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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Exploration of compressed natural gas as an automotive fuel in Nigeria

Ogunlowo, Olufemi O. January 2016 (has links)
Flaring of associated gas, found during petroleum exploration and production in Nigeria, results in substantial environmental degradation, which endangers sustainable development and exposes the population to health hazards. In addition, it results in significant economic losses, especially from the opportunity cost of the disposed natural gas (NG). As part of the many initiatives to abate flaring and harness NG resources, the Nigerian government proposed the use of compressed natural gas (CNG) as an automotive fuel in 1997, but progress has been slow. This study investigates the barriers to use of CNG as an automotive fuel in Nigeria and how these can be overcome. It identified, validated, prioritized and built consensus on 29 barriers and 25 policy recommendations, using a combination of case study of selected countries, semi-structured interviews and a Delphi survey among participants who are key stakeholders in the energy and transportation sectors. Major hindrances identified include the absence of market coordination; lack of transparency and accountability; inexperience of the population with gas usage; lack of public awareness on the benefits of NG; artificial distortion of the economic benefits of CNG due to the subsidy on gasoline; focus on export market development to the detriment of the domestic market; absence of regulatory standards; poor infrastructure; and an old and dilapidated national vehicle fleet. There was no convergence on the impact of insecurity of human and material resources caused by militancy and pipeline vandalism in the oil producing areas, despite widespread views of the negative effect on the oil and gas industry generally. Based on the consensus built among study participants, the study recommends 12 policy interventions, which might stimulate growth in the use of CNG as automotive fuel; these comprise specific energy market reforms, fiscal and operational incentives, transportation sector reforms and the creation/building of public awareness.
2

Petroleum geopolitics : a framework of analysis

Herbert-Burns, Rupert January 2012 (has links)
The playing field upon which actors, both state and non-state, develop strategies to secure existing supplies of oil and seek access to new ones is as systemically, politically and strategically complex is as it is geographically vast. In considering this activity, the terminology used by pundits and journalists to describe the significance of issues such as oil demand, the complexities of access to petroleum and concerns over security threats to supplies of oil is familiar. Juxtapositions such as the ‘geopolitics of oil', ‘energy geopolitics', the ‘geopolitics of resource wars' and the ‘geopolitics of oil and gas' are all familiar. But what do they mean when they use ‘geopolitics' in this context? Thus, by extension, can petroleum geopolitics - a hybrid conceptual construction used in this thesis - be disassembled into its component parts, analysed and systematically understood. This is the aim of this thesis. This thesis contends that the very nature of oil and gas reserves, the processes of exploration and production, and the means that govern and characterise the transportation of petroleum overland and by sea is inherently geopolitical - that some core features of geopolitical theory and key geopolitical concepts are pivotal in determining the ontology and process of the international oil business. Indeed, so central has oil been to the advancement of industrial capacity, technology, warfare, transportation and economic prosperity of states since the 20th century, it could be argued that petroleum is the single largest determinant of the geopolitics that characterises the modern international system. In order to address the interrelationship and correlations between core aspects of the petroleum industry and causal geopolitical phenomena, I begin by advancing a framework of analysis that systematically binds key geopolitical features and concepts – specifically: Spatial Phenomena; Environmental Ontology; Territorial Access; Geopolitical Features; State and Non-state Concepts; and, Strategic Resources and Geopolitics - with examples of empirical findings revealed in subsequent chapters in the thesis. Fundamentally, this process works to assess causality and correlations between geopolitical phenomena such as space and distance, sovereignty, territory, boundaries, chokepoints, resource nationalism, transnationalism, resource security and conflict, and the features and processes inherent in petroleum reserves and the exploration, production and transportation of oil and gas. The framework is followed with a sequential analysis of the three empirical foci of the project: the ontology of oil and natural gas reserves; the planning and processes of exploration and production; and, the processes of the conveyance petroleum. I have concentrated my research to activities within Eurasia, which comprises the traditional continents of Europe and Asia, and the Indo-Pacific maritime realm, which extends eastwards from the Red Sea to the western Pacific Rim. After systematically assessing the empirical findings and examining key areas of geopolitical theory, I conclude that there is an identifiable and logical correlation between geopolitical phenomena, petroleum reserves, and the means to produce and distribute oil and gas between source and market.
3

