Extra credit

Features - Operations Focus

Extra credit Providing heat to a campus building is the next project phase for the University of Wisconsin Oshkosh’s dry fermentation anaerobic biodigester.

August 7, 2014
REW Staff

First, the University of Wisconsin Oshkosh (UW Oshkosh) bought a vacated big-box grocery store building in 2009 and recycled it into its Campus Services headquarters and shops. Then, at the urging of students envisioning a greener campus, the university completed its dry fermentation anaerobic biodigester right next door to the former store in 2011.

The biogas plant’s airless, indoor chambers vacuum methane off of rotting heaps of campus food, grass clippings and agriculturally sourced plant matter. Up to 10 percent of the campus’ power is generated by the innovative system, and a research facility was created, which is overseen and operated by staff and students.

Now onto the next step: a more symbiotic and sustainable relationship between the two buildings, located just 160 feet or so apart. UW Oshkosh will receive a grant for more than $24,000 to help develop the infrastructure necessary to “recover waste heat from the biodigester to heat the Campus Services Building,” according to the proposal filed with the “Focus on Energy Large Energy User Program.”

Warming up

The University and its foundation propose to team up once again—they’ll capture waste heat from the 370 kilowatt (kW) generator that serves the biodigester. Because the biodigester’s generator operates nearly continuously and is capable of providing heat from a jacket cooling water system, UW Oshkosh wants to transport the waste heat through a heat transfer system in hopes of providing 100 percent of the annual heat needed for the facility management building.

“This is an example of how sustainability begets sustainability,” says Thomas Sonnleitner, UW Oshkosh vice chancellor for Administrative Services. “We are now looking for ways to refine and expand the savings and energy-efficiency impact our biodigester has already helped us realize. Using its available waste heat for the benefit of the campus services is simply the next smart and right thing to do. We continue to work with the Wisconsin State Energy Office to earn final approval for the project.”

The university and its green architectural partner, Berners Schober Associates Inc. of Green Bay, Wisconsin, estimate the new on-campus biodigester waste heat project will save the institution more than $20,000 a year. The more than $240,000 project is projected to pay itself back within nine years with the support of the grant.

In its short life, the facility has been heralded as a success at the state’s third largest campus and a benefit for off-campus partners.

The biodigester facility is the first of three such facilities UW Oshkosh and its foundation have pursued. Two others are off campus. In March 2012, the Wisconsin Department of Administration (DOA), through the Department of Administration and State Energy Program, supported a feasibility study to install anaerobic digestion units on family farms of 500 dairy cattle or less.

A project at Oshkosh’s Allen Farms involving the first small-scale, 55 kW biodigester unit in Wisconsin conducted by BIOFerm Energy Systems, based in Madison, Wisconsin, and UW Oshkosh through the UW Oshkosh Foundation followed. In December 2013, the university and partners dedicated their largest digester, a $7 million biogas production facility and living, learning and renewable energy laboratory.

The project was funded by the UW Oshkosh Foundation in partnership with Milk Source, Soil Net, Alliant Energy, Infinity Lawn and Garden, BIOFerm Energy Systems and its parent company, the Viessmann Group.

The facility generates 1.4 megawatts of electricity through methane production from livestock waste on-site at the state’s largest dairy farm, Rosendale Dairy in Pickett. In September 2012, the university collaboratively developed and marketed an opportunity for regional businesses, schools, nonprofits and other organizations to help produce renewable energy at the facility.

Gaining partners

Restaurants, grocers, schools, hospitals and senior living communities in the region continue to be recruited as partners in a community-based, food-waste-to-energy collaboration led by UW Oshkosh and Sanimax. The latter has been a North American recycling pioneer since 1881, with 15 locations in Canada, the United States and Mexico, specializing in byproduct collection services and transformation into high-quality products.

Three years after start-up, the biodigester, developed in partnership with the UW Oshkosh Foundation and BIOFerm Energy Systems, is using campus food waste, sourced agricultural plant waste, city of Oshkosh grass clippings and city wastewater treatment plant biogas to produce methane and electricity.

