Overview of worldwide wind generation

Renewable Energy, %'ol.5,Part I, pp. 542-550, 1994 Elsevier Science Lid Printed in Gre~ Britain

Pergamon

0960-1481/94 $7.00+0.00

OVERVIEW OF WORLDWIDE WIND GENERATION Paul Gipe Paul Gipe & Associates, P.O. Box 277, Tehachapi, CA 93581, USA

Portions of this paper have appeared previously in IndependentEnergyMagazine. Data herein has been compiled from numerous sources including Finn Godtfredsen, Risoe National Laboratory; Birger Madsen, BTM Consult; Attain Keuper, DEW]; Jos Buerskens, ECN; and Andrew Garrad, Garrad Hassan. ABSTRACT An overview of activities in the United States and Europe including a look at installed capacity, generation, specific yield, price, and environmental impact. The 1992-1993 period saw the wind industry reach several significant milestones. Worldwide wind generation exceeded 4 TWh during 1992 for the first time and surpassed 5 TWh in 1993. See Table 1. By 1995 total generation will approach 7 TWh. During 1993 Europe's total installed wind generating capacity exceeded 1,000 MW for the first time: the Netherlands and the United Kingdom both topped 100 MW, and Germany exceeded 300 MW. Table

1992 1993 1994 1995

i. W o r l d W i n d E n e r g y North America Europe MW TWh MW 1,700 1,700 1,700 1,750

2.8 2.9 3.1 31.0

900 1,270 1,550 1,950

542

Development

TWh 1.5 2.3 2.8 3.6

World MW 2,650 3,050 3,350 3,800

TWh 4.4 5.4 6.1 6.8

543 Europe's rapid growth pushed wind energy beyond another milestone in 1993 when sales of wind turbines and wind-generated electricity exceeded $1 billion (thousand million), an increase of nearly $200 million over 1992 sales. 1993 turnover included $600 million in project development, and sales of wind-generated electricity worth an estimated $450 million. The industry has not seen turnover in excess of $1 billion (thousand million) since 1985 at the height of California's wind rush. At that time, revenues were due almost entirely to sales of new wind turbines. Europe's feverish development of wind energy shows little sign of abating. Altogether, Europe installed more than 350 MW of capacity in 1993, up from nearly 250 MW in 1992. European development far outpaced the 15 MW installed in North America during 1992, and the 25 MW installed in 1993. By the end of 1993 Europeans will be operating more than 1,200 MW of wind capacity, and if the present pace continues, will outstrip the United States in total installed capacity by the end of 1995. Denmark currently accounts for half the capacity installed in Europe and continues to add 40-50 MW per year in one of Europe's most stable domestic markets. Germany accounts for another fifth, with new capacity additions in Germany now rivaling that of any other country in the world, including Denmark. See Figure 1. EUROPE TO SURPASS NORTH AMERICA IN 1995

North America's share of world wind generation fell to 53% in 1992, the lowest level in a decade. As recently as 1990, California alone accounted for 78% of worldwide wind generation. The slide in America's leading role in the world's wind industry began with a boom in European wind development while growth stagnated in the United States. If present trends continue, European generation will exceed that of North America by the end of 1995. See Figure 2. TEHACHAPI LEADS WORLD IN GENERATION The ranking of the world's top wind producing regions shifted significantly in 1993 reflecting Europe's growing role. As in 1992 the Tehachapi-Mojave wind resource area dominated worldwide production with 1.3 TWh of generation according to data from Southern California Edison Co. The Altamont Pass fell from its second-place perch to third place with 827 million kWh according to data from Pacific Gas & Electric Co. For the first time Denmark surpassed Altamont's generation by producing 1.05 TWh during 1993 says Denmark's Risoe national laboratory. And in another surprising development Germany pushed Palm Springs from its long-held third place position. Germany generated 673 million kWh in 1992 according to the German Wind Energy Institute, edging out Palm Springs' record 650 million kWh production. Britain followed Palm Springs with 211 million kWh. The Netherlands produced 125 million kWh. Data from California's utilities is preliminary. The California Energy Commission is expected to issue a final report on the state's 1993 wind generation in 1995. Unlike California, which reports actual energy sold to electric utilities from the state's wind power plants, generation in Denmark, and Germany are estimates based on the performance of representative turbines.

