The popularity of the internal combustion engine (ICE) vehicles has contributed to global warming problem and degradation of air quality around the world. Furthermore, the vehicles??? massive demand on gas has played a role in the depletion of fossil fuel reserves and the considerable rise in the gas price over the past twenty years. Those existing challenges force the auto-industry to move towards the technology development of vehicle electrification. An electrified vehicle is driven by one or more electric motors. And the electricity comes from the onboard energy storage system (ESS). Currently, no single type of green energy source could meet all the requirements to drive a vehicle. A hybrid energy storage system (HESS), as a combination of battery and ultra-capacitor units, is expected to improve the overall performance of vehicles??? ESS. This thesis focuses on the design of HESS and the development of a HESS prototype for electric vehicles (EVs) and hybrid electric vehicles (HEVs). Battery unit (BU), ultra-capacitor unit (UC) and a DC/DC converter interfacing BU and UC are the three main components of HESS. The research work first reviews literatures regarding characteristics of BU, UC and power electronic converters. HESS design is then conducted based on the considerations of power capability, energy efficiency, size and cost optimization. Besides theoretical analysis, a HESS prototype is developed to prove the principles of operation as well. The results from experiment are compared with those from simulation.

Orientador: Dr. Alfeu J. Sguarezi Filho / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia Elétrica, 2015. / Neste trabalho apresenta-se uma configuração do sistema de armazenamento de energia com baterias aplicado a sistemas de geração de energia eólica empregando conversores de fonte Z conectados à rede elétrica. Os geradores de indução gaiola de esquilo, são frequentemente utilizados nos sistemas de geração de energia eólica, por sua robustez, simplicidade, peso menor e custo baixo. Este é conectado diretamente ao conversor de potência bidirecional back to back, pode fornecer potências ativa e reativa à rede elétrica. Além disso, é estudado o conversor de fonte Z aplicado nesta topologia. No entanto, a implantação de sistemas de armazenamento de energia com baterias nos sistemas de geração de energia eólica na atualidade é muito importante, devido à possibilidade de oscilações da tensão e corrente na rede elétrica, portanto, estes podem ajudar à estabilização das tensões, correntes e a frequência na rede elétrica. Este sistema é conectado ao conversor back to back por meio de um conversor elevador-abaixador de corrente contínua. Para controlar a velocidade no eixo do rotor no gerador de indução, a estratégia é baseada no controle direto de torque. Enquanto, para o conversor do lado da rede é empregada a técnica de controle orientado pela tensão. Para o banco de baterias é utilizado o controle da tensão no barramento de corrente contínua e do fluxo na corrente da bateria, utilizando controladores do tipo PI. Com os novos desenvolvimentos tecnológicos nas chaves de potência, são apresentadas topologias de conversores CC-CA como o conversor de fonte Z, este tipo de conversor corrige algumas limitações do conversor back to back, com as características de elevador/abaixador de tensão, sem o uso de dispositivos de comutação, são permitidos os curto-circuitos na chaves, empregando novas técnicas de modulação, e reduz a quantidade harmônica injetada na rede elétrica. Os estudos foram realizados por meio de técnicas de simulação computacional usando modelos matemáticos do sistema estudado para a validação das estratégias de controle empregadas em diferentes condições de operação. Para as simulações empregou-se a ferramenta computacional SimPowerSystems R do Matlab/Simulink R . / This paper presents a battery energy storage system applied to wind power generation based on Z-source inverter connected to the power grid. The squirrel cage induction generators, often used in wind power generation systems, for its robustness, simplicity, lower weight and low cost. This is connected directly to the bidirectional power converter back to back, therefore, and provides active and reactive powers to grid. In addition, it is studied the Z-source inverter applied in this topology. However, the implementation of battery energy storage systems in wind power generation systems, currently is very important, due to possibility of the voltage and current fluctuations in the power grid, so these may to stabilisation of current, voltage and frequency on the grid. This system is connected to back to back converter through a DC-DC converter (buck-boost). For the rotor speed control on induction generator, the strategy is based on direct torque control. While, for the grid side converter is employed the technique of voltage oriented control. For the battery bank voltage control is used on DC-link voltage and battery current flow, through PI type controllers. With the new technological developments in the keys of power, DC converters topologies are presented as the Z-source inverter, this type converter fixes some limitations of the converter back to back, with the characteristics of buck-boost voltage, without the use of switching devices, allowed short-circuits on converter, using new modulation techniques, and reduces the amount injected harmonic to power grid. The studies were performed by means of computer simulation techniques using mathematical models of studied system to validate the control strategies employed in different operating conditions. For the simulations was used the computational tool SimPowerSystems R do Matlab/Simulink R .

