The primary aim of this thesis is to propose a method to develop the process synthesis and optimization of the production of syngas and ammonia, as well as other byproducts such as marketable CO2, in synthetic nitrogen fertilizers (SNF) complexes. The baseline analysis relies on a typical 1000 t/day ammonia production plant composed of syngas production, purification (CO2 capture) and compression systems, along with an industrial ammonia synthesis unit. Initially, exergy and exergoeconomy analyses are used to identify the most important sources of energy consumption and irreversibility associated to the operation units of the integrated plant. From these results, a variety of alternatives for the improvement of the performance at the plantwide and component level are thoroughly examined along the different chapters. Due to the large amount of possible configurations and interrelations, the optimization process may become a formidable engineering task to be solved by using merely trial and error approaches. Accordingly, a systematic approach, based on the combination of heuristics, thermodynamic principles and mathematical programming is used to identify, evaluate, and determine the best configurations in terms of exergy consumption, degree of energy integration, process irreversibility, atmospheric CO2 emissions and operating costs. In this way, the process synthesis and optimization include not only the modification of the main process parameters but also the arrangement of the chemical plant components, suitably integrated to the waste heat recovery and cogeneration systems. Several aspects concerning: (i) the choice of the syngas purification system, (ii) the nature of the energy resources consumed, (iii) the exploitation of the thermodynamic potential at higher temperatures, (iv) the increase of the pre-combustion carbon capture by introducing chemically recuperated concepts, (v) the gradual variation of operating conditions by applying Le Châtelier and Counteraction principles, as well as (vi) the environmental benefits of using alternative energy sources to decarbonize the SNF sector are analyzed in the light of the reduced room of improvement found in modern conventional ammonia production facilities. The results show significant potentials for decreasing the exergy intensity and environmental impact of those facilities. This allows issuing relevant recommendations for revamping the existing plants or embracing new approaches that attempt to minimize the economic costs, the process inefficiencies and mitigate the environmental impact produced. An efficiency increase of about 8-10% can be achieved by using more efficient combined cycle cogeneration systems with an affordable marginal investment cost. Alternative configurations with enhanced pre-combustion carbon capture, using either a CRGT system or upgraded biomass residues, may help cutting down the overall CO2 emissions in the syngas production in 20-28% or even promoting the decarbonization of the SNF sector at net rates of atmospheric CO2 depletion close to -2.3 tCO2/tNH3, respectively. The reduction of the process irreversibility has been also reduced by 10-13% in an industrial ammonia synthesis unit through the application of dual pressure systems and the introduction of a purge gas treatment process. / Sem resumo

Iniciativas de integração energética regional podem contribuir para a obtenção de benefícios diversos aos países envolvidos: redução tarifária, melhor utilização de recursos energéticos, aprimoramento da infraestrutura, além de aproximar os países em questão, viabilizando eventuais cooperações políticas e econômicas. Na América Latina, a despeito do surgimento de inúmeros projetos e instituições voltados a este propósito, a integração energética restringiu-se, em sua maioria, a empreendimentos bilaterais, cujo sucesso foi, ainda assim, relativo. Este trabalho buscou compreender algumas iniciativas de integração energética, no âmbito da energia elétrica e dos hidrocarbonetos, à luz do modo de inserção da América Latina nas esferas de produção e circulação de mercadorias na economia mundial, valendo-se do referencial teórico da Teoria Marxista da Dependência (TMD). Essa escolha decorreu da especificidade da análise e visão crítica dessa corrente teórica sobre