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Theses and dissertations (Engineering and Built Environment)

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    Feasibility of blue energy production using reverse electrodialysis In KwaZulu-Natal coastal region : modelling study using Comsol multiphysics
    (2024-05) Ngcobo, Lungisani; Ngema, Peterson Thokozani; Tumba, Kaniki
    Renewable energies have gained an increasing focus in recent years, due to the climate crisis contributed or associated with the current energy generation sources in South Africa. Thus, in this thesis, a renewable energy source called salinity gradient energy or blue energy will be presented and studied. The main objectives outlined in this dissertation were to evaluate the theoretical potential of electric energy production from the KwaZulu Natal rivers which are uThukela, uMvoti, uMkhomazi, Amanzimtoti, Umgeni, and uMfolozi. Finally, to optimize and simulate RED membrane and design reverse electrodialysis membranes and feeding pumps. In terms of the theoretical potential for producing electricity in the studied estuaries, it was concluded that the uThukela estuary has a considerably higher potential than the others. So, by this information, the possibility of designing the pilot plant in this estuary was studied, noting that the location of the pilot plant where the energy produced is greater and the capital cost are lower is at the mouth of the uThukela river. As for the pilot plant of RED, it was concluded that it is economically viable since the profit/loss found was R0 which is a break-even point, the plant is not generating a profit, but it’s also not generating a loss and since the focus for now is to try generating power. It’s economically viable in the sense that it covers its costs, but it is not profitable in terms of generating surplus revenue. It was concluded that using cheap and very thin membranes with high fluxes can increase the performance of the reverse electrodialysis. Also, the performance can be increased by using more than two reverse electrodialysis stacks instead of one.
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    Evaluation of grid-scale battery energy storage system as an enabler for large-scale renewable energy integration
    (2022-09-29) Loji, Nomhle; Davidson, Innocent Ewaen; Akindeji, Timothy Kayode
    Because of many substantial benefits over other renewable energy resources (RES), photovoltaic (PV) and wind technologies are the most important emerging renewable energy sources (RES) and they are rapidly and widely propagating. However, they are nondispatchable and, the stochastic and intermittent natures of solar irradiation and wind, are some of the fundamental barriers and challenges to their development and their large-scale deployment. As a result, power systems operators have no control over DG’s available resources and are compelled to operate conventional generators to both cater for normal changes in load demand and make provision for DG’s output variations. These concerns lead to increase the uncertainty in power systems operation as they modify both the structure and the operation of the distribution network by affecting inter alia, the voltage profile and stability, the direction of network power flow and the overall performance of the power system. Enabling PV penetration into electrical grids require a balance of supply and demand that cannot be achieved by oneself. Because of the flexibility to control their real power output, batteries are suggested as a suitable and cost effective solution to mitigate the adverse effects of intermittency and shape the fluctuation of the system’s output into relatively constant power. There is a need to quantitatively investigate and evaluate the performance of the use of BESS that adequately smoothen the output of the PV-BESS sub-system for over-voltage reduction and peak load shaving during the high PV generation – low consumption time in lieu of power curtailment or reactive power injection. Using DigSILENT™ - PowerFactory™ this research work investigated the impacts of BESS on voltage stability and power losses with the aim of increasing system loadability and enhancing stability. A modified standard IEEE 9-Bus was used to perform the studies using four cases and various scenarios and the simulation results and comparative analysis first reveal that the combined effect of the Solar PV-BESS system has a substantial positive impact on the system loadability improvement and reduction of the total power system losses. Results further confirmed the BESS’s ability to act as generator, or load, respectively during high load demand/lower PV generation and lower demand//higher Solar PV generation to contribute to the voltage regulation and power system stability, offsetting effectively the intermittency of Solar PV energy sources and subsequently enabling greater RE penetration.
