Saudi Cultural Missions Theses & Dissertations
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Item Restricted Plasma Reforming Technologies for Low Carbon Hydrogen Production(University College London (UCL), 2024-09) Alrasheed, Bader; Materazzi, MassimilianoThis project investigates the use of plasma-assisted methane pyrolysis for low-carbon hydrogen production and addresses the urgent global need for sustainable energy solutions. With hydrogen playing an important role in the transition to cleaner energy, the research focuses on developing a computational model using Ansys Chemkin-Pro to simulate the plasma pyrolysis process. The objective is to maximize hydrogen production while significantly reducing CO2 emissions, compared to traditional methods such as steam methane reforming. The study involves validating the model with experimental data and optimizing the process parameters for industrial-scale applications. Through a comparative analysis of different plasma conditions and feed compositions, the research identifies the most efficient scenarios for hydrogen production. The results show that plasma pyrolysis offers a feasible alternative for low carbon hydrogen production and allows for the utilization of carbon black as a valuable by-product. However, there are challenges that require further investigation to enhance the scalability and economic feasibility of this technology, such as optimizing reaction mechanisms and managing by-products. The study concludes with recommendations for future work, including reviewing kinetic data, exploring the option of an additional reactor, exploring the option of adding catalysts to the system, conducting laboratory experiments, and conducting detailed economic analysis to support the transition from research to industrial implementation.36 0Item Restricted Exploring the Use of S800 Starbons as Microwave Absorption Media in the Cracking of plastic waste to produce Hydrogen(University of York, 2024) Alawni, Mohammad; MacQuarrie, Duncan; Matharu, AvtarS800 Starbon was investigated as a microwave absorption medium in the decomposition of plastic waste to produce hydrogen. The thermal properties, porosity, elemental composition, and effectiveness of S800 Starbon in facilitating the decomposition of polyethylene (PE), polypropylene (PP), and polystyrene (PS) under various microwave conditions were investigated. The research exposed that S800 Starbon can effectively optimize hydrogen production from plastic waste, with the yield depending on the polymer type, Starbon concentration, microwave power, and temperature. Gas chromatography analyses showed complex product distributions, proving that the presence and type of polymer greatly affect the reaction pathways. The results indicated the potential for improving the value of plastic waste processes and developing more efficient recycling technologies.9 0Item Restricted Impact of policy on the adoption and development of hydrogen fuel cell vehicles(Queen Mary University of London, 2024-08) Alahmadi, Haitham; Peters, StuartThe transport sector accounts for the largest share of global carbon emissions—almost 25% of the aggregate total. As battery electric vehicles are being adopted quickly, it raises the demand for materials central to the production of the batteries, but hydrogen technology has been put forward as an alternative solution with the potential to reduce the carbon footprint of transportation. Its broader adoption encounters serious technical and policy hurdles. This study seeks to critically assess the effectiveness of various policies in stimulating market demand for hydrogen fuel cell vehicles (HFCVs). Through a combination of quantitative and qualitative methods, the research provides a comprehensive evaluation of how effectively these policies are meeting their intended goals. Results show that government direct investment in hydrogen refueling infrastructure, as with South Korea and Germany, improves significantly over the U.S. approach that depended on private investments from tax incentives. Additionally, sustained and focused investment in hydrogen research and development (R&D), particularly in South Korea via partnership with automaker Hyundai, has led to significant advancements in HFCV production. This approach has proven more effective than the broader, less targeted hydrogen R&D programs in the U.S. Moreover, direct government subsidies, which significantly reduce the cost of HFCVs, have made these vehicles more competitive with BEVs in South Korea, surpassing the effectiveness of tax incentives and rebates in the U.S. and Germany.21 0Item Restricted PERFORMANCE OPTIMIZATION OF A PROTON EXCHANGE MEMBRANE WATER ELECTROLYZER(University of Delaware, 2024-07) Alkhaldi, Shabeeb; Ajay, PrasadGreen hydrogen can contribute significantly to combating climate change by helping to decarbonize the world's energy sector. Hydrogen can be produced in a carbon-free manner using renewable energy by