Shadow Flicker Briefing

Transcription

1 Wind Farm Measurements and Modeling Shadow Flicker Briefing Subject: Customer: Project type: Prepared by: Distribution: Shadow-Flicker Modeling Clayton, NY. PPM Atlantic Renewable 330 Province Line Road Skillman, NJ Modeling Arne Nielsen, WEI Neil Habig, Diane Sullivan Revision: 0 Date: Feb. 07, Introduction This Project Briefing provides a brief explanation of the shadow-flicker phenomenon, the modeling approach employed and relevant explanations and results. 2. Shadow-Flicker Background Shadow-flicker from wind turbines is defined as alternating changes in light intensity caused by rotating blades casting shadows on the ground and on stationary objects such as a window at a dwelling. No shadow will be cast when the sun is obscured by clouds/fog and no flickering will take place when the turbine blades are not turning. Shadow-flicker can occur in project area homes when the turbine is located near a home and is in a position where the blades interfere with low-angle sunlight as the case is before sunset and after sunrise. The most typical effect is the visibility of an intermittent light reduction in the rooms of the home facing the wind turbines and subject to the shadow-flicker. Such locations are here referred to as shadow-flicker receptors. Obstacles such as terrain, trees, or buildings between the wind turbine and a potential shadow-flicker receptor significantly reduce or eliminate shadow-flicker effects. The spatial relationships between a wind turbine and receptor, as well as wind direction are key factors related to shadow-flicker time (hours per year). General industry practices place turbines 1200 ft or more from sensitive receptors. At this distance shadow flicker usually only occurs at sunrise or sunset when the cast shadows are sufficiently long. Shadow flicker intensity is defined as the difference in brightness at a given location in the presence and absence of a shadow. Shadow flicker intensity diminishes with greater receptorto-turbine separation distance and low visibility weather conditions, such as haze or fog. The analysis performed for this report does not evaluate the shadow flicker intensity, but rather focuses on the total amount of time (hours and minutes/year) that shadow flicker can potentially occur at receptors regardless of whether the shadow flicker is barely noticeable or Page 1 of 4

2 Shadow-Flicker Briefing, Clayton clearly distinct. Consequently, it is likely that receptors will experience less shadow-flicker impact than modeled and reported, especially those that are further away from turbines. It is very likely that marginally affected receptors may not be able to identify shadow-flicker at all. The shadow-flicker frequency is related to the rotor speed and number of blades on the rotor. The modeling results presented are based on a wind turbine with a 3-bladed, 88 meter diameter rotor, 80 meter hub height and a nominal rotor speed of 15.5 RPM which translates to a blade pass frequency of 0.8 Hz (less than 1 alternation per second). Health wise, such low frequencies are harmless. Frequencies higher than 3 Hz but below 10 Hz are widely used in discotheques. The Epilepsy Foundation has made statements that frequencies below 10 Hz are not likely to trigger epileptic seizures. 3. Modeling Approach A near worst case approach has been adopted for reporting the shadow-flicker results. Additional general site and receptor-specific assessments such as obstacles, diurnal and seasonal cloud and fog patterns may further reduce the reported shadow flicker impacts. The analysis assumes windows are situated in direct alignment with the turbine to sun line of sight. Even when windows are so aligned, the analysis does not account for the difference between windows in rooms with primary use and enjoyment (e.g. living rooms) and other less frequently occupied or un-occupied rooms or garages. The shadow-flicker model uses the following input: Turbine locations (coordinates) Shadow Flicker receptor (residence) locations (coordinates) USGS 1:24,000 topographic and USGS DEM (height contours) Turbine rotor diameter Turbine hub height Joint wind speed and direction frequency distribution Sunshine hours (long term monthly reference data) The model calculates detailed shadow-flicker results at each assessed receptor location and the amount of shadow-flicker time (hours/year) everywhere surrounding the project (on an iso-line plot). A receptor in the model is defined as a 1 m² area 1 meter above ground level. This omni-directional approach produces shadow-flicker results at a receptor regardless of the direction of windows and provides similar results as a model with windows on various sides of the receptor. The sun s path with respect to each turbine location is calculated by the software to determine the cast shadow paths every 2 minutes, every day over a full year. The turbine run-time and direction (seen from the receptor) are calculated from the site s long-term wind speed and direction distribution. Finally, the effects of cloud cover are calculated using long term reference data (monthly average sunshine hours) to arrive at the projected annual flicker time at each receptor. Output from the model includes the following information: Page 2 of 4

