Scielo RSS <![CDATA[Journal of Energy in Southern Africa]]> http://www.scielo.org.za/rss.php?pid=1021-447X20150003&lang=es vol. 26 num. 3 lang. es <![CDATA[SciELO Logo]]> http://www.scielo.org.za/img/en/fbpelogp.gif http://www.scielo.org.za <![CDATA[<b>Reliability benefit of smart grid technologies: A case for South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2015000300001&lng=es&nrm=iso&tlng=es The South African power industry faces many challenges, from poor performing networks, a shortage of generation capacity to significant infrastructure backlog and an ageing work force. According to the Development Bank of South Africa (DBSA), the key challenge facing the industry is ageing infrastructure. Smart grid technologies are a class of technologies that are being developed and used by utilities to deliver electrical systems into the 21st century using computer-based remote control and automation. The main motive towards smart grid technologies is to improve reliability, flexibility, accessibility and profitability; as well as to support trends towards a more sustainable energy supply. This study identifies a number of smart grid technologies and examines the impact they may have on the distribution reliability of a test system. The components on the selected test system are the same as those found on a South African feeder. The bulk of the load in test system was modelled using load data collected in South Africa. This study will consider a number of different cases, with the base case incorporating the impact of aged infrastructure on the reliability of the system. The smart grid technologies were then introduced into the system and their impact on distribution reliability was determined. These different cases were also compared to the alternative of replacing the aged and worn out infrastructure with new infrastructure. The findings of this study indicate that the identified smart grid technologies improve the reliability of the system, mainly by decreasing the outage duration experienced by customers on the network. An even better performance was achieved when the ageing infrastructure was replaced with new infrastructure. <![CDATA[<b>Low-income resident's preferences for the location of wind turbine farms in the Eastern Cape Province, South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2015000300002&lng=es&nrm=iso&tlng=es There is a general consensus that South Africa should be generating more power through harnessing renewable energy resources, such as wind power. However, there is no consensus with regard to the location of such generating projects. This paper describes a wind farm project proposed for development in the Kouga Local Municipality, reports low-income local residents' preferences on its nature and applies choice modelling to analyse these preferences. A questionnaire was presented to each respondent, the discrete choice experiment component of the questionnaire included two different onshore wind energy development scenarios and a status quo option. The scenarios differed by the combination of four elements: the distance of the wind turbines from residential areas, job creation, the number of turbines and a subsidy allocated to each household. <![CDATA[<b>Identification and characterisation of performance limiting defects and cell mismatch in photovoltaic modules</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2015000300003&lng=es&nrm=iso&tlng=es The performance and longevity of photovoltaic (PV) modules can be severely limited by cell mismatch occurring when a solar cell in a series-connected string produces a lower current than the other cells in that string. The current output of the entire string is limited by the weakest cell in the string so shading or damage to a single cell in a module can affect the entire module's current output. Electroluminescence (EL) occurs when a positive current and voltage are applied to a solar cell and is used to identify damage and defects in the cell. In this study, the cell mismatch in three single crystalline silicon modules was investigated using EL and current-voltage (I-V) characterisation techniques. Two modules have a white discolouration that affects the majority of the cells in the module and also have signs of mechanical damage, while the third module acts as a reference as it has no discolouration and appears undamaged. The EL signal intensity is related to cell performance and identifies material defects, bad contacts and broken cells. Cell mismatch in a module results in a decrease in the performance parameters obtained from the I-V characteristic curve of the module. The I-V curves indicate the presence of current mismatch in the degraded modules, which is supported by the EL images of these modules. The use of EL images, in conjunction with the I-V curves, allows the degradation in the modules to be characterised. <![CDATA[<b>A perspective on South African coal fired power station emissions</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2015000300004&lng=es&nrm=iso&tlng=es This paper investigates trends of historical and projected future South African coal-fired power station criteria (total primary Particulate Matter (PM), Sulphur Dioxide (SO2) and Nitrogen Oxides (NOx)) and Carbon Dioxide (CO2) emissions. It was found that an energy restricted environment has an increasing effect on emissions, as emissions per energy unit increased from the onset of the South African energy crisis. PM emissions particularly, increased during the energy crisis period, due to increased pressure on PM abatement and lowered maintenance opportunity. Projections of future coal-fired power station criteria and CO2 emissions are