Dissertations / Theses on the topic 'Wind energy'

In this study we conduct wind resource assessment to evaluate the annual energy production of a wind turbine. To estimate energy production of a wind turbine over a period of time, the power characteristics of the wind turbine are integrated with the probabilities of the wind speed expected at a chosen site. The first data set was obtained from a wind farm in Denmark. We propose several probability density functions to model the distribution of the wind speed. We use techniques from nonlinear regression analysis to model the power curve of a wind turbine. The best fit distribution model is assessed by performing numeric goodness–of–fit measures and graphical analyses. Johnson’s bounded (SB) distribution provides the best fit model with the smallest Kolmogorov–Smirnov (K-S) test statistic . 15. The four parameter logistic nonlinear regression (4PL) model is determined to provide the best fit to the power curve data, according to the Akaike Information Criterion (AIC) and the Bayesian Information Criterion (BIC). The estimated annual energy yield is compared to the actual production of the wind turbine. Our models underestimate the actual energy production by a 1 difference. In Chapter Six we conduct data processing, analyses and comparison of wind speed distributions using a data set obtained from a measuring wind mast mounted in Humansdorp, Eastern Cape. The expected annual energy production is estimated by using the certified power curve as provided by the manufacturer of the wind turbine under study. The commonly used Weibull distribution is determined to provide the best fit distribution model to our selected models. The annual energy yield is estimated at 7.33 GWh, with a capacity factor of 41.8 percent.

This thesis investigates issues like maintenance problems, key factors, maintenance challenges, maintenance solutions and practical difficulties in wind energy. In this case, surveys and interviews have been taken from several companies and maintenance experts, to find most prevailing problems and problem-solving methods since last few years. It helps to show, how the energy maintenance has been developed in past few years. Also it analyses the impact of fourth generation maintenance in wind energy production. From research questions, key factors involved in wind energy maintenance provides us with valuable suggestions to develop the maintenance methods in future vision.

Energy harvesting is a very attractive technique for a wide variety of self-powered microsystems such as wireless sensors. Airflow induced oscillations have been used as an attractive technique for energy harvesting because of its potential capacity for generating electrical power. The aero-elastic instability phenomenon such as flutter has been suggested especially for small scale energy harvesters. This paper describes the design, simulation, fabrication, measurement and performance of a miniature wind energy harvester based on a flapping cantilevered beam. The wind generator is based on oscillations of a cantilever that faces the direction of the airflow. The oscillation is amplified by interactions between an aerofoil attached on the cantilever and a bluff body placed in front of the aerofoil. To achieve the optimum design of the harvester, both computational simulations and experiments have been carried out to investigate the structure. Simulation is achieved with ANSYS to optimise the structure and predict the power generation for practical design. Both piezoelectric materials and electromagnetic transducers are used for the generator and tested. Three prototypes with the same volume of 37.5 cm3 are fabricated and tested through two aspects of the performance namely the threshold wind speed for operation and the output power. Wind tunnel test results are presented to determine the optimum structure and to characterize the performance of the harvesters. The piezoelectric generator is fabricated by thick-film screen printing technique. The optimized device finally achieved a working wind speed range from 2 m/s to 8 m/s. The power output was ranging from 0.35 to 3.6 μW and the open-circuit output voltage was from 0.6V to 1.9V. The first electromagnetic harvester had a working wind speed range from 1.35 m/s to 6 m/s with a maximum power output of 29.8 μW and a voltage of 293 mV. While for the second generator, the wind speed for operation is form 1.5 m/s to 6.5 m/s. The output power is ranging from 8.9 μW to 41 μW and the output voltage is up to 171 mV. Results verified the harvester can effectively convert wind energy into large amplitude mechanical vibration without strict frequency matching constraints.

In considering methods of reducing the emission of carbon dioxide; there is a growing interest for use of wind power at domestic building in U.K. But the technology of wind turbines development in building environment is more complicated than in open areas. Small wind turbines in suburban areas have been reported as having unsatisfactory energy output, but it is not clear whether this is due to insufficient wind resource or low turbine efficiency. The aim of this research is to discover whether the wind resource in suburban areas is large enough for small wind turbines to produce a useful energy output.Historical wind data and manufacturers' turbine characteristics were used to estimate the hourly wind speed and energy output for different U.K. cities, terrain zones and turbines. It was found that for turbines at 10 m height in suburban areas and depending on city, the annual wind energy conversion efficiency ranged from about 20 to 40%, while the number of turbines required to produce the annual average electricity consumption of a UK dwelling ranged from about 6 for the smallest turbine (5.3 m² rotor area) to about 1 for the largest (35.26 m² rotor area).This analysis was based on average conditions, but the wind speed near buildings can vary considerably from one point to another. In order to predict the performance of wind turbines more accurately, the atmospheric boundary layer (ABL) of suburban areas was simulated in both CFD and wind tunnel models, and models of groups of semi-detached and terraced houses were set in this ABL. It was found that at 10 m height in the area of the houses, the turbulence intensity was too high for satisfactory operation of wind turbines (19 to 35%) while the mean velocity at different points ranged from 86 to 108% of the 10m reference velocity. At 30m height the turbulence intensity was satisfactory (less than 19 %), while the mean velocity ranged from 92 to 103 % of the 30 m reference velocity. It is concluded that for wind turbines in suburban areas, at 10 m height the wind speed is too low and the turbulence is too high for satisfactory performance, while at 30 m height the wind speed is much higher and the turbulence is low enough.

Wind Energy facilities are becoming a more common occurrence among the U.S. landscape. The shift to renewable from non-renewable energy sources is an important agenda item for energy policy in the 21st century. Unlike other forms of energy, the unique visual aspects of wind energy provide opportunities to engage with and actually view the process of energy production. The sculptural element of turbines and their placement in highly visible areas, such as mountain ridges, provides opportunities of environmental interpretation and public interaction. Although existing security and safety precautions in the U.S. do not allow public use of these facilities, the integration of turbines into public places is becoming more common in other parts of the world. This creative project focuses on developing dynamic and unique cultural places that also serve as education spaces to celebrate wind and wind energy. Environmental art installations among the wind turbines serve as human-scaled interpretational guides to create meaningful, learning experiences between the user, the wind and the landscape.This project highlights the existing eleven-turbine (6MW) facility in the town of Searsburg in southern Vermont. This project includes inventory, analysis and site design of an existing wind facility. The methodology includes using GIS data and existing sight line data, as well as significant and environmental cultural points. Finally, general guidelines are included as a design foundation for other wind energy facilities.
Department of Landscape Architecture

Thesis (MScIng)--Stellenbosch University, 2003.
ENGLISH ABSTRACT: The effect of topography and terrain on wind is examined in order to ensure that the wind turbine positioning will encourage a greater availability of wind energy to it. Maximum power point tracking methods are presented whereby the loading on the wind turbine is controlled to ensure that the maximum available energy from the wind is captured. The wind turbine system is modelled and used in simulations to evaluate the three proposed maximum power point trackers, named anemometer control, calculation control and constant step control for the purpose of this thesis. An additional analog system is also created whereby the complete wind turbine system is able to be simulated. An inverter is used to replicate the generator and the loading is controlled using an active rectifier since this will be used on the practical system. The results from the simulations and analog system are presented whereby one of the trackers is shown to be inadequate and the other two trackers are shown to be close to ideal. The appeal of the calculation method is in the redundancy of an anemometer making it attractive to less expensive, small-scale systems.
AFRIKAANSE OPSOMMING: Die invloed van die topografie en die terrein op die dinamika van wind word ondersoek om sodoende te verseker dat die posisionering van wind turbienes 'n beter effektiwiteit van wind energie oordrag sal bewerkstellig. Maksimum drywingspunt volger metodes word bespreek sodat die lading op die wind turbiene beheer kan word om sodoende te verseker dat die maksimum wind energie oorgedra kan word. Die wind turbiene stelsel word gemodeleer en geimplimenteer om die drie voorgestelde maksimum drywingspount volgers te evalueer, naamlik windspoedbeheer, berekening-beheer en konstantestap-beheer vir die doeleindes van hierdie tesis. 'n Adissionele analoog stelsel is ontwerp waarmee die volledige wind turbiene stelsel gesimuleer kan word. 'n Omsetter word gebruik om die generator na te boots en die belading word beheer deur middel van 'n aktiewe gelykrigter soos gebruik 'n praktese stelsel. Resultate van die simulasies en die analog stelsel is verskaf om te bewys dat een van die volg-metodes onvoldoende volging bewerkstellig, en die ander twee nabyaan ideale volging bewerkstellig. Dit is getoon dat die berekening metode meer aantreklik is vir kleinskaal stelsels, aangesien 'n windspoedsensor onnodig is.

