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Providing an energy efficient recycle for the Teflon® synthesis process is of great interest due to environmental and economic reasons. This recycle step involves separating CO2 from a stream containing scCO2 and valuable monomer (C2F4). Membranes provide economical and environmental friendly separations compared to conventional methods (e.g. distillation, amine absorption). Therefore, I am investigating membrane materials that are well-suited for this important separation. Developing a robust membrane that can withstand the aggressive scCO2 environment (~1070 psi of CO2) is a key challenge. Supercritical CO2 swells traditional polymeric membrane materials, thereby increasing segmental mobility of the polymer chains which leads to a decrease in separation capacity. There have been no polymeric membrane materials identified in the literature which are suitable for this separation. In this work, I have identified an advanced polymer, Torlon® (a polyamide-imide), that solves this problem. After determining the appropriate material, it is important to choose a membrane morphology that is industrially desirable. The asymmetric hollow fiber membrane morphology provides the highest productivity. I have successfully produced defect-free asymmetric hollow fiber membranes using Torlon® that withstand high pressure feeds. These membranes have been shown to provide selective separations under scCO2 conditions without being plasticized. To further improve the separation performance of Torlon® membranes, mixed matrix concept was explored. Zeolite 4A, which is relatively more permeable and selective compared to Torlon®, was chosen as the sieve material. Mixed matrix membranes from Torlon® and zeolite 4A were made and their separation performance was measured. Based on these experimental measurements and Maxwell modeling, challenges in making successful mixed matrix membranes were identified and feasible solutions for these challenges are suggested.

The effectiveness of the heat transfer in a geothermal reservoir strongly depends on its temperature, pressure and rock type. A porous and fractured rock is essential to provide a hot fluid circulation to a geothermal power plant. Velocity anomalies in seismic tomography may relate to the location of a fluid reservoir, hydrothermal systems, and possible heat sources. However, the subsurface properties like porosity, fracture density, and fluid state (e.g liquid, gas or supercritical fluid) cannot be inferred directly using seismic tomography. The inversion of seismic data can be combined with an effective medium model (EMM) to investigate such rock and subsurface properties. In the present study, we implement an EMM involving elastic rock properties and the following descriptions of inclusions: pore porosity, fracture density, fracture aspect ratio, fracture porosity, and liquid ratio. The chosen EMM was reproduced from the work of Adelinet et al. (2011a) and Adelinet (2010). Tomographic results were inverted for the same geographic area (Krysuvik in Iceland) in order to validate our method and to confirm the presence of the supercritical fluid reservoir. We re-evaluate the assumptions and constraining parameters choice of the inverse model used in Adelinet et al. (2011a) and Adelinet (2010), in order to 1) get a better understanding of the underlying problems, 2) investigate the sensitivity of the results based on the constraining parameters, 3) produce suitable workflows, and 4) build an adaptive method for geothermal exploration in different areas. The newly implemented method found the same qualitative results in Krysuvik as Adelinet et al. (2011a). Namely, at ≈ 6.5 km depth both values of fracture density and of liquid ratio are consistent with hydraulic fracturing and a probable super-critical fluid reservoir. Afterwards, the method was applied to the Hengill volcanic complex. Fracture density and liquid ratio values similar to those observed at Krysuvik and associated to a geothermal reservoir were obtained at Hengill at the exact location of existing production sites. Our results also showed limitations of initial assumptions and could contribute to improve the method. This study could be a starting point to build a more sophisticated tool for geothermal exploration. / Idag består majoriteten av världens energiproduktion av fossilt bränsle. Naturgas, kol och olja stod tillsammans för 70% av världens energiproduktion 2010 och det ökar konstant trots nödvändigheten att minska koldioxidutsläppen. Geotermisk energi är en hållbar resurs men bidrar endast med mindre än 2% av världens energi. Det finns dock undantag, exempelvis på Island där 70% av all energi som förbrukas kommer från geotermiska resurser. Island är en seismiskt aktiv region som inkluderar diverse olika geotermiska områden med hög temperatur. På grund