Thesis (Ph. D.)--University of South Carolina, 2004. / Includes bibliographical references (leaves 302-319).

Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2015. / From the electric power generation perspective, the last three decades have been characterized by sustained growth in the amount of Distributed Power Generation (DPG) systems integrated into the electric grid. This trend is anticipated to continue, especially in light of the widespread acceptance of the many benefits envisaged in the increase of renewable-based power generation. The potential for grid-integrated DPG systems to significantly contribute to electric power supply reliability has consistently attracted extensive research in recent times, although concerns continue to be raised over their adverse impact on the normal grid operation at high penetration levels. These concerns largely stem from the limited controllability of most DPG systems, which tend to exhibit large output impedance variation, and non-deterministic power output characteristics. There has therefore also been a growing need to develop effective control strategies that can enhance the overall impact of the DPG systems on the grid operation, thus improving their synergistic properties, and probably also enabling an even higher penetration level into the utility grid. In line with this identified need, this thesis discusses the modeling and controller design for an inverter-based DPG system with the capability to effectively operate both in grid-connected and autonomous (i.e. independent of the utility grid) operational modes. The dual-mode operation of the DPG is made possible by incorporating into the inverter interface control scheme the means to ensure seamless transition of the DPG between the grid-connected and autonomous modes of operation. The intention is to have a grid-integrated inverter-based DPG system whose operation approximates that of an online Uninterruptible Power Supply (UPS) system, in that it is able to sustain power supply to the local load in the absence of the grid supply, which would be desirable for critical loads, for which the level of power supply reliability guaranteed by the grid often falls short of the requirements. The work developed in this thesis considers three of the aspects associated with grid-integrated DPG systems that are equipped with autonomous-mode operation capability.

Thesis (DTech (Engineering))--Cape Peninsula University of Technology, 2017. / The world has been experiencing energy-related problems following pressuring energy demands which go along with the global economy growth. These problems can be phrased in three paradoxical statements: Firstly, in spite of a massive and costless solar energy, global unprecedented energy crisis has prevailed, resulting in skyrocketing costs. Secondly, though the sun releases a clean energy, yet conventional plants are mainly being run on unclean energy sources despite their part in the climate changes and global warming. Thirdly, while a negligible percentage of the solar energy is used for power generation purposes, it is not optimally exploited since more than its half is wasted in the form of heat which contributes to lowering efficiency of solar cells and causes their premature degradation and anticipated ageing. The research is geared at addressing the issue related to unsatisfactory efficiencies and anticipated ageing of solar modules. The methodology adopted to achieve the research aim consisted of a literature survey which in turn inspired the devising of a high-efficiency novel thermal electric solar power panel. Through an in-depth overview, the literature survey outlined the rationale of the research interest, factors affecting the performance of PVs as well as existing strategies towards addressing spotted shortcomings. While photovoltaic (PV) panels could be identified as the most reliable platform for sunlight-to-electricity conversion, they exhibit a shortcoming in terms of following the sun so as to maximize exposure to sunlight which negatively affects PVs’ efficiencies in one hand. On the other hand, the inability of solar cells to reflect the unusable heat energy present in the sunlight poses as a lifespan threat. Strategies and techniques in place to track the sun and keep PVs in nominal operational temperatures were therefore reviewed.

