The Municipal Energy Agency of Nebraska (MEAN) will pay $51 million for a nearly one-fourth ownership interest in the Wygen I power plant in Gillette, Wyo.

Black Hills Corporation of Rapid City (NYSE: BKH) and MEAN announced the sale deal Monday. Officials said they expect to close the purchase by Dec. 31.

The partnership - MEAN will own 23.5 percent of the plant - will replace MEAN's current 10-year agreement with Black Hills Corp. to buy 20 megawatts of power annually from Wygen I. The coal-fired plant produces 85 megawatts of electricity annually.

MEAN's new ownership agreement also includes payment for overhead, operations and coal supply provided by Black Hills Corp.'s subsidiaries for the life of the facility.

"Purchasing interest in the Wygen I facility provides benefits to our wholesale customers," said MEAN Executive Director J. Gary Stauffer. "By acquiring ownership in the plant, we can continue to provide our customers with the benefits of competitively priced energy in a transmission constrained area for years to come."

The Nebraska Power Review Board approved the purchase and Black Hills Corp. will file with the Federal Energy Regulatory Commission.

Formed in 1981, MEAN provides wholesale power and energy-related services to 65 communities and one joint action agency in Colorado, Iowa, Nebraska and Wyoming. MEAN is one of four energy-related organizations of NMPP Energy, a joint-action agency headquartered in Lincoln, Neb.

Black Hills Corp. serves 750,000 utility customers in Colorado, Iowa, Kansas, Montana, Nebraska, South Dakota and Wyoming.

Learn more at www.blackhillscorp.com.