L’intégration de panneaux photovoltaïques dans un système électrique réduit la consommation des sources fossiles et apporte des avantages environnementaux. Toutefois, l'intermittence et les fluctuations de puissance détériorent la qualité d’alimentation électrique. La solution proposée est d’ajouter des éléments de stockage, coordonnés par un contrôleur local qui gère les flux de puissance entre toutes les sources et la disponibilité énergétique. Ce générateur actif PV peut générer des références de puissance et fournir des services « système » au réseau électrique. Puis les concepts liés au micro réseau sont transposés pour concevoir un système central de gestion de l'énergie d'un réseau électrique résidentiel, qui est alimenté par des générateurs actifs PV et une micro turbine à gaz. Un réseau de communication est utilisé pour échanger des données et des références de puissance. Un système de gestion de l'énergie est développé avec différentes fonctions de contrôle sur des échelles de temps différentes afin de maximiser l'utilisation de l'énergie PV. Une planification opérationnelle quotidienne est conçue par un algorithme déterministe, qui utilise la prédiction d'énergie PV et de la charge. Puis ces références de puissance sont actualisées chaque demi-heure en tenant compte de la disponibilité de l’énergie PV et l’état des unités de stockage. Les erreurs de prévision et les incertitudes sont compensées par le réglage primaire de fréquence. Les résultats de simulation et les tests valident la conception de la commande du générateur actif photovoltaïque ainsi que le système central de gestion de l'énergie du réseau résidentiel étudié / The integration of PV power generation in a power system reduces fuel consumption and brings environmental benefits. However, the PV power intermittency and fluctuations deteriorate the power supply quality. A solution is proposed by adding energy storages, which are coordinated by a local controller that controls the power flow among all sources and implements an inner energy management. This PV based active generator can generate power references and can provide ancillary services in an electric network. Then micro grid concepts are derived to design a central energy management system of a residential network, which is powered by PV based active generators and a gas micro turbine. A communication network is used to exchange data and power references. An energy management system is developed with different time-scale functions to maximize the use of PV power. An operational daily planning is designed by a determinist algorithm, which uses 24 hour-ahead PV power prediction and load forecasting. Then power references are refreshed each half of an hour by considering the PV power availability and the states of energy storage units. Prediction errors and uncertainties are compensated by primary frequency controllers. Simulation and testing results validate the design of the PV active generator local controller and the central energy management system of the studied residential network

Continued emission of green house gases has energized research activity worldwide to develop efficient ways to harness renewal energy. The availability of large scale energy storage technologies is essential to make renewal energy a reliable source of energy. Redox flow batteries show potential in this direction. These batteries typically need expensive membranes which need replacement be-cause of fouling. The recently proposed soluble lead redox flow battery (SLRFB), in which lead ions deposit on electrodes in charge cycle and dissolve back in discharge cycle, can potentially cut down the cost of energy storage by eliminating membrane. A number of challenges need to be overcome though. Low cycleability, residue formation, and low efficiencies are foremost among these, all of which require an understanding of the underlying mechanisms. A model of laminar flow-through SLRFB is first developed to understand buildup of residue on electrodes with continued cycling. The model accounts for spatially and temporally growing concentration boundary layers on electrodes in a self consistent manner by permitting local deposition/dissolution rates to be controlled by local ion transport and reaction conditions. The model suggests controlling role for charge transfer reaction on electrodes (anode in particular) and movement of ions in the bulk and concentration boundary layers. The non-uniform current density on electrodes emerges as key to formation of bare patches, steep decrease in voltage marking the end of discharge cycle, and residue buildup with continuing cycles. The model captures the experimental observations very well, and points to improved operational efficiency and decreased residue build up with cylindrical electrodes and alternating flow direction of recirculation. The underlying mechanism for more than an order of magnitude increase in cycle life of a beaker cell battery with increase in stirrer speed is unraveled next. Our experiments show that charging with and without stirring occurs identically, which brings up the hitherto unknown but quite strong role of natural convection in SLRFB. The role of stirring is determined to be dislodgement/disintegration of residue building up on electrodes. The depletion of active material from electrolyte due to residue formation is offset by “internal regeneration mechanism”, unraveled in the present work. When the rate of residue formation, rate of dislodging/disintegration from electrode, and