Seal of Dane County County of Dane
County Executive's Office

Dane County and Gundersen Health System celebrate completion of Dairy Digester

October 03, 2014
Melanie Conklin, Office of the Dane County Executive, (608) 267-8823 or Brian Gilberts, Gundersen Health System, (608) 775-6399
County Executive


New Cow Power Project will Produce Renewable Energy, Cleaner Lakes


A unique partnership is turning cow waste from farms into renewable energy. La Crosse-based Gundersen Health System and Dane County are partnering with three Dane County farm families on the GL Dairy Biogas Project just outside of Middleton.


On Friday, Dane County executive Joe Parisi and Gundersen executives joined dairy farmers, project contractors and state and local officials to celebrate the completion of their dairy digester project.


“This Cow Power project paves the way for home-grown renewable energy, cleaner lakes and keeping our dairy farm families milking cows for generations to come.  Dane County is the 23rdlargest dairy-producing county in the nation, and we are turning all that milk into green energy to power our homes and businesses,” said Dane County Executive Joe Parisi.


The project consists of a digesters and generators to create energy. Cow manure from Blue Star Dairy Farms, Hensen Brothers Dairy and Ziegler Dairy Farms, is processed in three air-tight digester tanks. The tanks are heated to about 100 degrees – just like a cow’s stomach. Bacteria in manure thrives in these conditions, and they consume solids in the manure while releasing methane gas. Instead of being released into the atmosphere, the methane is captured at the top of the digester and burned in a generator to create electricity.


“At Gundersen, our mission is to improve the health and well-being of our communities. Yet, hospitals consume significantly more energy than other buildings of the same size – contributing indirectly to harmful emissions that have been linked to human disease,” explains Jeff Rich, executive director, Gundersen Envision, LLC., a subsidiary of Gundersen Health System. “Projects like this one get to the core of our goal – improving energy efficiency and creating renewable energy projects which produce a healthier environment for all of our communities. This project represents 14 percent of our goal to become energy independent later this year.”


The digester operation, which is owned by Gundersen Health System, is expected to generate approximately 16 million kilowatt hours of electricity annually which will be added to the local grid in Dane County through Madison Gas and Electric.  The electricity purchased by MGE is enough to power approximately 2,500 homes.


Because of the methane released by untreated manure, the digester will also reduce greenhouse gas emissions. The state DNR estimates that by treating manure and generating renewable electricity, the digester will reduce climate-changing emissions by 22,000 tons per year – equivalent to the CO2 emissions from over 4,000 cars.


The process also creates a large amount of clean, organic fiber by-product that has many horticultural uses or can be used on the farms as cow bedding. Purple Cow Organics of Middleton is using the compost material as a raw material in their products. 


“Purple Cow Organics is proud to be assisting in the processing and utilization of the co-products produced from the GL Biogas project. Purple Cow and Gundersen share common values from utilizing renewable energy sources to replenishing the soil for more sustainable growth, now and into the future, says Jeanne Whitish, CEO, Purple Cow Organics.


In addition to producing cleaner energy, the digesters will prevent more than 3,700 pounds of phosphorus surface runoff in Dane County every year. Phosphorus is the leading cause of green algae and other weed growth in Dane County’s lakes and comes from both urban and rural sources. It is estimated that 370,000 pounds of algae will be reduced annually in the Yahara watershed as a result of this project.


US Biogas was the digester’s project developer. The Wisconsin-based construction management firm CG Schmidt provided the design and construction for the digester and surrounding facilities. The project’s construction and development hired 58 full time equivalent jobs and will create approximately five full time equivalent jobs on an ongoing basis for operations.