Search Results

Wind Harvest analyzed the San Gorgonio Pass Wind Resource Area using publicly available location information and UL’s Windnavigator. We found that the area could add 3,136 MWs of Wind Harvester type turbines to the existing 682 MWs of propeller-type turbines currently installed. Based on the mid-level wind speeds in the zone, this level of buildout would produce 10,040 GWh of electricity per year. The existing wind farms produce 2,661 GWh of electricity per year.

3D simulation of the vertical axis wind turbines

Author: Michal Petruzela, Vojtech Blazek

Publication: IEEE

Year Published: 2017

California, Density, H-Type, Horizontal Axis Wind Turbines, North America, Solano County, Solano Wind Resource Area, Synergy with Tall and Short Turbines, Vertical Axis Wind Turbines, Wind Farms

Computational fluid dynamics (CFD) is appropriate method to analyse aerodynamic flow in wind turbine. This is why we choose this method to compare static torque characteristics of two vertical axis wind turbines (VAWT), one with straight blade and the other one with helical blade. Analyses are realized by use of Ansys CFX software. At first, three-dimensional (3D) simulations of straight blade turbine with different meshes are carried out. To determine how much mesh parameters affect the accuracy of result and computational time. Then we perform 3D simulations of helical blade turbine and compare its results with straight blade one.

5 GW of short turbines could be added to the Solano Wind Resource Area

Publication: Wind Harvest International

Year Published: 2023

California, Density, H-Type, Horizontal Axis Wind Turbines, Kern County, North America, Synergy with Tall and Short Turbines, Tehachapi Wind Resource Area, Vertical Axis Wind Turbines, Wind Farms

Wind Harvest analyzed the Solano Wind Resource Area using publicly available location information and UL’s Windnavigator. The report concluded that the area could add 4,989 MWs of Wind Harvester type turbines to the existing 1,021 MWs of propeller-type turbines currently installed. Based on the mid-level wind speeds in the zone, this level of buildout would produce 13,572 GWh of electricity per year. The existing wind farms produce 3,827 GWh of electricity per year.

5.7 GW of short turbines could be added to the Tehachapi Wind Resource Area

Publication: Wind Harvest International

Year Published: 2023

Wind Harvest analyzed the Tehachapi wind resource area using publicly available location information and UL’s Windnavigator. We found that the area could add 5,700 MWs of Wind Harvester type turbines to the existing 3,263 MWs of propeller-type turbines currently installed in Kern County. Based on the mid-level wind speeds in the zone, this level of buildout would produce 18,364 GWh of electricity per year. The existing wind farms produce ~11,000 GWh of electricity per year.

A comparison of finite element predictions and experimental data for the forced response and the DOE 100kW vertical axis wind turbine

Author: Erik Mollerstrom, Fredric Ottermo, Jonny Hylander, Hans Bernhoff

Publication: Sandia National Laboratories

Year Published: 1984

A specialized finite element capability has been developed to predict dynamic structural response of the vertical axis wind turbine (VAWT). This report is concerned with evaluating this finite element analysis technique. This achieve this, several types of experimental data taken from the DOE 100kW rotor are compared with predictions. These data include parked rotor natural frequencies, very low wind centrifugal and gravitational load response, and vibratory response from wind loads covering the rotor operational spectrum. Generally, the agreement between theory and experiment is very satisfactory. It is concluded that the analysis package is suitable for engineering design. Shortcomings observed in modeling accuracy are believed to be due primarily to inadequacies in blade aerodynamic load calculations.

A Comparison of Wake Measurements in Motor-Driven and Flow-Driven Turbine Experiments

Author: Daniel Araya, John Dabiri

Publication: Springer-Verlag Berlin Heidelberg

Year Published: 2015

We present experimental data to compare and contrast the wake characteristics of a turbine whose rotation is either driven by the oncoming flow or prescribed by a motor. Velocity measurements are collected using two-dimensional particle image velocimetry in the nearwake region of a lift-based, vertical-axis turbine. The wake of this turbine is characterized by a spanwise asymmetric velocity profile which is found to be strongly dependent on the turbine tip speed ratio (TSR), while only weakly dependent on Reynolds number (Re). For a given Re, the TSR is controlled.

A Free Wake Method For Vertical-Axis Wind Turbine Performance

Author: Horia Dumitrescu, Vladimir Cardos

Publication: ResearchGate

Year Published: 2014

The fatigue analysis of a wind turbine component typically uses representative samples of cyclic loads to determine lifetime loads. In this paper, several techniques currently in use are compared to one another based on fatigue life analyses. The generalized Weibull fitting technique is used to remove the artificial truncation of large-amplitude cycles that is inherent in relatively short data sets. Using data from the Sandia/DOE 34-m Test Bed, the generalized Weibull fitting technique is shown to be excellent for matching the body of the distribution of cyclic loads and for extrapolating the tail of the distribution. However, the data also illustrate that the fitting technique is not a substitute for an adequate data base.

A General Method for Fatigue Analysis of Vertical Axis Wind Turbine Blades

Author: Paul Veers

Publication: Sandia National Laboratories

Year Published: 1983

The fatigue life of wind turbine blades that are exposed to the random loading environment of atmospheric winds is described with random data analysis procedures. The incident wind speed and the stresses caused by these winds are expressed in terms of probability density functions, while the fatigue life vs stress level relationship is treated deterministically. This approach uses a “damage density function” to express fatigue damage as a function of wind speed. By examining the constraints on the variables in the damage density expression, some generalizations of the wind turbine fatigue problem are obtained. The area under the damage density function is inversely related to total fatigue life. Therefore, an increase in fatigue life caused by restricted operation in certain wind regimes is readily visualized. An “on parameter”, which is the percentage of total time at each wind speed that the turbine actually operates, is introduced for this purpose. An example calculation is presented using data acquired from the DOE 100-kW turbine program.

A historical review of vertical axis wind turbines rated 100 kW and above

Author: Erik Mollerstrom, Paul Gipe, Jos Beurskens, Fredric Ottermo

Publication: Renewable and Sustainable Energy Reviews

Year Published: 2019

This paper summarizes and introduces all vertical axis wind turbine (VAWT) projects where 100 kW or larger turbines have been installed. The basis for the review is both existing literature and personal correspondence with people once involved in the different developments. By citing the most relevant work for each project, the paper will also work as an information hub, making information on these projects more accessible. Since the 1970s, there have been several VAWT projects with installed turbines of significant size, either as attempts to commercialize VAWTs, or as university led research projects, or as a combination of the two. Most have involved Darrieus turbines built in North America during the 1980s. However, H-rotors, which have always been a favored concept in Europe, have seen a revival during the 2010s. The reason VAWTs have never fully challenged the success of the horizontal axis wind turbine (HAWT) is too broad a question to answer here. However, the reasons some VAWT projects have failed are addressed in this paper. Besides the fact that many of the prototypes had terminal failures, most of the installed medium or largescale VAWTs have to some extent had problems with metal fatigue and durability. Additionally, a lack of longterm interest from governmental or private funders, as well as the introduction of reliable HAWTs, was a recurring theme from those involved in VAWT development, regarding the reason VAWTs so far have failed to succeed.

A Low-Reynolds-Number, High-Angle-of-Attack Investigation of Wind Turbine Aerofoils

Author: S Worasinchai, G Ingram and R Dominy

Publication: J. Power and Energy

Year Published: 2011

This article describes an experimental, aerodynamic investigation of four aerofoils intended for small wind turbine applications. The aerofoils of these small machines (both horizontal and vertical axes) normally experience conditions that are quite different from large-scale machines due to smaller chord length and lower wind speed, resulting in significantly lower Reynolds numbers. They also operate with an unusually wide range of incidence angles (0° to 90° for horizontal axis and 0° to 360° for vertical axis). Four appropriate aerofoils were chosen for testing at three Reynolds numbers (65000, 90000, and 150000) through 360° incidence to cover almost all possible conditions that might be encountered by both types of turbines…

A Model for the Response of Vertical Axis Wind Turbines to Turbulent Flow Parts 1 and 2

Author: David Malcolm

Publication: Sandia National Laboratories

Year Published: 1988

This report describes a project intended to incorporate the effects of atmospheric turbulence into the structural .response of Darrieus rotor, vertical axis wind turbines. The basis of the technique is the generation of a suitable time series of wind velocities, which are passed through a double multiple streamtube aerodynamic representation of the rotor. The aerodynamic loads are decomposed into components of the real eigenvectors of the rotor and subsequently into full-power and cross-spectral densities. These modal spectra are submitted as input to a modified NASTRAN random load analysis and the power spectra of selected responses are obtained. This procedure appears to be successful. Results at zero…

A Modeling Approach to Infer the Effects of Wind Farms on Landscape Connectivity for Bats

Author: Federica Roscioni, Hugo Rebelo, Danilo Russo, Maria Laura Carranza, Mirko Di Febbraro, Anna Loy

Publication: Lanscape Ecol

Year Published: 2014

Miscellaneous, Synergy with Tall and Short Turbines

Little is known about the potentially disrupting effects of wind farms on the habitat connectivity of ﬂying vertebrates at the landscape scale. We developed a regional-scale model to assess the wind farm impact on bat migration and commuting routes. The model was implemented for the bat Nyctalus leisleri in a region of central Italy currently undergoing considerable wind farm development. A Species Distribution Model (SDM) for N. leisleri was generated using the MaxEnt algorithm based on 47 presence records (reduced to 19 after the autocorrelation procedure) and 10 environmental variables derived from topographic and land cover maps. We used the SDM to create a map of connectivity using the software…

A New Approach to Wind Energy

Author: John Dabiri

Publication: California Institute of Technology

This document is a slideshow put together by Dr. Dabiri that summarizes his work on small vertical axis wind turbines and their impacts on “planform kinetic flux”, energy density in wind farms and related issues. This is an excellent resources with plenty of figures and graphics that reviews much of his work up to the publication date.

A Numerical Study on a Vertical-Axis Wind Turbine with Inclined Arms

Author: Agostino De Marco, Domenico Coiro, Domenico Cucco, Fabrizio Nicolosi

Publication: University of Naples

Year Published: 2014

This work focuses on a particular type of vertical-axis wind turbine, in which a number of inclined arms with airfoil-shaped cross-sections are mounted to connect the principal blades to their hub. While the majority of the known studies on vertical-axis turbines is devoted to the role of principal blades, in most of the cases without taking into account other parts of the wind turbine, the objective of this work is to investigate the effect of uncommon arm geometries, such as the inclined arms. The inclined arms are known to have a potentially beneficial role in the power extraction from the wind current but, due to the complexity ofthe phenomena, the investigation on aerodynamics of this type of turbine is often impossible through analytical models, such as blade-element momentum theory. It turns out that adequate studies can only be carried out by wind tunnel experiments or CFD simulations. This work presents a methodical CFD study on how inclined arms can be used on a selected wind turbine configuration to harvest additional power from the wind. The turbine configuration, geometry, and some fundamental definitions are introduced first. Then an in-depth CFD analysis is presented and discussed.

A Retrospective of VAWT Technology

Author: Jerbert Sutherland, Dale Berg, and Thomas Ashwill

Publication: Sandia National Laboratories

Year Published: 2012

The study of Vertical-Axis Wind Turbine (VAWT) technology at Sandia National Laboratories started in the 1970’s and concluded in the 1990’s. These studies concentrated on the Darrieus configurations because of their high inherent efficiency, but other configurations (e.g., the Savonius turbine) were also examined. The Sandia VAWT program culminated with the design of the 34-m ‘Test Bed’ Darrieus VAWT. This turbine was designed and built to test various VAWT design concepts and to provide the necessary databases to validate analytical design codes and algorithms. Using the Test Bed as their starting point, FloWind Corp. developed a commercial VAWT product line with composite blades and an extended height-to-diameter ratio. The purpose of this paper is to discuss the design process and results of the Sandia 34-m VAWT Test Bed program and the FloWind prototype development program with an eye toward future off-shore designs. This paper is our retrospective of the design, analysis, testing and commercial process. Special emphasis is given to those lessons learned that will aid in the development of an off-shore VAWT.

A Review of Bird Control Methods at Airports

Author: Abd El-Aleem Saad Soliman Desoky

Publication: Sohag University

Year Published: 2014

Birds are a serious problem at airports threat to aviation safety. Since the early days of aviation, collisions of aircraft and birds have taken place, sometimes with fatal consequences Generally, the damage due to their size of the bird species involved, hunting behavior, and hovering/soaring habits. The combination of abundant food sources, open space, and availability of perching structures on airport grounds and near runway/taxiway areas provides ideal hunting opportunities for many raptors. Also, the behavior of bird species influences the risks, for instance flocking or certain migration…

A Review of Numerical Modelling of Multi-Scale Wind Turbines and Their Environment

Author: Katrina Calautit, Angelo Aquino, John Kaiser Calautit, Payam Nejat, Fatimeh Jomehzadeh and Ben Richard Hughes

Publication: Computation

Year Published: 2018

Global demand for energy continues to increase rapidly, due to economic and population growth, especially for increasing market economies. These lead to challenges and worries about energy security that can increase as more users need more energy resources. Also, higher consumption of fossil fuels leads to more greenhouse gas emissions, which contribute to global warming. Moreover, there are still more people without access to electricity. Several studies have reported that one of the rapidly developing source of power is wind energy and with declining costs due to technology and manufacturing advancements and concerns over energy security and environmental issues, the trend is predicted to continue. As a result, tools and methods to simulate and optimize wind energy technologies must also continue to advance. This paper reviews the most recently published works in Computational Fluid Dynamic (CFD) simulations of micro to small wind turbines, building integrated with wind turbines, and wind turbines installed in wind farms.

A Summary and Comparison of Bird Mortality from Anthropogenic Causes with an Emphasis on Collisions

Author: Wallace P. Erickson, Gregory D. Johnson, and David P. Young Jr.

Publication: USDA Forest Service

Year Published: 2005

California, Country-by-Country Resources, North America

We estimate that from 500 million to possibly over 1 billion birds are killed annually in the United States due to anthropogenic sources including collisions with human-made structures such as vehicles, buildings and windows, power lines, communication towers, and wind turbines; electrocutions; oil spills and other contaminants; pesticides; cat predation; and commercial fishing by-catch. Many of the deaths from these sources would be considered unlawful take under federal laws such as the Endangered Species Act, Migratory Bird Treaty Act, and the Bald and Golden Eagle Protection Act. In this paper, we summarize this literature and provide the basis for the mortality projections for many of the apparent significant…

Advanced Characterization of Wind Resources in Selected Focus Areas of California

Author: AWS Truepower

Publication: California Energy Commission

Year Published: 2010

Aeroacoustics of Darrieus Wind Turbine

Author: Johannes Weber, Stefan Becker, Christoph Scheit, Jens Grabinger and Manfred Kaltenbacher

Year Published: 2005

The objective of this paper is to validate two different numerical methods for noise prediction of the H-Darrieus wind turbine using a complementary approach consisting of experimental measurements and numerical simulations. The acoustic measurements of a model scale rotor were performed in an anechoic wind tunnel. This data is the basis for the validation of the computational aeroacoustic simulations. Thereby, we have applied two different numerical schemes for noise prediction using hybrid methods. As usual in hybrid aeroacoustic approaches, flow field and acoustic calculations are carried out in separate software packages.

Aeroacoustics Prediction of a Vertical Axis Wind Turbine Using Large Eddy Simulation and Acoustic Analogy

Author: Masoud Ghasemian, Amir Nejat

Publication: Energy

Year Published: 2015

Miscellaneous, Synergy with Tall and Short Turbines

Operating wind turbines generate tonal and broadband noises affecting the living environment adversely; especially small wind turbines located in the vicinity of human living places. Therefore, it is important to determine the level of noise pollution of such type of wind turbine installation. The current study carries out numerical prediction for aerodynamic noise radiated from an H-Darrieus Vertical Axis Wind Turbine. Incompressible LES (Large Eddy Simulation) is conducted to obtain the instantaneous turbulent flow field. The noise predictions are performed by the Ffowcs Williams and Hawking…

Aerodynamic Interference of Vertical Axis Wind Turbines

Author: R. Ganesh Rajagopalan , Ted L. Rickerl and Paul C. Klimas

Publication: Sandia National Laboratories

Year Published: 1990

Coupled Vortex Effect, Synergy with Tall and Short Turbines

The laminal flowfield and performance of clusters of two-dimensional vertical axis wind turbines are analyzed by idealizing the rotors as momentum sources. The flowfield dominated by the pressure field of the operating turbines is determined by solving the incompressible Navier-Stokes equations and mutual interference is observed to be elliptic in nature. Physical positioning of the turbines with respect to each other significantly affects the aerodynamic performance of the turbines. Several cases are examined starting with…

Aerodynamic Model of the Wind Harvest International Model 1500 Wind Turbine

Author: Dr. Ion Paraschivoiu (with comments by Robert N Thomas, Dr. Farooq Saeed, and Norbert V. Dy)

Publication: IOPARA, Inc.

Year Published: 2009

Coupled Vortex Effect, Synergy with Tall and Short Turbines

This report is a compilation of the aerodynamic analyses of the Wind Harvest International (WHI) wind turbines, Model WHI 530 and WHI 1500, in isolated and multiple configuration settings. The aerodynamic analyses were carried out by IOPARA Inc. as a contract project for WHI from October 2008 to May 2009. The aerodynamic analyses focused on the specific tasks as requested in the project proposal.

Aerodynamic Model of the Wind Harvest International Model 3000 Wind Turbine

Author: Dr. Ion Paraschivoiu (with comments by Robert N Thomas, Dr. Farooq Saeed, and Norbert V. Dy)

Publication: IOPARA, Inc.

Year Published: 2009

This report is a compilation of the aerodynamic analyses of the Wind Harvest International (WHI) wind turbine Model WHI 3000 at wind speeds < 7.15 m/s (16 mph) in isolated and multiple configuration settings. The aerodynamic analyses were carried out by IOPARA Inc. as a contract project for WHI from August 2009 to October 2009. The aerodynamic analyses focused on the specific tasks as requested in the project proposal.

Aerodynamic modeling of floating vertical axis wind turbines using the actuator cylinder flow method

Author: Zhengshun Chenga, Helge Aagaard Madsend, Zhen Gaoa, Torgeir Moan

Publication: Energy Procedia

Year Published: 2016

Recently the interest in developing vertical axis wind turbines (VAWTs) for offshore application has been increasing. Among the aerodynamic models of VAWTs, double multi-streamtube (DMST) and actuator cylinder (AC) models are two favorable methods for fully coupled modeling and dynamic analysis of floating VAWTs in view of accuracy and computational cost. This paper deals with the development of an aerodynamic code to model floating VAWTs using the AC method developed by Madsen. It includes the tangential load term when calculating induced velocities, addresses two different approaches to calculate the normal and tangential loads acting on the rotor, and proposes a new modified linear solution to correct the linear solution.

Aerodynamic Performance Prediction of Straight-Bladed Vertical Axis Wind Turbine Based on CFD

Author: L.X. Zhang, Y.B. Liang, X.H. Liu, Q.F. Jiao, J. Guo

Year Published: 2013

Miscellaneous, Synergy with Tall and Short Turbines

Numerical simulation had become an attractive method to carry out researches on structure design and aerodynamic performance prediction of straight-bladed vertical axis wind turbine, while the prediction accuracy was the major concern of CFD. Based on the present two-dimensional CFD model, a series of systematic investigations were conducted to analyze the effects of computational domain, grid number, near-wall grid, and time step on prediction accuracy. And then efforts were devoted into prediction and analysis of the overall flow field, dynamic performance of blades, and its aerodynamic forces. The calculated results agree well with experimental data, and it demonstrates that RNG k-ε turbulent model is great to predict the tendency of aerodynamic forces but with a high estimate value of turbulence viscosity coefficient. Furthermore, the calculated tangential force is more dependent on near-wall grid and prediction accuracy is poor within the region with serious dynamic stall. In addition, blades experience mild and deep stalls at low tip speed ratio, and thus the leading edge separation vortex and its movement on the airfoil surface have a significant impact on the aerodynamic performance.

Aerodynamic Simulation of Vertical-Axis Wind Turbines

Author: A. Korobenko, M.C. Hsu, I. Akkerman, Y. Bazilevs

Publication: J. Appl. Mech.

Year Published: 2014

Coupled Vortex Effect, Synergy with Tall and Short Turbines

Full-scale, 3D, time-dependent aerodynamics modeling and simulation of a Darrieus-type vertical-axis wind turbine (VAWT) is presented. The simulations are performed using a moving-domain finite-element-based ALE-VMS technique augmented with a sliding-interface formulation to handle the rotor-stator interactions present. We simulate a single VAWT using a sequence of meshes with increased resolution to assess the computational requirements for this class of problems. The computational results are in good agreement with experimental data. We also perform a computation of two side-by-side counterrotating VAWTs to illustrate how the ALE-VMS technique may be used for the simulation of multiple…

Aerodynamically Interacting Vertical-Axis Wind Turbines: Performance Enhancement and Three-Dimensional Flow

Author: Ian Brownstein, Nathaniel Wei and John Dabiri

Publication: Energies

Year Published: 2019

Aerodynamic, Computer Modeling, Synergy with Tall and Short Turbines, Turbine Wake

This study examined three-dimensional, volumetric mean velocity fields and corresponding performance measurements for an isolated vertical-axis wind turbine (VAWT) and for co- and counter-rotating pairs of VAWTs with varying incident wind direction and turbine spacings. The purpose was to identify turbine configurations and flow mechanisms that can improve the power densities of VAWT arrays in wind farms. All experiments were conducted at a Reynolds number ofReD=7.3×104. In the paired arrays, performance enhancement was observed for both the upstream and downstream turbines. Increases in downstream turbine performance correlate with bluff–body accelerations around the upstream turbine, which increase the incident freestream velocity on the downstream turbine in certain positions. Decreases in downstream turbine performance are determined by its position in the upstream turbine’s wake. Changes in upstream turbine performance are related to variations in the surrounding flow field due to the presence of the downstream rotor.For the most robust array configuration studied, an average 14% increase in array performance over approximately a50◦range of wind direction was observed. Additionally, three-dimensional vortex interactions behind pairs of VAWT were observed that can replenish momentum in the wake byadvection rather than turbulent diffusion. These effects and their implications for wind-farm design are discussed.

Aerodynamics of vertical-axis wind turbines in full-scale and laboratory-scale experiments

Author: Daniel Araya

Publication: California Institute of Technology

Year Published: 2016

Within a wind farm, multiple turbine wakes can interact and have a substantial effect on the overall power production. This makes an understanding of the wake recovery process critically important to optimizing wind farm efficiency. Vertical-axis wind turbines (VAWTs) exhibit features that are amenable to dramatically improving this efficiency. However, the physics of the flow around VAWTs is not well understood, especially as it pertains to wake interactions, and it is the goal of this thesis to partially fill this void. This objective is approached from two broadly different perspectives: a low-order view of wind farm aerodynamics, and a detailed experimental analysis of the VAWT wake.

Aeroelastic Stability Investigations

Author: Brian Owens, Daniel Griffith

Publication: Sandia National Laboratories

Year Published: 2014

A vertical-axis wind turbine (VAWT) rotor configuration offers a potential transformative technology solution that significantly lowers cost of energy for offshore wind due to its inherent advantages for the offshore market. However, several potential challenges exist for VAWTs and this paper addresses one of them with an initial investigation of dynamic aeroelastic stability for large-scale, multi-megawatt VAWTs. The aeroelastic formulation and solution method from the BLade Aeroelastic STability Tool (BLAST) for HAWT blades was employed to extend the analysis capability…

Aerolastic Effects in the Structural Dynamic Analysis of Vertical Axis Wind Turbines

Author: Donald Lobitz, Thomas Ashwill

Publication: Sandia National Laboratories

Year Published: 1986

Aeroelastic effects impact the structural dynamic behavior of vertical axis wind turbines (VAWTs) in two major ways. First, the stability phenomena of flutter and divergence are direct results of the aeroelasticity of the structure. Secondly, aerodynamic damping can be important for predicting response levels, particularly near resonance, but also for off-resonance conditions. The inclusion of the aero- elasticity is carried out by modifying the damping and stiffness matrices in the NASTRAN finite element code. Through the use of a specially designed preprocessor, which reads the usual NASTRAN input deck and adds appropriate cards to it, the incorporation of the aeroelastic effects has been made…

Aerolastic Modeling of Large Offshore Vertical-axis Wind Turbines: Development of Offshore Wind Energy Simulation Toolkit

Author: Brian Owens, John Hurtado, Joshua Paquette, Daniel Griffith, Matthew Barone

Publication: Sandia National Laboratories

Year Published: 1986

Alameda/Contra Costa Counties, California, Country-by-Country Resources, North America

The availability of offshore wind resources in coastal regions makes offshore wind energy an attractive opportunity. There are, however, significant challenges in realizing offshore wind energy with an acceptable cost of energy due to increased infrastructure, logistics, and operations and maintenance costs. Vertical-axis wind turbines (VAWTs) are potentially ideal candidates for offshore applications, with many apparent advantages over the horizontal-axis wind turbine configuration in the offshore arena. VAWTs, however, will need to undergo much development in the coming years. Thus, the Offshore Wind ENergy Simulation (OWENS) toolkit is being developed as a design tool for assessing innovative floating VAWT configurations.

