Small Wind Electric Systems - NREL · Small Wind Electric Systems Cover photo: The Liberty Science...

ANew Jersey

Consumer's Guide

Small Wind Electric SystemsSmall Wind Electric Systems

U.S. Department of EnergyEnergy Efficiency and Renewable Energy

Wind and Hydropower Technologies Program

Small Wind Electric Systems

Cover photo: The Liberty Science Center in Liberty State Park, Jersey City, New Jersey, installed a 10-kilowattBergey wind turbine in April 2001 as a working exhibit. This grid-connected turbine helps to reduce the center'sutility bill and is a participant in the U.S. Department of Energy's Field Verification Project. Photo credit — NREL/PIX12336

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IntroductionCan I use wind energy to power myhome? This question is being askedacross the country as more peoplelook for affordable and reliablesources of electricity.

Small wind electric systems canmake a significant contribution toour nation's energy needs. Althoughwind turbines large enough to pro-vide a significant portion of the elec-tricity needed by the average U.S.home generally require one acre ofproperty or more, approximately21 million U.S. homes are built onone-acre and larger sites, and 24% of the U.S. population lives in ruralareas.

A small wind electric system willwork for you if:

• There is enough wind where youlive

• Tall towers are allowed in yourneighborhood or rural area

• You have enough space

• You can determine how muchelectricity you need or want toproduce

• It works for you economically.

The purpose of this guide is to pro-vide you with the basic informationabout small wind electric systems tohelp you decide if wind energy willwork for you.

Why Should I Choose Wind?

Wind energy systems are one of themost cost-effective home-basedrenewable energy systems.

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ContentsIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1First, How Can I Make My Home More Energy Efficient? . . . .2Is Wind Energy Practical for Me? . . . . . . . . . . . . . . . . . . . . . .3What Size Wind Turbine Do I Need? . . . . . . . . . . . . . . . . . . . .4What are the Basic Parts of a Small Wind Electric System? . .5What Do Wind Systems Cost? . . . . . . . . . . . . . . . . . . . . . . . .7Where Can I Find Installation and Maintenance Support? . . . .8How Much Energy Will My System Generate? . . . . . . . . . . . .9Is There Enough Wind on My Site? . . . . . . . . . . . . . . . . . . . .11How Do I Choose the Best Site for My Wind Turbine? . . . . .14Can I Connect My System to the Utility Grid? . . . . . . . . . . . .15Can I Go "Off-Grid"? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19Glossary of Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21For More Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

Small Wind Electric SystemsA U.S. Consumer's Guide

Homeowners, ranchers, and small businesses can use wind-generated electricity to reduce their utility bills. This grid-connected system installed for a home in Norman, Oklahoma,reduces the homeowner's utility bill by $100 per month.

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2002 Farm Bill — WindEnergy DevelopmentProvisionsRenewable Energy Systems andEnergy Efficiency ImprovementsIncentive Type: Low-interest loans, loan

guarantees, and grantsEligible Technologies: Renewable energy

systems (energy derived from wind,solar, biomass, geothermal, and hydro-gen derived from biomass or waterusing a renewable energy source) andenergy efficiency improvements.

Applicable Sectors: Agriculture, ruralsmall commercial

Amount: Varies. The grant may not exceed25% of the cost of a project, and a com-bined grant and loan or guarantee maynot exceed 50% of the cost of a project.

Terms: 2003 – 2007Date Enacted: 2002Authority: Farm Bill, Title IX, Section 9006Summary: This law allows direct financial assistance to farmers, ranchers, and ruralsmall businesses for the purchase of windpower and other renewable energy sys-tems and for energy efficiency improve-ments. This program is funded at$23,000,000 each year in 2003-2007, totaling$115 million. In determining the amount ofa grant or loan, USDA shall consider thetype of renewable energy system, thequantity of energy likely to be generated,the expected environmental benefits, theextent to which the system is replicable,and the amount of energy savings fromenergy efficiency improvements and thelikely payback period.

Conservation Reserve ProgramIncentive Type: CRP paymentsEligible Technologies: Wind turbinesApplicable Sectors: AgricultureAmount: No reduction in CRP payments

when a wind turbine is installed onCRP land (subject to USDA approval)

Effective Date: 2002Authority 1: Farm Bill, Titles II and VI,

Section 2101Authority 2: Section 1232(a)(7) of the Food

Security Act of 1985, 16 U.S.C. § 3831,et seq.

Summary: Wind turbine installations arenow allowed on Conservation ReserveProgram lands with no reduction in CRPpayments. However, the wind turbine installations are subject to USDA approval,

taking into account the site location, habitat, and the purpose of the CRP.

Value-Added Agricultural ProductMarket Development GrantsIncentive Type: GrantsEligible Technologies: Renewable energy

systems (energy derived from wind,solar, geothermal, hydrogen, and biomass—biomass is specificallydefined and excludes both paper that is commonly recycled and unsegregat-ed solid wastes).

Applicable Sectors: AgricultureAmount: Maximum grant amount is

$500,000 per projectTerms: 2002 – 2007Authority 1: Farm Bill, Titles II and VI,

section 6401Authority 2: Section 231 of the Agricultural

Risk Protection Act of 2000, 7 U.S.C. §1621 note.

Summary: Titles II and VI, section 6401 of the Farm Bill amends Section 231 of the Agricultural Risk Protection Act of2000, 7 U.S.C. § 1621 note to expand thedefinition of the term “value-added agricultural product” to include farm- andranch-based renewable energy. The pro-gram provides for competitive grants toassist producers of value-added agricultur-al products, including renewable energysystems, to develop feasibility studies, business plans, and marketing strategies.Recipients also can use the grant to pro-vide capital to establish alliances or busi-ness ventures.

The maximum grant amount is $500,000per project. The program is funded at$40,000,000 for each year in 2002-2007, to be made available from the CommodityCredit Corporation, totaling $240 million.

ContactsWilliam F. Hagy IIIDeputy Administrator, Business ProgramsPhone: 202-720-7287E-mail: [email protected]

Chris HumesPhone: 202-720-0813E-mail: [email protected] Business-Cooperative Service1400 Independence Ave., S.W.Washington, D.C. 20250-3220

Depending on your wind resource, asmall wind energy system can loweryour electricity bill by 50% to 90%,help you avoid the high costs of having utility power lines extended to remote locations, prevent power interruptions, and it is nonpolluting.

How Do Wind Turbines Work?

Wind is created by the unequal heat-ing of the Earth's surface by the sun.Wind turbines convert the kineticenergy in wind into mechanicalpower that runs a generator to produce clean electricity. Today's turbines are versatile modular sourcesof electricity. Their blades are aerody-namically designed to capture themaximum energy from the wind. Thewind turns the blades, which spin ashaft connected to a generator thatmakes electricity.

First, How Can I Make My Home More EnergyEfficient? Before choosing a wind system foryour home, you should considerreducing your energy consumption bymaking your home or business moreenergy efficient. Reducing your energy consumption will significantlylower your utility bills and willreduce the size of the home-basedrenewable energy system you need.To achieve maximum energy effi-ciency, you should take a whole-building approach. View your homeas an energy system with interrelatedparts, all of which work synergisti-cally to contribute to the efficiency ofthe system. From the insulation inyour home's walls to the light bulbs inits fixtures, there are many ways youcan make your home more efficient.

• Reduce your heating and coolingneeds by up to 30% by investingjust a few hundred dollars in

proper insulation andweatherization products.

• Save money and increase comfortby properly maintaining andupgrading your heating,ventilation, and air-conditioningsystems.

• Install double-paned, gas-filledwindows with low-emissivity (low-e) coatings to reduce heat loss in cold climates and spectrallyselective coatings to reduce heatgain in warm climates.

• Replace your lights in high-useareas with fluorescents. Replacing25% of your lights can save about50% of your lighting energy bill.

• When shopping for appliances,look for the ENERGY STAR® label.ENERGY STAR® appliances havebeen identified by the U.S.Environmental Protection Agencyand U.S. Department of Energy as being the most energy-efficientproducts in their classes.

• For more information on how tomake your home energy efficient,see Energy Savers, in the For MoreInformation section.


Government Agencies

Energy Efficiency and RenewableEnergy Clearinghouse, P.O. Box 3048,Merrifield, Virginia 22116 800-DOE-EREC (363-3732). http://www.eren.doe.gov

National Climatic Data Center,Federal Building, 151 Patton Avenue,Asheville, North Carolina, 28801-5001.(828) 271-4800. Fax (828) 271-4876.http://www.ncdc.noaa.gov

U.S. Department of Commerce,National Technical InformationService, 5285 Port Royal Road,Springfield, Virginia 22161. (800) 553-6847. http://www.ntis.gov/ordering.htm

Non-Government Organizations

American Wind Energy Association,122 C Street, N.W. 4th Floor,Washington, D.C. 20001. (202) 383-2500. http://www.awea.org

Solar Energy International—Shortcourses on renewable energy and sustainable development, inCarbondale, Colorado. (970) 963-8855.http://www.solarenergy.org

Periodicals

"Apples and Oranges" by MickSagrillo—A comprehensive compari-son of available small wind turbines.On Home Power Magazine Web site:http://www.homepower.com

Home Power Magazine—The defini-tive bimonthly magazine for thehomemade power enthusiast.(800)707-6586 or on the Web at:http://www.homepower.com

Videos

An Introduction to Residential WindSystems with Mick Sagrillo—A 63-minute video answering questionsmost often asked by homeowners as they consider purchasing andinstalling their own wind power

systems. Order from AWEA (202) 383-2500, http://www.awea.org

Web Sites

AWEA Small Wind Systems Website—Includes answers to frequentlyasked questions and information onU.S. manufacturers. http://www.awea.org/smallwind.html

Database of State Incentives forRenewable Energy—On the Web athttp://www.dcs.ncsu.edu/solar/dsire/dsire.html

Green Power Network Net MeteringWeb Site—Net metering programs arenow available in 30 states. Visit thisDOE Web site for information:http://www.eren.doe.gov/greenpower/netmetering

Small Wind "Talk" on the Web—AWEA's Home Energy Systems elec-tronic mailing list is designed as aforum for the discussion of small-scaleenergy systems that include wind. Tosubscribe, send a subscription [email protected].