rate of regeneration of active material in bulk of the electrolyte becomes equal, perpetual operation of SLRFB is expected. The identification of strong role of free convection in battery is put to use to demonstrate a battery that requires stirring/mixing only intermittently, during open circuit stages between charge and discharge cycles when no current is drawn. Inspired by our experimental finding that the measured currents for apparently diffusion limited situations (no external flow) are far larger than the maxi-mum possible theoretical value, the earlier model is modified to account for natural convection driven by concentration gradient of lead ions in electrolyte. The model reveals the presence of strong natural convection in battery. The induced flow in the vicinity of the electrodes enhances mass transport rates substantially, to the extent that even in the absence of external flow, normal charge/discharge of battery is predicted. The model predicted electrochemical characteristics are verified quantitatively through voltage-time measurements. The formation of flow circulation loops driven by electrode processes is validated qualitatively through PIV measurements. Natural convection is predicted to play a significant role in the presence of external flow as well. The hitherto unexplained finding in the literature on insensitivity of charge-discharge characteristics to electrolyte flow rate is captured by the model when mixed mode of convection is invoked. Flow reversal and wavy flow are predicted when natural convection and forced convection act in opposite directions in the battery. The effect of the presence of non-conducting material (PbO on anode) on the performance of SLRFB is studied using a simplified approach in the model. The study reveals the presence of charge coup de fouet phenomenon in charge cycle. The phenomenon as well as the predicted effect of depth of discharge on the magnitude of charge coup de fouet are confirmed experimentally.

Master thesis discusses the growing need of electric energy storage and its effectivity and capacity. It describes an overview of possible technologies with their advantages and disadvantages. Greater attention is paid to the storage of energy in gas, so-called Power to Gas, which combines the electrolytic production of hydrogen from water and the Sabatier reaction to produce synthetic methane. This technology is introduced in the so-called SIT Brno cycle of Siemens Industrial Turbomachinery company. The main part of the thesis is focused on the description of this cycle and on the calculation of the steam-gas turbine (high-pressure and low pressure module). This thesis describes the methodology of turbine calculation and the composition of the steam gas mixture after combustion of methane. The carbon dioxide formed by combustion in the steam-gas mixture generator was replaced by steam. Part of the diploma thesis are drawings of cross-section of individual turbine modules.

The potential for electrical energy storage to both provide services to the electrical grid and help to better integrate renewable energies in the electrical system is promising. This report investigates one type of storage, compressed air energy storage (CAES), where energy is stored by compressing air during hours of low electricity demand and later expanding the air to generate electricity during high demand hours. To this day it exists two large plants, but small facilities have yet to be implemented, raising the question whether it could be viable to use CAES on a smaller scale as well. By creating a model of a CAES system based on the principles of thermodynamics and applying it to a hypothetical group of residences, its ability to balance daily fluctuations in electricity demand is explored. The result show that the system is able to cover some of the demand but there is no economic profit to be gained. The results of this report suggest that a CAES system of this size is not a viable option during current price market for electricity in Sweden but during other circumstances it could be relevant. / Dagens energisystem kräver vissa tjänster för att kunna behålla stabilitet och tillgodose energibehovet. Energilagring är ett sätt att förse systemet med dessa tjänster samtidigt som det också skapar möjlighet att bättre utnyttja förnyelsebara energiresurser, som vind och sol, som annars kan vara för oförutsägbara för att kunna utnyttjas maximalt. I denna studie undersöks komprimerad luft som energilagring (CAES). Sammanfattningsvis används billig elektricitet under timmar då elförbrukningen är låg för att komprimera luft och lagra denna för att sedan expandera luften igen och på så vis generera elektricitet vid behov eller då det finns ekonomisk vinstmöjlighet. CAES systemet kan vara uppbyggt och dimensionerat på flera olika sätt vilket undersöks samt beskrivs i närmare detalj. Möjligheten att använda CAES i liten skala för att tillgodose ett dagligen varierande energibehov undersöks och det utrönas ifall detta är ekonomiskt gynnsamt eller inte. Detta undersöks genom att skapa en modell över ett CAES-system som appliceras på energibehovet för en grupp bostäder. Resultatet visar att systemet kan täcka en del av energibehovet men ekonomisk vinning är inte möjligt. Utifrån dessa resultat konstateras att CAES i liten skala inte är ett ekonomiskt försvarbart alternativ för att täcka toppar i ett varierande energibehov vid det rådande energipriset i Sverige men under andra omständigheter skulle det kunna vara möjligt.