Small-scale wind energy is a renewable energy technology with exciting prospects in a low carbon energy future. However, in order for the technology to be fully utilized, techniques capable of predicting the wind energy resource quickly, cheaply and accurately are urgently required. Specifically, the direct measurement approaches used in the large-scale wind industry are often not financially or practically viable in the case of small-scale installations. The subject of this thesis is the development of low-cost, indirect methods for predicting the wind resource using, (i) analytical models based on boundary layer meteorology and (ii) data-driven techniques based on measure-correlate-predict (MCP). The approaches were developed and tested using long-term (11 years) wind data from meteorological stations, short-term (1 year) data from a field trial of small-scale turbines, and output from an operational forecast model. As a first step, the performance of an existing boundary layer scaling model was evaluated at 38 UK sites and found to result in large site-specific errors. Based on these findings, a revised model was developed and shown to improve prediction accuracy. However, uncertainty analysis and comparison with onsite measurements revealed average errors in the predicted wind power density of over 60% due to uncertainties in the model input parameters. Hence, it was concluded that such an approach is best applied in a scoping context to identify sites worthy of further study. To investigate the ability of low-cost, data-driven techniques to reduce these uncertainties, MCP approaches were trialled using onsite measurement periods as short as 3 months at a subset of 22 of the above UK sites. In addition to established linear approaches, non-linear Gaussian process regression and bivariate conditional probability approaches were developed. Using a 3 month measurement period, the best performing MCP approaches resulted in average errors in the predicted wind power density of 14%, compared to 26% when using the boundary layer scaling approach at the same sites. The effect of seasonal variability in the prediction errors was investigated in detail and found to be most significant at coastal sites. This variability was found to be reduced by using output from an operational forecast model in place of long-term reference wind data. This work provides a means for low-cost and rapid wind resource assessment in cases where traditional approaches are not viable.

The wind industry has arrived at a state of technological maturity and is occasionally already today cost-competitive to conventional sources of energy. This thesis investigates the process of innovation that took place within the industry. A theoretical background into economical theory of innovation together with a status quo assessment of today's wind industry serves as introduction to the topic. In the analytical part, inducement mechanisms and functions of technological development will be identified as crucial drivers for innovation within the sector. The key findings of this thesis lead to conclude that it is now the responsibility of the industry to becoming fully cost-competitive to conventional sources. The advancement of technological lifecycle will primarily depend on turbine manufacturers and their capability to drive innovation more independently from governments.

The interaction of turbulent wakes with one another and with the adjacent fluid directly impacts the generation of electricity in wind turbine arrays. Computational modeling is well suited to the repeated iterations of data generation that may be required to inform understanding of the function of wind farms as well as to develop control schemes for plant function. In order to perform such computational studies, a simplified model of the turbine must be implemented. One of the most computationally efficient parametrizations of the blade utilizes a stationary disk which has a prescribed drag and produces a wake. However, since accurate estimates of wake properties and the interaction with the surrounding fluid is critical to the function of wind farms, a comparison of the wakes emitted from a stationary disk model should be compared to that of a model with a rotating blade. Toward this end, an array of model rotating wind turbines is compared experimentally to an array of static porous disks. Stereo particle image velocimetry measurements are done in a wind tunnel bracketing the center turbine in the fourth row of a 4$\times$3 array of model turbines. Equivalent sets of rotors and porous disks are created by matching their respective induction factors. The similarities and differences in the wakes between these two cases are explored using time-averaged statistics. The primary difference in the mean velocity components was found in the spanwise mean velocity component, which is much as 190\% different between the rotor and disk cases. Conditional averaging of mean kinetic energy transport in wake from these two models reveals that a differing mechanism is responsible for the entrainment of mean kinetic energy in the near wake. In contrast, results imply that the stationary porous disk adequately represents the mean kinetic energy transport of a rotor in the far wake where rotation is less important. Proper orthogonal decomposition and analysis of the invariants of the Reynolds stress anisotropy tensor is done in order to examine large scale structure of the flow and characterize the turbulent wake produced by the porous disks and rotors. The spatial coherence uncovered via the proper orthogonal decomposition in the rotor case and its absence in the disk case suggests caution should be employed when applying stationary disk parametrization to research questions that are heavily dependent on flow structure. Motivated by questions on the impact of freestream turbulence on wakes in wind energy, a study of pairs of cylinders subject to varying levels of inflow turbulence is undertaken. Time-averaged statistics show a modification of the symmetry and development of the wakes originating from the pairs of cylinders in response to freestream turbulence. Recurrence-based phase averaging allowws examination of the many configurations of the wake and the modification of these topologies due to varying inflow turbulence. Results show the changes in vortex shedding synchronization as well as large scale cross stream advection in response to elevated levels of incoming turbulence.

Wind turbines typically rely on feedback controllers to maximize power capture in below-rated conditions and regulate rotor speed during above-rated operation. However, measurements of the approaching wind provided by Light Detection and Ranging (lidar) can be used as part of a preview-based, or feedforward, control system in order to improve rotor speed regulation and reduce structural loads. But the effectiveness of preview-based control depends on how accurately lidar can measure the wind that will interact with the turbine.

In this thesis, lidar measurement error is determined using a statistical frequency-domain wind field model including wind evolution, or the change in turbulent wind speeds between the time they are measured and when they reach the turbine. Parameters of the National Renewable Energy Laboratory (NREL) 5-MW reference turbine model are used to determine measurement error for a hub-mounted circularly-scanning lidar scenario, based on commercially-available technology, designed to estimate rotor effective uniform and shear wind speed components. By combining the wind field model, lidar model, and turbine parameters, the optimal lidar scan radius and preview distance that yield the minimum mean square measurement error, as well as the resulting minimum achievable error, are found for a variety of wind conditions. With optimized scan scenarios, it is found that relatively low measurement error can be achieved, but the attainable measurement error largely depends on the wind conditions. In addition, the impact of the induction zone, the region upstream of the turbine where the approaching wind speeds are reduced, as well as turbine yaw error on measurement quality is analyzed.

In order to minimize the mean square measurement error, an optimal measurement prefilter is employed, which depends on statistics of the correlation between the preview measurements and the wind that interacts with the turbine. However, because the wind speeds encountered by the turbine are unknown, a Kalman filter-based wind speed estimator is developed that relies on turbine sensor outputs. Using simulated lidar measurements in conjunction with wind speed estimator outputs based on aeroelastic simulations of the NREL 5-MW turbine model, it is shown how the optimal prefilter can adapt to varying degrees of measurement quality.

The topic of this thesis is the study of energy storage systems operating with wind power plants. The motivation for applying energy storage in this context is that wind power generation is intermittent and generally difficult to predict, and that good wind energy resources are often found in areas with limited grid capacity. Moreover, energy storage in the form of hydrogen makes it possible to provide clean fuel for transportation. The aim of this work has been to evaluate how local energy storage systems should be designed and operated in order to increase the penetration and value of wind power in the power system. Optimization models and sequential and probabilistic simulation models have been developed for this purpose.

Chapter 3 presents a sequential simulation model of a general windhydrogen energy system. Electrolytic hydrogen is used either as a fuel for transportation or for power generation in a stationary fuel cell. The model is useful for evaluating how hydrogen storage can increase the penetration of wind power in areas with limited or no transmission capacity to the main grid. The simulation model is combined with a cost model in order to study how component sizing and choice of operation strategy influence the performance and economics of the wind-hydrogen system. If the stored hydrogen is not used as a separate product, but merely as electrical energy storage, it should be evaluated against other and more energy efficient storage options such as pumped hydro and redox flow cells. A probabilistic model of a grid-connected wind power plant with a general energy storage unit is presented in chapter 4. The energy storage unit is applied for smoothing wind power fluctuations by providing a firm power output to the grid over a specific period. The method described in the chapter is based on the statistical properties of the wind speed and a general representation of the wind energy conversion system and the energy storage unit. This method allows us to compare different storage solutions.

