INTRODUCTION

The main purpose of this chapter is to provide advice on choosing a decentralised wind energy site on the basis of an assessment of its wind resource alone. (Other factors are considered elsewhere in this book.) A secondary purpose is to provide guidance on estimating the wind resource. The end product, which may apply for various time periods (e.g., month, season, year), may be in one or more of the following forms:

1. a Mean wind speed.

2. b Wind speed as a function of wind direction.

3. c Wind speed frequency distribution (a function of wind speed class).

4. d Joint wind speed frequency distribution (function of direction and class).

5. e Weibull parameters of wind speed frequency distribution.

6. f Weibull parameters as a function of wind direction.

7. g Wind speed time series (sampled typically at 1 Hz) for periods of hours to days.

Items a to f may be derived by a combination of modelling and measurement whilst item g can only be obtained by measurement. Wind speed information may be converted to a similar description of available wind power which can then be used to select a suitable Wind Turbine Generator (WTG) or evaluate the economics of one that has been previously selected, say to fit the needs of the community, as discussed in Chapter 2.

An attempt will be made to take account of factors peculiar to such sites (e.g., limited funding and local turbulence effects). The emphasis, therefore, will be on small WTG's.