Small Wind Electric Systems: A U.S. Consumer's Guide by m3.lovers


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									Small Wind Electric Systems
                       A U.S.
                  Consumer’s Guide
Small Wind Electric Systems

                              Location—A home in Charlotte, Vermont
                              Capacity—10 kilowatts
                              Turbine manufacturer—Bergey Windpower Company
                              Photo credit—Trudy Forsyth, NREL/PIX09123

                              Location — Wales Wind Energy Project, Wales, Alaska
                              Capacity — 0.1 MW
                              Turbine manufacturer — Atlantic Orient Corporation
                              Developer — Kotzebue Electric Association
                              Photo credit — Steve Drouilhet, NREL/PIX09674

                              Capacity—10 kilowatts
                              Turbine manufacturer—Bergey Windpower Company
                              Photo credit—Bergey Windpower Company, NREL/PIX02102

                              Location—A ranch near Wheeler, Texas
                              Capacity—1 kilowatt
                              Turbine manufacturer—Southwest WindPower
                              Photo Credit—Elliott Bayly/PIX07169

                              Location — A farm in western Kansas
                              Capacity — 10 kilowatts
                              Turbine manufacturer — Bergey Windpower Company
                              Photo credit — Warren Gretz, NREL/PIX09618

                              Location—A cabin in South Park, Colorado
                              Capacity—600 watt
                              Turbine manufacturer—Southwest WindPower
                              Photo credit—E. McKenna, NREL/PIX04712
                                                                                           Small Wind Electric Systems                                                              

  Small Wind Electric Systems
                              A U.S. Consumer’s Guide

Can I use wind energy to power my
home? This question is being asked
across the country as more people
look for affordable and reliable sourc-
es of electricity.
Small wind electric systems can make
a significant contribution to our
nation’s energy needs. Although wind
turbines large enough to provide a
significant portion of the electricity
needed by the average U.S. home gen-
erally require one acre of property or
more, approximately 21 million U.S.

                                                                                                                                                                         Bergey Windpower/PIX01476
homes are built on one-acre and larger
sites, and 24% of the U.S. population
lives in rural areas.
A small wind electric system will
work for you if:
• There is enough wind where you          Homeowners, .ranchers, .and .small .businesses .can .use .wind-
                                          generated .electricity .to .reduce .their .utility .bills . .This .grid-
  live                                    connected .system .installed .for .a .home .in .Norman, .Oklahoma, .
• Tall towers are allowed in your         reduces .the .homeowner’s .utility .bill .by .$100 .per .month .
  neighborhood or rural area
• You have enough space
• You can determine how much                Introduction .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1
  electricity you need or want to           First, .How .Can .I .Make .My .Home .More .Energy .Efficient? .  .  .  .  . 2
                                            Is .Wind .Energy .Practical .for .Me? . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3
• It works for you economically.            What .Size .Wind .Turbine .Do .I .Need?  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4
The purpose of this guide is to pro-        What .are .the .Basic .Parts .of .a .Small .Wind .Electric .System? . .  . 5
vide you with the basic information         What .Do .Wind .Systems .Cost? .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7
about small wind electric systems to        Where .Can .I .Find .Installation .and .Maintenance .Support? .  .  .  . 8
help you decide if wind energy will         How .Much .Energy .Will .My .System .Generate? .  .  .  .  .  .  .  .  .  .  .  .  . 9
work for you.                               Is .There .Enough .Wind .on .My .Site? .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11
Why Should I Choose Wind?                   How .Do .I .Choose .the .Best .Site .for .My .Wind .Turbine? .  .  .  .  .  . 14
Wind energy systems are one                 Can .I .Connect .My .System .to .the .Utility .Grid?  .  .  .  .  .  .  .  .  .  .  .  . 15
of the most cost-effective home-            Can .I .Go .“Off-Grid”?  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19
based renewable energy systems.             Glossary .of .Terms .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21
Depending on your wind resource, a          For .More .Information . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 22
   Small Wind Electric Systems

                small wind energy system can lower                         Home Energy Use
                your electricity bill by 50% to 90%,                   Based on national averages
                help you avoid the high costs of
                extending utility power lines to                             Water
                remote locations, prevent power                             heating
                interruptions, and it is nonpolluting.                       14%
                                                                                                Heating and
                How Do Wind Turbines Work?                         Lighting,                      cooling
                Wind is created by the unequal heat-               cooking,                        44%
                                                                   and other
                ing of the Earth’s surface by the sun.            appliances
                Wind turbines convert the kinetic                    33%

                energy in wind into mechanical
                power that runs a generator to
                produce clean electricity. Today’s
                                                                                                Refrigerator 9%
                turbines are versatile modular sources
                of electricity. Their blades are aero-     The .largest .portion .of .a .utility .bill .for .a .typical .
                dynamically designed to capture the        house .is .for .heating .and .cooling .
                maximum energy from the wind. The
                wind turns the blades, which spin a        • Save money and increase
                shaft connected to a generator that          comfort by properly maintaining
                makes electricity.                           and upgrading your heating,
                                                             ventilation, and air-conditioning
                First, How Can I Make                        systems.
                My Home More Energy
                Efficient?                                 • Install double-paned, gas-filled
                                                             windows with low-emissivity
                Before choosing a wind system for
                                                             (low-e) coatings to reduce heat
                your home, you should consider
                                                             loss in cold climates and spectrally
                reducing your energy consumption by
                                                             selective coatings to reduce heat
                making your home or business more
                                                             gain in warm climates.
                energy efficient. Reducing your
                energy consumption will signifi-           • Replace your lights in high-use
                cantly lower your utility bills and will     areas with fluorescents. Replacing
                reduce the size of the home-based            25% of your lights can save about
                renewable energy system you need.            50% of your lighting energy bill.
                To achieve maximum energy effi-            • When shopping for appliances,
                ciency, you should take a whole-             look for the Energy Star® label.
                building approach. View your home            Energy Star® appliances have
                as an energy system with interrelated        been identified by the U.S.
                parts, all of which work synergisti-         Environmental Protection Agency
                cally to contribute to the efficiency        and U.S. Department of Energy
                of the system. From the insulation in        as being the most energy-efficient
                your home’s walls to the light bulbs         products in their classes.
                in its fixtures, there are many ways to
                                                           • For more information on how to
                make your home more efficient.
                                                             make your home energy efficient,
                • Reduce your heating and                    see Energy Savers in the For More
                  cooling needs by up to 30% by              Information section.
                  investing just a few hundred
                  dollars in proper insulation and
                  weatherization products.
                                                                 Small Wind Electric Systems                                        

