<p>The Renewable Energies play a rather small role so far in the overall mixture for power generation, but they increasingly gain in importance. Nevertheless an independent marketability is not given yet. To reach the development goals which are requested by the European Commission, a monetary sponsorship at the expense of electricity consumers is required. Can this governmental interference be justified? Which problems arise with the subvention?</p>

The Renewable Energies play a rather small role so far in the overall mixture for power generation, but they increasingly gain in importance. Nevertheless an independent marketability is not given yet. To reach the development goals which are requested by the European Commission, a monetary sponsorship at the expense of electricity consumers is required. Can this governmental interference be justified? Which problems arise with the subvention?

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Severe accidents in light water nuclear reactors occur when reactor vessel water inventory decreases and there is no available additional water coolant to be delivered into the core. In general, during an extended severe accident sequence a period exists in which the reactor core, after a partial or total melt down, is poured into the lower plenum that can have some water present. The study of the interaction of the melt fuel with the water is the objective of MFCI (Melt Fuel Coolant Interaction) activities.MFCI is one of the most important issues awaiting resolution in water cooled reactor safety analysis. The progression of a severe accident in a water cooled reactor can lead to energetic (steam explosion) or non-energetic (melt quenching) interactions as the molten fuel relocates and eventually interacts with the coolant either in the vessel lower head (in vessel) or in the cavity (ex-vessel).The MFCI experiments at JRC Ispra site were conducted in the FARO (Furnace And Release Oven) test facility under realistic melt composition and prototypical accident conditions to provide basic information on underlying phenomena. The experimental programme was complemented by comprehensive pre-test and post-test analytical activities based on the development and application of the thermalhydraulic COMETA (COre MElt Thermalhydraulic Analysis) code. The code is developed and assessed on the basis of experimental information acquired in the FARO facility tests, and there are some limitations and uncertainties in their application to the full plant, which need to be identified and possibly quantified.In general the main objective of the PhD research was achieved expanding the general knowledge in Melt Fuel Coolant Interaction. The knowledge was complemented collaborating and complementing the application of COMETA code under conditions not experimented before, developing and improving COMETA code sources and verifying the code consistency, analysing and unifying the COMETA simulations carried so far.Also a further analytical study was carried out in order to illustrate the MFCI inside the general overview of a NPP (Nuclear Power Plant) severe accident sequence.

Keywords: Energy Audits, Energy Efficiency, Rational Use of Energy, Life cycle assessment, Hotel buildings, Net Zero Emissions Buildings, Renewable Energy,Solar Energy, Biomass, cogeneration (CHP). This PhD analyzes the touristic facilities and proposes improvements in the energy process production and management of hotels. During the last years there have been changes related to social, economic, legislation and environment aspects that have produced a change in building designs and the process and energy systems. The tourist sector has more than 50 years in the Balearic Island¿s and has reached a level of maturity than allows for analysis and rethinking on energy production schemes. For this reason it¿s important to find a criterion of typologies of hotels and innovate in the design, management and production of energy. This can result a tool to be used to designers in the initial phase, for choose the architecture than reduce more the environment impacts, and be used to the public administration, users and managers for taking correct decisions. / La tesi analitza els establiments turístics i vol proposar millores en els processos de producció igestió energètica dels equipaments turístics. En els darrers anys s’han produït canvissociambientals, econòmics i legislatius que han provocat un canvi en els edificis, fent ques’estableixin noves estratègies i dissenys en els processos i sistemes de producció energètica.El sector turístic te més de 50 anys d’implantació a les Illes Balears, ja ha arribat a un grau demaduresa suficient per poder ser analitzat i reflexionar sobre el seu futur en l’ús de l’energia. Ésper aquesta raó que trobar un criteri de tipologies d’hotels i propostes d’innovació en el disseny,la gestió i producció de l’energia pot resultar una eina que serveixi de suport tant alsdissenyadors en l’etapa inicial, per a tal de seleccionar l’arquitectura que redueixi els impactesambientals, com també serveixi a l’administració pública, als usuaris i gestors a l’hora deprendre decisions.

