Please read the abstract in the section 00front of this document / Dissertation (MEng (Electrical Engineering))--University of Pretoria, 2006. / Electrical, Electronic and Computer Engineering / unrestricted

Since 1994, with many of its sanctions lifted, South Africa became a stronger economic power house in Africa leading the continent‘s industrial output and mineral production and generating a large proportion of Africa‘s electricity. The South African economy has since been growing at a fast pace which has also led to an increase in the demand for electricity. South Africa‘s generating capacity has remained constant through a consistently increasing demand, leading to an electricity shortfall. An immediate threat to South Africa‘s continued economic growth is a capacity constraint in terms of energy supply. Increasing economic growth coupled with the rapid industrialisation and mass electrification programme of the last decade, as well as planned and unplanned maintenance and coal stock pile problems led, in January 2008, to demand out stripping supply. With electricity being an important component of economic development, it is vital that the impact of the supply of electricity on the economic growth of the country be well understood. Currently few studies have been done on the analysis of this relationship in South Africa specifically and how this relationship impacts specific sectors of the economy that contributes to the total GDP of the country. This study has assumed rigorous application of Granger technique with proper statistical verification of assumptions, selection of relevant variables and provides trusted statistical forecasts. In an attempt to understand this relationship, an Econometric model has been developed to assess the impact of electricity supply and price on the economic growth of South Africa. In the empirical analysis section of this study it was found that with a forecast for GDP, past values of electricity prices and coal sales may be used to forecast electricity supply. It was also found that if we have a forecast value of future electricity price we can use past values of electricity supply and coal sales to forecast GDP for the next quarter. We also found that electricity supply is granger caused by GDP; electricity price; and total coal sales. And that economic growth is granger caused by electricity supply; electricity price; and total coal sales. It was concluded that in order for government to improve the economic growth of South Africa, a major focus on the energy industry is needed to ensure sustainable supply capacity. The energy sector, as was shown in the study, has a major impact in the functioning of the Gross Domestic Product of the country.

Energy poverty is a concept that has gained significance quite recently. Its significance has been prompted by the realization that without sustainable modern energy alternatives for the rural poor, prospects for rural transformation remains low. The recognition of modern energy as one of the missing link in rural transformation comes amid the growing concern about the negative effects of relying on traditional energy services and the increasing forecasts that most developing countries are likely to miss their MDG targets by 2015. Drawing on the Modernization and the Sustainable Development Approach, this study concluded that improving the quantity and quality of energy services consumed by the rural poor can counteract rural underdevelopment and enhance rural social and economic transformation in Dewedzo. The study confirmed that energy poor households are prone to various social, economic and environmental detriments such as poor health, hunger, malnutrition, poor education and missed socio economic opportunities. By addressing rural people‟s energy needs, more nexus can be injected into rural productivity and the economic social outputs of this process can in turn increase the pace at which MDGs can be achieved.

The development of technologies and structures providing energy for household use in South Africa have for many years been dominated by the needs of "white" households. While these needs have been comprehensively met through cheap and efficient energy supplies, the needs of those in the "homelands" and townships have effectively been ignored. Thus, for roughly two-thirds of the population in South Africa, the struggle to meet basic energy needs for cooking, water heating, space heating and lighting is time consuming and expensive. The planning of a national energy strategy for the future can no longer overlook the energy needs of underdeveloped areas. While the immense task of building institutions and techniques for providing all with adequate and affordable energy supplies will require substantial technical intervention and a large amount of capital, ignoring these problems will incur even greater political, social and environmental costs. Interest in the field of energy for underdeveloped areas has been increasing in recent years, and has led to research on various appropriate energy technologies and the highlighting of energy problems in various locations. However, there has been no overview of experience to date, nor any comparative assessment of these technologies and their potential role in an energy supply strategy. By drawing together the body of research into one publication, this thesis hopes to provide an overview, to allow different energy technologies and supply options to be assessed and compared, and to provide a starting point for debate on suitable energy strategies for underdeveloped areas.

