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Now showing 1 - 5 of 20

Recent Submissions

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    Techno-Economic Analysis of Green Hydrogen Production Through Solar in South Africa
    (University of the Witwatersrand, Johannesburg, 2025-08) Langdon, Chad Benoy; Roohani, Hamed; Schekman, Sjouke
    Green hydrogen is set to become a part of South Africa’s energy mix within the next decade, with multiple case studies already in place, and a planned adoption as early as 2030. The question is whether green hydrogen can financially compete with the likes of diesel, natural gas and alternative forms of energy. This research investigates the financial feasibility of green hydrogen production in South Africa using solar energy. Three scenarios are considered: utilising only solar power source; a grid tied solar system with clean energy wheeled through the grid; and a standalone solar system coupled with battery storage. Each scenario is evaluated for three electrolyser sizes (2.4 kW, 120 kW and 500 kW) using a levelized Cost-of-Hydrogen (LCOH) analysis. The study reveals that a grid tied system, with clean energy being wheeled through the grid, offers the most cost competitive pathway for green hydrogen production. This scenario can achieve an LCOH of 140.00 ZAR/kg at 100% electrolyser utilisation, approaching the cost of blue hydrogen (131.00 ZAR/kg). However, standalone solar-battery systems face challenges to the high cost of battery energy storage. The lowest LCOH achieved is 328.00 ZAR/kg for a 500 kW electrolyser. A sensitivity analysis identifies electrolyser efficiency, solar and electrolyser CAPEX, and the cost of capital as the three primary factors influencing the LCOH. This study underscores the need for further technological advances in green hydrogen production, as well as supportive policies aimed at reducing the cost of green hydrogen production in South Africa, to enhance its competitiveness against existing sources of energy.
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    Miniaturised Charpy Impact Toughness Testing for the Characterisation of Laser Powder Bed Fusion - Built and Laser Shock Peened Ti-6Al-4V
    (University of the Witwatersrand, Johannesburg, 2025-09) Chundunsing, Abhay Nookant Netrapal; Polese, Claudia; Strydom, Tristan
    Laser Powder Bed Fusion (L-PBF) Additive Manufacturing (AM) might produce inconsistent results that require testing and documentation for qualification and, eventually, certification for aerospace applications. Literature has shown that the inconsistent results in part mechanical performance could be attributed to part features such as porosity and imperfections, residual stresses, microstructure, surface integrity, and microhardness. These inconsistencies can compromise the reliability, safety, and performance of aerospace components, necessitating rigorous testing and documentation to ensure compliance with stringent industry standards. Therefore, a preliminary testing method called the Miniaturised Charpy V-Notch (MCVN) impact testing is used to qualitatively assess the integrity of the parts produced. It also assesses the variations in the identified features that result from the manufacturing technique. Ti-6Al-4V test samples were manufactured with the intentional variation of the hatch spacing distance, stress-relieved, and prepared according to specification. Laser Shock Peening (LSP) post-processing was also selectively performed on some samples. MCVN tests, which were performed on the modified and recalibrated equipment, revealed that increasing hatch spacing of ideal settings by around 80% resulted in a significant and discernible impact toughness difference. The corresponding peened samples, tested under the same conditions, indicated a slight improvement in the recorded absorbed energy values. While the microstructural structure remained the same for both sample sets, the % porosity, the surface average, and the microhardness showed some changes. Another significant contributing factor was also the induction of compressive residual stresses recorded post-LSP, which was beneficial in countering crack propagation. This work provides significant information on the subject matter that can help as a stepping stone to achieve a standard procedure in the preliminary qualification of parts at minimal costs.