a promoção do desenvolvimento e o posicionamento da América Latina no sistema capitalista mundial, para a qual o processo de integração regional assume papel central. Três categorias - Dependência, Subimperialismo e Integração - foram empregadas para nortear a sistematização e análise das experiências de integração energética escolhidas: o Sistema de Interconexión Eléctrica de los Países de América Central (SIEPAC), a PetroCaribe e o contrabando de combustível na fronteira entre Venezuela e Colômbia. As etapas metodológicas incluíram: revisão do processo histórico da formação da indústria energética da América Latina e levantamento de indicadores, para a seleção dos empreendimentos a estudar; descrição de cada empreendimento, incluindo antecedentes de sua concepção e implantação, indicadores técnicos e socioeconômicos dos países envolvidos e detalhamento da sua estrutura, funcionamento e resultados atingidos, ou não. A partir desses elementos, as iniciativas de integração foram caracterizadas, com base no atendimento aos critérios constitutivos das categorias de análise selecionadas. A principal conclusão do trabalho foi de que há vínculos entre a condição de Dependência dos países e as tentativas de integração energética estudadas, no sentido de que as iniciativas são impactadas por essa condição (intrínseca aos participantes), mas, ao mesmo tempo, causam impacto sobre ela: contribuem para agravá-la ou para sua atenuação. Ressalta-se, por fim, que a integração energética pode contribuir para a emancipação da América Latina, desde que seja, entretanto, garantida a priorização dos benefícios e melhora da condição de vida da população latino-americana e não, apenas, privilegiado o processo de acumulação de capital. / Regional energy integration initiatives may bring a variety of benefits to the countries involved: tariff reductions, better use of energy resources, improvement of the infrastructures and to bring closer the countries involved, making political and economic cooperation possible. In Latin America, despite the emergence of numerous projects and institutions focused on this purpose, the energetic integration was mostly restricted to bilateral projects which success was still relative. This dissertation sought to understand some of the energetic integration initiatives, in the field of electric energy and hydrocarbons, considering Latin Americas role in the production sphere and the circulation of goods sphere in the world economy, using the theoretical reference of the Marxist Dependency Theory. This choice was made as a result of the specificity of the analysis and the critical view of the theory about the promotion of Latin Americas development and positioning in the world capitalist system, which the process of regional integration assumes a central role. Three categories Dependency, Subimperalism and Integration were used to guide the systematization and analysis of the chosen energy integration experiences: the Sistema de Interconexión Eléctrica de los Países de América Central (SIEPAC), the PetroCaribe and the fuel smuggling at the Venezuela-Colombia border. The methodology steps included: review of the Latin American energy industry historical process of formation and definition of indicators to select the initiatives to study; description of each initiative, including antecedents of its design and implementation, technical and socio-economic indicators of the countries involved and detailed analysis of its structure, operation and results, achieved or not. From these elements, the integration initiatives were characterized based on the criteria met of the selected categories of the analysis. The main conclusion of this dissertation was that there are links between the dependency condition and the energy integration attempts studied, which means that the initiatives are impacted by this condition (intrinsic to the participants) but, at the same time, have an impact on it: they contribute to the aggravation or mitigation of the dependency condition. Finally, it should be emphasized that energy integration can contribute to the emancipation of Latin America since priority is given to the benefits and improvement of the living conditions of the Latin American, and not only privileging process of capital accumulation.

