Hydro-Quebec is exploring the possibility of restarting a decommissioned nuclear plant to increase its power generation capacity.
In this June 22, 2010, file photo, the Jean-Lesage hydroelectric dam on the Manicouagan River is seen north of Baie-Comeau, Quebec. A transmission line across western Maine will serve as a conduit for Canadian hydropower through Lewiston to the New England grid. Credit: Jacques Boissinot / The Canadian Press via AP

Hydro-Quebec, a partner on the controversial $1 billion hydropower line through western Maine, may restart a nuclear reactor as it eyes future power demands.

News broke earlier this month that the Canadian utility is considering restarting a decommissioned nuclear plant, and that has renewed questions about whether it can meet existing power contracts for the New England Clean Energy Connect project in Maine, a collaboration among it, Massachusetts electric companies and a Central Maine Power affiliate.

Work on the project resumed slowly this summer on both sides of the border as Hydro-Quebec and CMP await a decision by the Massachusetts Legislature on whether to alter current electricity contracts to cover a $500 million cost overrun. Both issues raised questions about potential new hurdles to the project, which already has survived multiple court challenges, including a referendum in Maine that was invalidated.

The utility is in the early stages of studying the feasibility of reactivating the nuclear station as it moves toward a 2050 goal of fully transitioning to a clean energy economy. The assessment is not linked to a particular project or to meeting its current export contracts, Serge Abergel, chief operating officer of Hydro-Quebec, said. Rebuilding such facilities could take 20 years, he said.

“Hydro-Quebec’s ability to supply our export contracts is not in doubt,” he said.

Hydro-Quebec will need new energy supplies by 2027 as electricity demand increases by 20 terawatt hours from 2019 to 2029, according to the utility’s strategic plan. To give an idea of how much that is, the Maine project will take about 9.45 terawatts and the New York project, known as the Champlain Hudson Power Express, about 10.4 terawatts.

The utility’s consideration of nuclear energy surprised Robert McCullough, head of energy consulting firm McCullough Research, because restarting any nuclear plant is very difficult. The plant in question, Gentilly-2, was decommissioned because of economic and other reasons in December 2012, and defueling was completed in September 2013. Restarting it could cost $3 billion or more, he said.

“The nuclear plant option smacks of desperation,” McCullough said.

One option is to buy thermal power from Ontario and New England for Quebec customers, and assign the hydroelectricity to the NECEC and New York that was promised for the clean energy goals of those projects.

The company has surpluses for almost the next decade, Lynn St-Laurent, a spokesperson for the utility, but projected demand in Quebec has jumped for new initiatives, including hydrogen and battery production.

That means it is tightening energy supplies for use in Canada, but it has planned for the NECEC and New York projects in its energy supply outlooks.

The contract that Hydro-Quebec has for the NECEC project with Maine and Massachusetts will deliver hydroelectricity most of the time, but it allows Hydro-Quebec to pull back supplies in critical hours when Quebec has its own shortages, said David Littell, an energy and environmental attorney in Portland and a former member of the Maine Public Utilities Commission.

“That risk has always been there since Massachusetts did the contract,” Littell said.

Lori Valigra, investigative reporter for the environment, holds an M.S. in journalism from Boston University. She was a Knight journalism fellow at M.I.T. and has extensive international reporting experience...