3 Shadow-Flicker Briefing, Clayton Calculated shadow-flicker time at selected receptors Tabulated and plotted time of day with shadow flicker at selected receptors Map showing turbine locations, selected shadow-flicker receptors and iso-line contours indicating projected shadow-flicker time (hours per year). 4. Conclusion The shadow-flicker model assumptions applied to this project are very conservative and as such, the analysis is expected to over-predict the impacts. Additionally, many of the modeled shadow flicker hours are expected to be of very low intensity. The results are therefore prudent projections of the anticipated shadow flicker levels that would be experienced at the nearby residences. Of the 193 modeled receptors 6 receptors will potentially receive shadow-flicker in excess of 25 hours per year. All other modeled receptors potentially receive little or no shadow flicker. Receptor name Shadow hours per year (worst case) [hh:mm / year] Shadow days per year [days / year] Max shadow hours per day [hh:mm / day] Shadow hours per year (real) [hh:mm / year] : :10 36: : :54 32: : :10 31: : :50 30: : :54 28: : :50 26:44 Fig. 1. Shadow-flicker listing, 25 hours and above. At this time no detailed information is available for the 6 receptors. Some of the receptors may be participating landowners. Further information may be obtained regarding eventual obstacles between the wind turbine and the receptor such as terrain, trees, or buildings. Such obstacles may significantly reduce or eliminate shadow-flicker. The overall statistics, including receptors that eventually can be disregarded are outlined below: Shadow-flicker time T [hours] Number of receptors Total modeled < T < T < T < T > 25 hours 6 Fig. 1. Overall statistics, all modeled receptors. The number of shadow-flicker hours calculated and reported above, considering the one participating landowner, is typical for wind power projects installed in the state of New York and around the USA. Page 3 of 4

4 Shadow-Flicker Briefing, Clayton For clarifications and eventual detailed analyses of expected influence at selected receptors please contact: Arne Nielsen Tel.: Fax: Cell.: Page 4 of 4

5 Project: 01/27/07 09:47 / 1 SHADOW - 37_5kz13 File: 37_5kz13.bmi New WTG m Map: 37_5kz13, Print scale 1:25,000, Map center UTM NAD27 Zone: 18 East: 416,350 North: 4,886,800 Shadow receptor Isolines showing shadow in Shadow hours per year. Real value calculation

6 SHADOW - 37_5kz13 File: 37_5kz13.bmi 01/27/07 11:57 / m Map: 37_5kz13, Print scale 1:25,000, Map center UTM NAD27 Zone: 18 East: 419,500 North: 4,889,800 New WTG Shadow receptor Isolines showing shadow in Shadow hours per year. Real value calculation

7 SHADOW - 37_5kz13 File: 37_5kz13.bmi 01/27/07 11:10 / m Map: 37_5kz13, Print scale 1:25,000, Map center UTM NAD27 Zone: 18 East: 419,500 North: 4,886,800 New WTG Shadow receptor Isolines showing shadow in Shadow hours per year. Real value calculation

8 SHADOW - 37_5kz13 File: 37_5kz13.bmi 01/27/07 10:10 / m Map: 37_5kz13, Print scale 1:25,000, Map center UTM NAD27 Zone: 18 East: 416,350 North: 4,883,800 New WTG Shadow receptor Isolines showing shadow in Shadow hours per year. Real value calculation