av detta, har det där skett mycket forskning om geotermiska resurser. Vidare information är nödvändig för att utforska potentialen av att nyttja geotermisk energi. I denna studie impementerades en metod som kombinerar seismiska hastigheter och teoretiska mekaniska egenskaper av stenar, exempelvis stenbrottsgeometri. Metoden tillåter att uttyda egenskaper under ytan, framförallt tätheten av sprickor och det fysiska tillståndet av vätskan. Dessa egenskaper kan bidra med relevant information för beslutstagande och är nödvändiga för att lyckas med borrning. En optimering av mätna och teoeriska värden var beräknad för att hitta de optimala värdena av spricktäthet och det fysiska tillståndet av vätskan. Studien fokuserar huvudsakligen på två geotermiska områden på Island, Krysuvik- och Hengill-vulkanernas områden. Resultat erhållna från Krysuvik konfimerade en möjlig superkritisk vätskereservoar på ettdjup av 5.5-6.5 kilometer. Efter att ha studerat Hengill-området, uppkom resultat på den geotermiska utvinningsplatsen men det visade även begränsningar kring metoden. Metoden behöver förbättras och anpassa sig till funktionen av området. Heterogeniteten och de komplexa egenskaperna (till exempel bergskomposition eller vätskealternering) under ytan ledde till omvärdering av antaganden gjorda i den initiala mediummodellen.

It is important for practical and legal reasons that water and sediments in disturbed areas around the mining operation should be controlled. The construction of a well-designed drainage system that controls erosion and thus restores the proper hydraulic function of the surface is one of the most important post-disturbance features which should be done as part of the mining activities. However, even with the best planning and design, unless proper construction practices are adapted; both the disturbed and reclaimed areas are very much likely to be susceptible to erosion, sedimentation and stability problems. In order to tackle the problem, guidelines on how to design and construct the drainage system should be well prepared. The main objective of this study was to prepare guidelines for the proper design, construction and monitoring of the water drainage management system in the study areas (Kankberg, Maurliden and Renström-Petiknäs). This report has analysed the results from the outcome of HEC-RAS software for the case study of the new ditch around the Maurliden mine site and integrated with different guidelines. Based on the results of the HEC-RAS, the most common problems in the drainage system have been identified. Moreover the thesis project identified important physical parameters such as cross-sections and slopes of the representative ditch which affect the function of the ditch in the study areas. Hydraulic parameters such as velocity which is very important for designing the type of lining and also Froude number which is very important in identifying the type of flow whether it is super-critical, critical or sub-critical were identified. The latter helps to select the type of guideline to be used between steep slope and mild slope.

The global need to eliminate CO2 emissions and its consequent reduction in the use of fossil fuels drives the ongoing energy transition that highly involves the research achievements of the scientific community to reach the goals of this purpose. Renewable sources like photovoltaic and wind energy, are central to this endeavor, however, the intermittency of natural resources makes it non-dispatchable and energy storage is fundamental. According to the European Roadmap [1] just a 60% of the CO2 emissions reduction goal can be achieved with available technologies and existing energy. However, the production, use and specially storage opportunities that hydrogen offers can drive non-dispatchable renewable sources to achieve its full potential by clearing up the intermittency problem as well as covering the remained 40% gap. This master's thesis aims to investigate the techno-economic feasibility of integrating a Solid Oxide Electrolyzer Cell (SOEC) into a hybrid PV-CSP(sCO2) plant. The study focuses on assessing various indicators related to electricity, energy, and hydrogen production prices. To achieve this, three different integration strategies within the hybrid PV-CSP(sCO2) plant were selected for analysis: Soec using heat from the particles coming from the receiver, soec using heat coming from the particles available in the thermal energy storage (TES) and soec recovering heat from the sCO2 power block. A sensitivity analysis was conducted on different PV sizes (MWp), battery capacities (MWh), and SOEC installed capacities (MWh) to investigate the technology's potential in the plant and determine optimal sizing of subsystems. However, the individual optimization of economic indicators presented technical and economic challenges. Scenarios allowing