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Anaerobic Digester Implementation on Small Dairy Farms in Michigan and Wisconsin: A Literature Review. By: Ben Bailey. Purpose. The purpose of this literature review is to identify factors that encourage and discourage small digester implementation in Michigan and Wisconsin.

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Anaerobic Digester Implementation on Small Dairy Farms in Michigan and Wisconsin: A Literature Review

By: Ben Bailey

  • The purpose of this literature review is to identify factors that encourage and discourage small digester implementation in Michigan and Wisconsin.
  • Offer possible solutions to barriers that prevent building more small on-farm anaerobic digesters.

Figure 1: Size distribution of US dairy herds in 2011

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small digester implementation
Small Digester Implementation

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Figure 2: Number of anaerobic digesters (2012) by state.

increased income
Increased Income

Figure 3: The anaerobic digestion process and its outputs

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plant available nutrients odor c ontrol
Plant Available Nutrients / Odor Control

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Figure 4: Digestate

state policy wisconsin and michigan
State Policy: Wisconsin and Michigan

Figure 5: Portrayal of Wisconsin’s projected green energy output by 2025

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flexibility of systems
Flexibility of Systems

Figures 6 & 7: Examples of two very different digester systems that ultimately perform the same process

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dairy industry consolidation trends
Dairy industry consolidation trends

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Figure 8: The decreasing number of dairy cows over a thirty year period

farmer views on small scale digestion
Farmer views on small scale digestion

“…digesters would not be a “real improvement” for farms that already utilize “good farming practices”.”

“it burns carbon when methane is burned as fuel,”

“One respondent indicated that he had “no ability to do it”…

“Overall, 45% of farmers surveyed were disinclined and 21% were inclined to adopt anaerobic digester technology.”

From Wilkerson, as cited in literature review

state policies
State policies

Figure 9 & 10: Michigan and Wisconsin

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cost of digesters
Cost of digesters


(4,000 head)



(600 head)


Figure 11: Comparison of Capital Cost of implementing a digester to number of head

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natural gas market
Natural gas market

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climatic conditions
Climatic conditions

Figure 13: A comparison between heat

input requirement for digesters compared

to daily temperature

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electricity and connecting to the grid
Electricity and connecting to the grid

Figure 14: Cost of electricity (cents/kWh) in leading


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what s missing
What’s Missing?
  • An economically viable way to install anaerobic digesters
  • Federal funding
  • High electrical reimbursement
  • Stable market economy for digesters to gain footing
  • State policies and permitting
  • High farmer opinions of digesters
how to fix it
How to Fix it?

Figure 15: Number of Anaerobic Digesters per Country

  • Model off Germany and other countries
  • Think outside the box
  • Identify synergies with other forms of renewable energy that generate profits for the farm.
  • Identify or develop less expensive materials that reduce the capital costs of the digester vessel.

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how to fix it1
How to fix it?
  • Research
    • Develop new digester systems.
    • Develop new uses of digestateto increase profits
    • Develop new strains of methanogens that work more efficiently at colder temperatures
  • Educate
    • Develop new training programs focused for farmers
    • Help policy makers understand the role of digesters
    • Help policy makers identify and react to overcome digester barriers
thank you for your time
Thank you for your time!
  • Questions will be held after the next presentation.
  • I now direct you to Charles Gould for the next segment of the webinar
small digester design and small digester case studies results

Small digester design and small digester case studies results

M. Charles Gould

Extension Educator-Agricultural Bioenergy and Energy Conservation

Agriculture and Agribusiness Institute

Michigan State University

small digester d esign
Small digester design

Dairy Farms in the United States (2009)






61,650 farms <500 cows

94.8% of total farms

Adapted from: USDA, NASS Farms, Land in Farms and Livestock Operations

small digester design
Small digester design

Average U.S. Digester Cost: $1.5 million (U.S. EPA, 2009)

Source: AgStar. 2010. Anaerobic Digestion Capital Costs for Dairy Farms.

small digester case studies
Small Digester Case Studies
  • What components cost the most?
  • Digester vessel and energy conversion
    • Small farms – approximately 50%
    • Large farms – approximately76%
  • Source
  • Source:
small digester design1
Small digester design

Jose Luis’ milking parlor. He ships his milk to Nestle.

Humza standing on a Sistema Biobolsa BB20 digester.

Installing a Sistema Biobolsa BB40 digester.

Concrete ramp to manure receiving basin.

Photos courtesy of Charles Gould.

Sistema Biobolsa web site:

the small digester concept
The Small Digester Concept

H2S and moisture removal, piping, valves, electrical, and pumps

Pictures courtesy of EPT (, Garb-el Company ( and M. Charles Gould.

small digester design2
Small digester design
  • Assumptions
    • 21 day HRT
    • Daily volatile solids loading rate – 0.33 lb/ft3
  • Three 40’ bladders would be needed for 100 cows.
  • One 40’ bladder would be needed for 38 horses.
  • Bladder dimensions are 40’x7.66’x3.92’.
  • Estimated cost for equine digester system described in previous slide using a 40’ bladder and cargo container is $20,000.
small digester design3
Small digester design
  • Increase digester efficiencies
    • Digester design
      • Scale up, not down
      • Reduce hydraulic retention time
      • Modular components
    • Cheaper digester vessels
      • Use materials other than concrete and steel
    • Focus on biogas as the end product
    • Improve digester performance
      • Feed digester high energy feedstocks such as fats, oils and grease, food waste, etc.
      • Manipulate methanogenesis?
      • Methanogens that are more efficient at producing methane?

