Biogas Digesters

Methane digesters are a rapidly developing technology that hold great potential for organic waste to produce energy. Methane digesters convert manure or other organic matter into biogas through a process called anaerobic digestion. In this process, bacteria decompose the organic matter in the absence of oxygen, producing a gas composed of 60 to 70 percent methane and 30 to 40 percent carbon dioxide—biogas. The biogas can then be combusted to power an engine generator or used in a modified hot water heater; emerging research is studying cleaning biogas for natural gas use. Farm owners can use generated power, heat, or eventually natural gas on the farm. Excess electricity derived from biogas can be sold to the grid through a cooperative utility agreement. Using biogas for natural gas is still evolving but possible scenarios for use is bottling it and then selling it to an industrial customer or pipeline injection.

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Digesters expert

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General Information Ryan Stockwell Amanda Bilek CERTs blog posts
Handbooks & Workshops Program Manager Program Associate CERTs case studies
Organizations The Minnesota Project Great Plains Institute CERTs presentations
Financing rstockwell@mnproject.org abilek@gpisd.net CERTs reports
Publications    
Case Studies    

General Information

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Biogas FAQ – CERTs

Biogas Basics – MN Dept. of Commerce State Energy Office

Commercial-Scale Biomass Gasification Power Production – University of North Dakota Energy & Environmental Research Center
The fact sheet presents an overview of UND EERC’s efforts to demonstrate the economic feasibility and practical nature of producing electric power from biomass gasification (wood chips, sawdust, agricultural residues, and byproducts from commercial industries).

Fact Sheet: Resources on Anaerobic Digestion – The Minnesota Project
Where to get the information you need to get started.

Midwest Rural Energy Council Digester Site
Contains many useful links, as well as information on the Wisconsin Biogas Development Group.

National Food and Energy Council
A wealth of information about agricultural methane recovery.

Renewable Energy Opportunities on the Farm – National Sustainable Agriculture Information Service
Renewable energy represents an important option for agricultural producers. This publication introduces three renewable energy resources that can be attractive and economically feasible for the farm: solar, wind, and renewable fuels.

Development Handbooks & Workshops

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Agricultural Biogas Casebook – Joseph M. Kramer, 2004
A report for the Council of Great Lakes Governors Regional Biomass Energy Program providing an overview of anaerobic digestion technology and methods, summaries of 20 regional biogas projects, information on grant and technical assistance programs, and contacts for government and business resources.

AgSTAR Handbook
This publication covers several chapters and appendices with pertinent information about how to go about designing and implementing an anaerobic digestion system.

Dairy Waste Anaerobic Digestion Handbook – Environmental Energy Company
This study outlines options for recovering beneficial products from dairy manure. It covers housing, transport, bedding, manure processing, and other details about digestion.

Digesters for Managing Animal Waste: A practical workshop – The Minnesota Project
On August 2002, The Minnesota Project hosted a workshop on anaerobic digesters in St. Cloud Minnesota, attended by 150 people. Agenda and contents of resource binder | Workshop presentations

Agencies, Organizations & Businesses

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Industry Directory for On-farm Biogas Recovery Systems – AgStar
The AgSTAR Industry Directory helps farm owners and others interested in on-farm biogas recovery systems identify appropriate consultants, project developers, energy services, equipment manufacturers and distributors, and commodity organizations. It provides company descriptions and contact information for each listed business.

AgSTAR
AgSTAR is a cooperative effort by several U.S. government agencies to promote and provide accurate information on manure digester systems. Many useful documents can be downloaded, including the AgSTAR handbook (a comprehensive guide to those considering a digester). There is also a software package available for analyzing the economics of digesters. AgSTAR also staffs a hotline: 1-800-AgSTAR (you need to leave a message and they will call you back).

Midwest Rural Energy Council
Anaerobic digester basics, alternative uses for biogas besides electricity production, financial assistance information and links, case studies and links to the Wisconsin Biogas Development Group.

The Minnesota Project
Case studies, general resources, financing tools, Minnesota resources and information on new and emerging technologies and research.

Minnesota Department of Agriculture, Agricultural Development Division
Information on Minnesota’s digester loan program.

Minnesota Feedlot Program – Minnesota Pollution Control Agency
MPCA is the state agency for regulating animal feedlots in Minnesota. They have a wide range of general and producer information.

Department of Bioproducts and Biosystems Engineering – University of Minnesota
University research unit with broad expertise in anaerobic digestion and odor control. Contacts: David Schmidt, 612-625-4262, schmi071@umn.edu or Phil Goodrich, 612-625-4215, goodrich@umn.edu.

Minnesota Department of Agriculture
MDA methane digester loan program, alternative generation research programs and a variety of reports, resources and links.

Agriculture Utilization Research Institute
The Agricultural Utilization and Research Institute (AURI) has a very useful “Self Screening Checklist” for evaluating if a digester is right for you.

Minnesota Milk Producers
The Minnesota Milk Producers are enthusiastic supporters of biogas digester technology and its installation on Minnesota’s dairy farms.

AD-NETT
AD-NETT is a network of professionals working in anaerobic digestion of agro-industrial wastes in Europe and Canada.

