sexta-feira, 11 de novembro de 2011

Geradores eólicos e o ruído


How Loud is a Wind Turbine?



Because wind turbines are such a great source of clean, renewable energy, they’re usuallygreeted with a great deal of enthusiasm. But some complaints have been made that they can cause too much noise for residents living within a mile of the blades.
So just how noisy are these turbines?
The closest that a wind turbine is typically placed to a home is 300 meters or more. At that distance, a turbine will have a sound pressure level of 43 decibels. To put that in context, the average air conditioner can reach 50 decibels of noise, and most refrigerators run at around 40 decibels.
At 500 meters (0.3 miles) away, that sound pressure level drops to 38 decibels. In most places, according to Keith Longtin of GE Global Research, background noise ranges from 40 to 45 decibels, meaning that a turbine’s noise would be lost amongst it. For the stillest, most rural areas, Longtin says the background noise is 30 decibels. At that level, a turbine located about a mile away wouldn’t be heard.
For a complete run down of louder-than-a-fridge but quieter-than-a-blender context points, check out the graphic below.

How loud is a wind turbine?
Sound check: Click the image to enlarge it.