[pt] O trabalho tem como objetivo a conversão de um grupo gerador, originalmente Diesel, para operar no modo Diesel-Gás, onde estes dois combustíveis são administrados simultaneamente no motor. Para tal foi utilizado um grupo gerador de 120KW, com um motor Perkins 1006 TAG (turbo alimentado com intercooler). Medidas experimentais foram realizadas tanto no modo Diesel quanto no bicombustível Diesel-gás. Foram avaliados: desempenho e, principalmente, emissões de poluentes atmosféricos. A redução das emissões foi realizada mediante a restrição parcial do ar de combustão, regulada por uma válvula tipo borboleta, que funciona eletronicamente, posicionada na entrada do coletor de admissão. A relação Diesel-Gás foi também avaliada, onde o segundo combustível era administrado através de um sistema eletrônico de injeção de gás natural. Os resultados indicam que em cargas baixas as reduções de monóxido de carbono e hidrocarbonatos são significativas (50% de redução de HC e 20% de CO) com máximas taxas de substituição. O mesmo se observa em cargas intermediárias. Em cargas médias e baixas observa-se um leve aumento nas emissões de óxido nitroso. Pode-se observar uma melhora no rendimento global do grupo gerador com o aumento da carga e da taxa de substituição. De forma geral, conseguiu-se reduzir os níveis de emissões em altas cargas, principalmente de hidrocarbonetos e monóxido de carbono. / [en] The objective of this study is converting a generator, originally Diesel, to operate in a Diesel-Gas; two fuels are administered simultaneously to the motor. One diesel generator of 120KW model Perkins 1006 TAG (powered with turbo intercooler), running on the Diesel / natural gas dual fuel mode, was tested. Experimental measurements were performed in both the Diesel and dual fuel diesel-gas. Are evaluated performances and; especially air pollutant emissions. The emission reduction was carried out by partial restriction of the combustion air with the help of an electronic throttle valve, positioned before the intake manifold. The ratio Diesel-Gas was evaluated, where the second fuel (natural gas) was administered with one electronic injection of natural gas. The results indicate that at low loads the reductions in carbon monoxide and hydrocarbons are significant (50% reduction in HC and 20% CO) with maximum replacement rates. Something like is observed at intermediate loads. In medium and low loads there is a slight increase in emissions of nitrous oxides. One can observe a slight increase in overall yield of the generator with the increased workload and the replacement rate; in general it was possible to reduce emissions at high loads, especially in hydrocarbons and carbon monoxide.

