Dane County mulling third community digester, alternative manure systems

Jan Shepel
Dane Co. wants to make sure that dairy farming has the chance to stay vibrant into the future. Handling manure is a key component in that request.

WAUNAKEE ‒ Dane County wants to make sure that a vital part of its economy – dairy farming – has the chance to stay vibrant into the future. Handling manure is a key component in that quest, which means finding a balance between responsible use of the nutrients and cost-effective practices on the farm.

To find out what’s on the minds of dairy farmers, Dane County’s Land and Water Resources Department staff held a meeting in Waunakee February 15 to gather input about farmer interest in a centralized location for a manure digester or other kinds of manure handling systems, like compost.

“We want to turn your manure into an asset,” said Laura Hicklin, director of the Land and Water Resources Department. “Agriculture is a huge part of our economy and we want to see a future for dairy farms in Dane County.”

Laura Hicklin

The county has already invested in two manure digesters. The first was built near Waunakee and takes liquid manure from three dairy farms via underground pipelines. Over the years it has had some problems, including an explosion and fire in one of the three digester tanks and manure leakage into a stream. Those problems made the news but have been remedied.

In 2021 those two digesters processed more than 90 million gallons of manure and removed about 168,000 pounds of phosphorus. The two digesters are partnerships between the county, independent businesses and farmers. After anaerobic digestion, the fiber and solids containing phosphorus are removed through centrifuges and screw presses. The liquid fraction, with its nitrogen and potassium, returns to the original farms and is used to fertilize cropland.

The second digester the county invested in is nearer to Middleton, serves three nearby farms, and is currently turning methane into compressed natural gas which is being trucked to the county’s landfill where it is put into a pipeline along with gas from the landfill’s operations. The Middleton digester facility includes a 71,000 square-foot building that is used to compost the separated solids.

Partners in a Middleton manure digester offered tours of the plant, including these large tanks where manure is heated and methane is collected. The plant has recently been retrofitted to produce renewable natural gas rather than electricity.

Hicklin said Dane County has put $3 million into this year’s budget to do a feasibility study for another manure-handling site, and possible land acquisition to make that possible, but added that not all of that money has to be used this year. Manure digesters are a treatment system that “isn’t perfect” she said, but they do add value to the manure.

The meeting with farmers wasn’t for her agency to “nit pick” about manure handling practices but to get ideas about their thoughts on a community manure facility and potential ways to add value to the manure, she said.

The county got involved in helping farmers search for ways to handle their manure in 2005 when there was a notable fish kill on the Sugar River. Farmers who spread manure on frozen fields were blamed for killing a large number of trout when that manure, and the snow it sat on, thawed and ran into the stream.

Those first interactions, said Hicklin, were based on the “blame game.”

In 2010 the Waunakee digester was built and in 2013 construction began on the Middleton unit. Both are “still in business” she said, and today both are adding participants. The county invested in the digesters as part of an effort to keep additional phosphorus out of the Madison chain of lakes. That nutrient is largely responsible for the growth of algae and weeds that make the lakes unpleasant or unsafe for recreation.

MORE: As state plans for more digesters, questions build up

The digesters have been part of a county-wide program that has helped the public understand that farms are important to the economy and that manure is an important asset to farmers and that it can be handled responsibly, she said. Various studies have shown that the community is behind these efforts.

Technology changes

Technology has been continually changing in the years since the existing digesters have been built. The original end-product was electricity, generated by the methane coming out of the digester. Currently the money-making end-product is natural gas, but “it may be electricity again at some point,” Hicklin said.

They are looking at the possibility that a new facility may produce livestock bedding, liquid fertilizer or granulated or pelleted fertilizer in efforts to add value to the nutrient stream. In general manure streams contain nutrients for growing crops, organic matter, solids, energy and fiber. Most of the kinds of projects the county is contemplating would not be possible at individual farm scale, she said.

But they want to do this now “before we end up in a situation that puts us back to where we were in the early 2000s – with the blame game,” she said. “We want to learn from farmers what their needs and goals are.” It wouldn’t be a good idea for the county to do a project that none of its farmers wanted or didn’t fit their needs, she added.

“We want to build trust so you believe in this project,” she told the farmers.

