Market Opportunities for
Biogas Recovery Systems
at U.S. Livestock Facilities
A^tab
•3^5?
SEPA
United States
Environmental Protection
Agency
www.epa.gov/agstar
June 2018
EPA-430-R-18-006

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AgSTAR is an outreach program jointly sponsored by the U.S.
Environmental Protection Agency the U.S. Department of Agriculture
(USDA), and the U.S. Department of Energy. The program encourages
the use of biogas recovery technologies at confined animal feeding
operations that manage manure as liquids or slurries. These
technologies reduce emissions of methane (a potent greenhouse gas),
generate clean energy and achieve other environmental benefits. For
additional information, please visit our website at www.epa.gov/agstar.

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Introduction	4
Document Update History	4
Environmental Benefits 	5
Economic Benefits	6
Identifying Profitable Systems	6
Energy Production Potential.	8
Top 10 States for Energy Potential	9
Biogas from Poultry Operations	11
Appendix A: Methodology	A-1
Appendix B: Profiles of Swine and Dairy States with
Biogas Energy Recovery Potential	B-1

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Introduction
Biogas is a valuable byproduct of decomposing animal waste in livestock operations': It is produced when the
organic fraction of manure decomposes anaerobically (i.e., in the absence of oxygen). Biogas typically contains
60 to 70 percent methane, the primary constituent of natural gas. Biogas recovery systems at livestock opera-
tions can be' a cost-effective source of clean, renewable energy that reduces greenhouse gas emissions.
A biogas capture and use project is most likely to succeed where manure IS collected as a liquid,slurry, or
semi-solid and stored in open pits, ponds, or lagoons. Because the vast majority of large dairy and swine oper-
ations in the United States use liquid or slurry manure management systems, biogas production potential at
these operations is high, as are the potential greenhouse gas reductions if biogas recovery systems are imple-
mented. Other animal sectors, including poultry farms and beef lots, manage manure primarily in solid form, and
efforts to more effectively produce energy from these management systems are also being developed.
Biogas can be collected from manure and
burned to meet on-farm energy needs such
as electricity, heating, and cooling. Surplus
electricity or biogas: can also be:sold to
neighboring operations or the utility grid.
As of August 2017, AgSTAR estimates, 250
manure anaerobic digester biogas recovery
systems were in operation at commercial
livestock facilities in the United States. The
full potential to provide renewable energy is
much greater: an estimated 8,100 U.S. dairy and swine operations (Table 1) could support biogas recovery
systems. These systems may also be feasible at some poultry and beef lot operations as new and improved
technologies for these manure types enter the market.
Document Update History
This document updates AgSTAR's 2011 Market Opportunities for Biogas Recovery Systems at U.S. Livestock
Facilities. It includes updates to USDA data and minor revisions to calculation methodologies or default factors
used in calculations. For example, for swine and dairy population data, EPA used USDA's 2012 Census of
Agriculture instead of the 2007 Census of Agriculture. For manure management system data, and calculations,
EPA used the updated Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2015. Methane's global
warming potential (GWP), which is used to estimate emission reductions:, was updated from 21 to 25 times the
heat trapping capacity of carbon dioxide (CO2) to be consistent with the Inventory and with Intergovernmental
Panel on Climate Change (I PCC) Fourth Assessment Report: Climate Change 2007(AR4).
Appendix B of this report includes data and analysis from specific swine- and dairy-producing states based
on data in EPA's previous report. EPA believes that agricultural practices have not changed significantly in
these states since the previous publication.
Table 1. Potential for Biogas Recovery Systems
at U.S. Swine and Dairy Operations
Animal
Sector
Candidate
Farms
Energy Generating Potential
MW
MWh/year
Thousands of
MMBtu/year
Swine
5,409
837
6,597,520
71,484
Dairy
2,704
1,172
9,240,893
100,124
Total
8,113
2,009
15,838,413
171,608

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Environmental Benefits
One of the biggest challenges facing livestock producers is managing the large amount of animal waste
(e.g., manure, process water) produced by their operations. Biogas recovery systems offer air and water
quality benefits for managing these wastes.
Odor control: Anaerobically digested manures produce significantly less odor than conventional storage
and land application systems. Stored livestock manure's odor mainly comes from volatile organic acids and
hydrogen sulfide, which has a "rotten egg" smell. In an anaerobic digester, volatile organic compounds are
reduced to methane and carbon dioxide, which are odorless gases. The volatized fraction of hydrogen
sulfide is captured with the collected biogas and destroyed during combustion.
Water quality protection and land conservation: Anaerobic digestion provides several water quality and
land conservation benefits. Digesters, particularly heated digesters, can destroy more than 90 percent of
disease-causing bacteria that might otherwise enter surface waters and pose a risk to human and animal
health. Digesters also reduce biochemical oxygen demand (BOD). BOD is one measure of the potential for
organic wastes to reduce dissolved oxygen in natural waters. Because fish and other aquatic organisms
need minimum levels of dissolved oxygen for survival, farm practices that reduce BOD protect the health of
aquatic ecosystems. In addition to protecting local water resources, implementing anaerobic digesters on
livestock facilities improves soil health. The addition of digestate to soil increases the organic matter content,
reduces the need for chemical fertilizers, improves plant growth, and alleviates soil compaction. In addition,
digestion converts nutrients in manure to a more accessible form for plants to use.
Methane reduction: Digesters reduce emis-
sions. Methane is a potent greenhouse gas
with a GWP about 25 times more powerful
than that of carbon dioxide over 100 year. In
2015, EPA estimates, livestock and poultry
manure was responsible for approximately 10
percent of annual U.S. methane emissions;
the majority of those manure emissions came
from swine and dairy operations. Biogas
recovery systems capture and combust
methane, reducing virtually all of the methane
that otherwise would be emitted. As shown
in Figure 1, installing digesters at dairy and
swine operations where it is feasible could
reduce their methane emissions by about 85
percent—2.2 million tons per year.
The use of biogas to generate energy can
also Offset fOSSil fuel use, which in turn lowers 2 Estimates based on installing biogas recovery systems at all
emissions of C02, another critical green-	economically feasible operations, as defined in Table 2.
house gas.
Figure 1. 2015 Methane Emissions and Potential
Reductions at Swine and Dairy Operations Where
Anaerobic Digesters Are Economically Feasible
Methane Emissions1
(tons/year, in thousands)
Potential Methane
Emission Reductions2
(tons/year, in thousands)
Swine
0 500 1,000 1,500 2,000 2,500 3,000
1 Emissions based on 2015 values from EPA's Inventory of U.S.
Greenhouse Gas Emissions and Sinks: 1990-2015.

