<p>  </p> <p>In this study, we aimed to explore the potential of integrating wind turbines into tall buildings to harness wind energy in urban areas. Advanced computer simulations will be used to analyze the complex wind patterns and turbulence around tall buildings. We will also study the optimization of wind turbine placement to maximize energy production. We focus on two types of wind turbines, the savonius and a modified savonius, using the Myring formula. We evaluated their performance in turbulent urban areas using computational fluid dynamics simulations. The simulations will also help us understand the wind flow behavior around tall buildings, informing wind turbine placement optimization.</p> <p>Our findings contribute to the understanding of urban wind energy production. This may lead to further advancements in wind turbine design and application in urban environments, promoting sustainable and clean energy production in densely populated areas.</p> <p>We also evaluate the economic feasibility of wind power as an energy source and its potential for commercial applications. Our study's insights are significant for wind energy research, urban planning, and sustainable energy production in cities.</p> <p>To achieve our objectives, we will use state-of-the-art computational tools such as the ANSYS Fluent Student software and the Steady Reynolds Averaged Navier-Stokes (SRANS) K-ε model and K-ω SST models for simulating wind flow around tall buildings.</p> <p>In summary, the goal of this research is to develop a methodology for integrating wind turbines into tall urban buildings to harness wind energy potential. This will contribute to the understanding of urban wind energy production and its economic feasibility for commercial applications.</p>

Given the bleak current and projected global climate trends, society is transitioning the energy systems that we rely upon away from fossil fuel based systems to reduce global CO2 emissions. There are now well-established technologies for providing renewable electricity at utility scales, such as wind turbines and solar panels, being deployed at an ever increasing pace. However, solutions for decarbonizing other sectors where fossil fuels are harder to replace are still needed. Current strategies for reducing fossil fuel use in these sectors rely on replacing them with synthetic fuels instead are produced using renewable electricity, and can therefore be part of a net-zero emissions cycle. The focus of this thesis is to examine a novel class of wind energy systems suitable for powering these fuel synthesis processes. Alternative applications of the proposed systems include powering direct air CO2 capture systems to support negative emissions technology efforts. This work develops and presents numerical models for concepts hereafter referred to as mobile offshore wind energy systems (MOWESs). A MOWES is a wind energy system that operates offshore and is not intended to remain stationary during operation. MOWESs would operate far from shore, harnessing a part of the wind resource that would not otherwise be usable. No full- or large-scale MOWES has yet been developed, and there is little work on developing these concepts, even within academia. Steady-state power performance models of two MOWES concepts, namely unmoored floating offshore wind turbines and energy ships, are developed to support further research in this field. Model results suggest that each concept has unique pros and cons and no conclusion can be drawn as to which technology is more effiient overall. A key conclusion of this work is that unmoored floating wind turbines can generate more power by sailing at a constant speed rather than holding station. We also conclude that unmoored floating wind turbines designed for downwind operation can produce as much power as conventional stationary wind turbines given sufficiently high wind speeds. Further work must examine whether the advantages of these technologies are exploitable given realistic wind conditions and when considering the complicated dynamics of the system. / Graduate / 2023-08-09

This thesis demonstrates how small wind turbines can contributeto a greener planet by using wind energy to generateelectrical power. It compares the conventional PIDcontroller with the Fuzzy PID controller, implemented ina small wind turbine that was constructed using variousmachines. The concept of changing the gain parameters of the PIDcontroller with fuzzy logic, depending on the wind directionfor greater power generation, is explained and tested. This,with usage of a DC-motor that gets an output signal fromthe system which reads input values from an encoder anda wind vane. The construction included a powertrain inwhich a transmission, roller bearings and shafts were implementedin the yaw mechanism. The tests resulted in showing that the Fuzzy PID controllerperformed better, minimizing the error, when theerror between the wind turbine and the wind itself, wassmall. The power generation was also increased when utilizingthe Fuzzy PID controller. However, the PID controllerperformed similar to the Fuzzy PID controller whenexposed to larger errors. / Det här arbetet visar hur små vindkraftverk kan bidra tillen grönare planet genom att omvandla vindenergi till elektriskenergi. Det beskriver jämförelsen mellan den vanligtförekommande PID regulatorn och den suddiga PID regulatorn,implementerad i ett litet vindkraftverk som konstruerades med hjälp av flertalet maskiner. Konceptet att ändra på parametrarna i PID regulatorn med hjälp av suddig logik, beroende på vindriktningen, förklaras och testas med syfte att generera energi. Dettamed hjälp av en DC-motor som får utsignaler från systemet som läser insignaler från en encoder och en vindflöjt. Konstruktionen av rotatonsmekanismen innehöll implementation av en växel, kullager och axlar. Testresultaten visade att den suddiga PID regleringenvar bättre på att minimera felet, när felet mellan vindkraftverket och vinden var litet. Även vid generering av energi,visade det sig att den suddiga PID regleringen presterade bättre. Likväl presterade PID regulatorn på samma nivå som den suddiga, när felet var större.