The potential for electrical energy storage to both provide services to the electrical grid and help to better integrate renewable energies in the electrical system is promising. This report investigates one type of storage, compressed air energy storage (CAES), where energy is stored by compressing air during hours of low electricity demand and later expanding the air to generate electricity during high demand hours. To this day it exists two large plants, but small facilities have yet to be implemented, raising the question whether it could be viable to use CAES on a smaller scale as well. By creating a model of a CAES system based on the principles of thermodynamics and applying it to a hypothetical group of residences, its ability to balance daily fluctuations in electricity demand is explored. The result show that the system is able to cover some of the demand but there is no economic profit to be gained. The results of this report suggest that a CAES system of this size is not a viable option during current price market for electricity in Sweden but during other circumstances it could be relevant. / Dagens energisystem kräver vissa tjänster för att kunna behålla stabilitet och tillgodose energibehovet. Energilagring är ett sätt att förse systemet med dessa tjänster samtidigt som det också skapar möjlighet att bättre utnyttja förnyelsebara energiresurser, som vind och sol, som annars kan vara för oförutsägbara för att kunna utnyttjas maximalt. I denna studie undersöks komprimerad luft som energilagring (CAES). Sammanfattningsvis används billig elektricitet under timmar då elförbrukningen är låg för att komprimera luft och lagra denna för att sedan expandera luften igen och på så vis generera elektricitet vid behov eller då det finns ekonomisk vinstmöjlighet. CAES systemet kan vara uppbyggt och dimensionerat på flera olika sätt vilket undersöks samt beskrivs i närmare detalj. Möjligheten att använda CAES i liten skala för att tillgodose ett dagligen varierande energibehov undersöks och det utrönas ifall detta är ekonomiskt gynnsamt eller inte. Detta undersöks genom att skapa en modell över ett CAES-system som appliceras på energibehovet för en grupp bostäder. Resultatet visar att systemet kan täcka en del av energibehovet men ekonomisk vinning är inte möjligt. Utifrån dessa resultat konstateras att CAES i liten skala inte är ett ekonomiskt försvarbart alternativ för att täcka toppar i ett varierande energibehov vid det rådande energipriset i Sverige men under andra omständigheter skulle det kunna vara möjligt.

An urgent transformation from fossil fuels to cleaner energy sources to combat climate change has led to the utilization of renewable energies like solar, wind, and tidal power. However, the intermittency of these sources hinders their wider implementation. To address this, large-scale electrical energy storage (EES) systems are needed. These systems store excess energy during periods of surplus and release it during peak demand, enhancing grid reliability. Secondary batteries have been developed as promising EES solutions due to their reliability, independence from weather, and ease of maintenance. While lithium-ion batteries (LIBs) are popular as secondary batteries, their limited lithium supply, and rising costs demand for cost-effective alternatives. This study focuses on developing sodium iron fluorophosphate (Na2FePO4F) as a promising cathode material for SIBs. Because of its iron-based composition, which is generated from sustainable sources, Na2FePO4F offers a potential solution to the cost and supply difficulties related with LIBs. However, challenges exist, including low electronic conductivity and inferior electrochemical performance. To address these challenges, this research explores mechanochemically assisted solid-state synthesis routes as a low-cost and environmentally friendly approach. The characterization and performance evaluation of Na2FePO4F (NFPF) and NFPF/C positive electrode materials for sodium-ion batteries (SIBs) were systematically investigated through a range of analytical techniques, including XRD, TGA, SEM-EDS, FT-IR, and Raman analyses. A single-step solid-state synthesis demonstrates effectiveness in producing NFPF and NFPF/C-positive electrode materials. Moreover, Fe2O3 nanoparticles serve as the primary iron source in the solid-state synthesis of iron-based fluorophosphate Na2FePO4F/C, successfully producing both NFPF pristine phase and NFPF carbon-coated active materials. Finally, a comparison between the two synthesis pathways reveals that the active material from single-step solid-state synthesis exhibits a superior initial discharge specific capacity of 74.24 mAh⋅g−1 at 0.005 C, outperforming the double-step solid-state synthesis. These findings can contribute to the development of affordable and sustainable energy storage solutions, offering alternatives to traditional LIBs. / En akut omvandling från fossila bränslen till renare energikällor för att bekämpa klimatförändringarna har lett till ett utnyttjande av förnybar energi som sol-, vind- och tidvattenkraft. Emellertid hindrar dessa källors intermittenser deras bredare genomförande. För att komma till rätta med detta