Alameda and Contra Costa County Wind Map

Publication: NREL Wind Prospector

An Approach to the Fatigue Analysis of Vertical Axis Wind Turbine Blades

Author: Paul Veers

Publication: Sandia National Laboratories

Year Published: 1981

A cursory analysis of the stress history of wind turbine blades indicates that a single stress level at each wind speed does not adequately describe the blade stress history. A statistical description is required. Blade stress data collected from the DOE/ALCOA Low cost experimental turbines indicate that the Rayleigh probability density function adequately describes the distribution of vibratory stresses at each wind speed. The Rayleigh probability density function allows the distribution of vibratory stresses to be described by the RMS of the stress vs. time signal. With the RMS stress level described for all wind speeds, the complete stress history of the turbine blades is known. Miner’s linear cumulative damage rule is used as a basis for summing the fatigue damage overall operating conditions. An analytical expression is derived to predict blade fatigue life. Input to the blade life expression includes a basic blade S-N curve, RMS stress vs. wind speed data, the probability density function of vibratory stress and the probability density function which describes the wind speed distribution. The implications of the assumption and the limitations of this approach are discussed.

An Assessment of Wind Energy Potential for the Three Topographic Regions of Eritrea

Author: Teklebrhan Negash, Erik Mollerstrom, Fredric Ottermo

Publication: Energies

Year Published: 2020

Environmental Impacts, Shadow Flicker

This paper presents the wind energy potential and wind characteristics for 25 wind sites in Eritrea, based on wind data from the years 2000–2005. The studied sites are distributed all over Eritrea, but can roughly be divided into three regions: coastal region, western lowlands, and central highlands. The coastal region sites have the highest potential for wind power. An uncertainty, due to extrapolating the wind speed from the 10-m measurements, should be noted. The year to year variations are typically small and, for the sites deemed as suitable for wind power, the seasonal variations are most prominent in the coastal region with a peak during the period November–March. Moreover, Weibull parameters, prevailing wind direction, and wind power density recalculated for 100 m above ground are presented for all 25 sites. Comparing the results to values from the web-based, large-scale dataset, the Global Wind Atlas (GWA), both mean wind speed and wind power density are typically higher for the measurements. The difference is especially large for the more complex-terrain central highland sites where GWA results are also likely to be more uncertain. The result of this study can be used to make preliminary assessments on possible power production potential at the given sites.

An Introduction to Shadow Flicker and its Analysis

Author: Thomas Priestley

Publication: NEWEEP

Year Published: 2011

Coupled Vortex Effect, Synergy with Tall and Short Turbines

The alternating changes in light intensity that can occur at times when the rotating blades of wind turbines cast moving shadows on the ground or on structures.

Analysis of the Coupled Vortex Effect

Author: Ion Paraschivoiu

Publication: Wind Harvest International

Year Published: 2010

Analysis Of Three Selected Design Parameters Related To A Fixed-Pitch Straight-Bladed Vertical Axis Wind Turbine

Author: Mazharul Islam, Khaled Almohammadi, Yasir M. Shariff

Year Published: 2009

The fixed-pitch straight-bladed vertical axis wind turbine (SB-VAWT) is one of the simplest types of wind turbine. The overall cost of the SB-VAWT will mainly depend on judicious choice of multiple design parameters. An attempt has been made in this paper to analyze the influence of three design parameters related to smaller-capacity fixed-pitch SB-VAWT with the help of a computational scheme. The three design parameters are: (i) solidity, (ii) aspect ratio and (iii) blade pitching. Affect of these parameters are analyzed for a SB-VAWT equipped with a special purpose airfoil “MIVAWT1” which has been designed for a smaller-capacity fixedpitch SB-VAWT. It has been demonstrated in this paper that proper selections of these three parameters are important for a cost-effective smaller-capacity SB-VAWT which can be considered as a candidate for urban and off-grid rural applications.

Analytical methods in Vertical Axis Wind turbines

Author: Hong-Hieu Le

Publication: Vietnam Nat. U. Ho Chi Minh City

Year Published: 2017

Horizontal and vertical axis wind turbines (HAWTs and VAWTs) are two main kinds of wind turbine, which are the most popular way to receive energy from wind. By comparison, VAWTs have a number of advantages, but it is also complex in aerodynamics that research is needed. A code is developed based on Double multiple stream-tube and corrections of dynamic stall for Darrieus VAWTs. It is capable of estimating the output power versus different operating condition. The code is also validated with experimental data of many SANDIA Darrieus VAWT turbines.

Application of the Darrieus Vertical Axis Wind Turbine to Synchronous Electrical Power Generation

Author: J. F. Banas, E. G. Kadlec, W. N. Sullivan

Publication: Sandia National Laboratories

Year Published: 1975

This report suggests that the Darrieus vertical-axis wind turbine may be particularly well-suited for driving a synchronous generator in parallel with a synchronizing electrical power network. Aerodynamic characteristics of the Darrieus wind turbine can be such that no torque regulation mechanisms are required on the turbine, providing the generator is properly sized. Synchronization to maintain constant turbine rotational speed under any wind conditions is provided by the network.

Argentina Mid-Level Wind Resources in Wind Farms

A projected 950 megawatts (MW) of the wind farms in Argentina have mid-level wind speeds over 6.5 meters per second (m/s) at 15 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	1,247
MWs over 6.5m/s at 15m agl (projected)	963
% of wind farms over 6.5m/s at 15m agl	77.3%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Armenia Mid-Level Wind Resources in Wind Farms

A projected 3 megawatts (MW) of the wind farms in Armenia have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	3
MWs over 6.5m/s at 20m agl (projected)	3
% of wind farms over 6.5m/s at 20m agl	100%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Assessing Impacts of Wind-Energy Development on Nocturnally Active Bats and Birds

Author: Thomas Kunz, Edward Arnett, Brian Cooper, Wallace Erickson, Ronald Larkin, Todd Mabee, Michael Morrison, Dale Strickland, and Joseph Szewczak

Publication: J. Wildlife Management

Year Published: 2007

Our purpose is to provide researchers, consultants, decision-makers, and other stakeholders with guidance to methods and metrics for investigating nocturnally active birds and bats in relation to utility-scale wind-energy development. The primary objectives of such studies are to 1) assess potential impacts on resident and migratory species, 2) quantify fatality rates on resident and migratory populations, 3) determine the causes of bird and bat fatalities, and 4) develop, assess, and implement methods for reducing risks to bird and bat populations and their habitats.

Assessment of the Effects of Wind Turbines on Air Traffic Control Radars

Author: John Lemmon, John Carroll, Frank Sanders, Doris Turner

Publication: U.S. Department of Commerce, NTIA

Year Published: 2008

Country-by-Country Resources, Oceania

This technical report describes the results of a study exploring the effects of power-producing wind turbines on Federal Aviation Administration (FAA) air traffic control (ATC) radars. The study was performed to identify the extent to which these effects exist, and to identify mitigation techniques and parameters for such effects. The topics addressed in this report are: review of the current state of the literature on wind turbine effects on ATC radar performance; determination of criteria for recommended no-interference radii between ATC radars and wind turbines; determination of methodology…

Australia Mid-Level Wind Resources in Wind Farms

A projected 1,938 megawatts (MW) of the wind farms in Australia have mid-level wind speeds over 6.5 meters per second (m/s) at 15 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	8,296
MWs over 6.5m/s at 15m agl (projected)	1,938
% of wind farms over 6.5m/s at 15m agl	23.4%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Austria Mid-Level Wind Resources in Wind Farms

A projected 42 megawatts (MW) of the wind farms in Austria have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	2,812
MWs over 6.5m/s at 20m agl (projected)	42
% of wind farms over 6.5m/s at 20m agl	1.4%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Avian Hearing and the Avoidance of Wind Turbines

Author: Dr. R. Dooling

Publication: University of Maryland

Year Published: 2002

Engineering, Frequency Response

This report provides a complete summary of what is known about basic hearing capabilities in birds in relation to the characteristics of noise generated by wind turbines. It is a review of existing data on bird hearing with some preliminary estimates of environmental noise and wind turbine noise at Altamont Pass, California, in the summer of 1999. It is intended as a resource in future discussions of the role that hearing might play in bird avoidance of turbines.

Avoidance of resonances in a semi-guy-wired vertical axis wind turbine

Author: Erik Mollerstrom, Fredric Ottermo, Jonny Hylander, Hans Bernhoff

Publication: EWEA

Year Published: 2014

Resonance analysis for a vertical axis wind turbine is performed. The turbine may be described as semi-guy wired, being bolted stiffly to the ground as well as supported by guy wires. The influence of the first mode eigen frequency of the guy wires and how it is affected by wind load is examined. Using beam theory, an analytical model for calculating the first mode eigen frequency of the guy wire for different wind loads is derived. The analytical model is verified with FEM-simulations and then used to assemble a diagram showing how to combine the wire size, inclination angle and pre-tension for an eigen frequency range over the 3P load for nominal rotational speed and for a certain effective spring force acting on the tower. This diagram, here called an EA-T diagram, may be used as a quick tool for comparing wire setups and a similar diagram can be used for other guy wired structures.

AWWI Technical Report: Evaluating a Commercial-Ready Technology for Raptor Detection and Deterrence at a Wind Energy Facility in California

Bird Collision Risk, Birds, Detection & Avoidance, Wildlife

Author: H.T. Harvey & Associates

Publication: American Wind and Wildlife Institute

Year Published: 2018

Bird collisions with anthropogenic objects are well documented in the literature, including those involving wind turbines. The purpose of this study was to evaluate and help improve the effectiveness of an automated detection and deterrent system designed to minimize the risk of raptors colliding with wind turbines. We evaluated the DTBird® system (Liquen Consultoría Ambiental, S.L., Madrid, Spain), which is designed to detect and deter raptors flying near and in the risk zone of wind turbines. The DTBird system includes a camera/video-based detection module that detects and tracks objects based on settings calibrated for birds with specific wingspans, and a collision-avoidance or deterrence module that emits sounds designed to discourage birds from proceeding into the collision risk zone of an operational turbine. The deterrence module first emits an audible warning signal when the surveillance system estimates that a detected flying object (whether a bird or an inanimate object) has crossed a calibrated distance threshold. If the surveillance system estimates that the tracked object crosses a second, closer distance threshold, then it emits a stronger dissuasion signal intended to scare the bird away from the signal noise and turbine.

Azerbaijan Mid-Level Wind Resources in Wind Farms

A projected 2 megawatts (MW) of the wind farms in Azerbaijan have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	55
MWs over 6.5m/s at 20m agl (projected)	2
% of wind farms over 6.5m/s at 20m agl	3.6%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Behavioral Responses of Bats to Operating Wind Turbines

Author: Jason W. Horn, Edward B Arnett, Thomas H. Kunz

Publication: J. Wildlife Management

Year Published: 2008

Wind power is one of the fastest growing sectors of the energy industry. Recent studies have reported large numbers of migratory tree-roosting bats being killed at utility-scale wind power facilities, especially in the eastern United States. We used thermal infrared (TIR) cameras to assess the flight behavior of bats at wind turbines because this technology makes it possible to observe the nocturnal behavior of bats and birds independently of supplemental light sources. We conducted this study at the Mountaineer Wind Energy Center in Tucker County, West Virginia, USA, where hundred…

Belgium Mid-Level Wind Resources in Wind Farms

A projected 25 megawatts (MW) of the wind farms in Belgium have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	1,905
MWs over 6.5m/s at 20m agl (projected)	25
% of wind farms over 6.5m/s at 20m agl	1.3%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Benefits of Collocating Vertical-Axis and Horizontal-Axis Wind Turbines in Large Wind Farms

Author: Shengbail Xie, Cristina Archer, Niranjan Ghaisas and Charles Meneveau

Publication: Wiley Online Library

Year Published: 2016

In this study, we address the benefits of a vertically staggered (VS) wind farm, in which vertical-axis and horizontal-axis wind turbines are collocated in a large wind farm. The case study consists of 20 small vertical-axis turbines added around each large horizontal-axis turbine. Large-eddy simulation is used to compare power extraction andflow properties of the VS wind farm versus a traditional wind farm with only large turbines. The VS wind farm produces up to 32% more power than the traditional one, and the power extracted by the large turbines alone is increased by 10%, caused by faster wake recovery from enhanced turbulence due to the presence of the small turbines. A theoretical analysis based on a top-down model is performed and compared with the large-eddy simulation. The analysis suggests a nonlinear increase of total power extraction with increase of the loading of smaller turbines, with weak sensitivity to various parameters, such as size,and type aspect ratio, and thrust coefficient of the vertical-axis turbines. We conclude that vertical staggering can be an effective way to increase energy production in existing wind farms. Copyright © 2016 John Wiley & Sons, Ltd.

Bird and Bat Movement Patterns and Mortality at the Montezuma Hills Wind Resource Area

Bats, Birds, California, Country-by-Country Resources, North America, Solano County, Wildlife

Author: Dave Johnston, Judd Howell, Scott Terrill, Nellie Thorngate, Jim Castle, Jeff Smith

Publication: California Energy Commission

Year Published: 2013

Birds and bats have become important factors in the siting and permitting of wind-energy facilities. Identifying methods to avoid, minimize, and mitigate bird and bat fatalities should help streamline wind energy permitting and reduce potential impacts to bird and bat resources. In this study, the authors conducted nighttime surveys to investigate the effectiveness of using horizontal/vertical radar, full-spectrum acoustic monitoring and night vision to determine nocturnal flight directions, passage rates, and flight altitudes of birds and bats at the Montezuma Hill Wind Resources Area in Northern California. Following nighttime surveys, daily carcass searches were conducted to assess fatality rates as a function of movement patterns in the wind resource area. In addition, the study explored relationships between bird and bat fatalities, relevant activity indicates, and the meteorological, landscape, and vegetation features of the study area.

Bob Thomas, wind energy “father”, VAWT pioneer and inventor, dies at 85

Author: Kevin Wolf

Publication: Wind Harvest International

Year Published: 2019

Bob Thomas was one of three Wind Harvest founders. Read about his life and contributions at the linked resource.

“Engineering for wind energy turbines is like trying to build a car that has the characteristics of a Prius, a Ferrari, and a tractor, with the price tag of a Hyundai.”

– Bob Thomas, WHI Co-Founder and Design Engineer

Brazil Mid-Level Wind Resources in Wind Farms

A projected 4,962 megawatts (MW) of the wind farms in Brazil have mid-level wind speeds over 6.5 meters per second (m/s) at 15 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	16,649
MWs over 6.5m/s at 15m agl (projected)	4,962
% of wind farms over 6.5m/s at 15m agl	29.8%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Calculating a Theoretical Collision Risk Assuming no Avoiding Actions

Publication: Scottish Natural Heritage

Year Published: 2000

Alameda/Contra Costa Counties, Altamont Pass Wind Resource Area, California, Country-by-Country Resources, East San Diego County Wind Resource Area, Horizontal Axis Wind Turbines, Kern County, Mendocino/Lake Counties, North America, Riverside County, San Bernardino County, San Diego County, San Gorgonio Pass Wind Resource Area, Shasta County, Solano County, Solano Wind Resource Area, Tehachapi Wind Resource Area, Vertical Axis Wind Turbines, Wind Farms

Windfarms may impact on ornithological interests in a number of ways. There may be: loss of habitat due to the construction of turbine bases and tracks, displacement of birds as a result of disturbance, and potential mortality through collision. SNH Guidance note describes a methodology for assessing in full the impact of windfarms on ornithological interests, taking account of each of these effects. The methodology includes a two-stage process for the assessment of collision risk.

California Mid-Level Wind Resources in Wind Farms

Summary of onshore wind farms
Existing GWs of HAWT wind farms in state	6.4
GWs of HAWTs over 6.5m/s at 20m agl (projected)	5.5
% of wind farms over 6.5m/s at 20m agl	86%

HAWT: Horizontal Axis Wind Turbine

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Wind Farm Summary & Details

California, Country-by-Country Resources, North America

California Regional Wind Energy Forecasting System

Author: Electric Power Research Institute Inc.

Publication: California Energy Commission

Year Published: 2006

Prepared for the California Energy Commission PIER Program

California Renewable Energy Program Preliminary Evaluation

California, Country-by-Country Resources, North America

Author: Regional Economic Research Inc.

Publication: Governor and California State Legislature

Year Published: 2000

California, Country-by-Country Resources, North America

Prepared for the Governor and California State Legislature

California Wind Energy Resource Modeling and Measurement: Measurement Program Final Report

Author: AWS Truewind, LLC

Publication: California Energy Commission

Year Published: 2006

Alameda/Contra Costa Counties, Altamont Pass Wind Resource Area, California, Country-by-Country Resources, Density, East San Diego County Wind Resource Area, H-Type, Horizontal Axis Wind Turbines, Kern County, North America, Riverside County, San Diego County, San Gorgonio Pass Wind Resource Area, Solano County, Solano Wind Resource Area, Synergy with Tall and Short Turbines, Tehachapi Wind Resource Area, Vertical Axis Wind Turbines, Wind Farms

Prepared by AWS Truewind, LLC for the California Energy Commission Public Interest Energy Research Program

California Wind Resource Areas: Mid-Level Wind Potential

All of California’s wind farms–6000+ megawatts producing 15,200 gigawatt-hours (GWh) annually as of 2021–are on land already zoned for wind energy production. Wind Harvest estimates that, if fully built out on existing wind farms in the Wind Resource Areas, H-type vertical axis wind turbines (VAWTs) could add 10 GW of capacity and about 31,500 GWh of energy per year to California’s grid, fulfilling about 23% of the state carbon neutrality goal. Alternatively, if these VAWTs were added to the Wind Resource Areas both around as well as within existing wind farms, California could add ~15 GW and 45,000 GWh of energy to the grid, or about 33% of what the state needs to reach carbon neutrality.

California Wind Resource Potential Report

Summary of onshore wind farms and H-type turbine potential
GWs of existing (HAWT) wind farms in California Wind Resource Areas (CA WRAs)	6
GWs of VAWTs that could be added outside of existing wind farms in CA WRAs	5
GWs of VAWTs that could be added to existing wind farms in CA WRAs	10

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

CEC 2002 New Wind Energy Resource Maps of California

California, Country-by-Country Resources, North America

Publication: California Energy Commission

Year Published: 2002

Alameda/Contra Costa Counties, California, Country-by-Country Resources, North America

CEC Wind Atlas 1985 – Alameda County

Publication: California Energy Commission

Year Published: 1985

California Wind Map (kmz file)

Alameda/Contra Costa Counties, California, Country-by-Country Resources, North America

Information found here was based on the California Energy Commission report, CEC Wind Atlas, April 1985. Most of the windspeed data was collected at <10m above ground level. The complete CEC Wind Atlas and its underlying reports can be found at the CEC’s main library at 1516 9th St, Sacramento, CA 95814, (916) 654-4292.

CEC Wind Atlas 1985 – Contra Costa County

Publication: California Energy Commission

Year Published: 1985

California, Country-by-Country Resources, North America

CEC Wind Atlas 1985 – excerpts

Publication: California Energy Commission

Year Published: 1985

California Wind Map (kmz file)

California, Country-by-Country Resources, Kern County, North America, Tehachapi Wind Resource Area

Wind Atlas Excerpts

CEC Wind Atlas 1985 – Kern County

Publication: California Energy Commission

Year Published: 1985

California, Country-by-Country Resources, North America, Riverside County

CEC Wind Atlas 1985 – Riverside County

Publication: California Energy Commission

Year Published: 1985

California, Country-by-Country Resources, North America, San Bernardino County

CEC Wind Atlas 1985 – San Bernardino County

Publication: California Energy Commission

Year Published: 1985

California, Country-by-Country Resources, North America, San Diego County

CEC Wind Atlas 1985 – San Diego County

Publication: California Energy Commission

Year Published: 1985

California, Country-by-Country Resources, North America, Shasta County

CEC Wind Atlas 1985 – Shasta County

Publication: California Energy Commission

Year Published: 1985

California, Country-by-Country Resources, North America, Solano County, Solano Wind Resource Area

CEC Wind Atlas 1985 – Solano County

Publication: California Energy Commission

Year Published: 1985

California, Country-by-Country Resources, North America

CEC Wind Energy Investing in our future – Darrieus VAWT photo

Publication: California Energy Commission

Year Published: 1983

Coupled Vortex Effect, Synergy with Tall and Short Turbines

CFD Analysis of Vertical Axis Wind Turbines in Close Proximity

Author: Marius Paraschivoiu, Chad X. Zhang, Selvanayagam Jeyatharsan, Norbert V. Dy, Farooq Saeed, Robert N. Thomas, Ion Paraschivoiu

Publication: IOPARA, Inc.

Year Published: 2011

This paper presents an analysis based on computational fluid dynamics of vertical axis wind turbines when placed in close proximity in a linear array. It has been noticed that VAWTs placed close to each other with counter rotation motions have a higher coefficient of power than a single turbine. This was termed the “coupled vortex effect”. Two mechanisms have been identified to cause this increase in efficiency: the stream tube contraction effect and the vortex effect. The first is due to the blockage effect from neighboring turbines while the later is related to the neighboring turbine acting as a vortex that induces an increased flow field. This paper analyzes each of these effects and studies the influence of the turbine size and the rotation speed. The change of torque on each blade due to these effects is investigated for two different sizes of wind turbines.

CFD simulations of power coefficients for an innovative Darrieus style vertical axis wind turbine with auxiliary straight blades

Author: F. Arpino, G. Cortellessa, M. Dell'lsola, M. Rotondi

Publication: J. Physics: Conference Series

Year Published: 2017

The increasing price of fossil derivatives, global warming and energy market instabilities, have led to an increasing interest in renewable energy sources such as wind energy. Amongst the different typologies of wind generators, small scale Vertical Axis Wind Turbines (VAWT) present the greatest potential for off grid power generation at low wind speeds. In the present work, Computational Fluid Dynamic (CFD) simulations were performed in order to investigate the performance of an innovative configuration of straight-blades Darrieus-style vertical axis micro wind turbine, specifically developed for small scale energy conversion at low wind speeds. The micro turbine under investigation is composed of three pairs of airfoils, consisting of a main and auxiliary blades with different chord lengths. The simulations were made using the open source finite volume based CFD toolbox OpenFOAM, considering different turbulence models and adopting a moving mesh approach for the turbine rotor. The simulated data were reported in terms of dimensionless power coefficients for dynamic performance analysis.

CFD-based Performance Analysis on Design Factors of Vertical Axis Wind Turbines at Low Wind Speeds

Author: Chaianant Sranpat, Suchaya Unsakul, Premchai Choljararux, Thananchai Leephakpreeda

Publication: Energy Procedia

Year Published: 2017

This paper presents effects of design factors on mechanical performances of Vertical Axis Wind Turbines (VAWTs), which are suitable to low wind speeds conditions in Thailand. Potential VAWTs models are numerically analyzed within virtual wind tunnels at low wind speeds by utilizing X-Flow^TM Computational Fluid Dynamics (CFD) software. Design factors include types/patterns, numbers of blades, types of materials, height-to-radius ratios and design modifications in this study. The performance curves of each VAWTs are represented by plots of power coefficients against tip speed ratios. It is found that the types/patterns, numbers of blades, and height-to-radius ratios have significant effects on mechanical performances whereas types of materials result in shifts of operating speeds of VAWTs. The proposed methodology can be used in designing VAWTs to improve mechanical performance before physical fabrication.

Channel geometry optimization for vertical axis wind turbines in skyscrapers

Author: Seifeddine Kefi, Ajay Joneja, Tim K.T. Tse, Sunwei Li

Publication: Computer-Aided Design and Applications

Year Published: 2017

The desire for sustainability and improved air quality has led architects to explore integrating vertical axis wind turbines (VAWT) in urban skyscrapers. However, the efficiency of such solutions is sensitive to the geometry of the wind channel. In this paper, we present a general technique for optimization of the wind channel geometry. Using parametric curves to define the profile of the channel, and by quantizing the location of the control points, we propose an experimental design approach to determine near-optimal channel geometry. The solution is further improved by interpolating the performance function so obtained via a statistical tool called kriging. The approach is tested by an experimental study, in which the parameters of the fluid dynamic model are determined by a series of wind tunnel tests.

Chile Mid-Level Wind Resources in Wind Farms

A projected 25 megawatts (MW) of the wind farms in Chile have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	2,805
MWs over 6.5m/s at 20m agl (projected)	25
% of wind farms over 6.5m/s at 20m agl	8.9%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

China Mid-Level Wind Resources in Wind Farms

A projected 15,823 megawatts (MW) of the wind farms in China have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

California, Country-by-Country Resources, North America, San Francisco County

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	119,786
MWs over 6.5m/s at 20m agl (projected)	15,823
% of wind farms over 6.5m/s at 20m agl	13.2%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

City and County of San Francisco Wind Resource Assessment Project – Data Analysis and Reporting

Author: Itron Inc.

Publication: California Energy Commission

Year Published: 2004

The California Energy Commission’s (Commission) Public Interest Energy Research (PIER) Renewables program element undertook an urban wind resource assessment project to help the City and County of San Francisco optimize its future investment in distributed wind energy generation.

