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INVESTIGATION of NOVEL AMMONIA PRODUCTION OPTIONS USING PHOTOELECTROCHEMICAL HYDROGEN by YUSUF BICER a Thesis Submitted in Parti

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INVESTIGATION of NOVEL AMMONIA PRODUCTION OPTIONS USING PHOTOELECTROCHEMICAL HYDROGEN by YUSUF BICER a Thesis Submitted in Parti INVESTIGATION OF NOVEL AMMONIA PRODUCTION OPTIONS USING PHOTOELECTROCHEMICAL HYDROGEN By YUSUF BICER A Thesis Submitted in Partial Fulfillment of the Requirements for the degree of Doctor of Philosophy in Mechanical Engineering University of Ontario Institute of Technology Faculty of Engineering and Applied Science Oshawa, Ontario, Canada © Yusuf Bicer, 2017 ABSTRACT Hydrogen and ammonia are two of the most significant clean fuels, energy carriers and storage media in the near future. Production of these chemicals are desired to be environmentally friendly. Renewable energy, in particular solar energy-based hydrogen and ammonia production technologies bring numerous attractive solutions for sustainable energy production, conversion and utilization. The energy of the sun is endless and the water is a substance which is always accessible and renewable. Ammonia is currently one of the mostly used chemicals throughout the world due to many applications, such as fertilizers, cooling agents, fuel, etc. The Haber-Bosch process is the most dominant ammonia synthesis process which requires very high temperatures and pressures to operate and consumes massive amounts of fossil fuels mainly natural gas leading a non-sustainable process in the long-term. Therefore, alternative methods for ammonia production are in urgent need of development. This study theoretically and experimentally investigates the photoelectrochemical production of hydrogen and electrochemical synthesis of ammonia in a cleaner and integrated manner. In this respect, the main objective of this thesis is to develop a novel solar energy based ammonia production system integrated to photoelectrochemical hydrogen production. The hybrid system enhances the utilization of sunlight by splitting the spectrum and combining the photovoltaic and photoelectrochemical processes for electricity, hydrogen and ammonia production. The photoelectrochemical reactor is built by electrodeposition of the photosensitive semiconductor (copper oxide) on the photocathode. The characterization of the reactor under solar simulator light, ambient irradiance and concentrated light is accomplished. Furthermore, an electrochemical ammonia synthesis reactor is built using molten salt electrolyte, nickel electrodes and iron-oxide catalyst. The electrochemical synthesis of ammonia is succeeded using hydrogen and nitrogen feed gases above 180°C and at ambient pressures. The photoelectrochemically produced hydrogen is then reacted with nitrogen in the electrochemical reactor to produce clean ammonia. The comprehensive thermodynamic, thermoeconomic, electrochemical and life cycle models of the integrated system are developed and analyses are performed. The results obtained through models and experiments are comparatively assessed. The spectrum of solar light can be separated for various applications to enhance the overall performance of energy conversion from solar to other useful commodities such as electricity, fuels, heating and cooling. The results of this thesis show that under concentrated and split spectrum, the photoelectrochemical hydrogen production rates and efficiencies are improved. The overall integrated system exergy efficiencies are found to be 7.1% and 4.1% for hydrogen and ammonia production, respectively. The total cost rate of the experimental system for hydrogen and ammonia production is calculated to be 0.61 $/h from exergoeconomic analyses results. The solar-to- hydrogen conversion efficiency of the photoelectrochemical process increases from 5.5% to 6.6% under concentrated and split spectrum. Similarly, the photovoltaic module efficiency can be increased up to 16.5% under concentrated light conditions. Furthermore, the maximum coulombic efficiency of electrochemical ammonia synthesis process is calculated as 14.2% -9 -1 -2 corresponding to NH3 formation rate of 4.41×10 mol s cm . i ACKNOWLEDGEMENTS First of all, I would to express my sincerest appreciation and gratitude to my supervisor, Prof. Dr. Ibrahim Dincer, for his endless, full-time, highly exergetic support and truthful guidance throughout my PhD thesis voyage. He provided me this unique opportunity to work with him in this research area under his excellent supervision and guidance. He has a very wide vision and mind to mentor and supervise his students in an extremely smart manner. This PhD thesis would not be possible without his supervision, patience, understanding, enthusiasm, and support. I am also grateful to Dr. Calin Zamfirescu for his support and help in critical times. I would also like to thank the examining committee members, Dr. Yasar