Comparing Meso-Micro Methodologies for Annual Wind Resource Assessment and Turbine Siting at Cabauw

J Sanz Rodrigo,D Cavar,D Allaerts,P Gancarski,A Folch,J Meyers,R Chávez Arroyo,A Dutrieux,F Borbón Guillén,J Barcons,M Avila

doi:10.1088/1742-6596/1037/7/072030

Abstract

A summary of the initial results of the “NEWA Meso-Micro Challenge for Wind Resource Assessment” is presented. The objective of this activity, conducted in the context of the New European Wind Atlas (NEWA) project, is to establish a process for the evaluation of meso-micro methodologies in the context of wind resource and wind turbine site suitability assessment. A hierarchy of methodologies that rely on coupling mesoscale and microscale models is evaluated as a tradeoff between accuracy and computational cost in terms of relevant wind conditions for wind turbine siting such as annual energy production, turbulence intensity, etc. Besides integrated annual quantities, these metrics are analyzed in terms of atmospheric boundary-layer drivers at wind climate (mesoscale tendencies) and site characteristics (atmospheric stability). This is used to characterize errors leading to the identification of knowledge-gaps in the model-chain. This first phase of the meso-micro challenge analyzes Cabauw onshore met mast in horizontally-homogeneous conditions to focus the assessment on mesoscale-to-microscale downscaling methods rather than on site complexity. A second phase of the challenge will add sites in heterogeneous terrain conditions from the NEWA database of experiments.

Highlights

In the development of meso-micro methodologies for wind resource assessment there is a tradeoff to be made between modeling fidelity and associated cost to yield the required accuracy for the intended use (Figure 1)
Wind Assessment Methodologies At this stage, we present results for year-long integrations of the models in Table 2 with the objective of comparing dynamical downscaling methodologies
Unstable conditions dominate at low wind speeds and stable conditions are more frequent at moderate speeds, between 6 and 11 m s-1

Summary

Introduction

In the development of meso-micro methodologies for wind resource assessment there is a tradeoff to be made between modeling fidelity and associated cost to yield the required accuracy for the intended use (Figure 1). Considering wind resource assessment applications, accuracy should gradually improve from the early-stage prospecting phase to the project financing phase, i.e. from planning to bankable accuracy This process will hopefully remove the bias and reduce the uncertainty of the assessment to desired financial limits. High fidelity models are based on the coupling of a mesoscale model with a large-eddy simulation (LES) atmospheric boundary layer (ABL) model that can resolve the dynamic effects of turbulence Between these two limits, a hierarchy of methodologies is established that combine mesoscale and microscale simulations, ranging in computational cost depending on the type of microscale model (steady or unsteady Reynolds-Averaged Navier Stokes, i.e. RANS or URANS) and the effectiveness of the coupling (dynamical or statistical) [1].

The Windbench NEWA Meso-Micro Challenge Phase 1

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Reference WRF simulation

Results

Conclusions and Outlook