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Economic Benefits
Biogas recovery systems offer substantial economic benefits, all of which improve the feasibility of a
potential project.
Energy use and sale: The principal economic benefit of biogas recovery is energy use, which can take
several different forms. Biogas can be used as a direct fuel source for heating, boilers, chillers, or drying,
or upgraded to a cleaner gas and used as vehicle fuel or put into natural gas pipelines for sale. It can also
be combusted in an engine-generator to produce electricity, which can power on-farm operations or be
sold to the electric grid. Additionally, waste heat from the engine-generator set can be captured in cogen-
eration power systems and used for heating the digester, or for water and space heating. Harnessing
power from anaerobic digestion gives farmers energy independence by allowing them to operate "off the
grid." Furthermore, energy added to the grid by anaerobic digestion helps local utilities meet renewable
energy goals.
Valuable byproducts: Another benefit of anaerobic digestion is the variety of byproducts that can be
created from the digestate (digester effluent) solids. Examples include fertilizer, livestock bedding, and soil
amendments that can be used at the farm or sold. Maximizing the value of manure through anaerobic diges-
tion helps facilities diversify their revenue and strengthens their resiliency to market fluctuations.
Tipping fees: Where feasible, facilities may accept organic waste streams from off site, including livestock
manure from neighboring farms or organic waste from local food-processing plants, groceries, restaurants,
schools, or other institutions. In many cases, facilities accepting offsite waste may charge a tipping fee to
manage these non-farm waste streams. In addition to boosting direct revenues, the co-digestion of non-farm
organic waste streams produces additional biogas.
Renewable energy credits and greenhouse gas markets: Using biogas for energy reduces methane emis-
sions and reduces demand for fossil fuels for heating or electricity. In 29 states plus the District of Columbia
and three territories, electricity produced from biogas may qualify operations with a digester to receive
renewable energy credits or a premium price for their green power.
Positive public image: The successful operation of an anaerobic digester limits the impacts of a farm on
the local community and promotes a positive public image. Farms with digesters often run regular tours that
educate groups about the technology and its environmental benefits. By connecting with their communities,
farmers maintain good relationships with their neighbors, which is good for business and can make farm
expansions more palatable.
Identifying Profitable Systems
Candidate farms for biogas recovery systems were identified using the characteristics described in
Table 2. These characteristics were chosen based on AgSTAR evaluations of the technical and economic
performance of successful digester systems operating on commercial-scale swine and dairy farms.
(Appendix A offers details on the methodology for identifying candidate farms and estimating their energy
production potential.)

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Table 2. Typical Characteristics for Profitable Biogas Recovery Systems
Animal Type
Manure Management Method1
Size of Operation
Dairy
Flushed or scraped freestall
barns and open lots
> 500 head
Swine
Houses with flush, pit recharge,
or pull-plug pit systems2
> 2,000 head
1	Assuming total solids content below 15 percent and at least weekly manure collection.
2	Swine confinement houses in cool regions, such as the upper Midwest, commonly use deep pits under slatted floors.
Biogas systems are not currently used with deep pits, which would need to be modified to remove manure more
often before biogas capture and use systems could be installed. The feasibility of conversion depends on the value
of the biogas produced relative to the capital investment required. Estimates in this report assume that deep pit
operations with more than 5,000 head could use biogas systems by converting to at least weekly manure removal.
Note that AgSTAR did not conduct a site-specific cost analysis; site conditions such as energy contracts,
environmental permitting requirements, and other variables will affect the economic feasibility of projects.
This report does not include poultry farms in its assessment of market potential—biogas from poultry opera-
tions is briefly discussed on page 11.
As shown in Table 1, biogas recovery systems are potentially profitable for more than 8,100 dairy and swine
facilities in the United States. These facilities are large operations that use liquid or slurry manure handling
systems, and collect manure often from animal confinement areas as described in Table 2.
Profitability depends on the ability to recover capital and operating costs at a reasonable rate of return and
generate a long-term income stream. Experience has shown that the profitability of biogas systems depends
on the size of the operation, the method of manure management, and local energy costs.
Size of operation: Available data indicate that the unit costs for construction, operation, and mainte-
nance decrease significantly as biogas system size increases. A positive financial return appears to be
most likely at dairy operations
with milking herds of at least
500 cows and at swine opera-
tions with at least 2,000 total
head of confinement capacity.
Manure management method:
Current digester systems are
designed for manure in a liquid,
slurry, or semi-solid state (Figure
2). Collection frequency also
influences the feasibility of biogas
recovery systems. Collecting
manure at least weekly minimizes
the loss of the biodegradable
organic matter that is converted
Figure 2. Manure Handling Practices Affect the
Feasibility and Choice of Digester Systems
Total Solids (%)
0	5 10 15 20 25 30
Manure


Water Added
Bedding Added ^

As Exci
reted



Classification



| Liquid
Slurry | Semi-Solid
Solid >



Handling Options


Pump | Scrape
| Scrape and Stack ^

>
Biogas Production
Recommended
Not Recommended
Digester Type
II II




Covered
Lagoon or
Attached Media

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into biogas during storage prior to digestion. Confined swine and dairy operations typically remove manure
as often as every few hours to every few days. In other animal sectors (e.g., poultry and beef operations), use
of dry manure management systems means manure is typically collected no more than three to four times
per year.
Energy costs: The value of biogas depends on the price of the energy it replaces (e.g., electricity, fuel oil,
liquefied petroleum gas [LPG], natural gas).
Typically, biogas generates electricity for onsite use, and any excess is sold to the local electric utility. This
strategy provides three possible sources of income:
¦	Avoided cost of electricity: The savings from electricity not purchased depends on local electricity rates.
Because the total revenue derived from biogas use usually depends heavily on the value of electricity,
relatively modest changes in rates can result in a significant change in the size of the operation where
biogas capture and use will be profitable.
¦	Sale of excess electricity to the local utility: There is significant variation from state to state in the prices
that utilities will pay small power producers. Rates can be very attractive in states with net metering, green
power markets, or green pricing programs.
¦	Waste heat recovery: Waste heat from engine-generator sets can be recovered and used for space and
water heating, thus reducing fuel oil or LPG purchases.
Although electricity generation is the most common use for captured biogas, upgrading biogas to pipeline-
quality natural gas is becoming more popular. Upgrading the biogas requires special processing equipment
to remove water, carbon dioxide, and hydrogen sulfide. Renewable natural gas (RNG) may be injected into
local utilities' pipeline systems, serving as a revenue source for projects. Some states, such as California,
may offer financial incentives for qualified projects to cover interconnection costs and to encourage use
of low-carbon fuels. RNG can also be used as vehicle fuel in the form of compressed natural gas (CNG) or
liquefied natural gas (LNG), which can yield significant cost savings on fleet truck fueling or other transporta-
tion costs. For instance, Fair Oaks Farms, in northwest Indiana, runs a fleet of over 40 CNG-fueled milk trucks
with the methane produced from their digesters. Each of these trucks travels around 270,000 miles a year,
and the CNG replaces 2 million gallons of diesel annually.
Energy Production Potential
Nationally, swine and dairy operations could generate nearly 16 million megawatt-hours (MWh) of electricity
each year—equivalent to more than 2,000 MW of electrical grid capacity or about 5.4 million MMBtu1 of
displaced fossil fuel use. According to the U.S. Department of Energy, the average price of electricity was
about 11 cents per kilowatt-hour (kWh) as of September 2017.2 Using this rate, swine and dairy operations
1	MMBtu = 1,000,000 Btu
2	U.S. DOE EIA. 2017. Table 5.6.A. Average Price of Electricity to Ultimate Customers by End-Use Sector. In Electric Power Monthly with
Data for September 2017. U.S. Department of Energy, Washington, D.C. Available at https://www.eia.gov/electricity/monthly/archive/
november2017.pdf.