Abstract The combustion of fuels in motor vehicles is one of the most significant causes of air emissions. The use of oxidation catalysts in exhaust gas emission treatment can reduce hydrocarbons (HCs) and carbon monoxide (CO) emissions by more than 90%. Fuels and engine lubricants contain impurities like sulphur (S) and phosphorus (P), which can have a significant effect on the activity and durability of oxidation catalysts. This thesis aims at increasing the current knowledge of the deactivation phenomena caused by sulphur and phosphorus in diesel and natural/bio gas oxidation catalysts. Accelerated laboratory scale sulphur, phosphorus and thermal treatments in gas-phase conditions were carried out for alumina (Al2O3) based platinum (Pt) and platinum-palladium (PtPd) metallic monolith diesel and natural gas oxidation catalysts. In addition, a vehicle-aged natural gas oxidation catalyst and an engine-bench-aged diesel oxidation catalyst were studied and used as a reference for the laboratory-scale-aged catalysts. BET-BJH, FESEM, TEM, XPS and DRIFT were used as characterization techniques to determine changes on the catalysts. The effect of accelerated deactivation treatments on the catalyst activity was determined using laboratory scale measurements in CO, HC and nitric oxide (NO) oxidation. Sulphur and phosphorus were found to cause morphological and chemical changes on the studied catalysts. Sulphur was found to be adsorbed vertically throughout the entire catalyst support from the catalyst surface to the metallic monolith, while phosphorus accumulated on the surface region of the precious metal containing catalysts. Both, sulphur and phosphorus, slightly increased the average size of the precious metal particles size and are adsorbed onto the alumina by chemical bonds. In addition, a partial transformation from PdO to Pd and a change in the shape of the precious metal particles due to phosphorus were detected. Due to the detected structural and chemical changes on the catalysts, sulphur and phosphorus treatments reduced the catalytic activity of the studied diesel and natural-gas-oxidation catalysts. Correspondence between real and simulated ageing was found and thus the used accelerated laboratory scale aging method can be stated to be a good tool to simulate sulphur and phosphorus exposure. / Tiivistelmä Moottoriajoneuvot ovat merkittäviä ilmapäästöjen aiheuttajia. Hapetuskatalyyttejä käyttämällä hiilimonoksidi- ja hiilivetypäästöistä pystytään poistamaan yli 90 %. Polttoaineet ja voiteluaineet sisältävät epäpuhtauksia kuten rikkiä ja fosforia, jotka voivat merkittävästi heikentää hapetuskatalyyttien aktiivisuutta ja kestävyyttä. Väitöskirjan tavoitteena on tuottaa uutta tietoa rikin ja fosforin aiheuttamasta diesel- ja maakaasukatalyyttien deaktivoitumisesta. Metalliseen monoliittiin tuettuja alumiinioksidipohjaisia platina- ja palladiumkatalyytteja ikäytetiin tekemällä niille rikki-, fosfori- ja lämpökäsittelyjä. Maantieikäytettyä maakaasuhapetuskatalyyttiä ja moottoripenkki-ikäytettyä dieselhapetuskatalyyttiä käytettiin laboratorioikäytettyjen katalyyttien referensseinä. Ikäytyskäsittelyjen aiheuttamat muutokset analysoitiin BET-BJH-, FESEM-, TEM-, XPS- ja DRIFT-menetelmillä. Käsittelyjen vaikutus katalyyttien hiilimonoksidin, hiilivetyjen ja typenoksidien hapetusaktiivisuuteen tutkittiin laboratoriomittakaavan aktiivisuuslaitteella. Rikki ja fosfori aiheuttivat rakenteellisia ja kemiallisia muutoksia tutkittuihin katalyytteihin. Rikki adsorboitui koko tukiaineeseen (tukiaineen pinnalta pohjalle), kun taas fosfori adsorboitui vain pinnan alueelle. Sekä rikki että fosfori kasvattivat jalometallipartikkeleiden kokoa sekä muodostivat alumiinioksidin kanssa yhdisteitä. Lisäksi fosforikäsittelyjen havaittiin osittain pelkistävän PdO:n Pd:ksi ja muuttavan jalometallipartikkelien muotoa. Havaitut rikin ja fosforin aiheuttamat rakenteelliset sekä kemialliset muutokset laskivat diesel- ja maakaasukatalyyttien hapetusaktiivisuutta. Laboratorioikäytyksillä havaittiin olevan hyvä korrelaatio todellisissa olosuhteissa tehtyjen ikäytysten kanssa ja tästä syystä työssä käytetyn laboratoriomittakaavan ikäytysmenetelmän voidaan todeta olevan hyvä työkalu simuloimaan rikin ja fosforin aiheuttamaa deaktivoitumista.

The thesis focuses on the influence of new natural gas sources on energy security in the USA. The new sources include mainly shale gas, but also tight gas and others. The main objective of the thesis is to evaluate the impact of changes in production and trade in gas on energy security and self-sufficiency of the USA. The thesis is divided into five chapters. The first chapter is theoretic and thus provides the frameworks for the following parts of the thesis. It focuses on the security concept in literature and in the papers of international energy agencies, e.g. IEA. For the purposes of the thesis, energy security is defined as the ability of a state to secure uninterrupted and stable supply of energy at a reasonable price of sufficiently diversified energy sources, which can be flexibly substituted among each other without additional costs by the end consumers. The second chapter concentrates on energy security in the USA, the development of energy legislation and the position of the United States in international comparison from this point of view. The third chapter deals with the technical background of production and its legislative status of the USA. To compare, it also addresses the production legislation in some EU countries. It follows up market implications of increased domestic production, specifically its profitability, changes in energy mix and in trading position of the USA in energy sources. The fourth chapter analyzes price impacts using change in domestic and foreign demand and supply in natural gas, including their price elasticity, and the price development itself. The fifth chapter summarizes, based on the findings from previous chapters, perspectives of the future development, mainly impacts on economy and potential export. The thesis comes to the main conclusion stating that the production from domestic sources shall have a positive impact on energy security not only in the USA, but also consecutively in other countries dependent on import of energy sources through higher diversification of source countries. Better available commodity may contribute to greater price competitiveness of domestic products on international markets and help to substitute coal with gas in energy mix. The biggest risk is seen in the low gas price that makes the production economically unprofitable. However, the gas price should maintain the level which would allow for profit of the producers, reasonable price for the consumers and increased level of energy security thanks to further development of the production technology, its better price availability and increased demand on cleaner energy sources.

