Small Wind Electric Systems

Home , Nacelle (wind turbine), National Wind, Southwest Windpower, Wind Powering America

Average Annual 0.1% Wind Speeds 5.8% 5.8% 60 meters

41.1% 47.2%

Miles per Hour (MPH) 7 - 10 10 - 12 12 - 13 13 - 14 14 - 15 15 - 16 16 - 17 17 - 18

Average annual wind speeds depicted in these maps were calculated in February 2003 using WindMap software. The State of Wisconsin Division of Energy developed this map. Many factors help determine the wind resource in Wisconsin. Major factors include elevation, land cover, wind speed, and wind direction. Wind data can come from a number of sources. Currently, the main source for wind data is tall tower data in Wisconsin collected through the Wisconsin Wind Resource Assessment Program. Other sources include tall tower data from Minnesota and data from navigation structures on Lake Superior and Lake Michigan. Use this map as a guide or reference. Site assessment is always necessary for identifying sites with good wind resources. For more information regarding wind power, please visit www.focusonenergy.com or www.doa.state.wi.us. Copies of this map can be obtained through the Focus on Energy or Department of Administration Web site.

Cover photo: Wisconsin residents take advantage of their wind resource to generate power for homes and businesses. Top row, left to right: PIX12968 — 3.5-kW Jacobs wind turbine; PIX12967 — 14-foot Jacobs (remanufactured) on 100-foot freestanding tower; PIX12970 — African Wind Power 3.5-meter wind turbine. Bottom row, left to right: PIX12966 — Bergey Excel wind turbine on a 122' guyed tower; PIX12969 — Southwest Windpower Whisper H40 wind turbine; PIX13054 — Proven WT6000 wind turbine (first U.S. installation) on a 12-ft. tower. Small Wind Electric Systems 1 Small Wind Electric Systems AU.S. Consumer's Guide

Introduction 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 sources 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 generally require one acre of property or more, approximately 6 7

21 million U.S. homes are built on 4 1 0 X one-acre and larger sites, and 24% I P / r e

of the U.S. population lives in rural w o p d areas. n i W

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

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

energy in wind into mechanical 02979309m power that runs a generator to produce clean electricity. Today's Refrigerator 9% turbines are versatile modular sources The largest portion of a utility bill for a typical of electricity. Their blades are aerody- house is for heating and cooling. namically designed to capture the proper insulation and maximum energy from the wind. The weatherization products. wind turns the blades, which spin a • Save money and increase comfort shaft connected to a generator that by properly maintaining and makes electricity. upgrading your heating, ventilation, and air-conditioning First, How Can I Make systems. My Home More Energy • Install double-paned, gas-filled Efficient? windows with low-emissivity (low-e) coatings to reduce heat Before choosing a wind system for loss in cold climates and spectrally your home, you should consider selective coatings to reduce heat reducing your energy consumption by gain in warm climates. making your home or business more energy efficient. Reducing your • Replace your lights in high-use energy consumption will significantly areas with fluorescents. Replacing lower your utility bills and will 25% of your lights can save about reduce the size of the home-based 50% of your lighting energy bill. renewable energy system you need. • When shopping for appliances, To achieve maximum energy effi- look for the E ciency, you should take a whole- building approach. View your home as an energy system with interrelated NERGYSTAR® label. parts, all of which work synergisti- ENERGYSTAR® appliances have cally to contribute to the efficiency of been identified by the U.S. the system. From the insulation in Environmental Protection Agency your home's walls to the light bulbs in and U.S. Department of Energy its fixtures, there are many ways you as being the most energy-efficient can make your home more efficient. products in their classes. • Reduce your heating and cooling • For more information on how to needs by up to 30% by investing make your home energy efficient, just a few hundred dollars in see Energy Savers, in the For More Information section. Small Wind Electric Systems 3

Is Wind Energy Practical structures permitted in residentially for Me? zoned areas, although variances are Asmall 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 that does not have easy tive data. For example, the ambient access to 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 potential sized wind turbine is no noisier than 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. orld Power Technology/PIX07168 W 4 Small Wind Electric Systems Turbines used in residential applica- Small Wind Electric Systems 21 tions can range in size from 400 watts to 100 kW (100 kW for very large kWh—Kilowatt-hour, a measure What Size Wind Turbine loads), depending on the amount of Glossary of Terms Do I Need? electricity you want to generate. For Airfoil—The shape of the blade cross- of energy equal to the use of one kilowatt in one hour. The size of the wind turbine you needresidential applications, you should section, which for most modern hori- depends on your application. Small establish an energy budget to help zontal axis wind turbines, is designedMW—Megawatt, a measure of power turbines range in size from 20 watts todefine the size of turbine you will to enhance the lift and improve tur- (1,000,000 watts). 100 kilowatts. The smaller or "micro" need. Because energy efficiency is bine performance. (20–500-watt) turbines are used in a usually less expensive than energy Nacelle—The body of a propeller-type variety of applications such as charg- production, making your house more Ampere-hour—A unit of for the quan- wind turbine, containing the gearbox, ing batteries for recreational vehicles energy efficient first will probably be tity of electricity obtained by integrat-generator, blade hub, and other parts. and sailboats. more cost effective and will reduce ing current flow in amperes over the O&M Costs—Operation and mainte- the size of the wind turbine you need time in hours for its flow; used as a One- to 10-kW turbines can be used in (see How Can I Make My Home measure of battery capacity. nance costs. applications such as pumping water. More Energy Efficient?). Wind turbine Wind energy has been used for cen- Power Coefficient—The ratio of the manufacturers can help you size your Anemometer—A device to measure turies to pump water and grind grain. power extracted by a wind turbine system based on your electricity the wind speed. Although mechanical windmills still to the power available in the wind needs and the specifics of local wind provide a sensible, low-cost option for Average wind speed—The mean wind stream. patterns. pumping water in low-wind areas, speed over a specified period of time. Power curve—A chart showing a farmers and ranchers are finding that Atypical home uses approximately Blades—The aerodynamic surface wind turbine's power output across wind-electric pumping is a little more9400 kilowatt-hours (kWh) of electric- that catches the wind. a range of wind speeds. versatile and they can pump twice ity per year (about 780 kWh per the volume for the same initial month). Depending on the average Brake—Various systems used to stop PUC—Public Utility Commission, a investment. In addition, mechanical wind speed in the area, a wind tur- the rotor from turning. state agency which regulates utilities. windmills must be placed directly bine rated in the range of 5 to 15 kilo- In some areas known as Public Service watts (kW) would be required to Converter—See Inverter. above the well, which may not take Commission (PSC). the best advantage of available wind make a significant contribution to this Cut-in wind speed—The wind speed resources. Wind-electric pumping demand. A 1.5- kW wind turbine will at which a wind turbine begins to PURPA—Public Utility Regulatory systems can be placed where the windmeet the needs of a home requiring generate electricity. Policies Act (1978), 16 U.S.C. § 2601.18 resource is the best and connected to 300 kWh per month in a location with CFR §292 that refers to small the pump motor with an electric a 14-mile-per-hour (6.26-meters-per- Cut-out wind speed—The wind speed generator utility connection rules. cable. second) annual average wind speed. at which a wind turbine ceases to The manufacturer can provide you generate electricity. Rated output capacity—The output with the expected annual energy out- power of a wind machine operating put of the turbine as a function of Density—Mass per unit of volume. at the rated wind speed. annual average wind speed. The Downwind—On the opposite side This 1 kW Whisper Rated wind speed—The lowest wind manufacturer will also provide infor- from the direction from which the turbine provides speed at which the rated output mation on the maximum wind speed wind is blowing. direct AC power for power of a wind turbine is produced. the water pump for at which the turbine is designed to operate safely. Most turbines have Furling—A passive protection for the stock tanks on a Rotor—The rotating part of a wind ranch in Wheeler, automatic overspeed-governing sys- turbine where typically the rotor folds turbine, including either the blades Texas. tems to keep the rotor from spinning either up or around the tail vane. and blade assembly or the rotating out of control in very high winds. This portion of a generator. information, along with your local Grid—The utility distribution system. The network that connects electricity wind speed and your energy budget, Rotor diameter—The diameter of the generators to electricity users. will help you decide which size tur- circle swept by the rotor. bine will best meet your electricity HAWT—Horizontal axis wind turbine. needs. Rotor speed—The revolutions per Inverter—Adevice 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 begin to spin. See also cut-in wind for electrical current (1000 watts). speed. Elliott Bayly/PIX09681 20 Small Wind Electric Systems Small Wind Electric Systems 5

What are the Basic Parts Basic Parts of a Small of a Small Wind Electric Wind Electric System System? Rotor Home wind energy systems generally comprise a rotor, a generator or Generator/ Tail alternator alternator mounted on a frame, a tail (usually), a tower, wiring, and the "balance of system" components: controllers, inverters, and/or batter- 02979312m ies. Through the spinning blades, the rotor captures the kinetic energy of Tower the wind and converts it into rotary motion to drive the generator.

