  The concept of capacity value is widely used to quantify the contribution of
additional generation (most notably renewables) within generation adequacy
assessments. This paper surveys the existing probability theory of assessment
of the capacity value of additional generation, and discusses the available
statistical estimation methods for risk measures which depend on the joint
distribution of demand and available additional capacity (with particular
reference to wind).
  Preliminary results are presented on assessment of sampling uncertainty in
hindcast LOLE and capacity value calculations, using bootstrap resampling.
These results indicate strongly that, if the hindcast calculation is dominated
by extremes of demand minus wind, there is very large sampling uncertainty in
the results due to very limited historic experience of high demands coincident
with poor wind resource. For meaningful calculations, some form of statistical
smoothing will therefore be required in distribution estimation.
