&EPA
United States
Environmental Protection
Agency
Office of Air and Radiation Winter 2006
Washington, DC 20460 www.epa.gov/agstar
AgSTAR Digest
Inside the Winter 2006 Issue
AgSTAR Digesters Continue Accelerating in the U.S. Livestock Market 1
Dairies Profit from Greenhouse Gas Market 13
Hilarides Dairy Demonstrates Energy and Environmental Success 14
AgSTAR Digesters Continue Accelerating in the U.S.
Livestock Market
Farm demand and use of anaerobic
digesters for livestock manure
stabilization and energy production
have shown continued acceleration
since the last edition of the Digest.
Over the past two years, the number
of digesters has more than doubled
due to a diverse array of national,
state, and local activities to market,
cost share, and reliably develop
operational systems. (See Figure 1.)
Digester Technology Profiles
Grow
The success rate of installed systems
has been extremely high and is
currently led by a growing number of
engineering and equipment supply
companies. European-style systems
are also emerging in the U.S. market.
The majority of commercially
operating systems are conventional
plug flow, vertically mixed plug flow,
and complete mix reactors (including
covered lagoons) operating at
mesophilic temperatures, and covered
lagoons operating at ambient
temperature. (See Figure 2.) Although
the majority of systems are still farm
owned and operated using only
livestock manure, innovative
approaches are also emerging. These
include commingling of high strength
organic wastes to increase gas
production per unit volume of reactor,
third party owned/ operated
centralized or regional plants, and
direct gas sales to utilities that then
produce power for their service
territory. The majority of these
systems are found in the dairy
industry in the Midwest, West, and
Northeast. Pig industry digester
clusters are found in Texas and Utah.
These systems are estimated to
produce 248 million kilowatt-hours
annually. (See Figure 3.)
Figure 1. Trends in methane reduction and equivalent kilowatt-hours attributed per year to anaerobic digesters - 2000
through 2006.
60,000 r -, 250,000,000
Methane Reduction kWh/yr Equivalent
30,000
25,000
° 20,000
_o
1.
.1 15,000
"I
cc
ra 10,000
|
5,000
-
-
-
-
-
-
-
140,000,000
120,000,000
100,000,000
80,000,000 "1
111
60,000X100 §
40,000/100
20,000/100
n
2000 2001
2002
2003 2004 2005
2006
-------
2 AgSTAR Digest Winter 2006
Figure 2. Operating anaerobic digesters by technology*.
2-Stage Mix
5
Mesophilic
Covered
Lagoon
13
Ambient
Temperature
Covered Lagoon
1
Attached
Media
Includes digesters in start-up and construction stage.
About the AgSTAR Program
The AgSTAR Program is a voluntary effort jointly
sponsored by the U.S. Environmental Protection
Agency (EPA), the U.S. Department of Agriculture,
and the U.S. Department of Energy. The program
encourages the use of methane recovery (biogas)
technologies at confined animal feeding operations
(CAFOs) that manage manure as liquids or slurries.
These technologies reduce greenhouse gas
(methane) concentrations while achieving other
environmental benefits. For additional information
about the AgSTAR program, please visit our Web
site atvvww.epa.gov/agstar.
'
Incentives for Growth Emerge
A number of elements have emerged
to increase the deployment rate of
these digester systems. For example,
grants awarded under Section 9006,
Renewable Energy and Energy
Efficiency, of the 2002 Farm Bill have
been the primary method for farms to
partially fund installation of
commercially proven livestock waste
digestion technologies. Since 2003, a
total of about $25 million has been
awarded for anaerobic digestion of
livestock manures. Annual funding
levels for anaerobic digesters are
shown in Figure 4. State programs
have also provided funding
opportunities such as the California
Energy Commission (see page 14 for a
project success story at Hilarides
Dairy), the Pennsylvania Harvest
Program, the Wisconsin
Focus on Renewable
Energy Program, and
the New York State
Energy Research and
Development Authority.
Some of these programs
are still active and some
have now shifted to
evaluating energy,
economic, and
environmental performance of
operational systems. The AgSTAR
program has coordinated with these
agencies in a number of areas in
developing these programs and
providing technical assistance.
Standardized Protocol
Additionally, the AgSTAR program
and the Association of State Energy
Figure 3. National distribution of anaerobic digester energy production -
operating and planned digesters * (Energy production in 1,000
kWh/yr).
Figure 4. Annual funding for anaerobic digesters.