Orientador: Jose Antonio Scaramucci / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-11T01:35:40Z (GMT). No. of bitstreams: 1 Medeiros_HerculesSouzade_M.pdf: 1050002 bytes, checksum: 6523a6c9f246b9abc2c8e9a17d70a0fc (MD5) Previous issue date: 2007 / Resumo: Nos últimos anos o gás natural vem despontando como uma alternativa energética viável para a economia brasileira, o que tem despertado grande interesse por parte de diversos agentes públicos e privados que atuam no setor de energia. Porém, sua inserção na matriz energética nacional não está ocorrendo de maneira eficaz e no ritmo desejado. Novos empreendimentos que utilizam o gás natural estão surgindo em todos os segmentos, quer seja em função das necessidades econômicas ou em função do apelo ambiental. A inserção do gás natural é uma realidade, mas a ausência de políticas concretas põe em risco o seu desenvolvimento de longo prazo. Assim, este trabalho procura permear todos os aspectos relativos à inserção do gás natural no Brasil e os impactos resultantes nas emissões de CO2, na matriz energética e na economia nacional. A metodologia escolhida para apoiar as análises foi a decomposição por índices. O objetivo é determinar os impactos do gás natural nas emissões de dióxido de carbono e fatores relevantes tais como, a dinâmica econômica, composição setorial e eficiência energética. Ainda sob o aspecto das análises, foram comparados possíveis cenários e, também, aplicações da mesma metodologia em países que possuem economias relativamente semelhantes à brasileira. Os resultados obtidos mostraram a consistência do modelo e, trouxeram importantes contribuições para o desenvolvimento de políticas para o gás natural entre os cenários avaliados. Resultados adicionais evidenciaram a importância futura deste, demonstrando assim, a necessidade de dar continuidade às análises para o desenvolvimento sustentável brasileiro / Abstract: In the last years, natural gas has unfolded as a feasible energy alternative for the Brazilian economy, attracting great interest from several major market players. However, its insertion in the energy sector has not been occurring in a consistent way and at the expected pace. New prospects for natural gas projects are appearing in all market segments due to growing economic needs and its environmental appeal. The insertion of natural gas is a reality, but the lack of concrete policies jeopardizes its long term development. This work aims at investigating different views related to the issue of natural gas introduction in Brazil and the resulting impacts on CO2 emissions, the energy sector and the national economy. The index decomposition analysis (IDA) methodology was chosen to conduct the study. The objective is to determine the impacts of natural gas on carbon dioxide emissions, through its significant explanatory factors, such as economical dynamics, sector composition and energy efficiency. Possible scenarios were compared. Also, applications of the same methodology in countries with similar economies are reported. The results obtained showed the model assertiveness and, also, brought important contributions for development of natural gas market policies among the scenarios considered here. Additional results indicate the importance of natural gas for Brazil, in particular for its economic and environmental future, as a means to achieve sustainable development / Mestrado / Energia, Sociedade e Meio Ambiente / Mestre em Engenharia Mecânica

Orientador: Silvia Azucena Nebra de Perez / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-20T12:24:18Z (GMT). No. of bitstreams: 1 GonzalesPalomino_Raul_D.pdf: 6830168 bytes, checksum: 3e74d7ae4f032a2a7aa3b78e9358cca1 (MD5) Previous issue date: 2012 / Resumo: Nos últimos anos, várias discussões e análises sobre um maior uso de gás natural no Peru foram realizadas. No início de 2011, durante os debates presidenciais, este era um item da agenda, e a priorização do desenvolvimento do mercado interno de gás, em vez de sua exportação foi o tema central. A presente tese analisa as alternativas de uso do gás natural nos setores de transporte, residencial, terciário, industrial de grande porte e de geração elétrica no Peru, assim como avalia o impacto da sua penetração na substituição de combustíveis derivados do petróleo e a possibilidade de produção de eletricidade através da cogeração. Para tanto, foram efetuadas uma análise da matriz energética peruana, uma revisão das reservas e infraestrutura da indústria do gás natural, para uma avaliação complementar e como ferramenta de comparação foram calculados os indicadores de sustentabilidade energética do País. Além disso, foi realizada uma revisão das metodologias existentes e empregadas para este tipo de estudo, além de definidos a abrangência e os cenários deste trabalho. Dos cenários avaliados, o tendencial- moderado seria o mais provável de acontecer e se viabilizar. Este mostra que o uso do gás natural aumentará de 3.280 Mm3, em 2008, para 6.295 Mm3, em 2020, melhorando, assim, a distribuição de sua utilização nos diferentes setores analisados, não sendo utilizado majoritariamente no setor de geração elétrica, como ocorre na atualidade. Por outro lado, a maior penetração deste energético permitirá substituir combustíveis derivados do petróleo, como o óleo Diesel, óleo combustível, gasolina e GLP, e, consequentemente, reduzir as emissões de dióxido de carbono. Os resultados mostram a existência de reservas para um maior desenvolvimento do mercado interno do gás natural no curto e médio prazo, mas, no futuro, é necessário continuar avaliando as reservas e o uso do gás (incluindo a exportação), considerando a garantia de seu fornecimento no longo prazo, descobertas de reservas e novos projetos para sua utilização / Abstract: In recent years there have been several discussions and analysis on a greater use of natural gas in Peru. This was part of the agenda during the presidential debates in early 2011. During these debates, the importance of developing a domestic demand for natural gas rather than gas exports was the central theme of discussion. This thesis analyzes the alternative for the use of natural gas in sectors such as transportation, residential, commercial, large-sized industry and power generation in Peru. Moreover, it evaluates the impact of its penetration as a replacement for oil products and the possibility of production of electricity through cogeneration. For this, an analysis on the Peru's energy matrix was conducted. Also, the current reserves and infrastructure of the natural gas industry were shown and additionally as a tool for comparison were calculated energy indicators for sustainable development in the country. In addition, a review of existing and used methodologies for this type of study were performed, and the scope and scenarios of this work were defined. The moderate trend scenario would be more feasible and likely to occur in comparison to all the scenarios evaluated in this study. This scenario shows that the use of natural gas will increase from 3.280 Mm3 in 2008 to 6295 Mm3 in 2020, which will improve the distribution of it in the different sectors that were analyzed, and reduce its use in the power generation sector where natural gas is mainly being utilized as of today. The greater penetration of natural gas would reduce the use of oil products such as Diesel oil, residual oil, gasoline and LPG, and thereby reduce CO2 emissions. The results show the existence of reserves for further development in the domestic gas market in the short and medium term, but in the future it will be necessary to continue evaluating the reserves and consumption of the natural gas in order to guarantee its supply for the long term, the discovery of new reserves, and the development of new projects for its use / Doutorado / Planejamento de Sistemas Energeticos / Doutor em Planejamento de Sistemas Energéticos