Optimisation multiobjectif de réseaux de transport de gaz naturel / Multiobjective optimization of natural gas transportation networks

Hernandez-Rodriguez, Guillermo 19 September 2011 (has links)
L'optimisation de l'exploitation d'un réseau de transport de gaz naturel (RTGN) est typiquement un problème d'optimisation multiobjectif, faisant intervenir notamment la minimisation de la consommation énergétique dans les stations de compression, la maximisation du rendement, etc. Cependant, très peu de travaux concernant l'optimisation multiobjectif des réseaux de gazoducs sont présentés dans la littérature. Ainsi, ce travail vise à fournir un cadre général de formulation et de résolution de problèmes d'optimisation multiobjectif liés aux RTGN. Dans la première partie de l'étude, le modèle du RTGN est présenté. Ensuite, diverses techniques d'optimisation multiobjectif appartenant aux deux grandes classes de méthodes par scalarisation, d'une part, et de procédures évolutionnaires, d'autre part, communément utilisées dans de nombreux domaines de l'ingénierie, sont détaillées. Sur la base d'une étude comparative menée sur deux exemples mathématiques et cinq problèmes de génie des procédés (incluant en particulier un RTGN), un algorithme génétique basé sur une variante de NSGA-II, qui surpasse les méthodes de scalarisation, de somme pondérée et d'ε-Contrainte, a été retenu pour résoudre un problème d'optimisation tricritère d'un RTGN. Tout d'abord un problème monocritère relatif à la minimisation de la consommation de fuel dans les stations de compression est résolu. Ensuite un problème bicritère, où la consommation de fuel doit être minimisée et la livraison de gaz aux points terminaux du réseau maximisée, est présenté ; l'ensemble des solutions non dominées est répresenté sur un front de Pareto. Enfin l'impact d'injection d'hydrogène dans le RTGN est analysé en introduisant un troisième critère : le pourcentage d'hydrogène injecté dans le réseau que l'on doit maximiser. Dans les deux cas multiobjectifs, des méthodes génériques d'aide à la décision multicritère sont mises en oeuvre pour déterminer les meilleures solutions parmi toutes celles déployées sur les fronts de Pareto. / The optimization of a natural gas transportation network (NGTN) is typically a multiobjective optimization problem, involving for instance energy consumption minimization at the compressor stations and gas delivery maximization. However, very few works concerning multiobjective optimization of gas pipelines networks are reported in the literature. Thereby, this work aims at providing a general framework of formulation and resolution of multiobjective optimization problems related to NGTN. In the first part of the study, the NGTN model is described. Then, various multiobjective optimization techniques belonging to two main classes, scalarization and evolutionary, commonly used for engineering purposes, are presented. From a comparative study performed on two mathematical examples and on five process engineering problems (including a NGTN), a variant of the multiobjective genetic algorithm NSGA-II outmatches the classical scalararization methods, Weighted-sum and ε-Constraint. So NSGA-II has been selected for performing the triobjective optimization of a NGTN. First, the monobjective problem related to the minimization of the fuel consumption in the compression stations is solved. Then a biojective problem, where the fuel consumption has to be minimized, and the gas mass flow delivery at end-points of the network maximized, is presented. The non dominated solutions are displayed in the form of a Pareto front. Finally, the study of the impact of hydrogen injection in the NGTN is carried out by introducing a third criterion, i.e., the percentage of injected hydrogen to be maximized. In the two multiobjective cases, generic Multiple Choice Decision Making tools are implemented to identify the best solution among the ones displayed of the Pareto fronts.
4

