After the nuclear fallout in Japan, Germany decided to back out from nuclear energy while at the same time changing the energy supply from fossil to renewable sources. This elaborate plan, known as Energiewende, will require significant economic and structural efforts that will have profound impacts on the environment and society itself. It is therefore crucial to identify possible technological pathways that can lead to a renewable energy supply, while reducing negative impacts on a holistic scope. In order to analyse alternative energy technology scenarios in Germany, this thesis focuses on the development of an indicator-based numerical Sustainable Energy Systems (SEnSys) model approach. Other than previous approaches, the SEnSys model considers full aggregated impacts of technological pathways leading to future configurations. With the help of an exemplary case study on two alternative energy technology scenarios (Trieb1 and Trieb2), the feasibility of the SEnSys model in evaluating sustainability is subsequently assessed. The results can affirm the findings of previous studies concerning lower economic and environ- mental impacts for scenario Trieb2, with small shares of renewable energy imports, compared to scenario Trieb1 based on only local but fluctuating renewables. Additionally, the results are in accordance with other relevant studies, while offering new valuable insights to the topic. Given a comprehensive revision of the identified uncertainties and limitations, it can be stated that the SEnSys model bares the potential for further analysing and improving sustainability of energy technology scenarios in Germany and other countries.

Penetration of renewable energy generators into energy systems is increasing. The intermittency and variability of these generators makes supplying energy reliably and cost effectively difficult. As a result, storage technologies are proposed as a means to increase the penetration of renewable energy, to minimize the amount of curtailed renewable energy, and to limit the amount of back-up supply. Therefore, methods for determining an energy system’s storage requirements are being developed. This thesis investigates and details four existing methods, proposes and develops a fifth method, and compares the results of all five methods. The results show that methods which incorporate cost, namely the Dynamic Optimization and the Abbey method, consistently yield the most cost effective solutions. Under excellent renewable energy conditions the results show that the cost-independent methods of Korpaas, Barton, and the Modified Barton method produce solutions that are nearly as cost effective but have greater reliability of energy supply than the Dynamic Optimization and Abbey solutions. This thesis recommends a new path of research for the Modified Barton method: the incorporation of cost through the confidence level. This thesis also recommends the development of new sizing methods from various aspects of the methods presented. / Graduate

Multi-objective optimization metaheuristics (MOMs) are powerful methods for solving complex optimization problems but can require a large number of function evaluations to find optimal solutions. Thus, an efficient multi-objective optimization method should generate accurate and diverse solutions in a timely manner. Improving MOMs convergence speed is an important and challenging research problem which is the scope of this thesis. This thesis conducted the most comprehensive comparative study ever in MOMs. Based on the results, multi-objective (MO) versions of particle swarm optimization (PSO) and differential evolution (DE) algorithms achieved the highest performances; therefore, these two MOMs have been selected as bases for further acceleration in this thesis. To accelerate the selected MOMs, this work focuses on the incorporation of leadership concept to MO variants of DE and PSO algorithms. Two complex case studies of MO design of renewable energy systems are proposed to demonstrate the efficiency of the proposed MOMs. This thesis proposes three new MOMs, namely, leader and speed constraint multi-objective PSO (LSMPSO), opposition-based third evolution step of generalized DE (OGDE3), and multi-objective DE with leadership enhancement (MODEL) which are compared with seven state-of-the-art MOMS using various benchmark problems. LSMPSO was found to be the fastest MOM for the problem undertaken. Further, LSMPSO achieved the highest solutions accuracy for optimal design of a photovoltaic farm in Toronto area. OGDE3 is the first successful application of OBL to a MOM with single population (no-coevolution) using leadership and self-adaptive concepts; the convergence speed of OGDE3 outperformed the other MOMs for the problems solved. MODEL embodies leadership concept into mutation operator of GDE3 algorithm. MODEL achieved the highest accuracy for the 30 studied benchmark problems. Furthermore, MODEL achieved the highest solution accuracy for a MO optimization problem of hydrogen infrastructures design across the province Ontario between 2008 and 2025 considering electricity infrastructure constraints.