Main purpose of this thesis is to find out how self sufficient concerning the energy raw materials are countries within Visegrad group. Further purpose of my thesis is to analyse total primary energy supply, the structure of energy supply in countries of Visegrad group and its developments in last 4 decades. Furher I want to reveal how the structure of total primary energy supply and structure of electricity generation reflect the disponibility of raw materials in these countries and transformation of economics in the nineties. A sub-objective of my work will examine how countries of the Visegrad Four use the potential of renewable energy sources and how they support it.

This thesis evaluates the possibilities of application of LNG (liquefied natural gas) in the Czech Republic. LNG is a relatively new commodity, which has broad use in the world, but as of now, the Czech Republic hasn't entered its market. The main objective of this thesis is to determine whether there exists suitable use for LNG in the Czech Republic today. By analysis and calculation I came to the conclusion, that there are applications that would be economically advantageous and would, in addition, bring other significant benefits, such as reducing emissions. The most perspective is the use of LNG as an alternative truck fuel. Under certain conditions suitable applications are also LNG satellite stations, cogeneration or bus transport. The conclusion of this thesis is that liquefied natural gas has a great potential to expand to the Czech Republic.

The thesis deals with the current trends and development of the unconventional oil and natural gas production. The main aim is to evaluate and analyze the global development of unconventional production and the influence of its growth in the last decade on the global economy and the given markets. In addition, not only the pros, but also the risks and limitations of unconventional production, are examined, e.g. economic and environmental issues. The final part focuses on the United States and the local shale boom. Based on the analysis of American unconventional production, the future of these sources is predicted. At the end of the thesis the effects of shale boom on the U.S. economy are explored as well, focusing mainly on the U.S. trade balance.

The diploma thesis deals with the energy security of China, mainly with the question considering energy mix, consumption, infrastructure network and diversification of importers in natural gas field. The analysis of research question is done mainly from the data of international energy organizations, from the Chinese government data and other sources, which enable to describe mentioned problems. From the People's Republic of China perspective, it focuses on the detailed description of gas pipeline infrastructure, importers and subjects, which are involved in energy sector. Risks and threats, which should occur from signed partnerships or projects, were taken into consideration too. The aim of this work is to define and evaluate the energy security of PRC, its energy policy mainly in natural gas field when considering present situation as well as possibilities for the future. Than the diploma thesis outlines the role of natural gas in Chinese energy mix, state of the gas sector in China and evaluation of projects, which take place in China's gas sector or will occur in the future.

