For the past fifty years or so, there has been a great deal of interest in the use of water based explosion suppression systems, designed to mitigate or reduce the impact of thermal explosions and their consequential overpressures, which may be as high as 2MPa in outdoor environments. This level of interest has been heightened in more recent years due to a number of high loss explosion events including, Flixborough, UK (1974), Piper Alpha, North Sea (1998) and Buncefield, UK (2005). All of the previous research has focused on the suppression and mitigation proficiency of existing or new water deluge systems, which deploy sprays containing droplets 200≤D32≤1000μm. Where a high speed flame propagates through a region of spray containing such droplets, the flow ahead of the flame will hydrodynamically break up the droplets into fine mist, which in turn will act as a heat sink in the flame, with a resulting degree of suppression. These studies concluded that in most cases, existing deluge systems contributed to a global reduction in flame speed and thus caused a decrease in the resultant damaging overpressures. This present study however, is focused on the mitigation of slow moving deflagrations with resulting speeds of ≤30m/s. A flame travelling at such low relative speeds will not possess the inertia to inflict secondary atomisation by hydrodynamic break up. Consequently, the droplets within the spray must be small enough to extract heat in the short finite moments that the flame and droplets interact (approximately 0.03ms for a representative 1mm thick flame front). Previous theoretical studies have suggested that droplets, D32, in the order of 10μm - 20μm will be required to successfully mitigate combustion without relying on further droplet break up. To date, there have been no other published experimental studies in this area. An innovative high pressure atomiser known as a Spill Return Atomiser (SRA) was selected, which contained a unique swirl chamber and was originally developed for decontamination and disinfection. The efficient atomisation of the SRA produced fine sprays containing droplets, D32, 15μm - 20μm. A series of „cold trials‟ were conducted to further develop the single SRA, which manifested in the creation of several exclusive single and multiple spray options in counter, parallel and cross flow, with the direction of the propagating flame. These new configurations were supplied with deionised water at a liquid pressure of 13MPa and were qualitatively analysed using High Definition (HD) imagery and quantitatively characterised using non-intrusive laser techniques. During the development stages of this study the SRA spray cone angle was increased from 34.7˚ to 49.2˚and the exit orifice flow rate was raised from 0.295 L/min to 1.36 L/min. The increase in flow rate provided a number of spray options ranging from 17≤D32≤29μm, with liquid volume flux of 0.011 cm3/s/cm2 - 0.047cm3/s/cm2 and mean droplet velocity of 0m/s - 21.4m/s, with the resulting characteristics giving way to complete explosion mitigation qualities. The second phase of this study was to conceive, design and build a suitable apparatus capable of producing slow representative flame speeds within the range of 5 m/s - 30m/s. In excess of 250 mitigation „hot trials‟ were performed using the unique conformations produced during the „cold trials‟, whereby a configuration consisting of 4 x SRA‟s in cross flow (X/F) configuration, successfully and repeatedly, completely mitigated homogeneous methane-air mixtures throughout the whole flammable range E.R. 0.5≤(ϕ)1.0≤ 1.69 (5 - 15%), with flame speeds ranging from 5 - 30m/s. The combined spray configuration consisted of four SRA‟s which were 105mm apart and each opposed by 120˚, thus providing a total spray region of 315mm (spray centre to centre). As the sprays did not overlap or converge, the liquid volume flux remained as 0.047cm3/s/cm2. With droplets, D32, ≤30μm generally requiring impact velocities of approximately ≥142.83m/s to break up further, the flame speeds experienced in these trials of ≤30m/s would not have caused hydrodynamic break up of the droplets in the sprays. Therefore, due to the flame speeds and drop sizes utilised in this study, the droplets entering the flame front would have been in their original form. Although some comparisons were made using the experimental data with Computational Fluid Dynamics (CFD), it proved to be an extremely complicated phenomenon. This was due to the presence and interaction of the complexities of the combustion process and other variables such as water droplet dynamics and heat transfer modes. As such, a set of recommendations have therefore been proposed in pursuing this work in future projects.