Globalt utgör byggnader för mer än 40% av världens energianvändning. I EU är 35% av byggnaderna mer än 50 år gamla samtidigt som 75% av dem är energiineffektiva. Byggnader från bland annat det svenska miljonprogrammet, den tid då en miljon bostäder byggdes mellan åren 1965 och 1974 i Sverige, är i behov av att rustas upp och energieffektiviseras för att de inte ska nå slutet av sin tekniska livslängd. I detta projekt jämförs tre energisystem på tre olika fastigheter i södra Sverige. Ett FX-system med fjärrvärmecentral i Lund, en spillvattenanläggning i Växjö och ett äldreboende i Ronneby med solhybrider och borrhål.  Jämförelsen görs bland annat genom en ekonomisk analys med LCC, återbetalningstid och investeringens minskning av primärenergianvändning. Genom en energiteknisk analys har jämförelser fastställts gällande energiförbrukning, potentiell energi att ta vara på ur frånluft och spillvatten samt förändringen av fastigheternas energideklarationer före och efter installation utifrån BBR29 i Boverkets Gripen tillsammans med en certifierad oberoende energiexpert. Jämförelsen har även lyft för- och nackdelar med de olika systemen. FX-systemet med fjärrvärmecentral medför risk för kallras och att obehandlad luft tas in i fastigheten, däremot är installationen enkel om lämplig i fastigheter med frånluftskanaler. Spillvattenanläggningen är beteende beroende och begränsas av en lägsta returtemperatur men möjliggör energiåtervinning ur spillvatten samt att solhybrider med borrhål begränsas av tillgången på användbar mark för installation men producerar både värme och el.  Resultatet av den ekonomiska analysen blev att återbetalningstiden, utan hänsyn till kalkylränta, var kortast för solhybridanläggningen med borrhål som var omkring 9 år medan spillvattenanläggningen hade längst återbetalningstid på 95 år. FX-systemet med fjärrvärmecentral hade en återbetalningstid på 22 år medan endast FX-systemet hade 11 år.  Utifrån den energitekniska analysen minskade solhybridanläggningen med borrhål primärenergitalet från energideklarationen mest med 61 kWh/Atemp, år motsvarande 33,7%, medan FX-systemet med fjärrvärmecentral minskade med 24 kWh/Atemp, år motsvarande 21,0%. För spillvattenanläggningen minskade primärenergitalet minst av de tre anläggningarna med 6 kWh/Atemp, år motsvarande 7,8%. Solhybridanläggningen med borrhål hade det högsta årliga anläggnings COP på 5,3 medan FX-systemet med fjärrvärmecentralen hade 3,9. Lägst årligt anläggnings COP hade spillvattenanläggningen med 3,8. Energin, för de standardiserade frånlufts- och spillvattenflödena, var att frånluften innehöll 2,4 gånger mer energi att ta vara på än spillvattnet. Spillvattnet hade 26,4 kWh/Atemp, år medan frånluften hade 64,4 kWh/Atemp.  En av slutsatserna med projektet var att spillvattenåtervinningen inte lämpar sig som första renoveringsåtgärd utan mer som effektivisering av redan energieffektiva byggnader som behöver reducera energianvändningen ytterligare. Installation av solhybrider med borrhål var lönsammast, men begränsas av markyta för borrhålen. FX-systemet lämpar sig för fastigheter med befintligt frånluftssystem.

Thesis (Ph. D.)--Drexel University, 2004. / Includes abstract and vita. Includes bibliographical references (leaves 124-133).