Ce travail vise à identifier l’impact potentiel des impulsions périodiques de courant sur laperformance et la durée de vie des accumulateurs graphite/LiFePO4. Il apparait que,contrairement aux résultats connus pour les accumulateurs Plomb-acide et à ceux annoncéspar certains auteurs de la littérature pour les accumulateurs Li-ion, l’application d’impulsionspériodiques de courant ne présente pas d’intérêt dans une logique d’amélioration de laperformance et/ou de la durée de vie des accumulateurs Li-ion. De surcroit, certains typesd’impulsions ont été identifiés pour entrainer des effets préjudiciables à ces derniers. En seréférant à une application de véhicule industriel hybride électrique, nous avons évalué sur descritères techniques et économiques l’intérêt d’implémenter un système de stockage d’énergiecombiné, c'est-à-dire mutualisant l’usage d’une batterie Li-ion et desupercondensateurs/condensateurs. Il apparait que les stratégies consistant à agir sur lescomposantes hautes fréquences du signal pour ajouter/retirer des impulsions du profil vu parla batterie ne permettent pas d’accéder à des allongements de durée de vie qui pourraientcompenser le surcoût actuel lié à l’implémentation de ces systèmes. En outre, il apparait quele meilleur levier d’optimisation du bilan technique et économique associé au système destockage d’énergie est son dimensionnement. En effet, même si les systèmes de stockaged’énergie combinés utilisant les supercondensateurs permettent d’atteindre des réductions duratio coût/durée de vie considérables, la prise en compte globale des critères de coût, de duréede vie, de masse et d’encombrement s’avère plus favorable à la solution constituée d’unebatterie seule, de taille optimisée vis-à-vis de son application. / This work aims to identify the possible impact of periodic current pulses on both performanceand lifetime of graphite/LiFePO4 secondary batteries. Contrary to the well-known results onlead-acid batteries and to results announced in previously published works, periodic pulses donot bring any benefit to the performance and the lifetime of Li-ion batteries. Moreover,certain pulse types have been identified to be detrimental to Li-ion batteries. Using the hybridelectric vehicle application as a reference, we evaluated both the technical and economicalaspects of implementing combined energy storage systems composed with Li-ion batteriesand supercapacitors/capacitors. We found that the control strategies acting on high frequencyharmonics of the current signal to adding/retrieving pulses to the Li-ion battery profile doesnot prolong its life enough to compensate the extra cost of such system implementation.Furthermore, it seems that the best way to optimize the technico-economic balance of theenergy storage system is the sizing. Even if combined energy storage systems using Li-ionbatteries and supercapacitors enable to considerably increase the lifetime/cost ratio, a generalconsideration of the criteria cost, life, mass and volume is more favorable to a solution whereone single Li-ion battery is optimally sized for its application.

Geothermal energy is the energy naturally present inside the earth crust. When a large volume of hot water and steam is trapped in subsurface porous and permeable rock structure and a convective circulating current is set up, it forms a geothermal reservoir. A geothermal system can be defined as - convective water in the upper crust of earth, which transfers heat from a heat source (in the reservoir) to a heat sink, usually the free surface. A geothermal system is made up of three main elements: a heat source, a reservoir and a fluid, which is the carrier that transfers the heat. As an alternative source of energy geothermal energy has been under attention of the researchers for quite some time. The reason behind this is the existence of several benefits like clean and renewable source of energy which has considerable environmental advantage, with no chemical pollutants or wastes are generated due to geothermal emissions, and the reliability of the power resource. Hence research has been directed in several directions like exploration of geothermal resources, modeling the characteristics of different types of geothermal reservoirs and technologies to extract energy from them. The target of these models has been the prediction of the production of the hot water and steam and thus the estimation of the electricity generating potential of a geothermal reservoir in future years. In a geothermal power plant reinjection of the heat depleted water extracted from the geothermal reservoir has been a common practice for quite some time. This started for safe wastewater disposal and later on the technology was employed to obtain higher efficiency of heat and energy extraction. In most of the cases a very small fraction of the thermal energy present in the reservoir can be recovered without the reinjection of geothermal fluid. Also maintaining the reservoir pressure is essential which gradually reduces due to continuous extraction of reservoir fluid without reinjection, especially for reservoirs with low permeabilities. Although reinjection of cold-water has several benefits, the possibility of premature breakthrough of the cold-water front, from injection well zone to production well zone, reduces the efficiency of the reservoir operation drastically. Hence for maintaining the reservoir efficiency and longer life of the reservoir, the injectionproduction well scheme is to be properly designed and injection and extraction rates are to be properly fixed. Modeling of flow and heat transport in a geothermal reservoir due to reinjection of coldwater