Noise from Wind: 2 Types
1. Mechanical- the “humming sound” often heard from the generator, and a clicking sound from the movement inside the gearbox.
2. Aerodynamic- the sound caused by the movement of the blades through the air. The louder of the two, often described as a “swishing” sound.
Although topography and other conditions may affect noise levels, generally speaking the closer one is to the turbine the loader it will be.
There is no evidence that the noise from wind turbines has any negative impact on human health or well being.
Some nations in Europe (Sweden, Denmark, Germany) have noise limits for turbines at 40 dBA.
A 300 KW turbine produces about 40 dBA
Common sound examples and their decibel (dBA) levels:
Chain saw- 125 dBA
Car horn- 110 dBA
Dishwasher, washing machine, AC unit- 55-75 dBA
Refrigerator- 50 dBA
Suburb at night- 50 dBA
Quiet office, library- 40 dBA
Categories of Turbines
Horizontal Axis Wind Turbines (HAWT)
- The traditional 3 blade design, with the nacelle attaching to the main rotor shaft, housing the gearbox, and the generator at the top of the tower.
- The turbine is pointed upwind of the tower to counteract the turbulence produced from the blades.
- Must be pointed directly into the wind.
- Taller towers allow more and stronger winds to be captured by the blades.
- More efficient as the blades are capturing all of the wind through their rotation as they are perpendicular to the wind.
- Large space requirement due to tower.
- Require a yaw controller to control the speed of the blades to prevent the turbine from spinning out of control in high winds.
Vertical Axis Wind Turbines (VAWT)
- Have the main rotor shaft aligned vertically, with the generator at the base of the structure.
- Do not need to be directly into the wind.
- Smaller and less obtrusive
- Can be mounted to roof tops
- No yaw parts needed
- Receive slower wind, and thus produce less electricity
Darrieus – the egg beater shaped design
Savonius- the wind dragging design.
Compiled by Greg Gronski, Alternative Energy Research Assistant
Pederson et al., Noise Annoyance from Wind Turbines: A Review, 2003