3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item Systematic synthesis framework for the generation of CO2 and H2 sinks: the P-Graph approach(2020) Jugmohan, JaimeeEconomies have become increasingly reliant on the use of fossil fuels as the primary energy source in order to meet energy demands of a growing population. The combustion of fossil fuels results in greenhouse gas (GHG) emissions, particularly carbon dioxide (CO2). This has resulted in CO2 emissions increasing at a rate that is detrimental to climate. To curb the detrimental effects of these emissions, whilst providing for the energy requirements of the population, a carbon negative energy source should ideally be introduced into the energy mix .In this dissertation, a P-Graph superstructure approach is utilized to encompass a wide array of CO2 reaction pathways that produce methanol (MeOH) and dimethyl ether (DME), both of which have proven to be prominent in the energy industry. A total of 85 reaction pathways were simulated using Aspen Plus ® software. These case studies were then analyzed from an environmental and economical perspective, in order to determine the most viable pathways to produce the aforementioned products. The framework developed was able to systematically reduce the search space from 85 possible scenarios, to 6 viable case studies, which is a 93% reduction in the original search space. The use of a CuO/ZnO/Al2O3 catalyst at 240oC and 80 bar pressure, was found to be the most viable option to produce MeOH. The most viable scenario for the production of DME, on the other hand, is to produce MeOH over the aforementioned catalyst, and then further dehydrate the MeOH over an Al/Si catalyst at 400oC and 25 bar pressure. The production of MeOH is deemed to be more feasible than the production of DME. With the most viable reaction pathway being known as the production of MeOH via a CuO/ZnO/Al2O3 catalyst, the focus is shifted outside of the framework, to the optimization of this reaction pathway. Post-optimization, it is found that the use of a CuO/ZnO/Al2O3 (TMC-3/1 industrial ZA Tarnow) catalyst at 201oC and 29bar pressure, is the most viable reaction conditions involved in the direct hydrogenation of CO2to MeOH. This pathway is able to yield a 97.69% conversion of CO2, thereby exhibiting the highest environmental and economic benefits after optimization. This dissertation details the systematic framework used in the synthesis and analysis of the P-Graph when arriving at the reduced search space, as well as the optimization procedure that is followed for the most viable reaction pathwayItem Formulation of a capacity mechanism for the Southern african power pool(SAPP) for sustaines long-term system adequacy(2019) Wright, Jarrad GPower system adequacy has been historically insufficient in the Southern African Power Pool (SAPP) region with resulting negative effects on economic growth and electrification efforts. Existing domestic regulatory frameworks and opaque longterm bilateral contracting for procuring capacity in the region have been shown to be insufficient in ensuring system adequacy. The concept of an adequacy product in the form of a Capacity Mechanism (CM) introduced into the SAPP region has not yet appeared in the literature. A Capacity Mechanism (CM) for the SAPP region has been proposed and designed as part of this research to address this. A framework has been developed to consider CMs via the combination of a screening assessment, quantitative (model-based) analysis of more favourable CM options and an identification and quantification of key design elements. The developed framework can also be generalised and applied to other jurisdictions where CMs are under consideration. A regional CM which transparently and explicitly values capacity is proposed in the form of a forward-looking annual Capacity Auction that is locationally disaggregated, supplied by all possible supply-side resources with all feasible SAPP market participants included. The CM should be technology agnostic and account for the dual requirement for firm capacity to meet peak demand and firm-energy to meet annual energy requirements considering the dominance of hydrobased capacity in the region when excluding South Africa. There should be a leadtime of 3-4 years with the possibility of long-term auctions for large hydro-based capacity. Strict market monitoring and adherence to performance incentives and penalties will need to be ensured to avoid exercising of market power considering the dominant size of the South African power system. Appropriately mandated institutions to run Capacity Auctions would include the SAPP Co-Ordination Centre as well as a sufficiently mandated regional regulatory body. A further contribution is made in the form of a public domain power system dataset of the SAPP region with sufficient detail to be used in power system operations and planning efforts by future researchers and practitioners.