has been attempted by several researchers analytically, numerically and experimentally. The analytical models which exist in this field deal mostly with a single injection well model injecting cold-water into a confined homogeneous porous-fractured geothermal reservoir. Often the thermal conductivity is neglected in the analytical study considering it to be negligible which is not always so, as proved in this study. Moreover heterogeneity in the reservoir is also a major factor which has not been considered in any such analytical study. In the field of numerical modeling there also exists a need of a general coupled three-dimensional thermo-hydrogeological model including all the modes of heat transport (advection and conduction), the heat loss to the confining rocks, the regional groundwater flow and the geothermal gradient. No study existing so far reported such a numerical model including those mentioned above. The present study is concerned about modeling the non-isothermal flow and heat transport in a geothermal reservoir due to reinjection of heat depleted water into a geothermal reservoir. Analytical and numerical models are developed here for the transient temperature distributions and advancement of the thermal front in a geothermal reservoir which is generated due to the cold-water injection. First homogeneous geothermal aquifers are considered and later heterogeneities of different kinds are brought into picture. Threedimensional numerical models are developed using a software code DuMux which solves flow and heat transport problems in porous media and can handle both single and multiphase flows. The results derived by the numerical models have been validated using the results from the analytical models derived in this study. Chapter 1 of the thesis gives a brief introduction about different types of geothermal reservoirs, followed by discussion on the governing differential equations, the conceptual model of a geothermal reservoir system, the efficiency of geothermal reservoirs, the modeling and simulation concepts (models construction, boundary conditions, model calibration etc.). Some problems related with geothermal reservoirs and geothermal power is also discussed. The scenario of India in the context having a huge geothermal power potential is described and different potential geothermal sites have been pointed out. In Chapter 2, the concept of reinjection of the heat depleted (cold) water into the geothermal reservoir is introduced. Starting with a brief history of the geothermal reinjection, the chapter describes the purpose and the need of reinjection of geothermal fluid giving examples of different geothermal fields over the world where reinjection has been in practice and benefitted by that. The chapter further discusses on the problems and obstacles faced by the geothermal projects resulting from the geothermal reinjection, most important of which is the thermal-breakthrough and cooling of production wells. Lastly the problem of this thesis is discussed which is to model the transient temperature distribution and the movement of the cold-water thermal front generated due to the reinjection. The need of this modeling is elaborated which represents the motivation of taking up the problem of the thesis. Chapter 3 describes an analytical model developed for the transient temperature in a porous geothermal reservoir due to injection of cold-water. The reservoir is composed of a confined aquifer, sandwiched between rocks of different thermo-geological properties. The heat transport processes considered are advection, longitudinal conduction in the geothermal aquifer, and the conductive heat transfer to the underlying and overlying rocks of different geological properties. The one-dimensional heat transfer equation has been solved using the Laplace transform with the assumption of constant density and thermal properties of both rock and fluid. Two simple solutions are derived afterwards, first neglecting the longitudinal conductive heat transport and then heat transport to confining rocks. The analytical solutions represent the transient temperature distribution in the geothermal aquifer and the confining rocks and model the movement of the cold-water thermal front in them. The results show that the heat transport to the confining rocks plays an influential role in the transient heat transport here. The influence of some parameters, e.g. the volumetric injection rate, the longitudinal thermal conductivity and the porosity of the porous media, on the transient heat transport phenomenon is judged by observing the variation of the transient temperature distribution with different values of the parameters. The effects of injection rate and thermal conductivity have been found to be high on the results. Chapter 4 represents another analytical model for transient temperature distribution in a heterogeneous geothermal reservoir underlain and overlain by impermeable rocks due to injection of cold-water. The heterogeneity of the porous medium is expressed by the spatial variation of the flow velocity and the longitudinal effective thermal conductivity of the medium. Simpler solutions are also derived afterwards first neglecting the longitudinal conduction, then the heat loss to the confining rocks depending on the situation where the contribution of them to the transient heat transport phenomenon in the porous media is negligible. Solution for a homogeneous aquifer with constant values of the rock and fluid parameters is also derived with an aim to compare the results with that of the heterogeneous one. The effect of heat loss to the confining rocks in this case is also determined