Browsing Masters Degrees (Centre for Renewable and Sustainable Energy Studies) by Title
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- ItemAerodynamic optimisation of a small-scale wind turbine blade for low windspeed conditions(Stellenbosch : Stellenbosch University, 2006-12) Cencelli, Nicolette Arnalda; Von Bakstrom, T. W.; Denton, T. S. A.; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronical EngineeringENGLISH ABSTRACT: Wind conditions in South Africa determine the need for a small-scale wind turbine to produce useable power at windspeeds below 7m/s. In this project, a range of windspeeds, within which optimal performance o the wind turbine is expected, was selected. The optimal performance was assessed in terms of the Coefficient of Power(Cp), which rates the turbines blade's ability to extract energy form the avalible wind stream. The optimisation methods employed allowed a means of tackling the multi-variable problem such that the aerodynamic characteristics of the blade were ideal throughout the wind speed range. The design problem was broken down into a two-dimensional optimisaion of the airfoils used at the radial stations, and a three-dimensional optimisation of the geometric features of the wind rotor. by means of blending various standard airfoil profiles, a new profile was created at each radial station. XFOIL was used for the two-dimensional analysis of these airfoils. Three-dimensional optimisn involved representation of the rotor as a simplified model and use of the Blade Element Momentum(BEM) method for analysis. an existimg turbine blade, on which the design specifications were modelled, was further used for comparative purposes throughout the project. The resulting blade design offers substantial improvements on the reference design. The application of optimisation methods has successfully aided the creation of a wind turbine blade with consistent peak performance over a range of design prints.
- ItemAgricultural residue as a renewable energy resource(Stellenbosch : University of Stellenbosch, 2011-03) Potgieter, Johannes George; Van Niekerk, J. L.; De Lange, L.; University of Stellenbosch. Faculty of Engineering. Centre for Renewable and Sustainable Energy StudiesENGLISH ABSTRACT: In the Greater Gariep agricultural area adjacent to the Orange River between Prieska and the Vanderkloof dam alone an estimated 311 000 ton/yr of maize and wheat straw is available. These agricultural residues have an energy equivalent of 196 000 ton of coal per year and should be utilised as a renewable energy resource. A technical and financial evaluation on the collection and transport of agricultural residue showed that the Hopetown area has the highest concentration of agricultural residue in the Greater Gariep agricultural area with approximately 68 000 ton/yr that is spread out over 76 kmª. Briquetting, combustion, pyrolysis and gasification were identified as the technologies with the highest potential to convert agricultural residue into a higher grade energy product in this area. The expected overall energy conversion efficiency for a plant capacity between 5 000 to 100 000 ton/yr is 98.9%, 10-25%, 25-30% and 28-36% for the briquetting, combustion, pyrolysis and gasification plants respectively. A financial evaluation based on the internal rate of return and the net present value of investment showed that the briquetting plant is financially feasible and the most profitable for capacities between 25 000 and 60 000 ton/yr while the pyrolysis plant was financially feasible and the most profitable technology for capacities greater than 60 000 ton/yr. A sensitivity and risk analysis done on the proposed briquetting and pyrolysis plants to evaluate the impact of market fluctuations on the profitability of the power plants exposed the briquetting plant as a very high risk investment, mainly because of the sensitivity to the selling price of fuel briquettes and the high maintenance cost associated with the briquetting equipment. Although the proposed pyrolysis plant is sensitive to variation in the electricity price, the risks associated with the market conditions for the pyrolysis plant is very low and an internal rate of return of 15% is still projected at the minimum expected electricity price. From the study it is clear that the utilisation of agricultural residue available in the Greater Gariep agricultural area is technically and financially viable.
