A $6 billion cable buried beneath New York promised clean power from Canada, then spent most of its first summer offline
On July 3, as a heat wave pushed demand across New York State, the grid imported 52 gigawatt-hours of electricity from Canada — enough to cover roughly 9% of that day’s total load. Some of that power traveled on a cable most New Yorkers have never heard of: the Champlain Hudson Power Express, a 339-mile underground transmission line running from Quebec to Queens that opened in May and carries the distinction of being the longest of its kind in North America. The $6 billion line represents a significant bet on cleaner power for one of the country’s most energy-hungry cities. But for most of July, it has been offline.
A $6 billion cable buried beneath New York
The Champlain Hudson Power Express runs 339 miles from Quebec to Queens, making it the longest underground transmission line in North America. Planning began 15 years ago — the permitting process formally started in March 2010 — reflecting just how long it takes to move major grid infrastructure from concept to operation. Construction started in late 2022 and wrapped up earlier this year.
The project was privately funded at a total cost of $6 billion. Transmission Developers, a company owned by asset management firm Blackstone, partnered with Hydro-Québec, Quebec’s public utility, to build and finance the line.
That’s a meaningful share for a city that consumes enormous amounts of electricity and has almost no room to build new generation within its own boundaries.
The engineering is worth understanding. CHPE consists of two high-voltage direct-current cables, each roughly five inches wide, bundled together and buried underground or laid at the bottom of the Hudson River. Specialized boats used water-jet trenching — shooting pressurized water deep into the sediment — to carve channels for the cable along much of the route.
The source of the power matters as much as the line itself. Over 99% of Quebec’s electricity comes from renewables, mostly hydropower, with wind capacity growing quickly. New York still relies heavily on fossil fuels. CHPE is, in effect, a clean-energy pipeline connecting an electricity surplus in one place to a carbon-heavy grid in another.
Why connecting grids matters for the clean energy transition
Transmission interconnection is one of the less visible but more consequential tools in decarbonizing electricity systems. When grids are linked, power can flow to where demand is highest — reducing the need to build redundant generation capacity that sits idle most of the time. Research suggests stronger interconnection can lower system costs and cut emissions across regions.
CHPE could eventually supply up to 20% of New York City’s electricity demand with low-carbon hydropower. That’s a meaningful share for a city that consumes enormous amounts of electricity and has almost no room to build new generation within its own boundaries.
The 15-year timeline from planning to operation isn’t unusual for projects of this scale. Permitting, environmental review, financing, and construction each add years. That long lead time is precisely why grid planners argue for starting transmission projects well before they’re urgently needed — by the time demand peaks, it’s already too late to build.
Two outages and a damaged cable
CHPE’s first outage hit on July 1, reportedly triggered by a converter trip on the Canadian side of the border. That disruption was brief compared to what followed: a second outage began July 4, and the line remained down as of July 22, meaning it was offline for most of the month it had been in commercial operation.
Officials traced the July 4 outage to a damaged section of cable on the US side. The manufacturer sent experts to investigate, the damaged portion was removed and replaced. Hydro-Québec spokesperson Lynn St-Laurent said post-repair testing was expected to wrap up by the following weekend.
Experts caution against reading too much into early outages. Normand Mousseau, a physics professor at Université de Montréal, noted that equipment of this complexity isn’t fully stress-tested until it’s actually running under live conditions. Other large transmission projects have encountered similar startup challenges. That context doesn’t make the downtime less frustrating — it does, however, place it in a familiar pattern for novel infrastructure.
New York’s grid held — but the pressure is building
The July heat wave arrived at an awkward moment, with CHPE offline and temperatures driving up demand. New York’s grid held anyway. The reason is straightforward: planners hadn’t counted on the line being available.
“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,” said Kevin Lanahan, a spokesperson for the New York Independent System Operator. He added that a core principle of reliability planning is not depending on any single project.
CHPE isn’t alone in its early struggles. The New England Clean Energy Connect line — a 145-mile cable from Quebec to Maine that opened in January — has also experienced outages, and very little additional energy has flowed into the Northeast from that project either. As these lines accumulate operating hours, grid planners will start factoring them into long-term supply strategies, and that’s when consistent performance becomes essential.
A drought shadow over Quebec’s hydropower
Even a perfectly functioning CHPE faces a variable it can’t control: the weather in Quebec. The province has experienced intense drought for three consecutive years, drawing down the water reserves that feed its hydroelectric fleet. Less water means less generation capacity and less power available to export.
This adds a climate-driven layer of uncertainty on top of the engineering and regulatory challenges already in play. The line could be operating flawlessly and still deliver less clean power than projected if Quebec’s reservoirs remain depleted.
CHPE’s long-term value depends not only on cables staying intact and converters staying online, but on the watersheds of northern Quebec continuing to receive the precipitation that makes hydropower possible. As drought patterns shift, that assumption deserves close attention from grid planners and policymakers on both sides of the border.
Carlos is an engineer with strong expertise in technical and industrial topics. He previously worked at international companies such as Siemens and is multilingual.