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    A study of biogas generation from poultry litter and its impurity removal
    (2019-01) Osagie, Ighodaro; Lazarus, I. J.; Reddy, G.K.; Singh, Ramkishore
    This study is focused on the anaerobic digestion of poultry waste to produce biogas. Waste was collected from three different poultry farms (Sekela farm, Emarldene and Parkside poultry industry) in Kwazulu-Natal, South Africa. The aim is to assess energy from poultry waste in Kwazulu-Natal and to enhance the process of biogas production by treating the impurities of sulphur content, moisture and carbon dioxide in the biogas. The objectives are: to determine the energy potential of poultry waste in Kwazulu-Natal region, to increase the energy density of the biogas by the removal of moisture content, incombustible and corrosive gas and to assess techno-economic feasibility of biogas generation from poultry waste. 1 kg of each waste was thoroughly mixed with 3 L of water and loaded into ten digesters with each water bath (thermal conductor) bearing two digesters. The slurry was investigated using water displacement method to determine biogas produced for a period of 21 days and at an average temperature of 30 0C, 31 0C, and 32 0C respectively. Production started on the 3rd day for each digester at different temperatures (30 0C, 31 0C, and 32 0C), and attained maximum value on the 14th and 15th days. The maximum amount of biogas produced was 265.6 ml at a temperature of 32 0C from waste A (Sekela farm). At 32 0C, an optimal biogas yield of 421.6 ml/g VS was observed from Sekela farm (poultry waste A) compared to Emarldene (370.10 ml/g) and Parkside poultry industry (349.10 ml/g) in KwaZulu-Natal. Biogas was collected from the digester with the maximum volume of biogas produced using 100 µʟ gas syringe and was taking to Gas chromatography for characterization. The result showed that it was composed of about 57.71 % methane (CH4), 26.8 % carbon dioxide (CO2), 0.8 % nitrogen (N2), traces of hydrogen sulfide (H2S), fractions of water vapor, and other impurities which the detector was unable to quantify with an energy potential of 0.028 MJ/ml. Purification and Upgrade system was comprised of one column charged with steel wool (iron sponge), and two cylinders charged with pressurized water and silica gel to treat H2S, CO2, and water vapor in the biogas for improvement of its energy density. Biogas was collected from the purified system using gas syringe to the Gas chromatography for characterization and result showed that it is composed of about 84.56 % CH4 and energy potential of 0.046 MJ/ml. The result confirmed that the biogas heating value/energy density was improved/increased using steel wool, pressurized water and silica gel as biogas contaminants removal. Techno-economic studies were carried out to assess the techno-economic feasibility of a small-scale biogas plant using poultry waste in KwaZulu-Natal. A fixed dome digester was selected as the most convenient technology for the community. Result showed that 2,160 kWh per year of energy could be produced from about 4,000 kg of poultry waste and the payback time was eleven years and nine months. It showed that it is techno-economically feasible to use a fixed dome digester for energy generation for domestic usage and is cost-effective. In conclusion, poultry waste as a feedstock is suitable for anaerobic digestion, producing methane which can be used as an energy source and which can be purified to improve its energy potential. Biogas optimization is dependable on: temperature, physio-chemical characteristics of waste, pH and retention time e.g. at same temperature (either 30 0C, 31 0C or 32 0C) and time, waste A production is higher than waste B and C because of its favorable physio-chemical characteristics and pH-value. It is deduced that the energy potential in poultry waste could be determine by treating the waste via anaerobic digestion and the increase in the energy density of the waste is dependable on temperature, pH, retention time and physio-chemical characteristics of the waste.
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    Investigating the root cause of solar power unsustainability in KwaZulu-Natal, South Africa
    (2020-05-05) Mdlolo,Bantubenzani Nelson; Olanrewaju, Oludolapo Akanni
    ABSTRACT Like many other countries, South Africa as a developing country relies on electricity as the most important basic amenity needed for development. KwaZulu-Natal (KZN) is a province in South Africa affected by an erratic supply of electricity. In the past few years, some areas in KZN region have continued to experience load shedding, while other areas do not have access to electricity at all. Municipalities are responsible for electricity supply and regulation in the KZN communities. Due to its geographical location KwaZulu-Natal enjoys a warm subtropical climate and receives year-round sunshine even in the winter months. It is thus an ideal region for the implementation of solar power on a large scale. Renewable energy in the form of solar power could easily generate an adequate supply of electricity to meet the electricity demand requirements and energy sustainability of the KZN province. South Africa has a renewable electricity generation of about 2% as per the research of United Nation Statistics Division of 2009 (Manju and Suger, 2017). However, the current access to electricity still faces the challenge of meeting demand and shortage of coal to generate electricity which the most important required to all South Africans; therefore, an effective alternative such as solar power is a necessity. The main challenge to the solar electricity supply is its unsustainability in the region. Intermittent load shedding coupled with the unsustainability of solar power, has negatively affected the economic performance of the region. This challenge (solar power unsustainability) limits the region from meeting the energy demands facing the KZN region. The main aim of this study was to investigate the root cause of solar power unsustainability in the KZN region. A quantitative method as well as a cost-benefit analysis was used to interrogate the solar power crisis in the KZN region. The Cost Benefit Analysis CBA gave an assurance of an early (financial) investment when implementing solar power in the eThekwini region. The adopted multiple regressions also revealed the high possibility of solar power performance of 0.75 r²-value. All challenges facing solar power are investigated through the cause and effect diagram as well. The Economical, Methodological and Environmental (EME) framework was proposed to address the unsustainability of solar power discovered in the region of KwaZulu-Natal. However, more work still needs to be done to investigate the potential growth of solar power in the region.