Este trabalho trata da análise de projetos de integração energética na América do Sul, em particular da área do MERCOSUL e dos países associados Bolívia e Chile. Com este trabalho busca-se identificar quais foram as motivações socioeconômicas que impulsionaram três projetos relevantes nessa região, a saber: Itaipu Binacional, Gasbol e Gasandes. A pesquisa tem o fito de mostrar a tese de que esses projetos foram realizados em diversos contextos históricos, mas que em todos os casos tiveram como referencia a acumulação capitalista. Para tanto, se escolhe um método que contextualiza os projetos na história e identificam-se, por meio da análise histórica, quais foram os setores da sociedade que receberam os maiores benefícios econômicos e qual foi a participação dos Estados em cada caso. O estudo mostra que nos projetos analisados, ainda tendo diferentes graus de participação dos Estados, a reprodução do capital constitui a motivação principal destes projetos, pois foram os capitais nacionais e internacionais os que tiveram seus lucros garantidos, em detrimento de empresas estatais ou públicas, ou bem em detrimento da população. As formas para garantir a acumulação privada foram diferentes e dependeram do contexto histórico em que cada projeto foi desenvolvido. No projeto Itaipu, as empresas foram beneficiadas com contratos de elevado valor e com tarifas abaixo do custo do serviço de eletricidade (isto particularmente para os grandes consumidores). Ademais, o manejo financeiro da dívida permitiu grandes transferências para o sistema financeiro. Nos casos de Gasbol e de Gasandes o modelo de organização dos projetos permitiu benefícios para as empresas em detrimento da Petrobras, no primeiro caso, e em detrimento diretamente da população, no segundo caso. / This work deals with the analysis of energy integration projects in the South America, in particular, in South American Common Market and its associated countries Bolivia and Chile. The thesis aims to identify the social and the economic motivations that stimulated the following three prominent projects in the region: Itaipu Binacional, Gasbol and Gasandes. The research thesis was that those projects were carried out taking as reference the capitalist accumulation, despite they were developed in diverse historical contexts. To carry out the research was chosen a methodological approach which puts the projects into an historical context and identifies, by means of the analysis, which were the sectors of the society that received the main economic benefits and which was the participation of the States in each case. The study concluded that in the projects analyzed, even having different levels of participation of the States, the reproduction of the capital was the main motivation of the projects. So, the international and national capitals had their profits guaranteed, but the risks and the financial losses were transferred to the state-owned or public companies or to the population. The forms to guarantee the private accumulation were different and depend on the historical context of each project. In the Itaipu project, for instance, the companies were benefited with high value contracts and with low tariffs of electricity (for huge consumers). Besides, the financial management of the debt permitted huge transferences from Itaipu to the financial system. In the cases of Gasbol and Gasandes the model of organization of the projects permitted benefits to the companies. The risks or financial losses were assumed by Petrobras, in the first case, and by the population, in the second case.

Brazil\'s discoveries of large gas reservoirs in the offshore ultra-deep waters of the presalt fields show a promising scenario, along with strategic investment and adequate policy, for the development of natural gas infrastructure and a sustainable transition in the Brazilian electricity mix. Such transition should occur through the use of transnational natural gas pipelines connected to large industrial facilities and power stations, as part of strategic planning to expand industrial usage, and avoid the shortage of electricity supply, with economic and environmental advantages. Since the most important debates of the new millennium are focused on globalization and sustainable development for nations, transnational energy integration in Latin America has been receiving increasingly attention from researchers and policy makers. In this overall context, the purpose of the present research was to develop a model to study, in a comparative manner, the thermoelectric generation, as well as to analyze the effect of legal frameworks and governmental policies on the development of infrastructure and natural gas market in Brazil, with a detailed study of the most relevant market and regulatory mechanisms. A comparison was performed in terms of the most relevant regulatory legislation in Brazil and other relevant Member States of the South American economic block. The study also evaluates the sanctions imposed by ANEEL Resolution n. 583 of 2013 on suppliers, due to the lack of NG supply for thermoelectric utilities, proposing an alternative formula, thought to