9 SHADOW - 37_5kz13 File: 37_5kz13.bmi 01/27/07 10:51 / m Map: 37_5kz13, Print scale 1:25,000, Map center UTM NAD27 Zone: 18 East: 419,500 North: 4,883,800 New WTG Shadow receptor Isolines showing shadow in Shadow hours per year. Real value calculation

10 Project: 01/27/07 08:52 / 1 SHADOW - 37_5kz13 File: 37_5kz13.bmi m Map: 37_5kz13, Print scale 1:40,000, Map center UTM NAD27 Zone: 18 East: 417,971 North: 4,886,455 New WTG Shadow receptor Isolines showing shadow in Shadow hours per year. Real value calculation

11 SHADOW - Main Result 01/27/07 15:22 / 1 Assumptions for shadow calculations Maximum distance for influence 1,000 m Minimum sun height over horizon for influence 3 Day step for calculation 1 days Time step for calculation 2 minutes Sun shine probabilities (part of time from sun rise to sun set with sun shine) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Operational time N NNE ENE E ESE SSE S SSW WSW W WNW NNW Sum ,251 1, ,747 Scale 1:200,000 New WTG Shadow receptor WTGs UTM NAD27 Zone: 18 WTG type East North Z Row data/description Valid Manufact. Type Power Diam. Height RPM [m] [kw] [m] [m] [RPM] ,865 4,883, Yes Suzlon S88 2.1MW 2, ,041 4,883, Yes Suzlon S88 2.1MW 2, ,197 4,883, Yes Suzlon S88 2.1MW 2, ,398 4,883, Yes Suzlon S88 2.1MW 2, ,616 4,882, Yes Suzlon S88 2.1MW 2, ,817 4,882, Yes Suzlon S88 2.1MW 2, ,893 4,886, Yes Suzlon S88 2.1MW 2, ,128 4,886, Yes Suzlon S88 2.1MW 2, ,266 4,886, Yes Suzlon S88 2.1MW 2, ,478 4,885, Yes Suzlon S88 2.1MW 2, ,683 4,885, Yes Suzlon S88 2.1MW 2, ,589 4,884, Yes Suzlon S88 2.1MW 2, ,769 4,884, Yes Suzlon S88 2.1MW 2, ,936 4,884, Yes Suzlon S88 2.1MW 2, ,133 4,884, Yes Suzlon S88 2.1MW 2, ,330 4,884, Yes Suzlon S88 2.1MW 2, ,782 4,884, Yes Suzlon S88 2.1MW 2, ,013 4,884, Yes Suzlon S88 2.1MW 2, ,584 4,883, Yes Suzlon S88 2.1MW 2, ,781 4,883, Yes Suzlon S88 2.1MW 2, ,953 4,883, Yes Suzlon S88 2.1MW 2, ,165 4,883, Yes Suzlon S88 2.1MW 2, ,938 4,887, Yes Suzlon S88 2.1MW 2, ,169 4,886, Yes Suzlon S88 2.1MW 2, ,381 4,886, Yes Suzlon S88 2.1MW 2, ,128 4,885, Yes Suzlon S88 2.1MW 2, ,351 4,885, Yes Suzlon S88 2.1MW 2, ,555 4,885, Yes Suzlon S88 2.1MW 2, ,812 4,885, Yes Suzlon S88 2.1MW 2, ,222 4,884, Yes Suzlon S88 2.1MW 2, ,651 4,884, Yes Suzlon S88 2.1MW 2, ,859 4,884, Yes Suzlon S88 2.1MW 2, ,108 4,884, Yes Suzlon S88 2.1MW 2, ,995 4,887, Yes Suzlon S88 2.1MW 2, ,951 4,886, Yes Suzlon S88 2.1MW 2, ,258 4,886, Yes Suzlon S88 2.1MW 2, ,371 4,886, Yes Suzlon S88 2.1MW 2, ,040 4,885, Yes Suzlon S88 2.1MW 2, Continued on next page...