Demands for sustainable energy have resulted in increased interest in wind turbines. Thus, despite widespread economic difficulties, global installed wind power increased by over 20% in 2011 alone. Recently, magnetic bearing technology has been proposed to improve wind turbine performance by mitigating vibration and reducing frictional losses. While magnetic bearing has been shown to reduce friction in other applications, little data has been presented to establish its effect on vibration and friction in wind turbines. Accordingly, this study provides a functional method for experimentally evaluating the effect of a magnetic bearing on the vibration and efficiency characteristics of a wind turbine, along with associated results and conclusions. The magnetic bearing under examination is a passive, concentric ring design. Vibration levels, dominant frequency components, and efficiency results are reported for the bearing as tested in two systems: a precision test fixture, and a small commercially available wind turbine. Data is also presented for a geometrically equivalent ball bearing, providing a benchmark for the magnetic bearing’s performance. The magnetic bearing is conclusively shown to reduce frictional losses as predicted by the original hypothesis. However, while reducing vibration in the precision test fixture, the magnetic bearing demonstrates increased vibration in the small wind turbine. This is explained in terms of the stiffness and damping of the passive test bearing. Thus, magnetic bearing technology promises to improve wind turbine performance, provided that application specific stiffness and damping characteristics are considered in the bearing design.

This thesis report outlines the creation of a MATLAB tool to design reversible machines that can function as both wind turbines and as agricultural frost protection fans. Frost protection fans are used to prevent crop loss during radiative freeze events during which a temperature inversion is present. Such a dual-purpose machine fundamentally has the constraint that it must use symmetric airfoils, so a suite of tools for automatically designing an optimized wind turbine blade with symmetric airfoils using the Blade Element Momentum (BEM) theory approach is presented. The BEM code is then re-derived and adapted for use with a frost protection fan, which is analogous to a propeller at zero free-stream windspeed. The relative performance of a blade operating in fan mode is investigated using a turbulent jet entrainment model to predict the time-averaged temperature rise provided by the fan during a thermal inversion event. With these tools, an optimal configuration of blade pitch angle, rotor tilt angle, and tower height can be found for a given wind turbine blade. The models are incorporated into a cohesive program with a graphical user interface. The feasibility of such machines is found to depend heavily on the wind resource at a given site.

Researchers from Uppsala University have carried out a project with a vertical axis wind turbine (VAWT). This was designed for 12 kW. An extension to this project is to be carried out where a counter-clockwise rotating turbine is to be added. This means that two rotations are created and that a solution for the generator needs to be implemented so that the different rotations can be turned into electrical power. The new project is intended to function as a Counter Rotational Wind Turbine and result in a generator with a rated output of 30 kW. The idea with the addition of a counterclockwise rotating part is to double the electrical power extracted by the alternator without an increase in RPM. The objective of this project will be to investigate the design of a generator whose stator and rotor both rotate in opposite directions. The aim is to theoretically design such a generator and find out suitable parameters for it. During this process, the aim is also to gain a broad and clear understanding of generators in general and test whether Aluminum can be used in the construction. To test and explore the theory around CRWT, two generators of 10 kW and 30 kW respectively will be created based on the Rutger generator. The Rutger generator is the one used in the project for a 12 kW VAWT. Two generators are created to explore how a generator can be scaled up/down in power. The 10 kW generator will then be drawn in the program Solidworks to evaluate the mechanical design.The generators were first simulated in the program KALK, which is a program created by researchers at Uppsala University. This software performs calculations by invoking the program ACE and using FEM to calculate various parameters of generators. The 10 kW generator was first created from a file containing the Rutgers parameters. After optimizations, the 30 kW generator was created based on the 10 kW file. After simulations in Solidworks and KALK, it was found that a generator that theoretically works as a CRWT has been created and is stable. It was also determined that a more comprehensive feasibility study is required to succeed with a mechanical design for a CRWT and not theoretical. Aluminum was a sustainable material for the stator frame based on the results from FEMbut may need further testing.

