Theses and Dissertations

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ACE one cook stove
(National University of Lesotho, 2021-07) Qoola, Thato; Thamae, Thimothy
The study was conducted to evaluate the performance of ACE One cook stove which is manufactured by African Clean Energy (ACE) in Lesotho by assessing the performance of different solid biomass fuels within the stove. Pellets, pine wood, corn cobs and cow dung provided by ACE were used in this study where cooking time, energy consumption, heat transfer, combustion temperature and particulate matter emissions were assessed. The heating values were determined using Proximate Analysis, the values ranged from 13.43 MJ/kg for cow dung to 17.65 MJ/kg for corn cobs. Measurement of air pollutants were performed using mobile air quality monitor and combustion temperature measurements were performed using infrared thermometer. The temperature was measured for each fuel and the highest temperature was found when using wood, about 460 °C, followed by corn cobs with 370 °C, pellets with 340 °C and cow dung with 290 °C. However, the pellets had the most sustained heat compared to other fuels. Using wood and corn cobs transferred heat faster due to their big flame and raised the temperature of the water quickly. When using wood, water in a pot gained 610 kJ in 9 minutes, with corn cobs, pellets and cow dung, energy gained was 410 kJ, 350 kJ and 240 kJ respectively. Water Boiling Tests (WTB) results showed that the use of cow dung required much more fuel and an extended cooking time compared to other fuels. The second WBT using a different mass to test refuelling showed that refuelling slowed the cooking process. When burning the fuels in a closed room, the PM2.5 emissions for all the fuels were above 425 μg/m3, which was considered as hazardous level. Cow dung emitted more particles than other fuels during combustion which lasted longer in a room. The pellets showed the lowest emissions of them all in both open and closed room. In a closed room, the highest value for the pellets was 800 μg/m3 while other fuels had reached 999.9 μg/m3. The values obtained when burning the fuels in an open room had shown a significant decrease in emissions, 60.3 μg/m3 for pellets, 144.7 μg/m3 for wood, 234.2 μg/m3 for corn cobs and 612.4 μg/m3. The study further assessed the performance of the charging system that comes along with the stove. The power dissipated by the solar panel in this study was less than its rated power. The highest value from 4 experiments done one different days was 8.57 W. Time taken to charge the stove with a wall charger was shorter than using a solar panel. Using the battery of the stove to charge a cell phone has shown high power usage but using it for powering LED lamp has shown to be discharging the battery at a very slow rate.
Analysis of Quthing River and Letseng-laLetsie for Hydropower Potential
(National University of Lesotho, 2020) Lekhanya, Liteboho; Dr Khaba, L.; Dr Makhele, M.
This dissertation presents the analysis of Quthing River and Letseng-la-Letsie for hydropower potential in Quthing district in Lesotho. Electrical power deficit in the country is more prominent in rural areas like Quthing District. This calls for assessment of electrical sources in the vicinity of rural area load centers to inform policies for electrical production so as to curb power deficit problem. Mountain Rivers like Quthing River with steep slopes or gradients naturally provide good head which needs to be assessed along with its flow rates. Furthermore elevated dams like Letseng-la-Letsie can also provide a natural good head which needs to be assessed alongside with its discharge rates. The assessment was carried out by employing catchment area method to asses flow rates since the abstraction points of the study areas were ungaged and lacks data. The maps in association with QGIS were used to evaluate heads of the study areas and lastly TURBNPRO was used to determine power outputs from the study areas. The resultant net head for Quthing River was found to be 164.15 m while the net head for Letsengla-Letsie was 159.23 m. The design flow rate of Quthing River was found to be 0.58 m3/s while that of Letseng-la-Letsie was 0.1 16 m3/s. The results from TURBNPRO showed that the power output for Quthing River turbine was 815 kW while the power output for Letseng-la-Letsie turbine was 221 kW. Using typical hydro-electric generators efficiency of 99% and typical capacity factor for Africa of 0.49, the capacity from Quthing River was found to be 807 kW with annual energy of 3.46 MWh. The capacity for Letseng-la-Letsie was found to be 0.22 MW with annual energy of 0.95 MWh.
