We have a residential wind turbine at Guilden Gate. An ISKRA http://www.iskrawind.com/index.htm 12 metre freestanding tower, grid-connected, wind turbine collects kinetic energy from the wind and converts it to electricity. As turbine output increases and the amount of power purchased from the utility is proportionately decreased. When the turbine produces more power than the cottage needs, the extra electricity is sold back into the grid. All of this is done automatically. There are no batteries in a modern grid linked residential wind system.

Noise from wind turbines

Compared to the noise of road traffic, trains, aircraft, construction activities and many other sources of noise, the noise from residential wind turbines is very low. There are two potential sources of noise from a wind turbine: Mechanical noise from the gearbox or generator, and aerodynamic noise from the rotor blades.

Mechanical noise has virtually disappeared from modern wind turbines. This is due to better engineering with more concern about avoiding vibrations. Other technical improvements include elastically dampened fastenings and couplings of the major components in the nacelle, and to a certain extent sound insulation. The basic components themselves, including gearboxes have developed considerably over the years. Modern wind turbine gearboxes use "soft" gearwheels, i.e. toothed wheels with hardened surfaces and relatively elastic interiors.

Aerodynamic noise i.e. the "swish" sound of the rotor blades passing the tower of a wind turbine primarily arises at the tip and the back edge of the rotor blade. Modern wind turbines have become very quiet. The swishing sound of rotor blades is usually masked completely by background wind noise especially where leafy trees or shrubs are nearby. Obviously the higher the rotational speed, the louder the sound, but, the higher the wind speed the louder the background masking noise. Aerodynamic noise has been cut dramatically during the past ten years due to better design of rotor blades (particularly blade tips and back edges). Pure tones can be very annoying to a listener, while "white noise" is hardly noticed at all. Rotor blade manufacturers take extreme care to ensure a smooth surface which is important to avoid pure tones. Wind turbines do not interfere with TV reception.