East Central Energy
East Central Energy is the first utility in the nation to offer customers the choice of “cow power” on their electric bill.

Financing

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Funding On-Farm Biogas Recovery Systems: A Guide to Federal and State Resources – AgStar
Provides information about programs and strategies, such as low-interest loans, grants, and tax incentives, that can help parties interested in implementing anaerobic digestion technology overcome financial barriers to project development.

Economics Fact Sheet – The Minnesota Project
Learn the basics of digester economics.

Renewable Energy Financing Fact Sheet – MN Dept. Agriculture
Fact sheet from the Minnesota Department of Agriculture on loan and grant programs available to farmers.

RFP: 2008 On-Farm Anaerobic Digester Grants – MN Dept. Commerce
The purpose of this Minnesota Department of Commerce Request for Proposals is to provide potential applicants with the necessary information regarding the 2008 On-Farm Anaerobic Digester Grant Round and application procedures. Application Due Date is April 29, 2008.

Methane Digester Loan Program – MN Dept. of Agriculture
The MDA developed the Methane Digester Loan Program in 1998 to help supplement the funds needed for livestock producers in Minnesota to begin installing digesters on their farms.

Publications

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Anaerobic Digester Systems for Mid-Sized Dairy Farms – Amanda Bilek, The Minnesota Project
96% of Minnesota’s dairy farms have 200 cows or less. However, current anaerobic digester technologies are only economically feasible for dairy farms that have 300 cows or more. The Minnesota Project is beginning work on studying appropriate digester models for Minnesota’s average dairy farm. Contact Amanda Bilek at the Minnesota Project, 651-645-6159 x.5 or abilek@mnproject.org for more information or with questions about this report.

Wisconsin Agricultural Biogas Casebook – Focus on Energy, Energy Center of Wisconsin – July 2008
Wisconsin continues to be one of the leading states in operating farm-based anaerobic digester systems. The Wisconsin Agricultural Biogas Casebook includes brief case studies of farm-based anaerobic digesters installed in Wisconsin. This report gives a snapshot with some history of the 17 operating anaerobic digester systems in Wisconsin as of June 2008. This information is presented to give those interested in digesters some insight into how these systems are working in Wisconsin. In addition, digester owners have generously shared experiences, ideas and innovations that may prove invaluable to those evaluating similar options for their farms.

An Analysis of Energy Production Costs from Anaerobic Digestion Systems on U.S. Livestock Production Facilities – USDA and NRCS (October 2007)
Report Overview: When considering anaerobic digesters, think simple and direct. Simplified systems that directly utilize biogas are typically more cost effective than complex systems that try to produce electrical generation. The cost of purchasing the electrical equipment involved, operating and maintenance fees make up much of the expense when looking as a whole at biogas systems. One’s chance of success is greatly increased by applying biogas on-farm for heating water or a current idea is heating animal housing from an indirect-fired heater. Keeping in mind, there will be a constant demand for heat throughout the year so that resources are not wasted. In deciding what specific system works best for the individual farm, one should take into consideration a multitude of factors: size of land, ease of implementation, worthwhile to replace current fuel source, efficiency, seasonal changes, etc. Mainly, there are three digester systems widely used today; covered anaerobic lagoon, plug-flow digester, and continually stirred tank reactors (mixed digesters), that had greater success than others. Although, other promising systems are out there, but they have not been installed in as great a number as the three previously mentioned. Always remember there are programs in place to help in acquiring renewable energy systems that can offset the overall cost.

Anaerobic Digesters Continue Growth in U.S. Livestock Market – US EPA AgStar (November 2007)
This update provides general information on anaerobic digesters in the US, as well as digester profiles and financial incentives.

The Economics and Feasibility of using Anaerobic Digesters on Small and Mid-size Dairy Farms – University of Wisconsin – Madison
The title of this report says it all.

Minnesota’s Potential for Electricity Production Using Manure Biogas Resources – MN Dept. of Commerce
This report’s objectives are to quantify on a county, regional and statewide basis the number of cows, swine and poultry farms that could potentially be used to generate electricity and to estimate the total electrical production potential. Includes economic models that identify minimum farm size where anaerobic digesters might be economically feasible.

Case Studies

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CERTs Biogas Digester Case Studies

Other Case Studies

  • Haubenschild Farms Anaerobic Digester – Carl Nelson & John Lamb, The Minnesota Project: This report was updated in August 2002 and provides detailed information about the Haubenschild digester project. Along with the report, The Minnesota Project website has a wealth of information on digesters.
  • Agricultural Biogas Casebook – Joseph M. Kramer, 2004: The Great Lakes Regional Biomass Energy Program has updated the 2002 casebook to include updates on the 19 farms originally profiled in 2002, with an additional profile of a new project in the region. The information contained in the casebook is incredibly useful information detailing operations that are operational or in the construction phase on anaerobic digestion. Costs, biogas and electrical output, and operation experience are included when available.
  • Digesters in Ireland – Practically Green: Site contains information on all the farm waste digesters in Northern Ireland.
  • Vermont Methane Pilot Project – VT Depts. of Public Service & Agriculture: Quarterly reports explore the use of methane recovery technology on Vermont dairy farms.

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Biogas Digesters