2. This is also not intended to To make the best use of your solar energy
be a complete guide to all of system, the modules must have a clear
the renewable energy oppor- “view” of the sun for most or all of the
tunities available to agricul- day—unobstructed by trees, roof gables,
tural producers. Among the chimneys, buildings, and other features
options not covered here are of your home and the surrounding land-
hydro-electric generators, scape. Some potential sites for your sys-
geothermal energy, meth- tem may be bright and sunny during cer-
ane digesters, and various tain times of the day, but shaded during
other “biomass” energy sys- other times. Such shading may substan-
Photo courtesy of NREL.
tems. For more information tially reduce the amount of energy that
on digesters, see the ATTRA your system will produce.
publication Anaerobic Digestion of Animal
Wastes: Factors to Consider.
Solar Energy
Throughout the United States, people are
Related ATTRA showing increased interest in capturing
Publications the sun’s energy for their farm operations,
homes, and businesses. These systems
Biodiesel—A Primer allow you to produce your own electricity
Biodiesel: and heat water with no noise and no air
The Sustainability pollution while using a clean, renewable
Dimensions resource—the sun.
Ethanol Opportunities Photovoltaic (PV) shingles are an attractive solar
and Questions Is My Site Suitable for Solar Energy? option, since they look much like ordinary roofing
shingles, but they also generate electricity.
A well-designed solar energy system needs Photo courtesy of NREL.
Wind-Powered
Electric Systems for clear and unobstructed access to the sun’s
Homes, Farms, and rays for most or all of the day, throughout
Ranches: Resources the year. Most farms and ranches have roof-
In the United States, the sun is always in
tops or open, sunny locations that are well-
Solar-Powered the southern half of the sky but is higher
suited to solar energy, and you can make
Livestock Watering
an initial assessment yourself. If the loca- in the summer and lower in the win-
Systems
tion looks promising, your solar installer or ter. Usually, the best location for a solar
Freeze Protection equipment dealer can determine whether energy system is a south-facing roof, but
for Solar-powered your home or business can effectively use a roofs that face east or west may also be
Livestock Watering solar energy system. acceptable. Flat roofs also work well for
Systems solar electric systems, because solar mod-
Solar Greenhouses
The orientation of your system (the compass ules can be mounted flat on the roof facing
direction that your system faces) affects its
the sky or bolted on frames tilted toward
performance.
the south at an optimal angle. They can
also be attached directly to the roof as
In general, the sun
should be unob-
“PV shingles.”
structed from 9
If a rooftop can’t be used, your solar mod-
a.m. to 3 p.m. for
solar collectors. ules can also be placed on the ground,
PV applications either on a fixed mount or a “track-
are more sensi- ing” mount that follows the sun to orient
tive to minor solar
obstructions than
the modules. Other options include
solar thermal mounting structures that create covered
applications. parking, or that provide shade as win-
NCAT Illustration. dow awnings.
Page 2 ATTRA Renewable Energy Opportunities on the Farm
3. pastures, where electricity from power
lines is unavailable. PV is often much less
expensive than the alternative of extend-
ing power lines into these remote areas.
Depending on the depth of the well (if any)
and the volume of water needed, a simple
pumping system can often be installed
for as little as $2,500, including the cost
of a pump especia l ly designed for
PV power. For more information, see
the ATTRA publication Solar-Powered
Solar system installed at the Heifer Ranch in Livestock Watering Systems.
Perryville, Arkansas. Photo courtesy of NREL.
The basic building block of PV technol-
ogy is the solar “cell.” Multiple PV cells
are connected to form a PV “module,”
Photovoltaics the smallest PV component sold commer-
What is a solar electric, or photovoltaic, sys- cially. Modules range in power output from
tem? Photovoltaic (PV) systems convert sun- about 10 watts to 300 watts. A PV system
light directly to electricity. They work any connected or “tied” to the utility grid has
time the sun is shining, but more electric- these components:
ity is produced when the sunlight is more
intense and strikes the PV modules directly • One or more PV modules, which are
(as when rays of sunlight are perpendicular connected to an inverter
to the PV modules). Unlike solar thermal • Inverter, which converts the sys-
systems for heating water, PV does not use tem’s direct-current (DC) electricity
the sun’s heat to make electricity. Instead, to alternating current (AC)
electrons freed by the interaction of sun- • Batteries (optional) to provide
light with semiconductor materials in PV energy storage or backup power in
cells are captured in an electric current. case of a power interruption or out-
PV allows you to produce electricity—with- age on the grid.
out noise or air pollution—from a clean,
renewable resource. A PV system never
runs out of fuel, and it won’t increase U.S.
oil imports. Many PV system components
are manufactured right here in the United
States. These characteristics could make PV
technology the U.S. energy source of choice
for the 21st century.
Solar electric power comes in very handy
on farms and ranches, and is often the most
cost-effective and low-maintenance solution
at locations far from the nearest utility line.
PV can be used to power lighting, electric
fencing, small motors, aeration fans, gate-
openers, irrigation valve switches, automatic
supplement feeders. Solar electric energy
can even be used to move some sprinkler
irrigation systems.
AC electricity is compatible with the utility
PV systems are also extremely well-suited grid. It powers our lights, appliances, com-
for pumping water for livestock in remote puters, and televisions.
www.attra.ncat.org ATTRA Page 3
4. Cost/Savings electric bills up front. Your monthly electric
A photovoltaic (PV) system can be a substan- bills will go down, but the initial expense of
tial investment. Cost-effectiveness will depend PV may be significant. By fi nancing your
on system installation cost, system perfor- PV system, you can spread the cost over
mance, and local electric rates. As with any many years, and rebates can also lighten
investment, careful planning will help you your financial load.
