2014: The Year When the Silent Onshore Wind Power Revolution ...

[6] “Potenziale der Windenergie an Land – Studie zur Ermittlung des bundesweiten Flächen und Leistungspotentials der. Windenergienutzung an Land”, Insa ...
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2014: The Year When the Silent Onshore Wind Power Revolution Became Universal and Visible to All? Evidence of Potential Onshore Wind High and Very High Capacity Factors On Sites With 5 to 10 m/s Average Annual Wind Speeds at Hub Height

Bernard Chabot, Renewable Energy Expert and Trainer, BCCONSULT, [email protected]

The “silent wind power revolution” consisting in the not sufficiently known but proven availability of new IEC3 class wind turbines optimized to deliver high and very high capacity factors on light and medium wind speed areas has been described in reference [1] and [2] and the kWh cost delivered by relevant onshore wind power projects has been analyzed in reference [3]. All those analysis and the actual wind power market changes demonstrate that this “revolution” opens new opportunities for developers and investors and presents many advantages to increase the wind energy penetration rates and to ease wind power integration in the electric systems and their management. This new article summarizes the results of a study of the potential impact of availability of new IEC class 1 and 2 wind turbines also optimized to deliver high and very high capacity factors on medium to high quality sites, from 7.5 to 10 m/s of average annual wind speed at hub height. Here also, there is evidence that the recent shift to IEC1 and IEC2 class wind turbines with higher ratio Su between the rated power and the swept area (in m2/kW) will offer similar advantages: high and very high equivalent annual full load hours Nh and capacity factors CF (CF = Nh/8760 and expressed in %), higher TWh delivered per installed or targeted GW, lower grid adaptation costs and higher annual hours of operation of wind farms at or near rated power. In 2014, almost all of wind turbines manufacturers will either confirm or announce such commercial products and will put on tests prototypes covering all potential onshore wind sites with high and very high capacity factors, “from 5 to 10 m/s average annual wind speed at hub height”, and so this “silent wind power revolution” could and should be now taken into account and backed not only by developers and investors, but also by governments, energy planners, electricity markets regulators, utilities and electricity transport and distribution systems operators.

In reference [1], results were given for equivalent full load hours Nh (hours per year) and average annual capacity factors CF (CF = Nh/8760, expressed in %) of new IEC3 class wind turbines with high and very high specific area (the ratio Su between the wind turbine swept area S and its rated power P, in m2 per kW). They demonstrated that high and very high Nh and CF values can be delivered even in low to medium wind speed areas, from 6 to 7.5 m/s of average annual wind speed at hub height and considering a Rayleigh statistical distribution of wind speeds. Those results were used in references [3] and [4] to make an analysis of the minimum required selling price of wind power kWh to attract private investors in projects using those new wind turbines on those sites. Figure 1 from [4] summarizes the very attractive results and put them in comparison with potential offshore required kWh selling prices.

1

Figure 1: Scenario of kWh price required to attract private investors in onshore IEC3a and offshore wind projects This article will analyze if such high and very high Nh and CF values can also be delivered by new IEC2 and IEC1 classes wind turbines. For that, a sample of new commercial or at the development stage wind turbines was defined: 12 for class 1, 16 for class 2 and to check and expand preliminary results in [1], 19 for IEC3a wind turbines. The total 47 wind turbines are from 13 manufacturers in Europe, North America and Asia. Potential reference annual energy yield of those 47 wind turbines were defined for wind speeds ranging from 5 to 10 m/s at hub height, with a Rayleigh distribution (shape coefficient k = 2), 10 % wind farm total losses and 100 % availability from wind turbines, wind farms and the grid. All calculation was made from the “Windmatching calculator” [5] in order to get harmonized and transparent results. From those results and for each IEC class 1, 2 and 3, Nh values of each wind turbines are drawn versus their Su values. A “quasi linear relationship” appears for each average annual wind speed at hub height value Vm between Nh and Su. So, a linear model Nh = a*Su + b is proposed for each reference average wind speed value and for the three IEC classes 1 (Vm from 8.5 to 10 m/s), 2 (Vm from 7.5 to 8.5 m/s) and 3. Average annual wind speed range for the IEC3 class is down to 5 m/s and up to 7.5 m/s. Discrepancies between those three linear models and the reference Nh values of the 47 wind turbines are low, within a maximum range of plus or minor 10 %, and so the Nh values from the proposed three linear values are sufficiently representative to make the present strategic comparative analysis. Of course, for actual wind power projects, even at the feasibility study stage, a more precise annual energy yield should be performed from the exact characteristics of the wind turbine (mainly its validated power curve), the actual wind speed statistical distribution on the site and the layout and the design of the wind farm. The two relevant graphs for each of the three IEC classes are detailed in ANNEX 1, 2 and 3 (pages 8, 9 and 10).

