FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / This paper analyzes the mesoscale model WRF (Weather Research And Forecast) to verify its reliability in use as a research tool in areas with potential for eolioeletric generation. The area chosen for study was a farm located in Maracanaà in the state of CearÃ. On the farm was installed an anemometer tower of 80 meters high with three anemometers, 1 windsock, 1 temperature sensor and a pyranometer, all sensors connected to a datalogger. The data collected in this tower were used for comparison with the data obtained through simulations in WRF. In the simulations the model was evaluated for two different climatic conditions in the region, the rainy and the dry seasons. The periods chosen to perform the simulations are: March/2012 (representing the rainy season) and November/2011 (representing the dry season). Was performed five sensitivity tests, which were exchanged in the parameterizations of the Planetary Boundary Layer (PBL), Surface Layer (CS) and Ground Surface Model (GSM). The simulation results were evaluated according to the Pearson's correlation method, that one has parameter values from -1 to 1 which presents an index of correlations ranging from bad (-1) to great (1). The simulation with the best performance in the dry and rainy periods presented values for correlations of 0.76 and 0.58, respectively, considered good and fair to the Pearson's parameters. The model was able to satisfactorily represent the local wind behavior for the dry season of the year, and more research is needed in the area to analyze how the model behaves in the representation of the rainy season. Thus, this model provides satisfactory results to be used as a tool for evaluate areas with potential for eolioeletric generation, more research is needed to fit better. / O presente trabalho analisa o modelo de mesoescala WRF (Weather Research and Forecast) para verificar a sua confiabilidade na utilizaÃÃo como ferramenta de investigaÃÃo de Ãreas com potencial para geraÃÃo eolioelÃtrica. A regiÃo escolhida para estudo foi uma fazenda localizada no municÃpio de MaracanaÃ, no estado do CearÃ. Na fazenda foi instalada uma torre anemomÃtrica de 80 metros de altura com 3 anemÃmetros, 1 biruta, 1 sensor de temperatura e um piranÃmetro, todos os sensores conectados a um datalogger. Os dados coletados nesta torre foram utilizados para comparaÃÃo com os dados obtidos atravÃs das simulaÃÃes no WRF. Nas simulaÃÃes o modelo foi avaliado para duas situaÃÃes climatolÃgicas distintas na regiÃo, o perÃodo chuvoso e o seco. Os perÃodos escolhidos para realizar as simulaÃÃes sÃo: marÃo/2012 (representando o perÃodo chuvoso) e novembro/2011 (representando o perÃodo seco). Foram realizados cinco testes de sensibilidade, nos quais foram permutadas as parametrizaÃÃes da Camada Limite PlanetÃria (CLP), Camada de SuperfÃcie (CS) e o Modelo de Solo SuperfÃcie (MSS). Os resultados das simulaÃÃes foram avaliados segundo o mÃtodo de correlaÃÃo de Pearson, mÃtodo este que possui parÃmetros de valores de -1 a 1 onde apresenta um indicativo de correlaÃÃes que vÃo de pÃssimas (-1) a Ãtimas (1). A simulaÃÃo com o melhor desempenho no perÃodo seco e chuvoso apresentaram valores de correlaÃÃes de 0,76 e 0,58, consideradas forte e moderada, para os parÃmetros de Pearson, respectivamente. O modelo conseguiu representar de forma satisfatÃria o regime de vento local para a estaÃÃo seca do ano, sendo necessÃrias mais pesquisas na Ãrea para analisar como o modelo se comporta na representaÃÃo do perÃodo chuvoso. Assim este modelo apresenta resultados satisfatÃrios para ser utilizado como ferramenta para avaliaÃÃo de regiÃes com potencial em geraÃÃo eolioelÃtrica, sendo necessÃrias mais pesquisas para ajustÃ-lo melhor.

