Analysis of wave resource model spatial uncertainty and its effect on wave energy converter power performance

Wave models used for wave energy resource assessments are subjected to uncertainties, which differ from one location to another over the defined model area. This is because the models are typically calibrated and validated using a single or few validation points, and the model uncertainties of the wave parameters generally grow with the distance to the validation point. The spatial uncertainty of wave resource is one of the vital considerations in wave resource numerical modelling, since it is used to estimate the confidence in site assessments of potential wave energy device locations away from the validation point and is a necessary requirement of a resource assessment to IEC TS 62600-101. This paper focuses on developing a methodology for determining the spatial uncertainty by analysing how wave parameter uncertainties may change with location over the model area. A test site is modelled using the SWAN third-generation numerical wave model and validated at a single location for several wave parameters. A set of Monte-Carlo simulations are used to generate estimates of model uncertainties for locations around the validation point and a step-wise procedure is demonstrated with appropriate justifications to evaluate the uncertainties at these locations with respect to the validation point. Finally, the obtained results are used with a Wave Energy Convertor (WEC) numerical model to estimate the uncertainties on the power capture of the device.