mitigate the influence of averages and other electricity market parameters, therefore decreasing the sanction value for the NG supplier, without compromising the contract neutrality. Different factors were analyzed in order to determine which technology would be the most efficient in terms of levelized costs. Results indicated that natural gas-fired generators are very competitive and efficient, when compared to other thermoelectric sources in both economic and environmental aspects, even when externalities were included. Also, that further strategic investment and adequate regulatory policy changes are required from the market agents, in order to foster the development of pipeline infrastructure and the expansion of natural gas use in Brazil. The study also demonstrates that the environmental impact of the CH4 leakage equals that of CO2 release from combustion at about 4.2% leakage on a mass basis, when methane leakage rises to a level in which natural gas becomes as greenhouse gas intensive as biomass. / As descobertas de substanciais reservatórios de gás natural no Brasil, localizados em águas ultra profundas após a camada Pré-Sal, demonstram um cenário promissor, aliado a investimentos estratégicos e a políticas públicas adequadas, para o desenvolvimento da infraestrutura de gás natural e uma transição sustentável na matriz elétrica brasileira. Tal transição deveria ocorrer por intermédio do uso de tubulação transnacional de gás natural, conectada a grandes instalações industriais e a usinas termelétricas, como parte de um planejamento estratégico voltado à expansão do uso de gás natural na indústria e a evitar a escassez no suprimento de energia elétrica, com vantagens econômicas e ambientais. Considerando que os debates mais relevantes do novo milênio estão focados na globalização e no desenvolvimento sustentável das nações, a integração transnacional na América Latina tem recebido crescente atenção por parte de pesquisadores e de elaboradores das políticas públicas. Nesse contexto geral, a proposta da presente pesquisa foi a de desenvolver um modelo para estudar, de uma forma comparativa, a geração termelétrica, bem como analisar o impacto do arcabouço jurídico-regulatório e das políticas governamentais no desenvolvimento da infraestrutura e do mercado do gás natural no Brasil, com um estudo detalhado dos mais relevantes mecanismos regulatórios e de mercado. Foi realizado, ainda, um comparativo da legislação regulatória do gás natural no Brasil com outros Estados-Membros relevantes do Mercosul. O estudo também avalia as sanções impostas pela Resolução ANEEL n. 583 de 2013 nos fornecedores, devido a corte no suprimento de gás natural para empreendimentos de geração termelétrica, propondo um cálculo alternativo visando a mitigar a influência das médias e outros parâmetros intrínsecos ao mercado de energia, dessa maneira reduzindo as sanções contratuais para o fornecedor de gás natural, sem prejudicar a neutralidade contratual. Diferentes fatores foram analisados de forma a determinar qual tecnologia seria a mais eficiente em termos de custos nivelados de eletricidade. Os resultados indicaram que as termelétricas a gás natural são muito competitivas e eficientes, quando comparadas com outros tipos de combustível, tanto pelo aspecto ambiental quanto pelo econômico, mesmo quando externalidades são incluídas. Ainda, que são necessárias mudanças nas políticas regulatórias e no investimento estratégico por parte dos agentes do mercado, de forma a incentivar o desenvolvimento de infraestrutura e a expansão do uso do gás natural no Brasil. O estudo também evidencia que o impacto ambiental do vazamento de CH4 se iguala àquele do CO2 liberado pela combustão em cerca de 4.2% em base mássica, quando o vazamento de metano atinge um nível em que seu impacto como gás do efeito estufa fica equivalente à biomassa.

O presente trabalho propõe sistemas para eliminar o efluente líquido (lixiviado) de um aterro sanitário a partir da combustão do efluente gasoso (biogás) gerado no mesmo local, caracterizando a integração energética dos dois efluentes. As gerações de biogás e lixiviado são referentes ao aterro de Guajuviras e são estimadas usando o modelo de IPCC, 2006 e o modelo de balanço hídrico respetivamente, estimando também suas incertezas de geração. Os resultados foram obtidos para a fase de operação e posteriormente de fechamento de um aterro real, com uma incerteza estimada de 50%. A integração energética dos efluentes é primeiramente verificada para situações de máxima eficiência por meio de balanços de massa e energia. Em sequencia, cinco propostas conceituais de sistemas são apresentadas, tendo em comum a completa eliminação do lixiviado a partir da energia do biogás. Os sistemas Combustor-Evaporador (CE) e Incinerador-Evaporador (IE) tem como produto apenas a evaporação do lixiviado, e consomem cerca de 30% do biogás disponível no aterro. Os sistemas Motor-Evaporador (ME), Combustor-Motor-Evaporador (CME) e Incinerador-Motor-Evaporador (IME) são montados com a finalidade de aproveitar o excedente de biogás, mantendo sempre a evaporação completa do lixiviado. O desempenho dos sistemas propostos