Orientador: Luiz Antonio Rossi / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-25T15:35:36Z (GMT). No. of bitstreams: 1 Rodrigues_RafaelValotta_M.pdf: 1796516 bytes, checksum: c10125b5f3d629834ab44f3d7dc88632 (MD5) Previous issue date: 2014 / Resumo: A participação da energia eólica na matriz elétrica brasileira vem aumentando continuamente desde 2005. A conexão de Aerogeradores de Grande Porte à rede elétrica foi permitida após a regulamentação do setor eólico no Brasil pela ANEEL, culminando com o crescimento contínuo do setor nos últimos cinco anos e a consolidação da participação da fonte eólica na matriz elétrica brasileira. O interesse pela utilização de Aerogeradores de Pequeno Porte no país aumentou, posto que sua conexão com a rede elétrica foi regulamentada pela ANEEL através da resolução 482. Acompanhando a evolução do uso de aerogeradores, metodologias para avaliação e simulação do desempenho de aerogeradores foram extensivamente desenvolvidas no século passado. Uma delas é o Método do Momento no Elemento de Pá, um modelo numérico unidimensional desenvolvido inicialmente por Glauert em 1920, utilizado para aferir o desempenho aerodinâmico do rotor do aerogerador. Neste trabalho, as curva de desempenho de potência e curvas adimensionais de desempenho de dois aerogeradores de pequeno porte foram simuladas teoricamente utilizando o Método do Momento no Elemento de Pá. Posteriormente, a aplicação desses aerogeradores na situação de conexão com a rede elétrica ou em um sistema isolado eólico-baterias foi simulada por meio do programa computacional Homer, considerando três cidades diferentes: Campinas e Cubatão (Brasil/SP) e Roscoe (Estados Unidos / TX). O aerogerador nacional possui melhor desempenho aerodinâmico em baixas rotações, enquanto que o importado possui coeficiente de potência mais alto em altas rotações. Além disso, o aerogerador nacional produz mais energia elétrica para todas as localidades analisadas com exceção da cidade de Campinas (SP/BR), onde o aerogerador importado obteve melhor desempenho simulado. Considerando o sistema isolado eólico - baterias, a garantia de suprimento integral à carga elétrica simulada só é alcançada com um banco de baterias com muitas unidades e alto número de aerogeradores devido à intermitência da fonte eólica. O desempenho aerodinâmico do rotor e o custo da energia ($/kWh) dependem fortemente das características técnicas do aerogerador e do recurso eólico local / Abstract: The use of the wind energy in the Brazilian energy matrix has been increasing since 2005. The connection of large wind generators to the grid was allowed after the regulation of the wind industry in Brazil by ANEEL, resulting in the continued growth of the sector over the past five years, and the consolidation of the use of wind energy in the Brazilian energy matrix. Interest in the use of Small Wind Turbines (SWT) in the country has grown, since the regulation of its connection to the energy grid by ANEEL by the 482 resolution. Following the evolution of wind turbine using, methodologies to evaluation and simulation of wind turbine performance were extensively developed last century. One of them is the numeric one-dimensional model based on the Blade Element Moment Method, first developed last century by Glauert to derive aerodynamic performance of wind turbine rotor. In this research, the power performance curve and non-dimensional performance curves of two small wind turbines of horizontal axis were evaluated simulated theoretically using the Blade Element Moment Method. Afterwards, the application of the wind turbines for on-grid and off-grid systems was simulated using the software Homer, considering three different cities: Campinas and Cubatão (Brazil/SP) and Roscoe (United States/TX). The national wind turbine has better aerodynamic performance in lower rotations, while the imported has higher power coefficient in higher rotations. Also, the national wind turbine produces more electric energy for all locations evaluated excepting for Campinas City (SP/BR), where the imported wind turbine had better simulated performance. Considering the off-grid wind batteries system, the full supply can be reached only using a bank battery with many units and several wind turbines due to the intermittency of the wind energy. The rotor aerodynamic performance and the cost of energy ($/kWh) depend strongly of the technical characteristics and the local wind resource / Mestrado / Construções Rurais e Ambiencia / Mestre em Engenharia Agrícola

The threatening impacts of climate change are driving a global revolution towards cleaner sources of energy. In South Africa, strategies for energy security and emissions reduction are focusing on renewables, wind energy being one of the most promising ones. The construction of wind energy projects has attached limitations in the identification of suitable areas that respect the environment and are technically feasible. Herein, site selection criteria has been grouped into the Site Identification group (SIG), and the Resource & Energy Generation group (R&E). The SIG incorporates technical, environmental and restricted criteria within a spatial frame; while R&E accounts for the wind resource, estimated energy generation and fitting to energy demand profiles under a spatial-temporal frame. The average wind resource is usually found to be analysed together within the technical factors to determine the feasibility of a site; however for this study, a different and independent treatment of the wind resource and its energy generation profile was undertaken. It consists of evaluating the unique hourly wind power profile of each site against the energy consumption profile for the same period. The need is for selecting places with the smallest variation between the electricity produced and the electricity demanded. The Production to Demand Difference (PDD) has been chosen as the indicator of such variations. Therefore, the new purpose is to identify spots where the combination of the PDD and the results from the SIG become smaller with time. The Mean Difference (MD) is also taken into account to obtain further information regarding the trends of the differences. Geoprocessing, overlays and mathematical combinations of datasets are all performed under a GIS environment. / Dissertation (MEng)--University of Pretoria, 2015. / tm2015 / Chemical Engineering / MEng / Unrestricted