Au regard de la croissance constante de la demande énergétique mondiale et de l'épuisement des ressources fossiles et des problèmes environnementaux, le recours à des sources d'énergie renouvelables est incontournable. La filière biomasse parait une voie prometteuse pour la production d’énergie propre et durable. La production du Gaz Naturel Synthétique (SNG) à partir de biomasse lignocellulosique est en plein essor. L’objectif de ce travail est la comparaison, par le biais d’indicateurs de développement durable, de systèmes de production de SNG à partir des résidus forestiers et des déchets des palmiers dattiers. L’Analyse de Cycle de Vie Emergétique a été choisie comme l’outil le plus judicieux pour cette étude. Elle permet de comparer les deux systèmes afin de déterminer lequel est le plus efficace et le plus durable, et de localiser leurs possibilités d’améliorations environnementales. Les résultats montrent que l'augmentation de la teneur en eau dans le gaz de synthèse peut éviter le dépôt de carbone au cours de la méthanation. Le rendement « Cold Gaz Efficiency » du procédé SNG est de 52%. Les résultats de l'évaluation environnementale montrent de fortes réductions des gaz à effet de serre pour chaque système. La transformité de SNG français est inférieure à celle du SNG tunisien. Par ailleurs, le système tunisien a la plus grande valeur du pourcentage de renouvelabilité et d'indice de durabilité. Le profil environnemental et la durabilité des deux systèmes étudiés peuvent être encore plus intéressants en installant l'unité de SNG à proximité d’oasis ou de forêts. Dans l'ensemble, le SNG devrait contribuer favorablement à l'avenir du mix d'énergie renouvelable / Actually biomass-based energy supply is a promising route for renewable energy system and sustainable development strategy. Methane rich gas from biomass can be obtained from gasification (Synthetic Natural Gas, SNG). SNG is very suitable, as it could be an important energy carrier. It could replace natural gas for electricity generation and heating systems and use the existing gas infrastructure. The main objective of this work is to investigate the syngas methanation, and to compare the environmental performance and sustainability for different SNG production systems. The French system (valorization of forest residue) and the Tunisian system (valorization of date palm waste) are analyzed and compared by using the Emergetic Life Cycle Assessment method. The inventory data are obtained mainly through process simulation by Aspen PlusTM software. The results show that increasing the steam ratio in syngas can avoid the carbon deposit during methanation process. The cold gas efficiency of the SNG process is 52%.The environmental analysis results show that high greenhouse gas savings can be obtained for each system. The transformity of the French SNG is lower than the one of the Tunisian SNG. On the other hand, the Tunisian system has the highest percentage of renewability and index of sustainability. The environmental performance and the sustainability of the two systems can be made even more attractive by installing the SNG production units near forests or oasis. Overall, the SNG is expected to contribute favorably to the future renewable energy system

The thesis analyses influence of actors in the regulatory mode of legislative process of the EU on a case study of liberalisation and integration of the Internal Market in electricity and natural gas. The Internal Market is regarded as an example of postmodern international system. Key arenas used for analysis of individual actors and their partial interests and goals (including ways of their pursuing) are national, regional and supranational.

A motivação para este trabalho originou-se da atual tendência do Gás Natural Liquefeito (GNL) se tornar uma importante opção para a diversificação da matriz energética brasileira. Atualmente, os terminais de gás natural liquefeito (GNL) são na maioria estruturas onshore, a construção destes terminais é custosa e muitos investimentos são necessários para atender as legislações ambientais e de segurança. Além disso, um acidente em uma destas instalações poderá produzir um grande impacto em áreas adjacentes. Sob esta perspectiva, surge uma nova proposta: uma unidade flutuante de armazenagem e regaseificação de gás natural liquefeito (FSRU - Floating Storage and Regasification Unit), o qual é uma unidade offshore e que pode trabalhar a quilômetros de distância da costa. O objetivo desta pesquisa é desenvolver uma metodologia de análise de Confiabilidade com o uso de Redes Bayesianas (RB) e aplicá-la na análise do sistema de Regaseificação do FSRU. O uso de RB, entre outras vantagens, permite a representação de incertezas no modelo e de dependências condicionais o que não é possível com as técnicas tradicionais, como por exemplo, as árvores de falhas e de eventos. Como resultado do trabalho, além da apresentação da metodologia a ser desenvolvida, serão identificados os pontos críticos do sistema contribuindo para o desenvolvimento de um plano de manutenção que assegure uma boa operabilidade do sistema com níveis razoáveis de dependabilidade. / The motivation for this research is the propensity of the Liquefied Natural Gas (LNG) becomes an important source of energy. Nowadays, LNG Import Terminals are mostly onshore; the construction of these terminals is costly and many adaptations are necessary to abide by environmental and safety laws. Moreover, an accident in one of these plants might produce considerable impact in neighboring areas. Under this perspective, a new option arises: a vessel known as FSRU (Floating Storage and Regasification Unit), which is an offshore unit, that can work miles away from de coast. The goal is to develop a Bayesian Network Reliability Modeling, which will show a preview of FSRUs Regasification System behavior. Using BN is possible to represent uncertain knowledge and local conditional dependencies. The results intend to clarify the critical equipment of the system and might improve the development of an effective maintenance plan, which can provide good operability with reasonable dependability levels.