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[en] The problematic of this thesis focuses on the impacts of the French capacity market on the deployment of renewable energies in the presence of uncertainty. This market is set up in France in order to cover high peaks in electricity consumption. It asks suppliers to ensure the consumption of their customers at these peaks by buying guarantees from electricity producers. This mechanism compensates for the available capacity during periods of tension between supply and demand, and its valuation depends on its contribution to security of supply. Due to their intermittent nature, the remuneration of renewable energies is more uncertain than for other means of electricity production. This thesis studies the adequacy between a goal of security of supply and a goal of deployment of renewable energies, two aims of the French government. (author)
[fr]La problematique de cette these porte sur les impacts du marche de capacite francais sur le deploiement des energies renouvelables en presence d'incertitude. Ce marche est mis en place en France dans le but de couvrir les fortes pointes de consommation electrique. Il demande aux fournisseurs d'assurer la consommation de leurs clients lors de ces pointes en achetant des garanties aupres des producteurs d'electricite. Ce mecanisme remunere alors la capacite disponible durant les periodes de tension entre l'offre et la demande, et sa valorisation depend de sa contribution a la securite d'approvisionnement. Or, du fait de leur nature intermittente, la remuneration des energies renouvelables est plus incertaine que pour les autres moyens de production electrique. Cette these etudie l'adequation entre un objectif de securite d'approvisionnement et un objectif de deploiement des energies renouvelables, deux visees du gouvernement francais. Ce document s'articule en quatre chapitres. Un premier chapitre dresse un etat des lieux du secteur electrique francais puis expose les differentes difficultes auxquelles il fait face ainsi que les solutions proposees et decrit le fonctionnement du marche de capacite, solution mise en place en France. Le deuxieme chapitre repond a la question du choix d'investissement entre electricite renouvelable et non renouvelable d'un producteur unique suppose adversaire a l'ambiguite lorsqu'il fait face a l'alea meteorologique et ce dans le cadre du marche de capacite. Un troisieme chapitre etudie le cas d'un duopole de Cournot entre un producteur d'electricite renouvelable faisant face a un alea meteorologique et un producteur d'electricite d'origine nucleaire. En vue de favoriser le deploiement des installations produisant de l'electricite renouvelable, le marche de capacite valorise les capacites d'effacement au meme titre que celles de production. Le dernier chapitre traitre alors la question de la modification de la demande en electricite lorsque le consommateur souscrit a un contrat d'effacement. Il met en lumiere des implications pour le deploiement des energies renouvelables. (auteur)
[en] The present dissertation aimed at estimating the photovoltaic (PV) generation potential at the Pici Campus of the Federal University of Ceara (UFC). Data collected during the period of one year - September 2016 to August 2017 - were evaluated on a photovoltaic (PV) distributed generation (DG) connected to the distribution network of the Pici Campus/UFC and the irradiation in the vicinity of the PV DG. Representative day charts were plotted for each month in the sample period. The annual average irradiance (Igmês m), average electricity generation (Gmês m), average PV capacity factor (FCmed) and PV efficiency (eFV) for the study region were of 5.21 kWh/m²/day, 7.55 kWh/day (0.7754kWh/m²/day), 20.98% and 14.94%, respectively. The equivalence in the reduction of CO2 provided by the PV DG (ECO2) in the LEA in the period studied was 255.64 kgCO2/year. The analysis of the PV potential of the Pici Campus was done with a focus on the ceilings of the buildings of the Technology Center (CT-UFC), Science Center (CC-UFC), Agricultural Science Center (CCA-UFC), Institute of Culture and Art/University Restaurant (ICA-UFC/RU-UFC) and University Library (BU-UFC), which are separated into five sets of areas that have a PV generation potential of 2.67 GWh/year, 4.80 GWh/year, 1.97 GWh/year, 2.25 GWh/year and 0.55 GWh/year respectively, totaling a PV potential of 12.25 GWh/year, with a total installed capacity of 6.67 MWp. For case 1, cost of PV DG in the Pici Campus based on the Investment of the Federal Institute of Ceara (IFCE), the investment for the implementation of the PV DG system (CFV) is R $ 29,262,587.57. For Case 2, cost of PV DG in the Pici Campus based on the Investment in the solar park of Nova Olinda, Piaui the required investment is R $ 20,400,732.78. The amount of the invoice for the Campus do Pici in this period was R $ 8,330,313.61. The consumption of electric energy was 14.33 GWh, with 1.19 GWh consumed in peak time (HP) and 13.14 GWh consumed in the off-peak time HFP. The average Gmês m of the Pici Campus is able to offset R $ 5,047,425.79 (93.29%) of the value of energy consumption in the HFP. The return period of the PV DG PRIFV) investment installed in the Pici Campus is from four to six years. (author)