make the right decisions for your farm, home, The value of your PV system’s electricity
or business. Before you decide to buy a PV depends on how much you pay for elec-
system, there are some things to consider. tricity now and how much your utility will
First, PV produces power intermittently pay you for any excess power that you gen-
erate. With net metering, the PV system’s
because it works only when the sun is shin-
electricity is metered back to the utility,
ing. This is not a problem for PV systems
which offsets the electricity coming from
connected to the utility grid, because any
the utility. You can use the calculation box
additional electricity required is automati-
on this page to estimate how much electric-
cally delivered to you by your utility. In the
ity your PV system will produce and how
case of non-grid, or stand-alone, PV sys-
much that electricity will be worth. Actual
tems, batteries can be purchased to store
energy production from your PV system will
energy for later use. Second, if you live near
vary by up to 20 percent from these figures,
existing power lines, PV-generated electric-
depending on your geographic location, the
ity is usually more expensive than conven-
angle and orientation of your system, the
tional utility-supplied electricity. Although
quality of the components, and the quality
PV now costs less than 1 percent of what it
of the installation. Also, you may not get
did in the 1970s, the amortized price over
full retail value for excess electricity pro-
the life of the system is still about 25 cents
duced by your system on an annual basis,
per kilowatt-hour. This is double to qua-
even if your utility does offer net metering.
druple what most people pay for electricity
Be sure to discuss these issues with your
from their utilities. A solar rebate program
PV provider. Request a written estimate of
and net metering can help make PV more
the average annual energy production from
affordable, but neither can match today’s
the PV system. However, even if an esti-
price for utility electricity—in most cases.
mate is accurate for an average year, actual
Finally, unlike the electricity you purchase electricity production will fluctuate from
monthly from a utility, PV power requires year to year because of natural variations
a high initial investment. This means that in weather and climate.
buying a PV system is like paying years of
How Much Does a PV System Cost?
How much energy will a grid-connected PV system produce?*
No single answer applies in every case.
System Size 1-kW 2-kW 3-kW 4-kW 5-kW But solar rebates and other incentives
Seattle, WA 970 1940 2910 3880 4850 will always reduce the cost. Your price
Sacramento, CA 1399 2799 4198 5597 6996 depends on a number of factors, includ-
Boulder, CO 1459 2917 4376 5834 7293 ing whether your home is under construc-
tion and whether PV is integrated into the
Minneapolis, MN 1286 2571 3857 5142 6428
roof or mounted on top of an existing roof.
Des Moines, IA 1292 2584 3876 5168 6459 The price also depends on the PV system
Houston, TX 1220 2440 3660 4879 6099 rating, manufacturer, retailer, and installer.
Pittsburgh, PA 1099 2197 3296 4395 5494 The size of your system may be the most
Jacksonville, FL 1286 2571 3857 5142 6428 significant factor in any measurement of
costs versus benefits. A 2-kilowatt system
*Estimated annual output in kWh/year (source: PV WATTS). A typical home that meets nearly all the needs of a very
uses an average of 9,400 kWh per year. Contact your utility to request a print- energy-efficient home will likely cost $8 to
out of your last 12 months of electrical energy consumption.
$10 per watt. At the high end, a 5-kilowatt
Page 4 ATTRA Renewable Energy Opportunities on the Farm
5. operations that have signifi-
Area of Solar Array Needed in Square Feet cant space heating require-
PV Module ments. For example, mod-
Efficiency PV Capacity Rating (Watts) ern pig and poultry farms
(%) raise animals in enclosed
100 250 500 1,000 2,000 4,000 10,000 buildings with carefully
4 30 75 150 300 600 1,200 3,000 controlled temperatures
8 15 38 75 150 300 600 1,500 that help maximize animal
health and growth. In addi-
12 10 25 50 100 200 400 1,000
tion, these facilities often
16 8 20 40 80 160 320 800 have high ventilation needs
For example, to generate 2,000 watts from a 12%-efficient system, in order to remove moisture,
you need 200 square feet of roof area. toxic gases, odors, and dust.
Properly designed solar
system that completely meets the energy space-heating systems can help meet both
needs of a large conventional home can cost of these needs.
$30,000 to $40,000 installed, or $6 to $8
per watt. These prices are rough estimates; Solar Greenhouse Heating
your costs depend on your system’s configu-
Solar greenhouses are designed to collect
ration, your equipment options, and other
solar energy during sunny days and also to
factors. Your local PV dealers can give you
store heat for use at night or during peri-
more accurate cost information.
ods when it is cloudy. They can either stand
alone or be attached to houses or barns. A
PV works best in an energy-efficient building. solar greenhouse may be an underground
So, measures such as adding insulation and pit, a shed-type structure, or a quonset hut.
sealing air leaks, as well as purchasing energy-
efficient lighting, and appliances, are essential
Large-scale producers use free-standing
to reduce your building’s overall electricity use solar greenhouses, while attached structures
before installing a PV system. are primarily used by home-scale growers.
Solar greenhouses differ from conventional
greenhouses in the following four ways.
Net Metering Solar greenhouses:
Utilities are required to offer net metering
in 40 states and the District of Columbia. In • have glazing oriented to receive
net metering, the customer is billed for the ma x imum sola r heat dur ing
net electricity purchased from the utility over the winter
the entire billing period—that is, the differ- • use heat-storing materials to retain
ence between the electricity coming from the solar heat
power grid and the electricity generated by • have large amounts of insulation
the PV system. The benefits of net meter- where there is little or no direct
ing to consumers are especially significant sunlight
in areas with high retail electric rates. Utili-
ties also benefit because the solar-generated • use glazing material and glazing
energy often coincides with their periods of installation methods that minimize
“peak” demand for electricity. heat loss
• rely primarily on natural ventilation
For state-by-state net metering information,
for summer cooling
see Net Metering Rules for Energy Effi-
ciency at www.dsireusa.org Passive solar greenhouses are often good
choices for small growers, because they are
Solar Space Heating a cost-efficient way for farmers to extend
Solar space-heating systems can be used the growing season. In colder climates
in livestock, dairy, and other agriculture or in areas with long periods of cloudy
www.attra.ncat.org ATTRA Page 5
6. weather, solar heating may need to be sup-
plemented with a gas or electric heating
system to protect plants against extreme
cold. Active solar greenhouses use sup-
plemental energy to move solar heated air
or water from storage or collection areas
to other regions of the greenhouse. Use
of photovoltaic heating systems for green-
houses is generally not cost-effective unless
you are producing high-value crops.