Research and Technology Transfer
Institutions are jointly developing a
protocol to provide a standardized
method for conducting digester
performance assessments. The U.S.
Department of Agriculture, U.S.
Environmental Protection Agency, a
number of university biological
engineering departments, and
digester system designers are
involved in the development of this
protocol. The protocol will be released
at the National AgSTAR Conference
April 25-26, 2006, in Madison,
Wisconsin, and posted on the
AgSTAR Web site. This protocol has
been used to evaluate a number of
digesters and other waste
management processes. Reports can
be found at the AgSTAR Web site.
State energy legislation has played a
significant role in restructuring the
methods by which farms are paid for
the renewable energy they produce
from digester systems. This legislation
has focused on net metering as a way
of providing a fair market for biogas-
generated electricity. Net metering
has reduced a key market barrier
imposed by conventional utility rate
-------
AgSTAR Digest Winter 2006 3
structures on grid-interconnected,
independent power producers that
has impeded the financial
performance of distributed generation
from digester technology. This has
resulted in the lack of private
financing for these systems.
Currently, net metering legislation has
been enacted in New York and
Pennsylvania and is under
development in California and
Maryland. Various electric utilities
have also created green power
programs that are favorable for
renewable base load generation
technologies such as anaerobic
digesters. For example, We Energies,
Wisconsin's largest utility, received
authorization from the Public Service
Commission of Wisconsin (PSCW) to
significantly expand its renewable
energy programs. Among these
programs, the PSCW approved a new
"Biogas Buy-Back Rate," which pays
8.0T/kWh for "on-peak" energy and
4.92 reduced
annually. (See page 13.)
Market Opportunities Evaluated
Indeed, these are exciting times for
anaerobic digesters and farm-based
power production, as well as for other
renewable energy resources. Rising
energy costs, reliance on imported
fossil fuels, and energy security
suggest that expanded efforts are
needed to realize the full potential of
domestic renewable energy resources.
A recently completed AgSTAR
analysis and upcoming report
Market Opportunities for Biogas
Recovery Systems at Animal Feeding
1
Market Opportunities for
Biogas Recovery Systems
A Guide to Identifying Candidates
for Gn-Farm and Centralized Systems
SB*
Operations evaluates the anaerobic
digestion market, its energy
production potential, greenhouse gas
reduction opportunities, and other
environmental benefits that are
available from domestic livestock
manure resources. As shown in Table
1 (based on farm scale, waste
handling method, and installed
digester cost) about 7,000 farms could
use anaerobic digestion cost-
effectively and provide about 700
megawatts (MW) of distributed
energy to rural areas while reducing
greenhouse gas by about 1.3 million
metric tons (MMT) of methane (CELi),
the equivalent of 30 MMT of carbon
dioxide (CO2). This would be
equivalent to removing 4.7 million
cars from our highways.
Table 1. Market Opportunities for Biogas Recovery Systems at Animal Feeding Operations (February 3, 2006)
Animal
Sector
Pigs
Candidate
Farms
4,300
363
MWh/year
3,184,000
CH4 Emission
Reductions
(tons/year)
771,000
Dairy
2,600
359
3,148,000
572,000
Total
6,900
722
6,332,000
1,343,000
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4 AgSTAR Digest Winter 2006
Digester Costs
The cost of anaerobic digestion for
biogas production and utilization will
vary with system type and size, type
of livestock operation, and site-
specific conditions. To provide some
preliminary guidance with respect to
expected cost, the AgSTAR program
has performed a series of analyses to
determine the relationships between
capital cost and size for different
types of operating digesters for dairy
and swine manures with internal
combustion engine-generator sets.
Results of these analyses in
combination with other information
were used to develop the cost
algorithms used in FarmWare,
Version 3.0. The graphics below
provide a snap shot of these
relationships. (See Figures 5, 6, and
7.)
$1,400,000-
$1,200,000 -
» $1,000,000 -
(/)
in $800,000 -
0
ra
£ r * I
^
0 1000 2000 3000 4000 5000 6000
Number of Animals
$350,000.00 -
8
_. . _ . y=63.863x+ 35990
Covered Lagoon Digester -Swine 2
R 0.9792
^*
^^
^^
^^
* -^^^ I
*
$0.00 -I 1 1 1 1 1 1 1 1 I
0 500 1000 1500 2000 2500 3000 3500 4000 4500
Head
Figure 5. Covered lagoon digester cost - relationship to
dairy herd size.
