Cows in southeastern South Dakota are powering vehicles in California.
The process of turning manure into fuel is nothing new, but government incentives for curbing greenhouse gases have caused a boom in such projects, especially at dairy farms.
Since June, a facility north of Beresford, South Dakota, has been making renewable natural gas – or biogas – from the manure of 15,000 cows. It’s pumped from the large dairy farms into four giant, domed tanks called digesters, holding 2 million gallons each.
“Those digesters are 2 million gallons of the unwanted side of the cow,” said John Reid, plant manager at the biogas operation, owned by DTE Vantage.
The manure sits in the digesters for about three weeks, stirred and kept at a steady temperature of about 100 degrees. All the while, microbes break down the manure in an aerobic digestion process, releasing methane and other gases. More >>