A atual problemática ambiental provocada pela atividade humana tem ganhado destaque na sociedade, à medida que se busca o desenvolvimento mundial. Um fator de extrema relevância neste cenário é a produção de energia elétrica, responsável por uma grande parcela das emissões causadoras do efeito estufa. Por conta disso, é preciso pensar em um desenvolvimento sustentável, com fontes alternativas de energia atrativas para esse objetivo, principalmente em localidades não abastecidas pela rede convencional de eletricidade, como é o caso de muitas comunidades da região nordeste brasileira. Assim, esse trabalho tem por objetivos calcular o custo ambiental, na fase de geração de eletricidade, para as fontes alternativas de energia solar, eólica e biomassa e estimar a viabilidade econômica dessas fontes em pequenas comunidades da região Nordeste do Brasil, considerando os custos evitados. É preciso identificar as externalidades e valorá-las de forma adequada para que os custos ou benefícios possam ser internalizados e reflitam de forma correta a viabilidade ou inviabilidade econômica dessas fontes. Para os objetivos propostos, adotou-se o método dos custos evitados para o cálculo das externalidades. Essa variável foi incluída no equacionamento desenvolvido para todas as fontes de energia alternativas consideradas. Foram feitos os cálculos de viabilidade econômica, considerando as novas configurações adotadas, sendo que o novo equacionamento foi reprogramado no Programa de Cálculo de Custos de Energias Alternativas, Solar, Eólica e Biomassa (PEASEB). Os resultados demonstraram que a fonte mais viável e amplamente aplicável em pequenas comunidades da região nordeste brasileira é a energia solar fotovoltaica em sistemas isolados. / There has been an increasing concern about current environmental issues caused by human activity, as the world searches for development. The production of electricity is an extremely relevant factor in this scenario since it is responsible for a large portion of the emissions that cause the greenhouse effect. Due to this fact, a sustainable development with alternative energy sources, which are attractive for such purpose, must be proposed, especially in places that are not supplied by the conventional electricity grid such as many communities in the Northeast Brazil. This work aims to calculate the environmental cost for the alternative sources of energy solar, wind and biomass during electricity generation, and to estimate the economic feasibility of those sources in small communities of Northeast Brazil, considering the avoided costs. The externalities must be properly identified and valued so the costs or benefits can be internalized and reflect accurately the economic feasibility or infeasibility of those sources. For this, the method of avoided costs was adopted for the calculation of externalities. This variable was included in the equation developed for all considered alternative energy sources. The calculations of economic feasibility were performed taking the new configurations in consideration, and the new equation was reprogrammed in the Programa de Cálculo de Custos de Energias Alternativas, Solar, Eólica e Biomassa (PEASEB). The results demonstrated that the solar photovoltaic energy in isolated systems is the most feasible and broadly applicable source for small communities of Northeast Brazil.

