United States
Environmental Protection
Agency
Air and Radiation
Washington, DC 20460
EPA-430/F-00-012
Spring 2000
http://www.epa.gov/agstar
oEPA AgSTAR Digest
ENERGY AND POLLUTION PREVENTION
Inside
AgSTAR 2000 1
Current Status of Farm-Scale Digesters 3
Environmental Corner
Anaerobic Lagoon Covers for Energy Production and Odor Control 8
Showcase Corner
Haubenschild Dairy 9
Apex Pork 10
AgSTAR 2000
As the agricultural industry
enters the new century, a num-
ber of growing environmental
challenges are already evi-
dent. Farmers are responding
by making changes to their
operations—driven in some
cases by new regulations or by
encroaching urbanization and
local pressure, in other cases
by the desire to improve pro-
ductivity of the land or by the
sense that protecting air and
water quality is simply smart
business.
Complete mix digester at Colorado Pork LLC's 5,000-sow
farrowing operation.
Meeting these challenges will
require farmers to develop long-
term, cost-effective environmental
strategies. Waste management sys-
tems—the focus of the AgSTAR pro-
gram for over five years—will play a
critical role in farmers' long term
approaches. How animal waste is
managed affects environmental per-
formance in a number of ways, from
air and water quality in surrounding
communities to the productivity and
profitability of the farm.
Choosing a Waste Management
System. Despite the importance of
waste management to a farm's over-
all operations, waste management
systems have developed with little or
no standardization or uniformity in
design, construction, and operation.
As might be expected with such a
diversity of systems, the environ-
mental performance of waste
management systems varies
widely. Farmers considering
expanding or updating their
current waste management
systems face a myriad of
options.
Although considerable re-
search on waste management
options has been undertaken,
a great amount of work
remains to be done to verify
and pull together the research
conducted to date. One of the
AgSTAR program's major
initiatives for 2000 is to
organize and structure the
existing research in a form that is
accessible and useful. We are striv-
ing to provide farmers the informa-
tion necessary to compare a wide
array of waste management systems
on environmental and cost bases.
Systems we are reviewing include
digesters, separators, open lagoons,
pits, tanks, and aeration processes.
continued on page 2
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AgSTAR DIGEST • SPRING 2000
AGSTAR 2000 (continued)
We are compiling information on the
net capital and O&M costs of these
systems, as well as on important
aspects of their environmental per-
formance. For example the table
below compares the costs of single
cell lagoons, covered lagoons with
separate storage, and heated
digesters for a 5,000-head continu-
ous flow finishing operation in Iowa,
based on the farm and cost parame-
ters below:
• Manure is collected with pull
plugs (at 3 percent total solids)
•Excavation costs are $1.50 per
cubic yard
• Lagoon lining costs are $0.70 per
square foot
• Concrete costs average $200 per
cubic yard (placed)
• Storage period is 210 days
This comparison shows that a com-
plete mix or covered lagoon digester
AgSTAR program information
All AgSTAR program information is available through the AgSTAR Hotline
(1-800-952-4782) and website (http://www.epa.gov/agstar). We are cur-
rently integrating data on environmental and cost comparisons into our fact
sheets, brochure, and other informational packages—you can download
these and other products from the website or call the Hotline to request
hard copies. The website also has direct links to related industry, vendor,
and utility sites, and the Hotline can provide information about the Digester
Farm Days sponsored throughout the country by AgSTAR, which offer
farmers an opportunity to view commercial-scale biogas systems firsthand.
in a manure treatment/storage plan
can be cost-competitive when com-
pared to a typical treatment/storage
lagoon. Substituting a digester
investment for a lagoon investment
provides the farm owner with a free
energy source, the additional benefit
of odor control, and the opportunity
to reduce methane and other manure-
generated off-gases. Additional cost
savings are achieved because of
reduced lagoon volumes and lower
land application costs. The stored
effluent is also of uniform quality
and will not be an odor source when
land applied.
In This Edition. Our feature article
summarizes the status of operating
digesters across the country, high-
lighting the range of digester tech-
nologies that are currently viable
options for livestock producers. This
article also highlights AgSTAR's
Charter Farm program, which
Table 1. Estimated Costs of Waste System Options for 5,000 Finish Hogs'!