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could generate: $1.7 billion annually in avoided
electricity purchases.
If captured biogas were directed to RNG or
CNG applications instead of power generation,
AgSTAR estimates, there is enough methane
production potential from candidate swine and
dairy farms to heat over 2.7 million homes or
produce over 8 billion pounds of CNG annually
(equivalent to 1.3 billion diesel gallons), enough
to fuel nearly 150,000 refuse trucks.
Top 10 States for Energy Potential
The number of dairy and swine farms with the
potential to recover methane varies significantly
from state to state. Figures 3 and 4 depict the
number of candidate swine and dairy farms in
each state, respectively.
Table 3 identifies the 10 states with the most
potential to generate electricity from swine
and dairy operations. For swine, the top 10
states account for about 88 percent of the
total electricity generation potential. Iowa and
North Carolina, the: largest pork-producing
states, account for 31 and 16 percent of the
total, respectively. For dairies,, the top 10 states
represent 79 percent of the total potential, with
California accounting for 30 percent.
Figure 3: Candidate Swine Farms
] 0 - 15 |	| 16-35	36-80	31 -250	>250
Figure 4: Candidate Dairy Farms
Appendix B, from EPA AgSTAR's 2011
report Market Opportunities for Biogas
Recovery Systems at U.S. Livestock Facilities,
offers more detail on the market potential
in the swine and dairy states with the
greatest potential for biogas recovery.

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Table 3. Top 10 States for Electricity Production from Swine and Dairy Manure
State
Number of
Candidate
Farms
Methane
Emissions
Reductions
(Thousand Tons)
Methane
Production
Potential
(Billion ft3/year)
Energy Generation Potential
(1,000 MMBtu/Year)
(1,000 MWh/Year)
Swine Farms
Iowa
2,174
331
24.30
22,430
2,070
North Carolina
761
192
12.21
11,266
1,040
Minnesota
691
64
7.64
7,052
651
Illinois
345
47
5.45
5,030
464
Indiana
302
34
4.11
3,795
350
Missouri
129
31
3.45
3,183
294
Nebraska
154
27
3.33
3,077
284
Oklahoma
45
49
3.26
3,013
278
Kansas
58
24
2.50
2,311
213
Ohio
226
15
1.73
1,594
147
Remaining 40 states
525
102
9.46
8,733
806
Swine Total:
5,409
915
77
71,484
6,598
Dairy Farms
California
799
431
32.64
30,125
2,780
Idaho
179
138
11.56
10,668
985
Wisconsin
358
88
9.02
8,323
768
Texas
126
102
7.10
6,553
605
New Mexico
88
83
6.26
5,780
533
Washington
122
54
4.80
4,428
409
Michigan
138
47
4.79
4,420
408
Arizona
56
59
3.84
3,544
327
New York
126
32
3.29
3,033
280
Colorado
58
31
2.72
2,514
232
Remaining 40 states
655
254
22.47
20,737
1,914
Dairy Total:
2,704
1,320
108
100,124
9,241
Overall:
8,113
2,234
186
171,608
15,838
Note: Subtotals and totals may not add due to rounding. The procedure for estimating the energy generation potential is explained in
Appendix A.

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Biogas from Poultry Operations
Poultry operations are classified as either producers of table eggs or birds for meat consumption, the latter
including broiler, turkey, duck, and goose production. Most poultry operations reduce manure moisture
content by evaporation, the addition of bedding material, or both. Dry manure management systems have
lower potential for anaerobic digestion because the microorganisms that degrade the organics require
moisture and the manure needs to be in a slurry state. Hence, poultry manure management systems often
are not readily adaptable to the use of anaerobic digesters. However, there are currently seven operational
poultry anaerobic digestion systems in the United States, indicating that developers can design systems to
overcome the challenges. The following describes typical poultry management systems:
Broilers and turkeys: The most common housing for meat birds is enclosed housing, where birds are raised
on litter (e.g., wood shavings, rice hulls, chopped straw, peanut hulls). Typically, the top layer of litter and
dried manure (termed "cake") that accumulates is removed between flocks (six to seven flocks per year are
cycled through), with total removal every one to three years. This infrequent removal cycle results in loss of a
substantial amount of the organic matter that is the source of biogas under anaerobic conditions. Meanwhile,
the litter material that is mixed with the manure has little biogas production potential.
Laying hens: Although many egg producers use systems to reduce manure moisture content in place,
anaerobic digestion can be incorporated into some manure management systems. Typically, layers are
raised in cages that are suspended above the floor to separate the layers from the manure.
¦	High-rise manure management systems use two-story houses that provide long-term manure storage
under cages in the upper story. The ventilation system is designed to dry the manure as it accumulates
under the caged birds. Therefore, the typical high-rise cage system is not suitable for anaerobic diges-
tion because the manure is too dry and the system is designed for long-term storage. In most operations,
liquid would have to be added to create a manure slurry.
¦	Scrape, flush, or belt systems are amenable to the inclusion of anaerobic digestion. In the first two
systems, cages are suspended over a shallow pit without litter and manure is removed mechanically or
hydraulically by flushing. In a belt system, manure is deposited on a continuous belt running under the
cages; this moves the manure to the end of the house, where it is placed into a spreader for immediate
disposal or a storage structure. Because the manure is removed regularly, has a relatively high moisture
content, and can be handled as a slurry, these systems are adaptable for anaerobic digester systems.
Dry systems, especially those that incorporate high-rate ventilation, promote volatilization of nitrogen into
ammonia, causing a loss of nutrient value. Wet (liquid) manure management systems will keep the nitrogen in
the manure until it is applied to the soil, assuming appropriate land application systems are used.
11