O objetivo deste trabalho é discutir as principais ações para que iniciativas de recuperação e uso de biogás gerado por resíduos sejam bem sucedidas. A discussão se inicia com informações a respeito do aumento do efeito estufa e da escassez de recursos naturais. O Brasil, um país em desenvolvimento, deve promover melhorias sanitárias em todos os níveis: coleta e disposição de resíduos sólidos, esgotamento e tratamento dos esgotos domésticos e comerciais e contenção e tratamento de fluentes industriais. O país deve também otimizar o uso de seus recursos energéticos preservando a qualidade ambiental. Ao final da Rio 92, o Governo Brasileiro assumiu o compromisso de realizar inventários de emissões dos GEE. Nestes se inclui o inventário de emissões de metano gerado pela degradação anaeróbia de resíduos. Sabe-se que, pela degradação anaeróbia dos resíduos, em 1.990, o Brasil emitia cerca de 800Gg de metano ao ano e estima-se 900Gg para o ano de 2.000. Nesse total não se identifica nenhuma iniciativa de recuperação energética bem sucedida em andamento. A maior parte do biogás é gerada pela degradação dos resíduos sólidos. Para que se promova a recuperação do biogás nos locais de disposição de resíduos sólidos (LDRS) deve-se, em primeiro lugar, promover a correta disposição dos resíduos sólidos. Deve-se fazer ainda com que o correto manejo do aterro inclua a recuperação do biogás gerado. Lembrando que esta atividade, na maioria dos casos, é responsabilidade do poder público, deve-se incluir ao processo a garantia de continuidade da atividade de uma gestão administrativa para outra. Cerca de 11% do metano gerado pela degradação anaeróbia de resíduos vem de efluentes industriais. O processo anaeróbio tem uma intensidade energética bastante inferior à do processo convencional. Para que uma indústria opte pela tecnologia anaeróbia, esta deve ter um eficiente controle de processo industrial impedindo que o efluente seja contaminado por substâncias tóxicas aos organismos anaeróbios. A iniciativa privada, diante de uma oportunidade de negócio lucrativo, naturalmente cria iniciativas replicáveis. Há vários países desenvolvendo projetos de recuperação de biogás. No Brasil são identificados vestígios dessa atividade, ocorrida nas décadas de 1.970 e 1.980. O encolhimento da economia nacional, a diminuição dos preços internacionais de combustíveis fósseis e a falta de incentivos ambientais e tributários podem ser responsabilizados pelo fim dos projetos. Hoje, a possibilidade de obtenção de ganhos econômicos pela emissão evitada de GEE através dos certificados de redução de emissões (CER) associada a incentivos ambientais e fiscais pode criar expectativas favoráveis para essa atividade. / The objective of this thesis is to discuss the main actions to achieve the success of the recovery and use of biogás generated by wastes initiatives. The discussion begins with information regarding the increase of the greenhouse effect and the shortage of natural resources. Brazil, a developing country, should promote sanitary improvements in all levels: collection and disposal of solid wastes, domestic and commercial wastewater sewage and treatment, as well as industrial wastewater treatment. The country must also optimize the use of its energy resources preserving the environmental quality. At end of Rio 92, the Brazilian Government has assumed the commitment to conducting emission inventories of greenhouse gases. Among these is included the inventory of methane emissions generated by the anacrobic degradation of wastes. It is known that in 1.990 Brazil emitted approximately 800Gg of methane (CH4) and it is estimated that in the year 2.000 more or less 900Gg will be emitted. From this total there are not any identified initiative of energy recovery ongoing well succeeded. The majority of biogas emitted by wastes comes from solid waste degradation. To promote the biogas recovery in municipal solid waste disposal sites (MSWDS) it is necessary, first of all, to promote the correct solid waste disposal. It should also that the correct landfill management includes the recovery of the generated biogas. Reminding that this activity, in most of the cases, is duty of the public sector, should be included to the process the guaranteed continuity of the activity from an administration to the next. About 11% of the methane generated by anaerobic degradation of wastes come from industrial wastewater. The anaerobic process has energy intensity much lower than the conventional process. To an industry chose the anaerobic technology, is should have an efficient control of industrial process avoiding the effluent contamination by substances toxic to the anaerobic organisms. The private initiative, facing an opportunity of profitable business, naturally creates replicable initiatives. Internationally, there are several countries developing projects of biogas recovery. In Brazil are identified vestiges of this activity, occurred in the 1.970´s and 1.980´s. The contraction of the national economy, the decrease of international fossil fuel prices and the lack of environmental and tax incentives can be responsible for the end of such projects. Today, the possibility of obtaining economic gains for greenhouse gases emission reductions incentives through CER associated to environmental and fiscal incentives can create favorable expectations for this activity.