Estimated
treatment
cost
Estimated
storage
cost
Estimated
total
cost
Net benefit
as propane
$/year*
Net cost
per pig
capacity
Treatment option, HDPE-lined
Single cell lagoon
$292,132
Two-cell lagoon, one cell covered $236,034
Complete mix digester
$184,740
included
$ 82,378
$ 82,378
$292,132
$318,412
$267,118
0
$20,454
$12,893
$58.43
$59.59
$50.85
Treatment option, no liner
Single cell lagoon
One cell covered
Complete mix digester
$166,289
$193,387
$184,740
included
$41,784
$41,784
* Propane @$0.50/gallon
1 Adapted from Keeping The Neighbors Happy — Reducing Odor While Making Biogas. Mark A.
Roos. Presented at: Animal Production Systems and the Environment, Ames, IA, July 19-22,
$166,289
$235,171
$226,524
Moser, Richard P.
1998.
0
$20,454
$12,893
Mattocks, Dr. Stacy Gettier,
$33.26
$42.94
$42.73
and Kurt F.
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AgSTAR DIGEST • SPRING 2000 3
completed its twelfth and final
demonstration system last fall. The
Technical Corner contains the latest
information on lagoon cover costs
and approaches for odor control and
energy production. Finally, the
Showcase Corner provides a snap-
shot review of Apex Pork's innova-
tive covered heated mixed earthen
digester for odor abatement and
manure treatment—a useful case
study as issues related to odor con-
tinue to emerge. The Haubenschild
Dairy article illustrates the environ-
mental and business opportunities
a digester provides for the farm,
the community, and rural electric
systems.
A Preview of Things to Come.
Thanks to the completion of these
systems, we are excited to announce
that the number and types of digester
Farm Days will be expanded from
last year. The Farm Days provide
firsthand exposure to a variety of
biogas systems and gas uses as
explained by their operators.
Farm Days also provide a great UM
opportunity to network within
the agricultural and energy
industries. The first Farm Day
of the year will be held
at Haubenschild Farms in
Princeton, Minnesota and will
showcase the recently installed
heated plug flow digester at the
Haubenschild's 500-cow freestall
dairy. A second Farm Day is sched-
uled in Lamar, Colorado. It will
showcase Colorado Pork, LLC's
Julian Barham and his bank-to-bank covered lagoon—1999 winner of the National
Pork Producers Council Environmental Stewardship Award.
complete mix digester and energy
recovery system.
And a Look Back. It seems fitting
to end our overview of the AgSTAR
program in the year 2000 by men-
tioning the impressive accomplish-
is
in a of ways
to the and if the
ments of several of our Partners in
1999. We are delighted to announce
that Julian and Elaine Barham won
the 1999 Environmental Stewardship
Award from the National Pork
Producers Council and that Mr.
Barham was featured in the
September issue of National Hog
Farmer. The Barhams use a covered
anaerobic lagoon for waste manage-
ment, electricity generation, and heat
production. Also featured in
the August, 1999 issue of
National Hog Farmer was
Glenn Saline of Apex Pork,
who installed an innovative
heated, covered anaerobic
lagoon. (See the Showcase
Corner for more information
on the Apex Pork digester.) We
congratulate Mr. Saline and the
Barhams, and all partners whose
innovation improves our capacity to
manage waste soundly and econom-
ically, and we look forward to work-
ing with you in 2000 and beyond.
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AgSTAR DIGEST • SPRING 2000
CURRENT STATUS OF FARM-SCALE DIGESTERS
In preparing this issue of the AgSTAR
Digest, we followed up with digester
owners to provide a brief report on the
status of farm-scale digesters current-
ly operating at commercial livestock
farms in the U.S.
Currently, 31 digester systems are in
operation at commercial livestock
farms. Of these, 15 are at swine
farms, 14 are at dairy farms, and 2
are at caged layer farms.