é avaliado por meio de indicadores técnico-ambientais e financeiros ao longo de um período de vinte anos, e sua importância é ordenada usando elementos da análise hierárquica de processos (AHP). Todos os sistemas propostos indicam ser viáveis, destacando-se aqueles que produzem energia elétrica, que se mostraram mais atraentes do ponto de vista técnico-ambiental, porém com investimentos específicos altos. Os sistemas que promovem a eliminação do lixiviado e produzem eletricidade com o excedente de biogás (CME e IME) são os mais viáveis financeiramente, com payback de 7 e 8 anos, VPL na media de US $4.790.00 e TIR de 39% aproximadamente. A AHP indica que os sistemas baseados em cogeração têm pesos similares, variando só em 3% ao serem avaliados num viés ambiental. Da mesma forma, o cenário de viés financeiro apresentou uma pequena diferença entre os sistemas CME, IME e CE. / The present work proposes systems to carry out the thermal decommissioning of the liquid effluent (leachate) from a sanitary landfill through the combustion of the gas effluent (biogas) produced in the same place, characterizing the energy integration of the two effluents. The biogas and leachate productions refer to the Guajuviras landfill and are estimated using the IPCC model, 2006, and the water balance model respectively, their production uncertainties are also estimated. The results are obtained for the operation phase and afterwards for a former real landfill, with an estimated uncertainty of 50%. The energy integration of effluents is first verified for situations of maximum efficiency through mass and energy balances. In the sequence, five conceptual proposals of systems are presented, having in common the complete reduction of the leachate from the biogas energy. The simplest CE and CI systems have only the leachate evaporation, and consume about 30% of the biogas available in the landfill. The ME, CME and IME systems are set up to take advantage of the biogas surplus, always maintaining complete evaporation of the leachate. The performance of the proposed systems is evaluated through technical-environmental (PEB and PEL) and financial indicators (IES, NPV, TIR and PB) over a period of twenty years, and their importance is ordered using the Analytic Hierarchy Process (AHP). All proposed systems indicate that they are feasible, especially those that produce electricity, which have been more attractive from an environmental and technical point of view, but with high specific investments (IES). The systems that promote leachate abatement and produce electricity with biogas surplus (CME and EMI) are the most financially viable, with paybacks of 7 and 8 years, NPV average of US $ 4,790.00 and IRR of approximately 39%. The AHP indicates that the cogeneration-based systems have similar weights, varying only by 3% when evaluated in an environmental bias. Likewise, the financial bias scenario presented a small difference between the CME, EMI and EC systems.

Este trabalho estuda a integração energética ancorada no gás natural entre os países que formam o chamado Cone Sul, ou seja: Argentina, Bolívia, Brasil, Chile, Paraguai e Uruguai. Inclui-se uma breve revisão histórica, bem como uma análise comparativa com outras realidades internacionais. O trabalho volta-se para o futuro e assume como pressuposto que a integração energética e econômica das nações representa uma estratégia fundamental para que nações e regiões possam aumentar sua competitividade em um mundo cada vez mais global. A partir de revisão e análise das experiências de integração energética norte americana e européia, com ênfase no gás natural, são avaliados os fatores que levaram esses países a atingirem o atual nível de integração, buscando os fatores coincidentes e eventuais diferenças, que ajudem a guiar no caminho de uma integração sul americana, especificamente no Cone Sul. Esse trabalho também se propõe a analisar os a formação das indústrias de gás natural nos principais países que formam o chamado Cone Sul, tentando entender as principais questões regulatórias e econômicas assim como quais foram as principais influências geopolíticas nessa formação. Também é avaliada a estrutura logística que conecta esses países e como eles se relacionam comercialmente e também na esfera geopolítica. A análise parte do princípio que novos pontos de recebimento Gás Natural Liquefeito - GNL através de navios no Brasil, Chile e, possivelmente, no Uruguai trarão, além de uma oferta adicional de gás natural, um sinal de preço até então inédito em toda região. Propõe-se então, que a partir desses novos fatores logístico e econômico, crie-se a motivação para que se produza uma regulação de transporte e comercialização de gás natural para todo Cone Sul e assim se inicie um processo integração baseado na racionalidade econômica. A proposta é verificar a possibilidade de que os países que formam o Cone Sul aproveitem o fato de já estarem interligados fisicamente através de gasodutos evoluam para uma integração econômica e regulatória na indústria gasífera. / This work studs the energy integration based on natural gas among the countries from the Southern Cone: