Thermal Energy Storage Technologies for Zero Carbon Housing in the UK
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Thermal energy storage technologies for zero carbon housing in the UK Jamal Khaled Alghamdi 2017 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY Welsh School of Architecture Cardiff University Cardiff, Wales, UK ii Declaration This work has not been submitted in substance for any other degree or award at this or any other university or place of learning, nor is being submitted concurrently in candidature for any degree or other award. Signed …………………………………………… (candidate) Date …01/08/2017….………… STATEMENT 1 This thesis is being submitted in partial fulfilment of the requirements for the degree of PhD Signed …………………………………………… (candidate) Date …01/08/2017….………… STATEMENT 2 This thesis is the result of my own independent work/investigation, except where otherwise stated, and the thesis has not been edited by a third party beyond what is permitted by Cardiff University’s Policy on the Use of Third Party Editors by Research Degree Students. Other sources are acknowledged by explicit references. The views expressed are my own. Signed …………………………………………… (candidate) Date …01/08/2017….………… STATEMENT 3 I hereby give consent for my thesis, if accepted, to be available online in the University’s Open Access repository and for inter-library loan, and for the title and summary to be made available to outside organisations. Signed …………………………………………… (candidate) Date …01/08/2017….………… STATEMENT 4: PREVIOUSLY APPROVED BAR ON ACCESS I hereby give consent for my thesis, if accepted, to be available online in the University’s Open Access repository and for inter-library loans after expiry of a bar on access previously approved by the Academic Standards & Quality Committee. Signed …………………………………………… (candidate) Date ………………….………… iii Summary of thesis Carbon dioxide emissions reduction in the domestic sector in the UK has been increasingly in focus in recent years. Reducing carbon emissions for both operational and embedded building energy will contribute to lowering the overall emission levels. This study aims to investigate the potential contribution of thermal energy storage systems in the UK’s domestic buildings. It also aims to investigate multiple thermal energy storage technologies and their integration into zero-carbon buildings. The research process is conducted in two phases: building energy simulation, and thermal energy storage modelling. Building energy simulation phase investigates energy performance of a single family zero-carbon house located in the UK. This simulation is performed to generate hourly thermal energy performance and calculate potential energy generated from on-site renewable sources. The energy simulation is conducted using HTB2, a computer based tool. The results show a total of 4158 kWh thermal demand while energy generation from renewables reached 6200 kWh. Although the generation exceeds demand, the simulated model requires an extra 1724 kWh of energy supply from the grid. The extra energy supply from the grid is a clear indication of an existing mismatch between energy demand and on-site energy generation. The second phase of this research is conducted by creating a calculation model for the thermal energy storage system. This model is used to determine the performance of different thermal energy storage systems under the operational loads of the zero-carbon house. This step determines the thermal energy storage system contribution in energy demand reduction by shifting load peaks. Furthermore, this step compares the performance between different storage technologies in terms of thermal energy capacity, volumetric storage, storage medium, and annual performance. The final modelling in this study shows performance difference between different TES technologies. While thermochemical energy storage systems achieved higher energy storage capacities with lower volumes than sensible heat storage and PCM systems, all systems were able to reduce demand from grid energy. The annual energy performance of artificial thermochemical sorption materials like zeolite 13X have the ability to achieve zero-grid demand with low requirement of storage volume compared to other material types tested in this study. iv Acknowledgment Firstly, I would like to express my sincere gratitude to my main supervisor, professor Phil Jones for his academic guidance and continues support throughout the thesis research and writing. It was a privilege for me to have him as a PhD supervisor for his unparalleled knowledge, patience, dedication, and motivation. His mentoring and supervision have set an ideal example for me to follow in my research and academic career. I would also like to thank my second supervisor Dr Simon Lannon for his help and advice in my study especially in the field of computer simulation. I would also thank Ms Katrina Lewis and all of the Welsh School of Architecture staff for the help and support offered during my PhD study. My sincere thanks also go to my beloved father Khaled Alghamdi for his guidance, support, encouragement, and his love in every step of my life. He is my life mentor, my beacon of hope in times of darkness, and my closest friend. My thanks also extend to my family in which they supported me with their kindness, warmth, and love. Last but not least, my great and deep gratefulness to the love of my life, my wife Najwa. With her love, dedication, support, and understanding I was able to overcome every difficulty and enjoy every achievement in this phase of my life. With her by my side, I feel blessed and I would not fear to take on any challenge in life. Jamal Alghamdi, March 2017 v Table of content Nomenclature ------------------------------------------------------------------------------------- viii Table of figures------------------------------------------------------------------------------------- ix 1 Introduction ------------------------------------------------------------------------------------ 1 1.1 Background information ---------------------------------------------------------------- 2 1.2 Research justifications ------------------------------------------------------------------ 4 1.3 Research aim and objectives ----------------------------------------------------------- 6 1.4 Research methods and work flow ----------------------------------------------------- 7 1.5 Research contribution ------------------------------------------------------------------- 8 1.6 Thesis outline ----------------------------------------------------------------------------- 8 2 Domestic Thermal Energy Demand and potential on-site energy sources --------- 11 2.1 Domestic thermal energy demand in the UK -------------------------------------- 12 2.1.1 Thermal energy demand in the UK’s domestic sector ---------------------- 12 2.2 Potential sources of renewable energy in the UK --------------------------------- 27 2.2.1 Solar energy ----------------------------------------------------------------------- 28 2.2.2 Wind energy ---------------------------------------------------------------------- 34 2.2.3 ASHP and GSHP ----------------------------------------------------------------- 38 2.3 Zero-carbon house --------------------------------------------------------------------- 39 2.3.1 General principle of zero carbon buildings ----------------------------------- 40 2.3.2 Fabric first approach ------------------------------------------------------------- 41 2.3.3 Performance of zero carbon buildings ---------------------------------------- 41 2.3.4 Passivhaus standards ------------------------------------------------------------- 44 2.3.5 Zero carbon buildings and the issue of overheating ------------------------- 48 2.3.6 Zero carbon building design process models --------------------------------- 49 2.3.7 Zero carbon case studies in the UK -------------------------------------------- 52 2.4 Summary of findings ------------------------------------------------------------------ 62 3 Thermal Energy Storage (TES) Systems ------------------------------------------------ 64 3.1 Thermal energy storage --------------------------------------------------------------- 65 3.2 Sensible thermal energy storage systems ------------------------------------------- 68 3.2.1 Storage materials and methods ------------------------------------------------- 69 3.3 Latent thermal storage systems ------------------------------------------------------ 74 3.3.1 Phase changing materials (PCM) ---------------------------------------------- 75 3.3.2 Selection of PCM material for TES systems --------------------------------- 77 3.3.3 PCM storage methods ----------------------------------------------------------- 79 3.3.4 Heat transfer enhancement for PCM TES ------------------------------------ 82 3.3.5 PCM TES application in domestic buildings --------------------------------- 83 vi 3.4 Thermochemical energy storage ----------------------------------------------------- 83 3.4.1 Thermochemical sorption phenomena ---------------------------------------- 85 3.4.2 Thermochemical sorption materials ------------------------------------------- 87 3.4.3 Thermochemical energy storage system design ----------------------------- 91 3.4.4 Thermochemical sorption case studies ---------------------------------------- 93 3.5 Thermal energy storage cycles ------------------------------------------------------- 97 3.6 Thermal energy storage systems volume and efficiency ------------------------- 98 3.7 Thermal energy storage operation from renewables ----------------------------- 100 3.8 Solar energy and thermal energy