electrolysis which is environmentally benign and produces hydrogen with high purity. Water is fed to the electrolytic cell as the reactant and it is dissociated into hydrogen and oxygen by the passage of electricity. Water electrolysis is typically accomplished today by one of three methods: (i) alkaline water electrolysis (AWE); (ii) solid oxide water electrolysis (SOWE); and (iii) proton exchange membrane water electrolysis (PEMWE). PEMWE offers certain advantages including high efficiency and high current density. Therefore, we focus on PEMWE in this study. First, we examine the effect of various operating parameters on PEMWE performance such as water flow rate, temperature, membrane thickness, flow field channel configuration, and porous transport layer properties. This work quantitatively compares the relative magnitude of anode water consumption against the concurrent water transport mechanisms of Fickian diffusion and electroosmotic drag as a function of the applied voltage. This study also gives insights on optimizing PEMWE performance by varying the operating parameters and provides a foundation for the design of a full-scale PEMWE system. Second, we evaluate multiple strategies for gas management in the PEMWE anode. In this study, we employ an electrolysis cell featuring a transparent anode to visualize oxygen bubble production and transport under a range of operating conditions. These strategies include changing the cell’s orientation with respect to gravity, increasing the water flowrate, and adding surfactant to the anode water supply. This study shows that optimally orientating the channels with respect to gravity can assist with oxygen bubble evacuation and improve performance. This study also captures the dynamic behavior of the two-phase flow phenomena in PEMWEs over a range of applied voltages. The results provide suggestions to enhance PEMWE performance by optimizing oxygen gas management within the PEMWE’s flooded anode. Third, we focus on the phenomenon of electroosmotic drag in an operating PEMWE with the goal of accurately measuring the electroosmotic drag coefficient. This study elucidates the effect of the cell temperature and membrane thickness on the relevant water transport phenomena. We also investigate the effect of supplying dry nitrogen to the cathode and provide an explanation for the improved current density based on the Nernst equation. Understanding these mechanisms is essential to improving PEMWE performance and efficiency. Finally, we compare the catalytic performance of nickel iron layered double hydroxide (NiFe LDH) against commercial iridium oxide (IrOx) in an anion exchange membrane water electrolyzer. In this study, we present the structural and performance analysis of NiFe LDH which was prepared in the form of nanosheets through a benzyl alcohol-mediated solvothermal process in one step. The NiFe LDH electrode demonstrated good stability over a 24-hour durability test. Although the electrochemical performance of NiFe LDH was somewhat lower compared to IrOx, it shows promise as a AEMWE catalyst due to its significantly lower cost and capacity for further activity enhancement.22 0Item Restricted The economic viability of blue hydrogen production: Forecasting Saudi production cost of blue hydrogen.(City, University of London, 2023-09-01) Alfaifi, Abdulaziz; Tamvakis, Michael; Alshammari, YousefAs global energy demands are surging and concerns over environmental sustainability intensify, the hydrogen emerges as a promising solution towards clean energy production and storage. This dissertation delves into the economic viability of blue hydrogen production in Saudi Arabia with the focus of the forecasting of production costs. By encompassing the evaluation of various hydrogen types, blue hydrogen applications, and an estimation of production costs according to historical feedstock prices. The literature review scrutinizes different hydrogen types with their economic feasibility in the context of blue hydrogen production. Consideration of cost competitiveness, environmental impact, and scalability lays the groundwork forward to insights. Furthermore, the examination of blue hydrogen's applications elucidates industries poised to benefit from future possible investments in this energy carrier, while also diving into potential challenges and opportunities. Employing a meticulous methodology, forecasting the production cost of Saudi blue hydrogen, placing particular emphasis on feedstock prices. By utilizing ARMA model to leverage forecasted natural gas prices, thereby shedding light on the relationship between feedstock costs and hydrogen production expenses. The results and recommendations have strategic insights and actionable suggestions. By comparing decisions made at the oil and gas industry, this dissertation positions itself at the intersection of industry growth stages. The findings offer suggestion for a transition from the emerging phase to the mature