544 CURRENT ACrlVITY IN NORTH AMERICA During 1993 and early 1994, wind developers will erect 100 MW of capacity in North America: 25 MW in California, 18 MW in Alberta, 26 MW in Iowa, and 25 MW in Minnesota. Between 1995 and 1997, wind companies will install 300-350 MW in North America outside of California: 10 MW in Saskatchewan, 5 MW in Quebec, 100 MW in Washington, 60 MW in Wyoming, 50 MW or more in Texas, 75 MW in Minnesota, 10 MW in Wisconsin, and 65 MW in Maine. More than 200 MW could be added in California during this period but the picture remains cloudy because of regulatory uncertainty. Several firms are also active in Mexico. PROJECT PRICE DECLINES The market price paid for wind power plants has decreased dramatically since the first projects were built in California. However, the price of installed wind plants bears little resemblance to the much-touted cost of $1,000/kW of installed capacity with the exception of projects installed by Danish utilities and two projects complted in the United States this year.(1) See Figure 4. California projects reached a low of $1,250/kW in 1987. Subsequent projects were more costly because of the construction of a 45 mile high voltage transmission line.(2) These projects also included the developer's up front profit. Similarly, non-utility projects in England and Wales are costing more than $2,000/kW, among the most costly in Europe. Only Danish utility projects are showing a steady decline in installed costs, resulting from competitive procurement and low-interest financing. Danish utilities also take their profit out over the life of the project. In early 1994 U.S. Windpower completed construction on projects in California for the Sacramento Municipal Utility Distrit and in Minnesota for Northern States Power at $1,100/kW. SPECIFIC YIELD STILL INCREASING According to data from the California Energy Commission's Performance Reporting System, BTM Consult and Denmark's Risoe National Laboratory, the specific yield of individual wind turbines and wind power plants in California and Denmark have increased steadily since the early 1980s. See Figure 5. The exception is average yield in California wind plants and the yield of post1985 wind plants in California. The specific yield in California reached a peak in 1990 and has declined since. There are several possible explanations. Wind speeds have suffered during the late 1980s and early 1990s due to El Nino and from a volcanic eruption in the Philippines. The turbine stock may also be showing signs of age. Of note is the steady improvement in specific yield with succeeding design iterations, both in California and Denmark. Medium-sized wind turbines have steadily increased in size since introduction of the 55 kW Danish wind turbine (15-16 meters in diameter) in the early 1980s. Machine designs have increased in modest increments from 55 kW to 100 kW, to 200 kW, to 400 kW, and to today's state-of-the-art machines in the 500 kW range. See Figure 6. Though the specific yield (the kWh generated per year per square meter of rotor area) increases for each Danish wind turbine model in succeeding years, the most dramatic improvement is from one wind turbine model to the next.(3) The average specific yield of the 450 kW model of 850-900

545 kWh/m2/y is twice that of the early 55 kW model. Even the later 55 kW model shows a marked performance improvement over the previous version. The same results can be seen in California, when the specific yield of all wind turbines is contrasted with those installed since 1985. The improved performance is attributable to greater reliability, improved airfoils, and taller towers. Next to greater reliability, the most important contributor to higher specific yields is taller towers. Tower heights have nearly doubled from 18 meters to 35 meters since the early 1980s. Doubling the tower height alone will increase the power available more than 30%. For sites yieldin~ 600 kWh/m2hj the taller towers will add nearly 200 kWh/m2/y, bringing total yield to 800 kWh/m2/y at a good site. At exceptional sites, such as on the west coast of the Jutland peninsula (7 m/s), or atop Whitewater Hill near Palm Springs, contemporary turbines should yield 1,000-1,250 kWh/m2/y. See Figure 7. San Gorgonio Farms, which operates the world's most productive wind plant, consistently produces within this range. There are numerous sites in Northern Europe where specific yields exceed 1,000 kWh/m2/y, including coastal Germany, and the Netherlands. REPOWERING CALIFORNIA As mentioned, California's turbine stock is comprised largely of early, less cost-effective designs. Some of the turbines are ten years old. The aging stock may have partially contributed to the decline of average specific yield during 1991 and 1992. Nearly 3,100 turbines comprising 230 MW of capacity are of first generation design. See Table 2. These turbines are costly to maintain, often sited poorly, installed on short towers, and unreliable. Many of them are unsalvageable. The bulk of the capacity in the state is provided by second generation designs, including 100-150 kW Danish machines and U.S. Windpower's 56-100. There are 1,300 state-of-the-art turbines representing 300 MW of capacity. T a b l e 2. R e p o w e r i n g Current Fleet