Figure 6. Analysis of covered lagoon digester system
costs (swine).
o ' '
o
Plug-Flow/Flexible Cover/Dairy y = ^^f8'9
.s^
^s^
.s^
* *-^^^^
» ^^
^'
s(* »
J 1000 2000 3000 4000 5000 6000 7000 80
No of Cows
36
00
Figure 7. Plug flow/flexible cover digester system cost
relationship to dairy herd size.
Digester Systems Operating
Tables 2 and 3 contain a listing of
livestock-based anaerobic digestion
system operating or in startup or
construction mode in the United
States. In addition, there are
approximately 80 systems in the
planning stages in the United States.
These systems represent an additional
200,000 dairy and swine plus 1.5
million layers. The electrical output of
these proposed generators is
estimated to be more than 400 million
kWh/yr. These operations are
estimated to reduce methane
emissions more than 26,000 metric
tons per year, which represents an
annual reduction in equivalent
greenhouse gas emissions of more
than 546,000 metric tons, expressed as
carbon dioxide. The predominant
digestion technology proposed is plug
flow, followed by complete mix and
heated and ambient temperature
covered lagoons. Because the number
of planned and operational systems
-------
AgSTAR Digest Winter 2006 5
are growing rapidly, there may be
additions, changes, and deletions as of
this posting, and this listing does not
contain the recently awarded 2005
Section 9006 anaerobic digester
grants. To the extent possible, this
listing provides the best quality data
available in the respective fields
reported. However, there may be
some inaccuracies. Maintaining data
quality is a key concern and becomes
more difficult to verify as systems go
on- or off-line, or initial plans change.
In this capacity, the AgSTAR program
will be launching a database, similar
to the one shown in Tables 2 and 3, on
the AgSTAR Web site. Digester
owner/ operators, developers,
extension personnel, and others will
be able to add, make changes, and
correct any data that may be
incorrectly reported or outdated. This
updating capability will be Web-
based, so that anyone wishing to
update or add information can do so
by e-mailing the database manager,
who will then verify the data
submission with the farm owner or
other appropriate party.
Table 2. Operating U.S. Digesters
i ~~,n n.~^t^r TW~« Year Animal Type/ Biogas End Operational Baseline
Location Digester Type Operatjona| population Use Output (kW) System
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
Mesophilic,
vertically
mixed, plug
flow, hard top,
concrete tank
Ambient
temperature
covered lagoon
Ambient
temperature
covered lagoon
Ambient
temperature
covered lagoon
Ambient
temperature
covered lagoon
Ambient
temperature
covered lagoon
Ambient
temperature
covered lagoon
Plug Flow
Plug Flow
Mesophilic,
flexible top,
plug flow,
concrete tank
Mesophilic,
flexible top,
plug flow,
concrete tank
Ambient
temperature
covered lagoon
2004 Dairy; 3,510
2005 Dairy; 237
2005 Dairy; 175
2005 Dairy; 5081
N/A Dairy; 5,081
2005 Dairy; 1050
2005 Dairy; 6000
2005 Dairy; 4700
2005 Dairy; N/A
2003 Dairy; 1 ,500
1982 Dairy; 400
2005 Dairy; 1258
Electricity
Electricity
Electricity
Electricity
Electricity
Electricity
Electricity
Electricity
Electricity
Electricity
Electricity; hot
water
Electricity
144
900
27
270
270
108
225
506
1350
234
36
135
Lagoon
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Methane Eq±a'ent
~ SSS
(MT/year) (MT/y|)
984 20,664
31 651
23 483
665 13,965
665 13,965
137 2,877
785 16,485
615 12,915
N/A N/A
196 4,116
52 1 ,092
165 3,465
1 Equivalent greenhouse gas emission reduction potential expressed as carbon dioxide. This value assumes methane has
approximately 21 times the heat trapping capacity of carbon dioxide.