Coal-Fired Power Plant Emissions for One Year

Publication: US Environmental Protection Agency

Year Published: 2015

In 2012, a total of 411 power plants used coal to generate at least 95% of their electricity (EPA 2015). These plants emitted 1,412,038,949 metric tons of CO2 in 2012. Carbon dioxide emissions per power plant were calculated by dividing the total emissions from power plants whose primary source of fuel was coal by the number of power plants.

Colombia Mid-Level Wind Resources in Wind Farms

A projected 20 megawatts (MW) of the wind farms in Colombia have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

H-Type, VAWT Companies, Vertical Axis Wind Turbines

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	20
MWs over 6.5m/s at 20m agl (projected)	20
% of wind farms over 6.5m/s at 20m agl	100%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Company: 4Navitas

Model: 4N-55
Power Output: 55kW
Cut-in wind speed: 3m/s
Cut-out wind speed: 25m/s
Rotor Height: 14m
Rotor Diameter: 14m
Rotor Swept Area: 196m²
Website Updated: 2022

Darrius Type, VAWT Companies, Vertical Axis Wind Turbines

Company: ArborWind

Model: PT-180
Power Output: 60kW
Annual Energy Production: 180,000kWh @7m/s)
Cut-in wind speed: 3.5m/s
Max wind speed: 26m/s
Height: 13.8m
Diameter: 15.2m
Tower Info: 30m
Rotor Swept Area: 210m²
Company information: Product available for sale
Website Updated: 2022

Other Types, VAWT Companies, Vertical Axis Wind Turbines

Company: Change Wind Corporation

Model: CWC 36kW
Power Output: 36kW
Cut-in wind speed: 2.7m/s
Tower Info: 9-12m
Website Updated: 2022

Darrius Type, VAWT Companies, Vertical Axis Wind Turbines

Company: Chava Wind

Model: Windleaf2500
Power Output: 25kW
Annual Energy Production: 65,000kWh @7m/s
Height: 14.2m
Diameter: 9.6m
Tower Info: 15.7m
Website Updated: 2022

H-Type, VAWT Companies, Vertical Axis Wind Turbines

Company: Eastern Wind Power

Model: Sky Farm 50kW
Power Output: 50kW
Annual Energy Production: 45,000kWh at unknown wind speed
Cut-in wind speed: 4m/s
Cut-out wind speed: 40m/s
Rotor Height: 6m
Rotor Diameter: 5m
Tower Info: 16m
Company Information: No longer in business

H-Type, VAWT Companies, Vertical Axis Wind Turbines

Company: Fairwind SA

Model: F180-50
Power Output: 50kW
Annual Energy Production: 107MWh at 5.5m/s
Cut-in wind speed: 2.5m/s
Cut-out wind speed: 20m/s
Tower Info: 30m
Website Updated: 2021

H-Type, VAWT Companies, Vertical Axis Wind Turbines

Company: Inerjy

Model: EcoVert
Power Output: 70kW
Cut-in wind speed: 3m/s
Cut-out wind speed: 15m/s
Tower Info: 25m
Rotor Swept Area: 190m²
Company Information: No longer in business

Company: Lux Wind Power

Darrius Type, VAWT Companies, Vertical Axis Wind Turbines

Model: Lux Wind Turbine
Power Output: 40kW
Website Updated: 2020

H-Type, VAWT Companies, Vertical Axis Wind Turbines

Company: MUCE VAWT

H-Type, VAWT Companies, Vertical Axis Wind Turbines

Model: FDM-25
Power Output: 25kW
Annual Energy Production: 62,500 kWh @ unknown wind speed
Cut-in wind speed: 1.3m/s
Cut-out wind speed: 35m/s
Rotor Height: 8m
Rotor Diameter: 7.5m
Website Updated: 2017

Model: FDM-150
Power Output: 150kW
Annual Energy Production: 880,500 kWh @ unknown wind speed
Cut-in wind speed: 1.4m/s
Cut-out wind speed: 35m/s
Rotor Height: 20m
Rotor Diameter: 18m
Website Updated: 2017

Company: Quinta

Model: Quinta 99
Power Output: 99kW
Cut-out wind speed: 22m/s
Rotor Swept Area: 120m²
Rotor Diameter: 10m
Tower Info: 22/33m
Company Information: Certification withdrawn

Company: Ropatec

H-Type, VAWT Companies, Vertical Axis Wind Turbines

Model: T20proS
Power Output: 20kW
Annual Energy Production: 82,000 kWh @ 7m/s
Cut-in wind speed: 4m/s
Cut-out wind speed: 20m/s
Rotor Diameter: 11m
Tower Info: 24m
Rotor Swept Area: 100m²
Company Information: Website offline

Model: T30proS
Power Output: 30kW
Annual Energy Production: 89,000 kWh @ 7m/s
Cut-in wind speed: 4m/s
Cut-out wind speed: 20m/s
Rotor Diameter: 11m
Tower Info: 24m
Rotor Swept Area: 132m²
Company Information: Website Offline

Company: SAWT

H-Type, VAWT Companies, Vertical Axis Wind Turbines

Model: PK60-AB
Power Output: 50kW
Cut-in wind speed: 2m/s
Cut-out wind speed: 25m/s
Rotor Diameter: 9m
Rotor Height: 9m
Tower Info: 11.5m
Company Information: Website no longer active

Company: SeaTwirl

Offshore, VAWT Companies, Vertical Axis Wind Turbines

Offshore, VAWT Companies, Vertical Axis Wind Turbines

Model: SeaTwirl S1
Power Output: 30kW
Wind Speed Limits: Unknown
Rotor Diameter: 10m
Tower Info: 13m
Website Updated: 2022

Model: SeaTwirl S2x
Power Output: 1MW
Wind Speed Limits: Unknown
Rotor Specifications: Unknown
Website Updated: 2022

Company: Vertax

Model: Vertax
Power Output: 15kW – 1MW
Website Updated: 2021

H-Type, VAWT Companies, Vertical Axis Wind Turbines

Company: XFlow Energy

Model: XFlow
Power Output: 25kW
Tower Info: 10m
Rotor Diameter: 10m
Website Updated: 2021

Comparison of aerodynamic models for Vertical Axis Wind

Author: C Simão Ferreira

Year Published: 2014

Multi-megawatt Vertical Axis Wind Turbines (VAWTs) are experiencing an increased interest for floating off-shore applications. However, VAWT development is hindered by the lack of fast, accurate and validated simulation models. This work compares six different numerical models for VAWTS: a multiple streamtube model, a double-multiple streamtube model, the actuator cylinder model, a 2D potential ow panel model, a 3D unsteady lifting line model, and a 2D conformal mapping unsteady vortex model. The comparison covers rotor configurations with two NACA0015 blades, for several tip speed ratios, rotor solidity and fixed pitch angle, included heavily loaded rotors, in inviscid flow.

Comparison of inflow-tubulence and trailing-edge noise with measurements of a 200-kW vertical axis wind turbine

Author: Erik Mollerstom and Fredric Ottermo

Publication: J. Physics: Conference Series

Year Published: 2019

Models of inflow-turbulence noise and turbulent-boundary-layer trailing-edge noise are compared to earlier measurements of a 200-kW vertical axis wind turbine so that conclusions regarding the origin of the aerodynamic noise can be drawn. The measurement campaigns, which aimed at establishing the noise emission value and locating the aerodynamic noise sources with a microphone array, are here both compared to further modified versions of the trailing-edge and inflow-turbulence models respectively. Unlike the case for horizontal axis wind turbine, inflow-turbulence noise is deemed as the prevailing noise mechanism. Reducing the self-induced turbulence could then be an effective way of lowering the noise levels for vertical axis wind turbines. Also, looking at the directivity of the inflow-turbulence noise model which indicate most noise in the cross-wind directions, a deviation from the standard downwind measurement position for measuring noise emission is suggested for the VAWT case.

Computational and Experimental Study on Vertical Axis Wind Turbine In Search For An Efficient Design

Aerodynamic, Computer Modeling, Design, Engineering

Author: Mohammad Bashar

Publication: Georgia Southern University

Year Published: 2014

Wind alone can fulfill most of the energy requirement of the world by its efficient conversion in to energy. Though Horizontal Axis Wind Turbine (HAWT) is more popular but needs high wind speed to generate energy. On the other hand Vertical Axis Wind Turbine (VAWT) needs low wind speed and can be installed anywhere which are some of the reasons for this research. The main objective of this research is to improve the design and performance of VAWT to make it more attractive, efficient, durable and sustainable. For a VAWT the blades perform the main role to extract energy from the wind. Airfoil is considered as the blade for this new design of VAWT. Airfoil has some good aerodynamic characteristics, match with…

Conceptual design of a large-scale floating offshore vertical axis wind turbine

Author: Brian Hand, Andrew Cashman

Publication: Energy Procedia

Year Published: 2017

Large-scale floating vertical axis wind turbines (VAWTs) are an attractive and economical solution to harness superior offshore wind resources in deep water locations. This paper presents the conceptual design of a VAWT for this application using a developed aerodynamic modelling strategy. A comprehensive examination of several critical VAWT design parameters was undertaken which included the turbine solidity, blade number, blade aspect ratio and non-prismatic strut design.

Control Methods and Devices-Comments of the National Pest Control Association

Author: Philip Spear

Publication: Bird Control Seminars Proceedings

Year Published: 1996

Central America, Country-by-Country Resources

The last speaker on any program as broad as this one has been usually finds that anything worthwhile he may have had in mind has already been said by one of the earlier speakers. My predicament is even more difficult because the topic for this period is “What’s New from Research Laboratories,” but I neither work in a laboratory, nor have I had an opportunity in recent months to visit laboratories concerned with bird control work. It may be useful, however, to review some of the considerations that go into recommendations concerning bird management. Later I will make some comments concern…

Costa Rica Mid-Level Wind Resources in Wind Farms

A projected 156 megawatts (MW) of the wind farms in Costa Rica have mid-level wind speeds over 6.5 meters per second (m/s) at 15 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	414
MWs over 6.5m/s at 15m agl (projected)	156
% of wind farms over 6.5m/s at 15m agl	37.6%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Croatia Mid-Level Wind Resources in Wind Farms

A projected 80 megawatts (MW) of the wind farms in Croatia have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	900
MWs over 6.5m/s at 20m agl (projected)	83
% of wind farms over 6.5m/s at 20m agl	9.2%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Cumulative impacts on Birds

Author: Agustin Rioperez, Marcos Puente

Publication: DTBird

Year Published: 2015

A compilation of data recorded by DTBird systems installed around the world in 2014 and 2015 are presented: Species detected, range/mean values of flights/day/WTG, total number flights/year/WTG, daily profile of flights, number warning/dissuasion signals activated, number and length of Stops.DTBird capabilities have been recently tested during Autumn 2014 in Calandawind wind turbine (Switzerland), model Vestas 3MW with tower height of 119 m, and rotor diameter of 112 m. The study was coordinated by Interwind AG, and financed by the Swiss Federal Offices of Energy and…

Cyprus Mid-Level Wind Resources in Wind Farms

A projected 35 megawatts (MW) of the wind farms in Cyprus have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Coupled Vortex Effect, Synergy with Tall and Short Turbines

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	189
MWs over 6.5m/s at 20m agl (projected)	35
% of wind farms over 6.5m/s at 20m agl	18.5%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Data Analysis from Experimental Measurements on a Vertical Axis Wind Turbine

Author: Raphael Coneu

Publication: KTH

Year Published: 2017

This thesis presents the analysis of the data measured during the test campaign of a vertical axis wind turbine prototype developed by the company Nenuphar Wind in France. Three studies are presented: the study of the loads measured during the test campaign, the study of the vibrations, and the study of the stall conditions on the blades. Focus is put on the methodology of these analyses rather than on their detailed results. The preliminary processing of data is presented in more details, in particular the determination of selection levels asserting the quality of the data, an analysis of the drift of the zero of the loads sensor and an analysis of the cross-talk effects on the same loads sensors. With reference to the experience gained on previous prototypes, the quality of the data acquired on this prototype was greatly improved, allowing the use of stricter selection levels and a better quality of the results. The drift of the zero of the strain gauges was identified to be caused by temperature effects and was corrected on most of the sensors, leading to a significant decrease of the uncertainty on the loads measurements. The analysis of the cross-talks led to the implementation of a new and more precise way of calculation of the uncertainty due to these effects. Finally, the study of the dynamic stall on the blades of the new prototype developed by Nenuphar is described at the end of the report. The comparison with the previous prototype showed similar stall angular ranges, but less stalled rotations were observed on the new prototype than on the previous one.

Design Evaluation – Design for Extreme Loads

Author: David Malcolm and Antonio Ojeda

Publication: Wind Harvest International

Year Published: 2017

This document describes the methodology used in the design of the Wind Harvester v3.1 turbine for extreme loads. It presents in detail the results of the process for some of the critical components including the mast-to-shaft connection, the drive shaft, the blade at the connection to the upper and middle arms, and the connection between the middle arm and the central mast. Results for the support structure are also presented.

Design Evaluation – Design for Fatigue

Author: David Malcolm and Antonio Ojeda

Publication: Wind Harvest International

Year Published: 2017

Design Evaluation – General Turbine Description for US

Author: David Malcolm and Antonio Ojeda

Publication: Wind Harvest International

Year Published: 2017

This document contains a general description of Wind Harvest International’s (WHI) Harvest production turbine to be installed and tested at the UL and West Texas A&M University’s Advanced Wind Turbine Testing Facility near Canyon Texas. The basic operational and geometrical parameters of the turbine are given, together with information about the most important components and parts. In addition, the external conditions are defined.

Design Evaluation – Structural Design Methodology

Author: David Malcolm and Antonio Ojeda

Publication: Wind Harvest International

Year Published: 2017

This document describes the methodology followed for the structural design of Wind Harvester turbine v3.1 to be installed in Denmark ins 2020. It includes a description of the various computer models used in the design procedure and of the Design Load Cases selected for analysis. The purpose of this document is not to address detailed design values or detailed design parameters. For this, references are given to other documents.

Design of a vertical-axis wind turbine: how the aspect ratio affects the turbine’s peformance

Author: S. Brusca, R. Lanzafame, M. Messina

Publication: Int J Energy Environ Eng

Year Published: 2014

This work analyses the link between the aspect ratio of a vertical-axis straight-bladed (H-Rotor) wind turbine and its performance (power coefficient). The aspect ratio of this particular wind turbine is defined as the ratio between blade length and rotor radius. Since the aspect ratio variations of a vertical-axis wind turbine cause Reynolds number variations, any changes in the power coefficient can also be studied to derive how aspect ratio variations affect turbine performance. Using a calculation code based on the Multiple StreamTube Model, symmetrical straight-bladed wind turbine performance was evaluated as aspect ratio varied. This numerical analysis highlighted how turbine performance is strongly influenced by the Reynolds number of the rotor blade. From a geometrical point of view, as aspect ratio falls, the Reynolds number rises which improves wind turbine performance.

Design, performance and economics of the DAF Indal 50 kW and 375 kW Vertical Axis Wind Turbine

Author: L.A. Schiehbein, David Malcolm

Year Published: 1982

A review of the development and performance of the DAF Indal 50 kW vertical axis Darrieus wind turbines shows that a high level of technical development and reliability has been achieved. Features of the drive train, braking and control systems are discussed and performance details are presented.

Designing of Vertical Axis Wind Turbines for Low Speed, Low Altitude Regions of Central India

Author: Sonali Mitra, Abhineet Singh, Pragyan Jain, S. V. H. Nagendra

Publication: Int J Energy Environ Eng

Year Published: 2014

Miscellaneous, Synergy with Tall and Short Turbines

This work analyses the link between the aspect ratio of a vertical-axis straight-bladed (H-Rotor) wind turbine and its performance (power coefficient). The aspect ratio of this particular wind turbine is defined as the ratio between blade length and rotor radius. Since the aspect ratio variations of a vertical-axis wind turbine cause Reynolds number variations, any changes in the power coefficient can also be studied to derive how aspect ratio variations affect turbine performance. Using a calculation code based on the Multiple Stream Tube Model, symmetrical straight-bladed wind turbine performance was evaluated as aspect ratio varied. This numerical analysis highlighted how turbine performance is strongly influenced by the Reynolds number of the rotor blade. From a geometrical point of view, as aspect ratio falls, the Reynolds number rises which improves wind turbine performance.

Development of the Dual Vertical Axis Wind Turbine Using CFD

Author: Gabriel Naccache, Marius Paraschivoiu

Publication: J. Fluids Eng.

Year Published: 2017

California, Country-by-Country Resources, North America

Small vertical axis wind turbines (VAWTs) are good candidates to extract energy from wind in urban areas because they are easy to install, service, and do not generate much noise; however, the efficiency of small turbines is low. Here-in a new turbine, with high efficiency, is proposed. The novel design is based on the classical H-Darrieus VAWT. VAWTs produce the highest power when the blade chord is perpendicular to the incoming wind direction. The basic idea behind the proposed turbine is to extend that said region of maximum power by having the blades continue straight instead of following a circular path. This motion can be performed if the blades turn along two axes; hence, it was named dual vertical axis wind turbine (D-VAWT). The analysis of this new turbine is done through the use of computational fluid dynamics (CFD) with two-dimensional (2D) and three-dimensional (3D) simulations. While 2D is used to validate the methodology, 3D is used to get an accurate estimate of the turbine performance. The analysis of a single blade is performed and the turbine shows that a power coefficient of 0.4 can be achieved, reaching performance levels high enough to compete with the most efficient VAWTs. The D-VAWT is still far from full optimization, but the analysis presented here shows the hidden potential and serves as proof of concept.

Draft Boundary Layer Research and Findings Report

Author: AWS Truewind, LLC

Publication: California Energy Commission

Year Published: 2005

Miscellaneous, Synergy with Tall and Short Turbines, Vertical Axis Wind Turbines, Wind Harvesters

Prepared by AWS Truewind, LLC for the California Energy Commission.

Dramatically increase wind farm output while protecting wildlife

Author: Kevin Wolf

Publication: Wind Harvest International

Year Published: 2018

Caribbean, Country-by-Country Resources

Wind farms in California and other regions of the world exist only in relatively small geographic regions. Most of these resource areas have reached their physical or political limits in their ability to install additional propeller-type, horizontal axis wind turbines (HAWTs). Nonetheless, many have topographies that create excellent near-ground wind speeds. To profit from the energetic wind below their HAWTs, wind farm owners need cost-effective vertical axis wind turbines (VAWTs) that operate efficiently in high turbulence and do so without wake shedding off the three-dimensionally spinning rotors negatively impacting their existing turbines. They also need turbines that are wildlife friendly. Turning the best near-ground wind into energy should eventually result in lower priced power than solar technologies or new wind farms, less habitat developed, and thousands of MWs of additional renewable power produced well after the sun sets.

Dutch Antilles Mid-Level Wind Resources in Wind Farms

A projected 41 megawatts (MW) of the wind farms in the Dutch Antilles have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Computer Modeling, Engineering, Frequency Response, Frequency Response

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	41
MWs over 6.5m/s at 20m agl (projected)	41
% of wind farms over 6.5m/s at 20m agl	100%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Dynamic Response of a Darrieus Rotor Wind Turbine Subject to Turbulent Flow

Author: David Malcolm

Publication: Engineering Structures

Year Published: 1988

Miscellaneous, Synergy with Tall and Short Turbines

A method is presented for the frequency response analysis of a Darrieus rotor wind turbine subject to turbulent flow. A number of time series vectors of longitudinal and lateral turbulent velocities are generated and the interaction with a two-bladed rotor is carried out with a double multiple streamtube model. The resulting time domain loads are transformed into the frequency domain in terms of components of a real set of eigenvectors of the rotor.

Dynamic Stall: The Case of the Vertical Axis Wind Turbine

Author: A. Leneville, P. Vittecoq

Publication: Sol Energ. Eng.

Year Published: 1986

This paper presents the results of an experimental investigation on a driven Darrieus turbine rotating at different tip speed ratios. For a Reynolds number of 3.8 × 104 , the results indicate the presence of dynamic stall at tip speed ratio less than 4, and that helicopter blade aerodynamics can be used in order to explain some aspects of the phenomenon. It was observed that in deep stall conditions, a vortex is formed at the leading edge; this vortex moves over the airfoil surface with 1/3 of the airfoil speed and then is shed at the trailing edge. After its shedding, the vortex can interact with the airfoil surface as the blade passes downstream.

Ecuador Mid-Level Wind Resources in Wind Farms

A projected 19 megawatts (MW) of the wind farms in Ecuader have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	19
MWs over 6.5m/s at 20m agl (projected)	19
% of wind farms over 6.5m/s at 20m agl	100%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Effect of some design parameters on the performance of a Giromill vertical axis wind turbine

Author: M. El-Samanoudy, A.A.E Ghorab, Sh.Z. Youssef, Ain Shams

Publication: Ain Jams Engineering J

Year Published: 2010

This paper describes the effect of some design parameters on the performance of a Giro-mill vertical axis wind turbine. A Giromill wind turbine has been designed, manufactured and tested. The turbine performance has been investigated with varying the design parameters such as, pitch angle, number of blades, airfoil type, turbine radius and its chord length. Then, the results were used for the comparison between the performance achieved while changing the design parameters.

Effect Of The Shaft On The Aerodynamic Performance Of Urban Vertical Axis Wind Turbines

Author: Abdolrahim Rezaeiha, Ivo Kalkman, Hamid Montazeri, Bert Blocken

Publication: Elsevier Ltd.

Year Published: 2017

The central shaft is an inseparable part of a vertical axis wind turbine (VAWT). For small turbines such as those typically used in urban environments, the shaft could operate in the subcritical regime, resulting in large drag and considerable aerodynamic power loss. The current study aims to (i) quantify the turbine power loss due to the presence of the shaft for different shaft-to-turbine diameter ratios δ from 0 to 16%, (ii) investigate the impact of different operational and geometrical parameters on the quantified power loss and (iii) evaluate the impact of the addition of surface roughness on turbine performance improvement. Unsteady Reynolds-averaged Navier-Stokes (URANS) calculations are…

Effects of Cyclic Stress Distribution Models on Fatigue Life Predictions

Author: Herbert J. Sutherland and Paul S. Veers

Publication: Wind Energy

Year Published: 1995

Effects of optimized airfoil on vertical axis wind turbine aerodynamic performance

Author: Changping Liang, Huaxing Li

Year Published: 2018

This paper investigates the effects of optimized airfoil on VAWT (vertical axis wind turbine) aerodynamic performance. The thickness and camber of the airfoil are selected as the constraints, the value of the maximum tangential force coefficient is chosen as the objective function, optimizing NACA0015 airfoil to enhance the wind energy utilization efficiency of the VAWT, a 3D CFD simulation is used to get the flow characteristics of the VAWT under variable tip speed ratio (TSR) conditions. To ensure the accuracy of the numerical simulation, the power coefficient calculated by CFD is validated against previous experimental result. The optimized airfoil is shown to improve the aerodynamic performance of the wind turbine. Through investigating the effects of optimized airfoil on the rotor flow field, this paper proposes measures to improve the VAWT aerodynamic performance under variable TSRs: measures should be made to avoid or delay the flow separation of blades and the stall vortex shedding and reduce the stall vortex scale at low TSR, while at high TSR measures should be made to shorten the wake length of the blades and reduce its diffusion range.

Effects of the Reynolds Number and the Tip Losses on the Optimal Aspect Ratio of Straight-Bladed Vertical Axis Wind Turbines

Author: Stefania Zanforlin, Stefano Deluca

Year Published: 2018

Aspect Ratio (AR) is one of the main design parameters of straight-bladed vertical axis turbines. This paper will examine whether a high AR, with long blades and low tip losses, or a low AR, with a higher diameter and higher losses, is more suitable to achieve the maximum power output given a fixed cross-sectional area. Traditional Double-Multiple Stream-Tube (DMST) approaches are limited by a lack of tip loss formulations specifically conceived for vertical axis turbines. Therefore, a CFD-3D investigation covering a power range from micro-generation to MW has been done. Results show that both Reynolds number and tip losses strongly influence the aerodynamic performance of the rotor. More advantages seem to be achieved by limiting tip losses rather than increasing chord-based Reynolds number (Re_c), addressing towards high AR at least for medium and large-size turbines. However, as turbine size and wind speed decrease, this difference narrows considerably. For micro turbines, tip losses are balanced by the effects of Re_c, thus a variation of AR does not imply a variation of C_P. For all the cases that have been analysed, turbine size and therefore Re_c does not appreciably affect the normalized C_P distribution along the blade, which only depends on AR.

Effects of Wind Farms on Birds

Author: R.H.W. Langston and J.D. Pullan

Publication: RSPB/Birdlife

Year Published: 2004

Coupled Vortex Effect, Synergy with Tall and Short Turbines

This report was commissioned by the Council of Europe for the Bern Convention as an update of the one commissioned by them last year and presented to the 22nd meeting of the Standing Committee for information. Its remit is to analyse the impact of wind farms on birds, establishing criteria for their environmental impact assessment and developing guidelines on precautions to be taken when selecting sites for wind farms. This revised version has, as an additional annex (Appendix 2), a draft recommendation for consideration by the 23rd meeting of the Standing Committee.

