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Renewable Energy 36 (2011) 1887e1901

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Renewable Energy

journal homepage: www.elsevier .com/locate/renene

Review

The wind energy (r)evolution: A short review of a long history

John K. Kaldellis*, D. ZafirakisLab of Soft Energy Applications & Environmental Protection, TEI of Piraeus, Greece

a r t i c l e i n f o

Article history:Received 30 November 2010Accepted 6 January 2011Available online 4 February 2011

Keywords:Wind powerGlobal marketTechnological evolutionEconomics of windEnvironmental impactsFuture prospects

* Corresponding author. Lab of Soft Energy ApProtection, TEI of Piraeus, P.O. Box 41046, Athens 15381237; fax: þ30 210 5381467.

E-mail address: jkald@teipir.gr (J.K. Kaldellis).URL: http://www.sealab.gr/

0960-1481/$ e see front matter � 2011 Elsevier Ltd.doi:10.1016/j.renene.2011.01.002

a b s t r a c t

Although wind energy exploitation dates back five thousand years ago, contemporary societies are basedalmost exclusively on fossil fuels for covering their electrical energy needs. On the other hand, during thelast thirty years, security of energy supply and environmental issues have reheated the interest for windenergy applications. In this context, the present work traces the long and difficult steps of wind energydevelopment from the California era to the construction of huge offshore wind parks worldwide,highlighting the prospects and the main challenges of wind energy applications towards the target of1000 GW of wind power by 2030.

� 2011 Elsevier Ltd. All rights reserved.

1. Introduction

It was centuries ago when the technology of wind energy madeits first actual stepsealthough simpler wind devices date backthousandsof years agoewith the vertical axiswindmills foundat thePersian-Afghan borders around 200 BC and the horizontal-axiswindmills of the Netherlands and the Mediterranean followingmuch later (1300e1875 AD) [1e3]. Further evolution [4] andperfection of these systems (Fig.1)was performed in theUSAduringthe 19th century, i.e. when over 6 million of small machines wereused forwater pumping between 1850 and 1970. On the other hand,the first largewindmachine to generate electricity (a low speed andhigh-solidity wind turbine (WT) of 12 kW) was installed in Cleve-land,Ohio, in1888,whileduring the late stages ofWorldWar I, useof25 kW machines throughout Denmark was widespread. Furtherdevelopment of wind generators in the USA was inspired by thedesign of airplane propellers and monoplane wings, while subse-quent efforts in Denmark, France, Germany, and the UK (during theperiod between 1935 and 1970) showed that large-scale WTs couldwork. European developments continued after World War II. InDenmark, the Gedser mill 200 kW three-bladed upwind rotor WToperated successfully until the early 1960s [5], while in Germany,a series of advanced horizontal-axis designs were developed, with

plications & Environmental2201, Greece. Tel.: þ30 210

All rights reserved.

both of the aforementioned concepts dictating the future hori-zontal-axis design approaches later emerging in the 70s.

One of themost importantmilestones of thewind energy historycoincideswith theUSAgovernment involvement in thewindenergyresearch and development (R&D) after the oil crisis of 1973 [6e8].Following, in the years between 1973 and 1986, the commercialWTmarket evolved fromdomestic and agricultural (1e25 kW) to utilityinterconnected wind farm applications (50e600 kW). In thiscontext, the first large-scale wind energy penetration outbreak wasencountered in California [9], where over 16,000machines, rangingfrom 20 to 350 kW (a total of 1.7 GW), were installed between 1981and1990, as a resultof the incentives (such as the federal investmentand energy credits) given by the USA government. In northernEurope on the other hand,wind farm installations increased steadilythrough the 80s and the 90s, with the higher cost of electricity andthe excellent wind resources leading to the creation of a small butstable market. After 1990 most market activity shifted to Europe[10],with the last twentyyearsbringingwindenergyat the front lineof the global scene with major players from all world regions.

In this context, in the current work, a short review of thedevelopments noted in the field of wind energy at the global level isundertaken, with special emphasis given on the major fields ofglobal market facts, technology issues, economics, environmentalperformance, wind energy prospects and R&D. Highlights and someinsight for each of the fields are currently presented, while specialattention is given to the European achievements. More specifically,in the global market facts’ section, the time evolution of the globalwind power capacity and energy generation are presented alongwith the leading markets of today and the most important EU and

Fig. 1. From the early stages of wind energy exploitation to the outbreak of California (Source: [4]).