Analysis of the viability of using thermal energy for Maluti Mountain Brewery
(National University of Lesotho, 2021-04) Lillane, Malillane; Mr. Hove, Tawanda; Dr. Mpholo, Moeketsi
It has been established by literature that there is worldly movement towards renewable energy usage because of global warming. Solar energy among many is one form of renewable energy that can be used to reduce conventional energy usage. This study realized an opportunity to reduce the conventional energy (coal) use at Maluti Mountain Brewery (MMB); a brewery in Lesotho by preheating the boiler make up water. The boiler at MMB is serviced by condensate (70°C) and the cold water from the tap. The cold makeup water mixes with the condensate prior to the being carried into the boiler and thus reducing the efficiency of the boiler. This is because the boiler in turn demands a lot of coal to heat up the boiler feed water. A retrofitted solar thermal system into the existing system at MMB was done. This system was aimed at preheating the cold make up water before it mixes with the hot condensate in order to avoid the makeup water from reducing the condensate temperature. An Excel based model was made in order to design a solar thermal system that is cost effective and technically viable. The designed system is an active solar thermal system composed of evacuated tube collector with the EPD of 18 kWh/$), collector area of 80 m2 which was decided upon by the required maximum storage tank temperature of 100 °C. The storage tank size of the system was found to be 2110 Liters. A tank of such size could not be found on the market; therefore, a 2500 Liters storage tank would be ideal for the purpose. The actual collector area decided upon according to the collector aperture area of 2.998 was found to be 81 m2. The system was found to be able to preheat 54% of the makeup water (12 % of the boiler feed water is the makeup water). The amount of coal used by MMB would be reduced by 11% and therefore saving the company as the NPVSS is positive, amounting to $25044 for over 20 years.
Application of lie symmetrics to solving fractional black-scholes option pricing model in financial mathematics
(National University of Lesotho, 2022-10-21) Ramoeletsi, Realeboha; Kaibe, Bosiu, Ngaka Nchejane
We perform Lie symmetry analysis to the fractional Black-Scholes option pricing model whose price evolution is described in terms of a partial di erential equation (PDE). As a result, new complete Lie symmetry group and in nitesimal generators of the one-dimensional fractional Black-Scholes pricing model are derived. Furthermore, we compute a family of exact invariant solutions that constitute the pricing models for the Black-Scholes model using the associated in nitesimal generators and the corresponding similarity reduction equations. Using known solutions, more solutions are generated via group point transformations
Application of Lie Symmetry method in pricing Arithmetic Asian options
(National University of Lesotho, 2024-06-23) Kubeletsane, Monts'uoe Edward
This research investigates the application of Lie symmetry method to find analytic solutions for arithmetic Asian options, which are crucial financial derivatives for managing risk in various commodity markets. By employing a two state partial differential equation approach, the study uses Lie symmetry method to enhance option pricing models. The research involves finding determining equations, infinitesimal generators, and invariant solutions, as well as examining the influence of parameters such as volatility, interest rates, and time on option prices.
Application of solution state NMR to structural problems in chemistry
(Durham University, 2006-09) Khoabane, Ntai Martin; Dr. Sanderson, John; Dr. Grayson, Elizabeth; Dr. Natrajan, Louise; Mr. McKeag, Ian; Mrs. Heffernan, Catherine
First and foremost I would like to thank the Lord almighty for the life he has given me. My stay and study at Durham University was funded and supported by Canon Collins Trust to whom I am very thankful. I would also like to pass my gratitude to the National University of Lesotho for releasing me on staff development leave, my dependants’ allowance, and funding my travel both ways. I would like to thank my supervisory team: Dr. Alan M. Kenwright for his supervision and training and demonstrated kindness and patience. He motivated and encouradme during this period. I am also grateful to him for coming up with original ideas of a project on which I worked. Dr. John Sanderson cannot be forgotten for his co-supervisory role. I am also grateful to Dr. Elizabeth Grayson for the supervision in chemistry and for the protection and deprotection of the mannoside compounds. Dr. Louise Natrajan, I thank you for the lanthanide complexes I worked on. I would also like to thank Mr. Ian McKeag and Mrs Catherine Heffernan who contributed a lot to my training in solution state NMR. Other groups of people who contributed to my training need to be mentioned: all my lectures in the taught modules, the mass spectrometry facility and all the Chemistry Department staff. Last but not least my family members. Most importantly my wife and son who suffered the loneliness of my