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CLEANUP - CLEAN AIR
DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS
Renewable Energy-
Technologies
Superfund
What's Inside?
Solar, wind, landfill gas and
anaerobic digester information:
What is Renewable Energy?
Renewable energy is obtained from sources that are
essentially inexhaustible (e.g., solar, wind, biomass).
While fossil fuels are being depleted, renewable energy
technologies provide a lasting source of energy. This
document includes information on solar, wind, landfill
gas and biomass. One use of renewable energy is to
generate heat and electricity to power Superfund
cleanup sites. Using renewable energy can avoid many
of the pollutants that are emitted from fossil fuel use as
well as reduce the demand to extract fossil fuels.
Purpose of Cleanup - Clean Air
The Cleanup-Clean Air Initiative (CCA) is focused on
encouraging, facilitating and supporting implementation
of diesel emissions and greenhouse gas reductions
technologies and practices at Superfund cleanup and
redevelopment sites. To accomplish the greenhouse
gas reduction goal, Cleanup - Clean Air:
Raises awareness of the potential for greenhouse
gas emissions reductions at Superfund cleanup and
redevelopment sites;
Provides coordination and facilitation support for
potential Cleanup-Clean Air projects;
Creates a forum for information sharing among
renewable energy users, and works to leverage
significant new resources to expand voluntary
greenhouse gas reduction; and
Creates momentum for future greenhouse gas
reduction efforts within the Superfund Program and
elsewhere.
CCA Website www.epa.gov/reqion9/cleanup-clean-air
~ Cleanup-Clean Air Pilot Projects ~ Smart Energy
Resources Guide ~ Factsheets ~ Cleanup-Clean Air
Updates ~ Cleanup-Clean Air Staff Contact Info
The goal of CleanupClean Air is to
encourage, facilitate, and support diesel
emissions and greenhouse gas reductions
technologies and practices at Superfund
cleanup and redevelopment sites.
~ Cost Estimation
~ Considerations
~ Funding Resources
Importance of Using Renewable Energy
Most electricity is generated from coal combustion, which
releases greenhouse gases (GHGs) and criteria air
pollutants into our atmosphere that harm the environment
and human health. In 2005, more than 2.6 billion metric
tons of C02 were emitted from electricity production in the
US.1 So, on average, in 2005, the nation generated about
8.7 metric tons of C02 per person due to electricity
production. To estimate the emissions reductions from
using renewable energy at your cleanup site, go to:
www.epa.qov/cleanenerqv/enerqy-and-vou/how-clean.html
There is much interest in increasing renewable energy
use and reducing greenhouse gases at the executive
level by way of provisions in the Energy Policy Act of
2005, Executive Order 13123 (Greening the
Government through Efficient Energy Management),
Executive Order 13432 (concerning greenhouse gases
from vehicles and engines), and EPA clean energy and
climate priorities.
Renewable Energy Options
Solar panels can provide a large amount of energy to
run site equipment. Cost: $8,000-$10,000 per kW.2
Wind turbines harness wind energy. A single medium-
sized wind turbine with good wind conditions can
provide enough energy for eight 3-bedroom homes.
Cost: $2,000-$7,000 per kW.3
Landfill-gas-to-energy projects collect biogas which is
naturally produced by landfills as the waste degrades.
Energy from biogas can be converted into electricity for
site use. Costs vary; See page 14.
Anaerobic digesters decompose organic wastes in a
controlled environment to produce biogas which can be
used to generate electricity. Cost: ~ $3,500 per kW.4
~ Technology Background
~ Applicability
~ Sizing Estimation
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Ener9_y Refresher
Here are some common energy terms to be familiar with to better understand how renewable energy projects can
be implemented at your site. Energy is the ability of a system to do work. Forms of energy include chemical,
thermal, radiant, mechanical and electrical energy. The following is basic information about how electrical energy works.
Understanding Electricity Using a Hydraulic Analogy
Think of a faucet with a hose to help
understand amps, voltage, and
watts. Electricity running through a
wire is analogous to water running
through a hose.
Image courtesy NDT6
Voltage: Voltage is the "pressure" that pushes electrons along in a wire. This "electrical pressure" is analogous
to water pressure in a garden hose. The greater the pressure, the more energy each parcel of water has in
the hose and the greater the force with which it is pushed along.7 Voltage is measured in volts, usually
abbreviated "V".
Amperes (Amps): An ampere is a unit of measure of electrical current. An electrical current is the rate at which
electrons flow past a certain point in a wire. This electrical flow rate is analogous to a volume of water flowing
per second. Amperes is usually abbreviated "amps" or "I".8
Power (Watts): The rate at which electricity is produced or consumed is referred to as power. It measures how
much energy is needed to start a device or operate a piece of equipment per unit time. Using the water
analogy, power is the combination of water pressure (voltage) and rate of flow (current) that allows work to
be done (e.g., lighting a light bulb, water turning a turbine). Power is measured in watts (W) and can also be
measured in horsepower (hp). One hp is equivalent to 745.7 W. The power rating is usually found on the
specs of a piece of equipment.
Power (watts) = voltage (volts) x current (amps)
The actual energy used is measured in watt-hours (Wh). Therefore, a 60-watt light bulb needs 60 watts of
power to operate. If it operates for 3 hours, this light bulb will use 60 W x 3 hr = 180 Wh of energy.
Electrical Energy (Wh) = Power (W) x Time Operated (hours)
You most often see kWh on an energy bill and it stands for kilowatt-hours. One kilowatt is 1,000 watts. A
megawatt (MW) is 106 watts and a gigawatt (GW) is 109 watts. A typical 3 bedroom house will use about
600 kWh per month.9 Another energy unit, the British Thermal Unit (BTU), is usually used to describe the
energy content in fuels like natural gas. One kWh is equivalent to 3,414 BTUs.
Alternating and Direct Current: Electricity needs a complete circuit to flow. Electricity flowing in one direction
is referred to as Direct Current (DC), like in batteries and solar modules. Electricity that cyclically reverses
direction is referred to as Alternating Current (AC). Most appliances and equipment use this type of power,
and utility companies provide power as AC. Some renewable energy sources such as solar power and small
wind turbines generate electricity as DC and an inverter is used to convert it to usable AC power.10
CLEANUP - CLEAN AIR
DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS
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Electric circuit. Image courtesy Solar on-Line5
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DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS
Solar Power
Solar Power Basics
Energy from the sun's radiation can be converted directly
to electricity. Photovoltaic (PV) technology produces
electricity from sunlight. Sunlight photons hit PV cells and
create an electrical current. PV systems generate
electricity without noise or pollution (although the
production of PV systems results in some emissions) and
are widely available. PV systems last about 25 years, at
which time the unit produces power at around 80% of its
original power rating. PV technology can be installed
almost anywhere and typically requires little maintenance,
depending on the complexity of the system.
n-typc
p-type
pn-junction
back contact
The pn-junction of a solar PV cell. Image courtesy Special
Materials and Research Technology11
The core component of a solar panel is a PV cell.
Individual PV cells wired together in a sealed unit are
called a module. Modules wired together are called an
array. PV cells are composed of at least two layers of
semiconductor material, commonly silicon-based.