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12

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Appendix A
Methodology
This section describes the methodology used to estimate the maximum potential for U.S. swine-and dairy
operations to generate electricity from biogas systems. The general approach was as follows:
1.	Characterize swine and dairy animal populations and profiles of farm sizes by state, using data from
U.S. Department of Agriculture (USDA) reports.
2.	Estimate manure management practices, using data from EPA Inventory of U.S. Greenhouse Emissions
and Sink$(The Inventory report, in turn, was developed with data from USDA, expert input, and observa-
tions: by EPA.)
3.	Determine the animal populations on farms where biogas systems are feasible. The criteria described
in the "Identifying Profitable Systems" section were used to identify candidate farms.
4.	Estimate methane emissions and emission reductions from candidate farms. Methane emissions were
estimated using the same methodologies found in Inventory of U.S. Greenhouse Emissions and Sinks. It
was assumed that, when a farm converts to a biogas recovery system, the methane- emission reduction is
essentially 100 percent.
5.	Estimate the methane production and electricity generation potential. These estimates were based on
literature references and AgSTAR investigations.
Sections below discuss these steps in more detail, including data ¦sources and calculation methodologies.
1. Characterizing State Animal Populations and Farm Profiles
The potential of individual states to reduce methane emissions from dairy and swine manures was based,
respectively, on estimates of the number of milk cows that have calved, and the1 number of hogs and pigs in
each state as reported in USDA's 2012 Census of Agriculture)
Census data were used to determine the number of operations in each state with 500 or more cows and
the aggregate number of cows on these farms throughout the state. Census data were also used to deter-
mine the number of swine operations in each state with a confinement capacity of 2,000 or more head, and
the total number of hogs and pigs confined on these operations.
To develop the maps used in Appendix B, county-level population data were obtained from the USDA's 2007
Census of Agriculture. USDA does not publicly disclose all of the data acquired by the census; some county-level
population data were non-disclosed and therefore unavailable. To estimate the number of animals in the non-
disclosed counties, EPA first determined how many non-disclosed counties existed in each state, then subtracted
the total number of animals in disclosed counties by the total number of animals in the state, and finally assumed
an even distribution of these animals across non-disclosed counties. The resulting estimate of the number of
1 USDA NASS. 2014.2012 Csetsusof Agriculture. National Agriculture Statistics Service, Washington, DC.
A-1

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Appendix A
animals in each undisclosed county was then input into the state-level maps. Note that these profiles reflect the
older census data and that not all profiled states will match up with the top 10 states listed in Table 3.
2.	Estimating Manure Management Practices
This analysis primarily relied on the manure management system data discussed in EPA's Inventory of U.S.
Greenhouse Gas Emissions and Sinks: 1990-2015,2 for which the key data sources were USDA's 2012
Census of Agriculture, EPA's Office of Water, and other expert sources. More detailed information about the
data sources and the development of the manure management system data for dairy and swine populations
can be found in the EPA report.
3.	Identifying Candidate Farms for Anaerobic Digestion
Candidate farms for feasible anaerobic digestion were assumed to be:
•	Dairy farms with anaerobic lagoons or liquid slurry manure management systems and more than 500 cows.
•	Swine farms with anaerobic lagoons or liquid slurry manure management systems and more than 2,000
animals, and swine farms with deep pit manure management systems and more than 5,000 animals.
4. Estimating Methane Emissions by State and Animal Group
Methane emissions were estimated based on the methodologies used for EPA's Inventory of U.S.
Greenhouse Gas Emissions and Sinks: 1990-2015.3 These methodologies were developed by the IPCC
and presented in the 2006 IPCC Guidelines for National Greenhouse Gas Inventories.4 Methane emission
estimates were developed for each state and animal group using the following equation:
methane = population * VSE x MCF * B0 * 0.041
where
methane = total methane emissions from different animal types in different states and manure
management systems, pounds (lb) per year
population = animal population
VSE	= total volatile solids excretion rate, lb VS per animal per year
MCF	= methane conversion factor, decimal
E>0	= maximum methane-producing capacity of manure, cubic feet (ft3) methane per lb
volatile solids
0.041
= density of methane at 25° Celsius, lb per ft3
2	U.S. EPA. 2017. Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2015. Report No. EPA 430-P-17-001. Office of Atmospheric
Programs, Washington, D.C.
3	Ibid.
4	IPCC. 2006.2006 IPCC Guidelines for National Greenhouse Gas Inventories. Prepared by the National Greenhouse Gas Inventories
Programme, H.S. Eggleston, L. Buendia, K. Miwa, T Ngara, and K. Tanabe (eds.). Japan.

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Table A-1 shows example data for two types of manure management systems. For swine, total volatile solids
(VS) was calculated using a national average VS excretion rate from the Agricultural Waste Management
Field Handbook,5 which was multiplied by the typical animal mass of the animal, the state-specific animal
population, and the number of days per year. For dairy cattle, regional VS excretion rates per animal per year
that are related to the diet of the animal were used.6 The maximum methane producing potential of manure
(Bo) varies by animal type and is based on values from the literature. The Bo for dairy cows is 3.84 ft3 of
methane per pound of VS and the Bo for swine is 6.6 ft3 of methane per pound of VS.7-8
Methane conversion factors (MCFs) were determined for each type of manure management system and are
shown in Table A-2. For dry systems, default IPCC factors were used. MCFs for liquid/slurry storage tanks
and ponds, anaerobic lagoons, and deep pit systems were calculated based on the forecast performance of
biological systems relative to temperature changes as predicted by the van't Hoff-Arrhenius equation. The
MCF calculations model the average monthly ambient temperature, a minimum digester system tempera-
ture, the carryover of VS in the system from month to month, and a factor to account for management and
design practices that result in the loss of VS from lagoon systems.
Example calculations: Page A-4 presents example methane emission reduction calculations from a biogas
recovery system. Table A-1 shows the calculation of direct methane emission reductions from a biogas
recovery system that replaces a manure storage tank or pond and an anaerobic lagoon on a farm with 500
dairy cows in California. The methane emission reduction from a biogas recovery system is equivalent to
the methane emissions from the baseline manure management system that it replaces—not the amount of
methane produced by the anaerobic digester. The amount of methane that an anaerobic digester would
collect and combust is greater than the amount of methane produced by the baseline manure management
systems because digesters are designed to optimize methane production.
5	USDA. 1996. Agricultural Waste Management Field Handbook. Natural Resources Conseivation Seivice, Washington, D.C.
6	U.S. EPA. 2017. Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2015. Report No. EPA 430-P-17-001. Office of Atmospheric
Programs, Washington, DC.
7	Hashimoto, AG. 1984. "Methane from Swine Manure: Effect of Temperature and Influent Substrate Composition on Kinetic Parameter (k)."
Agricultural Wastes, 9:299-308.
8	Morris, G.R. 1976.Anaerobic Fermentation of Animal Wastes: A Kinetic and Empirical Design Fermentation. M.S. thesis. Cornell University,
Ithaca, New York.