-------
6 AgSTAR Digest Winter 2006
i ~~,n n.~^t^r TW~« Year Animal Type/ Biogas End Operational Baseline
Location Digester Type Operatjona| population Use Output (kW) System
CA
CA
CA
CA
CA
CA
CO
CT
CT
FL
ID
IA
IA
IA
IA
IA
Mesophilic,
flexible top,
plug flow,
concrete tank
Mesophilic,
flexible top,
complete mix,
concrete tank
Mesophilic,
hard top, plug
flow, concrete
tank
Ambient
temperature
covered lagoon
Ambient
temperature
covered lagoon
Plug Flow
Mesophilic,
flexible top,
complete mix,
concrete tank
Mesophilic,
hard top,
complete mix,
above-ground
metal tank
Mesophilic,
flexible top,
plug flow,
concrete tank
Attached
media, hard
top,
aboveground
N/A
Ambient
temperature
covered lagoon
Mesophilic,
hard top, plug
flow, concrete
tank
Mesophilic,
hard top, plug
flow, concrete
tank
Mesophilic,
flexible top,
complete mix,
concrete tank
Mesophilic,
hard top, plug
flow, combined
phase,
concrete tank
2003
2001
2002
1982
2000
2005
1999
1997
1997
1999
N/A
1998
2002
2004
1998
N/A
Dairy; 1,900
Dairy; 5,000
Dairy; 7,000
Swine; 1,650
Dairy; 200
Dairy; 600
Swine; 5,000
Dairy; 600
Dairy; 200
Dairy; 250
Dairy; 3,000
Swine; 3,000
Dairy; 380
Dairy; 1,000
Swine; 5,000
Dairy; 700
Electricity
Electricity; hot
water
Electricity
Electricity; hot
air
N/A
Electricity
Electricity
Electricity
Hot water;
flare
Hot water;
flare
Electricity
Flare
Electricity;
heat
Electricity; hot
water
Electricity
Electricity
144
270
270
45
22
117
63
72
18
27
N/A
0
45
90
54
126
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Lagoon
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Lagoon
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Lagoon
Lagoon
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Lagoon
Liquid/Slurry
Storage
Methane E^fnt
Emission Emjssjon
RMTA±? Reduction1
(MT/year)
249 5,229
654 13,734
916 19,236
58 1,218
26 546
78 1 ,638
157 3,297
53 1,113
18 378
46 966
287 6,027
76 1 ,596
34 714
88 1 ,848
166 3,486
62 1 ,302
-------
AgSTAR Digest Winter 2006 7
Location Digester Type Op<^onal £
IL
IL
IL
IN
MD
Ml
MN
MN
MS
NC
NC
NY
NY
NY
NY
Mesophilic,
heated lagoon,
combined
phase
Plug flow
Mesophilic,
flexible top,
plug flow,
combined
phase,
concrete tank
Mesophilic,
hard top, plug
flow, concrete
tank
Mesophilic,
hard top,
complete mix,
vertical pour,
concrete tank
Plug flow,
inground tank
Mesophilic,
flexible top,
plug flow,
combined
phase,
concrete tank
Plug flow
Ambient
temperature
covered lagoon
temperature
covered lagoon
Mesophilic,
lagoon, mix
digestive
Mesophilic,
flexible top,
concrete tank,
plug flow
Mesophilic,
hard top,
complete mix,
metal above
ground tank
Hard top
Mesophilic,
flexible top,
plug flow,
concrete tank
1998 Swine; 8,300
2005 Dairy; 1,1 00
2002 Dairy; 1 ,400
2002 Dairy; 3,500
1994 Dairy; 120
1981 Dairy; 720
1999 Dairy; 1,000
N/A Dairy; 3000
1998 Swine; 145
1997 Swine; 4,000
2003 Swine; 10,000
1998 Dairy; 550
1985 Dairy; 270
N/A Dairy; N/A
2001 Dairy; 850
Methane
Biogas End Operational Baseline Emission
Use Output (kW) System Reduction
(MT/year)
Hot water;
flare
Electricity
Electricity
Electricity
Flare
Electricity
Electricity; hot
water
Electricity
Flare
Electricity; hot
Electricity
Electricity
Cogeneration
N/A
Hot water
36
126
162
360
14
0
99
N/A
4
108
135
117
58
N/A
68
Lagoon 285
Liquid/Slurry ...
Storage
Liquid/Slurry ...
Storage
Liquid/Slurry _._
Storage ^
Liquid/Slurry .
Storage
Liquid/Slurry
Storage
Liquid/Slurry .