Photons (discrete packets of light) striking the cell
release electrons from the negative layer and they flow
towards the positive layer, creating an electrical current.
A metal wire placed on the positive and negative sides
powers a load with the induced current. The electrons
flow in a single direction, generating direct current (DC).
Most readily available PV systems are crystalline
modules that are around 10%-15% efficient. Single-
crystailine solar cells are made from a single large
crystal. Multi-crystalline modules are made from
multiple crystals grown together and are slightly less
efficient than single-crystal modules. Amorphous
modules, or thin film technology, are manufactured by
depositing semi-conductor material onto a sheet of glass
or plastic. They have maximum efficiencies of around
10%. These are ideal for building integrated uses such
as roof tiles or shingles (see image on page 6).
Multi-crystalline solar cell. Image courtesy Lawton Ltd1
Sizing a PV System for My Site
The size of the PV system depends on the energy
demands and available solar energy at a particular site.
PV modules have two efficiency ratings. One measure
is the Standard Test Conditions Rating set by the
manufacturer which represents the maximum output in
laboratory conditions. The more applicable efficiency
rating is the PV-USA Test Conditions rating which
reflects the electricity output under day-to-day
conditions. In general, a 1-kW PV system in Region 9
territory will produce between 135 and 150 kWh per
month. As a rule of thumb, a 1-kW system requires at
least 100 ft2 of space for crystalline systems.
Amorphous cells would need about 150 ft2 per kW.1i
Use the following equations to get approximate figures
for the size and cost of a simple stationary, or fixed tilt,
PV system for your site. Note that these equations do
not account for batteries or solar tracking capabilities.
Size of PV
System
Site Energy Needs
per Month
Average PV
Energy Output
? kW
kWh
per month
135 kWhper
month per kW
Total Cost of PV
System
Size of PV System
PV System Price
per kW
? $
kW x
$10,000 per kW
Here are a few websites that can help you size a PV
system for the electricity needs at your site:
This site is hosted by solar professional
organizations and the U.S. Department of Energy
(DOE). www.findsolar. com/iridex.php?paqe=riqhtforme
This calculator was developed by DOE National
Renewable Energy Laboratory (NREL) researchers.
www.pvwatts.org
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CLEANUP - CLEAN AIR
DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS
Solar Power
PV System Terminology
PV Cell A PV cell is the core component of a solar module that converts sunlight
into electricity.
PV Module PV modules are made up of individual PV cells wired together.
PV Array A PV array is composed of one or more PV modules wired together.
Charge Controller A charge controller is a device that prevents PV panels from
overcharging the batteries and the batteries from overly discharging electricity.
Battery Batteries can store electricity to be used during periods without sunlight or
augment peak loads during the day.
Inverter An inverter changes direct current (DC) to alternating current (AC).
Electricity produced by the PV system is DC and stored as DC if batteries are
included in the PV system but appliances and equipment usually use AC power.
Load A load is the general term for the power demanded by any device,
equipment, or appliance that consumes electricity.
Balance of System The balance of system includes all other hardware including
wiring and safety equipment that keep the system functional.
Grid-tied Grid-tied systems have access to electricity supplied by a utility. These
systems can receive energy produced from a local PV system as well as from the
utility and do not require battery back-up. Energy from solar panels that is not used
immediately at the site can be sent to the energy grid. When solar power is not being
produced, such as at night, the site can use electricity provided from the utility. For
net metered systems, the utility acts like a giant battery. Sites that do not have
access to grid-electricity will have to completely rely on an alternate power source. If
it is important to have a constant electricity source, battery backup is necessary.
Net Metering Net metering programs allow grid-tied utility customers who
generate electricity in excess of their consumption at a certain time to credit that
amount for later use. www.eere.enerqv.qov/qreenpower/markets/netmeterinq.shtml
0
AC
TtyfMlPV
"AC LouTH
Crystalline vs Amorphous Modules Crystalline modules are currently the most
efficient modules. They are delicate and need to be mounted on a rigid frame.
Amorphous modules are currently less efficient but advancing technologies show that they may soon produce
electricity at rates almost as high as single-crystal modules. Amorphous modules are flexible, and efficiency is not
as affected as crystalline varieties by high temperatures, shading or cloudy days. They are also used in building-
integrated PV applications such as in roof tiles (see image on page 6).
15
Tracking or Fixed Tilt Tracking units point PV arrays at the optimal angle to the sun throughout the day. They
can increase efficiency by 15% in the winter and 40% in the summer and thus reduce the size of the system but
require significant additional costs. They may need more frequent maintenance due to the moving parts. They are
best used at sites with long hours of sunlight and with no shading. Fixed tilt units do not move; they are tilted at an
angle equal to the latitude of the site to capture the greatest amount of energy over the year without using a
tracking system.
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DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS
Solar
Power
Cost
Does My Site Have Good Potential for
Solar Power?
Sites that receive direct sunlight without shading from
the hours of 9am to 3pm have good solar power
potential. For crystalline systems, completely shading
just one cell can reduce efficiency by 75%.16 On
moderately cloudy days, arrays can produce 80% of
electricity compared to a bright sunny day. Ideally,
panels (for sites in the northern hemisphere) should be
south-facing for maximum sunlight exposure. Each kW
of solar panels needs at least 100 ft2 of space. Panels
can be mounted on roofs or poles or directly on the
ground. The following NREL website provides maps of
sunlight availability based on location and type of solar
mounting (fixed tilt or tracking).
http://rredc.nrel.gov/solar/old data/nsrdb/redbook/atlas/
Keep in mind that this website gives the actual solar
radiation hitting earth's surface. Solar modules are
10%-15% efficient at capturing this energy. PV panels
can provide power to Superfund site remediation
systems (1) that are off-grid; (2) that utilize low-flow
pump systems; and (3) to augment grid-power for sites
with high electricity demand. In general, PV systems
will be most suitable for sites with an expected long-
term need for power to operate equipment.
Solar Tracking Unit. Image courtesy Northern Arizona Wind
and Sun1
Operation and Maintenance
Panels should be cleaned once a year if the site
receives little rain and/or wind. See the PV equipment
manual for more information on maintenance of the
system and its components, inverters usually need
replacement after about 15 years of operation. Cost for
inverter replacement is about $700/kW.18 Annual
maintenance cost is 0.25%-1.5% of initial system cost.
A system with battery backup costs $15-$20 per rated
watt ($15,000-$20,000 per kW). PV systems without
batteries cost $8-$10 per rated watt ($8,000-$10,000
per kW).19 Use the following calculators to estimate
costs, cash flow, and energy production:
www.findsolar com (select "My Solar Estimator")
www.consumerenerqycenter.org/renewables/estimator
Funding Resources
Federal Investment Tax Credit
Residential and commercial sectors are eligible for this
rebate. For equipment installed before Dec. 31, 2008, the
rebate is 30% of the capital cost. Equipment installed after
January 1, 2009 will get a 10% rebate. Residential
rebates have a $2,000 cap. There is no cap for
businesses. PRP-lead sites are eligible while EPA-lead
sites may not be. www.irs.gov/pub/irs-pdf/f3468.pdf
California Solar Initiative
The California Public Utilities Commission provides over
$2 billion in incentives over the next decade for existing
residential homes and existing and new business,
industrial, agricultural, and non-taxable properties. The
California Energy Commission has $350 million for its New
Solar Homes Partnership, Customers of PG&E, SCE, and
SDG&E are eligible. This incentive may be applicable to
Superfund and redevelopment sites. For more information
go to www.gosolarcalifomia.ca.gov.
