By Dan Burden, content specialist, AgMRC, Iowa State University, djburden@iastate.edu.

Revised June 2012.

The production of electricity or biogas from manure is an area of alternative-energy interest to many livestock producers. According to the Environmental Protection Agency, there are an estimated 186 digester projects operating on commercial livestock farms in the United States as of March 2012. Most projects are located on dairy farms.

But is it feasible and what is the cost of this energy production? A major report from the USDA-Natural Resources Conservation Service (NRCS) published in October 2007 is perhaps the first in-depth analysis of the costs of anaerobic digester systems compared to conventionally purchased electricity, natural gas and liquid propane. The report discusses strategies for reducing the cost of anaerobic digester operations, as well as the economic advantages of employing these systems in remote locations where the costs of conventional energy are higher. The researchers found that, in most situations in the United States, anaerobic digester systems could produce energy for many livestock operations at a cost competitive with or below commercial natural gas prices.
 
The report was a collaborative effort of the USDA-NRCS and several major U.S. university research teams. The report was compiled and authored by: Jennifer Beddoes, NRCS, Meridian, Idaho; Kelsi Bracemort, NRCS, Washington, D.C.; Robert Burns, Iowa State University; and William Lazarus, University of Minnesota. Various projects and analysis efforts that created the core of publication were produced by: Noller Herbert, NRCS, Washington, D.C.; William Boyd, NRCS, Greensboro, North Carolina; Peter Wright, NRCS, Syracuse, New York; Conley Hansen, Utah State University; Raj Raman, Iowa State University; and Barry Kintzer, NRCS, Washington, D.C.


Sources
Anaerobic Digester Methane to Energy: A Statewide Assessment, Wisconsin Focus On Energy, 2003 - Survey of various systems in place and being used in Wisconsin with operating and capital cost information.

An Analysis of Energy Production Costs from Anaerobic Digestion Systems on U.S. Livestock Production Facilities, NRCS, USDA, 2007.

Managing Manure with Biogas Recovery Systems. Improved Performance at Competitive Costs, U.S. Environmental Protection Agency (EPA), 2002.

U.S. Anaerobic Digester Status Report, AgSTAR, U.S. EPA, 2010.