Storage
Liquid/Slurry
Storage
Lagoon 5
Lagoon 140
Lagoon 350
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage N/H
Liquid/Slurry
Storage
Equivalent
GHG
Emission
Reduction1
(MT/yr)
5,985
2,331
2,961
7,203
252
1,197
1,701
5,082
105
2,940
7,350
924
462
N/A
1,428
-------
8 AgSTAR Digest Winter 2006
Location Digester Type
NY
NY
NY
NY
OR
OR
OR
PA
PA
PA
PA
PA
PA
PA
TX
Mesophilic,
flexible top,
complete mix,
concrete
inground tank
Plug flow
Mesophilic,
hard top, plug
flow, concrete
inground tank
Mesophilic,
hard top, plug
flow, concrete
tank
Mesophilic,
hard top,
complete mix,
above ground
Mesophilic,
flexible top,
plug flow,
concrete tank
Mesophilic,
flexible top,
plug flow,
concrete tank
Mesophilic,
flexible cover
tank, plug flow,
complete mix,
slurry loop
Mesophilic,
hardtop,
complete mix,
slurry loop,
concrete tanks
N/A
Mesophilic,
hard top, plug
flow, complete
mix, slurry loop,
concrete tank
Mesophilic,
hard top, plug
flow, complete
mix, slurry loop,
concrete tank
N/A
Mesophilic,
flexible top,
plug flow,
complete mix,
concrete tank
Mesophilic,
plug flow, hard
and flexible
covers, lagoon
Year
Operational
2001
N/A
2003
N/A
2001
2003
2004
1983
1983
N/A
1979-1984
1983
2004
1985
1989
Animal Type/
Population
Dairy; 750
Dairy; 185
Dairy; 1,300
Dairy/swine;
2,080
Dairy; 325
Dairy; 2,000
Dairy/poultry;
2,000
Layer; 350,000
Layer; 75,000
Swine; 1,200
Dairy; 2,300
Dairy; 250
Swine; 4,400
Swine; 750
Dairy; 400
Methane
Biogas End Operational Baseline Emission
Use Output (kW) System Reduction
(MT/year)
Electricity; hot
water
Flare
Electricity
Electricity
Electricity
Electricity
Electricity
Electricity; hot
Electricity
Electricity
Electricity; hot
water
Electricity
Electricity
Electricity; hot
Electricity
122
0
117
117
32
225
270
135
58
90
225
22
117
180
54
Liquid/Slurry _
Storage
Liquid/Slurry 15
Storage
Liquid/Slurry
Storage
Liquid/Slurry 1R7
Storage lo'
Liquid/Slurry
Storage
Liquid/Slurry .,
Storage lo°
Liquid/Slurry ._
Storage 1BJ
N/A 263
Liquid/Slurry
Storage
Lagoon 40
Liquid/Slurry
Storage ^ b
Liquid/Slurry .,-
Storage
Lagoon 148
Lagoon 25
Liquid/Slurry
Storage
Equivalent
GHG
Emission
Reduction1
(MT/yr)
1,260
315
2,184
3,507
630
3,843
3,843
5,523
1,176
840
4,515
315
3,108
525
1,197
-------
AgSTAR Digest Winter 2006 9
Location
TX
TX
UT
VA
VT
WA
Wl
Wl
Wl
Wl
Wl
Wl
Wl
Wl
Digester Type
Mesophilic,
mixed covered
lagoon
Mesophilic,
mixed covered
lagoon
Mesophilic
covered lagoon
Ambient
temperature
covered lagoon
Mesophilic,
flexible top,
plug flow,
concrete tank
Plug Flow
Mesophilic,
hard cover,
modified plug
flow, concrete
tank
Mesophilic,
flexible cover,
plug flow,
concrete tank
Mesophilic,
hard cover,
modified plug
flow, concrete
tank
Mesophilic,
hard top,
modified plug
flow, concrete
tank
Mesophilic,
hard top,
modified plug
flow, concrete
tank
Mesophilic,
hard top,
modified plug
flow, concrete
tank
Mesophilic,
hard top,
modified plug
flow, concrete
tank
Mesophilic,
flexible top,
complete mix,
concrete tank
Year
Operational
2003
2003
2005
1984
1982
2005
2001-2
2001-2
2001
2004
1998
1999
2001
2004
Animal Type/
Population
Swine; 108,000
Swine; 10,000
Swine; 144,000
Swine; 3,000
Dairy; 340
Dairy; 1,500
Dairy; 730
Dairy; 1,200
Dairy; 2,400
Dairy; 3,000
Dairy; 1,100
Dairy; 1,600
Dairy; 875
Dairy; 1,350
Biogas End
Use
Electricity
Electricity
N/A
Electricity
Electricity; hot
water; steam
Electricity
Electricity;
heat
Electricity;
heat
Electricity;
heat
Electricity;
heat
Heat
Heat
Electricity;
heat
Electricity;
heat
Operational
Output (kW)
1,800
144
N/A
0
76
259
200
140
375
700
N/A
N/A
135
350
Baseline
System
Lagoon
Lagoon
Lagoon
Lagoon