Wind Energy for Homeowners—ThisWeb site discusses things you shouldconsider before investing in a smallwind energy system and providesbasic information about the systems.http://www.eren.doe.gov/wind/homeowner.html

Lighting,cooking,and otherappliances

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Home Energy UseBased on national averages

The largest portion of a utility bill for a typicalhouse is for heating and cooling.


Is Wind Energy Practicalfor Me?A small wind energy system can provide you with a practical and economical source of electricity if:

• your property has a good windresource

• your home or business is located onat least one acre of land in a ruralarea

• your local zoning codes orcovenants allow wind turbines

• your average electricity bills are$150 per month or more

• your property is in a remotelocation that does not have easyaccess to utility lines

• you are comfortable with long-terminvestments.

Zoning Issues

Before you invest in a wind energysystem, you should research potentialobstacles. Some jurisdictions, forexample, restrict the height of the

structures permitted in residentiallyzoned areas, although variances areoften obtainable. Most zoning ordi-nances have a height limit of 35 feet.You can find out about the zoningrestrictions in your area by calling the local building inspector, board ofsupervisors, or planning board. Theycan tell you if you will need to obtaina building permit and provide youwith a list of requirements.

In addition to zoning issues, yourneighbors might object to a windmachine that blocks their view, orthey might be concerned about noise.Most zoning and aesthetic concernscan be addressed by supplying objec-tive data. For example, the ambientnoise level of most modern residentialwind turbines is around 52 to 55 deci-bels. This means that while the soundof the wind turbine can be picked outof surrounding noise if a consciouseffort is made to hear it, a residential-sized wind turbine is no noisier thanyour average refrigerator.


In Clover Valley,Minnesota, this 3-kW WhisperH175 turbine on a 50-foot tower isconnected to theutility grid to offsetthe farm's utility-supplied electricity.

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What Size Wind Turbine Do I Need?The size of the wind turbine you needdepends on your application. Smallturbines range in size from 20 watts to100 kilowatts. The smaller or "micro"(20–500-watt) turbines are used in avariety of applications such as charg-ing batteries for recreational vehiclesand sailboats.

One- to 10-kW turbines can be used inapplications such as pumping water.Wind energy has been used for cen-turies to pump water and grind grain.Although mechanical windmills stillprovide a sensible, low-cost option forpumping water in low-wind areas,farmers and ranchers are finding thatwind-electric pumping is a little moreversatile and they can pump twice the volume for the same initial investment. In addition, mechanicalwindmills must be placed directlyabove the well, which may not takethe best advantage of available windresources. Wind-electric pumping systems can be placed where the windresource is the best and connected tothe pump motor with an electriccable.

Turbines used in residential applica-tions can range in size from 400 wattsto 100 kW (100 kW for very largeloads), depending on the amount ofelectricity you want to generate. Forresidential applications, you shouldestablish an energy budget to helpdefine the size of turbine you willneed. Because energy efficiency isusually less expensive than energyproduction, making your house moreenergy efficient first will probably bemore cost effective and will reduce the size of the wind turbine you need(see How Can I Make My Home More Energy Efficient?). Wind turbinemanufacturers can help you size yoursystem based on your electricity needs and the specifics of local windpatterns.

A typical home uses approximately9400 kilowatt-hours (kWh) of electric-ity per year (about 780 kWh permonth). Depending on the averagewind speed in the area, a wind tur-bine rated in the range of 5 to 15 kilo-watts (kW) would be required tomake a significant contribution to thisdemand. A 1.5- kW wind turbine willmeet the needs of a home requiring300 kWh per month in a location witha 14-mile-per-hour (6.26-meters-per-second) annual average wind speed.The manufacturer can provide youwith the expected annual energy out-put of the turbine as a function ofannual average wind speed. The manufacturer will also provide infor-mation on the maximum wind speedat which the turbine is designed tooperate safely. Most turbines haveautomatic overspeed-governing sys-tems to keep the rotor from spinningout of control in very high winds. Thisinformation, along with your localwind speed and your energy budget,will help you decide which size tur-bine will best meet your electricityneeds.


Glossary of TermsAirfoil—The shape of the blade cross-section, which for most modern hori-zontal axis wind turbines, is designedto enhance the lift and improve tur-bine performance.

Ampere-hour—A unit of for the quan-tity of electricity obtained by integrat-ing current flow in amperes over thetime in hours for its flow; used as ameasure of battery capacity.

Anemometer—A device to measurethe wind speed.

Average wind speed—The mean windspeed over a specified period of time.

Blades—The aerodynamic surfacethat catches the wind.

Brake—Various systems used to stopthe rotor from turning.

Converter—See Inverter.

Cut-in wind speed—The wind speedat which a wind turbine begins togenerate electricity.

Cut-out wind speed—The wind speedat which a wind turbine ceases to generate electricity.

Density—Mass per unit of volume.

Downwind—On the opposite sidefrom the direction from which thewind is blowing.

Furling—A passive protection for theturbine where typically the rotor foldseither up or around the tail vane.

Grid—The utility distribution system. The network that connects electricitygenerators to electricity users.

HAWT—Horizontal axis wind turbine.

Inverter—A device that converts directcurrent (DC) to alternating current(AC).

kW—Kilowatt, a measure of powerfor electrical current (1000 watts).

kWh—Kilowatt-hour, a measure of energy equal to the use of one kilowatt in one hour.

MW—Megawatt, a measure of power(1,000,000 watts).

Nacelle—The body of a propeller-typewind turbine, containing the gearbox,generator, blade hub, and other parts.

O&M Costs—Operation and mainte-nance costs.

Power Coefficient—The ratio of thepower extracted by a wind turbine to the power available in the windstream.

Power curve—A chart showing awind turbine's power output across a range of wind speeds.

PUC—Public Utility Commission, astate agency which regulates utilities.In some areas known as Public ServiceCommission (PSC).

PURPA—Public Utility RegulatoryPolicies Act (1978), 16 U.S.C. § 2601.18CFR §292 that refers to small generator utility connection rules.

Rated output capacity—The outputpower of a wind machine operating at the rated wind speed.

Rated wind speed—The lowest windspeed at which the rated outputpower of a wind turbine is produced.

Rotor—The rotating part of a windturbine, including either the bladesand blade assembly or the rotatingportion of a generator.

Rotor diameter—The diameter of thecircle swept by the rotor.

Rotor speed—The revolutions perminute of the wind turbine rotor.

Start-up wind speed—The wind speedat which a wind turbine rotor willbegin to spin. See also cut-in windspeed.


This 1 kW Whisperturbine providesdirect AC power forthe water pump forstock tanks on aranch in Wheeler,Texas.

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What are the Basic Parts of a Small Wind ElectricSystem?Home wind energy systems gener-ally comprise a rotor, a generator oralternator mounted on a frame, a tail (usually), a tower, wiring, and the"balance of system" components: controllers, inverters, and/or batter-ies. Through the spinning blades, therotor captures the kinetic energy ofthe wind and converts it into rotarymotion to drive the generator.

Wind Turbine

Most turbines manufactured todayare horizontal axis upwind machinesthat have two or three blades, whichare usually made of a composite mate-rial such as fiberglass.

The amount of power a turbine willproduce is determined primarily bythe diameter of its rotor. The diameterof the rotor defines its "swept area," orthe quantity of wind intercepted bythe turbine. The turbine's frame is thestructure onto which the rotor, genera-tor, and tail are attached. The tailkeeps the turbine facing into thewind.

Tower

Because wind speeds increase withheight, the turbine is mounted on a tower. In general, the higher thetower, the more power the wind system can produce. The tower alsoraises the turbine above the air turbulence that can exist close to the ground because of obstructionssuch as hills, buildings, and trees. Ageneral rule of thumb is to install awind turbine on a tower with thebottom of the rotor blades at least30 feet (9 meters) above any obstaclethat is within 300 feet (90 meters) ofthe tower. Relatively small invest-ments in increased tower height canyield very high rates of return in

power production. For instance, toraise a 10-kW generator from a 60-foottower height to a 100-foot towerinvolves a 10% increase in overall system cost, but it can produce 25%more power.

There are two basic types of towers:self-supporting (free standing) andguyed. Most home wind power sys-tems use a guyed tower. Guyed tow-ers, which are the least expensive, canconsist of lattice sections, pipe, or tub-ing depending on the design, andsupporting guy wires. They are easierto install than self-supporting towers.However, because the guy radiusmust be one-half to three-quarters of the tower height, guyed towersrequire enough space to accommodatethem. While tilt-down towers aremore expensive they offer the con-sumer an easy way to perform


Basic Parts of a Small Wind Electric System

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Tilt-Down Tower

Tilt-up towerin the normaloperating positionTilt-up tower in the

lowered position formaintenance or hurricanes

Tilt-down towersprovide easymaintenance forturbines.

maintenance on smaller light-weightturbines, usually 5 kW or less. Tilt-down towers can also be lowered tothe ground during hazardous weathersuch as hurricanes. Aluminum towersare prone to cracking and should beavoided. Most turbine manufacturersprovide wind energy system packagesthat include towers.

