Leaders from the University of Wisconsin visited the existing dry anaerobic digester this month. An addition to the first-of-its-kind biodigester will equip the system to generate heat in addition to power.

Trailblazing waste-to-energy system will soon also heat Wisconsin campus

The University of Wisconsin-Oshkosh developed an innovative solution to two challenges as it aims to reach carbon neutrality: using cleaner energy and reducing food waste. The university plans to use food waste to heat campus buildings with a technology upgrade to an existing dry anaerobic digester — a system that uses bacteria to break down organic matter to generate biogas.

UWO’s biodigester was touted as the first of its kind in the nation when the plan was announced 12 years ago. It has been capturing methane from campus food and yard waste, then the gas is burned to generate electricity. The unit produces about 8% of the campus’ electricity. The new addition will equip the biodigester to generate heat in addition to electricity.

The new project is funded with a Public Service Commission Energy Innovation Program grant. It will connect the campus services center to the biodigester and use some methane for heat energy instead of flaring it. Project developers will use the grant money to install a biogas-powered hot water boiler and pipe heat for the campus services center, according to Wisconsin Public Radio.

“Right now all of the gas produced gets burned and what is produced is electricity and heat,” Stephanie Spehar, director of the university’s Sustainable Institute for Regional Transformations, said in a news release. “We are not using the heat portion as efficiently as we could be, so that is what the PSC heat connection project will attempt to solve.”

Energy produced in the Oshkosh campus biodigester , at left, will soon be used to heat the Campus Services Center.
Energy produced in the Oshkosh biodigester, at left, will soon be used to heat the Campus Services Center.

UWO estimates the new system will provide at least 75% of the heat for the 55,000-square-foot campus services center, saving about $24,000 per year. It will also reduce reliance on fossil fuel-derived natural gas, which the campus currently uses for 100% of its heat.

The university anticipates that in the future the biodigester could be upgraded to start producing renewable natural gas. The RNG could be used for cleaner transportation throughout the city and other functions.

“If we don’t need to use that energy during some months, we could perhaps funnel that into fueling compressed natural gas or liquefied natural gas vehicles such as those owned by the city of Oshkosh,” Spanbauer said. “This closes the loop by offering a fueling site for renewable fuel made from food and yard waste on campus.”