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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1609531

How best to generate carbon revenue for small-scale projects in sub-Saharan Africa

Atkins, Peter Stuart January 2013 (has links)
Includes abstract. / Includes bibliographical references. / The Clean Development Mechanism (CDM) has not worked for sub-Saharan Africa and its mainly small projects, delivering only 0.3% of the total CDM carbon offsets. This is thought to be because of the low intensity of the greenhouse gas reducing interventions prevalent in sub-Saharan Africa, the lack of institutional capacity relating to the CDM processes, the high transaction costs of the lengthy CDM process – typically amounting to R 500 000 per project per year and taking years to complete the process. An alternative for small carbon emission-reducing projects is to register carbon reductions with the voluntary carbon market and its Verified Emission Reductions (VERs) carbon credits. By examining the carbon markets in some detail through the lens of a particular case study, this dissertation has investigated and identified the main factors affecting the cost-effective generation of small emission reduction projects in sub-Saharan Africa. The chosen case study was a small-scale South African voluntary carbon project, the Umdoni bioethanol gel fuel-switching project. Umdoni was identified as an example of a project that generated carbon revenue outside of the CDM. By assessing the manner in which this project addressed the critical requirements of the carbon market while simultaneously alleviating poverty, the study seeks to provide new insight in the components of effective carbon markets. Both the detailed understanding of the voluntary carbon market components and the exposition of an example in which this market worked effectively is considered important at a time when the efficacy of the CDM is being reviewed, casting uncertainty over the role of market based instruments in addressing the global threat of an anthropogenically warmed climate. The study has identified the main factors affecting the ability of small carbon projects to generate net-positive carbon revenue and has suggested ways a small project could exploit this information to its benefit: The type of carbon market the project operates in – the small voluntary carbon market is best, with higher prices and lower costs - The inherent attractiveness of the project to potential carbon offset buyers – small projects with strong sustainable development aspects command higher carbon prices - The registry and carbon standard through which the project trades its carbon offsets – registries and standards which measure and emphasise sustainable development benefits realise higher prices for suitable projects - The type of buyer – Corporate buyers purchasing carbon offsets for image and public relations purposes are best for small projects with good sustainable development co-benefits - The supply-demand situation in the relevant carbon markets – the voluntary carbon market has been relatively unaffected by the crash in the compliance market in 2012 - The project size and the calculation methods chosen – the volume of emission reductions is sensitive to the project scale, the emission reducing technology and the emission reduction methodologies chosen - The transaction costs – the transaction costs for a CDM project are in excess of R500 000, which is far bigger than the likely carbon revenue. Whereas some small voluntary carbon market registry costs are lower by a factor of six and yet they get comparable carbon prices.
1609532

A hydrodynamic investigation of platinum flotation in a pilot flotation plant

Lewis, Jonathan Stretton January 2003 (has links)
Bibliography: leaves 114-123. / The aim of this thesis was to determine the effect of impeller speed and air flowrate on the flotation of platinum in mechanical flotation cells.
1609533

Integration of wind energy systems into the grid: power quality and technical requirements

Madangombe, Taruziwa January 2010 (has links)
The integration of wind energy into the utility network has increased significantly over the past years largely as a result of the increasing environmental concerns arising from the use of fossil fuels, coupled with the anticipated global increase in oil. In South Africa, the wind energy industry is still in its infancy, with the Klipheuwel (about 3.2 MW) and Darling (about 4.2 MW) wind farms being the only grid connected projects in the country. However, grid integration studies carried out in [1] have shown that there are over 7 000 MW potential ideas for wind power in the Western Cape alone and this is a clear indication that there is a growing interest in wind development locally. The Government has also set a 4% target for the development of the renewable energy in the country by 2013. In light of the above, this thesis discusses some of the technical requirements and power quality issues that need to be addressed in order to fully integrate wind power into the network without adversely affecting the operation of the grid. These have been researched through reviewing the various standards and grid codes for wind power that have been implemented in other leading countries, in order to identify some of the requirements that can be adapted to suit our local integration process. Some of the main technical issues that are discussed in this thesis include the strength of the grid (fault levels), permitted penetration levels, choice of wind turbine and the reactive power requirements of the network. All these issues contribute towards the resolution of the impact of wind turbines on the power quality of the network, especially at the point of common coupling or connection (PCC). Various power quality phenomena were discussed in the literature but the ones that were further investigated included the voltage level profile, harmonic distortions as well as reactive power requirements from the wind turbines. These were determined both during the steady operation of the network and during a network disturbance.
1609534

