Shadow-Flicker Impact Assessment - Project - Amherst Island Wind

36 Pages·2013·2.39 MB·English

by  Joaquin E. Moran

Algonquin Power Co.

Shadow Flicker Impact Assessment

For

Amherst Island Wind Project

H340642-0000-50-124-0001
Rev. 2
February 26, 2013

Algonquin Power Co. (on behalf of Windlectric Inc.) voluntarily authorized the development of this report. This report is not a
requirement of O. Reg. 359/09 and as such is not a required component for a Renewable Energy Approval application.
Algonquin Power Co. (on behalf of Windlectric Inc.) voluntarily authorized the development of this report. This report is not a
requirement of O. Reg. 359/09 and as such is not a required component for a Renewable Energy Approval application.

Algonquin Power Co. - Amherst Island Wind Project
Shadow-Flicker Impact Assessment

Project Report

February 26, 2013
Algonquin Power Co.
Amherst Island Wind Project
DISTRIBUTION
Homer Lensink – Algonquin Power
Alex Tsopelas – Algonquin Power
Sean Fairfield – Algonquin Power
Rick Harrop – Algonquin Power
Bob Ilett – Hatch Ltd.
Joaquin Moran – Hatch Ltd.

Shadow-Flicker Impact Assessment

Feb 26/2013 2 Approved

J. Moran R. Ilett A. Tsopelas
Date Rev. Status Prepared By Checked By Approved By
Client

H340642-0000-50-124-0001, Rev. 2
Page i
© Hatch 2013/02
Algonquin Power Co. (on behalf of Windlectric Inc.) voluntarily authorized the development of this report. This report is not a
requirement of O. Reg. 359/09 and as such is not a required component for a Renewable Energy Approval application.

Algonquin Power Co. - Amherst Island Wind Project
Shadow-Flicker Impact Assessment

Table of Contents
1. Introduction ............................................................................................................................................ 1
2. Shadow Modeling .................................................................................................................................... 1
2.1 Model Description ......................................................................................................................... 1
2.2 SHADOW – The Shadow-Flicker Module ...................................................................................... 1
2.3 Model Setup and Calculation Procedure ........................................................................................ 1
2.4 Shadow-Flicker Guidelines and Model Assumptions ...................................................................... 3
3. Shadow Flicker Impact Results ................................................................................................................ 4
3.1 Astronomical Shadow – Worst Case Scenario ................................................................................ 4
3.2 Meteorological Probable Shadow – Real Case ................................................................................ 4
4. Summary ................................................................................................................................................. 5
5. References ............................................................................................................................................... 5

List of Tables

Table 1: Sunshine Statistics – Kingston A (WMO ID 71620) .......................................................................... 5

List of Figures

Figure 1: Schematic Diagram of Shadow Cast from a Wind Turbine on a Receptor ........................................ 2

Appendix A Wind Turbine Layout and Shadow Reports
Appendix B Shadow Flicker Impact Results
Appendix C Shadow Flicker Impact Map
Appendix D Summary of Wind Data – Meteorological Shadow

H340642-0000-50-124-0001, Rev. 2
Page i
© Hatch 2013/02
Algonquin Power Co. (on behalf of Windlectric Inc.) voluntarily authorized the development of this report. This report is not a
requirement of O. Reg. 359/09 and as such is not a required component for a Renewable Energy Approval application.

Algonquin Power Co. - Amherst Island Wind Project
Shadow-Flicker Impact Assessment

Report Disclaimer
This report has been prepared by Hatch Ltd. (Hatch) for the sole and exclusive use of Algonquin Power Co.
(the “Client”) for the purpose of assisting the management of the Client in making decisions with respect to
the Amherst Island Wind Project, and shall not be (a) used for any other purpose, or (b) provided to, relied
upon or used by any third party.
This report contains opinions, conclusions and recommendations made by Hatch, using its professional
judgment and reasonable care. Use of or reliance upon this report by Client is subject to the following
conditions:
(a) the report being read in the context of and subject to the terms of the agreement between Hatch and the
Client dated January 20, 2012 (the “Agreement”), including any methodologies, procedures, techniques,
assumptions and other relevant terms or conditions that were specified or agreed therein;
(b) the report being read as a whole, with sections or parts hereof read or relied upon in context;
(c) the conditions of the site may change over time or may have already changed due to natural forces or
human intervention, and Hatch takes no responsibility for the impact that such changes may have on the
accuracy or validity or the observations, conclusions and recommendations set out in this report; and
(d) the report is based on information made available to Hatch by the Client or by certain third parties
(Siemens, Land Information Ontario, LIO), including publicly available information; and unless stated
otherwise in the Agreement, Hatch has not verified the accuracy, completeness or validity of such
information, makes no representation regarding its accuracy and hereby disclaims any liability in
connection therewith.