12 SHADOW - Main Result 01/27/07 15:22 / 2...continued from previous page UTM NAD27 Zone: 18 WTG type East North Z Row data/description Valid Manufact. Type Power Diam. Height RPM [m] [kw] [m] [m] [RPM] ,255 4,885, Yes Suzlon S88 2.1MW 2, ,474 4,885, Yes Suzlon S88 2.1MW 2, ,258 4,888, Yes Suzlon S88 2.1MW 2, ,800 4,887, Yes Suzlon S88 2.1MW 2, ,052 4,887, Yes Suzlon S88 2.1MW 2, ,213 4,887, Yes Suzlon S88 2.1MW 2, ,461 4,887, Yes Suzlon S88 2.1MW 2, ,965 4,887, Yes Suzlon S88 2.1MW 2, ,212 4,887, Yes Suzlon S88 2.1MW 2, ,652 4,886, Yes Suzlon S88 2.1MW 2, ,930 4,885, Yes Suzlon S88 2.1MW 2, ,709 4,885, Yes Suzlon S88 2.1MW 2, ,884 4,888, Yes Suzlon S88 2.1MW 2, ,042 4,888, Yes Suzlon S88 2.1MW 2, ,719 4,887, Yes Suzlon S88 2.1MW 2, ,990 4,889, Yes Suzlon S88 2.1MW 2, ,689 4,888, Yes Suzlon S88 2.1MW 2, ,567 4,888, Yes Suzlon S88 2.1MW 2, ,768 4,888, Yes Suzlon S88 2.1MW 2, ,185 4,890, Yes Suzlon S88 2.1MW 2, ,364 4,890, Yes Suzlon S88 2.1MW 2, ,696 4,890, Yes Suzlon S88 2.1MW 2, ,823 4,889, Yes Suzlon S88 2.1MW 2, ,199 4,889, Yes Suzlon S88 2.1MW 2, Shadow receptor-input UTM NAD27 Zone: 18 No. Name East North Z Width Height Height Degrees from Slope of a.g.l. south cw window [m] [m] [m] [m] [ ] [ ] ,824 4,889, ,004 4,889, ,022 4,889, ,043 4,889, ,040 4,889, ,132 4,889, ,136 4,889, ,196 4,889, ,073 4,889, ,972 4,889, ,275 4,891, ,339 4,891, ,524 4,889, ,343 4,888, ,439 4,888, ,524 4,888, ,441 4,888, ,529 4,888, ,305 4,888, ,210 4,888, ,001 4,888, ,713 4,888, ,019 4,888, ,749 4,887, ,453 4,887, ,236 4,887, ,140 4,887, ,043 4,887, ,590 4,887, Continued on next page...

13 SHADOW - Main Result 01/27/07 15:22 / 3...continued from previous page UTM NAD27 Zone: 18 No. Name East North Z Width Height Height Degrees from Slope of a.g.l. south cw window [m] [m] [m] [m] [ ] [ ] ,994 4,887, ,365 4,887, ,425 4,887, ,622 4,887, ,292 4,887, ,125 4,888, ,134 4,888, ,066 4,888, ,066 4,888, ,142 4,888, ,166 4,888, ,142 4,888, ,129 4,888, ,178 4,888, ,196 4,887, ,196 4,887, ,240 4,887, ,202 4,887, ,202 4,887, ,142 4,887, ,111 4,887, ,237 4,887, ,249 4,887, ,230 4,887, ,164 4,887, ,248 4,887, ,187 4,887, ,015 4,886, ,380 4,886, ,208 4,886, ,344 4,886, ,854 4,886, ,724 4,886, ,461 4,886, ,478 4,886, ,510 4,886, ,571 4,886, ,652 4,886, ,715 4,886, ,788 4,886, ,134 4,887, ,532 4,886, ,412 4,886, ,798 4,887, ,887 4,886, ,670 4,886, ,474 4,886, ,206 4,886, ,458 4,886, ,387 4,886, ,206 4,887, ,091 4,887, ,231 4,886, ,624 4,886, ,762 4,886, ,803 4,886, ,097 4,886, ,555 4,886, ,758 4,886, ,700 4,886, Continued on next page...

