The Accomplishments

The AgSTAR Program has been very successful in encouraging the development and adoption of anaerobic digestion technology. Since the establishment of the program in 1994, the number of operational digester systems has grown to 140 systems across the United States. This growth has produced significant environmental and energy benefits, including in 2008 alone, approximately 341,400 MWh equivalent of energy generation.

Total Energy Production
(October 2009)

Select a state for a list of operational digester projects.

Numbers represent total annual energy production in MWh equivalent

Number of Operating Digesters
(October 2009)

Select a state for a list of operational digester projects.

Total farm-scale projects: 127
Total regional/centralized projects: 13

Select a Project Name for more details.

The development of anaerobic digesters for livestock manure treatment and energy production has accelerated at a very fast pace over the past few years. Factors influencing this market demand include: increased technical reliability of anaerobic digesters through the deployment of successful operating systems over the past five years; growing concern of farm owners about environmental quality; an increasing number of state and federal programs designed to cost share in the development of these systems; increasing energy costs and the desire for energy security; and the emergence of new state energy policies (such as net metering legislation) designed to expand growth in reliable renewable energy and green power markets.

Financial incentives have increased the deployment rate of manure digester systems. For example, grants and loans awarded by USDA Rural Development through the Farm Bill have been one of the primary methods for farms to partially fund installation of commercially proven livestock waste digestion technologies. Since 2003, USDA Rural Development has awarded more than $34 million for anaerobic digestion systems.

Estimated Annual Emission Reductions from Anaerobic Digestion

*Avoided emissions calculated based on EPA eGRID national average emission rates for electricity projects and EPA's "Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2006" for non-electricity projects. EPA eGRID data unavailable for 2001, 2002, and 2003, so values were extrapolated based on a linear decrease from 2000 to 2004. EPA eGRID data for 2005 and EPA greenhouse gas inventory data for 2006 were assumed for subsequent years as these are the most recent data available.

Anaerobic digesters reduce greenhouse gas emission reductions in two ways. The first is the direct methane emission reduction from the capture and burning of biogas that otherwise would escape into the atmosphere from the waste management system. For projects that generate energy, a second benefit is the avoided emissions of greenhouse gases (CO2, methane, and nitrous oxide) and other pollutants from the use of biogas to displace fossil fuels that otherwise would be used to generate energy.  The graph above shows the annual emission reductions, including both direct reductions and avoided emissions, resulting from anaerobic digesters since 2001.  

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