Mounting turbines on rooftops is notrecommended. All wind turbinesvibrate and transmit the vibrationto the structure on which they are

mounted. This can lead to noise andstructural problems with the building,and the rooftop can cause excessiveturbulence that can shorten the life ofthe turbine.

Balance of System

The parts that you need in addition tothe turbine and the tower, or the bal-ance of system parts, will depend onyour application. Most manufacturerscan provide you with a system pack-age that includes all the parts youneed for your application. For exam-ple, the parts required for a waterpumping system will be much differ-ent than what you need for a residen-tial application. The balance of systemrequired will also depend on whetherthe system is grid-connected, stand-alone, or part of a hybrid system. For

a residential grid-connected applica-tion, the balance of system parts mayinclude a controller, storage batteries,a power conditioning unit (inverter),and wiring. Some wind turbine controllers, inverters, or other electri-cal devices may be stamped by a recognized testing agency, likeUnderwriters Laboratories.

Stand-Alone Systems

Stand-alone systems (systems not con-nected to the utility grid) require bat-teries to store excess power generatedfor use when the wind is calm. Theyalso need a charge controller to keepthe batteries from overcharging.Deep-cycle batteries, such as thoseused for golf carts, can discharge andrecharge 80% of their capacity hun-dreds of times, which makes them agood option for remote renewableenergy systems. Automotive batteriesare shallow-cycle batteries and shouldnot be used in renewable energy sys-tems because of their short life indeep-cycling operations.


Can I Go "Off-Grid"?Hybrid Systems

Hybrid wind energy systems can provide reliable off-grid power forhomes, farms or even entire com-munities (a co-housing project, for example) that are far from the nearestutility lines. According to manyrenewable energy experts, a "hybrid"system that combines wind and photovoltaic (PV) technologies offersseveral advantages over either singlesystem. In much of the United States,wind speeds are low in the summerwhen the sun shines brightest andlongest. The wind is strong in thewinter when there is less sunlightavailable. Because the peak operatingtimes for wind and PV occur at differ-ent times of the day and year, hybridsystems are more likely to producepower when you need it. (For moreinformation on solar electric or PV systems, contact the EnergyEfficiency and Renewable EnergyClearinghouse—see For MoreInformation.)

For the times when neither the windnor the PV modules are producing,most hybrid systems provide powerthrough batteries and/or an engine-generator powered by conventionalfuels such as diesel. If the batteriesrun low, the engine-generator can provide power and recharge the bat-teries. Adding an engine-generatormakes the system more complex, butmodern electronic controllers canoperate these systems automatically.An engine-generator can also reducethe size of the other componentsneeded for the system. Keep in mindthat the storage capacity must be large enough to supply electricalneeds during non-charging periods.Battery banks are typically sized tosupply the electric load for one tothree days.

An off-grid hybrid system may bepractical for you if:

• You live in an area with averageannual wind speed of at least9 mph (4.0 m/s).

• A grid connection is not availableor can only be made through an

A Bergey XL.10, 10-kW wind turbineis part of a grid-connectedwind/photovoltaichybrid system thatreduces the utilitypower used by thishome in Vermont.The balance ofsystem (upper right)includes from left to right, a Traceinverter for the PVsystem, a breakerbox, and aPowersync inverterfor the wind system.

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Small wind turbines generate directcurrent (DC) electricity. In very smallsystems, DC appliances operatedirectly off the batteries. If you wantto use standard appliances that useconventional household alternatingcurrent (AC), you must install aninverter to convert DC electricityfrom the batteries to AC. Althoughthe inverter slightly lowers the overall efficiency of the system, itallows the home to be wired for AC,a definite plus with lenders, electri-cal code officials, and future homebuyers.

For safety, batteries should be iso-lated from living areas and electron-ics because they contain corrosiveand explosive substances. Lead-acidbatteries also require protection fromtemperature extremes.

Grid-Connected Systems

In grid-connected systems, the onlyadditional equipment required is apower conditioning unit (inverter)that makes the turbine output electri-cally compatible with the utility grid.Usually, batteries are not needed.

What Do Wind SystemsCost?A small turbine can cost anywherefrom $3,000 to $35,000 installed,depending on size, application, andservice agreements with the manufac-turer. (The American Wind EnergyAssociation [AWEA] says a typicalhome wind system costs approxi-mately $32,000 (10 kW); a comparablephotovoltaic [PV] solar system wouldcost over $80,000.)

A general rule of thumb for estimatingthe cost of a residential turbine is$1,000 to $3,000 per kilowatt. Windenergy becomes more cost effective as the size of the turbine’s rotorincreases. Although small turbinescost less in initial outlay, they are

proportionally more expensive. Thecost of an installed residential windenergy system that comes with an 80-foot tower, batteries, and inverter,typically ranges from $13,000 to$40,000 for a 3 to 10 kW wind turbine.

Although wind energy systemsinvolve a significant initial invest-ment, they can be competitive withconventional energy sources whenyou account for a lifetime of reducedor avoided utility costs. The length ofthe payback period—the time beforethe savings resulting from your sys-tem equal the cost of the systemitself—depends on the system youchoose, the wind resource on yoursite, electricity costs in your area, andhow you use your wind system. Forexample, if you live in California andhave received the 50% buydown ofyour small wind system, have netmetering, and an average annualwind speed of 15 miles per hour(mph) (6.7 meters per second [m/s]),your simple payback would beapproximately 6 years.


A SouthwestWindpower Air303, 300 wattturbine is the solesource of electricityfor this remotehome in northernArizona.

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Things to Consider WhenPurchasing a Wind Turbine

Once you determine you can install awind energy system in compliancewith local land use requirements, youcan begin pricing systems and compo-nents. Comparatively shop for a windsystem as you would any major pur-chase. Obtain and review the productliterature from several manufacturers.As mentioned earlier, lists of manu-facturers are available from AWEA,(see For More Information), but not all small turbine manufacturers aremembers of AWEA. Check the yellowpages for wind energy system dealersin your area.

Once you have narrowed the field,research a few companies to be surethey are recognized wind energy businesses and that parts and servicewill be available when you needthem. You may wish to contact theBetter Business Bureau to check on

the company's integrity and ask forreferences of past customers withinstallations similar to the one you areconsidering. Ask the system ownersabout performance, reliability, andmaintenance and repair requirements,and whether the system is meetingtheir expectations. Also, find out howlong the warranty lasts and what itincludes.

Where Can I FindInstallation andMaintenance Support?The manufacturer/dealer should beable to help you install your machine.Many people elect to install themachines themselves. Before attempt-ing to install your wind turbine, askyourself the following questions:

• Can I pour a proper cementfoundation?

• Do I have access to a lift or a way oferecting the tower safely?

• Do I know the difference betweenAC and DC wiring?

• Do I know enough about electricityto safely wire my turbine?

• Do I know how to safely handleand install batteries?

If you answered no to any of theabove questions, you should probablychoose to have your system installedby a system integrator or installer.Contact the manufacturer for help or call your state energy office andlocal utility for a list of local systeminstallers. You can also check the yel-low pages for wind energy systemservice providers. A credible installerwill provide many services such aspermitting. Find out if the installer isa licensed electrician. Ask for refer-ences and check them out. You mayalso want to check with the BetterBusiness Bureau.


consequently wind energy installa-tions are governed by the generic provisions of the NEC.

If your wind turbine is connected tothe local utility grid so that any of thepower produced by your wind tur-bine is delivered to the grid, then yourutility also has legitimate concernsabout safety and power quality thatneed to be addressed. The utility’sprincipal concern is that your windturbine automatically stops deliveringany electricity to its power lines dur-ing a power outage. Otherwise lineworkers and the public, thinking thatthe line is "dead," might not take nor-mal precautions and might be hurt oreven killed by the power from yourturbine. Another concern among utili-ties is that the power from your facili-ty synchronize properly with theutility grid, and that it match the util-ity’s own power in terms of voltage,frequency, and power quality.

A few years ago, some state govern-ments started developing new standardized interconnection require-ments for small renewable energygenerating facilities (including windturbines). In most cases the newrequirements have been based on con-sensus-based standards and testingprocedures developed by independ-ent third-party authorities, such as theInstitute of Electrical and ElectronicEngineers and UnderwritersLaboratories.

Interconnection Requirements

Most utilities and other electricityproviders require you to enter into aformal agreement with them beforeyou interconnect your wind turbinewith the utility grid. In states thathave retail competition for electricityservice (e.g., your utility operates the local wires, but you have a choice of electricity provider) you may have to sign a separate

agreement with each company.Usually these agreements are writtenby the utility or the electricityprovider. In the case of private(investor-owned) utilities, the termsand conditions in these agreementsmust be reviewed and approved bystate regulatory authorities.

Insurance

Some utilities require small windturbine owners to maintain liabilityinsurance in amounts of $1 million ormore. Utilities consider these require-ments are necessary to protect themfrom liability for facilities they do notown and have no control over. Othersconsider the insurance requirementsexcessive and unduly burdensome,making wind energy uneconomic. Inthe 21 years since utilities have beenrequired to allow small wind systemsto interconnect with the grid there has never been a liability claim, letalone a monetary award, relating toelectrical safety.