Η παρούσα διπλωματική εργασία πραγματεύεται τη μελέτη της επίδρασης ενός αιολικού συστήματος στην ευστάθεια ενός κοινού συστήματος ηλεκτρικής ενέργειας κατά τη λειτουργία της μόνιμης κατάστασης. Πιό συγκεκριμένα: Στο πρώτο κεφάλαιο γίνεται μία εισαγωγή σχετικά με την χρήση της αιολικής ενέργειας από τα παλαιά χρόνια έως και σήμερα, αλλά και στοιχείων που αφορούν τόσο την Ελλάδα αλλά και άλλες χώρες. Στο δεύτερο κεφάλαιο αναλύονται τα αιολικά συστήματα ως προς τη δομή τους, τη λειτουργία τους, τα προβλήματα που προκαλούν αλλά και τα οφέλη που αποφέρουν. Στο τρίτο κεφάλαιο ακολουθεί μία κατηγοριοποίηση των συστημάτων ανεμογεννητριών ως προς τον τύπο γεννήτριας που περιέχουν αλλά και τον τρόπο λειτουργίας τους. Στο τέταρτο κεφάλαιο γίνεται ανάλυση της διείσδυσης της αιολικής ενέργειας ως προς την κλίμακα διείσδυσης (μικρή – μεγάλη), τις προϋποθέσεις σωστής χρησιμοποίησής τους καθώς και των προβλημάτων που προκύπτουν σχετικά με την ευστάθεια τάσης αλλά και τη συχνότητα. Στο πέμπτο κεφάλαιο περιγράφεται η ανάλυση ροής φορτίου και πίο συγκεκριμένα η μέθοδος Newton-Raphson που χρησιμοποιήσαμε για την πραγματοποίηση του πειραματικού κομματιού αυτής της εργασίας. Στο έκτο κεφάλαιο παρουσιάζονται οι προσομοιώσεις που πραγματοποιήσαμε μαζί με τα αποτελέσματα που προέκυψαν. Τέλος στο έβδομο κεφάλαιο ακολουθεί σχολιασμός των παραπάνω αποτελεσμάτων. / This diploma thesis examines the influence of a wind energy system on the stability of a common electric power system during the steady state operation. More specifically: In the first chapter, there is an introduction related to the usage of wind energy from the past years up to nowadays, and also facts related not only to Greece but also other countries. In the second chapter, the wind energy systems are analyzed for their structure, the way they operate, the problems they cause and the benefits they yield. In the third chapter, there is a categorization of the wind energy systems in terms of the generator type the use and the state they operate. In the fourth chapter, there is an analysis of the wind power integration depending on the integration scale (small-scale – large-scale), the conditions of correct usage, as well as the problems that appear and are related to the voltage stability and the frequency. In the fifth chapter, the load flow procedure is described and more particularly the Newton-Raphson procedure that was used in this case. Ιn the sixth chapter, the simulation is presented along with the results. Finally, in the seventh chapter there are comments related to the results above.

