Dissertations / Theses on the topic 'CONVERSION OF ENERGY'
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Lundin, Staffan. "Marine Current Energy Conversion." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-280763.
Full textSilva, Ubiravan Geraldo de Oliveira e. [UNESP]. "Análise energética em refino de petróleo." Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/99282.
Full textConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
No trabalho apresentado foi realizada uma análise de eficiência energética levando em conta variáveis tais como a pressão, a temperatura, o estado físico dos componentes e a atividade de cada elemento que compõe a unidade de craqueamento em refino de petróleo. Tal análise foi realizada baseando-se na Primeira e Segunda leis da Termodinâmica. Destacou-se na análise do FCC a geração e a perda de energia com os gases, levando em conta a concentração molar de cada gás na entrada e na saída do FCC. No riser foram levadas em conta as transformações ocorridas e sua cinética com o propósito de fazer uma análise de gasto de energia no processo de formação inicial dos produtos do FCC; com isso, determinaram-se as quantidades de calor que foram utilizados no processo principal de formação. Foram realizadas análises sobre os fluxos de massas no vaso separador com a abordagem de um suposto fluxo interno, que seria a diferença entre as energias adquiridas com o vapor de retificação com os fluxos de carbono arrastados e com energia vinda do riser, e o fluxo de saída também para o processo de retificação no stripper. Verificou-se a energia gerada pelo regenerador e sua distribuição, que é feita com o aquecimento do catalisador na linha de transmissão do stripper e das perdas de energia com a troca do catalisador gasto e pela massa de catalisador que entra no riser. A energia perdida durante o processo foi associada à energia perdida na integralidade e em cada unidade. Verificou-se que uma parcela do calor gerado no processo é absorvida por gases inertes necessários ou integrados a gases reagentes; além disso, observou-se a formação de novos gases e compostos químicos que geram certas quantidades de energia, e que estão e são importantes na contabilização de toda energia que é gerada. Em tal análise levou-se em conta a energia de formação dos gases e a...
In the present study it was performed an analysis of energy efficiency taking into account variables such as pressure, temperature, physical state of the components and activities of each element that makes up a cracker in petroleum refining. The First and Second Law of Thermodynamics were used for the present analysis. It was highlighted in the analysis of the FCC the generation and loss of energy with the gases, taking into account the molar concentration of each gas at the inlet and outlet of the FCC. In the riser it was taken into account the transformations and their kinetics in order to make an analysis of energy use in the process of initial formation of the products of the FCC; with these results, it was determined the amounts of heat that were used in the main proceedings training. It was analyzed the flow of masses in the separator vessel with the approach of a supposed internal flow, which would be the difference between the energy gained steam with the rectification of carbon fluxes and dragged with energy coming from the riser, and the outflow also for the grinding process in stripper. There was the energy generated by the regenerator and its distribution, which is made by heating the catalyst in the transmission line striper and loss of energy with the exchange of spent catalyst and the mass of catalyst entering the riser. The energy lost during the process was associated with the energy that disappeared in the whole and in each unit. It was found that a portion of the heat generated is absorbed by inert gases necessary or integrated reactive gases; in addition, it was observed the formation of new gases and chemicals that generate amounts of energy, and are important in accounting for all energy that is generated. In this analysis it was taken into account the energy of formation of exhaust gases and the opportunities of products formation in the conditions ... (Complete abstract click electronic access below)
Thorburn, Karin. "Electric Energy Conversion Systems : Wave Energy and Hydropower." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7081.
Full textBalouchi, Farouk. "Footfall energy harvesting : footfall energy harvesting conversion mechanisms." Thesis, University of Hull, 2013. http://hydra.hull.ac.uk/resources/hull:8433.
Full textZhao, Yixin. "Developing Nanomaterials for Energy Conversion." Cleveland, Ohio : Case Western Reserve University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1270172686.
Full textLaestander, Joakim, and Simon Laestander. "OTEC - Ocean Thermal Energy Conversion." Thesis, KTH, Energiteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-98974.
Full textOTEC är en teknik där kraft utvinns från havsvatten genom att utnyttja temperaturdifferensen mellan ytvatten och vatten från djupet. Denna teknik kräver dock generellt en temperaturdifferens på minst 20K. En sådan temperaturskillnad är geografiskt begränsad till den tropiska zonen runt ekvatorn.I rapporten undersöks om OTEC kan användas till att förse 100 000 människor, boende på en 10 stor generisk ö i just den tropiska zonen, med dess elbehov. I detta projekt har det gjorts en litteraturstudie för att etablera en kunskapsbas och sedan gjorts en matematisk modell i programmet EES och slutligen har resultaten från modellen granskats och diskuterats. I modellen jämfördes två olika cykler och målet var att bestämma vilken av dessa som var det bästa alternativet för ön. För att underlätta beräkningarna gjordes vissa antaganden och förenklingar.Den slutna cykeln var mest effektiv men den öppna cykeln (OC) hade positiva synergieffekter som den sluta cykeln (CC) saknade. Kostnaden för en anläggning baserades på äldre studier och enligt dessa var den öppna cykeln billigare än den slutna. Anläggningar av de båda cyklerna kan tillgodose den fiktiva öns energibehov, det behöver dock byggas fler anläggningar om OC väljs framför CC.Det kommer krävas ytterligare arbete med att utveckla tekniken innan OTEC på allvar kan utmana dagens fossilbränslebaserade energisystem – eller att oljan helt enkelt blir för dyr. Idag är OTEC för dyrt för att kunna motiveras rent ekonomiskt, men om även miljövinsterna beaktas, samt att ön befriar sig från importer och därigenom får större kontroll över sitt eget energisystem, finns goda incitament att investera i OTEC redan idag.
