Next generation telecommunication satellites will demand an increasing amount of power in the range of 30 kW or more within the next 10 years. Battery technology that can sustain 30 kW for an eclipse length of up to 72 minutes will represent a major impact on the total mass of the satellite, even with new Li-ion battery technologies. Regenerative fuel cell systems (RFCS) were identified years ago as a possible alternative to rechargeable batteries. Nevertheless, one major drawback was identified by several independent system studies, namely the need to dissipate large amounts of heat from the fuel cell (FC) during eclipse. This in turn requires massive thermal hardware (mainly large radiators) that can contribute up to 50% of the system mass. In order to overcome this issue, the use of metal hydrides (MH) as combined hydrogen and heat storage system was suggested as a starting point of the research presented in this thesis. During eclipse the FC must dissipate waste heat, and at the same time the MH tank must absorb heat in order to desorb hydrogen. Rather than dissipating the waste heat from the FC directly through a radiator, it can be stored solely, or partly, in the MH tank, to be dissipated during Equinox, with a 20 times slower rate, requiring a radiator with significantly less volume and mass. This thesis aims to present the potential of using such MH storage tanks to alternately store hydrogen and waste heat from the FC on-board a spacecraft, investigated by theoretical and experimental means. The model application for the MH tank technology considered in this thesis is a 39 kW telecommunication satellite. Nevertheless, the derived results are to be considered a generic outcome and can be translated or scaled to many other applications. / Es kann davon ausgegangen werden, dass der Trend hin zu Telekommunikationssatelliten mit immer höherer Leistung in den nächsten 10 Jahren zu Satelliten-Plattformen mit 30kW und mehr führen wird. Batterien, welche eine Leistung von 30kW für Eklipse-Längen von 72 Minuten zur Verfügung stellen müssen, werden daher einen immer größeren Einfluss auf die Gesamtmasse des Satelliten haben. Regenerative Brennstoffzellensysteme wurden daher schon vor Jahren als mögliche Alternative zu wieder aufladbaren Batterien untersucht. Mehrere unabhängige Studien sind zu dem Schluss gekommen, dass die größte Problematik in der Einführung von Brennstoffzellensystemen auf Satelliten darin besteht, die relativ großen Mengen an Abwärme effizient abzustrahlen. Die Radiatoren, die hierfür benötigt werden können 50% der Masse des Gesamtsystems ausmachen. Um dieses Problem zu überwinden wurde als Startpunkt der vorliegenden Arbeit die Nutzung von Metallhydriden als kombinierter Wasserstoff- und Wärmespeicher vorgeschlagen. Während sich der Satellit im Erdschatten befindet produziert die Brennstoffzelle Abwärme, während zur gleichen Zeit der Metallhydrid-Tank Wärme benötigt um Wasserstoff freizusetzen. Die Abwärme der Brennstoffzelle muss daher nicht direkt über Radiatoren abgestrahlt werden, sondern wird von Metallhydrid-Tank absorbiert um dann während dem restlichen Erdumlauf 20 mal langsamer mit einem deutlich kleinerem und leichteren Radiator abgegeben werden zu können. Diese Arbeit hat zum Ziel, das durch analytische und experimentelle Methoden untersuchte Potential der Anwendung einer solchen Technologie auf Satelliten zu präsentieren. Die Modellapplikation für diese Arbeit ist ein 39kW Telekommunikationssatellit. Die Ergebnisse lassen sich allerdings auch auf andere Anwendungen skalieren und übertragen.

