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Five Star Dairy in Elk Mound, Wisc., installed a thermophilic digester about a year ago. Its 900 cows provide enough manure to generate enough power for about 600 homes.
Five Star owner and General Manager Lee Jensen. Five Star sells the biogas produced by the digester to a utility. It will take about 10 years for the revenue from gas sales to pay off the digester, he said, but in the meantime, the farm can cut costs in other ways. The liquids at the end of the process can be used as fertilizer while the solids are comfy cow beds. Neither the liquids nor cow beds smell nearly as bad as the manure did the first time around.