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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Design and development of a 200 W converter for phosphoric acid fuel cells

Kuyula, Christian Kinsala 03 1900 (has links)
M. Tech. (Engineering: Electrical, Department Electronic Engineering, Faculty of Engineering and Technology), Vaal University of Technology, / “If we think oil is a problem now, just wait 20 years. It’ll be a nightmare.” — Jeremy Rifkin, Foundation of Economic Trends, Washington, D.C., August 2003. This statement harmonises with the reality that human civilisation faces today. As a result, humankind has been forced to look for alternatives to fossil fuels. Among possible solutions, fuel cell (FC) technology has received a lot of attention because of its potential to generate clean energy. Fuel cells have the advantage that they can be used in remote telecommunication sites with no grid connectivity as the majority of telecommunication equipment operates from a DC voltage supply. Power plants based on phosphoric acid fuel cell (PAFC) have been installed worldwide supplying urban areas, shopping centres and medical facilities with electricity, heat and hot water. Although these are facts regarding large scale power plants for on-site use, portable units have been explored as well. Like any other fuel cell, the PAFC output power is highly unregulated leading to a drastic drop in the output voltage with changing load value. Therefore, various DC–DC converter topologies with a wide range of input voltages can be used to regulate the fuel cell voltage to a required DC load. An interleaved synchronous buck converter intended for efficiently stepping down the energy generated by a PAFC was designed and developed. The design is based on the National Semiconductor LM5119 IC. A LM5119 evaluation board was redesigned to meet the requirements for the application. The measurements were performed and it was found that the converter achieved the expectations. The results showed that the converter efficiently stepped down a wide range of input voltages (22 to 46 V) to a regulated 13.8 V while achieving a 93 percent efficiency. The conclusions reached and recommendations for future research are presented. / Telkom Centre of Excellence, TFMC, M-Tech, THRIP.
12

O uso de fontes limpas de energia na indústria paulista: um estudo envolvendo a técnica do incidente crítico e a análise conjunta / The use of clean energy resources in the São Paulo state industry: a study involving the critical incident technique and conjoint analysis

Camioto, Flávia de Castro 10 June 2010 (has links)
O presente trabalho tem o objetivo de identificar fatores intervenientes na adoção de energias limpas nos principais setores industriais do Estado de São Paulo. Para tanto, apresenta a fundamentação teórica sobre os diversos temas pertinentes a pesquisa, tais como: o atual cenário energético brasileiro e o desenvolvimento sustentável, bem como o estudo dos métodos aplicados. A análise dos dados realizada teve caráter qualitativo e quantitativo, por meio, respectivamente, da Técnica do Incidente Crítico e da Análise Conjunta. A aplicação da Técnica do Incidente Crítico forneceu os atributos que as empresas consideram importantes no processo de escolha. Já a Análise Conjunta, técnica estatística multivariada de análise de dados, foi utilizada para determinar a utilidade e importância relativa dos atributos relevantes na escolha das empresas. Com os resultados da pesquisa acredita-se que as empresas usuárias e não usuárias de energias limpas poderão ter conhecimentos sobre a opinião de seus pares com relação às vantagens e desvantagens do uso destes energéticos nos processos produtivos, assim como ao governo estabelecer estratégias adequadas para orientar e estimular a adoção de energias que promovem baixo impacto ao meio ambiente. / The scope of the present work is to identify intervening factors in the adoption of clean energy resources in the main industrial sectors of the São Paulo state. In order to perform such evaluation, a theoretical reasoning on the various relevant issues related to the research shall be displayed, such as: the current brazilian energy context and sustainable development, as well as the study of applied methods. The data analysis was realized guided on a qualitative and quantitative basis, by means, respectively, of the Critical Incident Technique and the Conjoint Analysis. The application of the Critical Incident Technique has imputed capabilities that companies regard as pivotal in the selection process. The Conjoint Analysis, on its hand, multivariate statistics technique on data analysis, was used in order to determine the utility and relative importance of the capabilities relevant to the companies\' selection. Based on the results inferred from the research it may be conjectured that companies that adopt and do not adopt clean energy resources may acquire acknowledge about the opinion of its couples in what it concerns the advantages and disadvantages of the use of these energetic in these productive processes, as well the government may set to establish adequate strategies in order to instruct and encourage the adoption of energy resources that promote a lesser impact to the environment.
13

Building capacity for green, just and sustainable futures – a new knowledge field requiring transformative research methodology

