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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.
81

An exploration of renewable energy policies with an econometric approach

Kilinc Ata, Nurcan January 2015 (has links)
This thesis focuses on the renewable energy policies for the case study countries (European Union, United States, United Kingdom, Turkey, and Nigeria) with using quantitative and qualitative analysis. The thesis adopts a three -pronged approach to address three main issues: The first paper investigates a 1990-2008 panel dataset to conduct an econometric analysis of policy instruments, such as; feed-in tariffs, quotas, tenders, and tax incentives, in promoting renewable energy deployment in 27 EU countries and 50 US states. The results suggest that renewable energy policy instruments play a significant role in encouraging renewable energy sources. Using data from 1990 to 2012 with the vector auto regression (VAR) approach for three case study countries, namely United Kingdom, Turkey, and Nigeria, the second paper focuses on how renewable energy consumption as part of total electricity consumption is affected by economic growth and electricity prices. The findings from the VAR model illustrate that the relationship between case study countries’ economic growth and renewable energy consumption is positive and economic growth in case study countries respond positively and significantly. The third paper focuses on the relationship between renewable energy policies and investment in renewables in the countries of United Kingdom and Turkey. The third paper builds upon current knowledge of renewable energy investment and develops a new conceptual framework to guide analyses of policies to support renewables. Past and current trends in the field of renewable energy investment are investigated by reviewing the literature on renewable energy investment linkage with policies, which identifies patterns and similarities in RE investment. This also includes the interview analysis with investors focusing on policies for renewable energy investment. The results from the interview and conceptual analysis show that renewable policies play a crucial role in determining investment in renewable energy sources. The findings from this thesis demonstrate that renewable energy policies increase with a growth of the renewable energy investment in the sector. Finally, the outcomes of this thesis also contribute to the energy economics literature, especially for academic and subsequent research purposes.
82

Photocatalytic water splitting

Kuo, Yenting January 1900 (has links)
Doctor of Philosophy / Department of Chemistry / Kenneth J. Klabunde / New photocatalystic materials Ti-In oxy(nitride) and nanosized Ru-loaded strontium titanate doped with Rh (Ru/SrTiO3:Rh) have been synthesized. The textural and surface characteristic properties were studied by nitrogen BET analysis, diffuse reflectance UV-vis spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy and powder XRD. The photocatalytic properties were enhanced by the binary metal oxides of titanium dioxide and indium oxide. The XRD patterns confirmed the oxygen exchange between two metal oxides during the synthesis. Moreover, the presence of titanium dioxide can help the stabilization of InN during hot NH3(g) treatment. On the other hand, the particle sizes of aerogel prepared Ru/SrTiO3:Rh varied from 12 to 25 nm depended on different Rh doping. A mixture of ethanol and toluene was found to be the best binary solvent for supercritical drying, which yielded a SrTiO3 sample with a surface area of 130 m2 Enhanced photocatalytic hydrogen production under UV-vis light irradiation was achieved by ammonolysis of intimately mixed titanium dioxide and indium oxide at high temperatures. Gas chromatography monitored steadily the formation of hydrogen when sacrificial (methanol or ethanol) were present. XRD patterns confirmed that the photocatalysts maintain crystalline integrity before and after water splitting experiments. Moreover, the presence of InN may be crucial for the increase of hydrogen production activities. /g and an average crystallite size of 6 nm. These Ru/SrTiO3:Rh photocatalysts have been studied for photocatalytic hydrogen production under visible light. The band gap of the bulk SrTiO3 (3.2 eV) does not allow response to visible light. However, after doping with rhodium and loaded with ruthenium, the modified strontium titanates can utilize light above 400 nm due to the formation of valence band or electron donor levels inside of the band gap. Moreover, the surface areas of these photocatalysts are much larger than conventional solid-state synthesized samples (1-2 m 2/g), which yielded more Ru loading and reaction sites. The areogel and hydrothermal synthesized samples required basic (alkaline) conditions for hydrogen generation facilitation compared with acidic conditions for conventional solid-state samples.
83

A comparative analysis of renewable energy financing models in Brazil, China, India and South Africa