behövs storskaliga system för lagring av elektrisk energi (EES). Dessa system lagrar överskottsenergi under perioder med överskott och släpper ut den under toppbelastning, vilket förbättrar nätets tillförlitlighet. Sekundära batterier har utvecklats som lovande EES-lösningar på grund av deras tillförlitlighet, väderberoende och enkla underhåll. Medan litiumjonbatterier (LIB) är populära som sekundära batterier, kräver deras begränsade litiumtillgång och stigande kostnader kostnadseffektiva alternativ. Denna studie fokuserar på att utveckla natriumjärnfluorfosfat (Na2FePO4F) som ett lovande katodmaterial för SIB. På grund av sin järnbaserade sammansättning, som genereras från hållbara källor, erbjuder Na2FePO4F en potentiell lösning på kostnads- och försörjningssvårigheter relaterade till LIB. Men det finns utmaningar, inklusive låg elektronisk konduktivitet och sämre elektrokemisk prestanda. För att möta dessa utmaningar undersöker denna forskning mekanokemiskt assisterade syntesvägar i fast tillstånd som ett billigt och miljövänligt tillvägagångssätt. Karakteriseringen och prestandautvärderingen av Na2FePO4F (NFPF) och NFPF/C positiva elektrodmaterial för natriumjonbatterier (SIB) undersöktes systematiskt genom en rad analytiska tekniker, inklusive XRD, TGA, SEM-EDS, FT-IR och Raman analyser. En enstegs solid state-syntes visar effektivitet vid framställning av NFPF och NFPF/C-positiva elektrodmaterial. Dessutom tjänar Fe2O3-nanopartiklar som den primära järnkällan i solid state-syntesen av järnbaserat fluorfosfat Na2FePO4F/C, vilket framgångsrikt producerar både NFPF orörd fas och NFPF kolbelagda aktiva material. Slutligen avslöjar en jämförelse mellan de två syntesvägarna att det aktiva materialet från enstegs-solid-state-syntes uppvisar en överlägsen initial urladdningsspecifik kapacitet på 74,24 mAh⋅g−1 vid 0,005 C, vilket överträffar dubbelstegs-solid-state-syntesen. Dessa resultat kan bidra till utvecklingen av prisvärda och hållbara energilagringslösningar, som erbjuder alternativ till traditionella LIB.

Dans le domaine aéronautique, l'optimisation du rendement énergétique global, la réduction des masses embarquées et la nécessité de répondre aux besoins énergétiques croissants conduisent à développer de nouvelles technologies et méthodes pour générer l'énergie électrique à bord, pour la distribuer, la convertir et la stocker. Dans cette thèse, des éléments de stockage de l'énergie électrique sont caractérisés dans l'optique d'être modélisés. Parmi les différents systèmes de stockage, présentés dans un état de l'art préliminaire, sont retenus les supercondensateurs et les accumulateurs électrochimiques Lithium-ion polymère, considérés respectivement comme des sources de puissance et d'énergie, à l'échelle de l'application. Ces moyens de stockage sont caractérisés par chronopotentiométrie à courant constant et par spectrométrie d'impédance électrochimique. Les essais sont éffectués dans des conditions expérimentales, définissant le domaine de validités des modèles, en cohérence avec les contraintes de l'application finale. Différents modèles sont alors développés en fonction de leur utilisation : des modèles simples, fonctionnels et suffisants pour la gestion globale d'énergie et des modèles dynamiques, comportementaux et nécessaires pour l'analyse de la qualité du réseau. Ils sont ensuite validés sur des profils de mission. Pour disposer d'un système de stockage performant et en adéquation avec les besoins énergétiques de l'aéronef, une méthode de dimensionnement est proposée, associant des composants de stockage complémentaires. Un gestion fréquentielle des sources est mise en oeuvre de manière à minimiser la masse du système de stockage. / In aeronautics, the optimization of the global energetic efficiency, the reduction of the embedded weight and the need to meet the growing energetic requirements lead to develop new technologies and methods to generate electrical energy, to distribute it, to convert it and to store it aboard. In this thesis, electrical energy storage systems are characterized with a view to be modeled. Among varied storage systems, presented in an introductory state of the art, ultracapacitors and Lithium-ion polymer secondary batteries are studied. These components are considered respectively as power and energy sources, in regards to the application scale. These storage systems are characterized by chronopotentiometry at constant current and by electrochemical impedance spectrometry. Tests are carried out in experimental conditions which define the validity area of modeling, in relation with the application constraints. Different models are developed according to their future use : simple models, which are functional and sufficient for the global energy management, and dynamics models, which are behavioral and necessary for the analysis of the network quality. Then, they validated thanks to mission profiles. Finally, to dispose of an efficient storage system that meets the energetic requirements of the aircraft, a sizing method is suggested by combining complementary storage systems. An energy management based on frequency approach is implemented in order to minimize the storage system weight.