[No abstract available] / Science, Faculty of / Botany, Department of / Graduate

This thesis focuses on issues surrounding energy regulation, and specifically regulation of pipelines that carry petroleum products in South Africa. The introduction of a regulator for petroleum pipelines is part of an ongoing process taking center stage in the South African government's petroleum industry policy arena. Independent regulation of energy industries is a recent phenomenon in South Africa. There is much activity in deciding which regulatory models should be adopted in the energy sector. The thesis analyses a government policy decision to introduce a regulator of petroleum pipelines. Among some of the key issues that receive attention are the following: • Is the petroleum pipeline industry in South Africa large enough to justify an independent regulator? • Do pipelines in South Africa enjoy monopoly rents? If they do, is the establishment of an independent regulator the most cost-effective way of dealing with monopoly rents? • How effective would such a regulator be in the current structure of the country's petroleum industry? Road and rail transport systems carry vast quantities of petroleum products. Would it be more appropriate for the regulator to include all transporters of petroleum products? The thesis concludes that for an industry of such small size as pipeline transportation in South Africa, the necessity of a pipeline regulator might need to be reviewed. For a variety of reasons, there are strong reasons to conclude that a pipeline regulator will have minimum impact over key issues of the transportation of petroleum products.

Includes bibliographical references. / The effect of energy on inequality and poverty is not well understood and its role in growth-inequality-poverty nexus has not been adequately studied. A country's energy mix can playa significant role in economic growth and poverty alleviation. Policy authorities and donors increasingly lend support to modem energy provision, especially Rural Electrification (RE). This thesis investigates which energy types contribute to poverty alleviation in South Africa and through what mechanisms. Theory indicates that poverty alleviation comes by growth boosting and inequality reducing policies. As such, the investigation of the pro-poor effects of any policy or factor would naturally culminate in studying the effects on economic growth (or production) and income distribution. Theory suggests endogeneity on one hand between energy and GDP and on the other between GDP and inequality. This necessitates a system of equations rather than the traditional single equations approach. There are other (South Africa-specific) reasons why the inequality-development relationship and the role of energy should be investigated. First, South Africa has been under-researched due to lack of data. Recent data released by the Presidency of South Africa (AMPS Dataset) makes such analysis possible. Secondly, the Kuznets' inequalitydevelopment hypothesis can be tested with time series data rather than the cross-section analyses found in earlier literature. Third, energy's role in economic growth or production has been analysed with aggregate energy measures and aggregate GDP. This work argues that such an approach will mask energy type-specific and sector-specific details and undertakes a more disaggregated analysis. Fourth, the multiracial nature of South Africa requires sub-group decomposed inequality rather than national aggregates.

The purpose of this study is to analyse the development of South Africa's liquid fuels industry from 1930s to the present and the various ways in which the state has extended subsidies and other measures of support to liquid fuels producers. The nature and extent of government support to the South African liquid fuels industry has remained hidden for many years, due to the veil of secrecy surrounding the industry prior to the country's transition to democracy. The study expands past analyses to identify and estimate the magnitude of subsidies to liquid fuels production in South Africa in the present. Using the historical institutional approach, the study then places these measures of support in the South African political economy environment so as to understand the institutional barriers to their reform. In doing so, the study sheds light on the drivers informing the endurance of the liquid fuels subsidy regime and state support to the liquid fuels industry following the transition to democracy.