being thousands of miles away from them without complaint. Nuclear Magnetic Resonance (NMR) spectroscopy is a robust, non invasive technique applicable in structure determination as well as in the study of dynamic behaviour of chemical compounds. This thesis is in two sections, the first dealing mainly with a structure determination application of NMR and the second dealing mainly with a study of dynamic behaviour. Section 1 NMR characterisation of carbohydrates has proved challenging because of the limited chemical shift ranges of both the proton and carbon signals. The broad signals due to the labile hydroxyl protons cause further complications by overlapping proton signals from the ring. Protecting group chemistry is vital in the preparation and manipulation of synthetic carbohydrates and can potentially help with the assignment of the (otherwise extremely complicated) NMR spectra of carbohydrates. However, the widely used benzyl protecting group can make the spectrum more difficult to interpret because the benzyl CH2 proton signals often come in the same region of the spectrum as the anomeric protons, usually used as reporter groups of carbohydrates and the benzyl CH2 carbon signals come in the same region as the carbohydrate ring carbons. This section reports the invetsigation and application of a family of alternative protecting groups, namely various fluorobenzyl groups, which have not been used in carbohydrate chemistry before. With pentafluorobenzyl, the proton chemical shift dispersion is improved, and the CH2 and carbohydrate ring carbon signals are shifted to lower frequency, considerably simplifying the task of assigning the carbon spectrum, facilitating the interpretation of all 1H-13C correlation experiments (HSQC, HMQC, HMBC). Section 2 Cyclen complexes of lanthanide (III) ions have found use in magnetic resonance imaging (MRI), luminescence imaging and assay studies. In particular, europium (III) complexes have potential in anlytical, forensic, and biomedical applications based on their impressive emissive properties. However, the emissive properties are modulated by the thermodynamic stability and kinetic inertness of the complexes. For biomedical applications, chelation is necessary to avoid europium toxicity that may be triggerd by accidental dissociation of the complex and release of the metal in vivo. A new cyclen europium(III) complex with pyridyl pendant ligands instead of the usual acetate groups has been synthesised by a group at Manchester University. The pyridyl ligands confer higher emmisive intensities to the complex, to enable applicability of the complex in time gated measurements. The chemical structure determination of the compound was accomplished by 1H, 13C, COSY, HMQC / HSQC and EXSY NMR experiments. Selective inversion experiments data were evaluated using the CIFIT simulation program, and showed that in aqueous solutions from -0.2º C to 107.6º C the dominant dynamic process is flipping of the pendant (pyridyl) arms, and isomerism is biased towards the twisted square antiprism (TSAP).
Catalytic Behaviour of Anionic Metalloporphyrins towards the Synthesis of Water- Soluble Polyaniline
(National University of Lesotho, 2011-05) Phooko, Mathese Palesa; Ass.Prof. Sekota, M.
In this study, metalloderivates of anionic tetrasulphonated tetraphenyl porphyrin (MTPPS4, where M= Ru(III) and Rh(III)) were synthesized and characterized and later utilized in the synthesis of water-soluble Polyaniline (PANi). The selected metalloporphyrins were synthesized with very low percentage yields. It was found that the RUTPPS4 was more effective as the homogeneous catalyst than RhTPPS4 as it showed a high turnover. This was attributed to the size of Ru3+ and the relative ease of oxidation of Ru(III) to Ru(IV). The synthesis and properties of PANi prepared are reported. The processabilty of the polymer was examined and it was found to be soluble in water and polar aprotic solvents like dimethyl formamide (DMF). The clewed nanostructured porous PANi exhibited rich electrochemical features which are interesting in the field of sensors and actuators.
Characterisation and Application of Municipal Sewage Sludge to Agricultural Land in the Maseru Metropolitan Area
(National University of Lesotho, 2011) Khesa, Makhale E; Tanor, E.B.
The nutrient content and other important properties of the sewage sludge from the Wastewater Treatment Plant at Ha Ratjamose in Maseru were determined. In addition, the sludge was characterised in terms of its, pH, salinity, TDS and temperature. The sludge was found to contain 0.011 - 0.013 (wt%) PO43- and 0.018 - 0.070 (wt%)NO3- with D/R 2000 Spectrophotometer. The values for some important physical properties were found to be as follows: pH,( 6.35-6.59); conductivity,( 335- 1674μScm-1) , salinity,( 0.00-0.6) , total dissolved solids (TDS) ,( 355-1576mgL-1) and temperature ,( 24.1-25.5˚C). The sludge was found to contain considerable amounts of nutrients, but lower than those found in commercial chemical fertilizers. It was also slightly acidic, hence it can be more appropriate if applied to strongly alkaline soils or be stabilized with alkalis if it is to be applied to neutral of acidic soils.