Search for state and local incentives at www.dsireusa.orci.
Considerations
Panels should be cleaned more frequently for sites
located in dusty regions and in areas with bird
populations.
Inverters should be stored in a cool and dry location out
of direct sunlight if possible. Dust and cobwebs on the
inverter unit inhibit it from cooling properly.
A module will lose approximately 0.5% efficiency per
degree centigrade temperature rise between 80ฐC and
90ฐC. It is important to allow air flow under and over the
modules to remove heat and avoid high cell
temperatures.20
A module degrades about 0.5% per year in efficiency.21
Some efficiency is lost from the inverter, battery and
wiring.
March 2008
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CLEANUP-CLEAN AIR
DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS
Solar Power
Permits
Installers are usually responsible for garnering permits
from city and/or county offices and will pass on the
costs to the consumer. Among these are building
permits and electrical permits. Permit fees may cost up
to $1,500 although some cities have eliminated the fee
for solar installations. Sometimes, additional drawings
or calculations must be provided to the permitting
agency. Be sure the permitting costs and
responsibilities are addressed with your PV contractor
before installation begins.
Hybrid solar and wind system. Image courtesy DOE
Building integrated PV. Image courtesy Kyoccnr
Choosing a Solar Installer
Setting up a PV system on a cleanup site is usually
done through a solar installer or contractor. They will
design and size the PV system, and acquire and install
the appropriate panels, inverters, batteries, mounting,
and any other equipment, for a full running system.
Here are a few websites that provide a variety of
information on solar installers:
~ Pre-screened, customer reviewed installers:
www.findsolar.com
~ National solar trade association: www.seia.org/
members, php
~ General Services Administration Contracts
Schedule: www.gsaelibrarv.qsa.gov
Search "206 3" for solar businesses
~ Renewable energy businesses and organizations
directory: www.energy.sourceguides.com
For More Information
Solar resources for businesses:
www.nrel.gov/learning/sb photovoltaics.html
For technical PV information:
www1.eere.energv.gov/solar/photovoltaics.html
Finding the Right Solar Contractor
Start with contractors local to the site since they
would be familiar with the weather, sun availability,
and permitting processes of the area. Make sure
that they are licensed. Research or interview the
companies. Some key questions to ask are:
How many years have they been in business?
How many projects did they complete in the past
year?
Can they provide references for past projects
similar to the one for the cleanup site?
Have their installers been trained in PV projects?
What warrantees or guarantees are included?
Do they offer a wide variety of products?
(manufacturers of panels, batteries, inverters,
etc.)
Do they offer services after the PV system is
installed? If so, for how long?
Are they a member of a trade organization?
Ask for a cost estimate
h Do they include the type of mounting
requested, type of solar PV, etc? Ask for
peak and average kW output estimates for
specific conditions and seasons (sunny,
summer, etc.) to be included in the bid. For
battery systems, ask for specifications on
battery capacity, recharging times, and the
recharging cycle that will be used. Cheaper
estimates may not include a service or
device or may have hidden costs.
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Wind Power
Wind Power Basics
Wind results from the uneven heating of the earth's
surface and atmosphere, rotation of the earth, and
topographical irregularities.24 Kinetic energy in wind can
be captured by wind turbines and converted to mechanical
energy. Generators produce electricity from this
mechanical energy. Simply, wind turbines work like a fan
operating backwards. Instead of electricity making the
blades turn to blow wind from a fan, wind turns the blades
of a turbine to generate electricity.
Basic Parts of a Small
Wind Electric System
Rotor
Generator/
alternator
Tower
Basic parts of a wind turbine. Image courtesy DOE EERE2
Wind turbines range in size from a few kilowatts to as
iarge as several megawatts. The amount of power
produced by the turbine depends on the length of the
blades and the speed of the wind. The faster the wind
speed, the more kinetic power it has. There is a cubic
relationship between wind speed and power, which
means that a small change in wind speed will have a
large effect on power produced. Wind speeds vary with
height and are generally weaker near the ground due to
friction between earth's surface and airflow. To reduce
turbulence and capture a greater amount of wind energy,
turbines are mounted on towers. A common tower height
is about 150 feet, though it will depend on the length of
the blades. A 10-kW turbine will usually need a tower of
80-120 feet.26 Wind speeds are classified into wind power
classes designated Class 1 (lowest) through Class 7
(highest). Sites with Class 2 and above wind speeds (at
least 10 mph measured at 33 feet above ground) could
consider installing a small wind turbine. See page 9 for
wind speed maps.
Close-up of wind turbine. Image courtesy Argonne National
Lab2?
There are two basic groups of wind turbines.
Horizontal axis turbines (propeller style) have two
blades that face downwind or three blades that face
upwind. Vertical axis turbines, such as the eggbeater-
style Darrieus model, are less commonly used. Blades
for both types are made from fiberglass, carbon fiber,
carbon composites, or wood and will not interfere with
TV or radio waves.28 Wind turbines can be used in a
wide variety of applications from charging batteries, to
pumping water, to powering a significant portion of a
site. Turbines may produce DC or AC power
depending on the generator. Generators that produce
DC power need an inverter to change the power to AC
for use in most equipment. Some efficiency is lost
through the inverter. A 1.5-kW wind turbine will
produce about 300 kWh per month in a location with a
14 mph (6.26
meters-per-second)
annual average wind
speed. The turbine
manufacturer can
provide the expected
energy output of a
turbine for wind
conditions at your
site.
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DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS
Wind Power
Wind Turbine Terminology
Anemometer Device ori a wind turbine that measures
the wind speed and transmits wind speed data to the
controller.
Blades Most turbines have either two or three blades.
Controller Component of a turbine that starts up the
rotor in wind speeds of about 8-16 mph and shuts it off
when wind speeds exceed about 65 mph. Usually,
turbines cannot operate in such high wind speeds
because their generators could overheat.
Cut-in speed Minimum wind speed needed to turn the
blades and produce electricity. Varies from turbine to
turbine.
Cut-out speed Maximum wind speed that a turbine
can handle. Turbines automatically stop spinning at
winds greater than the cut-out speed to prevent damage
to the turbine. Varies from turbine to turbine.
Generator Device that converts mechanical energy
into electrical energy.
High-speed shafts Drive the generator at 1,000-1,800
revolutions per minute (rpm).
Low-speed shafts Drives the generator at 30-60 rpm.
Nacelle The nacelle sits atop the tower and encloses
the gear box, low- and high-speed shafts, generator,
controller, and brake. A cover protects the components
inside the nacelle. Some nacelles are large enough for a
technician to stand inside while working.
Power curve Graph showing the power output of a
wind turbine at various wind speeds.
Swept area Space that turbine blades travel
through. Larger swept areas capture more wind
energy. Area Swept = tt * r2(r= length of one blade)
Tower Towers are made from tubular steel or steel
lattice. Because wind speeds increase with height,
taller towers enable turbines to capture more energy
and generate more electricity than those with shorter
towers.