Bibliography: leaves 273-276. / The thematic focus of this dissertation is the specificity of user requirements for domestic energy applications in informal urban settlements and how these are fashioned by the contextual pre-conditions of poverty and instability. The fieldwork focused on a group of people who can be defined by the facts that they are people who house themselves, possibly fall into the lowest or no income sector of the population, are peripheral to the mainstream economic activity in the country and are temporary or permanent or roving urbanites. The research approach is done from the viewpoint that user requirements should inform the design of systems for domestic energy applications and that these subjective requirements constitute the correct point of departure from which to evaluate the efficacy of energy support services. The bulk of this dissertation consists of recounts of research interviews, illustrating some aspects of user requirements. These are presented as 'primary data' with the purpose of rendering the research more transparent and of feeing an information resource with the option of re-interpretation by the reader. The dissertation concludes that appropriate energy services will have to be characterised by adaptability and diversity as well as by sensitive responses to the micro networks of urban subsistence household economies.

Air pollution is the world’s greatest environmental health risk factor and reducing exposure remains an ongoing challenge around the world. Among the world’s poor, marginalized, and rural populations, household air pollution from the inefficient burning of biomass fuels like firewood, charcoal, dung, and agricultural residues for daily household energy needs is a leading cause of morbidity and mortality, especially for children under the age of five years. However, household air pollution exposure is a modifiable risk factor and clean-burning cooking fuels like gas and electricity promise substantial health benefits for the 2.8 billion people reliant on biomass fuels. But, clean fuels remain prohibitively expensive or inaccessible for those most reliant on biomass fuels. It is in this context that I examine Ecuador – where substantial cooking gas subsidies have facilitated a nationwide transition to household clean fuel use over four decades – as a long-term case study to understand the potential for widespread clean fuel uptake to reduce air pollution exposure and improve children’s health. Chapter 1 provides background information that contextualizes the work presented in this dissertation. In Chapter 2, I discuss the development of Ecuador’s clean fuel policies. Originally established as a part of broad social support reforms in the 1970s, direct-to-consumer subsidies that lowered the cost of liquefied petroleum gas (LPG) – a popular clean-burning cooking fuel used widely around the world – have driven a transition from 80% of households cooking primarily with firewood in the 1970s to now 90% relying primarily on LPG. However, widespread clean fuel use has come at a cost; each year, the Government of Ecuador spends approximately 1% of the national growth domestic product subsidizing LPG (300-700 million USD). To reduce this financial burden, the government has offered incentives to households to install and use induction electric stoves, which can be powered by the nation’s growing hydroelectric capacity, thereby reducing the cost of LPG subsidies and greenhouse gas emissions. To supplement national data, I administered household energy surveys in a northern province, finding that while all households regularly used LPG, 80% still used firewood for cooking. In these remote regions along the Colombian border, limited access to LPG cylinder refills remains a significant barrier to exclusive LPG use, even after decades of building a robust distribution system. In Chapter 3, I describe results from tailored household surveys – covering energy end uses, costs and access to fuels, and fuel use preferences – administered in 808 households across coastal and Andean Ecuador. Nearly all participants reported using LPG for more than a decade and having frequent, convenient access to cheap LPG cylinder refills. Nonetheless, half of rural households and one-fifth of peri-urban households relied on firewood for cooking and to meet specific household energy needs, like space heating or heating water for bathing. Induction stoves were rare and many induction stove owners reported zero use because the required equipment had never been installed by electricity companies, their stove had broken, or they feared high electricity costs. Here, I show that nationally-representative surveys reporting only “primary cooking fuel” use may underestimate solid fuel use as a secondary option, particularly in rural areas where LPG fuel availability issues play an important role in cooking fuel decision making. These findings additionally indicate that persistent biomass use may curtail the benefits from even the most aggressive clean fuel policies and suggest that additional targeted interventions may be needed to more fully displace biomass. Furthermore, they highlight the need for more nuanced nationally- and subnationally-representative surveys to better understand the extent to which biomass fuels are used secondary to LPG throughout all regions of Ecuador. In Chapter 4, I present results from a sensor monitoring study where we measured personal PM2.5 exposure and stove use for 48-hour monitoring periods among 157 households in peri- urban and rural Ecuador. Firewood-using participants had higher distributions of 48-hour and 10-minute PM2.5 exposure as compared with primary LPG and induction stove users. Accounting for within-subject clustering, contemporaneous firewood stove use was associated with 101 μg/m3 higher 10-min PM2.5 exposure (95% confidence interval: 94–108 μg/m3). Cooking events with clean fuels were not associated with contemporaneous increases in PM2.5 exposure. These findings confirm our expectations that in a region with low ambient air pollution, long-term cooking gas subsidies can lead to relatively low personal air pollution exposures. And yet, persistent secondary firewood use led to higher average and peak exposures, further motivating the displacement of firewood use to reduce health risks from air pollution. I also outline the methodological challenges faced in combining time-resolved sensor data on participant location, stove use monitors, and PM2.5 concentration and offered advice for future studies. In Chapter 5, I assess whether Ecuador’s increased clean cooking fuel use has resulted in improvements in under-5 lower respiratory infection (LRI) mortality. Globally, LRIs are the leading cause of death for children under-5 and household air pollution exposure is a leading risk factor. I employ public use data on cooking fuel use and cause-coded mortalities from 1990 to 2019 to estimate the association between clean cooking fuel use and the rate of under-5 LRI mortalities at the canton (county) level in Ecuador. Using generalized additive mixed models with fixed effects for canton and study period, I observed a significant, non-linear negative association providing evidence that when more than 60% of households in a canton cook primarily with a clean fuel, increased clean fuel use is associated with reductions in under-5 LRI mortality. In total, I estimated that increased clean cooking fuel use is associated with 7,343 under-5 LRI mortalities averted since 1990. In Chapter 6, I conclude by discussing the broader implications of my work. Energy is an important thread connecting climate change, air pollution, and human health, and pathways towards cleaner energy generation will be important drivers of climate change mitigation, reduced environmental exposures, and improved population health. Investments in clean cookstoves have had mixed results over the last 40 years, with many studies revealing only limited uptake of intervention stoves and substantial continued use of polluting traditional fuels, resulting in lower-than-expected exposure reductions and health benefits. Ecuador’s transition has been remarkable in the context of its peer low- and middle-income countries in the rest of Latin America and beyond. The findings presented in this dissertation demonstrate that cooking gas is popular; when it is made cheap and available, gas significantly displaces the use of polluting fuels. Nevertheless, even under ideal cost and access circumstances, my work also reveals that policies and interventions will need to consider specific local needs – like space heating in cold climates – to further encourage a transition toward cleaner indoor air. In the context of efforts to eliminate the use of polluting fuels in the Americas, my work offers hope that ambitious clean cooking fuel policies will improve health.