<p>Renewable energy adoption is critical when considering future energy grids and how they impact the environment, economy and society. While fossil fuels have traditionally been employed to generate the electricity used across every facet of the global economy, renewables are becoming increasingly more attractive as a substitute. Fossil fuels have historically outperformed their clean energy counterparts in terms of levelized cost. However, over the last few decades renewables have become extremely cost competitive and are starting to outpace their opposition as advancements in technology continue. As the cost gap between “brown” and “green” energy sources decreases, energy grid mixes will adopt more sustainably responsible generation, positively impacting the planet.</p> <p>In the following thesis, two studies are presented which demonstrate new innovations for decreasing the cost of offshore wind energy and how renewables and desalination can be integrated along the US-Mexico border. The first study describes an itemized breakdown of how substituting the mechanical transmission with hydraulics can lower the life-time cost of an offshore wind turbine. The second analysis details a complex wind and solar powered clean water production and distribution network to combat ongoing water scarcity along the US-Mexico border. Both concepts push the boundaries of scientific innovation and its application for solving social and economic issues. </p>

[pt] A Sazonalização é o processo de dividir as quantidades anuais de um contrato de fornecimento de energia elétrica em montantes mensais. Trata-se de flexibilidade contratual facultativa geralmente determinada ou imposta pelo agente comprador. A participação das usinas eólicas na matriz energética brasileira tem aumentado nos últimos anos, sendo a energia dos ventos uma fonte renovável que apresenta uma característica interessante de complementaridade em relação à vazão das usinas hidrelétricas. As carteiras de empresas comercializadoras passam então a abrigar contratos com usinas eólicas e hidrelétricas. Tendo como meta auferir maiores ganhos algumas comercializadoras realizam operações descasadas e podem utilizar a flexibilidade da sazonalização de contratos. Neste trabalho foi tomada como referência uma comercializadora que possui uma carteira composta de um contrato de venda de um montante mensal fixo de energia, um contrato de compra da energia elétrica de uma usina eólica e um contrato de compra de energia de uma hidrelétrica que pode ser sazonalizado. Foi desenvolvida uma metodologia para determinar o perfil de sazonalização ideal a ser utilizado para aumentar os lucros da carteira de contratos. A maximização da medida Ômega delta foi a métrica utilizada para analisar os cenários e foram consideradas restrições de Value at Risk - VaR nas análises realizadas. Os resultados encontrados mostram que a maximização da medida Delta é obtida concentrando-se toda compra de energia da hidrelétrica no segundo semestre do ano. Entretanto, à medida que a restrição de VaR torna-se mais severa diminuindo o grau de liberdade para realizar a sazonalização a distribuição dos montantes de energia elétrica aproxima-se da uniformidade entre os meses do ano. / [en] The seasonal adjustment is the process of dividing the annual quantities of an electricity supply contract in monthly amounts. This is a contractual flexibility generally determined or imposed by the contract buyer. The share of wind farms in the Brazilian energy system has increased in the last few years and wind energy is a renewable source that presents an interesting feature of complementarity with hydroelectric power plants in Brazil. Therefore, contracts with wind farms and hydroelectric plants are becoming part of the trading companies portfolios. Aiming to reach higher gains, some energy traders enter into uncovered trading positions and use the flexibility of seasonal adjustments of contracts to combine these two sources in a portfolio. This study used as reference a trading company that has a portfolio composed of a sales contract for a fixed monthly amount of energy, a contract to buy electricity from a wind farm and a contract to purchase electricity from a hydroelectric plant that can be seasonally adjusted. A methodology is proposed to find the ideal profile of seasonal adjustments that should be used to increase the portfolio’s profits. The maximization of the Omega measure delta - along with Value at Risk (VaR) restrictions- , was the metric used to analyze the scenarios and choose the optimal portfolio. The results found show that the maximization of the Delta measure is obtained by concentrating all the energy bought from the hydroelectric in the second semester of the year. However, as the constraint VaR becomes more severe restricting the freedom to make seasonal adjustments, the distribution of energy amounts between the months of the year approaches the uniformity.