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Appendix A
Table A-1. Methane Emission Reduction Impacts
Factors
Storage Tank
or Pond
Anaerobic
Lagoon
Number of cows
500
500
Total VS excretion rate (VSE), lb VS/animal/year
6,170
6,170
B0a, ft3 CH4/lb VS
3.84
3.84
MCF for California, decimal
0.34
0.73
CH4 density, lb CH4/ft3
0.041
0.041
CH4 emissions/emission reduction from biogas
capture and use,c-d tons CH4/yr
82.6
179.4
Equivalent reduction in C02 emissions,6 tons C02e/yr
2,064
4,485
a The B0 and MCF values were obtained from EPA's Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2015.
b The MCF values shown here and in Table A-2 are rounded. The values calculated in this example use the actual values; calculated values
vary based on rounding.
c CH4 emissions are calculated for these examples using the equation on page A-2.
CH4 Emissions = Number of cows x VSE x MCF xB0x 0.041 lbs x 1 ton/2,000 lb
d It is assumed that biogas combustion destroys essentially 100 percent of baseline methane emissions.
e CH4 has approximately 25 times the heat trapping capacity of C02.
C02 equivalents (C02e) = CH4 Emissions x 25
The use of biogas to generate electricity also reduces C02 emissions from conventional power genera-
tion sources because fewer fossil fuels are combusted by electric power plants. The following shows an
example calculation for estimating reduced C02 emissions:
Equation	Values
VS added, lb VS/yr	3,084,881
VS = number of cows x VSE
CH4 production, ft3 CH4/yr	11,845,945
CH4 production = VS x 3.84ftJ CH4/lb VS added
electricity generation potential, kWh/yr	1,009,127
electricity generation potential = CH4 production x 923 Btu/ft3 x kWh/3.413 Btu x 0.35x0.9
(0.35 is the engine efficiency and 0.9 is the online efficiency)
reduction in utility carbon dioxide emissions,e ton/yr	828
emissions reduction = electricity generation potential x 1,641 lb x MWh/1000 WA/h * 1 ton/2,000 lb
e Based on 1,641 pounds of carbon dioxide emitted per MWh generated, which is the national weighted average C02 marginal emission rate
for 2016 from EPA's Avoided Emissions and Generation Tool (AVERT). C02 emission rates vary across the United States depending on local
electricity generation sources.

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Table A-2. Methane Conversion Factors by State for 2015 (percent)
State
Dairy
Swine
Anaerobic
Lagoon
Tank/Pond
Anaerobic
Lagoon
Tank/Pond and
Deep Pit
Alabama
78
42
78
41
Alaska
49
15
49
15
Arizona
79
58
78
49
Arkansas
77
37
78
40
California
73
34
73
33
Colorado
66
22
68
24
Connecticut
71
26
71
26
Delaware
76
33
76
33
Florida
82
60
81
58
Georgia
78
44
78
42
Hawaii
77
58
77
58
Idaho
68
25
65
22
Illinois
73
30
73
29
Indiana
71
27
72
28
Iowa
70
26
70
26
Kansas
76
34
76
33
Kentucky
75
33
75
33
Louisiana
80
50
80
50
Maine
65
21
65
21
Maryland
75
31
75
32
Massachusetts
69
24
70
25
Michigan
68
24
69
24
Minnesota
68
24
69
24
Mississippi
79
45
78
43
Missouri
75
32
74
32
Montana
60
19
63
21
Nebraska
72
27
72
28
Nevada
70
26
71
28
New Hampshire
66
22
66
23
New Jersey
74
30
75
31
New Mexico
74
32
72
29
New York
67
23
68
24
(continued on next page)

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Appendix A
Table A-2. Methane Conversion Factors by State for 2015 (percent) (continued)
State
Dairy
Swine
Anaerobic
Lagoon
Tank/Pond
Anaerobic
Lagoon
Tank/Pond and
Deep Pit
North Carolina
76
35
78
41
North Dakota
67
23
67
23
Ohio
71
27
72
28
Oklahoma
78
40
77
37
Oregon
65
23
65
23
Pennsylvania
71
27
72
28
Rhode Island
71
26
71
26
South Carolina
78
43
79
44
South Dakota
69
25
70
25
Tennessee
76
34
76
36
Texas
78
42
78
45
Utah
66
22
69
25
Vermont
64
21
64
21
Virginia
73
30
76
33
Washington
65
23
67
24
West Virginia
72
28
72
28
Wisconsin
67
23
68
24
Wyoming
62
20
63
21

