	Introduction

An anaerobic digestion system (AD system) captures the methane that may otherwise be released from conventional manure handling methods, and has the potential to reduce greenhouse gas emissions and produce clean energy. There are more than 160 AD systems operating on farms nationally (see Table 1 ). Some factors that may be responsible for the low technology adoption rates are high capital costs, reliability concerns, and payment rates for the electricity generated. Congress may consider encouraging increased adoption of the technology by (1) identifying the primary technology benefit, so as to determine whether AD should be pursued in the framework of greenhouse gas emission reduction or clean energy development; (2) determining if the captured methane will count as a carbon offset; and (3) considering additional financing options for the technology. Dairy to reduce greenhouse gas emissions from dairy operations by 25% by 2020. This report provides information on AD systems, technology adoption, and challenges to widespread technology implementation, and explores the issues facing Congress concerning adoption of the technology. What Is an Anaerobic Digestion System? Captured methane may qualify as a carbon offset because the methane would no longer be released directly into the atmosphere. Biogas can be used to produce heat or generate electricity. One principal source of federal funding is the Section 9007 Rural Energy for America Program (REAP) of the Food, Conservation, and Energy Act of 2008 (2008 farm bill, P.L. 110-246 ). Another source of financial assistance offered for anaerobic digestion projects is the Renewable Electricity Production Tax Credit (REPTC; 26 U.S.C. §45).
Anaerobic digestion technology may help to address two congressional concerns that have some measure of interdependence: development of clean energy sources and reduction of greenhouse gas emissions. Anaerobic digestion technology breaks down a feedstock—usually manure from livestock operations—to produce a variety of outputs including methane. An anaerobic digestion system may reduce greenhouse gas emissions because it captures the methane from manure that might otherwise be released into the atmosphere as a potent greenhouse gas. The technology may contribute to the development of clean energy because the captured methane can be used as an energy source to produce heat or generate electricity.
Anaerobic digestion technology has been implemented sparingly, with more than 160 anaerobic digestion systems operating on farms nationwide. Some barriers to adoption include high capital costs, questions about reliability, and varying payment rates for the electricity generated by anaerobic digestion systems. Two sources of federal financial assistance that may make the technology more attractive are the Section 9007 Rural Energy for America Program of the Food, Conservation, and Energy Act of 2008 (2008 farm bill, P.L. 110-246), and the Renewable Electricity Production Tax Credit (26 U.S.C. §45).
Congress could decide to encourage development and use of the technology by (1) identifying the primary technology benefit, so as to determine whether it should be pursued in the framework of greenhouse gas emission reduction or clean energy development; (2) determining if the captured methane will count as a carbon offset; and (3) considering additional financing options for the technology.
This report provides information on anaerobic digestion systems, technology adoption, challenges to widespread implementation, and policy interventions that could affect adoption of the technology.