For more information on greenhouses, see
the ATTRA publication Solar Greenhouses. PV provides year round solar-assisted power to a
domestic water-heating system for this residential
addition in Rhode Island. Photo courtesy of NREL.
Solar Crop Drying
Farmers have been using the sun to dry such as a water-glycol antifreeze mixture,
crops for centuries. You can take advantage in collectors most commonly mounted on
of this technology simply by allowing crops a roof. The heated water is then stored
to dry naturally in the field, or by spread- in a tank similar to a conventional gas or
ing grain and fruit out in the sun after har- electric water tank. Then, when water is
vesting. Today’s solar dryers are designed drawn from the water heater, it is replaced
to provide protection from insects, rodents, with the solar-heated water from that tank.
birds, as well as weather. A basic solar dyer Some systems use an electric pump to cir-
consists of an enclosure or shed, screened culate the fluid through the collectors.
drying trays or racks, and a solar collec-
Solar water heaters can operate in any cli-
tor. The design of a solar crop drying sys-
tem needn’t be complicated—it can simply mate. Performance varies depending, in
be a glazed box with a dark-colored inte- part, on how much solar energy is avail-
rior to collect solar energy, which heats the able at the site, but also on the temper-
air inside the box. The heated air is then ature of incoming water. The colder the
moved through the crop material either by water, the more efficiently the system oper-
natural convection or with a fan. ates. In almost all climates, you will need a
conventional backup system. In fact, many
For more information, see Solar Energy building codes require you to have a con-
Applications for Farms and Ranches ventional water heater as the backup.
at www.eere.energy.gov/consumer/your_
workplace/farms_ranches/index.cfm/ Types of Solar Water Heaters
mytopic=30006
There are four basic types of solar water-
heating systems available. These systems
Solar Water Heating share three similarities: a glazing (typi-
Water heating can account for as much as cally glass) over a dark surface to gather
25 percent of a typical family’s energy costs solar heat; one or two tanks to store hot
and up to 40 percent of the energy used in water; and associated plumbing with or
a typical dairy operation. A properly sized without pumps to circulate the heat-trans-
solar water-heating system could cut those fer fluid from the tank to the collectors and
costs in half. Hot water is also needed for back again.
pen and equipment cleaning and a host of Draindown systems pump water from the
other agricultural uses. hot water tank through the solar collectors,
where it is heated by the sun and returned
Solar Water Heater Basics to the tank. Valves automatically drain
Solar water heating systems use the sun to the system when sensors detect freezing
heat either water or a heat-transfer fluid, temperatures.
Page 6 ATTRA Renewable Energy Opportunities on the Farm
7. Antifreeze closed-loop systems rely on an
antifreeze solution to operate through cold
winter months. Antifreeze solutions are sep-
arated from household water by a double-
walled heat exchanger.
Breadbox batch systems are passive sys-
tems in which the storage tank also func-
tions as the collector. One or two water
tanks, painted black, are placed in a well-
insulated box or other enclosure that has
a south wall made of clear plastic or glass
and tilted at the proper angle. This allows
the sun to shine directly on the tank and
heat a “batch” of
water. An insulated
cover can provide
freeze protection.
Sizing Your
Draindown solar water system.
System
Illustration: North Carolina Solar Center. Just as you have to
choose a 30, 40-, or
50-gallon conven-
Drainback systems use a separate plumb- tional water heater,
ing line, fi lled with fluid, to gather the sun’s you need to deter-
heat. These systems operate strictly on grav- mine the right size Breadbox batch solar water system.
ity. When the temperature is near freezing, solar water heater Illustration: North Carolina Solar Center.
the pump shuts off and the transfer fluid to install. Sizing a
drains back into the solar storage tank. solar water heater involves determining the
total collector area and the storage volume
required to provide 100 percent of your
building’s hot water during the summer.
Solar equipment experts use worksheets or
special computer programs to assist you in
determining how large a system you need.
Solar storage tanks are usually 50-, 60-,
80-, or 120-gallon capacity. A small (50-
to 60-gallon) system is sufficient for one to
three people, a medium (80-gallon) sys-
tem is adequate for a three- or four-person
household, and a large (120-gallon) system
is appropriate for four to six people.
Cost/Savings
How much does a solar water-heating
system cost?
A solar water-heating system can cost
anywhere from $1,500 to more than
Drainback solar water system. $5,000. Cost depends on a number of vari-
Illustration: North Carolina Solar Center. ables, such as:
www.attra.ncat.org ATTRA Page 7
8. • the presence or type of freeze lower the temperature of the hot water you
protection use reduces the size and cost of your solar
• size of family, business, or agricul- water heater.
tural operation to be served Good first steps are installing low-flow show-
• size and type of solar system erheads or flow restrictors in faucets, insu-
lating your current water heater, and insu-
• type of roof on which the collector is
lating any hot water pipes that you can see.
to be installed
• building code requirements You’ll also want to make sure your site has
enough available sunshine to meet your
• installation costs needs efficiently and economically. Your
The less expensive solar water-heating sys- local solar equipment dealer can perform a
tems lack freeze protection and are applica- solar site analysis for you or show you how
ble primarily for summer recreation homes. to do your own.
A solar energy supplier or installer in your
area can help you determine specific costs Remember: Local zoning laws or covenants
may restrict where you can place your collec-
for your system.
tors. Check with your city and county to learn
about any restrictions.
How Much Will I Save?