- ItemAn automotive interior lighting application using white light-emitting diodes(Cape Town : Cape Town University, 2008) Solomon, Ramzi; Pillay, P.; Sebitosi, A.B.; Stellenbosch University. Faculty of Engineering. Department of Mechanical and Mechatronic EngineeringEnergy drives technological societies. Developing countries such as South Africa are caught between the desperate need for economic growth and the emerging obligations to the environment. Efficient technologies can be used to mitigate the impact of these seemingly conflicting requirements in urban and rural environments. In this thesis the commercially available white light-emitting diode (LED) with its inherent efficiency, longevity and mechanical strength, is used to show, that success in energy efficiency can be obtained. Two cases are used to illustrate the need for efficient demand-side technology: the electricity shortages of the Western Cape Province in South Africa and a white LED pilot project in Namulonge, Uganda. The Namulonge Solar-Home System (SHS) is analyzed with the intention of creating a more acceptable general lighting solution. The concept of appropriateness through self-determination is discussed within the context of location-specific information integrated into a design procedure. The major thrust and contribution of this thesis, however, is the design of an interior luminaire for Golden Arrow Bus Services (GABS). This is in part based on the hypothesis that application-specific information will lead to implementation and human-needs success, and is researched, designed, fabricated and then laboratory tested. The biggest challenge to be overcome was the spatial light distribution of the LED array. Thus non-imaging optical lens design became the main focus of this project as it held the key to utilizing available light while conserving the light-systems energy. Circular Fresnel and Linear Fresnel (an adaptation of the concentric design) lenses were designed. Electrical, mechanical and thermal aspects of design are also detailed. Far-field, horizontal plane detection over the specified area is used to best gain the uniformity of distribution. The four criteria namely luminance, illuminance, intensity and étendue (collection efficiency), against which each design and focal length iv configuration is compared to, are extensively explored and eventually lead to a final design. In the first designs, the area of the spatial distribution between 50% and 80% of its relative intensity is collimated. The Hybrid Circular Fresnel and Hybrid Linear Fresnel lenses now redirects the relative intensity in two areas, from 50% to 70% (creating parallel rays) and then from 70% to 100% (away from the central axis), renders a distinct difference is spatial uniformity and a reduction in the peak and offaxis located intensity. All four criteria are met, with a minor adjustment of configuration within the bus internal luminaire spacing, with the hybrid designs. It is proposed that GABS employ polished designs of the Hybrid Circular Fresnel, in any of the configurations, which have collection efficiencies ranging between 64.8% and 78.3%.
- ItemBiodiesel analytical development and characterisation.(Stellenbosch : University of Stellenbosch, 2010-03) Prah, Ebenezer; Callanan, L. H.; Lorenzen, L.; University of Stellenbosch. Faculty of Engineering. Dept. of Process Engineering.ENGLISH ABSTRACT: Development of analytical methods to characterise biodiesel has become central to the overall success of the marketing of biodiesel fuel. In this regard, different bodies including the American Society for Testing and Materials (ASTM) and the European normalization (EN) have come up with various methods to determine important biodiesel parameters such as total glycerol, methanol and the fatty acid methyl esters (FAMEs), etc. Various studies have been conducted on the parameters mentioned above using a variety of instrumentation and sample preparations. The best methods reported are those that have been adopted by both the ASTM and EN standards. The purpose of this study was to develop alternative analytical methods to both the recommended ASTM and EN methods and, in some cases, to make modifications to both standards (ASTM D 6571 and EN 14214) and methods to determine total and bound glycerol, the ester content and also methanol content in biodiesel. Moreover, water washing after transesterification and the effect this practice has on biodiesel cold flow properties such as kinematic viscosity, cloud and pour point and density were evaluated. The possibility of using the iodine value to predict the feedstock source of an unknown biodiesel was also investigated. Six different vegetable oil samples were transesterified with methanol and used for this study. The six samples used were palm, crown, sunflower, waste vegetable oil (wvo), peanut and rapeseed biodiesel. Quantitative results indicated that the use of programmable temperature volatilisation (PTV) for total glycerol did not produce the required repeatability of between 1-4% relative standard deviation(RSD) for total glycerol analyses in biodiesel with precision of 25%, 86%, 25% and 56% for free glycerol (FG), monoglycerides (MG), diglycerides (DG), and triglycerides (TG) respectively. The standard requires a relative standard of between 1-4% As an alternative to the method using gas chromatography, normal phase high performance chromatography (HPLC) with binary gradient elution was used to determine the bound glycerol content. This method proved accurate and repeatable with RSD % of 0.33, 1.12, and 1.2 for TG, DG and MG respectively. Following the EN14103 protocol (European standard ester determination), the Zebron ZBWAX column which is comparable to the specification recommended by EN14103 but afforded the determination of ester content from the esters of myristic acid (C14:0) to behenic acid (C22:0) with reproducibility with RSD % of 6.81, 1.91, 7.27, 0.64, 1.18, 1.55, 6.03, 1.96, and 5.21 for methyl esters of myristic, palmitic, stearic, oleic, linoleic, linolenic, arachidoic, gadoleic and behenic acid respectively. Solid phase micro extraction (SPME) using GC-MS was developed as an alternative to both the EN14110 and ASTM D93 protocols for determining the methanol content in biodiesel. For this method, polyethylene glycol fibre (PEG) was used together with a deuterated methanol internal standard and a DB-FFAP (60m×0.25um×0.25um) column. Less volume of sample was required as compared to the EN14214 method. This method was found to be sensitive, accurate and repeatable with a RSD % of 4.82. The Iodine number of biodiesel decrease compared to their corresponding feed stock and therefore predicting the feed stock of an unknown biodiesel was going to be difficult .Results from this study indicated that it is not possible to predict the feed stock source of an unknown biodiesel from its iodine value. The effect of water washing after phase separation on biodiesel cold flow properties such as kinematic viscosity, density, cloud and pour point depended on the type of biodiesel produced. We observed that water washing after transesterification caused an increase in all the cold flow properties of sunflower biodiesel, whereas only the densities and kinematic viscosities increased in the case of palm and waste vegetable oil biodiesel. The cloud and pour point of the latter two diesel samples remained unchanged after water washing. Thus, the effect of water washing on biodiesel cold flow depended on the type of biodiesel. Blending a highly saturated biodiesel (fewer numbers of double bonds) with a less saturated biodiesel (higher number of double bonds) resulted in an improvement of both the pour and cloud points of the resultant biodiesel blend.
