Wind Turbines
Wind turbines converts the energy in wind into mechanical energy
which can be used directly by machinery such as a windmill or turned
into electricity through a generator.
Wind turbines can be separated into two types based by the axis in
which the turbine rotates. Turbines that rotate around a horizontal axis
are more common. Vertical-axis turbines are less frequently used.
Advantages of Horizontal Wind Turbines
- Variable blade pitch, allows adjustment for increased
efficiency.
- Taller towers means higher wind speeds and greater energy
output. Every ten meter hight will yield a 20% greater wind speed
and 34% greater power output.
Disadvantages of Horizontal Wind Turbines
- Horizontal Wind Turbines have difficulty operating near
turbulent ground winds.
- The tall towers and blades are difficult to transport.
- Tall Horizontal Wind Turbines are difficult to install.
- Tall Horizontal Wind Turbines may affect airport radar.
- Their height makes them visible across from a distance.
- Horizontal Wind Turbines require an additional yaw control to
turn the blades toward the wind.
Advantages of Vertical Wind Turbines
- No massive tower structure is needed.
- Rotor blades are vertical so no yaw mechanism is needed.
- Vertical Axis Wind Turbines can be constructed nearer the
ground, making maintenance easier.
- Vertical Axis Wind Turbines have better aerodynamics which
decreases drag.
- Straight bladed Vertical Axis Wind Turbine designs have a larger
swept area for a given diameter than the circular swept area of
Vertical Axis Wind Turbines.
- Vertical Axis Wind Turbines have lower wind startup speeds than
Horozontal Axis Wind Turbines. Typically, they start creating
electricity at about 10 km/h.
- Vertical Axis Wind Turbines are less likely to break in high
winds.
- Vertical Axis Wind Turbines situated close to the ground can
take advantage of locations that funnel the wind for increase wind
velocity and output.
- Vertical Axis Wind Turbine blades are more easily avoided by
birds.
Disadvantages of Vertical Wind Turbines
- Most Vertical Axis Wind Turbines only produces 50% of the
efficiency of Horizontal Axis Wind Turbines.
- Vertical Axis Wind Turbine can not take advantage of the
stronger wind at higher elevation.
- Most Vertical Axis Wind Turbines have low starting torque, and
may require energy to get them started.
- While Vertical Axis Wind Turbine parts are located on the
ground, they are also located under the weight of the structure
above it, which can make changing out parts very difficult for
poorly designed turbines..
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