Thesis (M.Sc.Eng.) PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / Electrodynamic Shields (EDS) have been targeted as a technology to help mitigate degradation of power output caused by dust deposition on various solar collectors. Though printed circuit board based EDS prototypes have shown promising dust removal efficiencies, an inexpensive method of transparent EDS fabrication must be realized before the EDS technology is adopted by the solar industry. Development of a screen-printing process is presented as a scalable, low-cost method of EDS fabrication. The process is established using a silver-based ink on borosilicate glass substrates and then adapted to incorporate transparent conductive PEDOT:PSS and ITO nanoparticle solutions. Successful EDS prototypes are characterized and integrated with photovoltaic cells and second surface mirrored substrates. Removal efficiencies of the screen-printed EDS are tested by measuring the restoration in specular reflection and transmission in integrated EDS-mirror and EDSPV modules after dust depositions. Finally, a cost analysis of the EDS screen-printing process is performed in order to predict the economic viability of the EDS technology when used in conjunction with solar collecting technologies. / 2031-01-01

A constituição de sistemas híbridos como alternativa ao fornecimento de energia da concessionária, gerando energia própria e operando de forma isolada ou interconectada ao sistema de distribuição, tem originado estudos e implementações em nível industrial, comercial e mais recentemente residencial. A principal discussão que surge são as análises das vantagens técnicas e econômicas pela opção desse tipo de instalação. Neste trabalho, é apresentado um estudo complementar às pesquisas realizadas, onde é projetado um sistema híbrido contendo aerogeradores, painéis fotovoltaicos, processo de eletrólise, célula a combustível, microturbina a gás e geradores diesel. Esse sistema é simulado e comparado técnica e economicamente a um sistema que contém apenas geradores diesel. O sistema híbrido proposto possui uma microrrede conectada a um típico sistema de distribuição mas com um limite de demanda contratada que impede a satisfação de todas as necessidades energéticas da instalação apenas com a energia da concessionária. Procura-se avaliar os impactos técnicos e econômicos do atendimento da demanda por eletricidade através deste sistema híbrido além de executar-se a otimização, via PSO, do dimensionamento deste sistema, que utiliza uma ordem de despacho para gerenciar as mini unidades geradoras de energia. Foi utilizado o software TRNSYS devido a sua característica de permitir estimar a potência e energia produzidas no intervalo de um ano com detalhamento horário de cada recurso, considerando estimativas reais e localizadas para a disponibilidade dos recursos eólicos e fotovoltaicos. / The designing of hybrid systems as an alternative to power supply from power utility, generating their own energy in operating islanded or grid-tie to the power utility, has resulted in studies and implementations in industrial, commercial and residential level recently. The main discussion that arises is the analysis of the technical and economical advantages for this type of solution. This work presents a complementary study to the researches conducted nowadays, which is designed a hybrid system containing wind turbines, photovoltaic panels, electrolysis process, fuel cell, gas micro turbine and diesel generators. This system was simulated and was compared technically and economically to a system with only diesel gensets. The proposed hybrid system has a microrrede connected to a typical distribution system with a limited power demand value that prevents the satisfaction of all energy needs of the installation only with the utility power. This study evaluates the technical and economical impacts to meeting electric power consumption through this hybrid system and optimize using PSO, the design of this system that uses a dispatch order to manage the mini power generation units. The TRNSYS software was used due to its feature of allowing estimate the electric power and electric energy produced in one year apart with hourly details of each feature, considering actual estimates and localized availability of wind and photovoltaic resources.