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Methane E^fnt
Emission Emjssjon
SESTrt Reduction1
(MT/year) (MJ/yr)
3883 81 ,543
360 7,560
3750 78,750
41 861
24 504
418 8,778
107 2,247
176 3,696
351 7,371
439 9,219
161 3,381
234 4,914
128 2,688
197 4,137
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10 AgSTAR Digest Winter 2006
Location
Wl
Wl
Wl
Wl
Wl
Wl
Wl
Wl
WY
WY
Digester Type
Mesophilic,
hard top,
modified plug
flow, concrete
tank
Thermophilic
digestion, hard
top, complete
mix, steel tank
Thermophilic
digestion, hard
top, complete
mix, steel tank
Mesophilic,
hard top,
modified plug
flow, concrete
tank
Thermophilic
digestion, hard
top, complete
mix, steel tank
Mesophilic,
hard top,
complete mix,
stainless steel
tank
Mesophilic,
flexible top,
complete mix,
concrete tank
Complete mix
Mesophilic,
complete mix
Mesophilic,
complete mix
Year Animal Type/
Operational Population
2005 Dairy; 1,200
2005 Dairy; 1,000
2004 Dairy; 1,000
1988 Duck; 500,000
2005 Dairy; 1,300
2006 Dairy; 1,000
2006 Dairy; 2,500
2005 Dairy; 1 ,000
N/A Swine; 5,000
N/A Swine; 15,000
Biogas End
Use
Electricity;
heat
Electricity;
heat
Electricity,
heat
Electricity;
heat
Electricity;
heat
Electricity;
heat
Electricity;
heat
N/A
Electricity
Electricity
Operational Baseline
Output (kW) System
20Q Liquid/Slurry
Storage
Liquid/Slurry
//b Storage
77/- Liquid/Slurry
Storage
Liquid/Slurry
zuu Storage
77/- Liquid/Slurry
"° Storage
25Q Liquid/Slurry
Storage
-. Liquid/Slurry
buu Storage
99/- Liquid/Slurry
Storage
N/A Lagoon
N/A Lagoon
Methane E«uleni
Emission Emjssjon
SESTrt Reduction1
(MT/year) (MJ/yr)
176 3,696
146 3,066
146 3,066
603 12,663
190 3,990
146 3,066
366 7,686
79 1 ,659
10 210
458 9,618
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AgSTAR Digest Winter 2006 11
Table 3.
Location
IL
IN
NE
NY
NY
NY
NY
NY
PA
PA
PA
PA
VT
Wl
Wl
Wl
Wl
Wl
Wl
U.S. Digesters in Startup-Construction Stage
Digester Type
Plug flow
Plug flow
Complete mix
Complete mix
Plug flow
Plug flow
Plug flow
Complete mix
Plug flow
Plug flow
Plug flow
Plug flow
Two-stage mixed
Mesophilic, hard
top, modified plug
flow, concrete tank
Mesophilic, hard
top, modified plug
flow, concrete tank
Mesophilic, hard
top, modified plug
flow, concrete tank
Mesophilic, hard
top, modified plug
flow, concrete tank
Mesophilic, hard
top, modified plug
flow, concrete tank
Mesophilic, flexible
top, complete mix,
concrete tank
Animal
Type/Population
Dairy; 1 ,000
Dairy; 3,200
Swine; 6,000
Duck
Dairy; 170
Dairy; 700
Dairy
Dairy; 1 ,800
Dairy; 700
Dairy; 400
Dairy; 400
Dairy; 600
Dairy; 1 ,200
Dairy; 3,000
Dairy; 3,000
Dairy; 800
Dairy; 1 ,050
Dairy; 3,000
Dairy; 2,500
Biogas End
Use
Electricity
Electricity
Electricity
Electricity
Electricity
Electricity
Electricity
Electricity
Electricity
Electricity
Electricity
Electricity
Electricity;
flare;
cogeneration
Electricity,
heat
Electricity,
heat
Electricity,
heat
Electricity,
heat
Electricity,
heat
Electricity,
heat
Operational
Output (kW)
N/A
N/A
144
N/A
22
63
N/A
234
72
45
45
36
216
1,200
600
150
200
300
500
Baseline
System
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Lagoon
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Liquid/Slurry
Storage
Methane
Emission
Reduction
(MT/year)
101
314
82
N/A
14
56
N/A
144
65
37
37
56
254
230
230
62
80
230
191
Equivalent GHG
Emission
Reduction2
(MT/yr)
2,121
6,594
1,722
N/A
294
1,176
N/A
3,024
1,365
111
111
1,176
5,334
4,830
4,830
1,302
1,680
4,830
4,011
Equivalent greenhouse gas emission reduction potential expressed as carbon dioxide. This value assumes methane has
approximately 21 times the heat trapping capacity of carbon dioxide.