Other Links

• The AgStar Program (farm-scale digesters), EPA, USDA, U.S. Department of Energy (DOE).
• Ambient Temperature Anaerobic Digester and Greenhouse for Swine Waste Treatment and Bioresource Recovery at Barham Farm (NC), North Carolina State University - This provides research information on an anaerobic digester used on a 4,000-head farrow-to-wean pork operation.
• Anaerobic Digestion, California Energy Commission.
• Anaerobic Digestion, Iowa State University, 1998.
• Anaerobic Digestion, State of Michigan.
• Anaerobic Digester Calculator, Biorealis Systems, Inc.
• Anaerobic Digesters for Farms and Ranches, Energy Efficiency and Renewable Energy, U.S. DOE - Recover methane (biogas) from animal manure for producing electricity, heat and hot water.
• Anaerobic Digestion of Animal Wastes: Factors to Consider, Appropriate Technology Transfer for Rural Areas (ATTRA), NCAT, 2006.
• Anaerobic Digestion of Corn Stover and Swine Manure, Iowa Energy Center.
• Basics of Energy Production Through Anaerobic Digestion of Livestock Manure, BioEnergy series, Purdue University, 2008.
• Biogas Anaerobic Digester Considerations for Swine Farms in North Carolina, North Carolina Cooperative Extension, 2008.
• Carbon Prices and the Adoption of Methane Digesters on Dairy and Hog Farms, Economic Research Service, USDA, February 2011 - Depending on the direction and scope of future climate change legislation, income from carbon off set sales could make methane digesters profitable for many livestock producers.
• Cooperative Approaches for Implementation of Dairy Manure Digesters, Rural Business-Cooperative Service, USDA, Research Report 217, 2009 - Dairy farmer use of anaerobic digesters is not widespread due to various challenges, including high costs and inadequate return. Cooperative efforts may allow milk producers to remain focused on milk production while lowering costs and/or increasing returns from energy and byproduct sales.
• Cowpies to kilowatts: Poop becomes power, Maine Public Broadcasting Network, June 2012 - Stonyvale Farm in Exeter, Maine, converts tons of manure a day into electricity via their anaerobic digestion system.
• Economics and Environmental Impact of Biogas Production as a Manure Management Strategy, Texas A & M University, 1997.
• The Economics and Feasibility of Electricity Generation using Manure Digesters on Small and Mid-size Dairy Farms, University of Wisconsin - Madison, 2002.
• Environomics - Cost-benefit analysis and operating experience for ten farm-based manure digestion systems developed as part of The AgSTAR Program, sponsored by the U.S. EPA, USDA and U.S. DOE to encourage farm methane recovery from anaerobic digestion.
• Farm Anaerobic Digesters: Producing Energy from Waste, Wisconsin Focus on Energy, 2009.
• Farm-Based Anaerobic Digesters, Michigan State University Extension - Fact sheet that describes different system designs.
• Managing Manure with Biogas Recovery Systems. Improved Performance at Competitive Costs, EPA, 2002.
• Manure Treatment Technologies for Livestock and Poultry Manure, Cooperative Extension System.
• Methane (Anaerobic) Digesters, University of Nebraska - Lincoln.
• Methane Gas Recovery, Wisconsin Public Service Corporation.
• Methane Generation for Livestock Waste, Purdue University - This publication is an overview of various systems for methane generation. It discusses the design of on-farm systems and their problems, and provides a procedure for determining the potential of the technology for the farm.
• Methane Recovery from Animal Manures, The Current Opportunities Casebook, National Renewable Energy Laboratory, 1998 - This 150-page book tells about on-farm anaerobic digester use.
• Midwest Rural Energy Group
• On-Farm Renewable Energy Production Survey (2009), 2007 Census of Agriculture, National Ag Statistics Service, USDA, February 2011 - This energy survey was the first on-farm renewable energy production survey conducted at the national level. The survey provides additional information on energy produced by wind turbines, solar panels and methane digesters that were in operation on farms in 2009. Detailed data includes the installation cost, percent of cost from outside funding, year installed and total amount of utility savings from the use of on-farm renewable energy production.
• Portland General Electric built a methane digester on a 350-head Holstein dairy farm near Salem, Oregon, that converts 20 to 28 tons of manure each day into up to 70 kilowatts of electricity.
• Profits from Manure Power? The Economics of Anaerobic Digesters On-Farm, The Minnesota Project.
• U.S. Anaerobic Digester Status: A 2011 Snapshot, AgSTAR, U.S. EPA, 2011.
• U.S. Anaerobic Digester Status Report, AgSTAR, U.S. EPA, 2010.

Businesses/Case Studies

• Crave Brothers Farm Reaps Big Benefits with Energy Efficiency and Renewable Energy, Wisconsin Focus on Energy, 2009 - Crave Brothers strives for economy and environmental sustainability with the installation of a renewable energy system in the form of an anaerobic digester.
• Colorado Pork, Institute for Energy and the Environment, Vermont Law School, 2007  - This medium-sized hog operation near Lamar, Colorado, uses its manure to produce electricity via an in-ground anaerobic digester.
• EcoCombustion Energy Systems Case Study, Eric Anderson and Andrew Dane, 2008 - Located in Wisconsin, this corporation has successfully designed and created an on-site system that burns the manure from the dairy operation. As a result, there is minimal byproduct from the initial manure, and energy is produced from the operation.
• Emerald Dairy Case Study, Eric Anderson and Andrew Dane, 2008 - This case study details how Emerald Dairy's anaerobic digester system takes the manure from the cows and creates outputs that are completely used on-site. As a result, the dairy has lowered its need to import outside products to the dairy.
• Haubenschild Farm’s Anaerobic Digester, The Minnesota Project, 2002 - This 39-page report documents the use of a digester on a Minnesota dairy farm.
• Quantum Dairy Takes the Modernization Leap, Wisconsin Focus on Energy, 2005 - This Wisconsin farmer introduced several new energy-saving measures and maximized energy efficiency by installing an anaerobic digester.
• Viability of Methane Production by Anaerobic Digestion on Iowa Swine Farms, Iowa State University, 1999 - This is a case study on the MaCabe pork operation in Southern Iowa and its long-term use of a digester.

Links checked June 2012