In chapter 5, energy storage is evaluated as an alternative for increasing the value of wind power in a market-based power system. A method for optimal short-term scheduling of wind power with energy storage has been developed. The basic model employs a dynamic programming algorithm for the scheduling problem. Moreover, different variants of the scheduling problem based on linear programming are presented. During on-line operation, the energy storage is operated to minimize the deviation between the generation schedule and the actual power output of the wind-storage system. It is shown how stochastic dynamic programming can be applied for the on-line operation problem by explicitly taking into account wind forecast uncertainty. The model presented in chapter 6 extends and improves the linear programming model described in chapter 5. An operation strategy based on model predictive control is developed for effective management of uncertainties. The method is applied in a simulation model of a wind-hydrogen system that supplies the local demand for electricity and hydrogen. Utilization of fuel cell heat and electrolytic oxygen as by-products is also considered. Computer simulations show that the developed operation method is beneficial for grid-connected as well as for isolated systems. For isolated systems, the method makes it possible to minimize the usage of backup power and to ensure a secure supply of hydrogen fuel. For grid-connected wind-hydrogen systems, the method could be applied for maximizing the profit from operating in an electricity market.

Comprehensive simulation studies of different example systems have been carried out to obtain knowledge about the benefits and limitations of using energy storage in conjunction with wind power. In order to exploit the opportunities for energy storage in electricity markets, it is crucial that the electrical efficiency of the storage is as high as possible. Energy storage combined with wind power prediction tools makes it possible to take advantage of varying electricity prices as well as reduce imbalance costs. Simulation results show that the imbalance costs of wind power and the electricity price variations must be relatively high to justify the installation of a costly energy storage system. Energy storage is beneficial for wind power integration in power systems with high-cost regulating units, as well as in areas with weak grid connection.

Hydrogen can become an economically viable energy carrier and storage medium for wind energy if hydrogen is introduced into the transportation sector. It is emphasized that seasonal wind speed variations lead to high storage costs if compressed hydrogen tanks are used for long-term storage. Simulation results indicate that reductions in hydrogen storage costs are more important than obtaining low-cost and high-efficient fuel cells and electrolyzers. Furthermore, it will be important to make use of the flexibility that the hydrogen alternative offers regarding sizing, operation and possibly the utilization of oxygen and heat as by-products.

The main scientific contributions from this thesis are the development of

- a simulation model for estimating the cost and energy efficiency of wind-hydrogen systems,

- a probabilistic model for predicting the performance of a gridconnected wind power plant with energy storage,

- optimization models for increasing the value of wind power in electricity markets by the use of hydrogen storage and other energy storage solutions and the system knowledge about wind energy and energy storage that has been obtained by the use of these models.

Paper 1 is reprinted with kind permission of ACTA Press. Paper 2 is reprinted with kind permission of Elsevier/ Science Direct. http://www.elsevier.com, http://www.sciencedirect.com Paper 3 is reprinted with kind permission of IEEE.

This thesis proposes a methodology for planning, scheduling and on-line control of an energy storage system for the integration of wind energy. Using the case study of a remote wind-diesel system, the different time frames of the design and implementation process are detailed. First, a long-term planning approach for rating of the power and energy capacities of the ESS is presented, based on stochastic optimization. The formulation is then adapted into a hourly scheduling approach and results are compared with the expected cost of energy and energy requirements resulting from the planning study. The optimization results are used as training data for an artificial neural network, in an effort to generate an on-line control that captures inherent rules, using artificial intelligence. The ESS is realized as a two-level ESS and a general control structure for on-line operation of multi-level ESS is proposed and adapted for the wind-diesel system, as the first level in a hierarchical control. The system is evaluated in simulation and selected results are validated using a hardware-in-the-loop representation of the system, demonstrating that the proposed controller is realizable.
Cette thèse propose une méthodologie pour la planification, l'utilisation et la commande d'un système de stockage d'énergie permettant l'intégration de l'énergie éolienne. Utilisant comme étude de cas un réseau autonome alimenté par un système éolien-diesel, les différentes étapes de la conception et la mise en oeuvre sont détaillées. Premièrement, une étude de planification à long terme pour le dimensionnement de la puissance nominale et de la capacité énergétique du stockage est présentée, basée sur les méthodes d'optimisation stochastique. La formulation est ensuite adaptée à une commande sur une base horaire et les résultats sont comparés, au niveau de l'énergie et de la quantité d'énergie utilisée, aux résultats obtenus dans l'étude de planification. Les résultats obtenus par optimisation du système sont utilisés dans l'entrainement d'un réseau de neurones artificiels, afin de produire une commande qui capte les règles inhérentes au système, utilisant l'intelligence artificielle. Le stockage d'énergie est réalisé par un système de stockage à deux niveaux et une structure de commande appropriée à plusieurs niveaux est proposée et adaptée pour un système éolien-diesel, comme premier niveau d'une commande hiérarchique. La performance du système est évaluée par simulation et certains résultats ont été validés avec un banc d'essai. Celui-ci consiste à des convertisseurs électroniques intégrés avec une représentation par simulation temps réel du système. Les résultats obtenus concordent avec les résultats de simulation et confirment que la commande proposée est réalisable.

In this thesis work, electricty generation modeling of the wind energy -one type of the renewable energy sources- is studied. The wind energy characteristics and the distribution of wind speed in a specific region is also examined. In addition, the power curves of the wind turbines are introduced and the relationship between the wind speed and wind power is explained. The generation characteristics of the wind turbines from various types of producers are also investigated. In this study, the main wind power forecasting methods are presented and the advantages and disadvantages of the methods are analyzed. The physical approaches, statistical methods and the Artificial Neural Network (ANN) methods are introduced. The parameters that affect the capacity factor, the total energy generation and the payback period are examined. In addition, the wind turbine models and their effect on the total energy generation with different wind data from various sites are explained. As a part of this study, a MATLAB-based software about wind speed and energy modelling and payback period calculation has been developed. In order to simplify the calculation process, a Graphical User Interface (GUI) has been designed. In addition, a simple wind energy persistence model for wind power plant operator in the intra-day market has been developed.

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia de Automação e Sistemas, Florianópolis, 2016.
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Abstract : Airborne Wind Energy (AWE) is an emerging field of technology that investigates wind power devices capable of remaining airborne either through aerostatic or aerodynamic forces. Consequently, the heavy and expensive tower of conventional horizontal-axis wind turbines is no longer needed, allowing the AWE device to operate at higher altitudes, where the wind tends to be steadier and stronger and, therefore, more power is available. Another claimed advantage is the reduction on overall costs, especially regarding transportation and installation, due to the absence of the tower to withstand the torque caused by the rotating turbine, thus also requiring a simpler foundation. Several AWE concepts have been proposed, among which the pumping kite stands out as one of the simplest and cheapest, essentially comprising a ground winch where energy is generated, and a tethered wing that can be either flexible or rigid. This dissertation contributes to the field of AWE by addressing the pumping kite in four different aspects. The goal is to serve both as a manuscript for the lay reader with some background on physics, aerodynamics, dynamic systems, classic control and optimization techniques, as well as by specialists in either of these areas who intend to carry out deeper investigations. The first contribution is to revisit in detail important models in the literature used to simulate the flight dynamics, to design and to validate control laws. Namely, the 3D two-tether point-mass wing (to which modifications are proposed), the massless wing in dynamic equilibrium, the course angle dynamics and the logarithmic wind shear model are addressed. The second contribution is a comparative study of flight controllers whose references are computed separately from the ground winch control, in a decentralized topology. A two-loop approach is considered, where the outer loop defines a reference trajectory and generates a reference for the course angle, which is then tracked in the inner loop by manipulating the steering input of the tethered wing. A third contribution is the formulation of an optimization problem to choose the operating parameters of the traction and retraction phases that yield the maximum cycle power. One of the main findings is that, by reeling out at a lower speed than the value that maximizes the traction power, the duty cycle increases and, thereby, also the cycle power. The last major contribution is to reinterpret Loyd?s lift (the pumping kite traction phase) and drag modes as particular cases of the actuator disc considered in the derivation of the Betz limit for power extraction from the wind. The expression for the lift mode power coefficient is formulated using blade element momentum theory.