<p>This work focuses on the collection and analysis of Lithium-ion battery operational and temperature data during nail penetration testing through two different experimental approaches. Raman spectroscopy, machine learning, and internal temperature sensors are used to collect and analyze data to further investigate the effects on cell operation during and after nail penetrations, and the feasibility of using this data to predict future performance.</p> <p><br></p> <p>The first section of this work analyzes the effects on continued operation of a small Lithium-ion prismatic cell after nail penetration. Raman spectroscopy is used to examine the effects on the anode and cathode materials of cells that are cycled for different amounts of time after a nail puncture. Incremental capacity analysis is then used to corroborate the findings from the Raman analysis. The study finds that the operational capacity and lifetime of cells is greatly reduced due to the accelerated degradation caused by loss of material, uneven current distribution, and exposure to atmosphere. This leads into the study of using the magnitude and corresponding voltage of incremental capacity peaks after nail puncture to forecast the operation of damaged cells. A Gaussian process regression is used to predict discharge capacity of different cells that experience the same type of nail puncture. The results from this study show that the method is capable of making accurate predictions of cell discharge capacity even with the higher rate of variance in operation after nail puncture, showing the method of prediction has the potential to be implemented in devices such as battery management systems.</p> <p><br></p> <p>The second section of this work proposes a method of inserting temperature sensors into commercially-available cylindrical cells to directly obtain internal temperature readings. Characterization tests are used to determine the effect on the operability of the modified cells after the sensors are inserted, and lifetime cycle testing is implemented to determine the long-term effects on cell performance. The results show the sensor insertion causes a small reduction in operational performance, and lifetime cycle testing shows the cells can operate near their optimal output for approximately 100-150 cycles. Modified cells are then used to monitor internal temperatures during nail penetration tests and how the amount of aging affects the temperature response. The results show that more aging in a cell causes higher temperatures during nail puncture, as well as a larger difference between internal and external temperatures, due mostly to the larger contribution of Joule heating caused by increased internal resistance.</p>

<h4>A generalized physics-based modeling framework is presented to analyze: (a) the effects of temperature on identified degradation mechanisms, (b) interfacial debonding processes, including deterministic and stochastic mechanisms, and (c) establishing model performance benchmarks of electrochemical porous electrode theory models, as a necessary stepping stone to perform valid battery degradation analyses and designs. Specifically, the effects of temperature were incorporated into a physics-based, reduced-order model and extended for a LiCoO₂ -graphite 18650 cell. Three dimensionless driving forces were identified, controlling the temperature-dependent reversible charge capacity. The identified temperature-dependent irreversible mechanisms include homogeneous SEI, at moderate to high temperatures, and the chemomechanical degradation of the cathode at low temperatures. Also, debonding of a statistically representative electrochemically active particle from the surrounding binder-electrolyte matrix in a porous electrode was modeled analytically, for the first time. The proposed framework enables to determine the space of C-Rates and electrode particle radii that suppresses or enhances debonding and is graphically summarized into performance–microstructure maps where four debonding mechanisms were identified, and condensed into power-law relations with respect to the particle radius. Finally, in order to incorporate existing or emerging degradation models into porous electrode theory (PET) implementations, a set of benchmarks were proposed to establish a common basis to assess their physical reaches, limitations, and accuracy. Three open source models: dualfoil, MPET, and LIONSIMBA were compared, exhibiting significant qualitative differences, despite showing the same macroscopic voltage response, leading the user to different conclusions regarding the battery performance and possible degradation mechanisms of the analyzed system.</h4>