High Resolution Non-hydrostatic Numerical Simulations for Wind Energy Assessment over Libya. A thesis submitted in fulfilment of the requirements for the degree of (MMaster of Science) By IBRAHIM S. M. ALHAWARI School of Mathematics and Statistics Faculty of Science University of New South Wales Sydney, Australia August 2009 THE UNIVERSITY OF NEW SOUTH WALES Thesis/Dissertation Sheet Surname or Family name: ALHAWARI First name: IBRAHIM S. M. Other name/s: Abbreviation for degree as given in the University calendar: MSc School: Mathematics and Statistics Faculty: Science Title: High Resolution Non-hydrostatic Numerical Simulations for Wind Energy Assessment over Libya. Abstract 350 words maximum This research is aimed at understanding the national wind energy resource of Libya to examine the viability of obtaining wind-generated electricity in the country. High-resolution regional wind observations in Libya are not sufficient for wind resource assessments throughout the country. To overcome such a barrier, the wind conditions have been estimated utilising high-resolution 3-D nested numerical simulations by the Non-hydrostatic Mesoscale Model of the Weather Research and Forecasting system (WRF-NMM). Analysis 2007 data from the Global Forecast System (GFS) were used as initial conditions whereas the boundary conditions came from a combination of GFS analysis and forecast data, in all runs. The coarse domain had a horizontal resolution of 15 km and a temporal resolution of 30 seconds while the fine domain had a horizontal resolution of 5 km and a temporal resolution of 10 seconds. 365 successive nested simulations were performed to produce hourly wind velocity data at 10 m above the ground along with at model sigma levels for both domains for the entire year. A cubic spline interpolation was used to interpolate wind velocity data between sigma levels and 10-m winds. Thus, wind velocity data at each grid point at six fixed heights (25, 50, 75, 100, 125, and 150 m above the ground) were obtained. Hourly power density data were computed at the seven mentioned heights. Wind power outputs were also estimated based on the power curves of commercial wind turbines of different sizes and designs. Results have shown that Libya has a very good potential for wind power generation. Several areas have been identified to be promising for future wind farms. The eastern and western coastlines, the northwestern high-altitude regions, and the mountainous areas in the Sahara Desert, have great potentials of using wind-generated electricity. Summer experiences the highest wind power resource over most parts of Libya. Over most areas, vertical wind shear peaks in the atmospheric layer of 75-100m. The use of the standard value of wind shear exponent would underestimate the vertical wind speed and power changes on most parts of the nation, while it would overestimate them in a few areas. Declaration relating to disposition of project thesis/dissertation I hereby grant to the University of New South Wales or its agents the right to archive and to make available my thesis or dissertation in whole or in part in the University libraries in all forms of media, now or here after known, subject to the provisions of the Copyright Act 1968. I retain all property rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation. I also authorise University Microfilms to use the 350 word abstract of my thesis in Dissertation Abstracts International (this is applicable to doctoral theses only). ………………………………… ……………………………………..……………… ……….……………………...…….… Signature Witness Date The University recognises that there may be exceptional circumstances requiring restrictions on copying or conditions on use. Requests for restriction for a period of up to 2 years must be made in writing. Requests for a longer period of restriction may be considered in exceptional circumstances and require the approval of the Dean of Graduate Research. FOR OFFICE USE ONLY Date of completion of requirements for Award: THIS SHEET IS TO BE GLUED TO THE INSIDE FRONT COVER OF THE THESIS Originality Statement ‘I hereby declare that this submission is my own work and to the best of my knowledge it contains no materials previously published or written by another person, or substantial proportions of material which have been accepted for the award of any other degree or diploma at UNSW or any other educational institution, except where due acknowledgement is made in the thesis. Any contribution made to the research by others, with whom I have worked at UNSW or elsewhere, is explicitly acknowledged in the thesis. I also declare that the intellectual content of this thesis is the product of my own work, except to the extent that assistance from others in the project's design and conception or in style, presentation, and linguistic expression is acknowledged.’ Ibrahim S. M. Alhawari Copyright Statement ‘I hereby grant the University of New South Wales or its agents the right to archive and to make available my thesis or dissertation in whole or part in the University libraries in all forms of media, now or here after known, subject to the provisions of the Copyright Act 1968. I retain all proprietary rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation. I also authorise University Microfilms to use the 350 word abstract of my thesis in Dissertation Abstract International (this is applicable to doctoral theses only). I have either used no substantial portions of copyright material in my thesis or I have obtained permission to use copyright material; where permission has not been granted I have applied/will apply for a partial restriction of the digital copy of my thesis or dissertation.' Authenticity Statement ‘I certify that the Library deposit digital copy is a direct equivalent of the final officially approved version of my thesis. No emendation of content has occurred and if there are any minor variations in formatting, they are the result of the conversion to digital format.’ Ibrahim S. M. Alhawari Dedication To my parents who have supported me throughout my life, and who have given me a continual encouragement. Acknowledgment Firstly, a great gratitude goes to Mr Russel Morison without whom this dissertation would not have been possible. Many thanks go to him for his continual support, guidance, and dedication of much of his time throughout the research period. I am deeply indebted to Mr Morison for his help in supervising me especially in the initial stages of my project, his advice, assistance with numerical weather prediction models, and with the provision of extra storage space for the huge data used in this project. I consider myself lucky to undertake my research at the UNSW School of Mathematics and Statistics, which was ranked the world number 14 on the quality index. My gratitude goes towards this school for providing computing facilities that were required to perform extensive numerical model runs. I would like to express gratitude to my family and friends for their ongoing emotional supports, which have allowed me to complete this project in an organised and above all enjoyable manner. I would also like to thank people who assisted me in facilitating my research at any stage even with one word. Finally, I am deeply appreciative to the Libyan Government for the financial support throughout my study. Ibrahim S. M. Alhawari Contents List of Tables.………………………….……………………….….…………….IV List of Figures………………………….………………………...………………V Table of Acronyms and Units...…….………………………...….…….…….X Abstract..……………………………………….……..……………...….….....XIII 1 Introduction……………………….…………..…….……………1 1.1 Background and Motivation……………………..….……………………1 1.1 Aim and Approach of Study……….……...…..………………………….5 1.2 Structure of Dissertation……………….…………………………………6 2 Wind Energy Background…………………...………………..8 2.1 Introduction……………………….…………………….….……..………..8 2.2 Historical Development of Wind Energy………....……..…..…………9 2.3 Advantages and Disadvantages of Wind Energy……….….………..11 2.4 Wind Turbines .…………………………………………………………..15 2.5 The Physics of Wind Energy….………………..……………………….18 2.6 Maximum Energy Extracted from the Wind…………...……………19 2.7 Parameters Affecting Wind Energy…………...………...…………….20 2.8 Vertical Wind Shear……………………………………………….….….23 2.9 Power Curve………………………………….……………………………24 2.10 Wind Power Capacity Factor………….………..……..………………..26 2.11 Summary………………………………………..…………..……………..26 3 Wind Energy Meteorology ………………………..…………28 3.1 Introduction………………………………………...……………………..28 3.2 The Nature of the Wind…………………………….……….…………..29 3.3 Global and Local Wind Resources……………………….…………….30 3.3.1 Atmospheric Large-Scale Circulation…………..….………….30 3.3.2 Local Circulations………………………….………..……………33 3.3.2.1 Sea/Land Breezes………….……….…………………….34 3.3.2.2 Mountain/Valley Breezes………….……...…………….37 I 3.3.3 Atmospheric Gravity Waves…………………….…...…………39 3.4 Wind Resource Assessment………………….…..……….….…………40 3.5 Wind Energy Situation and Potential in Libya…….………....……..43 3.6 Resource Assessment Data……………………………...……..……….47 3.7 Summary………………………………………………….…..…..……….50 4 Numerical Weather Prediction and the Model Used in this Study………………..….………………………..……...…..52 4.1 introduction……………….……………………………………………….52 4.2 NWP……………………………..………………………………………….53 4.2.1 Overview.………………..…………….....………………………..53 4.2.2 NWP Models and their Capillary…………………….………..54 4.2.3 NWP Inputs………………………………………...……………..57 4.2.4 Initial