Milwaukee Journal  Sentinel: When it comes to generating renewable energy, Wisconsin lacks the  high winds of the Great Plains and the steady sunlight of Arizona, but it has  one abundant resource few others can match - cow power. Although renewable  energy makes up only a fraction of the state's total energy mix, one area that's  growing fast is systems that convert cow manure into electricity and heat. At  the Crave Brothers dairy farm and cheese factory in Waterloo, the farm's  anaerobic digester - its cow ...