Environmental Engineering Reference
In-Depth Information
Figure 4.13.
The inside of a wind turbine.
This simple explanation conceals the fact that a wind turbine is a highly complex
machine. Not only does it contain a variety of mechanical and electronic components that
convert the kinetic energy of the turning rotor into electricity, the blades themselves are a
marvelofengineering.Theyareusuallymadeofglassfibre,amaterialthatisbothlightand
durable, and are contoured to take maximum advantage of both drag and lift. Turbines are
also equipped with protective features - particularly braking systems - to avoid damage at
high wind speeds. The rotor is mounted on a tower high enough to avoid the air turbulence
caused by obstacles.
Wind speed is measured in metres per second (m/s) or kilometres per hour (km/h). It is
also measured using the Beaufort scale, ranging from 1 (a calm day) to 12 (hurricane). This
scaleclassifieswindspeednotonlyintermsofitsactualspeedbutbasedonitseffects(e.g.,
wave height at sea, destruction on land). The optimal conditions for wind power generation
vary depending on the size and type of turbine. Small turbines, including all VAWTs and
domestic HAWTs, begin to generate electricity in light winds of 2-3 metres per second
(force 2 on the Beaufort scale), operate optimally at medium wind speeds of 6-10 metres