Small windturbines like this10 kW BergeyXL.10 provideelectricity forhome, farm, andranch applications.

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Although small wind turbines arevery sturdy machines, they do requiresome annual maintenance. Bolts andelectrical connections should bechecked and tightened if necessary.The machines should be checked forcorrosion and the guy wires for proper tension. In addition, youshould check for and replace anyworn leading edge tape on the blades,if appropriate. After 10 years, theblades or bearings may need to bereplaced, but with proper installationand maintenance, the machine shouldlast up to 20 years or longer.

If you do not have the expertise tomaintain the machine, your installermay provide a service and mainte-nance program.

How Much Energy Will MySystem Generate?Most U.S. manufacturers rate theirturbines by the amount of power theycan safely produce at a particularwind speed, usually chosen between24 mph (10.5 m/s) and 36 mph(16 m/s). The following formula illustrates factors that are important to the performance of a wind turbine.Notice that the wind speed, V, has an

exponent of 3 applied to it. Thismeans that even a small increase inwind speed results in a large increasein power. That is why a taller towerwill increase the productivity of anywind turbine by giving it access tohigher wind speeds as shown in theWind Speeds Increase with Heightgraph. The formula for calculating the power from a wind turbine is:

Power = k Cp 1/2 ρ A V3

Where:

P = Power output, kilowatts

Cp = Maximum power coefficient, ranging from 0.25 to 0.45, dimension less (theoretical maximum = 0.59)

ρ = Air density, lb/ft3

A = Rotor swept area, ft2 or π D2/4 (D is the rotor diameter in ft, π = 3.1416)

V = Wind speed, mph

k = 0.000133 A constant to yield power in kilowatts. (Multiplyingthe above kilowatt answer by 1.340 converts it to horse-power. [i.e., 1 kW = 1.340 horsepower]).


8

7

6

5

4

3

2

1

0

1 2 3 4 5 6 7Rotor Diameter, m

Rot

or D

iam

eter

, m

Relative Size of Small Wind Turbines40

30

20

10

0

Sw

ept a

rea,

m2

7 m

6 m

5 m

4 m

3 m

2 m

1 m

0297

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m

Source: Paul Gipe, Wind Energy Basics

The rotor swept area, A, is importantbecause the rotor is the part of the turbine that captures the wind energy.So, the larger the rotor, the more energy it can capture. The air density,ρ, changes slightly with air tempera-ture and with elevation. The ratingsfor wind turbines are based on standard conditions of 59° F (15° C) at sea level. A density correctionshould be made for higher elevationsas shown in the Air Density Changewith Elevation graph. A correction fortemperature is typically not neededfor predicting the long-term perform-ance of a wind turbine.

While the calculation of wind powerillustrates important features aboutwind turbines, the best measure ofwind turbine performance is annualenergy output. The differencebetween power and energy is thatpower (kilowatts [kW]) is the rate atwhich electricity is consumed, whileenergy (kilowatt-hours [kWh]) is thequantity consumed. An estimate ofthe annual energy output from yourwind turbine, kWh/year, is the bestway to determine whether a particu-lar wind turbine and tower will pro-duce enough electricity to meet yourneeds.

A wind turbine manufacturer can helpyou estimate the energy productionyou can expect. They will use a calcu-lation based on the particular windturbine power curve, the averageannual wind speed at your site, theheight of the tower that you plan touse, and the frequency distribution ofthe wind–an estimate of the numberof hours that the wind will blow ateach speed during an average year.They should also adjust this calcula-tion for the elevation of your site.Contact a wind turbine manufactureror dealer for assistance with this calculation.

To get a preliminary estimate of theperformance of a particular wind tur-bine, use the formula below.

AEO = 0.01328 D2 V3

Where:

AEO = Annual energy output, kWh/year

D = Rotor diameter, feet

V = Annual average wind speed, mph

The Wind Energy Payback PeriodWorkbook found at http://www.nrel.gov/wind/ under consumer informa-tion is a spreadsheet tool that can helpyou analyze the economics of a smallwind electric system and decidewhether wind energy will work foryou. The spreadsheet can be openedusing Microsoft Excel 95 software. It asks you to provide informationabout how you're going to finance thesystem, the characteristics of your site, and the properties of the systemyou're considering. It then providesyou with a simple payback estimationin years. If it takes too long to regainyour capital investment—the numberof years comes too close or is greaterthan the life of the system—windenergy will not be practical for you.


and trees, and it needs to be 30 feetabove anything within 300 feet. Youalso need enough room to raise andlower the tower for maintenance, andif your tower is guyed, you mustallow room for the guy wires.

Whether the system is stand-alone or grid-connected, you will also needto take the length of the wire runbetween the turbine and the load(house, batteries, water pumps, etc.)into consideration. A substantialamount of electricity can be lost as aresult of the wire resistance—thelonger the wire run, the more electric-ity is lost. Using more or larger wirewill also increase your installationcost. Your wire run losses are greaterwhen you have direct current (DC)instead of alternating current (AC).So, if you have a long wire run, it isadvisable to invert DC to AC.

Can I Connect My Systemto the Utility Grid?Small wind energy systems can beconnected to the electricity distribu-tion system and are called grid-connected systems. A grid-connectedwind turbine can reduce your con-sumption of utility-supplied electrici-ty for lighting, appliances, and electric heat. If the turbine cannotdeliver the amount of energy you

need, the utility makes up the differ-ence. When the wind system producesmore electricity than the householdrequires, the excess is sent or sold tothe utility.

Grid-connected systems can be practi-cal if the following conditions exist:


• Utility-supplied electricity isexpensive in your area (about 10 to15 cents per kilowatt-hour).

• The utility's requirements forconnecting your system to its gridare not prohibitively expensive.

• There are good incentives for thesale of excess electricity or for thepurchase of wind turbines.

Federal regulations (specifically, thePublic Utility Regulatory Policies Actof 1978, or PURPA) require utilities to connect with and purchase powerfrom small wind energy systems.However, you should contact yourutility before connecting to their dis-tribution lines to address any powerquality and safety concerns. Your utility can provide you with a list ofrequirements for connecting your sys-tem to the grid. The American WindEnergy Association is another goodsource for information on utility

10,000

9,000

8,000

7,000

6,000

5,000

4,000

3,000

2,000

1,000

070 75 80 85 90 95 100

Density change compared to sea level, %

Ele

vatio

n, ft

Air Density Change with Elevation

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Is There Enough Wind on My Site?Does the wind blow hard and consis-tently enough at my site to make asmall wind turbine system economi-cally worthwhile? That is a key ques-tion and not always easily answered.The wind resource can vary signifi-cantly over an area of just a few milesbecause of local terrain influenceson the wind flow. Yet, there are stepsyou can take that will go a long waytowards answering the above question.

As a first step, wind resource mapslike the one on pages 12 and 13 canbe used to estimate the wind resourcein your region. The highest averagewind speeds in the United States aregenerally found along seacoasts, onridgelines, and on the Great Plains;however, many areas have windresources strong enough to power asmall wind turbine economically. Thewind resource estimates on this mapgenerally apply to terrain features thatare well exposed to the wind, such asplains, hilltops, and ridge crests. Localterrain features may cause the windresource at a specific site to differ con-siderably from these estimates. Moredetailed wind resource information,including the Wind Energy ResourceAtlas of United States, published by theU.S. Department of Energy (DOE),can be found at the National WindTechnology Center web site athttp://www.nrel.gov/wind/ and theDOE Windpowering America web site at http://www.eren.doe.gov/windpoweringamerica/.

Another way to indirectly quantifythe wind resource is to obtain averagewind speed information from a nearby airport. However, cautionshould be used because local terraininfluences and other factors maycause the wind speed recorded at an

airport to be different from your par-ticular location. Airport wind data aregenerally measured at heights about20–33 ft (6–10 m) above ground.Average wind speeds increase withheight and may be 15%–25% greaterat a typical wind turbine hub-heightof 80 ft (24 m) than those measured at airport anemometer heights. TheNational Climatic Data Center collectsdata from airports in the United Statesand makes wind data summariesavailable for purchase. Summaries ofwind data from almost 1000 U.S. air-ports are also included in the WindEnergy Resource Atlas of the UnitedStates (see For More Information).

Another useful indirect measurementof the wind resource is the observa-tion of an area’s vegetation. Trees,especially conifers or evergreens, canbe permanently deformed by strongwinds. This deformity, known as"flagging," has been used to estimatethe average wind speed for an area.For more information on the use of


Wind Speeds Increase with Height

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m150

120

90

60

30

00

Increase in wind power, %

Tow

er h

eigh

t, ft

41 75 100 124

Small Wind Electric Systems12 Small Wind Electric Systems 13

flagging you may want to obtain A Siting Handbook for Small WindEnergy Conversion Systems (see ForMore Information).

Direct monitoring by a wind resourcemeasurement system at a site pro-vides the clearest picture of the avail-able resource. A good overall guide on this subject is the Wind ResourceAssessment Handbook (see For MoreInformation). Wind measurement sys-tems are available for costs as low as$600 to $1200. This expense may ormay not be hard to justify dependingon the exact nature of the proposedsmall wind turbine system. The meas-urement equipment must be set highenough to avoid turbulence createdby trees, buildings, and other obstruc-tions. The most useful readings arethose taken at hub-height, the eleva-tion at the top of the tower where thewind turbine is going to be installed.If there is a small wind turbine systemin your area, you may be able toobtain information on the annual

output of the system and also windspeed data if available.

