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

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Increasing energy demand and carbon emissions have driven the development of alternative energy solutions. One promising technology is wind energy. Wind energy technology developments has advanced substantially since the 1980s. Offshore wind turbines have become a major research focus, due to the promising offshore wind resource. However, challenges in offshore wind energy have arisen due to the additional wave loading and strong wind loads. Structural control systems have been implemented and researched in order to decrease dynamic response of these systems. The previous studies were successful at decreasing fatigue loads in the tower and support structure of offshore wind turbines. Giving these results, it is still unknown if the reduced loading enabled by structural control systems can allow for reduced material costs in the major structural components. This research examines on an offshore wind turbine's tower-monopile structure by adding several configurations of passive tuned mass dampers, while simultaneously reducing the thickness of the structure in order to reduce costs. A range of candidate tower-monopile systems are created, and simulated in FAST-SC with and without passive tuned mass dampers. Fatigue and ultimate loads are calculated and analyzed. A variety of design criteria are considered including fatigue and ultimate loads, as well as local and global buckling. The results demonstrate that the tower-monopile thickness may be reduced up to 6.2% and still satisfy all design criteria.

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This thesis introduces a design optimization methodology that is based on minimizing the Cost of Energy (COE) of a Horizontal Axis Wind Turbine (HAWT) that is to be operated at a specific wind site. In the design methodology for the calculation of the Cost of Energy, the Annual Energy Production (AEP) model to calculate the total energy generated by a unit wind turbine throughout a year and the total cost of that turbine are used. The AEP is calculated using the Blade Element Momentum (BEM) theory for wind turbine power and the Weibull distribution for the wind speed characteristics of selected wind sites. For the blade profile sections, either the S809 airfoil profile for all spanwise locations is used or NREL S-series airfoil families, which have different airfoil profiles for different spanwise sections, are used,. Lift and drag coefficients of these airfoils are obtained by performing computational fluid dynamics analyses. In sample design optimization studies, three different wind sites that have different wind speed characteristics are selected. Three scenarios are generated to present the effect of the airfoil shape as well as the turbine power. For each scenario, design optimizations of the reference wind turbines for the selected wind sites are performed the Cost of Energy and Annual Energy Production values are compared.

Appréhender la question de l'insertion paysagère des éoliennes suppose la détermination préalable des objets juridiques étudiés. Sous les hospices de la notion de « patrimoine commun de la nation », éoliennes et paysages apparaissent ainsi comme des sœurs ennemies. Cette conflictualité est consommée lorsque l'article L. 110-1 du Code de l'environnement dispose que la protection des paysages est d'intérêt général autant que l'est la mise en valeur des ressources naturelles. L'antagonisme postulé des deux notions doit cependant être nuancé en ce que le juge administratif tient le rôle d'arbitre dans les conflits nés de ce que les préoccupations paysagères viennent limiter l'implantation des constructions éoliennes. Alors que ce rapport de force s'apprête à gagner le contentieux spécial des installations classées, le contentieux des permis de construire éolien a été le terrain fertile et propice de l'émergence d'une démarche objective orientant l'appréciation qualitative et donc a priori subjective de l'atteinte aux paysages. Le contentieux des permis de construire éolien a également rendu possible le dépassement du contrôle de l'atteinte aux paysages que la doctrine présente classiquement comme un contrôle dissymétrique, par la formalisation d'un contrôle du bilan paysager des constructions éoliennes pouvant symboliser l'armistice de cet affrontement infécond. / In order to understand the legal bond between wind turbines and landscapes, preliminary elements must be understood. Regarding the legal concept of a « common national heritage », wind turbines and landscapes appear to be two enemy sisters. The conflict emerges when the Environmental Code presents both landscape protection and natural resource development within general interest. The two antagonising notions have to be refined, as the administrative judge appears to be an adjudicator between landscape protection and wind turbine implementation. Whilst the wind turbine landscape sensitivity question is about to integrate the litigation for Classified Installations for the Protection of the Environment, building permits litigation provides the basis for defining an objective method for the subjective definition of damage to the landscape. Using a litigation concerning building permits, a new method of landscape damage assessment has been drafted. Thus, a fine line balancing landscaping can be considered as the end of the war but not necessarily a victory in this meaningless standoff.