Eighteen systems were installed dur-
ing the 1990's—more than doubling
the number of successful systems
installed during prior years. (See
Figure 1 below.) Twelve of the 31
digesters are at participating
AgSTAR Charter farms, and many
of these were completed in coordina-
tion with emerging state agricultural
energy programs in Iowa, Minnesota,
and New York.
In 23 of the 31 systems, the captured
biogas is used to generate electrical
power and heat. In 1999, these sys-
tems in total produced roughly 1 mil-
lion MWh of power. The remaining
8 systems flare the captured gas for
odor control.
The 31 operating digesters prevented
over 4,800 metric tons of methane
from entering the atmosphere
(approximately 27,500 metric tons
on a carbon-equivalent basis ).
The table on pages 5 and 6 provides
detailed information about each of
the operating digester systems. The
table is organized by digester type
(i.e., covered anaerobic lagoon, com-
plete mix, and plug flow configura-
tions). The map on page 7 illustrates
the location of each system. Swine
and dairy currently account for the
majority of methane emissions from
livestock management.1
I Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-1997. U.S. EPA, EPA 236-R-99-003, April 1999.
Figure 1: Operating Farm Scale Digesters
o>
Q.
O
20
15
10
Other
Plug Flow: Straight Flow
Complete Mix
Covered Anaerobic Lagoon
Plug Flow: Slurry Loop
1970's
1980's
Year Installed
1990's
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AgSTAR DIGEST • SPRING 2000 5
Table 2: U.S. Operating Digesters, March 2000 (Bold text indicates AgSTAR Charter Farms)
Location Year built Animal type Manure Installed Biogas end-use CH4 reduction
and population handling cost Mt CE/year*
COVERED LAGOON
CA
CA
CA
VA
NC
IA
CA
MS
NC
Wl
Wl
1982
1984
1986
1993
1997
1998
1998
1998
1999
1999
1999
Swine;
1,650 sows
farrow-to-finish
Swine;
900 sows
farrow-to-finish
Swine;
550 sows
farrow-to-finish
Swine;
600 sows
farrow-to-feeder
Swine;
4,000 sows
farrow-to-wean
Swine;
3,000 nursery pits
Dairy; 200 cows
Swine; 120 pigs
Swine; 400 sows
farrow-nursery
Dairy;
1,100 milkers
Dairy;
1,300 milkers
Flush
Flush
Flush and
gravity drain
Flush and
pull plug
Pull plug
Pull plug
Flush
Hose wash
Flush
Scrape
Scrape
$220,000
$120,000
$75,000
$85,000
$290,000
$15,000
$150,000
$19,000
$22,150
$37,300
$122,000
Electricity
and hot air
Electricity
and hot air
Electricity
and hot air
Electricity
Electricity
and hot water
Flare
Flare
Flare
Flare
Flare
Flare
2,316
1,263
772
397
1,158
Never metered
149
17
146
Never metered
Never metered
' Greenhouse gas emissions in the U.S. are most commonly expressed as metric tons of carbon equivalents (Mt CE/year). This measure is used to
compare the emissions of different greenhouse gases based on their global warming potential.