How Do I Choose the BestSite for My Wind Turbine?You can have varied wind resourceswithin the same property. In additionto measuring or finding out about theannual wind speeds, you need toknow about the prevailing directionsof the wind at your site. If you live incomplex terrain, take care in selectingthe installation site. If you site yourwind turbine on the top of or on thewindy side of a hill, for example, youwill have more access to prevailingwinds than in a gully or on the lee-ward (sheltered) side of a hill on thesame property. In addition to geologicformations, you need to considerexisting obstacles such as trees, houses, and sheds, and you need toplan for future obstructions such asnew buildings or trees that have notreached their full height. Your turbineneeds to be sited upwind of buildings


Is There Enough Wind on My Site?Does the wind blow hard and consis-tently enough at my site to make asmall wind turbine system economi-cally worthwhile? That is a key ques-tion and not always easily answered.The wind resource can vary signifi-cantly over an area of just a few milesbecause of local terrain influenceson the wind flow. Yet, there are stepsyou can take that will go a long waytowards answering the above question.

As a first step, wind resource mapslike the one on pages 12 and 13 canbe used to estimate the wind resourcein your region. The highest averagewind speeds in the United States aregenerally found along seacoasts, onridgelines, and on the Great Plains;however, many areas have windresources strong enough to power asmall wind turbine economically. Thewind resource estimates on this mapgenerally apply to terrain features thatare well exposed to the wind, such asplains, hilltops, and ridge crests. Localterrain features may cause the windresource at a specific site to differ con-siderably from these estimates. Moredetailed wind resource information,including the Wind Energy ResourceAtlas of United States, published by theU.S. Department of Energy (DOE),can be found at the National WindTechnology Center web site athttp://www.nrel.gov/wind/ and theDOE Windpowering America web site at http://www.eren.doe.gov/windpoweringamerica/.

Another way to indirectly quantifythe wind resource is to obtain averagewind speed information from a nearby airport. However, cautionshould be used because local terraininfluences and other factors maycause the wind speed recorded at an

airport to be different from your par-ticular location. Airport wind data aregenerally measured at heights about20–33 ft (6–10 m) above ground.Average wind speeds increase withheight and may be 15%–25% greaterat a typical wind turbine hub-heightof 80 ft (24 m) than those measured at airport anemometer heights. TheNational Climatic Data Center collectsdata from airports in the United Statesand makes wind data summariesavailable for purchase. Summaries ofwind data from almost 1000 U.S. air-ports are also included in the WindEnergy Resource Atlas of the UnitedStates (see For More Information).

Another useful indirect measurementof the wind resource is the observa-tion of an area’s vegetation. Trees,especially conifers or evergreens, canbe permanently deformed by strongwinds. This deformity, known as"flagging," has been used to estimatethe average wind speed for an area.For more information on the use of

0Nodeformity

Flagging

Prevailing wind

IBrushingand slightflagging

IISlightflagging

IIIModerateflagging

IVCompleteflagging

VPartialthrowing

VICompletethrowing

VIICarpeting

02979310m

Griggs-Putnam Index of DeformityIndex 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

Flagging, the effectof strong winds onarea vegetation,can help determinearea wind speeds.


and trees, and it needs to be 30 feetabove anything within 300 feet. Youalso need enough room to raise andlower the tower for maintenance, andif your tower is guyed, you mustallow room for the guy wires.

Whether the system is stand-alone or grid-connected, you will also needto take the length of the wire runbetween the turbine and the load(house, batteries, water pumps, etc.)into consideration. A substantialamount of electricity can be lost as aresult of the wire resistance—thelonger the wire run, the more electric-ity is lost. Using more or larger wirewill also increase your installationcost. Your wire run losses are greaterwhen you have direct current (DC)instead of alternating current (AC).So, if you have a long wire run, it isadvisable to invert DC to AC.

Can I Connect My Systemto the Utility Grid?Small wind energy systems can beconnected to the electricity distribu-tion system and are called grid-connected systems. A grid-connectedwind turbine can reduce your con-sumption of utility-supplied electrici-ty for lighting, appliances, and electric heat. If the turbine cannotdeliver the amount of energy you

need, the utility makes up the differ-ence. When the wind system producesmore electricity than the householdrequires, the excess is sent or sold tothe utility.

Grid-connected systems can be practi-cal if the following conditions exist:


• Utility-supplied electricity isexpensive in your area (about 10 to15 cents per kilowatt-hour).

• The utility's requirements forconnecting your system to its gridare not prohibitively expensive.

• There are good incentives for thesale of excess electricity or for thepurchase of wind turbines.

Federal regulations (specifically, thePublic Utility Regulatory Policies Actof 1978, or PURPA) require utilities to connect with and purchase powerfrom small wind energy systems.However, you should contact yourutility before connecting to their dis-tribution lines to address any powerquality and safety concerns. Your utility can provide you with a list ofrequirements for connecting your sys-tem to the grid. The American WindEnergy Association is another goodsource for information on utility


20 H2 H

Obstruction of the Wind by a Buildingor Tree of Height (H)

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H

2 H

Regionof highlyturbulent

flow

The farther youplace your windturbine fromobstacles suchas buildings ortrees, the lessturbulence youwill encounter.

interconnection requirements. The following information about utilitygrid connection requirements wastaken from AWEA's Web site. Formore detailed information, visithttp://www.awea.org/ or contactAWEA (see For More Information).

Net Metering

The concept of net metering programsis to allow the electric meters of cus-tomers with generating facilities toturn backwards when their generatorsare producing more energy than thecustomers’ demand. Net meteringallows customers to use their genera-tion to offset their consumption overthe entire billing period, not justinstantaneously. This offset wouldenable customers with generatingfacilities to receive retail prices formore of the electricity they generate.

Net metering varies by state and byutility company, depending onwhether net metering was legislatedor directed by the Public UtilityCommission. Net metering programsall specify a way to handle the netexcess generation (NEG) in terms ofpayment for electricity and/or lengthof time allowed for NEG credit. If thenet metering requirements defineNEG on a monthly basis, the con-sumer can only get credit for theirexcess that month. But if the netmetering rules allow for annual NEG,

the NEG credit can be carried for upto a year.

Most of North America gets morewind in the winter than in the sum-mer. For people using wind energy todisplace a large load in the summerlike air-conditioning or irrigationwater pumping, having an annualNEG credit allows them to produceNEG in the winter and be credited inthe summer.

Safety Requirements

Whether or not your wind turbine isconnected to the utility grid, theinstallation and operation of the windturbine is probably subject to the elec-trical codes that your local govern-ment (city or county) or in someinstances your state government hasin place. The government’s principalconcern is with the safety of the facility, so these code requirementsemphasize proper wiring and installa-tion, and the use of components that have been certified for fire andelectrical safety by approved testinglaboratories, such as UnderwritersLaboratories. Most local electricalcodes requirements are based on theNational Electrical Code (NEC),which is published by the NationalFire Protection Association. As of1999, the latest version of the NEC didnot have any sections specific to theinstallation of wind energy facilities,


Although small wind turbines arevery sturdy machines, they do requiresome annual maintenance. Bolts andelectrical connections should bechecked and tightened if necessary.The machines should be checked forcorrosion and the guy wires for proper tension. In addition, youshould check for and replace anyworn leading edge tape on the blades,if appropriate. After 10 years, theblades or bearings may need to bereplaced, but with proper installationand maintenance, the machine shouldlast up to 20 years or longer.

If you do not have the expertise tomaintain the machine, your installermay provide a service and mainte-nance program.

How Much Energy Will MySystem Generate?Most U.S. manufacturers rate theirturbines by the amount of power theycan safely produce at a particularwind speed, usually chosen between24 mph (10.5 m/s) and 36 mph(16 m/s). The following formula illustrates factors that are important to the performance of a wind turbine.Notice that the wind speed, V, has an

exponent of 3 applied to it. Thismeans that even a small increase inwind speed results in a large increasein power. That is why a taller towerwill increase the productivity of anywind turbine by giving it access tohigher wind speeds as shown in theWind Speeds Increase with Heightgraph. The formula for calculating the power from a wind turbine is:

Power = k Cp 1/2 ρ A V3

Where:

P = Power output, kilowatts

Cp = Maximum power coefficient, ranging from 0.25 to 0.45, dimension less (theoretical maximum = 0.59)

ρ = Air density, lb/ft3

A = Rotor swept area, ft2 or π D2/4 (D is the rotor diameter in ft, π = 3.1416)

V = Wind speed, mph

k = 0.000133 A constant to yield power in kilowatts. (Multiplyingthe above kilowatt answer by 1.340 converts it to horse-power. [i.e., 1 kW = 1.340 horsepower]).

Inverter

Load

AC

Windturbine

Grid-connected Systems

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Meter

A grid-connectedwind turbine canreduce yourconsumption ofutility-suppliedelectricity.


consequently wind energy installa-tions are governed by the generic provisions of the NEC.

If your wind turbine is connected tothe local utility grid so that any of thepower produced by your wind tur-bine is delivered to the grid, then yourutility also has legitimate concernsabout safety and power quality thatneed to be addressed. The utility’sprincipal concern is that your windturbine automatically stops deliveringany electricity to its power lines dur-ing a power outage. Otherwise lineworkers and the public, thinking thatthe line is "dead," might not take nor-mal precautions and might be hurt oreven killed by the power from yourturbine. Another concern among utili-ties is that the power from your facili-ty synchronize properly with theutility grid, and that it match the util-ity’s own power in terms of voltage,frequency, and power quality.

