chapter  7
Wind resource
Pages 33

The extraction of power from the wind with modern turbines and energy conversion systems is an established global industry. This chapter focuses on the wind power resource and its measurement; the technology to extract this power follows in Chapter 8. We are particularly interested in average and above-average wind speeds, because the power in the wind is proportional to the cube of the wind speed, as shown in §8.3.1. We are also interested in (a) how wind occurs; (b) measurement; (c) variation with time, because of output power fluctuations; (d) increase of wind speed with height above the ground, since blade tips of very large machines may be 200 metres high; (e) turbulence and gusts; (f) local site conditions and obstructions, including other turbines, which affect generated output, and (g) prediction, so that electricity grid operators can plan ahead.