HVDC transmission line to connect three ISO regions


Allette, Inc. and Grid United partnered to build what could become the first high-voltage direct current (HVDC) power transmission line that interconnects three independent system operator regions: the Midcontinent System Operator (MISO), Southwest Power Pool (SPP) and the Western Interconnection.

The new power project, the North Plains Connector, is a 385-mile HVDC transmission line that will connect central North Dakota to Colstrip, Montana. The power line will provide 3 GW of transfer capacity between the middle of the country and all three energy markets. The developers expect it to ease congestion on the transmission system, increase resiliency and reliability, and enable fast sharing of energy resources across a vast area with diverse weather patterns.

The North Plains Connector project is in the development phase. As project developer, Grid United is currently engaged with landowners and stakeholders to determine the best route for the line. Both companies expect project permitting to start this year as they work toward an in-service date of 2029, pending regulatory approvals.

North Plains Connector’s proposed route.

“It is no secret that the U.S. is in desperate need of new electric transmission capacity, and the North Plains Connector will provide resiliency and reliability benefits for decades to come,” said Michael Skelly, chief executive officer of Grid United.

Skelly is behind a previous transmission development company, Clean Line Energy, which dissolved in 2017 when a multi-state project failed to secure state regulatory approval. He previously helmed Horizon Wind Power, now part of EDPR, one of the largest onshore wind developers in the U.S.  He was the subject of the 2019 book, “Superpower,” by Wall Street Journal senior energy reporter, Russell Gold, who chronicled Skelly’s career as a risk taker in the project development market.

Grid United is developing five additional HVDC projects ranging from 100 to 300 miles providing interconnection of renewable energy in Texas, Arizona, Colorado, Oklahoma and Wyoming. The company backed by an advisory board that includes Carl Monroe, former chief operating officer of the SPP, Jack Hand, former CEO of Power Engineers, and William Kaul, former chief transmission officer of Great River Energy, a Minnesota utility.

Investments in transmission projects have grown in recent months with the promise of the Inflation Reduction Act putting subsidies behind renewable energy projects located in remote places of the grid, requiring a modern grid system.

On January 12, a partnership between Invenergy and the New Mexico Renewable Energy Transmission Authority outlined the 400-mile North Path transmission line, a proposed HVDC line that will have the capacity to move up to 4 GW of renewable energy produced in New Mexico to the state’s Four Corners region. The North Path line is expected to begin operations in 2025 and reach completion in 2028.

Another major transmission project was recently approved recently by the Arizona Corporation Commission (ACC).  SunZia is a 550-mile 525 kV HVDC transmission project. Separately, the New Mexico Public Regulatory Commission issued two approvals of Pattern Energy’s SunZia Wind project, a 3.5 GW proposed wind project in New Mexico that will provide power across the transmission line to Pinal County, Arizona. Once complete, the SunZia Transmission and Wind project represents the largest clean energy project in the U.S., including $8 billion in total investments.

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