A few years ago, some state govern-ments started developing new standardized interconnection require-ments for small renewable energygenerating facilities (including windturbines). In most cases the newrequirements have been based on con-sensus-based standards and testingprocedures developed by independ-ent third-party authorities, such as theInstitute of Electrical and ElectronicEngineers and UnderwritersLaboratories.

Interconnection Requirements

Most utilities and other electricityproviders require you to enter into aformal agreement with them beforeyou interconnect your wind turbinewith the utility grid. In states thathave retail competition for electricityservice (e.g., your utility operates the local wires, but you have a choice of electricity provider) you may have to sign a separate

agreement with each company.Usually these agreements are writtenby the utility or the electricityprovider. In the case of private(investor-owned) utilities, the termsand conditions in these agreementsmust be reviewed and approved bystate regulatory authorities.

Insurance

Some utilities require small windturbine owners to maintain liabilityinsurance in amounts of $1 million ormore. Utilities consider these require-ments are necessary to protect themfrom liability for facilities they do notown and have no control over. Othersconsider the insurance requirementsexcessive and unduly burdensome,making wind energy uneconomic. Inthe 21 years since utilities have beenrequired to allow small wind systemsto interconnect with the grid there has never been a liability claim, letalone a monetary award, relating toelectrical safety.


This grid-connected,10 kW Bergeywind turbineoffsets electricalpowerconsumption fora small businessin Norman,Oklahoma.

Berg

ey W

indp

ower

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In six states (California, Maryland,Nevada, Oklahoma, Oregon, andWashington), laws or regulatoryauthorities prohibit utilities fromimposing any insurance requirementson small wind systems that qualify for"net metering." In at least three otherstates (Idaho, New York, Virginia) reg-ulatory authorities have allowed utili-ties to impose insurance requirements,but have reduced the required cover-age amounts to levels consistent withconventional residential or commer-cial insurance policies (e.g., $100,000to $300,000). If your insuranceamounts seem excessive, you can askfor a reconsideration from regulatoryauthorities (in the case of privateinvestor-owned utilities) or to the utility’s governing board (in the caseof publicly-owned utilities).

Indemnification

An indemnity is an agreementbetween two parties where one agreesto secure the other against loss ordamage arising from some act orsome assumed responsibility. In the context of customer-owned

generating facilities, utilities oftenwant customers to indemnify themfor any potential liability arising fromthe operation of the customer’s generat-ing facility. Although the basic princi-ple is sound—utilities should not beheld responsible for property damageor personal injury attributable tosomeone else—indemnity provisionsshould not favor the utility but shouldbe fair to both parties. Look for lan-guage that says, "each party shallindemnify the other . . ." rather than"the customer shall indemnify the utility . . ."

Customer Charges

Customer charges can take a varietyof forms, including interconnectioncharges, metering charges, and standby charges, among others. Youshould not hesitate to question anycharges that seem inappropriate toyou. Federal law (Public UtilityRegulatory Policies Act of 1978, orPURPA, Section 210) prohibits utilitiesfrom assessing discriminatory chargesto customers who have their own generation facilities.


Small wind turbines generate directcurrent (DC) electricity. In very smallsystems, DC appliances operatedirectly off the batteries. If you wantto use standard appliances that useconventional household alternatingcurrent (AC), you must install aninverter to convert DC electricityfrom the batteries to AC. Althoughthe inverter slightly lowers the overall efficiency of the system, itallows the home to be wired for AC,a definite plus with lenders, electri-cal code officials, and future homebuyers.

For safety, batteries should be iso-lated from living areas and electron-ics because they contain corrosiveand explosive substances. Lead-acidbatteries also require protection fromtemperature extremes.

Grid-Connected Systems

In grid-connected systems, the onlyadditional equipment required is apower conditioning unit (inverter)that makes the turbine output electri-cally compatible with the utility grid.Usually, batteries are not needed.

What Do Wind SystemsCost?A small turbine can cost anywherefrom $3,000 to $35,000 installed,depending on size, application, andservice agreements with the manufac-turer. (The American Wind EnergyAssociation [AWEA] says a typicalhome wind system costs approxi-mately $32,000 (10 kW); a comparablephotovoltaic [PV] solar system wouldcost over $80,000.)

A general rule of thumb for estimatingthe cost of a residential turbine is$1,000 to $3,000 per kilowatt. Windenergy becomes more cost effective as the size of the turbine’s rotorincreases. Although small turbinescost less in initial outlay, they are

proportionally more expensive. Thecost of an installed residential windenergy system that comes with an 80-foot tower, batteries, and inverter,typically ranges from $13,000 to$40,000 for a 3 to 10 kW wind turbine.

Although wind energy systemsinvolve a significant initial invest-ment, they can be competitive withconventional energy sources whenyou account for a lifetime of reducedor avoided utility costs. The length ofthe payback period—the time beforethe savings resulting from your sys-tem equal the cost of the systemitself—depends on the system youchoose, the wind resource on yoursite, electricity costs in your area, andhow you use your wind system. Forexample, if you live in California andhave received the 50% buydown ofyour small wind system, have netmetering, and an average annualwind speed of 15 miles per hour(mph) (6.7 meters per second [m/s]),your simple payback would beapproximately 6 years.

Connecting to the Utility Grid—A Success Story

This 10-kW Bergey wind turbine, installed on afarm located in Southwestern Kansas in 1983,produces an average 1700–1800 kilowatt-hoursper month, reducing the user's monthly utilitybills by approximately 50%. The turbine costabout $20,000 when it was installed. Since then,the cost for operation and maintenance has beenabout $50 per year. The only unscheduled main-tenance activity over the years was repair to theturbine required as a result of damage caused bya lightning strike. Insurance covered all but $500of the $9000 cost of damages. The basic systemparts include:

Bergey XL.10 wind turbine100-foot free-standing lattice towerInverter

War

ren

Gre

tz, N

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Can I Go "Off-Grid"?Hybrid Systems

Hybrid wind energy systems can provide reliable off-grid power forhomes, farms or even entire com-munities (a co-housing project, for example) that are far from the nearestutility lines. According to manyrenewable energy experts, a "hybrid"system that combines wind and photovoltaic (PV) technologies offersseveral advantages over either singlesystem. In much of the United States,wind speeds are low in the summerwhen the sun shines brightest andlongest. The wind is strong in thewinter when there is less sunlightavailable. Because the peak operatingtimes for wind and PV occur at differ-ent times of the day and year, hybridsystems are more likely to producepower when you need it. (For moreinformation on solar electric or PV systems, contact the EnergyEfficiency and Renewable EnergyClearinghouse—see For MoreInformation.)

For the times when neither the windnor the PV modules are producing,most hybrid systems provide powerthrough batteries and/or an engine-generator powered by conventionalfuels such as diesel. If the batteriesrun low, the engine-generator can provide power and recharge the bat-teries. Adding an engine-generatormakes the system more complex, butmodern electronic controllers canoperate these systems automatically.An engine-generator can also reducethe size of the other componentsneeded for the system. Keep in mindthat the storage capacity must be large enough to supply electricalneeds during non-charging periods.Battery banks are typically sized tosupply the electric load for one tothree days.

An off-grid hybrid system may bepractical for you if:


• A grid connection is not availableor can only be made through an


Regulation andconversion

Load

Battery bank

AC or DC

Windturbine

PV modules

Generator

Hybrid Power SystemsCombine multiple sources to deliver non-intermittent electric power

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A hybrid systemthat combines awind system with asolar and/or dieselgenerator canprovide reliable off-grid power aroundthe clock.

expensive extension. The cost ofrunning a power line to a remotesite to connect with the utility gridcan be prohibitive, ranging from$15,000 to more than $50,000 permile, depending on terrain.

• You would like to gain energyindependence from the utility.

• You would like to generate cleanpower.


What are the Basic Parts of a Small Wind ElectricSystem?Home wind energy systems gener-ally comprise a rotor, a generator oralternator mounted on a frame, a tail (usually), a tower, wiring, and the"balance of system" components: controllers, inverters, and/or batter-ies. Through the spinning blades, therotor captures the kinetic energy ofthe wind and converts it into rotarymotion to drive the generator.

Wind Turbine

Most turbines manufactured todayare horizontal axis upwind machinesthat have two or three blades, whichare usually made of a composite mate-rial such as fiberglass.

The amount of power a turbine willproduce is determined primarily bythe diameter of its rotor. The diameterof the rotor defines its "swept area," orthe quantity of wind intercepted bythe turbine. The turbine's frame is thestructure onto which the rotor, genera-tor, and tail are attached. The tailkeeps the turbine facing into thewind.

Tower

Because wind speeds increase withheight, the turbine is mounted on a tower. In general, the higher thetower, the more power the wind system can produce. The tower alsoraises the turbine above the air turbulence that can exist close to the ground because of obstructionssuch as hills, buildings, and trees. Ageneral rule of thumb is to install awind turbine on a tower with thebottom of the rotor blades at least30 feet (9 meters) above any obstaclethat is within 300 feet (90 meters) ofthe tower. Relatively small invest-ments in increased tower height canyield very high rates of return in

power production. For instance, toraise a 10-kW generator from a 60-foottower height to a 100-foot towerinvolves a 10% increase in overall system cost, but it can produce 25%more power.