phase in early growth market, with an emphasis on cost-saving strategies and optimizing resource. A pivotal finding emerges in understanding the influence of natural gas prices on production costs of Saudi Aribia. The dissertation implies the significance of efficiently managing feedstock prices and subsidy costs. Implications extend to both national and international contexts as well, particularly in steering the export decision concern of blue hydrogen and blue ammonia. This dissertation holds significant relevance for particularly energy economists in Saudi Arabia, providing them with a nuanced understanding of the economic dynamics that are shaping the production and export of blue hydrogen that is by the insights from the dissertation into the interplay of feedstock prices, industry growth stages, and strategic decision-making, this dissertation contributes to a more informed energy landscape.44 0Item Restricted Fabrication and Optimisation of Engineered Nanostructured Thin Films for Enhanced Photoelectrochemical Applications(Exeter University, 2024-06-24) Alhabradi, Mansour; Tahir, AsifThis thesis presents an extensive study on the development and enhancement of nanostructured photoelectrode materials for photoelectrochemical (PEC) water splitting, a critical area in sustainable energy technology advancement. The research is divided into three focused areas: the development of a robust n-type semiconductor photoanode, the fabrication of heterojunction-based metal oxide semiconductors, and the integration of efficient co-catalysts with photoanodes. The first chapter, which has led to a publication, delves into the fabrication of thin films using radio frequency (RF) sputtering. This process involved an in-depth examination of the factors influencing the films' morphology and phase. A significant development was achieved with the synthesis of vertically aligned Fe2O3 nanorods, which were enhanced by incorporating cadmium oxide (CdO) nanoparticles. This unique combination resulted in a considerable boost in PEC activity, characterised by increased photocurrent density and stability. The innovative corn-like morphology and high crystallinity of these nanorods, combined with the synergistic effect of the CdO co-catalyst, led to improvements in photocurrent generation and stability, which are essential for applications in environmental remediation and sustainable energy conversion. The second chapter, which has also resulted in a publication, explores the creation of a type II nano-heterojunction by integrating HfO2 with α-Fe2O3. Preliminary results indicate that this heterostructure significantly improves charge separation and transport, showing promise for substantial enhancements in PEC performance. The increased photocurrent density and improved photon absorption in the visible spectrum are indicative of the potential improvements this research could provide to PEC systems. The third chapter, which has also resulted in a publication, investigates the deposition of cobalt nanoparticle-based co-catalysts on WO3 thin films. This approach has successfully enhanced carrier separation and interface charge transfer efficiency, leading to a significant improvement in photocurrent density under simulated solar radiation. This achievement marks a development in the field, demonstrating the potential of nanoparticle-based co-catalysts in enhancing the efficiency of PEC systems. In summary, this thesis provides valuable insights and new methods in the study of photoelectrochemical (PEC) water splitting. The research, especially the findings from the first and third chapters, represents important progress in photoelectrochemistry. These contributions pave the way for future developments in sustainable energy technologies.27 0Item Restricted Investigation of New Renewable Energy-based Multigeneration Systems for Saudi Arabia(Ontario Tech University, 2024-05-08) Altayib, Khalid; Dincer, IbrahimThis thesis explores three hybridized, large-scale solar thermal energy multigeneration systems: System 1 combines solar thermal energy with biomass, System 2 with geothermal, and System 3 with a petroleum coke and biomass blend. Each system provides power, heating, desalination, and other commodities. The thesis aims to develop energy system flowsheets integrating multiple technologies and assess their exergetic and economic benefits through case studies in KSA. Although the systems are of different kinds and scales, their economic parameters are found to be similar in terms of payback periods. System 1 achieves energy and exergy efficiencies of 50.4% and 45%, respectively. It generates annually 1040 GWh of electric power, 860 GWh of cogenerated heat, 80 GWh of refrigeration, 1100 tons of hydrogen, 26000 tons of chlorine gas, 11,600 tons of concentrated aqueous sodium hydroxide, 11,300 tons of ammonia, 1740 tons of aqueous urea, 905,000 m3 of fresh water. System 2 generates 700 GWh/year of power, 1200 GWh/year of heating, 