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12 AgSTAR Digest Winter 2006
So what are the potential GHG
benefits and how are they
calculated?
Similar data were reported in the last
edition of the Digest, and a number of
inquiries were submitted requesting
clarification on how methane
reduction values were calculated.
Recognizing that there is great
variability in methane emissions from
animal waste management systems, it
is necessary to establish an emission
profile for a specific waste
management system (see Table 4). To
represent this variability, Methane
Conversion Factors (MCFs) are used
in combination with Bo, the Ultimate
Methane Yield, and other key
parameters. For new farms where
there is no existing animal waste
management system, the state
requirement for the specific animal
specie, farm scale, and waste handling
method should be used.
Table 4. Livestock Manure Management Systems and Methane Emission Factors by Climate Type
Manure Management System
Climate
Cool
Temperature
Warm
Uncovered
Lagoon
90%
90%
90%
Liquid/Slurry
Storage
10%
35%
65%
Solid
Storage
1%
1.5%
2%
Dry Lot
1%
1.5%
5%
Pit less
than 1
Month
5%
18%
33%
Pit more
than 1
Month
10%
35%
65%
Daily
Spread
0.1%
0.5%
1%
Digester
10%
10%
10%
Other
1%
1%
1%
There are essentially two steps to this
process. The first step is to determine
a baseline emission profile. This
involves calculating annual methane
emissions from the existing animal
waste management system. The
second step is to calculate avoided
CC>2 emissions when the project uses
gas to generate electricity, recognizing
that the electric utility does not need
to combust fossil fuels to generate the
energy produced by the digester
system. The sum of step 1 and step 2
will determine the greenhouse gas
reductions achieved through the
project. Table 5 illustrates the method
and comparative reductions relative
to two baselines (a liquid manure
storage and a combined treatment and
storage lagoon) animal waste
management systems for 500 milk
cows.
Table 5. Comparison of Methane Emission Reductions for Two Example Systems
Factors
Manure Storage
Tank or Pond
Methane emission reductions
Conventional
Anaerobic Lagoon
Number of cows
500
500
Average live weight, Ib/cow
1,400
1,400
Total volatile solids (VS) excretion rate, lb/1,000 Ib live weight_day
8.5
8.5
B0,1 ft3/lb VS
3.84
3.84
MCF, decimal
0.292
0.707
Methane density, Ib/ft
0.041
0.041
Methane emissions, tons/yr
50
121
Methane emission reduction from biogas capture and utilization,4 ton/yr
50
121
Equivalent reduction in carbon dioxide emissions, tons/yr
1,048
2,538
Displaced emissions from utility electric generation
Methane production, ft3/yr @ 38.5 ft3/cow_day
7,026,250
7,026,250
Electricity generation potential, kWh/yr
467,838
467,838
Reduction in utility carbon dioxide emissions,7 tons/yr
526
526
Total greenhouse gas emission reduction as carbon dioxide, tons/yr
1,574
3,064
Bo = Maximum methane generation potential, m methane/kg VS.
U.S. average MCF for manure storage tanks and ponds, and conventional anaerobic lagoon.
Methane emissions = number of cows * average live weight * VS excretion rate * 1/1000 * B0* MCF * methane density * 365 days/yr *
ton/2000lb.
Biogas combustion destroys essentially 100% of baseline methane emissions.
Methane has approximately 21 times the heat trapping capacity of carbon dioxide.
Generation, kWh/yr = methane production * 1,010 Btu/ft3 of methane * kWh/3413 Btu * 0.25 (methane to electricity conversion efficiency)'
0.9 (on-line efficiency)
Assuming 2,249 Ib of carbon dioxide emitted per mWh generated from coal (Spath et al., 1999).
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AgSTAR Digest Winter 2006 13
Dairies Profit from Greenhouse Gas Market
Dairy farmer Darryl Vander Haak receives his first check
for carbon credits from Jim Jensen of Environmental
Credit Corp.