-------
6 AgSTAR DIGEST • SPRING 2000
Location Year built Animal type Manure Installed Biogas end-use CH4 reduction
and population handling cost Mt CE/year
COMPLETE MIX
NC
NY
*
PA
CT
IL
IA
CO
1983
1985
includes othe
1985
1997
1998
1999
1999
Caged layers;
70,000
Dairy; 270 milkers
r costs associated with the f£
Swine; 1,000 sows
farrow-to-finish
Dairy; 600 milkers
Swine; 8,600
finishing hogs
Swine; 5,000 sows
farrow-to-wean
Swine; 5,000 sows
farrow-to-wean
Scrape
Scrape
rm's manure ma
Scrape
Scrape
Pull plug
Pull plug
Pull plug
$225,000
$500,000*
nagement system
$325,000
$450,000
$152,300
$546,000
$368,000
Electricity
Electricity
and hot water
e.g., storage tanks, alley scrape
Electricity
and hot water
Electricity
Hot water and flare
Electricity
Electricity
1,129
672
rs)
1,210
1,210
1,191
959
1,013
PLUG FLOW-STRAIGHT FLOW CONFIGURATION
Ml
VT
CA
OR
NY
MN
1981
1982
1982
1997
1998
1999
Dairy; 720 milkers
Dairy; 340 milkers
Dairy; 400 milkers
Dairy; 1,000 milkers
Dairy; 1,000 milkers
Dairy; 1,000 milkers
Scrape
Scrape
Scrape
Scrape
Scrape
Scrape
$150,000
$185,000
$200,000
$287,300
$295,700
$295,853
Electricity
Electricity and hot water
Electricity and hot water
Electricity
Electricity
Electricity
1,169
1,008
806
1,129
1,129
992
PLUG FLOW-SLURRY LOOP CONFIGURATION
IA
PA
PA
PA
CT
MD
*
1972
1979
1983
1983
1997
1994
includes othe
Swine; 150 sows
Dairy; 2,000 milkers
Caged layer; 70,000
Dairy; 250 milkers
Dairy; 200 milkers
Dairy; 450 total head
;r costs associated with the fc
Flush
Scrape
Scrape
Scrape
Scrape
Scrape
irm's manure ma
$20,000
$260,000
$140,000
$120,000
$149,000
$500,000*
nagement system
Flare
Electricity and hot water
Electricity and hot water
Electricity and hot water
Hot water and flare
Flare
e.g., storage tanks, alley scrape
Never
measured
5,107
753
538
242
349
rs)
OTHER DIGESTER TYPES
IA
1999
Swine; 2,800
finishing hogs
Scrape
$244,675
Hot water and flare
827
-------
Figure 2: Operating farm-scale digester systems
Covered Lagoon
Complete Mix
Plug Flow: Straight Flow
Plug Flow: Slurry Loop
Other
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8 AgSTAR DIGEST • SPRING 2000
ENVIRONMENTAL CORNER
Anaerobic Lagoon Covers for Energy Production and Odor Control
In the United States, about 40 live-
stock lagoons have been covered to
collect and/or control methane and
odorous off-gases generated from
manure. Many of these covers are on
single-cell lagoons, which do not
take advantage of the environmental
and financial benefits of separating
the treatment and storage functions.
The majority of these covered
lagoons also vent unburned gases to
the atmosphere. Eight livestock
facilities, however, have designed
lagoon covers that collect gases for
combustion in odor control flares,
boilers, and engine generators. The
cost of covers used in these applica-
tions ranges from $0.37 to $1.75 per
square foot installed.
Separating the treatment and
storage functions. Where covered
anaerobic lagoons are used for odor
control and energy production, the
system typically consists of two sep-
arate lagoons operating in series1.
The first lagoon is a covered, fixed-
volume treatment lagoon designed to
biologically stabilize manure influ-
ent. Here, offgases are collected and
combusted. The second, uncovered
lagoon is used to store treated efflu-
ent from the first lagoon during non-
cropping periods. Separating the
storage and treatment functions
improves manure decomposition and
requires significantly less total
lagoon volume. In many cases, the
savings in lagoon excavation costs
achieved by separating the treatment
and storage functions can pay for
most of the lagoon cover costs.
Quality control considerations.
To achieve odor control and/or ener-
gy production, the lagoon cover must
continuously collect lagoon-generat-
ed biogas at a dedicated gas take-off
point for transmission to a flare, boil-
er, or generator. The cover must be
capable of collecting the biogas even
during periods of precipitation.
If the end-use for the collected gas is
energy production, the quality con-
trol in cover fabrication, assembly,
and installation must be high enough
to limit air intrusion. If the end-use is
solely odor control (i.e., if the col-
lected gas is flared), quality control
can be eased somewhat because air
infiltration is less of a concern.
Before constructing a lagoon cover,
the following critical variables must
be considered:
Materials: Cover materials need to
withstand sun, wind, extremes in
temperature, and other climate vari-
ables. Material resistance to capil-
lary action (i.e., wicking) should also
be considered.
Fabrication: Quality, gas-tight seams
are a key requirement for all lagoon
covers that collect gas for combustion.
Design: The cover design must fac-
tor in gas and rainfall management
as well as stresses caused by
extremes in weather. Poor design can
impede or cut off gas flow, cause air
to intrude, or—in extreme cases—
cause complete cover failure.