individual optimization of hydrogen production prices (€/kg H2) resulted in 10.9, 11.7, and 14.6 €/kg h2 for receiver, TES, and sCO2 integration strategy, respectively. These scenarios, however, require high SOEC installed capacities, leading to elevated electricity and energy production prices. On the other hand, the individual optimization of electricity and energy production prices led to better and lower results when no hydrogen production presence within the plant. However, this analysis also showed that soec capacities below 5MWh together with no installation of batteries and a new definition for calculating hydrogen production prices (LCOH) allows feasible integration of hydrogen production within the plant. LCOH(€/kg h2) results were 10.2€/kg h2, 7.6€/kg h2, and 9.4€/kg h2 for receiver, TES, and sCO2, respectively, for a soec installed capacity of 0.5MWh (119m2 size) along with energy production values not exceeding 101€/MWh. While the results present a favorable outlook for SOEC installations based on literature review data [2] [3] [4] they still face challenges when competing with the cost-efficient PEM technology, which offers 4.5-5.5€/kg H2 [5] without storage. Nonetheless, this research contributes valuable insights into the integration of SOEC technology within hybrid renewable energy systems and provides a comprehensive analysis of the techno-economic aspects related to hydrogen production following different integration strategies. The findings may inform decision-making processes and promote further advancements in sustainable energy solutions. / Det globala behovet av att eliminera CO2utsläpp och därmed minska användningen av fossila bränslen driver pågående energiomställning, som starkt involverar forskningsresultaten från vetenskapssamhället för att nå syftet med detta mål. Förnybara källor som solceller och vindkraft är centrala i detta arbete, men intermittensen hos naturliga resurser gör dem icke disponibla och energilagring är grundläggande. Enligt den europeiska vägkartan [1] kan endast 60% av målet att minska CO2-utsläppen uppnås med tillgängliga teknologier och befintlig energi. Produktionen, användningen och särskilt lagringsmöjligheterna som väte erbjuder kan emellertid driva icke-disponibla förnybara källor att nå sin fulla potential genom att lösa intermitt ensproblemet och täcka den återstående 40% klyftan. Detta examensarbete syftar till att undersöka den tekniskekonomiska genomförbarheten av att integrera en fastoxid elektrolysör (SOEC) i en hybrid PV CSP(sCO2)-anläggning. Studien fokuserar på att utvärde ra olika indikatorer relaterade till el-, energi- och vätgasproduktionspriser. För att uppnå detta har tre olika integrationsstrategier inom hybrid PV CSP(sCO2) anläggningen valts för analys: SOEC med hjälp av värme från partiklar som kommer från mottagaren, SOEC med hjälp av värme från partiklar som finns i termisk energilagring (TES) och SOEC som återvinner värme från sCO2-kraftblocket. En känslighetsanalys har genomförts för olika PVstorlekar (MWp), batterikapaciteter (MWh) och SOEC installerade kapacit eter (MWh) för att undersöka teknologins potential i anläggningen och bestämma optimal dimensionering av delsystem. Resultaten från individuell optimering av ekonomiska indikatorer ledde dock till flera tekniska och ekonomiska utmaningar. Scenarier som tillåter individuell optimering av vätgasproduktionspriser (€/kg H2) resulterade i 10, 9, 11, 7 respektive 14,6 €/kg H2 för mottagare, TES och sCO2 integrationsstrategi. Dessa scenarier kräver dock höga SOEC installerade kapaciteter, vilket leder till höga el och energipriser. Å andra sidan ledde individuell optimering av el och energiproduktionspriser till bättre och lägre resultat när ingen vätgasproduktion fanns i anläggningen. Denna analys visade också att SOEC kapaciteter under 5MWh tillsammans med ingen installation av batterier och en ny definition för beräkning av vätgasproduktionspriser (LCOH) möjliggör genomförbar integration av vätgasproduktion i anläggningen. LCOH (€/kg H2) resultaten var 10,2 €/kg h2 , 7 ,6 €/kg h2 respektive 9,4 €/kg h2 för mottagare, TES och sCO2, för en SOEC installerad kapacitet på 0,5 MWh (storlek 119m2) tillsammans med energiproduktionsvärden som inte överstiger 101 €/MWh. Medan resultaten visar en gynnsam utsikt för SOECinstallationer baserat på data från litteraturöversikter [2] [3] [4], står de ändå inför utmaningar när de konkurrerar med den kostnadseffektiva PEM teknologin, som erbjuder 4,5-5,5 €/kg H2 [5] utan lagring. Trots detta bidrar forskningen med värdefulla insikter i integrationen av SOEC teknologi i hybrid förnybara energisystem och ger en omfattande an alys av de teknisk-ekonomiska aspekterna relaterade till vätgasproduktion enligt olika integrationsstrategier. Resultaten kan informera beslutsprocesser och främja ytterligare framsteg inom hållbara energilösningar.

