On the Use of Power Laws for Estimates of Wind Power Potential

Abstract

The evaluation of wind power potential at a proposed aerogenerator site by extrapolation from measured winds at a reference level is investigated. It is shown that the total mean wind power density is not particularly sensitive to the selection of roughness length or power law exponent; over the entire likely range of these parameters the wind power in the mean flow at typical aerogenerator hub heights is within 1.4?4 times the power at a reference height of about 10 m. In lieu of in situ profile measurements, it is suggested that a power law exponent of 1/7 is adequate for realistic but conservative estimates of the available wind power except at extremely rough sites where the estimates may only be conservative.