Chin, Timothy Edward. "Electrochemical to mechanical energy conversion." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/63015.
Full textCataloged from PDF version of thesis.
Includes bibliographical references.
Electrode materials for rechargeable lithium ion batteries are well-known to undergo significant dimensional changes during lithium-ion insertion and extraction. In the battery community, this has often been looked upon negatively as a degradation mechanism. However, the crystallographic strains are large enough to warrant investigation for use as actuators. Lithium battery electrode materials lend themselves to two separate types of actuators. On one hand, intercalation oxides and graphite provide moderate strains, on the order of a few percent, with moderate bandwidth (frequency). Lithium intercalation of graphite can achieve actuation energy densities of 6700 kJ m-3 with strains up to 6.7%. Intercalation oxides provide strains on the order of a couple percent, but allow for increased bandwidth. Using a conventional stacked electrode design, a cell consisting of lithium iron phosphate (LiFePO4) and carbon achieved 1.2% strain with a mechanical power output of 1000 W m 3 . Metals, on the other hand, provide colossal strains (hundreds of percent) upon lithium alloying, but do not cycle well. Instead, a self-amplifying device was designed to provide continuous, prolonged, one-way actuation over longer time scales. This was still able to achieve an energy density of 1700 kJ n 3, significantly greater than other actuation technologies such as shape-memory alloys and conducting polymers, with displacements approaching 10 mm from a 1 mm thick disc. Further, by using lithium metal as the counterelectrode in an electrochemical couple, these actuation devices can be selfpowered: mechanical energy and electrical energy can be extracted simultaneously.
by Timothy Edward Chin.
Ph.D.
Clark, Joanna Helen. "Inorganic materials for energy conversion." Thesis, University of Liverpool, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.569768.
Full textQiu, Xiaofeng. "NANOSTRUCTURED MATERIALS FOR ENERGY CONVERSION." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1207243913.
Full textRiboni, F. "PHOTOCATALYTIC REACTIONS FOR ENERGY CONVERSION." Doctoral thesis, Università degli Studi di Milano, 2014. http://hdl.handle.net/2434/244319.
Full textChandrasekaran, Rajeswari. "Modeling of electrochemical energy storage and energy conversion devices." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37292.
Full textSilva, Ubiravan Geraldo de Oliveira e. "Análise energética em refino de petróleo /." Guaratinguetá : [s.n.], 2010. http://hdl.handle.net/11449/99282.
Full textAbstract: In the present study it was performed an analysis of energy efficiency taking into account variables such as pressure, temperature, physical state of the components and activities of each element that makes up a cracker in petroleum refining. The First and Second Law of Thermodynamics were used for the present analysis. It was highlighted in the analysis of the FCC the generation and loss of energy with the gases, taking into account the molar concentration of each gas at the inlet and outlet of the FCC. In the riser it was taken into account the transformations and their kinetics in order to make an analysis of energy use in the process of initial formation of the products of the FCC; with these results, it was determined the amounts of heat that were used in the main proceedings training. It was analyzed the flow of masses in the separator vessel with the approach of a supposed internal flow, which would be the difference between the energy gained steam with the rectification of carbon fluxes and dragged with energy coming from the riser, and the outflow also for the grinding process in stripper. There was the energy generated by the regenerator and its distribution, which is made by heating the catalyst in the transmission line striper and loss of energy with the exchange of spent catalyst and the mass of catalyst entering the riser. The energy lost during the process was associated with the energy that disappeared in the whole and in each unit. It was found that a portion of the heat generated is absorbed by inert gases necessary or integrated reactive gases; in addition, it was observed the formation of new gases and chemicals that generate amounts of energy, and are important in accounting for all energy that is generated. In this analysis it was taken into account the energy of formation of exhaust gases and the opportunities of products formation in the conditions ... (Complete abstract click electronic access below)
Orientador: José Antonio Perrella Balestieri
Coorientador: Rubens Alves Dias
Banca: Luiz Roberto Carrocci
Banca: Luciano Fernando dos Santos Rossi
Mestre
Ahmed, Shehab. "Compact harsh environment energy conversion systems." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1289.
Full textBoström, Cecilia. "Electrical Systems for Wave Energy Conversion." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-140116.
Full textFelaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 727
Giddings, S. L. "Heterogeneous reactions in solar energy conversion." Thesis, Swansea University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637056.
Full textHassan, Ibrahim. "Solar energy conversion by photoelectrochemical processes." Thesis, University of Bath, 2011. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.542078.
Full textMuralidharan, Shylesh. "Assessment of ocean thermal energy conversion." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/76927.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (p. 103-109).
