NEW YORK — The Champlain Hudson Power Express is expected to resume transmission on Saturday following repairs to a damaged cable. The 339-mile power line stretching from Quebec to Queens, New York, experienced two separate outages within four days of entering full service.

The project went into full service on July 1, 2024. On that same day, the line experienced an outage caused by a trip at a converter on the Canadian side of the border. Power flow resumed around midday on July 2, 2024, following the initial interruption.

A second outage began on July 4, 2024, this time caused by a damaged section of cable on the US side of the border. The damaged portion of the cable has been removed and replaced. Hydro-Quebec shipped the faulty cable back to the manufacturer for laboratory evaluation.

"A full root cause analysis is underway," said Peter Rose, spokesperson for Hydro-Quebec. Lynn St-Laurent, a spokesperson for Hydro-Québec, provided a timeline for the return to operation.

"It is currently estimated that the remaining work, including necessary post-repair testing, will be completed by the weekend," St-Laurent said. The line is officially the longest underground transmission line in North America. It consists of two high-voltage direct-current power cables, each measuring roughly five inches in diameter.

Much of the Champlain Hudson Power Express was laid at the bottom of the Hudson River. The transmission lines run underground and underwater, buried beneath Lake Champlain and the Hudson, Harlem, and East rivers before connecting to a converter station in Astoria, Queens. Transmission Developers, a company owned by Blackstone, and Hydro-Québec partnered to build the project.

The total cost of the project was $6 billion. The line brings power from hydroelectric plants in Quebec to New York City from May through October under a 25-year contract. Over 99% of Quebec’s electricity comes from renewable sources, primarily hydropower.

The project could provide up to 20% of New York City’s electricity demand. It is New York City’s largest power source, providing enough energy for about 1 million households. Consolidated Edison depends on the line to provide 20% of New York City’s base power needs. On July 3, 2024, New York State’s grid imported 52 gigawatt-hours of electricity from Canada.

The 52 gigawatt-hours imported on that day was enough to meet about 9% of New York State’s total electricity demand. Some of that electricity was transmitted via the Champlain Hudson Power Express. Quebec has experienced intense drought for the past three years, affecting water reserves used for hydropower generation.

Normand Mousseau, a physics professor at Université de Montréal, noted that early operational issues are not uncommon for major infrastructure. "Other power lines have seen similar startup challenges, and the equipment hasn’t really been fully tested until it’s in operation," Mousseau said. Chris Cayten, senior director at CodeGreen, an energy sustainability consulting firm, emphasized the need for reliability.

"There's no point in building a line like that if they can't actually keep it running," Cayten said. Kevin Lanahan, a spokesperson for the New York Independent System Operator, stated that grid planners did not count on the line being active during recent high-demand periods. "Our planning studies did not assume CHPE would be available this summer, and that was one reason the grid performed reliably during the heat wave earlier this month," Lanahan said.

He added that diversity in power sources is essential for stability. "A core principle of reliability planning is not relying on any single project," Lanahan said. Ken Lovett, spokesperson for Governor Kathy Hochul, addressed the state's position on the interruptions.

"Gov. Hochul has been clear that the outages the line experienced this month were unacceptable and needed to be addressed quickly and responsibly," Lovett said. "The Champlain Hudson Power Express will play a pivotal role in New York's clean energy future, but that can only happen if it's operating," Lovett said.