There are challenges to be addressed if South Africa is to reach its full potential in exploiting wind energy resources. One of such challenges is communal land ownership, which is used for the development of wind energy in rural areas. Often, communal lands have no formal land structures, ownership or title deeds to support the individuals and communities that claim possession thereof. This challenge of communal land ownership and the associated risks impact upon investments by independent power producers in wind energy infrastructure. Land in South Africa remains a highly sensitive issue given the historical injustice of land dispossession which became the source of poverty and inequality. Moreover, transitioning to renewable energy sources would add more pressure on land scarcity. Commercial wind energy projects are capital intensive, with high annual turnovers. Achieving financial close is a risk mitigation strategy that confirms that early-stage contractual agreements have been reached in the development stage of a wind project lifecycle. Therefore, risk identification and allocation are fundamental to ensuring that the structuring and contractual obligations of non-recourse project financing are met. Wind energy plants require significant stretches of land, and this is progressing at an industrial scale and often, onshore wind energy projects are located in rural areas, thereby impacting local communities. Land ownership rights are a key element for communities, in which renewable energy development takes place. Households living on communal land, of which the right to use land is vested in individual households, are situated on such lands. This study uses the theory of risk management to investigate pre-financial close risks in developing wind energy associated with communal land ownership rights and the extent to which those risks inhibit wind energy projects from reaching financial close in South Africa. An exploratory research design was applied, while a questionnaire survey was used to collect data from wind developers. The study identified the pre-financial close risks associated with communal land to be technical, legal, economic, social and political risks. Indeed, there is a lack of clear, long-term policy framework to support investments in clean energy infrastructure. This causes significant delays to wind energy project development and it negatively affects financial close. In addition, there are competing interests among multiple stakeholders, leading to the burdensome processes involved in securing leasehold agreements on communal land. As a result, projects which were initially proposed on communal land, have not always reach financial close as planned while others were stopped. The results show that risk mitigation tools could include effective and continuous stakeholder management which is critical to reaching financial close. Furthermore, the Department of Rural Development and Land Reform has not established a streamlined process that developers can follow to secure communal land leasehold rights, given that the process is time-consuming.

Wind farm layout optimization can greatly improve wind farm performance. However, past wind farm design has been limited in several ways. Wind farm design usually assumes that all the turbines throughout the farm should be exactly the same. Oftentimes, the location of every turbine is optimized individually, which is computationally expensive. Furthermore, designers fail to consider turbine loads during layout optimization. This dissertation presents four studies which provide partial solutions to these limitations and greatly improve wind farm layout optimization. Two studies explore differing turbine designs in wind farms. In these studies, Wind farm layouts are optimized simultaneously with turbine design. We found that for small rotor diameters and closely spaced wind turbines, wind farms with different heights have a 5–10% reduction in cost of energy compared to farms with all the same turbine height. Coupled optimization of turbine layout and full turbine design results in an 2–5% reduction in cost of energy compared to optimizing sequentially for wind farms with turbine spacings of 8.5–11 rotor diameters. Wind farms with tighter spacing benefit even more from coupled optimization. Furthermore, we found that heterogeneous turbine design can produce up to an additional 10% cost of energy reduction compared to wind farms with identical turbines throughout the farm, especially when the wind turbines are closely spaced. The third study presents the boundary-grid parameterization method to reduce the computational expense of optimizing wind farms. This parameterization uses only five variables to define the layout of a wind farm with any number of turbines. For a 100 turbine wind farm, we show that optimizing the five variables of the boundary-grid method produces wind farms that perform just as well as farms where the location of each turbine is optimized individually, which requires 200 design variables. The presented method facilitates the study for both gradient-free and gradient-based optimization of large wind farms. The final study presents a model to calculate fatigue damage caused by partial waking on a wind turbine which is computationally efficient and can be included in wind farm layout optimization. Compared to high fidelity simulation data, the model accurately predicts the damage trends of various waking conditions. We also perform a wind farm layout optimization with the presented model in which we maximize the annual energy production of a wind farm while constraining the damage of each turbine. The results of the optimization show that the turbine damage can be constrained with only a very small sacrifice of less than 1% to the annual energy production.