and the influence of some of the parameters involved, on the transient heat transport phenomenon is assessed by observing the variation of the results with different magnitudes of those parameters. Results show that the heterogeneity plays a major role in controlling the cold-water thermal front movement. The transient temperature distribution in the geothermal reservoir depends on the type of heterogeneity. The heat loss to the confining rocks of the geothermal aquifer also has influence on the heat transport phenomenon. In Chapter 5 another analytical model is derived for a heterogeneous reservoir where the heterogeneous geothermal aquifer considered is a confined aquifer consisted of homogeneous layers of finite length and overlain and underlain by impermeable rock media. All the different layers in the aquifer and the overlying and underlying rocks are of different thermo-hydrogeological properties. Results show that the advancement of the cold-water thermal front is highly influenced by the layered heterogeneity of the aquifer. As the cold-water thermal front encounters layers of different thermo-hydrogeological properties the movement of it changes accordingly. The analytical solution derived here has been compared with a numerical model developed by the multiphysics software code COMSOL which shows excellent agreement with each other. Lastly it is shown that approximation of the properties of a geothermal aquifer by taking mean of the properties of all the layers present will lead to erroneous estimation of the temperature distribution. Chapter 6 represents a coupled three-dimensional thermo-hydrogeological numerical model for transient temperature distribution in a confined porous geothermal aquifer due to cold-water injection. This 3D numerical model is developed for solving more practical problems which eliminate the assumptions taken into account in analytical models. The numerical modeling is performed using a software code DuMux as mentioned before. Besides modeling the three-dimensional transient temperature distribution in the model domain, the chapter investigates the regional groundwater flow has been found to be a very important parameter to consider. The movement of the thermal front accelerates or decelerates depending on the direction of the flow. Influence of a few parameters involved in the study on the transient heat transport phenomenon in the geothermal reservoir domain, namely the injection rate, the permeability of the confining rocks and the thermal conductivity of the geothermal aquifer is also evaluated in this chapter. The models have been validated using analytical solutions derived in this thesis. The results are in very good agreement with each other. In Chapter 7 the main conclusions drawn from the study have been enlisted and the scope of further research is also pointed out.

[ES] Dos aspectos críticos en la operación de una microrred son las estrategias de control y gestión de potencia implementadas, las cuales son esenciales para proporcionar su buen funcionamiento. La aplicación adecuada de dichas estrategias permite compensar los desequilibrios de potencia causados por la discontinuidad de la generación y de la demanda de energía en las microrredes. En este sentido, el objetivo global de estas estrategias de gestión es equilibrar adecuadamente el flujo de potencia en la microrred, mediante la aplicación de diferentes algoritmos que permiten cumplir con los criterios de estabilidad, protección, balance de potencia, transiciones, sincronización con la red y gestión adecuada de la microrred. En el caso de microrredes de pequeña escala de potencia con bajo número de generadores y sistemas de almacenamiento distribuidos, las estrategias de control centralizado ofrecen un alto nivel de flexibilidad para lograr funcionalidades avanzadas en la microrred y una adecuada distribución de la potencia entre los convertidores que la conforman. Esta tesis se ha enmarcado en el contexto de algoritmos de gestión centralizada de potencia de una microrred de generación distribuida en modo conectado a red. Los algoritmos presentados se pueden aplicar a los convertidores de potencia conectados al bus DC de una microrred AC/DC híbrida o en una microrred de DC, donde el despacho de potencia es observado y gestionado por un controlador central. Este último adquiere datos del sistema mediante una infraestructura de comunicaciones y estima la potencia que gestionará cada uno de los convertidores de potencia, sistemas de almacenamiento y cargas en funcionamiento. En este estudio se muestra la validación experimental de las estrategias de gestión aplicadas en la microrred desde el enfoque del comportamiento de los convertidores de potencia, de las baterías y las cargas ante dicha gestión. Se verifica la estabilidad de la microrred sometiendo a los convertidores a diferentes escenarios de funcionamiento. Estos escenarios pueden ser fluctuaciones en la irradiación, la demanda, el estado de carga de las baterías, los límites máximos de exportación/importación de potencia desde/hacia la microrred hacia/desde la red principal y de la tarifa eléctrica. Adicionalmente, se propone un sistema de almacenamiento de energía en baterías encargado de mantener el equilibrio de potencia en el bus de DC de la microrred que permite aprovechar las fuentes de generación renovables presentes en la microrred y maximizar el tiempo de servicio de las baterías mediante la aplicación de un algoritmo de carga de las baterías. Este último se ajusta al procedimiento de carga especificado por el fabricante, estableciendo las tasas de carga en función de los escenarios en que la microrred se encuentre. El