Σκοπός της παρούσας διπλωματικής εργασίας είναι η μελέτη των παραγόντων που επηρεάζουν την αξιοπιστία και τη διαθεσιμότητα των αιολικών συστημάτων. Η επεξεργασία των ανεμολογικών δεδομένων (SCADA) έγινε από διάφορες εταιρείες, για να βοηθήσουν στην πρόβλεψη της ενεργειακής παραγωγής. Εξετάζονται επίσης τα διάφορα είδη βλαβών που συμβαίνουν στα αιολικά πάρκα, ειδικά τα πρώτα χρόνια λειτουργίας τους, και πώς ακριβώς μπορούμε να μειώσουμε το ποσοστό τους αν επέμβουμε σωστά. Τέλος, δίνονται χρήσιμες πληροφορίες για το βαθμό χρησιμοποίησης της αιολικής ενέργειας στην Ελλάδα και παγκόσμια. Πιο αναλυτικά, η δομή της εργασίας οργανώνεται στα εξής εννέα κεφάλαια: Το πρώτο κεφάλαιο ξεκινάει με γενικές πληροφορίες για τις ανανεώσιμες πηγές ενέργειας και γιατί η χρήση τους έγινε επιτακτική. Κατόπιν, γίνεται εξειδίκευση στην αιολική ενέργεια με μια ιστορική αναδρομή για να μπορέσει να δει κανείς την εξέλιξη της στο πέρασμα του χρόνου. Αναφέρονται επίσης τα πλεονεκτήματα της αιολικής ενέργειας, τα προβλήματα που προκύπτουν από την αξιοποίησή της καθώς και διάφορες λύσεις για την αντιμετώπισή τους. Στο δεύτερο και τρίτο κεφάλαιο εξετάζεται η βασικότερη παράμετρος που οδήγησε την αιολική ενέργεια στο στάδιο που είναι σήμερα, ο άνεμος. Αναλύεται η συμπεριφορά του, τα κύρια χαρακτηριστικά του και η κατανομή του. Το τέταρτο κεφάλαιο παρουσιάζει τις μονάδες που συμβάλλουν στη δέσμευση και εκμετάλλευση της αιολικής ενέργειας. Παρουσιάζονται με λεπτομέρεια τα δομικά τους στοιχεία και αναφέρονται οι κατηγορίες στις οποίες ανήκουν ανάλογα με τα χαρακτηριστικά τους. Αναφέρονται επίσης, οι βασικοί τρόποι λειτουργίας τους καθώς και οι παράμετροι που επηρεάζουν την επιλογή της τοποθεσίας εγκατάστασής τους. Στο πέμπτο κεφάλαιο εξετάζονται τα ενεργειακά χαρακτηριστικά των ανεμογεννητριών και παρουσιάζονται επίσης τα στοιχεία που επιδρούν στην αναμενόμενη ενεργειακή παραγωγή και στο κόστος της αιολικής ενέργειας. Στο έκτο κεφάλαιο, δίνονται γενικές πληροφορίες για τα αιολικά πάρκα, τη λειτουργία και τη συντήρησή τους καθώς και κάποιοι οικονομικοί παράγοντες όσον αφορά τα υπεράκτια αιολικά πάρκα. Στο έβδομο κεφάλαιο παρουσιάζονται τα αποτελέσματα της επεξεργασίας ανεμολογικών δεδομένων, ώστε να γίνουν κατανοητοί οι παράγοντες που επηρεάζουν και βελτιώνουν την αξιοπιστία των αιολικών συστημάτων. Στο όγδοο κεφάλαιο, εξετάζεται και αξιολογείται η διαθεσιμότητα των αιολικών συστημάτων, δίνονται πληροφορίες για τα διάφορα είδη της καθώς και διάφοροι τρόποι οι οποίοι συμβάλλουν στη βελτίωσή της, που είναι και το ζητούμενο για την οικονομική βιωσιμότητα του αιολικού πάρκου. Τέλος, στο ένατο κεφάλαιο, παρουσιάζεται η τρέχουσα κατάσταση στην Ελλάδα, στις χώρες της Ευρωπαϊκής Ένωσης αλλά και παγκόσμια. / The purpose of this diploma thesis is the study of factors that affect the reliability and availability of wind energy systems. Wind data from several companies were accumulated for a better prediction of the energy production. More specifically, the structure of the essay is organized in the following nine chapters : The first chapter starts with general information on renewable energy sources and the reasons why their use became imperative. Moreover, there is specialization in wind energy with a throwback which enables us to see the evolution of the passing of time. The second and third chapter examines the key parameters leading wind energy in its present form, the wind. The fourth chapter presents the system-units that contribute to the exploitation of wind energy. Their components are presented in detail, and the categories to which they belong are indicated according to their characteristics. The fifth chapter discusses the energy characteristics of the wind turbines and also presents the elements that affect the expected energy production and the cost of wind energy. In the sixth chapter, general information about wind farms are given, as well as information about operation, maintenance and some economic factors in offshore wind farms. The seventh chapter presents the results of wind data processing in order to understand the factors that influence and improve the reliability of wind systems. The eighth chapter examines and evaluates the availability of wind energy systems. Information about the different types of availability are given, and also details about the different ways which contribute to the improvement of availability are presented. Finally, the ninth chapter presents the current situation in Greece, the countries of the European Union and worldwide.

Renewable energy (RE) resources are relatively unpredictable and dependent on climatic conditions. The negative effects of existing randomness in RE resources can be reduced by the integration of RE resources into what is called Hybrid Renewable Energy Systems (HRES). The design of HRES remains as a complicated problem since there is uncertainty in energy prices, demand, and RE sources. In addition, it is a multi-objective design since several conflicting objectives must be considered. In this thesis, an optimal sizing approach has been proposed to aid decision makers in sizing and performance analysis of this kind of energy supply systems. First, a straightforward methodology based on ε-constraint method is proposed for optimal sizing of HRESs containing RE power generators and two storage devices. The ε-constraint method has been applied to minimize simultaneously the total net present cost of the system, unmet load, and fuel emission. A simulation-based particle swarm optimization approach has been used to tackle the multi-objective optimization problem. In the next step, a Pareto-based search technique, named dynamic multi-objective particle swarm optimization, has been performed to improve the quality of the Pareto front (PF) approximated by the ε-constraint method. The proposed method is examined for a case study including wind turbines, photovoltaic panels, diesel generators, batteries, fuel cells, electrolyzers, and hydrogen tanks. Well-known metrics from the literature are used to evaluate the generated PF. Afterward, a multi-objective approach is presented to consider the economic, reliability and environmental issues at various renewable energy ratio values when optimizing the design of building energy supply systems. An existing commercial apartment building operating in a cold Canadian climate has been described to apply the proposed model. In this test application, the model investigates the potential use of RE resources for the building. Furthermore, the application of plug-in electric vehicles instead of gasoline car for transportation is studied. Comparing model results against two well-known reported multi-objective algorithms has also been examined. Finally, the existing uncertainties in RE and load are explicitly incorporated into the model to give more accurate and realistic results. An innovative and easy to implement stochastic multi-objective approach is introduced for optimal sizing of an HRES. / February 2016

