quebec’s massive hydroelectric plants in northern Quebec from millions of consumers in Massachusetts and other parts of New England and would be funded by Massachusetts ratepayers. It cuts through 53 miles of forest in western Maine – a major bone of contention with conservationists – before following existing transmission corridors to a new substation in Lewiston.

Press Herald graphic by Michael Fisher

The project – which is supported by Gov. Janet Mills and opposed by Maine and Quebec tribes – has received its state and federal permits but is already facing one existential challenge in the form of a referendum question that will appear on this November’s ballot. It asks voters if they wish to ban the upper section of the project and require legislative approval for future ones.

Even if voters reject the ballot initiative and the transmission line is completed, operations can’t begin until the Seabrook nuclear power plant’s backup generator circuit breaker is upgraded to ensure it works properly with higher electricity loads on the surrounding grid. And the owner of that circuit breaker is Avangrid’s bitter rival, NextEra, which has repeatedly tried to stop the project in various venues: the Massachusetts Department of Public Utilities; the Maine Public Utilities Commission; the Maine Supreme Judicial Court; the Maine Department of Environmental Protection, Board of Environmental Protection and Land Use Planning Commission; and the U.S. Army Corps of Engineers; and also by providing nearly $7 million to a political action committee opposing the project, Mainers For Local Power.

Avangrid argues in its FERC complaint that NextEra is now trying to trip up its transmission project by delaying the circuit breaker upgrade. “NextEra is a direct competitor to the NECEC Project and stands to lose significant revenues and profits as a result of the successful development of the NECEC Project,” the company claimed.

Avangrid also claimed in it filings that NextEra executives approached it and offered to make the switch upgrade problem go away if Avangrid agreed to grant NextEra an advantageous power purchasing deal.

“Of all the things they’ve done, this is the worst and most vindictive and petty of them,” Thorn Dickinson, president and CEO of the Avangrid subsidiary that will own and operate the project, NECEC Transmission LLC, said in an interview. “We’re at the point now where we need action from them to get this thing replaced by the spring of 2023,” when the project is supposed to start delivering electricity.

In a separate action filed in May, Avangrid tried to make a case before the Nuclear Regulatory Commission that the continued operation of the existing switch at Seabrook represents a public safety issue. NextEra has vigorously refuted this and many of Avangrid’s other assertions.

“The dispute between ourselves and Avangrid is a commercial dispute: We need to be fairly compensated for the work that needs to be done at Seabrook,” NextEra spokesman Steven Stengel told the Press Herald. “If we’re fairly compensated, we’re more than happy to perform the work.”

While Avangrid has agreed to pay for the upgrade itself, NextEra’s position is that Avangrid should also compensate NextEra for any revenues lost while the Seabrook station is offline to allow the work to happen. In filings it estimated these costs at about $560,000 a day.

But Avangrid doesn’t trust its rival not to slow walk the work, especially if there is no net financial cost for it to do so. “Their solution is: ‘Hey, we don’t know how long it will take, and we want you to pay for any time that takes longer,’” Dickinson said. “And if you have a 40-day window, why not damage us by making it take 60 or 70 days? The cost could be in the tens of millions.”

Avangrid argues the work could be done in a couple of weeks and take place when Seabrook is shut down for routine refueling. The company had wanted it to happen during this October’s scheduled shutdown, but now it says it’s concerned NextEra’s delays will jeopardize having the work take place during the next refueling shutdown after that, in May 2023.

Avangrid has asked the FERC to take action to compel NextEra to replace the switch then, and Dickinson said the agency would have to take action by the end of the year to ensure the replacement takes place before NECEC is supposed to start operating.

NextEra, for its part, has asked the FERC to instead step in to help reconcile their dispute over who pays for what. “We want them to help us solve this dispute,” Stengel said.

It’s unclear when FERC might act on either initiative.

Neither Mills’ office nor the director of her energy office, Dan Burgess, responded to interview requests for this story.