Savings from solar water heating depend
on specific climate, conventional fuel costs,
Be a Smart Consumer
and other factors. However, a study by the Take the same care in choosing a solar
Florida Solar Energy Center (FSEC) con- water heater that you would in the purchase
cluded that solar water heaters could reduce of any major appliance. Your best protection
water heating costs by as much as 85 per- is to consider only certified and labeled sys-
cent annually, compared to the cost of an tems. One such label is put on by the Solar
electric water heater. Paybacks vary widely, Rating & Certification Corporation (SRCC),
but you can expect a simple payback of four a nonprofit, independent third-party organi-
to eight years on a well-designed and prop- zation formed by the state energy officials,
erly installed solar water heater. (Simple and consumer advocates to certify and rate
payback is the length of time required to solar water heaters.
recover your investment through reduced or Find out if the manufacturer offers a
avoided energy costs.) warranty, and, if so, what the warranty
If you are constructing a new building or covers and for how long. If the dealer you
undergoing a major renovation, the econom- are buying the equipment from goes out
ics are even more attractive. The cost of of business, can you get support and parts
including the price of a solar water heater in from the manufacturer, or from a local
plumbing contractor?
a new 30-year mortgage is usually between
$13 and $20 per month. The portion of Make sure that the workers who are actually
the federal income tax deduction for mort- installing the system are qualified to do the
gage interest attributable to the solar system work. In many states, an installer of a solar
reduces that amount by about $3 to $5 per water heater must have a plumbing license.
month. If your fuel savings are more than Ask the installation contractor for references
$15 per month, the investment in the solar and check them. When the job is finished,
water heater is profitable immediately. have the contractor walk you through the sys-
tem so you are familiar with the installation.
First Things First And be sure that an owner’s manual with
Before investing in any solar energy system, maintenance instructions is included as part
of the package.
it is more cost-effective to invest in energy-
efficiency measures for your building. A solar water heater is a long-term invest-
Taking steps to use less hot water and to ment that will save you money and energy
Page 8 ATTRA Renewable Energy Opportunities on the Farm
9. for many years. Like other renewable energy for fuel cells; $200/kW for microturbines;
systems, solar water heaters minimize the no maximum specified for other technol-
environmental effects of enjoying a comfort- ogies. (Subject to funding limitations.)
able, modern lifestyle. In addition, they pro- Effective date: 1/1/2006. Expiration date:
vide a hedge against energy price increases, 12/31/2007.
help reduce our dependence on foreign oil,
and are investments in everyone’s future. Renewable Energy Systems
and Energy Efficiency
Financial Incentives Improvements Program
The following information identifies federal www.rurdev.usda.gov/rd/farmbill9006
fi nancial incentives. For more information resources.html
on these, as well as state incentives, see the This federal grant program applies to solar
Database of State Incentives for Renewable water heating, solar space heating, photo-
Energy (DSIRE) at www.dsireusa.org. voltaics, wind, biomass, geothermal elec-
tric, geothermal heat pumps, hydrogen,
Residential Solar and Fuel Cell anaerobic digestion, renewable fuels, and
A
Tax Credit fuel cells in commercial and agricultural solar water
Enacted by the Energy Policy Act of 2005 applications. Grants amount to 25 percent heater is a
(Section 1335), this credit applies to solar of eligible project costs; guaranteed loans long-term
water heating, photovoltaics, and fuel cells. are 50 percent of eligible project costs
investment that will
Incentive amount is 30 percent, with max- (pending). Maximums are $500,000 per
renewable-energy project for grants, and save you money and
imums of $2,000 for photovoltaics and
solar water heating and $500 per 0.5 kW $10 million for guaranteed loans. (Sub- energy for many
for fuel cells. (Subject to funding limita- ject to funding limitations.) Effective date: years.
tions.) Effective date: 1/1/2006. Expiration 10/5/2004. Expiration date: 10/1/2007.
Date: 12/31/2007. For more information on
the Energy Policy Act of 2005 and what it Wind Energy
means to you, visit the American Council More and more people are considering
for an Energy Efficient Economy (ACEEE) wind energy as they look for affordable and
at www.aceee.org/energy/legsttus.htm. For a reliable sources of electricity. Small wind
summary of energy efficiency tax incentives electric systems can make a significant
in the Energy Policy Act of 2005, click on contribution to our nation’s energy needs.
www.aceee.org/press/Tax_incentive05.pdf. Although wind turbines large enough to
provide a significant portion of the elec-
Business Energy Tax Credit tricity needed by the average U.S. farm or
Enacted by the Energy Policy Act of 2005 home generally require one acre of prop-
(Section 1336 - 1337), this credit applies erty or more, approximately 21 million
U.S. homes are built on one-acre and larger
to renewables including solar water heat-
sites, and 24 percent of the U.S. population
ing, solar space heating, solar thermal elec-
lives in rural areas. Many of these rural
tric, solar thermal process heat, geothermal
areas, particularly in the western U.S.,
electric, fuel cells, and solar hybrid light-
also have sufficient wind speeds to make
ing for commercial and industrial applica-
wind an attractive alternative.
tions. The industrial tax credit is currently
10 percent for geothermal electric and This section will provide you with basic
solar; from January 1, 2006, until Decem- information about small wind electric sys-
ber 31, 2007, the credit is 30 percent for tems to help you decide if wind energy will
solar, solar hybrid lighting, and fuel cells, work for you. Note that this discussion only
and 10 percent for microturbines. The covers small-scale wind electric systems.
geothermal credit remains at 10 percent. Two other options, not covered here, are of
Maximum incentive is $550 per 0.5 kW great importance to agricultural producers:
www.attra.ncat.org ATTRA Page 9
10. First, landowners in windy locations often lower your electricity bill, help you avoid
lease farmland to developers who want to the high costs of having utility power lines
install large wind turbines or wind farms. extended to remote locations, prevent power
These “turnkey” operations, where the interruptions, and it is non-polluting.
landowner receives an annual payment,
can generate an attractive income stream How Do Wind Turbines Work?
while often allowing farming and livestock
Wind is created by the unequal heating of
grazing to continue in close proximity to the
the Earth’s surface by the sun. Wind tur-
wind turbines. For information about sit-
bines convert the kinetic energy in wind
ing large-scale wind turbines on your land,
into mechanical power that runs a genera-
see Electricity from the Wind: What Land-
tor to produce clean electricity. Today’s tur-
owners Should Know. (www.eere.energy.gov/
bines are versatile modular sources of elec-
windandhydro/windpoweringamerica/docs/
tricity. Their blades are aerodynamically
what_landowners_should_know.doc)
designed to capture the maximum energy
Second, farmers in some parts of the coun- from the wind. The wind turns the blades,
try have formed cooperatives, pooling their which spin a shaft connected to a generator
fi nancial resources in order to purchase that makes electricity.
and operate their own large wind turbines.