Wind Turbine power production. For instance, to Most turbines manufactured today raise a 10-kW generator from a 60-foot are horizontal axis upwind machines tower height to a 100-foot tower that have two or three blades, which involves a 10% increase in overall are usually made of a composite mate-system cost, but it can produce 25% rial such as fiberglass. more power. The amount of power a turbine will There are two basic types of towers: produce is determined primarily by self-supporting (free standing) and the diameter of its rotor. The diameterguyed. Most home wind power sys- of the rotor defines its "swept area," ortems use a guyed tower. Guyed tow- the quantity of wind intercepted by ers, which are the least expensive, can the turbine. The turbine's frame is theconsist of lattice sections, pipe, or tub- structure onto which the rotor, genera-ing depending on the design, and tor, and tail are attached. The tail supporting guy wires. They are easier keeps the turbine facing into the to install than self-supporting towers. wind. However, because the guy radius must be one-half to three-quarters of the tower height, guyed towers Tower require enough space to accommodate them. While tilt-down towers are Because wind speeds increase with more expensive they offer the con- height, the turbine is mounted on sumer an easy way to perform a tower. In general, the higher the tower, the more power the wind system can produce. The tower also Tilt-down towers raises the turbine above the air provide easy maintenance for turbulence that can exist close to turbines. the ground because of obstructions 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 in the normal bottom of the rotor blades at least operating 30 feet (9 meters) above any obstacle Tilt-up tower in the position lowered position for that is within 300 feet (90 meters) of maintenance or the tower. Relatively small invest- hurricanes ments in increased tower height can yield very high rates of return in

02979311m 6 Small Wind Electric Systems a residential grid-connected applica- maintenance on smaller light-weight tion, the balance of system parts may turbines, usually 5 kW or less. Tilt- include a controller, storage batteries, down towers can also be lowered to a power conditioning unit (inverter), the ground during hazardous weatherand wiring. Some wind turbine such as hurricanes. Aluminum towerscontrollers, inverters, or other electri- are prone to cracking and should be cal devices may be stamped by a avoided. Most turbine manufacturersrecognized testing agency, like provide wind energy system packagesUnderwriters Laboratories. that include towers. Mounting turbines on rooftops is not recommended. All wind turbines Stand-Alone Systems vibrate and transmit the vibration Stand-alone systems (systems not con- to the structure on which they are nected to the utility grid) require bat- mounted. This can lead to noise and teries to store excess power generated structural problems with the building,for use when the wind is calm. They and the rooftop can cause excessive also need a charge controller to keep turbulence that can shorten the life ofthe batteries from overcharging. the turbine. Deep-cycle batteries, such as those used for golf carts, can discharge and For the times when neither the wind recharge 80% of their capacity hun- nor the PV modules are producing, Balance of System dreds of times, which makes them a most hybrid systems provide power good option for remote renewable The parts that you need in addition to Can I Go "Off-Grid"? through batteries and/or an engine- energy systems. Automotive batteries the turbine and the tower, or the bal- Hybrid Systems generator powered by conventional are shallow-cycle batteries and should ance of system parts, will depend on fuels such as diesel. If the batteries not be used in renewable energy sys- Hybrid wind energy systems can your application. Most manufacturers run low, the engine-generator can tems because of their short life in provide reliable off-grid power for can provide you with a system pack- provide power and recharge the bat- deep-cycling operations. homes, farms or even entire com- age that includes all the parts you teries. Adding an engine-generator need for your application. For exam- munities (a co-housing project, for example) that are far from the nearestmakes the system more complex, but ple, the parts required for a water modern electronic controllers can pumping system will be much differ- utility lines. According to many renewable energy experts, a "hybrid" operate these systems automatically. ent than what you need for a residen- An engine-generator can also reduce system that combines wind and tial application. The balance of system the size of the other components photovoltaic (PV) technologies offers required will also depend on whether needed for the system. Keep in mind several advantages over either single the system is grid-connected, stand- that the storage capacity must be system. In much of the United States, alone, or part of a hybrid system. For large enough to supply electrical wind speeds are low in the summer needs during non-charging periods. when the sun shines brightest and Battery banks are typically sized to longest. The wind is strong in the supply the electric load for one to A Bergey XL.10, winter when there is less sunlight 10-kW wind turbine three days. available. Because the peak operating is part of a grid- connected times for wind and PV occur at differ-An off-grid hybrid system may be wind/photovoltaic ent times of the day and year, hybrid practical for you if: hybrid system that systems are more likely to produce • You live in an area with average reduces the utility power when you need it. (For more annual wind speed of at least power used by this information on solar electric or home in Vermont. 9 mph (4.0 m/s). PV systems, contact the Energy The balance of system (upper right) Efficiency and Renewable Energy • A grid connection is not available includes from left Clearinghouse—see For More or can only be made through an to right, a Trace Information.) inverter for the PV system, a breaker box, and a Powersync inverter for the wind system. udy Forsyth, NREL/PIX09122 and PIX09123 Tr 18 Small Wind Electric Systems Small Wind Electric Systems 7

Small wind turbines generate direct A Southwest current (DC) electricity. In very small Windpower Air systems, DC appliances operate 303, 300 watt turbine is the sole directly off the batteries. If you want source of electricity to use standard appliances that use for this remote conventional household alternating home in northern current (AC), you must install an Arizona. 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- lated from living areas and electron- ics because they contain corrosive and explosive substances. Lead-acid batteries also require protection from temperature extremes.