Is Wind Energy Practical                  structures permitted in residentially
for Me?                                   zoned areas, although variances are
A small wind energy system can            often obtainable. Most zoning ordi-
provide you with a practical and          nances have a height limit of 35 feet.
economical source of electricity if:      You can find out about the zoning
                                          restrictions in your area by calling
• your property has a good wind           the local building inspector, board of
  resource                                supervisors, or planning board. They
• your home or business is located on     can tell you if you will need to obtain
  at least one acre of land in a rural    a building permit and provide you
  area                                    with a list of requirements.
• your local zoning codes or              In addition to zoning issues, your
  covenants allow wind turbines           neighbors might object to a wind
                                          machine that blocks their view, or
• your average electricity bills are
                                          they might be concerned about noise.
  $150 per month or more
                                          Most zoning and aesthetic concerns
• your property is in a remote            can be addressed by supplying objec-
  location without easy access to         tive data. For example, the ambient
  utility lines                           noise level of most modern residential
• you are comfortable with long-term      wind turbines is around 52 to 55 deci-
  investments.                            bels. This means that while the sound
                                          of the wind turbine can be picked out
Zoning Issues                             of surrounding noise if a conscious
Before you invest in a wind energy        effort is made to hear it, a residential-
system, you should research poten-        sized wind turbine is no noisier than
tial obstacles. Some jurisdictions, for   your average refrigerator.
example, restrict the height of the

                                                                                                          In .Clover .Valley, .
                                                                                                          Minnesota, .this . .
                                                                                                          3-kW .Whisper .
                                                                                                          H175 .turbine .on .a . .
                                                                                                          50-foot .tower .is .
                                                                                                          connected .to .the .
                                                                                                          utility .grid .to .offset .
                                                                                                          the .farm’s .utility-
                                                                                                          supplied .electricity .
                                                                                      World Power Technology/PIX07168
      Small Wind Electric Systems

                           What Size Wind Turbine                                        Turbines used in residential applica-
                           Do I Need?                                                    tions can range in size from 400 watts
                           The size of the wind turbine you need                         to 100 kW (100 kW for very large
                           depends on your application. Small                            loads), depending on the amount of
                           turbines range in size from 20 watts                          electricity you want to generate. For
                           to 100 kilowatts (kW). The smaller or                         residential applications, you should
                           “micro” (20- to 500-watt) turbines are                        establish an energy budget to help
                           used in a variety of applications such                        define the turbine size you will need.
                           as charging batteries for recreational                        Because energy efficiency is usually
                           vehicles and sailboats.                                       less expensive than energy produc-
                                                                                         tion, making your house more energy
                           One- to 10-kW turbines can be used in                         efficient first will probably be more
                           applications such as pumping water.                           cost effective and will reduce the size
                           Wind energy has been used for centu-                          of the wind turbine you need (see
                           ries to pump water and grind grain.                           How Can I Make My Home More
                           Although mechanical windmills still                           Energy Efficient?). Wind turbine
                           provide a sensible, low-cost option                           manufacturers can help you size
                           for pumping water in low-wind areas,                          your system based on your electricity
                           farmers and ranchers are finding that                         needs and the specifics of local wind
                           wind-electric pumping is a little more                        patterns.
                           versatile and they can pump twice
                           the volume for the same initial                               A typical home uses approximately
                           investment. In addition, mechanical                           10,000 kilowatt-hours (kWh) of elec-
                           windmills must be placed directly                             tricity per year (about 830 kWh per
                           above the well, which may not take                            month). Depending on the average
                           the best advantage of available wind                          wind speed in the area, a wind tur-
                           resources. Wind-electric pumping                              bine rated in the range of 5 to 15 kW
                           systems can be placed where the wind                          would be required to make a signifi-
                           resource is the best and connected to                         cant contribution to this demand. A
                           the pump motor with an electric cable.                        1.5- kW wind turbine will meet the
                                                                                         needs of a home requiring 300 kWh
                                                                                         per month in a location with a 14-
This .1-kW .Whisper .                                                                    mile-per-hour (6.26-meters-per-sec-
turbine .provides .                                                                      ond) annual average wind speed. The
direct .AC .power .for .
the .water .pump .for .
                                                                                         manufacturer can provide you with
stock .tanks .on .a .                                                                    the expected annual energy output
ranch .in .Wheeler, .                                                                    of the turbine as a function of annual
Texas .                                                                                  average wind speed. The manufac-
                                                                                         turer will also provide information on
                                                                                         the maximum wind speed at which
                                                                                         the turbine is designed to operate
                                                                                         safely. Most turbines have automatic
                                                                                         overspeed-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
                                                                Elliott Bayly/PIX09681

                                                                                         decide which size turbine will best
                                                                                         meet your electricity needs.
                                                                       Small Wind Electric Systems                

What are the Basic Parts
of a Small Wind Electric
Home wind energy systems gener-
ally comprise a rotor, a generator or             Generator/                           Tail
alternator mounted on a frame, a tail             alternator

(usually), a tower, wiring, and the
“balance of system” components:
controllers, inverters, and/or batter-
ies. Through the spinning blades, the
rotor captures the kinetic energy of
the wind and converts it into rotary
motion to drive the generator.
Wind Turbine
Most turbines manufactured today
are horizontal axis upwind machines        generator from a 60-foot tower height
with two or three blades, which are        to a 100-foot tower involves a 10%
usually made of a composite material       increase in overall system cost, but it
such as fiberglass.                        can produce 29% more power.
The amount of power a turbine will         There are two basic types of tow-
produce is determined primarily by         ers: self-supporting (free standing)
the diameter of its rotor. The diameter    and guyed. Most home wind power
of the rotor defines its “swept area,”     systems use a guyed tower. Guyed
or the quantity of wind intercepted by     towers, which are the least expensive,
the turbine. The turbine’s frame is the    can consist of lattice sections, pipe, or
structure onto which the rotor, genera-    tubing (depending on the design), and
tor, and tail are attached. The tail       supporting guy wires. They are easier
keeps the turbine facing into the wind.    to install than self-supporting tow-
                                           ers. However, because the guy radius
Tower                                      must be one-half to three-quarters
Because wind speeds increase with          of the tower height, guyed towers
height, the turbine is mounted on          require enough space to accommodate
a tower. In general, the higher the        them. Although tilt-down towers are
tower, the more power the wind             more expensive, they offer the con-
system can produce. The tower also         sumer an easy way to perform
                                                                                     Tilt-down .towers .
raises the turbine above the air           maintenance on smaller light-weight provide .easy .
turbulence that can exist close to         turbines, usually 5 kW or less.           maintenance .for .
the ground because of obstructions                                                       turbines .
such as hills, buildings, and trees. A
                                                                 Tilt-Down Tower
general rule of thumb is to install a
                                                                               Tilt-up tower
wind turbine on a tower with the bot-                                          in the normal
tom of the rotor blades at least 30 feet                                       operating
                                                Tilt-up tower in the           position
(9 meters) above any obstacle that              lowered position for
is within 300 feet (90 meters) of the           maintenance or
tower. Relatively small investments in
increased tower height can yield very
high rates of return in power produc-
tion. For instance, to raise a 10-kW                                                              02979311m
         Small Wind Electric Systems