[en] The main barriers for the deployment of renewable energy sources (RES) facilities in the Russian Federation are the lack of political, legislative and regulatory support, low prices for electricity and heat generated from fossil fuels, lack of information for decision makers (e.g. data from research projects) as well as the preference for centralized energy supply schemes. These barriers are contributing to an inadequate investment climate for the implementation of RES facilities. Nevertheless, in some regions of the Russian federation with a potential of RES and a comparatively low degree of economic centralization the situation is different. In the present thesis, the initial conditions for the development of RES potentials for the production of wind, solar and biomass energy in the Krasnodar region (southwestern region of the Russian Federation) are examined using a multi-criteria assessment methodology. For the assessment of the RES potentials at regional scale, the prosed multi-criteria methodology based on the geographic information systems (GIS) and has been complemented by the evaluation and analysis of primary and secondary data as well as economic calculations relevant related to economic feasibility of RES projects. The Krasnodar region has been chosen as model region for other regions in the Russian Federation, Eastern Europe and the former Soviet Union that have unexplored RES potentials but lack sufficient data for the assessment of RES potentials in GIS. An innovative element of the proposed multi-criteria methodology is the combined assessment of the maximum available factors relevant for the economically feasible exploration of RES potentials. These factors included the energy status with the specific features of the energy infrastructure, the energy policy relevant for RES along with the market and economic conditions of the region. The main objectives of the assessment of the RES potentials in the Krasnodar region were (1) to examine and present the energy status and the market conditions in GIS map as the essential conditions for an implementation of GIS facilities; (2) to calculate and present the available yield of wind, solar and biomass energy output through consideration of environmental and land-use restrictions reducing the theoretical resource potential, to the technologically and eventually the economically exploitable share of the initial resource potential; (3) to model energy scenarios and develop specific recommendations for and improved planning of future projects on RES in the study region. The assessment of the theoretical and technological wind energy potential utilized GIS models on extrapolation of wind speed, on suitability class (optimal locations for installation of RES facilities), on wind power density and wind energy estimation. For the assessment of the theoretic and technological solar energy potential, the kriging model, the suitability class model as well as the solar energy estimation model were applied in GIS. The assessment of the biomass energy potential utilized net primary productivity (NPP) and statistic data on organic wastes organic and animal manure using the GIS generic model. Optimal locations for the installation of biomass power plants were identified using network analysis tools in QGIS. The assessment of the technical wind energy potential in the Krasnodar region yielded an electricity production of 23 GWh year-1. Taking into account all the environmental and infrastructural restrictions as well as the current market conditions, the technical energy potential was subjected to reduction to an economically viable share of 0.8 GWh year-1. The total technical solar energy potential amounts to 24 GWh year-1. However, the economically viable share of the solar electricity is 4.5 GWh year-1 due to economic restrictions. The assessment of the biomass energy potential yielded an electricity production from biomass residues of 25 GWh year-1, which, however, was subjected to reduction to 4.7 GWh year-1 due to specific restrictions. The calculated unit (kWh) generation prices for hypothetical energy production facilities in both rural and urban areas of the Krasnodar region were Euros 0.15 (urban-utility scale) and Euros 0.20 (rural-utility scale) for wind electricity, Euros 0.16 (urban PV installations of up to 2 MW) and Euros 0.25 (rural PV installations of up to 1 kW) for solar electricity, and Euros 0.12 (rural-utility scale) and Euros 0.14 (urban-utility scale) for biomass electricity. Compared to the current mean unit generation prices for electricity from conventional energy sources of Euros 0.06 per kWh, the RES electricity prices are not competitive under the current regional and governmental energy policy. The recommendations provided in this thesis aim to highlight relevant support and measures to enable further development of RES potentials in the Krasnodar region. Thus, due to the application of an integrative multifactorial GIS-analysis it was possible to comprehensively estimate the RES potentials in the present work. Detailed and step-by-step analysis of constraints, the energy situation, and the market climate made an indepth feasibility assessment of potential RES projects in the study region. Thus, it was possible to answer the question why, despite the great potential of RES, there are no successful projects in the study region. As a result, reliable information about the RES potential in the region was provided, minimizing risks for investors and policy makers. For other regions, the proposed multi-criteria methodology provides a multi-purpose approach for a complex exploration of RES potentials and their exploitation under specific environmental and economic conditions.