proportionally more expensive. TheSouthwest Windpower/PIX09156 cost of an installed residential wind energy system that comes with an Grid-Connected Systems 80-foot tower, batteries, and inverter, In grid-connected systems, the only typically ranges from $13,000 to additional equipment required is a $40,000 for a 3 to 10 kW wind turbine. power conditioning unit (inverter) Although wind energy systems that makes the turbine output electri- involve a significant initial invest- cally compatible with the utility grid. ment, they can be competitive with Usually, batteries are not needed. conventional energy sources when you account for a lifetime of reduced What Do Wind Systems or avoided utility costs. The length of Cost? the payback period—the time before the savings resulting from your sys- Asmall turbine can cost anywhere tem equal the cost of the system from $3,000 to $35,000 installed, itself—depends on the system you depending on size, application, and choose, the wind resource on your service agreements with the manufac-site, electricity costs in your area, and turer. (The American Wind Energy how you use your wind system. For Association [AWEA] says a typical example, if you live in California and home wind system costs approxi- have received the 50% buydown of mately $32,000 (10 kW); a comparableyour small wind system, have net photovoltaic [PV] solar system wouldmetering, and an average annual cost over $80,000.) wind speed of 15 miles per hour Ageneral rule of thumb for estimating(mph) (6.7 meters per second [m/s]), the cost of a residential turbine is your simple payback would be $1,000 to $3,000 per kilowatt. Wind approximately 6 years. energy becomes more cost effective as the size of the turbine’s rotor increases. Although small turbines cost less in initial outlay, they are 8 Small Wind Electric Systems the company's integrity and ask for references of past customers with agreement with each company. installations similar to the one you are consequently wind energy installa- Usually these agreements are written considering. Ask the system owners tions are governed by the generic by the utility or the electricity about performance, reliability, and provisions of the NEC. provider. In the case of private maintenance and repair requirements, If your wind turbine is connected to (investor-owned) utilities, the terms and whether the system is meeting the local utility grid so that any of theand conditions in these agreements their expectations. Also, find out how power produced by your wind tur- must be reviewed and approved by long the warranty lasts and what it bine is delivered to the grid, then yourstate regulatory authorities. includes. utility also has legitimate concerns about safety and power quality that need to be addressed. The utility’s Insurance principal concern is that your wind Some utilities require small wind turbine automatically stops delivering turbine owners to maintain liability Where Can I Find any electricity to its power lines dur- Installation and ing a power outage. Otherwise line insurance in amounts of $1 million or Maintenance Support? workers and the public, thinking that more. Utilities consider these require- the line is "dead," might not take nor-ments are necessary to protect them The manufacturer/dealer should be mal precautions and might be hurt orfrom liability for facilities they do not able to help you install your machine. even killed by the power from your own and have no control over. Others Many people elect to install the turbine. Another concern among utili-consider the insurance requirements machines themselves. Before attempt- ties is that the power from your facili-excessive and unduly burdensome, ing to install your wind turbine, ask ty synchronize properly with the making wind energy uneconomic. In yourself the following questions: utility grid, and that it match the util-the 21 years since utilities have been arren Gretz, NREL/PIX09615 Gretz, arren W • Can I pour a proper cement ity’s own power in terms of voltage, required to allow small wind systems foundation? frequency, and power quality. to interconnect with the grid there has never been a liability claim, let Afew years ago, some state govern- • Do I have access to a lift or a way of alone a monetary award, relating to Small wind erecting the tower safely? ments started developing new electrical safety. turbines like this Things to Consider When standardized interconnection require- 10 kW Bergey Purchasing a Wind Turbine • Do I know the difference between ments for small renewable energy XL.10 provide AC and DC wiring? generating facilities (including wind electricity for Once you determine you can install a turbines). In most cases the new home, farm, and wind energy system in compliance • Do I know enough about electricity ranch applications. requirements have been based on con- with local land use requirements, you to safely wire my turbine? sensus-based standards and testing can begin pricing systems and compo- • Do I know how to safely handle procedures developed by independ- nents. Comparatively shop for a wind and install batteries? ent third-party authorities, such as the system as you would any major pur- Institute of Electrical and Electronic chase. Obtain and review the productIf you answered no to any of the Engineers and Underwriters literature from several manufacturers.above questions, you should probably Laboratories. As mentioned earlier, lists of manu- choose to have your system installed facturers are available from AWEA, by a system integrator or installer. (see For More Information), but not Contact the manufacturer for help all small turbine manufacturers are or call your state energy office and members of AWEA. Check the yellowlocal utility for a list of local system pages for wind energy system dealersinstallers. You can also check the yel- Interconnection Requirements in your area. low pages for wind energy system Most utilities and other electricity service providers. A credible installer Once you have narrowed the field, providers require you to enter into a will provide many services such as research a few companies to be sure formal agreement with them before permitting. Find out if the installer is they are recognized wind energy you interconnect your wind turbine a licensed electrician. Ask for refer- businesses and that parts and service with the utility grid. In states that ences and check them out. You may will be available when you need have retail competition for electricity also want to check with the Better them. You may wish to contact the service (e.g., your utility operates Business Bureau. Better Business Bureau to check on the local wires, but you have a choice of electricity provider) you may have to sign a separate 16 Small Wind Electric Systems Small Wind Electric Systems 9

exponent of 3 applied to it. This Although small wind turbines are means that even a small increase in very sturdy machines, they do requirewind speed results in a large increase some annual maintenance. Bolts and in power. That is why a taller tower electrical connections should be will increase the productivity of any checked and tightened if necessary. wind turbine by giving it access to The machines should be checked for higher wind speeds as shown in the corrosion and the guy wires for Wind Speeds Increase with Height proper tension. In addition, you graph. The formula for calculating should check for and replace any the power from a wind turbine is: worn leading edge tape on the blades, if appropriate. After 10 years, the Power = k C blades or bearings may need to be 1/2 ρ AV3 replaced, but with proper installation p and maintenance, the machine shouldWhere: last up to 20 years or longer. P=Power output, kilowatts If you do not have the expertise to C = Maximum power coefficient, maintain the machine, your installer p ranging from 0.25 to 0.45, may provide a service and mainte- dimension less (theoretical nance program. maximum = 0.59)

ρ = Air density, lb/ft3

How Much Energy Will My A=Rotor swept area, 2ft or System Generate? π D2/4 (D is the rotor Most U.S. manufacturers rate their diameter in ft,π = 3.1416) turbines by the amount of power theyV=Wind speed, mph can safely produce at a particular wind speed, usually chosen between k=0.000133 A constant to yield 24 mph (10.5 m/s) and 36 mph power in kilowatts. (Multiplying (16 m/s). The following formula the above kilowatt answer by illustrates factors that are important 1.340 converts it to horse- to the performance of a wind turbine. power. [i.e., 1 kW = 1.340 Notice that the wind speed, V, has an horsepower]).

Relative Size of Small Wind Turbines 40 8

2 30 7 7 m 20 6 6 m

5 Swept area, m 10 5 m

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

Rotor Diameter, m Rotor Diameter, 3 m

2 2 m

1 1 m

0 02979303m Source: Paul Gipe, Wind Energy Basics Awind turbine manufacturer can help 10 Small Wind Electric Systems you estimate the energy production you can expect. They will use a calculation based on the particular wind Air Density Change with Elevation turbine power curve, the average 10,000 annual wind speed at your site, the 9,000 height of the tower that you plan to 8,000 use, and the frequency distribution of 7,000 the wind–an estimate of the number 6,000 of hours that the wind will blow at 5,000 each speed during an average year. 4,000 They should also adjust this calcula- Elevation, ft Elevation, tion for the elevation of your site. 3,000 Contact a wind turbine manufacturer 2,000 or dealer for assistance with this 1,000 calculation.

