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Wind Renewable Energy Essentials: Wind n World generating capacity of wind energy is growing at 20-30% per year, and surpassed 90 Gigawatts (GW) in 2007 – 50 times installed capacity in 1990. Approximately 152 teraWatt hours (TWh) of wind electricityweregeneratedin2006. n AnnualinvestmenttoppedUSD50billionin2007.Theglobalwindindustryemploysaround200000 people. n Turbinecostshavedecreasedbyafactoroffoursincethe1980s.Since2004,howevertheyhaveincreased by20-80%,duetotightsupplyofturbinesandcomponents,andhighcommodityprices.In2007,onshore turbinecostsrangedfromUSD1.2m–1.8mperMW. n RecentproductioncostsonshorerangefromUSD75/MWhto97/MWhathightomediumqualitywind resourcesites.Onshorewindiscompetitiveatsiteswithgoodresourceandgridaccess. n TheIEAEnergy Technology Perspectives 2008publicationsuggeststhatin2050windpowercouldsupply upto12%ofglobaldemandforelectricity–withconcentratedeffortandtechnologyinnovation. n Barrierstogrowthincludecapitalcost,uncertaintyregardingpolicysupportandimpactsofvariabilityon powersystems,limitedgridcapacityandvisualimpact. Market status Windpowerintotalgenerated152TWhofelectricity in2006.In2007,windpowerplantsprovidedfor20% ofelectricityconsumptioninDenmark,10%inSpain, and6%inGermany.Morethan20GWofcapacitywere installedin2007alone,ledbytheUnitedStates,China and Spain. Cumulative installed capacities are shown in the map below. The largest individual wind power plant operating in 2007 (in Texas) had a capacity greaterthan700MW,thesameorderofmagnitudeas conventionalpowerplants. Figure 1. Cumulative installed gigawatts of wind power in leading countries, 1990 – 2007 Offshore Offshoreinstalledcapacitytopped1.1GWin2007,locatedinjustsixcountries,includingDenmark(420MW), UnitedKingdom(300MW),Netherlands(130MW),Ireland(25MW),andSweden(135MW).Severallarge projectsareplannedinothercountries.Offshorewindpowerplantscanproduceupto50%moreelectricity thantheironshorecousins,duetohigherandsteadierwindspeeds.Otheradvantagesincludegreatlyreduced visualimpact,lessturbulence,andlowernoiseconstraints–allowinghigherrotorspeeds.Ontheotherhand, withcurrenttechnologythehardwareanditsinstallationaremoreexpensive. Small wind Smallandmicrowindturbineshaveinthepastbeenconsideredmainlyforoff-gridapplications.Recentlya number of countries have shown renewed interest, including Canada, Ireland, Italy, Portugal, Spain, United KingdomandUnitedStates.However,reliabilityproblemspersist,andmarketsremainsmall. The wind resource Theglobalresourcemapbelowillustratesapproximate,averageglobalwindspeedson-andoffshore.The energycontentofthewindisproportionaltothecubeofthewindspeed,soaslighterfasteraveragespeed yields significantly greater output. This has major bearing on the financial viability of a project. A good windspeedsiteforanaveragedevelopmentisaround7m/s(25kmph,16mph)andabove,atahubheight of around 80 metres. The importance of a high quality wind regime is illustrated by the fact that the US producedmorewindelectricityin2007thananyothercountry,eventhoughitdoesnothavethelargest installedcapacity.Similarly,offshorewindenergyrepresented1.8%oftotalinstalledcapacity(in2006)but produced3.3%oftotalwindelectricity.Highqualitywindresourcesaredistributedthroughouttheglobe. Six countries worldwide account for almost all wind turbine manufacturing (see Figure 2). Although Denmark containsonlyalittleover3%ofglobalinstalledwindcapacity,itwasthebirthplaceofmodernwindenergyandstill producesoverathirdofallturbinessoldworldwide.OtherprinciplemanufacturingcountriesareGermany,Spain, theUSA,IndiaandChina.Theglobalwindindustryemploysaround200000people. 0 5 10 15 20 25 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 Spain Germany India China United States Manufacturing and employment INTERNATIONAL ENERGY AGENCY www.iea.org ©OECD/IEA,2008