The objective of this dissertation is to carry out dynamic modeling, analysis and control for Voltage-Source Converters (VSC). Two major applications of VSC will be investigated in this dissertation: microgrid application and High Voltage Direct Current (HVDC) application. In microgrid applications, VSC is used to integrate distributed energy sources such as battery and provide system functions: such as real and reactive power regulation, voltage and frequency support during islanding condition, and abnormal system condition mitigation. In HVDC applications, VSC is used to interconnect dc systems with ac systems. The functions supplied by VSC are similar to that in microgrids. However, the transfer capability and stability in such kind of system are of major interests. Therefore, Part I of this dissertation focuses on VSC's applications in microgrids. A battery's inverter can be operated in both grid-connected PQ regulation mode and voltage and frequency support mode during islanding condition. Transition scheme between these two control modes is firstly investigated to guarantee a smooth dynamic performance. Secondly, a coordinated control strategy between battery's and PV station's VSCs is developed to improve microgrid's power flow. Thirdly, power quality improvement through the battery's inverter is investigated. VSC's control and capability for microgrid operation at normal, transient, and abnormal conditions will be modeled and analyzed. Part II of this dissertation focuses on VSC's applications in HVDC. The following topics are investigated in this dissertation: (i) how to design VSC-HVDC's controller using system identification method? (ii) How to coordinate VSCs in multi-terminal HVDC scenarios? And (iii) how to determine VSC-HVDC system's transfer capability based on stability limits? High-fidelity simulation technology is employed to tackle control validation while frequency domain impedance modeling technique is employed to develop analytical models for the systems. With linear system analysis tools such as Nyquist plots and Bode plots, stability limits and impacting factors of VSC-HVDC systems can be identified. This dissertation led to four journal papers (two accepted, one request of revision, one to submit) and five conference papers. The major contributions of this dissertation include: 1) Developed VSC and microgrid models in high-fidelity simulation environment. Developed and validated VSC control schemes for variety of microgrid operations: normal, abnormal, and transient. The developed technologies can facilitate a battery to make up solar power, improve system dynamic performance during transients, and improve power quality. 2) Developed VSC-HVDC simulation models, including two-terminal HVDC and multi-terminal HVDC. Developed VSC-HVDC control schemes for two-terminal and multi-terminal systems. Developed analytical impedance models for VSC-HVDC systems and successfully carried out stability limit identification.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / A presente dissertaÃÃo apresenta o desenvolvimento de uma ferramenta computacional de auxÃlio ao planejamento energÃtico chamada de GDHER (GeraÃÃo DistribuÃda de Sistemas HÃbridos de Energias RenovÃveis) A ferramenta pode ser utilizada sem custo uma vez que foi desenvolvido atravÃs do Calc um programa de planilha eletrÃnica semelhante ao Excel que faz parte de um pacote de vÃrios aplicativos livres da Broffice ApÃs identificar algumas limitaÃÃes dos principais softwares disponÃveis no mercado foi desenvolvida uma nova ferramenta adaptada à realidade brasileira principalmente voltada Ãs Ãreas rurais e isoladas que utiliza o portuguÃs como idioma e possui uma interface bastante amigÃvel facilitando sua compreensÃo e operaÃÃo pelo usuÃrio A ferramenta permite o usuÃrio fazer dimensionamento de algumas modalidades de geraÃÃo de energia elÃtrica a partir de tecnologias limpas como a solar fotovoltaica aerogeradores e biodigestores e atravÃs de uma anÃlise financeira esses sistemas sÃo comparados com a extensÃo da rede de energia elÃtrica permitindo que o usuÃrio obtenha um prognÃstico de viabilidade A ferramenta tambÃm permite fazer o dimensionamento e a anÃlise financeira de configuraÃÃes de sistemas hÃbridos como fotovoltaico-eÃlico fotovoltaico-biodigestor e biodigestor-eÃlico a fim de encontrar a configuraÃÃo Ãtima para o projeto Para validaÃÃo da ferramenta foi feito um estudo de caso e a partir da anÃlise financeira e anÃlise de sensibilidade a modalidade de fornecimento de energia elÃtrica mais viÃvel para os sistemas individualizados sÃo os biodigestores em seguida sÃo os mÃdulos fotovoltaicos e a rede elÃtrica e por Ãltimo sÃo os aerogeradores De acordo com a anÃlise financeira dos sistemas hÃbridos a configuraÃÃo mais lucrativo à 75% da demanda sendo atendida por biodigestores e 25% por mÃdulos fotovoltaicos Os resultados sÃo apresentados atravÃs de tabelas e grÃficos para melhor compreensÃo do usuÃrio Com todas essas caracterÃsticas a ferramenta proposta permite dimensionar sistemas com mÃxima eficiÃncia e menor custo obtendo assim sistemas mais adequados e confiÃveis tanto do ponto de vista tÃcnico como financeiro / This work presents the development of a computational tool to aid in energy planning called GDHER (Distributed Generation of Hybrid Systems for Renewable Energy) The program can be used without cost since it was developed through the Calc a program of electronic spreadsheet similar to Excel which is part of a package of several free applications of Broffice After identifying some limitations of the main software available on the market we obtained a new tool adapted to the Brazilian reality especially to rural and isolated areas which uses the portuguese as language and has an interface very user friendly facilitating the understanding and operation of the program by the user The program allows the user to do the scaling of some methods of electricity generation from clean technologies such as solar photovoltaics wind turbines and biodigesters and through a financial analysis these systems are compared with the extension of the network of electric energy allowing the user get a prognosis of viability The tool also allows the user to do the scaling and the financial analysis of some configurations of hybrid systems like photovoltaic-wind photovoltaic-digester and wind-digester in order to find the optimal configuration for the project For validation of the program it was done a case study and from the financial analysis and sensitivity analysis the modality of electric energy supply more viable for individualized systems are the digesters then are the photovoltaic modules and the electrical network and finally are the wind turbines According to the financial analysis of hybrid systems the configuration more profitable is 75% of demand being served by biodigesters and 25% by photovoltaic modules The results are presented using tables and graphs for better understanding of the user With all these features the tool allows to scale systems with maximum efficiency and lower costs thereby obtaining more appropriate and reliable systems both from the technical point of view as financial

