Platte River Power Authority announced Tuesday that it signed an agreement with Salt Lake City-based Enyo Renewable Energy.
Platte River spokesman Steve Roalstad says the contract will run through June 2042.
The move will triple its wind power capacity for Fort Collins, Loveland, Estes Park and Longmont.
Officials say Platte River's delivered electricity from renewable sources could jump from about 30 percent to 48 percent.
The 22-square mile wind farm to be built along the Colorado-Wyoming border will provide 150 MW to the cities by the end of 2020.