D.Phil. / Global society has evolved into a complex multi-dimensional system in which it has become increasingly difficult to construct and maintain a systemic model of cause and effect. Specialisation and abstraction in the various disciplines of scientific and societal complexity has led to divergent theories of sustainability. Failure to integrate real life problems across disciplines poses a threat to modern society because the causal links between disciplines are unattended in many instances and events in one dimension could lead to catastrophic unintended consequences in another. In light of the above, this thesis contributes towards the multi-disciplinary integration of some of the most important sustainability concerns of modern society, namely Energy Security, Economic Growth and Global Warming. Analysing these real-life sustainability issues in a multi-disciplinary context leads to conclusions that are controversial in terms of established philosophical worldviews and policy trends. Firstly, the thesis establishes deterministic expectations of an imminent era of declining Energy Security resulting from the exhaustion of non-renewable fossil fuel resources, despite optimistic expectations of technology improvements in alternative energy sources such as renewable and nuclear. Secondly, the exhaustion of non-renewable fossil fuel resources imposes limits to the potential sources of anthropogenic carbon emissions that render the more pessimistic emissions cases considered in the global warming debate irrelevant. The lower level of attainable carbon emissions challenges the merits of the conventional carbon feedback cycle with the result that the predicted global warming is within acceptance limits of the contemporary global warming debate. Thirdly, the consequences of declining Energy Security on socio-economic welfare is a severe divergence from historical trends and demands the reassertion of the role of energy in human development, including Economic Growth theory. The thesis develops a novel economic growth model that treats energy as an explicit and Autonomous Factor of Production, thereby facilitating plausible predictions of future Economic Growth potential. The results challenge the sustainability of the current free-market capitalist economic system and demand strong policy responses to avoid the collapse of modern society.

The transition to a low carbon future is necessary to ensure humanity’s sustainable future, yet the expanding introduction of renewable energy technologies (RETs) is a central driver for transformations in rural landscapes worldwide. Introducing renewable energy (RE) infrastructures in rural landscapes raises concerns about the reduced naturalness and attractiveness of such landscapes for tourism and recreation as well as the transformation of people-place bonds as established through people’s interactions with and experiences in the surrounding landscapes. Few have examined how landscape transformation resulting from RE developments reshapes land users’ bonds with places. Furthermore, previous research has primarily relied on crosssectional quantitative data. This study addresses that literature gap and uses the Nature's Contributions to People (NCP) framework and the evolutionary theory of place attachment as theoretical underpinnings to examine how individuals perceive and experience evolving landscapes. By exploring individuals’ perceptions of and affective bonds with physical landscapes, this study provides a holistic understanding of the bonds that different groups of people may have with a certain place and how these bonds are manifested in the context of RE development and RET-related place change. In-depth interviews with private landowners and recreationists from the municipality of Mönsterås, Sweden, and observations in the Åby-Alebo wind park allow for the coconstruction of narratives reflecting individual accounts of meaning-making processes. The findings demonstrate that place attachment was evident in respondents’ descriptions of how they make a place meaningful to themselves through personal experiences and (recreational) practices. Along with landscape changes, for some individuals, meanings towards and bond with place evolved as well. The discussion shows that the emotional relationship to place reflects respondents’ particular journey in the world and over time. The study also highlights that differences in how recreationists and landowners bond with places is manifested in a changing context, disclosing the relationality of place attachment along social, practical, and temporal contextual factors. This points to encouraging possibilities for discussing the reconceptualization of humanity’s transition towards a low carbon future and fostering more sustainable landscape management in rural recreation areas.