Light-matter interactions lead to a variety of interesting phenomena, for example photosynthesis which is a process fundamental to life on earth. There exists many different spectroscopic methods to measure light-matter interactions, for example UV/Vis spectroscopy, that can provide information about electronically excited states. However, numerical methods and theory are important to model and gain understanding of these experiments. Quantum chemistry provides that understanding, giving the possibility to numerically calculate molecular properties like excitation energies. The aim of this thesis was to implement a reduced-space algorithm in Dalton, to solve an eigenvalue equation obtained by response theory, for the calculation of excitation energies of molecular systems. There already was a similar algorithm in Dalton, that was able to perform these calculations. However, in a different module of Dalton used mainly for complex response theory, an algorithm to obtain eigenvalues was missing. The new implementation was similar to the existing one, except for the division of the reduced space into even and odd parts used in the complex response module. The thesis starts with a quick introduction of light-matter interactions and proceeds with a description of many-body theory, including numerical methods used in that field. In the end of the theoretical part, the eigenvalue equation, used to calculate excitation energies, is derived. In the following section, the reduced-space algorithm is described. In the end of the thesis, numerical results obtained with the algorithm are presented, including a small basis set and method study. The comparison with the existing implementation of the similar algorithm verified the successful implementation of the algorithm presented in this thesis.

The physisorption of Kr on graphitic amorphous carbon (g-C) has been investigated using a statistical approach. The interaction energy calculation process (i) established a structural model of g-C and (ii) determined the adsorbate-adsorbate and the adsorbate-substrate interaction potentials on g-C. The structural model of g-C was divided into three regions. For the interaction potential between a Kr atom and a carbon atom the short and medium range order of g-C was described with a discrete medium model based on three ring clusters using ring statistics from Beeman's continuous random network C1120 model of g-C. For the intermediate distance region, Beeman's radial distribution function was used to model g-C. A homogenous and isotropic continuous medium model was used at large distances. The Kr-Kr and Kr-g-C interaction potentials used for Kr on g-C, which are pair-wise Lennard-Jones 6-12 potentials, are similar to Kr on graphite potentials. the validity of the model for g-C and the potentials were verified though calculations for Kr on graphite. Results compared favorably with recent literature values. The interaction energy calculation results for Kr on a g-C substrate assert that (i) Kr adlayers will form on g-C, (ii) the structure of the Kr adlayer is governed by the substrate corrugation at low coverage and by the Kr-Kr interaction at high coverage, and (iii) there is no direct relation between the structure of Kr adlayers on g-C and those on graphite. The average binding energy of Kr on g-C is comparable with that on graphite, but the corrugation of g-C is perhaps six times that of a graphite substrate. The wrinkling of the g-C surface, due to the presence of a distribution of 5-, 6-, and 7- membered rings, is responsible for this large corrugation of the g-C substrate.

One of the Sustainable Development Goals set in 2015 by the United Nations aims to ensure access to affordable, reliable, sustainable, and modern energy for all, increasing the global share of renewable energy to 32-35% by 2030. Moving towards this goal, the University of Trento funded the interdepartmental strategic project ERiCSol (Energie Rinnovabili e Combustibili Solari), in order to promote the research on renewable energy storage and solar fuels. The research activity presented in this thesis lies in the framework of this project, focusing on the development of new advanced simulation approaches to improve the estimation of the wind resource availability and the related power production for Italian wind farms in complex terrain. The wind farms, operated by the company AGSM S.p.A., are located in two different geographical contexts: Rivoli Veronese and Affi are at the inlet of the Adige Valley, while Casoni di Romagna and Carpinaccio Firenzuola, are on the crest of the Apennines close to the borders between the provinces of Bologna e Firenze. The analysis of data from year-long field measurements highlighted the different peculiarities of these areas. The wind farms at the mouth of the Adige Valley are influenced by a daily periodic thermally-driven circulation, characterised by a nocturnal intense down-valley wind alternating with a diurnal weaker up-valley wind, while the Apennines wind farms are primarily affected by synoptic-scale winds. Simulations, with the mesoscale Weather Research and Forecasting (WRF) model, are performed and compared with field measurements in both cases, to highlight strengths and weaknesses. The results show that the model is able to capture with good accuracy wind speed and direction in the Apennines wind farms, while larger errors arise for Rivoli Veronese and Affi wind farms, where the intensity of the nocturnal down-valley wind is generally underestimated. Considering the former case, modelled and observed yearly wind speed density distributions are compared, in order to evaluate the impact of model errors in the estimation of the wind resource at these sites. Since reliable simulations of the wind resource are also essential to ensure the security in power transmission and to prevent penalties to energy operators, an analysis of the power production is also performed, to evaluate how errors in the estimate of the resource translate into errors in the estimate of the production. Considering the wind farms at the mouth of the Adige Valley, the research work mainly focuses on the evaluation of the impact of data assimilation by means of observational nudging on model results, in order to optimize the setup for operational forecasts. Different configurations are tested and compared, varying the temporal window for the assimilation of local data.