kingston, ma shadow flicker study elizabeth king wind analyst chester harvey gis specialist 256...
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Kingston, MAShadow Flicker Study
Elizabeth King Wind Analyst
Chester Harvey GIS Specialist
256 Farrell Farm Rd.Norwich, VT 05055Ph: 802.649.1511
Goals
1. Estimate shadow flicker timeby location
2. Estimate curtailment time required to meet example shadow flicker thresholds
3. Document areas withline-of-sight to turbine(s)
Site Overview• 5 Wind Turbines
• 1083 Receptors within 1.6 km of turbines
Methodology1. Desktop estimate of shadow flicker exposure
– Shadow flicker modeled using WindPRO
• Incorporates GIS terrain model, daily sun pathsbased on latitude, local weather data and wind data
– Receptors identified using aerial images & GIS data
– No tree or building obstacles are accounted for
2. Field documentation of line-of-sight
– Assessed by car from public streets
Flicker Modeling• Theoretical Worst Case
– Maximum possible shadow hours for a given location
– Sun always shining; wind turbines always operating
– Is a step in process for deriving realistic case estimates
• Realistic Case
– Incorporates sunshine probability and likely wind turbine operational hours
• Sunshine data, 61 years – Boston, MA (National Climatic Data Center)
• Wind data, 1 year (July 05 – July 06) – Kingston, MA (UMass Amherst)
Receptors
• 20 meters wide x 10 meters tall
– Intended to simulate the façade of a house
• Each receptor modeled so that it faces perpendicular to each wind turbine in each iteration of analysis (Greenhouse Mode)
Receptors
Receptors
10meters
tall
20 meters wide
Receptor area facing perpendicular to
direct line to turbineReceptor point at bottom-center of modeled receptor area
Shadow modeled on receptor area
1.5 m figure for scale
WindPRO Inputs
9
WindPRO Inputs
10
WindPRO Inputs
11
WindPRO Inputs
12
Isol
ines
sho
w s
hado
w fl
icke
r esti
mat
es d
eriv
ed fr
om a
real
istic
cas
e m
odel
usi
ng a
10
m g
rid re
solu
tion
Hours per Yearat 1.5 metersabove ground level
WindPRO Report
WindPRO Report
WindPRO ReportCalendar Graphs
Receptor A Receptor B
WindPRO Report
Flicker Results
Realistic Case
More Than 10 Hours per Year
of Flicker
More Than 30 Hours per Year
of Flicker
More Than 50 Hours per Year
of Flicker
Number of Receptors
Affected189 55 31
Number of Existing
Residential Receptors
Affected
121 38 24
Line-of-Sight Survey
• Assesses line-of-sight to each turbine from public streets within thestudy area
• Accounts for trees and buildings that block line-of-sight to turbines
• Line-of-sight results are not incorporated into modeling results
Photo 27
Curtailment Analysis
• Only receptors for existing residential structures are included
• Accounts for coincident flicker across multiple receptors
Curtailment ResultsRealistic Case Theoretical Worst Case
Estimated Curtailment Required for 10 hrs of
Flicker Per Year(h/yr)
Estimated Curtailment Required for Maximum
30 hrs of Flicker Per Year(h/yr)
NFF West(Gamesa 1)
94 286
NFF Southeast(Gamesa 2)
47 140
NFF North (Gamesa 3)
107 326
KWI (Hyundai)
126 366
MBTA (Northern Power)
6 14