[en] The rapid expansion of renewable energies – above all wind power and photovoltaic – leads to higher quantities of fluctuating electricity in power supply systems. Germany, in particular, has a high share of fluctuating electricity generation. This is causing integration difficulties and is reflected through occasional negative electricity prices. The German government considers energy storage as a solution to this issue and subsidises the development of storage capacity in electric grids with significant funds. In this work, a model-based quantification of energy- and environmental-economic effects provides insights about implications of storage capacity development in the German power supply system. Evidence is given that the intended advantages of a better integration of renewable energy sources are overcompensated by negative effects of an altered conventional power generation structure. Over the next decades, higher storage capacity would lead to higher CO2 and air pollutant emissions of the German power supply system – in contrast to originally stated subsidy objectives governmental funding principles.
[de]Auf dem Hintergrund der Energiewende führt der rasante Ausbau erneuerbarer Energien – allen voran Windkraftanlagen und Photovoltaiksysteme – zu höheren Strommengen aus fluktuierenden Energiequellen in Stromversorgungssystemen. Insbesondere in Deutschland führt deren hoher Anteil zu Integrationsschwierigkeiten, die sich u.a. in zeitweise negativen Strompreisen ausdrücken. Die Bundesregierung sieht in Energiespeichern eine Lösung des Problems und subventioniert den Ausbau von Stromspeicherkapazitäten mit bedeutenden Mitteln. In dieser Arbeit werden mittels einer modellgestützten Quantifizierung der energiewirtschaftlichen und umweltbezogenen Auswirkungen die Implikationen eines Ausbaus von Energiespeicherkapazitäten im deutsche Stromversorgungssystem untersucht. Dabei wird durch den Autor nachgewiesen, dass die beabsichtigten Vorteile einer Integration erneuerbarer Energien durch negative Auswirkungen infolge einer Veränderung der Erzeugungsstruktur konventioneller Kraftwerke mehr als aufgewogen werden. Ein weiterer Ausbau von Stromspeichern bewirkt auf absehbare Zeit eine Erhöhung der CO2- und Luftschadstoffemissionen des deutschen Stromversorgungssystems, was im Gegensatz zu erklärten Förderzielen steht und Fördergrundsätzen widerspricht.
