Page 283 - Fluid Power Engineering

250 Chapter Twelve

Greenhouse Gas Emissions, kg/MWh
Type of fuel CO 2 NO x SO 2
Coal 992 2.2 4.9
Natural gas 538 0.8 0.1
System average 631 1.4 2.7

Source: From Environmental Impacts of Wind Energy Projects, The National Academies
Press, Washington, DC, 2007.
TABLE 12-1 Emission of Greenhouse Gases for Electrical Generating Units in
Year 2000

In addition to the greenhouse gases, the following are produced: 2
34 kg/MWh of flying ash, 5.1 kg/MWh of bottom ash, and 8.9 kg/
MWh of gypsum.
These pollutants have significant impact on wildlife and humans.
Other environmental impacts that are common to fossil fuel-based
and wind-power plants are: 1
Clearing of vegetation to construct plant and access roads.

Both types of plant impact the environment; the relative dif-
ference is difficult to quantify.
Aesthetics of scenic areas or visibility from public areas like

highways, public parks, and others. Both types of plants im-
pact the aesthetics. Wind plants occupy a larger area of land
and, therefore, larger areas are impacted.

Impact of Wind Farms on Wildlife
There are two primary impacts on wildlife: (a) Bird and bat fatalities,
and (b) impact on land-based animals because of forest clearing and
changes in forest structure.
It was believed that wind turbines cause fatalities in birds and
bats primarily through impact with rotating blades. Recently, a study
revealed that fatalities in bats happen through barotrauma when bats
3
enter zones of rapid decrease in air pressure near blades. According
to the report, “Barotrauma involves tissue damage to air-containing
structures caused by rapid or excessive pressure change; pulmonary
barotraumas is lung damage due to expansion of air in the lungs that
is not accommodated by exhalation.”
In contrast to bats, birds are vulnerable to collision with turbine
1
blades. The following information is from the NRDC report: 6% of
the reported fatalities are of raptors; other species with the highest rate
of reported fatalities are the nocturnally migrating passerines. Species