O modelo cascata, desenvolvido por consultores europeus e não difundido no Brasil, é formado por matrizes onde as colunas descrevem as tecnologias e as linhas as fontes de energia, e representa um completo balanço energético incluindo as tecnologias utilizadas na produção, extração, conversão, transporte e uso final. A avaliação quantitativa dos impactos e dos custos envolvidos é feita por intermédio de coeficientes de impactos e de custos, ou seja, cada matriz do balanço energético é multiplicada por sua correspondente matriz de coeficientes de impactos e de custos. O modelo, devido a sua construção, permite ainda simular cenários prospectivos a partir de informações obtidas em planos ou programas oficiais. Um levantamento histórico do planejamento energético no Brasil e dos modelos de energia utilizados em planejamento energético ajudaram a verificar a necessidade e a compreender melhor a concepção de instrumentos que auxiliem na tomada de decisão no setor energético brasileiro. Um estudo de caso, para o estado de São Paulo em 1991, utilizando a canade- açúcar como energético, foi elaborado a fim de ilustrar a utilidade do modelo cascata. A partir dos valores obtidos no balanço energético, foram elaborados três cenários prospectivos, que fornecem subsídios para a análise do futuro do setor sucro-alcooleiro. / The cascade model was developed by European consultants but it has not been available in Brazil. It is formed by matrices where columns represent types of technology and the rows represent types of energy. The resulting cascade of matrices represents a complete energy balance including all types of technology applied in the chain of extraction, conversion and use. The quantitative assessment of impacts and costs is made by the impacts and costs coefficients. For this purpose each of the energy balance matrices has to be multiplied by a corresponding matrix of impact and cost coefficients. The cascade model allows us to simulate scenarios with information obtained from official plans or programs. A historical survey of energy plan in Brazil, and of energy models, aid to check and to understand better the creation of tools that help decision makers and planning authorities in the Brazilian energy sector. A case study, for São Paulo State in 1991, using sugar cane as a type of energy, was made in order to show the utility of the cascade model. From the values obtained in the energy balance three scenarios were developed that provide assistance for the analysis of the future of the alcohol sector.

abstract: With the increasing penetration of converter interfaced renewable generation into power systems, the structure and behavior of the power system is changing, catalyzing alterations and enhancements in modeling and simulation methods. This work puts forth a Hybrid Electromagnetic Transient-Transient Stability simulation method implemented using MATLAB and Simulink, to study power electronic based power systems. Hybrid Simulation enables detailed, accurate modeling, along with fast, efficient simulation, on account of the Electromagnetic Transient (EMT) and Transient Stability (TS) simulations respectively. A critical component of hybrid simulation is the interaction between the EMT and TS simulators, established through a well-defined interface technique, which has been explored in detail. This research focuses on the boundary conditions and interaction between the two simulation models for optimum accuracy and computational efficiency. A case study has been carried out employing the proposed hybrid simulation method. The test case used is the IEEE 9-bus system, modified to integrate it with a solar PV plant. The validation of the hybrid model with the benchmark full EMT model, along with the analysis of the accuracy and efficiency, has been performed. The steady-state and transient analysis results demonstrate that the performance of the hybrid simulation method is competent. The hybrid simulation technique suitably captures accuracy of EMT simulation and efficiency of TS simulation, therefore adequately representing the behavior of power systems with high penetration of converter interfaced generation. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2018

abstract: Ethylene vinyl acetate (EVA) is the most commonly used encapsulant in photovoltaic modules. However, EVA degrades over time and causes performance losses in PV system. Therefore, EVA degradation is a matter of concern from a durability point of view. This work compares EVA encapsulant degradation in glass/backsheet and glass/glass field-aged PV modules. EVA was extracted from three field-aged modules (two glass/backsheet and one glass/glass modules) from three different manufacturers from various regions (cell edges, cell centers, and non-cell region) from each module based on their visual and UV Fluorescence images. Characterization techniques such as I-V measurements, Colorimetry, Different Scanning Calorimetry, Thermogravimetric Analysis, Raman spectroscopy, and Fourier Transform Infrared Spectroscopy were performed on EVA samples. The intensity of EVA discoloration was quantified using colorimetric measurements. Module performance parameters like Isc and Pmax degradation rates were calculated from