[en] Due to the variability and intermittency of renewable energy such as solar technology, its large-scale integration into the micro-grid of energy production remains complicated because the large-scale photovoltaic power plants directly connected to the electricity grid may create instabilities. In addition, this variability of the solar resource does not allow the use of photovoltaics for the stand-alone system. Dealing with these issues, one of the solutions for a deployment of renewables such as photovoltaic is the set-up of energy storage inside the grid. However, the most common technique is based on the use of lithium-ion batteries, which remains not environmentally friendly during the recycling or during the destruction after their use. So, the Compressed Air Energy Storage system (CAES) appears as a solution to this disadvantage. In fact, my thesis aims to study the feasibility of this kind of energy storage technology using a small and medium photovoltaic power plant, and its instant operation to supply electricity to the buildings and the unconnected areas. In this thesis, we present the modeling, simulation, and optimization of a ten-kilowatt compressed air storage system designed to supply instantly a building with real loads. The model performed reflects the dynamic operation of the overall system consisting of the building, the photovoltaic field, the electrical grid, and the compressed air storage module. The optimization carried out allows the sizing of a compressed air storage system with a better efficiency (about 55%). The integration of a heat recovery unit equipped with electrical resistance and the adding of a variable speed compression module allow the building to reach the energy autonomy as a battery system for a standalone site. (author)
[fr]En raison de la variabilite et de l'intermittence de l'energie solaire photovoltaique, son integration a grande echelle dans le mix energetique des micro-reseaux integrant differents moyens de production demeure compliquee. En plus, cette variabilite de la ressource solaire ne permet pas l'utilisation du photovoltaique seul pour des systemes energetiques autonomes. Une des solutions pour surmonter ces handicaps est le stockage d'energie qui est generalement base sur l'utilisation de batteries lithium-ion. Cependant, leur cout eleve et leur impact negatif sur l'environnement lors de l'extraction de leurs matieres premieres et lors de leur destruction ou de leur recyclage en fin de vie forcent a rechercher d'autres moyens de stockage. Dans cette these, nous avons modelise et simule un systeme de stockage d'energie base sur l'air comprime (Compressed Air Energy Storage: CAES) qui semble etre une bonne alternative au systeme a batterie compte tenu des desavantages cites plus haut. Cette technologie a air comprime consiste a augmenter la pression de l'air dans une enceinte par le biais d'un compresseur alimente par une source electrique. a ce jour, les systemes de stockage a air comprime existant sont bases sur des configurations a grande puissance avec des reservoirs souterrains tels que d'anciennes mines de sel ou de charbon, dont le stockage se fait sur une longue duree. Dans cette etude, nous presentons la modelisation, la simulation et l'optimisation d'un systeme de stockage a air comprime d'une dizaine de kilowatts destine a alimenter un batiment universitaire a energie positive de facon instantanee a l'oppose des systemes existants. Le modele concu reflete le fonctionnement en regime dynamique du systeme global compose du batiment, du champ photovoltaique, du reseau electrique et du module de stockage a air comprime. L'optimisation effectuee permet le dimensionnement d'un systeme de stockage a air comprime pour un meilleur rendement (environ 55 %). L'integration d'un recuperateur de chaleur muni de resistance electrique et l'introduction d'un module de compression a vitesse variable permettent au batiment alimente de tendre vers l'autonomie energetique a l'image d'un systeme a batterie pour un site isole. (auteur)
[en] Although the applications of nuclear technology benefit several fields, such as health, industry, agriculture, energy production, among others, its public acceptance is still reduced and there are various barriers to its use. A lack of assertive knowledge about this technology generates prejudice against its use. Prejudices may be explicit – at the conscious level – or implicit – operating outside awareness. Nevertheless, either conscious or unconscious, prejudices interfere with behavior and attitudes. The experiences in the explicit and implicit memories can be transferred from one to the other; thus unconscious prejudices or associations may be modified by the explicit memory, that is, new knowledge may reduce or even reverse them. The teachers play a critical role for transforming education; however, for sharing balanced knowledge they must have a perspective without prejudices. This work aims to develop a neuroscience-based methodology through which implicit associations of Brazilian science teachers towards nuclear technology may be assessed and possible implicit prejudices may be changed by new knowledge. In order to identify implicit prejudices, specific implicit memory tests are required. The Implicit Association Test (IAT) was chosen for this work. By following the steps provided by the software FreeIAT, the IAT was customized aiming to compare the implicit associations of respondents towards nuclear and oil. A pretest with nuclear specialists (control group) and lay people was administered to check the consistency of the customized IAT. The Cronbach´s alpha was applied to measure the reliability of the test and showed good internal consistency. A 5-hour multisensory program for science teachers was designed and administered at the Instituto de Pesquisas Energéticas e Nucleares (IPEN). The IAT was administered at the beginning and at the end of the program and the results of the implicit associations were compared. After a six-month period, the IAT was re-administered to the same group of teachers to verify whether the implicit associations remained stable. This multisensory program was compared to a 12-week traditional teaching program with lecture classes held at IPEN for incoming post-graduation students. The multisensory program was effective for changing and maintaining the implicit associations of teachers towards the beneficial