Ocean thermal energy conversion (OTEC) is a promising renewable energy technology to generate electricity and has other applications such as production of freshwater, seawater air-conditioning, marine culture and chilled-soil agriculture. Previous studies on the technology have focused on promoting it to generate electricity and produce energy-intensive products such as ammonia and hydrogen. Though the technology has been understood in the past couple of decades through academic studies and limited demonstration projects, the uncertainty around the financial viability of a large-scale plant and the lack of an operational demonstration project have delayed large investments in the technology. This study brings together a broad overview of the technology, market locations, technical and economic assessment of the technology, environmental impact of the technology and a comparison of the levelized costs of energy of this technology with competing ones. It also provides an analysis and discussion on application of this technology in water scarce regions of the world, emphasized with a case study of the economic feasibility of this technology for the Bahamas. It was found that current technology exists to build OTEC plants except for some components such as the cold water pipe which presents an engineering challenge when scaled for large-scale power output. The technology is capital intensive and unviable at small scale of power output but can become viable when approached as a sustainable integrated solution to co-generate electricity and freshwater, especially for island nations in the OTEC resource zones with supply constraints on both these commodities. To succeed, this technology requires the support of appropriate government regulation and innovative financing models to mitigate risks associated with the huge upfront investment costs. If the viability of this technology can be improved by integrating the production of by-products, OTEC can be an important means of producing more electricity, freshwater and food for the planet's increasing population.
by Shylesh Muralidharan.
S.M.in Engineering and Management
Mur, Miranda José Oscar 1972. "Electrostatic vibration-to-electric energy conversion." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/16609.
Full textIncludes bibliographical references (p. 193-197).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Ultra-Low-Power electronics can perform useful functions with power levels as low as 170 nW. This makes them amenable to powering from ambient sources such as vibration. In this case, they can become autonomous. Motivated by this application, this thesis provides the necessary tools to analyze, design and fabricate MEMS devices capable of electrostatic vibration-to-electric energy conversion at the microwatt level. The fundamental means of en- ergy conversion is a variable capacitor that is excited through a generating energy conversion cycle with every vibration cycle of the converter. This thesis presents a road map on how to design MEMS electrostatic vibration-to- electric energy converters. A proposed converter is designed to illustrate the design process, and is based on vibration levels typical of rotating machinery, which are around 2% of the acceleration of gravity from 1-5 kHz. The converter consists of a square centimeter with a 195 mg proof mass which travels ±200 pm. This mass and travel can couple to a sinusoidal acceleration source of 0.02g at 2.5 kHz, typical of rotating machinery, so as to capture 24 nJ per cycle. This moving proof mass is designed to provide a variable capacitor ranging from 1 pF to 80 pF. Adding a capacitor of 88 pF in parallel with this device will result in a capacitance change from 168 pF to 89 pF that is required to extract 24 nJ using a charge-constrained cycle.
(cont.) This device can be attached to power electronics that implement a charge-constrained cycle and deliver 0.5 nJ back to the reservoir for a total power output of 1.3 [mu]/W at 2.5 kHz. The efficiency of the electrical conversion is 2%. Including packaging, the power per volume would be 0.87 [mu]W/cm3 and the power per mass would be 1.3 [mu]W/g. System improvements are also identified such as those that address the principal sources of loss. For example, decreasing the output capacitance of the MOSFET switches from 10 pF to 1 pF, while keeping the energy conversion cycle the same, results in an energy output of 13 nJ out of 24 nJ, for an efficiency of 54% and a power output of 33 [mu]W. This argues strongly for the use of integrated circuits in which the output capacitance of the MOSFET switches can be reduced for this application.
José Oscar Mur Miranda.
Ph.D.
SCILLETTA, CLAUDIA. "Carbon nanotubes for solar energy conversion." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2009. http://hdl.handle.net/2108/1039.
Full textIt has been demonstrated that nanotechnology and nanomaterials could offer valid solutions to improve the conversion efficiency by exploiting effects induced at mesoscopic scales. In this research field, the activity on carbon nanotubes CNTs as building blocks for solar energy conversion devices is developing. The work presented in this thesis has been devoted to investigate the physical mechanisms underlying the photoresponse generation of multiwall carbon nanotubes (MWCNTs) when exploited in electrochemical cells and solid-state devices. A large part of the activity has consisted of the development of suitable strategies for the controlled growth of MWCNTs. MWCNTs have been synthesised by thermal CVD varying the experimental growth parameters. By using morphological and structural characterization techniques, it has been possible to fix the proper synthesis parameters to obtain controlled MWCNTs structures on specific substrates. Experiments of photochemical current generation by MWCNTs grown on SiO2/Si substrates have been performed as well as solid-state photoconductivity measurements. They have confirmed the capability of MWCNTs to generate a current of electrons under light irradiation, despite their close similarity to metallic graphite. EELS spectra show a shoulder at energies 2-4 eV, below the typical plasmon π -π* peak for HOPG. That can be associated, similarly to SWCNTs, to the presence of van Hove singularities in electronic density of states. These transitions allow the generation upon illumination of an exciton. The electrolyte inside the chemical cell and/or the presence of localized Schottky junctions between different MWCNTs separates the charges. The solid-state photoconductivity results have been compared with those obtained in photochemical experiments, and with other described in literature. On the basis of theoretical calculations of DOS for a specific four-wall carbon nanotube (4WCNT), it is possible to affirm that MWCNTs are able to locally create p-n and/or Schottky junctions with the silicon substrate underneath, giving rise to an extended depletion layer. This implies a modification of the feature in the expected photocurrent spectrum of MWCNTs. MWCNTs have been decorated by Cu nanoparticles and their photoresponse has been studied and compared with that of bare nanotubes. The quantum efficiency of the hybrid system increases over the entire spectrum and two models have been proposed to explain these results. Finally, a first measurement of the performance of a MWCNTs/SiO2/Si device as PV cell has been performed by using a solar simulator. The I-V characteristic under illumination is not the expected well-shaped curve of a PV cell, but it demonstrates that the MWCNT solid-state device can operate as an active power supply element under solar illumination.