0 02979302m 70 75 80 85 90 95 100 To get a preliminary estimate of the Density change compared to sea level, % performance of a particular wind turbine, use the formula below. need, the utility makes up the differ- and trees, and it needs to be 30 feet ence. When the wind system produces The rotor swept area, A, is important AEO = 0.01328 D above anything within 300 feet. You more electricity than the household because the rotor is the part of the also need enough room to raise and requires, the excess is sent or sold to turbine that captures the wind energy. lower the tower for maintenance, andthe utility. So, the larger the rotor, the more if your tower is guyed, you must Grid-connected systems can be practi- energy it can capture. The air density, allow room for the guy wires. ρ, changes slightly with air tempera- 2 3 cal if the following conditions exist: V Whether the system is stand-alone ture and with elevation. The ratings • You live in an area with average or grid-connected, you will also need for wind turbines are based on Where: to take the length of the wire run annual wind speed of at least standard conditions of 59° F (15° C) AEO= Annual energy output, between the turbine and the load 10 mph (4.5 m/s). at sea level. A density correction kWh/year (house, batteries, water pumps, etc.) should be made for higher elevations • Utility-supplied electricity is into consideration. A substantial as shown in the Air Density Change D=Rotor diameter, feet expensive in your area (about 10 to amount of electricity can be lost as a with Elevation graph. A correction for 15 cents per kilowatt-hour). V=Annual average wind speed, result of the wire resistance—the temperature is typically not needed mph • The utility's requirements for for predicting the long-term perform- longer the wire run, the more electric- connecting your system to its grid ance of a wind turbine. The Wind Energy Payback Period ity is lost. Using more or larger wire Workbook found at http://www.nrel. will also increase your installation are not prohibitively expensive. While the calculation of wind power gov/wind/ under consumer informa- cost. Your wire run losses are greater illustrates important features about • There are good incentives for the tion is a spreadsheet tool that can help when you have direct current (DC) wind turbines, the best measure of sale of excess electricity or for the you analyze the economics of a small instead of alternating current (AC). wind turbine performance is annual purchase of wind turbines. wind electric system and decide So, if you have a long wire run, it is energy output. The difference whether wind energy will work for advisable to invert DC to AC. Federal regulations (specifically, the between power and energy is that you. The spreadsheet can be opened Public Utility Regulatory Policies Act power (kilowatts [kW]) is the rate at using Microsoft Excel 95 software. of 1978, or PURPA) require utilities which electricity is consumed, while It asks you to provide information to connect with and purchase power energy (kilowatt-hours [kWh]) is the about how you're going to finance the from small wind energy systems. quantity consumed. An estimate of Can I Connect My System system, the characteristics of your However, you should contact your the annual energy output from your to the Utility Grid? site, and the properties of the system utility before connecting to their dis- wind turbine, kWh/year, is the best you're considering. It then provides Small wind energy systems can be tribution lines to address any power way to determine whether a particu- you with a simple payback estimation connected to the electricity distribu- quality and safety concerns. Your lar wind turbine and tower will pro- in years. If it takes too long to regain tion system and are called grid- utility can provide you with a list of duce enough electricity to meet your your capital investment—the number connected systems. A grid-connected requirements for connecting your sys- needs. of years comes too close or is greater wind turbine can reduce your con- tem to the grid. The American Wind than the life of the system—wind sumption of utility-supplied electrici-Energy Association is another good energy will not be practical for you. ty for lighting, appliances, and source for information on utility electric heat. If the turbine cannot deliver the amount of energy you airport to be different from your par- 14 Small Wind Electric Systems ticular location. AirportSmall wind Wind data Electric are Systems 11 generally measured at heights about 20–33 ft (6–10 m) above ground. Is There Enough Wind Average wind speeds increase with on My Site? height and may be 15%–25% greater at a typical wind turbine hub-height Does the wind blow hard and consis- of 80 ft (24 m) than those measured tently enough at my site to make a at airport anemometer heights. The small wind turbine system economi- National Climatic Data Center collects cally worthwhile? That is a key ques- data from airports in the United States tion and not always easily answered. and makes wind data summaries The wind resource can vary signifi- available for purchase. Summaries of cantly over an area of just a few miles wind data from almost 1000 U.S. air- because of local terrain influences ports are also included in theWind on the wind flow. Yet, there are steps Energy Resource Atlas of the United you can take that will go a long way States(see For More Information). towards answering the above question. Another useful indirect measurement of the wind resource is the observa- As a first step, wind resource maps tion of an area’s vegetation. Trees, like the one on pages 12 and 13 can especially conifers or evergreens, can be used to estimate the wind resourcebe permanently deformed by strong in your region. The highest average winds. This deformity, known as wind speeds in the United States are "flagging," has been used to estimate generally found along seacoasts, on the average wind speed for an area. ridgelines, and on the Great Plains; For more information on the use of however, many areas have wind resources strong enough to power a small wind turbine economically. The wind resource estimates on this map generally apply to terrain features that are well exposed to the wind, such as plains, hilltops, and ridge crests. Local terrain features may cause the wind resource at a specific site to differ con- Wind Speeds Increase with Height siderably from these estimates. More

detailed wind resource information, 150 including theW ind Energy Resource Atlas of United States, published by the 02979308m U.S. Department of Energy (DOE), can be found at the National Wind 120 Technology Center web site at http://www.nrel.gov/wind/ and the DOE Windpowering America web site at http://www.eren.doe.gov/ 90 windpoweringamerica/.

Another way to indirectly quantify ower height, ft T the wind resource is to obtain average 60 wind speed information from a nearby airport. However, caution should be used because local terrain influences and other factors may 30 cause the wind speed recorded at an

0 0 41 75 100 124 Increase in wind power, % 12 Small Wind Electric Systems Small Wind Electric Systems 13 airport to be different from your par- 14 Small Wind Electric Systems ticular location. Airport wind data are generally measured at heights about 20–33 ft (6–10 m) above ground. Flagging, the effect Is There Enough Wind Average wind speeds increase with of strong winds on Flagging 0 I on My Site? height and may be 15%–25% greater area vegetation, No Brushing at a typical wind turbine hub-height can help determine Prevailing wind Does the wind blow hard and consis- deformity and slight of 80 ft (24 m) than those measured area wind speeds. flagging tently enough at my site to make a at airport anemometer heights. The small wind turbine system economi- National Climatic Data Center collects cally worthwhile? That is a key ques- data from airports in the United States tion and not always easily answered. II III IV and makes wind data summaries Slight Moderate Complete The wind resource can vary signifi- available for purchase. Summaries of flagging flagging flagging cantly over an area of just a few miles wind data from almost 1000 U.S. air- because of local terrain influences ports are also included in theWind on the wind flow. Yet, there are steps Energy Resource Atlas of the United you can take that will go a long way States(see For More Information). V VI VII towards answering the above Partial Complete Carpeting question. Another useful indirect measurement throwing throwing of the wind resource is the observa- As a first step, wind resource maps tion of an area’s vegetation. Trees, like the one on pages 12 and 13 can 02979310m especially conifers or evergreens, can be used to estimate the wind resourcebe permanently deformed by strong Griggs-Putnam Index of Deformity in your region. The highest average winds. This deformity, known as wind speeds in the United States are Index I II III IV V VI VII "flagging," has been used to estimate generally found along seacoasts, on Wind mph 7-9 9-11 11-13 13-16 15-18 16-21 22+ the average wind speed for an area. ridgelines, and on the Great Plains; For more information on the use of Speed m/s 3-4 4-5 5-6 6-7 7-8 8-9 10 output of the system and also wind however, many areas have wind speed data if available. resources strong enough to power a small wind turbine economically. The flagging you may want to obtain wind resource estimates on this map ASiting Handbook for Small Wind generally apply to terrain features that Energy Conversion Systems(see For are well exposed to the wind, such as More Information). How Do I Choose the Best plains, hilltops, and ridge crests. Local Direct monitoring by a wind resourceSite for My Wind Turbine? terrain features may cause the wind measurement system at a site pro- You can have varied wind resources resource at a specific site to differ con- vides the clearest picture of the avail- within the same property. In addition siderably from these estimates. More able resource. A good overall guide to measuring or finding out about the detailed wind resource information, on this subject is theW ind Resource annual wind speeds, you need to including theW ind Energy Resource Assessment Handbook(see For More know about the prevailing directions Atlas of United States, published by the Information). Wind measurement sys-of the wind at your site. If you live in U.S. Department of Energy (DOE), tems are available for costs as low as complex terrain, take care in selecting can be found at the National Wind $600 to $1200. This expense may or the installation site. If you site your Technology Center web site at may not be hard to justify depending wind turbine on the top of or on the http://www.nrel.gov/wind/ and the on the exact nature of the proposed windy side of a hill, for example, you DOE Windpowering America web small wind turbine system. The meas-will have more access to prevailing site at http://www.eren.doe.gov/ urement equipment must be set high winds than in a gully or on the lee- windpoweringamerica/. enough to avoid turbulence created ward (sheltered) side of a hill on the Another way to indirectly quantify by trees, buildings, and other obstruc-same property. In addition to geologic the wind resource is to obtain average tions. The most useful readings are formations, you need to consider wind speed information from a those taken at hub-height, the eleva- existing obstacles such as trees, nearby airport. However, caution tion at the top of the tower where the houses, and sheds, and you need to should be used because local terrain wind turbine is going to be installed. plan for future obstructions such as influences and other factors may If there is a small wind turbine systemnew buildings or trees that have not cause the wind speed recorded at an in your area, you may be able to reached their full height. Your turbine obtain information on the annual needs to be sited upwind of buildings 10 Small Wind Electric Systems Small Wind Electric Systems 15