Efficiency Improvement of Vertical-Axis Wind Turbines with Counter-Rotating Lay-Out

Author: Nicolas Parneix, Rosalie Fuchs, Alexandre Immas, Frederic Silvert, Paul Deglaire

Publication: EWEA

Year Published: 2016

Improving the performance of Vertical Axis Wind Turbines (VAWTs) is key to make VAWTs commercially successful. Scientists have investigated several interesting concepts for that purpose: increasing the swept area, especially to limit the losses due to 3D effects, or using flap and pitch systems to control the flow around the blades [1, 2]. Nenuphar, with the Twinfloat concept(see Figure 1), propose to take advantage of all these concepts combined with an aerodynamic effect called counter-rotating effect [3]. The turbine is made of two 2.5MW VAWT on only one floater, to reach a rated power of 5MW. The proximity of the two rotors generates a contraction of the stream tubes that flow in the area between the rotors, thus increasing the air flow rate going through both the swept areas and thereby the performance of the VAWT. This concept has also other advantages:smaller rotors that make easier their fabrication,their installation and Operating and Maintenance (O&M) operations, floater motions reduction thanks to specific control laws and wake reduction leading to an increase in the capacity factor.Simulations presented in this paper are carried out by Computational Fluid Dynamics (CFD) or by a Vortex Panel Method to investigate the stream tubes contraction caused by counter-rotating wind turbines and the impact of the distance between each rotor.This paper presents the main results of this study and the positive impact of counter rotating turbines compared to single turbine performance for floating conditions.

Egypt Mid-Level Wind Resources in Wind Farms

A projected 1,047 megawatts (MW) of the wind farms in Egypt have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Engineering, Frequency Response

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	1,047
MWs over 6.5m/s at 20m agl (projected)	1,047
% of wind farms over 6.5m/s at 20m agl	100%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Eigen Frequencies of A Vertical Axis Wind Turbine Tower Made of Laminated Wood and the Effect Upon Attaching Guy Wires

Author: Erik Mollerstrom, Fredric Ottermo, Jonny Hylander, Hans Bernhoff

Year Published: 2014

Miscellaneous, Synergy with Tall and Short Turbines

Eigen frequencies of a vertical axis wind turbine tower made out of laminated wood which are both bolted to the ground and supported by guy wires are studied and compared. Using beam theory, an analytical model taking the guy wires into account for calculating the first mode eigen frequency of the tower has been derived. The analytical model is then evaluated by comparing with FEM-simulations and measurements performed on the actual tower. The model is found to be reasonably accurate keeping in mind that the estimated masses and second moments of area are somewhat rough. Furthermore the model can be used to give an indication of the magnitude of change in eigen frequency when modifying a tower or guy wire property.

Emergent Aerodynamics in Wind Farms

Author: John Dabiri

Publication: Physics Today

Year Published: 2014

The defining element of modern wind farms is the propeller like structure known as a horizontal-axis wind turbine. A marvel of engineering, the HAWT typically comprises more than 8000 parts, and its blades reach more than 200 m above the ground.

Energy Exchange in an Array of Vertical-Axis Wind Turbines

Author: Matthias Kinzel, Quinn Mulligan and John Dabiri

Publication: Journal of Turbulence

Year Published: 2012

We analyze the ﬂow ﬁeld within an array of 18 counter-rotating, vertical-axis wind turbines (VAWTs), with an emphasis on the ﬂuxes of mean and turbulence kinetic energy. The turbine wakes and the recovery of the mean wind speed between the turbine rows are derived from measurements of the velocity ﬁeld using a portable meteorological tower with seven, vertically-staggered, three-component ultrasonic anemometers. The data provide insight to the blockage effect of both the individual turbine pairs within the array and the turbine array as a whole. The horizontal and planform kinetic energy ﬂuxes into the turbine array are analyzed, and various models for the roughness length of the turbine array are compared…

Engineering and Economic Models of Vertical Axis Wind Turbines

Author: Elhadji Alpha A. Bah, Lakshmi N. Sankar, Jechiel I. Jagoda

Publication: ASME

Year Published: 2018

Miscellaneous, Synergy with Tall and Short Turbines

The interest in sustainable forms of energy is being driven by the anticipated scarcity of traditional fossil fuels over the coming decades. There is also a growing concern about the effects of fossil fuel emissions on human health and the environment. Many sources of renewable energy are being researched and implemented for power production. In particular, wind power generation by vertical-axis wind turbines is one of the option often considered. This option offers a robust design because of the relative simplicity of its technology. However, it also presents challenges that are inherent to its very concept. These systems suffer from dynamic stall, noticeably one of the main causes of the loss of performance. A dual-element concept is proposed as a way of alleviating the losses due to the dynamic stall. An economic analysis is done to establish the economic viability of the model. The Great Coast of Senegal is selected as a site of operation in this study.

Erratum: Energy Exchange in an Array of Vertical-Axis Wind Turbines

Author: Matthias Kinzel, Quinn Mulligan and John Dabiri

Publication: Journal of Turbulence

Year Published: 2013

The calculation of the planform kinetic energy flux in this paper contains an error. The equation stated in the manuscript, Pvert ≈ −ρAplanu < u′w′ >, is correct. However, a typographical error in the data processing code had the effect of calculating the planform kinetic energy flux using u2 instead of u. This error caused a quantitative change in the planform kinetic energy flux as can be seen in the revised version of Figure 7.

Evaluating the Impact of Wind Turbine Noise on Health-Related Quality of Life

Author: Daniel Shepherd, David McBride, David Welch, Kim Dirks, Erin Hill

Publication: Noise Health

Year Published: 2011

We report a cross-sectional study comparing the health-related quality of life (HRQOL) of individuals residing in the proximity of a wind farm to those residing in a demographically matched area sufficiently displaced from wind turbines. The study employed a nonequivalent comparison group posttest-only design. Self-administered questionnaires, which included the brief version of the World Health Organization quality of life scale, were delivered to residents in two adjacent areas in semirural New Zealand. Participants were also asked to identify annoying noises, indicate their degree of noise…

Excitation Methods for a 60 kW Vertical Axis Wind Turbine

Author: Todd Griffith, Randy Mayes, Patrick Hunter

Publication: Sandia National Laboratories

Year Published: 2010

A simple modal test to determine the first tower bending mode of a 60 kW (82 feet tall) vertical axis wind turbine was performed. The minimal response instrumentation included accelerometers mounted only at easily accessible locations part way up the tower and strain gages near the tower base. The turbine was excited in the parked condition with step relaxation, random human excitation, and wind excitation. The resulting modal parameters from the various excitation methods are compared.

Experimental investigation of vertical-axis wind-turbine wakes in boundary layer flow

Author: Vincent F-C. Rolin, Fernando Porté-Agel

Publication: Renewable Energy

Year Published: 2018

Coupled Vortex Effect, Synergy with Tall and Short Turbines

In this experiment, a small scale vertical-axis wind-turbine (VAWT) is immersed in a boundary-layer in a wind tunnel and stereo particle image velocimetry is employed to quantify the 3D characteristics of the wake. The measurements show that the wake is strongest behind the sector of the rotor which turns into the wind. Two counter-rotating vortex pairs in the wake induce crosswind motion which reintroduces streamwise momentum into the wake. Terms of the mean kinetic energy budget are computed and demonstrate that this crosswind flow has a significant influence on the redistribution of momentum in the wake. A similar analysis of the turbulence kinetic energy budget identifies shearing at the boundary of the wake as the primary contributor to the production of turbulence. An analytical model is developed in order to obtain a theoretical basis from which to understand how the aerodynamic behavior of VAWTs induces crosswind motion consistent with the production of counter-rotating vortex pairs.

Experimental Validation of Pharwen Code Using Data from VAWT Wind Tunnel Tests with Imposed Motions

Author: Marianne Dupont, Pitance Denis, Joanna Kluczewska-Bordier, Alexandre Immas, Paul Deglaire

Publication: WindEurope Conference, At Amsterdam

Year Published: 2017

NENUPHAR, in collaboration with IRT Jules Verne and ECN (Ecole Centrale de Nantes) has performed extensive testing in a large wind tunnel (CSTB, Nantes) of a scaled-model of a two-bladed VAWT in the frame of the “MOQUA” project. The model was mounted on a 6DOF robot (hexapod) capable of imposing simple and combined motions to the structure. The wind turbine was operated at a TSR (tip speed ratio) of about 4 with simulated floater motions (surge, sway, heave, roll, pitch, yaw, and combinations of those). Measurements were carried out using several internal balances placed at the junctions of the rotor elements. Main tests objectives consisted in the validation of the unsteady aerodynamic behavior of the VAWT and in the validation of the PHARWEN numerical code, NENUPHAR’s simulation tool. The experimental validation strategy and results from the comparison between the experiments and the results of numerical simulations are presented in the paper, with a focus on the loads variation over one full rotor revolution that are specific to VAWTs.

Exploring the benefits of vertically staggered wind farms: Understanding the power generation mechanisms of turbines operating at different scales

Author: Tanmoy Chatterjee, Yulia Peet

Publication: Wind Energy

Year Published: 2018

Wind farms are known to modulate large scale structures in and around the wake regions of the turbines. The potential benefits of placing small hub height, small rotor turbines in between the large turbines in a wind farm to take advantage of such modulated large‐scale eddies are explored using large eddy simulation (LES). The study has been carried out in an infinite wind farm framework invoking an asymptotic limit, and the wind turbines are modeled using an actuator line model. The vertically staggered wind turbine arrangements that are studied in the present work consist of rows of large wind turbines, with rows of smaller wind turbines (ie, smaller rotor size and shorter hub height) placed in between the rows of large turbines. The influence of the hub height of the small turbines, in particular, how it affects the interactions between the large and small turbines and consequently their power, along with the multiscale dynamics involved, has been assessed in the current study. It was found that, in the multiscale layouts, the small turbines at lower hub heights operate more efficiently than their homogeneous single‐scale counterparts. In contrast, the small turbines with higher hub heights incur a loss of power compared with the corresponding single‐scale arrangements.

Faroe Islands Mid-Level Wind Resources in Wind Farms

A projected 21 megawatts (MW) of the wind farms in the Faroe Islands have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	21
MWs over 6.5m/s at 20m agl (projected)	21
% of wind farms over 6.5m/s at 20m agl	100%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Fatigue Case Study and Reliability Analyses for Wind Turbines

Author: Herbert J. Sutherland and Paul S. Veers

Publication: Sandia National Laboratories

Year Published: 1995

Modern wind turbines are fatigue critical machines used to produce electrical power. Economic viability requires them to have both low initial cost and long term reliability. The fatigue and reliability projects in Sandia’s Wind Energy Program are developing the analysis tools required to accomplish these design requirements. The first section of the paper formulates the fatigue analysis of a wind turbine using a cumulative damage technique. The second section uses reliability analysis for quantifying the uncertainties and the inherent randomness associated with turbine performance and the prediction of service lifetimes. Both research areas are highlighted with typical results.

Fatigue Life Variability and Reliability Analysis of a Wind Turbine Blade

Author: Paul S. Veers, Herbert J. Sutherland, Thomas D. Ashwill

Publication: Sandia National Laboratories

Wind turbines must withstand harsh environments that induce many stress cycles into their components. A numerical analysis package is used to illustrate the sobering variability in predicted fatigue life with relatively small changes in inputs. The variability of the input parameters is modeled to obtain estimates of the fatigues reliability of the turbine blades.

Finding a best rotor for a floating vertical axis turbine

Author: Paul Dvorak

Publication: Windpower Engineering & Development

Year Published: 2016

Finite Element Analysis and Modal Testing of a Rotating Wind Turbine

Author: Thomas Carne, Donald Lobitz, Arlo Nord, Robert Watson

Publication: Sandia National Laboratories

Year Published: 1982

Aerodynamic, Computer Modeling, Miscellaneous, Synergy with Tall and Short Turbines

A finite element procedure, which includes geometric stiffening, and centrifugal and Coriolis terms resulting from the use of a rotating coordinate system, has been developed to compute the mode shapes and frequencies of rotating structures. Special application of this capability has been made to Darrieus, vertical axis wind turbines. In a parallel development effort, a technique for the modal testing of a rotating vertical axis wind turbine has been established to measure modal parameters directly. Results from the predictive and experimental techniques for the modal frequencies and mode shapes are compared over a wide range of rotational speeds.

Fish schooling as a basis for vertical axis wind turbine farm design

Author: Robert Whittlesey, Sebastian Liska, and John Dabiri

Publication: California Institute of Technology

Year Published: 2010

Most wind farms consist of horizontal axis wind turbines (HAWTs) due to the high power coefficient (mechanical power output divided by the power of the free-stream air through the turbine cross-sectional area) of an isolated turbine. However when in close proximity to neighbouring turbines, HAWTs suffer from a reduced power coeffi- cient. In contrast, previous research on vertical axis wind turbines (VAWTs) suggests that closely-spaced VAWTs may experience only small decreases (or even increases) in an individual turbine’s power coefficient when placed in close proximity to neighbours, thus yielding much higher power outputs for a given area of land…

Flow characteristics and dynamic responses of a parked straight-bladed vertical axis wind turbine

Author: Limin Kuang, Jie Su, Yaoran Chen, Zhaolong Han, Dai Zhou, Yongsheng Zhao, Zhiyu Jiang, Yan Bao

Publication: Energy Science & Engineering

Year Published: 2019

Miscellaneous, Synergy with Tall and Short Turbines

With the development of urbanization and the application of renewable energy, wind turbine is becoming an important approach for wind energy reservation and utilization. This study provides a numerical investigation on understanding the surface pressure distribution, flow characteristics and dynamic responses of a parked straight-bladed vertical axis wind turbine (VAWT), which is helpful for its design. Together with the two-way coupling method between simulation platforms such as STAR-CCM+ and ABAQUS, the SST k-ω turbulence model is used to obtain the surface pressure and surrounding flow of the VAWT, and the finite element method is used to obtain the dynamic responses of its structural components. The results show that the contours of the pressure distribution on the windward surface of the VAWT are similar even under a few different conditions, and the deformation of the VAWT can lead to changes in surface pressure; the turbulent flow characteristics and the wake effect become more obvious as the wind velocity increases; the blades and support arms of the VAWT need to be reinforced during the design, and the effect of the parked condition on the dynamic responses of the VAWT can be neglected. The two-way coupling method as well as the numerical simulation results is expected to provide references for the design of VAWTs subjected to coming wind action.

Flow Past a Rotating Cylinder

Author: Sanjay Mittal, Bhaskar Kumar

Publication: J. Fluid Mech.

Year Published: 2002

Miscellaneous, Synergy with Tall and Short Turbines

Flow-driven rotor simulation of vertical axis tidal turbines: A comparison of helical and straight blades

Author: Tuyen Quang Le, Kwang-Soo Lee, Jin-Soon Park, Jin Hwan Ko

Publication: Ocean Eng.

Year Published: 2014

Miscellaneous, Synergy with Tall and Short Turbines

In this study, flow-driven rotor simulations with a given load are conducted to analyze the operational characteristics of a vertical-axis Darrieus turbine, specifically its self-starting capability and fluctuations in its torque as well as the RPM. These characteristics are typically observed in experiments, though they cannot be acquired in simula- tions with a given tip speed ratio (TSR). First, it is shown that a flow-driven rotor simulation with a two-dimensional (2D) turbine model obtains power coefficients with curves similar to those obtained in a simulation with a given TSR. 3D flow- driven rotor simulations with an optimal geometry then show that…

Fluid Dynamics Theory and Computation

Author: Dan Henningson, Martin Berggren

Publication: KTH

Year Published: 2005

Miscellaneous, Synergy with Tall and Short Turbines

These lecture notes has evolved from a CFD course (5C1212) and a Fluid Mechanics course (5C1214) at the department of Mechanics and the department of Numerical Analysis and Computer Science (NADA) at KTH. Erik Stalberg and Ori Levin has typed most of the LATEX formulas and has created the electronic versions of most figures. In the latest version of the lecture notes study questions for the CFD course 5C1212 and recitation material for the Fluid Mechanics course 5C1214 has been added.

Fluid-Structure Interaction Modeling of Vertical-Axis Wind Turbines

Author: Y. Bazilevs, A. Korobenko, X. Deng, J. Yan, M. Kinzel, John Dabiri

Publication: J. Appl. Mech.

Year Published: 2014

Full-scale, 3D, time-dependent aerodynamics and ﬂuid–structure interaction (FSI) simulations of a Darrieus-type vertical-axis wind turbine (VAWT) are presented. A structural model of the Windspire VAWT (Windspire energy, http://www.windspireenergy.com/) is developed, which makes use of the recently proposed rotation-free Kirchhoff–Love shell and beam/cable formulations. A moving-domain ﬁnite-element-based ALE-VMS (arbitrary Lagrangian–Eulerian-variational-multiscale) formulation is employed for the aerodynamics in combination with the sliding-interface formulation to handle the VAWT mechanical components in relative motion. The sliding-interface formulation is augmented to handle nonstationary cylindrical sliding…

Georgia Mid-Level Wind Resources in Wind Farms

A projected 21 megawatts (MW) of the wind farms in Georgia have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Country-by-Country Resources, Europe, Horizontal Axis Wind Turbines, Vertical Axis Wind Turbines, Wind Farms

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	21
MWs over 6.5m/s at 20m agl (projected)	21
% of wind farms over 6.5m/s at 20m agl	100%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Greece Mid-Level Wind Resources in Wind Farms

A projected 333 megawatts (MW) of the wind farms in Greece have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Central America, Country-by-Country Resources

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	4,348
MWs over 6.5m/s at 20m agl (projected)	333

This data came from thewindpower.net and UL’s Windnavigator.

The linked Wind Farm Details data set is shared under Creative Commons Copyright terms.

Guatemala Mid-Level Wind Resources in Wind Farms

A projected 40 megawatts (MW) of the wind farms in Guatemala have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	108
MWs over 6.5m/s at 20m agl (projected)	40
% of wind farms over 6.5m/s at 20m agl	37%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

High Energy Rotor Development,Test and Evaluation – Final Project Report

Author: FloWind Corporation

Publication: Sandia National Laboratories

Year Published: 1996

Under the auspices of the “Government/Industry Wind Technology Applications Project” [“Letter of Interest” (LOI) Number RC-1-11101], Flo Wind Corp. has successfully developed, tested, and delivered a high-energy rotor upgrade candidate for their 19-meter Vertical Axis Wind Turbine. The project included the demonstration of the innovative extended height-to-diameter ratio concept, the development of a continuous-span single-piece composite blade, the demonstration of a continuous blade manufacturing technique, the utilization of the Sandia National Laboratories developed SNLA 2150 natural laminar flow airfoil and there use of existing wind turbine and wind power plant infrastructure.

High Frequency Sound Devices Lack Efficacy in Repelling Birds

Author: William Erickson, Rex Marsh and Terrell Salmon

Year Published: 1992

Ultrasonic or high-frequency sound-producing devices are marketed as a scaring or frightening method for bird control. Although inaudible to humans, most birds also do not hear in the ultrasonic frequency ranges of above 20,000 Hz, thus the credibility of advertised claims raises questions. A review of efficacy studies conducted and published by a number of researchers fails to demonstrate the usefulness of such bird control devices.

Historical Development of the Windmill

Author: Dennis Shepherd

Publication: NASA

Year Published: 1990

Central America, Country-by-Country Resources

Honduras Mid-Level Wind Resources in Wind Farms

A projected 126 megawatts (MW) of the wind farms in Honduras have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	180
MWs over 6.5m/s at 20m agl (projected)	126
% of wind farms over 6.5m/s at 20m agl	70%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

How Proper Planning And A General Understanding of Bats Help Reduce Impacts

Author: Nic Sharpley

Publication: Windpower Engineering & Development

Year Published: 2013

Unfortunately, the wind industry does not yet have a handle on the issue of the rising bat mortality rate. Researchers initially believed bat deaths at wind farms were the same as birds, but autopsies have revealed a more complex situation. Currently, there is no quick fix to completely end bat fatalities, but understanding bat migration and roosting can lessen impacts.

How to harvest plentiful low-level winds on existing wind farms

Author: Kevin Wolf

Publication: Windpower Engineering & Development

Year Published: 2018

Wind farms in California and other regions of the world exist only in relatively small geographic regions.¹ Most of these resource areas have reached their physical or political² limits in their ability to install additional propeller-type, horizontal axis wind turbines (HAWTs).³ Nonetheless, many have topographies that create excellent near-ground wind speeds. To profit from the energetic wind below their HAWTs, wind farm owners need cost-effective vertical axis wind turbines (VAWTs) that operate efficiently in high turbulence and that do so without wake⁴ from the added rotors negatively impacting their existing turbines. They also need turbines that are wildlife friendly.

Impact Analysis of Wind Farms on Telecommunication Services

Author: I. Angulo, D. de la Vega, I. Cascón, J. Cañizo, Y. Wu, D. Guerra, P. Angueira

Year Published: 2014

Wind power is one of the fastest-growing technologies for renewable energy generation. Unfortunately, in the recent years some cases of degradation on certain telecommunication systems have arisen due to the presence of wind farms, and expensive and technically complex corrective measurements have been needed. This paper presents a comprehensive review on the impact of wind turbines on the telecommunication services. The paper describes the potential affections to several telecommunication services, the methodology to evaluate this impact, and mitigation measures to be taken in case of…

Impacts of Wind Farms on Birds: A Review

Author: Ralph Powlesland

Publication: Science For Conservation 289

Year Published: 2009

California, Country-by-Country Resources, North America, San Diego County

The impacts of wind farms on New Zealand bird species and populations are unknown. This document reviews available literature on the impacts of on shore wind farms on birds, based on studies in other countries. A key finding is that wind farms tend to have variable effects on bird populations, which can be species-,season- and/or site-specific. The impacts include collision fatalities, habitat loss and disturbance resulting in displacement. The main factors that contribute to collision fatalities are proximity to areas of high bird density or frequency of movements (migration routes, staging areas, wintering areas), bird species (some are more prone to collision or displacement than others), landscape features that concentrate…

Imperial Valley Focus Area Wind Speed at 70m

Author: AWS Truepower

Publication: California Energy Commission

Year Published: 2010

Mean-Annual-Wind-Speed-at-70m-Imperial-Valley-Focus-ARea-300x194

India Mid-Level Wind Resources in Wind Farms

A projected 161 megawatts (MW) of the wind farms in India have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Asia, Country-by-Country Resources, Horizontal Axis Wind Turbines, Oceania, Vertical Axis Wind Turbines, Wind Farms

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	29,984
MWs over 6.5m/s at 20m agl (projected)	161
% of wind farms over 6.5m/s at 20m agl	0.5%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Indonesia Mid-Level Wind Resources in Wind Farms

A projected 147 megawatts (MW) of the wind farms in Indonesia have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	148
MWs over 6.5m/s at 20m agl (projected)	147

This data came from thewindpower.net and UL’s Windnavigator.

The linked Wind Farm Details data set is shared under Creative Commons Copyright terms.