There are two basic types of towers:self-supporting (free standing) andguyed. Most home wind power sys-tems use a guyed tower. Guyed tow-ers, which are the least expensive, canconsist of lattice sections, pipe, or tub-ing depending on the design, andsupporting guy wires. They are easierto install than self-supporting towers.However, because the guy radiusmust be one-half to three-quarters of the tower height, guyed towersrequire enough space to accommodatethem. While tilt-down towers aremore expensive they offer the con-sumer an easy way to perform

Living Off-Grid—A Success Story

This home, built near in Ward, Colorado (at an elevation of 9000 feet), hasbeen off-grid since it was built in 1972. When the house was built, the near-est utility 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 poweredby wind, solar, and a generator for a costof about $19,700. The parts of the systeminclude:

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 kWrated (3 kW derated for altitude)

Electric appliances in the home includetelevision, stereo, two computers, toaster,blender, vacuum cleaner, and hair dryer.The largest electric loads are created by a well pump and washing machine. Thegenerator runs about 20% of the time,particularly when the washing machine is in use. Propane serves the other majorloads in the home: range, refrigerator, hotwater, and space heat. Solar collectors onthe roof provide pre-heating for the hotwater.

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Glossary of TermsAirfoil—The shape of the blade cross-section, which for most modern hori-zontal axis wind turbines, is designedto enhance the lift and improve tur-bine performance.

Ampere-hour—A unit of for the quan-tity of electricity obtained by integrat-ing current flow in amperes over thetime in hours for its flow; used as ameasure of battery capacity.

Anemometer—A device to measurethe wind speed.

Average wind speed—The mean windspeed over a specified period of time.

Blades—The aerodynamic surfacethat catches the wind.

Brake—Various systems used to stopthe rotor from turning.

Converter—See Inverter.

Cut-in wind speed—The wind speedat which a wind turbine begins togenerate electricity.

Cut-out wind speed—The wind speedat which a wind turbine ceases to generate electricity.

Density—Mass per unit of volume.

Downwind—On the opposite sidefrom the direction from which thewind is blowing.

Furling—A passive protection for theturbine where typically the rotor foldseither up or around the tail vane.

Grid—The utility distribution system. The network that connects electricitygenerators to electricity users.

HAWT—Horizontal axis wind turbine.

Inverter—A device that converts directcurrent (DC) to alternating current(AC).

kW—Kilowatt, a measure of powerfor electrical current (1000 watts).

kWh—Kilowatt-hour, a measure of energy equal to the use of one kilowatt in one hour.

MW—Megawatt, a measure of power(1,000,000 watts).

Nacelle—The body of a propeller-typewind turbine, containing the gearbox,generator, blade hub, and other parts.

O&M Costs—Operation and mainte-nance costs.

Power Coefficient—The ratio of thepower extracted by a wind turbine to the power available in the windstream.

Power curve—A chart showing awind turbine's power output across a range of wind speeds.

PUC—Public Utility Commission, astate agency which regulates utilities.In some areas known as Public ServiceCommission (PSC).

PURPA—Public Utility RegulatoryPolicies Act (1978), 16 U.S.C. § 2601.18CFR §292 that refers to small generator utility connection rules.

Rated output capacity—The outputpower of a wind machine operating at the rated wind speed.

Rated wind speed—The lowest windspeed at which the rated outputpower of a wind turbine is produced.

Rotor—The rotating part of a windturbine, including either the bladesand blade assembly or the rotatingportion of a generator.

Rotor diameter—The diameter of thecircle swept by the rotor.

Rotor speed—The revolutions perminute of the wind turbine rotor.

Start-up wind speed—The wind speedat which a wind turbine rotor willbegin to spin. See also cut-in windspeed.


This 1 kW Whisperturbine providesdirect AC power forthe water pump forstock tanks on aranch in Wheeler,Texas.

Swept area—The area swept by theturbine rotor, A = πR2, where R is theradius of the rotor.

Tip speed ratio—The speed at the tipof the rotor blade as it moves throughthe air divided by the wind velocity.This is typically a design requirementfor the turbine.

Turbulence—The changes in windspeed and direction, frequentlycaused by obstacles.

Upwind—On the same side as thedirection from which the wind isblowing—windward.

VAWT—Vertical axis wind turbine.

Wind farm—A group of wind tur-bines, often owned and maintained byone company. Also known as a windpower plant.

Yaw—The movement of the tower topturbine that allows the turbine to stayinto the wind.

For More InformationBooks

A Siting Handbook for Small WindEnergy Conversion Systems. H. Wegley,J. Ramsdell, M. Orgill and R. Drake,Report No. PNL-2521 Rev.1, 1980;available from National TechnicalInformation Service, 5285 Port RoyalRd., Springfield, VA 22151. (800) 553-6847. http://www.ntis.gov/ordering.htm

Energy Savers Tips on Saving Energyand Money at Home—A consumer'sguide for saving energy and reducingutility bills. Available from U.S.Department of Energy's EnergyEfficiency and Renewable EnergyClearinghouse (EREC), P.O. Box 3048,Merrifield, Virginia 22116. (800) 363-3732. http://www.eren.doe.gov/consumerinfo/energy_savers.

Wind Energy Basics by Paul Gipe—Acomprehensive guide to modern small

wind technology. Available throughAWEA. (202) 383-2500. http://www.awea.org and Chelsea GreenPublishing Company, White RiverJunction, Vermont. 1999. ISBN 1-890132-07-01. http://www.chelseagreen.com

Wind Energy Resource Atlas of theUnited States by D. Elliott et al.Available from the American WindEnergy Association, 122 C. StreetN.W., Washington D.C. 20001.http://rredc.nrel.gov/wind/pubs/atlas

Wind Power for Home and Business byPaul Gipe—A comprehensive guide to modern small wind technology.Available through AWEA. (202) 383-2500. http://www.awea.org andChelsea Green Publishing Company,White River Junction, Vermont. 1999.ISBN - 0-930031-64-4. http://www.chelseagreen.com

Wind Power Workshop by HughPiggott—Provides an overview onhow to design a home-built wind tur-bine. Available from The Center forAlternative Technology, Machynlleth,Powys, SY20 9AZ, UK Phone: 06154-702400, FAX: 01654 702782. E-mail:[email protected],http://www.foe.co.uk/CAT

Wind Resource Assessment Handbook:Fundamentals for Conducting aSuccessful Monitoring Program—Thishandbook presents industry-acceptedguidelines for planning and conduct-ing a wind resource measurementprogram. These guidelines, which aredetailed and highly technical, empha-size the tasks of selecting, installing,and operating wind measurementequipment, as well as collecting andanalyzing the associated data.Prepared by AWS Scientific, Inc.Available electronically in NREL'spublication database at http://www.nrel.gov/publications.


Is Wind Energy Practicalfor Me?A small wind energy system can provide you with a practical and economical source of electricity if:

• your property has a good windresource

• your home or business is located onat least one acre of land in a ruralarea

• your local zoning codes orcovenants allow wind turbines

• your average electricity bills are$150 per month or more

• your property is in a remotelocation that does not have easyaccess to utility lines

• you are comfortable with long-terminvestments.

Zoning Issues

Before you invest in a wind energysystem, you should research potentialobstacles. Some jurisdictions, forexample, restrict the height of the

structures permitted in residentiallyzoned areas, although variances areoften obtainable. Most zoning ordi-nances have a height limit of 35 feet.You can find out about the zoningrestrictions in your area by calling the local building inspector, board ofsupervisors, or planning board. Theycan tell you if you will need to obtaina building permit and provide youwith a list of requirements.

In addition to zoning issues, yourneighbors might object to a windmachine that blocks their view, orthey might be concerned about noise.Most zoning and aesthetic concernscan be addressed by supplying objec-tive data. For example, the ambientnoise level of most modern residentialwind turbines is around 52 to 55 deci-bels. This means that while the soundof the wind turbine can be picked outof surrounding noise if a consciouseffort is made to hear it, a residential-sized wind turbine is no noisier thanyour average refrigerator.


Government Agencies

Energy Efficiency and RenewableEnergy Clearinghouse, P.O. Box 3048,Merrifield, Virginia 22116 800-DOE-EREC (363-3732). http://www.eren.doe.gov

National Climatic Data Center,Federal Building, 151 Patton Avenue,Asheville, North Carolina, 28801-5001.(828) 271-4800. Fax (828) 271-4876.http://www.ncdc.noaa.gov

U.S. Department of Commerce,National Technical InformationService, 5285 Port Royal Road,Springfield, Virginia 22161. (800) 553-6847. http://www.ntis.gov/ordering.htm

Non-Government Organizations

American Wind Energy Association,122 C Street, N.W. 4th Floor,Washington, D.C. 20001. (202) 383-2500. http://www.awea.org

Solar Energy International—Shortcourses on renewable energy and sustainable development, inCarbondale, Colorado. (970) 963-8855.http://www.solarenergy.org

Periodicals

"Apples and Oranges" by MickSagrillo—A comprehensive compari-son of available small wind turbines.On Home Power Magazine Web site:http://www.homepower.com

Home Power Magazine—The defini-tive bimonthly magazine for thehomemade power enthusiast.(800)707-6586 or on the Web at:http://www.homepower.com

Videos

An Introduction to Residential WindSystems with Mick Sagrillo—A 63-minute video answering questionsmost often asked by homeowners as they consider purchasing andinstalling their own wind power

systems. Order from AWEA (202) 383-2500, http://www.awea.org

Web Sites

AWEA Small Wind Systems Website—Includes answers to frequentlyasked questions and information onU.S. manufacturers. http://www.awea.org/smallwind.html

Database of State Incentives forRenewable Energy—On the Web athttp://www.dcs.ncsu.edu/solar/dsire/dsire.html

Green Power Network Net MeteringWeb Site—Net metering programs arenow available in 30 states. Visit thisDOE Web site for information:http://www.eren.doe.gov/greenpower/netmetering

Small Wind "Talk" on the Web—AWEA's Home Energy Systems elec-tronic mailing list is designed as aforum for the discussion of small-scaleenergy systems that include wind. Tosubscribe, send a subscription [email protected].

