Scielo RSS <![CDATA[Journal of Energy in Southern Africa]]> http://www.scielo.org.za/rss.php?pid=1021-447X20130002&lang=es vol. 24 num. 2 lang. es <![CDATA[SciELO Logo]]> http://www.scielo.org.za/img/en/fbpelogp.gif http://www.scielo.org.za <![CDATA[<b>The Manica Charcoal Stove Project</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2013000200001&lng=es&nrm=iso&tlng=es A study was conducted by staff and students from the Department of Industrial Design in the Faculty of Art, Design and Architecture (FADA) at the University of Johannesburg on alternative charcoal stove design under the title Manica Charcoal Stove Project for developing communities. The project was started in support of the principle designs developed for the Maputo Ceramic Charcoal Stove, now known as the Poupa Carvão (POCA) charcoal stove, developed by Crispin Pemberton-Piggott of the Program for Biomass Energy Conservation (ProBEC) which is supported by GIZ. A research group consisting of two academic staff members and four 3rd year Industrial Design students visited the town of Manica in Mozambique in 2008 to complete user field testing and use these results to inform alternative charcoal stove designs. The project falls under the broad area of design for social development and expands on aspects of community centred design developed within the Department of Industrial Design at the University of Johannesburg. This paper briefly describes the research method and the design process used to develop the stove concepts. It discusses aspects related to the design of new charcoal burning stoves and touches on the manufacturing systems available for stove production in the region. It evaluates the principles of user centred design in developing community projects and gives direction to further studies of this kind. <![CDATA[<b>Policy options for the sustainable development of Zambia's electricity sector</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2013000200002&lng=es&nrm=iso&tlng=es This paper aims at understanding how Zambia's electricity system would be affected by droughts (due to a dry year) and how the system's adaptive capacity could be improved. Hydropower currently supplies 99% of the total electricity in Zambia, and concerns have been raised because many climate change studies project increased occurrences of dry years in the Southern Africa region. Different economic and climatic scenarios were explored to understand their impact on the development of Zambia's power generation system, and what policies and strategies could be adopted to mitigate these impacts on security of supply and average generation costs, which directly affect the electricity price. The results show that a dry year has significant impact on the average generating cost since hydropower continues to dominate the system. Diversifying the system does not improve the adaptive capacity of the system but only increases the average cost of generating electricity in an average year. The most cost effective way of increasing the system's adaptive capacity is by importing electricity and gradually increasing share of renewable and coal technologies in the system. Further research on how electricity trade in Southern Africa could be enhanced, should be done. <![CDATA[<b>Reassessment of the environmental impacts of sulphur oxide emissions from power stations</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2013000200003&lng=es&nrm=iso&tlng=es It is a deeply entrenched belief that emissions of sulphur dioxide into the atmosphere are harmful to the environment, and that sulphur compounds should be removed from the gaseous wastes before discharge. The difficulties with this view are summarised. Extensive work in both North America and Europe has failed to demonstrate any of the early claims for impacts such as forest death. The claims for health effects seem unduly conservative and not supported by reliable data. There are even negative impacts from reducing sulphur emissions. Claims for high external costs associated with coal-fired power generation in South Africa are the result of arithmetic errors. The installation of flue-gas desulphurisation on the latest Eskom power station, Kusile, is shown to be completely unsustainable in the light of the minimal benefits that the considerable costs will bring. <![CDATA[<b>Simulation of a syngas from a coal production plant coupled to a high temperature nuclear reactor</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2013000200004&lng=es&nrm=iso&tlng=es In light of the rapid depletion of the world's oil reserves, concerns about energy security prompted the exploration of alternative sources of liquid fuels for transportation. One such alternative is the production of synthetic fuel using an indirect coal liquefaction process or coal-to-liquids (CTL) process. In this process, coal is gasified in a gasifier in the presence of steam and oxygen to produce a synthesis gas or syngas consisting mainly of hydrogen and carbon monoxide. The syngas is then converted to liquid fuels and a variety of