procedimiento de carga en las baterías es fundamental para garantizar las condiciones adecuadas de operación de las mismas, ya que toman en consideración los parámetros establecidos por el fabricante, como son: tasas de carga/descarga, tensión máxima de carga, temperaturas de operación, etc. / [CAT] Dos dels aspectes crítics en l'operació d'una micro-xarxa són les estratègies de control i gestió de potència implementades, les quals són essencials per proporcionar el seu bon funcionament. L'aplicació adequada de dites estratègies permet compensar els desequilibris de potència causats per la discontinuïtat de la generació i demanda d'energia en les micro-xarxes. En aquest sentit, l'objectiu global de les nomenades estratègies de gestió és equilibrar adequadament el flux de potència en la micro-xarxa mitjançant l'aplicació de diferents algoritmes que permeten complir amb els criteris d'estabilitat, protecció, balanç de potència, transicions, sincronització amb la xarxa i gestió adequada de la micro-xarxa. En el cas de micro-xarxes de potència a petita escala i amb baix nombre de generadors i sistemes d'emmagatzematge distribuïts, les estratègies de control centralitzades ofereixen un alt nivell de flexibilitat per aconseguir funcionalitats avançades en la micro-xarxa i una adequada distribució de la potència entre els convertidors que la conformen. Aquesta tesi s'ha emmarcat al context d'algoritmes de gestió centralitzada de potència d'una micro-xarxa de generació distribuïda en mode de connexió a xarxa. Els algoritmes presentats es poden aplicar als convertidors de potència connectats al bus DC d'una micro-xarxa AC/DC hibrida o en una micro-xarxa de DC, on el despatx de potència és observat i gestionat per un controlador central. Aquest últim adquireix dades del sistema mitjançant una infraestructura de comunicacions i estima la potència que gestionarà cadascun dels convertidors de potència, sistemes d'emmagatzematge i càrregues en funcionament. En aquest estudi es mostren la validació experimental de les estratègies de gestió aplicades en la micro-xarxa des d'un enfocament dels convertidors de potència, de les bateries i les càrregues davant d'aquesta gestió. Es verifica l'estabilitat de la micro-xarxa exposant als convertidors a diferents escenaris de funcionament. Aquest escenaris poden ser fluctuants en la irradiació, la demanda, l'estat de càrrega de les bateries, els límits màxims d'exportació/importació de potència des de/cap a la micro-xarxa cap a/des de la xarxa principal i de la tarifa elèctrica. Addicionalment, es proposa un sistema d'emmagatzematge d'energia en bateries encarregats de mantindre l'equilibri de potència al bus DC de la micro-xarxa i que permet aprofitar les fonts de generació renovables presents en la micro-xarxa i maximitzar el temps de servei de les bateries mitjançant l'aplicació d'un algoritme de càrrega de bateries. Aquest últim s'ajusta al procediment de càrrega especificat pel fabricant, establint les taxes de càrrega en funció dels escenaris en que la micro-xarxa es trobe. El procediment de càrrega a les bateries es fonamental per garantir les condicions adequades d'operació de les mateixes, ja que prenen en consideració els paràmetres establerts pel fabricant, com ara són: taxes de càrrega/descàrrega, tensió màxima de càrrega, temperatures d'operació, etc. / [EN] Two critical aspects in microgrids operation are the control and power management strategies, which are essential for their efficient operation. The adequate application of these strategies allows compensating the power imbalance caused by the discontinuity in the energy generation or changes in the power demand of the microgrid. In this sense, the overall objective of these power management strategies is to keep the power balance between the generation and the demand in the microgrid through the application of different algorithms that fulfill the criteria of stability, protection, smooth transitions and synchronization with the main grid. In the case of small-scale microgrids with a low number of distributed generators and energy storage systems, the centralized control strategies offer a higher level of flexibility to achieve advanced features in the microgrid and for the suitable power sharing between the converters that compose it. This thesis has been focused on centralized power management algorithms of a microgrid working in grid connected mode. These algorithms can be applied to the power converters connected to the DC bus of both hybrid AC/DC and DC microgrids, where the power dispatch is controlled by a central controller which acquires system data through a communication infrastructure and sets the power to be managed by each of the converters under operation. In this thesis, the experimental validation of the power management strategies of the microgrid is presented, from the point of view of the behavior of the power converters, batteries and loads. It is provided with a realistic evaluation under different microgrid operation scenarios. These scenarios were sudden changes of the irradiation, load, state of charge, the maximum power to be exported/imported from/to the microgrid to/from the grid, and the electricity tariff. Additionally, it is proposed a battery energy storage system that keeps the power balance at the DC bus of the microgrid, taking advantage from the renewable energy sources and adjusting the battery energy storage through a suitable charging procedure specified by the manufacturer. The proposed procedure changes the charging parameters of the batteries depending on the microgrid states. Its goal is to extend the service time of batteries and to allow proper energy management in the system. / Salas Puente, RA. (2019). Gestión eficiente de los convertidores de potencia conectados al bus DC de una Microrred híbrida de generación distribuida [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/118658 / TESIS

