NorthWestern Energy has signed an energy supply agreement with Atlas Power Group to power its flagship data center in Butte, Montana.

The new supply agreement will see NorthWestern supply Atlas with 75MW of power beginning in 2026, with a further 75MW expected in the next three to five years.

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Colstrip Power Plant – Photo by Eric Dietrich/MTFP

Atlas is already a NorthWestern transmission service customer.

“NorthWestern Energy’s strategic energy generation resource acquisitions and our balanced energy portfolio enables us to serve new large energy supply customers like Atlas Power Group’s Butte data center while continuing to provide our current customers with affordable and reliable energy,” said NorthWestern Energy president and CEO Brian Bird.

The Atlas Power Butte facility is an operational cryptocurrency and data center with a maximum capacity of 75MW. It is located on the former Mike Mansfield Advanced Technology Center, about six miles southeast of Butte, Montana.

“Atlas welcomes the opportunity to partner with NorthWestern Energy to supply cost-effective and reliable energy and transmission services to our flagship data center in Butte. With expanded growth opportunities on the horizon, securing long-term power supply at predictable prices is critical to support continued expansion and investment in our facilities,” said Atlas Power president and COO Jeff Young.

Cryptocurrency mining firm Cryptowatt initially owned the facility. However, a series of scandals led to its closure in December 2019 and the jailing of its owner, Matthew Goettsche. Atlas Power subsequently acquired the facility.

Atlas Power Group is a US company that develops flexible load data center hosting operations. In addition to its Butte data center, it has hosting facilities in North Dakota, Kentucky, and Texas.

The agreement with Atlas is NorthWestern’s second this week in Montana, following the signing of a 50MW supply agreement with an undisclosed data center. The delivery of the capacity is expected to begin in 2027.

The company's diversified energy portfolio includes hydroelectric power, wind, coal, gas, and solar. In Montana, 35 percent of its capacity is derived from hydroelectric power.

NorthWestern currently operates the 175MW Yellowstone County Generating Station and the 1,480MW coal-fired ColStrip Plant, which will increase in capacity in January 2026.

NorthWestern provides energy to Montana, South Dakota, Nebraska, and Yellowstone National Park.