Time Evolution of Global and European Wind Power Capacity

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Fig. 2. Time evolution of global and European wind power capacity and wind energy generation (based on data from [11e14]).

Fig. 3. The gradual shift of wind energy generation between world regions (based on data from [14]).

Fig. 4. Country and regional distribution of wind power capacity installed in 2009(based on data from [13]).

J.K. Kaldellis, D. Zafirakis / Renewable Energy 36 (2011) 1887e1901 1889

world wind power facts. Following, in the technology issuessection, discussion concerning the upscale of machines, the maintechnological characteristics of contemporary WTs and issues suchas grid integration, efficiency of the machines and expansion of thesmall scale machines’ industry is undertaken.

In the economics section, issues such as the time evolution ofinvestment costs, the costs of both onshore and offshore applica-tions, the effect of financial support mechanisms, the employmentopportunities appearing due to the expansion of the wind energyindustry as well as a comparison with other power generationtechnologies are all presented. Next, in the environmental perfor-mance section, a short notice on the impacts of wind energy isprovided while attention is given to the externalities avoided andthe social acceptance levels of wind power. Finally, in the windenergy prospects and R&D part, a summary of future targets isprovided at both the market and the technological level.

2. Global market facts

According to the latest official data [11e14], the global windpower capacity was increased during 2009 by 37.4 GW (Fig. 2a),thus reaching a total of almost 158 GW on the basis of remarkabledevelopment rates exhibited for the past twenty years. Europe is atthe moment approaching, if not yet exceeded, 80 GW and is nowheading to offshore applications [15]. In fact, it is since the mid-90sthat the EU market corresponds to over 50% of the global installedcapacity, that is nowadays said to yield an overall of 260TWh/year.In this context, although the EU held only 20% of the word windenergy generation in the early 90s (Fig. 2b), production of Europeanwind parks managed to even reach 70% in the years after 2000,with a production of 100TWh/year already achieved by the end of2007.

Fig. 5. Time evolution of wind power capacity in major EU markets (based on data from [11]).

J.K. Kaldellis, D. Zafirakis / Renewable Energy 36 (2011) 1887e19011890

However, restart of the USAmarket [16] and development of thewind energy industry in China [17] have considerably reduced theaforementioned numbers during the recent years to a current 60%.As a result, the aggregate share of North America and Asia & Oce-ania in 2007 corresponded to an approximate 38% of the worldwind energy production (Fig. 3). In the meantime, 80% of wind

Fig. 6. Time evolution of annual and cumulative power capacity insta

energy production attributed to North America in the early 90’sshrank to 20% within a decade’s time, while for the region of Asia &Oceania considerable contribution may be encountered since 1995.

Concerning the present status of wind power capacity (Fig. 4a),the USA managed during 2009 to add a new 40% over its cumula-tive capacity. At the same time the Chinese achieved to install

llations in the EU by technology type (based on data from [11]).

Fig. 7. Wind energy contribution to the gross electricity generation of EU countries (based on data from [19]).

J.K. Kaldellis, D. Zafirakis / Renewable Energy 36 (2011) 1887e1901 1891

almost 14 GW, i.e. 20% and 40% of the EU and the USA cumulativecapacity respectively, which leads to an aggregate (USA and China)of 62% of the 2009 capacity. As a result, China has reached thesecond place of the world ranking table together with the long-term leader of the EU, i.e. Germany. Besides, at the regional level(Fig. 4b), Asia has managed to marginally exceed the North Amer-icans in terms of cumulative capacity, while the EU is still the worldleader with almost 50%.

At the same time, at the European level (Fig. 5) Germany(25.8 GW) and Spain (19.1 GW) are now followed by Italy(4850MW), France (4492MW),UK (4051MW), Portugal (3535MW)and Denmark (3465), with the latter presenting a long-term stag-nation that calls for the improvement of the local legislation [18]although considerable exploitation of the local wind potential hasalready been achieved. On the other hand, France and Portugalpresent remarkable developing rates since 2000, while for Italy andNetherlands the local wind energy market encountered an earlierstart (i.e. since 1990)with analogous results only for the case of Italy.

Further, what is also interesting to see is the time evolution ofgenerating capacity of all technologies in the EU during the timefrom 1995 to 2009. As one may see in Fig. 6a, during the last twoyears, newwind power capacity exceeds any other technology withmore than 10 GW of wind power installed in 2009. Additionally, in

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terms of cumulative installations (Fig. 6b), European wind farmsexceed oil-based generation by 20 GW and are down by 50 GWwhen compared to nuclear power. In fact, the developing rate ofwind energy capacity is only comparable to the respective ofnatural gas installations, with the remarkable growth of photo-voltaic plants also designating the shift attempted in the EU toclean power generation technologies.