With increasing intermittency from renewable energy production, such as solar and wind power, the need for increased flexibility is quickly arising. The Åland Islands have an ambitious energy transition agenda with the goal of having a 100 % renewable energy system. Since there is no possibility of hydropower acting as regulatory power on Åland, reaching the goal is a challenging task. Increasing flexibility can be achieved by either implementing energy storage in the system or by matching the demand with the production.   The purpose of this study was to estimate and evaluate the technical potential of demand response (DR) on Åland, both in 2019 and for a scenario in 2030 when domestic production of wind and solar have increased. Six areas of interest were identified; electric heating, refrigeration processes, lighting, ventilation and air conditioning, electric vehicles and industries. Electricity import from Sweden to Åland was examined since high import coincides with either low domestic renewable production or high consumption. Import is therefore a good indicator for when flexibility is most required.  The results show that the technical potential of DR on Åland can lower the maximum electricity import from Sweden by 18 % in 2019. 4.3 % of the total import can be moved to times when there is less stress on the grid. Electric heating is the biggest contributor, and can by itself lower the import with three fourths of the total reduction. The domestic renewable production for 2019 is too low for DR to have an effect on the self-sufficiency. In 2030, the self-sufficiency and utilization of domestic renewable production could be increased with 4.2-9.9 % and 5.4-12 % respectively when using DR, depending on if vehicle-to-grid is implemented on a large scale or not. The cost of implementing DR is still uncertain, and varies between different resources. Nonetheless, DR in electric heating is presumably a less expensive alternative in comparison to batteries, while providing a similar service.

As manufacturing is creating welfare and prosperity, it is important for humankind. Nevertheless, manufacturing is causing the depletion of natural resources, environmental burdens affecting the health of animals, humans and eco-systems, and social conflicts. Thus, it is essential to implement sustainability into manufacturing. Paint shops are however known for being liable for a big part of the large energy consumptions within manufacturing. Therefore, it is necessary to investigate what cost-effective solutions can be implemented in paint shops in order to reduce the energy consumption in a sustainable manner. Hence, the aim of this study was to, from a manufacturing perspective identify possible cost-effective solutions for lowering energy consumption within paint shops. The aim was further divided into two research questions: • RQ1: What are the enablers for energy efficient paint shops? • RQ2: What are the challenges for energy efficient paint shops? The research approach used to answer the aim and research questions were a literature review and a case study. The literature review was performed to get a deeper understanding of the subject and was then complimented with the findings from the case study. The case study was performed at the paint shop of a global automotive manufacturing company in Sweden, which currently have a high energy consumption. The enablers identified were (1) implementation of solar photovoltaic, and an energy storage system, which enables an environmentally friendly way of generating energy on-site and store excess energy for later use. The energy storage system can also be used to save money by utilizing the fluctuating electricity market prices, charging the battery when the energy price is at its lowest. (2) Implementation of an UV-curing system and paint, which is an environmentally harmless method of curing paint. (3) Reducing or disabling the heating, ventilation and air conditioning system of a building when it is not a necessity. (4) Workers commitment and motivation towards sustainability, to ensure everyone’s participation. The challenges identified were (1) the expensiveness of sustainability, allocating and prioritizing it in budgets is challenging for a company since profitability is always a major concern that often overshadows sustainability. (2) The risk of modifying the processes within the paint shop, as the consequences are unexplored. (3) In its current state, the energy consumption of the paint shop is very high, it is hence difficult to provide the whole paint shop with solely solar photovoltaic. (4) An energy storage system requires space and freeing up that space is a challenge without reconstructing existing facilities. (5) With implementation of UV- curing, the paint used must be curable with UV-light. Additionally, complex three-dimensional shapes make it challenging to properly cure evenly with UV-curing. (6) It is not guaranteed whether it is possible to completely shut down heating, ventilation and air conditioning since industrial equipment in general is designed to always run. (7) Sustainability is not a focus and even if it is increasingly requested by society, the commitment of companies is experienced as low. It is challenging to motivate all the employees to work towards sustainability and find ways to always keep sustainability in mind and to prioritize it over other alternatives.