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

Region of highly 2 H turbulent H flow 02979307m

2 H 20 H need, the utility makes up the differ- and trees, and it needs to be 30 feet ence. When the wind system producesThe farther you above anything within 300 feet. You more electricity than the household place your wind also need enough room to raise and turbine from requires, the excess is sent or sold to obstacles such lower the tower for maintenance, andthe utility. as buildings or if your tower is guyed, you must Grid-connected systems can be practi-trees, the less allow room for the guy wires. turbulence you cal if the following conditions exist: will encounter. Whether the system is stand-alone • You live in an area with average or grid-connected, you will also need to take the length of the wire run annual wind speed of at least between the turbine and the load 10 mph (4.5 m/s). (house, batteries, water pumps, etc.) • Utility-supplied electricity is into consideration. A substantial expensive in your area (about 10 to amount of electricity can be lost as a 15 cents per kilowatt-hour). result of the wire resistance—the longer the wire run, the more electric-• The utility's requirements for ity is lost. Using more or larger wire connecting your system to its grid will also increase your installation are not prohibitively expensive. cost. Your wire run losses are greater • There are good incentives for the when you have direct current (DC) sale of excess electricity or for the instead of alternating current (AC). purchase of wind turbines. So, if you have a long wire run, it is advisable to invert DC to AC. Federal regulations (specifically, the Public Utility Regulatory Policies Act of 1978, or PURPA) require utilities to connect with and purchase power Can I Connect My System from small wind energy systems. to the Utility Grid? However, you should contact your utility before connecting to their dis- Small wind energy systems can be tribution lines to address any power connected to the electricity distribu- quality and safety concerns. Your tion system and are called grid- utility can provide you with a list of connected systems. A grid-connected requirements for connecting your sys- wind turbine can reduce your con- tem to the grid. The American Wind sumption of utility-supplied electrici-Energy Association is another good ty for lighting, appliances, and source for information on utility electric heat. If the turbine cannot deliver the amount of energy you 16 Small Wind Electric Systems

exponent of 3 applied to it. This Although small wind turbines are A grid-connected Grid-connected Systems means that even a small increase in wind turbine can very sturdy machines, they do requirewind speed results in a large increase reduce your some annual maintenance. Bolts and in power. That is why a taller tower consumption of Meter electrical connections should be utility-supplied will increase the productivity of any electricity. checked and tightened if necessary. wind turbine by giving it access to The machines should be checked for higher wind speeds as shown in the AC corrosion and the guy wires for Wind Speeds Increase with Height Inverter proper tension. In addition, you graph. The formula for calculating Load should check for and replace any the power from a wind turbine is: Wind worn leading edge tape on the blades, turbine if appropriate. After 10 years, the Power = k C blades or bearings may need to be ρ 3 p 1/2 AV the NEG credit can be carried for up replaced, but with proper installation 02979301m to a year. and maintenance, the machine shouldWhere: last up to 20 years or longer. Most of North America gets more P=Power output, kilowatts interconnection requirements. The wind in the winter than in the sum- If you do not have the expertise to following information about utility C = Maximum power coefficient, mer. For people using wind energy to maintain the machine, your installer p grid connection requirements was ranging from 0.25 to 0.45, displace a large load in the summer may provide a service and mainte- taken from AWEA's Web site. For dimension less (theoretical like air-conditioning or irrigation nance program. more detailed information, visit maximum = 0.59) water pumping, having an annual http://www.awea.org/ or contact NEG credit allows them to produce ρ = Air density, lb/ft3 AWEA (see For More Information). NEG in the winter and be credited in 2 the summer. How Much Energy Will My A=Rotor swept area, ftor Net Metering System Generate? π D2/4 (D is the rotor The concept of net metering programs Most U.S. manufacturers rate their diameter in ft,π = 3.1416) is to allow the electric meters of cus- turbines by the amount of power theyV=Wind speed, mph tomers with generating facilities to can safely produce at a particular turn backwards when their generators wind speed, usually chosen between k=0.000133 A constant to yield Safety Requirements are producing more energy than the 24 mph (10.5 m/s) and 36 mph power in kilowatts. (Multiplying customers’ demand. Net metering Whether or not your wind turbine is (16 m/s). The following formula the above kilowatt answer by allows customers to use their genera- connected to the utility grid, the illustrates factors that are important 1.340 converts it to horse- tion to offset their consumption over installation and operation of the wind to the performance of a wind turbine. power. [i.e., 1 kW = 1.340 the entire billing period, not just turbine is probably subject to the elec- Notice that the wind speed, V, has an horsepower]). instantaneously. This offset would trical codes that your local govern- enable customers with generating ment (city or county) or in some facilities to receive retail prices for instances your state government has more of the electricity they generate. in place. The government’s principal concern is with the safety of the Net metering varies by state and by facility, so these code requirements utility company, depending on emphasize proper wiring and installa- whether net metering was legislated tion, and the use of components or directed by the Public Utility that have been certified for fire and Commission. Net metering programs electrical safety by approved testing all specify a way to handle the net laboratories, such as Underwriters excess generation (NEG) in terms of Laboratories. Most local electrical payment for electricity and/or length codes requirements are based on the of time allowed for NEG credit. If the National Electrical Code (NEC), net metering requirements define which is published by the National NEG on a monthly basis, the con- Fire Protection Association. As of sumer can only get credit for their 1999, the latest version of the NEC did excess that month. But if the net not have any sections specific to the metering rules allow for annual NEG, installation of wind energy facilities, 8 Small Wind Electric Systems Small Wind Electric Systems 17 agreement with each company. consequently wind energy installa- Usually these agreements are written tions are governed by the generic by the utility or the electricity provisions of the NEC. provider. In the case of private If your wind turbine is connected to (investor-owned) utilities, the terms the local utility grid so that any of theand conditions in these agreements power produced by your wind tur- must be reviewed and approved by bine is delivered to the grid, then yourstate regulatory authorities. utility also has legitimate concerns about safety and power quality that need to be addressed. The utility’s Insurance principal concern is that your wind Some utilities require small wind turbine automatically stops delivering turbine owners to maintain liability any electricity to its power lines during a power outage. Otherwise line insurance in amounts of $1 million or workers and the public, thinking that more. Utilities consider these require- the line is "dead," might not take nor-ments are necessary to protect them mal precautions and might be hurt orfrom liability for facilities they do not even killed by the power from your own and have no control over. Others turbine. Another concern among utili-consider the insurance requirements ties is that the power from your facili-excessive and unduly burdensome, ty synchronize properly with the making wind energy uneconomic. In utility grid, and that it match the util-the 21 years since utilities have beenThis grid- ity’s own power in terms of voltage, required to allow small wind systemsconnected, frequency, and power quality. to interconnect with the grid there 10 kW Bergey has never been a liability claim, let wind turbine Afew years ago, some state govern- offsets electrical alone a monetary award, relating to ments started developing new power electrical safety. consumption for standardized interconnection require- a small business ments for small renewable energy in Norman, generating facilities (including wind Oklahoma. turbines). In most cases the new requirements have been based on con- sensus-based standards and testing procedures developed by independ- ent third-party authorities, such as the Institute of Electrical and Electronic Engineers and Underwriters Laboratories.