Wind Power Classes at 10 m (33 ft) Elevation
Power
Wind Speed
Wind Speed
Power Density
Class
mph
m/s
W/m2
1
0-9.8
0-4.4
0-100
2
9.8-11.5
4.4-5.1
100-150
3
11.5-12.5
5.1-5.6
150-200
4
12.5-13.4
5.6-6.0
200-250
5
13.4-14.3
6.0-6.4
250-300
6
14.3-15.7
6.4-7.0
300-400
7
15.7-21.1
7.0-9.4
400-1,000
si* alt
Wind power class NREL classification system of
wind speeds and corresponding wind power.
Wind power density Available
power in the wind usually measured
in watts per square meter.
Wind direction The figure to the
left illustrates an upwind turbine, so-
called because it operates with the
blades facing into the wind. Other
turbines are designed to run
downwind, with blades facing away
from the wind.
Wind map Map showing average
annual wind speeds at a specified
elevation.
Wind vane Measures wind
direction and communicates with the
yaw drive to orient the turbine
properly with respect to the wind.
Also known as the tail.
Yaw drive Upwind turbines
require a yaw drive to keep the rotor
facing into the wind.
Cleanup - Clean Air
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*Tenns and wind power chart courtesy
DOE31
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CLEANUP - CLEAN AIR
DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS
Wind
Power
What Size Turbine is Right for My Site?
While solar panels are rated at an industry standard,
there are no standards that apply to wind turbines.
Each turbine is different so you must look at the
specifications for each to estimate how much power it
could generate given the wind availability at your site.
The electricity produced by a wind turbine depends on
the average wind speed at your site, length of blades,
tower height, and efficiency of system components.
Turbine models with high rated power at lower wind
speeds will produce more energy because power in the
wind is proportional to the cube of the wind speed.
Wind turbine developers can help properly install a
turbine that is well suited for conditions at your cleanup
site. Though it is more expensive to install a taller
tower, it is often a good investment because the return
in energy production is greater. Installing a wind
turbine is usually cost effective if electricity rates are
more than 10 cents to 15 cents per kWh. Small
turbines are considered to be 100 kW or less while
large turbines are considered to be greater than 100
kW.
Does My Site Have Good Wind Energy
Potential?
There is a space minimum as well as wind speed
minimum for a wind power project to be feasible for
your site. The potential site should be located on or
near at least one acre of open, rural land. More
importantly, it is necessary to have consistent wind
speeds of at least 10 mph (4.5 m/s) at 33 ft (10 m)
elevation. A common height for wind turbines is about
150 feet (45.7 m) where the wind speeds are about
25% greater than at 30 feet. In general, for a small
wind turbine to be cost effective, it would need to be
installed in an area that has at least Class 2 wind
conditions.32 Wnd speeds at a site can vary based on
topography and structural interference. Localized areas
of good wind power potential such as a ridge-top may
not show up on a wind map, so site-specific evaluations
should be conducted to determine wind availability.
Wnd turbines should be sited in an area where
obstructions or future obstructions, such as new
buildings, will have minimal effect on the wind resource.
Consult vendors to determine turbines models that will
operate efficiently with wind speeds available at your
site. To view average wind speed maps, visit:
www.eere.enerqv.gov/windandhvdro/
windpowerinqamerica/wind maps.asp
Get site specific wind speed data using a recording
anemometer, which generally costs from $500 to
$1,500. The most accurate readings are taken at "hub
height," the elevation at the top of the prospective wind
turbine tower. This requires placing the anemometer
high enough to avoid turbulence created by trees,
buildings, and other obstructions.
Considerations
There has been concern over the aesthetic impact of
wind turbines, the noise generated (especially by
smaller turbines) and the impact on avian and bat
wildlife that might fly into turbines. Careful siting of
the turbines and continual technology improvements
can mitigate these concerns. One should look into
legal and environmental limitations for your city and
county.
How to Read a Wind Turbine Power Curve
A wind turbine power curve shows the power
output of a turbine at corresponding wind speeds.
A wind turbine with the power curve shown below
may be rated at 500 kW. What may not be stated
upfront is that wind speeds of 14 m/s to 24 m/s are
necessary to produce the rated power of 500 kW.
Be sure to determine the power output of a turbine
for wind speeds that are specific to your site.
Wind Turbine Power Curve
g 400.00 --
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0
1Il-T IllllllIIIIIIiliiliIh
10 12 14 16 18 20 22 24 26
Wind Speed m/s
Wind turbine power curve. Courtesy De Montfort
Univerisity33
Cleanup - Clean Air
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CLEANUP - CLEAN AIR
DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS
Wind
Power
Funding Resources
Cost
Smaller wind turbines cost between $2,000 and $7,000
per rated kW. A typical 10-kWwind turbine system will
cost between $25,000 and $35,000. If placed in an
area with wind speeds averaging 10-15 mph, it will
produce between 10,000 and 18,000 kWh per year.34
Used turbines will be much less expensive but should
undergo remanufacturing by a qualified mechanic.
Many parts should be replaced, even if they are still
functioning since it is easier to replace parts while the
system is already disassembled.35
Operation and Maintenance
Annual operating and maintenance costs are estimated
to be about 1% of the capital costs. Alternator bearings
need replacement after several years of operation. The
same is true for yaw bearings given their significant
loading. Check that bolts remain tight. Dust, debris,
saltwater mist, and insects will eventually erode the
most durable blade materials, leading edge tapes, and
paint coatings. Paint coatings, subjected to sunlight,
moisture, and temperature extremes will eventually
deteriorate. Also, lubricant in the gearbox, like oil in a
car engine, will degrade over time. Maintain the turbine
as recommended by the manufacturer to ensure that it
will continue to operate properly for many years.36 A
typical wind turbine lifetime is 20-30 years.
Permits
Permitting requirements, procedures, and fees for wind
turbines vary by county. Costs for building permits,
zoning permits, and use permits may range from $100
to $1,600. Wind turbine standards and regulations may
include minimum land size, tower height restrictions,
minimum distance from the edge of the property, and
maximum noise levels. If your turbine tower is less than
20,000 feet from an airport runway or greater than 200
feet tall, you may need to get permission from the
Federal Aviation Administration and/or add warning
lights to your tower. The turbine must comply with the
Uniform Building Code and National Electric Code.
Consultants can help with permitting issues. Contact
the local municipality for more information on permitting
requirements.37
Renewable Electricity Production Credit (REPC)
Commercial and industrial sectors are eligible. The tax
credit is 1.90 per kWh of electricity produced by wind.
The duration for the credit is for 10 years. A business
can take the credit by completing IRS Form 8835
www.irs.gov/pub/irs-pdf/f8835.pdf and www.irs.gov/pub/
irs-pdf/f3800.pdf. This incentive can be applied to wind
turbines at PRP-lead facilities installed by December
31, 2008.
Renewable Energy Production Incentive (REPI)
This incentive is currently 1.90 per kWh produced for
the first 10 fiscal years of the system's operation. Only
generated energy that is sold to another entity
can receive the production incentive. Check
www.eere.energy.gov/repi for eligibility requirements.
Facilities must be in place by October 1, 2016.