Today’s carbon constrained world with its increasing demand for cheap energy and a fossil fuel intensive fleet of power producers is making carbon capture and storage (CCS) desirable. Several CCS technologies are under investigation by various research and development groups globally. One of the more promising technologies is oxy-fuel combustion, since it produces a CO2 rich flue gas which requires minor processing to meet storage condition requirements. In this study the economics of an advanced super critical oxy-coal power plant burning lignite, simulated in-house was assessed. A robust and user-friendly financial tool box has been developed with commonly acceptable default parameter settings. Capital, operation and maintenance costs were estimated along with corresponding levelized cost of electricity and CO2 avoidance costs calculated using the detailed financial model developed. A levelized cost of electricity of 131 $/MWhrnet along with a levelized CO2 avoidance cost of 64 $/tonne was estimated for an ASC oxy-coal power plant with CO2 capture. Also a levelized cost of electricity of 83 $/MWhrnet was estimated for an ASC air-fired coal power plant without CO2 capture capabilities as the base plant. The price of electricity was observed to increase from 83 $/MWhrnet to 131 $/MWhrnet translating into a 57% increase. The sensitivity of the overall economics of the process was assessed to several parameters. The overall economics was found sensitive to the choice chemical engineering plant cost index (CEPCI), capacity factor, size of power plant, debt ratio, fuel price, interest rate, and construction duration.

Today???s carbon constrained world with its increasing demand for cheap energy and a fossil fuel intensive fleet of power producers is making carbon capture and storage (CCS) desirable. Several CCS technologies are under investigation by various research and development groups globally. One of the more promising technologies is oxy-fuel combustion, since it produces a CO2 rich flue gas which requires minor processing to meet storage condition requirements. In this study the economics of an advanced super critical oxy-coal power plant burning lignite, simulated in-house was assessed. A robust and user-friendly financial tool box has been developed with commonly acceptable default parameter settings. Capital, operation and maintenance costs were estimated along with corresponding levelized cost of electricity and CO2 avoidance costs calculated using the detailed financial model developed. A levelized cost of electricity of 131 $/MWhrnet along with a levelized CO2 avoidance cost of 64 $/tonne was estimated for an ASC oxy-coal power plant with CO2 capture. Also a levelized cost of electricity of 83 $/MWhrnet was estimated for an ASC air-fired coal power plant without CO2 capture capabilities as the base plant. The price of electricity was observed to increase from 83 $/MWhrnet to 131 $/MWhrnet translating into a 57% increase. The sensitivity of the overall economics of the process was assessed to several parameters. The overall economics was found sensitive to the choice chemical engineering plant cost index (CEPCI), capacity factor, size of power plant, debt ratio, fuel price, interest rate, and construction duration.