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) you may have to sign a separate Bergey Windpower/PIX07166 Bergey 18 Small Wind Electric Systems

generating facilities, utilities often In six states (California, Maryland, Small wind turbines generate direct want customers to indemnify them Nevada, Oklahoma, Oregon, and current (DC) electricity. In very small for any potential liability arising from Washington), laws or regulatory systems, DC appliances operate the operation of the customer’s generat- authorities prohibit utilities from directly off the batteries. If you want ing facility. Although the basic princi- imposing any insurance requirements to use standard appliances that use ple is sound—utilities should not be on small wind systems that qualify for conventional household alternating held responsible for property damage "net metering." In at least three other current (AC), you must install an or personal injury attributable to states (Idaho, New York, Virginia) reg- inverter to convert DC electricity someone else—indemnity provisions ulatory authorities have allowed utili- from the batteries to AC. Although should not favor the utility but should ties to impose insurance requirements, the inverter slightly lowers the be fair to both parties. Look for lan- but have reduced the required cover- overall efficiency of the system, it guage that says, "each party shall age amounts to levels consistent with allows the home to be wired for AC, indemnify the other . . ." rather than conventional residential or commer- a definite plus with lenders, electri- "the customer shall indemnify the cial insurance policies (e.g., $100,000 cal code officials, and future utility . . ." to $300,000). If your insurance homebuyers. amounts seem excessive, you can ask For safety, batteries should be iso- for a reconsideration from regulatory lated from living areas and electron- authorities (in the case of private Customer Charges ics because they contain corrosive investor-owned utilities) or to the Customer charges can take a variety and explosive substances. Lead-acid utility’s governing board (in the case of forms, including interconnection batteries also require protection from of publicly-owned utilities). charges, metering charges, and temperature extremes. standby charges, among others. You proportionally more expensive. The should not hesitate to question any cost of an installed residential wind charges that seem inappropriate to energy system that comes with an Indemnification Grid-Connected Systems you. Federal law (Public Utility 80-foot tower, batteries, and inverter, An indemnity is an agreement Regulatory Policies Act of 1978, or In grid-connected systems, the only typically ranges from $13,000 to between two parties where one agrees PURPA, Section 210) prohibits utilities additional equipment required is a $40,000 for a 3 to 10 kW wind turbine. to secure the other against loss or from assessing discriminatory charges power conditioning unit (inverter) Although wind energy systems damage arising from some act or to customers who have their own that makes the turbine output electri- involve a significant initial invest- some assumed responsibility. In generation facilities. cally compatible with the utility grid. ment, they can be competitive with the context of customer-owned Usually, batteries are not needed. conventional energy sources when you account for a lifetime of reduced What Do Wind Systems or avoided utility costs. The length of Connecting to the Utility Grid— Cost? the payback period—the time before A Success Story the savings resulting from your sys- Asmall turbine can cost anywhere This 10-kW Bergey wind turbine, installed on a tem equal the cost of the system from $3,000 to $35,000 installed, farm located in Southwestern Kansas in 1983, itself—depends on the system you depending on size, application, and produces an average 1700–1800 kilowatt-hours choose, the wind resource on your service agreements with the manufac- per month, reducing the user's monthly utility site, electricity costs in your area, and turer. (The American Wind Energy bills by approximately 50%. The turbine cost how you use your wind system. For Association [AWEA] says a typical about $20,000 when it was installed. Since then, example, if you live in California and home wind system costs approxi- the cost for operation and maintenance has been have received the 50% buydown of mately $32,000 (10 kW); a comparable about $50 per year. The only unscheduled main- your small wind system, have net photovoltaic [PV] solar system would tenance activity over the years was repair to the metering, and an average annual cost over $80,000.) turbine required as a result of damage caused by wind speed of 15 miles per hour a lightning strike. Insurance covered all but $500 Ageneral rule of thumb for estimating(mph) (6.7 meters per second [m/s]), of the $9000 cost of damages. The basic system the cost of a residential turbine is your simple payback would be parts include: $1,000 to $3,000 per kilowatt. Wind approximately 6 years. energy becomes more cost effective Bergey XL.10 wind turbine as the size of the turbine’s rotor 100-foot free-standing lattice tower increases. Although small turbines Inverter cost less in initial outlay, they are arren Gretz, NREL/PIX09634 Gretz, arren W 6 Small Wind Electric Systems Small Wind Electric Systems 19

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

Generator

AC or Load Regulation and DC conversion Wind turbine 02979301m

BatteryFor bankthe times when neither the wind nor the PV modules are producing, most hybrid systems provide power Can I Go "Off-Grid"? through batteries and/or an engine- Hybrid Systems generator powered by conventional fuels such as diesel. If the batteries Hybrid wind energy systems can run low, the engine-generator can provide reliable off-grid power for homes, farms or even entire com- provide power and recharge the bat- munities (a co-housing project, for teries. Adding an engine-generator example) that are far from the nearestmakes the system more complex, but utility lines. According to many modern electronic controllers can renewable energy experts, a "hybrid" operate these systems automatically. An engine-generator can also reduce system that combines wind and the size of the other components photovoltaic (PV) technologies offers needed for the system. Keep in mind several advantages over either single that the storage capacity must be system. In much of the United States, large enough to supply electrical wind speeds are low in the summer needs during non-charging periods. when the sun shines brightest and Battery banks are typically sized to longest. The wind is strong in the supply the electric load for one to winter when there is less sunlight three days. available. Because the peak operating times for wind and PV occur at differ-An off-grid hybrid system may be ent times of the day and year, hybrid practical for you if: systems are more likely to produce • You live in an area with average power when you need it. (For more annual wind speed of at least information on solar electric or 9 mph (4.0 m/s). PV systems, contact the Energy Efficiency and Renewable Energy • A grid connection is not available Clearinghouse—see For More or can only be made through an Information.) 20 Small Wind Electric Systems

• You would like to gain energy expensive extension. The cost of What are the Basic Parts running a power line to a remote independence from the utility. of a Small Wind Electric site to connect with the utility grid • You would like to generate clean System? can be prohibitive, ranging from power. $15,000 to more than $50,000 per Home wind energy systems gener- mile, depending on terrain. ally comprise a rotor, a generator or alternator mounted on a frame, a tail (usually), a tower, wiring, and the "balance of system" components: controllers, inverters, and/or batteries. Through the spinning blades, the rotor captures the kinetic energy of Living Off-Grid—A Success Story the wind and converts it into rotary This home, built near in Ward, Colorado (at an elevation of 9000 feet), has motion to drive the generator. been 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 Wind Turbine (based on 1985 rates) to connect to the utility lines. The owners decided to power production. For instance, to raise a 10-kW generator from a 60-foot install a hybrid electric system powered Most turbines manufactured today tower height to a 100-foot tower by wind, solar, and a generator for a cost are horizontal axis upwind machines involves a 10% increase in overall of about $19,700. The parts of the system that have two or three blades, which system cost, but it can produce 25% include: are usually made of a composite mate- rial such as fiberglass. more power. Bergey 1.5 kW wind turbine, 10-ft (3-m) There are two basic types of towers: diameter rotor, 70-ft. (21-m) tower The amount of power a turbine will produce is determined primarily by self-supporting (free standing) and Solarex PV panels, 480 watts the diameter of its rotor. The diameterguyed. Most home wind power sys- 24 DC battery bank, 375 ampere-hours of the rotor defines its "swept area," ortems use a guyed tower. Guyed tow- the quantity of wind intercepted by ers, which are the least expensive, can Trace sine wave inverter, 120 AC, 1 phase, the turbine. The turbine's frame is theconsist of lattice sections, pipe, or tub- 4 kW structure onto which the rotor, genera-ing depending on the design, and Onan propane-fueled generator, 6.5 kW tor, and tail are attached. The tail supporting guy wires. They are easier rated (3 kW derated for altitude) keeps the turbine facing into the to install than self-supporting towers. Electric appliances in the home include wind. However, because the guy radius television, stereo, two computers, toaster, must be one-half to three-quarters blender, vacuum cleaner, and hair dryer. of the tower height, guyed towers The largest electric loads are created by Tower require enough space to accommodate them. While tilt-down towers are a well pump and washing machine. The Because wind speeds increase with more expensive they offer the con- generator runs about 20% of the time, height, the turbine is mounted on sumer an easy way to perform particularly when the washing machine a tower. In general, the higher the is in use. Propane serves the other major tower, the more power the wind loads in the home: range, refrigerator, hot system can produce. The tower also water, and space heat. Solar collectors on raises the turbine above the air the roof provide pre-heating for the hot turbulence that can exist close to water. the ground because of obstructions such as hills, buildings, and trees. A general rule of thumb is to install a wind turbine on a tower with the Jim Green, NREL/PIX02796 Jim Green, bottom of the rotor blades at least 30 feet (9 meters) above any obstacle that is within 300 feet (90 meters) of the tower. Relatively small investments in increased tower height can yield very high rates of return in 4 Small Wind Electric Systems Small Wind Electric Systems 21

