The Governor, Xcel Energy and two environmental groups say a Billion dollar settlement to modernize three Twin Cities-area energy plants will mean dramatically cleaner air in Minnesota. Under the settlement announced yesterday (Thurs), Xcel will convert the Minneapolis Riverside plant and St. Paul High Bridge plant to natural gas; and also install new pollution control equipment at the Allen King plant on the St Croix river south of Stillwater. Minnesota Public Radio's Elizabeth Stawicki reports.