New transmission line approved in Minnesota; will boost reliability, increase access to renewable energy for customers

Construction of the eastern segment, Alexandria-Big Oaks, to start in 2025

Several regional energy companies are moving ahead with a new high-voltage transmission line that will increase the capability of the transmission system to reliably meet customer demand and deliver energy within the Upper Midwest, following Thursday’s unanimous approval from the Minnesota Public Utilities Commission.

The new line, called the Big Stone South-Alexandria-Big Oaks project, will reduce congestion on the grid to make it operate more efficiently and ensure continued reliable electric service and system resilience. The project is a collaboration between Great River Energy, Minnesota Power, Missouri River Energy Services ( on behalf of Western Minnesota Municipal Power Agency), Otter Tail Power Company and Xcel Energy.

 “We thank the Commission for approving our Certificate of Need that recognizes the importance of this project to the Upper Midwest,” the energy partners said. “Expanding the transmission grid will help us lower costs, increase access to renewable electricity, and provide reliable service to our customers.”

Project developed in two segments

The new transmission line is being developed in two segments, with the western segment, led by Otter Tail Power Company, connecting the Big Stone South substation in northeastern South Dakota with the Alexandria substation in central Minnesota and the eastern segment, led by Xcel Energy, continuing from the Alexandria substation to a new Big Oaks substation near Becker, Minnesota.

The Commission’s approval of the Certificate of Need for the Minnesota portion of the transmission line and its concurrent approval of the eastern segment Route Permit paves the way for construction between Alexandria and the Big Oaks substation to begin in 2025. That segment, totaling about 105 miles, will add a second 345 kV circuit to the existing CapX2020 project that was installed mostly along Interstate 94 between 2010 and 2015. The CapX2020 project was developed, permitted, and constructed as double-circuit capable, anticipating that future load growth and generation development would require additional transmission capacity. Xcel Energy expects work on the Big Oaks substation will begin in 2025 with the eastern segment being complete by the end of 2027.

“The project will help us achieve our company’s plans to meet our requirements to deliver 100% carbon-free electricity by 2040, while also providing new connections to infrastructure to ensure reliable service as more renewable energy is added to the electric grid in the coming years,” said Ryan Long, President of Xcel Energy-Minnesota, North Dakota and South Dakota. “Thanks to the foresight and collaborative long-range planning of many stakeholders over the past two decades, more than 95% of the new infrastructure along the eastern segment will be in the existing right-of-way, saving time and money for our customers.”

The western segment, which will run approximately 100 miles between northeast South Dakota and Alexandria, Minnesota is being developed by Otter Tail Power Company and Missouri River Energy Services as double-circuit capable. The two energy providers plan to file a Route Permit application with the Minnesota Public Utilities Commission for the western segment later this year and the review process is expected to take between 12 and 18 months. They also filed a Facility Permit with the South Dakota Public Utilities Commission in April 2024 and expect a decision in April 2025. Construction is estimated to be  complete by the end of 2031.

“We’ve worked closely with landowners, local officials, and other stakeholders over the past 18 months to identify proposed route options that will minimize impacts to the area while balancing the interests of stakeholders. We look forward to the Commission’s review of our Route Permit application for the western segment beginning later this year,” said Tim Rogelstad, President of Otter Tail Power Company.

“When Minnesota’s utilities planned the CapX2020 expansion in the early 2000’s, we had the foresight to build some of the lines to be capable of carrying an additional circuit because we knew the time would come when we needed more capacity. That time has come. Now we can add that second circuit to existing infrastructure and double our capacity while minimizing landowner impact,” said Priti Patel, Great River Energy’s vice president and chief transmission officer.

“We are very excited to see approval of this project, said Dan Gunderson, Minnesota Power Vice President of Transmission and Distribution.  “The historic collaboration and foresight by the utilities within the State on transmission planning is evident with the expansion of this corridor and the addition of new critical connections, resulting in increased reliability and low-carbon energy pathways.” 

“The Big Stone South-Alexandria-Big Oaks transmission project represents a major step forward in strengthening the reliability and resilience of the Upper Midwest’s electric grid,” said Matt Schull, president and CEO of MRES. “As the region’s electric utilities continue to integrate more renewable energy into the grid, this new infrastructure will help deliver clean energy while meeting the growing demands of our communities. We are proud to collaborate with our partners on this critical project, which will benefit our customers and support a more sustainable energy future.”

The Big Stone South-Alexandria-Big Oaks project was originally identified by the Midcontinent Independent System Operator, Inc. (MISO) as part of the regional transmission organization’s Long-Range Transmission Plan Tranche 1 portfolio. The LRTP projects will increase access to energy from new renewable and other generation sources, reduce system congestion, improve long-term regional reliability, and enhance the resilience of the transmission grid in the face of extreme heat and cold. The projects will also help energy companies deliver energy where and when it is needed, as aging power plants throughout the region are retired and new generation is added to the system.