Wind energy is expanding rapidly in the United States as the nation\'s energy policy objectives increasingly focus on renewables. Public opinion polls show that a majority of Americans support wind energy development but actual wind farm projects often face intense local opposition. This dichotomy between general support for wind energy but opposition towards siting a project nearby is often attributed to the not-in-my-backyard (NIMBY) phenomenon. In this study we employ a discrete choice experiment to investigate public preferences for different characteristics of a local wind farm. We investigate NIMBY by first controlling for characteristics that might cause local opposition, such as seeing or hearing a wind farm from home, and then after considering these effects of a wind farm we examine whether people who favor wind energy display NIMBY resistance. Finally, we estimate compensation requirements for siting a wind farm within sight or sound of someone\'s home. Results show that people who somewhat favor wind energy do display NIMBY attitudes since they are predisposed to vote against local wind development even after controlling whether they would see and hear the wind farm from their homes. We do not detect NIMBY attitudes among people who strongly favor wind energy because they have a positive disposition towards local wind farms. Our results suggest that if an incentive program is in place from the onset of a wind development project it could offset NIMBY reactions to specific projects. / Master of Science

The way our electricity is generated is in a period of rapid change; in the United States and many other countries the system is becoming less reliant on coal based power systems, while natural gas and solar and wind power are becoming more and more important. Technological advances have made solar and wind power more efficient and increasingly cost-effective. While these changes to the electrical system come with great benefits, such as less pollution, these technologies are not free of impacts. The electrical system is inseparable from our modern lifestyle, and because the system is so large this transition will affect society in many ways. This dissertation analyzes one aspect of the social side of these changes in the electrical system by asking, what does the public think about renewable energy? In particular we examined how political beliefs, community differences, and residential distance from wind turbines might influence attitudes about renewable energy. We find that political belief is an important factor in predicting levels of support for renewable energy, with conservatives less likely to prefer renewable energy and liberals more supportive of its development. We also find distinct differences in how residents of particular communities tend to react to renewable energy and local wind power development. In addition, we find that living closer to wind turbines is not a good way to predict attitudes about wind energy. These results should help policy makers and developers to make better decisions about how and where we build utility-scale solar and wind electric power facilities by taking into consideration the nuances of personal and political beliefs as well as community differences.

Vibration energy harvesting has been widely investigated by academia and industry in the past decade with focus on developing distributed power sources. One of the prime goals of energy harvesters is to provide power to wireless sensors allowing for the placement of these sensors in the remote and inaccessible areas where battery is not an option. Electromechanical modeling approaches have been developed for enhancing the mechanical to electrical conversion efficiencies utilizing electromagnetic, piezoelectric, and magnetostrictive mechanisms. Models based upon the constitutive equations for these three conversion mechanisms, supported by extensive experimental results available in literature, suggest that power requirement through energy harvesters can be met only when the total volume is in the range of 1-100 cm3. There exists a critical volume of 0.5 cm³ at which above which the electromagnetic mechanism exhibits higher power density as compared to the other mechanisms. Therefore, in this thesis electromagnetic energy conversion was adopted to develop high power energy harvesters. We also present a novel vibration energy harvesting method which rivals the power density and bandwidth of the traditional methods. The overarching theme throughout the design process was selecting the structure and fabrication methodology that facilitates the transition of the technology. The experimental models were characterized at accelerations and frequencies typically found in the environmental vibration sources. The thesis provides in-depth the design, modeling, and characterization of a vibration energy harvester which creates relative motion differently than the conventional harvesters. Conventional designs rely on amplifying the original source displacement operating at the resonance condition. In the harvester design proposed in this thesis, the relative motion is created by cancelling the vibration at one location and transferring the source vibration directly to another location by combining a vibration isolator with a vibration absorber. In this novel configuration, termed as Direct Vibration Harvester (DVH), the energy is harvested directly from the vibrating source mass rather than a vibrating seismic mass attached to the source increasing the harvesting bandwidth and power density. Four bar magnet and magnetic levitation architectures were modified and modeled to reach closer to the theoretical maximum power densities. Extensive FEM was utilized to understand the performance limitations of the existing structures and the results from this analysis paved the pathway towards the development of the DVH. �A comparative analysis of the performance of the DVH with the traditional harvesting methods in terms of normalized power output and bandwidth was conducted. Performance improvements of DVH required development of the high efficiency rotational generators as linear to rotational conversion occurs in the DVH. The optimized rotational generator was modeled and all the predicted performance metrics were validated through experiments. The generator was applied towards the fabrication of DVH and also in a micro windmill. The power density of the micro windmill was found to be better than all the other results reported in literature. Extensive fluid and structural modeling was conducted to tailor the performance of the micro windmill in the desired wind speed range. Combined, this thesis provides significant advancement on many fronts. It pushes the magnetic levitation and four-bar mechanism harvester systems to their theoretical limits. It demonstrates a novel direct vibration harvester that has the possibility of surpassing the power density and bandwidth of all the known vibration harvester with large magnitude of output power. It provides a design process for an efficient small scale electromagnetic generator that can form for the backbone of many rotational and linear harvesters. This generator was used to develop the world's highest power density micro windmill in the small wind speed range. / Ph. D.