Masters Degrees (DPCMS)

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Browsing Masters Degrees (DPCMS) by Advisor "Dobreva, Petja"

Now showing 1 - 6 of 6
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    Assessment of fire and explosion hazards in large-scale battery energy storage systems intended for Namibian green hydrogen projects
    (University of Namibia, 2025) John, Laudika Lifoshiwana; Dobreva, Petja
    The integration of large-scale battery energy storage systems (BESS) is a pivotal component in advancing Namibian green hydrogen projects, aimed to promote sustainable energy solutions. But there are serious fire and explosion risks associated with the use of Battery Energy Storage Systems, particularly those that use lithium-ion technology. These risks are intensified by the chemical instability of lithium-ion cells and operational challenges associated with large-scale systems. This research investigates the specific risks and failure modes associated with BESS, aiming to provide safety solutions and guidelines for their broader application in renewable energy projects. The study begins with a comprehensive literature review, identifying the primary causes of fires/explosions in lithium-ion batteries, leading to thermal runaway, like electrical faults, and mechanical damage. It also examines various battery chemistries and their respective safety profiles, alongside an analysis of global case studies to draw lessons for Namibia. Fault Tree Analysis (FTA) and statistical tests were employed to pinpoint critical failure mechanisms, with emphasis on factors such as system design, battery age, and operational states during failure events. The study creates a thorough risk assessment model that emphasizes the risks that come with large-scale battery energy storage (BESS). This model evaluates critical factors such as thermal runaway, mechanical stress, and system design. Additionally, study explores potential mitigation strategies, including advanced battery management systems, robust fire suppression mechanisms, and the use of alternative battery technologies to improve overall system safety. By addressing the inadequate safety guidelines, deficiencies in Battery Management Systems (BMS), and failure mode analysis in various operational states, this study provides critical insights and recommendations for enhancing the safety protocols and the regulatory framework for BESS in Namibia’s Green Hydrogen projects. The findings aim to contribute to the safe and efficient deployment of BESS, thereby supporting Namibia’s transition to a sustainable energy future
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    Assessment of the performance of a Photovoltaic (pv) system for powering electrolysers in the green hydrogen project at Tsau//khaebs National Park using modelling and simulation approach
    (University of Namibia, 2025) Petrus, Jeremia Tangi; Dobreva, Petja
    The Namibian government, through the Southern Corridor Development Initiative (SCDI), aims to produce 300,000 tons of hydrogen annually at Tsau //Khaeb National Park using wind and solar energy. This thesis focuses on the PV system required to power the electrolyser, involving site analysis, component selection, and system optimisation using PVsyst and Fraunhofer Zenit. Economic evaluation was conducted via Levelized Cost of Energy (LCOE) calculations. A site investigation using QGIS, Google Earth, and SolarGIS determined the coordinates, area, topography, and solar resources. System sizing and optimisation indicated that 4,586,736 monofacial modules (610 W) are needed for the fixed-tilt system and 4,181,184 modules for the tracked system. The fixed system requires 803 inverters, while the tracked system needs 732. The land area required is 21.7 km² for the fixed system and 32.2 km² for the tracked system across both Springbok and Dolphin sites, respectively. Simulation results showed differences in performance ratio (PR). At Springbok, PVsyst reported 83.55% for the fixed system and 82.42% for the tracked system. At Dolphin, PR was 83.99% (fixed) and 82.75% (tracked). In Zenit, Springbok's PR was 76% (fixed) and 81.4% (tracked), while Dolphin's PR was 76.1% (fixed) and 81.6% (tracked). Zenit’s results were deemed more realistic due to its comprehensive modelling. The purpose of this study is to address the lack of independent research on the proposed SCDI Namibian Green Hydrogen project. The tracked system is recommended due to its superior performance, though further cost evaluations are necessary to address uncertainties
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    Assessment of the thermal and energy performance of Photovoltaic modules in Agrivoltaics systems
    (University of Namibia, 2025) Mbalundu, Hertha Liina; Dobreva, Petja
    The study evaluates the thermal and energy performance of photovoltaic modules in an agrivoltaic system in Benin, west Africa. This was done by employing three sets of heat transfer coefficients: Faiman, Benin, and Büren into the Faiman module temperature prediction model. The dataset for this study extends from April to July 2023, marked by high ambient temperatures exceeding 30℃. According to the findings, the cooling effect was significant for the results of Büren coefficients, and the agrivoltaic system generated up to 3.0% more energy than the non-agrivoltaic, especially at higher module temperature ranges of 40 ℃ - 55 ℃. The Benin coefficients demonstrated a moderate cooling effect, evidenced by a positive energy yield difference of up to 1.0% in the month of May. However, the cooling effect reduced in the hotter month of July resulting in a -1.0% energy difference between the two systems. The Faiman coefficient, on the other hand, demonstrated no cooling effect, as shown by consistently yielding negative energy differences, especially in May (-1.0%). The statistical analysis indicates that the Faiman coefficients provided a closer fit to the actual Benin-derived temperatures (R2 : 0.99 and MAE: 0.54 ℃). Whereas the results from the Büren coefficients showed the strongest cooling effect, achieving a reduction in module temperatures of up to 4℃ relative to the non-agrivoltaic system. The findings highlight the need for site-specific coefficient tuning to enhance the accuracy and the reliability of the findings