Rosenberg, Eureta, Ramsarup, Presha, Gumede, Sibusisiwe, Lotz-Sisitka, Heila 1965- January 2016 (has links)
Education has contributed to a society-wide awareness of environmental issues, and we are increasingly confronted with the need for new ways to generate energy, save water and reduce pollution. Thus new forms of work are emerging and government, employers and educators need to know what ‘green’ skills South Africa needs and has. This creates a new demand for ‘green skills’ research. We propose that this new knowledge field – like some other educational fields – requires a transformative approach to research methodology. In conducting reviews of existing research, we found that a transformative approach requires a reframing of key concepts commonly used in researching work and learning; multi-layered, mixed method studies; researching within and across diverse knowledge fields including non-traditional fields; and both newly configured national platforms and new conceptual frameworks to help us integrate coherently across these. Critical realism is presented as a helpful underpinning for such conceptual frameworks, and implications for how universities prepare educational researchers are flagged.
14

Tecnologia de geração de energia limpa a serviço da promoção da saúde / Technology of clean energy to health promotion

Luiz Felipe de Camargo Kastrup 24 February 2006 (has links)
A falta de acesso à energia elétrica e a todos os benefícios que ela pode trazer levou à elaboração desta pesquisa, tendo como foco principal o atendimento às necessidades básicas de saúde. Para a presente pesquisa estudou-se: o acesso à saúde no Brasil; a seleção de um município como piloto, em um estado brasileiro com baixo IDH (índice de Desenvolvimento Humano), precário atendimento básico à saúde e sem eletrificação rural; oss sistemas de geração de energia elétrica no Brasil, com destaque para os sistemas de geração distribuída; as tecnologias disponíveis no Brasil, para geração de energia elétrica distribuída e limpa; a definição de uma UBS (Unidade Básica de Saúde), quanto a compartimentos, equipamentos, consumo energético, baixa manutenção e facilidade na construção. Foi dimensionada uma Unidade Básica de Saúde, que atendesse a este município, resultando em um projeto de UBS e de um sistema de geração de energia para atender às suas demandas. Desenvolveu-se então um sistema de geração de energia elétrica distribuída e limpa, para a UBS, através da integração de painéis fotovoltaicos com célula a combustível que utiliza hidrogênio, e para a produção do hidrogênio, um eletrolisador para a eletrólise da água. O sistema proposto permite o funcionamento continuo desta UBS, com baixa manutenção, de forma sustentável, em qualquer região isolada, necessitando apenas da incidência da luz solar e de água, permitindo promover a saúde das populações carentes, residentes nos locais mais longínquos, fixando-as em seus locais de origem, sem causar impactos ambientais. / The lack of access to electric energy and all the benefits that it can bring led to the elaboration of this research, having as main focus the attendance to the basic necessities of health. For the present research it was studied: the access to health in Brazil; the election of a city as pilot, in a Brazilian state with low IDH (index of Human Development), precarious basic health attendance and without agricultural electrification; the electric energy generation systems in Brazil, with prominence for the distributed systems generation; the available technologies in Brazil, for distributed electric and clean energy generation; the definition of a BHU (Basic Health Unit), about compartments, equipment, energy consumption, low maintenance and easy construction. The BHU's size was calculated, for this city, resulting in a project of BHU and a generation energy system for its demands. A distributed electric and clean energy generation system was developed, for the BHU, through the integration of photovoltaic panels with fuel cells that use hydrogen, and for the hydrogen production, an electrolyser for electrolysis of water. The considered system allows the continuous functioning of this BHU, with low maintenance, in sustainable form, in any isolated region, needing only the solar light incidence and water, allowing to promote the health of the poor populations living 9in places most distant, fixing them in their places of origin, without environmental impacts.
15

Tecnologia de geração de energia limpa a serviço da promoção da saúde / Technology of clean energy to health promotion

