JESA Volume 11 (abstracts only)
JESA Volume 11 (abstracts only)
Vol.11 No.1: February 2000
• Performance of solar water heating systems in Botswana E Bakaya-Kyahurwa and M T Oladiran
There is plenty of solar energy in tropical countries that make solar thermal applications attractive in these regions. For example, in Botswana, the government, the housing corporation and the mining companies have installed over 10 000 solar water-heating units. However, most of the first generation units did not supply adequate hot water when required. It is also common to find units abandoned or the users uninterested in the condition and the energy contributions of the solar water heaters. Consequently this paper presents the results of an on-going investigation to determine the technical performance of solar water heaters in Botswana. The study consisted of an extensive questionnaire survey administered to system owners and users in 5 different residential zones in Gaborone. Various technical problems were identified, categorised and discussed. Lack of standards and regulations to monitor and control the manufacture, installation and performance of solar heating systems seem to be a major source of problems.
• Application of the input-output method of energy analysis in estimating process energy intensities D Holm, D Irurah and A Ströh
Although the conventional input-output (I-O) method serves as a satisfactory tool for estimating cumulative energy intensities using the inverse coefficient matrix ***, it fails to show the breakdown of energy flows through the diverse paths of the sectoral flow of inputs and outputs. By using the formula *** this paper demonstrates a process of identifying, quantifying and interpreting the internal energy flows between the sectors of an economy based on the I-O method with the building construction sector as an illustrative example. The approach yields data, which can be applied in detailed sectoral energy studies and analysis, especially for policy making and sectoral energy conservation initiatives. The paper recommends that the series of iterative A matrices be compiled as part of the regular I-O analysis tables to facilitate the application substantiated in this paper.
• Energy pollution trends in South Africa during the period 1983 – 93 M I Howells
The use of energy is essential for socio economic development. Under current conditions, the extraction, transformation and use of energy carriers are associated with a range of environmental impacts. These vary according to fuel, sector and technologies employed. The effect of the environmental impact also varies in terms of dissatisfaction, appreciation, cost or benefit. This paper discusses various emissions indicators, relating emissions to energy and economic activities. As such, these indicators represent an important step in recognising important emitters in the South African context. Indicator trends for the period 1983-93 are quantified and discussed. Indicators include various emission intensities while national carbon dioxide, sulphur dioxide and PM10 particulate emissions are discussed in detail.
A needs-driven approach to the design process – a case study in combating pollution in low cost housing W M K Van Niekerk and A S Van Niekerk
Air pollution in South African townships is a serious problem. Efforts to reduce air pollution started in the 1960’s and included introducing devolatilised coal, low-smoke stoves and electrification. These efforts were technology-driven and have had limited success in reducing indoor air pollution. In this paper we report on the eMbalenhle Air Quality (MAQ) Project, a needs-driven approach to the reduction of indoor air pollution levels in informal houses in eMbalenhle, a township near Secunda. Promising results that prove the validity of the needs-driven approach to the design process were obtained. It seems that such an approach will make the implementation of the most effective, desirable and affordable solutions possible. Unlike a technology-driven approach, where attempts are made to implement specific solutions, a needs-driven approach starts from the end-user. The ways in which residents use and evaluate existing stoves, new low-smoke stoves, devolatilised coal, normal coal, proper chimneys, LP gas and thermal insulation of houses were investigated. The potential solutions in different combinations were introduced to forty households in order get the residents’ reaction, stimulate discussion and test their effectiveness to reduce indoor air pollution in the actual, real life context. The primary objective was to try and understand and explain the attitude of the community towards the changes. To do this, trained field workers regularly visited the forty households, conducted interviews and held group discussions. Special attention was paid to the interaction between the product and the end-user. As a secondary objective, pollution levels inside the houses and coal consumption before and after the changes were also measured. However, it was difficult to isolate readings inside the house from the effect of the air pollution outside or quantify the effect on indoor pollution levels of other possible influences - for instance, the speed and direction of the wind, the opening and closing of doors, changes in ambient temperature etcetera. Insulating the houses thermally was effective in reducing indoor pollution levels (between 5% and 30%). Even more significantly, users reported huge reductions in coal consumption (some respondents reported up to 50%). It is reasonable to expect that total pollution production would be reduced proportionally. The desirability of insulation is also very high. People felt it helped to keep dust out of the house and helped to “create a real home”. The devolatilised coal used in this study is expensive and ineffective in reducing indoor pollution. The desirability is negative to low because of the lower heating value, difficult ignition and poor heat retention. A proper chimney was also effective (15-25% reduction) and perhaps the best value-for-money solution as far as indoor pollution is concerned. LPG is acceptable to a certain small market segment. There is widespread fear that children could tamper with gas appliances and cause an explosion. Such resistance to LPG could perhaps be reduced by appropriate product designs.