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    A Novel Clustering Approach for Minimizing Transportation Lanes of Complex Supply Chain Networks based on Economic Significance
    (University of the Witwatersrand, Johannesburg, 2024) Eardley, Matthew Peter; Bührmann, Joke
    This work studied a business problem in transportation management identified as an area of future research by Caplice and Sheffi (2003) and Acocella and Caplice (2023) and presented it as a fully formulated mathematical optimisation problem. This new clustering problem, here named the lane elimination clustering problem (LECP), is fundamentally multi-objective. The formulation includes the individual principal objective functions of the LECP as well as extensions of these functions that may represent additional measures of utility to some decision-makers. Known evolutionary algorithm methods were applied to solve the LECP for three problem instances using large-scale, privately owned datasets with up to 400 000 data points. Mutation and crossover operators, as well as constraint handling techniques, were developed as a general evolutional model of the LECP based on a priori knowledge of the problem domain. The applied genetic algorithms included the aggregation selection solution approach to provide a decision-maker with a Pareto front approximation that represents suitable trade-offs with respect to the various fitness functions. Focus, however, was given to Pareto dominance selection approaches to generate these solutions. The Pareto-based NSGA-II, SPEA2, PESA and PAES were applied to the LECP. Parallelization strategies were incorporated into these algorithms to improve performance. The performance data of these algorithms were empirically obtained and presented as a new comparative study of the efficacy of well-known multi-objective optimisation solution approaches applied to a constrained combinatorial problem. Results were compared and discussed as the basis for suggested approaches to solving the LECP. A single integrated pMOEA approach to optimize lanes was therefore provided to the field of transportation science. A new case study of evolutionary methods applied to a combinatorial multi-objective problem was also thereby contributed to the field of operations research. Although the problem was initially framed in the context of transport procurement event design, this research acknowledged the applicability of the LECP and its algorithmic optimisation to other areas of transportation management. This thesis concludes with a discussion regarding the relevance of understanding the trade-offs of this multi-objective optimisation problem with respect to these additional operational and strategic activities. Notes regarding the implementation of the LECP are given for each scenario, both in terms of the specific approaches to be used and the process by which the algorithms should be deployed.
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    An examination of the impact of leadership style on DRA Global’s talent retention and employee development in remote copper mining projects in the Democratic Republic of the Congo (DRC)
    (University of the Witwatersrand, Johannesburg, 2025-03) Govender, Rajesan; Doherty, Lorraine
    The increased demand for copper has resulted in a global uptake in copper mining projects. Subsequently, mining project houses must prioritise talent retention strategies to ensure competitive advantage and sustainable delivery of projects in this environment. In this study, DRA Global’s workforce was investigated to assess the influence of leadership styles on talent retention in remote copper mining projects in the Democratic Republic of Congo (DRC). The research followed a descriptive, quantitative approach and data was collected via Likert scale questionnaires distributed to project professionals in the research environment. The perceived importance and actual experience of leadership styles were assessed, along with the actual experience of their leader’s talent retention behaviours. The transformational leadership style was found to positively correlate with talent retention while laissez-faire and management-by-exception leadership behaviours were found to correlate with high attrition rates. Recommendations are made to further enhance leadership effectiveness by tailoring bespoke leadership programmes to address the unique challenges of remote mining projects. These leadership development initiatives offer opportunities to improve workforce stability in remote, copper mining projects in the DRC.
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    Towards standardized project management practices to improve renewable energy based microgrid design and deployment in South Africa
    (University of the Witwatersrand, Johannesburg, 2025) Oloo, Fiona Rose Amondi; Sunjka, Bernadette
    The deployment of renewable energy (RE) microgrid projects in South Africa faces significant project management challenges that impact efficiency and success. This study investigates project management practices in RE microgrid projects, identifying key success factors, challenges, and potential solutions. Through a critical literature review and two sets of semi-structured interviews, the research examines commonly used project management frameworks and methodologies, including PMBOK, CPM, CCPM, PERT, Waterfall, and PRINCE2 and also considers methodologies not common to the RE space such as Agile and Lean. Findings reveal that the Waterfall method is the most widely used due to its simplicity, though its rigidity presents limitations in adapting to project changes. The study highlights critical success factors such as leadership, communication, stakeholder engagement, and context-specific solutions. Key challenges identified include leadership and communication deficits, adapting solutions to local contexts, and project scope management. In addition, risk management is considered a priority concern across the project lifecycle. Based on these findings, the study proposes standardized project management practices tailored to the South African context. These recommendations include defining clear project success criteria, improving stakeholder and risk management, and incorporating complementary project management approaches to address existing shortcomings. The alignment between literature findings and participant feedback suggests the practical applicability of these recommendations. While this research provides actionable insights for improving RE microgrid project deployment, its scope is limited by the participant sample size. Future studies could expand on these findings by including a more diverse range of professionals to further refine best practices. This study contributes to addressing the challenges of RE microgrid deployment in South Africa by offering actionable recommendations. These insights aim to enhance the efficiency and success of microgrid projects, providing a foundation for improving energy access and sustainability in the region.