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THREE OF A KIND: THE PRIMARY WAYS TO PRODUCE WIND POWER
(One of) the answers
is blowing
IN THE WIND By harnessing an abundant, clean and free resource, wind power has become a viable source of energy for homes, farms and businesses. Despite setbacks such as large start-up costs and the remote locations of wind farms, it remains one of the fastest growing forms of alternative energy on the planet. By John Kalmar
SMALL SCALE
WIND FARMS
OFFSHORE WIND FARMS
Small-scalewindturbines allowhomeowners, farms, small businesses andpublicfacilities togeneratetheir ownon-siteenergy. Small-scaleturbines aredefined as havingcapacities of producing100kilowatts or less. Averagesmall windturbines standfrom35to140feet tall. Small turbines may serveas a way tobreak free fromtherelianceof fossil fuels for poweringhomes andbusinesses, but they don’t comecheap. For a 10kilowatt machine, whichis thesize neededtopower anaverage home, thepricetagranges from$35,000to$50,000.
Bybeingbuilt inrural regions awayfromcities, large scalewindfarms areabletoharness thepowerful winds intheir isolatedareas.Texas is hometothesixlargest winds farms intheU.S. withtheRoscoeWindFarm inRoscoe,Texas tippingthewindenergyscales at a capacityof 781.5MW.The100,000-acreWest Texas farm houses 627windturbines, rangingfrom350to415feet tall.Thelandwas primarily usedfor cottonbeforebeing convertedtoa windfarmin 2007. RoscoeWindFarmcan generateelectricityfor more than230,000homes.
Thebiggest advantageof offshorewindfarms is their ability tocapturethestrong, afternoonbreezes producedat sea, whichoccurs at a timeof peak energy consumption. Whiletherecurrently areno offshorewindfarms intheU.S. (pendingtheCape WindProject), thelargest offshoreproject is the Thanet OffshoreWindFarm, approximately seven miles off thecoast of England.Thewindfarm boasts 100turbines witha total capacity of 300MW, whichis enoughtopower 200,000Britishhomes.
WORKING WITH WIND WIND SPEED Winds blowover theblades of theturbine, causingthemtorotate.Turbines generally don’t operateunless winds speeds blow greater than8 miles per hour. Turbines are abletogeneratethemost electricitywhen winds areblowingat 22-to-55 mph.
BREEZY NUMBERS States with the highest installed megawatt capacity for wind TEXAS SWEPT AREA Thearea coveredby therotating rotors, alsoknownas theswept area, plays a roleinhowmuchelectricity theturbines canproduce.Thelarger theswept area, thegreater the electricity yieldwill be.
SAY YES! TO WIND ENERGY! PLENTIFUL
JOBS
TIME
Windis oneof the cleanest forms of energy onearth. It’s a sustainable resourcethat canbe convertedtoenergy without emitting fossil fuels andhas fewnegativeimpacts ontheenvironment, makingit a popular choicefor renewableenergy resources.
Becauseit is a formof solar energy wind resources will never bedepleted. Windexists duetounevenheatingof theearthby thesun. As hot air rises, cool air moves intotakeits place, resultinginthecreationof wind.
Thegrowthinwind energyhasled tothecreationof moreengineering andmanufacturing jobsinwindenergytechnologies.The U.S. increaseditswindpower capacity bymorethan5,000megawatts(MW) in 2010toitscurrent capactiyof 40,180MW.
Comparedwith coal andnaturalgas power plants, it takes less time toconstruct wind farms. A50-megawatt windfarmis typically built in18to 24months, andthepayback energy periodis only threetosix months.
CO2
TURN OFF THE WIND TURBINES! COSTLY
DISTANCE
CONSISTENCY
AESTHETICS
Theaveragecost of windturbines in 2007rangedfrom $1.2millionto$2.6 millionper MWof nameplatecapacity, themaximum ratedoutput of a windgenerator. Most commercial-scaleturbines produce2MWof power.
Becauseof thehigh windspeeds, some 0 25 50 of thebest places toharvest windare inremotelocations, oftenhundreds of miles away from major cities. Buildingtransmission lines fromthesedesolatewind farms canbeexpensive.
Windisn’t always constant. This increases theneed tohavepower plants storetheenergy or the useof a battery systemtohelpevenout erraticflows. Turbines must beshut off in winds greater than55miles per hour to prevent damagetothemachine.
Windturbines aren’t themost aesthetically appealing structures. Some opponents citethat windturbines areaneyesore, causenoisepollution andposeas life-threatening obstacles tobothbirds andbats.
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20| ej
spring 2011
SOURCES: AMERICANWINDENERGYASSOCIATION, MSNBC.COM,NATIONALGEOGRAPHIC.COM,NATURALRESOURCESDEFENSECOUNCIL, NPR.ORG, POLITIFACT.COM,POWERNATURALLY.ORG,POWER-TECHNOLOGY.COM, SUSTAINABLEBUSINESS.COM,THENEWYORKTIMES, U.S. DEPARTMENTOFENERGY,U.S. DEPARTMENTOFTHEINTERIOR, U.S. ENERGYINFORMATIONADMINISTRATION,WINDUSTRY.ORG
Gearbox
Theelectrical output of thegenerator is connectedtoa larger electrical grid, whichsupplies power tohomes, offices andother businesses.
CALIFORNIA
2,192 MW
MINNESOTA
WASHINGTON & OREGON
Drive shaft
GENERATOR Generator Thespinning High-speed blades turna drive shaft shaft, whichpowers thegearbox within theturbine.Thegearbox rotates at 1,200-1,800 rpm, whichis the speedrequiredby most generators toproduceelectricity.Thegear box moves thehigh-speedshaft whichin turnfuels thegenerator.
IOWA 3,177 MW
2,104 MW
CLEAN
3,675 MW
10,085 MW
TURBINE SIZE Larger turbines takeadvantageof the morepowerful winds at altitudeandare less subjectedtoturbulence. Offshore windturbines areabletoharvest the dense, heavy air at sea level, whichis abletoproducemoreelectricity by exertingmorelift ontheblades. Most small-scaleturbines are100 feet tall witha rotor diameter of 23 feet. Thelargest windturbines standas tall as 230 feet witha rotor diameter spanning231 feet.
Megawatt capacity for other forms of U.S. energy in 2009 COAL: 459,803 MW NATURALGAS: 338,723 MW NUCLEAR: 106,618 MW HYDRO: 77,910 MW WIND: 34,683 MW*
1 MW = 1,000 U.S. HOMES
*The 2010 MW capacity for wind energy was reported at 40,180 by the American Wind Energy Association.
A breath of fresh wind facts 20 percent of the nation’s electricity that will be supported by wind energy in 2030, according to an U.S. Department of Energy estimate. 100,000-300,000 estimated number of birds killed per year by wind turbines.
39 million estimated number of birds killed per year by rural cats.
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