Renewable Energy Technologies at Superfund Sites October 2007


/q\	CLEANUP - CLEAN AIR

V^Elj	DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS

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The goal of Cleanup—Clean Air is to
encourage, facilitate, and support diesel
emissions and greenhouse gas reductions
technologies and practices at Superfund
cleanup and redevelopment sites.



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 renewable
energy 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
Implements projects and leverages funds from a
variety of sources to create momentum for future
greenhouse gas reduction efforts within the
Superfund Program and elsewhere.

~	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.cleanerandqreener.org/resources/
emission reductions.htm
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: ~ $4,000 per kW.4

~	Technology Background

~	Applicability

~	Sizing Estimation

Cleanup - Clean Air

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October 2007

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Energy 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.

CLEANUP - CLEAN AIR

DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS

Understanding Electricity Using a Hydraulic Analogy

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5 amp

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BATTERY

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.

Electric circuit. Image courtesy Solar on-l.ine"

Image courtesy NDT

Voltage: Voltage is the pressure that pushes electrons along in a wire. Think of electrical pressure like water
pressure, pushing water through a pipe. Increasing pressure at the faucet increases the flow rate of water in
the hose. This is analogous to increasing voltage which would increase the flow of electrons through the wire
(increasing current).7 Voltage is measured in volts, usually abbreviated "V".

Amperes (Amps): Think of electrons flowing through a circuit like molecules of water flowing through a hose.
An electrical current is the rate at which electrons flow past a certain point in the pipe. This current is
measured in amperes, usually abbreviated "amps" orT.8

Power (Watts): Electrical power is the rate at which electricity is produced or consumed. 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). This rate of energy use is called power, which is
measured in watts (W). It 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 10° 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: Unlike water through a hose, electricity needs a complete circuit to flow.
Electricity runs as Direct Current (DC) flowing in one direction, like in batteries and solar modules, or as
Alternating Current (AC). AC alternates direction and most appliances and equipment use this type of
power. 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.

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October 2007

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CLEANUP-CLEAN AIR

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.

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The pn-junction of a solar PV cell. Image courtesy Special
Materials and Research Technology 11

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 side
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 ballpark 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 U.S. DOE
National Renewable Energy Laboratory (NREL)
researchers, www.pvwatts.ora

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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 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 sites have access to electricity supplied by a utility. These sites
can receive energy produced from a local PV system as well as from the utility. Grid-
tied systems 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

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"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). Crystalline modules are 10%-15% efficient
while amorphous modules are about 10% efficient. While 100 ft2 of crystalline cells produce roughly 1 kW, 100 ft2
of amorphous cells will produce about 0.60 kW.

Tracking or Fixed Tilt — Tracking units point the PV array 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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CLEANUP - CLEAN AIR

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) as an augmentation 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 watt
($15,000-$20,000 per kW). PV systems without
batteries cost $8-$10 per 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.consumerenerqvcenter.org/renewables/estimator

Funding Resources
Federal Tax Rebate

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. aov/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.qosolarcalifomia.ca.gov.

Search for state and local incentives at www.dsireusa.oro.

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. They may
need replacement after about 15 years of use.

•	A module will lose approximately 0.5% efficiency per
degree centigrade temperature rise between 80°C and
90°C. It is important to allow air flow under and over the
modules to remove heat and avoid high cell
temperatures.

21

•	A module degrades about 0.5% per year in efficiency,

•	Some efficiency is lost from the inverter, battery and

wiring.

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Solar Power

Hybrid solar and wind system. Image courtesy DOE

Permits

Installers are usually responsible for garnering permits
from city and/or county offices and will pass on the
costs to the consumer. They include 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 at the start with your PV contractor before
installation begins.

Building integrated PV. Image courtesy Kyoccnr

Choosing a Solar Installer
Setting up a PV system on a Superfund site is usually
done through a solar installer or contractor. They will
help size the PV system, get appropriate panels,
inverters, wiring, batteries, mounting, etc., and install
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

~	Renewable energy businesses and organizations
directory: www.enerqy.sourcequides.com

~	General Services Administration Contracts
Schedule: www.qsaelibrarv.qsa.gov
Search "206 3" for solar businesses

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 Check that you are comparing apples to
apples when looking at estimates. Do they
include the type of mounting requested,
type of solar PV, etc? Ask for kW output
estimates to be included in the bid.