Publication: Wind Harvest International

Innovative Offshore Vertical-Axis Wind Turbine Rotors

Author: Joshua Paquette, Matthew Barone

Publication: Sandia National Laboratories

Year Published: 2012

Ireland Mid-Level Wind Resources in Wind Farms

A projected 1,566 megawatts (MW) of the wind farms in Ireland have mid-level wind speeds over 6.5 meters per second (m/s) at 15 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	3,765
MWs over 6.5m/s at 15m agl (projected)	1,566
% of wind farms over 6.5m/s at 15m agl	41,6%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Italy Mid-Level Wind Resources in Wind Farms

A projected 758 megawatts (MW) of the wind farms in Ireland have mid-level wind speeds over 6.5 meters per second (m/s) at 15 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Caribbean, Country-by-Country Resources

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	10,750
MWs over 6.5m/s at 15m agl (projected)	758
% of wind farms over 6.5m/s at 15m agl	7.1%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Jamaica Mid-Level Wind Resources in Wind Farms

A projected 68 megawatts (MW) of the wind farms in Jamaica have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	103
MWs over 6.5m/s at 20m agl (projected)	68
% of wind farms over 6.5m/s at 20m agl	66%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Japan Mid-Level Wind Resources in Wind Farms

A projected 146 megawatts (MW) of the wind farms in Croatia have mid-level wind speeds over 6.5 meters per second (m/s) at 15 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	2,693
MWs over 6.5m/s at 15m agl (projected)	348
% of wind farms over 6.5m/s at 15m agl	12.9%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Jordan Mid-Level Wind Resources in Wind Farms

A projected 95 megawatts (MW) of the wind farms in Jordan have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	470
MWs over 6.5m/s at 20m agl (projected)	95
% of wind farms over 6.5m/s at 20m agl	20.2%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Kenya Mid-Level Wind Resources in Wind Farms

A projected 438 megawatts (MW) of the wind farms in Kenya have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

California, Country-by-Country Resources, Kern County, North America, Tehachapi Wind Resource Area

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	438
MWs over 6.5m/s at 20m agl (projected)	438
% of wind farms over 6.5m/s at 20m agl	100%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Kern County Wind Map at 80m agl

Publication: NREL Wind Prospector

California, Country-by-Country Resources, Kern County, North America, Tehachapi Wind Resource Area

Kern County Wind Map at 80m agl from NREL Wind Prospector

Kern County Wind Speed Maps

Author: AWS Truepower

Publication: California Energy Commission

Year Published: 2006

Wind speed map at 50m

Percent change in wind speed at 50m

Comparison-for-2002-and-2006-wind-speeds-Tehachapi-300x204

Wind speed map of Tehachapi pass at 50m – comparison between 2002 and 2006

Mean-Annual-Wind-Spped-at-70m-Tehachapi-Pass-Focus-Area-201x300

Mean annual wind speed at 70m

Letter of Support for WHI’s VAWT Wake Research Proposal

Author: Marius Parashivoiu

Publication: Concordia University

Year Published: 2019

As consultant for Iopara Inc., I collaborated with WHI on their prior project, Modeling Blade Pitch and Solidities in Straight Bladed VAWTs, funded through the CEC’s Energy Innovations Small Grant Program. For that research project, Iopara created an aerodynamic model of WHI’s vertical axis wind turbine using data collected from a 3-turbine array located in Palm Springs, CA. Iopara’s modeling validated the “coupled vortex effect” and predicted that the physics and wind effects the phenomenon generated by certain configurations of turbines would be able to significantly increase the energy output of lower solidity VAWTs such as WHI’s G168.
WHI’s proposed Applied Research and Development project will test these predictions, confirming the increase in Capacity Factor that can be realized by the strategic positioning of a VAWT near its neighbor. The project will further build on the findings of the previous study in order to develop a commercially viable strategy for deployment of VAWTs in the understories of existing horizontal axis wind turbines. Although our CEC funded study evaluated two dimensional wakes produced directly behind the VAWT array, our other work on VAWTs indicates that a region of turbulence will develop just above an array of closely spaced turbines. Above that, the increase in wind flowing over the top of the VAWT array will produce a region of wind moving faster than the incoming wind speed at that height. In order to take advantage of the speed-up effect, the VAWT arrays would need to be placed so that the HAWT rotors operate in the higher-speed wind zone without being impacted by the turbulent region.

Life Cycle Assessment Harmonization and Results and Findings

Publication: National Renewable Energy Laboratory

Year Published: 2014

The data from the Life Cycle Harmonization Project show that life cycle greenhouse gas (GHG) emissions from technologies powered by renewable resources are generally less than from those powered by fossil fuel-based resources. Only the very highest estimates for biopower overlap with the range of a fossil-fueled technology, and the central tendencies of all renewable technologies are between 400 and 1,000 g CO₂eq/kWh lower than their fossil-fueled counterparts without carbon capture and sequestration (CCS).

Lightning Protection for the Vertical Axis Wind Turbine

Author: Curtis Dodd

Publication: Sandia National Laboratories

Year Published: 1977

This report contains the results of lightning protection studies for Vertical Axis Wind Turbines. The methodology is established for determining the chances for a lightning strike at a VAWT site. Proposed designs include an insulator design, a brush by-pass design, a cone of protection, lightning elimination device, and a concentric tower protection system. The work also describes an effective grounding system.

Location of aerodynamic noise sources from a 200kW vertical-axis wind turbine

Author: Fredric Ottermo, Erik Mollerstrom, Anders Nordborg, Jonny Hylander, Hans Bernhoff

Publication: J. Sound and Vibration

Year Published: 2017

Noise levels emitted from a 200 kW H-rotor vertical-axis wind turbine have been measured using a microphone array at four different positions, each at a hub-height distance from the tower. The microphone array, comprising 48 microphones in a spiral pattern, allows for directional mapping of the noise sources in the range of 500 Hz to 4 kHz. The produced images indicate that most of the noise is generated in a narrow azimuth-angle range, compatible with the location where increased turbulence is known to be present in the flow, as a result of the previous passage of a blade and its support arms. It is also shown that a semi-empirical model for inflow-turbulence noise seems to produce noise levels of the correct order of magnitude, based on the amount of turbulence that could be expected from power extraction considerations.

Low-Order Modeling of Wind Farm Aerodynamics Using Leaky Rankine Bodies

Author: aniel Araya, Anna. Craig, Matthias Kinzel, and John Dabiri

Publication: J. Renewable and Sustainable Energy

Year Published: 2014

We develop and characterize a low-order model of the mean ﬂow through an array of vertical-axis wind turbines (VAWTs), consisting of a uniform ﬂow and pairs of potential sources and sinks to represent each VAWT. The source and sink in each pair are of unequal strength, thereby forming a “leaky Rankine body” (LRB). In contrast to a classical Rankine body, which forms closed streamlines around a bluff body in potential ﬂow, the LRB streamlines have a qualitatively similar appearance to a separated bluff body wake; hence, the LRB concept is used presently to model the VAWT wake. The relative strengths of the source and sink are determined from ﬁrst principles analysis of an actuator disk model of the VAWTs. The LRB…

Mammalian mesocarnivore visitation at tortoise burrows in a wind farm

Habitat, Wildlife

Author: Mickey Agha, Amanda Smith, Jeffrey Lovich, David Dalaney, Joshua Ennen, Jessica Briggs, Leo Fleckenstein, Laura Tennant, Shellie Puffer, Andrew Walde, Terence Arundel, Steven Price, Brian Todd

Publication: J. Wildlife Management

Year Published: 2017

Country-by-Country Resources, Hawaii, North America

There is little information on predator–prey interactions in wind energy landscapes in North America, especially among terrestrial vertebrates. Here, we evaluated how proximity to roads and wind turbines affect mesocarnivore visitation with desert tortoises (Gopherus agassizii) and their burrows in a wind energy landscape. In 2013, we placed motion‐sensor cameras facing the entrances of 46 active desert tortoise burrows in a 5.2‐km² wind energy facility near Palm Springs, California, USA. Cameras recorded images of 35 species of reptiles, mammals, and birds. Counts for 4 species of mesocarnivores at desert tortoise burrows increased closer to dirt roads, and decreased closer to wind turbines. Our results suggest that anthropogenic infrastructure associated with wind energy facilities could influence the general behavior of mammalian predators and their prey. Further investigation of proximate mechanisms that underlie road and wind turbine effects (i.e., ground vibrations, sound emission, and traffic volume) and on wind energy facility spatial designs (i.e., road and wind turbine configuration) could prove useful for better understanding wildlife responses to wind energy development.

Maui Mid-Level Wind Resources in Wind Farms

A projected 75 megawatts (MW) of the wind farms in Maui have mid-level wind speeds over 6.5 meters per second (m/s) at 15 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

California, Country-by-Country Resources, Mendocino/Lake Counties, North America

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in area	75
MWs over 6.5m/s at 15m agl (projected)	75
% of wind farms over 6.5m/s at 15m agl	100%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Mayacamas Mountains Wind Maps

Author: AWS Truepower

Publication: California Energy Commission

Year Published: 2006

Percent-Change-in-Wind-Speed-at-50m-Mayacamas-Mountains-204x300

Percent change in wind speed at 50m map

Wind speed map at 50m

Mean Kinetic Energy Replenishment Mechanisms in Vertical-Axis Wind Turbine Farms

Miscellaneous, Synergy with Tall and Short Turbines

Author: Sayed Hossein Hezeveh, Elie Bou-Zeid

Publication: Physical Review Fluids

Year Published: 2018

Vertical-axis wind turbines (VAWTs) are the subject of renewed interest due to the potential for higher power generation per unit land used, as well as their lower center of mass (the generator is at the bottom of tower), which renders them favorable for offshore deployment. However, VAWT farms have hardly been studied. In this paper, using a previously tested actuator line model in a large eddy simulation code, we investigate the transport of the mean kinetic energy (MKE) that replenishes the power in the farm. The primary sources of MKE are (1) the initial advective streamwise influx through the frontal area and (2) the vertical planform influx through the top and bottom interfaces of the farm. The results show that, for realistic finite-size farms, the planform MKE transport is a loss term over the first six rows: in this initial zone the mean flow adjusts by slowing down, and an upward mean advection develops that results in an efflux loss of MKE from the farm volume. The power extracted from farms is thus mainly from the frontal advection over the first few rows. When the initial streamwise advective flux is exhausted, the planform regeneration of MKE from above the wind farm becomes the dominant source; it is primarily affected by turbulent-mean interaction. This regeneration continues to adjust until rows 8 to 10 in our setups, beyond which a fully developed flow (similar to an infinite wind farm) can be observed. In the fully developed region, actual mechanical power generation by the turbines is about one third of replenishment. A primary conclusion is that more irregular farms designs should be studied, while the current literature continues to focus on the very classic layouts.

Measurements and Calculations of Aerodynamic Torques for a Vertical Axis Wind Turbine

Author: Robert Akins, Dale Berg, W. Tait Cyrus

Publication: Sandia National Laboratories

Year Published: 1987

This report describes measurements of aerodynamic torque on a vertical-axis wind turbine. Accelerometers mounted at the equator of the rotor and a torque meter mounted at the base of the rotor were used to compute the net aerodynamic torque acting on the rotor. Assumptions concerning blade-response symmetry were required to achieve blade torque as a function of rotor position on each half of a revolution for a two-bladed rotor. Results are presented for tip-speed ratios from 2.5 to 8.0 for two turbine rotational speeds. Evidence of dynamic stall is observed at low tip-speed ratios.

Measurements of the wake characteristics of co- and counter-rotating twin H-rotor vertical axis wind turbines

Author: H.F. Lam, H.Y. Peng

Publication: Energy

Year Published: 2017

Increasing the efficiency of individual vertical-axis wind turbines (VAWTs) has been the subject of much research. However, wind farms that comprise individual VAWTs are not necessarily the most efficient configuration in accordance with VAWTs’ signature wake pattern. This study aims to identify efficient array configurations and thereby increase the packing density and power output by grouping individual VAWTs as a unit. Systematic measurements of wake aerodynamics of co-rotating and counter-rotating (forward- and backward-rotating) twin VAWTs were taken in a wind tunnel. The wake was measured both along the blade mid-span plane up to 10 turbine diameters (10D) and along the vertical plane. The wake of co-rotating twin VAWTs showed great asymmetry, similar to that of a single VAWT. Interestingly, the wake of counter-rotating twin VAWTs demonstrated elegant symmetric patterns. Two pairs of stationary counter-rotating vortices were found to evolve in the wake. The turbulence intensity downstream was observed to experience drastic changes and slow recovery compared with its velocity counterpart. Finally, two types of array units are proposed for applications in wind farms in accordance with the measurements.

Mesh Convergence Study for 2-D Straight-Blade Vertical Axis Wind Turbine Simulations and Estimation for 3-D Simulations

Author: Saman Naghib Zadeh, Matin Komeili and Marius Paraschivoiu

Publication: Concordia University

Year Published: 2014

Country-by-Country Resources, North America

Mesh resolution requirements are investigated for 2-D and 3-D simulations of the complex flow around a straight-blade vertical axis wind turbine (VAWT). The resulting flow, which may include large separation flows over the blades, dynamic stall, and wake-blade interaction, is simulated by an Unsteady Reynolds- Averaged Navier–Stokes analysis, based on the Spalart–Allmaras (S–A) turbulence model. A grid resolution study is conducted on 2-D grids to examine the convergence of the CFD model. Hence, an averaged grid residual of y+ > 30 is employed, along with a wall treatment, to capture the near-wall region’s flow structures. Furthermore a 3-D simulation on a coarse grid of the VAWT model is performed in order to explore the influence of the 3-D effects on the aerodynamic performance of the turbine. Finally, based on the 2-D grid convergence study and the 3-D results, the required computational time and mesh to simulate 3-D VAWT accurately is proposed.

Mexico Mid-Level Wind Resources in Wind Farms

A projected 6,256 megawatts (MW) of the wind farms in Mexico have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Computer Modeling, Engineering, Frequency Response, Modal Testing

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	6,623
MWs over 6.5m/s at 20m agl (projected)	6,256
% of wind farms over 6.5m/s at 20m agl	94.5%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Modal Identification of a Rotating Blade System

Author: Thomas Carne, D.R. Martinez, S.R. Ibrahim

Publication: Sandia National Laboratories

Year Published: 1983

A new testing technique and the Ibrahim time domain (ITD) modal identification algorithm have been combined, resulting in a capability to estimate modal parameters for rotating blade systems. This capability has been evaluated on the Sandia two-meter, vertical-axis wind turbine. Variation in modal frequencies as a function of rotation speed has been experimentally determined from 0 rpm (parked) to 800 rpm. Excitation of the rotating turbine was provided by a scheme which suddenly released a pretensioned cable, thus plucking the turbine as it rotated.

Modal Testing in the Design Evaluation of Wind Turbines

Author: James Lauffer, Thomas Carne, Thomas Ashwill

Publication: Sandia National Laboratories

Year Published: 1988

In the design of large, flexible wind turbines subjected to dynamic loads, knowledge of the modal frequencies and mode shapes is essential in predicting structural response and fatigue life. During design, analytical models must be depended upon for estimating modal parameters. When turbine hardware becomes available for testing, actual modal parameters can be measured and used to update the analytical prediction or modify the model. The modified model can then be used to reevaluate the adequacy of the structural design. Because of problems in providing low-frequency excitation (0.1 to 5.0 Hz), modal testing of large turbines can be difficult. This report reviews several techniques of low-frequency excitation used successfully to measure modal parameters for wind turbines, including impact, wind, step-relaxation, and human input. As one application of these techniques, a prototype turbine was tested and two modal frequencies were found to be close to integral multiples of the operating speed, which caused a resonant condition. The design was modified to shift these frequencies, and the turbine was retested to confirm expected changes in modal frequencies.

Modal Testing of a Rotating Wind Turbine

Author: Thomas Carne, Arlo Nord

Publication: Sandia National Laboratories

Year Published: 1982

Coupled Vortex Effect, Synergy with Tall and Short Turbines

A testing technique has been developed to measure the modes of vibration of a rotating vertical axis wind turbine. This technique has been applied to the Sandia 2-m turbine, where the changes in individual modal frequencies as a function of the rotational speed have been tracked from 9 rpm to 600 rpm. During rotational testing, the structural response was measured using a combination of strain gages and accelerometers, passing the signals through slip rings. Excitation of the turbine structure was provided by a scheme that suddenly released a pretensioned cable, thus plucking the turbine as it was rotating a ta set speed. In addition to calculating the real modes of the parked turbine, the modes of the rotating turbine were also determined at several rotational speeds. The modes of the rotating system proved to be complex because of centrifugal and Coriolis effects. The modal data for the parked turbine was used to update a finite element model. Also, the measured modal parameters for the rotating turbine were compared to the analytical results, thus verifying the analytical procedures used to incorporate the effects of the rotating coordinate system.

Modeling Blade Pitch and Solidities in Straight Bladed VAWTs – Final Report from IOPARA Inc. to Wind Harvest

Author: IOPARA Inc.

Publication: Wind Harvest International

Year Published: 2012

Coupled Vortex Effect, Synergy with Tall and Short Turbines

This report is a compilation of the aerodynamic analyses carried out by IOPARA Inc. as part of a contract project called “Modeling Blade Pitch and Solidities in Straight Bladed VAWTs,” realized under the request of Wind Harvest International Inc.

Modeling Blade Pitch and Solidities in Straight Bladed VAWTs – Final Report from Wind Harvest to CEC

Author: Robert Thomas, Kevin Wolf

Publication: Wind Harvest International

Year Published: 2012

Final report to the California Energy Commission for the Energy Innovations Small Grant Program awarded to Wind Harvest International in 2012.

Modeling Stochastic Wind Loads on Vertical Axis Wind Turbines

Author: Paul Veers

Publication: Sandia National Laboratories

Year Published: 1984

The Vertical AXIS Wind Turbine (VAWT) is a machine which extracts energy from the wind. Since random turbulence is always present, the effect of this turbulence on the wind turbine fatigue life must be evaluated. This problem is approached by numerically simulating the turbulence and calculating, In the time domain, the aerodynamic loads on the turbine blades. These loads are reduced to the form of power and cross spectral densities which can be used in standard linear structural analysis codes. The relative importance of the turbulence on blade loads is determined.

Modeling the Effects of Wind Turbines on Radar Returns

Author: Ryan Ohs, Gregory Skidmore, Gary Bedrosian

Publication: IEEE

Year Published: 2011

Wind turbines located near radar installations can significantly interfere with a radar’s ability to detect its intended targets. In order to better understand and mitigate the adverse effects of wind turbines on radar, the government and wind farm community need tools that can be used to analyze the radar returns from wind turbines. Remcom’s XGtd® software is a high frequency solver capable of calculating the radar cross section of electrically large objects. In this paper, interference from wind turbines is predicted using XGtd simulations and new post-processing algorithms that…

Morocco Mid-Level Wind Resources in Wind Farms

A projected 1,008 megawatts (MW) of the wind farms in Morocco have mid-level wind speeds over 6.5 meters per second (m/s) at 15 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

California, Country-by-Country Resources, North America, San Bernardino County

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	1,283
MWs over 6.5m/s at 15m agl (projected)	1,008
% of wind farms over 6.5m/s at 15m agl	78.5%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Movaje Desert Wind Speed Maps

Author: AWS Truepower

Publication: California Energy Commission

Year Published: 2006

Percent-Change-in-Wind-Speed-at-50m-Mojave-Desert-204x300

Percent change in wind speed at 50m map

Wind speed map at 50m

Multi-Body Unsteady Aerodynamics in 2D Applied to a Vertical-Axis Wind Turbine Using a Vortex Method

Author: David Osterberg

Publication: Uppsala Universitet

Year Published: 2010

Vertical axis wind turbines (VAWT) have many advantages over traditional Horizontal axis wind turbines (HAWT). One of the more severe problem of VAWTs are the complicated aerodynamic behavior inherent in the concept. In contrast to HAWTs the blades experience varying angle of attack during its orbital motion. The unsteady flow leads to unsteady loads, and hence, to increased risk for problems with fatigue. A tool for aerodynamic analysis of vertical axis wind turbines has been developed. The model, a Discrete vortex method, relies on conformal maps to simplify the task to finding the flow around cylinders. After the simplified problem has been solved with Kutta condition, using the Fast Fourier transform, the solution is transformed back to the original geometry yielding the flow about the turbine. The program can be used for quick predictions of the aerodynamic blade loads for different turbines allowing the method to be validated by comparing the predictions to experimental data from real vertical axis wind turbines. The agreement with experiment is good.

Near wake flow analysis of a vertical axis wind turbine by stereoscopic particle image velocimetry

Author: G. Tescione, D. Ragni, C. He, C.J. Simao Ferreira, G.J.W van Bussel

Publication: Renewable Energy

Year Published: 2014

The development of the near wake of a vertical axis wind turbine is investigated by stereoscopic particle image velocimetry. The experiments are conducted in an open-jet wind tunnel on an H-shaped rotor, operated at a tip speed ratio of 4.5 and at an average chord-based Reynolds number of 1.7 × 105. Phase-locked measurements are acquired at the turbine mid span in order to study the horizontal wake dynamics at the symmetry plane. Results show the evolution of the vorticity shed by the blade, how it organizes in large scale vortical structures at the edges of the wake and the resulting asymmetric induction field in the wake. The evolution of the blade tip vortices and the 3D wake geometry are detailed by a second…

Near-wake structure of full-scale vertical-axis wind turbines

Author: Nathaniel Wei, Ian Brownstein, J.L. Cardona, M.F. Howland, John Dabiri

Publication: J. Fluid Mech.

Year Published: 2020

Miscellaneous, Synergy with Tall and Short Turbines

To design and optimize arrays of vertical-axis wind turbines (VAWTs) for maximal power density and minimal wake losses, a careful consideration of the inherently three-dimensional structure of the wakes of these turbines in real operating conditions is needed. Accordingly, a new volumetric particle-tracking velocimetry method was developed to measure three-dimensional flow fields around full-scale VAWTs in field conditions. Experiments were conducted at the Field Laboratory for Optimized Wind Energy (FLOWE) in Lancaster, CA, using six cameras and artificial snow as tracer particles. Velocity and vorticity measurements were obtained for a 2-kW turbine with five straight blades and a 1-kW turbine with three helical blades, each at two distinct tip-speed ratios and at Reynolds numbers based on the rotor diameter D between 1.26×106and 1.81×106. A tilted wake was observed to be induced by the helical-bladed turbine. By considering the dynamics of vortex lines shed from the rotating blades, the tilted wake was connected to the geometry of the helical blades. Furthermore, the effects of the tilted wake on a streamwise horseshoe vortex induced by the rotation of the turbine were quantified.Lastly, the implications of these dynamics for the recovery of the wake were examined.This study thus establishes a fluid-mechanical connection between the geometric features of a VAWT and the salient three-dimensional flow characteristics of its near-wake region,which can potentially inform both the design of turbines and the arrangement of turbines into highly efficient arrays.

Nested Contour Dynamics Models for Axisymmetric Vortex Rings and Vortex Wakes

Author: Clara O’Farrell and John O. Dabiri

Publication: Cambridge University

Year Published: 2014

Inviscid models for vortex rings and dipoles are constructed using nested patches of vorticity. These models constitute more realistic approximations to experimental vortex rings and dipoles than the single contour models of Norbury and Pierrehumbert, and nested contour dynamics algorithms allow their simulation with low computational cost. In two dimensions, nested-contour models for the analytical Lamb dipole are constructed. In the axisymmetric case, a family of models for vortex rings generated by a piston–cylinder apparatus at different stroke ratios is constructed from experimental data. The perturbation response of this family is considered by the introduction of a small region of vorticity at the rear of the vortex,…

New blade configuration promotes peak power efficiency of vertical axis wind turbines

Author: Chris Patrick

Year Published: 2017

California, Density, North America, Riverside County, San Gorgonio Pass Wind Resource Area, Synergy with Tall and Short Turbines, Vertical Axis Wind Turbines, Wind Farms

Horizontal axis wind turbines (HAWTs) are the more common form of wind energy production, but attention is increasingly given to vertical axis wind turbines (VAWTs), which have their main rotor shaft positioned transverse the wind. VAWTs can accept wind coming from any direction and operate in harsher wind conditions. However, VAWT usage grows slower than that of HAWTs, especially in large scale, because they also have shortcomings, like trouble self-starting and lower power efficiency. To increase power efficiency, researchers from universities in China and Denmark proposed and evaluated a new blade design for H-type VAWTs. They report their findings in the Journal of Renewable and Sustainable Energy.

New Study Shows Groundbreaking Mid-Level Wind Turbines Can Almost Quadruple Wind Energy Output in the San Gorgonio Pass

Publication: The Next Generation

Year Published: 2023

Country-by-Country Resources, Oceania

A new study by Wind Harvest, a company that is building a novel type of short, utility-scale turbine, has found that mid-level wind turbines could almost quadruple the energy output in the notoriously windy San Gorgonio Pass Wind Resource Area. These turbines would provide enough energy to power 1 million California homes each year.

Find the complete press release in the resource link above.

New Zealand Mid-Level Wind Resources in Wind Farms

A projected 459 megawatts (MW) of the wind farms in New Zealand have mid-level wind speeds over 6.5 meters per second (m/s) at 15 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Acoustics, Engineering, Environmental Impacts, Miscellaneous

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	459
MWs over 6.5m/s at 15m agl (projected)	692
% of wind farms over 6.5m/s at 15m agl	66.3%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Noise Emission of a 200 kW Vertical Axis Wind Turbine

Author: Erik Mollerstrom, Fredric Ottermo, Jonny Hylander and Hans Bernhoff

Publication: Energies

Year Published: 2015

The noise emission from a vertical axis wind turbine (VAWT) has been investigated. A noise measurement campaign on a 200 kW straight-bladed VAWT has been conducted, and the result has been compared to a semi-empirical model for turbulent-boundary-layer trailing edge (TBL-TE) noise. The noise emission from the wind turbine was measured, at wind speed 8 m/s, 10 m above ground, to 96.2 dBA. At this wind speed, the turbine was stalling as it was run at a tip speed lower than optimal due to constructional constraints. The noise emission at a wind speed of 6 m/s, 10 m above ground was measured while operating at optimum tip speed and was found to be 94.1 dBA. A comparison with similar size horizontal axis wind turbines (HAWTs) indicates a noise emission at the absolute bottom of the range. Furthermore, it is clear from the analysis that the turbulent-boundary-layer trailing-edge noise, as modeled here, is much lower than the measured levels, which suggests that other mechanisms are likely to be important, such as inflow turbulence.