california Units

Junk Second Generation State-of-the Art

Wind Plants MW

3078 12509 1286

233 1211 317

16873

1761

0 0 7012

0 0 1761

TWh/y

2.8

After Repowering Junk Second Generation State-of-the Art

3.6

546 The American Wind Energy Association's west coast office, in a study for the California Energy Commission, estimated that repowering California's wind plants by replacing first and second generation designs with contemporary machines could lower operations and maintenance costs, reduce the density of turbines on the landscape by more than 50%, and increase annual generation by 30% to 3.6 TWh. The AWEA study concluded that repowering with modern turbines would make the California industry more competitive with other resources, preserve jobs, and reduce the industry's aesthetic impact, thus improving its public acceptance. The AWEA study took the first-ever truly comprehensive employment survey of California wind plant operators and their service providers. See Table 3. AWEA found that there are 1,250 people working directly with wind energy in California for 460 jobs/TWh/y. This compares well with estimates by BTM Consult of the number of people employed in Denmark. BTM Consult estimates there are nearly 600 manufacturing jobs in Denmark for 6 jobs/MW of manufacturing and another 400 people are employed in the service sector for 440 jobs/TWh.(4) Table

3. Wind Industry Jobs in California California Denmark Jobs Jobs/TWh Jobs

Manufacturing O&M and support Indirect

0 1250 4350

0 460 1500

600 400 ?

and Denmark Jobs/TWh (600/100 MW) 440 ?

ENVIRONMENTAL IMPACT During 1992 and 1993, the wind industry has made considerable strides towards quieting wind turbine noise. Bonus, Vestas, and WEG have demonstrated that noise emissions can be reduced significantly by focusing attention on tip design, trailing edge thickness, drive-train compliance, noise insulation, and nacelle isolation. Keeping tip speeds to 60 m/s or less is an important means for reducing aerodynamic noise. These wind turbines are 5-7 dB(A) quieter in their noise emissions than competitive machines designed during the mid-1980s that operate at higher tip speeds. Despite the industry's best efforts, wind turbines will introduce noise into many rural environments previously noted for their solitude. This intrusion creates concern, fear, and objections until the public has had ample time to become familiar with the technology. See Figure 8. It has taken the community of Tehachapi a decade to become comfortable with its wind industry. It was Tehachapi's experience that prior to development there was broad support of wind energy in the abstract. Yet when wind projects were first developed, there was a loud outcry and consternation that the wind turbines would devour the small town of 5,000. Several years after installation qualitative acceptance has resumed to near pre-project levels. Energy Connection, a Dutch wind developer, has observed the same effect in the Netherlands.(5)

547 Wind energy's most significant impact remains its use of the visual amenity. Wind energy will only reach its potential when the industry addresses aesthetic impact. However, public opinion surveys and architectural studies in the United States and Europe can provide guidelines for minimizing wind's aesthetic impact. The single most important measure is aesthetic uniformity. All wind turbines and towers within a wind plant must look similar. They need not be identical, but they must appear similar. This is less of a problem in Europe than in the United States. In California, for example, it is common for a developer to install a wind plant containing hundreds of different wind turbines in a seemingly incoherent mix. To maintain visual uniformity within a wind plant that comprises one visual unit, all wind turbines must spin in the same direction, have the same number of blades, use the same tower, and use the same color scheme. If another wind turbine and tower combination will be installed nearby, there must be sufficient visual separation to make the projects distinct from one another. Turbines should all be of the same height unless they are part of a coherent wind wall, with alternating groups of turbines on towers of different heights. If turbines are of different heights, all towers should appear similar if not identical. This provision alone would eliminate much of the jumble and visual clutter typical of many California wind plants. Further, developers must minimize roads or eliminate them altogether. This prevents unsightly cut and fill slopes in steep terrain, and minimizes the amount of land used by the wind plant. If two-bladed turbines are used, all turbines must park their rotors in the same position. This "synchronized stop" provides visual balance for what many consider an ungainly design choice. Three-bladed rotors, xvhich appear more visually symmetrical to observers than two-bladed rotors, can be parked in any position. No wind turbine should ever go out undressed: none should operate without a nacelle cover. Nose cones and nacelle covers serve a valuable purpose. They smooth the angular lines of the drive train and aid in making the nacelle a part of a visual whole with the tower. Nacelle covers should be replaced immediately if they blow off. Designers should strive toward visual unity between rotor, nacelle, and tower. A wind turbine need not be a box on a stick~ Lattice towers need not appear cluttered with cross braces and angular lines. Lattice towers can be designed with graceful curves and a sparing use of cross braces. The industry must address the question of aesthetics or the publics' general support will be lost. Consider the reversal of public attitudes towards nuclear power during the 1960s. Wind is currently a preferred technology even when accounting for wind's aesthetic impact.(6) See Figure 9. This support is tenuous and can be squandered by inappropriate development.