Includes bibliographical references. / This study looks at possible improvements of energy efficiency in the iron and steel industry in Zimbabwe and the case of South Africa is studied also for comparison. Data required was obtained through field visits and international databases. The fieldwork findings, analysis and published literature contributed to the conclusions and recommendations. There is a relationship between technology advancement, energy efficiency and energy intensity. The more modern technology a country's steel industry adopts the more energy efficient it becomes and so lowers its energy intensity. Countries such as South Korea, Japan and Germany have adopted modern technologies and they are among the most efficient steel producers and have the lowest energy intensities while India and China have low levels of modern technologies, low efficiencies and high intensities. ZISCO, the iron and steel industry of Zimbabwe has a relatively high energy intensity (closer to China and India) compared to South Africa and other developing country producers. ZISCO has both new and old technology while industry in South Africa, which has retired most old technology and closed all its less efficient plants, is largely using new and even state of the art technology in some of its plants. In Zimbabwe the national economic and industrial policies have had negative impacts on the growth and development of its iron and steel industry. ZISCO needs policies that support the adoption of energy efficient technology, create a level playing field for downstream steel industries since ZISCO has the potential to influence growth of this sector and the sector has prospects for significant foreign currency earnings. The study recommends a restructuring of ZISCO to improve productivity, and energy efficiency through replacement of old technologies in the medium to long term and implementation of some identified less capital-intensive options that are typical in an integrated steel mill.

The industrial sector is the main energy user in South Africa, using about half the national total, and compared to most other industrialised countries South Africa has a high in_dustrial energy intensity, thus necessitating improved industrial energy management. The malt brewing industry was chosen as a case study industry to illustrate the potential for improved energy management in industry. Ohlsson's brewery in Cape Town was analysed in detail and energy management improvements identified for that brewery were ·expanded to include the malt brewing industry in general, by comparing Ohlsson's brewery to other breweries in South Africa. It was found that energy requirements at Ohlsson's Brewery could be reduced by 12-20%, by the implementation of economically feasible energy management schemes. However, mainly because of discrepancies in coal prices between Ohlsson's Brewery and most other breweries in South Africa, energy requirements for the brewing industry in general can be reduced by 7-13%. This translates to be a monetary saving of R242 000-R486 000/month, which is evenly spread between coal, electricity, and maximum demand savings. No single large energy saving scheme was identified, but the potential. savings are due to a number of schemes. The potential energy savings identified in this study exclude the savings as a result of the implementation of process sensitive schemes, which were considered beyond the scope of this study. Nevertheless some process sensitive schemes, associated with boiling in the brewhouse, could result in substantial savings. The energy usage target identified for South African breweries is higher than current energy requiiements for breweries in the Britain and Germany when climatic and operational constraints are taken into account. This is because Britain and Germany have higher energy costs relative to production costs, government incentive schemes for reducing energy usage, and more stringent environmental legislation often necessitating the recovery of brewhouse vapours.

Includes bibliographical references (leaves 132-135). / Integrated resource planning aims to fulfil electricity requirements with supply and demand resources. Least cost resources are optimised as supply expansions compete with measures to modify the load in meeting energy services. A demand side study is conducted to determine representative load profiles for electricity use within South Africa. Analysis of electricity consumption us in g load profiles of each sector ' s end-use electrical loads is essential for determining the appropriate supply technologies as well as the impact of demand side management and energy efficiency measures . A supply side study considers all existing and future power generation options required for expected electricity growth and system load characteristics. Energy model, TIMES, provides time-slices for adequate load profile representation TIMES is a Partial Dynamic Equilibrium Model as constraints are placed on the investment, usage and availability of technologies. All optimisations are for the least cost to the system. Demand and supply options are integrated into a single plan using the TIMES model and the supply expansion plan is changed when demand reduction targets are achieved using DSM and EE. The base case us in g a business-as-usual approach is compared with a low and medium impact DSM and EE scenario. Demand resources are estimated from the industrial, commercial and residential economic sectors. The scope of the plan is 22 years and there is full utilisation of all existing supply capacity with small amounts of decommissioning. Mothballed power stations are recommissioned initially. Peak-load plants are needed from 2007 and OCGT are selected using natural gas or LNG. Intermediate-load capacity is needed by 2011 using CCGT. Base-load capacity demands are met using new coal PF power stations in 2014. FBC stations using discard coal begin operation in 2016. The capacity expansion plan anticipates 2. 93GW of OCGT, 2.5 GW of CCGT, 7. 2GW of coal PF, 2. 8 GW of FBC plants and 2 GW of pump storage stations to be in use by 2020. Imported hydroelectric capacity of0.9 G W and PBMR capacity of3 GW is expected to be commissioned by 2024. Approximately 4 % less installed capacity is needed when a medium impact DSM and EE strategy is implemented. The marginal cost of energy gradually increases from 0. 06 R/kWh in 2002 to 0. 175 R/kWh in 2016 and to 0.325 R/kWh in 2024 as supply capacity is added. Compound load profiles from all national electricity usage provide an effective means whereby appropriate supply technologies are selected whilst incorporating load modifications due to DSM and EE.