Les travaux précédents trouvés dans la littérature ont mis l'importance sur la pile à combustible PEM ou électrolyseur PEM. Certains articles ont étudié également la pile à combustible réversible et le système d'alimentation en hydrogène par énergie solaire en intégrant à la fois la pile à combustible et électrolyseur. Contrairement à un « Unitised regenerative fuel cell (URFC)», notre conception a un compartiment individuel pour chaque système de PEM-Fuel Cell et d'electrolyseur-PEM et nommé Quasi - URFC. Grâce à ce nouveau concept, l'objectif principal est de réduire le coût de la pile à combustible régénératrice (RFC) en minimisant le rapport de surface superficielle géométrique du catalyseur de l'assemblage membrane électrodes (AME) des deux modes dans la cellule. D'ailleurs, nous visons également à construire un RFC plus compact, léger et portable par rapport à une pile à combustible ou l'électrolyseur classique. Ce travail de recherche est divisé en trois parties : la modélisation et simulation numérique, l'assemblage du prototype et le travail d'expérimentation. Quant à la partie de modélisation, un modèle physique multi-2D a été développé dans le but d'analyser les performances d'une pile à combustible à régénérée à trois-compartiments, qui se compose d'une piles à combustible et d'électrolyseur. Ce modèle numérique est basée sur la résolution des équations de conservation de masse, du momentum, des espèces et du courant électrique en utilisant une approche par éléments finis sur des grilles 2D . Les simulations permettent le calcul de la vitesse, de la concentration de gaz, la densité de courant et les distributions de potentiels en mode pile à combustible et en mode d'électrolyse, ainsi nous aider à prédire le comportement de quasi - RFC. En outre, l'assemblage du premier prototype du nouveau concept de pile à combustible à combustible régénérée a été achevée et testée au cours des trois années d'études dans le cadre d'une thèse. Les résultats expérimentaux de la 3 Compartiments R-PEMFC ont été prometteurs dans les deux modes, soit en mode piles à combustible et soit en mode d'électrolyseur. Ces résultats valideront ensuite les résultats de la simulation, obtenus auparavant par la modélisation. / The past works found in the literature have focused on either PEM fuel cell or electrolyzer-PEM. Some of the papers even studied the unitised reversible regenerative fuel cell (URFC) and the solar power hydrogen system by integrating both fuel cell and electrolyzer. Unlike the URFC, our design has an individual compartment for each PEMFC and E-PEM systems and named Quasi-URFC. With this new concept, the main objective is to reduce the cost of regenerative fuel cell (RFC) by minimizing the ratio of the catalyst’s geometric surface area of the membrane electrode assembly (MEA) of both cell modes. Apart from that, we also aim to build a compact, light and portable RFC.This research work is divided into three parts: the modeling, assembly of the prototype and the experimentation work. As for the modeling part, a 2D multi-physics model has been developed in order to analyze the performance of a three chamber-regenerative fuel cell, which consists of both fuel cell and electrolyzer systems. This numerical model is based on solving conservation equations of mass, momentum, species and electric current by using a finite-element approach on 2D grids. Simulations allow the calculation of velocity, gas concentration, current density and potential's distributions in fuel cell mode and electrolysis mode, thus help us to predict the behavior of Quasi-RFC. Besides that, the assembly of the first prototype of the new concept of regenerative fuel cell has been completed and tested during the three years of PhD studies. The experimental results of the Three-Chamber RFC are promising in both fuel cell and electrolyzer modes and validate the simulation results that previously obtained by modeling.