Kamara, Rivhatshinyi Nicole January 2016 (has links)
Thesis submitted in fulfilment of the requirements for the degree of Master of Management in Finance & Investment in the Faculty of Commerce Law and Management Wits Business School, Johannesburg 2016 / This thesis reviewed research papers, reports, conference documents and policy documents that looked at financial models used to finance RE projects in Brazil, China, India and South Africa.The comparison between the financing models revealed the following; Both Brazil and China’s financing model is a centralised government led model which might not necessarily work in the South African context. The India decentralised model is similar to the South African model, with the exception that corporate finance is widely used in India and Project Finance in South Africa. Thus there are lessons to be learnt from each country, however no single country financing model was found to be suitable for South Africa. Accordingly, this paper therefore recommends that South Africa’s model be altered to incorporate project bonds. The use of these bonds in the current financial model will ensure that banks are able to lend to projects on short term basis; thus, managing their liquidity and their asset--liability effectively. Further, some institutional investors have shown an interest in funding projects at the construction stage, and the inclusion of project bonds would ensure that more of these investors play a role in financing projects. Key Words GDP-Gross Domestic Product; GW- Gigawatts; DoE-Department of Energy; REIPPPP- Renewable Energy Independent Power Producer Procurement Programme; BEE-Black Economic Empowerment; RE-Renewable Energy; SSA-Sub Saharan Africa; PPA-Power Purchase Agreement; FIT-Feed In Tariff; DFIDevelopment Finance Institution; MDB-Multilateral Development Bank / GR2018
84

Desenvolvimento de um método para a determinação de acilgliceróis em biodiesel utilizando cromatografia líquida de alta eficiência com detecção eletroquímica /

Ballottin, Daniela Pott Marinho. January 2011 (has links)
Orientador: Nelson Ramos Stradiotto / Banca: Marcelo Firmino de Oliveira / Banca: André Luiz dos Santos / Resumo: A alta demanda de energia no mundo atual, bem como o grande número de problemas ambientais existentes, resultam em uma crescente necessidade por novas fontes de energia, estimulando assim o interesse por fontes alternativas para os combustíveis de origem fóssil. Surge então o Biodiesel, combustível biodegradável derivado de fontes renováveis. No entanto, este biocombustível apresenta certos contaminantes que podem causar sérios danos ao motor e ao ambiente dependente de seus teores. Dentre estes, estão os acilgliceróis, remanescentes da matéria prima para a produção do biodiesel. Por exemplo, a alta concentração destes compostos aumenta a viscosidade do biocombustível, provocando depósitos nos cilindros e nas válvulas diminuindo assim a vida útil do motor. Assim, foi avaliado neste trabalho o comportamento voltamétrico do mono, di e trilinoleato de glicerina através da técnica de Redissolução Adsortiva com Voltametria AC. As curvas analíticas para o mono e trilinoleato de glicerina apresentaram linearidade de 4,0 x 10-8 a 1,6 x 10-6 mol L-1, com limites de detecção da ordem de 10-8 mol L-1. A curva analítica do dilinoleato de glicerina mostrou-se linear de 4,0 x 10-9 a 4,0 x 10-7 mol L-1, com limite de detecção da ordem de 10-9 mol L-1. Os limites de quantificação foram da ordem de 10-8 mol L-1 para o mono e o dilinoleato de glicerina e 10-7 mol L-1 para o trilinoleato de glicerina. Porém, estes não puderam ser determinados simultaneamente e, por isso, utilizou-se um método cromatográfico com detecção eletroquímica para a separação e posterior detecção destes compostos. Os acilgliceróis foram separados em coluna de fase reversa (C-18) operando em modo isocrático com fase móvel tampão fosfato pH 3,0/MeOH 60:40 (v/v) com adição de ácido ascórbico / Abstract: Currently, the high energy demand in today's world, as well as the environmental problems result in an increased need for developing renewable energy sources, thereby stimulating interest in alternative sources to fossil fuels. Then, Biodiesel comes as a biodegradable fuel derived from renewable sources. However, this biofuel has certain contaminants that can cause serious damage to the engine and the environment if they are present in inadequate amounts. Among these contaminants are the glycerides, remnants of the raw material for biodiesel production. For example, the high concentration of these compounds increases the viscosity of the biofuel causing deposits in the cylinders and valves reducing the engine lifetime. Thus, it was evaluated in this study the voltammetric behavior of glyceryl mono, di and trilinoleate by Adsorptive Stripping technique with AC voltammetry. The analytical curves for mono and tri showed linearity from 4.0 x 10-8 to 1.6 x 10-6 mol L-1, with detection limits of about 10-8 mol L-1. The analytical curve of glyceryl dilinoleate was linear from 4.0 x 10-9 to 4.0 x 10-7 mol L-1, with a detection limit of about 10-9 mol L-1. The quantification limits were in the order of 10-8 mol L-1 for mono and dilinoleate and 10-7 mol L-1 for trilinoleate. However, these could not be determined simultaneously and therefore it was developed a chromatographic method with electrochemical detection for separation and detection of these compounds. The glycerides were separated on a reversed phase column (C-18) operating in isocratic mode with mobile phase pH 3.0 phosphate buffer / MeOH 60:40 (v/v) with addition of ascorbic acid / Mestre
85