made for four different future scenarios for the period 2015 to 2030. Three of the four scenarios are based on the lower projected energy demand baseline case as published in the updated Integrated Development Plan (IRP). The difference between these three scenarios is different retrofit rates of power stations with emissions abatement technologies. The fourth scenario is a worst case scenario and assumes high energy demand (and therefore no decommissioning of power stations), high emission rates (similar to worst past emission rates during the period 1999-2012) and no further abatement of emissions above and beyond current mitigation efforts. This scenario gives an indication of what South African coal-fired power station emissions could look like if the energy crisis persists. There is a marked difference between projected best and worst case PM emissions during the entire projected period, but especially during 2030 when worst case PM emissions compared to a 2015 baseline value are expected to rise by 40% and best case PM emissions are projected to decline by 40%. Worst case NOx emissions are expected to increase by 40% in 2030 from a 2015 baseline value whereas best case emissions are expected to decline 10% from the same level in 2030. Worst case SO2 emissions are predicted to increase by around 38% in 2030 and best case emissions are expected to decrease by around 20% in 2030 from a 2015 baseline value. Relative emissions used in the projection of future CO2 emissions in this paper differ from that used in the energy demand and energy mix modelling done for the updated IRP baseline case. The reason for this is that the modelling for the updated IRP assumed relative CO2 emission factors for supercritical boilers, whereas only Kusile and Medupi fall in this category and relative emissions from all other stations are, in fact, between 5% and 16% higher. For this reason, it seems unlikely that the South African climate commitment target for 2030 will be made. <![CDATA[<b>Modelling energy supply options for electricity generations in Tanzania</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2015000300005&lng=es&nrm=iso&tlng=es The current study applies an energy-system model to explore energy supply options in meeting Tanzania's electricity demands projection from 2010 to 2040. Three economic scenarios namely; business as usual (BAU), low economic consumption scenario (LEC) and high economic growth scenario (HEC) were developed for modelling purposes. Moreover, the study develops a dry weather scenario to explore how the country's electricity system would behave under dry weather conditions. The model results suggests: If projected final electricity demand increases as anticipated in BAU, LEC and HEC scenarios, the total installed capacity will expand at 9.05%, 8.46% and 9.8% respectively from the base value of 804.2MW. Correspondingly, the model results depict dominance of hydro, coal, natural gas and geothermal as least-cost energy supply options for electricity generation in all scenarios. The alternative dry weather scenario formulated to study electricity system behaviour under uncertain weather conditions suggested a shift of energy supply option to coal and natural gas (NG) dominance replacing hydro energy. The least cost optimization results further depict an insignificant contribution of renewable energy technologies in terms of solar thermal, wind and solar PV into the total generation shares. With that regard, the renewable energy penetration policy option (REPP), as an alternative scenario suggests the importance of policy options that favour renewable energy technologies inclusion in electricity generation. Sensitivity analysis on the discount rate to approximate the influence of discount rate on the future pattern of electricity generation capacity demonstrated that lower values favour wind and coal fired power plants, while higher values favour the NG technologies. Finally, the modelling results conclude the self-sufficiency of the country in generating future electricity using its own energy resources. <![CDATA[<b>Options for the supply of electricity to rural homes in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2015000300006&lng=es&nrm=iso&tlng=es The residential sector in South Africa is being electrified by the South African government on a priority basis. For this purpose, both grid and off-grid electrification options are being used. As off-grid option, 50 Watt Solar Home Systems (SHS) is being provided to consumers in remote rural areas where grid connection is inaccessible. But the SHS of the mentioned size can hardly produce 0.3 to 0.4 kilowatt-hour (kWh) of electricity per day, even under the best solar conditions. This electric energy is substantially lesser than the Basic Electric Energy (BEE = 50 kWh per month), being utilized in the country free of cost by grid connected low income households. In this research work, efforts have been made to determine the most economical options in South Africa's rural areas with off-grid capacity equivalent to BEE. For analysis, off-grid/micro grid options have been compared not only with one another but also with grid connection. To incorporate renewable resources spatial variations, the work has been carried out at provincial level with the period 2014 to 2050. From analysis, it has been found that currently grid-connection is marginally better than off-grid options. But due to increasing grid connection cost and development in the off-grid technologies, the later with generation equivalent to BEE will be a more attractive option to electrify South African rural areas. <![CDATA[<b>Determinants of energy poverty