Next generation telecommunication satellites will demand an increasing amount of power in the range of 30 kW or more within the next 10 years. Battery technology that can sustain 30 kW for an eclipse length of up to 72 minutes will represent a major impact on the total mass of the satellite, even with new Li-ion battery technologies. Regenerative fuel cell systems (RFCS) were identified years ago as a possible alternative to rechargeable batteries. Nevertheless, one major drawback was identified by several independent system studies, namely the need to dissipate large amounts of heat from the fuel cell (FC) during eclipse. This in turn requires massive thermal hardware (mainly large radiators) that can contribute up to 50% of the system mass. In order to overcome this issue, the use of metal hydrides (MH) as combined hydrogen and heat storage system was suggested as a starting point of the research presented in this thesis. During eclipse the FC must dissipate waste heat, and at the same time the MH tank must absorb heat in order to desorb hydrogen. Rather than dissipating the waste heat from the FC directly through a radiator, it can be stored solely, or partly, in the MH tank, to be dissipated during Equinox, with a 20 times slower rate, requiring a radiator with significantly less volume and mass. This thesis aims to present the potential of using such MH storage tanks to alternately store hydrogen and waste heat from the FC on-board a spacecraft, investigated by theoretical and experimental means. The model application for the MH tank technology considered in this thesis is a 39 kW telecommunication satellite. Nevertheless, the derived results are to be considered a generic outcome and can be translated or scaled to many other applications.:1 Introduction 2 The Metal Hydride Regenerative Fuel Cell System (MH-RFCS) 3 Metal Hydride Material Selection and Characterization 4 Design and Optimization of the Metal Hydride Tank System 5 Design and Manufacturing of a Technology Demonstrator 6 Simulation of the Metal Hydride Tank Performance 7 Experimental Results and Discussion 8 Outlook 9 Bibliography / Es kann davon ausgegangen werden, dass der Trend hin zu Telekommunikationssatelliten mit immer höherer Leistung in den nächsten 10 Jahren zu Satelliten-Plattformen mit 30kW und mehr führen wird. Batterien, welche eine Leistung von 30kW für Eklipse-Längen von 72 Minuten zur Verfügung stellen müssen, werden daher einen immer größeren Einfluss auf die Gesamtmasse des Satelliten haben. Regenerative Brennstoffzellensysteme wurden daher schon vor Jahren als mögliche Alternative zu wieder aufladbaren Batterien untersucht. Mehrere unabhängige Studien sind zu dem Schluss gekommen, dass die größte Problematik in der Einführung von Brennstoffzellensystemen auf Satelliten darin besteht, die relativ großen Mengen an Abwärme effizient abzustrahlen. Die Radiatoren, die hierfür benötigt werden können 50% der Masse des Gesamtsystems ausmachen. Um dieses Problem zu überwinden wurde als Startpunkt der vorliegenden Arbeit die Nutzung von Metallhydriden als kombinierter Wasserstoff- und Wärmespeicher vorgeschlagen. Während sich der Satellit im Erdschatten befindet produziert die Brennstoffzelle Abwärme, während zur gleichen Zeit der Metallhydrid-Tank Wärme benötigt um Wasserstoff freizusetzen. Die Abwärme der Brennstoffzelle muss daher nicht direkt über Radiatoren abgestrahlt werden, sondern wird von Metallhydrid-Tank absorbiert um dann während dem restlichen Erdumlauf 20 mal langsamer mit einem deutlich kleinerem und leichteren Radiator abgegeben werden zu können. Diese Arbeit hat zum Ziel, das durch analytische und experimentelle Methoden untersuchte Potential der Anwendung einer solchen Technologie auf Satelliten zu präsentieren. Die Modellapplikation für diese Arbeit ist ein 39kW Telekommunikationssatellit. Die Ergebnisse lassen sich allerdings auch auf andere Anwendungen skalieren und übertragen.:1 Introduction 2 The Metal Hydride Regenerative Fuel Cell System (MH-RFCS) 3 Metal Hydride Material Selection and Characterization 4 Design and Optimization of the Metal Hydride Tank System 5 Design and Manufacturing of a Technology Demonstrator 6 Simulation of the Metal Hydride Tank Performance 7 Experimental Results and Discussion 8 Outlook 9 Bibliography