Zuo, Yong. "Nanostructured Metal Sulfides for Electrochemical Energy Conversion." Doctoral thesis, Universitat de Barcelona, 2020. http://hdl.handle.net/10803/670925.
Full textEn esta tesis, se produjeron y optimizaron cuatro catalizadores nanoestructurados basados en Cu2S y SnS2 para mejorar su rendimiento hacia la conversión de energía electroquímica. El Capítulo 1 presentó una introducción general para explicar la motivación del tema de tesis. En el capítulo 2, las matrices de las nanovarillas de Cu2S se sintetizaron in situ sobre un sustrato de cobre metálico para la reacción electroquímica de evolución de oxígeno (OER). Se aplicaron herramientas de caracterización adecuadas para investigar la transformación en la operación OER, durante la cual las matrices iniciales de las nanovarillas Cu2S in situ cambió a nanohilos de CuO. En particular, el CuO derivado de Cu2S mostró un rendimiento de OER significativamente mejor cuando comparado al de CuO preparado mediante el recocido. En el capítulo 3, se detalló un proceso basado en una solución de inyección en caliente para producir nanoplacas ultrafinas SnS2 (NPL). Posteriormente, se cultivóPt en su superficie mediante la reducción in situ de una sal de Pt. Posteriormente se probó el rendimiento fotoelectroquímico (PEC) de los fotoanodes hacia la oxidación del agua. Los fotoanodes de SnS2-Pt optimizados proporcionaron densidades de fotocorriente significativamente más altas que el SnS2 desnudo (seis veces). Se analizó el efecto de Pt. En el capítulo 4, se informó una tinta molecular simple para cultivar capas de SnS2 nanoestructuradas directamente sobre sustratos conductores. Tales capas nanoestructuradas en FTO se caracterizaron por excelentes densidades de fotocorriente. Se utilize la misma estrategia para producir compuestos de grafeno-SnS2, recubrimientos ternarios SnS2-xSex, capas de SnSe2 de fase pura e incluso polvo de SnS2 a gran escala. En el capítulo 5, el SnS2 nanoestructurado con diferentes morfologías se probaron como ánodos LIB en primer lugar para encontrar que los NPL de SnS2 delgados proporcionaban el mayor rendimiento. Posteriormente, se desarrolló una estrategia de síntesis coloidal para cultivar los mismos NPL de SnS2 dentro de una matriz de g-C3N4 (CN) poroso y placas de grafito (GP) y se probaron para la aplicación LIB. Tales compuestos jerárquicos SnS2/CN/GP mostraron excelentes propiedades electroquímicas, lo que se atribuye a la sinergia creada entre los tres componentes como se investigó.
Neves, Marcus Godolphim de Castro [UNESP]. "Estudo da viabilidade de implantação de plantas para conversão de energia térmica do oceano (OTEC) no Brasil." Universidade Estadual Paulista (UNESP), 2015. http://hdl.handle.net/11449/124434.
Full textAtualmente, a busca por novas fontes de energias renováveis tem sido o motivo de pesquisas e investimentos, sendo que a possibilidade de exploração da energia dos oceanos pode ser uma interessante alternativa. Um desses processos é baseado na extração da energia térmica solar acumulada na superfície dos oceanos. Parte dessa energia pode ser transformada em eletricidade e em vários outros subprodutos por meio de um processo conhecido como Conversão da Energia Térmica dos Oceanos (OTEC), que utiliza a água fria obtida a partir de uma profundidade de 1.000 m. As usinas OTEC podem operar em sistemas térmicos aberto, fechado ou híbrido, sendo que, para operar de forma adequada, o local de instalação da usina OTEC deve ter águas com temperatura média da superfície maior que 24 °C. O Brasil possui várias regiões que atendem esta condição sendo, portanto, um dos países com boa capacidade de instalação de usina OTEC para ajudar a suprir sua demanda energética. Este trabalho apresenta o estudo de viabilidade termodinâmica, termoeconômica e econômica de instalação de uma usina OTEC no Brasil por meio de simulações numéricas de seis casos de ciclos fechados, sendo cinco deles com um estágio (três com coletores solares e dois sem); e um caso com dois estágios, sem coletor solar. Os resultados mostraram que a planta com dois estágios não se mostrou viável. No entanto, observou-se que uma usina com ciclo fechado, com um estágio, é capaz de produzir de 13 a 19 MW, dependendo do caso, com custo entre R$ 0,55 (com coletor) e R$ 0,65 (sem coletor) por kW. Esse valor é inferior ao custo da energia produzida por motores estacionários a Diesel, de modo que essa tecnologia pode ser uma alternativa viável e sustentável para substituição dessa forma de geração de eletricidade no nordeste do Brasil, sendo também capaz de produzir água dessalinizada e sal
The search for new sources of clean renewable energy has been the subject of current research and investment, and the possible exploration of oceanic processes may be an interesting alternative. One of these processes is based on extraction of the solar thermal energy accumulated in the ocean upper layer. A fraction of this energy can be converted into electricity and various byproducts by means of a conversion process known simply as Ocean Thermal Energy Conversion (OTEC), which uses the cold water gotten from a depth of 1,000 m. OTEC plants operate in three distinct thermal cycles: open, closed and hybrid. To operate in an adequate form, the local of installation of an OTEC plant must have the sea's average surface temperature greater than 24 oC. Brazil has several offshore regions with these conditions, being one of the countries with good capacity to install OTEC plants to help to supply the electrical and energy demands. This work presents the study of thermodymanic, thermoeconomic and economic feasibility to install an OTEC plant in Brazil through numerical simulation of six cases of closed thermal cycles of an OTEC plant, being five of them with one stage (three with and two without solar boosters); one case with two stages and none solar booster. The results have shown that the two-stage plant has not been feseable. However, the one-stage closed cycle plants are able to produce between 13 to 19 MW, depending on the case considered, with cost between R$ 0,55 (with solar booster) and R$ 0,65 (without solar booster) per kW. These values is lower than the energy cost produced by Diesel stationary engines, so that this technology may be a feseable and sustainable alternative to replace this kind of power generation in Brazilian Northeast region, being able to produce fresh water and salt too
Neves, Marcus Godolphim de Castro. "Estudo da viabilidade de implantação de plantas para conversão de energia térmica do oceano (OTEC) no Brasil /." Ilha Solteira, 2015. http://hdl.handle.net/11449/124434.
