UNCERTAINTY IN WIND RESOURCE ASSESSMENT - Wind Resource Assessment: A Practical Guide to Developing a Wind Project - page 217

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UNCERTAINTY IN WIND
RESOURCE ASSESSMENT
Wind resource estimates are only useful if their uncertainty is well defined. Unless the
analyst can offer a degree of confidence that the resource falls within a specified range,
it is not possible to construct a sound financial model for a wind project investment.
Financial models depend on risk, and for a wind project, risk depends strongly on
uncertainty in the resource.
The uncertainty present in all wind resource estimates is primarily related to the fol-
lowing factors: wind speed measurements, their relationship to the historical climate,
potential future climate deviations, wind shear, and the spatial wind resource distri-
bution. This chapter reviews these factors and provides a range of estimates for each.
In addition, ways of combining the uncertainties from different sources depending on
their correlation with one another are discussed. (Note that except where otherwise
stated, the uncertainty estimates mentioned here are expressed as a percent of the
speed and represent one standard error of a normal distribution.)
Not addressed in this chapter is the relationship between the uncertainty in speed
and the uncertainty in energy production, which varies depending on the turbine model,
mean wind speed, speed frequency distribution, and other factors. The uncertainty in
turbine performance and losses is also not considered. These topics, along with other
elements of energy production estimation, are discussed in the next chapter.