Modelling local scour around bridge piers using TELEMAC

Kabir, Alamgir January 2005 (has links)
Scour at bridge crossings is a major cause of bridge failure. There are several different types of scour such as general scour, constriction scour and local scour. One of the most serious types is local scour which occurs as a result of vortex formation around bridge piers and abutments (Hoffmans & Verheij, 1997; Raudkivi, 1998; Melville & Coleman, 2000; Richardson & Davis, 2001; Armitage & McGahey, 2003). Local scour is also one of the most difficult to predict accurately. If not adequately designed for, local scour of a riverbed at a bridge pier may become deep enough to undermine the pier foundation and eventually cause the bridge to collapse. Complete protection against scour is expensive and therefore not a favourable design option. It is generally cheaper to ensure that the foundation lies below the maximum expected scour depth. Traditionally, the maximum scour depth is predicted from empirical equations derived from simple laboratory tests without much regard for local conditions. Alternatively, smaIlscale hydraulic models, which are laborious and time intensive, are widely used. In view of the above, increasing attention is being paid to the use of Computational Fluid Dynamics (CFD) based modelling for the prediction of local scour and its opposite, local deposition. The ever-improving capabilities of computers and the increasing availability of powerful and flexible CFD codes have further assisted in this process. This study is a contribution in this direction.
1609535

The effect of temperature and crystallite size on the growth and morphology of carbon nanotubes

Kleinsmidt, Jacques N January 2005 (has links)
The aim of the study was to synthesise iron oxide crystallites with different crystallite sizes supported on y-A120 3 using the reverse micelle technique. It was hypothesised that changing the crystallite size of the synthesised iron oxide crystallites could lead to the control of the external nanotube diameter. The effect of temperature on the external diameter and productivity was also investigated. It was found through titration and AAS that the iron loading was lower than the expected 15 wt.-%. Furthermore, it was observed that the loading was not consistent through different catalyst samples. This was attributed to incomplete precipitation of iron using the reverse micelle technique, the rigorous cleaning regime implemented and weak metal-support interaction. It was found through XRD and TEM that crystallites in the nanometre range were produced although they were not well distributed over the support. It was also found that the expected linear relationship between water to surfactant ratio and crystallite size was not achieved. Hence the obtained crystallite sizes were significantly different from those obtained in the work by Mabaso.
1609536

The role of collectors in the flotation of partially oxidised copper ores

Hangone, Gregory January 2004 (has links)
The effects of xanthates, dithiophosphates, dithiocarbamates and mixtures of these collectors on the froth flotation performance of partially oxidised and oxidised copper sulphide ores were investigated in this study. More specifically, the role of the functional groups of the collectors, their dosages and the effect of collector mixtures and their dosages were investigated. Batch flotation tests were used to assess the performance in terms of mass-water recovery, sulphur grade-recovery, copper grade-recovery and acid soluble copper grade-recovery relationships and the Klimpel rate constant for copper recovery. Flotation characteristics of bornite rich Carolusberg copper sulphide ore from Okiep Copper Company (1.8% copper) and bornite and chalcopyrite rich ore from Palaborwa Mining Company (0.58% copper) were compared.
1609537

Limit Analysis and Shakedown in Plane Frames and Plane Stress Problems

Douglas, Andrew Sholto January 1977 (has links)
A method is developed for the determination of the shakedown load factor for elastic, perfectly plastic plane frames subjected to cyclic loading or random loads varying between fixed limits. The essential feature of the method is the employment of an automatic force method of elastic analysis which provides self-stress systems for the frame. This in turn permits the ready formulation of the compatibility requirements which are imposed on plastic hinge rotations. As a result, the analysis proceeds with data input which is comparable to straightforward kinematic analysis. A preliminary study of the generalisation of this approach to the limit analysis of plane stress problems is also given.
1609538