14 SHADOW - Main Result 01/27/07 15:22 / 4...continued from previous page UTM NAD27 Zone: 18 No. Name East North Z Width Height Height Degrees from Slope of a.g.l. south cw window [m] [m] [m] [m] [ ] [ ] ,055 4,886, ,187 4,886, ,337 4,886, ,408 4,886, ,563 4,886, ,939 4,886, ,178 4,886, ,287 4,886, ,242 4,886, ,179 4,886, ,976 4,886, ,261 4,886, ,295 4,886, ,343 4,886, ,439 4,886, ,722 4,885, ,465 4,885, ,296 4,885, ,416 4,884, ,043 4,884, ,679 4,883, ,581 4,883, ,542 4,884, ,929 4,883, ,535 4,883, ,494 4,884, ,476 4,884, ,378 4,884, ,072 4,884, ,094 4,884, ,934 4,885, ,910 4,885, ,898 4,885, ,179 4,884, ,369 4,884, ,633 4,884, ,763 4,884, ,031 4,885, ,919 4,885, ,810 4,885, ,880 4,885, ,987 4,885, ,358 4,882, ,476 4,882, ,587 4,881, ,732 4,881, ,512 4,882, ,381 4,882, ,846 4,882, ,146 4,883, ,935 4,883, ,899 4,883, ,413 4,883, ,851 4,883, ,878 4,883, ,002 4,884, ,460 4,884, ,162 4,885, ,684 4,884, ,736 4,884, Continued on next page...

15 SHADOW - Main Result 01/27/07 15:22 / 5...continued from previous page UTM NAD27 Zone: 18 No. Name East North Z Width Height Height Degrees from Slope of a.g.l. south cw window [m] [m] [m] [m] [ ] [ ] ,622 4,886, ,758 4,885, ,068 4,888, ,511 4,882, ,398 4,882, ,137 4,882, ,998 4,883, ,785 4,883, ,982 4,883, ,044 4,883, ,247 4,883, ,308 4,884, ,057 4,885, ,311 4,885, ,361 4,885, ,517 4,885, ,756 4,885, ,641 4,885, ,824 4,885, ,040 4,886, ,483 4,884, ,410 4,884, ,980 4,884, ,043 4,884, ,085 4,884, ,868 4,884, ,799 4,884, ,535 4,884, ,252 4,884, ,139 4,884, ,837 4,884, ,869 4,884, ,972 4,884, ,981 4,885, ,026 4,884, ,624 4,887, ,558 4,886, ,111 4,889, ,250 4,884, ,145 4,883, ,208 4,882, ,613 4,884, ,421 4,885, ,572 4,885, Calculation Results Shadow, worst case Shadow, expected values No. Name Shadow hours Shadow days Max shadow Shadow hours per year per year hours per day per year [h/year] [days/year] [h/day] [h/year] : :24 2: : :24 2: : :30 6: : :44 12: : :50 17: : :36 4: : :42 13: : :18 1:00 Continued on next page...