Vol.11 No.2: May 2000
• The use of biomass for electric power generation in the South African and Zimbabwean sawmilling industry E D D Cochrane
There are opportunities in South Africa and in Zimbabwe for these countries’ respective sawmilling industries to be self-sufficient in the generation of power for their own industrial electrical energy requirements. The analysis of wood residues from sawmilling operations in both these countries confirms that there is a substantial amount of fuel available for the main heating requirement of a wet sawmill. This heating demand arises from the timber-drying kilns in the sawmill complex. One of the principal arguments put forward for the cogeneration of electrical power is that by passing steam through a condensing or backpressure turbine, the entire power demand of a sawmill can be met in addition to the heat required for the kiln. One of the major difficulties perceived for cogeneration in a sawmill is balancing the electrical load with that of the kiln steam-heating demand. This difficulty arises from the situation in which the kilns of a sawmill usually operate around the clock, whereas the sawmill itself only operates for 10-12 hours per day. The cogeneration power plant size for the sawmill itself in terms of electrical output is about two to three times the electrical power required by the kilns. There is a need to dispose of this off-peak surplus power for a sawmill to make full economic use of its significant wood waste residue. The low cost of electrical power as provided by Eskom in South Africa inhibits investment in capital equipment for self-generation in that country. The situation in Zimbabwe is significantly different because of higher power costs.
• Distributed generation in South Africa: economically sound or environmentally benign? J L Schäffler
The question that this paper seeks to answer is whether the greater use of distributed electricity generation is driven primarily by a growing awareness of the impacts of human activity on the natural environment or by traditional (excluding environmental externalities) economic considerations. The concept of distributed generation is explained and some alternative definitions explored. Amongst the factors included in the economic consideration are technological innovation, changes in public policy and the changing character of transmission and distribution systems. The hypothesis that appropriately sized and situated generation technologies are not a cost effective alternative to large centrally located generation facilities but merely a bid for proponents of emerging technologies to find an early niche for these technologies is explored. The elegance of distributed generation is the result not only of the flexibility it affords planners in meeting customer demand but also its potential to be simultaneously economically sound and environmentally benign. Environmental pressure is seldom the primary driver of the emergence of the distributed electricity generation concept in developing countries. Consideration is given to whether distributed generation could form part of the repertoire of methods used to balance the supply and demand of electricity in South Africa.
• A project review of two climate conscious buildings in Botswana B Marland
The Architecture Unit of the Botswana Technology Centre (BOTEC) has been responsible for two major building projects in Botswana. These are the new BOTEC Headquarters in Gaborone and the National Food Technology Research Centre (NFTRC) Headquarters in Kanye. Apart from being energy efficient commercial buildings, they will also serve as a practical demonstration for researchers, developers, designers, etc., of appropriate technologies for achieving thermal comfort in buildings in Botswana's hot and dry climate. This article describes the various active and passive climate responsive design features. NFTRC is a parastatal organisation specialising in developing new technologies for food processing. BOTEC, also a parastatal, provides research and development facilities in the areas of renewable energy, electronics, civil engineering and architecture. The Architecture and Civil Engineering Units work closely together on aspects such as water conservation, development of appropriate construction materials, passive and active solar and low energy building environment systems. Anderson + Anderson International were appointed to design and supervise the construction of the BOTEC Headquarters with the BOTEC Architecture Unit making an input into the design centred on the technologies to be employed and ensuring that the design achieved a sufficiently high profile. The design of the NFTRC Headquarters was developed in-house by the Architecture Unit. Work on both buildings started on site in December 1998. The NFTRC Headquarters was completed in April 2000 and the BOTEC Headquarters is currently scheduled for completion this July.
