Energia eólica em alto mar: distribuição dos recursos e complementaridade hídrica

The stabilization of energy supply in Brazil has been a challenge for the operation of the National Interconnected System in face of hydrological and climatic variations. Thermoelectric plants have been used as an emergency source for periods of water scarcity. The utilization of fossil fuels, however, has elevated the cost of electricity. On the other hand, offshore wind energy has gained importance in the international context and is competitive enough to become a possibility for future generation in Brazil. In this scenario, the main goal of this thesis was to investigate the magnitude and distribution of offshore wind resources, and also verify the possibilities of complementing hydropower. A data series of precipitation from the Climatic Research Unit (CRU) Blended Sea Winds from the National Climatic Data Center (NCDC/NOAA) were used. According to statistical criteria, three types of complementarity were found in the Brazilian territory: hydro × hydro, wind × wind and hydro × wind. It was noted a significant complementarity between wind and hydro resources (r = -0.65), mainly for the hydrographical basins of the southeast and central regions with Northeastern Brazil winds. To refine the extrapolation of winds over the ocean, a method based on the Monin-Obukhov theory was used to model the stability of the atmospheric boundary layer. Objectively Analyzed Air-Sea Flux (OAFLUX) datasets for heat flux, temperature and humidity, and also sea level pressure data from NCEP/NCAR were used. The ETOPO1 from the National Geophysical Data Center (NGDC/NOAA) provided bathymetric data. It was found that shallow waters, between 0-20 meters, have a resource estimated at 559 GW. The contribution of wind resources to hydroelectric reservoir operation was investigated with a simplified hybrid wind-hydraulic model, and reservoir level, inflow, outflow and turbine production data. It was found that the hybrid system avoids drought periods, continuously saving water from reservoirs through wind production. Therefore, from the results obtained, it is possible to state that the good winds from the Brazilian coast can, besides diversifying the electric matrix, stabilize the hydrological fluctuations avoiding rationing and blackouts, reducing the use of thermal power plants, increasing the production cost and emission of greenhouse gases. Public policies targeted to offshore wind energy will be necessary for its full development.

Contribuições para estratégia de controle aplicada à geração fotovoltaica interconectada à rede elétrica

Generation systems, using renewable sources, are becoming increasingly popular due to the need for increased use of electricity. Currently, renewables sources have a role to cooperate with conventional generation, due to the system limitation in delivering the required power, the need for reduction of unwanted effects from sources that use fossil fuels (pollution) and the difficulty of building new transmission and/or distribution lines. This cooperation takes place through distributed generation. Therefore, this work proposes a control strategy for the interconnection of a PV (Photovoltaic) system generation distributed with a three-phase power grid through a connection filter the type LCL. The compensation of power quality at point of common coupling (PCC) is performed ensuring that the mains supply or consume only active power and that his currents have low distorcion. Unlike traditional techniques which require schemes for harmonic detection, the technique performs the harmonic compensation without the use of this schemes, controlling the output currents of the system in an indirect way. So that there is effective control of the DC (Direct Current) bus voltage is used the robust controller mode dual DSMPI (Dual-Sliding Mode-Proportional Integral), that behaves as a sliding mode controller SM-PI (Sliding Mode-Proportional Integral) during the transition and like a conventional PI (Proportional Integral) in the steady-state. For control of current is used to repetitive control strategy, which are used double sequence controllers (DSC) tuned to the fundamental component, the fifth and seventh harmonic. The output phase current are aligned with the phase angle of the utility voltage vector obtained from the use of a SRF-PLL (Synchronous Reference Frame Phase-Locked-Loop). In order to obtain the maximum power from the PV array is used a MPPT (Maximum Power Point Tracking) algorithm without the need for adding sensors. Experimental results are presented to demonstrate the effectiveness of the proposed control system.

