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Kingston, MA Shadow Flicker Study. Elizabeth King Wind Analyst Chester Harvey GIS Specialist 256 Farrell Farm Rd. Norwich, VT 05055 Ph: 802.649.1511. Goals. Estimate shadow flicker time by location Estimate curtailment time required to meet example shadow flicker thresholds
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Kingston, MAShadow Flicker Study Elizabeth King Wind Analyst Chester Harvey GIS Specialist 256 Farrell Farm Rd. Norwich, VT 05055 Ph: 802.649.1511
Goals Estimate shadow flicker timeby location Estimate curtailment time required to meet example shadow flicker thresholds Document areas withline-of-sight to turbine(s)
Site Overview • 5 Wind Turbines • 1083 Receptors within 1.6 km of turbines
Methodology • 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 • 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 20 meters wide 10 meters tall Shadow modeled on receptor area Receptor area facing perpendicular to direct line to turbine 1.5 m figure for scale Receptor point at bottom-center of modeled receptor area
Hours per Yearat 1.5 metersabove ground level Isolines show shadow flicker estimates derived from a realistic casemodel using a 10 m grid resolution
WindPRO Report Calendar Graphs Receptor A Receptor B
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
Curtailment Analysis • Only receptors for existing residential structures are included • Accounts for coincident flicker across multiple receptors