Full textCo-orientador: Cassio Roberto de Macedo Maia
Banca: Emanuel Rocha Woiski
Banca: Mauro Conti Pereira
Resumo: Atualmente, a busca por novas fontes de energias renováveis tem sido o motivo de pesquisas e investimentos, sendo que a possibilidade de exploração da energia dos oceanos pode ser uma interessante alternativa. Um desses processos é baseado na extração da energia térmica solar acumulada na superfície dos oceanos. Parte dessa energia pode ser transformada em eletricidade e em vários outros subprodutos por meio de um processo conhecido como Conversão da Energia Térmica dos Oceanos (OTEC), que utiliza a água fria obtida a partir de uma profundidade de 1.000 m. As usinas OTEC podem operar em sistemas térmicos aberto, fechado ou híbrido, sendo que, para operar de forma adequada, o local de instalação da usina OTEC deve ter águas com temperatura média da superfície maior que 24 °C. O Brasil possui várias regiões que atendem esta condição sendo, portanto, um dos países com boa capacidade de instalação de usina OTEC para ajudar a suprir sua demanda energética. Este trabalho apresenta o estudo de viabilidade termodinâmica, termoeconômica e econômica de instalação de uma usina OTEC no Brasil por meio de simulações numéricas de seis casos de ciclos fechados, sendo cinco deles com um estágio (três com coletores solares e dois sem); e um caso com dois estágios, sem coletor solar. Os resultados mostraram que a planta com dois estágios não se mostrou viável. No entanto, observou-se que uma usina com ciclo fechado, com um estágio, é capaz de produzir de 13 a 19 MW, dependendo do caso, com custo entre R$ 0,55 (com coletor) e R$ 0,65 (sem coletor) por kW. Esse valor é inferior ao custo da energia produzida por motores estacionários a Diesel, de modo que essa tecnologia pode ser uma alternativa viável e sustentável para substituição dessa forma de geração de eletricidade no nordeste do Brasil, sendo também capaz de produzir água dessalinizada e sal
Abstract: The search for new sources of clean renewable energy has been the subject of current research and investment, and the possible exploration of oceanic processes may be an interesting alternative. One of these processes is based on extraction of the solar thermal energy accumulated in the ocean upper layer. A fraction of this energy can be converted into electricity and various byproducts by means of a conversion process known simply as Ocean Thermal Energy Conversion (OTEC), which uses the cold water gotten from a depth of 1,000 m. OTEC plants operate in three distinct thermal cycles: open, closed and hybrid. To operate in an adequate form, the local of installation of an OTEC plant must have the sea's average surface temperature greater than 24 oC. Brazil has several offshore regions with these conditions, being one of the countries with good capacity to install OTEC plants to help to supply the electrical and energy demands. This work presents the study of thermodymanic, thermoeconomic and economic feasibility to install an OTEC plant in Brazil through numerical simulation of six cases of closed thermal cycles of an OTEC plant, being five of them with one stage (three with and two without solar boosters); one case with two stages and none solar booster. The results have shown that the two-stage plant has not been feseable. However, the one-stage closed cycle plants are able to produce between 13 to 19 MW, depending on the case considered, with cost between R$ 0,55 (with solar booster) and R$ 0,65 (without solar booster) per kW. These values is lower than the energy cost produced by Diesel stationary engines, so that this technology may be a feseable and sustainable alternative to replace this kind of power generation in Brazilian Northeast region, being able to produce fresh water and salt too
Mestre
Yuen, Katarina. "System Aspects of Marine Current Energy Conversion." Licentiate thesis, Uppsala University, Electricity, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-113339.
Full textFree-flowing water currents such as tides and unregulated water courses could contribute to world electricity production given the emergence of robust technical solutions for extracting the energy. At Uppsala University, a concept for converting water currents to electricity using a vertical axis turbine with fixed blade pitch and a direct drive permanentmagnet generator is studied. A system approach is desired, and in this thesis, a first analysis of two system components, the generator and the turbine, is presented. This thesis also deals with some issues concerning the design and construction of a low speed generator for this application. An experimental generator for verification of simulations has been designed and constructed. For the electromagnetic design, a FEM simulation tool has been used. The construction work has given valuable practical experience concerning for example handling permanent magnets and winding the generator with cable. Simulations and measurements of the experimental generator have been carried out for different speeds and loads. The generator can operate at the speeds and loads corresponding to maximum power capture for different turbines for water current velocities between approximately 0.5 and 2.5 m/s. At higher water current velocities the turbines may need to be run at a tip speed ratio that gives a lower power capture in order to limit the electrical currents in the generator, cavitation of the blades, or mechanical loads. Comparisons of measurements and simulations show an agreement. The FEM simulation tool can be used to simulate and design electrical machines with a low electrical frequency, i.e. 2–16 Hz.