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.

The Piceance Basin in western Colorado has undergone a drastic increase in oil and gas development over the last two decades. This increase has escalated concerns about the effects of development on the Basin’s flora and fauna, especially the rare plant community. Potential impacts from oil and gas development on rare plants may be found through decrease in plant habitat or by a decrease in plant reproductive success through changes to important pollinator communities. Here, we observed the pollinator community on two rare mustard plants, Physaria congesta and Physaria obcordata (Brassicaceae), both listed as threatened by the US Fish and Wildlife Service (Federal Register 55 FR 4152). We studied a series of questions concerning the pollinator community important to each Physaria species. The experiments were conducted in the spring of 2010 and 2011 during the blooming season of each rare Physaria. We investigated the effect of oil and gas development on the pollinator community by evaluating abundance, diversity, behavior, and foraging rates along a distance gradient from roadsides. This study also examines plant fecundity to determine the extent of pollinator efficiency across the same distance gradient from roadsides. Additionally, we examine nesting success of pollinators within plant populations, as well as around natural gas wellpads. Further, we conduct a breeding system and cross pollination study on P. congesta to determine the importance of pollination services for reproduction. To determine overall pollinator community changes around other development types we sampled pollinators around wellpads. Our data supports the null hypothesis, suggesting that at this time oil and gas development may have little to no impact on the pollinator community abundance. The analysis conducted may not have been able to detect changes in the community, due to a small sample size of pollinators collected. Bee pollinators may forage on a few or many floral resources. Here, we account for the ancillary foraging resources of P. congesta and P. obcordata pollinators by identifying pollen removed from bees collected on rare Physaria. This specific community of plants may require conservation in addition to the rare plants, to assist in maintaining the pollinator community.

A thesis submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. University of the Witwatersrand, Johannesburg / Power system adequacy has been historically insufficient in the Southern African Power Pool (SAPP) region with resulting negative effects on economic growth and electrification efforts. Existing domestic regulatory frameworks and opaque longterm bilateral contracting for procuring capacity in the region have been shown to be insufficient in ensuring system adequacy. The concept of an adequacy product in the form of a Capacity Mechanism (CM) introduced into the SAPP region has not yet appeared in the literature. A Capacity Mechanism (CM) for the SAPP region has been proposed and designed as part of this research to address this. A framework has been developed to consider CMs via the combination of a screening assessment, quantitative (model-based) analysis of more favourable CM options and an identification and quantification of key design elements. The developed framework can also be generalised and applied to other jurisdictions where CMs are under consideration. A regional CM which transparently and explicitly values capacity is proposed in the form of a forward-looking annual Capacity Auction that is locationally disaggregated, supplied by all possible supply-side resources with all feasible SAPP market participants included. The CM should be technology agnostic and account for the dual requirement for firm capacity to meet peak demand and firm-energy to meet annual energy requirements considering the dominance of hydrobased capacity in the region when excluding South Africa. There should be a leadtime of 3-4 years with the possibility of long-term auctions for large hydro-based capacity. Strict market monitoring and adherence to performance incentives and penalties will need to be ensured to avoid exercising of market power considering the dominant size of the South African power system. Appropriately mandated institutions to run Capacity Auctions would include the SAPP Co-Ordination Centre as well as a sufficiently mandated regional regulatory body. A further contribution is made in the form of a public domain power system dataset of the SAPP region with sufficient detail to be used in power system operations and planning efforts by future researchers and practitioners. / E.K. 2020