Environmental Credit Corp. (ECC), a
supplier of environmental credits to
global financial markets, delivered the
first payments to U.S. dairy farmers
for greenhouse gas reductions. Darryl
Vander Haak, a dairy farmer in
Lynden, WA, and Dennis
Haubenschild, from Princeton, MN,
received their first checks for
capturing methane from manure on
their farms using anaerobic digesters.
"It's one more
revenue stream that
helps us keep
producing milk for
our customers," said
Vander Haak.
Combined, the two
dairy farmers were
credited with
preventing the
release of over 720
tons of methane to
the atmosphere -
equivalent to more
than 13,000 metric
tons of carbon
dioxide. The "carbon
credits" produced by
these two projects are worth more
than $26,000.
ECC, a member of the Chicago
Climate Exchange (CCX), worked
closely with the farmers to monitor
and certify their methane emission
reductions, formally registering them
with the CCX in October. The CCX is
the world's first (and North America's
only) voluntary, legally binding rules-
based greenhouse gas emissions
allowance trading system. CCX
provides farmers the opportunity to
receive greenhouse gas credits for
environmentally friendly farming
practices such as methane combustion
and destruction from anaerobic
manure digestion. Farmers can then
sell these greenhouse gas credits
through the exchange to willing
buyers.
With about eight million dairy cows
in the U.S., potential revenues to the
dairy industry from carbon credits
could exceed tens of millions of
dollars annually as the greenhouse
gas market grows. Dozens of farmers
have already applied to enroll in
ECC's carbon credit program.
For farmers interested in ECC's
carbon credit program, Jim Jensen can
be contacted at: (814) 235-1623 or
jjensen@envcc.com. ECC's Web site is
at www.envcc.com.
Story courtesy of ECC.
The Methane to Markets Partnership is an international initiative whose purpose is to reduce global methane
emissions to enhance economic growth, promote energy security, improve the environment, and reduce greenhouse
emissions. The Partnership is a collaborative between developed countries, developing countries, and countries with
economies in transition - together with strong participation from the private sector. The Partnership was launched on
November 16, 2004, at a Ministerial meeting in Washington, D.C. where 14 countries signed into the partnership to
reduce emissions from the coal, natural gas, and landfill sector. The livestock sector was added during a November
2005 meeting in Buenos Aires, Argentina, and now is a formal subcommittee of the Partnership focused on reducing
emissions and other environmental impacts from livestock waste. For more info see the Web site at
www. methanetoma rkets. o rg.
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14 AgSTAR Digest Winter 2006
Hilarides Dairy Demonstrates Energy and
Environmental Success
A.J. Yates and Rob Hilarides at a Hilarides Dairy Open
House.
The Hilarides Dairy in Lindsay,
Tulare County, California, recently
displayed its methane gas-powered
generators to nearly 100 visitors,
giving them a glimpse of how dairy
cow manure is powering their
operations while benefiting the
environment. CDFA Undersecretary
A.J. Yates was among the many
officials on hand and praised owner
Rob Hilarides for "turning a waste
product into an energy product."
Hilarides has
doubled its original
generating capacity to
500 kilowatts, and
now four generators
provide
approximately 90% of
the dairy's electrical
power. The digester
uses manure from the
nearly 6,000 dairy
heifers and steers at
the Sierra Cattle Co.
run by Hilarides. In
addition to the
electricity generated,
it cuts down on odor,
captures methane gas
before it reaches the
atmosphere, and helps reduce the
strain on the California power grid.
Michael Marsh, CEO of Western
United Dairymen, noted that dairy
producers are benefiting from a
WUD-sponsored law that extends net
metering to December 31, 2009.
Under net metering, electricity
generated by biogas can be credited
against electricity consumed.
However, Marsh and others were
quick to point out that a greater
incentive for more digester projects
would be "having the dairy producer
get paid for the power he's
generating." He pointed out that a
mandate that utilities purchase excess
power would be a greater economic
incentive for dairy producers when
weighing the costs of building a
methane-powered generator.
About half of the Hilarides Dairy
digester's $1 million cost was paid by
the California Dairy Power
Production Program (DPPP), which is
administered by Western United
Resource Development for the
California Energy Commission.
Fourteen projects have been approved
for DPPP grants, totaling nearly $58
million. The projects have an
estimated generating capacity of
nearly 3.5 megawatts.
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