Kastrup, Luiz Felipe de Camargo 24 February 2006 (has links)
A falta de acesso à energia elétrica e a todos os benefícios que ela pode trazer levou à elaboração desta pesquisa, tendo como foco principal o atendimento às necessidades básicas de saúde. Para a presente pesquisa estudou-se: o acesso à saúde no Brasil; a seleção de um município como piloto, em um estado brasileiro com baixo IDH (índice de Desenvolvimento Humano), precário atendimento básico à saúde e sem eletrificação rural; oss sistemas de geração de energia elétrica no Brasil, com destaque para os sistemas de geração distribuída; as tecnologias disponíveis no Brasil, para geração de energia elétrica distribuída e limpa; a definição de uma UBS (Unidade Básica de Saúde), quanto a compartimentos, equipamentos, consumo energético, baixa manutenção e facilidade na construção. Foi dimensionada uma Unidade Básica de Saúde, que atendesse a este município, resultando em um projeto de UBS e de um sistema de geração de energia para atender às suas demandas. Desenvolveu-se então um sistema de geração de energia elétrica distribuída e limpa, para a UBS, através da integração de painéis fotovoltaicos com célula a combustível que utiliza hidrogênio, e para a produção do hidrogênio, um eletrolisador para a eletrólise da água. O sistema proposto permite o funcionamento continuo desta UBS, com baixa manutenção, de forma sustentável, em qualquer região isolada, necessitando apenas da incidência da luz solar e de água, permitindo promover a saúde das populações carentes, residentes nos locais mais longínquos, fixando-as em seus locais de origem, sem causar impactos ambientais. / The lack of access to electric energy and all the benefits that it can bring led to the elaboration of this research, having as main focus the attendance to the basic necessities of health. For the present research it was studied: the access to health in Brazil; the election of a city as pilot, in a Brazilian state with low IDH (index of Human Development), precarious basic health attendance and without agricultural electrification; the electric energy generation systems in Brazil, with prominence for the distributed systems generation; the available technologies in Brazil, for distributed electric and clean energy generation; the definition of a BHU (Basic Health Unit), about compartments, equipment, energy consumption, low maintenance and easy construction. The BHU's size was calculated, for this city, resulting in a project of BHU and a generation energy system for its demands. A distributed electric and clean energy generation system was developed, for the BHU, through the integration of photovoltaic panels with fuel cells that use hydrogen, and for the hydrogen production, an electrolyser for electrolysis of water. The considered system allows the continuous functioning of this BHU, with low maintenance, in sustainable form, in any isolated region, needing only the solar light incidence and water, allowing to promote the health of the poor populations living 9in places most distant, fixing them in their places of origin, without environmental impacts.
16

Determinants of Green Power Purchases: An Analysis of the EPA's Green Power Partnership

Houseworth, Sean C. 01 January 2013 (has links)
This paper explores the factors that drive purchases of green power by private and public organizations. Using a cross-sectional analysis of participants in EPA’s Green Power Partnership, I explore whether state energy policies have motivated increased consumption of green power among these participating organizations. Additionally, I analyze economic and political variables by state to determine if certain factors contribute to an organization’s green power purchases. I find that state mandates on renewable energy production and lower premiums for green power lead to increased purchases of green power for members of the Green Power Partnership.
17

A study of the economic structure and change in the Texas Triangle

Kim, Kiwook 04 December 2013 (has links)
As global economic competition has intensified, many countries have begun focusing on the competitiveness of larger regions of city networks called megaregions. Consisting of two or more cities with specific linkages and connections, megaregions are becoming a new unit that researchers are using to analyze the global economy. The world’s 40 largest megaregions produce two thirds of the global economic output and more than eighty percent of the world’s innovations (Florida et al., 2007). Therefore, understanding the economic characteristics of megaregions can help isolate various challenges and opportunities associated with building on inter-relationships that enhance competitiveness. The Texas Triangle is one of 10 major megaregions in the U.S., and it functions as the primary economic engine of the Texas economy. This study analyzes how the economic characteristics of the major metropolitan areas in the Texas Triangle have changed over time by studying the basic dynamics of these metropolitan areas over the last decade. Results from this study show that each metropolitan area contains specialized export industries and that competition among them seems to be encouraging the economic growth of Texas. The basic industrial structure of the Texas Triangle has not been affected significantly by economic changes over the last decade. Finally, this report presents policy implications related to strengthening traditional economic bases and promoting sustainable economic development such as clean energy in the Texas Triangle. / text
18

Synthesis of a Novel Organoplatinum (II) Compound

Nesbitt, Elizabeth 01 January 2015 (has links)
Preliminary NMR data indicate that a new platinum compound, assigned (TpyO)PtMe (TpyO = 2,6-bis-(2’pyridyl)-4-pyridonate), can be synthesized by the addition of impure trans-(DMSO)2PtMeCl to impure 2,6-bis(2’-pyridyl)-4-hydroxypyridine (TpyOH) in the presence of NEt3 in about 10% yield. It is likely that the yield could be increased by using purified TpyOH and (DMSO)2PtMeCl. The metalation step of the synthesis was also attempted using (COD)PtMeCl but was unsuccessful with either Na2CO3 or NEt3 as bases, most likely due to the chelate effect of the bidentate COD. Future work with (TpyO)PtMe will include the addition of H+/D+ to generate the platinum (IV) complex, [(TpyO)Pt(Me)(H)]+, and/or the σ-complex [(TpyO)Pt(Me-H)]+ in order to examine the kinetic, isotope, and thermodynamic effects of the resulting reductive elimination reaction.
19

Why U.S. states became leaders in climate and energy policy: innovation through competition in federalism