Basic lagoon cover designs.
There are two basic types of lagoon
cover designs: bank-to-bank and
modular. Both designs can effective-
ly collect biogas and reduce odor.
Bank-to-Bank covers completely
span the lagoon surface with a fabri-
cated floating cover. To secure the
cover to the lagoon bank, the cover's
edges are buried in perimeter trench-
es. Burying the cover edges creates a
completely anaerobic environment,
ensures the capture of all off-gases
AgSTAR Farm Day demonstration of
seaming process for lagoon covers
produced, and excludes rainfall from
the lagoon. For bank-to-bank covers
to function effectively, incident rain-
fall removal mechanisms must be
included. Rainwater management
must also be considered in the cover
design to ensure against longer-term
cover performance problems.
Modular covers use smaller cover
sections, or modules, as opposed to
the single large cover used in bank-
to-bank designs. The owner or sup-
plier can build the modules offsite
and then assemble the cover on site.
The lagoon can be covered in stages,
thereby reducing the need for a large
initial capital outlay. Modular lagoon
covers typically cover 50 to 90 per-
cent of a lagoon's surface and can be
secured either with bank trenching or
tether ropes. Modular covers do not
catch all gas, nor do they exclude all
rainfall. Flotation and rainfall man-
agement must be included in the
design. When sizing a treatment
lagoon for a modular cover, rainfall
addition must be accounted for if
rainfall is allowed to enter the treat-
ment lagoon.
For more information on covered
lagoons and other environmentally
smart waste management systems, or
to review a copy of the Industry
Directory for On-Farm Biogas
Recovery Systems, visit the AgSTAR
website or call the AgSTAR hotline.
l As prescribed under NRCS Interim Design Standard No. 360
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AgSTAR DIGEST • SPRING 2000 9
SHOWCASE CORNER
Haubenschild Dairy
In September 1999, Dennis Hauben-
schild and sons Tom and Bryan,
owners and operators of Hauben-
schild Farms in Princeton, Minnesota,
completed the installation of a heat-
ed plug flow digester at their 500-
cow freestall dairy.
The digester, which measures 130
feet long, 30 feet wide, and 14 feet
deep, is sized to treat manure from
up to 1000 milk cows. Manure from
the freestall barns is scraped twice a
day into a collection tank. From the
tank, the manure flows into a mix pit
before it is pumped into the digester.
and my
%» <3 / 1
The digester is covered by an imper-
meable coated plastic material and is
equipped with a network of water-
heated pipes that maintain an appro-
priate digester temperature of 100
degrees Fahrenheit. Under the anaer-
obic conditions within the digester,
the manure is broken down to pro-
duce biogas and a nutrient-rich efflu-
ent. The effluent flows via gravity
into a nearly odor-free storage basin
and is then land-applied. The
methane-rich biogas fuels a Caterpil-
lar 3406 engine attached to a 150 kW
Haubenschild Farms heated plug-flow digester
generator. The Haubenschilds sell all
the excess electricity produced to
their local electric cooperative, East
Central Energy. Heat, recovered as
hot water from the engine and
exhaust, is stored in an insulated
3,800-gallon tank and is used to
maintain the digester's temperature
and to heat the floor of the milking
parlor.
In its first seven months, the system
operated over 96 percent of the time,
producing 320,000 kWh of power
from 8 million cubic feet of biogas.
The system produces over 33 percent
more electricity than is used on the
farm. Propane purchase have been
all but eliminated, and areas are now
heated which were not winterized
before.
By Fall 2000, the Haubenschilds will
complete construction on a second
barn that will house an additional 500
cows. Barn floors will be heated with
hot water from the digester system.
A cost breakdown for this digester is
shown in Table 3 below.
Table 3: Haubenschild Farms
Heated Plug Flow Digester Costs
Collection Tank
$29,505
Cogeneration Building $155,503
Digester
$111,313
TOTAL COST
$295,853
Savings after first $24,200
7 months of operation
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10 AgSTAR DIGEST • SPRING 2000
The methane recovery system at
Haubenschild Farms has produced
revenues from sale of electricity and
reduced farm expenditures by virtu-
ally eliminating propane purchases,
while contributing to the farm's envi-
ronmentally sound manure manage-
ment strategy. The value of energy
production over the 7-month period
is about $23,000 in electricity and
$1,200 in propane.