Contact:
Christine Carter
christine.carter@go.doe.gov
(303) 275-4755
Check for state and local incentives at
www.dsireusa.org.
Wind Power Companies
There are many wind turbine manufacturers, retailers,
designers, consultants, and installers. Check
warranties, predicted lifetimes, and reputation of
companies to make well informed decisions.
Directory of wind power companies:
~ American Wind Energy Association:
www.awea.org/fag/smsvslst.html
~ Wndustry:
www.windustrv.org/companies
For More Information
General information:
American Wind Energy Association www.awea.org
Technology information:
U.S. Department of Energy wwwl .eere.energy.gov/
windandhvdro/wind technologies.html
Net metering information:
U.S. Department of Energy www.eere.energy.gov/
greenpower/markets/netmetering.shtml
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CLEANUP-CLEAN AIR
DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS
Landfill Gas
Landfill Gas Basics
Municipal solid waste (MSW) landfills consist of
everyday garbage generated from residences,
businesses, and institutions."48 Superfund landfills are
usually co-disposal facilities that include hazardous waste
as well as MSW. The decomposition of MSW creates
landfill gas (LFG). This gas is composed of about 50%
carbon dioxide (C02), 50% methane (CH4), and traces of
non-methane organic compounds (NMOC). Co-
disposal landfills tend to produce higher concentrations of
NMOC and air toxics. Methane, the major component of
natural gas, is a high energy gas that is used to provide
energy for homes, businesses and industries. Instead of
wasting a valuable energy source by flaring the LFG, it can
be collected from landfills and used directly for heating
and/or to generate electricity by implementing a Landfill-
Gas-to-Energy (LFGE) project. A series of wells drilled
into the landfill can collect the gas and transport it through
a system of pipes to be cleaned and then used to power
engines or turbines to produce electricity for use on your
Superfund site. Co-disposal landfills usually produce less
methane due to the age of the landfill and amount of inert
materials buried, rather than decomposable MSW waste.
Use EPA's Guidance for Evaluating Landfill Gas
Emissions From Closed or Abandoned Facilities
(www.epa.aov/nrmrl/pubs/600r05123/600r05123.pdf) to
evaluate potential emissions from Superfund landfills.
All
Landfill gas wells and piping.
Image courtesy LMOP39
Landfill gas treatment/blower/flare station.
Image courtesy LMOP4"
Cleanup - Clean Air
What is the Potential Energy Production
from a Landfill?
As a basic rule of thumb, 432,000 ft3" of LFG is produced
per day for every million tons of MSW in a landfill. This is
equivalent to 0.8 megawatts (MW) of power that could be
generated. Site measurements are recommended,
especially for co-disposal landfills, to more accurately
quantify LFG flow rates. When LFG is uncontrolled, it is
released into the atmosphere, contributing to smog and
climate change. Utilizing LFG as an energy source
reduces direct emissions from the landfill, as well as
offsets emissions otherwise emitted from fossil fuel use,
such as particulate matter (PM), sulfur dioxide (S02), and
carbon dioxide (C02)41 There are many factors that effect
the amount of gas produced for each landfill. Some of the
most important factors are:
Depth of landfill A landfill with a depth of at least 40
feet would be an ideal candidate because this depth
suits anaerobic conditions for producing LFG.
However, LFGE project have been successfully
implemented in shallower landfills.
Amount of waste A landfill with at least one million
tons of MSW is optimal. Smaller landfills are good
candidates if the gas will be used on-site or close by.
Type of waste Decomposing organic wastes like
paper and food scraps produce the most landfill gas.
Landfills with a lot of construction and demolition,
industrial, or hazardous wastes may not be as productive.
Age of landfill As a landfill ages, the rate of
methane production decreases. Landfills that are still
open or have recently closed have the best potential for
a LFGE project.
Rainfall The bacteria that break down the waste
thrive best in moisture. An optimal site will have at least
25 inches of rainfall a year. Landfills in arid climates
may produce gas at a lower rate but are expected to
produce gas for a longer period of time.
42
LANDFILL GAS SAFETY
LFG is potentially explosive, may pose an
asphyxiation hazard, and may cause headaches and
nausea due to odors. LFG collection systems
minimize exposure. Always take precautions when
handling LFG. For more information, see:
www.atsdr.cdc.gov/HAC/landfill/html/toc.html
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DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS
Landfill Gas
How is Landfill Gas Used?
Landfill gas is approximately 50% carbon dioxide and
50% methane. The methane can be (a) used directly
as a boiler fuel to produce hot water or steam to run a
steam turbine or for other processes; (b) used as a fuel
to power internal combustion engines or turbines to
generate electricity; or (c) treated to become pipeline-
quality gas.
I Ground Sur*-scซ
\ /
i?l
1 I l|l
Ok
K.
E-Hjracwi
Active Gas Collection System
Gas extraction schematic. Image courtesy LMOP43
LFGE Systems
Collecting landfill gas for energy production requires
three components:
1. Gas Collection and Backup Flare:
Gas collection typically begins after a portion of a
landfill (called a cell) is closed. A collection well is
drilled into the landfill to collect the LFG. Each LFG
wellhead is connected to lateral piping, which transports
the gas to a main collection header. An aqueous
condensate forms when warm gas from the landfill
cools as it travels through the collection system. If
condensate is not removed, it can block the collection
system and disrupt the energy recovery process.
Sloping pipes and headers in the field collection system
are used to drain condensate into collecting
("knockout") tanks or traps. Condensate could be
recirculated to the landfill, discharged to the public
sewer system, or treated on-site. Most landfills with
energy recovery systems have flares for combusting
excess gas and for use during equipment downtimes.
2. Gas Treatment:
The collected LFG must be treated to remove any
condensate that is not captured in the knockout tanks.
NMOC and air toxics must be properly treated.
Removal of particles and other impurities depend on
the end-use application of the LFG. For example,
minimal treatment is required for direct use of gas in
boilers, while extensive treatment is necessary to
remove C02 and other trace organic compounds for
injection into a natural gas pipeline. Power production
applications typically include a series of filters to
remove impurities that could damage engine
components and reduce system efficiency.
3. Energy Recovery:
Internal combustion (IC) engines, combustion
turbines (CTs), and boiler/steam turbines can
produce electricity using IFG. The IC engine is the
most commonly used conversion technology in LFG
applications. IC engine projects typically have higher
rates of NOx emissions than other technologies which
may cause permitting issues. Usually, NOx controls
can be installed to meet local requirements. CTs are
typically used in medium to large LFGE projects, where
landfill gas volumes are sufficient to generate a
minimum of 3-4 MW. One of the primary disadvantages
of CTs is that they require high gas compression levels.
More energy is required to run the compression system
for CT systems, as compared to other options.
However, CTs are much more resistant to corrosion
damage than IC engines and have lower NOx emission
rates. They are also relatively compact and have low
operations and maintenance costs in comparison to IC
engines. The boiler/steam turbine configuration is the
least used of these three landfill gas power conversion
technologies. It is applicable mainly in very large
landfill gas projects, where gas flows support systems
of at least 8-9 MW. The boiler/steam turbine consists of
a conventional gas or liquid fuel boiler, and a steam
turbine generator to produce electricity. This
technology usually requires a complete water treatment
and cooling cycle, plus an ample source of process and
cooling water.44 Lastly, note that LFG may be corrosive
to LFG collection and electricity generation parts and
equipment so proper maintenance is necessary to keep
the system running safely and efficiently.
