NorthWestern Energy is a partner in high-voltage transmission lines

NorthWestern Energy announced Thursday that it is partnering on a high-voltage transmission line that would connect the country’s eastern and western power grids.

Montana’s largest utility has reached an agreement with transmission developer Grid United and Minnesota power company ALLETE for 10% of the capacity of the North Plains Connector, 3,000-megawatt, 420-mile line that will connect Colstrip to Bismark, North Dakota.

NorthWestern wrote in a news release about the agreement that the transmission line will take advantage of varying load and weather patterns and increase grid reliability.

“NorthWestern Energy’s Colstrip, Montana substation is strategically located and will serve as a critical terminus for North Plains Connector and strengthen Colstrip’s position as a major energy hub,” NorthWestern CEO Brian Bird said in the release. “The North Plains Connector developer’s collaborative approach with Montana communities to address concerns and ensure the footprint reflects local priorities is consistent with NorthWestern Energy’s commitment to our customers.”

If built, the $3.6 billion project will connect three energy markets stretching from the West Coast to Mississippi, easing some of the transmission constraints that have frustrated energy developers trying to pump more electricity into the nation’s oversubscribed grid want to feed in. ALLETE is supposed to operate the route.

Kyle Unruh, policy manager for Montana and Idaho at Renewable Northwest, a green energy nonprofit, said the deal will benefit Montana energy consumers in several ways.

In addition to expanding NorthWestern Energy’s access to other markets for buying and selling electricity – “benefits that are passed on dollar for dollar to consumers,” he said – capacity on the North Plains line will “spin” NorthWestern’s revenue are a bit like a motorway toll for electricity.

“North Plains Connector is an extremely important project for Montana because it has the potential to provide all of these benefits, and those who subscribe to the line will see them,” Unruh said. “It should also enable construction of more power generation plants in the state, which has its own benefits. Everything is fine.”

Unruh added that the 525-kilovolt line unlocked a $700 million federal Grid Resilience and Innovation Partnership grant that the U.S. Department of Energy awarded to Montana in August, as well as $46 million, which the state received for road, sewer and water services to support the workforce of the connection construction.

NorthWestern is the fourth utility in the West to contract for some of the line’s capacity.

The three Pacific Northwest utilities that have signed agreements with Grid United are Puget Sound Energy, Portland General Electric and Avista. They are expected to use the additional transmission capacity to move wind energy from eastern Montana to the northwest while pursuing an output from Colstrip, the coal-fired power plant they co-own with NorthWestern and Talen, to comply with climate-related laws Washington and Oregon.

NorthWestern has expanded its fossil fuel footprint in recent years with a new gas-fired power plant in Laurel that came online this fall and plans to acquire additional shares of the Colstrip plant.

Unruh said the expanded transmission capacity will allow all of the aforementioned utilities access to expanded markets, regardless of the generation source those utilities offer.

North Plains developers have begun the permitting process, which is being overseen by the U.S. Department of Energy. They expect approvals to be issued in 2026 and construction of the line to begin in 2028, with the aim of having the connection operational in 2032.