Five Wisconsin-based dairy farms and one Iowa-based dairy operation in Alliant Energy's service territory currently account for a total of 3.71 megawatts of electricity produced by anaerobic digesters. The methane captured by the digesters is used as fuel to produce electricity, as well as heat for milking parlors and to pre-heating water.
The most recent digester signed on to supply renewable energy to Alliant Energy customers is in Dane County, Wisconsin and is operated by Clear Horizons. The digester is the first in the state to be shared by three farms. Between those three farms, about 2,500 dairy cows will provide about seven million gallons of manure for the digester a year. The facility is expected generate over 17 million kilowatt-hours annually.