Anaerobic Digester Production and Cost Functions

Methane production from anaerobic digestion has long been technically feasible, but adoption has been limited by economic considerations. For the first time using survey data, methane production and cost functions for anaerobic digesters are estimated for U.S. dairy and swine operations. Farm size, digester inputs, digester design parameters, and construction materials all affect the productivity and profitability of an anaerobic digester. Economies of size were evident for plug flow and complete mix anaerobic digesters, which were more economically feasible on dairy farms than on swine operations. Methane production alone is not enough to provide positive net present values. On dairy farms, economic feasibility could be achieved by marketing co-products, but swine farms required government support to achieve positive NPVs.