Avaliação de sustentabilidade ambiental do sistema de abastecimento de água e esgotamento sanitário de Uberaba - MG

This paper analyses the sustainability under the environmental (ecological) perspective of Water Supply and Sanitary Sewers Systems from Uberaba city, MG. It was accomplished in this analysis, An Environmental Sustainability Assessment of those systems, by the means of specific sustainability indicators proposed for Uberaba, but which may be used for other simi-lar cities. To the characterization of the systems, visitations were made to the main units as well as a documental was elaborated. The definition of the level or stage of the sustainability by the indicators was made based on a literature review, on interviews with the technicians and managers of the systems and based on the characterization and observation of the system reality, being attributed to them the following classification: Non Sustainable, Low Sustaina-bility, Medium Sustainability and High Sustainability. It was verified that the indicators that have lower compatibility to the process of sustainability to the studied systems are those rela-ted to the water physical losses, to the water per capita consumption, to the electricity con-sumption and to the sludge from the water treatment plants disposal untreated into a water body, for the Water Supply System. And those ones related to the attendance with sewage treatment, to the electricity consumption and to the usage of the treated sewage, for the Sani-tary Sewers, all of them classified as Non Sustainable.

Estudo do potencial de poupança energético associado a um parque informático distribuído

A crescente evolução da utilização das Tecnologias de Informação (TI), nomeadamente em instituições e empresas, faz com que exista um aumento no consumo da energia elétrica e elevados custos de manutenção associados. Com esta situação, existe cada vez mais a preocupação em arranjar formas/técnicas de baixar este consumo, isto é, a necessidade de gerir estes consumos de forma a que se consiga baixar a fatura energética. O presente trabalho tem como objetivo estudar possibilidades de eficiência energética associado a um parque informático distribuído, nomeadamente estudar o que pode ser feito para reduzir consumos num edifício escolar, utilizando como caso de estudo uma escola do Instituto Politécnico de Leiria. Esta dissertação apresenta diferentes propostas de modo a que se consigam reduzir os consumos energéticos, nomeadamente com a substituição de equipamentos por outros mais eficientes. Numa parte inicial, o trabalho abrange uma visão global sobre técnicas que têm vindo a ser desenvolvidas para melhorar a eficiência energética em sistemas computacionais. Efetuaram-se medições de consumos, tanto em equipamentos como em sala, durante um período experimental, de modo a obter conclusões sobre os valores obtidos com a substituição dos equipamentos existentes por equipamentos eficientes.

Consumo, cenários comunicacionais e subjetividades juvenis

Esta comunicação articula reflexões das pesquisas "Imagens limiares e visualidades juvenis: imagética do consumo", sediada na ESPM/SP, e “Imagens de presença e de ausência: sentidos midiáticos da subjetividade juvenil”, sediada na UFRN. O consumo é referência de uma epistemologia dos processos comunicacionais/midiáticos apoiada em investigações multimetodológicas. Buscam-se critérios para pensá-lo como sistema midiático com implicações em processos materiais e produtivos, e também como regime afetual, dinâmica estésica e estética de produção de sentido vinculado a dimensões simbólicas. São investigadas práticas de consumo dirigidas ao corpo e relevantes nos processos de subjetivação de jovens urbanos tanto pela reprodução de padrões como pela criação de novas formas de apropriação de bens simbólicos

Recomendações para o desenvolvimento de uma ferramenta de suporte às primeiras decisões projetuais visando ao desempenho energético de edificações de escritório em clima quente

PEDRINI, Aldomar; SZOKOLAY, Steven. Recomendações para o desenvolvimento de uma ferramenta de suporte às primeiras decisões projetuais visando ao desempenho energético de edificações de escritório em clima quente. Ambiente Construído, Porto Alegre, v. 5, n. 1, p.39-54, jan./mar. 2005. Trimestral. Disponível em: . Acesso em: 04 out. 2010.