applications of nuclear technology, unlike the traditional teaching program with lecture classes. This work demonstrated that it is possible to break paradigms and prejudices. The multisensory program enabled an enriched knowledge about the applications of nuclear technology, that is, it promoted new experiences in the explicit memory, which modified the previous associations stored in the implicit memory. Therefore, the multisensory program has proven to be a successful, cost-effective tool, which is able to cause and maintain changes in implicit associations and can be applied in several areas where changes in implicit associations and prejudice reversal are desired. The results demonstrated that the proposed doctoral research was effective, thus contributing to the diffusion of knowledge of the beneficial applications of nuclear technology and, consequently, to its demythification. This methodology may be administered to other fields to identify, modify and/or reduce implicit prejudices or stereotypes. (author)
[en] The dissertation ''Essay on the Efficient Integration of Renewable Energies into Electricity Markets'' consists of five research articles which shed light on the efficient integration of renewable energies into electricity markets. A major share of renewable energies has characteristics which differ from classical conventional generation technologies. The uncertain weather-dependent characteristics in combination with almost-zero marginal generation costs raise new challenges to some parts of the electricity system. On the other side, the promotion of renewable energies seems promising to achieve the Energy Transition targets and reduce Germany's CO2-emissions. This becomes relevant in the light of the 2015 UN Climate Change Conference which negotiated the Paris Agreement to tackle climate change, e.g. by the restriction of global warming to a maximum of 2 C, and translate to CO2-reduction efforts, especially for the carbon-dioxide intense electricity sectors. The five research papers focusing on different aspects and potential inefficiencies of the renewable energy market integration. The focus can roughly be separated into temporal and regional efficiency examinations. The temporal efficiency is subject to paper 1, paper 2 and paper 3. The regional efficiency is subject to paper 5 which is based on the preliminary findings and the generated dataset in paper 4.
[en] The aim of the work is to establish the thermodynamic, kinetic and anodic properties of the AF 2.18 alloy with lithium, magnesium, beryllium and their use in developing the composition of new alloy compositions for the needs of technology. The mathematical models of the temperature dependences of heat capacity, heat transfer coefficient, and thermodynamic functions (enthalpy, entropy, Gibbs energy) of AF 2.18 alloy with lithium, beryllium, magnesium were obtained; kinetic and energy parameters of oxidation process of AF 2.18 alloy with lithium, beryllium, magnesium are determined. The main regularities of change of heat capacity and change of thermodynamic functions (enthalpy, entropy, Gibbs energy) of AF 2.18 alloy with lithium, beryllium, magnesium depending on temperature and quantity of alloying component are determined as well. (author)
[en] The international climate targets can only be achieved by generating more electricity using renewable energy sources. At the same time, flexible electricity consumers are needed to balance the fluctuating generation from renewables. As not all the electricity produced can be used directly, additional energy carriers are required as storage medium. Hydrogen that is produced by the flexible and controllable electrolysis of electricity and water is a versatile energy carrier, e.g. for the chemical industry or fuel cell electric vehicles. So far, this is not yet profitable, because the hydrogen production costs using electrolysis exceed those of competing methods. This could change under altered framework conditions and given the ongoing advances in electrolysis technology, which begs the question: Could hydrogen production using electrolysis be profitable in a future German energy system with high shares of renewable energies? To answer this question, electricity markets and the current market situation for flexible technologies are examined and developments in the field of hydrogen production and demand are presented. A fundamental simulation model is constructed to determine the future development of electricity market prices in different scenarios. The focus lies on two markets of relevance for operating electrolysers: the spot market for short-term electricity trading and the market for balancing power that allows the marketing of flexible loads. The prices on the market for balancing power are calculated using an approach based on opportunity costs. The simulated prices serve as input to an optimization model that maximizes the contribution margin of an electrolyser taking technical constraints into account. Different concepts are considered that include the direct sale of hydrogen, its reconversion into electricity as well as the provision of balancing power. The concepts are evaluated using the revenues and costs and the results used to answer the research question. Three scenarios selected from the literature depict different development pathways of the energy system as well as different values for the electrolyser’s techno-economic parameters up to the year 2050. The scenarios differ with regard to the deployment of renewable energy sources and the prices for energy carriers among other criteria. It becomes clear that profitable operation of electrolysers will, if at all, only be possible in the long term, probably from 2030 onwards. To achieve this, the electrolyser’s specific investment has to decrease and its efficiency has to increase or the framework conditions in the energy system must allow high full load hours of the electrolyser at low electricity costs. Operation is considered profitable if hydrogen can be produced via electrolysis at lower costs than conventional production methods. This is achieved in particular if the electrolyser is used to provide balancing power. Reconverting hydrogen into electricity is not profitable in most cases. However, electrolysis may become essential at an earlier point in time to meet climate targets. In this case, specific incentives are needed for its use.