                                 Tilt-down towers can also be low-         application, the balance of system
                                 ered to the ground during hazard-         parts may include a controller, storage
                                 ous weather such as hurricanes.           batteries, a power conditioning unit
                                 Aluminum towers are prone to              (inverter), and wiring. Some wind
                                 cracking and should be avoided.           turbine controllers, inverters, or other
                                 Most turbine manufacturers provide        electrical devices may be stamped
                                 wind energy system packages that          by a recognized testing agency, like
                                 include towers.                           Underwriters Laboratories.
                                 Mounting turbines on rooftops is not      Stand-Alone Systems
                                 recommended. All wind turbines            Stand-alone systems (systems not
                                 vibrate and transmit the vibration        connected to the utility grid) require
                                  to the structure on which they are       batteries to store excess power gener-
                                 mounted. This can lead to noise and       ated for use when the wind is calm.
                                 structural problems with the building,    They also need a charge controller to
                                 and the rooftop can cause excessive       keep the batteries from overcharging.
                                 turbulence that can shorten the life of   Deep-cycle batteries, such as those
                                 the turbine.                              used for golf carts, can discharge
                                 Balance of System                         and recharge 80% of their capacity
                                 The parts that you need in addition       hundreds of times, which makes them
                                 to the turbine and the tower, or the      a good option for remote renewable
                                 balance of system parts, will depend      energy systems. Automotive batteries
                                 on your application. Most manufac-        are shallow-cycle batteries and should
                                 turers can provide you with a system      not be used in renewable energy
                                 package that includes all the parts you   systems because of their short life
                                 need for your application. For exam-      in deep-cycling operations.
                                 ple, the parts required for a water
                                 pumping system will be much differ-
                                 ent than what you need for a residen-
                                 tial application. The balance of system
                                 required will also depend on whether
                                 the system is grid-connected, stand-
                                 alone, or part of a hybrid system.
                                 For a residential grid-connected

    A .Bergey .XL .10, . .
    10-kW .wind .
    turbine .is .part .of .
    a .grid-connected .
    wind/photovoltaic .
    hybrid .system .that .
    reduces .the .utility .
    power .used .by .this .
    home .in .Vermont . .
                                                                                                                      Trudy Forsyth, NREL/PIX09122 and PIX09123

    The .balance .of .
    system .(upper .right) .
    includes .from .left . .
    to .right, .a .Trace .
    inverter .for .the .
    PV .system, .a .
    breaker .box, .and .a .
    Powersync .inverter .
    for .the .wind .system . .
                                                                    Small Wind Electric Systems                              

Small wind turbines generate direct                                                                  A .Southwest .
current (DC) electricity. In very small                                                              Windpower .Air .
                                                                                                     303, .300-watt .
systems, DC appliances operate                                                                       turbine .is .the .sole .
directly off the batteries. If you want to                                                           source .of .electricity .
use standard appliances that use con-                                                                for .this .remote .
                                                                                                     home .in .northern .
ventional household alternating cur-                                                                 Arizona .
rent (AC), you must install an inverter
to convert DC electricity from the
batteries to AC. Although the inverter
slightly lowers the overall efficiency
of the system, it allows the home to
be wired for AC, a definite plus with
lenders, electrical code officials, and
future homebuyers.
For safety, batteries should be iso-

                                                                                         Southwest Windpower/PIX09156
lated from living areas and electron-
ics because they contain corrosive
and explosive substances. Lead-acid
batteries also require protection from
temperature extremes.
Grid-Connected Systems
In grid-connected systems, the only          ranges from $15,000 to $50,000 for
additional equipment required is a           a 3- to 10-kW wind turbine.
power conditioning unit (inverter)
that makes the turbine output electri-       Although wind energy systems
cally compatible with the utility grid.      involve a significant initial invest-
Usually, batteries are not needed.           ment, they can be competitive with
                                             conventional energy sources when
What Do Wind Systems                         you account for a lifetime of reduced
Cost?                                        or avoided utility costs. The length
Installation costs vary greatly depend-      of the payback period—the time
ing on local zoning, permitting,             before the savings resulting from your
and utility interconnection costs.           system equal the cost of the system
According to the American Wind               itself—depends on the system you
Energy Association, small wind               choose, the wind resource on your
energy systems cost from $3,000 to           site, electricity costs in your area, and
$5,000 for every kilowatt of generating      how you use your wind system. For
capacity. This is much cheaper than          example, if you live in California and
solar electric systems, but the payback      have received the 50% buydown of
period can still be lengthy.                 your small wind system, have net
                                             metering, and an average annual
Wind energy becomes more cost effec-         wind speed of 15 miles per hour
tive as the size of the turbine’s rotor      (mph) (6.7 meters per second [m/
increases. Although small turbines           s]), your simple payback would be
cost less in initial outlay, they are        approximately 6 years.
proportionally more expensive. The
cost of an installed residential wind
energy system with an 80-foot tower,
batteries, and inverter typically
       Small Wind Electric Systems

                                                                                              references of past customers with
                                                                                              installations similar to the one you are
                                                                                              considering. Ask the system owners
                                                                                              about performance, reliability, and
                                                                                              maintenance and repair requirements,
                                                                                              and whether the system is meeting
                                                                                              their expectations. Also, find out how
                                                                                              long the warranty lasts and what it

                                                                                              Where Can I Find
                                                                                              Installation and
                                                                                              Maintenance Support?
                                                                                              The manufacturer/dealer should be
                                                                                              able to help you install your machine.
                                                                                              Many people elect to install the
                                                                                              machines themselves. Before attempt-
                                                                                              ing to install your wind turbine, ask
                                                                Warren Gretz, NREL/PIX09615

                                                                                              yourself the following questions:
                                                                                              • Can I pour a proper cement
                                                                                              • Do I have access to a lift or a way of
                                                                                                erecting the tower safely?
    Small .wind .
    turbines .like .this . Things to Consider When                                            • Do I know the difference between
    10-kW .Bergey .        Purchasing a Wind Turbine
    XL .10 .provide .
                                                                                                AC and DC wiring?
    electricity .for .     Once you determine you can install                                 • Do I know enough about electricity
    home, .farm, .and .    a wind energy system in compliance
    ranch .applications .                                                                       to safely wire my turbine?
                      with local land use requirements, you
                      can begin pricing systems and compo-                                    • Do I know how to safely handle
                      nents. Comparatively shop for a wind                                      and install batteries?
                      system as you would any major pur-                                      If you answered no to any of the
                      chase. Obtain and review the product                                    above questions, you should probably
                      literature from several manufacturers.                                  choose to have your system installed
                      As mentioned earlier, lists of manu-                                    by a system integrator or installer.
                      facturers are available from AWEA,                                      Contact the manufacturer for help
                      (see For More Information), but not                                     or call your state energy office and
                      all small turbine manufacturers are                                     local utility for a list of local system
                      members of AWEA. Check the yellow                                       installers. You can also check the yel-
                      pages for wind energy system dealers                                    low pages for wind energy system
                      in your area.                                                           service providers. A credible installer
                      Once you have narrowed the field,                                       will provide many services such as
                      research a few companies to be sure                                     permitting. Find out if the installer is a
                      they are recognized wind energy                                         licensed electrician. Ask for references
                      businesses and that parts and service                                   and check them out. You may also
                      will be available when you need them.                                   want to check with the Better Business
                      You may wish to contact the Better                                      Bureau.
                      Business Bureau to check on                                             Although small wind turbines are
                      the company’s integrity and ask for                                     very sturdy machines, they do require
                                                                                     Small Wind Electric Systems                  

