Thesis (M.S.)--Ohio University, November, 1998. / Title from PDF t.p.

Este trabalho trata da avaliação dos impactos que os múltiplos usos da água causam à operação dos reservatórios de uma bacia hidrográfica para a geração de energia elétrica. Apresenta-se o equacionamento do modelo HIDRO, desenvolvido em linguagem GAMS para tratamento de problemas de otimização em Programação Não Linear, cuja função objetivo inclui variáveis relacionadas não somente à geração de energia, como também ao fornecimento de água aos diversos usos do recurso hídrico tratados no problema. A aplicação do modelo é feita para a bacia do rio São Francisco, localizada entre as regiões Sudeste e Nordeste do Brasil, que conta com uma capacidade instalada de 10,7 GW em suas usinas hidrelétricas, as quais também realizam operações de controle de cheia. A região apresenta um expressivo uso consuntivo do recurso hídrico, principalmente voltado à irrigação de culturas, além de abastecimento humano e criação animal. Dentre os usos não consuntivos, têm-se a navegação e a conservação ambiental. Uma vez que grande parte da bacia é marcada por escassez hídrica, a operação de seu sistema de reservatórios vem sendo questionada no que se refere ao gerenciamento dos recursos hídricos. São avaliados os índices de atendimento da demanda de energia e da demanda hídrica para cenários de baixa afluência aos reservatórios. As relações de troca entre energia, uso consuntivo e conservação ambiental são avaliadas, levando-se em conta, também, os efeitos decorrentes da transposição das águas do São Francisco para o Nordeste Setentrional. As perdas na geração de energia decorrentes do aumento da demanda hídrica e do aumento da demanda ambiental são avaliadas. São estimados os custos relacionados às perdas na geração de energia se as demandas consuntivas atingirem o valor outorgado na bacia pelo Poder Público, valor este que não consegue ser plenamente atendido. O modelo proposto pode ser aplicado a quaisquer bacias hidrográficas com múltiplos usos do recurso hídrico. / This research presents a study conducted to evaluate the impacts of the hydroelectric power plants operation caused by the multipurpose uses of water resources. There are many conflicts involved in the operation of a reservoir system mainly due to competitive uses of water. That is the case of São Francisco River, located between the Southeast and Northeast regions of Brazil. The hydro system in this region has an installed capacity of 10.7 GW and supports 13% of the Brazilian hydro electrical power. Due to the scarcity of water in this region, the operation of this system has been questioned in the last few years. The competitive uses of water in this region are water supply, irrigation and animal raising. The non-consumptive uses of water are navigation and environmental protection. The electrical sector is planning to review the reservoir operation rules in order to attend these demands. The study was conducted by applying the HIDRO model, which is an optimization PNL model developed with GAMS software that maximizes hydropower production. A new objective function was added to the HIDRO model in order to consider the treatment of energy and water demands the both. The trade-offs among energy, consumptive uses and environment protection are presented. The lack of energy due the increasing water demand implies costs which are evaluated according to some demand scenarios and different scarcity historical periods. Also the effect due the operation of the water transfer system from São Francisco to the neighboring basins is considered.