Cheaper estimates may not include a
service or device or may have hidden costs.

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October 2007

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CLEANUP-CLEAN AIR

DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS

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 Wind turbines capture
kinetic energy in the wind and convert it into mechanical
energy as wind turns the turbine blades. Generators
convert this mechanical energy into electricity which can
be used on a Superfund cleanup site. Wind turbines
range in size from a few kilowatts to as large as several
megawatts. 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. The amount of power
produced by the turbine depends on the length of the

Basic Parts of a Small
Wind Electric System

Basic parts of a wind turbine. Image courtesy DOE EERE'
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 the height of
the tower and are generally weaker near the ground
because of frictional resistance of air flow with the surface
of the earth. To avoid turbulence and to 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/6 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 30 feet
above ground) could consider installing a small wind

Cleanup - Clean Air

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. The other type is the vertical axis turbine like
the eggbeater-style Darrieus model, which is less
commonly used. Blades for both types are made from
fiberglass, carbon fiber, carbon composites, or wood
so they 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.

Darrieus model wind
turbine. Image courtesy
Solcomhouse

October 2007

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Wind Power

Wind Turbine Terminology

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: DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS

Anemometer — Measures the wind speed and transmits
wind speed data to the controller.

Blades — Most turbines have either two or three blades.

Controller — The controller starts up the rotor in wind
speeds of about 8 to 16 miles-per-hour (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 — Usually an off-the-shelf induction generator
that may produce AC or DC electricity.

High-speed shafts — Drives 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 — Area swept by turbine blades.

Area Swept = tt * r2
r= length of one blade
Larger swept areas capture more wind energy.

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
Class

Wind Speed
mph

Wind Speed
m/s

Power Density
W/nr

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

Wind power class — Classification system of wind
speeds and the corresponding wind power.

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HiglMtaMd
Aran

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.

*Temis and wind power chart courtesy
DOE31

October 2007

Parts of a wind turbine. Image courtesy DOE30

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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.
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. In
other words, a small change in wind speed will
significantly affect the power output from the turbine.
Wind turbine developers can help properly install a
turbine that is well suited for conditions at your
Superfund site. Higher elevations have faster wind
speeds because there is less turbulence. 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.

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. Your site should be located on or near at
least one acre of open, rural land. More importantly,
there needs to be 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 Furthermore,
the actual wind resource for your site can still 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. Site your
wind turbine in an area where obstructions or future
obstructions like new buildings will have minimal effect
on the wind resource. Consult developers to determine
which turbines 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

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100.00
0.00

10 12 14 16 18 20 22 24 26
Wind Speed m/s

Wind turbine power curve. Courtesy De Montfort
Univerisity33

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DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS

Wind

Power

Funding Resources

Cost

A typical 10-kW wind turbine system will cost between
$25,000 and $35,000. A 10-kW turbine usually has a
blade diameter of about 20-25 feet and needs a tower
that is approximately 100 feet tall. 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

In many cases, the local zoning board must grant a
conditional use permit or a variance from the existing
code for a wind turbine building permit. Definitions may
vary from document to document; however, in general,
a variance refers to permission granted to a landowner
to build a structure normally prohibited by a zoning
ordinance. A conditional use permit allows a landowner
to build a structure if certain stipulations or conditions
are met. 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 will
receive the production incentive. Check
www.eere.enerqv.gov/repi for eligibility requirements.

Facilities must be in place by October 1, 2016.

Contact:

Christine Carter
christine.carter@qo.doe.qov
(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/faq/smsvslst.html

~ Windustry:

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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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

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 Surtico
\ /

—^

1 I l|l

0*6

N»

E-Kjracwi





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:

Most landfills with energy recovery systems will have a
flare to combust excess gas and for use during
equipment downtimes. 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.
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.

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 convert
LFG into electricity. The IC engine is the most
commonly used conversion technology in landfill gas
applications. IC engine projects typically have higher
rates of NOx emissions than other conversion
technologies which may cause a permitting issue.
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 to 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 to 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 Take
care to maintain LFG collection and electricity
generation parts and equipment as LFG may be
corrosive.

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/"S

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 landfill gas. The gas collection system
transports the gas to be treated and used to generate
electricity or as a heating fuel.

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 required.