- ItemCarbon finance and reforestation : a survey of African cases(Stellenbosch : University of Stellenbosch, 2010-12) Lagrange, Chantal V. M.; Stamm, A.; McDonald, I. A. W.; University of Stellenbosch. Faculty of Economic and Management Sciences. School of Public Leadership.ENGLISH ABSTRACT: This thesis addresses the topic of carbon finance in the context of reforestation and avoided deforestation. The research is based on the Nhambita Reduced Emissions from Deforestation and Degradation (REDD) and Agro-forestry carbon offset project in North West Mozambique. The thesis raises important questions in terms of the relevance of carbon offset projects to human and biophysical realities in Africa. The research was conducted through the lens of ethnographic development and explores how carbon offset projects are received by recipient communities. What issues do such projects attempt to address? Are the targeted issues the „real‟ issues, as they are perceived by local populations in developing countries? Who do such projects benefit and who do they benefit the most? The thesis comprises two academic papers. The first paper is a synthesis article presenting a review of key issues with regards to the roll-out of improved cooking stoves (ICS) in the context of carbon offset projects, combined with a pre-feasibility study on the introduction of ICS in the Nhambita village. It shows how biomass will continue to play a dominant role in addressing Southern African energy needs and how a large scale dissemination of ICS could play a seminal role in alleviating pressure on threatened ecosystems. The paper, however, recognizes that ICS programmes are not a panacea and discusses the pitfalls of paradigms underlying stove-provision programmes to date. Based on a review of the pertinent literature and on the field work conducted in Mozambique, conclusions are drawn that environmental and health considerations do not constitute a sufficient „pull‟ factor from the end user‟s perspective. It appears that best channels to engage with the targeted users are economic and social rationales. This debate is of particular relevance to climate change policy but it also offers insights in terms of the acceptance of such programmes by the target communities. The second paper is related to the first in that it discusses the opportunities and challenges associated with the developmental ambitions of carbon offset projects. By virtue of the market systems that regulate them, such carbon offset projects imply an innovative developmental praxis, whereby project recipients become the owners and the sellers of a tangible good in the form of carbon credits. This innovative dimension is, however, thwarted by the fact that such projects stir welfare expectations from project participants. Such livelihood improvement expectations become the fertile ground for difficulties reminiscent of the weakness of traditional aid. The intricacies underpinning this new mechanism that combines land use changes with environmental conservation and livelihood benefits are debated in the context of private entrepreneurship and global markets. The analysis is anchored in a socioanthropological interpretation of climate change science and lays the emphasis on the risks and constraints of such projects, from the perspective of the target communities. The paper concludes by discussing the policy implications of these findings.
- ItemCharacterisation of a solar roof tile (SunSlates™) : with focus on local applicability and conditions(Stellenbosch : Stellenbosch University, 2008-12) Rautenbach, Karel Frederick; Swanepoel, R.; Meyer, R.; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.Three SunSlates™ were investigated to predict the performance of a fully installed system. The three slates were mounted on a fixed tilt of 30°, but with different orientations. The tilt is close to latitude of the Stellenbosch site, which is 33.92°. The one faces due east, another due west and last due north. This is to determine the effect that orientation has on the energy from the SunSlates™. Another slate, also facing north, was mounted on an adjustable framework. The framework was used to adjust the tilt angle of the slate, the orientation of the slate was constantly north. This slate was used to determine the effect of tilt on the total daily energy produced by the slate. To determine the performance of the slates daily measurements of temperature, solar insolation and wind was taken. These were used to investigate the effects on the SunSlates™. During the test period, which scheduled from September to November, the results show a difference, smaller than commonly believed, in the daily and annual energy delivered from the differently orientated slates. The slates facing east and west, however, have similar energy outputs, even though the power profiles differ. The north facing slate has the highest annual energy output, as expected. It was found that during the months of summer, November to January, the optimal tilted slate (Slate tilted to have a incidence angle of 0° from solar rays at noon) had a slightly lower energy output, but higher maximum power output per day than the 30 degree tilted slate. This is in contrast to the energy output predictions for the winter months where in the winter the energy can be as much as double that of the 30 degree tilted slate. The thorough testing and expert installation of the SunSlates™ are essential. From the case study it can be seen that some problems during installation, possibly a single faulty slate or shadowing, can cause a complete system to lose 30% of its efficiency.