Sources: Lansing. S and Moss A.R. 2010. Small-Scale Anaerobic Digestion: Technology and Applications presentation.

Siemens Industry Inc. 2010. Process analytics support higher yields in biogas plants

the bioenergy industry with smaller scale d igesters
The bioenergy industry with smaller-scale digesters

US annual natural gas consumption (MMcf/yr)

MMt CH4 emissions from livestock manure/yr

US methane emissions reduced by 5% per year (reduction of 34.5 million tons of CO2 equivalent)

US natural gas consumption reduced by 25% (equivalent to 1 billion barrels of oil annually)

Source: Lansing. S and Moss A.R. 2010. Small-Scale Anaerobic Digestion: Technology and Applications presentation.

small digester case studies1
Small Digester Case Studies
  • Bakerview EcoDairy - BC
    • 44 milk cows
    • Avatar digester
  • Joneslan Farm - VT
    • 230 milk cows
    • UEM Inc. digester
  • Keewaydin Farm - VT
    • 90 milk cows
    • Avatar digester
  • Two Wisconsin case studies will be posted shortly.
small digester case studies2
Small Digester Case Studies
  • Joneslan Farm
    • Financial
      • Below are the projected estimated percent of revenue:
        • Total revenue from tipping fees (0%)
        • Total revenue from electrical generation (61.9%)
        • Total revenue from “avoided cost” of purchasing fossil fuels for heating (4.6%)
        • Total revenue from “Other” sources:
          • Fiber sales (11%)
          • Avoided cost - On-farm bedding use (22.5%)
      • It is difficult to arrive at a true value of the electricity produced because of generator issues, but at a minimum, the value of the electricity produced is approximately $50,000.
      • In terms of annual operating expenses, if the generator engine was functioning correctly the annual operating expenses would be approximately 5% more than what was predicted.
small digester case studies3
Small Digester Case Studies
  • Keewaydin Farm
    • Financial
      • The digester has not been in operation long enough to arrive at a reasonable estimation of profit and loss.
        • From January through August 2013 the gross value of the electricity produced was $4,178.
      • Operating expenses are much higher than projected when the project was designed because of many costly repairs.
small digester case studies4
Small Digester Case Studies
  • Bakerview EcoDairy
    • Financial
      • Ongoing operational challenges had made it difficult to assess long-term operational requirements, as the system has yet to operate as a stable system for any length of time (>6 months).
      • Net annual cash flow: $3,480, based on the period of June 1, 2011 to December 1, 2012 when electrical production was metered and fiber was used as bedding.
small digester case studies5
Small Digester Case Studies
  • Reported problems/failures
    • Site planning and design
    • Engineering
    • Construction and equipment
    • Biogas utilization and systems
    • System control and operation monitoring and control
small digester case studies6
Small Digester Case Studies
  • Lessons learned from farmers
    • It is best to have a turnkey contract with performance guarantees.
    • Choose a digester vendor with capital and experience behind them.
    • Keep the system as simple as possible.
    • Hiring local skilled labor and making digester components locally reduces the overall cost of the project.
    • Digester vendors should include farmers in the design of the digesters as farmers may have suggestions that can save a project time and money.
    • Digester vendors should talk among themselves and share information to avoid the same costly mistakes that seem to be repeated when on-farm digesters are built.
    • Be careful with assumptions.
project summary
Project Summary
  • Less expensive digesters and favorable policies will support small digester growth in the U.S.
  • Need more basic and applied research.
  • Targeted farmer educational programs.

Ben and Jerry’s Ice Cream store in Vermont. Photo credit: Charles Gould.


This project was made possible by funding from The North Central Regional Center for Rural Development (NCRCRD).


M. Charles Gould

Extension Educator-Agricultural Bioenergy and Energy Conservation

Agriculture and Agribusiness Institute

Michigan State University

12220 Fillmore St, Suite 122

West Olive, MI 49460

Toll Free: (888) 678-3464, Ext. 68829

Direct line: (616) 994-4547

Email: [email protected]

Thank you!

MSU is an affirmative-action, equal-opportunity employer, committed to achieving excellence through a diverse workforce and inclusive culture that encourages all people to reach their full potential. Michigan State University Extension programs and materials are open to all without regard to race, color, national origin, gender, gender identity, religion, age, height, weight, disability, political beliefs, sexual orientation, marital status, family status or veteran status. Issued in furtherance of MSU Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Thomas G. Coon, Director, MSU Extension, East Lansing, MI 48824. This information is for educational purposes only. Reference to commercial products or trade names does not imply endorsement by MSU Extension or bias against those not mentioned.