From an article by Ron Seely in the Wisconsin State Journal:

WAUNAKEE – Sure, the cows on the farm run by Chuck Ripp and his brothers near here generate a lot of manure — about 7 million gallons a year.

But now they also generate electricity.

Call it cow power.

Thursday, Dane County officials were joined by farmers and utility officials and others to flip a ceremonial switch and power up the state’s first cooperative manure digester. Spearheaded by Dane County Executive Kathleen Falk, the $12 million project has been more than six years in the making.

When it is in full operation, the digester plant with its three huge tanks will process manure from three adjacent farms and a total of 2,500 cows. It will remove about 60 percent of weed-growing phosphorus from the manure. The digester will produce methane and that methane will be used to power generators that will churn out $2 million a year in electricity, enough to allow Alliant Energy to power 2,500 homes.

And, according to Dick Pieper, with Clear Horizons, the company that will run the plant, the entire operation can be run with an iPod.

“The efficiency of this plant is exceptional,” said Pieper. “It’s world class.”

Falk said the plant represents an important milestone in green energy production and in manure management in Wisconsin. Many digesters don’t remove phosphorus, which clogs lakes with weeds and toxic blue-green algae during warm months. But the Dane County plant was designed specifically to remove the nutrient.