- ItemCommercial biodiesel production in South Africa : a preliminary economic feasibility study(Stellenbosch : University of Stellenbosch, 2007-03) Nolte, Mirco; Lorenzen, L.; University of Stellenbosch. Faculty of Engineering. Dept. of Process Engineering.Biodiesel, a fatty acid alkyl ester, derived from the transesterfication of vegetable oil, is considered a renewable fuel that can be used as a replacement for fossil diesel. The urgency for biofuel production in South Africa is motivated by the vulnerability of crude oil prices, high unemployment, climate change concerns and the need for the growing economy to use its resources in a sustainable manner. The technical feasibility of biodiesel production has been proven and this study investigates its preliminary economic feasibility in South Africa by looking at the market, financial and agricultural feasibility of commercial biodiesel production.
- ItemA comparative study on the performance of biodiesel in a modern 1.9L turbo diesel engine(Stellenbosch : University of Stellenbosch, 2010-03) Kotze, Johan; Van der Spuy, S. J.; Lorenzen, L.ENGLISH ABSTRACT: This thesis comprises of the testing and evaluation of a modern diesel engine running on both biodiesel and mineral diesel on the upgraded Bio-fuels Testing Facility (BTF) at Stellenbosch University. The project was motivated by the need to install a modern diesel engine onto the existing BTF test rig for biodiesel testing. In this project, the BTF was re-designed to support a new Volkswagen 1.9L TDI engine. The capabilities of the BTF were then expanded further by the implementation of a low-cost pressure indicating system, utilising an optical pressure transducer. During the testing of biodiesel, it was found that the calorific value of the biodiesel was 14% lower than that of the tested mineral diesel. The ignition quality (cetane index) of the biodiesel was also lower than that of the mineral diesel. Even so, the engine only experienced a maximum power loss of 4.2%. During heat-release analysis, it was determined that there was no significant difference in the combustion process of biodiesel and that of mineral diesel. The conclusion could be made that biodiesel is suitable for use in modern TDI engines. Testing validated the operation of the upgraded test cell, and in trials it was determined that the test results are highly repeatable. The pressure indicating set proved to have some limitations. Only simplified heat-release analyses and reasonable indicated power calculations could be performed with the indicating set. Recommendations were made for improvement in future research.
- ItemDecoupling infrastructure services from unsustainable resource use : cases from Cape Town(Stellenbosch : University of Stellenbosch, 2011-03) Robinson, Blake; Swilling, Mark; University of Stellenbosch. Faculty of Economic and Management Sciences. School of Public Leadership.Please refer to full text to view abstract.
- ItemDesign and analysis of a gearless, direct grid, permanent magnet induction wind generator(Stellenbosch : University of Stellenbosch, 2011-03) Potgieter, Johannes H. J.; Kamper, M. J.; University of Stellenbosch. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.; Stellenbosch University. Faculty of Engineering. Centre for Renewable and Sustainable Energy StudiesENGLISH ABSTRACT: In this study a new type of gearless, direct-drive wind generator, which can be connected directly to the grid, is proposed. The working characteristics of this generator are based upon the principles of the permanent magnet induction generator (PMIG). By omitting the need for a gearbox and power electronic converter this generator type has several advantages regarding cost and reliability. Although the PMIG is proposed in previous studies as favourable for wind power generation, the mechanical complexity and difficult construction associated with these types of generators, seems to be the main reason why these generator systems are not used. The design methods presented in this study are intended to alleviate these constructional issues by proposing the split-PMIG (S-PMIG), where the stator winding and the induction cage-rotor windings are electromagnetically separated. The machine is basically split into two permanent magnet (PM) machines, a grid connected synchronous generator (SG) unit and a turbine connected induction generator (IG) unit. These two units are mechanically linked by a common PM-rotor. To evaluate this concept a finite element (FE) design analysis is done independently for both machine components. The emphasis of the design optimisation is the minimisation of the cogging torque, while still having a decent performing, easily constructible generator. This generator should also have low load ripple content. Cogging torque can result in the failure of the turbine to start up, especially at low wind speeds. As this is a directly grid connected generator, torque ripple transferred to the common PM-rotor can destabilise the generator. Based upon the FE designs a preliminary S-PMIG system is constructed and practically evaluated. Due to the modular nature of the design it is possible to implement the synchronous generator part of the S-PMIG in conjunction with a grid-connected solid state converter (SSC). This allows for a useful comparison with the S-PMIG system. Promising results are obtained from initial tests of the S-PMIG directly connected to the grid. It is shown that the operation of this generator is stable under a wide range of wind load conditions. However, some important machine design issues are identified from these practical results, which could prove vital in the implementation of future S-PMIG designs.