In this context, contribution shares of wind energy productionto the gross electricity generation of certain EU countries alreadyexceed 10% (e.g. Denmark, Portugal and Spain) [19], while for theDanish approximately 20% should be considered, with the respec-tive EU average kept at 4.1% (Fig. 7). Nevertheless, shift to offshoreattempted by many European countries [20,21] (1.5 GW already inoperation in Denmark and the UK), with short-term plans of 33 GWby 2015 mainly supported by Germany and UK (Fig. 8), shall furtherincrease the contribution shares of EU wind farms.

Summarizing, according to the latest official data, the EU stillremains the world leader, although the USA made a considerablecome-back with over 10 GW installed in 2009. Meanwhile, Chinapersists on its outstanding growth rates, each year doubling itscumulative capacity, and seems ready toovertake thefirst place in theworld ranking table. On top of these, India following a steady growthrate [22] is the China’s most important ally, addingmore than 10 GW

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Fig. 9. Time evolution of size scale-up (Source: [30]) and the largest commercial wind turbines of nowadays.

J.K. Kaldellis, D. Zafirakis / Renewable Energy 36 (2011) 1887e19011892

for the Asian region. Besides, after a long stagnating period Australiamanaged to install almost1GWduring2008e09 [23], thus increasingthe Pacific capacityatmore than2GW.On the otherhand, in the LatinAmerica, noteworthy is only the development encountered in Brazil,Chile, Mexico and Costa Rica, summing up however to a total of only1GW[24]. Finally, Egypt,Morocco andTunisia [25] are the only activeAfricancountries (more than0.7GW),with Iranbeing theonlyMiddleEast country found to considerably exploit its local wind potential(w100 MW) [26].

Time Evolution of Pitch & Stall Regulated Machines' Shares

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Fig. 10. Time evolution of the pitch to stall ratio (Source: [30]).

3. Technology issues

The development of contemporary WTs in the course of time[27e29]may be reflected by the gradual upscale of machines, basedon the rationale for better land exploitation, presence of scaleeconomies, reduced maintenance and operation (M&O) require-ments and past funding development programs [1] pushingtowards the development of big-scalemachines. On the other hand,a stabilizing trend is noted during the recent years that has put anend to the exponential increase of the rotor diameter met in thefirst two decades (Fig. 9a) [30]. As a result, WTs of nowadays aremainly in the order of 2e3MW, although larger scale machines thatare already commercial do exist (Fig. 9b). Contrariwise, the shift tooffshore applications calls for multi-MW solutionsealready offered

by some of themanufacturers (even at the levels of 7MW)e , whiledesigns of machines that will exceed the nominal power of 10 MWare already underway.

Meanwhile, during the evolution of technology, multi-bladedturbines are found to be constrained to water pumping applica-tions. On the other hand, among the types of electricity generation,the three-bladed WTs prevailed over the respective single- and

Time Evolution of the Mean Annual CF on the EU & the Global Level

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Fig. 11. Time evolution of the mean annual CF for the world and the EU wind energy applications (based on data from [14]).

Fig. 12. Range of applications for small scale wind turbines (based on data from [45]).

J.K. Kaldellis, D. Zafirakis / Renewable Energy 36 (2011) 1887e1901 1893

two-bladed machines that appeared to be both less efficient andless accepted concerning their visual impact. Similarly, the inherentlower efficiency and the cost-ineffectiveness were themain reasonsfor the vertical axis WTs (VAWTs) actually never becoming main-stream, although a new market seems to emerge for the smallestscale VAWTs in building applications [31,32].

Concerning power regulation, pitch control found itself to begradually more adaptable to new machines, with the ratio of pitchto stall machines increasing from 1:1 (1997) to 4:1 in 2006 (Fig. 10).Following, introduction of the variable speed concept, althoughinducing extra costs and additional losses in the variable speeddrive, allowed for increased energy capture below the rated powerarea and relief of loads, enhancement of the pitch and smoothpower output above the rated power area.

In this context, a long term increase of the mean annual capacityfactor (CF)met at both theEUand theglobal level (Fig.11a), exceeding20% in 2007, reflects the effect of technological improvements, thisalso including the gradual establishment of pitch control machines.More specifically, although goodwind potential areas are nowharderto find, exploitation of wind energy per kW has increased due toimproved efficiency of contemporary turbines, sophisticated assess-mentof the localwindpotential, considerable reductionof downtimeperiods, upgrade of networks and operation of offshore applications.In this context, of special interest are countries such as Germany and

Denmarkwhere although local windpotential keeps CFs atmoderatevalues, diffusion of wind parks is remarkable, and countries such asIreland, Spain and Turkey where the long-term CF is found to exceed25% (Fig. 11b).

