Forecasting for Concentrated Solar Thermal Power Plants in Australia Edward Weikin Law A thesis in fulfilment of the requirements for the degree of Doctor of Philosophy University of New South Wales School of Photovoltaic and Renewable Energy Engineering Faculty of Engineering May 2017 i THE UNIVERSITY OF NEW SOUTH WALES Thesis/Dissertation Sheet Surname or Family name: LAW First name: Edward Other name/s: Weikin Abbreviation for degree as given in the University calendar: PhD School: School of Photovoltaic and Renewable Energy Engineering Faculty: Engineering Title: Forecasting for concentrated solar thermal power plants in Australia Abstract: Up to 50% of electricity needs in Australia could be supplied by solar power. At these high levels of solar power generation, solar forecasting is necessary to manage the impact of solar variability. However, there has been little research on using solar forecasting in Australia. This study used modelling to investigate the benefits of using short-term and long-term solar forecasts to operate a concentrated solar thermal (CST) plant for a year at four sites that covered different climate zones within the Australian National Electricity Market. Using 1-hour ahead short-term forecasts increased net value by $0.90-$2.07 million for a CST plant with storage, and by $0.76-$3.10 million for a CST plant without storage. It also improved reliability by reducing the equivalent forced outage rate by 21-38 percentage points for a CST plant with storage, and by 16-42 percentage points for a CST plant without storage. Using 1-hour forecasts achieved 59%-94% of the net value achievable if the 48-hour forecast were perfect. At each site, the highest net value and reliability were achieved by a CST plant with storage and using 1-hour forecasts, thus a CST plant should have both storage and short-term forecasts. If only one can be used, then a CST plant with storage and without 1-hour forecasts achieves higher net value, whereas a CST plant without storage and with 1-hour forecasts achieves higher reliability. These results demonstrated that using short-term forecasts is beneficial for CST plants that operate in electricity markets that allow updated bids to be submitted at short-term time frames. The results can be used to estimate the return on investment in obtaining short-term forecasts for operating a CST plant. Furthermore, the research method can be adapted into a tool for estimating value to assist CST plant project planning. 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 Signature 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 ii iii iv Acknowledgements “It takes a village to raise a child.” – An African proverb “If I have seen further it is by standing on the shoulders of giants.” – Isaac Newton First and foremost, I thank my mother, father, and sister for their love and support, without which I would not be where I am today. I thank my supervisors, Robert Taylor and Merlinde Kay, for tirelessly giving me guidance and their time for the duration of my candidature. I appreciate the invaluable feedback provided by my co-supervisor, Graham Morrison, my progress review panellists, Alistair Sproul and Evatt Hawke, and the peers who reviewed my journal and conference papers. I am grateful to the Australian Renewable Energy Agency (ARENA) and the University of New South Wales for awarding me ARENA and Australian Postgraduate Award scholarships. My research could not have been conducted without the ground and satellite solar radiation data supplied by the Australian Bureau of Meteorology, the National Centers for Environmental Prediction Reanalysis data provided by the US National Oceanic and Atmospheric Administration Office of Oceanic and Atmospheric Research Earth System Research Laboratory Physical Sciences Division, and The Air Pollution Model provided by the Commonwealth Scientific and Industrial Research Organisation. Finally, I have a word of thanks for my colleagues and friends, who each supported me in their own small ways. v Abstract Up to 50% of electricity needs in Australia could be supplied by solar power. At these high levels of solar power generation, solar forecasting is necessary to manage the impact of solar variability. However, there has been little research on using solar forecasting in Australia. This study used modelling to investigate the benefits of using short-term and long-term solar forecasts to operate a concentrated solar thermal (CST) plant for a year at four sites that covered different climate zones within the Australian National Electricity Market. Using 1-hour ahead short-term forecasts increased net value by $0.90-$2.07 million for a CST plant with storage, and by $0.76-$3.10 million for a CST plant without storage. It also improved reliability by reducing the equivalent forced outage rate by 21-38 percentage points for a CST plant with storage, and by 16-42 percentage points for a CST plant without storage. Using 1- hour forecasts achieved 59%-94% of the net value achievable if the 48-hour forecast were perfect. At each site, the highest net value and reliability were achieved by a CST plant with storage and using 1-hour forecasts, thus a CST plant should have both storage and short-term forecasts. If only one can be used, then a CST plant with storage and without 1-hour forecasts achieves higher net value, whereas a CST plant without storage and with 1-hour forecasts achieves higher reliability. These results demonstrated that using short-term forecasts is beneficial for CST plants that operate in electricity markets that allow updated bids to be submitted at short-term time frames. The results can be used to estimate the return on investment in obtaining short-term forecasts for operating a CST plant. Furthermore, the research method can be adapted into a tool for estimating value to assist CST plant project planning. vi List of Publications Journal papers Law, E.W., Kay, M., Taylor, R.A., 2016, Evaluating the benefits of using short-term direct normal irradiance forecasts to operate a concentrated solar thermal plant, Solar Energy 140, p. 93-108 http://dx.doi.org/10.1016/j.solener.2016.10.037 Law, E.W., Kay, M., Taylor, R.A., 2016, Calculating the financial value of a concentrated solar thermal plant operated using direct normal irradiance forecasts, Solar Energy 125, p. 267-281 https://dx.doi.org/10.1016/j.solener.2015.12.031 Law, E.W., Prasad, A.A., Kay, M., Taylor, R.A., 2014, Direct normal irradiance forecasting and its application to concentrated solar thermal output forecasting – A review, Solar Energy 108, p. 287-307 http://dx.doi.org/10.1016/j.solener.2014.07.008 Conference papers Law, E.W., Kay, M., Taylor, R.A., 2014, Assessing the economic benefit of forecasting concentrated solar thermal energy output, Solar2014: The 52nd Annual Conference of the Australian Solar Council, p. 131-140 vii Table of Contents Acknowledgements ........................................................................................................................ v Abstract ......................................................................................................................................... vi List of Publications ....................................................................................................................... vii Table of Contents .......................................................................................................................... 1 Nomenclature ............................................................................................................................... 5 List of Figures ................................................................................................................................ 8 List of Tables ............................................................................................................................... 10 1. Introduction ........................................................................................................................ 12 1.1. Research Aim, Motivation and Scope ......................................................................... 12 1.2. An Overview of the Australian National Electricity Market ........................................ 18 2. Concentrated Solar Thermal Power .................................................................................... 23 2.1. CST Plant