Made available in DSpace on 2017-07-10T17:59:27Z (GMT). No. of bitstreams: 1 Ana Carolina de Araujo Abdala.pdf: 1086977 bytes, checksum: 3669a77a33625e3d6a3660105a7eb19d (MD5) Previous issue date: 2013-02-15 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The current work aimed to investigate the production of ethyl esters which result from the esterification reactions of oleic acids (AO) and transesterifiction of residual fried oils (ORF), both in supercritical ethanol throught non-catalic method. The experiments were carried out in a packed bead reactor operated in continuous mode. The esterification reactions were carried out under a temperature from 200 to 325ºC, pressure of 15 and 20 MPa and molar reason AO: ethanol in the range of 1:3 to 1:12. From the results on, was possible to note, that the temperature and the pressure influenced positively the conversion on the esterification reaction of oleic acid, with an income of 93, 5%, observed under 325°C and 20Mpa, in a reaction that last 40 minutes. The excess of alcohol in the reactional system didn´t provide significant differences in the conversions, with the optimum molar reason, defined in 1:6 (AO: ethanol). The transesterification reactions, were carried out with pauses of temperatures from 275 to 325ºC, pressure fixed of 20MPa, adopting the mass reason of ORF to ethanol of 1:0.5 and 1:1, varying the residence time, leading the determination of great conditions to the ethyl esters synthesis. Notable results in the alcoholysis reactions were observed at 325ºC, mass ratio of ORF to ethanol at 1:1 and residence time of 40 minutes. Using the molar ratio ORF: ethanol selected as the best suitable, was also evaluated the effect of the water addition to the reactional medium (0, 5 and10% of water relative to the ethanol mass), in order to investigate the technical viability of the use of low quality and costs of the raw materials containing water in the composition. The effect of addition of deco- hexane solvent (0, 5, 10 and 20% of hexane compared to the substrates mass), as well the effect of addition of soy bio-fuel (0, 20 and 40% of soy bio-fuel compared to substrates mass), were also investigated, in order to improve the performance of the reaction. Notable incomes were observed in the reaction with 5% of water addition and 20% of hexane. The best results related to the soy bio-fuel addition to the reactional medium were observed in the reactions carried out with 40% of soy bio-fuel, however, taking into consideration the amount of esters added to the process, the condition considered great was with 20% soy bio-fuel.. From the best conditions of the process, the kinetic daalcoholise super-critical was investigated with the reactions conducted with the residence time from 0 to 70 minutes and the notable results were: 83% in ethyl esters, obtained in 300ºC, 70 minuts of reaction, using 5% of water, 87% in ethyl esters observed in 300ºC, 70minutes of reaction, using 20% of hexane and 82% in ethyl esters obtained in 325ºC, 50 minutes of reaction, using 20% of soy bio-fuel. Lastly, the stability of the daalcoholise reactional medium was investigated. Temperatures of reaction till to 300ºC resulted in decomposition <10% with residence time of 20 minutes. However, the reactions with longer residence time, showed a higher ratio of decomposition of the constituents of the reactional medium. / O presente trabalho teve como objetivo investigar a produção de ésteres etílicos nas reações de esterificação do ácido oleico (AO) e transesterificação de óleo residual de fritura (ORF), ambas em etanol supercrítico pelo método não catalítico. Os experimentos foram realizados em um reator tubular com leito empacotado operado em modo contínuo. As reações de esterificação foram conduzidas com temperatura na faixa de 200 a 325ºC, pressão de 15 e 20 MPa e razão molar AO:etanol na faixa de 1:3 a 1:12. A partir dos resultados, foi possível observar que a temperatura e a pressão influenciaram positivamente a conversão nas reações de esterificação do ácido oleico, com rendimentos de 93,5%, observados a 325ºC e 20 MPa, em 40 minutos de reação. Já o excesso de álcool no sistema reacional não proporcionou diferenças significativas nas conversões, com a razão molar