Teoria de carteiras e a alocação de parques eólicos offshore

The consumption of energy on the planet is currently based on fossil fuels. They are responsible for adverse effects on the environment. Renewables propose solutions for this scenario, but must face issues related to the capacity of the power supply. Wind energy offshore emerging as a promising alternative. The speed and stability are greater winds over oceans, but the variability of these may cause inconvenience to the generation of electric power fluctuations. To reduce this, a combination of wind farms geographically distributed was proposed. The greater the distance between them, the lower the correlation between the wind velocity, increasing the likelihood that together achieve more stable power system with less fluctuations in power generation. The efficient use of production capacity of the wind park however, depends on their distribution in marine environments. The objective of this research was to analyze the optimal allocation of wind farms offshore on the east coast of the U.S. by Modern Portfolio Theory. The Modern Portfolio Theory was used so that the process of building portfolios of wind energy offshore contemplate the particularity of intermittency of wind, through calculations of return and risk of the production of wind farms. The research was conducted with 25.934 observations of energy produced by wind farms 11 hypothetical offshore, from the installation of 01 simulated ocean turbine with a capacity of 5 MW. The data show hourly time resolution and covers the period between January 1, 1998 until December 31, 2002. Through the Matlab R software, six were calculated minimum variance portfolios, each for a period of time distinct. Given the inequality of the variability of wind over time, set up four strategies rebalancing to evaluate the performance of the related portfolios, which enabled us to identify the most beneficial to the stability of the wind energy production offshore. The results showed that the production of wind energy for 1998, 1999, 2000 and 2001 should be considered by the portfolio weights calculated for the same periods, respectively. Energy data for 2002 should use the weights derived from the portfolio calculated in the previous time period. Finally, the production of wind energy in the period 1998-2002 should also be weighted by 1/11. It follows therefore that the portfolios found failed to show reduced levels of variability when compared to the individual production of wind farms hypothetical offshore

Análise energética a uma instalação produtiva de cerâmica de revestimento

O presente trabalho deriva do Projeto GALP 20–20-20 implementado na empresa Primus Vitória, em parceria com a Universidade de Aveiro. A empresa na qual foi efetuado o estágio produz azulejos para revestimento, estando situada na Zona Industrial de Taboeira. Este relatório expõe a caracterização energética da Primus Vitória, onde são apresentados consumos de energia elétrica e gás natural nos diversos sectores produtivos, relação entre consumos energéticos globais e a produção de azulejos e ainda os indicadores energéticos da mesma. Através deste estudo foi possível a criação de medidas de eficiência energética passíveis de implementação, aplicadas a equipamentos consumidores de energia elétrica, através da substituição do motor elétrico existente no setor da aspiração, e de gás natural, otimizando o funcionamento da plastificadora para sequencial, com o devido impacte no consumo final de energia. Como trabalho futuro propõe-se o desenvolvimento de um plano de monotorização de consumos energéticos com o intuito de obter um controle rigoroso dos mesmos reduzindo possíveis perdas e identificando possíveis defeitos no processo produtivo.

Consumo, cenários comunicacionais e subjetividades juvenis

Esta comunicação articula reflexões das pesquisas "Imagens limiares e visualidades juvenis: imagética do consumo", sediada na ESPM/SP, e “Imagens de presença e de ausência: sentidos midiáticos da subjetividade juvenil”, sediada na UFRN. O consumo é referência de uma epistemologia dos processos comunicacionais/midiáticos apoiada em investigações multimetodológicas. Buscam-se critérios para pensá-lo como sistema midiático com implicações em processos materiais e produtivos, e também como regime afetual, dinâmica estésica e estética de produção de sentido vinculado a dimensões simbólicas. São investigadas práticas de consumo dirigidas ao corpo e relevantes nos processos de subjetivação de jovens urbanos tanto pela reprodução de padrões como pela criação de novas formas de apropriação de bens simbólicos