Argentina, Bolivia, Brazil, Chile Paraguay and Uruguay. It includes a short historic review as well as a comparative analysis with other realities. This work look to the future and assumes that the energy and economy integration represents a fundamental strategy for countries e regions to increase their competitiveness inside a global world. From the review and the analysis of North American and European Energy integration experiences, with emphasis on natural gas, the events that led these countries to accomplish the present integration degree will be evaluated, presenting coincident factors and eventual differences that could help guide to the way of South American integration, specifically in the so-called Southern Cone. This study also proposes to review the natural gas industries formation in the main countries that form the Southern Cone, trying to understand the most important regulatory and economic issues as well as the essential geopolitical influences on such formation. The logistics structure that connects these countries, the way they relate commercially and their geopolitical relation will also be assessed. The analysis supposes that new Natural Gas Liquefied - LNG reception terminals through Brazilian, Chilean and possibly Uruguaian vessels will bring both an additional supply of natural gas and a new price indication throughout the region. In view of that and considering these new economic and logistical factors, the creation of a motivation to construct a natural gas transportation and marketing regulation for all Southern Cone is proposed, starting an integration process based on economic rationality. This study purpose is to launch the stimulus for the Southern Cone countries to take advantage of the fact that they are already physically interconnected and thus also create mechanisms for economic integration.

Brazil\'s discoveries of large gas reservoirs in the offshore ultra-deep waters of the presalt fields show a promising scenario, along with strategic investment and adequate policy, for the development of natural gas infrastructure and a sustainable transition in the Brazilian electricity mix. Such transition should occur through the use of transnational natural gas pipelines connected to large industrial facilities and power stations, as part of strategic planning to expand industrial usage, and avoid the shortage of electricity supply, with economic and environmental advantages. Since the most important debates of the new millennium are focused on globalization and sustainable development for nations, transnational energy integration in Latin America has been receiving increasingly attention from researchers and policy makers. In this overall context, the purpose of the present research was to develop a model to study, in a comparative manner, the thermoelectric generation, as well as to analyze the effect of legal frameworks and governmental policies on the development of infrastructure and natural gas market in Brazil, with a detailed study of the most relevant market and regulatory mechanisms. A comparison was performed in terms of the most relevant regulatory legislation in Brazil and other relevant Member States of the South American economic block. The study also evaluates the sanctions imposed by ANEEL Resolution n. 583 of 2013 on suppliers, due to the lack of NG supply for thermoelectric utilities, proposing an alternative formula, thought to mitigate the influence of averages and other electricity market parameters, therefore decreasing the sanction value for the NG supplier, without compromising the contract neutrality. Different factors were analyzed in order to determine which technology would be the most efficient in terms of levelized costs. Results indicated that natural gas-fired generators are very competitive and efficient, when compared to other thermoelectric sources in both economic and environmental aspects, even when externalities were included. Also, that further strategic investment and adequate regulatory policy changes are required from the market agents, in order to foster the development of pipeline infrastructure and the expansion of natural gas use in Brazil. The study also demonstrates that the environmental impact of the CH4 leakage equals that of CO2 release from combustion at about 4.2% leakage on a mass basis, when methane leakage rises to a level in which natural gas becomes as greenhouse gas intensive as biomass. / As descobertas de substanciais reservatórios de gás natural no Brasil, localizados em águas ultra profundas após a camada Pré-Sal, demonstram um cenário promissor, aliado a investimentos estratégicos e a políticas públicas adequadas, para o desenvolvimento da infraestrutura de gás natural e uma transição sustentável na matriz elétrica brasileira. Tal transição deveria ocorrer por intermédio do uso de tubulação transnacional de gás natural, conectada a grandes instalações industriais e a usinas termelétricas, como parte de um planejamento estratégico voltado à expansão do uso de gás natural na indústria e a evitar a escassez no suprimento de energia elétrica, com vantagens econômicas e ambientais. Considerando