For more information, see Community Wind
Financing, a handbook from the Environ-
mental Law & Policy Center. (www.elpc.org)
Wind turbines operate in harmony with farming and
ranching. Photo courtesy of NREL.
Is Wind Energy Practical for Me?
A small wind energy system can provide
you with a practical and economical source
of electricity if:
• your property has a good wind
resource
• your farm, home, or business is
located on at least one acre of land
in a rural area
Homeowners, ranchers, and small businesses can use wind-generated electricity
to reduce their utility bills. This grid-connected system installed in Norman, Okla- • your local zoning codes or covenants
homa, reduces the owner’s utility bill by $100 per month. Photo courtesy of NREL. allow wind turbines
• your average electricity bills are
$150 per month or more
Why Should I Choose Wind? • your property is in a remote loca-
Under certain circumstances, wind energy tion that does not have easy access
systems can be a cost-effective renewable to utility lines
energy system. Depending on your wind • you are comfortable with long-term
resource, a small wind energy system can investments
Page 10 ATTRA Renewable Energy Opportunities on the Farm
11. Is There Enough Wind at My Site? caution should be used because local ter-
rain influences and other factors may cause
Does the wind blow hard and consistently
the wind speed recorded at an airport to
enough at my site to make a small wind
turbine system economically worthwhile? be different from your particular location.
That is a key question and not always eas- Airport wind data are generally measured
ily answered. The wind resource can vary at heights about 20–33 feet (6–10 meters)
significantly over an area of just a few miles above ground.
because of local terrain influences on the Average wind speeds increase with height
wind flow. Yet, there are steps you can take and may be 15–25 percent greater at a
that will go a long way towards answering typical small wind turbine hub-height of
the above question. 80 feet (24 meters) than those measured at
As a first step, consult resources such as the airport anemometer heights. The National
National Wind Technology Center website at Climatic Data Center collects data from air-
www.nrel.gov/wind and DOE’s Wind Power- ports in the United States and makes wind
ing America website at www.eere.energy.gov/ data summaries available for purchase.
windandhydro/windpoweringamerica to esti- Summaries of wind data from almost
mate the wind resource in your region. The 1,000 U.S. airports also are included in
highest average wind speeds in the United Wind Energy Resource Atlas of the United
States are generally found along seacoasts, States, available online at http://rredc.nrel.
on ridgelines, and on the Great Plains; gov/wind/pubs/atlas.
however, many areas have wind resources Another useful indirect measurement of the
strong enough to power a small wind tur- wind resource is the observation of an area’s
bine economically. vegetation. Trees, especially conifers or
Another way to indirectly quantify the wind evergreens, can be permanently deformed
resource is to obtain average wind speed by strong winds. This deformity, known as
information from a nearby airport. However, “flagging,” has been used to estimate the
www.attra.ncat.org ATTRA Page 11
12. average wind speed for an area. For more may be able to obtain information on the
information on flagging, you may want to annual output of the system and also wind
obtain A Siting Handbook for Small Wind speed data if available.
Energy Conversion Systems, by H. Wegley,
J. Ramsdell, M. Orgill & R. Drake, Report Zoning Issues
No. PNL-2521, available from National
Agricultural producers generally have
Technical Information Service at www.ntis.
greater freedom than residential homeown-
gov or 703-605-6585.
ers in what they do on their own, agricul-
turally-zoned land. Nonetheless, before you
invest in a wind energy system, you should
research potential obstacles. Some jurisdic-
tions, for example, restrict the height of the
structures permitted in residentially zoned
areas, although variances are often obtain-
able. Most zoning ordinances have a height
limit of 35 feet. You can find out about the
zoning restrictions in your area by calling
the local building inspector, board of super-
visors, or planning board. They can tell you
if you will need to obtain a building permit
and provide you with a list of requirements.
In addition to zoning issues, your neighbors
might object to a wind machine that blocks
their view, or they might be concerned
about noise. Most zoning and aesthetic con-
cerns can be addressed by supplying objec-
tive data. For example, the ambient noise
level of most modern residential wind tur-
bines is around 52 to 55 decibels. This
Flagging, the effect of strong winds on area vegetation, can help determine area means that while the sound of the wind tur-
wind speeds. bine can be picked out of surrounding noise
if a conscious effort is made to hear it, a
residential sized wind turbine is no noisier
Direct monitoring by a wind resource mea- than your average refrigerator.
surement system at a site provides the
clearest picture of the available resource.
What Size Wind Turbine Do I Need?
A good overall guide on this subject is the
Wind Resource Assessment Handbook, which The size of the wind turbine you need
is available online at www.nrel.gov/docs/ depends on your application. Small tur-
legosti/fy97/22223.pdf. Wind measure- bines range in size from 100 watts to 100
ment systems are available for costs as low kilowatts. The smaller or “micro” (100–
as $600 to $1,200. This expense may or 500-watt) turbines are used in a variety of
may not be hard to justify, depending on applications such as charging batteries for
the exact nature of the proposed small wind recreational vehicles and sailboats. One- to
turbine system. The measurement equip- 10-kW turbines can be used in applications
ment must be set high enough to avoid tur- such as pumping water. Wind energy has
bulence created by trees, buildings, and been used for centuries to pump water and
other obstructions. The most useful read- grind grain. Although mechanical windmills
ings are those taken at hub-height, the ele- still provide a sensible, low-cost option for
vation at the top of the tower where the wind pumping water in low-wind areas, farmers
turbine is going to be installed. If there is a and ranchers are finding that wind-electric
small wind turbine system in your area, you pumping is a little more versatile and they
Page 12 ATTRA Renewable Energy Opportunities on the Farm
13. can pump twice the volume for the same Grid-Connected Systems
initial investment. In addition, mechanical
In grid-connected systems, the only addi-
windmills must be placed directly above the
tional equipment required is a power con-
well, which may not take the best advantage
ditioning unit (inverter) that makes the tur-
of available wind resources. Wind-electric
bine output electrically compatible with
pumping systems can be placed where the
the utility grid. Usually, batteries are not
wind resource is the best and connected to
needed. Small wind energy systems can
the pump motor with an electric cable.
be connected to the electricity distribution
Turbines used in residential applications system and are called grid-connected sys-
can range in size from 400 watts to 100 kW tems. A grid-connected wind turbine can
(100 kW for very large loads), depending on reduce your consumption of utility-supplied
the amount of electricity you want to gener- electricity for lighting, appliances, and
ate. For residential applications, you should electric heat. If the turbine cannot deliver
establish an energy budget to help defi ne the amount of energy you need, the utility
the size of turbine you will need. Because makes up the difference. When the wind
energy efficiency is usually less expensive system produces more electricity than the
than energy production, making your house household requires, the excess is sent or sold
more energy-efficient fi rst will probably be to the utility. Grid-connected systems can be
more cost-effective and will reduce the size practical if the following conditions exist:
of the wind turbine you need. Wind turbine
• You live in an area with average
manufacturers can help you size your sys-
annual wind speed of at least 10
tem based on your electricity needs and the
mph (4.5 m/s)
specifics of local wind patterns.