- ItemDesign and implementation of a low cost grid-connected 10 kw hydro power system(Stellenbosch : University of Stellenbosch, 2010-03) Lombard, Adriaan Cornelius Johannes; Kamper, M. J.; University of Stellenbosch. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: The world is increasingly being faced with the challenge of effectively exploiting available renewable energy resources, not only to meet an ever growing energy demand, but also to preserve the available amount of fossil fuels and to reduce the amount of carbon dioxide emissions released into the atmosphere by fossil fuelled power stations. Hence, every available renewable energy resource, even small rivers has a contribution to make in the attempt to reduce the amount of fossil fuel generated electricity. The focus of this study is the design and installation of a low cost grid-connected 10 kW micro hydro power system (MHPS). The process to determine the potential of the available water resource is first to be presented. The environmental aspects of these systems, based on the study that is undertaken for the implementation of the landmark example, are discussed. The complete design of a micro hydro power system for a specific site is presented. This design is based on using commercially available components and equipment in an attempt to minimise the total cost of a micro hydro power system. The designed micro hydro power system is installed in-field and the predicted performance of the designed system is verified with measured results of the implemented system. Based on the results of the micro hydro power system landmark example, it is shown through a complete economic study, that this investment is very worthwhile.
- ItemDesign of a pump-as-turbine microhydro system for an abalone farm(Stellenbosch : University of Stellenbosch, 2010-03) Teuteberg, B. H.; Van Niekerk, W.; University of Stellenbosch. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.ENGLISH ABSTRACT: This document details the design process of a 97 kW microhydro system for Roman Bay Sea Farm in Gansbaai in the Western Cape Province of South Africa. It contains a literature study of microhydro power, with a focus on the use of Pump-as-Turbine technology and direct-drive systems. The literature study leads to several possible concepts for the project, which are then evaluated and the most suitable design is found to be a reverse running pump that powers a different pump through a direct drive system. Experimental data from KSB is used to test the accuracy of various correlations that can be used to generate turbine-mode operation curves from pump curves. The final design parameters for the complete system are then determined, and presented along with a cost benefit analysis.
- ItemDesign, build and test a passive thermal system for a loft : a roof solar chimney application for South African weather conditions(Stellenbosch : Stellenbosch University, 2007) Beviss-Challinor, Lauren Margaret; Dobson, R. T.; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.ENGLISH: The design, construction and testing of a passive thermal system, a roof solar chimney, for a loft is considered. Unlike conventional solar chimneys the solar collector is constructed from corrugated iron roof sheets with the aim that it can be integrated into existing buildings at a lower cost or used in low cost housing developments. The main objective of the study was to determine the feasibility of such low-cost design to regulate thermal conditions in a loft, that is heating the loft during winter and enhancing natural ventilation during summer, by carrying out an experimental and analytical study. The results obtained from the experimental study showed that for winter the solar chimney, having a channel width, depth and length of 0.7 m, 0.1 m and 1.8 m respectively and with a peal solar radiation of 850 W/m², heated the room air 5°C higher than the ambient temperature during the hottest periods of the day, which is only marginally better than a loft with conventional roof insulation. At night, it was found that reverse airflow occurred through the chimney, cooling the loft down to ambient temperature, due to radiation heat loss from the roof collector to the night sky. For summer operation, the experimental data showed that the chimney was able to maintain the loft at ambient temperature and the analytical study found that the chimney was able to enhance natural ventilation effectively, reaching air exchange rate of 6.6 per hour for the 4.6 m³ volume space. It was also found that the chimney’s performance dropped rapidly and significantly during periods of low solar radiation and at night. A sensitivity analysis illustrated that for both summer and winter operation, the size, tilt angle and absorptivity of the roof collector greatly effected the efficiency and mass flow rates of the system, agreeing well with other literature. These results prove that this low cost solar chimney cooling design was feasible to enhance natural ventilation mainly during hot summer conditions with high solar radiation. Compared to a loft with only conventional roof insulation, the chimney did not perform effectively during the winter to heat the loft up, meaning that winter operation for this specific design is not feasible. Possible improvements to the design include using construction materials with higher thermal capacities to retain heat energy and ensure continued operation during periods of low solar radiation, as well as using selective absorber coatings on the collector surface. It is recommended that further work on the project include the integration of these improvements into the present design and to use the findings obtained from the sensitivity analysis to improve system efficiencies. CFD analysis of the test-rig will be insightful as an additional means to validate and compare with the analytical and experimental data obtained in this report. With the continuation of these studies, this low-cost solar chimney design can be optimised, validated on a commercial scale and built into existing and new housing developments. Incorporating such a passive thermal device will aid homeowners in air regulation and thermal comfort of their living space as well as saving on energy requirements.