Energia eólica aérea (Airborne Wind Energy (AWE), em inglês) é uma tecnologia de energia renovável que trata de dispositivos que aproveitam a energia cinética do vento e são capazes de se manter no ar através de forças aerostáticas ou forças aerodinâmicas. Este campo de estudos vem atraindo cada vez mais pesquisas devido a duas grandes vantagens previstas sobre a tecnologia convencional de turbinas de eixo horizontal. A primeira vantagem é que a substituição da torre por cabos de comprimento variável permite ao dispositivo operar em altitudes mais elevadas, onde os ventos tendem a soprar mais consistentemente e a uma velocidade maior, caracterizando, portanto, um potencial energético maior. A segunda vantagem é uma redução substancial nos custos do empreendimento, especialmente nos quesitos de transporte e instalação, devido à ausência de uma torre que deva suportar o torque causado pela operação da turbina. Assim, acredita-se que a fundação para o ponto de ancoragem do sistema também se torna mais simples e barata. Os dispositivos de AWE que mantêm-se em voo através de forças aerodinâmicas são denominados de aerofólios cabeados . Várias estruturas com aerofólios cabeados já foram propostas, dentre as quais destaca-se o pumping kite por ser uma das mais simples e de menor custo. O pumping kite consiste, essencialmente, de duas unidades uma de solo e a outra, de voo com possíveis variações quanto ao tipo de aerofólio (rígido ou flexível), número e função dos cabos, atuadores para controle de voo no solo ou junto ao aerofólio, etc. Em uma das configurações mais usuais, tem-se uma máquina elétrica no solo acoplada a um carretel através de uma redução mecânica. À medida em que o aerofólio descreve uma trajetória que visa maximizar a força de tração no cabo, este desenrola-se do carretel, fornecendo potência mecânica à máquina elétrica que, nessa fase, opera como gerador. Quando o comprimento de cabo atinge um valor pré-determinado, encerra-se a fase de tração e inicia-se a fase de recolhimento, durante a qual a máquina elétrica opera como motor para enrolar o cabo até seu comprimento inicial. Para isto o aerofólio é reconfigurado para uma condição de baixa força aerodinâmica, permitindo o recolhimento com um pequeno gasto energético e, assim, aumentando a potência média entregue à rede (potência de ciclo) ao final deste ciclo com duas fases. A unidade de voo é composta essencialmente pelo aerofólio, por um microcomputador embarcado e pelos atuadores de controle de voo. Esta tese visa contribuir à área de AWE em quatro diferentes aspectos. O objetivo é servir tanto como um documento para o leitor leigo interessado no assunto e que tenha conhecimentos em física, aerodinâmica, sistemas dinâmicos, controle clássico e otimização, bem como uma referência para especialistas que estejam buscando avançar em qualquer uma destas frentes. A primeira contribuição é a discussão em detalhes de alguns modelos importantes usados para a simulação, análise e projeto de controladores de voo para aerofólios cabeados. Dentre estes modelos está o aerofólio ponto de massa com dois cabos, cuja construção é explicada passo-a-passo, incluindo a proposição de pequenas modificações relativas ao efeito da massa dos cabos nas equações de movimento. Em seguida também é feita a derivação do modelo que representa a dinâmica do ângulo de curso ( ângulo de giro ) do aerofólio, que é uma variável frequentemente utilizada para o controle de voo. Um terceiro modelo discutido é o modelo logarítmico que descreve a variação da intensidade média do vento de acordo com o coeficiente de rugosidade do solo. Para fins ilustrativos, o modelo foi interpolado para algumas localidades com base em um banco de dados norte-americano aberto ao público. A segunda contribuição desta tese é um estudo comparativo sobre abordagens para controle de voo em uma topologia decentralizada, na qual as leis de controle da unidade de solo e de voo são computadas separadamente. O controle de voo utiliza uma estratégia com duas malhas em cascata. Durante a fase de tração, uma opção é a malha externa utilizar a lemniscata de Bernoulli como referência para a trajetória de oito deitado desejada para o voo do aerofólio. Com base no erro de seguimento da lemniscata, é gerada uma referência para o ângulo de curso, que é repassada à malha interna. Já para a fase de retração, a referência do ângulo de curso é mantida apontando para o zênite, fazendo com que o aerofólio saia da zona de potência (condição de vento cruzado, crosswind) e possa ser recolhido com baixo gasto energético. Uma outra possibilidade discutida, mais simples, é o uso de apenas dois pontos de atração (atratores) como referência de posição do aerofólio na malha externa, com apenas um dos atratores ativo. Assim que o aerofólio cruza a coordenada azimute de um atrator, o outro torna-se o ativo, levando o aerofólio a executar uma curva e, dessa forma, realizar a trajetória desejada de oito deitado. Devido à descontinuidade no erro de seguimento quando chaveia-se entre os atratores, ocorre uma descontinuidade no sinal de controle, razão pela qual esta estratégia é conhecida como bang-bang . É discutido como o bang-bang pode ser vantajoso no caso de aerofólios cabeados com um curto perímetro (comprimento de arco) da trajetória, situação em que o período de amostragem do controle torna-se relativamente grande, o que dificulta a estabilização do controle. Por outro lado, no caso de trajetórias com perímetro maior, a ausência de um percurso bem definido entre os dois atratores pode resultar em uma trajetória aproximadamente geodésica ( reta angular), afastando-se, assim, das trajetórias ótimas de oito deitado sugeridas na literatura. Neste caso, a opção com a lemniscata de Bernoulli pode tornar-se vantajosa. Para a malha interna do controle de voo também foram investigadas algumas alternativas, entre as quais um controlador proporcional. Usando o modelo da dinâmica do ângulo de curso linearizado em alguns pontos principais, é computado o intervalo do ganho proporcional que garante estabilidade em malha fechada, supondo conhecidos os parâmetros do modelo. Também com base no mesmo modelo do ângulo de curso, projetou-se um controlador de realimentação linearizante que impõe uma dinâmica estável de primeira ordem ao erro de rastreamento da malha interna. Tal controlador linearizante requer, em sua lei de controle, o conhecimento da derivada da referência do ângulo de curso. Dado que esta derivada pode ser difícil de se obter, na prática, com baixo ruído, é investigada uma variante do controlador linearizante sem a mencionada derivada. Considerando, para os três controladores, aproximadamente a mesma constante de tempo do sistema em malha fechada, o controlador linearizante completo obteve o melhor desempenho, seguido pelo proporcional, enquanto o linearizante sem derivada da referência do ângulo de curso ficou com o pior desempenho. Uma terceira contribuição ao estudo do pumping kite é a formulação de um problema de otimização para um ciclo de operação, considerando-se a topologia de controle decentralizado. Já que a lei de controle de voo é computada separadamente da unidade de solo, é necessário determinar os valores de alguns parâmetros de operação cuja escolha pode ter um impacto significativo na potência de ciclo. Mostra-se como a potência média durante a fase de tração varia em função do ângulo de ataque médio, e como o ângulo de ataque base pode ser determinado para operar-se no ponto de máxima potência. A fase de tração é parametrizada em termos de um ângulo de ataque base, uma velocidade de desenrolamento, um ângulo polar médio da trajetória, e um comprimento médio do cabo. Já a fase de retração é parametrizada por meio de dois coeficientes que definem a inclinação das rampas de força de tração e ângulo de ataque base, e dois patamares ao final destas rampas. São consideradas restrições no mínimo ângulo de ataque importante no caso de aerofólios flexíveis e na máxima velocidade de enrolamento alcançada pela máquina elétrica. A ideia é reduzir a força de tração e o ângulo de ataque do aerofólio enquanto a velocidade de enrolamento aumenta e, dessa forma, obter-se uma fase de retração eficiente. Para fins ilustrativos, o problema de otimização é resolvido para os valores de patamar através de uma busca em grid, enquanto os coeficientes de inclinação de rampa são definidos de maneira ad hoc. Entre as principais conclusões está que, para o aerofólio do tipo foil (ram-air) kite com 12 m2 de área projetada sujeito a um vento nominal de aproximadamente 10 m/s, ao desenrolar-se o cabo a 2.3 m/s, o que corresponde a uma redução de 25.8 % com relação à velocidade que maximiza a potência na fase de tração, obtém-se um acréscimo de 9.3 % na potência de ciclo. Com base em um método simplificado para cálculo da potência de ciclo, também é obtida a curva de potência do pumping kite, discutindo-se as suas distintas regiões de operação. A última contribuição desta tese refere-se à interpretação dos aerofólios cabeados como um caso específico do disco atuador considerado na derivação do limite de Betz para extração de potência do vento. No caso do disco atuador, a potência extraída é abstraída como o produto entre o empuxo sofrido pelo disco e a velocidade do vento atravessando o disco. No caso da turbina eólica de eixo horizontal, a potência dá-se pelo produto entre o torque no disco e a sua velocidade angular. Já no caso do modo de sustentação de Loyd (a fase de tração do pumping kite), a potência decorre do produto entre o empuxo no disco e a velocidade de translação do disco no sentido do vento (velocidade de desenrolamento ). Finalmente, no caso do modo de arrasto de Loyd (turbina acoplada ao aerofólio cabeado), a potência aproveitada surge do produto entre a velocidade tangencial do disco e a força de arrasto (empuxo) sofrida pela turbina. A tese é concluída com a formulação da expressão do coeficiente de potência para o modo de sustentação de Loyd, evidenciando-se o problema do cálculo dos fatores de indução axial, radial, e o ângulo de ataque parcial para cada anel do disco.