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 designedMW—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 of for the quan- wind turbine, containing the gearbox, tity of electricity obtained by integrat-generator, blade hub, and other parts. ing current flow in amperes over the O&M Costs time in hours for its flow; used as a —Operation and mainte- measure of battery capacity. nance costs. 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 wind turbine's power output across that 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 This 1 kW Whisper Rated wind speed—The lowest wind from the direction from which the turbine provides speed at which the rated output wind is blowing. direct AC power for power of a wind turbine is produced. the water pump for Furling—A passive protection for the stock tanks on a Rotor—The rotating part of a wind ranch in Wheeler, turbine where typically the rotor folds turbine, including either the blades Texas. either 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—Adevice 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 begin to spin. See also cut-in wind for electrical current (1000 watts). speed. 22 Small Wind Electric Systems wind technology. Available through AWEA. (202) 383-2500. http://www. structures permitted in residentially Swept area—The area swept by the Is Wind Energy Practical awea.org and Chelsea Green zoned areas, although variances are turbine rotor, A =πR 2, where R is the Publishing Company, White River for Me? often obtainable. Most zoning ordi- radius of the rotor. Junction, Vermont. 1999. ISBN Asmall wind energy system can nances have a height limit of 35 feet. 1-890132-07-01. http://www. Tip speed ratio—The speed at the tip provide you with a practical and You can find out about the zoning chelseagreen.com of the rotor blade as it moves through economical source of electricity if: restrictions in your area by calling Wind Energy Resource Atlas of the the air divided by the wind velocity. • your property has a good wind the local building inspector, board of United Statesby D. Elliott et al. This is typically a design requirement resource supervisors, or planning board. They for the turbine. Available from the American Wind can tell you if you will need to obtain Energy Association, 122 C. Street • your home or business is located ona building permit and provide you Turbulence—The changes in wind N.W., Washington D.C. 20001. at least one acre of land in a rural with a list of requirements. area speed and direction, frequently http://rredc.nrel.gov/wind/pubs/ In addition to zoning issues, your caused by obstacles. atlas • your local zoning codes or neighbors might object to a wind Upwind—On the same side as the Wind Power for Home and Businessby covenants allow wind turbines machine that blocks their view, or Paul Gipe—A comprehensive guide they might be concerned about noise. direction from which the wind is • your average electricity bills are blowing—windward. to modern small wind technology. Most zoning and aesthetic concerns Available through AWEA. (202) 383- $150 per month or more can be addressed by supplying objec- VAWT—Vertical axis wind turbine. 2500. http://www.awea.org and • your property is in a remote tive data. For example, the ambient noise level of most modern residential Wind farm—A group of wind tur- Chelsea Green Publishing Company, location that does not have easy wind turbines is around 52 to 55 deci- bines, often owned and maintained byWhite River Junction, Vermont. 1999. access to utility lines ISBN - 0-930031-64-4. http://www. bels. This means that while the sound one company. Also known as a wind • you are comfortable with long-termof the wind turbine can be picked out power plant. chelseagreen.com investments. of surrounding noise if a conscious Wind Power Workshopby Hugh Yaw—The movement of the tower top effort is made to hear it, a residential- Piggott—Provides an overview on sized wind turbine is no noisier than turbine that allows the turbine to stay Zoning Issues how to design a home-built wind tur- your average refrigerator. into the wind. bine. Available from The Center for Before you invest in a wind energy Alternative Technology, Machynlleth, system, you should research potential For More Information Powys, SY20 9AZ, UK Phone: 06154- obstacles. Some jurisdictions, for example, restrict the height of the Books 702400, FAX: 01654 702782. E-mail: [email protected], ASiting Handbook for Small Wind http://www.foe.co.uk/CAT Energy Conversion Systems. H. Wegley, Wind Resource Assessment Handbook: J. Ramsdell, M. Orgill and R. Drake, Report No. PNL-2521 Rev.1, 1980; Fundamentals for Conducting a available from National Technical Successful Monitoring Program—This Information Service, 5285 Port Royal handbook presents industry-accepted Rd., Springfield, VA 22151. guidelines for planning and conduct- (800) 553-6847. http://www.ntis. ing a wind resource measurement gov/ordering.htm program. These guidelines, which are detailed and highly technical, empha- Energy Savers Tips on Saving Energy size the tasks of selecting, installing, and Money at Home—A consumer's and operating wind measurement guide for saving energy and reducingequipment, as well as collecting and utility bills. Available from U.S. analyzing the associated data. Department of Energy's Energy Prepared by AWS Scientific, Inc. Efficiency and Renewable Energy Available electronically in NREL's Clearinghouse (EREC), P.O. Box 3048,publication database at http://www. Merrifield, Virginia 22116. (800) nrel.gov/publications. 363-3732. http://www.eren.doe.gov/ consumerinfo/energy_savers. Wind Energy Basics by Paul Gipe—A comprehensive guide tomodern small 2 Small Wind Electric Systems Small Wind Electric Systems 23

Government Agencies systems. Order from AWEA (202) 383- 2500, http://www.awea.org Energy Efficiency and Renewable Energy Clearinghouse, P.O. Box 3048, Web Sites Merrifield, Virginia 22116 800-DOE- EREC (363-3732). http://www.eren. AWEA Small Wind Systems Web doe.gov site—Includes answers to frequently National Climatic Data Center, asked questions and information on Federal Building, 151 Patton Avenue, U.S. manufacturers. http://www. Asheville, North Carolina, 28801-5001.awea.org/smallwind.html (828) 271-4800. Fax (828) 271-4876. Database of State Incentives for http://www.ncdc.noaa.gov Renewable Energy—On the Web at U.S. Department of Commerce, http://www.dcs.ncsu.edu/solar/ National Technical Information dsire/dsire.html Service, 5285 Port Royal Road, Green Power Network Net Metering Springfield, Virginia 22161. (800) Web Site—Net metering programs are 553-6847. http://www.ntis.gov/ now available in 30 states. Visit this ordering.htm DOE Web site for information: http://www.eren.doe.gov/ greenpower/netmetering Non-Government Organizations Small Wind "Talk" on the Web— American Wind Energy Association, AWEA's Home Energy Systems elec- 122 C Street, N.W.th 4Floor, tronic mailing list is designed as a forum for the discussion of small-scale Washington, D.C. 20001. (202) 383- energy systems that include wind. To 2500. http://www.awea.org subscribe, send a subscription request Solar Energy International—Short awea-wind-home-subscribe@ courses on renewable energy and egroups.com. sustainable development, in Wind Energy for Homeowners—This Carbondale, Colorado. (970) 963-8855. Web site discusses things you should http://www.solarenergy.org consider before investing in a small wind energy system and provides Periodicals basic information about the systems. "Apples and Oranges" by Mick http://www.eren.doe.gov/wind/ Sagrillo—A comprehensive compari- homeowner.html 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 the homemade power enthusiast. (800)707-6586 or on the Web at: http://www.homepower.com