ótima, definida em 1:6 (AO:etanol). As reações de transesterificação foram conduzidas no intervalo de temperatura de 275 a 325ºC, pressão fixa de 20 MPa, adotando razão mássica de ORF para etanol de 1:0,5 e 1:1, variando-se o tempo de residência, possibilitando a determinação das condições ótimas para a síntese de ésteres etílicos. Resultados apreciáveis nas reações de álcoolise foram verificados em 325ºC, razão mássica de ORF para etanol de 1:1 e tempo de residência de 40 minutos. Utilizando a razão mássica ORF:etanol selecionada como a mais adequada, ainda foi avaliado o efeito da adição de água ao meio reacional (0, 5 e 10% de água em relação à massa do etanol), visando investigar a viabilidade técnica da utilização de matérias-primas de menor qualidade e menor custo que contenham água em sua composição. O efeito da adição de co-solvente hexano (0, 5, 10 e 20% de hexano em relação à massa dos substratos) bem como o efeito da adição de biodiesel de soja (0, 20 e 40% de biodiesel de soja em relação à massa dos substratos) também foram investigados, buscando melhorar o desempenho da reação. Rendimentos apreciáveis foram observados nas reações com 5% de adição água e 20% de hexano. Os melhores resultados referentes à adição de biodiesel de soja ao meio reacional foram observados nas reações conduzidas com 40% de biodiesel de soja, porém, levando-se em conta a quantidade de ésteres adicionada ao processo, a condição considerada ótima foi de 20% de adição de biodiesel de soja. A partir das melhores condições de processo, a cinética da álcoolise supercrítica foi investigada com reações conduzidas com tempo de residência na faixa de 0 a 70 minutos e os resultados apreciáveis foram de: 83% em ésteres etílicos, obtidos em 300°C, 70 minutos de reação, utilizando 5% de água, 87% em ésteres etílicos observados em 300°C, 70 minutos de reação, utilizando 20% de hexano e 82% em ésteres etílicos alcançados em 325°C, 50 minutos de reação, utilizando 20% de biodiesel de soja. Por fim, a estabilidade dos componentes do meio reacional da alcoólise foi investigada. Temperaturas de reação de até 300ºC resultam em decomposições <10% com tempo de residência de 20 minutos. Porém, as reações com tempos de residência mais longos, apresentaram taxas de decomposição dos constituintes do meio reacional mais elevadas.

Dans cette thèse, on a d’abord considéré une équation d'onde. On a premièrement montré que l’équation est bien-posée presque sûre par la méthode de décomposition de fréquence de Bourgain sous l’hypothèse de régularité que s > 2(p−3)/(p-1). Ensuite, nous avons réduit de cette exigence de régulation à (p-3)/(p−1) en appelant une estimation probabiliste a priori. Nous considérons également l’approximation des solutions obtenues ci-dessus par des solutions lisses et la stabilité de cette procédure d’approximation. Et nous avons conclu que l’équation est partout mal-posée dans le régime de super-critique. Nous avons considéré ensuite l’équation du faisceau quintique sur le tore 3D. Et nous avons montré que cette équation est presque sûr bien-posée globalement dans certain régimes de super-critique. Enfin, nous avons prouvé que la mesure de l’image de la mesure gaussienne sous l’application de flot de l’équation BBM généralisé satisfait une inégalité de type log-Sobolev avec une petit peu de perte de l’intégrabilité. / In this thesis, we consider a wave equation. We first showed that the equation is almost sure global well-posed via Bourgain’s high-low frequency decomposition under the regularity assumption s > 2(p−3)/(p−1). Then we lowered down this regularity requirement to be (p−3)/(p−1) by invoking a probabilistic a priori estimate. We also consider approximation of the above achieved solutions by smooth solutions and the stability of this approximating procedure. And we concluded that this equation is everywhere ill-posed in the super-critical regime. Next, we considered the quintic beam equation on 3D torus. And we showed that this equation is almost sure global well-posed in certain super-critical regime. Lastly, we proved that the image measure of the Gaussian measure under the generalized BBM flow map satisfies a log-Sobolev type inequality with a little bit loss of integrability.

No description available.