some annual maintenance. Bolts             wind speed results in a large increase
and electrical connections should be       in power. That is why a taller tower
checked and tightened if necessary.        will increase the productivity of any
The machines should be checked for         wind turbine by giving it access to
corrosion and the guy wires for            higher wind speeds as shown in the
proper tension. In addition, you           Wind Speeds Increase with Height
should check for and replace any           graph. The formula for calculating
worn leading edge tape on the blades,      the power from a wind turbine is:
if appropriate. After 10 years, the                          Power = k Cp 1/2 ρ A V3
blades or bearings may need to be
replaced, but with proper installation     Where:
and maintenance, the machine should        P = Power output, kilowatts
last up to 20 years or longer.             Cp = Maximum power coefficient,
If you do not have the expertise to             ranging from 0.25 to 0.45,
maintain the machine, your installer            dimension less (theoretical
                                                maximum = 0.59)
may provide a service and mainte-
nance program.                             ρ = Air density, lb/ft3
                                           A = Rotor swept area, ft2 or
How Much Energy Will My                        π D2/4 (D is the rotor
System Generate?                               diameter in ft, π = 3.1416)
Most U.S. manufacturers rate their         V = Wind speed, mph
turbines by the amount of power they       k = 0.000133 A constant to yield
can safely produce at a particular             power in kilowatts. (Multiplying
wind speed, usually chosen between             the above kilowatt answer by
24 mph (10.5 m/s) and 36 mph (16 m/            1.340 converts it to horse-
s). The following formula                      power [i.e., 1 kW = 1.340
illustrates factors that are important         horsepower]).
to the performance of a wind turbine.      The rotor swept area, A, is important
Notice that the wind speed, V, has an      because the rotor is the part of the
exponent of 3 applied to it. This          turbine that captures the wind energy.
means that even a small increase in

                             Relative Size of Small Wind Turbines

                                            Swept area, m2

                    6                                        20
Rotor Diameter, m

                    5                                        10
                    4                                         0
                        4m                                        1        2        3        4       5                    6   7
                                                                                  Rotor Diameter, m

                                                                      Source: Paul Gipe, Wind Energy Basics
0                Small Wind Electric Systems

                          Air Density Change with Elevation                       height of the tower that you plan to
             10,000                                                               use, and the frequency distribution of
                 9,000                                                            the wind–an estimate of the number
                 8,000                                                            of hours that the wind will blow at
                 7,000                                                            each speed during an average year.
 Elevation, ft

                 6,000                                                            They should also adjust this calcula-
                 5,000                                                            tion for the elevation of your site.
                 4,000                                                            Contact a wind turbine manufacturer
                 3,000                                                            or dealer for assistance with this
                 2,000                                                            calculation.

                                                                                  To get a preliminary estimate of the
                    0                                                             performance of a particular wind tur-
                     70     75       80      85      90       95    100
                          Density change compared to sea level, %                 bine, use the formula below.
                                                                                           AEO = 0.01328 D2 V3
                                 So, the larger the rotor, the more               Where:
                                 energy it can capture. The air density,          AEO = Annual energy output,
                                 ρ, changes slightly with air tempera-                kWh/year
                                 ture and with elevation. The ratings
                                                                                  D = Rotor diameter, feet
                                 for wind turbines are based on
                                 standard conditions of 59° F (15° C)             V = Annual average wind speed,
                                 at sea level. A density correction                   mph
                                 should be made for higher elevations             The Wind Energy Payback Period
                                 as shown in the Air Density Change               Workbook found at
                                 with Elevation graph. A correction for           wind/docs/spread_sheet_Final.xls is
                                 temperature is typically not needed              a spreadsheet tool that can help you
                                 for predicting the long-term perfor-             analyze the economics of a small wind
                                                                                  electric system and decide whether
                                 mance of a wind turbine.
                                                                                  wind energy will work for you. The
                                 Although the calculation of wind                 spreadsheet can be opened using
                                 power illustrates important features             Microsoft Excel 95 software. It asks
                                 about wind turbines, the best mea-               you to provide information about how
                                 sure of wind turbine performance is              you’re going to finance the system,
                                 annual energy output. The difference             the characteristics of your site, and
                                                                                  the properties of the system you’re
                                 between power and energy is that
                                                                                  considering. It then provides you with
                                 power (kilowatts [kW]) is the rate at            a simple payback estimation in years.
                                 which electricity is consumed, while             If it takes too long to regain your capi-
                                 energy (kilowatt-hours [kWh]) is the             tal investment—the number of years
                                 quantity consumed. An estimate of                comes too close or is greater than the
                                 the annual energy output from your               life of the system—wind energy will
                                 wind turbine, kWh/year, is the best              not be practical for you.
                                 way to determine whether a particular
                                 wind turbine and tower will produce
                                 enough electricity to meet your needs.
                                 A wind turbine manufacturer can help
                                 you estimate the energy production
                                 you can expect. They will use a cal-
                                 culation based on the particular wind
                                 turbine power curve, the average
                                 annual wind speed at your site, the
                                                                                Small Wind Electric Systems                  

Is There Enough Wind                         particular location. Airport wind data
on My Site?                                  are generally measured at heights
Does the wind blow hard and con-             about 20–33 ft (6–10 m) above ground.
sistently enough at my site to make a        Average wind speeds increase with
small wind turbine system economi-           height and may be 15%–25% greater
cally worthwhile? That is a key ques-        at a typical wind turbine hub-height
tion and not always easily answered.         of 80 ft (24 m) than those measured
The wind resource can vary signifi-          at airport anemometer heights. The
cantly over an area of just a few miles      National Climatic Data Center collects
because of local terrain influences          data from airports in the United States
 on the wind flow. Yet, there are steps      and makes wind data summaries
you can take that will go a long way         available for purchase. Summaries
towards answering the above                  of wind data from almost 1000 U.S.
question.                                    airports are also included in the Wind
                                             Energy Resource Atlas of the United
As a first step, wind resource maps          States (see For More Information).
like the one on pages 12 and 13 can
 be used to estimate the wind resource       Another useful indirect measurement
in your region. The highest average          of the wind resource is the observa-
wind speeds in the United States are         tion of an area’s vegetation. Trees,
generally found along seacoasts, on          especially conifers or evergreens, can
ridgelines, and on the Great Plains;         be permanently deformed by strong
however, many areas have wind                winds. This deformity, known as
resources strong enough to power a           “flagging,” has been used to estimate
small wind turbine economically. The         the average wind speed for an area.
wind resource estimates on this map          For more information on the use of
generally apply to terrain features that     flagging, you may want to obtain
are well exposed to the wind, such as
plains, hilltops, and ridge crests. Local                            Wind Speeds Increase with Height
terrain features may cause the wind
resource at a specific site to differ con-                150
siderably from these estimates. More
detailed wind resource information,
including the Wind Energy Resource
Atlas of United States, published by the
U.S. Department of Energy (DOE),
can be found at the National Wind
                                             Tower height, ft

