REPORT REF: SFAUSVICXXMOR.1 SHADOW FLICKER AND BLADE GLINT REPORT

Transcription

1 REPORT REF: SFAUSVICXXMOR.1 SHADOW FLICKER AND BLADE GLINT REPORT MORTLAKE SOUTH WIND FARM SITE VICTORIA (AUSTRALIA) March 2016

2 Contents 1 Executive Summary Mortlake Site Site Location Wind Turbine Shadow Flicker Evaluation Considerations Shadow Flicker Evaluation Real Conditions Modelling and Findings Blade Glint Evaluation Conclusion Turbine Locations Dwelling Locations References SFAUSVICXXMOR.1 Page i

3 List of Tables Table 4.A Mortlake Annual Shadow Flicker Duration for 120m Hub-Height Turbines Table 7.A Mortlake Wind Turbine Locations, Projection UTM, Datum GDA94, Zone Table 8.A Mortlake Dwelling Locations within 1500m of a Wind Turbine, Projection UTM, Datum GDA94, Zone Error! Bookmark not defined. List of Figures Figure 4.A Mortlake Regional Location... 9 Figure 4.B Mortlake Situation Map Figure 4.C Mortlake Shadow Flicker Map for 120m Hub-Height Turbines SFAUSVICXXMOR.1 Page ii

4 1 Executive Summary ACCIONA Energy Australia Global (ACCIONA Energy) is seeking a variation to the planning permit for the proposed Mortlake South Wind Farm project. The current planning permit allows for the construction of up to 51 wind turbine generators to be built, with a maximum tip height of 141m and a maximum blade length of 41m. The planning permit variation will seek to amend the project configuration, to allow for construction of up to 42 wind turbine generators with a maximum tip height of 186m. This report considers potential changes in impacts (from the current planning permit to the proposed variation) associated with shadow flicker on nearby dwellings and the effect of blade glint on nearby dwellings and roads. In line with clause of the Moyne Planning scheme which references the recommendations from the Policy and planning guidelines for development of wind energy facilities in Victoria (Victoria State Government, 2015), a shadow flicker evaluation has been conducted in order to determine any possible effect on the surrounding properties. The shadow flicker assessment was conducted using wind turbines with a 132m rotor diameter and hub height of 120m, as this was considered the worst case scenario. The results of the shadow flicker modelling are a theoretical maximum number of annual hours of shadow flicker that could be experienced at residences in close proximity to the proposed wind farm. The model assumes that the wind farm and surroundings always experience the ideal conditions for propagation of shadows. The number of hours predicted by the model using the ideal conditions is referred to as the ideal shadow flicker hours. In real world, nonideal conditions, the actual number of shadow flicker hours is very likely to be lower. The ideal conditions for the propagation of shadow flicker assumed are: There is always sun available to cast a shadow; The wind turbine is always facing directly to or away from the sun, perpendicular to the sun path; The wind turbine is always rotating; The blades cast a shadow of the same intensity along their entire length; The sun is a point source; and There is no vegetation or other obstructions to the path of the shadow. When the real (non-ideal) conditions are taken into consideration, the number of hours calculated for each location is very likely to be significantly reduced (or potentially eliminated altogether). SFAUSVICXXMOR.1 Page 3

5 There are no dwellings within 1,000m of a wind turbine at the proposed Mortlake South Wind Farm. Modelling of the proposed configuration predicts that a maximum of seven (7) dwellings may potentially be affected by shadow flicker from the development of the Mortlake South Wind Farm; however, none of these dwellings are predicted to exceed the Victorian Planning Guidelines maximum level of 30 hours of shadow flicker exposure per year. This assessment of the extent of shadow flicker has been undertaken using the same assessment methodology and assumptions as those adopted in the Updated Shadow Flicker and Blade Glint Report prepared by ACCIONA Energy, dated August 2009, as part of the changes to the planning application layout. It can be observed that overall figures have decreased and the majority of dwellings experience a reduction in shadow flicker hours. This reassessment concludes that the proposed alterations to the Mortlake South Wind Farm will still comply with the Victorian Planning Guidelines for shadow flicker. Therefore, the proposed alterations to the Mortlake South Wind Farm will still comply with the Victorian Planning Guidelines for shadow flicker. Blade glint, annoyance caused by reflected sun light from wind turbines, will not create a significant problem as ACCIONA Energy will use turbine blades with a low reflectivity coating, as is industry best practice. SFAUSVICXXMOR.1 Page 4