Energy from sugarcane by-products : analysis for Kenya

Mbithi, Justus M. P. January 2003 (has links)
Bibliography: leaves 68-71. / The Kenyan sugar industry continues to face the task of being competitive in a liberalized global economy that has witnessed a trend in declining sugar prices and increasing local production costs. This dissertation attempts to investigate possible options that could assist Kenyan sugar industry to cope with the crisis. One such option is the diversification of the sugar industry's product base. Expanding their business to energy as a co-product to sugar processing, sugar companies could generate additional revenue from surplus electricity sales to the national utility. In Mauritius, gross revenue of USD 50 million, equivalent to 90% of that accruing to the miller for cane processing is generated from bagasse-based energy sales. On the basis of the Mauritian and other experiences the research concludes that Kenya sugar industries have the potential to export 43, 258, and 306 GWh of electricity to the national grid, depending on the mode of operation of the power plant. Thus the potential for revenue expansion through power sales for the Kenyan sugar industry is substantial. Power sector reforms have seen the entry into the electricity market of independent power producers (IPPs), and so this presents a good opportunity for sugar companies to enter into power purchase agreements with the national utility for the supply of power. Anaerobic digestion systems, used in the treatment and management of industrial effluent provide an additional benefit of generating boiler fuel in the form of biogas in sugar industries of Kenya. This technology and its application to the sugarcane industry are reviewed as part of this thesis.
1609539

Further numerical techniques for planar elastostatic analysis by the boundary integral equation method

Howell, Graham Conrad January 1984 (has links)
Includes bibliography. / Prior experience of the Finite Element Method stimulated interest and led to research into the Boundary Integral Equation Method, specifically for the solution of planar elastostatic problems. A complete expose of the mathematical theory of the Boundary Integral Equation Method is given. The basis of the method is traced and the similarities and differences as opposed to the Finite Element Method, are highlighted. The numerical implementation of the method, using constant, linear and quadratic interpolation functions over the boundary segments is developed and then inclusion in computer programs is discussed. Attention is given to the problem of numerical integration over a singularity, for which detailed expressions are given. The verification and applicability of the technique is thoroughly investigated in five fully documented examples. Solutions to the problem of traction discontinuities at a corner are proposed and an analysis of the inclusion of body forces, together with documented examples, are described. Also investigated is the nonsymmetric form of the resulting matrices. It is proven that no direct and practical way can be found to render these matrices symmetric. By investigating the error in the numerical integration process, the suitability of segments is also discussed. Emphasis is placed on the solution of non-homogeneous domains and domains which extend to infinity. The development of the necessary numerical techniques required in both cases is discussed and fully documented. Finally, a method of automatically improving the accuracy of the solution of the Boundary Integral Equation Method by using p and h convergence adaptive processes is also presented.
1609540

Low loss microwave power combiners/dividers

Waardenburg, Thijs January 1986 (has links)
Includes bibliographical references. / As many current applications require microwave solid state sources with output powers greater than that available from a single device a need for combining the power from these devices is required. N-way combiners/dividers may be used to achieve this. For high output powers these combiners/dividers must have a high combining efficiency. This dissertation describes various power combining techniques and essentially a power combiner/divider that is both planar and low loss is required. The planar structure is a requirement if efficient heat dissipation is to be achieved. Cylindrical resonant cavity structures give very high combining efficiencies, however, they are non planar and have narrow bandwidths. N-way planar combiners/dividers fabricated on microstrip provide the desired planar structure but due to the characteristics of microstrip are lossy. As a culmination of this work a low loss 8-way planar stripline combiner/divider was constructed that gave a peak combining efficiency of 94 percent which approaches the combining efficiency of 98 percent that was obtained with the cylindrical resonant cavity combiner. The former offers its broader bandwidth and planar structure as advantages.

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