2

From those three linear models, figure 2 shows the complete “mapping” of Nh values from the three IEC classes 1, 2 and 3 versus the total range of Su values (from 1.6 to 5.2 extreme potential values) and for average annual wind speeds at hub height Vm from 5 to 10 m/s by 0.25 m/s increments.

Nh = f(Su, Vm) for IEC class 1, 2 and 3 Wind Turbines k = 2, Mvair = 1.225 kg/m3, wind farm losses 10%, 100 % availability 4 800

Vm (m/s)

4 600

10

4 400

9,75 9,5

4 200

9,25

Nh (Full load hours/year)

4 000

9

3 800

8,75

3 600

8,5

3 400

8,25 8

3 200

7,75 3 000

7,5

2 800

7,25

2 600

7

2 400

6,75

6,5

2 200

6,25

2 000

6

1 800

5,75

1 600

5,5 5,25

1 400 1,6

1,8

2

Bernard CHABOT - BCCONSULT

2,2

2,4

2,6

2,8

3

3,2

3,4

3,6

3,8

4

4,2

4,4

4,6

4,8

5

5,2

5

Su = S / P (m2/kW)

Figure 2: Reference Nh values versus Su values for average wind speeds Vm from 5 to 10 m/s One can see that the “linear models” for IEC classes 2 and 3 fit very well together at the common limit of wind speed of 7.5 m/s. The linear model for class 1 differs from the one for class 2. Optimized class 3 wind turbines can deliver Nh values higher than 1,800 hour/year with very low wind speed Vm = 5 m/s at hub height if their Su value is higher than 4.1 m2/kW, and such IEC3a wind turbines are already available or under development to be put on the market in 2014: seven of them are included in the sample for the present analysis. On sites with Vm = 7.5 m/s, those IEC3 wind turbines can deliver Nh values from 3,300 to 4,360 hours per year. Those results confirm perfectly the previous analysis in reference [1] and give a stronger base to the very attractive economic analysis results in reference [3] and the summary in figure 1 above. Optimized Class 2 wind turbines, here in their logical wind speed range from 7.5 to 8.5 m/s at hub height can deliver Nh values from 3,000 to 4,400 hours/year. Minimum values are of course much higher than with class 3 wind turbines, but the maximum values is not so much higher than with class 3 wind turbines on sites with 7.5 m/s at hub height. Optimized Class 3 wind turbines with Su values higher than 2.4 m2/kW (9 models in the IEC1 sample), can deliver Nh values from 3,600 hours/year at 8.5 m/s at hub height and up to 4,700 hours/year at 10 m/s. Here also, this last higher value of 4,700 hours/year is not so different from the maximum of 3,400 hours/year for class 2 at 8.5 m/s and from the maximum 3,300 hours/year for the class 3 at 7.5 m/s.

3

Those results confirm the strategic values of those new IEC3 wind turbines: even in medium wind speed areas (6.5 to 7.5 m/s), they can easily deliver Nh values higher than 3,000 hours/year, which compare well with those on IEC2 and IEC1 sites equipped with past conventional wind turbines. From this figure 1, it is also easy for wind turbines manufacturers to see what should be the minimum targets for the Su values of their new models. Figure 3 shows the same analysis results expressed in average annual capacity factors CF (expressed in %).

Capacity Factor CF (%) = f(Su, Vm) for IEC class 1, 2 and 3 Wind Turbines k = 2, Mvair = 1.225 kg/m3, wind farm losses 10%, 100 % availability 56

Vm (m/s)

54

10

52

9,75

50

9,5

48

9,25

46

9

44

8,75

Average Annual Capacity Factor CF (%)

42

8,5

40

8,25

38

8

36

7,75

34

7,5

32

7,25

30

7

28

6,75

26

6,5

24

6,25

22

6

20

5,75

18

5,5

16

5,25

14 1,6

1,8

2

2,2

Bernard CHABOT - BCCONSULT

2,4

2,6

2,8

3

3,2

3,4

3,6

3,8

4

4,2

4,4

4,6

4,8

5

5,2

5

Su = S / P (m2/kW)

Figure 3: Reference capacity factors CF values versus Su values for average wind speeds Vm from 5 to 10 m/s Same conclusions can be drawn from those CF values: for example, CF higher than 20 % can be delivered on very low quality sites at only 5 m/s at hub height if the Su values is higher than 4.1 m2/kW, and CF values higher than 40 % can be delivered either by class 2 or class 3 wind turbines at 7.5 m/s at hub height if Su values are higher than 3.6 m2/kW. Highest CF values with very high Su values (already proven possible) can be as high as 48 % at 7.5 m/s with class 3 wind turbines, up to 50 % at 8.5 m/s with class 2 wind turbines and up to 54 % with class 1 wind turbines at 10 m/s at hub height. Figure 4 and 5 show the same analysis results in Nh values (figure 4) and CF values (figure 5) versus average annual wind speed at hub height Vm and for selected reference Su values for class 1, 2 and 3 wind turbines.