16 SHADOW - Main Result 01/27/07 15:22 / 6...continued from previous page Shadow, worst case Shadow, expected values No. Name Shadow hours Shadow days Max shadow Shadow hours per year per year hours per day per year [h/year] [days/year] [h/day] [h/year] : :22 1: :00 0 0:00 0: :00 0 0:00 0: :00 0 0:00 0: : :38 5: : :34 7: : :40 9: : :44 7: : :42 11: : :48 12: : :52 14: : :46 6: : :50 5: : :44 16: : :26 2: :00 0 0:00 0: : :30 3: : :24 2: : :22 1: : :22 1: :00 0 0:00 0: :00 0 0:00 0: : :30 3: : :32 3: : :38 4: : :40 8: : :46 20: : :46 12: : :34 6: : :52 18: : :40 8: : :50 13: : :42 15: : :46 18: : :40 14: : :42 17: : :42 21: : :40 7: : :42 14: : :42 14: :00 0 0:00 0: : :34 4: : :40 11: :00 0 0:00 0: :00 0 0:00 0: :00 0 0:00 0: :00 0 0:00 0: : :22 1: : :26 2: : :36 9: : :52 20: : :42 16: :00 0 0:00 0: : :24 2: : :34 10: :00 0 0:00 0: :00 0 0:00 0: :00 0 0:00 0: : :28 3: : :58 14:59 Continued on next page...

17 SHADOW - Main Result 01/27/07 15:22 / 7...continued from previous page Shadow, worst case Shadow, expected values No. Name Shadow hours Shadow days Max shadow Shadow hours per year per year hours per day per year [h/year] [days/year] [h/day] [h/year] : :36 10: : :22 1: :00 0 0:00 0: :00 0 0:00 0: : :30 15: : :34 11: : :38 10: : :54 28: : :46 4: : :54 32: : :38 18: : :28 3: : :24 2: : :48 19: : :10 36: : :06 20: : :10 31: : :40 16: : :02 20: : :42 16: : :46 3: : :24 3: : :26 5: : :32 15: : :38 12: : :32 11: : :32 7: : :20 2: :20 5 0:04 0: : :46 10: : :02 11: : :34 13: : :06 12: : :52 11: : :50 10: :00 0 0:00 0: : :32 13: : :48 11: : :50 10: : :14 17: : :28 7: : :22 1: : :36 13: : :36 24: : :38 14: : :40 19: : :38 24: : :34 19: : :36 13: : :40 22: : :42 21: : :30 4: : :28 2: : :26 11: : :50 30: : :36 22: :00 0 0:00 0: : :26 5: : :34 6: : :28 10:07 Continued on next page...

18 SHADOW - Main Result 01/27/07 15:22 / 8...continued from previous page Shadow, worst case Shadow, expected values No. Name Shadow hours Shadow days Max shadow Shadow hours per year per year hours per day per year [h/year] [days/year] [h/day] [h/year] : :30 13: : :34 11: : :30 12: : :38 14: : :30 7: :00 0 0:00 0: :00 0 0:00 0: : :12 1: :00 0 0:00 0: :00 0 0:00 0: : :32 11: : :32 8: : :30 11: : :22 3: : :28 5: : :30 7: : :32 9: : :04 14: : :44 20: : :18 17: : :10 14: : :38 7: : :34 10: : :38 7: :00 0 0:00 0: :00 0 0:00 0: : :22 1: : :22 2: : :22 2: : :22 2: :00 0 0:00 0: :00 0 0:00 0: : :38 12: :00 0 0:00 0: : :00 17: : :06 15: : :00 12: : :52 19: : :56 13: : :58 17: : :46 15: :00 0 0:00 0: :00 0 0:00 0: :00 0 0:00 0: :00 0 0:00 0: :00 0 0:00 0: :00 0 0:00 0: :00 0 0:00 0: :00 0 0:00 0: : :26 3: : :38 7: : :24 5: : :36 4: : :02 13: : :34 6: : :36 8: : :44 3: : :58 13: : :24 2: :00 0 0:00 0:00 Continued on next page...

19 SHADOW - Main Result 01/27/07 15:22 / 9...continued from previous page Shadow, worst case Shadow, expected values No. Name Shadow hours Shadow days Max shadow Shadow hours per year per year hours per day per year [h/year] [days/year] [h/day] [h/year] :00 0 0:00 0: : :46 20: : :50 26: : :18 15: : :10 13:15