Thesis (M. Com. (Accounting)) -- University of Limpopo, 2021 / Since 2008, South Africa has been experiencing significant bottlenecks in its energy supply. The transition to renewable energy is no longer just an option but a necessity. In demonstrating the commitment to the Kyoto Protocol, which requires a reduction in greenhouse gases and is a response to the electricity crisis, various mechanisms have been applied to stimulate renewable energy production. This study examines the effect of the influencing factors and enablers on renewable energy generation in selected developing countries. To this end, the study investigated if the amount invested in renewable energy, economic, governance, environmental and social factors have an impact on renewable energy output produced in the selected emerging economies. Secondary data which comprised of the renewable energy output, investment and proxy data for the other factors being tested was used in the investigation. A quantitative research design was used, and panel data for the periods 2000-2016 was analysed. Results of the study revealed that the renewable energy generation is impacted diversely by the elements tested. A positive causal link was found between the dollar amount invested and the production of renewable energy. Additionally, the study found that governance, economic, environmental, and social factors can influence renewable energy output favourably or unfavourably. Results of the study suggest that policymakers should consider the effect of these variables when formulating policies to accelerate the transition to a sustainable energy supply system. Furthermore, the results provide possible solutions for budgetary constraints which have limited the transformation of the energy industries in the selected developing countries. Potential to investigate this study further on a country by country basis as data becomes available exists. Additionally, mixed methods may be applied to explore a qualitative element in the study. Keywords: Renewable Energy, Non-renewable energy, Green energy