- ItemDeveloping a scorecard for sustainable transport : a Cape Town application(Stellenbosch : University of Stellenbosch, 2009-03) Du Toit, Rudolph; Muller, A.; University of Stellenbosch. Faculty of Economic and Management Sciences. School of Public Management and Planning.Globally, transport and its associated ills are creating urban landscapes that can best be described as unhealthy, unfriendly and unsustainable. The unsustainable nature of current transportation practices are most keenly displayed in four key areas, namely: the pending oil peak; global climate change; environmental degradation and social deprivation. South Africa is no exception to these impacts, but also suffers an extra disadvantage of demonstrating very little knowledge of more sustainable transportation option in terms of its planning regime. This study endeavours to improve the state of sustainability in transportation planning by developing a user-friendly and pragmatic transportation sustainability appraisal mechanism and testing this mechanism on a real-life case. In order to develop such an appraisal mechanism, the theory of sustainable development is firstly examined to provide direction to the study, followed by an attempt to distil the most pertinent principles of sustainable transport from the literature. These principles form the objectives which the appraisal mechanism aims to measure sustainability against. Owing to the poor level of awareness regarding sustainable transport practices in South Africa, a discussion on selected benchmark sustainable transport practices is also included in the study and consequently added to the appraisal mechanism. To test its operability, the appraisal mechanism is finally applied to Cape Town’s Draft Integrated Transport Plan (ITP) 2006-2011. The study indicates that the ITP is a reasonably sustainable transport plan, with the exception of its affordability and public participation aspects. These exceptions are attributed to the ITP either not properly addressing these aspects, or due to the ITP not providing enough information on these aspects. Finally, the study found that the developed appraisal mechanism is operable in the field of transportation planning, but suggests that the mechanism be further developed and refined to improve its value and effectiveness. A transdisciplinary process involving the input of community stakeholders and specialists is identified as major area for such development
- ItemThe development of a biofuels engine testing facility(Stellenbosch : Stellenbosch University, 2008-12) Palmer, Duncan; Lorenzen, L.; Van der Spuy, Johan; Stellenbosch University. Faculty of Engineering. Dept. of Process Engineering.; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.This report covers the development of a biofuels engine testing facility at Stellenbosch University. The motivation for the project was three fold: a) a desire to establish biofuels and engine testing know-how; b) to test the performance characteristics of biodiesel; and c) make a facility available for future research. The two main conclusions drawn from the initial test results are: 1) the test cell is fully operational and 2) biodiesel can be substituted for mineral diesel. To the author’s knowledge this is the first biofuel specific engine testing facility in South Africa. After a literature study the test cell was realised in three phases. • Firstly, the hardware layout was designed and the necessary equipment was sourced from respectable suppliers including the judicious use of good qaulity second hand components to minimize capital cost. • The test cell was then instrumented with new sensors. Key components among these are the K-type thermocouples, barometric pressure, humidity, oil pressure and an Allen-Bradley programmable controller to serve as a data acquisition card. Two software programs were chosen, ETA for the control of the test cell and RSLogix to program the programmable logic controller (PLC). • The complete system was then integrated, debugged and validated. The design methods and procedures have been documented throughout the project along with user manuals to facilitate further research. To determine the difference in combustion parameters between biodiesel and mineral diesel an autonomous power curve test was conducted. This revealed little difference in terms of performance between the two fuels, although biodiesel had on average a marginal 0.4% decrease in power over mineral diesel. The fuel consumption for pure biodiesel was found to be higher, which is as expected as it is has a lower calorific value than mineral diesel. As a final validation, an energy balance was conducted. Here the calculated calorific value of biodiesel was compared to the results from a calorie bomb test, and the two results were found to be within 2% of each of other.
