An article by Diane Greer in BioCycle gives a detailed description of the biodigester at Gunderson Lutheran:
Gundersen Lutheran Health Systems and City Brewing Company, both based in La Crosse, Wisconsin, are partnering on an innovative cogeneration project fueled by biogas from the brewery’s waste treatment process. The system, which started operating in October, is expected to generate 3 million kilowatt hours (kWh) per year of electricity, equivalent to 8 to 10 percent of the power used on Gundersen Lutheran’s La Crosse and Onlaska campuses. City Brewing will employ waste heat from the system, estimated at 17,000 mmBtus/year, to warm its anaerobic digesters producing the biogas. . . .