• Utility-supplied electricity is expen-
Wind Turbine Sizes sive in your area (about 10 to 15
Size Height Diameter cents per kilowatt-hour).
1 kW 30-100 ft. 4-8 ft. • The utility’s requirements for con-
10 kW 60-120 ft. 23-25 ft. necting your system to its grid are
not prohibitively expensive.
100 kW 80-120 ft. 56-60 ft.
Examples. Specific component sizes vary by manufacturer.
• There are good incentives for the
sale of excess electricity or for the
A typical home uses approximately 9,400 purchase of wind turbines.
kilowatt-hours (kWh) of electricity per year Federal regulations (specifically, the Pub-
(about 780 kWh per month). Depending on lic Utility Regulatory Policies Act of 1978,
the average wind speed in the area, a wind or PURPA) require utilities to connect with
and purchase power from small wind energy
turbine rated in the range of 5 to 10 kilo-
systems. However, you should contact your
watts (kW) would be required to make a
utility before connecting to their distribu-
significant contribution to this energy need.
tion lines to address any power quality and
The manufacturer can provide you with the
expected annual energy output of the tur-
bine as a function of annual average wind
speed. The manufacturer will also provide
information on the maximum wind speed
at which the turbine is designed to operate
safely. Most turbines have automatic over-
speed-governing systems to keep the rotor
from spinning out of control in very high
winds. This information, along with your
local wind speed and your energy budget,
will help you decide which size turbine will
best meet your electricity needs. A grid-connected wind turbine can reduce your consumption of utility-supplied electricity.
www.attra.ncat.org ATTRA Page 13
14. safety concerns. Your utility can provide This federal grant program applies to solar
you with a list of requirements for connect- water heating, solar space heating, photovol-
ing your system to the grid. The American taics, wind, biomass, geothermal electric,
Wind Energy Association (www.awea.org) geothermal heat pumps, hydrogen, anaer-
is another good source for information on obic digestion, renewable fuels, and fuel
utility interconnection requirements. cells in commercial and agricultural appli-
cations. Grants amount to 25 percent of eli-
What Do Wind Systems Cost? gible project costs; guaranteed loans are 50
A small turbine can cost anywhere from percent of eligible project costs (pending).
$3,000 to $35,000 installed, depending Maximums are $500,000 per renewable-
on size, application, and service agree- energy project for grants, and $10 million
ments with the manufacturer. A general for guaranteed loans. (Subject to funding
rule of thumb for estimating the cost of a limitations.) Effective date: 10/5/2004.
residential turbine is $3,000 per kilowatt Expiration date: 2007.
for systems up to 10 kW. Smaller wind
systems are more costly per kilowatt of Wind Energy Production Tax Credit
installed capacity. Wind energy becomes The Energy Policy Act of 2005 extends the
more cost-effective as the size of the tur- tax credit for wind energy systems. The tax
bine’s rotor increases. Although small tur- credit amounts to 1.9 cents-per-kilowatt-
bines cost less in initial outlay, they are hour (kWh) tax credit for electricity gener-
proportionally more expensive. The cost of ated with wind turbines over the fi rst ten
an installed residential wind energy system years of a project’s operations. (Subject
that comes with an 80-foot tower, batteries, to funding limitations.) Expiration date:
and inverter, typically ranges from $13,000 12/31/2007.
to $40,000 for a 3- to 10-kW wind turbine.
Although wind energy systems involve a sig-
nificant initial investment, they can be com-
Renewable Fuels for
petitive with conventional energy sources Transportation
when you account for a lifetime of reduced Transportation accounts for 65 percent of
or avoided utility costs. The length of the U.S. oil consumption and is the predomi-
payback period—the time before the savings nant source of air pollution. However, there
resulting from your system equal the cost are safe, environmentally friendly alter-
of the system itself—depends on the system native fuels that can substitute for gaso-
you choose, the wind resource on your site, line and diesel or be blended with them to
electricity costs in your area, and how you reduce toxic air emissions. Using renewable
use your wind system. fuels also reduces greenhouse gas buildup,
Photo courtesy of NREL.
dependence on imported oil, and trade defi-
Financial Incentives cits, while supporting local agriculture and
The following information identi- rural economies.
fies federal financial incentives.
For more information on these, What are renewable fuels?
as well as state incentives, see the Renewable fuels are not petroleum-based,
Database of State Incentives for so they’re cleaner burning. Renewable
Renewable Energy (DSIRE) at fuels include:
www.dsireusa.org.
Biodiesel – a low-polluting diesel alterna-
Renewable Energy Systems tive fuel made from vegetable oils, animal
and Energy Efficiency fats, and even recycled cooking greases.
Improvements Program Ethanol – an alcohol-based fuel derived
www.rurdev.usda.gov/rd/farmbill/ from crops, usually corn, barley, and wheat.
9006resources.html Ethanol can be blended with gasoline in
Page 14 ATTRA Renewable Energy Opportunities on the Farm
15. varying concentrations. E85, for example, heavy-duty AFV applications include tran-
is a blend of 85 percent ethanol and 15 sit buses, airport shuttles, delivery trucks
percent gasoline. and vans, school buses, refuse haulers, and
street sweepers.