que os debates mais relevantes do novo milênio estão focados na globalização e no desenvolvimento sustentável das nações, a integração transnacional na América Latina tem recebido crescente atenção por parte de pesquisadores e de elaboradores das políticas públicas. Nesse contexto geral, a proposta da presente pesquisa foi a de desenvolver um modelo para estudar, de uma forma comparativa, a geração termelétrica, bem como analisar o impacto do arcabouço jurídico-regulatório e das políticas governamentais no desenvolvimento da infraestrutura e do mercado do gás natural no Brasil, com um estudo detalhado dos mais relevantes mecanismos regulatórios e de mercado. Foi realizado, ainda, um comparativo da legislação regulatória do gás natural no Brasil com outros Estados-Membros relevantes do Mercosul. O estudo também avalia as sanções impostas pela Resolução ANEEL n. 583 de 2013 nos fornecedores, devido a corte no suprimento de gás natural para empreendimentos de geração termelétrica, propondo um cálculo alternativo visando a mitigar a influência das médias e outros parâmetros intrínsecos ao mercado de energia, dessa maneira reduzindo as sanções contratuais para o fornecedor de gás natural, sem prejudicar a neutralidade contratual. Diferentes fatores foram analisados de forma a determinar qual tecnologia seria a mais eficiente em termos de custos nivelados de eletricidade. Os resultados indicaram que as termelétricas a gás natural são muito competitivas e eficientes, quando comparadas com outros tipos de combustível, tanto pelo aspecto ambiental quanto pelo econômico, mesmo quando externalidades são incluídas. Ainda, que são necessárias mudanças nas políticas regulatórias e no investimento estratégico por parte dos agentes do mercado, de forma a incentivar o desenvolvimento de infraestrutura e a expansão do uso do gás natural no Brasil. O estudo também evidencia que o impacto ambiental do vazamento de CH4 se iguala àquele do CO2 liberado pela combustão em cerca de 4.2% em base mássica, quando o vazamento de metano atinge um nível em que seu impacto como gás do efeito estufa fica equivalente à biomassa.

Electric energy constitutes one of the most crucial elements to almost every aspect of life of people. The modern electric power systems face several challenges such as efficiency, economics, sustainability, and reliability. Increase in electrical energy demand, distributed generations, integration of uncertain renewable energy resources, and demand side management are among the main underlying reasons of such growing complexity. Additionally, the elements of power systems are often vulnerable to failures because of many reasons, such as system limits, weak conditions, unexpected events, hidden failures, human errors, terrorist attacks, and natural disasters. One common factor complicating the operation of electrical power systems is the underlying uncertainties from the demands, supplies and failures of system components. Stochastic programming provides a mathematical framework for decision making under uncertainty. It enables a decision maker to incorporate some knowledge of the intrinsic uncertainty into the decision making process. In this dissertation, we focus on application of two-stage and multistage stochastic programming approaches to electric energy systems modeling and optimization. Particularly, we develop models and algorithms addressing the sustainability and reliability issues in power systems. First, we consider how to improve the reliability of power systems under severe failures or contingencies prone to cascading blackouts by so called islanding operations. We present a two-stage stochastic mixed-integer model to find optimal islanding operations as a powerful preventive action against cascading failures in case of extreme contingencies. Further, we study the properties of this problem and propose efficient solution methods to solve this problem for large-scale power systems. We present the numerical results showing the effectiveness of the model and investigate the performance of the solution methods. Next, we address the sustainability issue considering the integration of renewable energy resources into production planning of energy-intensive manufacturing industries. Recently, a growing number of manufacturing companies are considering renewable energies to meet their energy requirements to move towards green manufacturing as well as decreasing their energy costs. However, the intermittent nature of renewable energies imposes several difficulties in long term planning of how to efficiently exploit renewables. In this study, we propose a scheme for manufacturing companies to use onsite and grid renewable energies provided by their own investments and energy utilities as well as conventional grid energy to satisfy their energy requirements. We propose a multistage stochastic programming model and study an efficient solution method to solve this problem. We examine the proposed framework on a test case simulated based on a real-world semiconductor company. Moreover, we evaluate long-term profitability of such scheme via so called value of multistage stochastic programming.