[en] Accurate knowledge and understanding of heat transfer characteristics near and above critical conditions is crucial to the successful design of the SCWR. Many studies, both numerical and experimental assessments have been conducted on bare tubes and simple geometries like annuli. However, heat transfer performance studies of the fuel assemblies for SCWR are scarce. Thus, there is still a lack of understanding of heat transfer performance in the fuel assembly designs for SCWR. Moreover, the importance of this study cannot be over-emphasized as it will broaden and better the understanding of the concept of heat transfer in the rod bundle geometry by providing more numerical data.In this study a 3D CFD code STAR CCM+ was used in assessing the performance of heat transfer in the square fuel assembly of a High Performance Light Water Reactor (HPLWR). Utilizing the computational environment and the flexibility of STAR CCM+ code, test analysis was conducted using the four turbulence models, namely AKN low-Re, Standard Lien’s low-Re, Standard Wilcox κ-ω and SST κ-ω to choose a suitable turbulence model yielding satisfying prediction (capabilities) in describing the heat transfer and flow of supercritical water in the fuel assembly “near”, at and after the pseudo-critical region. The analysis was carried out at 25 MPa system operating pressure, mass flow rate of 0.167 (601.2 kg/h), 300 °C inlet temperature with uniform heat flux of 650 kW/m2. Turbulence sensitivity analysis was performed and SST κ-ω model was selected based on its simplicity and superiority to others especially with regard to numerical stability. Moreover, SST κ-ωmodel also does not involve damping functions, but allows simple Dirichlet specified boundary conditions. Furthermore, using the SST κ-ω with low y+ wall treatment the selected heat transfer correlations were assessed. Overall, the Cheng et al. correlation provided the most satisfying prediction for the wall temperatures in all the sub-channels and captured closely Wataa’s Numerical data. This was followed by the McAdams correlation, but the Dyadyakin and Popov and the Petukhov correlations also yielded acceptable results. Test analysis results of the heat transfer correlation also confirmed the occurrence of heat transfer enhancement and heat transfer deterioration at the pseudo-critical point and after or beyond respectively. The maximum wall temperature was obtained in sub-channel 9, the hottest sub-channel and exceeded the design limit of 620 °C by 60 °C for the Cheng correlation while for the other correlations it was more. The difference in temperature between the hottest and coldest sub-channels was approximately 80 °C. Finally, parametric analysis was conducted in sub-channels 4 and 9 by varying mass flow rates 0.1670 kg/s (601.2 kg/h) and 0.1559 kg/s (561.2 kg/h), pressure 23 MPa and 25 MPa and with or without gravity. Results from this test analysis showed that mass flow rate, pressure and gravity have significant influence. It was observed that at low mass flow rate with varying pressure (23 MPa and 25 MPa), the temperatures significantly increased in the heat transfer deterioration region. Nevertheless, experimental investigations involving rod bundles adopted in this study should be conducted to validate the results obtained numerically and address the inconsistence of the conclusions drawn, “when compared with similar studies”. These experimental studies would also be helpful in validating similar numerical studies in future. (author)