It was a moment nearly two decades in the making: This May, North America’s longest fully buried power line broke onto the scene…and it had a rough first few months. Now, the 339-mile Champlain Hudson Power Express (CHPE) delivers 1.3 GW of hydropower from Québec to NYC.
Clearly, pulling off massive undergrounding projects like CHPE proves no small feat—but these could become increasingly vital in the coming years.
The trend: Buried lines are nothing new, but large-scale undergrounding projects have growing appeal thanks to intensifying extreme weather and wildfire threats and recent tech advancements.
“Now, you see utilities that hadn't dreamed about doing undergrounding actually looking at it,” Mike Beehler, a transmission engineer and former VP at consulting firm Burns & McDonnell, told Energy Central.
Cutting-edge drilling equipment can get the job done cheaper and more quickly, Beehler said, and modern high-voltage lines take up a smaller footprint, lowering right-of-way costs. And as of 2022, buried cable costs had dropped from >$3M to $1-2M per GW-mile.
The lineup: A handful of interregional undergrounding projects are now in the works, including the 2.1-GW, 350-mile SOO Green HVDC Link project that’s planned to connect MISO and PJM territory.
Utilities are also spearheading ambitious builds in their footprints, including Dominion’s proposed 200-mile high-voltage line planned to serve Data Center Alley. Over in California, PG&E just floated a plan to build 5K miles of underground lines from 2028-2037, and estimates over $110B in long-term benefits from avoided fires and outages. And to maintain resilience during storms, Florida Power & Light has installed 2K miles of underground lines throughout the state.
These orgs aren’t alone. In a recent S&C Electric Company-sponsored survey of utility and energy industry pros, 41% of respondents said they expect undergrounding to drive the most growth in distribution investment over the next five years.
But are these lines worth it in the long run? Let’s dig in.🍴
The benefits:
Increased resilience: Burying lines protects them from a long list of hazards—including ice storms, wildfires, and, of course, rodents—all of which can lead to costly outages.
Easier permitting: Underground lines can often run through existing rights of way.
Cost savings: These projects can reduce expenses elsewhere. For example, they can curb the need for new power plants or local transmission.
The drawbacks:
High price tags: Despite recent advancements, burying transmission lines can still cost 10-20X more than building overhead lines, according to Xcel Energy’s 2024 numbers.
Temp troubles: Restarting after a blackout is trickier with buried lines, since they need to be actively cooled. And because these lines face higher risks of overheating, they can only transport so much power.
Long repair times: It can take weeks or months to locate and repair damaged underground lines, per Xcel.
The bottom line: As customers face quickly rising rates, careful cost-benefit analysis is key here, Seth Kaplan, VP of consulting firm Grid Strategies, told us. “The fundamental question is always: Is the juice worth the squeeze?” 🧃