Duke Energy Building 3rd Wyoming Wind Farm

Officials say the Silver Sage wind farm will tie into existing transmission lines.

Duke Energy brought the Happy Jack wind farm online last fall. Cheyenne Light and Black Hills Power, another subsidiary of Black Hills Corp., have a 20-year agreement to buy the 29 megawatts of Happy Jack power.

One megawatt is enough electricity to power 800 to 1,000 homes.

Jason Ketchum, a spokesman for Black Hills Corp., said Cheyenne Light's peak demand was 168 megawatts, recorded last December.

"This agreement affirms our commitment to be an environmental steward and use a diversified portfolio to deliver economical energy to our customers," said David R. Emery, Black Hills chairman, president and chief executive.

(This version CORRECTS number of wind farms in hed, ADDS reference to third wind farm in 3rd graf)