Le siècle dernier a été le siècle de la révolution technologique. Les combustibles fossiles ont alimenté cette révolution technologique. Les défis auxquels notre société est confrontée, que ce soit le changement climatique ou la situation énergétique mondiale ou l’épuisement des réserves de combustibles fossiles, sont les défis les plus graves auxquels sont confrontés toutes les générations. L'énergie renouvelable est considérée comme la clé des problèmes énergétiques de notre société. De nombreuses technologies innovantes se font concurrence pour alimenter la prochaine révolution énergétique. Sources d'énergies renouvelables telles que l'énergie solaire, l'énergie éolienne, la biomasse, l'hydroélectricité, l'énergie géothermique, etc. Presque tous sont saisonniers, et sont donc des sources d'énergie discontinues et non uniformes. Ils ont également une limitation en termes de choix des sites de production et, en général, nécessitent de grandes étendues de terre pour les plantes, ce qui conduit à une faible densité de puissance par unité de surface.Néanmoins, l'énergie éolienne et solaire a beaucoup attiré l'attention au cours des dernières décennies. Cependant, pour que le monde passe complètement des énergies fossiles et de l’énergie nucléaire à l’énergie éolienne et solaire, il est nécessaire de développer de nouveaux types de systèmes capables de générer de l’énergie à moindre coût avec moins de contraintes de sélection de sites.Dans la quête de la source d'énergie pérenne. Notre société se tourne vers la communauté scientifique pour des solutions innovantes. Cette thèse est une étape vers la recherche de solutions innovantes à nos problèmes énergétiques. Les systèmes d'énergie éolienne à haute altitude (HAWE) ou plus communément appelés systèmes éoliens aéroportés (AWES) sont considérés comme la réponse aux besoins énergétiques des générations futures. L'énergie éolienne aéroportée (AWE) est un concept innovant visant à utiliser l'énergie des courants de vent à haute altitude, car les courants de vent à haute altitude sont presque uniformes dans le monde entier et AWES peut pratiquement être installé partout dans le monde. De plus, les systèmes AWE proposés nécessitent moins de matériau de structure. Ils devraient donc être beaucoup moins chers que toute autre source d’énergie disponible. AWE est donc une perspective prometteuse dans cette quête pour trouver une solution à nos problèmes énergétiques.Dans ce travail, la faisabilité des systèmes d'énergie éolienne aéroportés basés sur Magnus est explorée. Le travail présente en détail un bref historique des systèmes d'énergie éolienne aéroportés et des concepts de base nécessaires pour développer une compréhension de la technologie AWE. Il examine en détail les systèmes aéroportés basés sur Magnus et donne une perspective historique sur les machines basées sur l’effet Magnus. Il présente en détail les propriétés aérodynamiques de l’effet Magnus et présente un modèle aérodynamique pour ces systèmes. Puisque la modélisation est un aspect important de toute technologie. Ce travail présente un modèle détaillé des systèmes AWE basés sur Magnus ainsi que les algorithmes de contrôle nécessaires au fonctionnement de tels systèmes. Les courbes de puissance sont des outils couramment utilisés pour analyser les systèmes d'énergie éolienne. Ce travail présente une approche pour la conception de courbes de puissance pour les systèmes AWE afin d'analyser les capacités de production d'énergie des systèmes d'énergie éolienne aéroportés
Last century has been the century of the technology revolution. Fossil fuels have fueled this technology revolution. The challenges faced by our society be it the climate change or the world energy situation or the depletion of fossil fuel reserves are the most grievous challenges faced by any generation. Renewable energy is believed to be the key to energy problems of our society. There are many innovative technologies competing against each other to fuel the next energy revolution. Renewables sources of energies such as solar, wind, biomass, hydropower, geothermal etc. Though promising but due to the high economic cost and limited application they are yet to prove their mass scale applicability. Almost all of them are seasonal, hence, are discontinuous and non-uniform sources of energy. They also have a limitation in terms of choice of plant sites, and generally, require large tracts of land for plants which lead to low power density per unit area.Nonetheless, Wind and Solar energy have attracted a lot of attention in the last few decades. However, for the world to fully shift from fossil fuels and nuclear energy to Wind and Solar power, it is necessary to develop new kind of systems which can generate continuous power at a lower cost with fewer site selection constraints.In the quest to find the perennial clean source of energy. Our society is looking towards the scientific community for innovative solutions. This thesis is one such step towards finding innovative solutions to our energy problems. High altitude wind energy systems (HAWE) or more commonly known as Airborne wind energy systems (AWES) are believed to be the answer to the energy needs of the future generations. Airborne wind energy (AWE) is an innovative concept aiming at utilizing the energy of the high altitude wind currents, as high altitude wind currents are almost uniform across the globe, and AWES can be practically set-up anywhere around the world. Also, the proposed AWE systems require less structural material. Thus, they are expected to be much cheaper than any other available energy source. Therefore, AWE is a promising prospect in this quest to find a solution to our energy problems.In this work, the feasibility of Magnus-based airborne wind energy systems is explored. The work presents in detail a brief history of Airborne wind energy systems and the basic concepts needed to develop an understanding about the AWE technology. It discusses in detail Magnus-based airborne systems and gives a historical perspective on the Magnus-effect based machines. It discusses in detail the aerodynamical properties of the Magnus effect and presents an aerodynamic model for such systems. Since modeling is an important aspect of any technology. This work presents a detailed model of the Magnus-based AWE systems along with the control algorithms required for the operation of such systems. A common tool used to analyze wind-based energy systems is power curves. This work presents an approach to design power curves for AWE systems in order to analyze the power producing capabilities of Airborne wind energy systems

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 221-225).
As energy becomes an increasingly important issue for generations to come, it is crucial to develop tools for valuing and understanding energy projects from an economic perspective since ultimately only economically viable solutions will be pushed forward. A model is developed for valuing a generic offshore floating wind farm from a corporate finance perspective. The model is used to value the project based on multiple valuation metrics and to generate sensitivity analyses on multiple important technical, cost and financial parameters. It is found that offshore wind projects can be economically viable under current conditions contingent on high annual mean wind speed and government support. In addition, it is also found that financial parameters prove to be equally or even more important than technical parameters in affecting the overall project value. Furthermore, the wind speed and power output are modeled using a mean reverting Ornstein - Uhlenbeck process whereby it is found that while wind speed is positively autocorrelated, the averaging period plays an important role in determining the nature and extent of the autocorrelation. Finally, the valuation is extended and generalized to a Black-Scholes option based valuation of any project whose underlying asset follows a mean reverting process, whereby a model is developed to find the debt and equity values under the assumption of time independence. The tools developed for this purpose can prove to be useful in other applications besides energy, such as shipping and commodities, as the underlying characteristics of energy projects are often similar across other markets.
by Andrew Nanopoulos.
S.M.

