No description available.

Thesis (MScEng (Energy and Development Studies)) -- University of Cape Town, 2010. / ENGLISH ABSTRACT: Growing concerns regarding climate change, energy security, long-term carbon price exposure, fuel-price risk and fossil fuel depletion have continued to drive growth in wind energy globally over the past decade. In spite of South Africa’s renewable energy target and feed-in tariff for renewable energy, the current deployment of wind energy in South Africa is extremely low. Consequently, as the country embarks upon promoting the development of renewable energy, it is important to consider the challenges facing the wind energy industry in South Africa. / Sponsored by the Centre for Renewable and Sustainable Energy Studies

Organic petrology and RockEval-TOC pyrolysis studies were carried out on over 600 samples of shales, siltstones, marls and coals from forty three sections in the Upper Devonian and Carboniferous strata of the northern part of the Liard Basin and adjacent areas of northern Canada between latitudes 59° 30' N and 60° 30' N and longitudes 121° 30' W and 125° W, to determine the hydrocarbon source potential, thermal maturity and thermal history. The focus of the study is on the optical characteristics and genesis of bitumens and their viability as indicators of thermal maturity. Total organic carbon (TOC) contents indicate that potential oil and gas source rocks occur in the Muskwa, Kotcho, Besa River, Exshaw, Lower Banff, Yohin, Clausen, Golata and Mattson formations; the latter includes thin algal laminites and sapropelic coals. Hydrogen versus oxygen indices indicate that the organic matter comprises Type II kerogen, except for the Golata and Mattson formations which contain mixed Type II and Type III kerogen. Petrographic analysis indicates that the organic components consist of primary and secondary liptinites of marine origin and indigenous microscopic bitumens. In addition, shales in the Golata and Mattson contain structured liptinite macerals, predominantly sporinite derived from Carboniferous mega- and microspores. ... Organic petrology and RockEval-TOC pyrolysis studies were carried out on over 600 samples of shales, siltstones, marls and coals from forty three sections in the Upper Devonian and Carboniferous strata of the northern part of the Liard Basin and adjacent areas of northern Canada between latitudes 59° 30' N and 60° 30' N and longitudes 121° 30' W and 125° W, to determine the hydrocarbon source potential, thermal maturity and thermal history. The focus of the study is on the optical characteristics and genesis of bitumens and their viability as indicators of thermal maturity. Total organic carbon (TOC) contents indicate that potential oil and gas source rocks occur in the Muskwa, Kotcho, Besa River, Exshaw, Lower Banff, Yohin, Clausen, Golata and Mattson formations; the latter includes thin algal laminites and sapropelic coals. Hydrogen versus oxygen indices indicate that the organic matter comprises Type II kerogen, except for the Golata and Mattson formations which contain mixed Type II and Type III kerogen. Petrographic analysis indicates that the organic components consist of primary and secondary liptinites of marine origin and indigenous microscopic bitumens. In addition, shales in the Golata and Mattson contain structured liptinite macerals, predominantly sporinite derived from Carboniferous mega- and microspores.

Thesis (PhD(Agricultural Economics, Extension and Rural Development))--University of Pretoria, 2005. / Abstract in English. Includes bibliographical references.

A global tradable-permit regime designed to minimize the costs of stabilizing world carbon emissions from fossil fuel combustion at 1987 levels by the year 2000-- and to be acceptable to both OECD and non-OECD countries. / Cover title: Global tradable carbon permits, participation incentives, and transfers. "June 1994"--Cover. Includes bibliographical references (p. 20-21). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (p. 295-332).

A global tradable-permit regime designed to minimize the costs of stabilizing world carbon emissions from fossil fuel combustion at 1987 levels by the year 2000-- and to be acceptable to both OECD and non-OECD countries. / Cover title: Global tradable carbon permits, participation incentives, and transfers. "June 1994"--Cover. Includes bibliographical references (p. 20-21).

John D. Sterman, George P. Richardson. / "April 1983." "D-3432." / Bibliography: p. 38-41.

