Hundreds tour West River, digester operation
Hundreds of people turned out for Riverview's open house at its West River Dairy operation on Thursday, affording the public an up-close look at a manure digester system which produces more electricity than even the massive dairy uses.
Riverview's open house was at its West River Dairy south of Morris. In addition to the digester, Riverview staff led dozens of tours of its dairy barns, its rotating milking parlor and informational booths.
Riverview's West River and Riverview dairies both have digester systems operating, and a third digester is in the plans for its District 45 Dairy, as well.
Manure from West River's 6,000 cows is pumped into a 150-feet by 300 feet insulated concrete tank that is 16 feet deep. The manure is kept at 100 degrees for about three weeks. The methane rises to the top two feet of the tank and is then carried into three 1,000 horsepower engines. After moisture is removed from the gas, it's burned to create electricity that is then carried to the electrical grid.
Jim Nieland and Miguel Urrutia, who coordinate Riverview's digester operations, said the digester produces enough electricity to power about 1,200 homes. The heat generated by the engines is circulated back into the manure tank to maintain temperatures.
The manure from a half-dozen cows is enough to power a home, Urrutia said. Nieland added that the system operates around the clock, 365 days a year, burns a greenhouse gas in methane, and has proven to be a steady, stable source of electricity.
In addition, digesting the manure eliminates weed seeds and pathogens, making the solids a much cleaner bedding material and helping to reduce somatic cell counts, Nieland said.
The liquids are pumped to lagoons and eventually used or sold as fertilizer.
But work continues to develop systems to scale. Right now, an operation would need about 1,000 cows to make digestion economically feasible, Nieland said.