The increasing presence of wind energy installations is faced with citizen and political resistance often founded on the potential damage these can impose on fauna such as birds. This resistance is an obstacle to the necessary introduction of more weather-based renewable electricity sources due to the consequences of fossil-fuel electricity generation. However, if the introduction of more wind energy installations is to continue, this must also not be at the expense of wildlife. This project seeked to verify the existence of bird-turbine collision risk and to identify high collision risk zones in the temporal and spatial scale for Afro-Palaearctic migratory birds flying through Europe. Collision risk was assumed as the presence of birds through the swept area of turbines. The migratory movement of birds was obtained from an interpolation of a geostatistical model and data from 37 weather radars for the dates 13 February 2018 to 1 January 2019. The data is given as a volumetric flow across a 0.25° grid. The volumetric distribution of wind energy installations was derived from a database of 23145 installations and a self-sourced turbine database of 589 turbine models. This distribution is presented as both a high-resolution map covering the European continent and as a swept area density map. The volumetric bird flow was multiplied by the swept area density to obtain values for birds at risk of collision in a 0.25° grid cell. Birds were not considered at risk when the average wind speed in the cell was outside the cut-in and cut-out wind speed region for the turbines (i.e. not between 3 m/s and 24 m/s). The potential electricity production per 0.25° grid cell was also estimated. This was achieved by assigning power curves from a database to the wind energy installations and assigning a mean power curve to the entries missing a specific turbine model. The wind velocities were hourly average values for the dates 13 February 2018 to 1 January 2019 from the ERA5 reanalysis. A calculation of energy per bird at risk in [TJ/bird] was also done. Four high collision risk spatial zones were explored in detail by use of a map compiled in QGIS and their proximity to or overlay with protected bird habitat sites discussed. Temporally, date ranges when bird collision is highest were obtained for the four country sub-region in 2018. The possibility of curtailment is briefly discussed.

The possibility to use wind power directly in a house to replace part of the used electricity is examined here theoretically. Measured climate data from Finland, Vanda airport at 10 meters height, are used for outdoor temperature and wind data. This data is simulated for 8 different wind turbine power output and a case study residence building is used for the energy demand. The energy demand consists of heating, hot water and electrical equipment. If wind production is higher than energy demand then the remaining energy is stored in one electrical battery or the buildings hot water boiler. Additional excess energy is delivered free to the network and does not taken into account into the energy balance of the building. The 8 different small scale wind turbine options and the energy demand of the house are compared and the profitability of each system is assessed. Based on the available data, excel is used to calculate the energy production and demand over a year based on hourly temperature and wind speed measurements. Some suggestions for further research are given at the end.

Cross flow wind turbines are not unique. The performance of Savonius and Darrieus turbines is well documented. Both share the advantage of being able to accept fluid flow from any direction. The Savonius is drag based and hence has poor power output while the Darrieus is lift based. Due to the fact that the Darrieus has fixed blades the fluid flow through the rotor does not result in optimal lift being generated at all points in the rotation circle. A drawback of the Darrieus system is that it has to operate at a high tip-to wind-speed ratio to obtain reasonable performance with the fixed blades. Deviation from a small optimal range of tip speed ratios results in poor performance. The Darrieus also has poor starting torque. The research conducted in this project focused on overcoming the shortcomings of other turbines and developing an effective cross flow turbine capable of good performance. A number of different concepts were experimented with, however all were based on a symmetrical aerofoil presented to the actual relative airflow at an angle that would produce the highest lift force at all times. The lift force was then utilized to generate movement and to do work on an electrical generator. All concepts contemplated were researched to ascertain their appropriateness for the intended application. During development of the final experimental platform and after lodging of a provisional patent (RSA 2007/00927) it was ascertained that the design shared some similarities with an American patent 5503525 dated 28/4/1994. This patent employed complex electronic sensing and control equipment for control of blade angle. This was thought to be overly complex and costly, particularly for small scale wind energy generation applications and a simpler mechanical solution was sought in the design of the final experimental platform used in this project. The design of the mechanical control system was refined in an attempt to make it simpler, more durable and employ the least number of moving parts. Literature studies and patent searches conducted, suggested that the mechanical control system as developed for the final experimental platform was unique. The enormous variation in the power available from the wind at the different wind speeds likely to be encountered by the device necessitated some means of control. In high wind conditions control of the amount of wind power into the device was deemed to be the preferable means of control. A number of different concepts to achieve this were devised and tested. The final concept employed limited the tail angle deflection and hence the lift produced by the aerofoils. This resulted in a seamless “throttle” control allowing the device to be used in any wind strength by adjusting the control to a position that resulted in the device receiving a suitable amount of power from the wind. The outcome of performance tests conducted indicated that the device has the potential to be developed into a viable wind turbine for both small and large scale applications. The ability to control the power input from the wind to the machine from zero to a maximum is considered to be one of the most beneficial outcomes of this project and together with the quiet operation and low speed, are considered the main advantages of the device over existing wind turbine designs. The possibilities of using the device to compress air for energy storage are exciting avenues that warrant further research.

Wind energy provides an environmentally friendly and renewable source of electricity, that can help meet Canada's Kyoto commitments, help safeguard against future blackouts, reduce air pollution and create economic opportunities in the form of manufacturing jobs and land leases for farmers. From a land use planning perspective, however, wind turbines create challenges that municipalities and planners have to deal with more frequently. Ontario in particular lags behind countries such as Ireland and Australia in terms of providing a clear, equitable and comprehensive land use planning framework to deal with wind energy.

What is lacking in particular is a clear understanding of how Ontario municipalities are dealing with the issue of wind energy developments, whether the policies that are being developed adhere to good planning principles, what are the land use planning issues that are impacting wind energy development in Ontario and what are some recommendations that could be made to improve wind energy policies. A secondary goal of this thesis was to identify common elements of good wind energy planning frameworks that could be used to develop wind energy planning policies in the City of Stratford, which currently does not have any policies or a wind energy land use planning framework and is also where the author is employed as the City Planner.

To address this lack of information, this report focuses on the current state of wind energy planning policy development in southwestern Ontario and in particular; the types of wind energy planning frameworks have been developed in the world, the elements of "good" planning principles and frameworks and whether or not they are found in these frameworks, whether there are components of these policies that would be appropriate for wider adoption in Ontario and finally, what types of framework should the City of Stratford develop for wind energy?

To address these questions, a literature review was conducted on wind energy land use planning issues and examples of international wind energy planning guidelines were reviewed. Additionally, five southwestern Ontario municipalities with wind energy policies were selected as case studies and Planners and other wind energy stakeholders were interviewed.

This study found that the main issues and barriers surrounding wind energy planning policy development in Ontario are visual impact, lack of education and a lack of a municipal planning framework. It was also determined that, the public reaction to wind energy proposals in Southwestern Ontario has been mostly positive and the conflicts that have arisen have been in instances where wind turbines are proposed in the vicinity of recreational properties. In terms of a wind energy planning framework, southwestern Ontario municipalities have for the most part opted for General Official Plan policies supporting wind energy development in principle and directing its development to certain land use designations subject to a zoning by-law amendment. The planning frameworks in the case studies for the most part conform to good planning principles identified, however, there was a large variation between the municipalities in terms of the level of detail within the planning framework. Finally, it was determined that the City of Stratford Official Plan and Zoning By-law are inadequate in terms of policy and regulations for wind energy.

This study recommends that the Ontario Provincial Government should follow up on the Wind Energy Information Sheet and the recent Provincial Policy Statement with a comprehensive land use-planning framework for wind energy developments that should borrow on existing international guidelines that have been developed. This study also recommends that the City of Stratford should update its Official Plan to include policies that address wind energy generation, should initiate a study to determine if there are any areas within the City that are considered to be natural heritage views or areas that should be protected from the visual impacts of wind energy production, should investigate permitting wind energy facilities in certain industrial areas of the City, subject to a zoning by-law amendment and should work with the County of Perth to develop a common set of zoning by-law regulations for wind energy developments.

Thesis (MScEng (Energy and Development Studies)) -- University of Cape Town, 2010.
ENGLISH ABSTRACT: Growing concerns regarding climate change, energy security, long-term carbon price exposure, fuel-price risk and fossil fuel depletion have continued to drive growth in wind energy globally over the past decade. In spite of South Africa’s renewable energy target and feed-in tariff for renewable energy, the current deployment of wind energy in South Africa is extremely low. Consequently, as the country embarks upon promoting the development of renewable energy, it is important to consider the challenges facing the wind energy industry in South Africa.
Sponsored by the Centre for Renewable and Sustainable Energy Studies

Includes abstract.
Includes bibliographical references (leaves 87-94).
Growing concerns regarding climate change, energy security, long-term carbon price exposure, fuel price risk and fossil fuel depletion have continued to drive growth in wind energy globally over the past decade. In spite of South Africa’s renewable energy target and feed-in tariff for renewable energy, the current deployment of wind energy in South Africa is extremely low. Consequently, as the country embarks upon promoting the development of renewable energy, it is important to consider the challenges facing the wind energy industry in South Africa.