27,100 tons/year of methanol, 130 million m3/year of fresh water, 42,500 tons/year of oxygen with efficiencies of 22% energy and 30% exergy. System 3 generates 1200 GWh/year of power, 690 GWh/year of heating, 12,700 tons/year of hydrogen, 19,300 tons/year of dried dates, 290,000 m3/year of fresh water and 80 GWh/year of cooling. The energy and exergy efficiencies of System 3 are 83.2% and 64%, respectively. For all systems, the chemical reactors are modelled using the Aspen Plus, which helps determine the best oxygen-to-biomass fraction in the gasifier as 15% at the turbine inlet temperature of 1500°C for System 1, the optimum methanol synthesis temperature in the range of 250°C-300°C for System 2, and results in 1.5 H2/C as the best molar ratio in hydro-gasifier to enhance the synthetic methane production rate for System 3. The thesis study underscores the potential of multigeneration and hybridization in improving the economics and ecology of renewable energy systems and offering insights applicable beyond the case studies explored.10 0Item Restricted Waste Gasification for Hydrogen Production(University College London (UCL), 2023) Lahig, Talal; Materazzi, MassimilianoThe vision for hydrogen being at the forefront of the energy transition is already in existence, due to its high energy density and its zero greenhouse gas emissions during use. Current production methods include steam-methane reforming and coal gasification, which lead to high CO2 emissions that will amplify climate change with increasing demand. Opposite to this is waste gasification, which provides a sustainable gateway for clean hydrogen production as waste contains biogenic carbon and can attain negative carbon emissions when coupled with carbon capture and sequestration (CCS). This study concentrates on the development of a novel approach to predict the pyrolysis yields of diverse waste based on its components of cellulose, hemicellulose, lignin, polyethylene and polypropylene. The work demonstrates that the flexibility and predictive capability of an air-steam bubbling fluidised bed (BFB) gasification model for a wide array of waste types is improved. The model was rigorously validated against pilot plant data through comparison of the outlet syngas composition, the tar content, the heating value and the temperature profile across the fluidised bed gasifier at a range of conditions. The effects of the feedstock type, equivalence ratio (ER) and the steam-to-waste ratio (STWR) are investigated to determine the optimal conditions for achieving a high H2 yield, while maintaining medium heating values. It was found that a H2/CO ratio of 2.37 is achieved with an ER of 0.30 and a STWR of 1.2 using sugarcane bagasse.33 0Item Restricted Development of Quantitative Finite Element based Phase-Field model for the Precipitation of δZrH in αZr(Saudi Digital Library, 2023-09-22) Salman, Alrakan; Takahashi, HiroyukiDue to the excellent combination between its mechanical, thermal, physical, and nu- clear properties, Zirconium based alloys are the material of choice for cladding tubes in light water nuclear reactors. However, the interaction between the water coolant and the Zirconium cladding will result in a corrosion reaction. This will result in the formation of Zirconium Oxide and the release of Hydrogen. A portion of the released Hydrogen diffuses into the cladding, and as the concentration of Hydrogen increases, Zirconium hydrides will precipitate. Zirconium hydrides are brittle mate- rials which will result in a degradation of the long term structural integrity of the cladding. Several pioneering experimental investigations were implemented in the past 50 years. These important studies made considerable advancements in under- standing the properties of Zirconium and its hydride phases, and in addition, studied the effect of several important forces on the Zirconium hydride precipitation process such as stress, texture, and temperature. However, many of the precipitation induced mechanisms are still unknown, and were not clarified by experimental investigations. This is due to the fact that precipitation occurs at very fine length and time scales, which are beyond the capability of experimental investigations. Hence, a compu- tational investigation is required. Among computational techniques, the phase-field method established itself as the main continuum method for the investigation of ma- terial transformations at the miso-scale. This is due to its fundamental origins, the ability to depict specific material structural features such as grain boundaries and defects, and its intuitive approach to multi-physical coupling. In the past 15 years, several important models were proposed for Zirconium hydride precipitation. These models made considerable advancements in understanding, and clarifying key aspects associated with precipitation process, and paved the way for the development of fu- ture models. However, the inaccurate deception