Cette thèse porte sur l’aide à la décision dans un contexte décisionnel très complexe. Classiquement, pour résoudre de telles situations, on utilise des méthodes de structuration de problèmes. Cependant ces méthodes bien qu’appliquées dans le cadre multi acteur ou dans les décisions de groupe, n’aboutissent pas toujours à des résultats directement exploitables dans un modèle d’évaluation. Ou, lorsque c’est le cas, les données obtenues par structuration sont utilisées comme si elles provenaient d’un seul décideur, tendant à réduire par conséquent l'efficacité de la décision prise et son adhésion publique. Dans cette thèse nous nous sommes attelés à concevoir un modèle d’intégration d’outils conciliant le choix approprié d’outils de structuration pour les décisions de groupe et son exploitation efficace dans un modèle d’évaluation multicritère. En particulier nous nous sommes focalisés sur les modalités du passage des cartes cognitives aux arbres de valeurs. Ensuite nous avons appliqué notre démarche sur le cas pratique du projet ’’AIde à la Décision pour l'identification et l'accompagnement aux transformations sociétales induites par les nouvelles technologies de l'Hydrogène’’ (AIDHY). Enfin, la dernière partie de notre thèse est axée sur l’apport d’une modélisation multicritère pour appréhender formellement le problème d’évaluation des scénarios, formulé comme un problème de tri multicritère. Par conséquent, nous avons construit une méthode permettant d’observer et de paramétrer le comportement des invariants d’une acceptabilité sociale en général, par le biais d’une d’analyse de sensibilité à partir du cas de l’hydrogène énergie. / This thesis focuses on decision support in a very complex decision-making context. Typically, to solve such situations, methods of problem structuring are used. However, these methods although applied in the multi-stakeholder framework or group decisions do not always lead to results directly used in a valuation model. Even when this is the case, the data obtained by problem structuring are used as if they came from a single decision maker, thus tending to reduce the effectiveness of the decision and its popular support. In this thesis we attempted to develop a model that incorporates tools that reconcile the appropriate choice of tools for structuring group decision choice and its effective operation in a model of multi-criteria evaluation. In particular, we focused on how processing cognitive maps into value trees. Then we have applied our approach to the practical case of the ‘‘AIDHY” project. Finally, the last part of the thesis is focused on providing a multi-criteria modeling to formally approach the problem of evaluating scenarios, formulated as a multi-criteria sorting problem. Therefore, we constructed a method to observe and configure the behavior of invariants of social acceptability in general, through a sensitivity analysis based on the case of hydrogen energy.

<p>Energy is one of the basic needs of human beings and is extremely crucial for continued development of human life. Our work, leisure and our economic, social and physical welfare all depend on the sufficient, uninterrupted supply of energy. Therefore, it is essential to provide adequate and affordable energy for improving human welfare and raising living standards. Global concern over environmental climate change linked to fossil fuel consumption has increased pressure to generate power from renewable sources [1]. Although substantial advances in renewable energy technologies have been made, significant challenges remain in developing integrated renewable energy systems due primarily to mismatch between load demand and source capabilities [2]. The output from renewable energy sources such as photo-voltaic, wind, tidal, and micro-hydro fluctuate on an hourly, daily, and seasonal basis. As a result, these devices are not well suited for directly powering loads that require a uniform and uninterrupted supply of input energy.</p>

<p>Energy is one of the basic needs of human beings and is extremely crucial for continued development of human life. Our work, leisure and our economic, social and physical welfare all depend on the sufficient, uninterrupted supply of energy. Therefore, it is essential to provide adequate and affordable energy for improving human welfare and raising living standards. Global concern over environmental climate change linked to fossil fuel consumption has increased pressure to generate power from renewable sources [1]. Although substantial advances in renewable energy technologies have been made, significant challenges remain in developing integrated renewable energy systems due primarily to mismatch between load demand and source capabilities [2]. The output from renewable energy sources such as photo-voltaic, wind, tidal, and micro-hydro fluctuate on an hourly, daily, and seasonal basis. As a result, these devices are not well suited for directly powering loads that require a uniform and uninterrupted supply of input energy.</p>