Globally, wind power is leading the renewable energy revolution. While carbon neutral and cost-effective, wind energy infrastructure is immobile and has the potential to profoundly change land use and the visible landscape. As wind technology takes its place as a key contributor to the US energy grid, it becomes clear that these types of projects will come into greater contact with areas occupied by humans, and eventually with wilderness and other more natural areas. This increased visibility and close proximity necessitates the development of future wind farm sites that afford opportunities for auxiliary uses while maintaining their intrinsic value as energy producers. In short, it is important for wind farms to be versatile because land is a finite resource and because over time, increasing numbers of these sites will occupy our landscapes. In the Eastern US, the majority of onshore wind resources suitable for energy development are found along ridge lines in the Appalachian mountains. These mountains are ancient focal points in the landscape, and subsequently host myriad sites of historic, recreational, and scenic significance. In the future, these windswept ridges will likely become targets for wind energy development. This thesis demonstrates a methodology for the thoughtful siting and design of future wind projects in the Appalachian mountains. Opportunities for offsite views, diversified trail experiences, and planned timber harvests are realized by locating a seven-turbine wind park adjacent to the Appalachian Trail in Cherokee National Forest in Carter county, Tennessee. The proposed wind park demonstrates the sound possibility of thoughtfully integrating wind infrastructure along Appalachian ridges in conjunction with forestry and recreation opportunities, such as hiking and camping. The design is a wind park rather than a wind farm because in addition to its inherent function as a production landscape, it is also a place that is open to the general public for recreational use.
Master of Landscape Architecture

I dagens samhälle diskuteras miljö- och energifrågorna i allt större utsträckning. Projektgruppen valde att bidra till utvecklingen genom att underlätta för vindkraftbolagen att nå ut med grön energi på marknaden.

Projektgruppen har tillsammans med samarbetspartnern Lars Bååth professor i fotonik på Högskolan i Halmstad tagit fram en produkt som mäter vind inför byggandet av vindkraftverk. Wind Energy Analyzing System mäter vindförhållandena kontinuerligt från marknivå med hjälp av ljud och förvandlar informationen till vindriktning och vindhastighet på specifika höjder. Wind Energy Analyzing System är enkelt för kunden att använda och ger överlägsen information över vindförhållandena jämfört med de produkter som finns på marknaden idag. Priset för Wind Energy Analyzing System kommer att ligga en bra bit under konkurrenternas och tillverkas endast av standard komponenter vilket gör att produkten kan säljas med stor vinst.

Tidigare har man behövt investera stora summor för att säkerställa vindförhållandena innan man bygger ett vindkraftverk. Samtidig har informationen från dessa mätningar varit delvis uppskattade vilket har bidragit till en viss osäkerhet vid etablerandet av vindkraftverk. Wind Energy Analyzing System medför bättre vindmätningar till ett lägre pris.

Wind Energy Analyzing System är ett steg i rätt riktning, ett steg mot en framtid med förnyelsebar energi.

In the society today there are a lot of discussion about the environment and energy. The project group chose to contribute to the development by making it easier for wind energy companies to reach out with the green energy.

The project group has with cooperation of Lars Bååth, professor of photonics at Halmstad University, been developing a product for measuring wind before establishing of wind power plants. Wind Energy Analyzing System continuously measures the wind conditions from ground level by means of audio and converts the information to wind directions and wind speed at specific heights. Wind Energy Analyzing System is easy for customers to use and provide superior information on wind conditions compared to the products on the market today. The Price for Wind Energy Analyzing System will be well below its competitors and manufactured only of standard components so that the product can be sold with great profit.

Previously the wind power companies had to invest large sums to ensure the wind conditions before building a wind turbine. Meanwhile, information from these measurements was partly estimated which has contributing to some uncertainty of the establishment of wind power plant. Wind Energy Analyzing System will contribute with better wind measurements at a lower price.

Wind Energy Analyzing System is a step in the right direction, a step toward a future of renewable energy.

As the demand for safe and clean electricity increases, the New Zealand wind energy industry seems poised to expand. Many generating companies have projects in the planning stage and there are likely to be many more potential sites yet to be identified. Reliable wind climate predictions over a wide area and for different heights above grounds are often vital to determine the viability of wind farm projects. This study investigates the use of meteorological mesoscale models to determine the wind and energy resource, particularly in areas of complex terrain. Complex terrain environments are likely to be typical of where New Zealand wind energy developments will take place. Using the prognostic mesoscale meteorological model TAPM (The Air Pollution Model), regions of relatively high mean wind speed were identified for a number of regions, including Banks Peninsula and parts of Canterbury and Otago. The simulations were conducted for a one-year period (2001) and at different heights above ground level. Depending on the resolution of the model calculations, speed-up effects from the forcing of some topographic features were accounted for by this model. Where the modelling was considered reliable, hourly wind data were obtained from grid points within the inner grid and used as input data for the industry-standard wind energy assessment model WAsP (The Wind Atlas Analysis and Application Program). As WAsP is able to account for detailed topography and surface roughness features, wind and energy predictions at a specific site or over a wider area surrounding the site were made. Limitations of both models in complex terrain were identified. These limitations were due to a number of factors, including the grid spacing used for mesoscale model calculations, the complexity of the terrain, and difficulties in modelling some regional scale airflow regimes. Being aware of when and where model limitations are likely to occur is important in being able to overcome and account for them.

Large Scale Wind Turbines (LSWTs) have been extensively examined for decades but very few studies have been conducted on the small scale wind turbines (SSWTs) especially for the applications near ground level where wind speed is of order of few meters per second. This study provides the first systematic effort towards design and development of SSWTs (rotor diameter<50 cm) targeted to operate at low wind speeds (<5 m/s). An inverse design and optimization tool based on Blade Element Momentum theory is proposed. The utility and efficacy of the tool was validated by demonstrating a 40 cm diameter small-scale wind energy portable turbine (SWEPT) operating in very low wind speed range of 1 m/s-5 m/s with extremely high power coefficient. In comparison to the published literature, SWEPT is one of the most efficient wind turbines at the small scale and very low wind speeds with the power coefficient of 32% and overall efficiency of 21% at its rated wind speed of 4.0 m/s. It has very low cut-in speed of 1.7 m/s. Wind tunnel experiments revealed that SWEPT has rated power output of 1 W at 4.0 m/s, and it is capable of producing power output up to 9.3 W at wind speed of 10 m/s. The study was further extended to develop a piezoelectric wind turbine which operates below 2.0 m/s wind speed. The piezoelectric wind turbine of overall dimension of 100mm x 78mm x 65mm is capable of producing peak electric power of about 450 microwatt at the rated wind speed of 1.9 m/s.
Master of Science

This report starts discussing a number of possible risk analysis methods related to five challenges identified by SINTEF within offshore renewable wind energy industry, and it ends up with case studies on two challenges by testing SPAR-H method and proposing risk reducing measures. I answer to all the questions, which are defined in the thesis assignment, by first selecting all the five safety challenges. I consider different risk analysis techniques and suggest a few of them for each individual challenges in a tabular fashion. I describe the proposed risk analysis techniques with their strengths and limitation and discuss, to a considerable extent, how they can be related to the challenges. The risk analysis techniques I suggested includes both technical and human error related methods. The technical related methods are based on some available risk analysis methods which are broadly acceptable in different applications. The human error analysis techniques, which have been practiced in nuclear industry, are the main focus in this report as it is believed that the techniques could be applicable in the offshore wind firm industry.Among the different challenges in HSE offshore wind farm operation, two challenges: collision (between the vessel and the wind turbine) and Access or egress from/to the offshore installation are presented as the main important part in the report. Because accident is most likely to happen when personnel transfer is required. Possible human errors and probability of accident due to those errors are broadly discussed. Possible risk-reducing measures to reduce the identified human errors and recommendation which may prevent the potential accident are discussed at the end of the report

Purpose/aim The aim is to explore which price policy of the Chinese wind power is the most suitable for the market. Design/methodology/approach Data has been collected through questionnaires. The analysis includes the statistical test in form of chi-square. Additionally the whole thesis followed the onion process put forward by Saunders. Findings The analysis showed that the price policy which is based on the local price of coal is more suitable for the market than the price policy decided by concession projects. Originality/value An original idea is given the relationship between ages, education levels and two policies. Further, the empirical data is collected from a comprehensive online-forum, so that the samples are randomly selected. The data shows that the businesses which want to enter the Chinese wind power market should choose the price policy which is based on the local price of coal. This choice should be useful in the real life.