Deitchman, Benjamin Harris 27 August 2014 (has links)
The competitive federalist system facilitated state leadership and the diffusion of innovative policies that addressed climate change and energy issues in the absence of comprehensive federal action at the start of the twenty-first century. In a competitive federalist system state governments and their politicians challenge one another horizontally and the federal government vertically for legislative credit and functional authority on relevant policy issues. What drove state-level climate and clean energy leadership from 2001 to 2012? This dissertation develops three competitive federalism-based hypotheses for analysis: (H1) A national, bipartisan network of ambitious, entrepreneurial governors drove climate and clean energy policy innovation from 2001 to 2012; (H2) the State Energy Program Recovery Act resources reduced the policy adoption gap between early enactors and laggards in clean energy financing and regulation; (H3) and justification for climate and clean energy activities in the states shifted from environmental to economic rationales from 2001 to 2012 (Figure ES1). While competitive federalism theory has centered on both fiscal and ideological considerations driving innovation in the policy environment, the experience of climate change policymaking and clean energy actions at the state level during the period under consideration reveals a clear partisan divide in policymaking within this domain.
20

Tailoring Carbon Materials as Fuels for the Direct Carbon Fuel Cells

Xiang Li Unknown Date (has links)
As a novel high temperature fuel cell, the direct carbon fuel cell (DCFC) is drawing ever-increasing attention due to its significant high conversion efficiency, diversified fuel resources and low pollution compared with conventional coal-fired power plants. Despite the advantages of the DCFC technology, there are a number of fundamental and technological challenges which need to be overcome for its further development and commercialization. One of the major hurdles in current study of the DCFC is that the efficacy of carbon fuels is still unclear. Meanwhile, the effects of impurities in the carbon fuels on the performance and lifetime of the DCFC are still up for debate. Furthermore, the molecular-level study on the mechanism of electrochemical oxidation of carbon fuels in the DCFC is limited by the lack of techniques to detect the reaction intermediates at high temperature. Finally, how to scale up the DCFC system with suitable hardware materials and optimum structural designs needs further investigation. Based on successfully developing a DCFC system with a stirring molten carbonate electrolyte, various commercial and self-made carbon fuels including activated carbons, carbon blacks, graphitic carbons, coals and carbon nanofibers (CNFs) are systematically characterized and evaluated in this thesis. It is found that the nature of carbon fuels plays an important role in the anodic performance of the DCFC. A higher surface area and a smaller particle size of carbon fuel can effectively improve its electrochemical reactivity by increasing the interaction between the carbon particles and the molten carbonate electrolyte. On the contrary, a higher graphitic degree of carbon fuel results in a lower electrochemical reactivity in the DCFC due to the less reactive sites such as edges and defects on carbon surface. Furthermore, the order of the electrochemical reactivities for carbon fuels is in good agreement with the concentration of oxygen-containing functional groups on their surface, which is believed to play a key role in the electrochemical oxidation of carbons in the DCFC. In order to better understand the relationship between the surface chemistry of carbons and their electrochemical performance in the DCFC, various pre-treatment techniques including acid washing, air-plasma treatment, air oxidation, pyrolysis and the pre-electrochemical oxidation (in molten alkali carbonate electrolytes) have been conducted on the carbon fuels. It is shown that both the HNO3 washing and pre-electrochemical oxidation are much more effective to improve the electrochemical reactivities of carbon fuels compared to other pre-treatment techniques, which is attributed to the significant changes in the microstructure of carbon fuels and more surface oxygen functional groups produced during the pre-treatments. In contrast, the pyrolysis treatment results in a sharp decrease of electrochemical reactivity of carbon fuels due to the decreases in oxygen-containing surface groups and surface areas, and the increase of their graphitic degrees. For the sake of the optimum operational conditions for the DCFC system, the influences of stirring rates, the carbon fuel loadings and fuel cell temperatures on the anodic performance of the DCFC are investigated. It has been shown that the carbon discharge rates can be significantly boosted by effective stirring and high carbon fuel concentrations due to an improved mass transport. A higher operation temperature can also increase the current density and open circuit voltage of the DCFC. However, the complete electrochemical oxidation of carbon into CO2 can be only achieved at the low operation temperature of 600-700 ºC, while the partially electrochemical oxidation of carbon into CO occurs at 800 ºC, which will significantly decrease the carbon efficiency to less than 10% at 800 ºC. In the study of self-made CNFs as fuels for the DCFC, both microstructure and electrochemical reactivity of CNFs are highly dependent on their synthesis conditions. Compared with Ni-Al2O3 catalyst, the coprecipitated Ni-Cu-Al2O3 catalyst produced more CNFs with higher electrochemically reactivity. Over the same catalyst, the CNFs synthesized at lower temperature typically have higher surface areas, more surface oxygen functional groups and lower graphitic degrees, thereby leading to a higher electrochemical reactivity in the DCFC tests. In an effort to study the catalytic effects of mineral impurities on the electrochemical performance of the DCFC, Al2O3 and SiO2 present passivation effects in the anodic reaction. In contrast, the CaO, MgO and Fe2O3 show catalytic effects in the carbon electrochemical oxidation, which is demonstrated by the increases of current densities at low over-potentials in the polarization curves.

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