Construction of a long-term hourly electricity demand curve and peak load using MAED-EL for Lesotho
(National University of Lesotho, 2020) Kente, Leana
At the time that this study was undertaken, Lesotho Electrical Company (LEC) had no longterm hourly load curve forecast for electricity consumption. This makes it difficult for the utility to plan for future power plants and cost effective bilateral agreements as well as policy maker to make informed decision and for Independent Power Producers (IPPs) to be developed by investor. Therefore, this study aimed to construct a long-term hourly load curve for future electricity consumption in Lesotho starting with 2018 as the base year, followed by five-year long intervals from 2020 to 2040. The Model for Analysis of Energy Demand (MAED-EL) was used to calculate future hourly load curves for electricity and it uses the end-use approach when calculating the energy projections. Three scenarios were considered in this study to model possible trajectories of future electricity consumption, namely: Business-as-Usual (BAU), Low Economy Scenario (LE) and High Economy Scenario (HE). The annual growth rates of electricity consumption were estimated to be 4.3% for BAU, 2.4% for LE and 6.3% for HE. The projected peak demand for each scenario occurs during winter season (June to July). It was anticipated that the peak load will grow by 224% 123% and 54% for HE, BAU and LE scenarios from 2020 to 2040 while the energy consumption will increase by 223%, 122% and 53% for HE, BAU and LE from 2020 to 2040. The base load was predicted to grow from 58.77 MW,56.79 MW and 54.74 MW for HE,BAU and LE to 190.05 MW, 126.29 and 84.29 in for HE,BAU and LE respectevely in 2040 . Due to growth of electrical energy load the power deficit which was already high in 2018 at 94.44 MW would increase to 539.92 MW, 330.1 MW and 196.44 MW for HE, BAU and LE respectively in 2040. The Peak Load of the system was equal or above 75% of system peak load for 20% of the available time of the year.
Design and analysis for a feasibility study of a floating solar PV power system for Metolong Dam
(National University of Lesotho, 2022-06) Moqulo, Rorisang Christopher
Over the past years, an increasing capacity of floating solar photovoltaic (FSPV) technology utilizing water bodies to install solar power has been implemented, showing an alternative for countries where land use is constrained, land is not easily accessible, or land leasing is expensive. In addition to reducing land use competition, FSPV is promoted as a more efficient solar technology, bringing with it additional benefits such as reduced water evaporation and decreased algae growth. Based on previous field studies and industry insights, this study aims to analyse whether an FSPV project can be a feasible and cost-effective option for electricity generation and usage at Metolong Dam and water treatment works (WTW) located in Maseru district, Lesotho. Furthermore, PV module temperature analysis is another critical area, governing the efficiency performance of solar cells. In this study, the initial approach entailed the modelling of the Metolong reservoir water temperature (using Microsoft Excel) due to insufficient water temperature data at a selected location (since simulation software does not have features for FSPV). Then water temperature was used to investigate the photovoltaic (PV) module temperature on water bodies. The optimal sizing and performance prediction of a proposed power plant was modelled using a set of mathematical equations in a spreadsheet application (Microsoft Excel) and PVSyst software. Both models were compared to analyse the difference in annual electricity generation. Then, an economic analysis was performed to showcase the Levelized Cost of Electricity (LCOE) and Net Present Value (NPV). Finally, an evaporation model was proposed with the objective to quantify the potential savings an FSPV could provide using the calculations adapted from the Penman-Monteith model. The results indicated that this FSPV power plant would significantly contribute to the reduction of carbon dioxide (CO2) emissions. The recommended FSPV, with total installed capacity of 7.8 MWp, would consist of 3 platforms with an installed power of 2.6 MWp each. The study reveals that the proposed FSPV energy generation system is about 3.4% higher than ground-mounted PV (GMPV) generation system predicted by the PVSyst software due to the cooling effect provided by water just below the panels. From the simulation results, the value of performance ratio (PR) comes out as 90%, and the capacity utilization factor (CUF) value is 15.21% with a total effective energy generation at the output of the array of 17,345 MWh per year. The system could meet up to 70% of load demand during a typical day in winter months at the selected facilities. The FSPV system could cost US$ 10 Million with a payback period of 13 years, where the largest contributors to this cost are related to the floating structures and anchoring system of this plant. The proposed FSPV plant will substantially reduce the cost of energy as the plant cost is expected to be considerably reduced based on the low LCOE of 36.4 $/MWh. The economic feasibility of a FSPV system on a Metolong reservoir was thus established, and may be considered an efficient use option for electricity generation in Lesotho. Additionally, the shading provided by the FSPV system can save up to 84,136 m3 of water annually. The annual reduction of greenhouse gas (GHG) emissions was analyzed and found to be 17,329 tCO2 per year. Future studies should include more in-depth research into factors such as the impact of substation upgrade costs, variable interest rates, economies and environmental impacts
Detection and Estimation of Aflitoxins in Groundnut and Groundnut Materials
(National University of Lesotho, 2011-05) Nkhabu, Rethabile A; Prof. Alemayehu, G.C
The aflatoxins are well suited for analysis by Thin Layer Chromatography (TLC) since most of the compounds fluoresce under long wave ultraviolet (UV) light. The TLC technique serves as both purification and quantitation step. Before the TLC analysis, the peanut butter and crushed groundnut (peanuts) samples were separately de-fatted with light petroleum (boiling point 40 to 600C, ant the toxins within the samples were extracted from the de-fatted samples with methanol, and the extracts were purified by repetition solvent partition technique. The solvents used in the former technique were water-methanol mixture and chloroform, and aflatoxins have high affinity for chloroform. The obtained extracts were diluted to desirable concentrations and were then used for TLC analysis using silica gel Kieselgel G chromatoplate, and the mobile phase as the methanol-chloroform combinations. The quantitation of the results obtained was by fluorescence using fluorescent lamp (365 nm).