Energy use is the human activity responsible for the majority of its greenhouse gas emissions. In 2010 the global energy-related emissions of carbon dioxide - the principal greenhouse gas-jumped by 5.3% from the previous year, to a record 30.4 gigatonnes (IEA 2011a). The International Energy Agency (2011) has projected that the world's primary energy demand could increase by 33% and that energy related CO2 emissions will increase by 20% to 36.4 Gt between 2010 and 2035 (IEA 2011a). South Africa is one of the most energy intensive countries in the world, measured as GHG emissions per Gross Domestic Product produced. South Africa's energy intensiveness is a result of the energy intensive nature of a number of its key industries. The mineral industry is one such industry. It plays a crucial role in South Africa's economy and is the largest industry in its primary economic sector (Chamber of Mines 2010). Energy efficiency has been identified as one of the cheapest and most effective measures to reduce energy consumption and its associated greenhouse gas emissions. The Long Term Mitigation Scenarios coordinated by the University of Cape Town's Energy Research Centre identified that South Africa's industrial sector had cumulatively the greatest potential to reduce its GHG emissions through improved energy efficiency, ahead of the commercial, residential or transport sectors(Winkler 2007). South Africa's continued reliance on unsustainable energy production, particularly coal, increases the need for maximising energy efficiency to mitigate resource consumption and the GHG emissions associated with the production and use of fossil fuel generated energy. This project aims to identify and holistically evaluate the potential opportunities that exist for the reduction of energy and climate footprints of South Africa's gold industry sub-sector, with the aim of providing guidance to both government and industry for a path towards a more energy efficient industry with lower associated GHG emissions. To this end the thesis begins with a comprehensive review of the potential drivers, barriers and opportunities for increased EE and GHG emissions mitigation for the local minerals industry.

Energy is an essential requirement for a reasonable socio economic development in a country; however, its provision depends on availability of energy sources and the require d investment. Nigeria possesses abundant deposits of energy sources ranging from fossil fuel to renewable energy sources. Over the years, the level of production of energy from these sources has been considerably low. The present level of electricity supply is short of demand and the supply is not reliable. As the country is experiencing rapid growth in population, adequate energy provision is necessary for corresponding level of production and development. The need for sustainable and renewable sources of energy has emerged globally owing to environmental issues associated with the use of conventional fuel. In order to consider the possibility of harnessing the solar energy resource in northern Nigeria, this study explores the potential contribution of the adoption of Concentrated Solar Power (CSP) technology to the energy system in the far northern States of Nigeria. These States are chosen because the region lies within a high sunshine belt and thus having a daily average DNI of 6.2 KWh/m2 / day and an annual average of 2320 KWh/m2/yr. The annual average DNI in the region is a bit higher than that of the Andasol CSP plant in Spain which is 2090 KWh/m2/yr. The thesis seeks to uncover the potential for CSP in Nigeria, and determine when the cost of energy from CSP will become competitive with the cost of energy from conventional power. Using three possible economic growth scenarios (reference (7%), high (10%) and optimistic (13%) economic growth scenarios) to model future energy demand and supply from CSP and conventional gas plant. The results obtained show possible competition from potential CSP plant in Nigeria depending on the international and domestic gas market. However, continuous payment of blanket subsidy on the domestic price of natural gas in Nigeria will adversely affect potential investment in CSP market in Nigeria.