Technology Center Web site at www.                              90 and the DOE Wind
Powering America Web site at www.                                        60
Another way to indirectly quantify
the wind resource is to obtain average
wind speed information from a
nearby airport. However, caution
should be used because local terrain
influences and other factors may
cause the wind speed recorded at                                0
                                                                                   0          41     75    100     124
an airport to be different from your                                                   Increase in wind power, %
12   Small Wind Electric Systems   Small Wind Electric Systems   13
        Small Wind Electric Systems

     Flagging, .the .effect .
     of .strong .winds .on .             Flagging                               0                           I
     area .vegetation, .                                                        No                          Brushing
     can .help .determine .         Prevailing wind
                                                                                deformity                   and slight
     area .wind .speeds . .                                                                                 flagging

                                                      II                        III                         IV
                                                      Slight                    Moderate                    Complete
                                                      flagging                  flagging                    flagging

                                                      V                         VI                          VII
                                                      Partial                   Complete                    Carpeting
                                                      throwing                  throwing


                                                             Griggs-Putnam Index of Deformity
                                      Index             I         II     III      IV         V       VI       VII
                                      Wind mph        7-9        9-11   11-13   13-16       15-18   16-21    22+
                                      Speed m/s       3-4        4-5     5-6     6-7         7-8     8-9      10

                                A Siting Handbook for Small Wind                How Do I Choose the Best
                                Energy Conversion Systems (see For              Site for My Wind Turbine?
                                More Information).                              You can have varied wind resources
                                Direct monitoring by a wind resource            within the same property. In addition
                                measurement system at a site pro-               to measuring or finding out about
                                vides the clearest picture of the avail-        the annual wind speeds, you need to
                                able resource. A good overall guide             know about the prevailing directions
                                on this subject is the Wind Resource            of the wind at your site. If you live in
                                Assessment Handbook (see For More               complex terrain, take care in selecting
                                Information). Wind measurement                  the installation site. If you site your
                                systems are available for costs as low          wind turbine on the top of or on the
                                as $600 to $1200. This expense may or           windy side of a hill, for example, you
                                may not be hard to justify depending            will have more access to prevailing
                                on the exact nature of the proposed             winds than in a gully or on the lee-
                                small wind turbine system. The mea-             ward (sheltered) side of a hill on the
                                surement equipment must be set high             same property. In addition to geologic
                                enough to avoid turbulence created              formations, you need to consider
                                by trees, buildings, and other obstruc-         existing obstacles such as trees,
                                tions. The most useful readings are             houses, and sheds, and you need to
                                those taken at hub-height, the eleva-           plan for future obstructions such as
                                tion at the top of the tower where the          new buildings or trees that have not
                                wind turbine is going to be installed.          reached their full height. Your turbine
                                If there is a small wind turbine sys-           needs to be sited upwind of build-
                                tem in your area, you may be able to            ings and trees, and it needs to be 30
                                obtain information on the annual                feet above anything within 300 feet.
                                output of the system and also wind              You also need enough room to raise
                                speed data if available.                        and lower the tower for maintenance,
                                                                      Small Wind Electric Systems            

               Obstruction of the Wind by a Building
                       or Tree of Height (H)

                                              of highly

                                    H            flow

              2H                                               20 H
                                                                                      The .farther .you .
                                                                                      place .your .wind .
and if your tower is guyed, you must        requires, the excess is sent or sold to   turbine .from .
allow room for the guy wires.               the utility.                              obstacles .such .
                                                                                      as .buildings .or .
Whether the system is stand-alone           Grid-connected systems can be practi-     trees, .the .less .
or grid-connected, you will also need       cal if the following conditions exist:    turbulence .you .
                                                                                      will .encounter .
to take the length of the wire run          • You live in an area with average
between the turbine and the load              annual wind speed of at least
(house, batteries, water pumps, etc.)         10 mph (4.5 m/s)
into consideration. A substantial
amount of electricity can be lost as a      • Utility-supplied electricity is
result of the wire resistance—the lon-        expensive in your area (about 10 to
ger the wire run, the more electric-          15 cents per kilowatt-hour)
ity is lost. Using more or larger wire      • The utility’s requirements for
will also increase your installation          connecting your system to its grid
cost. Your wire run losses are greater        are not prohibitively expensive
when you have direct current (DC)           • There are good incentives for the
instead of alternating current (AC).          sale of excess electricity or for the
So, if you have a long wire run, it is        purchase of wind turbines.
advisable to invert DC to AC.
                                            Federal regulations (specifically, the
Can I Connect My System                     Public Utility Regulatory Policies Act
to the Utility Grid?                        of 1978, or PURPA) require utilities
Small wind energy systems can be            to connect with and purchase power
connected to the electricity distribu-      from small wind energy systems.
tion system and are called grid-            However, you should contact your
connected systems. A grid-connected         utility before connecting to their dis-
wind turbine can reduce your con-           tribution lines to address any power
sumption of utility-supplied electric-      quality and safety concerns. Your
ity for lighting, appliances, and           utility can provide you with a list of
electric heat. If the turbine cannot        requirements for connecting your sys-
deliver the amount of energy you            tem to the grid. The American Wind
need, the utility makes up the differ-      Energy Association is another good
ence. When the wind system produces         source for information on utility
more electricity than the household         interconnection requirements. The
      Small Wind Electric Systems

     A .grid-connected .                                Grid-connected Systems
     wind .turbine .
     can .reduce .your .
     consumption .of .                                                                  Meter
     utility-supplied .
     electricity .


                           following information about utility          Most of North America gets more
                           grid connection requirements was             wind in the winter than in the sum-
                           taken from AWEA’s Web site. For              mer. For people using wind energy to
                           more detailed information, visit www.        displace a large load in the summer
                  or contact AWEA (see For           like air-conditioning or irrigation
                           More Information).                           water pumping, having an annual
                                                                        NEG credit allows them to produce
                           Net Metering
                                                                        NEG in the winter and be credited in
                           The concept of net metering programs         the summer.
                           is to allow the electric meters of cus-
                           tomers with generating facilities to         Safety Requirements
                           turn backwards when their generators         Whether or not your wind turbine
                           are producing more energy than the           is connected to the utility grid, the
                           customers’ demand. Net metering              installation and operation of the wind
                           allows customers to use their genera-        turbine is probably subject to the
                           tion to offset their consumption over        electrical codes that your local gov-
                           the entire billing period, not just          ernment (city or county), or in some
                           instantaneously. This offset would           instances your state government, has
                           enable customers with generating             in place. The government’s principal
                           facilities to receive retail prices for      concern is with the safety of the
                           more of the electricity they generate.       facility, so these code requirements
                           Net metering varies by state and             emphasize proper wiring and installa-
                           by utility company, depending on             tion and the use of components
                           whether net metering was legis-              that have been certified for fire and
                           lated or directed by the Public Utility      electrical safety by approved testing
                           Commission. Net metering programs            laboratories, such as Underwriters
                           all specify a way to handle the net          Laboratories. Most local electrical
                           excess generation (NEG) in terms of          codes requirements are based on
                           payment for electricity and/or length        the National Electrical Code (NEC),
                           of time allowed for NEG credit. If           which is published by the National
                           the net metering requirements define         Fire Protection Association. As of
                           NEG on a monthly basis, the consum-          1999, the latest version of the NEC did
                           er can only get credit for their excess      not have any sections specific to the
                           that month. But if the net metering          installation of wind energy facilities’
                           rules allow for annual NEG, the NEG          consequently wind energy installa-
                           credit can be carried for up to a year.      tions are governed by the generic
                                                                        provisions of the NEC.
                                                                   Small Wind Electric Systems                

