Urban Wind Map for Delft, Rotterdam and Zoetermeer Fikirte M. Yemer B.Sc. 12-12-2010 Urban Wind Map for Delft, Rotterdam and Zoetermeer Fikirte M. Yemer B.Sc. Delft University of Technology Faculty of Applied Science Department of Sustainable Energy Technology DELFT UNIVERSITY OF TECHNOLOGY DEPARTMENT OF WIND ENERGY The undersigned hereby certify that they have read and recommend to the faculty of Applied science sustainable energy department for acceptance a thesis entitled “ Urban Wind Map for the Delft, Rotterdam and Zoetermeer’’ by Fikirte M. Yemer B.Sc. in partial fulfilment of the requirements for the degree of Master of Science. Date ________________ Head of Department and Supervisor _____________________________ Prof. dr. G.J.W Van Bussel Reader _______________________________ dr. Ir. Wim A. A. M. Bierbooms Reader _______________________________ dr. Hans Zoetelief SUMMARY Urban wind turbines fall within the scope of the green energy goal of municipalities in the Netherlands. For feasibility and potential green energy contribution assessment of these turbines, realistic wind speed prediction method is essential. The objective of this thesis is to develop urban wind resource mapping methodology and apply it to Delft, Rotterdam, and Zoetermeer. A non-conventional application of WASP is adapted by treating urban areas as a complex environment. As a topographic map, a Digital surface model that evolves above individual buildings which is then refined to a smooth synthetic surface evolving above cluster of buildings is used. Kriging interpolation and a combination of maximum and moving average grid filtering methods are used to create the synthetic surface. This smooth synthetic surface has lower ruggedness index around the meteorological sites, which indicates a gentle and smooth terrain that is relatively within the WASP working envelop. Roughness change maps generated by „wasp_map_exe’ and the wind data of Geulhaven and Zestienhoven meteorological stations, collected from the KNMI website are used in this work. The roughness change maps are modified to take into account the standardized potential wind speed of the meteorological sites. Annual mean wind speeds of 5.71 m/s and 4.71 m/s are registered for Geulhaven and Zestienhoven stations respectively. For both meteorological sites total frequency greater than 30 % is registered for south and southwest directions. Minimum prediction error is observed while using Geulhaven as a source than Zestienhoven. However Zestienhoven predicted the wind speed for Rotterdam with very low percentage error. Furthermore, the wind speed frequency of each predicted site has comparable distributions to that of the respective predictor. A 3.5% difference is seen among the omni directional predicted wind speeds of Rotterdam Noord that are based on the two meteorological sites. The sector wise wind speed differences range from 0.69% to 23%. Frequency difference among predictor sites, Ruggedness index and distance between the predictor and predicted sites contribute to the observed prediction difference.Wind resource maps are developed for the cities of Delft, Rotterdam, and Zoetermeer. The developed resource maps show a logical trend i.e. lower wind speed in the urbanized areas and higher wind speed in areas of low building density. Nonetheless, relatively higher wind speeds are observed at highly elevated locations within the urban areas. These areas have a good potential for installation of UWTs. It is recommended to use a raw wind speed data so that the introduction of error while modifying the roughness length can be reduced. Introduction of number of masts is very advantageous in refining the input data and validating the wind mapping methodology. i ii ACKNOWLEDGEMENT I would like to extend my sincere gratitude to my supervisor Prof. Dr. Gerard van Bussel for his invaluable support during the thesis work. I would like to thank Robert Schneider (CEO) for the opportunity to work with Donqi Urban Windmills. I would like to acknowledge the stuff members of Map Room of the TUDelft Library for their prompt supply of data; Kasper van Der Heiden, Paul Ten Hoppen, and Tamiru W. Shire for their feedbacks and inputs. I would like to thank the stuff members of the Rotterdam Noord police station for their assistance during my visit to the station. I would also like to thank Patricia Carrion Gordon and the academic counsellor Mirjam van der Geur for their assistance during the last months of my study. My special thanks go to Mesi, Fethea, Edi, and G.J. Wiersma for their hospitality during my stay in Delft. G5 it was great to share all the wonderful memories. Finally yet importantly, I would like to praise my mother for her love care and support. She has been an inspiration throughout my life. Above all, I wish to thank the Almighty God for holding me up and giving me the strength to finalize my study with a good sprit. iii iv TABLE OF CONTENTS SUMMARY ....................................................................................................................................... i ACKNOWLEDGEMENT ............................................................................................................... iii TABLE OF CONTENTS ................................................................................................................. v LIST OF FIGURES .......................................................................................................................... ix LIST OF TABLES ........................................................................................................................ xiii ABBREVIATIONS ......................................................................................................................... xv 1. INTRODUCTION ..................................................................................................................... 1 1.1. Background ......................................................................................................................... 1 1.1.1. Small Wind Turbines in the Netherlands .................................................................... 2 1.1.2. Existing wind Atlases of the Netherlands ................................................................... 3 1.2. Problem Definition ............................................................................................................. 3 1.3. Objective and Scope ........................................................................................................... 3 1.4. Approach ............................................................................................................................. 4 1.5. Thesis Outline ..................................................................................................................... 4 2. OVERVIEW .............................................................................................................................. 5 2.1. Basics of Wind Resource Estimation ................................................................................. 5 2.2. Urban Wind Property .......................................................................................................... 8 2.3. Wind Study Methods ........................................................................................................ 11 2.3.1. Use of Onsite Measurement ...................................................................................... 11 2.3.2. Physical Model .......................................................................................................... 12 2.3.3. Numerical Model ....................................................................................................... 12 2.3.4. Coupled Meso-scale and Micro-scale Modelling ...................................................... 14 2.4. Conclusion ........................................................................................................................ 15 3. WASP ....................................................................................................................................... 17 3.1. Introduction ....................................................................................................................... 17 3.2. WASP Sub-Models ........................................................................................................... 19 v 3.3. Factors affecting the prediction process ........................................................................ 24 3.4. Ruggedness Index (RIX) ............................................................................................... 25 4. SYNTHETIC DIGITAL SURFACE MODEL ....................................................................... 27 4.1. Introduction ....................................................................................................................... 27 4.1.1. Kriging Interpolation ................................................................................................. 28 4.1.1.1. Steps of kriging interpolation ................................................................................ 29 4.1.2. Grid Filtering ............................................................................................................. 30 4.2. DSM Application Software .............................................................................................. 31 4.3. Elevation Data .................................................................................................................. 31