How much wind?

A common question asked about wind turbines is whether there will be enough wind, and also what happens when it is not blowing. The factor that is used in calculating the energy that will be generated is the mean (average) wind speed over a period of a year. This takes into account times when there is no wind.
	This is the published mean annual wind speed chart that show us that in Suffolk we can expect 5-7 m/s speeds at the elevation at which the turbine operates. This is classified as a gentle to moderate wind speed and is sufficient to generate the estimated 25,000 units of electricity and £6,500 income for the Community Fund each year. Remember that this in not the strength of wind we experience at ground level. Even on open ground, the wind speed falls off the closer you get to the ground. Buildings, trees and hedges will further reduce the speed. So although we may experience only a very light breeze, up at 20-25m it will be steady and stronger.
This graph shows how the wind speed varies with height on open ground. Finally to wrap up this topic, the table below shows what wind speeds in m/s mean in terms of Beaufort wind force numbers and descriptions more familiar to us.