A preliminary concept for an LNG import terminal for Saldanha bay

O Connor, Padhraic 04 1900 (has links)
Thesis (MScEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: South Africa presently faces a serious and much-acknowledged energy capacity deficit. The Department of Energy are determined to address this capacity crisis by creating several new power plants between 2010 and 2030, as stipulated in the “Integrated Resource Plan 2010”. A Combined Cycle Gas Turbine (CCGT) power plant is proposed to add 2370 MW of capacity to the national grid. The “new-build” CCGT plant will use natural gas as a feedstock for energy generation. The plant is destined to begin energy generation by 2019, and will ramp up to full capacity by 2030. Following a review of the existing natural gas sources and the nascent gas network in South Africa, Liquefied Natural Gas (LNG) has been identified as the most suitable immediate source of natural gas feedstock for the CCGT. LNG fuel must be imported into South Africa aboard large, special purpose LNG Carrier (LNGC) vessels. LNGC vessels require a designated marine import terminal in order to offload the super-cooled and potentially flammable cargo. Saldanha Bay, located on the South West coast of South Africa, has been selected by Transnet as a preferred location for LNG terminal development. A review of LNG technology reveals the need for mandatory onshore LNG storage and regasification facilities, land area requirements, demands of different LNGC types and the characteristics of dedicated LNG jetties and terminals. Floating, offshore and traditional LNG terminals are discussed. The objective of this thesis is to review potential terminal sites and conceptual layouts in Saldanha Bay, and via a Multi Criteria Analysis, to present three distinct LNG terminal layout options for further consideration. The conceptual layouts will address technical concerns such as berth orientation and layout, safe navigational access to the terminal, mandatory onshore infrastructure and optimisation of berth operations. Saldanha Bay as a port location is studied and the importance of local environmental features is highlighted. Potential terminal development sites are identified following a review of nautical and terrestrial restrictions. Four conceptual site layouts are proposed, providing jetty locations and orientations in the Bay. The sites are located in North Bay, Hoedjiespunt, and two in Big Bay. Several Key Design Parameters (KDP’s) are identified as having a critical bearing on the ultimate layout, operation and feasibility of an LNG terminal in Saldanha Bay. The sensitivity and influence of the KDP’s at each of the four conceptual sites is investigated. Analysis of KDP effects leads to the development of design variation options at the sites. Twelve terminal layout schemes are ultimately derived. A Multi Criteria Analysis (MCA) is performed to rank the 12 terminal layout schemes in terms of technical efficacy. A sensitivity study is conducted to justify the selection of MCA parameter weights. The three top-scoring schemes are recommended for more detailed pre-feasibility investigation. The three terminal layout schemes, located in Big Bay and Hoedjiespunt, make use of both standard trestle jetties and floating LNG