Determinants of choice of household energy use in Lesotho
(National University of Lesotho, 2020-05) Mothala, Matsoso; Dr Mpholo, Moeketsi; Mr Thamae, Rets'elisitsoe
With the need to achieve Sustainable Development Goals, modern clean household energy choice forms the basis for heeding this call. In developing countries, most of the population lives in rural areas and is characterized by high dependence on polluting biomass for cooking and heating while they rely predominantly on paraffin and candles for lighting. Women and children in developing countries spend an appreciable amount of time collecting the biomass, hence unable to carry out other development activities. The use of modern technologies such as solar home systems for lighting could help pupils study at night with adequate light and with no adverse effects on their health. Nevertheless, the determinants of household energy choice have not been studied in many developing countries including Lesotho, despite the potential benefits of such a study. This study uses the data collected by Lesotho’s Bureau of Statistics through a national household energy consumption survey of 2017, to develop a multinomial logistic regression to identify and analyze the determinants of the choice of household energy use. The results indicate that income, as predicted by the energy ladder model is statistically significant for the choice of clean energy fuels. But other socio-economic factors such as gender, education, household size, and settlement type also play an important role in the choice of clean energy choice. The role of gender in the choice of fuels used within a household is generally statistically insignificant. There is not a clear distinction of preference, on the choice of fuel, between male-headed households versus female-headed households. An increase in the education level of the household head is statistically significant in choosing cleaner fuels. This suggests that public policies should have a strong focus on improving formal and informal education to increase awareness of clean energy fuels and their benefits. Household size is negative and statistically significant for the choice of clean fuels over traditional fuels. Large households have enough labour that is required for the collection of traditional fuels. In rural settlements, electricity is hardly used for either cooking or water heating, it is used only for lighting. This suggests that policies, for economic reasons, should not focus on extending the grid to the rural areas but to promote domestic systems and micro-grids that provide enough electricity for lighting and household entertainment.
Determination of Cost-Reflective Feed-in Tariff for Grid Connected Solar PV Systems in Lesotho
(National University of Lesotho, 2020-05) Kokome, Limpho
Lesotho needs a feed-in tariff policy that can help accelerate integration of renewable energy in its electricity grid. In this study a method to determine the feed-in tariff for grid connected solar Photovoltaic (PV) systems was developed. The necessity to set different tariffs for different locations in terms of the solar PV array yield 𝑌, and different tariffs for different installed capacities were examined. Location specific tariffs were examined because given a particular solar module, the array yield 𝑌 could vary with location because of different ambient temperature and radiation, while size specific tariffs were examined because solar PV systems have different specific costs for different system sizes. In order to determine the cost reflective feed-in tariff, the Levelized Cost of Electricity (LCOE) was used as the objective function. With this approach the feed-in tariff was set as the price for selling electricity that is reasonably above the unit cost of production. A custom spreadsheet model was used to calculate the solar PV array yield 𝑌 over Lesotho. This array yield was used to divide Lesotho into two regions, low yield regions, and high yield regions. Representative systems were chosen and the feed-in tariff for different solar PV installed capacities in both regions were determined. The study found that the feed-in tariff varies with location and system size as follows; System Category FiT ($/kWh) Low Array Yield Region High Array Yield Region 30 kWp Roof Mount 0.1778 0.1616 500 kWp Roof Mount 0.1597 0.1451 30 kWp Ground Mount 0.1740 0.1581 500 kWp Groun Mount 0.1453 0.1321 10 000 kWp Ground Mount 0.1138 0.1034 The study recommends a feed-in tariff that is both location and size specific. The feed-in tariff depends on duration of the tariff with shorter periods resulting in higher feed-in tariff. A 20-year duration of the feed-in tariff is therefore recommended by this study. The method used in this study to determine the feed-in tariff included the impact of inflation in the analysis and therefore a fixed feed-in tariff (that is not indexed to inflation) is recommended. The energy regulator, and theministry responsible for energy policy setting can make use of this study in setting out feed-in tariff policy.