I-V measurements. Properties such as degree of crystallinity, vinyl acetate content and degree of crosslinking were calculated from DSC, TGA, and Raman measurements, respectively. Polyenes responsible for EVA browning were identified in FTIR spectra. The results from the characterization techniques confirmed that when EVA undergoes degradation, crosslinking in EVA increases beyond 90% causing a decrease in the degree of crystallinity and an increase in vinyl acetate content of EVA. Presence of polyenes in FTIR spectra of degraded EVA confirmed the occurrence of Norrish II reaction. However, photobleaching occurred in glass/backsheet modules due to the breathable backsheet whereas no photobleaching occurred in glass/glass modules because they were hermetically sealed. Hence, the yellowness index along with the Isc and Pmax degradation rates of EVA in glass/glass module is higher than that in glass/backsheet modules. The results implied that more acetic acid was produced in the non-cell region due to its double layer of EVA compared to the front EVA from cell region. But, since glass/glass module is hermetically sealed, acetic acid gets entrapped inside the module further accelerating EVA degradation whereas it diffuses out through backsheet in glass/backsheet modules. Hence, it can be said that EVA might be a good encapsulant for glass/backsheet modules, but the same cannot be said for glass/glass modules. / Dissertation/Thesis / Masters Thesis Chemical Engineering 2018

As estatísticas de produção e consumo de lenha e carvão vegetal existentes para o Brasil apresentam diferenças significativas entre si. Como não estão disponíveis os métodos utilizados, o que permitiria identificar os critérios utilizados, foram desenvolvidos métodos para estimar o consumo de lenha e carvão vegetal e elaborado um balanço oferta-demanda de madeira. Os métodos foram elaborados buscando simplicidade, robustez e disponibilidade de informações. Os métodos foram testados para o período 1996 - 2005 e comparados com os dados do Balanço Energético Nacional - BEN, elaborado pelo Ministério das Minas e Energia - MME. Os resultados mostram pequenas diferenças para o consumo total de lenha e carvão vegetal. Por outro lado, existem diferenças significativas no consumo setorial. Em 2005, quando comparado com o BEN, o consumo calculado de lenha no setor residencial é a metade, no setor agropecuário é o triplo, no setor de serviços e na industria é 26,5% e 14,6% menor, respectivamente. O consumo de carvão vegetal cai nos setores residencial e de serviços, 62,9% e 82,7%, respectivamente e cresce 10,0% e 812,3% nos setores industrial e agropecuário, respectivamente. No diagnóstico realizado sobre o uso de lenha e carvão vegetal no Brasil, foram identificadas regiões suscetíveis a problemas de oferta e que deverão ser alvo de estudos aprofundados para não comprometer a quantidade de madeira disponível de forma sustentável. O balanço é o resultado da diferença entre a oferta e a produção de madeira em nível municipal, que corresponde à menor unidade espacial com informação disponível para o Brasil. As regiões mais críticas no que se refere à produção de madeira para fins energéticos encontram-se nos Estados de Mato Grosso do Sul, Minas Gerais e Bahia. É importante destacar que mesmo municípios com balanços positivos podem apresentar situações de déficit devido à exploração excessiva e pontual de madeira. / Fuelwood and charcoal statistics for Brazil present important differences between them. Once the methods used to estimate production and consumption of these woodfuels are not available, which would allow to identify the used criteria, methods were developed to estimate the fuelwood and charcoal consumption and it was also elaborated a supply-demand balance of woodfuels. The methods were prepared seeking simplicity, robustness and availability of information. The methods were tested for the 1996 - 2005 period and compared with data from Brazilian Energy Balance (BEB), produced by Mines and Energy Ministry. The results show little differences for total fuelwood and charcoal consumption. On the other hand, there are expressive differences in sector consumption. In 2005, the fuelwood consumption in residential sector estimated by this study is half of Brazilian Energy Balance data. In agriculture is triple and in services sector and industry is 26.5% and 14.6% less than BEB data, respectively. The charcoal consumption decreases in residential and services sectors in 62.9% and 82.7%, respectively and grows 10.0% and 812.3% in industrial and agriculture, respectively. In the spatial assessment of fuelwood and charcoal use in Brazil, hotspots were identified concerning supply problems, which should be studied in order not to endanger the availability of woodfuels. The balance is the difference between supply and demand of woodfuel in the municipal level, which corresponds to the minimum administrative unit with available information for Brazil. The more critical woodfuels production hotspots are located in Mato Grosso do Sul, Minas Gerais and Bahia States. It is important to highlight that even municipal districts with positive balances may present fuelwood deficits due to an excessive and punctual wood exploitation.