- ItemEconomic development, decoupling and urban infrastructure : the role of innovation for an urban transition in Cape Town(Stellenbosch : University of Stellenbosch, 2011-03) Hyman, Katherine; Swilling, Mark; University of Stellenbosch. Faculty of Economic and Management Sciences. School of Public Leadership.; Stellenbosch University. Faculty of Engineering. Centre for Renewable and Sustainable Energy StudiesENGLISH ABSTRACT: This thesis investigates the case of the Cape Town Central City Provincial Government Revitalisation Initiative (CCPGRI) as a means to further understanding of socio-technical transitions. The departure point for this research is the recognition that the current economic growth and development trajectory is unsustainable. Despite this, deeply institutionalised frames of reference for decision-making reinforce and perpetuate the utilisation of (incumbent) sociotechnical systems which diminish finite resources and deteriorate eco-system services. The theoretical notion of decoupling, however, offers an alternative economic development paradigm. Decoupling has been identified, within this thesis, as the guiding framework through which adaption strategies should be carried out. This was indentified through a comprehensive literature review and an assessment of Cape Town's critical networked infrastructure. Networked infrastructure conveys flows of resources across vast urban spaces, in a linear configuration, thus conditioning resource flows and consumption. The case of Cape Town, however, illustrates that a linear configuration of infrastructure is both financially and environmentally unsustainable. Moreover, the case provides the empirical evidence for decoupling, reinforcing the argument for the adoption of the notion as an alternative development paradigm. Networked infrastructure has furthermore been identified as a socio-technical system, and therefore is considered as the component requiring a system transition and the subsequent intervention point for decoupling economic growth from resource consumption. From an implementation perspective, socio-technical system transitions, achieved through innovation, are the necessary component for realising sustainable urban development. It is argued that innovation, necessary for socio-technical system transitions, should be the product of sustainability-orientated innovation systems (SOIS's). SOIS's are implicitly linked to decoupling through the shared goal of enabling greater sustainability. The Cape Town CCPGRI has been extrapolated onto the multi-levelled perspective (MLP) model and is used to further understanding about how socio-technical system transitions are achieved. Findings indicate that socio-technical systems transitions are possible in urban areas that have multiple niche innovations developing simultaneously. Of significance is the presence of an intermediary, who is able to facilitate and manage the development of niche innovations emerging from SOIS's. It is therefore argued that high quality networking is critical for achieving socio-technical transitions which emerge from SOIS's.
- ItemAn economic evaluation of a wind power electricity generating farm in South Africa(2011-12) Menzies, Greig Hamilton; Hosking, S. G.; Sale, M. C.; Stellenbosch University. Faculty of Engineering. Centre for Renewable and Sustainable Energy StudiesENGLISH ABSTRACT: Renewable energy technology has received much attention over recent years. The depletion of known fossil fuel reserves and the volatility of international fuel prices require that society looks beyond the current coal-dominated electricity generation methods. Wind energy is an internationally well-established technology with large markets in major countries around the world, such as the USA and Germany. South Africa has the potential to generate large amounts of electricity from the wind because of the strength of the country’s wind resource. The long coast line and open areas are ideal for the exploitation of wind energy.
- ItemEvaluation and performance prediction of a wind turbine blade(Stellenbosch : University of Stellenbosch, 2009-03) Pierce, Warrick Tait; Von Backstrom, T. W.; University of Stellenbosch. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.The aerodynamic performance of an existing wind turbine blade optimised for low wind speed conditions is investigated. The aerodynamic characteristics of four span locations are determined from surface pressure measurements and wake surveys with a traversed five-hole probe performed in a low speed wind tunnel for chord Reynolds numbers ranging from 360,000 - 640,000. Two-dimensional modelling of the wind tunnel tests is performed with the commercial computational fluid dynamics code FLUENT. The predictive accuracies of five eddy-viscosity turbulence models are compared. The computational results are compared to each other and experimental data. It is found that agreement between computational and experimental results varies with turbulence model. For lower Reynolds numbers, the Transitional-SST turbulence model accurately predicted the presence of laminar separation bubbles and was found to be superior to the fully turbulent models considered. This highlighted the importance of transitional modelling at lower Reynolds numbers. With increasing angles of attack the bubbles were found to move towards the leading edge and decrease in length. This was validated with experimental data. For the tip blade section, computations implementing the k-ε realizable turbulence model best predicted experimental data. The two-dimensional panel method code, XFOIL, was found to be optimistic with significantly higher lift-to-drag ratios than measured. Three-dimensional modelling of the rotating wind turbine rotor is performed with the commercial computational fluid dynamics code NUMECA. The Coefficient of Power (Cp) predicted varies from 0.440 to 0.565 depending on the turbulence model. Sectional airfoil characteristics are extracted from these computations and compared to two-dimensional airfoil characteristics. Separation was found to be suppressed for the rotating case. A lower limit of 0.481 for Cp is proposed based on the experimental data.