H340642-0000-50-124-0001, Rev. 2
Page ii
© Hatch 2013/02
Algonquin Power Co. (on behalf of Windlectric Inc.) voluntarily authorized the development of this report. This report is not a
requirement of O. Reg. 359/09 and as such is not a required component for a Renewable Energy Approval application.

Algonquin Power Co. - Amherst Island Wind Project
Shadow-Flicker Impact Assessment

1. Introduction
Hatch was retained by Algonquin Power Co. (Algonquin) to carry out a shadow-flicker impact
assessment for the 75-MW Amherst Island Wind Project. This memorandum presents a
description of the methodology used and results obtained in the assessment of the project,
located in the Loyalist Township, Ontario. Algonquin Power Co. (on behalf of Windlectric Inc.)
voluntarily authorized the development of this report. This report is not a requirement of O.
Reg. 359/09 and as such is not a required component for a Renewable Energy Approval
application.
The project consists of thirty six (36) wind turbine generators. The turbines will be manufactured
by Siemens, and will correspond to model SWT 2.3-113. The rated capacity of the turbines is
2.3 MW, with a rotor diameter of 113 m, located at 99.5 m above ground level.
2. Shadow Modeling
2.1 Model Description
WindPRO, a commercial software developed by EMD International A/S (EMD) (www.emd.dk)
was used to determine the shadow-flicker impact on receptors surrounding and within the wind
farm boundaries. WindPRO is a fully integrated modular software package that is recognized
and accepted worldwide by developers, planners, utilities and wind turbine manufacturers. The
model is widely used for design and planning of large wind farms.
2.2 SHADOW – The Shadow-Flicker Module
SHADOW is the WindPRO calculation module that estimates how often and in which intervals a
specific neighbour or area will be affected by shadows generated by one or more wind turbines.
These calculations are usually worst-case scenarios (astronomical maximum shadow,
e.g., calculations which are solely based on the positions of the sun relative to the wind turbine).
Shadow impact may occur when the blades of a wind turbine pass through the sun’s rays as seen
from a specific position (e.g., a window in an adjacent settlement). If the weather is overcast or
calm, or if the wind direction forces the rotor plane of the wind turbine to stand parallel with the
line between the sun and the neighbour, the wind turbine will not produce shadow flicker, but
the impact will still appear in the calculations. The calculation of the worst-case scenario
represents the maximum potential risk of shadow impact.
Apart from calculating the potential shadow impact at a given location, Hatch has created maps
rendering the isolines of the shadow impact (see Appendices C and D). The maps show the
areas where shadow impact is expected to be higher than the suggested guidelines.
2.3 Model Setup and Calculation Procedure
For the shadow-flicker calculations, the model utilizes the position of the sun relative to the wind
turbine rotor disk, and the resulting shadow is calculated in steps of 1 minute throughout a
complete year. If the shadow of the rotor disk (which in the calculation is assumed solid) at any
time casts a shadow reflection on a shadow receptor object, then this step will be registered as
1 minute of potential shadow impact (see Figure 1). A shadow receptor object is defined as a
window with a certain orientation and dimensions.

H340642-0000-50-124-0001, Rev. 2
Page 1
© Hatch 2013/02
Algonquin Power Co. (on behalf of Windlectric Inc.) voluntarily authorized the development of this report. This report is not a
requirement of O. Reg. 359/09 and as such is not a required component for a Renewable Energy Approval application.

Algonquin Power Co. - Amherst Island Wind Project
Shadow-Flicker Impact Assessment

The parameters required for the calculations are as follows:
1. Location of the wind turbines
2. Hub height and rotor diameter
3. Position (coordinates) of the shadow receptors
4. Typical size of the window and its orientation, both directional (relative to south) and
inclination (angle of window plane to the horizontal)
5. Geographic position and time zone of the project area
6. Simulation model, which holds information about the earth’s orbit and rotation relative to
the sun.