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-10-18T14:27:42Z No. of bitstreams: 1 FRANCINALDO DE FREITAS PEREIRA - TESE PPGEP 2005..pdf: 5181579 bytes, checksum: 4b0502fc646549fa86f1d070395e206c (MD5) / Made available in DSpace on 2018-10-18T14:27:42Z (GMT). No. of bitstreams: 1 FRANCINALDO DE FREITAS PEREIRA - TESE PPGEP 2005..pdf: 5181579 bytes, checksum: 4b0502fc646549fa86f1d070395e206c (MD5) Previous issue date: 2005-08-26 / Capes / O objetivo deste trabalho é estudar o desempenho de um forno tipo mufla adaptado para utilizar hidrogénio eletrolítico como combustível. O sistema de aquecimento poderá ser aplicado em fornos de produção de tijolos, telhas, materiais cerâmicos, e produtos derivados do trigo. Neste sentido o hidrogénio eletrolítico substituiria os combustíveis de origem orgânica, que são os grandes vetores da poluição atmosférica, o hidrogénio poderá ser produzido usando-se energias renováveis como painéis fotovoltaicos e/ou turbinas eólicas. O hidrogénio foi produzido a partir da eletrolise da água em um reator bipolar usando hidróxido de potássio como eletrólito. O consumo de energia e a produção de hidrogénio foram estimados para diferentes níveis temperaturas de 300°C, 900°C e, 1100°C. / The objective of this work is the study of an oven adapted to use electrolytic hydrogen as fuel. The possible applications are the cooking of clay used in the production of ceramic materiais, bricks and tiles; as well as the production of derived products of the wheat. The electrolytic hydrogen, used as a fuel in replacement of carbonaceous fuels which contribute to the atmospheric pollution, can be produced using renewable energies like photovoltaic solar paneis and/or aeolian turbine power generators. The hydrogen production is done by electrolysis of water which occurs in a bipolar reactor using potassium hydroxide as electrolyte. The energy consumption and the hydrogen production are calculated for different temperatures of 300°C, 900°C and 1100°C range. They are respectively, 0,9 kWh and 0,131 m3, 2,1 kWh and 0,311 m3 and 3,2 kWh and 0,498 m3.

Magister Scientiae - MSc / Energy is one of the basic needs of human beings and is extremely crucial for continued development of human life. Our work, leisure and our economic, social and physical welfare all depend on the sufficient, uninterrupted supply of energy. Therefore, it is essential to provide adequate and affordable energy for improving human welfare and raising living standards. Global concern over environmental climate change linked to fossil fuel consumption has increased pressure to generate power from renewable sources [1]. Although substantial advances in renewable energy technologies have been made, significant challenges remain in developing integrated renewable energy systems due primarily to mismatch between load demand and source capabilities [2]. The output from renewable energy sources such as photo-voltaic, wind, tidal, and micro-hydro fluctuate on an hourly, daily, and seasonal basis. As a result, these devices are not well suited for directly powering loads that require a uniform and uninterrupted supply of input energy. / South Africa

This thesis explores what Karlstad Airport needs to go 100% green. Photovoltaics are assumed to be installed at the facility and a Hydrogen Energy Storage System and Battery Energy Storage System will be evaluated to reduce peaks during charging of the planes. Different power peak limits are explored as well as different sized Energy Storage Systems and later evaluated economically. A method to find the cheapest possible system is created with some assumptions and is then used to evaluate throughout the whole dataset. In the end any of the different sized Energy Storage Systems reduces the profitability when considering each systems expected lifecycle.

There has recently been an increased interest in hydrogen, both as a solution for seasonal energy storage but also for implementations in various industries and as fuel for vehicles. The transition to a society less dependent on fossil fuels highlights the need for new solutions where hydrogen is predicted to play a key role. This project aims to investigate technical and economic outcomes of different strategies for production and storage of hydrogen based on hydrogen demand and source of electricity. This is done by simulating the operation of different systems over a year, mapping the storage level, the source of electricity, and calculating the levelized cost of hydrogen (LCOH). The study examines two main cases. The first case is a system integrated with offshore wind power for production of hydrogen to fuel the operations in the industrial port Gävle Hamn. The second case examines a system for independent refueling stations where two locations with different electricity prices and traffic flows are analyzed. Factors such as demand, electricity prices, and component costs are investigated through simulating cases as well as a sensitivity analysis. Future potential sources of income are also analyzed and discussed. The results show that using an alkaline electrolyzer (AEL) achieves the lowest LCOH while PEM electrolyzer is more flexible in its operation which enables the system to utilize more electricity from the offshore wind power. When the cost of wind electricity exceeds the average electricity price on the grid, a higher share of wind electricity relative to electricity from the grid being utilized in the production results in a higher LCOH. The optimal design of the storage depends on the demand, where using vessels above ground is the most beneficial option for smaller systems and larger systems benefit financially from using a lined rock cavern (LRC). Hence, the optimal design of a system depends on the demand, electricity source, and ultimately on the purpose of the system. The results show great potential for future implementation of hydrogen systems integrated with wind power. Considering the increased share of wind electricity in the energy system and the expected growth of the hydrogen market, these are results worth acknowledging in future projects.