These trucks are used to haul compressed natural gas produced at a community manure digester facility near Middleton in Dane County. Methane produced by three manure digestion tanks is compressed and hauled to a pipeline near the county's landfill where it is put into the pipeline.

It’s also a good time to consider this kind of project because the Inflation Reduction Act, passed into law last year, may have funding for projects like this. The Farm Bill, which lawmakers have just started working on, is also on the docket and may have funding that could help bring this kind of project to reality.

There also may be opportunities to fund agricultural conservation easements on land farmers own in the county, she said.

Where the cows are

Kyle Minks, who is the Land and Water Conservation Department’s watershed manager, explained that this first meeting and others like it are aimed at identifying solutions for treating manure mainly in northern Dane County – because that’s where most of the animal numbers are -- that will “significantly improve nutrient cycling and reduce greenhouse gas emissions.”

“We want to look at different ways to collect, concentrate and redistribute manure nutrients in the county and create a revenue stream from that,” he said. Another goal would be to refine manure by condensing nutrients.

Minks said the idea of the project is to improve manure management for any size livestock operation. “Solutions need to be scalable and modular,” he added. A goal of this overall project is to “protect and improve water quality as it relates to manure management” with the objective of recycling manure’s nutrients.

The county conservationist hopes that these efforts will help balance crop nutrient needs with nutrient applications and draw down excessively high phosphorus soil tests where those exist.

A manure separator removes the manure solids for use as animal bedding or compost.

Sustainability goals include reducing methane emissions from manure, utilizing and enhancing soil health and carbon sequestration. Ideas for recycling the solids from the manure include using it as livestock bedding, pelletizing is as fertilizer or using it as an additive for building materials.

The team of conservationists held an extensive question-and-answer session with the 70 or so farmers that were on hand in Waunakee. Jeff Endres, a dairy farmer who is involved with the Yahara Pride farmers’ group in the area, commented that it is an open question whether or not farmers will be subjected to demands or if there will be an income stream from their proper handling of manure.

Jeff Endres

Some major companies who will “tell that story” to their customers are willing to pay and others don’t, he noted.

Hicklin said her agency plans to organize a tour to a Brown County digester facility this spring. It handles manure from 30,000 cows on 11 dairy farms.

One of the key questions that will need to be answered in Dane County is ownership. Should it be public/private, farmer-owned, or potentially a cooperative entity?

Requests for proposals on a feasibility study will go out this spring, Hicklin said, and that kind of study would generally take about a year or so. She told the group that the study would be aimed at looking at existing technology and would likely cost about $100,000.

They plan to get a group of dairy farmers together again for more input. “We need to have this dialogue.”

No site identified yet

She told the farmers that there has not yet been a site identified for any potential community digester or other facility, like a central composting site. They are targeting a facility that could serve 40,000 dairy cows. There are about 57,000 dairy cows in Dane County now.

Technology that was presented to farmers 15 years ago, when plans were being explored for the first of Dane County’s “community” digesters, is not the same as what’s being used today.

Minks said that digester economies have changed over the years. When the first of the county’s two “community” digesters was built, electricity was sold from it. Today, 95 percent of the revenue stream is coming from the natural gas that is produced at the digester. They now skip the step of running that gas through a generator and producing electricity. At nearly all digesters today, the production of natural gas is the reality that currently drives the bottom line.

Chuck Ripp is one of the farmers who pipes his liquid manure into the first of the county’s two digesters. He told the gathered farmers that he and his family have been working with the digester for 13 years. Initially the idea was that the digester would take all of their manure but after working with it, they learned that the process couldn’t take bed-pack type manure, the kind that is generated by steer pens and calf pens and has a substantial amount of bedding mixed in with it.

Their solution was to stack that manure and not put it into the digester. That was one of the bugs that had to be worked out from the farmers’ perspective. Another problem they identified was that there was no market -- no income -- for the solids coming out of the digester.

Minks told Wisconsin State Farmer that it wasn’t a preconceived idea that a community manure system would be a digester. There may be ways to handle manure through composting sites at satellite locations in the county, which is one of the things the feasibility study may look into.

For more on this, he suggested doing a web search for “Dane County Community Manure Management” or access the website