Fine Line Metallization of Silicon Heterojunction Solar Cells via Collimated Aerosol Beam Direct Write

January 2012 (has links)
Solar energy has come to the forefront as a scalable and largely underutilized renewable energy resource. The current cost of solar electricity, namely from photovoltaics, along with other logistics factors, has prevented the widespread adaptation of the technology. A key determinant of efficiency and cost for a solar cell is the current collector grid. This work presents the Collimated Aerosol Beam Direct Write (CAB-DW) system as a non-contact printing method that can achieve current collector grid finger widths of less than 10 μm which are amenable to decreasing both resistive and optical losses. The ability to produce high aspect ratio grid fingers, and deposit optimized grid structures on high efficiency SHJ solar cells using silver nanoparticle inks is also demonstrated. A decrease in shadowing and via profile modification of the grid fingers is presented, along with a study of aging and degradation of electrical properties within silver nanoparticle inks.
86

Minimizing Water Requirements for Electricity Generation in Water Scarce Areas

Stults, Erica Suzanne 04 May 2015 (has links)
Renewable energy technologies are infrequently evaluated with regard to water use for electricity generation; however traditional thermoelectric power generation uses approximately 50% of the water withdrawn in the US. To address problems of this water-energy nexus, we explore the replacement of existing electricity generation plants by renewable technologies, and the effect of this replacement on water use. Using a binary mixed integer linear programing model, we explore how the replacement of traditional thermoelectric generation with renewable solar and wind technologies can reduce future water demands for power generation. Three case study scenarios focusing on the replacement of the J.T. Deely station, a retiring coal thermoelectric generation plant in Texas, demonstrate a significant decrease in water requirements. In each case study, we replace the generation capacity of the retiring thermoelectric plant with three potential alternative technologies: solar photovoltaic (PV) panels, concentrated solar power (CSP), and horizontal axis wind turbines (HAWT). The first case study, which was performed with no limits on the land area available for new renewable energy installations, demonstrated the water savings potential of a range of different technology portfolios. Our second case study examined the replacement while constrained by finite available land area for new installations. This demonstrated the trade-off between land-use efficient technologies with water-use efficiency. Results from our third case study, which explored the replacement of a gas-fired plant with a capacity equivalent to the J. T. Deely station, demonstrated that more water efficient thermoelectric generation technologies produce lower percentages of water savings, and in two scenarios the proposed portfolios require more water than the replaced plant. Comparison of multiple aspects of our model results with those from existing models shows comparable values for land-use per unit of electricity generation and proposed plant size. An evaluation of the estimated hourly generation of our model’s proposed solution suggests the need for a trade-off between the intermittency of a technology and the required water use. As we estimate the “costs� of alternative energy, our results suggest the need to include in the expression the resulting water savings.
87

A study of regularities associated with biochemical processes and renewable energy resources

Patel, Snehal A January 2011 (has links)
Typescript (photocopy). / Digitized by Kansas Correctional Industries
88

