Scielo RSS <![CDATA[Journal of Energy in Southern Africa]]> vol. 27 num. 3 lang. pt <![CDATA[SciELO Logo]]> <![CDATA[<b>Promoting energy efficiency in a South African university</b>]]> Electricity supply issues have resulted in widespread blackouts and increased utility costs in South Africa. This is placing financial pressure on universities as they have limited means of increasing their income to cover the additional energy costs and, at the same time, are energy-intensive due to peculiar usage patterns and sprawling campuses with many (and often large) buildings. Thus, they must become energy-efficient. This is a case study of one such attempt. Four main findings emerged. Firstly, energy demand side management (DSM) had to be implemented in distinct phases due to unforeseen implementation hurdles. Secondly, there are both barriers and enablers to becoming an energy-efficient campus; that is, DSM requires managerial buy-in, capacitated operational personnel and money. Thirdly, personnel can either support or hinder DSM implementation. So, while hiring dedicated, skilled personnel to harness organisational commitment to DSM is essential, all personnel need training in energy-efficient behaviour and should be held accountable for DSM initiatives within their sphere of influence. An energy champion - at the highest level of the organisation - to influence policy and drive the behavioural and structural changes required, is strongly recommended. Lastly, DSM technologies may be readily available but are not necessarily bought, installed or used correctly due to behavioural and institutional cultural constraints. Highlights • The challenges facing universities when adopting energy-efficiency are identified. • There are also enablers to achieving energy-efficiency targets. <![CDATA[<b>Scoping exercise to determine load profile archetype reference shapes for solar co-generation models in isolated off-grid rural African villages</b>]]> For many off-grid rural communities, renewable energy resources may be the only viable option for household and village energy supply and electrification. This is especially true for many rural regions in southern Africa, where the population spread is characterised by small villages. These rural villages rely heavily on firewood, charcoal, biochar, biogas and biomass to meet thermal energy needs (hot water and cooking), while candles, kerosene and paraffin are mostly used for lighting. Alternative energy systems such as hybrid concentrated solar micro-CHP (combined heat and power) technology systems have been proposed as viable energy solutions. This paper reports on a scoping exercise to determine realistic hourly reference profile shapes for thermal and power energy consumption in isolated rural African villages. The results offer realistic energy consumption load profiles for a typical rural African village in time-series format. These reference load profiles enable experimental comparison between computermodelled solar micro-CHP systems and control automation solutions in isolated rural village micro-grid simulations. <![CDATA[<b>Varying percentages of full uniform shading of a PV module in a controlled environment yields linear power reduction</b>]]> Partial shading of a PV module has received much attention over the past few years, as it results in uneven cell power generation, compromising a PV system performance. Full uniform shading of a PV module has not received as much attention. This article correlates the percentage of full uniform shading of a given PV module within a controlled environment to its output power. The percentage of full uniform shading provided by shade nets was firstly determined. These shade nets are then used to cover a specific PV module (experimental system), while an identical PV module remains totally unshaded (control system). Increasing percentages of full uniform shading negatively affected the direct beam component in a linear way. Decreasing the light intensity falling on the PV model exhibited a linear increase in the percentage of output power reduction of the PV module. This is observed in that a shade net providing 36% of full uniform shading resulted in a 56% output power reduction, while a 63% full uniform shading net yielded 82% power reduction. These results hold a strong promise to improve current simulation modules that focus on determining the output power of a given PV array under specific environmental conditions or for specialised geographical locations. Highlights 1. Six different shade nets were quantified using the shading experiment. 2. A 36% shade net resulted in a 56% output power reduction. 3. A 63% shade net yielded 82% power reduction. <![CDATA[<b>Determination of oxidation characteristics and decomposition kinetics of some Nigerian biomass</b>]]> The oxidation characteristics and devolatilisation kinetics studies of palm kernel shell (Elaeis guineen-sis), African bush mango wood and shell (Irvingia wombolu), and African border tree wood (Newbouldia laevis), were carried out by the ther-mogravimetric method. A thermogravimetric analyser TA Q500 instrument was used at a heating rate of 30 °C.min-1 under oxidative conditions. It was observed that all the samples followed a two-stage structural decomposition between 200 °C and 500 °C. The greatest mass loss rate occurred within the oxidation stage (200-375 °C) in all the samples. The ignition temperature of the samples ranged from 275-293 °C while their burnout temperatures ranged from 475-500 °C. During the oxidation stage, African bush mango shell was the most reactive sample, while palm kernel shell was the least. During the char combustion stage (375-500 °C), the reactivity of palm kernel shell was the highest. The average activation energy of the samples for the entire decomposition period are 140, 270, 131 and 231 kJ.mol-1 respectively. The biomass samples considered are thus suitable for combustion purposes for bioenergy production with minimal external energy input. <![CDATA[<b>Ranking South African provinces on the basis of MERRA 2D surface incident shortwave flux</b>]]> The main objective of the present study is to rank South African provinces on the basis of incoming solar radiation. The surface incident shortwave flux (SW Flux, Wm-2) of NASA Modern-Era Retrospective Analysis for Research and Applications (MERRA 2D) reanalysis data for the period 1980-2009 over South Africa was analysed on annual, seasonal and monthly scales. The monthly mean ± standard deviation values of SW Flux for the period revealed that, Northern Cape received the most (267.38 ± 4.32 Wm-2) incoming solar radiation throughout the year, followed by North West (263.37 ± 7.13 Wm-2) and Free State (259.20 ± 7.66 Wm-2). The northern region of Limpopo also showed a good amount of incoming solar radiation (257.95 ± 6.16 Wm-2) at the surface. KwaZulu-Natal received least (232.99 ± 7.02 Wm-2) amount of mean monthly solar radiation in comparison with other provinces. On an annual scale, the Northern Cape ranked first, and on seasonal and monthly scales North West ranked first. Limpopo and Free State also performed well in the present study.