Noise Propagation from a Vertical Axis Wind Turbine

Author: Erik Mollerstrom, Sebastian Larsson, Fredric Ottermo, Jonny Hylander and Lars Baath

Publication: Inter-noise

Year Published: 2014

Initial noise measurements were performed on a 200kW vertical axis wind turbine (VAWT) and results were compared to that of a Vestas V27, a similar size horizontal axis wind turbine (HAWT). Multiple recording units were placed in line downwind of the turbine to investigate noise propagation. The frequency distribution of the noise were analyzed indicating that the VAWT has lower relative levels for frequencies under 3000 Hz, especially within 600-1200 Hz. Furthermore, VAWT noise seems to occur more around the same frequencies as the natural background noise, increasing masking…

Norway Mid-Level Wind Resources in Wind Farms

A projected 1,165 megawatts (MW) of the wind farms in Norway have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	2,955
MWs over 6.5m/s at 20m agl (projected)	1,165
% of wind farms over 6.5m/s at 20m agl	39.4%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Numerical Investigations of the Effects of the Rotating Shaft and Optimization of Urban Vertical Axis Wind Turbines

Author: Lidong Zhang, Kaiqi Zhu, Junwei Zhong, Ling Zhang, Tieliu Jiang, Shaohua Li and Zhongbin Zhang

Publication: Energies

Year Published: 2018

The central shaft is an important and indispensable part of a small scale urban vertical axis wind turbines (VAWTs). Normally, it is often operated at the same angular velocity as the wind turbine. The shedding vortices released by the rotating shaft have a negative effect on the blades passing the wake of the wind shaft. The objective of this study is to explore the influence of the wake of rotating shaft on the performance of the VAWT under different operational and physical parameters.

Numerical Simulation of Unsteady Flow and Aerodynamic Performance of Vertical Axis Wind Turbines with LES

Author: Akiyoshi Iida, Keiichi Kato and Akisato Mizuno

Publication: Austrailian Fluid Mechanics Conf.

Year Published: 2007

The goal of this investigation is to develop high performance Vertical Axis Wind Turbines (hereafter VAWT) for clean energy supply systems. For this purpose, we attempted to simulate flow around a VAWT with Large Eddy Simulation (LES). Since the angles of attack of VAWT are widely changed during the rotor rotation, large scale separation and interaction between the turbulent wakes are occurred [1]-[3]. Therefore, unsteady and high accuracy simulation is necessary to simulate flow around a VAWT. LES with a sliding mesh technique was utilised to solve the complicated flow around the VAWT. The numerical results show the large separation occurred and unsteady aerodynamic forces were observed in the wake of VAWT.

Numerical Simulation of VAWT Stochastic Aerodynamic Loads Produced by Atmospheric Turbulence

Author: Gregory Homicz

Publication: Sandia National Laboratories

Year Published: 1991

Blade fatigue life is an important element in determining the economic viability of the Vertical Axis Wind Turbine (VAWT). A principal source of blade fatigue is thought to be the stochastic (i.e., random) aerodynamic loads created by atmospheric turbulence. This report describes the theoretical background of the VAWT Stochastic Aerodynamic Loads (VAWT-SAL) computer code, whose purpose is to numerically simulate these random loads, given the rotor geometry, operating conditions, and assumed turbulence properties. A Double-Multiple-StreamTube (DMST) analysis is employed to model the rotor’s aerodynamic response.

Observations of dynamic stall on Darrieus wind turbine blades

Author: Noboyuki Fujisawa, Satoshi Shibuya

Publication: J. Wind Eng. and Industrial Aerodynamics

Year Published: 2001

Flow field around a Darrieus wind turbine blade in dynamic stall is studied by flow visualization and particle image velocimetry (PIV) measurement in stationary and rotating frames of reference. The experiment is carried out using the small-scale Darrieus wind turbine in a water tunnel. The unsteady nature of the dynamic stall observed by the flow visualization is quantitatively reproduced in the instantaneous velocity distributions by PIV measurement, which describes the successive shedding of two pairs of stall vortices from the blade moving upstream. The mechanism of dynamic stall is due to the successive generation of separation on the inner surface of the blade followed by the formation of roll-up vortices from the outer surface. Although the qualitative nature of the dynamic stall is independent of the tip-speed ratios, the blade angle for stall appearance and the growth rate of the stall vortices are influenced by the change in tip-speed ratios

On the structural response of two- and three-bladed vertical axis wind turbines

Author: David Malcolm

Publication: Wind Energy

Year Published: 2019

Vertical axis wind turbines have suffered from the periodic nature of the aerodynamic loads and early efforts at commercialization were plagued by fatigue issues resulting from an inability to anticipate critical resonances. This paper examines the criteria for determining whether intersections of harmonics of the rotor speeds and natural frequencies will be damaging in two‐ or three‐bladed machines. The approach involves expressing the complex natural modes and also the aerodynamic loads and structural response as components of the real, stationary modes. The results show that the symmetry offered by three‐bladed rotors leads to many intersections being benign whereas the two‐bladed rotor does not benefit in this way.

On the way to reliable aeroelastic load simulations on VAWT’s

Author: Torben Juul Larsen and Helge Aagaard Madsen

Publication: European Wind Energy Association

Year Published: 2013

California, Density, East San Diego County Wind Resource Area, H-Type, Horizontal Axis Wind Turbines, North America, San Diego County, Synergy with Tall and Short Turbines, Vertical Axis Wind Turbines, Wind Farms

In this paper a method for an implementation of a 2D actuator cylinder flow model of an Vertical Axis Wind Turbine (VAWT) is presented. The model is implemented in a full aeroelastic code including consideration of structural dynamics, dynamic inflow, tower shadow and dynamic stall, which is needed for a full load analysis relating to eg. certification of a VAWT turbine. Further on, principal load cases according to the IEC61400-1 are simulated for a fictitious 5MW VAWT turbine in it’s simplest 2 bladed Darrieus configuration. The IEC61400-1 load cases, originally developed for Horizontal Axis Wind Turbines (HAWT’s), are discussed regarding the application to VAWT’s. Further on a small section regarding aerodynamic flow in curved motion is included.

Over 500 MW of short turbines could be added to the East San Diego County Wind Resource Area

Publication: Wind Harvest International

Year Published: 2023

Wind Harvest analyzed the East San Diego County Wind Resource Area using publicly available location information and UL’s Windnavigator. The report concluded that the area could add 457 MWs of Wind Harvester type turbines to the existing 406 MWs of propeller-type turbines currently installed. Based on the mid-level wind speeds in the zone, this level of buildout would produce 1,559 GWh of electricity per year. The existing wind farms produce 1,069 GWh of electricity per year.

Parametric analysis of resistance type vertical axis wind turbines

Author: Baolin Li, Zhixin Bian, Kedi Chen

Publication: Boletín Técnico

Year Published: 2017

The performance of wind turbines is usually evaluated by proprietary parameters, but these parameters are used to analyze the dynamic performances of the blades qualitatively. Thus,it cannot exactly express the actual working performances of wind turbines. In this paper, a comparative analysis on physical meanings is made between resistance type vertical axis wind turbines and horizontal axis wind turbines. And the actual meanings of the parameters to be expressed was also discussed. The result shows that analysis theory of blades in different type of wind turbines are different. And then a design method was put forward to calculate and analyze the resistance type vertical axis wind turbines. It is concluded that wind turbines with different structures and blades have its own analysis theory and method.

Parametrical evaluation of the aerodynamic performance of vertical axis wind turbines for the proposal of optimized designs

Author: Andrés Meana-Fernández, Irene Solís-Gallego, Jesús Manuel Fernández Oro, Katia María Argüelles Díaz, Sandra Velarde-Suárez

Publication: Energy

Year Published: 2018

Many studies have tried to give insight into the optimal values of solidity and the airfoil geometry that maximize the performance and self-starting capability of vertical axis wind turbines, but there is still no consensus. In addition, most studies focus on one particular airfoil or airfoil family, which makes the generalization of the results difficult. In this work, these research gaps are intended to be assessed.

Passive Stall Control Systems of Power Limitation Modes for Vertical Axis Wind Turbines (VAWT)

Author: Ihor Shchur, Andrii Lozinskyi, Bohdan Kopchak, Yurii Biletskyi, Vsevolod Shchur

Year Published: 2017

California, Density, North America, Riverside County, San Gorgonio Pass Wind Resource Area, Synergy with Tall and Short Turbines, Vertical Axis Wind Turbines, Wind Farms

Vertical axis wind turbines (VAWT) with direct drive permanent magnet synchronous generator operate with the greatest energy efficiency and reliability in low-power wind energy conversion systems (WECS). This article offers a classification of optimal control methods of such WECS. Special attention is also given to an unexplored area—the development of control systems of power limitation mode when VAWT work at high wind speeds—passive stall and feathering control. In particular, the structures of control systems were developed, the parameters of power regulators were obtained, and these regimes were compared by means of computer simulation. The fractional order control method was also used for this mode and the parameters of fractional order PID power regulator were found by the method of Particle Swarm Optimization (PSO). The article also demonstrates how to realize the mode of passive stall control in the energy-shaping control system (ESCS) previously developed by the authors.

PATENT – Vertical Axis Wind Turbine Blade-Arm Connection Member

Publication: The Next Generation

Year Published: 2023

Patent

Additional Resource

Wind Harvest engineers (David John Malcom, Alan Ionut Munteanu, Olaaamide Ajala Inyand, Antonio owed Monge, Jeffrey Willis) are the inventors of a patented technology connecting the blades and arms of Vertical Axis Wind Turbines.

Find more information about the patent at the link above.

Performance And Wake Development of Vertical Axis Wind Turbine A LES Study Using a Vortex Particle-Mesh Method

Author: Matthieu Duponcheel, Denis-Gabriel Caprace, Gregoire Winckelmans, Philippe Chatelain

Publication: Universite Catholique de Louvain

Year Published: 2016

Performance Characteristics of a Vertical Axis Wind Turbine Operating in Different Environmental Conditions

Author: Aboufares Ghada

Publication: University of Huddersfield

Year Published: 2015

Renewable energy is an essential source for harnessing natural forces such as wind energy in an age which is very conscious of the environmental effects of burning fossil fuels, and where sustainability is an ethical norm. Therefore, the focus is currently on both the adequacy of long-term energy supply, as well as the environmental implications of particular sources. In that regard, the near certainty of costs being imposed on carbon dioxide emissions in developed countries has profoundly changed the economic outlook of clean energy sources.

Performance enhancements on vertical axis wind turbines using flow augmentation systems: A review

Author: Kok Hoe Wong, Wen Tong Chong, Nazatul Liana Sukiman, […], C.-T. Wang

Publication: J. Renewable and Sustainable Energy

Year Published: 2017

There are many advantages of vertical axis wind turbines (VAWTs) compared with horizontal axis wind turbines (HAWTs). Research has shown that VAWTs are more suitable for turbulent wind flow and urban applications. However, the efficiency and low self-start ability of VAWTs are always the main drawbacks especially for the lift-type VAWTs. Unlike HAWTs, the rotor blades for VAWTs do not always provide positive torque during operation. Many innovative designs have been implemented to improve the performance of VAWTs, and this includes different configurations and blade profiles. This paper extensively reviews various flow augmentation systems and attempts to provide information to researchers on current augmentation techniques and other relevant research. The flow augmentation system is able to increase the coefficient of power, C_P, hence improving the output power of different types of VAWTs. Some augmentation systems are able to increase the maximum power output by up to 910%. The methods and designs used to increase upwind velocity and to reduce negative torque created on the wind turbine have been discussed in detail.

Performance Evaluation of a Vertical Axis Wind Turbine Using Real-Time Measuring Wind Data

Author: Choon-Man Jang, Chul-Kyu Kim, Sang-Moon Lee, Sajid Ali

Year Published: 2018

Miscellaneous, Synergy with Tall and Short Turbines

Recently, small vertical axis wind turbine has been in the limelight as an essential component of hybrid renewable energy system, based on many advantages, such as low noise and cut-in wind speed, cost and site flexibility, etc. Turbine performance is analyzed by introducing the effect of different time averaging steps using real-time measuring wind data. All measured data through wind master is stored in the computer every second using a data acquisition system. The test turbine is installed at the island, which is located near Seoul, South Korea. Vertical axis wind turbine (VAWT) having the rated power of 1.5 kW is installed. The performance of the VAWT is compared and analyzed using 10-, 20-, and 30-min averaged data. Numerical simulation has also been performed to compare the turbine performance with experimental results. From the comparisons between experimental and numerical simulation, it is found that performance of the tested wind turbine is slightly different according to the different time-averaged data. Turbine performance analyzed by using 10-min time-averaged data, which has relatively lower standard deviation, has a good agreement to the result of numerical simulation.

Perturbation Response and Pinch-off of Vortex Rings and Dipoles

Author: Clara O’Farrell and John O. Dabiri

Publication: Cambridge University

Year Published: 2012

The nonlinear perturbation response of two families of vortices, the Norbury family of axisymmetric vortex rings and the Pierrehumbert family of two-dimensional vortex pairs, is considered. Members of both families are subjected to prolate shape perturbations similar to those previously introduced to Hill’s spherical vortex, and their response is computed using contour dynamics algorithms. The response of the entire Norbury family to this class of perturbations is considered, in order to bridge the gap between past observations of the behaviour of thin-cored members of the family and that of Hill’s spherical vortex. The behaviour of the Norbury family is contrasted with the response of the analogous…

Peru Mid-Level Wind Resources in Wind Farms

A projected 219 megawatts (MW) of the wind farms in Peru have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	410
MWs over 6.5m/s at 20m agl (projected)	219
% of wind farms over 6.5m/s at 20m agl	53.4%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Philippines Mid-Level Wind Resources in Wind Farms

A projected 118 megawatts (MW) of the wind farms in the Philippines have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	457
MWs over 6.5m/s at 20m agl (projected)	118
% of wind farms over 6.5m/s at 20m agl	25.8%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Pilot Study to Evaluate the Effectiveness of DTBird in Reducing Risk of Golden Eagles and Other Raptors Colliding with Operational Wind Turbines

Author: Jeff Smith, Jeff Zirpoli, Kristina Wolf, Judd Howell, and Scott Terril

Publication: H.T. Harvey & Associates

Year Published: 2018

Miscellaneous, Synergy with Tall and Short Turbines

The study goals were to evaluate effectiveness of DTBird automated detection and audio deterrent system in reducing the risk of Golden Eagles and other raptors entering the rotor swept zone of operating turbines and to run the first rigorous pilot study of technology in North America.

Pinch-off of Non-Axisymmetric Vortex Rings

Author: Clara O’Farrell and John O. Dabiri

Publication: Cambridge University

Year Published: 2014

The formation and pinch-off of non-axisymmetric vortex rings is considered experimentally. Vortex rings are generated using a non-circular piston–cylinder arrangement, and the resulting velocity fields are measured using digital particle image velocimetry. Three different nozzle geometries are considered: an elliptical nozzle with an aspect ratio of two, an elliptical nozzle with an aspect ratio of four and an oval nozzle constructed from tangent circular arcs. The formation of vortices from the three nozzles is analysed by means of the vorticity and circulation, as well by investigation of the Lagrangian coherent structures in the flow. The results indicate that, in all three nozzles, the maximum circulation the vortex can attain…

Portugal Mid-Level Wind Resources in Wind Farms

A projected 988 megawatts (MW) of the wind farms in Portugal have mid-level wind speeds over 6.5 meters per second (m/s) at 15 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	5,444
MWs over 6.5m/s at 15m agl (projected)	988
% of wind farms over 6.5m/s at 15m agl	18.2%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Potential life-cycle cost reductions for offshore floating wind energy

Author: Michael Borg

Publication: DTU Wind Energy

Year Published: 2015

Coupled Vortex Effect, Synergy with Tall and Short Turbines

Potential Order-Of-Magnitude Enhancement of Wind Farm Power Density Via Counter-Rotating Vertical-Axis Wind Turbine Arrays

Author: John Dabiri

Publication: J. Renewable and Sustainable Energy

Year Published: 2011

Modern wind farms comprised of horizontal-axis wind turbines (HAWTs) require significant land resources to separate each wind turbine from the adjacent turbine wakes. This aerodynamic constraint limits the amount of power that can be extracted from a given wind farm footprint. The resulting inefficiency of HAWT farms is currently compensated by using taller wind turbines to access greater wind resources at high altitudes, but this solution comes at the expense of higher-engineering costs and greater visual, acoustic, radar, and environmental impacts. We investigated the use of counter-rotating vertical-axis wind turbines (VAWTs) in order to achieve higher power output per unit land area than existing…

Predicted Costs and Benefits for VAWTs installed in Wind Farm understories

Publication: Wind Harvest International

Year Published: 2016

The three major factors leading to a projected lower Leveled Cost of Energy for VAWT created wind energy in CA than the alternatives are, they make double use of existing wind farm assets, they can be installed in high energy land where HAWTS can’t, and they can achieve the efficiencies of horizontal axis wind turbines. The table present in this document varies only these three factors when comparing VAWTs in existing wind farms to the other options.

Predictions of peak fatigue stresses in a Darrieus rotor wind turbine under turbulent winds

Author: David Malcolm

Publication: Wind Energy Symposium

Year Published: 1990

The field stress data from two locations on the blade of the Indal 500 kW Darrieus rotor have been processed into histograms of fatigue stresses and grouped according to the atmospheric turbulence intensity. The aim was to determine the magnitude of the maximum cyclic stresses on the rotor. These distributions are compared with corresponding results obtained from a frequency domain structural analysis model. Comparisons are good and confirm the greater role of turbulence in in-plane blade bending.

Public receptiveness of vertical axis wind turbines

Author: Iris Hui, Bruce Cain, John Dabiri

Publication: Elsevier Ltd.

Year Published: 2017

Most of the scholarly focus to date has been on large horizontal axis rather than vertical axis wind turbines. It may be possible to improve the efficiency of vertical axis wind technology by deploying turbines in clusters. There might also be advantages to deploying vertical axis turbines at a smaller scale in urban or suburban areas and in places where the risk of bird damage is highest. Would these features increase public acceptance of new wind turbine installations and possibly open up new areas for wind energy development?

Reduction of the Generated Aero-Acoustics Noise of a Vertical Axis Wind Turbine Using CFD (Computational Fluid Dynamics) Techniques

Author: H. Mohamed

Publication: Energy

Year Published: 2016

Miscellaneous, Synergy with Tall and Short Turbines

Noise pollution from wind turbines is an important public health issue, and strict regulations regarding noise levels for nearby residents to a wind farm is a necessity. The fact that more turbines equals higher noise levels constitutes a problem, an expansion of turbines is needed but the nearby residents should not be affected. Noise levels can be measured, but, similar to other environmental attentions, the public’s perception of the noise impact of wind turbines is in part a subjective determination. Vertical axis wind turbines are suitable to be established within the densely populated…

Renewable Fluid Dynamic Energy Derived from Aquatic Animal Locomotion

Author: John Dabiri

Publication: IOPScience

Year Published: 2007

Aquatic animals swimming in isolation and in groups are known to extract energy from the vortices in environmental ﬂows, signiﬁcantly reducing muscle activity required for locomotion. A model for the vortex dynamics associated with this phenomenon is developed, showing that the energy extraction mechanism can be described by simple criteria governing the kinematics of the vortices relative to the body in the ﬂow. In this way, we need not make direct appeal to the ﬂuid dynamics, which can be more difﬁcult to evaluate than the kinematics. Examples of these principles as exhibited in swimming ﬁsh and existing energy conversion devices are described. A beneﬁt of the developed framework is that the potentially…

Review Paper: Overview of the Vertical Axis Wind Turbines

Author: E A D Kumara, N K Hettiarachchi, K G R M Jayathilake

Publication: J. Sci. Research and Innovative Tech.

Year Published: 2017

California, Country-by-Country Resources, North America, Solano County

This paper gives an overview of a vertical axis wind turbine. The behaviour of the Vertical Axis Wind Turbine (VAWT), present technological state, new finding through modelling work and future direction of VAWTs were reviewed. It was observed that VAWT plays a vital role in the present energy crisis. Ones can foresee that human being dwelling in a world with wind turbines and solar panels due to present energy crisis with the non-renewable energy. Wind energy has been identified as a promising renewable option Although the full life cycle accounting shows VAWTs are advantageous on a cost basis or materials basis over horizontal axis wind turbines (HAWTs), Currently the VAWTs do not generate enough electricity due to some challenges which discussed in this paper. Drag driven VAWT (Savonius type), lift driven VAWT (Darrieus type) and hybrid of both (D+S) turbine efficiencies can be increased by adding the deflector system that guides the wind towards the turbine blades. A lot of researches are ongoing at present in this level. From the vast survey of the present technological states of VAWT, it was observed that China is the leading researcher in this field for the past few years while European countries serve their place in this research area.

Rio Vista Wind Energy Project Final Data Report

Author: SECOR International Incorporated

Publication: SMUD

Year Published: 2005

California, Country-by-Country Resources, North America, San Bernardino County

This report summarizes and documents operation of the doppler miniSODAR lower boundary layer wind monitoring system installed and operated at the Sacramento Municipal Utilities District (SMUD) Montezuma Hills Station. It also summarizes the data collected at the station during the period May 29 through June 28 of 2004. The goal of the project was to investigate the wind speed shear exponent at various heights above ground level (AGL) and the relation of those calculations to engineering construction options including turbine hub height and blade selection.

San Bernardino County Wind Map at 80m agl

Publication: NREL Wind Prospector

San-Bernardino-Wind-Map-80m-NREL-OpenCarto-300x197

San Gorgonio Pass Wind Resource Area Wind Speed Maps

California, Country-by-Country Resources, North America, Riverside County, San Gorgonio Pass Wind Resource Area

Author: AWS Truepower

Publication: California Energy Commission

Year Published: 2006

Wind speed map at 50m

Percent change in wind speed at 50m

Sandia Study Provides Insight into Technical and Economic Feasibility of this Less-Common Turbine Design

Author: Sandia National Laboratories

Publication: Office of EE & Renewable Energy

Year Published: 2018

Self-similarity and flow characteristics of vertical-axis wind turbine wakes: an LES study

Author: Mahdi Abkar and John Dabiri

Publication: Journal of Turbulence

Year Published: 2017

California, Density, East San Diego County Wind Resource Area, Horizontal Axis Wind Turbines, Kern County, North America, Riverside County, San Diego County, San Gorgonio Pass Wind Resource Area, Tehachapi Wind Resource Area, Turbulence, Wake, Wind Farms

Large eddy simulation (LES) is coupled with a turbine model to study the structure of the wake behind a vertical-axis wind turbine (VAWT). In the simulations, a tuning-free anisotropic minimum dissipation model is used to parameterise the subfilter stress tensor, while the turbine-induced forces are modelled with an actuator line technique. The LES framework is first validated in the simulation of the wake behind a model straight-bladed VAWT placed in the water channel and then used to study the wake structure downwind of a full-scale VAWT sited in the atmospheric boundary layer. In particular, the self-similarity of the wake is examined, and it is found that the wake velocity deficit can be well characterised by a two-dimensional multivariate Gaussian distribution. By assuming a self-similar Gaussian distribution of the velocity deficit, and applying mass and momentum conservation, an analytical model is developed and tested to predict the maximum velocity deficit downwind of the turbine. Also, a simple parameterisation of VAWTs for LES with very coarse grid resolutions is proposed, in which the turbine is modelled as a rectangular porous plate with the same thrust coefficient. The simulation results show that, after some downwind distance (x/D ≈ 6), both actuator line and rectangular porous plate models have similar predictions for the mean velocity deficit. These results are of particular importance in simulations of large wind farms where, due to the coarse spatial resolution, the flow around individual VAWTs is not resolved.

Sensitivity of Southern California Wind Energy to Turbine Characteristics

Author: Scott B. Capps, Alex Hall and Mimi Hughes

Publication: Wind Energy, John Wiley & Sons, Ltd.

Year Published: 2011

California, Country-by-Country Resources, North America, Shasta County

Capps, Hall and Hughes evaluate how variation in wind turbine characteristics such as rotor diameter, rater power and hub height affect wind energy production in Southern California.

Shasta County Wind Maps

Author: AWS Truepower

Publication: California Energy Commission

Year Published: 2006

Percent-Change-in-Wind-Speed-at-50m-Shasta-Valley-204x300

Percent change in wind speed at 50m map

Wind speed map at 50m

Shedding Light on Photosensitivity, One of Epilepsy’s Most Complex Conditions

Environmental Impacts, Shadow Flicker

Author: Giuseppe Erba

Publication: Epilepsy Foundation

Year Published: 2006

Certain individuals are born with special sensitivity to flashing lights or contrasting visual patterns, such as stripes, grids and checkerboards. Because of this condition, their brain will produce seizure-like discharges when exposed to this type of visual stimulation.

Siting Wind Turbines to Minimize Raptor Collisions at Sand Hill Repowering Project, Altamont Pass Wind Resource Area

Year Published: 2018

Map-based collision hazard models were prepared as a set of tools to help guide the careful siting of proposed new wind turbines as part of the repowering effort at Sand Hill in the eastern Alameda County portion of the Altamont Pass Wind Resource Area (APWRA). Similar collision hazard models were prepared for the Tres Vaqueros and Vasco Winds repowering projects in Contra Costa County and for the Patterson Pass, Golden Hills, Golden Hills North, Summit Winds repowering projects in Alameda County, as well as for an earlier version of the Sand Hill repowering project. After three years of fatality monitoring following construction, it was found that the repowering of Vasco Winds reduced fatalities of raptors as well as all birds as a group. Our newest set of models for Sand Hill benefit from the lessons learned at Vasco Winds, as well as from many additional data collected through 2015 and the emergence of dependent variables and predictor variables that we believe result in superior collision hazard models. The new models were derived from an additional four years of fatality monitoring data, including monitoring with much shorter fatality search intervals at repowered, modern wind turbines as well as at some old-generation wind turbines. And like the models developed for Sand Hill and Golden Hills North, the golden eagle collision hazard model was partly derived from GPS/GSM telemetry data transmitted by golden eagles (Aquila chrysaetos) flying within the APWRA.