Este trabalho trata da avaliação dos impactos que os múltiplos usos da água causam à operação dos reservatórios de uma bacia hidrográfica para a geração de energia elétrica. Apresenta-se o equacionamento do modelo HIDRO, desenvolvido em linguagem GAMS para tratamento de problemas de otimização em Programação Não Linear, cuja função objetivo inclui variáveis relacionadas não somente à geração de energia, como também ao fornecimento de água aos diversos usos do recurso hídrico tratados no problema. A aplicação do modelo é feita para a bacia do rio São Francisco, localizada entre as regiões Sudeste e Nordeste do Brasil, que conta com uma capacidade instalada de 10,7 GW em suas usinas hidrelétricas, as quais também realizam operações de controle de cheia. A região apresenta um expressivo uso consuntivo do recurso hídrico, principalmente voltado à irrigação de culturas, além de abastecimento humano e criação animal. Dentre os usos não consuntivos, têm-se a navegação e a conservação ambiental. Uma vez que grande parte da bacia é marcada por escassez hídrica, a operação de seu sistema de reservatórios vem sendo questionada no que se refere ao gerenciamento dos recursos hídricos. São avaliados os índices de atendimento da demanda de energia e da demanda hídrica para cenários de baixa afluência aos reservatórios. As relações de troca entre energia, uso consuntivo e conservação ambiental são avaliadas, levando-se em conta, também, os efeitos decorrentes da transposição das águas do São Francisco para o Nordeste Setentrional. As perdas na geração de energia decorrentes do aumento da demanda hídrica e do aumento da demanda ambiental são avaliadas. São estimados os custos relacionados às perdas na geração de energia se as demandas consuntivas atingirem o valor outorgado na bacia pelo Poder Público, valor este que não consegue ser plenamente atendido. O modelo proposto pode ser aplicado a quaisquer bacias hidrográficas com múltiplos usos do recurso hídrico. / This research presents a study conducted to evaluate the impacts of the hydroelectric power plants operation caused by the multipurpose uses of water resources. There are many conflicts involved in the operation of a reservoir system mainly due to competitive uses of water. That is the case of São Francisco River, located between the Southeast and Northeast regions of Brazil. The hydro system in this region has an installed capacity of 10.7 GW and supports 13% of the Brazilian hydro electrical power. Due to the scarcity of water in this region, the operation of this system has been questioned in the last few years. The competitive uses of water in this region are water supply, irrigation and animal raising. The non-consumptive uses of water are navigation and environmental protection. The electrical sector is planning to review the reservoir operation rules in order to attend these demands. The study was conducted by applying the HIDRO model, which is an optimization PNL model developed with GAMS software that maximizes hydropower production. A new objective function was added to the HIDRO model in order to consider the treatment of energy and water demands the both. The trade-offs among energy, consumptive uses and environment protection are presented. The lack of energy due the increasing water demand implies costs which are evaluated according to some demand scenarios and different scarcity historical periods. Also the effect due the operation of the water transfer system from São Francisco to the neighboring basins is considered.

Nas últimas décadas, sistemas de suprimento de energia que utilizam recursos renováveis têm sido estudados e empregados como opção para o fornecimento de energia elétrica. Devido aos avanços da tecnologia fotovoltaica, associada à diminuição de custos e maior conhecimento de seu desempenho, os sistemas fotovoltaicos apresentam-se como uma opção tecnicamente promissora. Neste contexto, a energia solar fotovoltaica, que, além de gerar eletricidade de forma distribuída também vem ganhando cada vez mais espaço no mercado mundial. Esta tecnologia evita as emissões de gases poluentes e é uma fonte alternativa que diversifica a matriz energética. Para complemento da energia hidrelétrica é necessária uma fonte energética com várias características ecologicamente corretas, a energia solar fotovoltaica é uma dessas fontes, pois é limpa (não poluente), inesgotável, silenciosa, estática, distributiva, simples em sua operação, possui características modulares podendo-se integrar as edificações. Para viabilizar sua implantação nas edificações, vários países, inclusive o Brasil, também buscam soluções para o futuro, elaborando estudos para avaliar a eficácia dessa tecnologia. Adicionalmente, como a energia é cada vez mais necessária para o desenvolvimento humano, utilizar a fonte de geração próxima ao ponto de consumo é uma maneira eficaz de reduzir as perdas por transmissão e distribuição. Esta dissertação tem por objetivo apresentar os conceitos, aspectos e aplicações das células solares de filmes finos na inserção como gerador fotovoltaico de energia elétrica integrada a estrutura das edificações. O foco principal do tema da dissertação é o estudo de área disponível na edificação, estimando o potencial fotovoltaico de geração existente no envoltório. Através desta análise, pode-se quantificar a contribuição energética de uma unidade geradora fotovoltaica para a redução de consumo energético na rede em que a edificação estiver conectada. / In recent decades, energy supply systems that use renewable resources have been studied and used as an option for the supply of electricity. Due to advances in photovoltaic technology, coupled with lower costs and greater knowledge of its performance, photovoltaic systems are presented as an option technically promising. In this context, photovoltaic solar energy, this, besides generating electricity in distributed also gaining more and more space in the world market. This technology avoids the emissions of greenhouse gases and is an alternative source to diversify the energy matrix. To complement the hydropower energy supply is needed with various features eco-friendly, photovoltaic solar energy is one of those sources, because it is clean (clean) endless, silent, static, distributive, simple in its operation, has modular features can to integrate the buildings. To enable its deployment in buildings, several countries, including Brazil, also look for solutions for the future, preparing studies to evaluate the effectiveness of this technology. Additionally, energy is increasingly necessary for human development, using the power generation near the point of consumption is an effective way to reduce transmission and distribution losses. This paper aims to present the concepts, issues and applications of thin film solar cells in photovoltaic generator insertion as power integrated structure of buildings. The main focus of the dissertation topic is the study of the available area in the building, estimating the potential of photovoltaic generation in existing wrap. Through this analysis, one can quantify the energy contribution of a photovoltaic generating unit to reduce energy consumption in the network in which the building is connected.

