Benefits, costs and operating experience at ten agricultural anaerobic digesters

Farmer motivation for building and operating anaerobic digesters has expanded from solely energy benefits to include manure treatment cast savings, nutrient conversion, odor and pathogen control, and byproduct recovery. Over the last 3 years, three dairy plug flow digesters (NY, CT, OR), four covered pig manure lagoons (NC, VA, IA, MS) and three heated mixed pig manure digester (CO, IO,IL) have been placed in operation with AgSTAR technical assistance. The farms and their digester systems are described. The system installation, operation and benefits are described A summary table by type of digester is presented to allow comparisons of costs. Biogas recovery and use in boilers or engine-generators is discussed for each farm. Start up and operational lessons learned are presented The USEPA, USDA and USDOE sponsor the AgSTAR Program to encourage farm methane recovery from anaerobic digestion.