Figure 1 : Schematic Diagram of Shadow Cast from a Wind Turbine on a Receptor
Two cases of shadow can be explored using the WindPRO model: the “Astronomical maximum
shadow” (also called worst-case shadow) and the “Meteorological probable shadow” (also called
real shadow). The astronomical or “worst case” shadow assumes that every day of the year is a
sunny, clear day. The real shadow considers the hours of sun light that are typical for every
month, as well as the wind direction and speed. In practical terms, two statistical parameters
should be provided:
• Operational hours statistics – This is the period that the wind turbine will be in operation
from the different wind directions during the year.
• Sunshine probability statistics – This is the percentage of sunshine hours in daytime (from
sunrise to sunset).

H340642-0000-50-124-0001, Rev. 2
Page 2
© Hatch 2013/02
Algonquin Power Co. (on behalf of Windlectric Inc.) voluntarily authorized the development of this report. This report is not a
requirement of O. Reg. 359/09 and as such is not a required component for a Renewable Energy Approval application.

Algonquin Power Co. - Amherst Island Wind Project
Shadow-Flicker Impact Assessment

For this project, the primary inputs consisted of a digital elevation model that spans the entire
area of interest and the locations of shadow receptors and wind turbine generators. The contours
were provided by Land Information Ontario (LIO) in 2011. For the estimation of the real
shadow, the wind speed data has been gathered using three meteorological masts installed on
the island from 2005 to 2008. The wind data is required to determine the time periods where
the turbine is moving and the position of the rotor plane relative to the receptors. If the turbine
is not moving, no shadow flicker is produced.
The location of receptors and wind turbine generators is shown in Figure A.1, Appendix A. The
total number of receptors considered is 427, and their location was based on the existing noise
receptors associated to the Amherst Island Wind Project.
2.4 Shadow-Flicker Guidelines and Model Assumptions
At present, only Germany has detailed guidelines on limits and conditions for calculating
shadow impact [Ref 1]. Denmark and Sweden have some guidelines, but they are for practical
purposes only. According to the German guidelines, the limit of the shadow is set by two
factors:
1. The angle of the sun over the horizon must be at least 3 degrees.
2. The blade of the wind turbine must cover at least 20% of the sun.
The maximum shadow impact on a neighbour from a wind farm according to the German
guidelines should be:
• maximum 30 h/yr of astronomical maximum shadow (worst case)
• maximum 30 minutes worst day of astronomical maximum shadow (worst case).
Demark and Sweden suggest a threshold of 10 and 8 h/yr respectively if the sunshine statistics or
cloud cover index are included in the shadow calculations. In this case, the SHADOW module
of WindPRO was used to determine the time intervals (maximum hours per year and minutes per
day) in which the presence of the wind turbines could cast shadows over nearby receptors based
on the German guidelines. The assumptions used for the shadow modelling were:
1. Wind turbines are Siemens SWT-2.3, with a rotor diameter of 113 m and hub height of
99.5 m
2. The shadow flicker receptors locations are based on existing potential receptors on the
island
3. Window at the receptor is assumed to be facing perpendicular to the wind turbines (worst
case).
4. Window dimensions considered: 1 m x 1 m, at 1 m from the ground. The window was
oriented at 90 degrees (normal vertical window)
5. Both cases (Astronomical shadow and Real Shadow) were calculated.

H340642-0000-50-124-0001, Rev. 2
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© Hatch 2013/02
Algonquin Power Co. (on behalf of Windlectric Inc.) voluntarily authorized the development of this report. This report is not a
requirement of O. Reg. 359/09 and as such is not a required component for a Renewable Energy Approval application.

Algonquin Power Co. - Amherst Island Wind Project
Shadow-Flicker Impact Assessment