of the system properties, affected the clarity of the implemented studies, and in addition, the inefficient implementation re- sulted in low fidelity studies that did not reveal several aspects that are associated with the precipitation process. Hence, this study was implemented to develop a novel, quantitative, Finite Element-based, phase-field model to investigate the precipitation process of δ-Zirconium hydride in α-Zirconium. The model was built utilizing a novel nucleation model that is based on the classical nucleation theory which respects mass conservation in the system, and results in the natural and accurate determination of the equilibrium concentrations for the phases in the system. Furthermore, the model uses the modern matrix-free implementation, and adaptive mesh refinements strate- gies. These result in a very efficient implementation and relatively moderate system. This will allow the model to conduct high-fidelity investigations. The model can be applied to investigate any two phase system, and can be easily extended to inves- tigate multiple phases. Furthermore, it has the ability to investigate a wide range of phenomena including solidification, precipitation, and second-phase growth. The model was verified & validated by comparing the numerical solution of this model, and the analytical solution of the Kim-Kim-Suzuki model. Furthermore, the model was compared with current preferred software that is used for phase-field modeling, the MOOSE framework which is developed by the Idaho National Laboratory. The developed model showed a much higher runtime efficiency and at the same time, did not require an intensive hardware consumption. This allowed the developed model to run very high fidelity analysis cases on relatively moderate hardware. The model was applied to investigate the role of capillary-induced forces on the precipitation mecha- nisms of δ-Zirconium hydride in α-Zirconium, which to our best of knowledge have not been investigated before experimentally or computationally. A high-fidelity analysis in terms of particles simulated and the duration allowed the study to verify the role of precipitate size, shape, and stacking formation structure on the precipitation process. Furthermore, it clarified the role of hydride-hydride interaction as well. In addition, a very large domain size was generated preventing the development of excessive elastic energy during the precipitation process. The study was able to reveal key mechanisms associated with δ-Zirconium hydride precipitation in α-Zirconium. The shape of the precipitates changes from a spherical shape toward a disk-like shape precipitates that aligned along the basal plane of α-Zirconium as the size increases. At small precipi- tate sizes, the isotropic interfacial energy will dominate the shape formation process resulting in a spherical shape. As the size of the precipitate increases, the shape of precipitates will become more influenced by the elastic energy leading to a more disk- like shape where the precipitates will possess a larger radius along the basal plane relative to the c-axis. This is promoted by a stronger stiffness of α-Zirconium and a higher misfit strain along the c-axis relative to the basal plane. This is confirmed by the linear relationship that develops between the aspect ratio of precipitates, and the interface to area ratio. As precipitates grow and their shapes become more disk-like, the equilibrium concentration will be affected by the surface curvature of precipitates maximizing along the basal plane where the maximum curvature is located. This leads to a lower chemical potential which promotes precipitates realignment along the basal plane. The close proximity of aligned precipitates, results in an accumu- lation of hydrogen. This is promoted by capillary-induced surface diffusion. This leads to a decrease in the chemical potential between the precipitates. This promotes the migration process of precipitates toward each other and ultimately coalescence. At the onset of coalescence, a large increase in the precipitate growth rate occurs leading to the flattening of the newly formed single precipitate surface. This will lead to the development of large size variations within the local vicinity. This results in an acceleration of capillary-induced diffusion-limited coarsening. Here, larger precip- itates will keep growing and smaller precipitates will shrink and ultimately dissolve. This is promoted by a higher equilibrium concentration of hydrogen and a higher chemical in smaller precipitates which drives the diffusion of mass from smaller to larger precipitates. The sequence of precipitate realignment, migration, coalescence, and diffusion-limited coarsening keep re-emerging as the length scale of precipitates increases. These mechanisms are verified through a complete set of results that were provided by the study, they are originally proposed, and on par with fundamentals in material kinetics.24 0