Vol.11 No. 3: August 2000
• Proposals for a standardised referential framework for an integrated energy information system for South Africa C J Cooper
Energy policy formulation is comparable to the decision making process. Research on the human decision process has differentiated three definite stages. These are data gathering and analysis, model building and choice. These stages are also applicable to the policy formulation process. In designing an information system to provide inputs to support the policy process, similar stages are followed. For the information system, the processes are data collection, data processing and finally information dissemination. A critical aspect is the classification of data from many different sources in a manner that will permit easy and consistent analysis. The key is the use of a single standardised referential framework. There are four dimensions that need to be defined for such a framework for an energy information system. These are fuel type, economic sector, spatial location and time unit. Proposals for the data sets for each of these dimensions for South Africa are presented in this paper.
• Development of heating- and cooling degree-day data for South African locations L.J Grobler and W.l.R den Heijer
The outside air temperature plays an important role in the energy consumption of an air-conditioned building. The relationship that exists between building energy consumption and outside air temperature is important to building designers, engineers and energy managers. Heating- and cooling degree-days is one means of determining the relationship between outdoor conditions and energy consumption. From experience it was found that degree-days are often difficult to obtain and seldom available for locations in South Africa. A study was initiated that would ensure the availability of degree-day data for South African cities and various other locations in South Africa. During the study, an existing and well-trusted method was used to calculate the degree-days. The heating and cooling degree-days were calculated using different types of historical and typical temperature data and is provided for a number of locations in South Africa. A brief description of the application for degree-days is provided in the last part of this article.
• Challenges facing the implementation of non-grid technology in South Africa T C Lithole, M Montwedi
The first phase of the National Electrification Programme (NEP) started in 1994 and ended in 1999. The Year 2000 NEP was driven as a stand-alone programme, as the new programme is planned to start in April 2001. The new National Electrification Programme to start in 2001 will integrate non-grid with grid electricity for households, schools, clinics and other selected community facilities. Non-grid electrification of households in South Africa was never a national programme. There is very little experience to draw from with reference to this programme. In the past, only Eskom and Municipalities were involved in electrification. The new programme plans to involve concessionaires.
• A market overview of commercial renewable energy technologies in SADC G Stassen and AC Olivier
The Development Bank of Southern Africa (DBSA), together with the International Solar Energy Society (ISES) and the European Commission (DGXVII for Energy) have recently completed a study aimed at assessing the market for commercial renewable energy technologies (RETs) in the Southern African Development Community (SADC). The research was conducted by means of country visits to 12 of the 14 SADC member countries as well as desk research and meetings assessing the European industrial interests and requirements for renewable energy development within SADC. This paper presents an overview of this SADC-wide assessment of commercial RETs. The strong market growth in the photovoltaics (PV) sector makes this the dominant renewable energy technology in the SADC region. Solar water heating (SWH) is the renewable energy technology that sees the most regional trade of locally manufactured products. The traditional application for wind energy has been in mechanical water pumping. This market is declining with the increased use of PV pumps and the extension of the electricity grid. A small market exists for wind turbine battery chargers and it is likely that a number of pilot projects may be implemented in Namibia, Mauritius and South Africa in the near future. With the opening up of the regional electricity market the opportunity to implement small hydro systems as independent power producers have also become commercially viable. Other than fuelwood the only other commercial source of biomass energy in the region is electricity and heat generation from the combustion of sugar cane residues (bagasse). The paper concludes by identifying opportunities and obstacles to the increased development of the regional commercial RETs market.