Balanço energético da operação de uma caldeira a biomassa

A pressão causada sobre os recursos energéticos é impulsionada pela evolução demográfica e pelo crescimento económico, que se vem registando principalmente nos países em desenvolvimento. Segundo várias estatísticas, a procura pela energia incide principalmente sobre os combustíveis fósseis, os quais, representam cerca de do mix de consumo mundial de energia primária. A incerteza sobre as reservas das fontes energéticas não renováveis, e os problemas ambientais derivados da sua conversão noutros tipos de energia, levaram a uma implementação de medidas com rumo à sustentabilidade e eficiência energética. Desta forma, o aumento da utilização sobre as fontes energéticas renováveis é de extrema importância. A biomassa é uma das fontes energéticas de maior relevo. A utilização de biomassa em caldeiras, oferece benefícios económicos, sociais e ambientais, tais como poupança financeira no combustível, conservação dos recursos fósseis e redução de emissões poluentes. As caldeiras desenvolvidas por empresas como a Ventil, são uma solução para a produção de energia térmica pela combustão da biomassa. Estes sistemas caracterizam-se por serem energeticamente eficientes nas várias componentes da sua operação. Assim, pretende-se fazer uma caracterização dos consumos energéticos associados à operação de uma caldeira Ventil de, nomeadamente o consumo de energia elétrica de equipamentos associados. Também será considerado um balanço energético da caldeira e determinado o seu rendimento. Desta forma, concluiu-se que a potência do sistema é de MJ/s, apresentando um rendimento de. Foram detetados motores mal dimensionados e apresentadas alternativas de substituição. Com um investimento de seria possível reduzir a fatura energética em, obtendo um payback de anos. No entanto, a fatura energética do sistema ultrapassa os anuais, sendo que do investimento é na compra do combustível e os restantes são relativos ao consumo de energia elétrica.

Recomendações para o desenvolvimento de uma ferramenta de suporte às primeiras decisões projetuais visando ao desempenho energético de edificações de escritório em clima quente

PEDRINI, Aldomar; SZOKOLAY, Steven. Recomendações para o desenvolvimento de uma ferramenta de suporte às primeiras decisões projetuais visando ao desempenho energético de edificações de escritório em clima quente. Ambiente Construído, Porto Alegre, v. 5, n. 1, p.39-54, jan./mar. 2005. Trimestral. Disponível em: . Acesso em: 04 out. 2010.

Exergetic, energetic, economic and environmental evaluation of concentrated solar power plants in Libya

The PhD project addresses the potential of using concentrating solar power (CSP) plants as a viable alternative energy producing system in Libya. Exergetic, energetic, economic and environmental analyses are carried out for a particular type of CSP plants. The study, although it aims a particular type of CSP plant – 50 MW parabolic trough-CSP plant, it is sufficiently general to be applied to other configurations. The novelty of the study, in addition to modeling and analyzing the selected configuration, lies in the use of a state-of-the-art exergetic analysis combined with the Life Cycle Assessment (LCA). The modeling and simulation of the plant is carried out in chapter three and they are conducted into two parts, namely: power cycle and solar field. The computer model developed for the analysis of the plant is based on algebraic equations describing the power cycle and the solar field. The model was solved using the Engineering Equation Solver (EES) software; and is designed to define the properties at each state point of the plant and then, sequentially, to determine energy, efficiency and irreversibility for each component. The developed model has the potential of using in the preliminary design of CSPs and, in particular, for the configuration of the solar field based on existing commercial plants. Moreover, it has the ability of analyzing the energetic, economic and environmental feasibility of using CSPs in different regions of the world, which is illustrated for the Libyan region in this study. The overall feasibility scenario is completed through an hourly analysis on an annual basis in chapter Four. This analysis allows the comparison of different systems and, eventually, a particular selection, and it includes both the economic and energetic components using the “greenius” software. The analysis also examined the impact of project financing and incentives on the cost of energy. The main technological finding of this analysis is higher performance and lower levelized cost of electricity (LCE) for Libya as compared to Southern Europe (Spain). Therefore, Libya has the potential of becoming attractive for the establishment of CSPs in its territory and, in this way, to facilitate the target of several European initiatives that aim to import electricity generated by renewable sources from North African and Middle East countries. The analysis is presented a brief review of the current cost of energy and the potential of reducing the cost from parabolic trough- CSP plant. Exergetic and environmental life cycle assessment analyses are conducted for the selected plant in chapter Five; the objectives are 1) to assess the environmental impact and cost, in terms of exergy of the life cycle of the plant; 2) to find out the points of weakness in terms of irreversibility of the process; and 3) to verify whether solar power plants can reduce environmental impact and the cost of electricity generation by comparing them with fossil fuel plants, in particular, Natural Gas Combined Cycle (NGCC) plant and oil thermal power plant. The analysis also targets a thermoeconomic analysis using the specific exergy costing (SPECO) method to evaluate the level of the cost caused by exergy destruction. The main technological findings are that the most important contribution impact lies with the solar field, which reports a value of 79%; and the materials with the vi highest impact are: steel (47%), molten salt (25%) and synthetic oil (21%). The “Human Health” damage category presents the highest impact (69%) followed by the “Resource” damage category (24%). In addition, the highest exergy demand is linked to the steel (47%); and there is a considerable exergetic demand related to the molten salt and synthetic oil with values of 25% and 19%, respectively. Finally, in the comparison with fossil fuel power plants (NGCC and Oil), the CSP plant presents the lowest environmental impact, while the worst environmental performance is reported to the oil power plant followed by NGCC plant. The solar field presents the largest value of cost rate, where the boiler is a component with the highest cost rate among the power cycle components. The thermal storage allows the CSP plants to overcome solar irradiation transients, to respond to electricity demand independent of weather conditions, and to extend electricity production beyond the availability of daylight. Numerical analysis of the thermal transient response of a thermocline storage tank is carried out for the charging phase. The system of equations describing the numerical model is solved by using time-implicit and space-backward finite differences and which encoded within the Matlab environment. The analysis presented the following findings: the predictions agree well with the experiments for the time evolution of the thermocline region, particularly for the regions away from the top-inlet. The deviations observed in the near-region of the inlet are most likely due to the high-level of turbulence in this region due to the localized level of mixing resulting; a simple analytical model to take into consideration this increased turbulence level was developed and it leads to some improvement of the predictions; this approach requires practically no additional computational effort and it relates the effective thermal diffusivity to the mean effective velocity of the fluid at each particular height of the system. Altogether the study indicates that the selected parabolic trough-CSP plant has the edge over alternative competing technologies for locations where DNI is high and where land usage is not an issue, such as the shoreline of Libya.

