M.A. / Although South Africa is a country endowed with abundant energy resources (fuels such as coal, uranium and gas), biomass is the prime source of energy for cooking and heating in the rural domestic sector. Fuelwood is the common biomass used, followed by crop residues and animal dung. This research examines the environmental and socio-economic impacts of biomass energy consumption in the Mbhokota village in the Northern Province. The research was conducted by means of a field survey. Data collection methods included administering questionnaires to those who are involved in fuelwood collection (mostly women), interviews with various interested groups and personal observation of the affected sites, and a review of literature relevant to this study. The use of biomass as a source of fuel has much wider implications for the social and biophysical environments. The excessive cutting of trees for fuel leads to a reduction in the diversity of plant species and destruction of habitat for wildlife. Loss of soil cover through the use of crop residues increases soil erosion and thus reduces the agricultural production. The use of biomass fuels gives rise to high levels of indoor air pollution which affects the health of people. As fuelwood supplies diminish, people must travel further and hence spend more time collecting wood. Greater time spent collecting wood means that less time is spent on food production and other household activities (farming, childcare, housekeeping, socialising and educating themselves). Other issues of concern include the high cost of purchasing wood from vendors and personal security in places where wood is collected. The above factors do not only entrench poverty, but also have dire implications for the rural economy. This study has shown that the present patterns of fuelwood collection inflict permanent damage on the environment, reducing its ability to provide further fuel in the future. The implication is that the supply of fuelwood can no longer be guaranteed in some parts of the study area, leading to the use of crop residues and animal dung. This report also highlights the recommendations and management measures (based on the results of the study) that can be used in mitigating the impacts of biomass energy use. These include the introduction of improved stoves, use of solar energy as an alternative energy source, empowerment of women, establishment of community based projects and integrating energy with rural development

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Call number: LD2668 .T4 1979 G36 / Master of Science

Call number: LD2668 .T4 1985 C48 / Master of Science

Submitted in fulfilment of the requirements of the Degree of Master of Technology: Biotechnology, Durban University of Technology, 2011. / The depletion of global energy supplies coupled with an ever increasing need for energy and the effects of global warming have warranted the search for alternate renewable sources of fuel such as biodiesel. First generation biofuels are not sustainable enough to meet long term global energy requirements and more recently there has been concern expressed as to the potential negative implication of crop based biofuels in the form of negative energy balances and potentially no greenhouse gas benefit due to land utilisation not being taken into account. Microalgae have shown great promise as a sustainable alternative to first generation biofuels. They have faster growth rates, have greater photosynthetic efficiencies, require minimal nutrients and are capable of growth in saline waters which are unsuitable for agriculture. Microalgae utilise a large fraction of solar energy and have the potential to produce 45 to 220 times higher amounts of triglycerides than terrestrial plants. The use of microalgae for biodiesel production requires strain selection, optimisation and viability testing to ascertain the most appropriate organism for large scale cultivation. This study focuses on bioprospecting for indigenous lipid producing microalgae, screening, selection and optimisation of growth and lipid yields with respect to nutrient limitation. Further we have ascertained the sustainability of a selected species of microalgae in open pond system. Chlorella sp. and Scenedesmus sp. were found to be dominant amongst the isolates. Strains we selected and underwent media selection and growth and lipid optimisation trials. BG11 media was selected as the most appropriate media for the growth of the selected Chlorella and Scenedesmus strains. Little variation in growth was observed for both cultures ten days into cultivation under varying nitrate concentrations. Phosphate optimum was shown to be 0.032g/l for Scenedesmus sp and 0.04g/l for Chlorella sp. Best lipid yield determined during exponential growth was achieved in cultures with 0.3g/L to 0.6g/L nitrate and phosphate as per BG11 medium. pH optimisation showed that cultures may be adapted to growth at higher pH over time. The optimum pH range for growth was determined to be narrow and was found to be between pH 10 and pH 11. Chlorella sp. was shown to be sustainable as a dominant culture in open pond system. Open pond systems however are prone to contamination by other species of microalgae within weeks of inoculation. / National Research Foundation.

No description available.

No description available.

