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.
• Offer possible solutions to barriers that
prevent building more small on-farm
anaerobic digesters.
Introduction
Figure 1: Size distribution of US dairy herds in 2011
Image from http://thedairymom.blogspot.com
Small Digester Implementation
Image from www.epa.gov
Figure 2: Number of anaerobic digesters (2012) by state.
Results: Why install an anaerobic digester?
Increased Income
Figure 3: The anaerobic digestion process and its outputs
Images from http://www.plugflowdigester.com/
Plant Available Nutrients / Odor Control
Images from http://www.jipl.co.nz/anaerobicdigestion.html
Figure 4: Digestate
State Policy: Wisconsin and Michigan
Figure 5: Portrayal of Wisconsin’s projected green energy output by 2025
Images from www.usuca.org
Flexibility of Systems
Figures 6 & 7: Examples of two very different digester systems that ultimately perform the same process
Images from Wikipedia.com and http://brisbanelocalfood.ning.com/profiles/blogs/problem-pollution-solution-biogas
Results: Barriers to anaerobic digestion
implementation.
Dairy industry consolidation trends
Images from www.ers.usda.gov
Figure 8: The decreasing number of dairy cows over a thirty year period
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
Figure 9 & 10: Michigan and Wisconsin
Images from michfencing.net and wisconsinbroker.net
Cost of digesters
($3,500,000)
(4,000 head)
$875/cow
($1,000,000)
(600 head)
$1,667/cow
Figure 11: Comparison of Capital Cost of implementing a digester to number of head
Image from www.epa.gov
Natural gas market
Image from
Energytrendsinsider.
com
Climatic conditions
Figure 13: A comparison between heat
input requirement for digesters compared
to daily temperature
Image from http://www.sciencedirect.com/science/article/pii/S0961953410004757
Electricity and connecting to the grid
Figure 14: Cost of electricity (cents/kWh) in leading
countries
Images from http://thinkprogress.org/
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?
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.
Images from http://www.iea-biogas.net
How to fix it?
• Research
• Develop new digester systems.
• Develop new uses of digestate to 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!
• 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
M. Charles Gould
Extension Educator-Agricultural Bioenergy and Energy Conservation
Agriculture and Agribusiness Institute
Michigan State University
Small digester design
Dairy Farms in the United States (2009)
Herd Size
Number of Farms Percent of
(hd of cattle)
Total Farms
1-29
20,400
31.4
30-49
11,500
17.7
50-99
17,300
26.6
100-199
8,600
13.2
200-499
3,850
5.9
500-999
1,700
2.6
1,000-1,999
910
1.4
2,000+
740
1.1
Total
65,000
99.9
Adapted from: USDA, NASS Farms, Land in Farms and Livestock Operations
75.7%
88.9%
13.2%
94.8%
5.9%
61,650 farms <500 cows
94.8% of total farms
Small digester design
Average U.S. Digester Cost: $1.5 million (U.S. EPA,
2009)
Source: AgStar. 2010. Anaerobic Digestion Capital Costs for Dairy Farms.
Small Digester Case Studies
Farm
Joneslan Farm1
Number
of
cows
Total
Project
Cost ($)
$/cow
with
grants
230
823,000
278
3,578
Keewaydin Farm1
90
512,000
277
5,688
Bakerview EcoDairy1
44
600,000
?
13,636
Cornell Case Studies2
1,078
1,782,558
What components cost the most?
• Digester vessel and energy conversion
• Small farms – approximately 50%
• Large farms – approximately76%
1.
2.
$/cow
without
grants
Source http://ncrcrd.msu.edu/ncrcrd/webinars
Source: http://www.manuremanagement.cornell.edu/Pages/Resources/Resources-Case_Studies.htm
1,653
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: http://sistemabiobolsa.com/home/
The Small Digester Concept
H2S and moisture
removal, piping, valves,
electrical, and pumps
Pictures courtesy of EPT (http://eptpac.com/index.html), Garb-el Company (http://www.garb-el.com/) and M. Charles Gould.
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 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 digesters
US annual natural gas consumption
(MMcf/yr)
US natural gas consumption reduced by 25%
(equivalent to 1 billion barrels of oil annually)
MMt CH4 emissions from livestock manure/yr
US methane emissions reduced by 5% per year
(reduction of 34.5 million tons of CO2
equivalent)
Source: Lansing. S and Moss A.R. 2010. Small-Scale Anaerobic Digestion: Technology and Applications presentation.
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 Studies
• Joneslan Farm
• Financial
• Below are the projected estimated percent of revenue:
–
–
–
–
Total revenue from
Total revenue from
Total revenue from
Total revenue from
tipping fees (0%)
electrical generation (61.9%)
“avoided cost” of purchasing fossil fuels for heating (4.6%)
“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 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 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 Studies
• Reported problems/failures
1.
2.
3.
4.
5.
Site planning and design
Engineering
Construction and equipment
Biogas utilization and systems
System control and operation monitoring and control
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
• 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: gouldm@msu.edu
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