Grabbe, Mårten. "Marine Current Energy Conversion : Resource and Technology." Licentiate thesis, Uppsala University, Electricity, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-113365.
Full textNyhlén, Erik. "Control of marine current energy conversion system." Thesis, Uppsala University, Electricity, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-129988.
Full textThis thesis involves the development of a system for control of a marine current energy conversion system. The control system is developed on the principles of load control, i.e. it aims to control the rotational speed of the turbine by controlling the power extracted from the generator. The system operates by feedback of the generator DC-voltage and current as well as the speed of the water current passing through the turbine. An IGBT-transistor controlled by an AVR-microcontroller executes control of the generator and hence the turbine. A digitally implemented PID-controller serves as the fundamental automatic control regime. The control system can be operated from a PC-application connected to the microcontroller through a serial wire connection. From the graphical user interface ofthe PC-application the system operator can set the system control parameters and monitor the state of the generator and turbine. The control system can be set to keep the turbine operating at a desired tip speed ratio, rotational speed or generator voltage. Further, for purposes of indoor testing of the control system a separate system, a motor control system, was developed as a part of this thesis work. The purpose of the motor control system is to enable simulating the behavior of a turbine with a motor driving the generator instead of an actual turbine. The motor control system operates by control of an ACS800 variable frequency drive that is connected to the motor. The motor control system allows its operator to feed in data describing the variations in water speed over time as well as data describing how the simulated turbine's power coefficient depends on its tip speed ratio. From this data the motor control system continuously calculates the torque that should be put on the generator axis by the motor. Results from test runs of the system show that the performance of the system is good. The system responds quickly to changes in the control parameters. Also the system manages to keep the specified control parameter quite well even during rapid changes in the water speed.
Ekeström, Anton. "Sustainable energy conversion in ruralareas in Cuba." Thesis, KTH, Energiteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-99019.
Full textYuen, Katarina. "System Perspectives on Hydro-Kinetic Energy Conversion." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-181555.
Full textZhu, Qirong. "Modular polyoxometalate architectures for solar energy conversion." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066437.
Full textIn this work, the main objective were to understand the electronic processes of polyoxometalates solid films at an indium tin oxide interface. A well-organized polyoxometalate film was deposited onto ITO and with an appropriate annealing process a highly ordered conductive surface was observed. The anisotropic morphology has been proved to be able to optimize electrical/electronic properties and further improve hole transport in organic photovoltaic devices by inserting as anode interfacial layer. We demonstrated the conductivity took place at the outer shell of the polyoxometalate due to oxygen vacancies which generate very localized gap state. We pursue the study by investigating the counter-ions (K+, Li+ and H+) effect on the identical polyoxoanion [P2W18O62]6-. We show it can not only influence the film aggregation mechanism, but allow tuning the density of gap states. The substitution of tungsten, especially by molybdenum, result in a more favorable energy level alignment from ITO and P3HT, i.e. desirable position and higher density of gap states. In a last we integrated the polyoxometalate in organic solar cells to prove the previous demonstration
Basta, Marek. "Low energy photovoltaic conversion in MIND structures." Thesis, Strasbourg, 2013. http://www.theses.fr/2013STRAD019/document.
Full textPhotovoltaic devices of today convert solar energy into electricity in a clean, renewable and inexhaustible way and represent a possible replacement for the fossil fuels. However, in order to compete with classical energy sources a significant increase in the conversion efficiency is inevitable. In this work, we concentrate on the aspects able to raise the conversion efficiency above the limitations of present cells. The first part of the study is devoted to new theoretical ideas considered as 3rd generation photovoltaics, while the most interest is kept at studying the possible benefits of electron multiplication at low-energies. In the second part of the study, we develop a model that allows a precise treatment of optical and transport properties of silicon structures with buried interfaces. Extensive theoretical and experimental analyses of existing MIND structures are then conducted. By studying the exact flux and power distribution inside several structures in conjunction with their geometry, we estimate the possible quantum efficiencies and compare them with experimental results. Through the means of numerical simulations coupled with experimental characterization, we extract the carrier collection efficiency of studied cells. New effects are being observed, such a possible increase in collection efficiency above unity. A deeper analysis of the experimental results coupled with the numerical study analyzes several classical and non-classical explanations of the increase in collection efficiency or the resulting increase in the quantum efficiency. With most of the classical explanations ruled out, we conclude that the most probable, but not definitiveexplanation of this effect can be interpreted as the result of a low-energy carrier multiplication
Warner, John M. "Wave energy conversion in a random sea." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ31537.pdf.
Full textThomas, Karin. "Low Speed Energy Conversion from Marine Currents." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8400.
Full textGrabbe, Mårten. "Hydro-Kinetic Energy Conversion : Resource and Technology." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-195942.
Full textLin, Ziyin. "Functionalized graphene for energy storage and conversion." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/51871.
Full textMichas, Marios. "Control of turbine-based energy conversion systems." Thesis, Cardiff University, 2018. http://orca.cf.ac.uk/117586/.
Full textALMEIDA, SILVIO CARLOS ANIBAL DE. "DIRECT CONVERSION OF THERMAL ENERGY INTO ELECTRICAL." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1987. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=33281@1.