In a smart city, it is vital to provide a clean and green environment by curbing air pollution and greenhouse gas emissions (GHGs) from transportation. As a recent action from many governments aiming to minimize transportation’s pollution upon the climate, new plans have been announced to ban cars with gas engines throughout the world. Therefore, it is anticipated that the presence of electric vehicles (EVs) will grow very fast globally. Consequently, the necessity to establish electric vehicle supply equipment (EVSE) in the smart city through public charging stations is growing incrementally year by year. However, the EV charging process via EVSE which is primarily connected to the power grid will put high pressure upon the centralized power grid, especially during peak demand periods. Increasing the power production of power grid will increase the environmental impact. Therefore, it is fundamental for the smart city to be equipped with a modern power grid to cope with the traditional power grid’s drawbacks. In this thesis, we conduct an in-depth analysis of the problem of EVs’ interaction with the modern power grid in a smart city to manage and control EV charging and discharging processes. We also present various approaches and mechanisms toward identifying and investigating these challenges and requirements to manage the power demand. We propose novel solutions, namely Decentralized-EVSE (D-EVSE), for EVs’ charging and discharging processes based on Renewable Energy Sources (RESs) and an energy storage system. We present two algorithms to manage the interaction between EVs and D-EVSE while maximizing EV drivers’ satisfaction in terms of reducing the waiting time for charging or discharging services and minimizing the stress placed on D-EVSE. We propose an optimization model based on Game Theory (GT) to manage the interaction between EVs and D-EVSE. We name this the decentralized-GT (D-GT) model. This model aims to find the optimal solution for EVs and D-EVSE based on the concept of win-win. We design a decentralized profit maximization algorithm to help D-EVSE take profit from the electricity price variation during the day when selling or buying electricity respectively to EVs or from the grid or EVs as discharging processes. We implement different scenarios to these models and show through analytical and simulation results that our proposed models help to minimize the D-EVSE stress level, increase the D-EVSE sustainability, maximize the D-EVSE profit, as well as maximize EV drivers’ satisfaction and reduce EVs’ waiting time.

Battery Storage Systems (BESS) installed Behind the Meter (BTM) can provide demand management services, reducing electricity costs and enhancing overall electricity system stability. BTM BESS can also imporve self-consumption obtained with distributed generation assets like solar photovoltaics. This study examines the influence on value creation from consumption patterns and utility tariffs. Using Swedish and UK tariffs and a set of consumption profiles, the study determines the optimal BESS configuration and conducts simulations to assess profability through Net Present Value. Comparative analysis reveals the impact of utility tariffs and consumption profiles on profitablility. Projected BESS cost levels for 2030 and 2050 are used to evaluate expected future profitability.  The findings indicate that utility tariff has a stronger influence on BTM BESS profitability than consumption profile. Energy arbitrage creates most of the value, depending more on tariff structure than consumption pattern. However, with higher demand charges, the consumtion profile becomes more important as the relative value of peak shaving increases. Two sensitivity analyses have been performed. The first shows that NPVs are affected by decreased electricity price variability, emphasising the need for accurate long-term price forcasts. The second shows that existing electricity consumption forecasting techniques prove sufficient for effective peak shaving.  In conclusion, this research inderscores the significance of utility tariffs and consumption profiles in determining BTM BESS profitability. Energy arbitrage dominates value creation, while peak shaving gains importance with higher demand charges. Accurate long-term price forecasts are crucial for assessing BTM BESS profitability, and existing consumption forecasting techniques are suitable for peak shaving. / Batterilagring installerad bakom elmätaren kan optimera en fastighets elkonsumtion för att reducera elkostnader samt förbättra stabiliteten i elsystemet som helhet. Den här studien undersöker faktorer som påverkar värdeskapande genom energiarbitrage och peak shaving, inklusive konsumtionsprofiler och eltariffer. Studien undersöker även om det går att uppnål önsamhet under nuvarande och framtida prisnivåer för batterilagring. Studien utgår ifrån svenska och brittiska eltariffer samt fem konsumtionsprofiler, och fastställer den mest optimala konfigurationen av batterilagring genom optimering. Därefter jämförs lönsamheten genom nettonuvärde-analys för att dra slutsatser om hur eltariff och konsumtionsprofil påverkar lönsamhet. Studien visar att lönsamhet för batterilagring bakom mätaren beror mer på eltariff än konsumtionsprofil. Detta eftersom mest värde skapas genom energiarbitrage som är mindre beroende av konsumtionsprofil men direkt beroende av variationer i elpriset. Med högre effektavgifter ökar lönsamhetens beroende av konsumtionsprofilen då det relativa värdet av peak shaving höjs. En känslighetsanalys visar på en stark korrelation mellan värdet av energiarbitrage och variationer i elpriset, vilket visar vikten av långsiktiga prognoser av elprisets volatilitet. Befintliga tekniker för prognostisering av elkonsumtion har tillräcklig noggrannhet för effektivpeak shaving. Sammanfattningsvis visar studien hur eltariff och konsumtionsprofil påverkar lönsamheten för batterilagring installerad bakom elmätaren. Majoriteten av värdet skapas genom energiarbitrage för svenska och brittiska tariffer. Med högre effektavgifter ökar betydelsen av peak shaving. Dessutom betonar studien vikten av långsiktiga prognoser av elprisvolatilitet vid utvärderingen av lönsamheten för investeringar i batterilagring bakom mätaren.