If your wind turbine is connected to        provider. In the case of private (inves-
the local utility grid so that any of the   tor-owned) utilities, the terms and
power produced by your wind tur-            conditions in these agreements must
bine is delivered to the grid, then your    be reviewed and approved by state
utility also has legitimate concerns        regulatory authorities.
about safety and power quality that
need to be addressed. The utility’s
principal concern is that your wind         Some utilities require small wind
turbine automatically stops deliver-         turbine owners to maintain liability
ing any electricity to its power lines      insurance in amounts of $1 million or
during a power outage. Otherwise            more. Utilities consider these require-
line workers and the public, thinking       ments necessary to protect them from
that the line is “dead,” might not take     liability for facilities they do not own
normal precautions and might be             and have no control over. Others
hurt or even killed by the power from       consider the insurance requirements
your turbine. Another concern among         excessive and unduly burdensome,
utilities is whether the power from         making wind energy uneconomic. In
your facility synchronizes properly         the 21 years since utilities have been
with the utility grid and it matches the    required to allow small wind systems
utility’s own power in terms of volt-       to interconnect with the grid, there
                                                                                       This .grid-
age, frequency, and power quality.          has never been a liability claim, let      connected, . .
                                            alone a monetary award, relating to        10-kW .Bergey .
A few years ago, some state govern-         electrical safety.                         wind .turbine .
ments started developing new                                                           offsets .
standardized interconnection require-       In seven states (California, Georgia,      electrical .power .
                                            Maryland, Nevada, Oklahoma,                consumption .for .
ments for small renewable energy                                                       a .small .business .
generating facilities (including wind       Oregon, and Washington), laws              in .Norman, .
turbines). In most cases, the new           or regulatory authorities prohibit         Oklahoma .
requirements are based on consen-
sus-based standards and testing pro-
cedures developed by independent
third-party authorities, such as the
Institute of Electrical and Electronic
Engineers and Underwriters
Interconnection Requirements
Most utilities and other electricity
providers require you to enter into a
formal agreement with them before
you interconnect your wind turbine
with the utility grid. In states that
have retail competition for electricity
service (e.g., your utility operates
the local wires, but you have a
choice of electricity provider)
                                                                                                              Bergey Windpower/PIX07166

you may have to sign a separate
agreement with each company.
Usually these agreements are writ-
ten by the utility or the electricity
   Small Wind Electric Systems

                 utilities from imposing any insurance                                facility. Although the basic principle
                 requirements on small wind sys-                                      is sound—utilities should not be
                 tems that qualify for “net metering.”                                held responsible for property dam-
                 In at least two other states (Idaho,                                 age or personal injury attributable
                 Virginia), regulatory authorities have                               to someone else—indemnity provi-
                 allowed utilities to impose insurance                                sions should not favor the utility but
                 requirements but have reduced the                                    should be fair to both parties. Look for
                 required coverage amounts to levels                                  language that says, “each party shall
                 consistent with conventional residen-                                indemnify the other . . .” rather than
                 tial or commercial insurance policies                                “the customer shall indemnify the
                 (e.g., $100,000 to $300,000). If your                                utility . . .”
                 insurance amounts seem excessive,
                                                                                      Customer Charges
                 you can ask for a reconsideration from
                 regulatory authorities (in the case of                               Customer charges can take a variety
                 private investor-owned utilities) or                                 of forms, including interconnection
                 the utility’s governing board (in the                                charges, metering charges, and
                 case of publicly owned utilities).                                   standby charges. You should not
                                                                                      hesitate to question any charges that
                 Indemnification                                                      seem inappropriate to you. Federal
                 An indemnity is an agreement                                         law (Public Utility Regulatory Policies
                 between two parties in which one                                     Act of 1978, or PURPA, Section 210)
                 agrees to secure the other against loss                              prohibits utilities from assessing dis-
                 or damage arising from some act or                                   criminatory charges to customers who
                 some assumed responsibility. In the                                  have their own generation facilities.
                 context of customer-owned generat-
                 ing facilities, utilities often want
                 customers to indemnify them for any
                 potential liability arising from the
                 operation of the customer’s generating

                                                                         Connecting to the Utility Grid:
                                                                         A Success Story
                                                                         This 10-kW Bergey wind turbine, installed on
                                                                         a farm in Southwestern Kansas in 1983, pro-
                                                                         duces an average 1700–1800 kilowatt-hours per
                                                                         month, reducing the user’s monthly utility bills
                                                                         by approximately 50%. The turbine cost about
                                                                         $20,000 when it was installed. Since then, the
                                                                         cost for operation and maintenance has been
                                                                         about $50 per year. The only unscheduled main-
                                                                         tenance activity over the years was repair to the
                                                                         turbine required as a result of a lightning strike.
                                                                         Insurance covered all but $500 of the $9000 cost of
                                                                         damages. The basic system parts include:
                                           Warren Gretz, NREL/PIX09634

                                                                         Bergey XL.10 wind turbine
                                                                         100-foot free-standing lattice tower
                                                                              Small Wind Electric Systems                       

                                 Hybrid Power Systems                                                 A .hybrid .system .
             Combine multiple sources to deliver non-intermittent electric power                      that .combines .a .
                                                                                                      wind .system .with .a .
                                                                                                      solar .and/or .diesel .
                                                                                                      generator .can .
                                                                                                      provide .reliable .off-
                                                                                                      grid .power .around .
                                                                                                      the .clock . .
                                   PV modules


                                                                  AC or            Load
                                            Regulation and         DC