Full textO presente trabalho descreve o desenvolvimento de um gerador termoelétrico cujos termoelementos são obtidos a partir de um composto de dissiliceto de ferro (FeSi2). A originalidade do trabalho reside na simplificação do processo de obtenção do termoelemento e na utilização de matérias-primas com grau de pureza industrial, em contraposição aos processos usuais que utilizam materiais de custo elevado, com alto grau da pureza e sofisticados processos de fabricação. O composto é obtido pelo processo de fusão num forno de indução à vácuo. A forma geométrica do termoelemento é assegurada pelo processo de sinterização. Um processo de recozimento garante a formação da fase Beta, assegurando a existência das propriedades termoelétricas. O coeficiente de Seebeck mostrou-se dependente do tempo de recozimento. Para os materiais desenvolvidos, o termoelemento tipo P apresentou um coeficiente de Seebeck de 250 MV/K e o material tipo N, um coeficiente de 75 MV/K, valores estes que qualificam o material para construção de geradores termoelétricos. Estima-se que o custo de fabricação do material desenvolvido reduziu de oito para dois dólares o custo de fabricação de materiais termoelétricos por watt de eletricidade gerado. Experiências preliminares utilizando a técnica de serigrafia para fabricação de termoelementos parecem confirmar a possibilidade de uma redução ainda maior do custo de fabricação.
This work describes the development of a thermoelectric generator whose thermoelements are made of a new thermoelectric material, FeSi2, an iron disilicide alloy. The originality of this work relies on the simplicity of the process by which the termoelements are obtained and also on the possibility to use a raw material with industrial purity grade, as opposed to conventional techniques which use costly materials, with a high degree of purity, and sofisticated process of fabrication. The alloy is obtained by a process of fusion in a vacuum induction type furnace. The geometric shape of the thermoelement is obtained by a process of sinterization. An annealing process garantees the formation of the Beta phase, thus assuring the existence of thermoelectric propertyes. The Seebeck coefficient proved to be dependent on the time duration of the annealing. As for the material developed, the P Type material presented an average Seebeck coefficient of 250 MV/K and the N type material, a coefficient of 75 MV/K, these figures qualify the materials for construction of thermoelectric generators. It is estimated that the manufacturing cost of the material developed reduced the cost of thermoelectric materials per watt of electricity generated from eight to two dollars. Preliminary experiments using the silk-scream technique in manufacturing of thermoelements seems to promise an even greater reducting in the manufacturing costs.
Altalhi, Amal A. "Energy conversion and storage via photoelectrochemical methods." Thesis, University of Hull, 2013. http://hydra.hull.ac.uk/resources/hull:16512.
Full textJo, Won Jun. "Solar energy conversion via photovoltaics and photocatalysis." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111409.
Full textCataloged from PDF version of thesis.
Includes bibliographical references.
Due to the forthcoming shortage of natural resources, the demand for more efficient and ecofriendly chemical processes for the conversion of energy and matter, especially with respect to carbon management, is growing rapidly. Therefore, a search for high-performance solar energy conversion systems to end the current carbon economy era is of paramount importance in both academic and industrial sectors. In this regard, we have studied organic photovoltaics and solar water splitting by using oCVD (Oxidative Chemical Vapor Deposition) polymers and doping-treated bismuth vanadate (BiVO 4), respectively. oCVD is a solvent-free conformal vacuum-based technique to enable thin-film fabrication of insoluble polymers at moderate vacuum (~ 0.1 Torr) and low temperature (25 150 °C). Moreover, oCVD carries the well-cited processing benefits of vacuum processing, such as parallel and sequential deposition, well-defined thickness control, large-area uniformity, and inline integration with other standard vacuum processes (e.g., vacuum thermal evaporation). Based on the above-mentioned technical advantages from oCVD, polyselenophene and poly(3,4- dimethoxythiophene) have been successfully applied to organic photovoltaics. Cost-effective solar hydrogen production requires catalytic materials that have earth-abundant element composition, suitable photoelectrochemical properties, and broad technological applicability. To create this versatile catalytic material, controlling the catalyst's atomic structure is of primary importance since their functionalities (e.g., electronic band structure, catalytic activity, chemical stability, etc.) are governed by its atomic structure. According to the strategy, BiVO 4's atomic structure has been engineered via phosphorus, indium and molybdenum doping. The improved photocatalytic behavior of doping-treated BiVO4 has been studied within experimental and computational domains.
by Won Jun Jo.
Ph. D.
Ansovini, Davide. "Catalysis for sustainable energy conversion and storage." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/413468/.
Full textAfzal, Muhammad. "Nanocomposite Materials for New Energy Conversion Device." Thesis, KTH, Materialvetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-122675.
Full textBardagot, Olivier. "N-type organic semiconductors for energy conversion." Thesis, Université Grenoble Alpes (ComUE), 2019. https://thares.univ-grenoble-alpes.fr/2019GREAV027.pdf.