Determining cost-effective integration renewable energy resource plan for Lesotho (2022-2040)
(National University of Lesotho, 2022-07) Nzemene, Tsoarelo Nelson
The renewable energy potential for Lesotho has been sufficiently studied with only a limitation of which specific places could such energy be derived. The country does not have an integrated renewable energy plan (IRP) to help direct its efforts to address the problem of energy insecurity, low energy supply and over 50 percent dependence on electricity imports from South Africa and Mozambique. Most of the resources have been spent haphazardly and unprofitably in a bid to address access to energy problem. The objective of this study is to create an IRP that responds to cost effectiveness in Lesotho for 2022 to 2040 and to identify suitable places for renewable energy generation using Geographic Information System (QGIS) capabilities in order to increase the baseload capacity for Lesotho. These objectives were achieved by evaluating the existing renewable energy resources, especially solar and wind by determining suitable places for power generation to meet the ever-growing demand. This was achieved by first establishing the aggregated forecast electricity demand using the existing studies and this forecast formed the basis for envisaged future power demand for Lesotho. For example, the electricity demand is projected to reach 350MW in 2040. Secondly, proximity analysis results of the resource base to the grid, primary road infrastructure and substations at 3.5km and 15km buffer zones were done to determine suitable areas for renewable energy generation. The identified places were examined and the amount of energy that could be generated from them was estimated and evaluated. The findings showed that a total of 310MW added into the main grid cumulatively from both wind and solar resources from 2022 to 2040 would result in electricity supply independence for the country. The cheapest option in a generation was given first priority in terms of when to enter into the generation stream to meet the existing demand during scheduling in the determination of the optimum IRP. The study recommends a progressive reduction of imports since they can serve as safety buffers of the electricity network in the event hydropower is not sufficiently developed. The energy policy, renewable energy policy and other energy supply and demand instruments will be profited by this study.
Development of charcoal briquettes using Sehalahala (Seriphium plumosum and Felicia filifolia)
(National University of Lesotho, 2020-08) Thabane, Kanono; Prof Mekbib, Sissay
Introduction: Production of charcoal briquettes using invasive shrubs found on Lesotho’s rangelands can provide alternative sustainable biomass energy for household heating and cooking applications in rural Lesotho. Objectives: To develop briquettes using the two species of Sehalahala (Seriphium plumosum and Felicia filifolia) and evaluate the performance properties of charcoal briquettes made from the two shrubs. Methods: Sehalahala feedstock was harvested and dried for five days to reduce the moisture content. Dried materials were cut and carbonised using a 200L steel drum. Wheat and clay binders were added at 5% (w/w) with charcoal powder and mixed together. Puck shaped briquettes were developed using a car jack driven briquetting machine. Four treatments (2 species and 2 binders) were developed and compared with a briquette purchased from the local supermarket for benchmarking. Proximate analysis was conducted using ASTM standards. Caloric value (MJ/Kg) was calculated using an empirical formula. Ultimate analysis was undertaken using a LECO CHNS 628 Determinator. Results: The mean percentage value of the four manufactured briquettes for the respective parameters evaluated were found to be as follows: moisture content (6.83 ± 2.72) m %,volatile matter content (30.53 ± 5.93) m %, ash content (3.77 ± 1.10) m %, fixed carbon (58.88 ± 6.51) m %, and higher heating value (25.66 ± 1.28) MJ/kg. In addition, the results indicated that the clay binder yields higher calorific value compared to the boild wheat flour suspention mix. Results of the ultimate analysis showed total carbon (35.14 ± 4.13) %, total nitrogen (1.01 ± 0.20) %, hydrogen (2.13± 0.26)% and sulphur (0.34 ± 0.08) %. Conclusion: Based on the results, it can be concluded that Sehalahala is suitable for production of bio-char briquettes. The newly produced briquettes have a higher energy content, less indoor air pollution and burns longer than traditional biomass (cow dung, agro-residues, shrubs, wood, etc) used in rural Lesotho for cooking and laughing applications. However, the results also indicate an opportunity for optimising production methods in order to achieve better results for mass production.