6 2 Mortlake Site 2.1 Site Location The site is located in south western Victoria, Australia. The approximate location is indicated below in Figures 4.A and 4.B. The site is south of the Great Dividing Range in an extensive area of flat land. The area has limited vegetation and is well exposed to prevailing winds. 2.2 Wind Turbine A turbine with a 132m rotor diameter and a 120m hub-height was used for the shadow flicker evaluation at Mortlake. SFAUSVICXXMOR.1 Page 5

7 3 Shadow Flicker Evaluation Considerations Wind turbines are tall structures with rotating blades. As the blades rotate during operation they may cast an intermittent shadow on the surrounding landscape. The extent of the shadow will depend mainly on the time of day and geographical position. In line with clause of the Moyne Planning scheme i which references the recommendations from the Policy and planning guidelines for development of wind energy facilities in Victoria (Victoria State Government, 2015), a shadow flicker evaluation has been conducted in order to determine any possible effect on the surrounding properties. The Victorian Planning Guidelines limit the duration of shadow flicker at any dwelling to 30 hours a year ii. There are a number of factors influencing the effect and duration of shadow flicker, these include: Position of the sun with respect to the wind turbine (season/time of day); Position of the dwelling with respect to the wind turbine and the sun; Rotor size and height of the wind turbines; Distance of the dwelling from the wind turbines; Terrain undulation; Vegetation; Presence of wind and direction of wind (wind turbines rotating/swept shadow area); Weather/cloud cover; and Airborne particles/haze. Based on the suggested industry accepted distance beyond which shadow flicker is considered no longer a problem (normally ten rotor diameters from a wind turbine), ACCIONA Energy has conservatively limited its analysis of potential shadow flicker effects to a radius of 1,500m from each wind turbine location. SFAUSVICXXMOR.1 Page 6

8 4 Shadow Flicker Evaluation WindFarmer software has been used for the modelling and evaluation of potential shadow flicker impacts associated with the proposed Mortlake South Wind Farm. The following information was used to generate the model: A Digital Terrain Model (DTM) for the area with 50m horizontal resolution. This resolution was considered sufficient to model the impacts given the relatively flat terrain at the site; The wind turbine locations; The wind turbine physical characteristics (i.e., a wind turbine with 120m hub-height and 132m rotor diameter); Location of dwellings surrounding the wind farm; No impact of shadow flicker beyond a distance of 1,500m from the wind turbine locations; and Calculation time interval of 10 minutes. A minimum elevation angle of the sun of 3 degrees is based on industry accepted practice. When sun angles are lower than 3 degrees, the light travels through more of the atmosphere and becomes too diffuse to form a coherent shadow. As a result, the difference of radiation intensity between the shadow maximum and minimum is low enough such that a shadow is not perceptible. The results of the shadow flicker modelling are a theoretical maximum number of annual hours of shadow flicker that could be experienced under ideal conditions at residences in close proximity to the proposed wind farm. The ideal conditions assumed are given and discussed below: There is always sun available to cast a shadow (i.e., no reduction is made for cloud cover or other unfavourable weather conditions); The wind turbine is always facing directly to or away from the sun, perpendicular to the sun path. In reality the wind turbine blades will not always be perpendicular and may be parallel to the shadow path; The wind turbine is always rotating. In practice the wind turbines do not operate at all times, there will be periods where the wind speed is too low to operate the wind turbines or the wind turbine will be shut down for maintenance; The blades cast a shadow of the same intensity along their entire length; The sun is a point source and so casts strong shadows with no reduction due to interference from the wider light source; and There is no vegetation or other obstructions to the path of the shadow. SFAUSVICXXMOR.1 Page 7

9 4.1 Real Conditions When the real (non-ideal) conditions are taken into consideration, the number of hours of shadow flicker calculated for each location are very likely to be reduced based on weather and geometric considerations. Reductions for vegetation and other obstructions may also significantly reduce the amount of shadow flicker experienced at a dwelling. SFAUSVICXXMOR.1 Page 8