The Energy Policy Act of 1992 (EPAct)
requires state and federal government fleets
to purchase renewable fuel vehicles for three- AFV Types
quarters of their new light-duty vehicle pur- Flex-Fuel Vehicles can be fueled with gaso-
chases. Additionally, renewable fuel provider line or, depending on the vehicle, with either
fleets covered by EPAct are required to pur- methanol (M85) or ethanol (E85). The vehi-
chase renewable fuel vehicles for 90 percent cles have one tank and can accept any mix-
of their new vehicle purchases. Local govern- ture of gasoline and the alternative fuel.
ment and private fleets are not covered by this Bi-fuel or Dual-Fuel Vehicles have two
rule, but the U.S. Department of Energy has tanks—one for gasoline and one for either
the authority to include them at a future date. natural gas or propane, depending on the
Ethanol is an excellent renewable fuel (the vehicle. The vehicles can switch between
standard is E85, a blend of 85 percent eth- the two fuels.
anol and 15 percent gasoline). Flexible-fuel Dedicated Vehicles are designed to be fueled
vehicles designed to use E85 or other gaso- only with an alternative fuel. Electric vehicles
line mixtures include modified oxygen sen- are a special type of dedicated vehicle.
sors and different seals in the fuel system.
Because ethanol has less energy per gal- Hybrid Vehicles combine the best features of
lon than gasoline, E85 vehicles also need two different energy sources, one of which is
larger fuel tanks to keep the same range. electric power. Until alternative fuels really
E85 flex-fuel vehicles qualify as alternative catch on, hybrids can be a good choice.
fuel vehicles and Daimler-Chrysler, Ford,
and General Motors all offer several mod- Fueling
els designed to use E85 or gasoline for the Alternative fuel stations are becoming
same price as gasoline-only models. Today, increasingly popular across the country, as
92 state and alternative fuel provider fleets more consumers and agencies turn to clean
use E85 flex-fuel vehicles to help them meet fuels. Find out where these stations are
their EPAct requirements. using DOE’s Alternative Fuel Station Loca-
tor at http://afdcmap.nrel.gov/locator.
Alternative-Fuel Vehicles
Alternative fuel vehicles (AFVs) can use Ethanol and Local Resources
renewable fuel instead of gasoline or
From Corn: In the United
diesel fuel. AFVs range in size and shape,
States, ethanol, also known as
from small commuter cars to large 18-
grain alcohol, is made from the
wheeler trucks. A number of automobile
starch in kernels of field corn.
manufacturers offer light-duty vehicles for
(Field corn is otherwise predom-
personal transportation.
inantly used as animal feed; in
AFVs are well-suited for fleets in certain 2005 ethanol production used
“niche” markets. Taxi fleets, for example, 15 percent of the feed corn
are high-mileage vehicles that drive fairly crop). Modern fuel ethanol tech-
centralized routes and may benefit from nology is highly sophisticated
using a less expensive alternative fuel such and efficient, and the process
as natural gas or propane. Local delivery is similar to making alcoholic
fleets with low mileage, and high-use vehi- beverages. Starch is converted
cles that frequently idle in traffic or must into sugars, the sugars are
often start and stop, may be good candi- fermented to a “beer,” and then
dates for electric vehicles. Medium- and the beer is distilled to make Photo courtesy of NREL.
www.attra.ncat.org ATTRA Page 15
16. pure ethanol. Of U.S. blended in one of out every eight gallons of
corn ethanol production, gasoline for pollution reduction.
about half is in wet-mill
Ethanol made from corn is slightly more
plants and half is in dry-
expensive than gasoline. To encourage eth-
mill plants. The former
anol use, however, the federal government
are typically large opera-
exempts 5.3 cents per gallon of 10percent
tions that produce etha-
ethanol blend (53 cents per gallon of etha-
nol along with a slate of
nol) of the 18.3 cents per gallon federal
food products such as
fuel excise tax. In effect since 1979, this
corn sweeteners, corn
exemption makes ethanol competitive for
syrup, corn oil, and glu-
fuel additive use. Several states also pro-
Corn is a common feedstock for ethanol, provid- ten feed. The latter are
vide additional incentives. The federal sub-
ing an economic boon for agricultural states. typically smaller facili-
sidy, however, is more than offset by reduced
Photo courtesy of NREL. ties that produce ethanol
agricultural price support payments, and
as their primary product
increased employment taxes for an estimated
and a high-protein ani-
net taxpayer savings of about $3.6 billion per
mal feed known as distillers dried grains as
year. The U.S. Department of Agriculture
a co-product. The dry-mill plants are typi-
credits the sale of corn for ethanol produc-
cally located in rural communities and often
tion—about 600 million bushels per year—
farmer-owned, which make them an excellent
with increasing corn prices by 25 to 30 cents
way to develop the local economy. In 2005,
per bushel. (The typical price range of field
more than 80 U.S. ethanol plants produced
corn is $1.80 to $2.30 per bushel.)
about four billion gallons of ethanol. While
ethanol accounts for about three percent of From Other Starch or Sugar: Even
automotive fuel use in the United States, it is states with a small corn crop can benefit
Page 16 ATTRA Renewable Energy Opportunities on the Farm
17. from building ethanol plants. Conventional reasons related to economics, air quality,
ethanol technology can process any starch and health. B100 (straight biodiesel) can
or sugar source. While corn certainly pre- cut carbon monoxide, hydrocarbons, partic-
dominates, U.S. plants are currently mak- ulates, and other pollutant emissions in half
ing ethanol from barley, milo, wheat starch, while reducing the cancer-risk contribution
potato waste, cheese whey, and brewery and of diesel by about 90 percent. Emission
beverage waste. reductions with B20 are roughly propor-
tional. Biodiesel will even reduce the smelly
From Cellulose and Hemicellulose: oily smoke that makes it so frustrating to
Starches and sugars constitute only a small get caught behind a truck, tractor, or bus.
portion of plant matter. The bulk of most Since it is biodegradable, biodiesel is far
plants consists of cellulose, hemicellu- more benign than petroleum-based diesel
lose, and lignin. Cellulose and hemicellu- fuels, should it be spilled on the ground.
lose, though, are made of chains of sugars.