Solano County Wind and Solar Diurnal Energy Outputs with Batteries

Battery Storage, California, Diurnal Wind Speed, North America, Solano County, Solano Wind Resource Area, Solar Energy

Author: Wind Harvest International

Year Published: 2023

California, Country-by-Country Resources, North America, Solano County, Solano Wind Resource Area

This resource contains diurnal wind speed information for Solano County, as well as diurnal wind and solar energy outputs. Wind speed data was derived from wind speeds recorded at Travis Air Force Base.

The material included in the linked document is protected by Creative Commons BY-SA copyright.

Solano County Wind Speed Map

Publication: California Energy Commission

Wind speed map at 100m

Sonic Pest Repellents

Author: Nicholas Aflitto and Tom DeGomez

Publication: U. of Arizona Cooperative Extension

Year Published: 2015

Sonic pest devices are tools that emit sound in the attempt to repel, deter, or kill unwanted animals such as insects, rodents, birds and large mammals. These devices, depending on the target species, cover a wide range of the acoustic spectrum from below what humans perceive (infrasonic) to above our hearing range (ultrasonic). Infrasonic is characterized as sound below 20Hz, whereas ultrasonic sound is defined as sound above 18,000 Hz. Ultrasonic devices are typically marketed to target arthropod (including spiders, scorpions and insect pests) and mammal pests, while devices…

South Korea Mid-Level Wind Resources in Wind Farms

A projected 137 megawatts (MW) of the wind farms in South Korea have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	1,159
MWs over 6.5m/s at 20m agl (projected)	137
% of wind farms over 6.5m/s at 20m agl	11.8%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Spain Mid-Level Wind Resources in Wind Farms

A projected 2,961 megawatts (MW) of the wind farms in Spain have mid-level wind speeds over 6.5 meters per second (m/s) at 15 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	23,948
MWs over 6.5m/s at 15m agl (projected)	2,961
% of wind farms over 6.5m/s at 15m agl	12.4%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Structural Response and Eole Code Validation of the Wind Harvester 3.1 VAWT

Aerodynamic, Aeroelastic, Computer Modeling, Fatigue Life, Frequency Response, Technology, Vertical Axis Wind Turbines, Wind Harvesters

Author: Dr. David Malcolm

Publication: Wind Harvest International

Year Published: 2023

Report

Slide Deck

This report brings together much of the structural and performance data from the operation of the Wind Harvester 3.1. The response at three of the sensors is examined in detail (the lower mast bending, lower mast torque, the bending in the middle of the upper blade, and the out-of-plane bending of the middle arm). In general, the predictions of the mean and harmonic values for the three responses are in good or acceptable agreement with the field data.

Switzerland Mid-Level Wind Resources in Wind Farms

A projected 32 megawatts (MW) of the wind farms in Switzerland have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	87
MWs over 6.5m/s at 20m agl (projected)	32
% of wind farms over 6.5m/s at 20m agl	36.7%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Taiwan Mid-Level Wind Resources in Wind Farms

A projected 1,142 megawatts (MW) of the wind farms in Taiwan have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Country-by-Country Resources, North America, Texas

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	1,142
MWs over 6.5m/s at 20m agl (projected)	1,142
% of wind farms over 6.5m/s at 20m agl	100%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Texas Mid-Level Wind Resources in Wind Farms

A projected 2,250 megawatts (MW) of the wind farms in Texas have mid-level wind speeds over 6.5 meters per second (m/s) at 15 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in state	25,439
MWs over 6.5m/s at 15m agl (projected)	2,250
% of wind farms over 6.5m/s at 15m agl	8.8%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

The Hazard Posed to Aircraft by Birds

Publication: Australian Transport Safety Bureau

Year Published: 2002

Birdstrikes continue to be a problem for aviation worldwide, costing approximately $US3 billion annually. Increasingly, funds are being directed towards research which focuses on bird control and avoidance methods. Two such methods which are proving to be successful, are the use of hand held laser devices to scare birds from the airport environment, and the use of the US developed Avian Hazard Advisory System (AHAS), which allows aircraft to avoid high-risk birdstrike areas. This study investigated the Australian birdstrike data for the period 1991 to 2001. Although limited, the available…

The Influence Of Blade Roughness On The Performance Of A Vertical Axis Tidal Turbine

Author: Luis Priegue

Publication: Thorsten Stoesser Elsevier Ltd

Year Published: 2017

This paper reports the findings of an experimental study investigating the influence of blade roughness on the performance of a vertical axis tidal turbine. Due to their design, vertical axis turbines undergo periods of stall, i.e. flow separation from the blade, during each revolution. It is hypothesised that roughening turbine blades delays flow separation (in analogy to flows over rough bluff bodies) and hence diminishes turbine stall which in turn should result in an increase in turbine performance. Laboratory experiments were undertaken in Cardiff University’s hydraulics laboratory, testing vertical axis turbines with rotors comprising smooth and rough blades.

The LIFE Computer Code Fatigue Life Prediction for Vertical Axis Wind Turbine Components

Author: Herbert J. Sutherland, Thomas D. Ashwill, Norman Slack

Publication: Sandia National Laboratories

Year Published: 1987

The LIFE computer code was originally written by Veers to analyze the fatigue life of a vertical axis wind turbine (VAWT) blade. The basic assumptions built into this analysis tool are: the fatigue life of a blade component is independent of the mean stress; the frequency distribution of the vibratory stresses may be described adequately by a Rayleigh probability density function; and damage accumulates linearly (Miner’s Rule). Further, the yearly distribution of wind is assumed to follow a Rayleigh distribution. The original program has been updated to run in an interactive mode on a personal computer with a BASIC interpreter and 256K RAM. Additional capabilities included in this update include: the generalization of the Rayleigh function for the wind speed distribution to a Weibull function; the addition of two constitutive rules for the evaluation of the effects of mean stress on fatigue life; interactive data input: and the inclusion of a stress concentration factor into the analysis.

The Near Wake Structure of a Vertical Axis Wind Turbine

Author: Kristian Dixon

Publication: Delft University of Tech.

Year Published: 2008

A 3D unsteady multi-body panel method is developed that can model arbitrary geometries. The method has been specifically designed so that it can handle the blade-wake interactions and viscous wake effects that are important for modelling a vertical axis wind turbine (VAWT). A systematic validation and verification of the model is presented against theoretical and experimental results. Validation of VAWT wake shapes is given in 2D and 3D by comparison with experimental results using several different techniques (smoke-trail, PIV, and water-tank dye injection). A generalized wake structure for a straight bladed VAWT is explained, and how this structure deforms in time and changes with tip speed ratio and height-diameter ratio.

The Nearness of Wind

Author: Kevin Wolf

Publication: North American Clean Energy

Year Published: 2021

What do you think of when you hear the wind blow? Or see clouds flying across the sky? If you ask most people about capturing the power of wind, they picture a towering wind turbine. In fact, the clean energy industry may be missing out on an oft-ignored resource: low-lying winds.

Reintroducing H-type turbines

H-type turbines are compact, ground-level wind turbines that have been around for decades. By placing these relatively short turbines in the “understory” of tall turbines, an estimated 20 percent of wind farms can profitably capture the energy of near-ground winds.

The Netherlands Mid-Level Wind Resources in Wind Farms

A projected 170 megawatts (MW) of the wind farms in the Netherlands have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	3,518
MWs over 6.5m/s at 20m agl (projected)	170
% of wind farms over 6.5m/s at 20m agl	4.8%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

The Potential of Vertical Wind Turbines in the Context of Growing Land use Conflicts and Acceptance Problems of the Wind Energy Sector

Author: Lukas Kern, Johan Valentin Seeba, Jan Schluter

Publication: Z Energiewirtsch

Year Published: 2019

Aeroelastic, Computer Modeling, VAWT History, Vertical Axis Wind Turbines

The expansion of wind power is accompanied by a decreasing social acceptance and various land-use conflicts. They are mainly caused by the large acoustic and the large visual footprint of conventional Horizontal Axis Wind Turbines (HAWTs). Currently research is carried out on a wind turbine that provides the capability to avoid these negative effects. It refers to a special type of Vertical Axis Wind Turbines (VAWTs). This wind turbine form hasn’t been at the focus of scientific or public discussion so far. The overall advantages are its low installation height and its low noise emissions resulting in a smaller visual and acoustic footprint. Recent research that combined wind energy with bioengineering also showed that the power density of VAWTs can be higher than the power density of HAWTs. By analyzing the existing literature,the potential of these wind turbines is explored in this article. Furthermore the sound propagation of these systems will be examined in more detail on the basis of an emission forecast, as there are few studies on this topic from a regional planning point of view. The results show that VAWTs provide new land-use options compared to the conventional HAWTs and could be an alternative wind turbine type within the energy transition.

The Sandia Legacy VAWT Research Program

Author: Dale Berg

Publication: Sandia National Laboratories

Year Published: 2016

This slide deck was present to Delft Technical University by Dale Berg who was a principal researcher of the Darrieus type VAWTs that Sandia National Laboratories worked on from the 1970s through the 1990s. It covers the history of Sandia’s work on VAWTs including their efforts to develop validated aeroelastic modeling.

These dogs are sniffing out solutions for safer wind farms

Publication: The Optimist Daily

Year Published: 2021

Wind turbines are a great source of renewable energy in blustery climates, but like every solution, there are potential risks to be weighed as well. Turbines take a toll on local birds, bats, and insects, and although the effects of turbines on large birds like condors and eagles are well known, we have less information on how they affect smaller animals. This is mostly because they are harder to spot. Fortunately, researchers have found a new way to sniff out the real impact of turbines: dogs.

Researchers have found that dogs deployed in turbine fields are able to locate 96 percent of dead bats, compared to the human detection rate of just six percent. This is why organizations like Rogue Detection Teams are in such high demand. The organization describes itself as a conservation-detection-dog company. They take in strays and surrendered pets to be retrained as animal-detection devices. Dogs with high energy levels and an insatiable appetite for play generally make the best detection dogs.

Three Pitch Control Systems for Vertical Axis Wind Turbines Compared

Author: L. Lazauskas

Publication: Wind Engineering

Year Published: 1992

The desirable performance attributes of a vertical axis wind turbine (VAWT) include high starting torque, high peak efficiency, broad operating range and a reasonable insensitivity to the parameters that define its operation. The theoretical performances of three variable pitch mechanisms for VAWT are compared. Cycloturbines use cam devices or gears to impose a sinusoidal pitch regime. In the mass-stabilised system, pitch is determined by the interplay of two opposing moments on the blades. These two mechanisms are compared with “Aeropitch”, a hypothetical pitch control system in which stabilising moments are related to the blade relative velocity.

Torque Ripple in a Vertical Axis Wind Turbine

Author: Robert Reuter, Mark Worstell

Publication: Sandia National Laboratories

Year Published: 1978

Torque ripple is a name given to time variations in torque which are propagated through the drive train of wind energy conversion systems.This paper covers an analytical and experimental investigation of torque ripple in a Darrieus vertical axis wind turbine. An analytical model of the turbine is described and numerical results from a solution to the equations of this model are compared to experimental results obtained from the existing DOE/Sandia 17 meter vertical axis wind turbine. Discussions on the sources of torque ripple, theoretical and experimental correlation, and means of suppressing its magnitude are included.

Towards accurate CFD simulations of vertical axis wind turbines at different tip speed ratios and solidities

Author: Abdolrahim Rezaeiha, Hamid Montazeri, Bert Blocken

Publication: Elsevier Ltd.

Year Published: 2017

Towards accurate CFD simulations of vertical axis wind turbines at different tip speed ratios and solidities: Guidelines for azimuthal increment, domain size and convergence

Author: Sam Kanner, Per-Olof Persson

Publication: Energy Conversion and Management

Year Published: 2018

The accuracy of CFD simulations of vertical axis wind turbines (VAWTs) is known to be significantly associated with the computational parameters, such as azimuthal increment, domain size and number of turbine revolutions before reaching a statistically steady state condition (convergence). A detailed review of the literature, however, indicates that there is a lack of extensive parametric studies investigating the impact of the computational parameters. The current study, therefore, intends to systematically investigate the impact of these parameters, on the simulation results to guide the execution of accurate CFD simulations of VAWTs at different tip speed ratios (λ) and solidities (σ). The evaluation is based on 110 CFD simulations validated with wind-tunnel measurements for two VAWTs. Instantaneous moment coefficient, C_m, and power coefficient, C_P, are studied for each case using unsteady Reynolds-averaged Navier-Stokes (URANS) simulations with the 4-equation transition SST turbulence model. The results show that the azimuthal increment dθ is largely dependent on tip speed ratio. For moderate to high λ, the minimum requirement for dθ is 0.5° while this decreases to 0.1° at low to moderate λ. The need for finer time steps is associated to the flow complexities related to dynamic stall on turbine blades and blade-wake interactions at low λ. In addition, the minimum distance from the turbine center to the domain inlet and outlet is 15 and 10 times the turbine diameter, respectively. It is also shown that 20–30 turbine revolutions are required to ensure statistically converged solutions. The current findings can serve as guidelines towards accurate and reliable CFD simulations of VAWTs at different tip speed ratios and solidities.

Towards Performance Improvements in Vertical Axis Wind Turbines: Improving Wind Tunnel Simulations of the Atmospheric Boundary Layer and Wake Interaction Studies

Author: Tristen Charles Hohman

Publication: Princeton University

Year Published: 2017

The performance and wake structure of a model vertical axis wind turbine (VAWT)is studied, subject to various blade geometries, modes of operation, and inflow conditions. To facilitate this investigation, the neutral atmospheric boundary layer (ABL) must be simulated in a short recirculating wind tunnel. This is achieved using a modified form of Counihan’s method, composed of passive devices including a barrier wall, elliptical vortex generators, and wall roughness elements. Improvements to these elements resulted in a 1∶1000 scale representation of the neutral ABL, with turbulence characteristics that match well with both rough wall boundary layer measurements and full-scale atmospheric measurements alike. Good span wise and stream wise uniformity of this simulated ABL was achieved in only five boundary layer depths,δ,allowing approximately half of the wind tunnel test section for turbine measurements…

Transition to bluff-body dynamics in the wake of vertical-axis wind turbines

Author: Daniel Araya, Tim Colonius and John Dabiri

Publication: J. Fluid Mech.

Year Published: 2017

We present experimental data to demonstrate that the far wake of a vertical-axis wind turbine (VAWT) exhibits features that are quantitatively similar to that of a circular cylinder with the same aspect ratio. For a fixed Reynolds number (Re ≈ 0.8 × 10^5) and variable tip-speed ratio, two-dimensional particle image velocimetry (PIV) is used to measure the velocity field in the wake of four different laboratory-scale models: a 2-bladed, 3-bladed and 5-bladed VAWT, as well as a circular cylinder. With these measurements, we use spectral analysis and proper orthogonal decomposition (POD) to evaluate statistics of the velocity field and investigate the large-scale coherent motions of the wake. In all cases, we observe three distinct regions in the VAWT wake: (i) the near wake, where periodic blade vortex shedding dominates; (ii) a transition region, where growth of a shear-layer instability occurs; (iii) the far wake, where bluff-body wake oscillations dominate. We define a dynamic solidity parameter, σ_D , that relates the characteristic scales of the flow to the streamwise transition location in the wake. In general, we find that increasing σ_D leads to an earlier transition, a greater initial velocity deficit and a faster rate of recovery in the wake. We propose a coordinate transformation using σ_D in which the minimum velocity recovery profiles of the VAWT wake closely match that of the cylinder wake. The results have implications for manipulating VAWT wake recovery within a wind farm.

Tunisia Mid-Level Wind Resources in Wind Farms

A projected 189 megawatts (MW) of the wind farms in Tunisia have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Engineering, Miscellaneous, Synergy with Tall and Short Turbines, Turbulence

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	243
MWs over 6.5m/s at 20m agl (projected)	189
% of wind farms over 6.5m/s at 20m agl	77%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Turbulence in Vertical Axis Wind Turbine Canopies

Author: Matthias Kinzel, Daniel Araya and John Dabiri

Publication: Physics of Fluids

Year Published: 2015

Experimental results from three different full scale arrays of vertical-axis wind turbines (VAWTs) under natural wind conditions are presented. The wind velocities throughout the turbine arrays are measured using a portable meteorological tower with seven, vertically staggered, three-component ultrasonic anemometers. The power output of each turbine is recorded simultaneously. The comparison between the horizontal and vertical energy transport for the different turbine array sizes shows the importance of vertical transport for large array conﬁgurations. Quadrant-hole analysis is employed to gain a better understanding of the vertical energy transport at the top of the VAWT arrays. The results show a striking…

Turbulence influence on optimum tip speed ratio for a 200 KW wind turbine

Engineering, Turbulence

Author: Erik Mollerstrom, Fredric Ottermo, Anders Goude, Sandra Eriksson, Jonny Hylander

Publication: J. Physics: Conference Series

Year Published: 2019

The influence of turbulence intensity (TI) on the tip speed ratio for maximum power coefficient, here called λCp_max, is studied for a 200 kW VAWT H-rotor using logged data from a 14 month period with the H-rotor operating in wind speeds up to 9 m/s. The TI – λCp_max relation is examined by dividing 10 min mean values in different turbulence intensity ranges and producing multiple CP(λ) curves. A clear positive relation between TI and λCp_max is shown and is further strengthened as possible secondary effects are examined and deemed non-essential. The established relation makes it possible to tune the control strategy to enhance the total efficiency of the turbine.

Turbulence influence on wind energy extraction for a medium size vertical axis wind turbine

Engineering, Turbulence

Author: Erik Mollerstrom, Fredric Ottermo, Anders Goude, Sandra Eriksson, Jonny Hylander, Hans Bernhoff

Publication: Wind Energy

Year Published: 2016

Asia, Country-by-Country Resources, Europe, Horizontal Axis Wind Turbines, Vertical Axis Wind Turbines, Wind Farms

The relation between power performance and turbulence intensity for a VAWT H-rotor is studied using logged data from a 14 month (discontinuous) period with the H-rotor operating in wind speeds up to 9 m/s. The turbine, designed originally for a nominal power of 200 kW, operated during this period mostly in a restricted mode due to mechanical concerns, reaching power levels up to about 80 kW. Two different approaches are used for presenting results, one that can be compared to power curves consistent with the International Electrotechnical Commission (IEC) standard and one that allows isolating the effect of turbulence from the cubic variation of power with wind speed. Accounting for this effect, the turbine still shows slightly higher efficiency at higher turbulence, proposing that the H-rotor is well suited for wind sites with turbulent winds. The operational data are also used to create a Cp(λ) curve, showing slightly lower Cp compared with a curve simulated by a double multiple streamtube model.

Turkey Mid-Level Wind Resources in Wind Farms

A projected 1 gigawatt (GW) of the wind farms in Turkey have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Country-by-Country Resources, Europe, Horizontal Axis Wind Turbines, Wind Farms

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country	8,251
MWs over 6.5m/s at 20m agl (projected)	1,048

This data came from thewindpower.net and UL’s Windnavigator.

The linked Wind Farm Details data set is shared under Creative Commons Copyright terms.

Publication: Wind Harvest International

United Kingdom Mid-Level Wind Resources in Wind Farms

Summary of onshore wind farms
Existing GWs of HAWT wind farms in country	15.1
GWs of HAWTs over 6.5m/s at 20m agl (projected)	6.2
% of wind farms over 6.5m/s at 20m agl	41%

HAWT: Horizontal Axis Wind Turbine

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Wind Summary & Farm Details

Country-by-Country Resources, North America

United States Mid-Level Wind Resources in Wind Farms

A projected 22,059 megawatts (MW) of the wind farms in the United States (excluding California) have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in country (excluding CA)	104,212
MWs over 6.5m/s at 20m agl (projected)	22,059
% of wind farms over 6.5m/s at 20m agl	21.1%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Unsteady Flow Numerical Simulation of Vertical Axis Wind Turbine

Author: Du Gang, Wu Chun Kau

Publication: Elsevier Ltd.

Year Published: 2015

California, Country-by-Country Resources, North America, San Francisco County

This paper sets up model of the flow field for vertical axis wind turbine based on airfoil DU93-W 210. FLUENT is used to solve the two dimensional unsteady incompressible N-S equations with RNG κ ε turbulence model. COUPLE algorithm and sliding mesh is used to simulate the 2-D unsteady flow field of the wind turbine. The rotor power coefficient of wind energy and the variation of the wind turbine’s total torque are analyzed under the variation of varied blade installation angle and chord length. As the result shows, the power coefficient of wind energy at the best installation angle is increased by 2%, and the power coefficient of wind energy in the best solidity is increased by 15%.

Urban Wind Power Assessment

Author: California Wind Energy Collaborative

Publication: California Energy Commission

Year Published: 2014

This project was a preliminary investigation of the wind resource in urban areas. Five buildings in two zones within the city of San Francisco were chosen to assess near surface winds on buildings by wind‐tunnel testing in the Atmospheric Boundary Layer Wind Tunnel at the University of California, Davis. Three buildings located near 10th Street and Market Street—Fox Plaza, the CSAA Building and the Bank of America Building—were tested for two settings. The first setting was actual and included existing buildings and approved developments in the area. The second setting was cumulative, which included proposed development projects and provided what the city might look like in the near future. Two buildings near Folsom Street and Main Street were wind‐tunnel tested for the existing setting only. It was shown that the wind for all of the buildings tested near 10th Street and Market Street averaged “good,” (more than 400 watts per square meter) or “great,” (more than 700 watts per square meter) average wind power density values for the existing and cumulative settings. The two buildings near Folsom Street and Main Street had average values of approximately 234 watts per square meter each.

Uruguay Mid-Level Wind Resources in Wind Farms

A projected 219 megawatts (MW) of the wind farms in Uruguay have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in the country	1,572
MWs over 6.5m/s at 20m agl (projected)	65
% of wind farms over 6.5m/s at 20m agl	4.1%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Use of Avoidance Rates in the SNH Wind Farm Risk Collision Model

Author: Blair Urquhart

Publication: Scottish Natural Heritage

Year Published: 2010

The SNH Collision Risk Model (CRM) provides an estimate of the potential number of bird collisions likely to occur at a proposed wind farm. Birds react to a wind farm in different ways. Some may be displaced from the area of the wind farm, while others may avoid turbines or take other evasive action to prevent a collision. The CRM first estimates the number of collisions that would occur if the birds were to take no avoidance action. It then applies an avoidance rate to take account of the likely degree of successful avoidance.

Validation and comparison of a newly developed aeroelastic design code for VAWT

Author: David Marten, Matthew Lennie, Georgios Pechlivanoglou, Christian Oliver Paschereit, Norbert Dy, Ion Paraschivoiu, Farooq Saeed

Publication: Wind Energy Symposium

Year Published: 2017

The open source simulation code QBLADE, based on a Lifting Line Free Vortex Wake formulation to evaluate the unsteady aerodynamics, recently integrated the PROJECT-CHRONO FEA library that, by using Euler-Bernoulli beams in a corotational formulation, solves for the structural dynamics to achieve an aeroelastic coupling. To validate the newly implemented structural model its performance is compared to literature data and two other structural computer codes. The comparison is based on a modal analysis, steady- and aeroelastic simulations of the SNL 34m VAWT testbed for which the aerodynamic and structural properties are well known. The structural loads are obtained from IEC 61400-1 design load cases. In one of the calculated load cases an aeroelastic instability could be observed which confirms similar observations that have previously been reported in the literature.

Validation of a suite of codes for the structural response of vertical axis wind turbines

Author: David Malcolm

Year Published: 2017

Computer Modeling, Frequency Response

The vertical axis wind turbine was “re-invented” in 1970 by Peter South and Raj Rangi [1] of the Canadian National Research Council, Ottawa, where much development was carried out. Considerable development was also carried out at Sandia National Laboratories, New Mexico, especially into the structural dynamics of the curved Darrieus rotor [2, 3]. It was determined that the rotating frame effects of Coriolis action, rotational softening, and pretensioning played important roles.

Validation of a suite of codes for the structural response of vertical axis wind turbines

Author: David Malcolm

Publication: Wind Harvest International

Year Published: 2017

Validation of High-Order Wall-Resolved Large-Eddy Simulation of Vertical-Axis Wind Turbines

Author: Sam Kanner, Per-Olof Persson

Publication: University of California Berkeley

Year Published: 2018

A high-order Wall-Resolved Implicit Large Eddy Simulation (WR-ILES) method is used to simulate a vertical-axis wind turbine in 2D and 3D. In this work, we perform these simulations at nearly full-scale Reynolds numbers (O(105)). The high-order simulations are compared to experimental wind tunnel data, where the turbine blades were outfitted with pressure sensors. The wind turbine is also simulated with a low-order, finite volume method found in Open FOAM. The results of tangential forces are compared and it is shown that both methods adequately estimate the forces in the upwind section of the blade. The flow structure at various time instances is shown in 2D and 3D.