This thesis focuses on determining the potential of bio-energy crops to contribute to Europe’s future energy needs and to reduce future greenhouse gas emissions. This requires an end-to-end (seed to exhaust gas) analysis of the crop production and enabling technology in terms of energy use and greenhouse gas emissions. The starting point of this research was to consider which energy crops had the potential to grow in future European climate scenarios and to determine those for which models did not exist to make this prediction. <i>Miscanthus</i> was identified as a relatively new crop with 15 years of European growing experience but with limited previous model development.  MISCANMOD, a simple model of <i>Miscanthus</i> crop growth, was improved and rewritten in FORTRAN so that it could be interfaced to use climate scenario, soil property and land use data bases to predict energy yields for current and future climate scenarios. A greenhouse gas emissions and energy balance model was added to investigate the sustainability of <i>Miscanthus</i> as a bio-energy crop. This model was combined with data from other energy crop predictions to determine the energy yields and GHG mitigation of different crops for the various scenarios of future climate, each considering the soil conditions, land available and climatic conditions. We conclude that <i>Miscanthus</i> is the crop with the highest energy yield and largest carbon mitigation potential of all the available energy crops, and that the maximum amount of primary energy that could be produced by bio-energy crops in Europe would represent only 12% of EU 25’s primary energy needs. The carbon intensity of such energy is estimated to be 24% of that for gas. To achieve this level of energy production we show that it is necessary to develop drought and frost resistant hybrids to increase the range of the <i>Miscanthus</i> crop for current and future climate scenarios. This demonstrates that bio-energy is not a panacea but must be considered as part of the strategy to achieve sustainable energy whilst mitigating greenhouse gas emissions.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science 17th August 2015 in Johannesburg, South Africa / Ecosystem services provide a vital lifeline to millions of people living in rural areas. The poorest people in these areas depend upon the natural resource base in their surroundings to provide these services. With growing populations in rural areas of South Africa, the natural resource base is under considerable pressure; however, uncovering the dynamics of vegetation in these systems has proven difficult. While much attention has been given to savanna ecology, long term studies on the patterns and drivers of woody biomass are few. We used 65 years of aerial imagery (from 1944 to 2009) over 31 953 ha of rural savanna in a communal rangeland in South Africa to determine the abundance of woody canopy cover. This data were captured at hectare resolution, giving a fine enough level of detail for local level analysis. We also captured data for five potential drivers for change at this resolution, in order to analyse these drivers for their relative importance in determining woody canopy cover throughout the study period. Surprisingly, while individual sites showed varied trends in the amounts of woody canopy cover through time, when pooled across all sites the total woody canopy cover increased over the 65 year period. Disturbance gradients were found around some of the villages, but only in 2009, suggesting that the drivers of disturbance gradients in these systems may have only operated sufficiently to produce disturbance gradients in recent years. A hot spot analysis (hot spots indicate cells that have similarly high values beyond what would be expected in a random distribution, with cold spots indicating the inverse) revealed an increase in both hot and cold spots through time, but with a low persistence of both through time. High canopy cover cells are presumed to be the result of bush encroachment, while low canopy cover cells are presumed to be the result of harvesting of trees for fuelwood or clearing for fields. The low persistence of hot and cold spots points to a system in continual change, with patches of hot and cold spots appearing and disappearing, and therefore drivers of change operating in short periods of time. MAP (Mean Annual Precipitation), and not an anthropogenic driver, was found to be the most important driver for woody canopy cover throughout the study period, with MAP up to 670 mm having a predictable pattern of hot and cold spots through time. Higher MAP was shown to have a non-linear and unpredictable pattern of hot and cold spots through time, indicating that low precipitation may produce a system where woody canopy cover is less influenced by other drivers and is more stable when acted upon by other drivers. This research demonstrates the value of a long term dataset, and the applicability of our methods for monitoring woody canopy cover. As such, it may well serve as a baseline for woody canopy cover in communal savanna rangeland systems, with the methodology employed here suitable for an early warning detection system for sudden changes in the woody canopy cover.

Submitted to School of Chemical and Metallurgical Engineering, Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, South Africa June, 2016 / The main objective of this study is to produce biofuel from waste animal fat (collected from abattoirs) using the pyrolysis (thermal cracking) method. To achieve this goal, the study investigated the effects of temperature and heating rate on the yield and quality of the bio-oil produced. Also investigated was the effect of zeolite nano-catalyst(s) on the quality of the bio-oil produced. Animal waste fat (tallow) was pyrolyzed in a laboratory fixed bed reactor of volume 2200 cm3 at final temperatures (FT), 450oC, 500oC, 530oC and 580oC using heating rates (HR) of 4oC/min, 5oC/min and 6oC/min. The properties of the resultant bio-oils were tested and analyzed. The maximum bio-oil yield of 82.78 % was achieved at 530oC FT and 6oC /min HR while the highest calorific value, 52.41 MJ/kg, was recorded from the bio-oil produced at the FT of 580oC and 6oC/min HR. The molecular components of each of the bio-oil samples was analyzed using the Gas Chromatography – Molecular Spectrograph (GC-MS) which indicated the predominant presence of alkanes, alkenes, carboxylic acids and alkyl esters in the bio-oils produced without a catalyst. The introduction of zeolites in nano-form yielded relatively more cyclo-alkanes and aromatics. A maximum yield of 58% was recorded when 1% of the zeolite nano-catalyst was used to pyrolyse the tallow at 530oC FT and 6oC/min HR but with lots of coking and gas formation. The viscosity improved with a 35% reduction for the samples produced with 1% zeolites (C1 and C2). The viscosity of the bio-oil produced with 2% zeolites improved with a resultant 34% reduction in value. For pyrolysis done at 530oC FT and 6oC/min HR, the bio-oils with 1% (C1) and 2% zeolite (C3) resulted in a reduction in acid value of 32% and 30%, respectively. Acid value is the mass of potassium hydroxide (KOH) in milligrams that is required to neutralize one gram of chemical substance. / MT2016