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Landfill Gas
Landfill Gas Terms
Boiler I Steam turbine A boiler produces thermal
energy from burning methane gas. This heat is used in
a steam turbine to generate electricity. This
configuration is best suited for landfills with gas
production of greater than 5 million cubic feet per day.
It is the least used among landfill gas projects because
it is more expensive than other gas power conversion
technologies for the typical size of LFGE projects.
Collection wells Wells are strategically dug into a
landfill to collect LFG. The gas collection system
transports the gas to be treated and used to generate
electricity or as a fuel for heating applications.
Combustion (Gas) turbine Combustion turbines
(CTs) are typically used in medium to large landfill gas
projects, where landfill gas production is approximately
2 million cubic feet per day. This technology is
competitive in larger landfill gas electric generation
projects because of significant economies of scale.
The efficiency of electricity generation generally
improves as size increases.
Compressor This device changes the density of the
landfill gas to be compatible for use in an internal
combustion engine, combustion turbine, or
microturbine.
Condensate Condensate is a liquid that forms from
water and/or other vapors in the landfill gas that
condense as LFG travels through the pipes. Proper
disposal of condensate is necessary.
Internal combustion engine I reciprocating engine
This engine is the most widely used electricity
generation technology for LFG. They are typically used
for generation projects greater than 800 kW.
Methane (CH4) Methane is a highly combustible
greenhouse gas that makes up about 50% of gas
emitted from an MSW landfill. This gas can be used
directly to generate heat or as a fuel to produce
electricity. Methane makes up more than 90% of
typical natural gas.
Microturbine Each unit produces 30-250 kW and
can be combined with each other. They are better
suited to landfills where gas production is too low (low
concentrations of methane and/or low flow) to
economically use a larger engine, for landfills with
onsite energy use, or for use in areas where the use of
larger technologies is not feasible. The total installed
cost for a LFG microturbine project is estimated to be
$4,000 to $5,000 per kW for smaller systems (30 kW).45
Landfill Gas
MSW, other
organic waste,
moisture
bacterial
digestion in a
landfill
particulate matter,
odor, liquid waste
gas collection system
separator
liquid waste
blower, compressor
I
dryer
I
filters and scrubbers
sulfur, carbon
dioxide, solid
wastes
air
\
/
gaseous
emissions
biogas~^)
combustion
/
engine or
gas turbine and
generator
gaseous
emissions
boiler
I
heat,
steam
mechanical energy,
heat, electricity
Landfill gas to energy processes. Image courtesy Oregon
Department of Energy46
Possible Business Models
The following are possible business models that
outline LFGE operations and maintenance roles:
1) Landfill owner owns and manages all LFGE
equipment and sells electricity to the utility or
directly to an end user.
2) Landfill owner owns LFG collection system.
Electricity generation equipment owned and
operated by utility; the utility purchases landfill
gas from landfill owner.
3) Landfill owner provides LFG. Third party owns
and operates LFG collection system and
electricity generation equipment.
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DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS
Landfill Gas
Permitting Issues
LFGE recovery projects must comply with federal
regulations related to both the control of LFG emissions
and the control of air emissions from the energy
conversion equipment. Emissions need to follow Clean
Air Act and Resource Conservation and Recovery Act
regulations. States may have more stringent requirements.
Permits can take more than a year to attain. No
construction should begin until permitting issues are
resolved since permits may affect the design of the
project. Permits in the following areas may be required:
Air Quality
Building Permit
Land use Permit
Noise
Wastewater
Condensate
Water
Stack height
Costs and Benefits of a LFGE Project
Cost of a landfill gas project varies depending on a
variety of factors including the size of landfill, type of
electricity generation technology, and site specific
characteristics. A one million ton MSW landfill in 2002
with a typical landfill gas collection and control system
cost around $600,000-$750,000 and O&M cost for this
size landfill is approximately $40,000-$50,000 a year.47
Site preparation and installation costs vary significantly
among locations but electricity generation equipment
account for about 30-70% of the capital cost. Total
capital cost includes the engine/turbine, auxiliary
equipment, interconnections, gas compressor,
construction, and engineering services. Some landfills
may already have a gas collection system in place.48
Use the following resources to estimate LFGE costs
and benefits for an MSW landfill gas project.
Landfill Gas Emissions Model (LandGEM) This
model can be used to estimate total LFG, methane,
carbon dioxide, non-methane organic compounds, and
other emissions from MSW landfills.
www.epa.gov/ttn catc1/products.html#software
Landfill Gas Energy Cost Model Use this tool to
estimate the economic feasibility of an MSW LFGE project.
www.epa.qov/lmop/res#5
LFGE Benefits Calculator Use this tool to estimate
greenhouse gas reductions from a LFGE project.
www.epa.qov/lmop/res#5
Landfill Methane Outreach Program
The Landfill Methane Outreach Program (LMOP) is an
EPA assistance and partnership program that promotes
the use of landfill gas as a renewable, green energy
source. LMOP partners and forms agreements with
communities, landfill owners, utilities, power marketers,
states, the LFG industry, tribes, non-profit
organizations, and trade associations to overcome
barriers to project development by helping them assess
project feasibility, financing, and marketing the benefits
of project development to the community. LMOP
provides technical, informational, and marketing
services, such as:
Technical assistance, guidance materials, and
software to assess a potential project's economic
feasibility;
Assistance in creating partnerships and locating
financing for projects;
Informational materials to help educate the
community and the local media about the benefits
of LFG; and
Networking opportunities with peers and LFG
experts to allow communities to share challenges
and successes.
Contact LMOP for assistance on your landfill project:
www.epa.gov/lmop/contact
Renewable Electricity Production Credit (REPC)
Corporate tax credit of 1.90 per kWh produced for a
period of 10 years. Project must be operational by Jan
1, 2009. To apply for the credit, a business must
complete www.irs.gov/pub/irs-pdf/f8835.pdf and
www.irs.gov/pub/irs-pdf/f3800.pdf
Renewable Energy Production Incentive (REPI)
Credit of 1.00 per kWh generated and sold for a period
of 10 years, until 2026, if funds are available. Contact:
Christine. carter@qo.doe.gov or repi@ee.doe.qov
Check www.eere.enerqv.gov/repi.html for eligibility
requirements.
Check the following websites for more opportunities:
www.epa.gov/lmop/res/quide
www.dsireusa.org
For Net Metering Information:
www.eere.enerav.aov/areenpower/markets/netmeterina.shtml
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CLEANUP - CLEAN AIR
DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS
Anaerobic Digester Basics
Anaerobic digestion is the natural process of
decomposing organic materials such as manure,
wastewater treatment facility residuals, agricultural
wastes and food processing wastes, by bacteria in an
oxygen-free environment. One of the products of
anaerobic digestion is biogas, which consists of 60-70%
methane, 30-40% carbon dioxide, and trace amounts of
other gases. This natural process can be manipulated
in a controlled environment, such as in an anaerobic
digester, where the methane gas can be collected and
used for heating and/or electricity production.49
Digesters may be designed as plastic or rubber covered
lagoons, troughs, or as steel or concrete tanks.
