A Princeton, Minn., dairy farmer is using a new piece of equipment called a digester to capture the methane in cow manure and turn it into energy. The 450-cow herd produces about 1,700 gallons of manure daily—that's enough gas to heat the barns and provide electricity to 28 homes. In addition to capturing the methane for power, the digester controls the odor produced by the manure gas. The remaining manure turns into fertilizer for the cornfields that feed the cows, thus bringing the process full circle.
About six digesters can be found in Minnesota, with another dozen or so around the nation. The technology is not cheap: The cost of Princeton farm's system was about $300,000, but would be less for smaller farms.
