Wisconsin county advances digester project

By Anna Austin
Posted August 23, 2010, at 3:36 p.m. CST

The ball is finally rolling for a community dairy manure digester project in Dane County, Wis., that is the first of its kind in the state and has been in the works for more than five years.

According to Gov. Jim Doyle's office, Dane County has 400 dairy farms that milk 50,000 cows and bring $700 million to the county each year along with 4,000 jobs.

John Welch, Dane County recycling/project manager, said initially the county set up a manure management task force and passed some resolutions for conducting a digester feasibility study in 2005. "We did two feasibility studies, one at the 10,000-foot level and then one closer to the ground for that specific project," Welch said. "We then put out a request for proposals last summer, and in-depth planning began last October."

Near the town of Waunakee, the facility will be centrally located between three participating family dairy farms, according to Welch. The manure will be transported to the digester via pipeline; the greatest distance is only about half of a mile. "Manure is pumped for about 20 minutes of every hour, so there's a very small receiving pit at each farm with only about a day's worth of storage," he explained. The digester will be a complete-mix mesophilic system, followed by solids separation with a centrifuge.

Groundbreaking for the facility, which is being developed by Clear Horizons LLC, was held in early August. When complete it will produce $2 million worth of electricity to power about 2,500 homes based on Dane County electricity usage, or roughly 2 megawatts.

Besides producing renewable energy, there were several other objectives in implementing this project from the county's standpoint, Welch said. These include improving water quality, helping to maintain and sustain the state's agriculture industry and to develop a project that will be economically viable. "This wasn't something we wanted to put money into every year to continue to function," he said, adding that the digester also will bring some new high-paying jobs to the area.

Welch said the last total cost estimate for the project was at $12.5 million. The state has chipped in to cover a portion of that, providing a $3.5 million grant because of an additional phosphorous removal component for water quality that is not typical in digester systems. "With that, we can capture 60 to 70 percent of the phosphorous in the manure," he said.

Meanwhile, Dane County is developing a second community digester project near the town of Middleton, for which the state will also provide a $3.5 million grant. Welch said county officials met with interested dairy farmers last week. "We're working really hard to get that one moving forward," he added.