Environmental Engineering Reference
In-Depth Information
to wind power development, there are documented cases where concerns
over impairment of existing ecosystems have also catalyzed social opposi-
tion to wind power developments.
Many attractive wind power sites are located in ecologically sensitive
areas.
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Rural or ofshore sites that are often richer in biodiversity appeal to
wind project developers thanks to lower land costs and lower risks of public
opposition.
66
Although coastal areas, mountain ridges, and mountain passes
all present attractive siting options due to superior wind quality,
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they are
often among the most ecologically precious. In many countries, coastal areas
are extensively developed and few undeveloped sites remain. Erecting wind
farms in such areas can close of important migration corridors for keystone
species that bridge coastal and inland habitats.
68
Similarly, mountain passes
are often attractive wind power sites due to wind channels inherent to such
passes; unfortunately, wind channels also serve as avian light paths.
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2.6.1 Bird Mortality
Bird mortality is perhaps the most notorious of the ecological threats that
wind farms pose. It is not uncommon for wind project developers to be con-
fronted with public concern or even active protest over threats to the avian
population.
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Statistically, as Table 2.1 illustrates, pollution, electrocution, collisions
with vehicles or buildings, and collisions with electricity infrastructure asso-
ciated with conventional power grid operations cause far more bird deaths
than do collisions with wind turbines.
71
A study in 2001 conducted by the
US National Wind Coordinating Committee estimated that there were
6,400 bird fatalities associated with 3,500 wind turbines investigated by the
study.
72
Generally, research indicates that it is not the absolute number of
bird kills, but rather, the rarity or ecological sensitivity of speciic avian spe-
cies that fuels the staunchest opposition to wind energy projects.
Despite low avian mortality rates, misperceptions fuelled by planning
laws associated with wind farms of the 1970s and 1980s can still fan
the lames of protest. Early turbine models were erected on lattice tow-
ers which provided a nesting ground for birds.
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However, newer turbine
models are mounted on pylon-style towers which are not conducive to nest-
ing.
74
Unfortunately, although the primary causes of avian fatalities have
been signiicantly mitigated by improved tower construction, larger rotor
blades that spin at a slower pace and improved siting strategies, the stigma
remains that wind turbines pose unacceptably large threats to avian popula-
tions. Community engagement supported by avian impact assessments can
help difuse such dissonance.