Biogas released by the decomposing organic material is captured and reused for heat and electricity. After 28 days, half of the remaining material is reused for compost on local farms and the other half is reused in a new fermenter batch. Nothing is wasted and the byproduct is continually being refined by the university.

UW Oshkosh continues reaching out to restaurants, schools, health care organizations and other organic food waste (OFW) generators. They serve as suppliers of the fuel the biodigester needs to maximize methane and renewable energy. The combination of anaerobic digestion and compost technology is the best available treatment technology for recovering value from OFW materials.

“Sanimax is proud to be a part of our partnership with the University of Wisconsin Oshkosh,” said Alan Ceschin, organics business development director for Sanimax, to the university’s news source, UW Oshkosh Today, in a 2012 report.

“UW Oshkosh has invested in the technology for processing organic food waste into energy and building this technology into its curriculum for environmental sciences,” Ceschin says. “Sanimax brings years of experience and the necessary infrastructure for servicing food waste customers in the Fox Valley. Joining together with UWO to promote community awareness and participation for the diversion of food wastes from landfills just makes sense. It’s a clear win for the customer, the university and the environment.”

Sanimax has existing service routes for organic food waste materials in the Oshkosh and Fox Valley areas enabling easy setup for new customers. The company already services the university, collecting food wastes generated from campus and area dining facilities and transporting them to the biodigester. The public-private collaboration has helped UW Oshkosh reach its goal of generating about 8 percent of campus electricity from the biodigester alone.

Sonnleitner said the partnerships and biodigester advancements keep the high-impact renewable energy research thriving at the university’s Environmental Research and Innovation Center (ERIC) labs. There, students and faculty study biodigester methane production maximization. “This is just one more way our academic community works hand-in-hand with private enterprise to propel student learning, pursue high-value research beneficial to industries and seek solutions to some of our greatest environmental challenges,” Sonnleitner said.

There’s clearly an appetite for more sustainable uses for OFW. Data and public opinion reported before the Sanimax partnership’s kickoff suggested that demand abounds:

  • The 2009 Vision Oshkosh Final Report shows an overwhelming majority of survey participants wanting to see more sustainable initiatives in the community.
  • 62 percent of patrons choose restaurants based on commitment to the environment (Source: National Restaurant Association, 2008).
  • More than 36 million tons of food waste was generated in 2011. Food waste accounted for almost 14 percent of the total municipal solid waste stream, less than 3 percent of which was recovered and recycled in 2010. The rest —33 million tons—was thrown away. Food waste was the single largest component of municipal solid waste reaching landfills and incinerators. (Source: U.S. Environmental Protection Agency).

By helping area schools, companies and nonprofits and their students, customers and clients divert OFW from the landfill to the biodigester, Sanimax and UW Oshkosh are demonstrating the incredible power of the renewable energy plant to reduce our reliance on fossil fuels:

  • The biodigester produces enough energy to potentially power 210 average U.S. homes using 11,040 kW hours per year.
  • The biodigester produces enough heat to potentially warm 180 average U.S. homes using 43.9 million British thermal units (MMBtu) per year.
  • Its annual biogas production is equivalent to 132,237 gallons of gasoline, enough to potentially fuel 246 cars for 15,000 miles at 28 miles per gallon (mpg).

This article was submitted by University of Wisconsin Oshkosh. For more information, contact Laura Vandenberg at laura.vandenberg@sanimax.com or Michelle Bogden Muetzel at bogdenmm@uwosh.edu.


A portion of this story was developed from “Can’t clean your plate? No problem: UWO, Sanimax help community feed the Biodigester,” UW Oshkosh Today, Sept. 12, 2012.

Further reading on the University of Wisconsin Oshkosh dry fermentation anaerobic digestion project can be found in the article, “Ahead of the Class,” which appeared in Renewable Energy from Waste magazine in April 2012 and is available online at www.REWmag.com/rew0412-decomposing-organic-waste-into-energy.aspx.

A student-produced video explaining how the University of Wisconsin Oshkosh’s biodigester works is available at www.REWmag.com/uwo-digester-student-video.aspx.