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d Renewable Energy Essentials: Windn �World�generating�capacity�of�wind�energy� is�growing�at�20-30%�per�year,�and�surpassed�90�Gigawatts�

(GW)� in�2007�–�50� times� installed�capacity� in�1990.�Approximately�152� teraWatt�hours� (TWh)�of�wind�electricity�were�generated�in�2006.

n� �Annual�investment�topped�USD�50�billion�in�2007.�The�global�wind�industry�employs�around�200�000�people.

n� �Turbine�costs�have�decreased�by�a�factor�of�four�since�the�1980s.�Since�2004,�however�they�have�increased�by�20-80%,�due�to�tight�supply�of�turbines�and�components,�and�high�commodity�prices.�In�2007,�onshore�turbine�costs�ranged�from�USD�1.2m�–�1.8m�per�MW.�

n� �Recent�production�costs�onshore�range�from�USD�75/MWh�to�97/MWh�at�high�to�medium�quality�wind�resource�sites.�Onshore�wind�is�competitive�at�sites�with�good�resource�and�grid�access.�

n� �The�IEA�Energy Technology Perspectives 2008�publication�suggests�that�in�2050�wind�power�could�supply�up�to�12%�of�global�demand�for�electricity�–�with�concentrated�effort�and�technology�innovation.

n� �Barriers�to�growth�include�capital�cost,�uncertainty�regarding�policy�support�and�impacts�of�variability�on�power�systems,�limited�grid�capacity�and�visual�impact.

Market status Wind�power�in�total�generated�152�TWh�of�electricity�in�2006.�In�2007,�wind�power�plants�provided�for�20%�of�electricity�consumption�in�Denmark,�10%�in�Spain,�and�6%�in�Germany.�More�than�20GW�of�capacity�were�installed�in�2007�alone,�led�by�the�United�States,�China�and�Spain.�Cumulative� installed�capacities�are�shown�in� the�map�below.�The� largest� individual�wind�power�plant� operating� in� 2007� (in� Texas)� had� a� capacity�greater�than�700�MW,�the�same�order�of�magnitude�as�conventional�power�plants.�

Figure 1. Cumulative installed gigawatts of wind power in leading countries, 1990 – 2007

Offshore Offshore�installed�capacity�topped�1.1�GW�in�2007,�located��in�just�six�countries,�including�Denmark�(420�MW),�United�Kingdom�(300�MW),�Netherlands�(130�MW),�Ireland�(25�MW),�and�Sweden�(135�MW).�Several�large�projects�are�planned�in�other�countries.�Offshore�wind�power�plants�can�produce�up�to�50%�more�electricity�than�their�onshore�cousins,�due�to�higher�and�steadier�wind�speeds.�Other�advantages�include�greatly�reduced�visual�impact,�less�turbulence,�and�lower�noise�constraints�–�allowing�higher�rotor�speeds.�On�the�other�hand,�with�current�technology�the�hardware�and�its�installation�are�more�expensive.�

Smallwind� �Small�and�micro�wind�turbines�have�in�the�past�been�considered�mainly�for�off-grid�applications.�Recently�a�number�of�countries�have�shown�renewed�interest,� including�Canada,� Ireland,� Italy,�Portugal,�Spain,�United�Kingdom�and�United�States.�However,�reliability�problems�persist,�and�markets�remain�small.

Thewindresource� �The�global� resource�map�below�illustrates�approximate,�average�global�wind�speeds�on-�and�offshore.�The�energy�content�of�the�wind�is�proportional�to�the�cube�of�the�wind�speed,�so�a�slighter�faster�average�speed�yields� significantly� greater� output.� This� has� major� bearing� on� the� financial� viability� of� a� project.� A� good�wind�speed�site�for�an�average�development�is�around�7m/s�(25�kmph,�16mph)�and�above,�at�a�hub�height�of�around�80�metres.�The� importance�of�a�high�quality�wind�regime� is� illustrated�by�the�fact� that�the�US�produced�more�wind�electricity� in�2007�than�any�other�country,�even�though�it�does�not�have�the� largest�installed�capacity.�Similarly,�offshore�wind�energy�represented�1.8%�of�total�installed�capacity�(in�2006)�but�produced�3.3%�of�total�wind�electricity.�High�quality�wind�resources�are�distributed�throughout�the�globe.