In the past decade, research in the field of singlet fission, the process in which one high energy singlet fission exciton forms two lower energy triplet excitons, has seen a resurgence as a process that has the potential to improve solar energy conversion efficiency and contribute to a push for renewable energy. While an impressive motivation, there is still much progress in terms of understanding the physics of the process as well as improving molecular design for actual applications that needs to be made before this motivation can be fully realized. Two significant current hurdles in this field are the extraction of the newly formed triplet excitons from their entangled triplet pair state before recombination, and the lack of stable chromophores with viable energetics for singlet fission and high triplet energies for application purposes. Over the past five years, we have addressed these issues with targeted molecular design. Only a couple of studies have successfully separated the triplet pair state in intramolecular singlet fission systems. We create an intramolecular singlet fission system, a PDI-pentacene-pentacene-PDI tetramer, in which a charge transfer state is utilized to separate an electronically entangled triplet pair. We have also shown that singlet fission can be controlled as well as actually induced in chromophores by employing molecular contortion to tune the energetics. With this work, we have contributed to the motivation of using singlet fission in real-life applications.

Includes bibliography. / A proposal to develop the Upper Tugela Location in KwaZulu, Natal, prompted this study. This study aims to investigate the means to enhance the availability of, and access to, affordable energy sources in the Upper Tugela Location. A further aim is to match appropriate energy sources with the socio-economic conditions prevailing there. The Upper Tugela Location is an ecologically sensitive area of the Upper Tugela catchment. Rural energy planning has been criticized for the development of energy-conversion technologies while there is insufficient understanding of energy procurement practices in rural subsistence economies in South Africa. Qualitative information gained from a questionnaire survey, informal group discussions and direct observations suggest that the inhabitants of the Upper Tugela Location are relatively poor. For this reason a basic rural energy needs approach, which attempts to address the needs of the poorest, has been adopted to provide a theoretical base for the study. Research has revealed the following. Wood is the dominant energy source in the Upper Tugela Location. It is estimated that the annual household consumption of fuelwood is 3000 kg which is below the average fuelwood consumption for a rural area in South Africa. This reflects that this resource is being depleted to the degree that the local inhabitants are supplementing their use of fuelwood with expensive commercial fuels such as coal and paraffin. Locally available wood is in short supply, particularly in densely populated areas of the Upper Tugela Location. Most people are buying fuelwood from Natal farmers living on the borders of the study area. This results in an economic leakage from the Upper Tugela Location and dependence on extralocally available sources of energy. There appear to be few attempts to establish woodlots at present in the Upper Tugela Location. Equitable access to local supplies of wood are curtailed. Renewable sources of energy such as thermal and photovoltaic solar energy, micro-hydro and wind generated power, and afforestation have been investigated as have non-renewable sources of energy such as grid electricity and commercial fuels. It is concluded that no single technical option adequately addresses the energy needs of the inhabitants of the Upper Tugela Location. Most of the renewable sources of energy, except wood, are too expensive for subsistence economies and can be unreliable as they are still at the developmental stage. It is recommended that electricity from the national grid should be made available to those who can afford it. The means to improving the distribution of commercial fuels in the Upper Tugela Location should be addressed. Woody biomass management and agroforestry programmes provide the best options for an energy strategy for the Upper Tugela Location as they are inexpensive, require little maintenance, are sustainable and reliable, and serve conservation requirements at the same time.

Improving the functioning and the safety of the electrical grids is a topic of great concern, given its magnitude and importance in today's world. In this thesis, we focus in these two subjects. In the first part, we study undetectable cyber-physical attacks on power grids, which are attacks that involve physical disruptions, including tripping lines and load modifications, and sensor output alterations. We propose a sophisticated attack model described under the full Alternating Current (AC) power flow equations and show its feasibility on large grids from a test cases library. As counter-measures, we propose different defensive strategies that the network's controller can apply under a suspected cyber attack. These are random, simple and fast procedures that change the voltages across the network and aim to unmask the current status of the system, assuming that the attacker cannot react against their randomness. Secondly, with access to data collected through Phasor Measurement Units (PMUs) by a power utility in the United States, we perform statistical analyses on the frequency and voltage time series that have been recorded at a rate of 30 Hz. We focus on intervals of time where the sampled data shows to be in steady-state conditions and, with the use of appropriate signal processing filters, we are able to extract hidden anomalies such as spatio-temporal correlations between sensors and harmonic distortions.