Internal combustion engine I reciprocating engine Landfill gas to energy processes. Image courtesy Oregon
— This engine is used for large LFGE projects. It is the DePartment o Energy
most widely used electricity generation technology for
LFG. They are typically used for generation of 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. 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

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CLEANUP - CLEAN AIR

DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS |

Landfill Gas

MSW, other
organic waste,
moisture

blower, compressor

dryer

filters and scrubbers

sulfur, carbon
dioxide, solid
wastes

gaseous
emissions

heat,
steam

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

Landfill gas to energy recovery projects must comply
with federal regulations related to both the control of
landfill gas 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	• Wastewater

Building Permit

Land use Permit
Noise

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
from location to location but electricity generation
equipment account for about 30% to 70% of the capital
cost. Total capital cost includes the engine, auxiliary
equipment, interconnections, gas compressor,
construction, and engineering. Some landfills may
already have a gas collection system in place.48 Use the
following EPA resources to estimate landfill gas
production and costs 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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DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS

Anaerobic Digester Basics
Anaerobic digestion is the process of decomposition of
organic materials such as manure, wastewater
treatment facility residuals, agricultural wastes or food
processing wastes, by bacteria in an oxygen-free
environment. One of the products of anaerobic
digestion is biogas, which consists of 60%-7Q%
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.4M 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 organic matter. Digesters
work best with biomass that is greater than 85%
moisture by weight. Digesters can operate at two ideal
temperature ranges: mesophilic (95°F-105°F) which
best host mesophile bacteria, and thermophilic (125°F-
135°F), which best hosts thermophile bacteria. Waste
heat from electric 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. The digested manure can
be used as high-quality fertilizer. There is little change

Effluent
Storage

Anaerobic Digester

in the volume of the manure after it goes through the
digester. The manure 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.

Manure Source
and Collection System

Gas
Handling
System

The Digester System

The digester system components include:

Nutrient source — Includes animal manure,
wastewater treatment facility residuals, food waste,
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, boilers / steam engines, or microturbines
and generators can produce electricity from the
methane.

Flare or heat source — Excess methane is flared.
Methane can also be used directly for heating the

digester or other
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.

Electric

Generation

System

, Flare or
' Heat Source

Schematic of digester system. Image courtesy AgStar 50

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DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS

Anaerobic Digester

Conventional Types of Anaerobic Digesters

There are many different types of 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% to 10%, such as manure collected
from a flush system. Complete-mix digesters can be operated at
either the mesophilic 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.

Other Digester Designs51

-	Advanced integrated
pond system

-	Up-flow solids reactor

-	Fixed Film

-	Temperature-phased

-	Anaerobic filter reactor

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 a soiids 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.

Fixed-film digester. Image courtesy University
of Florida5"

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
wastes. An anaerobic 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.

Typical Digester Configuration Image courtesy U.S. EPA5"1

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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 95°F and
105°F in which methanogenic microbes thrive.

Thermophilic — Temperature range between 125°F
and 135°F 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 and
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:

These engines are used for large projects. When a
reciprocating engine is used, 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/kW-$1,100 per kW. The addition of a heat
recovery system, which captures the otherwise wasted
heat, adds between $75 per kW to $350 per kW.56
However, 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. Tcnpefature depmdenl
Anaerobic Digestion process. Image courtesy Penn State University

57

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DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS

Anaerobic Digester

Maintenance and Operations

Is Anaerobic Digestion Suitable for My
Site?

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 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 manure can be pumped long distances
Reduction in pathogens and weed seeds in
digested manure
Fly propagation reduced

Solids separation of digested manure—solids 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 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 design 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 during biogas combustion may be of
great 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 are generally not
a concern for other types of influent.

Cost	

AgStar estimates the installed cost of both a covered
lagoon and heated digester to range between $200 and
$450 per Animal Unit (1,000 lbs of live animal weight)
and a 3 to 7 year payback period when energy recovery
is employed. 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 2007, 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
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.g o v/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. Contact:
christine.carter@go.doe.gov or repi@ee.doe.gov

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 Biogas Svstems-

2004 Update.pdf

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CLEANUP - CLEAN AIR

DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS

EPA Region 9 Contacts

Jennifer Wang
(415) 947-4171
wanq.iennifer@epa.gov

Penny McDaniel
(415) 972-3178
mcdaniel.penelope@epa.gov

www.epa.gov/region09/cleanup-clean-air

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DIESEL EMISSIONS & GREENHOUSE GAS REDUCTIONS

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