Kenneth Kaliski Slides 6.7.11

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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




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




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




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

[email protected]

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Kenneth Kaliski Slides 6.7.11

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