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J.K. Kaldellis, D. Zafirakis / Renewable Energy 36 (2011) 1887e19011894

Another important technology issue is grid integration, withlarge-scale penetration of onshore and offshore wind parks chal-lenging all parties involved andwith system issues including powerquality, voltage management, grid stability, grid adequacy, controlof emissions and efficiency reduction of other generating plants[33e35]. As a result, in order to confront future wind power gridintegration, themain directions include design and operation of thepower system with the introduction of demand side managementtechniques and energy storage [36e38], grid infrastructure issuesmeaning reinforcement and upgrade of networks, grid connectionof wind power with grid codes issued, market operation with theintroduction of more flexible mechanisms and other issues such asinstitutional [39].

Finally, of special interest is as already implied, the industry ofsmall scale WTs [40e42], satisfying a range of applications [43e45](Fig. 12). Such applications may concern both on-grid and off-gridconcepts like building integration, mini wind farms and singleturbine installations for the first category, and wind-battery alongwith wind-based hybrid systems for the second [46]. Besides, theinterest lately exhibited may also be illustrated by the recentdevelopments in the specific field, these including active pitchcontrols for high wind speeds, vibration isolators to dampen sound,advanced blade design, self-protection mechanisms for extremewinds, dual mode models (both on- and off-grid), software devel-opment, inverters fitted into the nacelle, attempts to make small

WTsmore aesthetically attractive and integration of small WTs intoseveral structures.

4. Economics of wind energy

Among the main trends dominating the market of wind energyduring the years, one may note the size increase of contemporaryWTs, the efficiency improvement and the long-term reduction ofthe specific investment cost per kW (turnkey cost) of installed windpower capacity [47]. Concerning the latter, although starting froma remarkable 3500€/kW during the mid-eighties, it has during thelast years stabilized in the order of 1200€/kW, i.e. between 1000€/kW and 1400€/kW [48], depending also on the area of study(Fig. 13a and b).

In this context, some rough numbers may also be given in termsof investment cost breakdown, noting also the difference betweenonshore and offshore applications. More specifically, the turbinecomponent being critical in onshore projects (w930€/kW)(Fig.14a) drops to a typical 48% in offshore plants (Fig.15a) while onthe other hand, foundation requirements increase by more thanfour times and grid connection in offshore is increased by morethan 150€/kW. Overall, the total specific investment cost of offshoreapplications is found to be higher by more than 40% for most of theplants in operation and may increase to even exceed 3000€/kW forinstallations that are under construction [49,50]. Besides, based on

Fig. 14. Breakdown of the investment (based on data from [48]) and the maintenance and operation cost (based on data from [52]) of onshore wind parks.

J.K. Kaldellis, D. Zafirakis / Renewable Energy 36 (2011) 1887e1901 1895

the experience of in operation offshore parks employment of moreturbines implies relatively lower turnkey costs (Fig. 15b). Any casegiven, M&O costs (Fig. 14b) including insurance, regular mainte-nance, repairs, spare parts, administration, land rent and others[51e53], are also considerable for wind power installations,although the introduction of more efficient machines and thereduction of downtime hours constantly decrease the M&Orequirements which are now in the order of 1.2e1.5c€/kWh.

On the other hand however, the wind energy production cost isfound to be comparable with the respective of conventional fossil-fueled generation methods [54], even without internalizing theexternalities. As a result, clear advantage of wind power in theeconomic field as well becomes evident (Fig. 16), with estimationsconcerning the near future electricity generation cost of onshoreand offshore wind parks supporting values between 50€/MWh and80€/MWh and between 75€/MWh and 120€/MWh respectively[55e57].

Following, State support, as already seen in the introductionsection, led to the outbreak of California. In this context, of analo-gous importance for the remarkable growth of the wind energymarket has been the implementation of various support mecha-nisms [58] including price- and quantity-driven instruments suchas feed-in-tariffs, investment and production tax incentives for thefirst and quota along with tradable green certificates and tenderingsystems for the second. At this point, one should underline theeffectiveness of most of these measures and especially the feed-in-tariff mechanism [59], which since being adopted by themajority ofleading countries worldwide (Germany, USA, China, Denmark,

Spain, India, etc.) [60] led to the remarkable growth of wind energygeneration (see also Fig. 17aec).

