On July 3, as a heat wave swept the region, New York State's grid imported 52 gigawatt-hours of electricity from Canada — enough to meet about 9% of its total demand that day[reference:64]. Some of that power traveled on the Champlain Hudson Power Express (CHPE), a 339-mile transmission line stretching from Quebec to Queens that opened in May[reference:65].
The line is officially the longest underground transmission line in North America[reference:66]. It could provide up to 20% of New York City's electricity demand, largely with abundant hydropower from Quebec[reference:67]. Over 99% of Quebec's electricity comes from renewable sources, with hydropower meeting most demand[reference:68].
But CHPE has been down for most of July, and the outages are raising questions about reliability[reference:69].
Two Outages in Two Weeks
The first outage occurred on July 1, reportedly caused by a trip at a converter on the Canadian side of the border[reference:70]. The second began on July 4 and stretched for 19 days, caused by a damaged section of cable on the US side[reference:71][reference:72]. Hydro-Quebec confirmed the two incidents were unrelated[reference:73].
Hydro-Quebec spokesperson Lynn St-Laurent said the damaged portion of cable had been removed and replaced, with repairs completed by July 24[reference:74]. The line was expected to resume service by the weekend[reference:75].
Similar woes have afflicted the New England Clean Energy Connect line, which opened in January. That 145-mile line from Quebec to Maine has also seen outages[reference:76].
What the Outages Mean
The good news for New York is that the grid wasn't relying on CHPE yet. "Our planning studies did not assume CHPE would be available this summer," said Kevin Lanahan, a spokesperson for the New York Independent System Operator[reference:77]. "A core principle of reliability planning is not relying on any single project.[reference:78]"
But the idea is that eventually, states and regions will be able to rely on these projects. Building massive transmission lines is a major long-term investment — CHPE cost $6 billion[reference:79]. In future years, as equipment gets stress-tested and utilities gain confidence, these lines could play a bigger role.
Construction and Context
The line consists of a bundle of two high-voltage direct-current power cables, each roughly five inches across[reference:80]. Developers buried the bundle underground or underwater across the length of New York State. Much of the line was laid at the bottom of the Hudson River, requiring special boats that shot water jets deep into the sediment to create trenches[reference:81].
Transmission Developers, owned by Blackstone, and Hydro-Quebec partnered to build CHPE[reference:82]. Construction began in late 2022 and wrapped up earlier this year[reference:83]. Planning started 15 years ago, with the permitting process formally beginning in March 2010[reference:84].
Connecting grids can help accelerate the transition away from fossil fuels[reference:85]. Research has shown that interconnection can cut emissions and lower system costs[reference:86].
The Drought Factor
One thing to watch: Quebec's hydropower fleet faces drought conditions that have eaten into water reserves used for electricity generation[reference:87]. That could mean there won't always be abundant hydropower to ship across the border, even if the transmission lines are able to carry it.
For now, CHPE is back online. But the July outages underscore the challenges of integrating large-scale transmission projects into the grid — and the importance of building reliability from the start.