Minimizar o sobrecusto da redução da capacidade de interligação com recurso ao counter-trading

Dissertação para obtenção do grau de Mestre em Engenharia Electrotécnica Ramo de energia

Aspectos da morfometria de drenagem e produção de sedimentos em relação a variante chuva x vazão de diferentes trechos da Bacia do Ribeirão do Gama – Distrito Federal nos anos de 2014 a 2015

Dissertação (mestrado)—Universidade de Brasília, Departamento de Geografia, Programa de Pós-Graduação em Geografia, 2015.

Redes elétricas inteligentes: desenvolvimento de modelos computacionais e aplicações para a gestão do lado da procura

Esta tese incide sobre o desenvolvimento de modelos computacionais e de aplicações para a gestão do lado da procura, no âmbito das redes elétricas inteligentes. É estudado o desempenho dos intervenientes da rede elétrica inteligente, sendo apresentado um modelo do produtor-consumidor doméstico. O problema de despacho económico considerando previsão de produção e consumo de energia obtidos a partir de redes neuronais artificiais é apresentado. São estudados os modelos existentes no âmbito dos programas de resposta à procura e é desenvolvida uma ferramenta computacional baseada no algoritmo de fuzzy-clustering subtrativo. São analisados perfis de consumo e modos de operação, incluindo uma breve análise da introdução do veículo elétrico e de contingências na rede de energia elétrica. São apresentadas aplicações para a gestão de energia dos consumidores no âmbito do projeto piloto InovGrid. São desenvolvidos sistemas de automação para, aquisição monitorização, controlo e supervisão do consumo a partir de dados fornecidos pelos contadores inteligente que permitem a incorporação das ações dos consumidores na gestão do consumo de energia elétrica; SMART GRIDS - COMPUTATIONAL MODELS DEVELOPMENT AND DEMAND SIDE MANAGMENT APPLICATIONS Abstract: This thesis focuses on the development of computational models and its applications on the demand side management within the smart grid scope. The performance of the electrical network players is studied and a domestic prosumer model is presented. The economic dispatch problem considering the production forecast and the energy consumption obtained from artificial neural networks is also presented. The existing demand response models are studied and a computational tool based on the fuzzy subtractive clustering algorithm is developed. Energy consumption profiles and operational modes are analyzed, including a brief analysis of the electrical vehicle and contingencies on the electrical network. Consumer energy management applications within the scope of InovGrid pilot project are presented. Computational systems are developed for the acquisition, monitoring, control and supervision of consumption data provided by smart meters allowing to incorporate consumer actions on their electrical energy management.