Post on 02-Jun-2018
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Topics in Public Acceptance
Human Impacts: Sound and Shadow Flicker
June 2011
Kenneth Kaliski, P.E., INCE Bd. Cert.New England Wind Energy Education ProjectWind Energy in New England:
Understanding the Issues Affecting PublicAcceptance
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Outline
Introduction to sound
Sound from wind turbines
Noise regulations in New England
Shadow flicker
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Hearing Sensitivities
Frequency
most sensitive to frequencies between 500 and4,000 Hz (speech frequencies)
-80
-60
-40
-20
0
20
1 10 100 1,000 10,000 100,000
Frequenc y (Hz)
S o u n
d P r e s s u r e
L e v e
l ( d B )
Human Hearing Response Curv e
Human Hearing Frequency RangeInfrasound Ultrasound
20 20,000
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Weighting Networks
-60
-50
-40
-30
-20
-10
0
10
20 40 80 160 315 630 1,250 2,500 5,000 10,000 20,000
Frequency (Hz)
R e
l a t i v e
R e s p o n s e
( d B )
dBA Correction
dBC Correction
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dBA Levels for Common EnvironmentsOccupational Noise Decibels (dBA)
Perception Measured at the ear Everyday Noise Transportation Noise
Near a jet engine
Threshold of Pain
Deafening
Hard Rock Band
Chainsaw
Table sawCircular sawBandsawImpact Wrench Auto horn at 10 feet
Electric hand drill Very Loud
SnowmobileRiding lawn mower, at ear
Street SweeperShop-vac, at ear, outdoors
Truck passby, 60 mph at 50 feet
Inside car, windows open, 65 mphTruck passby, 30 mph, at 50 feet
Vacuum cleaner, at earLoud
Playground recess (avg) Inside car, windows closed, 65 mph
Car passby, 30 mph, at 50 feetUrban Area
140
100
130
120
110
90
80
70
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Outline
Introduction to sound
Sound from wind turbines
Noise regulations in New England
Shadow flicker
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Typical evaluation process
Determine sound emissions
Monitor background sound levels inrepresentative areas (protocol-depending)
Conduct sound propagation modeling
Compare results to standards orguidelines
Mitigate, if necessary
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Determine sound power level of the turbine
40
50
60
70
8090
100
110
120
2 0 3 1
. 5 5 0 8 0 1 2 5
2 0 0
3 1 5
5 0 0
8 0 0
1 2 5 0
2 0 0 0
3 1 5 0
5 0 0 0
8 0 0 0
1/3 Octave Band Center Frequency
A - w
e i g h t e d S o u n
d P o w e r
L e v e
l ( d B A )
Weighted sound power
Unweighted sound power
Sound power ofvarious turbines
(different from soundpressure)
Sound power byfrequency
92949698
100102104106108110
112
0 500 1000 1500 2000 2500 3000 3500
S o u n
d P o w e r
L e v e
l ( d B A )
Turbine Output (kW)
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Noise generation from wind turbines
Modern wind turbines make
noiseSome mechanisms of noisegeneration
Broadband blade noise
Broadband and tonal hubnoise
Leading edge separation
Inflow turbulence
Surface boundary layer
Wake
Trailing edge flow
Tip vortex
wind
Time
f r e q u e n c y
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Issues exacerbating noise
Turbulent inflow primarily due to tight turbinespacing
Blade roughness (insects, tape, etc)
Deformations
Icing
Synchronized blade passage (primarily with singlespeed turbines)
Mechanical errors (pitch control)
Downwind towers (low frequency) not used muchanymore
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Noise Prediction
Modeling is typically done toestimate the maximumlevel, but we can also modelsound levels under otherconditions
The percentile sound levelsat a receiver is dependenton
The distribution of windspeed and direction overthe year
The placement of theturbines with respect tothe receiver
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0%10%20%30%40%50%60%70%80%90%
100%
15 20 25 30 35 40 45 50 55
P e r c e n
t o
f Y
e a r
E x p e c
t e
d t
o
E x c e e
d L
e v e
l
Sound Level (dBA)
Within 5 dB ofLmax 12% of theyear
Lmax
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Effects
Similar effects to other sources of noise at
high enough levelsAnnoyancePossibly sleep disturbanceOther
Is affected by non-acoustic factorsVisibilityAttitude
CompensationExperience
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Mitigation
Re-siting project turbines
Increase setbacks Increase spacing between turbines Identify quieter turbines or components
Automatic controls to slow tipspeeds/reduce noise under specificconditions
Improve noise insulation on target
homesIncrease the number of projectparticipants
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New developments
Sound emissions
New blade designs to reduce noiseSiting
Offshore wind turbinesEffects
Cross-sectional and dose response studies, etcSound prediction
New modeling techniques
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Range (m)
-3000 -2000 -1000 0 1000 2000 3000
0
100
200
10 20 30 40 50 60
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Outline
Introduction to sound
Sound from wind turbines
Noise regulations in New England
Shadow flicker
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What can be regulated
Total level
Usually expressed in units of A-weighted decibelsLevel by frequency
Full or 1/3 octave bandsTonality
Pure tone penalties and limitationsImpulsiveness
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New England States Wind Turbine Noise Regs
Maine
Statewide Site LawNew Hampshire
Site Evaluation CommitteeVermont
Section 248, Public Service BoardMassachusetts
AQCD Noise PolicyConnecticut
Statewide noise regulations
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Outline
Introduction to sound
Sound from wind turbines
Noise regulations in New England
Shadow flicker
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Shadow Flicker
What is shadow flicker?
Alternating changes in light intensity that canoccur at times when the rotating blades of windturbines cast moving shadows on the ground or onstructures (Thomas Priestley, CH2MHill, NEWEEP Webinar #5)
For and individual structure, S.F. only occursWhen sun is shining, and at a narrow angle rangeWhen blades are rotating
When no obstructions are presentEffects
Too slow to create epileptic seizuresCreates annoyance if prevalent
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Kenneth Kaliski, P.E., INCE Bd. Cert.
Resource Systems Group, Inc.
55 Railroad RowWhite River Junction, VT 05001
kkaliski@rsginc.com
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