"The AgSTAR Program has been very successful in encouraging the development and adoption of anaerobic digestion technology. The program was established in 1994, and by the end of 2010 the number of operational digester systems had reached 162 systems across the United States. This growth has produced significant environmental and energy benefits, including in 2010 alone, approximately 453,000 MWh equivalent of energy generation."
Full article can be viewed here on the EPA AgSTAR website.