Wind Power: Where Eagles Don’t Dare - Environmental Impacts of Renewable Energy - page 19

DID YOU KNOW?
During rotation of the nacelle, the cables inside the tower can twist, with the
cables becoming more and more twisted if the turbine keeps turning in the same
direction, which can happen if the wind keeps changing in the same direction.
The wind turbine is therefore equipped with a cable twist counter, which notifies
the controller that it is time to straighten the cables (Khaligh and Onar, 2010).
High-speed shaft —The shaft that drives the generator.
Low-speed shaft —A shaft that turns at about 30 to 60 rotations per minute.
Nacelle —Unit that sits atop the tower and contains the gearbox, generator,
low- and high-speed shafts, controller, and brake.
Pitch —Blades are turned, or pitched, out of the wind to control the rotor speed
and keep the rotor turning in winds that are too high or too low to produce
ele ct r icit y.
Rotor —Comprised of the blades and the hub.
Tower —Made from tubular steel, concrete, or steel lattice. Because wind
speed increases with height, taller towers enable turbines to capture more
energy and generate more electricity.
Wind direction —An upwind turbine operates facing into the wind; other tur-
bines are designed to run downwind, facing away from the wind.
Wind vane —Measures wind direction and communicates with the yaw drive
to orient the turbine properly with respect to the wind.
Yaw drive —In upwind turbines, this is used to keep the entire nacelle and thus
the rotor facing into the wind as the wind direction changes. Downwind
turbines do not require a yaw drive, as the wind blows the rotor downwind.
Yaw motor —Powers the yaw drive.
WIND ENERGY SITE EVALUATION IMPACTS
Site evaluation phase activities, such as monitoring and testing, are temporary and
are conducted at a smaller scale than those at the construction and operation phases.
Potential impacts of these activities are presented below by type of affected resource.
The impacts described are for typical site evaluation and exploration activities, such
as ground clearing (removal of vegetative cover), vehicular and pedestrian traffic,
borings for geotechnical surveys and guy wire installation, and positioning of equip-
ment, such as meteorological towers. If excavation of road construction is necessary
during this phase, potential impacts would be similar in character to those for the
construction phase, but generally of smaller magnitude.
A ir Q uAlity
Impacts on air quality during monitoring and testing activities would be limited to tem-
porary and local generation of vehicle emissions and fugitive dust. These impacts are
unlikely to cause an exceedance of air quality standards or to impact climate change.