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5. Estimating Potential Electricity Yield from Methane Production
This report's estimates of the biogas production potential from dairy cow and swine manure are based on
the following approach:
•	Methane production. Based on previously observed values9-10 and expert judgment, the production of
methane from swine manure is estimated to be 6.6 ft3 of methane per pound of total VS added. For dairy
manure, the production of methane is assumed to be 3.84 ft3 of methane per pound of total VS added to
the system, based on the value used in EPA's greenhouse gas inventory.
•	Heating value of methane. To calculate the energy content of methane produced in swine and dairy
anaerobic digesters for this report, EPA used the lower heating value of methane, 923 Btu per ft3 methane.
•	Engine and online efficiency. Electrical output from a typical generator was estimated at 85 kWh per
1,000 ft3 of methane. This factor is based on a thermal conversion efficiency of methane to electricity of
35 percent, and an online operating rate of 90 percent (to account for downtime due to maintenance and
repair).
•	Heating value ratio. The heating value ratio is 0.9638 ft3 of natural gas to 1 ft3 of methane, which assumes
higher heating values of 1,012 Btu/ft3 for methane and 1,050 Btu/ft3 for natural gas.
•	Homes heated. The total methane production was multiplied by the heating value ratio of natural gas
to methane to determine the volume of RNG available for use in residential heating applications. It was
assumed the average household using natural gas for heat consumes 66,000 ft3 natural gas per year.11
•	Refuse trucks fueled. AgSTAR assumed a methane to CNG conversion factor of 0.0451 lb CNG/ft3 CH4,
based on higher heating values of 1,012 Btu/ft3 for methane and 22,453 Btu/lb for CNG.12
AgSTAR also assumed a gallon gasoline equivalent (GGE) factor of 5.66 lb CNG/GGE13 and assumed an
average annual fuel usage of 9.877 GGE per refuse truck per year.14
9	Martin, J.H., Jr. 2002. A Comparison of the Performance of Three Swine Waste Stabilization Systems. Final report submitted to the U.S.
Environmental Protection Agency AgSTAR Program by Eastern Research Group, Inc., Boston, Massachusetts.
10	Martin, J.H., Jr. 2003. An Assessment of the Performance of the Colorado Pork, LLC, Anaerobic Digestion and Biogas Utilization
System. Final report submitted to the U.S. Environmental Protection Agency AgSTAR Program by Eastern Research Group, Inc., Boston,
Massachusetts.
11	U.S. DOE EIA. 2013.2009 Residential Energy Consumption Suivey: Consumption & Expenditures Tables. Table CE2.1.
12	U.S. DOE. 2014. Alternative Fuels Data Center—Fuel Properties Comparison.
Available at https://www.afdc.energy.gov/fuels/fuel_comparison_chart.pdf.
13	Ibid.
14	U.S. DOE. 2015. Alternative Fuels Data Center Maps and Data —Average Annual Fuel Use of Major Vehicle Categories.
Available at https://www.afdc.energy.gov/data/10308.

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A-8

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Appendix B
Profiles of Swine and
Dairy States with Biogas
Energy Recovery Potential
The data and analysis shown in Appendix B are from EPA AgSTAR's 2011 report
Market Opportunities for Biogas Recovery Systems at U.S. Livestock Facilities.
EPA believes that agricultural practices have not changed significantly in these
states since the previous publication..

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State Profile: Iowa
Swine
Market Opportunities to Generate
Electricity with Anaerobic Digestion (2007)
Total number of swine operations
8,330
Total number of mature swine
(000 head)
19,295
Number of feasible swine operations1
1,997
Number of mature swine at feasible
operations (000 head)
13,824
Methane emission reduction
potential (000 tons/year)
301
Methane production potential
(billion ft3/year)
21.5
Electricity generation potential
(000 MWh/yr)
1,829
Swine Farm Size
1 Anaerobic digestion was considered feasible at all existing operations
with flush, pit recharge, or pull-plug pit systems with at least 2,000
swine and at deep pit systems with at least 5,000 swine.
Swine Population by County
¦¦¦!¦¦¦¦!
HiihipHij
««¦¦¦¦¦¦]
r< 2,000 head 2,000-5,000 head | > 5,000 head
Swine Manure Managed in Each Waste
Management System
53%
Anaerobic
Lagoon
Pasture
Storage

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State Profile: North Carolina
Swine
Market Opportunities to Generate
Electricity with Anaerobic Digestion (2007)
Total number of swine operations
2,836
Total number of mature swine
(000 head)
10,134
Number of feasible swine operations1
939
Number of mature swine at feasible
operations (000 head)
8,471
Methane emission reduction
potential (000 tons/year)
203
Methane production potential
(billion ft3/year)
13.2
Electricity generation potential
(000 MWh/yr)
1,121
Swine Farm Size
1 Anaerobic digestion was considered feasible at all existing operations
with flush, pit recharge, or pull-plug pit systems with at least 2,000
swine and at deep pit systems with at least 5,000 swine.
2,000-4,999
head
I
1-1,999
74%
>5,000 head
Swine Population by County
Swine Manure Managed in Each Waste
Management System
32%
Deep Pit
57%
Anaerobic
Lagoon
Pasture
Storage
B-3

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State Profile: Minnesota
Swine
Market Opportunities to Generate
Electricity with Anaerobic Digestion (2007)
Total number of swine operations
4,382
Total number of mature swine
(000 head)
7,652
Number of feasible swine operations1
707
Number of mature swine at feasible
operations (000 head)
4,692
Methane emission reduction
potential (000 tons/year)
63
Methane production potential
(billion ft3/year)
7.3
Electricity generation potential
(000 MWh/yr)
621
Swine Farm Size
1 Anaerobic digestion was considered feasible at all existing operations
with flush, pit recharge, or pull-plug pit systems with at least 2,000
swine and at deep pit systems with at least 5,000 swine.
Swine Population by County
B-4
Swine Manure Managed in Each Waste
Management System
Anaerobic
Lagoon
Solid Storage Pasture

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State Profile: Illinois
Swine
Market Opportunities to Generate
Electricity with Anaerobic Digestion (2007)
Total number of swine operations
2,864
Total number of mature swine
(000 head)
4,299
Number of feasible swine operations1
350
Number of mature swine at feasible
operations (000 head)
2,746
Methane emission reduction
potential (000 tons/year)
39
Methane production potential
(billion ft3/year)
4.3
Electricity generation potential
(000 MWh/yr)
363
Swine Farm Size
1 Anaerobic digestion was considered feasible at all existing operations
with flush, pit recharge, or pull-plug pit systems with at least 2,000
swine and at deep pit systems with at least 5,000 swine.
2,000-4,999
head
1-1,999
head
>5.000 head
Swine Population by County
Swine Manure Managed in Each Waste
Management System
Anaerobic
Lagoon
Solid Storage
Pasture

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State Profile: Missouri
Swine
Market Opportunities to Generate
Electricity with Anaerobic Digestion (2007)
Total number of swine operations
2,999
Total number of mature swine
(000 head)
3,101
Number of feasible swine operations1
154
Number of mature swine at feasible
operations (000 head)
2,277
Methane emission reduction
potential (000 tons/year)
34
Methane production potential
(billion ft3/year)
3.5
Electricity generation potential
(000 MWh/yr)
301
Swine Farm Size
1 Anaerobic digestion was considered feasible at all existing operations
with flush, pit recharge, or pull-plug pit systems with at least 2,000
swine and at deep pit systems with at least 5,000 swine.
Swine Population by County
B-6
Swine Manure Managed in Each Waste
Management System
Anaerobic
^Lagoon
Solid Storage pasture