3. Shadow Flicker Impact Results
3.1 Astronomical Shadow – Worst Case Scenario
The shadow flicker results for each of the receptors are presented in Table B.1, Appendix B.
For the worst case scenario, a total of 48 receptors are above the recommended hours-per-year
(30 h/yr) and 60 exceed the shadow minutes-per-day. Most of the receptors that do not comply
with the hours of shadow per year also exceed on a min/day basis (42). In addition to Table B.1,
the shadow-flicker results from WindPRO can be presented as a shadow map (shown in
Figure C.1, Appendix C). The shadow map allows for a quick qualitative observation of the
shadow receptors, presenting the different levels of shadow flicker impact in hours/year.
Figures C.2 present the “shadow flicker calendar” for the Amherst Island Wind Project, which
indicates the approximate hours of the day and months of the year where the flicker impact from
each turbine may potentially affect certain locations. These figures are for reference purposes
and were derived based on the worst-case shadow scenario presented in Table B.1. It can be
seen that shadows are potentially cast mostly during sunrise and sunset, when the sunlight is
diffuse (rather than direct) and with lower intensity than in the middle of the day.
3.2 Meteorological Probable Shadow – Real Case
In order to determine shadow-flicker impact on potential receptors, based on the Danish
guidelines, the local meteorological conditions were taken into consideration. This method
considers both the time where the wind is not blowing and the sky conditions above the project
area. Since sunshine data was not available at the site, the sunshine statistics were taken from
the Kingston A Weather Station (Climate Normals, 1971-2000), which is located less than 10 km
away from the project site. Table 1 presents the sunshine statistics used in the calculations as a
percentage of daylight hours. The wind speed frequency distribution and direction are shown in
Appendix D.
Table B.1 shows the shadow flicker results for the meteorological shadow case. Based on the
Danish guidelines (of 10 h/yr), the number of potentially affected receptors decreases from 48 to
19. This assessment can be further refined by describing more accurately the location and
orientation of the windows. Note that the SHADOW module of WindPRO does not estimate the
shadow minutes per day for the real shadow case, given that the sunshine statistics are recorded
in a per month basis. The shadow map for the meteorological shadow case is shown in
Figure C.1, Appendix C.

H340642-0000-50-124-0001, Rev. 2
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© Hatch 2013/02
Algonquin Power Co. (on behalf of Windlectric Inc.) voluntarily authorized the development of this report. This report is not a
requirement of O. Reg. 359/09 and as such is not a required component for a Renewable Energy Approval application.

Algonquin Power Co. - Amherst Island Wind Project
Shadow-Flicker Impact Assessment

Table 1: Sunshine Statistics – Kingston A (WMO ID 71620)
Month Total Hours of Days with % of Possible

Jan 66 21.2 33.1

Feb 92 21.8 40.4
Mar 120 23.4 38.2
Apr 162 24.8 43.8
May 221 27.8 48.6
Jun 243 28.0 52.5
Jul 262 29.9 59.7
Aug 222 29.4 55.7
Sep 163 26.0 43.3
Oct 128 26.1 42.8
Nov 70 21.0 30.4
Dec 52 19.5 27.1

4. Summary
Algonquin power Co. (on behalf of Windlectric Inc.) voluntarily authorized the development of
this report. This report is not a requirement of O. Reg. 359/09 and as such is not a required
component for a Renewable Energy Approval application. Hatch undertook the shadow flicker
assessment using the two guidelines referenced in previous sections, however, the
meteorological probable shadow methodology (using the sunshine statistics provide by
Environment Canada) is the most practical. The results of the use of the meteorological probable
shadow real case suggest that 19 receptors are above 10 hr/yr. Please note the following:
1. Five (5) of the 19 receptors are between 10.0-11.0 h/year (one receptor is a participant)
3. Five (6) of the 19 receptors are between 11.1-12.6 h/year
4. Four (4) of the 19 receptors are between 12.7 -15.8 h/year
5. Two (2) of the 19 receptors are between 15.9 -18.9 h/year
6. One (1) of the 19 receptors is between 18.9 -21 h/year
7. One (1) of the 19 receptors is between 35 -37.3 h/year (participating).
For the potential shadow receptors, the number of shadow hours per year could be further
refined by defining the real window orientation and size for each case.
5. References
[1] EMD International A/S. WindPRO 2.6 User Guide. Denmark, 2008.

H340642-0000-50-124-0001, Rev. 2
Page 5
© Hatch 2013/02
Algonquin Power Co. (on behalf of Windlectric Inc.) voluntarily authorized the development of this report. This report is not a
requirement of O. Reg. 359/09 and as such is not a required component for a Renewable Energy Approval application.

Algonquin Power Co. - Amherst Island Wind Project
Shadow-Flicker Impact Assessment

Appendix A
Wind Turbine Layout and Shadow Receptors

H340642-0000-50-124-0001, Rev. 2

© Hatch 2013/02