The development of highly selective modified glassy carbon electrode on acted carbon-iron oxide/graphene foam for electrocatalytic oxidation of uric acid and dopamine
(National University of Lesotho, 2023) Mpakanyane, Teboho
This research study explores the application of nanomaterial-modified glassy carbon electrodes (GCE) for the voltammetric determination of dopamine and uric acid. The GCE was fabricated with iron oxide, activated carbon, and graphene foam. Energy Dispersive X-ray Spectroscopy (EDS), Fourier Transform Infrared spectroscopy (FT-IR), X-ray diffraction Spectroscopy (XRD), and Scanning Electron Microscopy (SEM) were used to examine the microporous activated carbon, iron oxide spherical structure (Fe3O4) particles that were attached to the graphene foam sheets. A drop-dry method was used for electrode modification. AC-Fe3O4/GF/GCE was electrochemically interrogated in the ferrocyanide redox probe using cyclic voltammetry. The current intensity and the reversibility of the redox probe were enhanced in the presence of the electrochemical sensor. Differential pulse voltammetry technique (DPV) was employed for individual determination of uric acid under the optimized experimental conditions; pH 6, scan rate 50 mV s -1 , pulse width 0.05 s, pulse amplitude 0.05 V, and supporting electrolyte 0.1 M phosphate buffer solution. A detection limit of 2.55 µM was obtained with an analytical linear range of 5 - 1630 µM. All selected foreign species showed no significant interference with the electrochemical determination of uric acid. Furthermore, dopamine analysis was carried out on AC-Fe3O4/GF/GCE using DPV. The electrochemical sensing was also optimized at various analytical conditions and a detection limit of 1.47 µM was obtained in the linear dynamic range of 2.5 to 450 µM. Glucose, glutamic acid, l lysine, and ascorbic acid are a few of the interfering species that exhibited almost no impact on dopamine detection. In addition, the simultaneous determination of uric acid and dopamine was conducted successfully. They have been determined by differential pulse voltammetry, and the modified electrode exhibited a linearity relationship over a wide range of uric acid concentrations from 2.5 to 450 μM, with a detection limit of 1.75 μM, (s/n = 3). A linear trend for the current response for dopamine concentrations ranging from 5 to 400 μM, with a detection limit of 2.7 μM, has also been obtained. The results, therefore, demonstrated the sensor’s superior electrocatalytic activity and its high selectivity for dopamine and uric acid even when some foreign species were present. The average V recoveries from the real sample analyses of the urine samples showed that the proposed sensor could be put to use in the real sample analysis. The developed electrode was generally found to be highly selective and sensitive toward uric acid and dopamine. It has achieved better sensing performances with a very low detection limit, wider linear ranges, and short analysis times as compared to most previously reported modified electrodes for the same analytes. Furthermore, the developed electrode was validated successfully for real sample analysis in biological fluids. The proposed methods have many attractive features, such as low cost, simplistic electrode preparation procedure, easy renewability, long-term usability, and rapid analysis. The developed electrode also displayed good repeatability and selectivity towards interfering substances. It is a promising modified electrode for the electrochemical detection of other electroactive important compounds in biological systems.
The development of highly selective modifies glassy carbon electrode on activated carbon-iron oxide/graphene foam for electrocatalytic oxidation of uric acid and dopamine
(National University of Lesotho, 2023) Mpakanyane, Liteboho
This research study explores the application of nanomaterial-modified glassy carbon electrodes (GCE) for the voltammetric determination of dopamine and uric acid. The GCE was fabricated with iron oxide, activated carbon, and graphene foam. Energy Dispersive X-ray Spectroscopy (EDS), Fourier Transform Infrared spectroscopy (FT-IR), X-ray diffraction Spectroscopy (XRD), and Scanning Electron Microscopy (SEM) were used to examine the microporous activated carbon, iron oxide spherical structure (Fe3O4) particles that were attached to the graphene foam sheets. A drop-dry method was used for electrode modification. AC-Fe3O4/GF/GCE was electrochemically interrogated in the ferrocyanide redox probe using cyclic voltammetry. The current intensity and the reversibility of the redox probe were enhanced in the presence of the electrochemical sensor. Differential pulse voltammetry technique (DPV) was employed for individual determination of uric acid under the optimized experimental conditions; pH 6, scan rate 50 mV s-1, pulse width 0.05 s, pulse amplitude 0.05 V, and supporting electrolyte 0.1 M phosphate buffer solution. A detection limit of 2.55 µM was obtained with an analytical linear range of 5 - 1630 µM. All selected foreign species showed no significant interference with the electrochemical determination of uric acid. Furthermore, dopamine analysis was carried out on AC-Fe3O4/GF/GCE using DPV. The electrochemical sensing was also optimized at various analytical conditions and a detection limit of 1.47 µM was obtained in the linear dynamic range of 2.5 to 450 µM. Glucose, glutamic acid, l-lysine, and ascorbic acid are a few of the interfering species that exhibited almost no impact on dopamine detection. In addition, the simultaneous determination of uric acid and dopamine was conducted successfully. They have been determined by differential pulse voltammetry, and the modified electrode exhibited a linearity relationship over a wide range of uric acid concentrations from 2.5 to 450 μM, with a detection limit of 1.75 μM, (s/n = 3). A linear trend for the current response for dopamine concentrations ranging from 5 to 400 μM, with a detection limit of 2.7 μM, has also been obtained. The results, therefore, demonstrated the sensor’s superior electrocatalytic activity and its high selectivity for dopamine and uric acid even when some foreign species were present. The average recoveries from the real sample analyses of the urine samples showed that the proposed sensor could be put to use in the real sample analysis. The developed electrode was generally found to be highly selective and sensitive toward uric acid and dopamine. It has achieved better sensing performances with a very low detection limit, wider linear ranges, and short analysis times as compared to most previously reported modified electrodes for the same analytes. Furthermore, the developed electrode was validated successfully for real sample analysis in biological fluids. The proposed methods have many attractive features, such as low cost, simplistic electrode preparation procedure, easy renewability, long-term usability, and rapid analysis. The developed electrode also displayed good repeatability and selectivity towards interfering substances. It is a promising modified electrode for the electrochemical detection of other electroactive important compounds in biological systems.