4

Nh = f(Su, Vm) for IEC class 1, 2 and 3 Wind Turbines k = 2, Mvair = 1.225 kg/m3, wind farm losses 10%, 100 % availability 4 800

Su (m2/kW)

4 600

5,1

4 400

4,6 4,1

4 200

3,6

Nh (Full load hours/year)

4 000

3,1

3 800

2,8

3 600

2,5

3 400

2

1,5

3 200 3 000 2 800 2 600 2 400

2 200 2 000 1 800 1 600

IEC1

IEC2

IEC3

IEC4

1 400 5

5,5

6

6,5

7

7,5

8

8,5

9

9,5

10

Vm (m/s at hub height)

Bernard CHABOT - BCCONSULT

Figure 4: Nh values versus Vm values for a range of Su values from 1.5 to 5.1 m2/kW

Capacity Factor CF (%) = f(Vm, Su) for IEC class 1, 2 and 3 Wind Turbines k = 2, Mvair = 1.225 kg/m3, wind farm losses 10%, 100 % availability 56

Su (m2/kW)

54

1,5

52

2

50

2,5

48

2,8

46

3,1

44

3,6

Average Annual Capacity Factor CF (%)

42

4,1

40

4,6

38

5,1

36

34 32 30

28 26 24

22 20

18 16 14 5

5,5

Bernard CHABOT - BCCONSULT

6

6,5

7

7,5

8

8,5

9

9,5

10

Vm (m/s at hub height)

Figure 5: CF values versus Vm values for a range of Su values from 1.5 to 5.1 m2/kW

5

Some conclusions can be drawn from this analysis and the above results: Advantages of using the new IEC3a wind turbines with high Su values on light to medium wind speed areas are confirmed with the linear model resulting from an extended sample of those new IEC3 wind turbines: o High and very high values for the equivalent full load hours of operation Nh and for the related average annual capacity factors CF. o More TWhs per year and higher penetration rates per installed or targeted GWs. o Lower cost of grid adaptation and development: “Much less copper per new TWhs/year delivered”. o More opportunities for local developers and investors, including local communities, farmers and cooperatives. o Easier integration in the electrical system and its management due to higher annual hours of operation at or near rated power for wind turbines and wind farms. All those advantages can be extended now to the IEC class 1 and 2 wind turbines and sites “from 5 to 10 m/s at hub height”, opening opportunities for comprehensive and rational development of onshore wind power in all a territory, region or country. Favoring the use of those new wind turbines with high and very high Su values would require: o Information and training on those strategic opportunities and advantages offered by those new wind turbines for wind power developers and investors and also for policy makers and energy planners. o Adapted regulations for projects authorization and permits, as the trend for high Su values is towards large diameters and high to very high hub heights. o Adapted feed-in tariffs and other incentives systems, giving a clear incentive to use wind turbines with high Su values in order to materialize the above advantages. o Deliver public, comprehensive and transparent information on effective field performance of wind farms using those new wind turbines:  Actual monthly and yearly measured energy delivery and related Nh and CF values factors.  Project’s investment costs in order to refine economic assessment, including reference kWh costs calculation, in order to make updated comparisons with other reference kWh costs from different energy technologies. o Assist the development and the market deployment of those new wind turbines by specific technical assistance and research and development:  New wind energy atlas and studies of potential use of wind energy taking into account those new wind turbines and their high performances, such as the recent German one, see reference [6].  Specific studies on low and very low wind speed sites characteristics (including in forests and in complex terrain) which can differ greatly from “conventional sites” historically used.  R&D on optimized blades and wind turbines designs with high and very high Su values for all the three IEC classes 1, 2 and 3. Those conditions are easy to materialize, and can benefit from the fact that the vast majority of world wind turbines manufacturers are proposing or will propose in a short delay such high Su values models for all IEC classes, and from the evidence that more and more investors have already chosen them for projects in both regulated and non regulated wind power markets, proving that those projects can be profitable. And they can participate to transform this “Silent revolution” into one highly visible one for all stakeholders and decision makers, from the start of 2014, with related benefits to the decades to come. ________________

REFERENCES: [1] “ Wind Power Silent Revolution: New Wind Turbines for Light Wind Sites”, Bernard Chabot, online May 6, 2013 and downloadable as pdf at the bottom of the web page: http://www.renewablesinternational.net/turbines-in-low-wind-areas/150/505/62498/

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[2] “Is the “Wind Power Silent Revolution” Possible? First Conclusions from a Real Project Performance Analysis and Economic Simulation”, Bernard Chabot, online August 20, 2013, and downloadable as pdf at: http://www.renewablesinternational.net/silentwind-power-revolution/150/435/72126/