Nas últimas décadas, sistemas de suprimento de energia que utilizam recursos renováveis têm sido estudados e empregados como opção para o fornecimento de energia elétrica. Devido aos avanços da tecnologia fotovoltaica, associada à diminuição de custos e maior conhecimento de seu desempenho, os sistemas fotovoltaicos apresentam-se como uma opção tecnicamente promissora. Neste contexto, a energia solar fotovoltaica, que, além de gerar eletricidade de forma distribuída também vem ganhando cada vez mais espaço no mercado mundial. Esta tecnologia evita as emissões de gases poluentes e é uma fonte alternativa que diversifica a matriz energética. Para complemento da energia hidrelétrica é necessária uma fonte energética com várias características ecologicamente corretas, a energia solar fotovoltaica é uma dessas fontes, pois é limpa (não poluente), inesgotável, silenciosa, estática, distributiva, simples em sua operação, possui características modulares podendo-se integrar as edificações. Para viabilizar sua implantação nas edificações, vários países, inclusive o Brasil, também buscam soluções para o futuro, elaborando estudos para avaliar a eficácia dessa tecnologia. Adicionalmente, como a energia é cada vez mais necessária para o desenvolvimento humano, utilizar a fonte de geração próxima ao ponto de consumo é uma maneira eficaz de reduzir as perdas por transmissão e distribuição. Esta dissertação tem por objetivo apresentar os conceitos, aspectos e aplicações das células solares de filmes finos na inserção como gerador fotovoltaico de energia elétrica integrada a estrutura das edificações. O foco principal do tema da dissertação é o estudo de área disponível na edificação, estimando o potencial fotovoltaico de geração existente no envoltório. Através desta análise, pode-se quantificar a contribuição energética de uma unidade geradora fotovoltaica para a redução de consumo energético na rede em que a edificação estiver conectada. / In recent decades, energy supply systems that use renewable resources have been studied and used as an option for the supply of electricity. Due to advances in photovoltaic technology, coupled with lower costs and greater knowledge of its performance, photovoltaic systems are presented as an option technically promising. In this context, photovoltaic solar energy, this, besides generating electricity in distributed also gaining more and more space in the world market. This technology avoids the emissions of greenhouse gases and is an alternative source to diversify the energy matrix. To complement the hydropower energy supply is needed with various features eco-friendly, photovoltaic solar energy is one of those sources, because it is clean (clean) endless, silent, static, distributive, simple in its operation, has modular features can to integrate the buildings. To enable its deployment in buildings, several countries, including Brazil, also look for solutions for the future, preparing studies to evaluate the effectiveness of this technology. Additionally, energy is increasingly necessary for human development, using the power generation near the point of consumption is an effective way to reduce transmission and distribution losses. This paper aims to present the concepts, issues and applications of thin film solar cells in photovoltaic generator insertion as power integrated structure of buildings. The main focus of the dissertation topic is the study of the available area in the building, estimating the potential of photovoltaic generation in existing wrap. Through this analysis, one can quantify the energy contribution of a photovoltaic generating unit to reduce energy consumption in the network in which the building is connected.

