Environmental Impacts of Wind Energy Development

1
Environmental Impacts of Wind Energy Development

• Charles P. Nicholson
• Tennessee Valley Authority
• Knoxville, TN

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Approach

• Description of windfarm construction
• Overview of potential environmental issues
• Detailed description of major environmental
  concerns
• Emphasis on windfarms in eastern U.S.

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Basic Windfarm Components

• Access road to site and roads connecting wind
  turbines
• Wind turbines
• Meteorological tower
• Electrical substation
• Electrical connections between turbines and
  substation
• Connection to area electrical grid
• Communications system

4
Access Roads

• Heavy duty, all-weather road to site, with gentle
  grade and broad turns
• 15-20 wide service road between wind turbines

5
Wind Turbines and Substation

• Cleared area of ½ to 1 acre around base of each
  turbine
• Smaller graded area for turbine foundation,
  construction crane
• Excavations for turbine foundations,
  transformers, substation components
• Fencing around base of turbines, substation

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Wind Turbine Construction
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Electrical Connections

• Electrical and communications cables connecting
  wind turbines and substation typically buried
• Overhead electrical line from windfarm site to
  area electrical grid
• Type of overhead line depends on size of windfarm
  and voltage at point of connection to grid

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Potential Environmental Concerns

• Geology and soils
• Surface water resources
• Ground water resources
• Air quality
• Biological resources
• Noise
• Visual resources

• Transportation
• Land use
• Hazardous materials
• Cultural resources
• Socioeconomics
• Environmental justice
• Health and safety

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Major Environmental Concerns

• Noise
• Land Use
• Visual Resources
• Biological Resources
• Threatened and endangered species
• Vegetation
• Wildlife, including bird mortality

10
Noise

• Construction noise typical noise from heavy
  equipment operation, blasting for foundation
  construction
• Operations noise typical levels
• 100 dBA at base of turbine
• 53 dBA 330 feet from turbine
• 35 dBA ½ mile from turbine
• Typical background noise levels for rural area
  40-50 dBA day, 30-40 dBA night

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Land Use

• Is windfarm compatible with existing zoning and
  land use plans?
• If area not zoned, is windfarm compatible with
  surrounding land uses?
• Most farming, recreational, resource management
  activities compatible with windfarm operation

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Visual Resources

• Modern wind turbines up to 380 feet tall
• White or off-white color
• Flashing lights on turbine towers for aviation
  safety
• Therefore, they are visually prominent

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Visual Resources
Simulation of view of formerly proposed Stone
Mountain, TN windfarm from top of Beech Mountain,
NC
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Biological Resources Threatened Endangered
Species

• Potential impacts are site-specific and primarily
  related to construction activities
• Many mountain-top sites in southeast have
  potential for TE species to be present
• Impacts may be avoided by proper siting studies

15
Biological Resources - Vegetation

• Potential impacts are site-specific and primarily
  related to construction activities
• Much of area cleared for turbine construction can
  revegetate
• Only small area around base of turbine and access
  roads maintained as open areas

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Biological Resources - Wildlife

• Some loss of wildlife habitat from windfarm
  construction
• More prominent issue is bird mortality from
  collisions with wind turbines
• Mortality issue has been intensively studied at
  windfarms in western and mid-western US
• Mortality issue less studied in eastern US

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Biological Resources - Wildlife

• Overall average mortality rate of 2.2
  birds/turbine/year for US windfarms
• Raptor (eagles, hawks, owls) mortality very
  localized high at Altamont Pass, CA, very low
  elsewhere
• Consensus that bird mortality not significant at
  most windfarms
• Are mortality study results from west and
  mid-west applicable to eastern windfarms?

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Western and Mid-western Windfarms
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Eastern Windfarms
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Biological Resources - Wildlife

• Short-term monitoring of windfarms in Vermont and
  Pennsylvania showed no mortality
• Only long-term monitoring in east is at TVA
  Buffalo Mountain Windfarm (10/2000-present)
• Adjusted mortality rate of 9 birds/turbine/year
• Additional 13 birds/year killed at met tower

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Biological Resources - Wildlife Buffalo
Mountain Windfarm Bird Mortality

• Most mortality during spring and fall migration
• Most mortality apparently at night
• No raptor mortality
• All birds killed were songbirds except for a rail
  and a cuckoo

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Biological Resources - Wildlife

• Bat Mortality May Be Issue Of Concern
• Has been studied at 9 windfarms in US
• For windfarms in west and mid-west, mortality
  rates 0.07-2.3 bats/turbine/year
• For TVA Buffalo Mountain Windfarm, mortality rate
  of 28 bats/turbine/year

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Biological Resources Wildlife Bat Mortality
May Be Issue Of Concern

• Most mortality during late summer, when bats
  dispersing, migrating
• Most mortality of larger tree-dwelling species,
  not smaller cave-dwelling species
• No mortality of endangered bats
• Bat studies ongoing at Buffalo Mountain

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Guidance on Windfarm Environmental Impacts

• Guidance documents available from NWCC
• US Fish Wildlife Service is issuing draft
  guidance on bird mortality issue