The Nexus research group with help from students in the Biofuels Technology course have installed a unique small-scale biodigester to convert organic waste into cooking fuel and fertilizer. The system is located inside the Nexus greenhouse facility at the Watauga County Landfill. The Homebiogas system was developed by an Israeli start-up company to create an appliance to turn household waste into energy. Sustainable Technology Associate Professor Dr. Jim Houser visited Homebiogas in Israel earlier this year to develop a relationship to pursue University related research with the system. How it Works: A slurry of organic waste (kitchen food scraps, animal manure, and even human manure) is loaded into the funnel to fill the bottom bag, the digester. Biogas Happens: Biogas (primarily methane and carbon dioxide) is produced by anaerobic decomposition of organic wastes. The gas is captured in the top bag and pressurized by the weight of sandbags to force the gas through a carbon filter to remove hydrogen sulfide, and finally to a single-burner stove. There is an isolation valve to close off the gas when not being used. The biogas is currently over 70% methane and burns clean like natural gas or propane. As new organic waste is added, the effluent passes through a chlorine table to ensure pathogen destruction and into a bucket from the outlet pipe. It is nitrogen rich and can be used as a fertilizer. The Nexus group is currently tracking the digester’s performance by logging temperature, pH, gas production and composition. Future work includes adding biochar to the digester to see the effects on gas production and fertilizer value of the leachate. The group is also interested in research in cold climate digestion and installing the equipment in developing communities abroad.
Dr. Jim Houser explains the Homebiogas digester
Gabbie Batzko loading the digester
Dr. Jeremy Ferrell measures methane concentration and demonstrates boiling water with clean burning biogas.