Montana

High-voltage substation construction and transformer work across Montana. Here is the grid ESS operates in.

How Montana makes its power

Montana's electricity comes mainly from coal and hydropower, which in 2024 supplied roughly 37 percent and 33 percent of in-state generation. Wind provides a significant and growing share, and renewable sources together account for more than half of the state's generation. The Colstrip plant is Montana's largest generating station, with about 1,500 megawatts of coal capacity after two of its four units retired in 2020.

Grid challenges

Colstrip, the state's largest power plant, has seen unit retirements and ownership changes that add uncertainty for the coal-heavy eastern grid. Montana sits on the seam between the Western and Eastern interconnections, which are not synchronized, and long distances separate generation from load. The proposed North Plains Connector, a 3,000MW, roughly 420-mile 525kV HVDC line between Colstrip and Bismarck, North Dakota, would create a new link among the WECC, SPP, and MISO grids.

Major utilities and grid operators

  • NorthWestern Energy
  • Montana-Dakota Utilities (MDU)
  • Colstrip co-owners
  • Rural electric cooperatives
  • Bonneville Power Administration and Western Area Power Administration
  • WECC / Western Interconnection

Sources

Substation work in Montana?

Tell us the voltage class, the site, and the timeline. ESS mobilizes across the West.

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