Minnesota Power has begun a $450 million North Dakota high-voltage direct current modernization project with Mortenson as the general contractor. The new facility is expected to replace 50-year-old transmission infrastructure, including new stations and converter substations in North Dakota and Minnesota, and is tied to a potentially massive new demand: a proposed $2 billion Google data center in Hermantown, Minnesota, in the northeastern part of the state.
The converter station at Center, ND, along with one at the other end of the 465-mile-long line at Hermantown, near Duluth, is planned to convert locally generated alternating current to direct current for long-distance transmission and can also convert direct current to alternating current when needed.
The project is part of a $900 million investment already underway in Minnesota with Mortenson as the general contractor for that portion to upgrade the transmission network.
The line provides renewable wind energy from Minnesota Power’s Bison Wind Energy Center in North Dakota.
“One of the biggest benefits of this modernization is flexibility,” Minnesota Power CEO Josh Skelton said in a press release. “When extreme weather hits, when system conditions change rapidly, or when energy is needed in a different place than expected, the ability to move energy both ways along this line becomes a real advantage.”
Siemens Energy is supplying HVDC technology for the project.
The line began operating in 1977 and is one of five HVDC overhead lines in the U.S. Minnesota Power began more than a decade ago to identify the need to replace equipment that dates to the 1970s, he says. In 2025, the North Dakota Public Service Commission approved permits for the transmission project.
In March, Minnesota Power signed a deal with Google to supply power to the proposed Hermantown data center, which would involve 700 MW of new clean energy resources, including 300 MW of wind power and 400 MW of battery storage.
The Hermantown data center is still under consideration and has faced opposition from residents who oppose its proposed $80 million property tax break and have concerns about water, noise and energy use.
Kimley Horn Associates is engineer and landscape architect for the proposed data center.
Whether the data center is built or not, Minnesota Power says HVDC technology is especially effective over long distances, losing 15% to 30% less energy than a comparable AC line.