Due to increasing concerns for global climate change, onshore and offshore wind energy technologies have stimulated a tremendous interest worldwide, and are considered as a viable solution to mitigate the environmental impacts related to electricity generation. Although wind energy technologies have been considered as one of the cleanest energy sources, they have a wide range of direct and indirect environmental impacts when the whole supply chain is considered. This study aims to quantify the direct and indirect environmental impacts of onshore and offshore wind power technologies by tracing all of the economy-wide supply chain requirements. To accomplish this goal, we developed a comprehensive hybrid life cycle assessment (LCA) model in which process-based LCA model is combined with the economic input-output (EIO) analysis. The analysis results show that on average, concrete and steel and their supply chains are responsible for 37% and 24% of carbon footprint, consequently. On average, offshore wind turbines produce 48% less greenhouse gas emissions per kWh produced electricity than onshore wind turbines. For the onshore wind turbines, concrete, aggregates, and crushed stone approximately consume 95% of total water in this construction phase. On the other hand, concrete, lead, copper, and aggregate are responsible for around 90% of total water for the offshore wind turbines. It is also found that the more capacity the wind turbine has, the less environmental impact the wind turbine generates per kWh electricity. Moreover, based on the economic and environmental impacts of studied wind turbines and also three more nonrenewable energy sources, this study develops a decision making framework to understand the best energy source mix for a building in the state of Florida. This framework accounts for the uncertainty in the input material by deploying a Monte Carlo simulation approach. The results of decision making framework show that natural gas is a better option among nonrenewable sources. On the other hand, V90-3.0 MW offshore wind turbine is the best source of energy among renewable energy sources for a building. The findings of this research are critical for policy makers to understand the direct and indirect environmental impacts of different onshore and offshore wind energy systems. Also this study furnishes the decision maker with a range of possible energy mixes based on different economic and environmental weights.
M.S.C.E.
Masters
Civil, Environmental, and Construction Engineering
Engineering and Computer Science
Civil Engineering

The Climatic Wind Tunnel (CWT) is a facility used by the motor industry to test vehicles under climatic extremes without the need for expensive overseas test programs. This work focuses on the application of computer simulation to the Heating Ventilation and Air Conditioning (HVAC) plant that makes up a CWT facility. The objective being to reduce its operational costs through the identification of energy saving operational strategies. When in operation the CWT has a peak power consumption of 3MW. The implementation of any measures that would reduce this peak load would give rise to considerable savings in the operating costs of the facility. Computer simulation is an accepted technique for the study of systems operating under varying load conditions. Simulation allows rapid analysis of different strategies for operating plant and the effectiveness of achieving the desired effect without compromising the buildings performance. Models for the components of the CWT have been developed and coded in Neutral Model Format. These models have then been linked together in a modular simulation environment to give a model of the complete plant. The CWT plant naturally decomposesin to four major subsystems these being the test chamber, the soakroom, air make-up and refrigeration system. Models of all the primary and secondary HVAC plant are described as is how they constitute the systems that make up the CWT. Validation tests for individual components as well as for the systems have been carried out. To illustrate the potential of the application of computer simulation into finding improved modes of operation that would reduce the energy consumption of the facility, four studies have been carried out. The studies involve the possibility of scheduling the operation of condenser fans as a function of refrigeration load and outside ambient temperature, methods for the pre-test conditioning of a vehicle, a reduction in the secondary refrigerant flow temperature and an increase in the thickness of the insulated panels from which the facility is constructed. The studies carried out showed that there was potential for moderate energy savings to be made in the operation of the facility and that extended simulation runs would allow for the in-depth assessment of a large range of possible modes of plant operation in order to identify the areas where the greatest savings are possible.

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Finance from the NOVA – School of Business and Economics
At the beginning of 2007, EdP, a Portuguese electricity utility was studying the potential acquisition of Horizon Wind Energy. Owned by Goldman Sachs, Horizon was a relevant player in the wind energy industry with capacity installed in USA. Requiring that EdP more than doubles its investments in renewables until 2010, this consolidation move would place the company as the 4th largest operator in the world.. Governmental support is just one of the factors that has to be analyzed in this deal, since the strategic implications and risks involved may determine the approval or refusal to go forward with the acquisition, and the price to be paid for the American company.

In this thesis, probability theory and risk analysis are used to determine the riskof wind energy stocks. Three stocks of wind energy companies and three stocksof technology companies are gathered and risks are compared. Three difffferent riskmeasures: variance, value at risk, and conditional value at risk are used in this thesis.Conclusions which has been drawn, are that wind energy company stock risks arenot signifificantly lower than the stocks of other companies. Furthermore, optimalportfolios should include short positions of one or two of the energy companies forthe studied time period and under the difffferent risk measures.

L’énergie éolienne, l’une des énergies renouvelables les plus compétitives, est considérée comme une solution qui remédie aux inconvénients de l’énergie fossile. Pour une meilleure gestion et exploitation de cette énergie, des prévisions de sa production s’avèrent nécessaires. Les méthodes de prévisions utilisées dans la littérature permettent uniquement une prévision de la moyenne annuelle de cette production. Certains travaux récents proposent l’utilisation du Théorème Central Limite (TCL), sous des hypothèses non classiques, pour l’estimation de la production annuelle moyenne de l’énergie éolienne ainsi que sa variance pour une seule turbine. Nous proposons dans cette thèse une extension de ces travaux à un parc éolien par relaxation de l’hypothèse de stationnarité la vitesse du vent et la production d’énergie, en supposant que ces dernières sont saisonnières. Sous cette hypothèse la qualité de la prévision annuelle s’améliore considérablement. Nous proposons aussi de prévoir la production d’énergie éolienne au cours des quatre saisons de l’année. L’utilisation du modèle fractal, nous permet de trouver une division ”naturelle” de la série de la vitesse du vent afin d’affiner l’estimation de la production éolienne en détectant les points de ruptures. Dans les deux derniers chapitres, nous donnons des outils statistiques de la détection des points de ruptures et d’estimation des modèles fractals
The wind energy, one of the most competitive renewable energies, is considered as a solution which remedies the inconveniences of the fossil energy. For a better management and an exploitation of this energy, forecasts of its production turn out to be necessary. The methods of forecasts used in the literature allow only a forecast of the annual mean of this production. Certain recent works propose the use of the Central Limit Theorem (CLT), under not classic hypotheses, for the estimation of the mean annual production of the wind energy as well as its variance for a single turbine. We propose in this thesis, an extension of these works in a wind farm by relaxation of the hypothesis of stationarity the wind speed and the power production, supposing that the latter are seasonal. Under this hypothesis the quality of the annual forecast improves considerably. We also suggest planning the wind power production during four seasons of the year. The use of the fractal model, allows us to find a "natural" division of the series of the wind speed to refine the estimation of the wind production by detecting abrupt change points. Statistical tools of the change points detection and the estimation of fractal models are presented in the last two chapters

The research topic is developping a power converting interface for the novel FLEHAP wind energy harvester allowing the produced energy to be used for powering small wireless nodes. The harvester’s electrical characteristics were studied and a strategy was developped to control and mainting a maximum power transfer. The electronic power converter interface was designed, containing an AC/DC Buck-Boost converter and controlled with a low power microcontroller. Different prototypes were developped that evolved by reducing the sources of power loss and rendering the system more efficient. The validation of the system was done through simulations in the COSMIC/DITEN lab using generated signals, and then follow-up experiments were conducted with a controllable wind tunnel in the DIFI department University of Genoa. The experiment results proved the functionality of the control algorithm as well as the efficiency that was ramped up by the hardware solutions that were implemented, and generally met the requirement to provide a power source for low-power sensor nodes.