build a wind turbine with your neighbours. Understand your neighbours' natural fear
of the unknown and be prepared to respond to their concerns.
Some of the concerns raised about wind turbines are untrue. Wind turbines are not, as
many people believe, dangerous to birds. A sliding glass door is more dangerous to
birds than a small wind turbine. The risk can be minimised further by painting the tips
of the blades so that they can be seen easily when spinning fast. Wind turbines have a
very low potential to interfere with radio and television reception. All modern
turbines, large and small, have blades made of fibreglass or wood. These materials are
transparent to electromagnetic waves such as radio and television.
Wind turbine noise
Your neighbours' concerns relating to wind turbine noise are important. No matter the
size of the wind turbine, the potential for turbine noise to bother other people always
exists. Even if a wind turbine does not emit enough sound to violate any noise
regulations, the noise it produces may still be objectionable to other people. Before
building a wind turbine, familiarize yourself with the types of noise your wind turbine
could make:
•
Aerodynamic noises may be made by the flow of air over and past the blades
of the turbine. Such noises tend to increase with the speed of the rotor. For
blade noise, lower blade tip speed results in lower noise levels. Of particular
concern is the interaction of wind turbine blades with atmospheric turbulence,
which results in a characteristic "whooshing" sound.
•
Mechanical noises may also be produced by components of a wind turbine.
Normal wear and tear, poor component designs or lack of preventative
maintenance may all be factors affecting the amount of mechanical noise
produced.
How loud might a wind turbine be?
At a distance of 250 m, a typical wind turbine produces a sound pressure level of
about 45 dB(A) (decibels). As the diagram below shows, this sound level is below the
background noise level produced in a home or office. Most small wind turbines, in
fact, make less noise than a residential air conditioner.
Small wind turbines
The blades rotate at an average range of 175-500 revolutions per minute with some as
high as 1150 rpm. Large turbines turbine blades rotate in the range of at 50-15 rpm at
constant speed, although an increasing number of machines operate at a variable
speed.