Nanofluidics: Fundamentals and Applications in Energy Conversion

Liu, Ling January 2010 (has links)
As a nonwetting liquid is forced to invade the cavities of nanoporous materials, the liquid-solid interfacial tension and the internal friction over the ultra-large specific surface area (usually billions of times larger than that of bulk materials) can lead to a nanoporous energy absorption system (or, composite) of unprecedented performance. Meanwhile, while functional liquids, e.g. electrolytes, are confined inside the nanopores, impressive mechanical-to-electrical and thermal-to-electrical effects have been demonstrated, thus making the nanoporous composite a promising candidate for harvesting/scavenging energy from various environmental energy sources, including low grade heat, vibrations, and human motion. Moreover, by taking advantage of the inverse process of the energy absorption/harvesting, thermally/electrically controllable actuators can be designed with simultaneous volume memory characteristics and large mechanical energy output. In light of all these attractive functionalities, the nanoporous composite becomes a very promising building block for developing the next-generation multifunctional (self-powered, protective and adaptive) structures and systems, with wide potential consumer, military, and national security applications. In essence, all the functionalities of the proposed nanofluidic energy conversion system are governed by nanofluidics , namely, the behavior of liquid molecules and ions when confined in ultra-small nanopores. Nanofluidics is an emerging research frontier where solid mechanics and fluid mechanics meet at the nanoscale. The complex interactions between liquid molecules/ions and solid atoms at the nanointerface, as well as the unique structural, thermal and electrical characteristics of fluids confined in nanocavities collectively represent an outstanding challenge in physical science. A thorough understanding of the science of nanofluids, in particular the detailed molecular mechanisms as well as the roles of various material and system parameters, does not only underpin the development and optimization of the aforementioned nanofluidic energy conversion system, but it also have broad impact on a number of other areas including environmental engineering, chemical engineering, bioengineering, and energy engineering, etc. This dissertation carries out a systematic computational study to explore the fundamental nanofluidic infiltration and transport mechanisms, as well as the thermal and electrical characteristics of the solid-liquid interface. New physical models describing the unique nanofluidic phenomena will be established, where critical parameters, such as the surface tension, contact angle, and viscosity, will be reinvestigated at the nanoscale. The effects of various material and system parameters, such as the solid phase, liquid phase, pore size and pore geometry, as well as the external thermal, electrical and mechanical loads, etc., will be systematically investigated and bridged with the nanofluidic energy conversion processes. The energy conversion efficiencies under various conditions will be evaluated via a synergy between simulation and experiment. Reverse analysis based on the revealed principles can guide the optimization of the various material and system parameters, which potentially may contribute to the design of highly efficient and sustainable nanofluidic energy conversion devices. Besides the direct impact on the nanofluidic energy conversion, the study is also directly relevant to biological conduction and environmental sustainability, in both of which infiltration and transport play important roles.
89

Sustainable agriculture, renewable energy and rural development an analysis of bio-energy systems used by small farms in China /

Zhou, Aiming. January 2006 (has links)
Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: John Byrne, School of Urban Affairs & Public Policy. Includes bibliographical references.
90

Integration of renewable energy sources: reliability-constrained power system planning and operations using computational intelligence

Wang, Lingfeng 15 May 2009 (has links)
Renewable sources of energy such as wind turbine generators and solar panels have attracted much attention because they are environmentally friendly, do not consume fossil fuels, and can enhance a nation’s energy security. As a result, recently more significant amounts of renewable energy are being integrated into conventional power grids. The research reported in this dissertation primarily investigates the reliability-constrained planning and operations of electric power systems including renewable sources of energy by accounting for uncertainty. The major sources of uncertainty in these systems include equipment failures and stochastic variations in time-dependent power sources. Different energy sources have different characteristics in terms of cost, power dispatchability, and environmental impact. For instance, the intermittency of some renewable energy sources may compromise the system reliability when they are integrated into the traditional power grids. Thus, multiple issues should be considered in grid interconnection, including system cost, reliability, and pollutant emissions. Furthermore, due to the high complexity and high nonlinearity of such non-traditional power systems with multiple energy sources, computational intelligence based optimization methods are used to resolve several important and challenging problems in their operations and planning. Meanwhile, probabilistic methods are used for reliability evaluation in these reliability-constrained planning and design. The major problems studied in the dissertation include reliability evaluation of power systems with time-dependent energy sources, multi-objective design of hybrid generation systems, risk and cost tradeoff in economic dispatch with wind power penetration, optimal placement of distributed generators and protective devices in power distribution systems, and reliability-based estimation of wind power capacity credit. These case studies have demonstrated the viability and effectiveness of computational intelligence based methods in dealing with a set of important problems in this research arena.

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