O modelo cascata, desenvolvido por consultores europeus e não difundido no Brasil, é formado por matrizes onde as colunas descrevem as tecnologias e as linhas as fontes de energia, e representa um completo balanço energético incluindo as tecnologias utilizadas na produção, extração, conversão, transporte e uso final. A avaliação quantitativa dos impactos e dos custos envolvidos é feita por intermédio de coeficientes de impactos e de custos, ou seja, cada matriz do balanço energético é multiplicada por sua correspondente matriz de coeficientes de impactos e de custos. O modelo, devido a sua construção, permite ainda simular cenários prospectivos a partir de informações obtidas em planos ou programas oficiais. Um levantamento histórico do planejamento energético no Brasil e dos modelos de energia utilizados em planejamento energético ajudaram a verificar a necessidade e a compreender melhor a concepção de instrumentos que auxiliem na tomada de decisão no setor energético brasileiro. Um estudo de caso, para o estado de São Paulo em 1991, utilizando a canade- açúcar como energético, foi elaborado a fim de ilustrar a utilidade do modelo cascata. A partir dos valores obtidos no balanço energético, foram elaborados três cenários prospectivos, que fornecem subsídios para a análise do futuro do setor sucro-alcooleiro. / The cascade model was developed by European consultants but it has not been available in Brazil. It is formed by matrices where columns represent types of technology and the rows represent types of energy. The resulting cascade of matrices represents a complete energy balance including all types of technology applied in the chain of extraction, conversion and use. The quantitative assessment of impacts and costs is made by the impacts and costs coefficients. For this purpose each of the energy balance matrices has to be multiplied by a corresponding matrix of impact and cost coefficients. The cascade model allows us to simulate scenarios with information obtained from official plans or programs. A historical survey of energy plan in Brazil, and of energy models, aid to check and to understand better the creation of tools that help decision makers and planning authorities in the Brazilian energy sector. A case study, for São Paulo State in 1991, using sugar cane as a type of energy, was made in order to show the utility of the cascade model. From the values obtained in the energy balance three scenarios were developed that provide assistance for the analysis of the future of the alcohol sector.

The goal of this research was to quantify the degradation experienced by a polymer electrolyte fuel cell after storage at subzero temperatures ranging from 0 to -40°C. The performance loss was determined by comparing the polarization and other applicable power curves before and after the subzero storage cycle. The causes of this performance degradation were investigated by the use of Scanning Electron Microscope, Energy Dispersive x-ray Spectroscopy, and porosity scanning technologies. It was found that there are two distinct types of degradation experienced by the membrane. The first type was identified as a variance of the actual voltage - current relationship of the cell. The membrane experienced a 2 - 15% power reduction depending on the load applied to the cell. This mode of degradation only pertained to the initial freeze/thaw cycle and was not observed after any number of subsequent cycles. The cause of this type of degradation has been hypothesized to be related to the delamination of the proton exchange, gas diffusion, and micro porous layers. The second type of degradation was only observed during the subsequent cycles, and mainly affected the high power regions of the operating range. A 5% reduction in current density and power output was observed as a result of further freeze/thaw cycles. Mass transport limitations may have been caused by the destruction of the meso-porous gas diffusion and micro-porous layers. The pore size, volume, and membrane surface area were quantified using a B.E.T. porosity scanner. The results showed that the pore diameter of the catalyst and proton exchange layer did not increase significantly. The porosity scanner did indicate that a pore volume increased by a factor of ten and was confirmed by the surface area measurements of the membrane. The S.E.M. investigations allowed visual inspection of the membrane's structural integrity. Physical separation of the catalyst and gas diffusion layers was observed in the experimental sample, while a more homogeneous assembly was seen in the control sample.