548 COMMUNITY ASSIMILATION Community acceptance of wind energy can be aided by addressing community concerns, by providing information about the operation of nearby wind turbines and the companies involved, and by low-key, long-term participation of the wind industry in community events. In Tehachapi the Kern Wind Energy Association is the focal point for inquiries about wind energy and the local wind industry. KWEA and member companies offer speakers for local service clubs, participate in local festivals, and provide simple, inexpensive brochures and postcards to local merchants for distribution to tourists and residents alike. KWEA also operates a low-power radio transmitter for broadcasting information about the wind industry to motorists on Highway 58, a major artery crossing the Tehachapi Mountains. More recently KWEA has sponsored a new local event: the Tehachapi Wind Fair. The success of this weekend event, which drew 14,000 the first year and 12,000 the next, confirms that the Tehachapi wind industry has become an accepted part of the community. CONCLUSION Wind generation now meets 1% of California's electrical supply and nearly 4% of Denmark's electrical consumption. Worldwide wind generation will exceed 6 TWh in 1995, when Europe will surpass North America in total generation and installed capacity. At good sites, medium-sized wind turbines today should produce specific yields in excess of 800 kWh/m2/y. Wind energy can become an accepted part of the community if designers and developers keep community interests in mind, especially those of wind's aesthetic impact on the landscape. REFERENCES

1. Jens Vesterdal, ELSAM, "Experience with Wind Farms in Denmark," European Wind Energy Association special topic conference on "The Potential of Wind Farms," Herning, Denmark, September 1992. 2. California Energy Commission, "Wind Project Performance Reporting System," Sacramento, Calif., 1985-1991. 3. Finn Godtfredsen, Risoe National Laboratory, "Wind Energy in Denmark: Development in Wind Turbine Technology and Economics Since 1980," paper presented at Windpower 93, American Wind Energy Association annual conference, San Francisco, Calif., July 1993. 4. BTM Consult, personal communication, April 1993. 5. C. Westra and L. Arkesteijn, "Physical Planning, Incentives, and Constraints in Denmark, Germany, and the Netherlands," European Wind Energy Association special topic conference on "The Potential of Wind Farms," Herning, Denmark, September 1992. 6. Robert Thayer and Heather Hansen, "Consumer Attitude and Choice in Local Energy Development," Center for Design Research, Department of Environmental Design, University of California, Davis, Calif., May 1989.

549

WIND POWER PLANT PRICE U.S. AND DENMARK

1994 EUROPEAN WIND CAPACITY 4000

I I I ~ S 1200 ~ 1994 1480

1992 $ / k W

19951860Id

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Paul Glpe & Amlo0., 1994

Peu~olp= •/~l.=e,

Figure 4. Market price of installed capacity. Figure 1. Installed capacity in Western Europe by year end 1993. World Wind Generatk)n Growing European Influence

Specific Yield in California and D e n m a r k 1200

kWh/m2/y

TeraWatt houri= (Billion k W h )

Ssn Gorgonlo Farms

k~2~:~ ~ _ _ _ ~ _ ~ ~

lOOO m E~e

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L=t= 6e kW ell A~g I 85

i 86 87 Year

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Figure 5. Average actual specific yield. Figure 2. North American and European wind generation.

MAJOR CENTERS OF WIND GENERATION 1993 GENERATION

r..~=..,===

I I

D. . . . . k Altllmont,

CA

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i i J,,,oo IJ=~

COMPARATIVE WIND TURBINE SIZE Rotor D i a m e t e r (m)

(ft)

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; i 4oo ooo soo looo 12oo 14 o loo( Million k W h in 1993

;

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JO

0

Paul G i p e & Assoc., 1994

Figure 3. Ranking of major producing centers.

Figure 6. Increasing rotor diameter in successive design iterations.

550 TypiCal Specific Yields kWh/m2/yr kWh/m2/yr

'"0

M e a i u m ' S i ~ a Wind Turbin

t501

1250 1000 750

. . . .

o

500 26 4

5 e 7 8 Average A n n u a l Wind ~ o e e d in m / s

9

Figure 7. Typical specific yield. ACCEPTANCE OF WIND ENERGY Pement Acceptanoe

ect

High

Poe~

uring Project

Low

Tim 8ourcll I. NIIIIIl,ln, ~

Olmlll~llafl

Figure 8. Acceptance after installation. POWER PLANT PREFERENCE 5

Ratings

4.543.5 $ 2~ 2 Visual OgalRy

, Health • 8mfoty

, Environments| Impa¢l

T h a y e r , R. C o n s u m e r A t t i t u d e a n d C h o l c o

Figure 9. Preference of generating technologies.

~rall