                                             Battery bank

Can I Go “Off-Grid”?                              For the times when neither the wind
                                                  turbine nor the PV modules are pro-
Hybrid Systems
                                                  ducing, most hybrid systems provide
Hybrid wind energy systems can                    power through batteries and/or an
provide reliable off-grid power for               engine-generator powered by conven-
homes, farms, or even entire com-                 tional fuels such as diesel. If the bat-
munities (a co-housing project, for               teries run low, the engine-generator
example) that are far from the near-              can provide power and recharge
est utility lines. According to many              the batteries. Adding an engine-
renewable energy experts, a “hybrid”              generator makes the system more
system that combines wind and                     complex, but modern electronic
photovoltaic (PV) technologies offers             controllers can operate these systems
several advantages over either single             automatically. An engine-generator
system. In much of the United States,             can also reduce the size of the other
wind speeds are low in the summer                 components needed for the system.
when the sun shines brightest and                 Keep in mind that the storage capac-
longest. The wind is strong in the                ity must be large enough to supply
winter when less sunlight is available.           electrical needs during non-charging
Because the peak operating times                  periods. Battery banks are typically
for wind and PV occur at different                sized to supply the electric load for
times of the day and year, hybrid                 one to three days.
systems are more likely to produce
power when you need it. (For more                 An off-grid hybrid system may be
information on solar electric or PV               practical for you if:
systems, contact the Energy Efficiency            • You live in an area with average
and Renewable Energy Information                    annual wind speed of at least
Portal—see For More Information.)                   9 mph (4.0 m/s)
                                                  • A grid connection is not available
                                                    or can only be made through an
0   Small Wind Electric Systems

                   expensive extension. The cost of                                  • You would like to gain energy
                   running a power line to a remote                                    independence from the utility
                   site to connect with the utility grid                             • You would like to generate clean
                   can be prohibitive, ranging from                                    power.
                   $15,000 to more than $50,000 per
                   mile, depending on terrain.

                   Living Off-Grid: A Success Story
                   This home, built near Ward, Colorado (at an elevation of 9000 feet), has been
                   off-grid since it was built in 1972. When the house was built, the nearest util-
                   ity was over a mile away, and it would have cost between $60K–$70K (based
                   on 1985 rates) to connect to the utility lines. The owners decided to install a
                                                        hybrid electric system powered by wind,
                                                        solar, and a generator for a cost of about
                                                        $19,700. The parts of the system include:
                                                                               Bergey 1.5-kW wind turbine, 10-ft (3-m)
                                                                               diameter rotor, 70-ft. (21-m) tower
                                                                               Solarex PV panels, 480 watts
                                                                               24 DC battery bank, 375 ampere-hours
                                                                               Trace sine wave inverter, 120 AC, 1 phase,
                                                                               4 kW
                                                                               Onan propane-fueled generator, 6.5 kW
                                                                               rated (3 kW derated for altitude)
                                                                               Electric appliances in the home include
                                                                               television, stereo, two computers, toaster,
                                                                               blender, vacuum cleaner, and hair dryer.
                                                                               The largest electric loads are created by
                                                                               a well pump and washing machine. The
                                                                               generator runs about 20% of the time, par-
                                                                               ticularly when the washing machine
                                                                               is in use. Propane serves the other major
                                                                               loads in the home: range, refrigerator, hot
                                                    Jim Green, NREL/PIX02796

                                                                               water, and space heat. Solar collectors on
                                                                               the roof provide pre-heating for the hot
                                                                 Small Wind Electric Systems   

Glossary of Terms                         kWh—Kilowatt-hour, a measure
Airfoil—The shape of the blade cross-     of energy equal to the use of one
section, which for most modern hori-      kilowatt in one hour.
zontal axis wind turbines is designed     MW—Megawatt, a measure of power
to enhance the lift and improve tur-      (1,000,000 watts).
bine performance.
                                          Nacelle—The body of a propeller-type
Ampere-hour—A unit for the quantity       wind turbine, containing the gearbox,
of electricity obtained by integrating    generator, blade hub, and other parts.
current flow in amperes over the time
                                          O&M .costs—Operation and mainte-
in hours for its flow; used as a mea-
                                          nance costs.
sure of battery capacity.
                                          Power .coefficient—The ratio of the
Anemometer—A device to measure
                                          power extracted by a wind turbine
the wind speed.
                                          to the power available in the wind
Average .wind .speed—The mean wind        stream.
speed over a specified period of time.
                                          Power .curve—A chart showing a
Blades—The aerodynamic surface that       wind turbine’s power output across
catches the wind.                         a range of wind speeds.
Brake—Various systems used to stop        PUC—Public Utility Commission, a
the rotor from turning.                   state agency which regulates utilities.
Converter—See Inverter.                   In some areas known as Public Service
                                          Commission (PSC).
Cut-in .wind .speed—The wind speed
at which a wind turbine begins to         PURPA—Public Utility Regulatory
generate electricity.                     Policies Act (1978), 16 U.S.C. § 2601.18
                                          CFR §292 that refers to small
Cut-out .wind .speed—The wind speed       generator utility connection rules.
at which a wind turbine ceases to
generate electricity.                     Rated .output .capacity—The output
                                          power of a wind machine operating
Density—Mass per unit of volume.          at the rated wind speed.
Downwind—On the opposite side             Rated .wind .speed—The lowest wind
from the direction from which the         speed at which the rated output
wind blows.                               power of a wind turbine is produced.
Furling—A passive protection for the      Rotor—The rotating part of a wind
turbine in which the rotor folds either   turbine, including either the blades
up or around the tail vane.               and blade assembly or the rotating
Grid—The utility distribution system.     portion of a generator.
The network that connects electricity     Rotor .diameter—The diameter of the
generators to electricity users.          circle swept by the rotor.
HAWT—Horizontal axis wind turbine.        Rotor .speed—The revolutions per
Inverter—A device that converts direct    minute of the wind turbine rotor.
current (DC) to alternating current       Start-up .wind .speed—The wind speed
(AC).                                     at which a wind turbine rotor will
kW—Kilowatt, a measure of power for       begin to spin. See also Cut-in wind
electrical current (1000 watts).          speed.
   Small Wind Electric Systems

                 Swept .area—The area swept by the         Wind Energy Basics
                 turbine rotor, A = π R2, where R is the   Paul Gipe
                 radius of the rotor.                      ISBN 1-890132-07-01
                 Tip .speed .ratio—The speed at the tip    A comprehensive guide to modern
                 of the rotor blade as it moves through    small wind technology.
                 the air divided by the wind velocity.     American Wind Energy Association
                 This is typically a design requirement    (202) 383-2500
                 for the turbine.                
                 Turbulence—The changes in wind            Chelsea Green Publishing Company
                 speed and direction, frequently 
                 caused by obstacles.
                                                           Wind Energy Resource Atlas of the
                 Upwind—On the same side as the            United States
                 direction from which the wind is          D. Elliott et al.
                 blowing—windward.                         American Wind Energy Association
                 VAWT—Vertical axis wind turbine.          (202) 383-2500
                 Wind .farm—A group of wind tur-
                 bines, often owned and maintained by
                 one company. Also known as a wind         Wind Power for Home, Farm, and
                 power plant.                              Business: Renewable Energy for the
                                                           New Millenium
                 Yaw—The movement of the tower top
                                                           Paul Gipe
                 turbine that allows the turbine to stay
                 into the wind.
                                                           Completely revised and expanded
                 For More Information                      edition of Wind Power for Home and
                 Books                                     Chelsea Green Publishing Company
                 A Siting Handbook for Small Wind
                 Energy Conversion Systems
                                                           Wind Power Workshop
                 H. Wegley, J. Ramsdell, M. Orgill and
                                                           Hugh Piggott
                 R. Drake
                                                           Provides an overview on how to
                 Report No. PNL-2521 Rev.1, 1980
                                                           design a home-built wind turbine.
                 National Technical Information
                                                           The Center for Alternative
                 5285 Port Royal Rd.
                                                           Machynlleth, Powys
                 Springfield, VA 22151
                                                           SY20 9AZ, UK
                 (800) 553-6847
                                                           Phone: 06154-702400
                 Energy Savers Tips on Saving Energy
                 and Money at Home — A consumer’s
                 guide for saving energy and reducing
                 utility bills.
                                                              Small Wind Electric Systems   