Videos An Introduction to Residential Wind Systems with Mick Sagrillo—A 63- minute video answering questions most often asked by homeowners as they consider purchasing and installing their own wind power 24 Small Wind Electric Systems

that they sell such tags. In addition, 2002 Farm Bill — Wind Mainstay Energy purchases green tags from smaller-scale renewable energy Energy Development systems, and Evolution Markets sells Provisions environmental attributes in the form of Renewable Energy Credits. Renewable Energy Systems and Energy Efficiency Improvements Incentive Type:Low-interest loans, loan Contacts: guarantees, and grants Green-e Eligible Technologies:Renewable energy (888) 634-7336 Introduction systems (energy derived from wind, green-e.org/your_e_choices/trcs.html Can I use wind energy to power my solar, biomass, geothermal, and hydro- Mainstay Energy gen derived from biomass or water home? This question is being asked (877) 473-3682 using a renewable energy source) and across the country as more people [email protected] energy efficiency improvements www.mainstayenergy.com look for affordable and reliable Applicable Sectors:Agriculture, rural, sources of electricity. small commercial Evolution Markets Amount:Varies. The grant may not exceed (914) 323-0200 Small wind electric systems can [email protected] 25% of the cost of a project, and a com- make a significant contribution to bined grant and loan or guarantee may our nation's energy needs. Although not exceed 50% of the cost of a project. wind turbines large enough to pro- Terms:2003 – 2007 vide a significant portion of the elec- Date Enacted:2002 tricity needed by the average U.S. Authority: Farm Bill, Title IX, Section 9006 home generally require one acre of Summary:This law allows direct financial property or more, approximately assistance to farmers, ranchers, and rural 21 million U.S. homes are built on small businesses for the purchase of wind power and other renewable energy sys- one-acre and larger sites, and 24% tems and for energy efficiency improve- of the U.S. population lives in rural ments. This program is authorized for areas. funding for up to $23,000,000 per year in 2003-2007, totaling up to $115 million. In A small wind electric system will determining the amount of a grant or loan, work for you if: USDA shall consider the type of renewable • There is enough wind where you energy system, the quantity of energy likely Windpower/PIX01476 Bergey to be generated, the expected environmen- live Homeowners, ranchers, and small businesses can use wind- tal benefits, the extent to which the system generated electricity to reduce their utility bills. This grid- is replicable, and the amount of energy • Tall towers are allowed in your connected system installed for a home in Norman, Oklahoma, savings from energy efficiency improve- neighborhood or rural area reduces the homeowner's utility bill by $100 per month. ments and the likely payback period. USDA Rural Development State Office • You have enough space contacts can be found at www.rurdev. • You can determine how much usda.gov/rbs/farmbill/contacts.htm. electricity you need or want to USDA Farm Bill Web site: www.rurdev. produce usda.gov/rbs/farmbill. • It works for you economically. The purpose of this guide is to pro- Green Tags vide you with the basic information about small wind electric systems to Wind energy systems generate both electricity and environmental attributes help you decide if wind energy will (emission savings from not burning fossil work for you. fuels). These environmental attributes are a product that some consumers are interested in purchasing. Green tags can be sold to marketing entities who will then aggregate them and resell them to Why Should I Choose Wind? consumers. The Green-e Web site below includes a list Wind energy systems are one of the of companies that might be interested in most cost-effective home-based purchasing green tags, by virtue of the fact renewable energy systems. Small Wind Electric Systems

Wisconsin Incentives Wind Energy Equipment Exemption Phone: (608) 831-1127 Ext.308 The value added by a qualified wind energy system, Fax: (608) 836-1290 as well as transmission equipment, is exempt for E-mail: [email protected] property tax purposes. Commercial, industrial, and Web site: www.wisconsun.org residential applications are eligible. The value of Beth Shippert equipment or components for conventional energy Wisconsin Energy Conservation Corporation systems that operate without mechanical means 211 S Paterson St. 3rd Floor is not eligible for tax exemption. Madison, WI 53703 Authority: Wis. Stat. § 70.111 Phone: (608) 249-9322 Ext.320 www.dsireusa.org/library/docs/incentives/WI01F.htm Fax: (608) 249-0339 E-mail: [email protected] Web site: www.weccusa.org Implementation Grant Focus on Energy offers an Implementation Grant to provide financial support for large renewable energy projects (greater than 20 kW or 5,000 therms per year). Eligible wind systems may receive grants Contact of up to 25% of project costs with a maximum of Alex De Pillis $35,000. The amount is based on the estimated Wisconsin Department of Administration annual kWh generated or thermal energy saved or Division of Energy utilized. Businesses, individuals, organizations, insti- P.O. Box 7868 tutions, and municipal or tribal governments located Madison, WI 53707-7868 in the service territory of a participating electric or Phone: (608) 266-1067 natural gas utility are eligible. Renewable energy Fax: (608) 267-6931 systems can be off-grid. For more information, visit E-mail: [email protected] www.focusonenergy.com/page.jsp?pageId=725. Web site: www.doa.state.wi.us/energy/index.asp Loan Program Wisconsin Focus on Energy Low-interest loans, ranging from $2,500 to $20,000, Focus on Energy is a public/private partnership that for financing wind projects on existing owner-occupied offers energy information and services to residential, single-family and duplex homes are available. A par- business, and industrial customers throughout ticipating contractor must install eligible systems. Wisconsin. These services are delivered by a group Loan terms vary from 3 to 10 years with an interest of firms contracted by the Wisconsin Department of rate of 1.99% APR. Applicants may be asked to Administration's Division of Energy. The goals of this verify income when loans exceed $4,000. program are to encourage energy efficiency and use Customers must be located in the service territory of of renewable energy, enhance the environment, and a participating electric or natural gas provider. ensure the future supply of energy for Wisconsin. Applications for low-interest loans are available at Three programs support these goals, including www. cash-back rewards, grant, and loan programs. focusonenergy.com/page.jsp?pageId=904. Cash-Back Rewards Contact Businesses and homes installing or expanding Niels Wolter (see Cash-Back Rewards above) renewable energy systems are eligible for a partial reimbursement of expenses through the Cash-Back Interconnection Standards Rewards Program. Payments are based on the esti- Wisconsin is developing distributed generation (DG) mated amount of electricity generated annually. interconnection rules and revising outdated intercon- Nonresidential and residential wind energy systems nection rules for small renewable generators, includ- (20 kW or less) are eligible for up to 25% of project ing wind. Both residential and nonresidential sectors cost or $35,000. Customer property must be located will be eligible. The interconnection guidelines in the service territory of a participating electric or (www.dsireusa.org/library/docs/additionaldocs/WIDG natural gas provider. Applications are available at IntrGuidelinesv6.pdf) categorize DG systems by www.focusonenergy.com/page.jsp?pageId=904. capacity as follows: Contacts Category 1: 20 kW or less Niels Wolter Category 2: Greater than 20 kW to 200 kW WisconSUN Category 3: Greater than 200 kW to 1 MW c/o MSB Energy Associates Inc. Category 4: Greater than 1 MW to 15 MW 7507 Hubbard Ave., Suite 200 The interconnection rules (PSC 119) will establish Middleton, WI 53562 both a Standard Application Form and a Standard Interconnection Agreement. In both cases, separate, Other Contacts simplified documents will be used for small systems William Hui up to 20 kW. These smaller systems will also be eli- U.S. Department of Energy gible for net metering. Insurance requirements and Chicago Regional Office interconnection application fees are also based One South Wacker Drive, Suite 2380 on these categories. For more information, visit Chicago, IL 60606-4616 psc.wi.gov/electric/cases/electgen/electgen.htm. Phone: (312) 885-8586 Authority: Wis. Stat. § 196.025 (www.dsireusa. Fax: (312) 886-8561 org/library/docs/incentives/WI11R.htm) E-mail: [email protected] Web site: www.eere.energy.gov/cro Net Metering The Public Service Commission of Wisconsin Wind Powering America (PSCW) authorized net metering for commercial, www.windpoweringamerica.gov industrial, and residential customer-owned systems (up to 20 kW). The order applies to all utilities under the jurisdiction of PSCW. All technologies, including renewables such as wind and cogeneration, are eligible. There is no limit on the amount of energy a utility can receive through net metering. Utilities pay customer generators the retail rate for net excess generation from renewable energy facilities. Customer generators producing energy from non-renewable resources receive the avoided-cost rate for net excess generation. Authority 1: Rate Schedules; PSC of Wisconsin Order 6690-UR-107 (www.dsireusa.org/library/ docs/incentives/WI11R.htm) Contact Paul Helgeson Public Service Commission of Wisconsin 610 North Whitney Way P.O. Box 7854 Madison, WI 53707-7854 Phone: (608) 266-3905 Fax: (608) 266-3957 E-mail: [email protected] Web site: psc.wi.gov/

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) www.eere.energy.gov DOE/GO-102004-1807 • May 2004

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