Carefully controlled nutrient feed, moisture,
temperature, and pH in the digester can make a
habitable environment for anaerobic bacteria, which are
naturally occurring in manure. Digesters work best with
biomass that is greater than 85% moisture by weight.
Digesters can operate at two ideal temperature ranges:
mesophilic (95ฐF-105ฐF) which best host mesophile
bacteria, and thermophilic (125ฐF-135ฐF), which best
host thermophile bacteria. Waste heat from electricity
generators can be used to heat the digesters.
Thermophilic conditions decrease the hydraulic
retention time (time the organic matter remains in
digester), thus reducing the size of the digester needed.
However, thermophilic bacteria are also much more
sensitive to changes in their environment so digester
conditions must be closely monitored and maintained.
There is little change in the volume of the feedstock
after it goes through the digester. The digested
Anaerobic Digester
material can be used as high-quality fertilizer. The
effluent can be spread on fields as a liquid fertilizer or
liquids and solids can be separated to be sold
individually. Some liquid content can be re-fed into the
digester in the case that moisture content of the
feedstock needs to be increased.
The Digester System
The digester system components include:
Nutrient source Organic material Including
animal manure, wastewater treatment sewage
sludge, food processing waste, or agricultural
waste. It is possible to combine different sources of
organic matter to feed into a digester.
Transport system Most digesters are
constructed onsite near the nutrient source. The
organic matter must be collected and fed into the
digester.
Pre-treatment tank Sometimes a pre-treatment
tank is recommended in order to settle out sand,
grit, and other contaminants from the organic
feedstock before transporting into the digester.
Digester Choose a digester that suits your site-
specific characteristics (see page 16).
Gas handling system Biogas is collected and
processed to remove moisture and contaminants to
the degree necessary for end use.
Electricity generation system Reciprocating
engines, gas turbines, boilers / steam engines, or
microturbines and generators can produce
electricity using methane gas.
Flare or heat source Excess methane is flared.
Methane can also be used directly for heating the
digester or other
Effluent
Storage
Electric
Generation
System
Manure Source
and Collection System
Gas
Handling
System
I Flare or
' Heat Source
processes.
Effluent storage
Digested manure is
stored for later use. It
can be spread on fields
as a liquid fertilizer.
Solids can also be
separated for use as a
solid fertilizer.
Schematic of digester system. Image courtesy AgStar 50
Cleanup - Clean Air
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CLEANUP-CLEAN AIR
DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS
Anaerobic Digester
Conventional Types of Anaerobic Digesters
There are many types of anaerobic digesters. A digester suitable
for your site depends on the moisture content of the influent and, in
the case of covered lagoon digesters, climate at the site.
Complete-mix digester The complete-mix digester is a
vertical concrete or steel circular container that can be installed
above or below ground. It can handle organic wastes with total
solid concentration of 3-10%, such as manure or food waste
collected from a flush system. Complete-mix digesters can be
operated at either the mesophiiic or thermophilic temperature
range with a hydraulic retention time (HRT) of 10-20 days. A
mixer keeps the solids in suspension. This type of digester is
usually more expensive to build and maintain than the plug-flow
or lagoon digesters.
Fixed-film digester. Image courtesy University
of Florida^"
Cleanup - Clean Air 16 March 2008
Plug-flow digester The basic plug-flow digester design is a
rectangular trough, often built below ground level, with an
impermeable, flexible cover. Organic waste is added to one
end of the trough and decomposes as it moves through the
digester. Each day a new "plug" of organic wastes is added,
pushing the feedstock down the trough. Plug-flow digesters are
suitable for organic wastes with total solid
concentration of 11-13%, with a HRT of 20-30
days. Suspended heating pipes of hot water stir the
slurry through convection. This type of digester has
few moving parts and requires little maintenance.
Covered lagoon digesters A covered lagoon is an
earthen lagoon fitted with a floating, impermeable cover
that collects biogas as it is produced from the organic
feedstock. A lagoon is best suited for liquid organic
wastes with a total solid concentration of 0.5-3%.
Covered lagoon digesters are generally not heated so
they must be located in warmer climates for them to
produce enough biogas
for energy production.
This type is the least
expensive of the three.
See page 19 for more on
digester costs.
Plug flow digester. Image courtesy Pemi State University53
Other Digester Designs31
- Advanced integrated
pond system
- Up-flow solids reactor
- Fixed film
- Temperature-phased
- Anaerobic filter reactor
Typical digester configuration Image courtesy U.S. EPA54
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CLEANUP - CLEAN AIR
DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS
Anaerobic Digester
Energy Production
Digester Terminology
Anaerobic Absence of oxygen.
Anaerobic Digester Sealed container in which
anaerobic bacteria break down organic matter and
create biogas.
Biogas Gas produced from decomposition of
organic matter in an anaerobic digester. Consists of
60-80% methane, 30-40% carbon dioxide, and other
trace gases such as hydrogen sulfide, ammonia and
hydrogen.
Effluent Organic liquid and solid material leaving a
digester.
Feedstock Liquid and solid material fed to the
digester, usually manure, also known as influent.
Hydraulic Residence Time (HRT) The average
length of time the influent remains in the digester for
decomposition.
Influent Liquid and solid material fed to the
digester.
Methane A combustible gas produced by anaerobic
digestion, also the principle component of natural gas.
Mesophilic Temperature range between 95ฐF and
105ฐF in which methanogenic microbes thrive.
Thermophilic Temperature range between 125ฐF
and 135ฐF where certain methanogenic bacteria are
most active. The greatest pathogen destruction occurs
in this temperature range.
Producing biogas is the first step to harnessing energy
from organic wastes. Then, engines or boilers coupled
with generators convert the energy in the biogas into
heat and/or electricity to be used on the cleanup site.
Internal Combustion Engine I Reciprocating Engine:
An internal combustion engine is the most commonly
used technology for utilizing biogas. The biogas must
have condensate and particulates removed.
Boiler I Steam Turbine: The boiler produces thermal
energy from burning the methane gas. This heat is
used in a steam turbine to generate electricity. This
configuration is best suited for digesters that produce
more than 5 million cubic feet of methane per day.
Combustion (Gas) Turbine: Combustion turbines
(CTs) are typically used in medium to large biogas
projects. This technology is competitive in larger
biogas electric generation projects because of
significant economies of scale. The biogas must have
most of the visible moisture and particulates removed
and then compressed in order to be utilized in a gas
turbine combustion chamber.
Microturbine: Microtrubines range in size from 30kW-
250kW and can be combined. They are better suited
for digester projects for which gas production is too low
(low concentrations of methane and/or low flow) to
economically use a larger engine and for projects with
onsite energy demand. A microturbine costs from $700
per kW to $1,100 per kW. The addition of a heat
recovery system, which captures the otherwise wasted
heat, adds between $75 and $350 per kW.56
Microturbines require very clean biogas fuel, increasing
the cost for biogas cleanup.
Slurry - The mixture of biomass
processed in the digester.