Magister Economicae - MEcon / Against the backdrop of rising fuel prices and increasing transport fuel demand, biofuel production, driven by the potential to contribute to energy security, climate change mitigation and rural development has experience rapid growth in recent years. Apart from a few private initiatives, South Africa has no commercialized biofuel industry to date. The concerns are that economic, environmental and socio economic issues can be a hindrance to the success of the industry. In response to these concerns this research intends to ascertain whether biofuel production could offer a viable economic alternative to fossil fuels in South Africa. For decision makers it is hard to find reliable reference material and solid guidance. Uncertainty over the potential risks and benefits has left potential investors unsure whether biofuel production could be a viable investment opportunity. The aim of this study was to determine if the benefits derived from biofuel production are significant enough to justify the substantial investment required. The findings reveal that in the absence of clear government strategies and the availability of low cost feedstocks the production of biofuel cannot be viewed as viable. The results show that bioethanol from grain sorghum and sugarcane are not economically viable since the results turn out to be negative in terms of both net present values (NPV) and internal rate of return (IRR) calculations, thus rendering a viable payback (PBP) period as unattainable. Similarly, the NPV and IRR for biodiesel from soya beans and sunflower is negative and the PBP also unattainable. Sensitivity analyses indicate that these crops (except for sunflowers) could only become viable if there were to be a substantial reduction in feedstock prices. All other changes in parameters would not render any of the production plant viable.