useful chemicals in a Fischer Tropsch-type synthesis reactor. However, the traditional process for syngas production also produces substantial amounts of carbon dioxide. In fact, only about one third of the carbon in the coal feedstock ends up in the liquid fuel product using traditional CTL technology. If more hydrogen was available than the hydrogen produced during the gasification step, the carbon utilisation of the process could be improved significantly. The high temperature reactor (HTR) is a gas cooled Generation IV nuclear reactor ideally suited to provide power and high temperature heat for carbon neutral production of hydrogen via high temperature electrolysis. The integration of an HTR into a CTL process therefore provides an opportunity to improve the thermal and carbon efficiency of the CTL process significantly. This paper presents a possible process flow scheme for a nuclear assisted CTL process. The system is evaluated in terms of its thermal or syngas production efficiency (defined as the ratio of the heating value of the produced syngas to the sum of the heating value of the coal plus the HTR heat input) as well as its carbon utilisation. If the hydrogen production plant is sized to produce only enough associated oxygen to supply the needs of the gasification plant, syngas is produced at about 63% thermal efficiency, while 71.5% of the carbon is utilised in this process. It was found that the optimum HTR outlet temperature to produce hydrogen with a high temperature steam electrolysis process is 850°C. If enough process heat and power are available and process equipment capacities are sufficient, the carbon utilisation of the process could be improved even further to values in excess of 90%. <![CDATA[<b>Evaluation of the regression parameters of the Angstrom-Page model for predicting global solar radiation</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2013000200005&lng=es&nrm=iso&tlng=es A simple and empirical model for the estimation of average monthly global solar radiation for a Nigerian location is presented. Regression coefficients satisfying the Angstrom-page model have been obtained using clearness index (KT) and the relative sunshine data for the location. The test of validity of the model was done by evaluating the following statistical parameters: the mean bias error (MBE), root mean square error (RMSE), mean percentage error (MPE) and the correlation coefficient (CC). The results obtained from the statistical tests show that the new model is reliable for high precision estimation of global solar radiation. A comparison between the new model and other models is presented. <![CDATA[<b>Photovoltaic electricity production in a residential house on Réunion</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2013000200006&lng=es&nrm=iso&tlng=es In this paper, the electrical energy generation of photovoltaic (PV) arrays is discussed for three cities on the island of Réunion (the Republic of France) located in the Indian Ocean. Each PV array has a different orientation as it is placed at different parts of the roof of a residential house that supposedly is a sustainable building. The electrical energy generation is obtained by using EnergyPlus software and measured solar radiation data. The highest generation of electric energy is found for the PV array located at the north roof surface. The generation of electric energy at the east-facing PV array is larger than that at the west-facing PV array. The electrical energy generation for the city of Le Port on the coast is higher than that for the cities of Cilao, and Plaine des Cafres that are located in the mountains of Réunion. <![CDATA[<b>Decoupling analysis of electricity consumption from economic growth in China</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2013000200007&lng=es&nrm=iso&tlng=es The purpose of this paper is to apply the decoupling index combined with the LMDI method to analyze the contribution of the factors which influence electricity consumption in China over the period 19912009. The main results are as follows: (1) Electricity consumption has been rising year by year with economic growth. Electricity consumption came to 427.37 Mtce in 2009, which accounted for 19.56% of total energy consumption. (2) China's electricity intensity has continuously decreased during the 1990s and early 2000s, the decreasing trend has reserved since 2003. (3) The economic activity effect is the most important contributor to increase electricity consumption in China, the sector electricity share effect is another important factor leading to the rapid growth of electricity and the energy intensity effect plays the dominant role in decreasing electricity consumption. (4) The period from 1999 to 2007 represents a re-coupling effect, while the other time interval shows weak decoupling effect. <![CDATA[<b>Human and physical energy cycles in a subsistence village in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2013000200008&lng=es&nrm=iso&tlng=es A rural, self-contained village in Africa relies