Terminology courtesy of Penn State
University55
How it
5-20 Days. Tcnpefafure dependent
Anaerobic Digestion process. Image courtesy Penn State University
57
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CLEANUP - CLEAN AIR
DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS
Anaerobic Digester
Maintenance and Operations
Assessing Anaerobic Digester Potential
To consider an anaerobic digester energy project, a
Superfund site should be close to an organic waste
source. It may also be possible to collect organic
wastes from a community, such as local farms and food
processing facilities, though transportation costs must
be taken into consideration. As a general rule of thumb
for a manure biomass energy project, facilities should
have at least 300 head of dairy cows or steers, 2,000
swine in confinement, or 50,000 caged layers or
broilers (types of fowl) where manure is collected
regularly.58 This influent source should be available
year round for a constant supply of biogas for energy
production. Also, anaerobic digesters need material
with high moisture content. The influent should be
collected as a liquid, slurry, or semi-solid from a single
point daily or every other day. Alternatively, water may
be added after collection. Consider gasification
technologies for drier materials. Digesters work best
with manure that have as little bedding materials as
possible. It may be necessary to have at least one
person who can manage the digester for daily and
annual maintenance. Consider uses for the digested
material, both liquid and solid components, such as
fertilizers.
Benefits of Anaerobic Digesters
Green energy production
Reduced odor compared to stored liquid manure,
reducing potential nuisance complaints
Digested effluent can be pumped long distances
Reduction in pathogens and weed seeds in
digested manure
Fly propagation reduced
Solids separation of digested manuresolids can
be used as bedding or fertilizer. The fiber in
digested dairy manure can be used on farms as
bedding or recovered for sale as a high-quality
potting soil ingredient or mulch. Digested liquids
can be used as liquid fertilizer. Because anaerobic
digestion reduces ammonia losses, digested
manure can contain more valuable nitrogen for crop
production. Nutrient content of digested manure is
equal to that of the raw manure.
Anaerobic digesters require daily maintenance checks
and longer term maintenance. Daily maintenance
includes checking proper digester and engine function
(e.g., gas leaks in digester cover or piping, oil level in
the engine, film buildup in the digester). Daily
maintenance takes from 10 minutes to 1 hour a day.
Oil in the engine may need changing every few months.
Digesters may need to be cleaned out after several
years of operation. Biogas is a potentially dangerous
gas. Take precautions including, but not limited to,
installing gas detectors and posting warning signs and
never entering an empty digester without extensive
venting. Developers should train the owner to properly
maintain and operate the system to ensure efficiency
and safety. Go to http://www.biogas.psu.edu/
Safetv.html for more information on digester safety.
How Much Energy Can be Produced?
The amount of energy produced by an anaerobic
digester system depends upon the type of organic
matter, digester type, environment inside the digester,
loading rate, and type of energy recovery technology.
The following biogas production rates are based on
laboratory tests and excludes these efficiency factors.
Animal
(pounds of live
animal)
Beef (1,000 lbs)
Daily (1,200 lbs)
Poultry (4 lbs)
Swine (150 lbs)
Biogas BTU* production
Production per per hour
day (ft3)
31
22.7
0.21
4.1
775
568
5.25
103
(Chart courtesy of University of Missouri)59 *3,414 BTU = 1 kWh
Relationships Among Involved Parties
Consider the following:
Appropriate level of involvement with local utility if
the digester is to produce a large excess amount of
energy that can be net metered or sold to the utility.
The need for a formal agreement with agricultural
operator / food processor.
Which party will own, operate, and manage the
digester.
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Anaerobic Digester
Funding Resources
Permits
It is essential to garner appropriate permits early in the
digester planning process as the design may need
adjustment to comply with federal, state, and local
rules. Anaerobic digester construction and operation
may need permits in the following areas:
Land use
Confined Animal Facility Operation Permit
Noise
Wastewater
Water
Stormwater management
. Air
Emissions Issues
NOx emissions from combusting biogas may be of
concern for a digester project. Naturally aspirated
reciprocating internal combustion engines emit
relatively high levels of NOx. Fuel injected lean-bum
reciprocating internal combustion engines provide
greater engine power output and lower NOx emissions
compared to a naturally aspirated engine. Gas
turbines emit even lower levels of NOx. SOx may be
produced from swine manure digesters and may
necessitate the use of scrubbers. SOx emissions are
generally not a concern for other types of influent.
Cost
For a manure digester, EPA AgStar estimates that a
covered lagoon and heated digester will cost about
$200-$450 per 1,000 pounds of live animal weight that
contribute to the influent and a 3-7 year payback period.
Download FarmWare from www.epa.gov/aqstar/
resources.html to get a preliminary feasibility and
economic analysis for swine or dairy manure feedstock.
USDA Conservation Innovation Grants
These are competitive federal grants that target
innovative conservation approaches and technologies.
Grant monies and topics range year to year. For fiscal
year 2008, the grant can provide up to 50% of project
costs, not to exceed $1 million. Apply for state grants
for smaller projects.
www. n res. u sd a ,q o v/proq ra ms/ciq/
www.nrcs.usda.gov/proqrams/ciq/statecomponent.html
Contact: Tessa Chadwick (202) 720-2335
tessa.chadwick@wdc.usda.gov
Farm Pilot Project Coordination, Inc. (FPPC)
FPPC is a not-for-profit organization designated by
Congress that assists in implementing innovative
treatment technologies to address animal waste issues
from animal feeding operations. About $2-$3 million is
available per RFP round and each project is eligible for
up to $500,000.
www.fppcinc.orginfo@fppcinc.org (800) 829-8212
Renewable Energy and Energy Efficiency Program
Department of Agriculture: Rural Development
This program provides competitive grants and
guaranteed loans for rural agriculture producers and
small businesses to purchase renewable energy
systems and make energy efficiency improvements.
www.rurdev.usda.gov/rbs/
Renewable Electricity Production Credit (REPC)
Corporate Tax Credit of 1.00 per kWh produced for a
period of 10 years. Project must be operational by Jan
1, 2009. To apply for the credit, a business must
complete www.irs.gov/pub/irs-pdf/f8835.pdf and
www.irs.gov/pub/irs-pdf/f3800.pdf
Renewable Energy Production Incentive (REPI)
Credit of 1.90 per kWh generated and sold for a period
of 10 years, until 2026, if funds are available. Go to
www.eere.enerqy.gov/repi.html for more information.
For More Information
EPA AgStar
AgStar is an EPA program that specializes in
agricultural waste issues. Use the AgStar Handbook to
appraise the feasibility outlook of powering your site
with a digester. These resources are especially helpful
for swine or dairy manure, www.epa.gov/agstar
Penn State University
www.biogas.psu.edu/anaerobicdigestion.html
Cornell University
www.manuremanagement.cornell.edu
Possible Business Models
The following are possible business models that outline
digester operations and maintenance roles:
~ Producer of organic matter owns and manages digester
and electricity generation equipment.
~ Producer of organic matter owns and manages
digester. Electricity generation equipment owned and
operated by utility; the utility purchases the biogas
from digester owner.
~ Producer of organic matter provides influent. Third
party owns and operates digester and electricity
generation equipment.
Agricultural Biogas Casebook Update 2004
www.rs-inc.com/downloads/
Experiences with Agricultural Biooas Svstems-
2004 Update.pdf
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