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    Enhancing solar photovoltaic efficiency with porous silica coatings
    (University of Namibia, 2025) Namwiha, Leonard Etuna; Dobreva, Petja
    Solar surface glass is known to exhibit reflectance loss of no less than 4%, depending on the angle of the incident light. Furthermore, the high operating temperature of the solar photovoltaic (PV) module also reduces the solar PV module efficiency by approximately 0.45 − 0.50 %/℃ depending on the temperature coefficient and the type of the solar modules[1]. The study investigated porous silica which is known to have high transmittance in the solar spectrum range (0.3-1.1μm) and high emissivity in the mid-infrared range (8-13μm) due to its bonding structure. The research employed the base/acid double catalysis technique of the sol-gel method, using Pluronic F127 as a surfactant, Tetraethylorthoxysilicate (TEOS), ethanol, hydrochloric acid, ammonium hydroxide, hexamethyldisilazane (HMDS) and distilled water to synthesise silicon dioxide sol. The sol was afterwards spin-coated on a glass substrate, resulting in a porous silica layer approximately 200 nm thick. Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and Ultraviolet-Visible-Near Infrared Spectroscopy (UV-Vis-NIR) spectrophotometer were employed to investigate the optical characteristics of the coatings. The study achieved an approximate 2% increase in transmittance within the solar spectrum (0.3- 1.1μm) with a single porous silica layer with 8% emissivity in the mid-infrared range (8-13μm). In addition, it observed a nearly 20% enhancement in emissivity with three layers in the mid-infrared range (8-13μm), while transmittance in the solar spectrum (0.3-1.1μm) decreased almost linearly by 8% from 0.3-0.55μm with three layers
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    Modelling and analysis of a photovoltaic system for a local business in Windhoek, Namibia
    (University of Namibia, 2025) Kauluma, Aina; Dobreva, Petja
    Photovoltaic (PV) technology generates electricity from light. There are two types of PV technologies in the market: traditional monofacial solar cells, which capture light on their front side, and emergent bifacial solar cells, which capture light on both their rear and front sides. Studies focusing on the performance of bifacial solar modules in Windhoek have not yet been conducted, so their potential advantages in this loca tion are unknown. The study aimed to model and evaluate the PV systems based on monofacial and bifacial silicon (Si) technologies. This feasability study was conducted for a business in Windhoek, Namibia. The evaluation was conducted by assessing the specific yield, performance ratio criteria, and the levelized cost of electricity (LCOE) for the systems modelled within the same specified location using the PVsyst soft ware. The systems are a bifacial single-axis tracking PV system, a bifacial fixed-tilt PV system, a monofacial single-axis tracking PV system, and a monofacial fixed-tilt PV system, all with similar technical parameters. The results showed that the en ergy production of the single-axis tracking bifacial system is higher than that of the monofacial system; however, there is no statistically significant difference between the two. On the other hand, the fixed-tilt bifacial PV system significantly outperforms the fixed-tilt monofacial PV system. Additionally, the single-axis tracking monofacial PV system has the shortest payback period of 3 years, 2 months with an ROI of 35.62%, while the fixed-tilt bifacial PV system has the longest payback period of 3 years, 8 months and an IRR of 31.50%. The system that performs the best financially is the single-axis tracking monofacial PV system with an LCOE of N$ 0.85/kWh
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    PV-powered membrane system control for continuous autonomous water solution in remote areas
    (University of Namibia, 2025) Kasheeta, Rauna Ndapandula; Dobreva, Petja
    This research addressed the challenge of Solar Irradiance (SI) fluctuations, which adversely affect the performance of photovoltaic-membrane (PV-membrane) systems used for water purification. These fluctuations lead to reduced permeate volume and quality, as well as increased specific energy consumption. The primary aim of this research is to incorporate mechanical energy storage and develop a hydraulic buffering control method to enhance system performance under varying SI conditions. To achieve this, a hydraulic energy storage system utilizing a bladder tank was implemented, designed to buffer periods of SI fluctuations. A control algorithm was developed that allows the hydraulic bladder accumulator to discharge during low solar irradiance periods for buffering and charge during high solar irradiance periods by monitoring power ramp down rates. Results indicate that, in the worst-case scenario of a very cloudy day, the system produced an additional 98.5 L of permeate while maintaining permeate quality within the WHO palatable limit of 1.13 mS/cm. Furthermore, the average specific energy consumption was reduced by 38%. The algorithm effectively prevented system pressure from dropping to zero, thereby maintaining system stability despite fluctuations caused by SI changes. Future investigations should focus on minimizing pump shutdowns during hydraulic buffering due to increased pressure resistance. This research contributes to sustainable water solutions in remote areas, offering a promising approach to enhance the reliability and efficiency of PV-powered membrane systems