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State Profile: Indiana
Market Opportunities to Generate
Electricity with Anaerobic Digestion (2007)
Total number of swine operations
3,420
Total number of mature swine
(000 head)
3,669
Number of feasible swine operations1
296
Number of mature swine at feasible
operations (000 head)
2,238
Methane emission reduction
potential (000 tons/year)
31
Methane production potential
(billion ft3/year)
3.5
Electricity generation potential
(000 MWh/yr)
296
1 Anaerobic digestion was considered feasible at all existing operations
with flush, pit recharge, or pull-plug pit systems with at least 2,000
swine and at deep pit systems with at least 5,000 swine.
Swine
Swine Farm Size
Swine Population by County
Swine Manure Managed in Each Waste
Management System
Anaerobic
Lagoon
Solid Storage Pasture

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State Profile: Oklahoma
Swine
Market Opportunities to Generate
Electricity with Anaerobic Digestion (2007)
Total number of swine operations
2,702
Total number of mature swine
(000 head)
2,398
Number of feasible swine operations1
56
Number of mature swine at feasible
operations (000 head)
2,207
Methane emission reduction
potential (000 tons/year)
51
Methane production potential
(billion ft3/year)
3.4
Electricity generation potential
(000 MWh/yr)
292
1 Anaerobic digestion was considered feasible at all existing operations
with flush, pit recharge, or pull-plug pit systems with at least 2,000
swine and at deep pit systems with at least 5,000 swine.
Swine Farm Size
94%
>5,000 head
12,000-4,999
head
-3%
1-1,999
head
Swine Population by County
< 2,000 head 2,000-5,000 head | > 5,000 head
Swine Manure Managed in Each Waste
Management System
3
Deep Pit
58%
Anaerobic
Lagoon
Pasture
4%
Solid
0cyo Storage
Liquid/
Slurry

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State Profile: Nebraska
Swine
Market Opportunities to Generate
Electricity with Anaerobic Digestion (2007)
Total number of swine operations
2,213
Total number of mature swine
(000 head)
3,269
Number of feasible swine operations1
177
Number of mature swine at feasible
operations (000 head)
2,052
Methane emission reduction
potential (000 tons/year)
27
Methane production potential
(billion ft3/year)
3.2
Electricity generation potential
(000 MWh/yr)
272
1 Anaerobic digestion was considered feasible at all existing operations
with flush, pit recharge, or pull-plug pit systems with at least 2,000
swine and at deep pit systems with at least 5,000 swine.
Swine Farm Size
2,000-4,999
head
1-1,999
head
>5.000 head
Swine Population by County
Ijr rtr.ii
m mnmm ¦¦!¦¦¦*
3 iah iriii
<2,000 head 2,000-5,000 head | > 5,000 head
Swine Manure Managed in Each Waste
Management System
14%
Anaerobic
Lagoon
Solid Storage
Pasture

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State Profile: Kansas
Swine
Market Opportunities to Generate
Electricity with Anaerobic Digestion (2007)
Total number of swine operations
1,454
Total number of mature swine
(000 head)
1,885
Number of feasible swine operations1
80
Number of mature swine at feasible
operations (000 head)
1,508
Methane emission reduction
potential (000 tons/year)
22
Methane production potential
(billion ft3/year)
2.3
Electricity generation potential
(000 MWh/yr)
199
Swine Farm Size
1 Anaerobic digestion was considered feasible at all existing operations
with flush, pit recharge, or pull-plug pit systems with at least 2,000
swine and at deep pit systems with at least 5,000 swine.
Swine Population by County
B-10
Swine Manure Managed in Each Waste
Management System
Anaerobic
yLagoon
Solid Storage pasture

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State Profile: Texas
Swine
Market Opportunities to Generate
Electricity with Anaerobic Digestion (2007)
Total number of swine operations
4,471
Total number of mature swine
(000 head)
1,156
Number of feasible swine operations1
10
Number of mature swine at feasible
operations (000 head)
1,057
Methane emission reduction
potential (000 tons/year)
25
Methane production potential
(billion ft3/year)
1.6
Electricity generation potential
(000 MWh/yr)
140
1 Anaerobic digestion was considered feasible at all existing operations
with flush, pit recharge, or pull-plug pit systems with at least 2,000
swine and at deep pit systems with at least 5,000 swine.
Swine Farm Size
94%
>5.000 head
r-1%
I 2,000-4,999
I head
-5%
1-1,999
head
Swine Population by County
Swine Manure Managed in Each Waste
Management System
57%
Anaerobic
Lagoon
-3%
Pasture
J/o
\ Solid
6% Storage
Liquid/
Slurry

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State Profile: California
Dairy
Market Opportunities to Generate
Electricity with Anaerobic Digestion (2007)
Total number of dairy operations
2,165
Total number of mature dairy cows
(000 head)
1,841
Number of feasible dairy cow operations1
889
Number of mature dairy cows at feasible
operations (000 head)
1,352
Methane emission reduction
potential (000 tons/year)
341
Methane production potential
(billion ft3/year)
27.9
Electricity generation potential
(000 MWh/yr)
2,375
1 Anaerobic digestion was considered feasible at all existing operations with
flushed or scraped freestall barns and drylots with at least 500 dairy cows.
Dairy Farm Size
8%
200-499
head
1%
1-199
head
91%
>500 head
Dairy Population by County
> 1,000 head
Dairy Manure Managed in Each Waste
Management System
< 500 head
500-1,000 head
1%
Pasture
Storage

-------
Dairy
Dairy Farm Size
6%
4%
1-199
head
90%
>500 head
State Profile: Idaho
Market Opportunities to Generate
Electricity with Anaerobic Digestion (2007)
Total number of dairy operations
811
Total number of mature dairy cows
(000 head)
536
Number of feasible dairy cow operations1
203
Number of mature dairy cows at feasible
operations (000 head)
430
Methane emission reduction
potential (000 tons/year)
99
Methane production potential
(billion ft3/year)
8.9
Electricity generation potential
(000 MWh/yr)
762
1 Anaerobic digestion was considered feasible at all existing operations with
flushed or scraped freestall barns and drylots with at least 500 dairy cows.
Dairy Population by County
P ^
¦ ¦
Dairy Manure Managed in Each Waste
Management System
~
< 500 head
500-1,000 head
> 1,000 head
Pasture
Deep Pit
Daily Spread
Storage
65%
Anaerobic
Lagoon