Wind turbine efficiency typically focuses on the shape, orientation, or stiffness of the turbine blades. In this thesis, the focus is instead on using static fixed airfoils in proximity to the wind turbine to control the airflow coming out of the turbine. These control devices have three beneficial effects. (1) They gather air from “higher up” where the air is moving faster on average (and therefore has more kinetic energy in it). (2) They throw the used (and slowed down air) downwards. This means that any turbines in the wind farm behind the lead turbines do not get “stale” air. (3) These control devices provide a large stabilizing lifting force for floating off-shore turbines. In this study, Reynolds-Averaged Navier-Stokes (RANS) simulations of an aligned array of two wind turbines along with various designs of these control devices is studied. The recovery in the velocity at the inlet plane of downstream turbine due to the controlled flow facilitated by these devices is measured with respect to the average streamwise wind velocity at the inlet plane of upstream turbine. A customized numerical solver was written in C++ using Opensource Field Operation And Manipulation (OpenFOAM) to model the turbines as actuator discs with axial induction and to generate an inlet velocity field similar to a turbulent atmospheric boundary layer (ABL). All the design configurations use a streamlined (airfoil shaped) structure, at an angle of attack carefully selected to prevent flow separation depending upon its location around the turbine. For strong wake displacement, the devices are placed in proximity to the upstream wind turbine so as to facilitate a substantial downwash of the faster wind from upper layers of the ABL and at the same time deflect the wake out of the way of the downstream turbine. Also, the pressure coefficient across the upstream turbine augmented with these devices can sometimes become more negative than a bare turbine, which in turn increases the mass flow rate of air passing through it, thereby also increasing the leading turbine’s efficiency slightly.

The global market for wind energy is expanding rapidly, and in the last decade, Sweden has constructed thousands of wind turbines. The high installation pace suggests that a similarly rapid decommissioning rate is to be anticipated in the near future, notwithstanding the small number of turbines that have been retired thus far. There will be serious questions about the viability of wind power as a clean energy option if the decommissioned material by unfunctional turbines is not managed in a proper manner. The purpose of this research is to provide the distribution of Swedish installed wind turbine with the aspect of age, brand &amp; model, hub height &amp; rotor diameter, and nameplate capacity and also a reliable estimate of the total amount of decommissioned material that will be produced by wind turbines in Sweden over the next two decades. The results will represent to current characteristic of an industry to benefit the operation &amp; maintenance activity and wind industry market research. Moreover, this will also help the waste management sector prepare for the inevitable increase in decommissioned material. The estimates are based on the installation dates, rotor diameter and other pertinent data included in vbk.lansstyrelsen.se, a Swedish national wind turbine map service. Applying the available data set with logarithmic function of rotor diameter and material fraction technique, the quantity of steel, iron, copper,aluminium, blade material, and electronics were generated. The material of each turbine is considered to be dismantled as wastes at 20 years after the installation date due to the industry average and comparison with empirical facts. As the results, the distributions show that most of Swedish wind turbines were installed between 2007 and 2016 and the most popular rated capacity ranged between 2 MW to 3 MW. Furthermore, the biggest market share belonged to Vestas, Enercon, and Siemens, respectively. The forecasted numbers reveal a large increase in decommissioned material weights year by year, and the blade material end-of-life management is the key concern when comparing the estimated number to Sweden's waste management capacity. Limitations associated with the suggested methodology and adopting data set are presented and discussed.

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