technologies. The thesis has shown that a number of viable sites and layouts for LNG terminals exist in Saldanha Bay and demonstrates a systematic analysis of design issues leading to preferred options. The thesis concludes by outlining the next steps in the process towards a final terminal scheme selection. / AFRIKAANSE OPSOMMING: Suid-Afrika ervaar huidig ‘n drastiese energie kapasiteit verlies. Die Departement van Energie is vasbeslote om die energie krisis aan te spreek deur verskeie nuwe kragstasies tussen 2010 en 2030 op te rig, soos beskryf in die “Integrated Resource Plan 2010”. ‘n Gekombineerde Siklus Gas Turbine (GSGT) kragstasie is voorgestel om ‘n verdere 2370 MW by te voeg tot die nasionale krag netwerk. Die “nuut-geboude” GSGT kragstasie sal natuurlike gas as brandstof vir kragopwekking gebruik. Die kragstasie is beplan om teen 2019 krag op te wek, en sal teen 2030 volle kapasiteit loop. Na ‘n ondersoek van die bestaande natuurlike gas bronne en gas netwerke in Suid Afrika, is Vloeibare Natuurlike Gas (VNG) geïdentifiseer as die huidiglike beskikbare bron van brandstof vir die GSGT. VNG moet ingevoer word aanboord spesiaal geboude VNG vaartuie. VNG vaartuie benodig ‘n spesifieke mariene invoer terminaal om die vlambare vloeistof mee af te laai. Saldanhabaai, aan die Suid-Westerlike kus van Suid Afrika, is as verkose area vir die VNG terminaal ontwikkeling geïdentifiseer deur Transnet. ‘n Oorsig van VNG tegnologie bevind dat VNG stoorplek en vergassings fasiliteite, land area, verskeie VNG vaartuie en karakteristieke van VNG terminale benodig word. Verskeie VNG terminale word bespreek in hierdie studie. The doel van hierdie tesis is om die potensiële terminaal bou-terrein en konseptuele ontwerpe in Saldanhabaai, deur middel van ‘n multi-kriteria analise (MKA), in drie verskillende ontwerp moontlikhede voor te stel. Saldanhabaai, as hawe, is bestudeer en belangrike omgewings aspekte is geïdentifiseer. Potensiële terminaal bou-terrein is geïdentifiseer na aanleiding van seevaart en land beperkings. Vier konseptuele bou-terreine is voorgestel wat jetty posisies en orientasies aandui. Die bou-terreine is in Noordbaai, Hoedjiespunt, en twee in Big Bay. Verskeie Sleutel Ontwerp Parameters (SOP’s), wat ‘n kritieke rol speel in die uiteindelike orientasie, werking en effektiwiteit van die VNG terminaal in Saldanhabaai, is geïdentifiseer. Die sensitiwiteit van die SOP’s by elk van die vier voorgestelde moontlikhede, is ondersoek. ‘n Ontleding van die effek van die SOP’s het variasie in die ontwerp moontlikhede by die verskillende bouterrein tot gevolg. Twaalf terminaal orientasie skemas is voorgestel. ‘n MKA is uitgevoer om ‘n ranglys van opsies te produseer in terme van tegniese effektiwiteit. Dit is voorgestel dat die top drie opsies verder ondersoek moet word. Die drie terminaal orientasie skemas, wat voorgestel word vir die Big Bay en Hoedjiespunt areas, maak gebruik van standaard jetties en drywende VNG tegnologie. Hierdie tesis bevind dat ‘n aantal uitvoerbare bouterreine en orientasies in Saldanhabaai moontlik is. ‘n Sistematiese analise van ontwerps kwessies wat na verkose opsies lei, word ook in die tesis ge-adresser. Die voorgestelde stappe in die besluitneming van ‘n finale terminaal skema vorm die slot van die tesis.
5

