Argo Infrastructure Partners subsidiary AIA Energy North America has signed an agreement to purchase 49.9% stake in Black Hills Colorado.
Terms of the deal have not been disclosed.
Black Hills Colorado is an indirect subsidiary of South Dakota-based Black Hills Corp and operates 200MW natural gas-fired power facility in Pueblo, Colorado.
As part of the long-term contract, the facility provides its generating capacity to the Black Hills' electric utility in Colorado.
Argo managing director Aaron Gold said: "We are excited to form a partnership with the Black Hills team, a top-notch operator of utility and generation assets.
"As a long-term capital provider to the utility and energy sector, we look forward to working with Black Hills in supporting the stewardship of this critical facility and providing service to Black Hills Colorado Electric and, in turn, its customers, for many years to come."
Black Hills Corp chairman and CEO David Emery said: "We look forward to a long-term relationship with Argo, a team of experienced infrastructure investment professionals."
The deal is subject to customary Federal Energy Regulatory Commission approval.
Black Hills Corp's non-regulated businesses generate wholesale electricity and produce natural gas, oil and coal.
It serves around 1.2 million natural gas and electric utility customers in eight states.