A Thesis submitted to the Faculty of Science, School of Chemistry at University of the Witwatersrand, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2015. / Photovoltaic cells offer a good alternative to the fossil fuels. Several approaches are being analysed in order to have solar cells that are capable to conquer the energy market all around the world. Quantum dots (QDs) have already proven features that can be taken into account to improve the properties of solar cells. Metal selenide nanoparticles (NPs) possess semiconducting behaviours that can vary with their structural and optical properties evolving from their synthesis. The reaction parameters such as the method, time, solvent and precursors can affect the growth and nucleation of particles and thus impose on the properties of the synthesized materials. The performance of solar cells made of the synthesized metal selenides will then be dependent upon the properties of the NPs used as active layer. Furthermore, the electrical current generation also depends on the structure of the deposited active layer and its interface with other films to be assembled for the device. The binary copper selenide, ternary copper indium selenide (CISe), quaternary copper indium gallium selenide (CIGSe) and quinary copper zinc tin sulphur selenide (CZTSSe) NPs were synthesized via conventional colloidal method (CCM) and microwave assisted method (MAM). The MAM has a particular interest as it is less time consuming and can easily be a large scale synthesis. Photovoltaic devices were fabricated from the synthesized materials as proof of concept for photovoltaic activities. The CCM was used to optimize various parameters for the synthesis of each type of the chalcogenide materials as this is easily controllable than the ones from the sealed vessel from MAM. The dependency of properties of all copper chalcogenide NPs on the time, precursor concentration, temperature and solvent of synthesis have been demonstrated via various characterization techniques including ultraviolet-visible-near infrared spectroscopy, photoluminescence spectroscopy, X-ray diffractometry and transmission electron microscopy. The binary copper selenide was first synthesized and considered as a template for evaluation of the use of copper chalcogenide materials in solar cells. Relatively smaller copper selenide NPs with average sizes of 4.5 and 6.0 nm were obtained from conventional colloidal and microwave assisted methods respectively. The sample yielded from the microwave assisted method possessed less polydispersed NPs. The later had better crystallinity in which prevailed a single cubic Cu2Se phase. To the best of our knowledge this is the first evidence of defined shapes and nearly single phase of small sized copper selenide NPs synthesized by mean of the MAM. The copper selenide particles synthesized via this method were used to fabricate a Schottky device. The conditions of copper selenide synthesis were optimized to 250 oC, 30 min of CCM synthesis using oleylamine (OLA) and a Cu/Se ratio of 1:1. Nearly hexagonal facets with blue-shifted absorption band edge of monodispersed NPs sizing 4-8 nm in diameter were obtained. The synthesized copper selenide showed better crystallinity with a single cubic Cu2Se phase. A Schottky device using MAM synthesized copper selenide NPs as the semiconducting layer was fabricated at room temperature. The diode effect was demonstrated with the electrical parameters such as the ideality factor, barrier height and the series resistances extracted from the experimental current-voltage data using the thermionic theory and Cheung’s modification. The thermionic theory resulted in the ideality factor of 4.35 and the barrier height of 0.895 eV whilst the Cheung’s method resulted in the ideality factor, barrier height and series resistance of 1.04, 2.59 10-3 eV and 0.870 Ω respectively. The ternary copper indium selenide NPs showed that the MAM allowed the formation of copper rich NPs alongside secondary products. The synthesis of the ternary sample via CCM was optimized using uncapped precursors (no TOP was added) in OLA at 220 oC for 30 min. The synthesized CuInSe2 NPs possessed a large blue-shift in their absorption band edges and emission peaks. The nearly stoichiometric CuInSe2 particles with diameter sizes of 5-9 nm were found in tetragonal crystalline orientation. The cyclic voltametry (CV) and the absorption spectra showed a large blue-shifted energy gap, about 0.95 eV, an increase from the bulk, proving the quantum confinement effects of synthesized copper indium selenide quantum dots. The CuInSe2 NPs were thus used as absorbing materials in the quantum dot sensitized solar cell devices (QDSSCs). The QDSSC devices were assembled via treatment of the titanium oxide, quantum dot layers and their interface. This was done by the treatment of copper indium selenide surface with mercapto-propionic acid (MPA) and ethanedithiol (EDT) during the deposition of the quantum dots onto TiO2 films. The MPA treatment did not reveal positive effects on copper indium selenide thin film and the assembled device under our optimized working conditions. However the use of EDT allowed the improvement of electron transport. The short circuit current (Jsc), open circuit voltage (Voc) and fill factor (FF) obtained from the current-voltage (J-V) curves reached the values of 324 μA cm-2, 487 mV and 43% respectively, indicating that the investigated quantum dots possess electrical properties. For the quaternary copper indium gallium selenide, relatively small sized NPs were synthesized via CCM and MAM. The CCM synthesized CIGSe NPs were less agglomerated with a shorter tailing in absorption than those from MAM. The stoichiometric CuIn0.75Ga0.25Se2 showed less agglomerated and highly crystalline particles with a large blueshifted absorption band edge and a smaller full width at halth maximum (FWHM) of the emission peak compared to CuIn0.5Ga0.5Se2 and CuIn0.25Ga0.75Se2. The use of OLA as solvent of synthesis improved the growth and dispersivity of copper indium gallium selenide NPs. The particles with a large blue-shifted absorption band edge, a lattice of tetragonal phase, more monodispersed CIGSe and possessing an average size of 6.5 nm were obtained from CCM synthesis using OLA. The OLA as-synthesized CIGSe NPs were used in thin film for the assembly of QDSSC. The device exhibited electrical properties with the Jsc, Voc and FF of 168 μA cm-2, 162 mV and 33% respectively. The overall device performance was poor but may further be improved for further photovoltaic application. The quinary CZTSSe NPs possessed large blue-shifted absorption band edges of 450-460 nm than the bulk material (827 nm). The emission peak at 532 nm and similar FWHM of less than 50 nm were observed in samples from both CCM and MAM. More monodispersed crystals were obtained with both methods whilst the average particle sizes of 10 and 9 nm were yielded from MAM and CCM respectively. The nanoparticles crystallized in tetragonal lattices between copper zinc tin sulphide and copper zinc tin selenide crystals. However, the MAM gave more crystalline phases. The CV and the absorption spectra showed a blue shifted energy gap, about 0.21 eV increase from the buk which is located at 1.51 eV. This is indicative of the quantum confinement effects of synthesized NPs. The evidence of electrical properties was also shown in the QDSSCs fabricated using the MAM synthesized quinary QDs. This was done following the same treatments as for copper indium selenide devices. The Jsc, Voc and FF were found at the maxima of 258 μA cm-2, 395 mV and 38% respectively. The MPA and EDT treatments did not improve the device performance under our working conditions. Nevertheless, the electrical properties observed in the assembled device were indicative of promising efficient solar cells from synthesized CZTSSe NPs.