mainly on draft animals, energy provided by humans and energy from natural resources, especially firewood, for survival. The human metabolic energy cycle in a rural self-sufficient village in Venda in the Limpopo Province of South Africa is investigated, concentrating on selected activities that make up the routine livelihoods in the wet season. The selected village depended on only a slight extent on external 'modern' energy inputs such as electricity, paraffin and diesel in relation to overall energy consumption. Forty-three interviews were conducted in order to identify patterns of labour, sources of food, and foods consumed, while electronic pedometers were employed to quantify energy expended for weeding, firewood and water collection carried out in the wet season in February. A conceptual energy model showing flows of energy from one activity to another within the village was developed. An energy balance model, for an average adult male and female village resident, was developed quantitatively from the conceptual model, taking into account energy intake and energy expenditure. Energy expenditure for males was 1 991 kcal/d; females were 1 965 kcal/d, energy intake for males was 1 953 kcal/d and females was 2 007 kcal/d .This study is significant for future development of rural dwellers. It provides a baseline case for future developments in which modern energy carriers are introduced into remote areas. These may include conventional energy such as electricity, or renewable energies such as low energy devices powered off solar photovoltaic panels or off grid solar/wind systems. <![CDATA[<b>Implementing building integrated photovoltaics in the housing sector in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2013000200009&lng=es&nrm=iso&tlng=es The installation of Building Integrated Photovoltaics (BIPV) has been increasing rapidly throughout the world, yet little, if at all, has been reported in South Africa. The country has abundant solar energy resource estimated to be between 4.5 and 6.5 kWh/m2/day, yet solar energy contributes less than 1% to the country's energy mix. More than 90% of the country's primary energy comes from fossil fuels leading to an unsustainable per capita carbon footprint of about 9 tCO2e. Previous research has shown that photovoltaics can significantly augment the constrained fossil fuel generated electricity supply. This paper discusses the practical application of photovoltaics as a building element in energy efficient residential housing. The study also aims to determine the feasibility of implementing BIPV systems in the residential sector in South Africa. An energy efficient solar house was designed using simulation software and constructed. Ordinary solar panels were integrated onto the north facing roof of the house. A data acquisition system that monitors meteorological conditions and BIPV output was installed. It was observed that elevated back of module temperatures reaching up to 75°C on sunny days decreased module efficiency by up to 20% in the afternoon. The temperature profiles reveal that BIPV products can significantly influence indoor heating and cooling loads. The research seeks to raise awareness among housing stakeholders and solar industry policy makers of the feasibility of BIPV in South Africa. <![CDATA[<b>SASEC - the Southern African Solar Energy Conference</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2013000200010&lng=es&nrm=iso&tlng=es The installation of Building Integrated Photovoltaics (BIPV) has been increasing rapidly throughout the world, yet little, if at all, has been reported in South Africa. The country has abundant solar energy resource estimated to be between 4.5 and 6.5 kWh/m2/day, yet solar energy contributes less than 1% to the country's energy mix. More than 90% of the country's primary energy comes from fossil fuels leading to an unsustainable per capita carbon footprint of about 9 tCO2e. Previous research has shown that photovoltaics can significantly augment the constrained fossil fuel generated electricity supply. This paper discusses the practical application of photovoltaics as a building element in energy efficient residential housing. The study also aims to determine the feasibility of implementing BIPV systems in the residential sector in South Africa. An energy efficient solar house was designed using simulation software and constructed. Ordinary solar panels were integrated onto the north facing roof of the house. A data acquisition system that monitors meteorological conditions and BIPV output was installed. It was observed that elevated back of module temperatures reaching up to 75°C on sunny days decreased module efficiency by up to 20% in the afternoon. The temperature profiles reveal that BIPV products can significantly influence indoor heating and cooling loads. The research seeks to raise awareness among housing stakeholders and solar industry policy makers of the feasibility of BIPV in South Africa. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2013000200011&lng=es&nrm=iso&tlng=es