Master of Science / Department of Mechanical and Nuclear Engineering / Warren N. White / As traditional resources are becoming scarce, renewable energy is a recent topic receiving greater concern. Among the renewable energies, wind power is a very popular type of energy extracted from wind which is readily available in the environment. The use of wind power all over the world is receiving increased attention. Horizontal axis wind turbines are the most popular equipment for extracting power form the wind. One of the problems of using wind turbines is how to maximize the wind power capture. In this paper, a method for maximizing the rotor power coefficient of a wind turbine is proposed. Simultaneous Perturbation Stochastic Approximation (SPSA) is an efficient way for extremum seeking. It is different from the classical gradient based extremum seeking algorithms. For maximizing the rotor power coefficient, it only needs two objective function measurements to take a step toward the next extremum approximation. The one measurement SPSA is a modification of SPSA method developed in this work. Instead of using measurements of two positions occurring at random directions away from the current position, it uses the measurement of one position in a random direction and the measurement of the current position to estimate the gradient. Usually, the rotor power coefficient is not easily measurable. For speed regulation, a nonlinear robust speed controller is used in this work. The controller produces an estimate of the aerodynamic torque of wind turbine. The quality of this estimate improves with time. From that, a good estimate of power coefficient can be obtained. Simulations in MATLAB are executed with a model of a wind turbine based on its dynamic equations. From simulations, it can be seen that the one measurement SPSA method works very well for the wind turbine. It changes the tip speed ratio and blade pitch simultaneously, and the power coefficient reaches its maximum value quickly in a reliable manner. The power capture optimization is then implemented in FAST, a turbine simulation model created by NREL which is used to test the 5MW NREL reference turbine. From the results, it is evident that the wind turbine reaches the maximum power coefficient rapidly.

This thesis addresses the development of industries manufacturing in the renewable energy sector. As the most mature of the renewable energy technologies, it specifically assesses the development of the wind turbine manufacturing industry up to the present in order to address what lessons may be learned for the future development of the industry and for other renewable energy industries. Data is presented in the form of a number of case studies which detail the comparative successes of Denmark, Germany, Spain and the UK in encouraging the growth of wind turbine industries. Three areas of study are identified, and the data collected in the case studies applied to each. Firstly, the question of whether it is still possible for countries to stimulate national industries to successfully gain entry to the wind turbine manufacturing industry. Applying the historical data in the context of a typological theory on entrepreneurial success with regard to industrial phase, it is argued that such entry is still possible. The remaining two areas of study are linked in that they both address what lessons might be learned from the international development of the wind turbine manufacturing industry in order for the UK to replicate the success of other nations. The first of these areas specifically addresses how lessons from elsewhere might enable UK access to the wind turbine manufacturing industry. The second area addresses the extent to which experiences in the wind turbine industry might provide lessons for entrants to the industries of newer, less mature renewable energy technologies.

This Thesis aims to assess the reliability of turbulence models in predicting the flow fields around the horizontal axis wind turbine (HAWT) rotor blades and also to improve our understanding of the aerodynamics of the flow field around the blades. The simulations are validated against data from the NREL/NASA Phase VI wind turbine experiments. The simulations encompass the use of fourteen turbulence models including low-and high-Reynolds-number, linear and non-linear eddy-viscosity models and Reynolds stress models. The numerical procedure is based on the finite-volume discretization of the 3D unsteady Reynolds-Averaged Navier-Stokes equations in an inertial reference frame with the sliding mesh technique to follow the motion of the rotor blades. Comparisons of power coefficient, normalised thrust, local surface pressure coefficients (CP) and the radial variation of the section average of normal force coefficients with published experimental data over a range of tip-speed ratios, lead to the identification of the turbulence models that can reliably reproduce the values of the key performance indicators. The main contributions of this study are in establishing which RANS models can produce quantitatively reliable simulations of wind turbine flows and in presenting the flow evolution over a range of operating conditions. At low (relative to the blade tip speed) wind speeds the flow over the blade surfaces remains attached and all RANS models return the correct values of key performance coefficients. At higher wind speeds there is circumferential flow separation over the downwind surface of the blade, which eventually spreads over the entire surface, Moreover, within the separation bubble the centrifugal force pumps the flow outwards, which at the higher wind speeds suppresses the formation of the classical tip vortices. More refined RANS models which do not rely on the linear effective viscosity approximation generally lead to more reliable predictions over this range of higher wind speeds. In particular the Gibson-Launder version of the Reynolds stress transport model and the high-Re versions of the Lien et al non-linear k-ε produce consistently reliable simulations over the entire range of wind speeds. By contrast some popular linear effective viscosity models, like the SST (k-ω) and the v^2-f, perform the poorest over this complex flow range. Finally all RANS models are also able to predict the dominant (lowest) frequency of the pressure fluctuations and the non-linear effective viscosity models, the Launder and Shima version of RSM and the SST are also able to return some of the higher frequencies measured.