�Six�countries�worldwide�account� for�almost�all�wind� turbine�manufacturing� (see�Figure�2).�Although�Denmark�contains�only�a�little�over�3%�of�global�installed�wind�capacity,�it�was�the�birthplace�of�modern�wind�energy�and�still�produces�over�a�third�of�all�turbines�sold�worldwide.�Other�principle�manufacturing�countries�are�Germany,�Spain,�the�USA,�India�and�China.�The�global�wind�industry�employs�around�200�000�people.

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�Investment� reached� USD� 50.2� billion� in� 2007,� accounting� for� 43%� of� new� investments� in� renewable�energy.�Wind�raised�USD�11.3�bn�in�public�markets,�60%�of�which�through�a�single�Initial�Public�Offering.�

Figure 2. World onshore and offshore resource map at 80m height and 15 km resolution, with installed capacity, production and manufacturing data for leading countries

Map notes: Figures for 2007 capacity increase for India and China are gross. TWh produced in India and China are for 2006. Most Danish activity in 2007 was in re-powering. Leading states in the Unites States, in terms of share of national electricity production, include Minnesota (5%), Iowa (5%), New Mexico (4%) and Oregon (3.5%).

Turbine�costs�have�decreased�by�a�factor�of�four�since�the�early�1980s.�Since�2004,�however,�they�have�risen�by�around�20-80%�(2006),�driven�by�supply�tightness�(turbines,�gear�boxes,�blades,�bearings�and�towers)�and�higher�commodity�prices� (particularly� steel�and�copper).� Industry� sources�expect� supply� tightness� to� loosen�by�2010.� In�2007,� onshore� turbine�costs� ranged� from� USD� 1.2m� per�MW� in� the� United� States� to� USD�1.8m� in� Italy.� Total� installed� costs�(inc.�turbine)�ranged�from�USD�1.4m�in� the�UK� to�USD�2.7m� in� Ireland�(Figure�3).

Figure 3. Evolution of investment costs in selected countries: 2003 to 2007 (USD millions per MW)

The�annual�operating� cost� for� large�onshore� turbines� in�2006,� including� insurance,� regular�maintenance,�spare�parts,�repair�and�administration�was�in�the�range�of�USD�14/MWh�to�USD�26/MWh.�O&M�costs�are�considerably�higher�for�offshore�wind�turbines.

At�sites�with�the�best�available�wind�resource�as�well�as�nearby�grid�access,�wind�power�plants�can�be�competitive�with�conventional�electricity�producers.�The�cost�per�unit�of�electricity�generated�depends�on�the�quality�of�the

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Wind resource map© 2008 3TIER Inc.

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dwind�resource�(represented�by�the�number�of�full� load�hours�of�operation)� investment�cost,�O&M�cost,�and�turbine�longevity.�Wind�power�plants�are�capital-intensive�so�the�cost�of�capital�(discount�rate)�is�a�decisive�factor�in�wind�cost�estimation.�Typical�production�costs,�levelised�over�turbine�lifetime,�with�a�discount�rate�of�7.5%�and�investment�costs�of�USD�1.6m�per�MW,�for�example,�range�from�USD�75/MWh�to�97/MWh,�at�high�to�medium�quality�wind�resource�sites,�as�illustrated�in�Figure�4.

�Costs� are� largely� dependent� on� water� depth� and� distance� from� shore.� Foundations,� installation,� and� grid�connection� are� significantly� more� costly� offshore.� Turbine� cost� is� typically� 20%� higher,� and� towers� and�

foundations�perhaps�150%�more.�However,�offshore�wind�plant� output� can�be�up� to�50%�greater,� due� to�higher�wind� speeds.� Installations� in� the� United� Kingdom� and�Sweden�in�2007�–�2008�cost�between�USD�2.5m�per�MW�and�USD�3.7m�per�MW,� and�production� costs� at� these�locations�ranged�from�USD�85�–�105/MWh.�

�Drivers�for�cost�reductions�include�increased�performance�and�reliability,�technology�advances,�larger�turbines�(when�installed�offshore),�and�increased�manufacturing�capacity.�The�use�of�“learning�rates”�to�gauge�future�cost�reductions�is�based�on�the�assumption�that�existing�trends�will�persist.�In�essence,�this�methodology�yields�a�percentage�reduction�in�costs�for�each�doubling�of�production.�For�wind�energy,�recent�IEA�analysis�suggests�a�learning�rate�of�around�10-20%.�With�a�10%�learning�rate,�costs�in�2015�would�be�about�USD�53/MWh�at�high�wind,�onshore�sites.