Research has shown that three-phase balancing alone can improve the operation of secondary distribution networks and that the addition of energy storage to the phase balancing power electronics further helps to alleviate the negative effects of phase unbalances. However, less attention has been paid to the economic potential of said technologies and particularly for loadside implementation. It appears that the deployment of phase balancers, with or without energy storage, is indeed hampered by uncertainty related to its economic feasibility, despite both technologies being commercially available. This thesis therefore aims to assess and compare the economic feasibility of the two configurations for peak shaving purposes in the context of residential property loads in Sweden. The assessment was performed using a specially developed deterministic techno-economic model taking into consideration historical load data from three Swedish real estate, cost estimations for a range of alternatives used when sizing the systems, applicable tariffs and fees for electricity and its distribution as well as technical parameters such as the capacities and efficiencies of the involved components. A novel approach was taken by linearly extrapolating the three load profiles into three sets of 91 synthesized load profiles to enable a larger dataset for analysis. The net present values generated for each set were then graphed and analyzed per original real estate. The results showed that both configurations can be economically feasible, but only under certain conditions. A phase balancer alone was found to be feasible for real estate whose peak currents are distinctly unbalanced and exceed 50 A, with the best expected rate of return for profiles exceeding 63 A since they enable a tariff switch. The combined system was found to be even more contingent on the tariff switch and therefore only feasible for peaks above 63 A. A substantial difference in the initial investment further makes the single phase balancer the preferred choice, unless the discount rate is as low as 2 % or less. On this basis, potential investors need to assess the state of unbalance of their loads and perform their own calculation based their load profile, cost of capital and applicable tariffs. / Tidigare forskning har visat att fasbalansering enskilt kan förbättra driften hos lokala distributionsnät och att ett batterisystem i tillägg till fasbalanserarens kraftelektronik ytterligare kan minska de negativa effekterna av fasobalanser. Däremot har mindre uppmärksamhet riktats mot den ekonomiska genomförbarheten hos dessa teknologier och i synnerhet för implementation på lastens sida av elmätaren. Det tycks vara så att spridningen av fasbalanserare, med eller utan energilagring, hindras av osäkerheten kring dess ekonomiska potential trots att båda teknologierna är kommersiellt tillgängliga. Detta arbete ämnar därför att värdera och jämföra den ekonomiska nyttan hos de två konfigurationerna vid toppreducering av fastighetselen i svenska bostadsfastigheter. Värderingen utfördes med hjälp av en särskilt utvecklad deterministisk tekno-ekonomisk modell som beaktade historiska lastdata från tre svenska fastigheter, kostnadsuppskattningar för en uppsättning av konfigurationer som användes vid dimensionering av systemen, applicerbara tariffer och avgifter för elektricitet och dess distribution samt tekniska parametrar såsom kapaciteter och verkningsgrader för de olika komponenterna. Ett annorlunda tillvägagångssätt tillämpades vidare för att utöka datamängden genom linjär extrapolation av lastprofilerna, vilket resulterade i tre uppsättningar av 91 syntetiserade lastprofiler. Nettonuvärdet beräknades följaktligen för varje profil och investeringsalternativ för att sedan plottas och analyseras per ursprunglig fastighet. Resultaten visade att båda konfigurationerna kan uppvisa lönsamhet, men endast under särskilda förutsättningar. Den enskilda fasbalanseraren bedömdes som lönsam för fastigheter vars strömtoppar är påtagligt obalanserade och som överstiger 50 A, med största möjliga lönsamhet för profiler som överstiger 63 A då dessa möjliggör ett tariffbyte. Det kombinerade systemets lönsamhet bedömdes vara ännu mer beroende av tariffbytet och därför endast lönsamt för strömtoppar över 63 A. En betydligt större grundinvestering för det kombinerade systemet gör vidare att den enskilda fasbalanseraren i regel är att föredra, såvida inte kalkylräntan är så låg som 2 % eller mindre. Baserat på detta uppmanas potentiella investerare att undersöka balanstillståndet hos deras laster och att utföra en egen kalkyl baserat på deras specifika last, kapitalkostnad och nätföretag.