Development of solar radiation database and its integration into solar process applications in Lesotho
(National University of Lesotho, 2020-05) Bulane, Lebohang; Hove, Tawanda
Solar energy is a viable alternative source of energy for socio-development of a developing country like Lesotho. Investment in solar process applications, requires a accurate solar radiation data for the successful implementation of solar process projects. However, in Lesotho measured solar radiation datasets are not sufficient both temporally and spatially as there are only seven solar radiation measuring sites, two of which are not reliably operational. This study solves the problem of the scarcity of solar radiation data in Lesotho, by developing a solar radiation database for the country. It has a primary objective of developing an accurate solar radiation database for Lesotho. This is achieved by merging ground measured solar radiation data with satellite – derived solar radiation data. The merged data is complimented by solar radiation data derived from sunshine duration data. Merging solar radiation datasets is important because ground measured data are sparsely distributed and cannot be interpolated accurately to represent solar radiation at any location. Although satellite – derived datasets are spatially continuous, they are not accurate as they are inferred from extra- terrestrial solar radiation modified with atmospheric models. As a result, each of the databases cannot be relied up unilaterally. Measured ground data is from five stations and sunshine duration derived solar radiation is form twelve stations. The improved database is validated using a leave one out cross validation technique. Its reliability in estimating ground solar radiation is tested by relative bias error (rBE), relative mean bias error (rMBE) and normalized root mean square error (NRMSE). Results show that the database is credible as it has a maximum error of 2.7 % which is comparable to other studies of similar nature in Africa. An interpolation tool, increases the accuracy and reliability of interpolated solar radiation as compared to manual reading of data from solar radiation maps. It has an accuracy of 99.54%. The improved database and interpolation tool can confidently be used in any solar application process design and sizing in the country.
Development of time-of-use-tariffs
(National University of Lesotho, 2020-07) Mohasoa, Lebohang Edwin; Mpholo, Moeketsi, Dan, Retselisitsoe Eager, Thamae
The electricity consumption profile varies during any 24-hour period, but the electricity pricing policy for Lesotho Electricity Company (LEC) does not reflect this fluctuation as it employs flat-rate tariffs across all customer categories. This fails to adequately capture the costs exerted on the electricity network by each customer at a certain period. To address this problem, time-of-use (ToU) tariffs are determined in this study, while ensuring revenue neutrality for the utility before any load shifting. Implementation of a comprehensive ToU based pricing model could be an effective mechanism to reflect the costs imposed on the network by customers and therefore encourage customers to engage in load adjustment. The Gaussian mixture model has been utilized to determine ToU time-periods and prices. The time-periods are divided into different periods; off-peak, standard, and peak periods. Different customer categories have different durations of time- periods. This is attributed to the observed load profiles of different customer categories. Furthermore, different customer categories have different prices per period resulting in different price ratios. Possible load-shifting scenarios of 5% and 10% have resulted in a reduction in customer energy bills of 2.6% and 5.2%, respectively. While, the LEC bulk energy savings translated to 13 GWh and 30 GWh for the two load-shifting scenarios, respectively. Key words:
Disrupting tumor vasculature with oncolytic viruses
(National University of Lesotho, 2022-03) Motlomelo, Phallang Albert
Cancer is a disease caused by accumulation of phenotype-altering genetic mutations in somatic cells, which results in abnormal growth of a ected cells. Among many cancer therapies that are currently under clinical investigation, virotherapy, which uses viruses called oncolytic viruses (OVs) that specif- ically replicate in cancerous cells while sparing normal cells, has recently become one of the promising therapeutic approaches that aim to destroy cancer cells. The aim of this study is to understand the dynamics of disrupting tumor vasculature and tumor endothelium with OVs. The model is developed based on the modeling techniques that lead to a system of ordinary di erential equations (ODEs). Qualitative analysis, non-dimensionalization and stability of ODEs are performed. We also derive the steady states of the model and investigate their stability. Interestingly, our results show that there are two stable points and one non-stable point from which we found that the treatment is successful if the viral clearance rate is larger than the lysis rate. The simulations further show that oncolytic virotherapy is successful when both burst size and lysis rate are large, and fails whenever both are small.

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