in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2015000300007&lng=es&nrm=iso&tlng=es This paper provides empirical evidence on the determinants of energy poverty in South African households using the National Income Dynamics Survey (NIDS, 2012), while controlling for individual, household and demographic characteristics. This is formulated within a logistic regression framework, while defining energy poverty using the expenditure approach consistent with the definition by the Department of Energy (DoE) of South Africa. The model reveals that household expenditure patterns, race, education level, household and dwelling size, location of the household and access to electricity are important factors in explaining the state of energy in South African households. This paper also discusses limitations in defining energy poverty using the expenditure approach. Finally, some recommendations are made for regulators and policy makers. <![CDATA[<b>An overview of refrigeration and its impact on the development in the Democratic Republic of Congo</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2015000300008&lng=es&nrm=iso&tlng=es The development of refrigeration is a priority in all countries, given the multidimensional roles that it plays in the sustainable development of society. In developing countries, efforts are being made to catch up with the delayed experienced in the use of refrigeration. To achieve this goal, several countries are allowed to trace the history of refrigeration in their countries in order to understand the main causes of non-expansion, and then set up a new strategy of sustainable development for this technology. The Democratic Republic of Congo (DRC) is a developing country that has experienced a very interesting history of refrigeration, but is still less known by the Congolese themselves as well as by scientists. This paper has traced out the outline in the history of refrigeration in the DRC. Surveys were conducted in the industrial, health, residential, commercial, and tourism sectors during the colonial and post-colonial period. Results showed that the use of refrigeration in the DRC has been remarkably observed in the industrial sector, especially in breweries, with a cooling capacity ranging from 50.1 thousand to 2.88 million kWh, about 5 659 % between 1929 and 1957; from 3 million to 26.5 million kWh, about 783.3 % between 1958 and 1980, and then dropped to 6.5 million kWh in 2004 before resuming its growth up to 11 million kWh in 2009. The variations in the use of refrigeration during the above periods significantly influenced the economy, in the sense that the economic and social indicators of the country grew from 0.415 to 0.430 between 1975 and 1985, and then declined to 0.375 in 2000, due to political instability, before rising up to 0.410 in 2005. <![CDATA[<b>Comparative bioelectricity generation from waste citrus fruit using a galvanic cell, fuel cell and microbial fuel cell</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2015000300009&lng=es&nrm=iso&tlng=es This article demonstrates the new approaches for the generation of bioelectricity from waste citrus fruit using direct a galvanic cell (DGC), an indirect galvanic cell (IDGC), a conventional fuel cell (CFC) and a microbial fuel cell (MFC). The citrus fruit was used as whole for the preparation of DGC and their juices for the preparation of IDGC, CFC and MFC. The performance and bioelectrical parameters obtained were compared. The voltage found to be increased by increasing the number of cells in a series while, the current remains constant. Whereas the voltage remains constant and the current found to be increased with increasing the number of cells in parallel sequence. The power output of three units of citrus fruit connected together in a series found to be sufficient to turn on the LED light bulb in all cases. The result showed that lemons have the maximum power output by the DGC and MFC method, whereas grapefruit showed the maximum power output by IDGC, and thus considered as the best citrus fruit. Addition of NaCl solution in DGC and IDGC slightly increased the values of power output. The power output of citrus fruit was also determined by CFC and MFC before and after the inoculation of Escherichia coli. The detailed microscopic analysis of all the samples was carried out. It is found that all MFCs have higher power output as compared to their counterpart CFCs. However, maximum power output was displayed by DGCs. Moreover, a lemon fuel cell has the higher power output as compared to the fuel cells of other citrus fruit. This approach can be used to overcome the disadvantages of many non-renewable and conventional sources of energy including burning of fossil fuels to mitigate the major source of global warming and pollution by using such biodegradable and renewable sources. <![CDATA[<b>The effect of an angle on the impact and flow quantity on output power of an impulse water wheel model</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2015000300010&lng=es&nrm=iso&tlng=es Nowadays, the world is more focused on hydraulic energy, which scientists have initiated thorough analyses of hydropower resources. The potential of wind power generation is immense. It is an historical source of energy but wind power is not applicable in this case. In India, water can be used for both - as a source of electricity and for irrigation and agricultural use. Impulse type water wheels were employed until flow is accessible. According to available literature, there are three types of water wheels and the application of a particular type of water wheel depends upon the stream of water. In this article, an extremely uncomplicated category