"We're very pleased to assist the
Haubenschilds in the development of
this exciting new renewable energy
project and the results are particular-
ly noteworthy," said Henry Fischer,
East Central Energy's (ECE's)
Manager of Business and Community
Development. "This project exem-
plifies ECE's mission, which is to
enhance the quality of life and pro-
vide premier service to our cus-
tomers," Fischer added.
Under a power purchase agreement,
ECE purchases all excess energy
from the Haubenschild farm under
the cooperative's general service
The engine room at Haubenschild Farms
three phase rate and ECE resells the
energy to other customers who par-
ticipate in the cooperative's Well-
spring renewable energy program.
"The Haubenschild Farm project is
an excellent example of how agricul-
ture, utilities, environmental organi-
zations, community groups, and oth-
ers can effectively pool their
resources to develop renewable ener-
gy, promote sustainable agriculture,
and ensure environmental steward-
ship," Fischer pointed out.
SHOWCASE CORNER
Apex Pork
It has sracllcd a lot better in Rio,
Illinois since 1998. That year, Glenn
Saline of Apex Pork installed a
methane digester next to the single
cell lagoon at his 8,600-hcad finish-
ing site. The operation of the digester
has significantly reduced odors—
and neighbors' complaints.
Manure from nine grow-finish
buildings used to flow into a vari-
able-depth single-cell lagoon with a
surface area of 6 acres and a depth of
13 feet. This configuration led to
seasonal odor episodes from the
lagoon. To control odor, the manure
now flows into a covered heated
1999 AgSTAR Farm Day at Apex Pork
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AgSTAR DIGEST • SPRING 2000 11
mixed earthen digester that measures
120 x 160 x 17 feet. The digester can
hold roughly 20 days' worth of
manure before the treated manure
enters the original lagoon now used
for storage. Mixing and heating
allow for year-round digestion. The
alternative would have been an
ambient-temperature lagoon 20
times the size of the current digester.
PHOTO NATIONAL HOG FARMER, '
that to to
A submersible propeller mixer,
located near the bottom of the
lagoon, mixes and suspends manure
solids daily. Bacteria in the digester
convert soluble and suspended
organic compounds into methane,
carbon dioxide, and water. The
methane and carbon dioxide bubble
to the surface of the digester, where
Floating gas collection cover at Apex Pork
the methane is collected under the
digester cover and piped to a small
boiler. Hot water is pumped back into
the digester to maintain slurry tem-
perature (ideally, 85-105 degrees F).
Table 4: Apex Pork Complete Mix Digester Costs
Manure transfer pipe
Excavation
Digester cover
Digester mechanical
Gas pump, meter, piping
Engine-generator
Boiler
Hot water use equipment
Engine-generator building
Farm labor, electrical
SUBTOTAL
Engineering and permits
Startup
TOTAL COST
$1,400
$24,000
$39,700
$21,000
$6,200
$0
$17,600
$0
$5,700
$5,000
$120,600
$19,000
$8,000
$147,600
This heating system allows the bac-
teria to work effectively in the win-
ter. Digested manure flows into the
storage basin—now nearly odor-
free—and is held until crop, soil, and
weather conditions are appropriate
for land application.
The digester cost approximately
$150,000 to build. (See Table 4 at
left.) Annual operating costs are
about $5 00 for electricity for pumps,
while maintenance costs to date have
been less than $500 per year.
Estimated long-term operating and
maintenance costs are about $2,000
per year.
According to Saline, the benefits are
worth the cost. These include
improved effluent for land applica-
tion and—most importantly—signif-
icantly reduced odors. "I think we've
dramatically reduced those odors,
and we're expecting that to continue
to improve," says Saline. "We feel
like we have tried hard and we feel
good about what we have done."
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For more
or the an at:
EPA
1200 Ave., NW
DC
of to PST)
www.epa.gov/agstar
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