[3] “Bright economic and strategic perspectives for onshore wind power in medium to low wind speed areas”, Bernard Chabot, WindTech International, Volume 9, N°6, September 2013. [4] “Onshore and Offshore Wind Power Capacity Factors: How Much they Differ Now and in the Future? A Case Study from Denmark“, Bernard Chabot, online on October 9th, 2013 and downloadable as pdf at: http://www.renewablesinternational.net/historic-danish-wind-statistics-analyzed/150/435/73702/ [5] Access to the “WindMatching Calculator”: http://www.windmatching.com/technical,calculator/ [6] “Potenziale der Windenergie an Land – Studie zur Ermittlung des bundesweiten Flächen und Leistungspotentials der Windenergienutzung an Land”, Insa Lütkehus & alii, UBA, June 2013, downloadable at: http://www.umweltbundesamt.de/en/publikationen/potenzial-windenergie-an-land

ANNEXES 1 to 3: pages 8, 9 and 10: Sample of IEC 1, 2 and 3 wind turbine Nh values versus Su, and proposed linear models Nh = a*Su + b

7

ANNEX 1: IEC1 Wind Turbines and Model

Nh = f(Su, Vm) of IEC1 Wind Turbines 8,5

9

9,5

10

Linear (8.5)

Linear (9)

Linear (9.5)

Linear (10)

4 800

y = 739,16x + 2441,9 4 600 y = 752,28x + 2180,7 4 400 y = 750,57x + 1927,8

4 200

NH (h/an)

4 000

y = 760,59x + 1623,9

3 800 3 600

3 400 3 200 3 000 2 800

1,6 BCCONSULT

1,7

1,8

1,9

2,0

2,1

2,2

2,3

2,4

2,5

Su (m2/kW)

IEC1 Wind Turbines Model:

8

2,6

2,7

2,8

2,9

3,0

3,1

ANNEX 2: IEC2 Wind Turbines and Model

Nh = f(Su, Vm) of IEC2 Wind turbines 7

7,5

8

8,5

Linear (7)

Linear (7.5)

Linear (8)

Linear (8.5)

4 500

4 400 y = 475,66x + 2432,7

4 300 4 200 4 100

y = 484,84x + 2107,9

4 000 3 900

NH (h/an)

3 800 y = 488,37x + 1773

3 700 3 600 3 500 3 400

y = 484,33x + 1436,8

3 300 3 200

3 100 3 000 2 900 2 800 2 700 2 600

2,6 BCCONSULT

2,7

2,8

2,9

3,0

3,1

3,2

3,3

3,4

Su (m2/kW)

IEC2 Wind Turbines Model:

9

3,5

3,6

3,7

3,8

3,9

4,0

ANNEX 3: IEC3 Wind Turbines

NH (hyear)

Nh = f(Su, Vm) of IEC3 Wind Turbines 5

5,5

6

6,5

7

7,5

Linear (5)

Linear (5.5)

Linear (6)

Linear (6.5)

Linear (7)

Linear (7.5)

4 300 4 200 4 100 4 000 3 900 3 800 3 700 3 600 3 500 3 400 3 300 3 200 3 100 3 000 2 900 2 800 2 700 2 600 2 500 2 400 2 300 2 200 2 100 2 000 1 900 1 800 1 700 1 600 1 500 1 400

y = 473,45x + 1815,1 y = 476,83x + 1454

y = 471,69x + 1098,3

y = 455,85x + 761,56

y = 426,42x + 462,84

y = 369,16x + 280,58

3,1

3,2

3,3

3,4

3,5

3,6

3,7

3,8

3,9

4,0

4,1

4,2

4,3

4,4

4,5

4,6

4,7

4,8

4,9

5,0

5,1

5,2

Su (m2/kW)

BCCONSULT

IEC3 and IEC4 Wind Turbines Model:

Nh = f(Su, Vm) for IEC3 class Wind Turbines

Nh (hours/year)

K = 2, Mvair = 1.225 kg/m3, wind farm losses 10 %, 100% availability Vm (m/s)

4 400 4 300 4 200 4 100 4 000 3 900 3 800 3 700 3 600 3 500 3 400 3 300 3 200 3 100 3 000 2 900 2 800 2 700 2 600 2 500 2 400 2 300 2 200 2 100 2 000 1 900 1 800 1 700 1 600 1 500 1 400

7,5 7,25

7 6,75 6,5

6,25 6 5,75 5,5 5,25

5

3,1 3,2 3,3 3,4 3,5 3,6 3,7 3,8 3,9 BCCONSULT

4

4,1 4,2 4,3 4,4 4,5 4,6 4,7 4,8 4,9

Su (m2/kW)

10

5

5,1 5,2