impulse water wheel is fabricated. To fabricate this water wheel, little engineering is required. The experimental results obtained indicate that intensity of generated power depends upon the angle of water impact on the turbine blade, height, quantity of water flowing in pipe etc. The aim of this article is to suggest an alternative source of economical and environmentally friendly green energy for a small quantity of fluid flowing. There are various sources of small quantity water such as large society storage tank water, sewer line water, canals water and many more. The construction cost of water wheels is not as much since it does not have an intricate blade profile. <![CDATA[<b>Harnessing Nigeria's abundant solar energy potential using the DESERTEC model</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2015000300011&lng=es&nrm=iso&tlng=es The DESERTEC project, a European Union (EU) initiative to harness solar energy by means of Concentrated Solar Power (CSP) from Africa for use in Europe, shows the enormous potential that exists in alternative energy sources for the sub-region once there is political will. The Trans-Mediterranean Renewable Energy Corporation (TREC), a network of scientists and politicians who have taken it upon themselves to solve Europe's energy problem using sun from Africa, conducted three studies which evaluated the potential of renewable energy resources in the Middle East and North Africa (MENA), the expected needs for water and power in EU-MENA between now and 2050 and issues relating to the construction of an electricity transmission grid connecting the EU and MENA (EU-MENA-Connection), with a formula to turn the North African desert sun into electricity and transport same to Europe. This paper harnesses the TREC fact-finding studies in order to estimate how much the same ideas can be applied in many other parts of the world, Nigeria in particular. Investigation reveals that this association exists with huge potentials for an energy-starved country like Nigeria in harnessing her abundant hot sun in the north, which could go a long way in meeting the energy needs in that part of the country and beyond. Other benefits include unlimited supplies of clean electricity, agricultural gains, and creation of new industries, new jobs and new sources of income. <![CDATA[<b>Efficiency analysis of an induction motor with direct torque and flux control at a hot rolling mill</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2015000300012&lng=es&nrm=iso&tlng=es This paper presents an efficiency analysis of an induction motor with direct torque and flux control at a hot rolling mill in South Africa. Two scenarios were evaluated: 1) where the induction motor was controlled at a constant speed with a variable thickness slab; and 2) where the speed of the induction motor was controlled according to the thickness of the slab. Both scenarios used the speed as reference to control the torque and flux of the induction motor. A comparison on the energy consumption of the induction motor for both scenarios was done by means of a detailed simulation model. The simulation model for this specific case study is explained in detail. The results obtained showed an increase in the efficiency of the induction motor from the original system (scenario 1) to the improved system (scenario 2). Part of this paper provides an overview on hot rolling mills. <![CDATA[<b>Contemporary wind generators</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2015000300013&lng=es&nrm=iso&tlng=es It is believed that wind energy is growing at a very rapid rate, especially in the last few years. When compared with other sources of renewable energy in the energy portfolio, it becomes evident that the bulk is wind energy-based. However, there are some backlogs to full manifestation of this technology ranging from initial high cost to performance and reliability issues, among others. But in spite of these bottlenecks, new research trends have been assertive in seeking out a sustainable solution for harnessing wind energy for power generation -especially in the design and construction of wind generators. In order to motivate and prime a sustainable energy mix among stakeholders, this paper is a shot at appraising the theory of these innovative wind generators towards ecological sustainability, economy, efficiency, and employment creation. <![CDATA[<b>Impact of renewable energy deployment on climate change in Nigeria</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2015000300014&lng=es&nrm=iso&tlng=es It is well known fact that the rate of industrial growth of any country is a function of the amount of energy available in that country and the extent to which this energy is utilized. The burning of fossil fuels to generate energy is a dirty process. Greenhouse gas (GHG) emissions result when fossil fuels are produced and consumed and these emissions contribute to climate change. Nigeria as a country is highly vulnerable to the impacts of climate change because its economy is mainly dependent on income generated from the production, processing, export and/or consumption of fossil fuels and its associated energy-intensive products. Hence, it is on this premise that this paper is researched to review the energy sources being used in Nigeria and investigate its impact to climate change. Findings reveal Nigeria's over-dependence on fossil-generated energy with associated adverse environmental effects, among other things. Recommendations for the integration of renewable energy into Nigeria's energy mix, beyond other measures, have been offered, especially with reference to the salient environmental benefits that accrue to it.