Demirel, Dr. Martin Agelin-Chaab, Dr. Ali Grami and Dr. Yuping He for their valuable feedbacks and comments in improving this thesis. Financial support provided by the Natural Sciences and Engineering Research Council of Canada, Mitacs and Hydrofuel Inc. are gratefully acknowledged. Although it is not possible to mention all the names here, I have to thank all my friends and colleagues as a past or present member of Dr. Dincer’s Research Group at ACE3030 and Clean Energy Research Laboratory (CERL) namely; Farrukh Khalid, Dr. Hasan Ozcan, Murat Emre Demir, Muhammad Ezzat, Abdullah Al-Zahrani, Maan Al-Zareer, Ahmed Hasan, Huseyin Karasu, Reza Mohammadali zadeh, Dr. Canan Acar, Dr. Rami Salah El-Emam in addition to Murat Bahadir Ozkan. Special thanks go to Janettte Hogerwaard, Ghassan Chedade, André Felipe Vitorio Sprotte, Lowell Bower and Rodrigo Siliceo for their generous supports in the experimentation process. Karasu, Dereci, Ozkan, Zamfirescu and Khalili families are gratefully acknowledged for their kind friendships during my stay in Canada. I am also thankful to the managers of my previous employer, UGETAM, especially to Prof. Dr. Umit Dogay Arinc and Serkan Keleser in addition to Dr. Cevat Ozarpa for their valuable mentorship, advices and encouragements before and during this PhD. Sacrifice and patience are precious blessings and not easy to perform, therefore special thanks and love go to my dear chemist wife and mother of my children, Elif Derya, and my daughters, Erva Hatice and Zumra Ayse (who was born in the last moments of this thesis and was so quiet for her father to finish the thesis), for their generous sacrifice and endless encouragement. This work wouldn’t have been accomplished without their patience and support. Last but not the least, I would like to gratefully thank my dear parents; Mehmet Bicer and Sema Bicer who raised, educated and shaped me, and my siblings; Zehra Betul Bicer and Zeynep Bicer for their love, prayers and support. ii TABLE OF CONTENTS ABSTRACT i ACKNOWLEDGEMENTS ii TABLE OF CONTENTS iii LIST OF FIGURES vi LIST OF TABLES xiv NOMENCLATURE xvii CHAPTER 1: INTRODUCTION 1 1.1 Importance of Renewable Energy .............................................................................. 1 1.2 Hydrogen Energy ....................................................................................................... 1 1.3 Hydrogen Production Methods .................................................................................. 3 1.3.1 Hydrogen from nuclear energy ................................................................................ 3 1.3.2 Hydrogen from natural gas ....................................................................................... 4 1.3.3 Hydrogen from coal ................................................................................................. 4 1.3.4 Partial oxidation of heavy oils .................................................................................. 4 1.3.5 Hydrogen from biomass ........................................................................................... 5 1.3.6 Hydrogen from wind energy .................................................................................... 5 1.3.7 Hydrogen from solar energy .................................................................................... 5 1.3.8 Hydrogen from other renewable resources .............................................................. 5 1.4 Solar Light Based Hydrogen Production Methods .................................................... 6 1.5 Photoelectrochemical Hydrogen Production .............................................................. 7 1.6 Ammonia as a Sustainable Energy Carrier ................................................................ 7 1.7 Ammonia Production Methods .................................................................................. 8 1.8 Ammonia Utilization ................................................................................................ 14 1.9 Thesis Outline .......................................................................................................... 16 CHAPTER 2: BACKGROUND AND LITERATURE REVIEW 18 2.1 Solar and Photoelectrochemical Based Hydrogen Production Technologies ............... 18 2.2 Photosensitive Materials and Electrodeposition ............................................................ 21 2.3 Electrochemistry of the Photoelectrochemical Cells ..................................................... 24 2.4 Solar Concentrators and Solar Spectrum Effect on PV and Photoelectrochemical Hydrogen Production .......................................................................................................... 25 2.5 Spectrum Splitting Mechanisms and Applications ....................................................... 26 2.6 Solar PV and PV/T Systems .........................................................................................
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