This master thesis examines the energy efficiency of preheating outdoor air in ventilation systems by using geothermal heat from boreholes. Energy efficiency in this context only relates to minimise the energy consumption and to minimise the peak power consumption during cold days. Preheating the outdoor air before it enters the heat exchanger is a techinque that is used to avoid frost formation in the heat exhanger. The aim of preheating the outdoor air is to reduce the energy consumption in the buidling and to reduce the peak power consumption during cold days. In this project a buliding in Töfsingdalen, Stockholm, is investigated. In one part of the building the outdoor air is preheated while the air in another part of the building is not. The investigation is partly based on an analysis of measured temperaures in the building’s ventilation system during 2017. The results of the analysis show that the heat exchanger in the air-handling unit with preheating has not been defrosted during the investigated period. In this thesis, models are also constructed to simulate the system. The models are created in the simulation programme IDA ICE, wich is a simulation tool for bulidings. The simulations show that the total energy consumption is 1.2 kWh/m2Atemp, year higher and the maximal power consumption is 18 kW lower for the system that preheats the outdoor air compared to the system without preheating. In addition to this, the conclusion of this report is that the energy efficiency of preheating the outdoor air depends on the type of heat exchanger. A heat exchanger with high efficiency results in a lower peak power consumption than a heat exchanger wth a lower efficiency. Futhermore, the results show that geothermal preheating is better from an energy perspective when heat exchangers with moderate as opposed to high efficiencies are used. The energy efficiency of preheating outdoor air in ventilation systems also depends on the outdoor climate and the control strategy of the preheating. In this report, the control strategy for the preheating system in Töfsingdalen has been optimised in order to reduce the energy consumption in the building.

Cette thèse interroge l'existence d'une utopie environnementale de coopération entre Nature et Technique dans le secteur de l'énergie, qu'il s'agisse d'énergie renouvelable au Royaume-Uni ou d'énergie nucléaire en France. Dans la première partie de ce travail, nous avons établi que les systèmes énergétiques, par le biais de projets de coopération entre Nature et Technique, offraient un tableau pertinent des concurrences, et de plus en plus des coopérations entre Nature et Technique dans les discours et les pratiques étudiés, et ce en France. La deuxième partie de ce travail a consisté à démontrer dans quelle mesure les résistances à ces visions de la Nature et de la Technique en coopération sont plus fortes en France qu'au Royaume-Uni, car ces visions en coopération, comme nous l'avons montré en première partie, sont plus explicitement présentes en France qu'au Royaume-Uni. Dans la dernière partie de cette recherche, l'objectif a été enfin de démontrer dans quelle mesure ces représentations de la Nature et de la Technique en coopération traduisaient la rencontre d'idéologies technologiques propres au champ énergétique et de visions utopiques de l'environnement. Nous avons donc réussi à démontrer qu'au Royaume-Uni, cette vision utopique de l'environnement était davantage saisie comme une opportunité pour les acteurs du projet de centrale houlomotrice, tandis qu'en France, cette vision utopique de l'environnement menaçait l'idéologie technologique incarnée par l'énergie nucléaire. / This thesis is dealing with the reality of an environmental utopia of cooperation between Nature and Technique in the energy sector, in the renewables in the United-Kingdom and in the nuclear energy in France. In a first part, we have established that energy systems, through cooperation projects between Nature and Technique, offered an interesting map of the competition, and more and more of the cooperation, between Nature and Technique in the studied discourses and practices, and especially in France. The second part of this work was about to show to what extent any resistances to these visions of Nature and Technique were stronger in France rather than in the United-Kingdom, because the se visions, as we have seeing in the first part, were more explicit in France. In the last part of this research, the aim was to demonstrate to what extent these representations of Nature and Technique cooperating meant the meeting of technological ideologies, belonging to the energy field, and of utopian visions of environment. We managed to show that, in the United-Kingdom, this utopian vision of the environment was more understood as a chance for energy actors in a project of a wave power plant, instead of France, where these utopian visions of the environment were a threat for the technological ideology, embodied by the nuclear energy