- ItemEvaluation of different process designs for biobutanol production from sugarcane molasses(Stellenbosch : Stellenbosch University, 2010-03) Van der Merwe, Abraham Blignault; Knoetze, J. H.; Gorgens, Johann F.; Stellenbosch University. Faculty of Engineering. Dept. of Process Engineering.ENGLISH ABSTRACT: Recently, improved technologies have been developed for the biobutanol fermentation process: higher butanol concentrations and productivities are achieved during fermentation, and separation and purification techniques are less energy intensive. This may result in an economically viable process when compared to the petrochemical pathway for butanol production. The objective of this study is to develop process models to compare different possible process designs for biobutanol production from sugarcane molasses. Some of the best improved strains, which include Clostridium acetobutylicum PCSIR-10 and Clostridium beijerinckii BA101, produce total solvent concentrations of up to 24 g/L. Among the novel technologies for fermentation and downstream processing, fedbatch fermentation with in situ product recovery by gas-stripping, followed by either liquid-liquid extraction or adsorption, appears to be the most promising techniques for current industrial application. Incorporating these technologies into a biorefinery concept will contribute toward the development of an economically viable process. In this study three process routes are developed. The first two process routes incorporate well established industrial technologies: Process Route 1 consist of batch fermentation and steam stripping distillation, while in Process Route 2, some of the distillation columns is replaced with a liquid-liquid extraction column. The third process route incorporates fed-batch fermentation and gas-stripping, an unproven technology on industrial scale. Process modelling in ASPEN PLUS® and economic analyses in ASPEN Icarus® are performed to determine the economic feasibility of these biobutanol production process designs. Process Route 3 proved to be the only profitable design in current economic conditions. For the latter process, the first order estimate of the total project capital cost is $187 345 000.00 (IRR: 35.96%). Improved fermentation strains currently available are not sufficient to attain a profitable process design without implementation of advanced processing techniques. Gas stripping is shown to be the single most effective process step (of those evaluated in this study) which can be employed on an industrial scale to improve process economics of biobutanol production.
- ItemExploring the possibility of the insurance industry as a solar water heater driver in South Africa(Stellenbosch : University of Stellenbosch, 2011-03) Kritzinger, Karin; Sebitosi, A. B.; University of Stellenbosch. Faculty of Economic and Management Sciences. School of Public Leadership.ENGLISH ABSTRACT: South Africa is facing an energy crisis on two levels; the existing capacity to supply electricity is unable to support future growth in demand, and the electricity being produced comes mostly from coal-fired power stations with associated emission problems. The South African government has a target for renewable energy to service 23% of the country’s energy consumption by 2013. This could potentially be realised through achievement of another government target, the installation of one million Solar Water Heaters (SWHs). On a technical level, Solar Water Heaters (SWHs) represent a completely viable renewable energy alternative for South Africa. It is an established and proven technology which has the potential to have a big impact on the country’s electricity capacity problems. SWHs can be used in a variety of applications from industry to households. Most of the hot water in South African homes is heated by electric resistance heating in standard electric water heaters and there are no technical obstacles to replacing most of these with SWHs, thereby delivering a saving of up to 70% of the water heating energy bill. Water heating currently accounts for 40% of domestic electricity consumption within a residential sector that uses 20-30% of the national supply. At the macroscale, the roll out of SWH programmes is completely scalable. The benefits of SWH installation accrue to the consumer in the form of a financial saving in the long-term and to society in the form of reduced emissions. Awareness of the benefits is growing amongst the general public, commercial institutions and in government. Sales are starting to pick up due to, amongst other reasons, electricity price hikes and government subsidies for SWH installations offered through the national electricity supply company, Eskom. A national building regulation enforcing energy-efficient water heating in new buildings has been drafted and is expected to be in place by mid 2011. The rate of change from electric to solar water heaters remains disappointingly slow, however. The SWH industry in South Africa accounts for less than 10% of total hot water solutions sold. This study sought to establish the opportunities as well as possible barriers for the creation of SWH programmes within the insurance sector. Close to 50% of all standard electric water heaters installed in South Africa are procured and installed via the insurance industry due to the failure of units that have endured beyond the manufacturer’s guarantee period. This presents an opportunity for interventions that encourage policyholders to change to SWHs. Such interventions, if successful, would dramatically speed up the roll out of SWHs in South Africa. In addition the study sought to determine the barriers to the uptake of SWHs by policyholders in the case of the two insurance companies that currently have SWH programmes in operation. Data was collected through interviews with representatives in the insurance industry and a range of SWH industry stakeholders and consumers. The literature review focused on SWH policies and regulations and corporate and marketing theories. The material on transition in socio-technological systems proved especially useful in understanding the complex dynamics of the study topic. The conclusion drawn from the research is that the South African insurance industry has the capacity and opportunity to drive the penetration of SWH technology. The opportunity is, however not being exploited to anywhere near its potential. The entire system is geared towards providing a particular ‘business-as-usual’ solution. Analysis conducted in this study confirms that the system is in a “locked-in” state and extremely resistant to change. If the opportunity is to be acted on, to supplant the dominant technology for water heating installed by the insurance industry with what is currently a niche technology (SWHs), an external landscape shock is almost certainly needed. This shock to the system could be aided by interventions that target a change in the current system’s logic. The study provides some suggestions in this regard.