Finally, one should also emphasize on the employment oppor-tunities [61] offered by the expansion of the wind energy market ata global level. Somewhat 100,000 plus 50,000 is the number ofpeople employed directly and indirectly in the wind energy field ofEurope, while another 85,000 correspond to the 100manufacturingplants operating in the USA. These include employment posts inmanufacturing companies, in promotion, utilities, engineering andR&D (direct employment) or employment in companies providingservices or producing components for WTs (indirect relation). Notethat according to rough estimations [62], among the leader coun-tries on the basis of the people employed per MW installed ratio(Fig. 18), Denmark, Belgium and Finland employ more than 7persons while in terms of absolute numbers Germany currentlyemploys 38,000 people [63].

5. Environmental performance of wind energy

Although suggesting an a-priori clean energy source, windpower also comes with certain environmental impacts [64] such asthe visual [65] and the noise impact [66], the land use, the birdfatalities [67], the electromagnetic interference, the impacts on fishand marine mammals and the embodied energy plus LC emissionscommon in every power generation technology. Many of theseimpacts are nowadays perceived by many as “myths” [68,69] (seealso Fig. 19a), while others still lie on the subjectivity of oneself.What is documented however [70e74] is that WTs require primary

Fig. 15. Typical investment cost breakdown and variation of offshore wind parks’ turnkey cost (based on data from [48]).

J.K. Kaldellis, D. Zafirakis / Renewable Energy 36 (2011) 1887e19011896

LC embodied energy amounts in the order of only 1e3MWh/kW(that usually implies energy payback periods of months), with thestage of manufacturing being the most demanding (Fig. 19b).

Furthermore, if also considering externalities [75e77], a clearadvantage may be recorded for wind power installations in

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comparison with conventional power plants (Fig. 20a). In fact,according to estimations [78], realization of the high expectationsset by the EU for 2020 implies avoidance of externalities in theamount of almost 40 billion €/year, with the distribution of costsavings per country given in Fig. 20b.

uction Cost: 2020 Estimation

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Fig. 17. The feed-in-tariff effect for representative big and small scale wind energy producers (based on data from [14,60]).

J.K. Kaldellis, D. Zafirakis / Renewable Energy 36 (2011) 1887e1901 1897

Besides that, environmental performance of wind energyperceived by the majority of people (over 70% in favor) [79,80] andtransformed in to widespread social support (only solar energyseems to be more socially accepted) further boosts wind energydevelopments (Fig. 21). On the other hand, one of the challengesthat wind energy is faced with during the recent years is theparadox of increased social support being obscured by real-life

NIMBY attitudes [81e83], especially since availability of good sitesis becoming increasingly rare.

6. Wind energy prospects and R&D

Up till now, the policy framework of the EU was of criticalimportance for the promotion of RES and wind energy in particular.

Direct Employment in Wind Energy Companies in Europan Countries (2006-2007)

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Fig. 18. Employment opportunities in the wind energy sector by EU country (based on data from [11,62]).

J.K. Kaldellis, D. Zafirakis / Renewable Energy 36 (2011) 1887e19011898

In this context, new targets set call for 20% coverage of the finalenergy consumption by RES by 2020, while in terms of electricityconsumption, wind energy is expected to contribute by a 14%e17%.In fact, two scenarios have been elaborated on the basis of the 2020target [84], i.e:

1. The “baseline” scenario that assumes a total installed windpower capacity of 230 GW (Fig. 22a), producing 580TWh ofelectricity and increasing the electricity demand coverage bywind from 4.1% in 2008 to 14.2% in 2020.

2. The “high” scenario where the total installed wind powercapacity is assumed to reach 265 GW by 2020, producing

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Fig. 19. Insight on the environmental impacts of wind energy; bird fatalities and lifecycle energy requirements (based on data from [69,72]).

681TWh of electricity and increasing the electricity demandcoverage from 4.1% in 2008 to 16.7% in 2020.

Moreover, according to long-term plans [84], 400 GW (250 GWonshore and 150 GW offshore, see also Fig. 22b) of wind power inthe EU and 20% of the USA electricity demand covered by wind by2030 [85], along with China requesting 150 GW installed by 2020[86], set the scenery of wind power prospects and challenge thetarget of 1000 GWglobally by 2030. In this context one should alsonote that:

� In India, existence of a domestic industry and 65e70 GW ofassessed wind potential along with 10% of RES capacity and4e5% of RES energy shares by 2012 are the main drivers ofwind energy with estimations calling for 2 GW/year in thefollowing period.