Full textAt a time when the impacts of climate change have become undeniable, the development of low-carbon energies is crucial. Potentially low cost compared to established technologies, emerging organic technologies offer an eco-efficient alternative for harvesting solar and thermal (< 473 K) energies. In the first chapter, the advantages and drawbacks of the different technologies currently being developed are discussed. Photovoltaic devices, like thermoelectric devices, require two types of materials conducting holes (p type) and electrons (n-type) respectively. Despite remarkable advances, the development of n-type semiconductors represents a major lever for improving organic technologies. In this context, this doctoral work presents the design, synthesis, characterization and device developments of innovative pi-conjugated n-type polymers and small molecules.Based on three electron-accepting units – isoindigo (ISI), naphthalene diimide (NDI) and fluorinated benzodifurandione-oligo(p-phenylenevinylene) (FBDOPV) – the design and synthesis of alternated copolymers are presented in the second chapter. These polymers exhibit high electron affinities ranging from 3.5 eV to 4.1 eV. DFT modelling and thin-film X-ray diffraction studies allowed to identify the main structural aspects leading to electron mobility as high as 0.26 cm2.V 1.s 1 achieved in organic field effect transistors.For thermoelectricity, molecular doping of these organic semiconductors is required. It is the subject of the third chapter. The necessary conditions for thermo- and photo-activation of N DMBI dopant have been identified. In particular, the degradation of the activated dopant in the presence of oxygen has been demonstrated by single crystal X-ray diffraction. Each polymer and two small molecules based on ISI and NDI cores have successfully being doped. The doping mechanisms and conductivities obtained are discussed on a case by case basis using UV-Visible-Near-Infrared and Electron Paramagnetic Resonance spectroscopies. In particular, conductivities in the range of 10-4 S.cm-1 were obtained without external energy supply neither before nor after deposition. Encouraging conductivities in the range of 10-3 S.cm 1 for a small molecule based on NDI and 10-2 S.cm 1 for a polymer based on FBDOPV have been achieved. The stability and reversibility of thin film conductivities when exposed to air were investigated and correlated to the LUMO level of the materials. The thorough control of deposition and doping conditions have afforded to achieve a power factor of about 0.3 µW.m-1.K-2 associated to a thermal conductivity of 0.53 W.m 1.K 1. Figure of merits of approximately 2.10-4 at 303 K and 5.10-4 at 388 K have been obtained, which represent the first values reported to date for an n-doped organic semiconductor measured on a single device.These materials also allow the replacement of fullerene derivatives in photovoltaic devices as presented in the last chapter. In particular, they demonstrate strong absorption properties, extended to the near infrared domain for one of the polymers. A conversion efficiency of 1.3% was obtained in all polymer bulk-heterojunction solar cell before optimization. Following the donor-spacer-acceptor approach, two ITIC derivatives have been designed and characterized. The modification of alkyl substituents on the spacer provides improved absorption and molecular packing properties compared to ITIC. High open-circuit voltages up to 1.10 V and conversion efficiencies of 4.2% have been achieved with these non-fullerene acceptors
Hosomizu, Kohei. "Photoactive molecular assemblies for solar energy conversion." 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/136306.
Full textZou, Yu. "Supported Composite Electrocatalysts for Energy Conversion Applications." Thesis, Griffith University, 2022. http://hdl.handle.net/10072/417198.
Full textThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
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Baniasadi, Mahsa <1986>. "Thermal Processes for Biomass to Energy Conversion." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7493/1/Mahsa_Baniasadi-Thesis.pdf.
Full textBoni, Alessandro <1987>. "Electrochemistry of Nanocomposite Materials for Energy Conversion." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7510/1/boni_alessandro_tesi.pdf.
Full textGuerrero, Felipe Martinez. "Development of a wave energy basin to maximize wave energy conversion." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20241.
Full textSagaidak, Iryna. "Bi-functional materials combining energy storage and energy conversion from sunlight." Thesis, Amiens, 2019. http://www.theses.fr/2019AMIE0025.
Full textThe problem of intermittent nature of solar energy is often addressed by the traditional coupling of the PV and battery units. Our more fundamental approach targets the development of materials able to combine solar energy conversion and storage at the molecular level. The 5 nm anatase TiO2 nanocrystals were synthesized in our group affording a quantitative photorecharge reaction by a sole contribution of illumination. Here, we present a study of the evolution of the optoelectronic properties and dynamics of charge transfer in TiO2 electrode using in situ / in operando experiments performed during the battery functioning (UV-visible, Mott-Schottky, fluorescence spectroscopy). The increase of the bandgap value and the rise of absorbance are observed upon lithium insertion into TiO2. A negative shift of the conduction band indicates a more oxidizing potential of the photogenerated holes in Li0.6TiO2 compared to TiO2. By analysis of the recombination processes in TiO2 upon lithium insertion, we established a competition of the ultra-fast (ps range) processes of direct recombination and charge transfer towards Ti3+ in Li0.6TiO2, potentially limiting the yield of the photorecharge reaction. This study was extended to other insertion materials typically used in lithium-ion batteries (Li4Ti5O12, LiCoO2, LiFePO4, MoO3, etc.). The measured band edge positions, band gap, charge carrier type and concentration were gathered into a database, based on which the fundamental evaluation of the possibility of the light-induced photorecharge was conducted. The first results of the photoelectrochemical study of chosen materials are also discussed
Oh, Sang Joon. "Electromagnetics of inertial energy storage systems with fast electromechanical energy conversion /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
Full textConceição, Ricardo Filipe Carrão da. "Soiling in solar energy conversion technologies: assessment and mitigation." Doctoral thesis, Universidade de Évora, 2019. http://hdl.handle.net/10174/25527.
Full textCarter, Jesse James. "Analysis of a direct energy conversion system using medium energy helium ions." Texas A&M University, 2005. http://hdl.handle.net/1969.1/3790.
Full textWang, Huizhi, and 王慧至. "Electrochemical conversion of aluminum energy: energy efficiency, co-production concept and systemcharacteristics." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B4697040X.
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