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Guide to Operational Systems
This section provides information on the status of farm-scale digesters
currently operating at commercial livestock farms in the U.S.
The tables on this Web page provide detailed information about each of the operating digester systems, as of October, 2002. The tables also can be found in the 2002/2003 AgSTAR Digest (PDF, 14 pp., 814 KB, About PDF). Of the 40 operating digester systems, nine are at swine farms, 29 are at dairy farms, one is at a caged layer farm, and one is at a duck farm. Three of these are centralized systems that provide manure treatment for surrounding farms. In 35 of the 40 operational systems, the captured biogas is used to generate electrical power and heat. These produce the equivalent of approxamtely 4 MW per year. The remaining systems flare the captured gas for odor control, and they reduce methane emissions by about 7,400 tons on a carbon-equivalent basis. In total, the operating digesters prevented nearly 124,000 metric tons of methane, on a carobn-equivalent basis, from entering the atmosphere. Swine and dairy currently account for the majority of methane emissions from livestock management1.
1Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-1997. U.S. EPA, EPA 236-R-99-003, April 1999.
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