10 Figure 4.A Mortlake Regional Location SFAUSVICXXMOR.1 Page 9

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12 4.2 Modelling and Findings The shadow flicker modelling of the proposed Mortlake South Wind Farm on any of the surrounding dwellings has shown that a maximum of seven (7) dwellings may be affected by shadow flicker at certain times. The calculated number of annual hours at all dwellings within 1,500m of a wind turbine is presented in Table 4.A below for 120m hub-height wind turbines with 132m diameter blades, against the original planning permit layout. It can be observed that overall figures have decreased and the majority of dwellings experience a reduction in shadow flicker hours. The reassessment has been undertaken using an updated modelling resolution with the same shadow flicker assessment methodology and assumptions as those adopted in the Shadow Flicker and Blade Glint Report prepared by ACCIONA Energy, dated August 2009, which ultimately informed the decision to issue a planning permit. Each dwelling was represented by a shadow receptor with the same position as the dwelling and assuming the receptor is always oriented toward the wind turbine to present the worst case scenario. At the proposed Mortlake South Wind Farm site there are no dwellings within 1,000m of a wind turbine; the locations of the wind turbines for the proposed wind farm are presented in Table 7.A. The locations of the dwellings, based on a recent housing survey, are presented in Table 8.A; dwelling identification numbers are based on this housing survey. The minimum distance between a dwelling and a wind turbine is 1,009m (dwelling 126). The location of all dwellings nearby the Mortlake South Wind Farm site and the position of the wind turbines are shown in Figure 4.C. The first three shadow flicker colour bands (green, purple and orange) correspond to a cumulative range of under 30 annual hours; the dwelling with the highest number of calculated flicker duration (dwelling 162) falls between the purple and green bands (i.e., between 10 and 20 hours). The results of the modelling are considered to be a theoretical maximum and are therefore considered conservative. A reduction in the number of hours of shadow flicker can be assumed for real conditions for the reasons discussed in Section 4.1 of this report. SFAUSVICXXMOR.1 Page 11

13 Table 4.A Mortlake Annual Shadow Flicker Duration for 120m Hub-Height Wind Turbines Dwelling Number Original Layout Variation Layout Calculated Shadow Calculated Shadow Flicker Duration Flicker Duration 100m height 120m height (h/year) (h/year) Compliant 162 6:20 19:00 Yes 132 3:30 14:10 Yes :50 9:00 Yes :50 7:10 Yes :50 7:00 Yes 107 0:00 5:20 Yes 133 5:20 1:00 Yes 145 8:10 0:00 Yes 126 4:30 0:00 Yes :00 0:00 Yes 125 3:20 0:00 Yes 191 0:00 0:00 Yes 180 0:00 0:00 Yes 179 0:00 0:00 Yes 173 0:00 0:00 Yes 169 0:00 0:00 Yes 154 0:00 0:00 Yes 153 0:00 0:00 Yes 120 0:00 0:00 Yes 116 0:00 0:00 Yes 112 0:00 0:00 Yes 111 0:00 0:00 Yes 991 0:00 0:00 Yes It can be seen that the proposed wind farm continues to comply with the 30 hour shadow flicker limit set in the Victorian Planning Guidelines. SFAUSVICXXMOR.1 Page 12

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15 5 Blade Glint Evaluation Blade glint is defined as sunlight reflecting off the wind turbine blades and visible to a person. This may, under rare circumstances, result in impacted visibility that may affect some motorists or cause annoyance at dwellings. Modern wind turbine blade manufacturers have acknowledged the possibility of adverse effects due to blade glint and now use low reflectivity gel finish to minimise any reflections. The amended Mortlake South Wind Farm project will use wind turbine blades with a low reflectivity finish (as was proposed for the currently permitted project). Blade glint will therefore not affect any of the dwellings or any motorist travelling on nearby gazetted roads close to the proposed wind farm. SFAUSVICXXMOR.1 Page 14

16 6 Conclusion ACCIONA Energy has carried out a detailed analysis of the potential for shadow flicker and blade glint to impact the dwellings close to the proposed Mortlake South Wind Farm. None of the surrounding dwellings will be impacted by shadow flicker in excess of the limit set out in the Victorian Planning Guidelines. As the modelling results are a theoretical maximum, it is very likely that the number of hours of shadow flicker experienced would be significantly less. The proposed Mortlake South Wind Farm continues to comply with the Victorian Planning Guidelines for shadow flicker. SFAUSVICXXMOR.1 Page 15

17 7 Turbine Locations The locations of the wind turbines in the permit variation layout are given below. Table 7.A Mortlake Wind Turbine Locations, Projection UTM, Datum GDA94, Zone 54 Wind Turbine Eastings (m) Northings (m) Elevation (m) SFAUSVICXXMOR.1 Page 16

18 8 Dwelling Locations The locations of dwellings within 1,500m of a wind turbine are given below. Table 8.A Mortlake Dwelling Locations within 1,500m of a Wind Turbine, Projection UTM, Datum GDA94, Zone 54 Dwelling Number Eastings (m) Northings (m) Elevation (m) , , , , , , , , , , , , , , , , , , , , , , ,260.9 Distance to nearest Wind turbine (m) SFAUSVICXXMOR.1 Page 17

19 9 References i ii Moyne Planning Scheme (October 2015), clause Victorian Government Department of Environment, Land, Water & Planning (January 2016). Policy and planning guidelines for development of wind energy facilities in Victoria SFAUSVICXXMOR.1 Page 18