Strategies� to� mitigate� anthropogenic� climate� change,� and� other� negative� environmental� effects� of�conventional�power�production,�have�given�rise�to�a�range�of�supportive�government�policies�for�renewable�energy,�some�of�which�are�specific�to�wind�energy,�as�well�as�carbon�markets.�Other�drivers�include�technology�advances,�fossil�fuel�scarcity�and�increasing�price,�growing�concern�regarding�energy�independence,�electricity�market� liberalisation,�and�rising�electricity�demand�particularly� in�emerging�economies.�Off-grid�and�rural�energisation,�and�poverty�reduction�are�important�developing�country�drivers.�

Barriers�to�wind�energy�development�include�uncertainty�relating�to�the�future�of�/lack�of�incentive�schemes�(e.g.�annual�renewal�of�the�Production�Tax�Credit� in�the�USA),�concerns�about�the�impacts�of�variability�on�power�system�reliability,�access�to�transmission,�perceived�visual�and�ecological�impacts,�and�the�structure�of�conventional�electricity�markets.�The�latter�evolved�around�conventional�generation�and�utilities,�and�in�many�cases�could�be�optimised�to�facilitate�wind�power�participation.

The�outlook�is�for�continued�double-digit�percentage�annual�growth�in�wind�energy.�IEA�Energy�Technology�Perspectives�(ETP)�2008�suggests�that�wind�technology�could�feasibly�provide�9%�(approx.�2�700�TWh)�of�global�electricity�in�20301.�By�2050,�the�IEA’s�advanced�“BLUE”�Scenario,�which�requires�significant�technology�innovation,�suggests�that�as�much�as�12%�(approx.�5�200�TWh)�could�be�feasible2.�These�amounts�are�plotted�in�Figure�5,�as�a�range.�The�Global�Wind�Energy�Council�has�prepared�an�Advanced�Scenario�that�suggests�

that,� if� stronger� early� action� is� taken,� wind� electricity�production�could�reach�still�higher:�5�200�TWh�in�2030�and�7�200�TWh�in�2050.�The�IEA�scenarios�are�generated�by� a� model� which� also� takes� into� account� competing�generation�technologies.

1.� “ACT”�Scenario,�in�which�CO2�emissions�stabilised�at�present�levels�by�2050,�and�measures�are�taken�with�a�cost�of�up�to�USD�50/tonne�CO2.2.� “BLUE”�Scenario,�in�which�present�CO2�emissions�halved�by�2050,�and�measures�are�taken�with�a�cost�of�up�to�200/tonne�CO2.�

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Figure 5. IEA ETP Scenarios: range of potential global wind electricity production (TWh)

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dWind�power�plants�–�like�wave,�tidal,�and�solar�plants�–�depend�on�a�variable�resource;�the�wind�does�not�blow�all�the�time�in�any�one�place.�Consequently,�the�capacity�factor3�of�wind�turbines�ranges�from�20%�to�40%,�lower�than�for�conventional�base-load�technologies.�Variability�is�commonly�perceived�to�be�challenging�at�high�shares,�but�there�is�no�intrinsic,�technical�ceiling�to�variable�renewables’�potential.�Nonetheless,�as�variable�electricity�inputs�to�the�system�increase,�so�the�flexibility�of�the�power�system�must�increase�also,�to�provide�for�times�when�wind�power�output�is�low.�In�electricity�system�terms,�flexible�power�plants�are�those�in�the�generation�portfolio�that�can�quickly�ramp�production�of�electricity�up�or�down�as�required.�But�the�system�can�also�respond�to�fluctuating�wind�power�output�through�the�use�of�stored�energy,�import�from�other�areas�and�through�enabling�demand�side�response.�A�number�of�operational�measures�exist�also,�particularly�relating�to�the�operation�of�transmission�capacity�and�electricity�markets.�

