Duke Energy Corp. plans to expand its portfolio of wind projects and other clean energy resources, according to Jim Rogers, the company’s chairman, president and chief executive, Dow Jones reports.

Duke intends to develop its renewable energy business into a stand-alone unit within subsidiary Duke Energy Generation Services.

In late May, Duke agreed to acquire Tierra Energy, an Austin, Texas-based wind-project developer that has more than 1,000 megawatts of wind assets under development in the West and Southwest. Duke plans to spend about $400 million through 2008 on Tierra’s first three wind projects.

Duke Energy Indiana has also agreed to purchase up to 100 megawats from a wind farm under development in Indiana.