Advanced bioethanol technology can break From Fats or Oils: Fatty acid methyl
these chains down into their component sug- ester, commonly known as biodiesel, is
ars, and then ferment them to ethanol. This made by bonding alcohol (com-
makes it possible to produce ethanol from monly methanol) to oils or fats
virtually any biomass material. In the near- (even animal fats or used cook-
term, ethanol will probably be made from ing oil). The process is relatively
low- or negative-cost opportunity feedstocks routine, but must consistently
such as municipal waste, wood process- achieve prescribed standards
ing waste, sugarcane bagasse, rice hulls, or adopted by the American Soci-
rice straw. In the mid-term, ethanol sources ety for Testing and Materials to
will include agricultural and forestry resi- minimize the risk of damaging
dues such as corn stover—a huge potential expensive diesel engines.
source—or wood chips. From a Growing Industry:
In the long-term, farmers may grow dedi- Biodiesel popularity is grow-
cated energy crops, such as switchgrass or ing rapidly. According to the
fast-growing trees, just for fuel production. Nat iona l Biodiesel Board,
Because it requires sophisticated conversion biodiesel production reached 75
technology, making ethanol from cellulosic million gallons in 2005, com-
biomass is currently more expensive than pared to 25 million gallons in
making it from corn grain—especially when 2004. As of April 2006, there
using waste or residue feedstocks. However, are 65 commercial biodiesel Soybeans can be made into biodiesel
to fuel any vehicle currently running
cellulosic feedstocks would be inexpensive, production plants in the United biodiesel with little to no conversion of
so experts expect equal or lower costs in the States, with a combined annual the vehicle. Photo courtesy of NREL.
long run. Advanced bioethanol technology production capacity of 395 mil-
will supplement rather than replace corn- lion gallons per year. Another
grain ethanol by greatly expanding the poten- 50 plants are scheduled to be online by the
tial feedstock supply and making ethanol end of 2007 and several plants are expand-
production an option outside the Cornbelt. ing, which will have a combined annual
The U.S. Department of Energy National capacity of 713 million gallons.
Biofuels Program is spearheading the effort Also, the detergent and fatty acid industries,
to improve advanced bioethanol technology. which supply methyl esters to the biodiesel
For more information, see the ATTRA publi- industry and can provide extra supplies
cation Ethanol Opportunities and Questions. when demand grows quickly, could provide
another 30-50 million gallons of capacity, if
Biodiesel—Easily Produced needed to meet demand.
Many agricultural producers are taking When purchased from commercial sup-
a hard look at biodiesel these days, for pliers, biodiesel is generally more expen-
www.attra.ncat.org ATTRA Page 17
18. sive than diesel fuel, but B20 typically The Energy Policy Act of 2005 will provide
costs only 8 to 20 cents more than reg- a federal excise tax credit for biodiesel as a
ular diesel. Although usually used by tax incentive for petroleum distributors who
centrally fueled fleets, biodiesel is becom- blend biodiesel with diesel fuel into both
ing increasingly available at retail service on-road and off-road markets. The incen-
stations across the country. tive equates to $1.00 per gallon of biodiesel
made from virgin vegetable oils (like soy)
For information on biodiesel distribu-
and animal fats, and $0.50 per gallon for
tors, suppliers, and retailers, see “Buying
biodiesel made from recycled oils (subject
Biodiesel” at http://nbb.org/buyingbiodiesel/
to funding appropriation.)
producers_marketers/Supplier_List.pdf
Newly purchased, qualified electric vehi-
Farmers in some parts of the country are
cles and clean-fuel vehicles (including gaso-
also successfully making their own biodie- line/electric hybrids) are eligible for federal
sel from waste oil, often collected from local income tax incentives:
restaurants. The cost of this “home-brewed”
biodiesel is often far lower than the cost of • Purchasers of hybrid and advanced
B
conventional diesel fuel. For more informa- lean-burn diesel vehicles can receive
iodiesel is tion on making biodiesel, see the ATTRA a federal tax credit of up to $3,400.
becoming publication Biodiesel – a Primer. This will be capped at 60,000
increasingly vehicles per manufacturer and will
available at retail expire in 2014. For medium and
Financial Incentives heavy hybrid trucks the tax credit
service stations The following information identifies federal will expire in 2009, and for lean-
across the country. fi nancial incentives. For more information burn diesel vehicles, the tax credit
on these, as well as state incentives, see the will expire in 2010.
Database of State Incentives for Renewable
• Electric vehicles are eligible for a
Energy (DSIRE) at www.dsireusa.org.
one-time tax credit of 10 percent of
The Federal government exempts offers a the vehicle cost, up to $4,000 per
53 cents per gallon incentive to encourage vehicle. The credit will be reduced
ethanol use. A 10-percent ethanol blend to $1,000 in 2006 and will expire
fuel receives an exemption of 5.3 cents at the end of that year. For more
from the federal fuel excise tax (currently information, visit www.fueleconomy.
18.3 cents per gallon). gov/feg/tax_afv.shtml.
Resources
American Solar Energy Society DOE Vehicle Buyers Guide
www.ases.org www.eere.energy.gov/cleancities/vbg
American Wind Energy Association DOE Wind and Hydropower Technologies Program
www.awea.org www.eere.energy.gov/windandhydro
DOE Biomass Program
EERE Information Center
www.eere.energy.gov/biomass
www.eere.energy.gov/informationcenter
DOE Clean Cities Program
www.eere.energy.gov/cleancities/transportation.html Florida Solar Energy Center
www.fsec.ucf.edu
DOE’s Office of Energy Efficiency and Renewable
Energy (EERE) HybridCenter.org
www.eere.energy.gov www.hybridcenter.org
Page 18 ATTRA Renewable Energy Opportunities on the Farm
19. Interstate Renewable Energy Council
www.irecusa.org/smallwindenergy/index.html
National Biodiesel Board
www.biodiesel.org
National Renewable Energy Laboratory
www.nrel.gov
National Sustainable Agriculture Information
Service/ATTRA
www.attra.ncat.org
Renewable Energy Access
www.renewableenergyaccess.com
Notes
www.attra.ncat.org ATTRA Page 19