A liberal think tank is calling for state policies that would promote development of wind energy. Iowa Policy Project executive director David Osterberg says it’s time to require that utilities get 15 percent of their power from “alternative” energy sources like wind turbines. Osterberg says development of wind energy is “very good for farmers” because utilities buy or lease farmland for the turbines that are erected. Osterberg says Iowa is the third-largest producer of wind energy among the 50 states, but Minnesota is about to eclipse Iowa. Osterberg says the state of Minnesota requires its largest utility to buy 10 percent of its power from wind farms and other alternative energy sources. Osterberg says the state should use some of the “Iowa Values Fund” grants for wind energy projects. Current Iowa law requires investor-owned utilities to buy two percent of their power from alternative sources.