Wind Energy for Homeowners—ThisWeb site discusses things you shouldconsider before investing in a smallwind energy system and providesbasic information about the systems.http://www.eren.doe.gov/wind/homeowner.html



IntroductionCan I use wind energy to power myhome? This question is being askedacross the country as more peoplelook for affordable and reliablesources of electricity.

Small wind electric systems canmake a significant contribution toour nation's energy needs. Althoughwind turbines large enough to pro-vide a significant portion of the elec-tricity needed by the average U.S.home generally require one acre ofproperty or more, approximately21 million U.S. homes are built onone-acre and larger sites, and 24% of the U.S. population lives in ruralareas.

A small wind electric system willwork for you if:

• There is enough wind where youlive

• Tall towers are allowed in yourneighborhood or rural area

• You have enough space

• You can determine how muchelectricity you need or want toproduce

• It works for you economically.

The purpose of this guide is to pro-vide you with the basic informationabout small wind electric systems tohelp you decide if wind energy willwork for you.

Why Should I Choose Wind?

Wind energy systems are one of themost cost-effective home-basedrenewable energy systems.

Homeowners, ranchers, and small businesses can use wind-generated electricity to reduce their utility bills. This grid-connected system installed for a home in Norman, Oklahoma,reduces the homeowner's utility bill by $100 per month.

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2002 Farm Bill — WindEnergy DevelopmentProvisionsRenewable Energy Systems andEnergy Efficiency ImprovementsIncentive Type: Low-interest loans, loan

guarantees, and grantsEligible Technologies: Renewable energy

systems (energy derived from wind,solar, biomass, geothermal, and hydro-gen derived from biomass or waterusing a renewable energy source) andenergy efficiency improvements.

Applicable Sectors: Agriculture, ruralsmall commercial

Amount: Varies. The grant may not exceed25% of the cost of a project, and a com-bined grant and loan or guarantee maynot exceed 50% of the cost of a project.

Terms: 2003 – 2007Date Enacted: 2002Authority: Farm Bill, Title IX, Section 9006Summary: This law allows direct financial assistance to farmers, ranchers, and ruralsmall businesses for the purchase of windpower and other renewable energy sys-tems and for energy efficiency improve-ments. This program is funded at$23,000,000 each year in 2003-2007, totaling$115 million. In determining the amount ofa grant or loan, USDA shall consider thetype of renewable energy system, thequantity of energy likely to be generated,the expected environmental benefits, theextent to which the system is replicable,and the amount of energy savings fromenergy efficiency improvements and thelikely payback period.

Conservation Reserve ProgramIncentive Type: CRP paymentsEligible Technologies: Wind turbinesApplicable Sectors: AgricultureAmount: No reduction in CRP payments

when a wind turbine is installed onCRP land (subject to USDA approval)

Effective Date: 2002Authority 1: Farm Bill, Titles II and VI,

Section 2101Authority 2: Section 1232(a)(7) of the Food

Security Act of 1985, 16 U.S.C. § 3831,et seq.

Summary: Wind turbine installations arenow allowed on Conservation ReserveProgram lands with no reduction in CRPpayments. However, the wind turbine installations are subject to USDA approval,

taking into account the site location, habitat, and the purpose of the CRP.

Value-Added Agricultural ProductMarket Development GrantsIncentive Type: GrantsEligible Technologies: Renewable energy

systems (energy derived from wind,solar, geothermal, hydrogen, and biomass—biomass is specificallydefined and excludes both paper that is commonly recycled and unsegregat-ed solid wastes).

Applicable Sectors: AgricultureAmount: Maximum grant amount is

$500,000 per projectTerms: 2002 – 2007Authority 1: Farm Bill, Titles II and VI,

section 6401Authority 2: Section 231 of the Agricultural

Risk Protection Act of 2000, 7 U.S.C. §1621 note.

Summary: Titles II and VI, section 6401 of the Farm Bill amends Section 231 of the Agricultural Risk Protection Act of2000, 7 U.S.C. § 1621 note to expand thedefinition of the term “value-added agricultural product” to include farm- andranch-based renewable energy. The pro-gram provides for competitive grants toassist producers of value-added agricultur-al products, including renewable energysystems, to develop feasibility studies, business plans, and marketing strategies.Recipients also can use the grant to pro-vide capital to establish alliances or busi-ness ventures.

The maximum grant amount is $500,000per project. The program is funded at$40,000,000 for each year in 2002-2007, to be made available from the CommodityCredit Corporation, totaling $240 million.

ContactsWilliam F. Hagy IIIDeputy Administrator, Business ProgramsPhone: 202-720-7287E-mail: [email protected]

Chris HumesPhone: 202-720-0813E-mail: [email protected] Business-Cooperative Service1400 Independence Ave., S.W.Washington, D.C. 20250-3220

Small Wind Electric Systems

Clean Energy ProgramThe program offers rebates for commercial and residential wind projects installed on the user’s sideof the meter and sized within 125% of customeruse. Rebates are scaled down as system sizeincreases and as the total number of installed systems increases. Currently the state’s utilitiesadminister the program. For all application materi-als, complete funding schedule, and current incen-tive levels, see the NJ Clean Energy Program Web site http://www.njcleanenergy.com/html/3renewable/1_home.html

The state incentive is available as a result of 1999deregulation legislation that requires a "societalbenefits charge" be collected from all electric publicutility customers and a portion of these funds beprovided to support investments in energy efficiency and renewable energy.

Solar and Wind Energy SystemsExemptionTaxpayers are eligible for a sales tax exemptionfrom the state’s 6% sales tax for all solar and windinstallations. Such equipment must conform to NewJersey's technical sufficiency standards, regulationsthat establish the criteria for eligibility. The exemp-tion continues to be in effect, but regulations defining eligible systems expired in 2000. New reg-ulations are expected to be promulgated in 2003.

Net MeteringUtility customers that install wind systems up to100 kW are eligible for net metering. They receivecredit on their bills for electric generation thatexceeds their use. At the end of each year, their utility will purchase any unused credit at the utility’savoided cost. The program has an upper limit of0.1% of peak demand or $2,000,000 annual financial impact.

Features of the June 6, 2001 ruling include:

• systems up to 100 kW serving residential orsmall commercial customers are eligible for netmetering

• customers are not required to have additionalliability insurance

• customer can be charged a $100 fee forprocessing of application

• excess monthly kWhs are rolled over until theend of the annualized period and thenpurchased by the utility at the utility’s avoidedcost.

Contact:Cameron Johnson New Jersey Board of Public Utilities Division of Energy P.O. Box 350 Trenton, NJ 08625-0350 Phone: (609) 777-3316 Fax: (609) 777-3330 E-Mail: [email protected] Web site: http://www.bpu.state.nj.us Authority 1: N.J.S.A 54:32B-8.33 and regulations:N.J.A.C. 14:25-1

Renewable Energy Grid SupplyProgramThe NJ Board of Public Utilities offers a Grid SupplyProgram presently funded at $11 million dollars a year. In January 2002, the Board released arequest for proposals (RFP) to supply electricitygenerated by renewable energy systems to thePJM grid. Three wind projects were accepted forfunding.

The grid supply program is funded under 1999deregulation legislation that requires a "societalbenefits charge" be collected from all electric publicutility customers and a portion of these funds beprovided to support investments in energy effi-ciency and renewable energy.Contact:Victor Bozzo New Jersey Board of Public Utilities Division of Energy 2 Gateway Center Newark, NJ 07102 Phone: (973) 648-2891 Fax: (973) 648-2467 E-Mail: [email protected] Web site: http://www.bpu.state.nj.us Authority: N.J.S.A. 48:3-49 et seq.Joe CarpenterNJ Department of Environmental ProtectionOffice of Innovative Technology and MarketDevelopmentPO Box 409Trenton, NJ 08625-0409609-984-5418609-292-7340 (fax)[email protected]

ContactsMaryanne Daniel Philadelphia Regional OfficeThe Wanamaker Building100 Penn Square East, Suite 890Philadelphia, PA 19107-3396Phone: 215-656-6964Email: [email protected]: www.eren.doe.gov/pro

Wind Powering Americawww.windpoweringamerica.gov

Produced for the U.S. Department of Energy by the National Renewable Energy Laboratory, a DOE national laboratory

DOE/GO-102003-1682June 2003

Printed with a renewable-source ink on paper containing at least 50% wastepaper, including 20% postconsumer waste

U.S. Department of EnergyEnergy Efficiency and Renewable EnergyWind and Hydropower Technologies Program

A Strong Energy Portfolio for a Strong America

Energy efficiency and clean, renewable energy will mean a stronger economy, acleaner environment, and greater energy independence for America. Working with awide array of state, community, industry, and university partners, the U.S. Departmentof Energy’s Office of Energy Efficiency and Renewable Energy Invests in a diverseportfolio of energy technologies.

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