Electricity generation from wind power and other renewable energy sources is increasing, and their variability introduces new challenges to the existing power system, which cannot cope effectively with highly variable and distributed energy resources. The emergence of smart grid technologies in recent year has seen a paradigm shift in redefining the electrical system of the future, in which controlled response of the demand side is used to balance fluctuations and intermittencies from the generation side. This thesis investigates the impact of smart grid technologies on the integration of wind power into the power system. A smart grid power system model is developed and validated by comparison with a real-life smart grid experiment: the Olympic Peninsula Demonstration Experiment. The smart grid system model is then expanded to include 1000 houses and a generic generation mix of nuclear, hydro, coal, gas and oil based generators. The effect of super-imposing varying levels of wind penetration are then investigated in conjunction with a market model whereby suppliers and demanders bid into a Real-Time Pricing (RTP) electricity market. The results demonstrate and quantify the effectiveness of DR in mitigating the variability of renewable generation. It is also found that the degree to which Greenhouse Gas (GHG) emissions can be mitigated is highly dependent on the generation mix. A displacement of natural gas based generation during peak demand can for instance lead to an increase in GHG emissions. Of practical significance to power system operators, the simulations also demonstrate that Demand Response (DR) can reduce generator cycling and improve generator efficiency, thus potentially lowering GHG emissions while also reducing wear and tear on generating equipment. / Graduate

An increased penetration of renewable energy into the electric power grid is desirable from an environmental standpoint as well as an economical one. However, renewable sources such as wind and solar energy are often variable and intermittent, and additionally, are non-dispatchable. Also, the locations with the highest amount of available wind or solar may be located in areas that are far from areas with high levels of demand, and these areas may be under the control of separate, individual entities. In this dissertation, a method that coordinates these areas, accounts for the variability and intermittency, reduces the impact of renewable energy forecast errors, and increases the overall social benefit in the system is developed. The approach for the purpose of integrating intermittent energy sources into the electric power grid is considered from both the planning and operations stages. In the planning stage, two-stage stochastic optimization is employed to find the optimal size and location for a storage device in a transmission system with the goal of reducing generation costs, increasing the penetration of wind energy, alleviating line congestions, and decreasing the impact of errors in wind forecasts. The size of this problem grows dramatically with respect to the number of variables and constraints considered. Thus, a scenario reduction approach is developed which makes this stochastic problem computationally feasible. This scenario reduction technique is derived from observations about the relationship between the variance of locational marginal prices corresponding to the power balance equations and the optimal storage size. Additionally, a probabilistic, or chance, constrained model predictive control (MPC) problem is formulated to take into account wind forecast errors in the optimal storage sizing problem. A probability distribution of wind forecast errors is formed and incorporated into the original storage sizing problem. An analytical form of this constraint is derived to directly solve the optimization problem without having to use Monte-Carlo simulations or other techniques that sample the probability distribution of forecast errors. In the operations stage, a MPC AC Optimal Power Flow problem is decomposed with respect to physical control areas. Each area performs an independent optimization and variable values on the border buses between areas are exchanged at each Newton-Raphson iteration. Two modifications to the Approximate Newton Directions (AND) method are presented and used to solve the distributed MPC optimization problem, both with the intention of improving the original AND method by improving upon the convergence rate. Methods are developed to account for numerical difficulties encountered by these formula- tions, specifically with regards to Jacobian singularities introduced due to the intertemporal constraints. Simulation results show convergence of the decomposed optimization problem to the centralized result, demonstrating the benefits of coordinating control areas in the IEEE 57- bus test system. The benefit of energy storage in MPC formulations is also demonstrated in the simulations, reducing the impact of the fluctuations in the power supply introduced by intermittent sources by coordinating resources across control areas. An overall reduction of generation costs and increase in renewable penetration in the system is observed, with promising results to effectively and efficiently integrate renewable resources into the electric power grid on a large scale.