The�costs�relating�to�social�and�environmental�damage�caused�by�pollution�–�are�rarely�taken�into�account�in�assessment�of�the�costs�of�power�technologies.�Wind�power�plants�require�no�fossil�fuel�and�produce�little�environmental�pollution�during�their�manufacture,�operation�and�decommissioning.�CO2�emissions�for�wind�energy�are� small,� (around�10g�of�CO2�per�kWh).� If�external� costs�were� taken� into�account� in�normal� cost�assessments,�studies�suggest�that�wind�energy�would�already�be�competitive�with�most�power�technologies.�

Although�public�support�for�wind�power�is�often�high,�wind�turbines�may�be�considered�by�some�to�be�visually�intrusive.�Micro-siting�techniques�can�be�used�to�reduce�visual�impacts.�Issues�relating�to�aerodynamic�noise�are�largely�resolved�with�suitable�codes�relating�to�the�allowable�distance�from�residential�areas.�Following�concern�about�potential�avian,�bat�and�marine�impacts,�most�environmental�assessments�have�suggested�that�these�are�easily�minimised�through�careful�siting�of�turbines.�

Wind�turbines�extract�kinetic�energy�from�moving�air�flow�(wind)�and�convert�it�into�electricity�via�an�aerodynamic�rotor�connected�by�a�transmission�system�to�an�electric�generator.�Today’s�standard�turbine�has�three�blades�rotating�on�a�horizontal�axis,�upwind�of�the�tower,�with�a�synchronous�or�asynchronous�generator�connected�to�the�grid.�Two-blade,�and�direct-drive�(without�a�gearbox)�turbines�are�also�found.�

The�electricity�output�of�a�turbine�is�roughly�proportional�to�the�rotor�area,�so�fewer�larger�rotors�(on�taller�towers)�use�the�wind�resource�more�efficiently�than�more�numerous,�smaller�machines.�The�largest�wind�turbines�today�are�5-6�MW�units�with�a�rotor�diameter�of�up�to�126�metres.�Turbines�have�doubled�in�size�approximately�every�five�years,�but�a�slowdown�in�this�rate�is�likely�for�onshore�turbines,�due�to�transport,�weight�and�installation�constraints.

The�estimated�lifetime�of�an�individual�wind�turbine�is�20�to�25�years.�Life�spans�may�stretch�as�the�technology�continues�to�mature.�However,�due�to�the�youth�of�the�industry�and�the�re-powering�of�plants�with�the�latest�turbine� technology,� few�turbines�have�been�around� long�enough�to� test� this�assumption.�Due�to�extensive�testing� and� certification,� the� reliability� of� wind� turbines� –� the� proportion� of� the� time� they� are� technically�available�for�operation�–�is�around�99%.

�Technology� efficiency� gains� are� ongoing.� More� efficient� blades� and� drive� trains,� lighter� nacelles� (rotor� plus�generator)� and� fewer� components� mean� a� higher� electricity� output� per� unit� of� materials� required� in� the�manufacturing�process.�Such�efficiency�gains�will� to�some�extent�counter�rising�capital�costs�associated�with�higher�commodity�prices�(e.g.�copper�and�steel).

�To�a�large�extent,�the�move�offshore�can�be�said�to�be�driving�wind�energy�technology�development�generally.�Most�offshore�wind�at�present�is�installed�in�shallow�water.�Floating�turbines,�for�the�deep�offshore�environment,�are�at�the�demonstration�phase�with�a�2.3�MW�prototype�scheduled�to�be�deployed�in�2009�off�the�coast�of�Norway�in�the�North�Sea,�and�another�2.5�prototype�scheduled�to�be�installed�in�2009�off�the�Apulia�region�in�Italy.�

�Subjects�for�further�research,�specific�to�wind�energy�technology,� include�more�refined�resource�assessment;�materials�with�higher�strength�to�mass�ratios;�advanced�grid�integration�&�power�quality�and�control�technologies;�standardisation�and�certification;�development�of�low-wind�regime�turbines;� improved�forecasting;�increased�fatigue�resistance�of�major�components�such�as�gearboxes;�better�models�for�aerodynamics�and�aeroelasticity;�generators�based�on�superconductor�technology;�deep-offshore�foundations;�and�high-altitude�“kite”�concepts.�

3.� The�amount�of�output�a�power�plant�produces,�divided�by�the�amount�it�would�have�produced,�had�it�been�in�operation�24h,�365�days.

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