The greatest political, scientific, and engineering challenge of the 21st century is finding a viable solution to limit anthropogenic greenhouse gas emissions (CO2) to curb the effects of global climate change. All sectors of society need to contribute to alleviate this problem, but industrial operations must play a significant leadership role. Some of these industries include: metallurgy, cement, power, agriculture and forestry. In particular, the iron/steel, cement, and power generation industries use coal on account of its high energy density among solid fuels. Coal combustion yields 720 tonne CO2/GWh, and produces fine particulates, sulphur and nitrous oxides, along with excess CO2 contributing to climate change. In comparison, biomass (such as agricultural and forestry residues) has a solid fuel rating of 25-100 tonne CO2/GWh; therefore, biomass fuels are considered more sustainable since the living biomass consumed CO2 in the early part of its life cycle. However, biomass has significant industrial shortcomings for its use as fuel at large scale, including low energy content, density, and hydrophobicity relative to coal. In short, biomass fuels cannot be substituted without major infrastructure changes which add economic penalties that industry is currently unwilling to absorb. Biomass upgrading routes were considered in this thesis. These include densification, torrefaction, and integrated torrefaction and densification (ITD). The first half of the methodology involved converting woody biomass (willow residue and poplar bark), agricultural residue (switchgrass plants), and pulp mill waste via a single pellet/briquette press at different densification temperatures and pressures. The second half of the methodology involved product characterization of each batch of pellets and briquettes. In this work, pellets and briquettes were tested for physical characteristics (density and durability), chemical differences (energy content and hydrophobicity), and transport phenomena characteristics (drying profiles). First, results showed that extrusion of torrefied biomass at 300°C with an estimated pressure of 10 MPa creates partially formed pellets from agricultural residues. Using the concept of ITD (temperature range 220-325°C and pressure range 40 and 215 MPa), the density was found to be 1000-1250 kg/m3 for pellets and briquettes. The degree of compression from the loose biomass was on the order of 3-10 which corresponds with theoretical expectations. Material density increased with increasing pressure. The solid yield of pellets and briquettes decreased with increasing temperature, and results aligned with micro-scale thermogravimetric analysis. The larger ITD briquettes (produced at T = 325°C, P = 40 MPa) were evaluated for calorific value and found to fall in the lignite classification (O/C < 0.4 and H/C < 1.2) on a van Krevelen diagram. The resulting ITD pellets and briquettes were found to have a durability similar to commercial materials (durability > 97%), and to be more hydrophobic (8 wt% moisture absorption compared to 35 wt%). The drying time of ITD materials was faster than commercial torrefied briquettes, with an effective diffusivity of 1.5×10-6 m2/s compared to 7.3×10-9 m2/s likely because of a smaller pore volume in ITD briquettes. Further pilot scale studies would help improve the ITD methodology and make the process more appealing for the replacement of coal fuels.

The focus of this thesis is to explore a new mechanism to give added incentive to invest in new capacities in deregulated electricity markets. There is a lot of concern in energy markets, regarding lack of sufficient private sector investment in new capacities to generate electricity. Although some markets are using mechanisms to reward these investments directly, e.g., by governmental subsidies for renewable sources such as wind or solar, there is not much theory to guide the process of setting the reward levels. The proposed mechanism involves a long term planning model, maximizing the social welfare measured as consumers’ plus producers’ surplus, by choosing new generation capacities which, along with still existing capacities, can meet demand. Much previous research in electricity capacity planning has also solved optimization models, usually with continuous variables only, in linear or non-linear programs. However, these approaches can be misleading when capacity additions must either be zero or a large size, e.g., the building of a nuclear reactor or a large wind farm. Therefore, this research includes binary variables for the building of large new facilities in the optimization problem, i.e. the model becomes a mixed integer linear or nonlinear program. It is well known that, when binary variables are included in such a model, the resulting commodity prices may give insufficient incentive for private investment in the optimal new capacities. The new mechanism is intended to overcome this difficulty with a capacity price in addition to the commodity price: an auxiliary mathematical program calculates the minimum capacity price that is necessary to ensure that all firms investing in new capacities are satisfied with their profit levels. In order to test the applicability of this approach, the result of the suggested model is compared with the Ontario Integrated Power System Plan (IPSP), which recommends new generation capacities, based on historical data and costs of different sources of electricity generation for the next 20 years given a fixed forecast of demand.

The focus of this thesis is to explore a new mechanism to give added incentive to invest in new capacities in deregulated electricity markets. There is a lot of concern in energy markets, regarding lack of sufficient private sector investment in new capacities to generate electricity. Although some markets are using mechanisms to reward these investments directly, e.g., by governmental subsidies for renewable sources such as wind or solar, there is not much theory to guide the process of setting the reward levels. The proposed mechanism involves a long term planning model, maximizing the social welfare measured as consumers’ plus producers’ surplus, by choosing new generation capacities which, along with still existing capacities, can meet demand. Much previous research in electricity capacity planning has also solved optimization models, usually with continuous variables only, in linear or non-linear programs. However, these approaches can be misleading when capacity additions must either be zero or a large size, e.g., the building of a nuclear reactor or a large wind farm. Therefore, this research includes binary variables for the building of large new facilities in the optimization problem, i.e. the model becomes a mixed integer linear or nonlinear program. It is well known that, when binary variables are included in such a model, the resulting commodity prices may give insufficient incentive for private investment in the optimal new capacities. The new mechanism is intended to overcome this difficulty with a capacity price in addition to the commodity price: an auxiliary mathematical program calculates the minimum capacity price that is necessary to ensure that all firms investing in new capacities are satisfied with their profit levels. In order to test the applicability of this approach, the result of the suggested model is compared with the Ontario Integrated Power System Plan (IPSP), which recommends new generation capacities, based on historical data and costs of different sources of electricity generation for the next 20 years given a fixed forecast of demand.

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