Government Agencies                     Videos
U.S. Department of Energy’s Energy      An Introduction to Residential Wind
Efficiency and Renewable Energy         Systems with Mick Sagrillo
Information Portal                      A 63-minute video answering ques-                     tions most often asked by homeown-
                                        ers as they consider purchasing and
National Climatic Data Center
                                        installing wind power systems
Federal Building, 151 Patton Avenue
                                        American Wind Energy Association
Asheville, North Carolina, 28801-5001
                                        Phone: (202) 383-2500
Phone: (828) 271-4800
U.S. Department of Commerce             Web Sites
National Technical Information          Small Wind Systems
Service                                 Includes answers to frequently asked
5285 Port Royal Road                    questions and information on U.S.
Springfield, Virginia 22161             manufacturers.
(800) 553-6847                                            Database of State Incentives for
Non-Government Organizations            Renewable Energy
American Wind Energy Association
1101 14th St., NW                       Green Power Network Net Metering
12th Floor                              Net metering programs are now avail-
Washington, D.C. 20005                  able in more than 35 states.
Phone: (202) 383-2500                                     markets
Solar Energy International              Small Wind “Talk” on the Web
Short courses on renewable energy       AWEA’s Home Energy Systems elec-
and sustainable development             tronic mailing list is a forum for the
Phone: (970) 963-8855                   discussion of small-scale energy sys-                     tems that include wind. To subscribe,
                                        send a subscription request to awea-
Apples and Oranges
                                        Wind Energy for Homeowners
Mick Sagrillo
                                        This Web page covers items you
A comprehensive comparison of
                                        should consider before investing
available small wind turbines avail-
                                        in a small wind energy system and
able on the Home Power Magazine
                                        provides basic information about the
Web site:
Home Power Magazine           
The definitive bimonthly magazine       wind.html
for the homemade power enthusiast.
                                        Wind Resource Assessment
Phone: (800)707-6586
   Small Wind Electric Systems

                 2002 Farm Bill — Wind                           The amount of the payments depends on
                                                                 the size of the wind installation, the pro-
                 Energy Development                              duction of electricity by that system, and
                 Provisions                                      the length of the contract period. Mainstay
                                                                 offers 3-, 5-, and 10-year purchase con-
                 Renewable Energy Systems and
                                                                 tracts. The longer contract periods provide
                 Energy Efficiency Improvements                  greater incentive payments on a $/kWh
                 Incentive Type: Low-interest loans, loan        basis. Typical payments for wind, which
                      guarantees, and grants                     are made quarterly, range from 0.2¢/kWh
                 Eligible Technologies: Renewable energy         to 1.5¢/kWh.
                      systems (energy derived from wind,
                      solar, biomass, geothermal, and hydro-     There is a $100 certification fee to get
                      gen derived from biomass or water          started with Mainstay Rewards. However,
                      using a renewable energy source) and       the fee may be paid with future green tag
                      energy efficiency improvements.            sales, and is generally waived for partici-
                 Applicable Sectors: Agriculture, rural          pants who opt for 10-year contracts.
                      small commercial                           The requirements are:
                 Amount: Varies. The grant may not exceed         1. The system must be grid-connected;
                      25% of the cost of a project, and a com-    2. Net-metering by the utility does not
                      bined grant and loan or guarantee may          restrict the system owner from selling
                      not exceed 50% of the cost of a project.       the green tags;
                 Terms: 2003 – 2007                              3. The system owner must have title to the
                 Date Enacted: 2002                                  green tags or renewable energy credits.
                 Authority: Farm Bill, Title IX, Section 9006        They cannot have been sold
                 Summary: This law allows direct financial           or transferred to any other entity;
                 assistance to farmers, ranchers, and rural       4. The system must be a new renewable,
                 small businesses for the purchase of wind           which, in most states, means pow-
                 power and other renewable energy sys-               ered up on or after 1/1/1999. See the
                 tems and for energy efficiency improve-             Mainstay Energy web site for
                 ments. This program is authorized for               exceptions;
                 funding for up to $23,000,000 per year in        5. For any systems over 10 kW, the system
                 2003-2007, totaling up to $115 million. In          generation must be metered separately.
                 determining the amount of a grant or loan,          For systems under 10 kW, separate
                 USDA shall consider the type of renewable           metering is not necessary. Payments
                 energy system, the quantity of energy likely        are made based on estimated
                 to be generated, the expected environmen-           production.
                 tal benefits, the extent to which the system    Contact:
                 is replicable, and the amount of energy         Mainstay Rewards Program
                 savings from energy efficiency improve-         Mainstay Energy
                 ments and the likely payback period.            161 E. Chicago Ave.
                 USDA Rural Development State Office             Suite 41B
                 contacts can be found at www.rurdev.            Chicago, IL 60611-2624
                     Phone: (877) 473-3682
                                                                 Fax: (312) 896-1515
                 USDA Farm Bill Web site: www.rurdev.            E-Mail:
                      Web site:
                 Green Tag Purchase Program
                 Mainstay Energy is a private company
                 offering customers who install, or have
                 installed, renewable energy systems the
                 opportunity to sell the green tags (also
                 known as renewable energy credits, or
                 RECs) associated with the energy gener-
                 ated by these systems. These green tags
                 will be brought to market as Green-e*
        or state certified
                 products. Participating customers receive
                 regular, recurring payments through the
                 Mainstay Energy Rewards Program.
                                                                      Small Wind Electric Systems

Incentives for Small Wind in the United States
For a comprehensive overview of the incentives for small wind projects, visit the DSIRE (Database of
State Incentives for Renewables and Efficiency) Web site at
U.S. Department of Energy
Wind Energy Program

Wind Powering America

A Strong Energy Portfolio for a Strong America
Energy efficiency and clean, renewable energy will mean a stronger economy, a cleaner environment, and greater energy
independence for America. Working with a wide array of state, community, industry, and university partners, the U.S. Department
of Energy’s Office of Energy Efficiency and Renewable Energy invests in a diverse portfolio of energy technologies.

Produced for the U.S. Department of Energy by the                                For more information contact:
National Renewable Energy Laboratory,                                            EERE Information Center
a DOE national laboratory                                                        1-877-EERE-INF (1-877-337-3463)
DOE/GO-102007-2465 • August 2007
Printed with a renewable-source ink on paper containing at least 50% wastepaper, including 20% postconsumer waste.

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