Fig. 20. Insight on the environmental benefits of wind energy; life cycle greenhousegas emissions (based on data from [77]) and avoidance of external costs (Source: [78]).

Social Acceptance of Wind Energy in Comparison with Other Technologies

0%

20%

40%

60%

80%

100%

Sola

rEn

ergy

Win

dEn

ergy

Hyd

ropo

wer

Oce

anEn

ergy

Biom

ass

Ener

gy Gas O

il

Coa

l

Nuc

lear

Don’t KnowOpposedBalanced ViewsIn favour

Fig. 21. Social acceptance of various electrical power technologies (Source: [80]).

J.K. Kaldellis, D. Zafirakis / Renewable Energy 36 (2011) 1887e1901 1899

� Wind potential for onshore wind energy capacity in Brazil hasbeen assessed at 143 GW (at 50 m high).

� At the end of 2008, Australia’s expanded the country RES targetto 20% by 2020.

� South Africans turn to wind, since the bulk part of the 100TWhproduced by RES up to 2025 is to be assigned to wind power.

Finally, what is important to consider is that for the aforemen-tioned goals to be realized, R&D targets set must be put forward bythewind energy industry [87], with themain directions and actionsto be taken including the following:

� New wind turbines need to reduce their overall costsB Large scale turbines of 10e20 MW going offshore (R&Dprogrammes for prototypes already initiated)

B Improved design and reliability of components (Testingfacilities to assess efficiency and reliability of wind turbines)

Fig. 22. Future targets of wind energy in the EU (Source: [84]).

B Development of innovative logistics (Cross industrialprogrammes)

� Deeper waters and larger turbines for offshoreB Development and industrialization of support structures forsea installations, both fixed and floating (Structure conceptsto be developed and tested at different depths and underdifferent conditions)

� Achieve grid integration for even greater wind energypenetrationB Introduction of large-scale energy storage systems and highvoltage alternative and direct current (HVAC-HVDC) inter-connections (Offshore farms connected with more than onegrid, long distance HVDC, R&D of energy storage systems)

� Resource assessment and spatial planningB More sophisticated assessment of wind resources (Highquality measurements and databases for wind data as wellas short-termwind speed forecasting with the use of neuralnetworks)

B Spatial planning through social and environmental consider-ations (Development of planning tools and methodologies).

7. Conclusions

A review of the wind energy history undertaken in the currentwork emphasizes on the main issues of global market facts, tech-nology, economics, environmental performance, prospects andR&D of wind power, providing some insight and presenting thehighlights for each of the fields. From the review undertaken, thedynamics of wind power at the global energy scene during the lastthirty years is illustrated, while according to the targets set, theperspective of exceeding 1 TWof wind power installations by 2030seems feasible, especially if considering the challenges introducedby the need of each country to safeguard security of supply andpromote clean power technologies.

Besides that, although the leading role of the EU throughout theperiod of wind energy development has been designated, thereturn of the USA and the tremendous growth of the wind energyindustry in China are also reflected. On top of that, of specialinterest is also the gradual adoption of wind energy by severalcountries of the developing world, this clearly demonstrating boththe catholic character of wind power and its ability to largelysubstitute fossil-fueled power generation in the years to come.

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Wind Energy Status: End of 2008

• 2008 a Big Year for Wind Energy Development (especially in the US and China)1( p y )

1Wiser, R and Bolinger, M. (2008). Annual Report on US Wind Power: Installation, Cost, and Performance Trends. US Department of Energy – Energy Efficiency and Renewable Energy [USDOE – EERE].

© 2007 ESS, Engineering Systems Division, Massachusetts Institute of Technology

Department of Energy Energy Efficiency and Renewable Energy [USDOE EERE].

Logan, J. and Kaplan, S. M. (2008). Wind Power in the United States: Technology, Economic, and Policy Issues. Congressional Research Service [CRS].

http://www.mitenergyclub.org/assets/2009/3/6/Wind-online.pdf

Brief History of Wind Energy

• Highly Standardized Technical System:– 3-blade Upwind Horizontal-Axis with some variation in design of

a planetary gearbox and induction, increasingly in doubly-fed p y g , g y yconfiguration, generator on a monopole tower

• Progressive Increase in Size from 1970s to Today

© 2007 ESS, Engineering Systems Division, Massachusetts Institute of TechnologyGraphic courtesy of Steve Connors, MIT Energy Initiative