More and more farmers and communities are interested in generating renewable energy from farm waste such as manure, so there is a growing need for information on the economic feasibility and sustainability of these processes.

Qingbin Wang and co-workers, University of Vermont, USA, have examined the economic feasibility for dairy farms to convert cow manure into electricity via anaerobic methane digestion. They assessed the cash flow of dairy farms participating in the Central Vermont Public Service Corporation (CVPS) Cow Power program over a period of 7 yr under different scenarios. They confirm that it is technically feasible to convert cow manure to electricity on farms, but economic returns are highly dependent on the base electricity price, premium rate, financial supports from government or other agencies, and sales of the byproducts of methane generation. In particular, relatively small changes in the premium price had a significant impact on the cash flow of an average operation and grants and subsidies were needed to offset the initial investment.

• Economic Feasibility of Converting Cow Manure to Electricity: A Case Study of the CVPS Cow Power Program in Vermont
  Q. Wang, E. Thompson, R. Parsons, G. Rogers, D. Dunn,
  J. Dairy Sci. 2011, 94(10), 4937-4949.
  DOI: 10.3168/jds.2010-4124