Mortenson to Build $450M HVDC Line Upgrade Across North Dakota, Minnesota
Minnesota Power has broken ground on a $450 million high-voltage direct-current transmission modernization project spanning North Dakota and Minnesota, with Mortenson serving as general contractor, ENR Midwest reports.
Market Impact
The project will replace transmission infrastructure dating back to 1977, including new converter stations and substations in Center, N.D., and Hermantown, Minn., near Duluth. The 465-mile line delivers renewable wind energy from Minnesota Power’s Bison Wind Energy Center in North Dakota and is one of only five overhead HVDC lines operating in the U.S. Siemens Energy is supplying the HVDC technology.
The North Dakota Public Service Commission approved permits for the project in 2025, and Minnesota Power says it began identifying the need to replace the aging 1970s-era equipment more than ten years ago. “One of the most important benefits of this modernization is flexibility,” said Minnesota Power CEO Josh Skelton in a press release. “When extreme weather hits, when system conditions change quickly, or when energy is needed in a different place than expected, the ability to move power both ways on this line becomes a real advantage.”
The rebuild is part of a larger $900 million grid improvement investment already underway in Minnesota, also with Mortenson as general contractor. The line’s capacity is also linked to a proposed $2 billion Google data center in Hermantown. In March, Minnesota Power signed an agreement with Google to supply power to the facility, which would require 700 MW of new clean energy resources, including 300 MW of wind and 400 MW of battery storage. The data center remains under consideration and faces local opposition over an $80 million property tax break and concerns about water, noise and power use. Kimley-Horn is serving as engineer and landscape architect on that project. Minnesota Power notes that regardless of the data center’s outcome, HVDC technology loses 15% to 30% less energy than comparable alternating current lines over long distances.
What It Means for Subcontractors
- Structural steel and electrical contractors should watch for subcontract packages tied to new converter stations in Center, N.D., and Hermantown, Minn., as Mortenson mobilizes on the $450 million line.
- Firms with HVDC or high-voltage substation experience have an opening given Siemens Energy’s role supplying technology across both the North Dakota and Minnesota converter sites.
- The related $900 million Minnesota grid improvement project, also under Mortenson, may offer additional civil, electrical and E&I scope beyond the 465-mile HVDC line itself.
- Contractors bidding wind-adjacent transmission work should note the line’s tie to the Bison Wind Energy Center, signaling continued build-out demand in North Dakota’s wind corridor.
- The Hermantown data center’s power agreement calls for 700 MW of new clean energy, including 300 MW of wind and 400 MW of battery storage. Subcontractors should track the data center’s local permitting process, given ongoing resident opposition to its $80 million tax break, before counting on that demand materializing.