• Liberalisation and the changing role of governments in the petroleum sector: implications for South Africa Z. C. Xabendlini
The petroleum sector in countries throughout the world is going through a process of liberalisation. This results in changing roles for the state. The petroleum sector is strategically important to all economies. This justifies the involvement of governments in the sector in one way or another. In the 1970’s most developed countries experienced economic downturns. This was a time when governments in most countries were highly involved in industries. Such policies began to be reviewed. With the era of liberalisation that started in the 1980’s, the roles of government are changing. Liberalisation advocates minimum government intervention. There is however, no guarantee that liberalisation will bring about the intended results. Implications of liberalisation are very important for a country like South Africa that intends to liberalise. This paper tries to highlight some of those implications by trying to draw from experiences of countries that have attempted to liberalise the petroleum sector. This paper is mainly based on the work undertaken for completion of the author’s masters thesis in the Faculty of Engineering, University of Cape Town titled: An international review of the impacts of liberalisation on the petroleum sector: lessons for South Africa.
Vol.11 No. 4: November 2000
• Preliminary tests of a Near-Stirling cycle internal combustion engine B.M. Mangaya and C.J. Rallis
Near-Stirling (NS) cycles have been presented in previous publications. First-order (ideal cycle) and second-order (lumped parameter) models of such cycles have been developed. The latter was used to adapt a two-cylinder Petter compression-ignition engine to operate on a NS cycle. One cylinder was used as the compressor and the other as the expander. The compressor piston crown was provided with an isothermalizer and that of the expander with a dome shaped heat shield. Only the lower part of the expander cylinder was cooled. The expansion space was therefore essentially adiabatic. The crank shaft was made up of three parts so as to enable the phase angle between the compressor and expander to be varied. The two cylinders were connected at their top end by a regenerator and a rotary transfer/exhaust valve. Reed type inlet and exhaust valves were used in the compressor. The engine was tested on a torsion dynamometer test-bed. Unfortunately, because of the large out-of-balance forces of the engine and the lack of stiffness of the test-bed, all tests were carried out at low speeds (~500 rpm). A series of tests were carried out, both with the engine being motored and with it generating power. With the exception of the expansion process of the clearance gas in the compressor, the lumped parameter model was validated as an adequate design tool. A more sophisticated simulation of this process confirmed the importance of heat transfer to and from the isothermalizer. Power tests with and without a wire mesh regenerator between the compressor and expander cylinders underlined the importance of this device. Its effectiveness was estimated as being about 78%. The volumetric efficiency was very low - between 20% and 65% and calls for a redesign of the air intake system. The fuel pump system was unsatisfactory and will have to be replaced. Notwithstanding the problems encountered this appears to be potentially viable.
This paper presents an inventory of greenhouse gas (GHG) emissions from the energy sector for the year 1994. This year is the latest base year that South Africa is currently required to report for its national communication to the United Nations Framework Convention on Climate Change (UNFCCC). The work is presented according to the Intergovernmental Panel on Climate Change (IPCC) reporting framework. In order to reflect the South African situation, where possible, locally derived emissions data are used and noted. Standard methodologies of the IPCC have been followed where appropriate and deviations from default procedures are motivated. This paper does not try to compare South African emissions with those of other countries with a similar economy to itself. This study was prompted in response to South Africa’s ratification of the United Nations Framework Convention on Climate Change (UNFCCC). As part of South Africa’s obligations a ‘Country Study’ needs to be drawn up. Work that has been compiled for this country study has been researched to provide input to this paper. This report forms a sub-sector of the report of the UNFCCC emissions inventory. Other similar and previous studies include Scholes and van der Merwe and Howells. These studies were not confined to the energy sector but include a full range of GHG sources and sinks. The latter of the two was carried out according to OECD guidelines, for the base year 1990, and is similar in methodology to the present study. The results show a deviation from this 1990 inventory. This was observed to be so due the availability of better energy statistics in the year 1994. Other deviations from the 1990 inventory are a general increase in emissions in various sub-sectors. This is due to more consistent reporting of the energy data used than in the 1990 inventory, rather than a marked increase in energy consumption.