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State Profile: New Mexico
Dairy
Market Opportunities to Generate
Electricity with Anaerobic Digestion (2007)
Total number of dairy operations
272
Total number of mature dairy cows
(000 head)
326
Number of feasible dairy cow operations1
110
Number of mature dairy cows at feasible
operations (000 head)
261
Methane emission reduction
potential (000 tons/year)
64
Methane production potential
(billion ft3/year)
5.3
Electricity generation potential
(000 MWh/yr)
455
Dairy Farm Size
1 Anaerobic digestion was considered feasible at all existing operations with
flushed or scraped freestall barns and drylots with at least 500 dairy cows.
200-499
head
99%
>500 head
1-199
head
Dairy Population by County

~
< 500 head
500-1,000 head
> 1,000 head
Dairy Manure Managed in Each Waste
Management System
Storage

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Dairy
Dairy Farm Size
State Profile: Texas
Market Opportunities to Generate
Electricity with Anaerobic Digestion (2007)
Total number of dairy operations
1,293
Total number of mature dairy cows
(000 head)
404
Number of feasible dairy cow operations1
155
Number of mature dairy cows at feasible
operations (000 head)
266
Methane emission reduction
potential (000 tons/year)
66
Methane production potential
(billion ft3/year)
5.0
Electricity generation potential
(000 MWh/yr)
429
1 Anaerobic digestion was considered feasible at all existing operations with
flushed or scraped freestall barns and drylots with at least 500 dairy cows.
Dairy Population by County
Dairy Manure Managed in Each Waste
Management System
Daily Spread
Deep Pit
11%
Solid
Storage
58%
Anaerobic
Lagoon
B-15

-------
State Profile: Wisconsin
Dairy
Market Opportunities to Generate
Electricity with Anaerobic Digestion (2007)
Total number of dairy operations
14,158
Total number of mature dairy cows
(000 head)
1,249
Number of feasible dairy cow operations1
251
Number of mature dairy cows at feasible
operations (000 head)
238
Methane emission reduction
potential (000 tons/year)
41
Methane production potential
(billion ft3/year)
4.5
Electricity generation potential
(000 MWh/yr)
386
Dairy Farm Size
1 Anaerobic digestion was considered feasible at all existing operations with
flushed or scraped freestall barns and drylots with at least 500 dairy cows.
200-499
head
Dairy Population by County
B-16
Dairy Manure Managed in Each Waste
Management System
3%
Deep Pit
>>l
f 12% ^
Daily Spread
Anaerobic
Lagoon
Pasture
35%
Solid
Storage

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State Profile: Washington
Dairy
Market Opportunities to Generate
Electricity with Anaerobic Digestion (2007)
Total number of dairy operations
817
Total number of mature dairy cows
(000 head)
243
Number of feasible dairy cow operations1
125
Number of mature dairy cows at feasible
operations (000 head)
163
Methane emission reduction
potential (000 tons/year)
35
Methane production potential
(billion ft3/year)
3.4
Electricity generation potential
(000 MWh/yr)
294
Dairy Farm Size
1 Anaerobic digestion was considered feasible at all existing operations with
flushed or scraped freestall barns and drylots with at least 500 dairy cows.
1-199
head
200-499
head
75%
>500 head
Dairy Population by County
~
< 500 head
500-1,000 head
> 1,000 head
Dairy Manure Managed in Each Waste
Management System
1%
17%
Pasture
51%
Anaerobic
Lagoon
10%
Solid
Storage

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State Profile: Arizona
Dairy
Market Opportunities to Generate
Electricity with Anaerobic Digestion (2007)
Total number of dairy operations
182
Total number of mature dairy cows
(000 head)
184
Number of feasible dairy cow operations1
54
Number of mature dairy cows at feasible
operations (000 head)
146
Methane emission reduction
potential (000 tons/year)
44
Methane production potential
(billion ft3/year)
3.1
Electricity generation potential
(000 MWh/yr)
263
Dairy Farm Size
1 Anaerobic digestion was considered feasible at all existing operations with
flushed or scraped freestall barns and drylots with at least 500 dairy cows.
Dairy Population by County
Dairy Manure Managed in Each Waste
Management System
< 500 head	500-1,000 head	1,000 head
Anaerobic
Lagoon

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State Profile: Michigan
Dairy
Market Opportunities to Generate
Electricity with Anaerobic Digestion (2007)
Total number of dairy operations
2,647
Total number of mature dairy cows
(000 head)
344
Number of feasible dairy cow operations1
107
Number of mature dairy cows at feasible
operations (000 head)
138
Methane emission reduction
potential (000 tons/year)
26
Methane production potential
(billion ft3/year)
2.9
Electricity generation potential
(000 MWh/yr)
246
Dairy Farm Size
1 Anaerobic digestion was considered feasible at all existing operations with
flushed or scraped freestall barns and drylots with at least 500 dairy cows.
Dairy Population by County

Dairy Manure Managed in Each Waste
Management System
< 500 head	500-1,000 head ^>1,000 head

Daily Spread
Deep Pit
28%
Anaerobic
Lagoon
23%
Solid
Storage

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State Profile: New York
Dairy
Market Opportunities to Generate
Electricity with Anaerobic Digestion (2007)
Total number of dairy operations
5,683
Total number of mature dairy cows
(000 head)
626
Number of feasible dairy cow operations1
111
Number of mature dairy cows at feasible
operations (000 head)
109
Methane emission reduction
potential (000 tons/year)
18
Methane production potential
(billion ft3/year)
2.1
Electricity generation potential
(000 MWh/yr)
177
Dairy Farm Size
1 Anaerobic digestion was considered feasible at all existing operations with
flushed or scraped freestall barns and drylots with at least 500 dairy cows.
Dairy Population by County
< 500 head	500-1,000 head J > 1,000 head
Dairy Manure Managed in Each Waste
Management System
2°/t
Deep Pit
>>,
Anaerobic
. Lagoon
45%
Daily Spread
17%
Solid
Storage
Pasture

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State Profile: Colorado
Dairy
Market Opportunities to Generate
Electricity with Anaerobic Digestion (2007)
Total number of dairy operations
449
Total number of mature dairy cows
(000 head)
127
Number of feasible dairy cow operations1
54
Number of mature dairy cows at feasible
operations (000 head)
97
Methane emission reduction
potential (000 tons/year)
22
Methane production potential
(billion ft3/year)
2.0
Electricity generation potential
(000 MWh/yr)
174
Dairy Farm Size
1 Anaerobic digestion was considered feasible at all existing operations with
flushed or scraped freestall barns and drylots with at least 500 dairy cows.
200-499
85%
>500 head
•5%
1-199
head
Dairy Population by County
< 500 head	500-1,000 head H>1<000 head
Dairy Manure Managed in Each Waste
Management System
Daily Spread

Deep Pit
Pasture
Storage
64%
Anaerobic
Lagoon

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B-22

-------