A movimentação de gás natural comprimido e liquefeito em pequena escala: as fronteiras de competitividade do modal rodoviário / The logistics of compressed natural gas and small-scale LNG: the competitive frontier of the roads modal.

Fraga, Denis Martins 18 October 2018 (has links)
A produção brasileira de gás natural (GN) cresceu 7,7% ao ano, entre 2006 e 2016, acompanhada do crescimento das descobertas de reservas de GN associado ao petróleo, oriundas dos campos contidos no polígono do pré-sal. Observa-se que a demanda por GN apresenta taxa de crescimento anual de 3,4% no período compreendido entre 2006 e 2018. No âmbito da oferta de GN, a reinjeção em poços demonstra um crescimento de 200% no período compreendido entre 2013 e 2018. Destaca-se na fonte de suprimento importada, através do gasoduto Bolívia-Brasil, o término da vigência do contrato de suprimento, previsto para 2019, que permitirá a renegociação das condições de fornecimento em termos de quantidade, preço e prazo. Tal importação também deverá se adequar às realidades de consumo e expectativas de crescimento da oferta doméstica no longo prazo. Este desequilíbrio, entre oferta e demanda, se apresenta como uma oportunidade no plano do aprimoramento da segurança energética do país, bem como nas diferentes dimensões de atrações de investimentos para expansão da indústria gasífera, através de métodos alternativos de movimentação de GN. Estes métodos são caracterizados neste trabalho como gás natural comprimido (GNC) e gás natural liquefeito em pequena escala (GNL). Identifica-se a competividade destes métodos de movimentação bem como são apresentados os principais elementos que compõem a formação de custos destes sistemas de movimentação de GN. Em seguida, é proposto um modelo de estimação de custos por unidade energética (USD/MMBTU), cuja competitividade, obtida através de simulações e comparadas com custos de gasodutos (utilizando-se o método abordado no PEMAT), é avaliada. Demonstra-se que, para volumes movimentados de 0.1MTPA, o a movimentação de GN por gasoduto apresenta menor custo por unidade energética até distâncias de 380 quilômetros (km). A partir desta distância, a movimentação através de sistemas de GNL apresenta-se mais competitiva. Observa-se que o GNC é mais competitivo que o GNL para distâncias de até 18 km, para o mesmo volume movimentado. Analisa-se as mesmas curvas para volumes movimentados de 0.5 MTPA e 1 MTPA, cuja competitividade do GNL, frente ao gasoduto, é observado em 650 km de distância no primeiro caso e não pode ser verificada no segundo caso. Em adição, o GNC apresentou resultados competitivos para volumes movimentados inferiores, cerca de 100 vezes, aos avaliados neste trabalho. Após a modelagem de estimação custos, aplica-se o modelo de GNL em pequena escala para abastecimento dos municípios situados no estado de São Paulo e em conjunto com o plano de metas do setor de gás natural (PMGN) para o estado. Observa-se que, dos 139 municípios avaliados, 103 municípios apresentaram competitividade ponderada para substituição de eletricidade e óleo combustível para fins térmicos industriais por GN. Do universo estudado, 85 municípios estavam contidos no PMGN com expectativa de instalação de infraestrutura de distribuição de GN entre 2022 e 2029 e cujo suprimento de NG poderia ser antecipado pelo sistema de GNL em pequena escala. / The Brazilian natural gas (NG) production has been growing 7,7% per year during 2006 and 2016, this growth has been followed by the increase of the reserves of oil associated natural gas from the fields within the pre-salt polygon. From the demand side, one can observe a growth of 3,4% per annum for the period starting in 2006 to 2018. It Worth to mention that the imported NG supply contract from Bolivia has its termination due to 2019, which will enable the negotiation of conditions of supply such as quantities, term and price. This import contract is expected to reflect the current conditions of demand and future supply from indigenous production in the long term. Based on that, on can observe an imbalance between supply and demand, which can be explored as an opportunity for improvements in the energy security of the country and also as an opportunity for investments in alternative methods for transportation of NG, in order to foster the industry. These alternative methods are described in this research as compressed natural gas (CNG) and small-scale LNG (SSLNG). It is explored not only the competitiveness of those methods but also the cost indicatives and the state of the art technologies are presented. Followed the characterising of CNG and SSLNG, a cost per-unit-of-energy estimation model is proposed for CNG and SSLNG and compared with the pipelines cost estimation adopted in the PEMAT. It is demonstrated that, for the transportation volumes of 0.1MTPA, pipelines option is more competitive than SSLNG up to 380 kilometres (km) transportation distance. SSLNG option was observed more competitive for transportation distances higher than 380 km. On the other hand, CNG option has demonstrated competitiveness only against SSLNG option and for transportation distances up to 18 km. For the transportation volumes of 0.5 MTPA and 1 MTPA, the SSLNG option was observed more competitive than the pipeline option, for transport distances higher than 650 km for the former volumes transported and no competitiveness was observed for the latter volumes transported. Additionally, for the sake of illustration, CNG has demonstrated competitiveness against SSLNG and pipeline for lower transported volumes, around 100 times lower than 0.1MTPA. After the cost estimation modelling, the SSLNG model was applied in the municipalities of the state of São Paulo and together with the plan of targets for the NG sector (PMGN) for the state. One can observe 103 municipalities out of 139 have shown competitive costs of SSLNG in the displacement of electricity and oil fuel for the thermic energy uses in the industrial and agricultural sector. 85 municipalities out of the 103 were considered in the PMGN as municipalities that would have NG distribution pipelines infrastructure from 2022 to 2029 and could anticipate the use on NG by adopting the SSLNG.

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