October 17, 2011 | Andrew Burger

The first anaerobic dry fermentation biodigester in the United States is up and running at the University of Wisconsin Oshkosh. The alternative power system has been producing clean, renewable electricity from plant and food waste to supply electricity and heat for the university campus since Oct. 3, the University news service reported.

University staff and students involved with the development of the power system had been stockpiling agricultural plant and food waste as feedstock in airless chambers and feeding it into the dry anaerobic biodigester since last summer in anticipation of bringing it online.

As background, anaerobic digestion consists of a series of processes in which microorganisms break down biodegradable material in the absence of oxygen. As part of an integrated waste management system, anaerobic digestion reduces the emission of methane gas, CO2, and “non-methane organic compounds” or NMOCs into the atmosphere.  Anaerobic digestion is also used as a renewable energy source as the process produces a methane and carbon dioxide rich biogas suitable for energy production. As the name indicates, ‘dry,’ as opposed to ‘wet,’ anaerobic digesters break down dry organic materials with moisture content of less than 75%, such as agricultural waste and plant material traditionally left over after harvesting a crop.

On Oct. 3, the University of Wisconsin Oshkosh team determined that the point had been reached where they had enough biogas to start-up energy production, so they turned on the plant’s gas turbine engines. The biogas from the biodigester drives the turbines, which are expected to generate enough electricity in the start-up phase to meet 5% of the university’s electricity and heating needs.

Besides producing clean, renewable energy from agricultural and food waste – corn stalks, husks, leaves, and discarded food – the bio-energy plant is serving as an ideal site for experiential learning, particularly for biology and environmental students.

The UW Oshkosh Foundation, which helped get the agriculture and food waste-to-energy plant built, is already working on plans to build a second, wet anaerobic biodigester for Milk Source at the Rosendale Dairy, the largest dairy farm in Pickett County, WI.

The larger, wet anaerobic biodigester will generate electricity from the methane produced by the decomposition of dairy cow manure.

Proposed plans call for revenue from the plant to flow into student scholarships, campus laboratory upgrades and expansion, and the creation of a rural community development innovation center.