Venezuela Mid-Level Wind Resources in Wind Farms

A projected 100 megawatts (MW) of the wind farms in Venezuela have mid-level wind speeds over 6.5 meters per second (m/s) at 20 meters above ground level (agl). These wind farms could double their output by adding H-Type wind turbines like Wind Harvesters under and around existing turbines.

Summary of onshore wind farms and H-type turbine potential
Existing MWs of wind farms in the country	126
MWs over 6.5m/s at 20m agl (projected)	100
% of wind farms over 6.5m/s at 20m agl	79.3%

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Vertical Axis Wind Turbine Acoustics

Author: Charlie Pearson

Publication: Cambridge University

Year Published: 2013

Increasing awareness of the issues of climate change and sustainable energy use has led to growing levels of interest in small-scale, decentralised power generation. Small-scale wind power has seen signi_cant growth in the last ten years, partly due to the political support for renewable energy and the introduction of Feed In Tari_s, which pay home owners for generating their own electricity. Due to their ability to respond quickly to changing wind conditions, smallscale vertical axis wind turbines (VAWTs) have been proposed as an e_cient solution for deployment in built up areas, where…

Vertical Axis Wind Turbine Design Load Cases Investigation and Comparison with Horizontal Axis Wind Turbine

Aerodynamic, Computer Modeling, Design, Engineering

Author: Christos Galinos, Torben Larsen, Helge Madsen, Uwe Paulsen

Publication: Energy Procedia

Year Published: 2016

Presentation

The paper studies the applicability of the IEC 61400-1 ed.3, 2005 International Standard of wind turbine minimum design requirements in the case of an onshore Darrieus VAWT and compares the results of basic Design Load Cases (DLCs) with those of a3-bladed HAWT. The study is based on aeroelastic computations using the HAWC2 aero-servo-elastic code A 2-bladed 5MW VAWT rotor is used based on a modified version of the DeepWind rotor For the HAWT simulations the NREL 3-bladed 5MW reference wind turbine model is utilized Various DLCs are examined including normal power production, emergency shut down and parked situations, from cut-in to cut-out and extreme wind conditions.

Vertical Axis Wind Turbine Evaluation and Design

Author: Lucas Desadze, Drew Digeser, Christopher Dunn, Dillon Shoikat

Publication: Worcester Polytechnic Institute

Year Published: 2013

This project studied the potential for installing roof-mounted vertical axis wind turbine (VAWT) systems on house roofs. The project designed several types of VAWT blades with the goal of maximizing the efficiency of a shrouded turbine. The project also used a wind simulation software program, WASP, to analyze existing wind data measured on the roofs of various WPI buildings. Scale-model tests were performed in the WPI closed-circuit wind tunnel. An RPM meter and a 12 volt step generator were used to measure turbine rotation speeds and power output at different wind speeds. The project also studied roof mounting systems for turbines that are meant to dissipate vibrations to the roof structure. Turbine vibrations were measured during the wind tunnel tests and in impact tests on a scale-model house. Recommendations were made for future designs of roof-mounted VAWTs.

Vertical Axis Wind Turbine Experiments at Full Dynamic Similarity

Author: M.A. Miller, S. Duvviri, Ian Brownstein, John Dabiri, M. Hultmark

Publication: J. Fluid Dynamics

Year Published: 2018

Laboratory experiments were performed on a geometrically scaled vertical-axis wind turbine model over an unprecedented range of Reynolds numbers, including and exceeding those of the full-scale turbine. The study was performed in the high-pressure environment of the Princeton High Reynolds number Test Facility (HRTF). Utilizing highly compressed air as the working fluid enabled extremely high Reynolds numbers while still maintaining dynamic similarity by matching the tip speed ratio (defined as the ratio of tip velocity to free stream, $𝜆 = 𝜔 R / U$ ) and Mach number (defined at the turbine tip, $M a = 𝜔 R / a$ ). Preliminary comparisons are made with measurements from the full-scale field turbine. Peak power for both the field data and experiments resides around $𝜆 = 1$ . In addition, a systematic investigation of trends with Reynolds number was performed in the laboratory, which revealed details about the asymptotic behaviour. It was shown that the parameter that characterizes invariance in the power coefficient was the Reynolds number based on blade chord conditions ( $R e_{c}$ ). The power coefficient reaches its asymptotic value when $R e_{c} > 1.5 \times 10^{6}$ , which is higher than what the field turbine experiences. The asymptotic power curve is found, which is invariant to further increases in Reynolds number.

Vertical Axis Wind Turbine Farms: Modeling and Optimization

Author: Elie Bou-Zeid and Alexander Smits

Publication: Princeton Environmental Institute

Year Published: 2013

Vertical axis wind turbines (VAWTs) are proposed as an alternative to the more commonly used horizontal axis wind turbines (HAWTs) due to the potential increase in packing density (reduction in distance between turbines) that is possible with VAWTs. But for VAWTs to be more widely adopted and for their advantages to be maximized, more work is needed in the turbine and farm designs. This project aims at improving the design of VAWTS and their configurations in large farms.This work has major impacts on the adaptation and development of wind as an alternative energy source in the US and worldwide; wind is already the fastest growing energy source in the US (as a percent increase on previous installed capacity for a given source). The project team has generated an artificially thickened boundary layer in the MAE wind tunnel in order to test scale models of wind turbines. Tests of the original flow indicated that improvements were required to remove the cross-stream variations in the profile. They have now achieved a flow that closely matches the wind profile, turbulence levels, and spectrum seen in the atmospheric boundary layer. Their tests on a model VAWT in the original thick boundary layer are now being repeated and performance results are expected shortly. They have also implemented a VAWT representation (that resolves the force on each individual blade) in a large eddy simulation code and we proceeding with validation of the approach and modeling of various configurations of multiple turbines to understand their interactions and optimize farm configuration.

Vertical Axis Wind Turbine Radar Impact Assessment

Author: Chris New, Sebastian Di Laura

Publication: QinetiQ Proprietary

Year Published: 2008

QinetiQ was contracted by the Air Defence and Air Traffic Services Integrated Project Team to predict and measure the radar cross section (RCS) of a vertical axis wind turbine (VAWT), as well as assess the potential impact it would have on radar. The VAWT used for the study was the Quiet Revolution (QR) qr5, a 7kW turbine that is roughly 5 metres high and 3 metres in width. To predict the RCS of the VAWT, a computer aided design (CAD) model was created, with a finite element mesh applied to it.

Vertical Axis Wind Turbines – History Technology and Applications

Author: Marco D’ Ambrosio, Marco Medaglia

Publication: Hogskolan Halmstad

Year Published: 2010

In these Master Thesis a review of different type of vertical axis wind turbines (VAWT) and an preliminary investigation of a new kind of VAWT are presented. After an introduction about the historical background of wind power, the report deals with a more accurate analysis of the main type of VAWT, showing their characteristics and their operations. The aerodynamics of the wind turbines and a review of different type on generators that can be used to connect the wind mill to the electricity grid are reported as well. Several statistics are also presented, in order to explain how the importance of the wind energy has grown up during the last decades and also to show that this development of the market of wind power creates new opportunity also for VAWT, that are less used than the horizontal axis wind turbine (HAWT).

Vertical Axis Wind Turbines Current Technologies and Future Trends

Author: J. Damota, I. Lamas, A. Couce, J. Rodriguez

Publication: J. Renewable Energy & Power Quality

Year Published: 2015

This paper, based on the pursuit of scientific articles published and recorded in the last five years (2010-2014) patents on VAWT technology, gives an image of the current situation of the treated technology. From data extracted we know:The different models that are working with different geometries, distinguishing between Savonius, Darrieus, hybrid of both (D+S), models dedicated to Offshore technology and what can be applied generally (D&S) on both types of VAWT (controllers, electric generators, materials …). The main countries that research and develop VAWT technology, globally and at European level and the number of dedicated studies and patents each. Multiple applications that can be given in fields such as building, industrial environment, social areas, civil engineering and other more. Future trends for VAWT, which can be seen in our environment, both rural and urban, as has already happened with other renewable technologies for electricity production, as HAWT and photovoltaic (PV), becoming part of the mix of renewable energy technology and business network of the future, thereby contributing to the reduction of CO2 production and economic growth.

Vertical-Axis Wind Turbines Revisited A Sandia Perspective

Author: Matt Barone, Josh Paquette

Publication: Sandia National Laboratories

Year Published: 2012

Computer Modeling, Frequency Response

Vibration Analysis of a Vertical Axis Wind Turbine Blade

Author: K. McLaren, S. Tullis and S. Ziada

Publication: McMaster University

Year Published: 2007

Environmental Impacts, Visual

The motivation for this project arose from an expected vibration source of a small-scale vertical axis wind turbine currently undergoing field-testing. The turbine consists of three 3-metre long vertically aligned blades each fixed to the central shaft by two horizontal arms and separated from one another by an angle of =120º. The blade profile is a NACA 0015 with a chord length of 0.4 metres fixed at zero angle of attack to the support arms. The turbine optimally operates at a blade-tip speed ratio (the ratio of the blade rotational velocity to the ambient wind velocity) of 1.6.

Visual impact Evaluation of a Wind Park in a Greek Island

Author: Theocharis Tsoutsosa, Androniki Tsouchlarakia, Manolis Tsiropoulosa, Michalis Serpetsidakisb

Publication: Applied Energy

Year Published: 2009

Miscellaneous, Synergy with Tall and Short Turbines

The visual impact of wind turbines is one of the main factors affecting public acceptance of wind parks. This paper evaluates the visual impact of a wind park in Chania, Crete, using the Spanish method of evaluation. The outcomes are combined with the psychometric testing of the residents by the use of questionnaires and with the values of the Spanish method about various scenarios concerning the size of the wind park (double, half, one wind turbine). The results of the study prove that the quantification of the potential visual impact could minimize this, apparently, main reason that affects public acceptance.

Vortex Shedding From A Spinning Cylinder

Author: F. Diaz, J. Gavalda, J. G Kawall, J.F. Keffer, and F. Giralt

Publication: Universitat de Barcelona

Year Published: 1983

Vortex Suppression And Drag Reduction in the Wake of Counter-Rotating Cylinders

Author: Andre Chang, Peter Dewey, Antony Jameson, Chunlei Liang, Alexander Smits

Publication: Stanford University

Year Published: 2011

The ﬂow over a pair of counter-rotating cylinders is investigated numerically and experimentally. It is demonstrated that it is possible to suppress unsteady vortex shedding for gap sizes from one to ﬁve cylinder diameters, at Reynolds numbers from 100 to 200, expanding on the more limited work by Chan & Jameson (Intl J. Numer. Meth. Fluids, vol. 63, 2010, p. 22). The degree of unsteady wake suppression is proportional to the speed and the direction of rotation, and there is a critical rotation rate where a complete suppression of ﬂow unsteadiness can be achieved. In the doublet-like conﬁguration at higher rotational speeds, a virtual elliptic body that resembles a potential doublet is formed, and the drag is reduced to…

Vortex-Enhanced Propulsion

Author: Lydia Ruiz, Robert Whittlesey, John Dabiri

Publication: Cambridge University

Year Published: 2010

It has been previously suggested that the generation of coherent vortical structures in the near-wake of a self-propelled vehicle can improve its propulsive eﬃciency by manipulating the local pressure ﬁeld and entrainment kinematics. This paper investigates these unsteady mechanisms analytically and in experiments. A self-propelled underwater vehicle is designed with the capability to operate using either steady-jet propulsion or a pulsed-jet mode that features the roll-up of large-scale vortex rings in the near-wake. The ﬂow ﬁeld is characterized by using a combination of planar laser-induced ﬂuorescence, laser Doppler velocimetry and digital particle-image velocimetry. These tools enable measurement of vortex dynamics and…

Wake Flow Simulation Of A Vertical Axis Wind Turbine Under The Influence Of Wind Shear

Author: Victor Mendoza, Anders Goude

Publication: J. Physics: Conference Series

Year Published: 2017

The current trend of the wind energy industry aims for large scale turbines installed in wind farms. This brings a renewed interest in vertical axis wind turbines (VAWTs) since they have several advantages over the traditional Horizontal Axis Wind Turbines (HAWTs) for mitigating the new challenges. However, operating VAWTs are characterized by complex aerodynamics phenomena, presenting considerable challenges for modeling tools. An accurate and reliable simulation tool for predicting the interaction between the obtained wake of an operating VAWT and the flow in atmospheric open sites is fundamental for optimizing the design and location of wind energy facility projects. The present work studies the wake produced by a VAWT and how it is affected by the surface roughness of the terrain, without considering the effects of the ambient turbulence intensity. This study was carried out using an actuator line model (ALM), and it was implemented using the open-source CFD library Open FOAM to solve the governing equations and to compute the resulting flow fields. An operational H-shaped VAWT model was tested, for which experimental activity has been performed at an open site north of Uppsala-Sweden. Different terrains with similar inflow velocities have been evaluated.Simulated velocity and vorticity of representative sections have been analyzed. Numerical results were validated using normal forces measurements, showing reasonable agreement.

What Can Birds Hear?

Author: Robert C. Beason

Publication: USDA Wildlife Services

Year Published: 2004

For birds, hearing is second in importance only to vision for monitoring the world around them. Avian hearing is most sensitive to sounds from about 1 to 4 kHz, although they can hear higher and lower frequencies. No species of bird has shown sensitivity to ultrasonic frequencies (>20 kHz). Sensitivity to frequencies below 20 Hz (infrasound) has not received much attention; however, pigeons and a few other species have shown behavioral and physiological responses to these low frequencies. In general, frequency discrimination in birds is only about one-half or one-third as good it is for…

Why Bats Can’t See Wind Turbines

Author: David Gallagher

Publication: Cal Poly BIO 502

Year Published: 2013

If you have driven over Tehachapi Pass on Highway 58, you probably could not have helped but notice the 500 or so wind turbines that dot the ridges. These turbines make-up the Alta Wind Energy Center, the largest wind farm in the United States at 1,320 Mega-Watts. Wind energy in the United States and around the world is expanding quickly.

Wind Energy Landscapes: Society and Technology in the California Desert

Bats, California, Environmental Impacts, North America, Riverside County, San Gorgonio Pass Wind Resource Area, Visual, Wildlife, Wind Farms

Author: MARTIN J. PASQUALETTI

Publication: Society and Natural Resources, Taylor & Francis

Year Published: 2001

Alameda/Contra Costa Counties, California, Country-by-Country Resources, North America, Solano County, Solano Wind Resource Area

Abstract:

There may be no more conspicuous example of a conflict between society and technology than a wind energy landscape. The fastest growing renewable energy resource in the world, wind energy has evoked a cool public response. Through the use of interviews, the published literature, governing legislation, and personal experience, this article examines this conflict near Palm Springs, California. Its purpose is to summarize and explain the opposition that developed there from the earliest days, what has been done to mitigate it, and how the local experience is reflected in similar developments elsewhere. This particular conflict between society and technology has the potential, with proper guidance, controls, and sensitivity, to diminish with time.

Wind Energy Prospecting in Alameda and Solano Counties

Author: Earl Davis and Ron Nierenberg

Publication: California Energy Commission

Year Published: 1980

The Pacific Gas and Electric Company and the California Energy Commission conducted a wind energy prospecting program in Northern California. Eight candidate areas were initially considered and qualitatively evaluated; two areas in the San Francisco Bay Area were selected for study. a total of 23 sites were instrumented at the 30 ft level. Data were collected and analyzed for the ten-month period of March through December, 1979.

Wind Farm ‘Hits Eagle Numbers’

Publication: BBC News

Year Published: 2006

Wind farm turbine blades are killing a key population of Europe’s largest bird of prey, UK wildlife campaigners warn.

Wind Harvest’s VAWT-Bird Collision Calculator

Author: Matthew Wylder

Publication: Wind Harvest International

Year Published: 2014

Directions to set up Calculator

Calculator

WHI commissioned UCD engineer Matt Wylder to take the Scottish Natural Heritage model for calculating bird strikes in HAWTs and redo it for VAWTs. His paper “Vertical Axis Wind Turbines and Birds: Calculating a Theoretical Collision Risk Assuming No Avoiding Action” summarizes a number of runs he made using the VAWT collision model he developed. We welcome people to use and improve upon this tool.

Command Line

Python Script

Wind Harvester Model 3.0 Prototype

Prototypes, Vertical Axis Wind Turbines, Wind Harvesters

Author: Kevin Wolf

Publication: Wind Harvest International

Year Published: 2015

Prototypes, Vertical Axis Wind Turbines, Wind Harvesters

The most significant changes incorporated into the Wind Harvester 3.0 were cantilevering the basic H-type rotor, dramatically lowering its solidity, and moving from induction generation to power converters. The work produced by Wind Harvest European engineers Charliaos (Haris) Kotsarinis (aerodynamic modeling), Ionut Munteanu (cantilevered mechanical engineering), and Pablo Paz (electrical engineering) formed the basis of the design. In 2015 Antonio Ojeda and David Malcolm were brought on board to serve as Lead Engineer and Senior Engineer. They completed the modeling of model 3.0 and the redesign of model 3.1

Wind Harvester Models 1.0 and 2.0 Prototype

Author: Kevin Wolf

Publication: Wind Harvest International

Year Published: 2012

Environmental Impacts, Shadow Flicker

Wind Harvest had never tested a three-bladed configuration. There was concern that the longer distance between each blade in the rotor’s circumference would create a problematic “torque ripple” in the energy output. Model 1.0 used the same blade configuration as the 530G with 12 blades essentially placed 30 degrees apart from each other. This smoothed out the torque but the 24 arms and blade ends created significant drag. Model 2.0 used the same 12 blades but aligned them so that there were only 6 exposed blade ends and 12 arms. The good news was that 2.0 did not produce any significant torque ripple that harmed power quality and was more efficient at producing energy.

Wind Power and Human Health: Flicker, Noise and Air Quality

Author: Erik Nordman

Publication: Grand Valley State University

Year Published: 2010

Shadow flicker occurs when the sun is low in the sky and a wind turbine creates a shadow on a building. As the turbine blades pass in front of the sun, a shadow moves across the landscape, appearing to flick on and off as the turbine rotates. The location of the turbine shadow varies by time of day and season and usually only falls on a single building for a few minutes a day. Shadows that fall on a home may be disruptive. Shadow flicker has been a concern in Northern Europe where the high latitude and low sun angle exacerbate the effect.

Wind Technologies Market Report

Author: Ryan Wiser, Mark Bollinger

Publication: Berkeley Lab

Year Published: 2016

This report shows that in the early years (1982-2004) of HAWT development, the industry realized a “learning curve” of 14.4%, meaning that costs per kWh dropped at this rate year on year. WHI predicts that VAWTs will realize a similar “learning curve” as they increase in sales.

Wind Tunnel and Numerical Study of a Small Vertical Axis Wind Turbine

Aerodynamic, Computer Modeling, Engineering, Miscellaneous

Author: Jonathan Edwards, Naveed Durrani, Robert Howell and Ning Qin

Publication: Renewable Energy

Year Published: 2010

Coupled Vortex Effect, Synergy with Tall and Short Turbines

This paper presents a combined experimental and computational study into the aerodynamics and performance of a small scale vertical axis wind turbine. Wind tunnel tests were carried out to ascertain overall performance of the turbine and two and three dimensional unsteady CFD models were generated to help understand the aerodynamics of this performance. Wind tunnel performance results are presented for cases of different wind velocity, tip-speed ratio and solidity as well as rotor blade surface finish. It is shown experimentally that the surface roughness on the turbine rotor blades has a significant effect on performance. Below a critical wind speed the performance of the turbine is degraded and above it, the turbine performance is enhanced by a smooth rotor surface finish. A Significant increase in performance coefficient is observed for the high solidity rotors over most of hte operating range. Dynamic stall behavior and the resulting large and rapid changes in lift coefficient are shown to be the likely cause of changes to rotor pitch angle that occurred during early testing. This small change in pitch angle caused significant decreases in performance.

Wind tunnel experiments of a pair of interacting vertical-axis wind

Author: A Vergaerde, Tim de Troyer, Joanna Kluczewska-Bordier, Nicolas Parneix, Frederic Silvert and MC Runacres

Publication: J. Physics: Conference Series

Year Published: 2018

Vertical-axis wind turbines (VAWTs) have received a renewed interest in the wind energy research community, mainly for off-shore applications. One advantage is that installing a pair of counter rotating VAWTs on the same floating platform would result in thrust reduction and potential cancellation of the mooring yaw moment. In addition, such configurations could benefit from increased power output and reduced wake losses. In this article, we report on wind tunnel experiments to study the mechanical power output of a reference VAWT scale model, tested individually and in a closely-spaced pair of VAWTs. The power output of the individual VAWT configuration is compared with a pair of VAWTs spaced 1.3 diameters apart for two counter rotating directions. A net power increase in the power coefficient for the paired configuration of up to 17.0% compared with two individual rotors has been observed.

Wind Tunnel testing of small Vertical-Axis Wind Turbines in Turbulent Flows

Author: Andreu Carbó Molina, Gianni Bartoli, Tim de Troyer

Publication: Elsevier Ltd.

Year Published: 2017

This study presents an innovative wind tunnel approach to evaluate the efficiency of Vertical-Axis Wind Turbines (VAWT) in turbulent flows, to study their integration in urban environments. The first part of the research is devoted to obtaining highly-turbulent wind profiles in the wind tunnel, with the use of different configurations of square grids. A careful study and validation of this technique is done, in order to obtain uniform wind conditions with adequate values of turbulence intensity and length scales to model the urban flows. The set-up is used to test a H-Darrieus VAWT under values of turbulence over 5%, in comparison with the operation of the turbine under free stream…

Wind Turbine Design: With Emphasis on Darrieus Concept

Author: Ion Paraschivoiu

Publication: Polytechnic International Press

Year Published: 2002

The depletion of global fossil fuel reserves combined with mounting environmental concerns has served to focus attention on the development of ecologically compatible and renewable alternative sources of energy. Wind energy, with its impressive growth rate of 40% over the last five years, is the fastest growing alternate source of energy in the world since its purely economic potential is complemented by its great positive environmental impact. The wind turbine, whether it may be a Horizontal Axis Wind Turbine (HAWT) or a Vertical Axis Wind Turbine (VAWT), offers a practical way to convert the wind energy into electrical or mechanical energy. Although this book focuses on the aerodynamic design and performance of VAWTs based on the Darrieus concept, it also discusses the comparison between HAWTs and VAWTs, future trends in design and the inherent socio-economic and environmental friendly aspects of wind energy as an alternate source of energy.

Wind Turbine Effects on VOR System Performance

Author: C. Morlaas, M. Fares, B. Souny

Publication: IEEE

Year Published: 2009

The implementation of wind farms establishment in France is increasing. When wind farms are located close to radionavigation systems, it becomes important to evaluate their electromagnetic effects on existing radionavigation instalations. In this study, the radionavigation system is a VOR (VHF omnidirectional radio) operating at about 110 MHz. Because rotor blades are made of a balsa and dielectric multilayers composition, their electromagnetic behavior differs from that of metal blades at VHF frequences. In this study, we first obtain an electromagnetic CAD model…

Windfarm Characteristics and Their Effect on Radar Systems

Author: C.A. Jackson

Publication: Intl. Conference on Radar Systems

Year Published: 2007

Prototypes, Vertical Axis Wind Turbines, Wind Harvesters

Generating electricity from renewable energy sources is a major part of the UK Government’s strategy to tackle climate change and to develop business opportunities. It has set ambitious targets of generating 10% of all UK’s energy from renewable sources by 2010 with an aspiration to double this by 2020. Wind energy is expected to be a key contributor to these targets. There are concerns, however, that the construction of wind farms will have a negative effect on both Air Traffic Control (ATC) and Air Defence (AD) radars and many windfarm developments fail due to objections from radar…

Windstar 1066 Prototype

Author: Kevin Wolf

Publication: Wind Harvest International

Year Published: 1994

Prototypes, Vertical Axis Wind Turbines, Wind Harvesters

The Model 1066 was designed to be built in Harbin, China. However, the first prototype was made in Los Angeles with an all-Chinese crew from Harbin.

The turbine consisted of the following features:

Single module, larger than the multi-module Model 530.
Blades 3 times longer than the Model 530 with about twice the cord.
Blade aspect ratio was 10.2.

A single large rotor has fewer blade/blade arm connections and a lower blade arm fairing reference area to blade reference area ratio. A higher overall averaged lift to drag ratio is expected for the 1066, which results in higher energy output.

Windstar 258 Prototype

Author: Kevin Wolf

Publication: Wind Harvest International

Year Published: 1979

Prototypes, Vertical Axis Wind Turbines, Wind Harvesters

Wind Harvest Company’s Windstar 256 was a larger model than its predecessor with two stacked “modules” of blades attached to a central rotor mast. These changes were based on what was learned from the previous “Camarillo Model,” built in 1976. The prototype was mounted on a cement foundation in Sandberg, CA.

Windstar 480-4 Prototype

Author: Kevin Wolf

Publication: Wind Harvest International

Year Published: 1984

Prototypes, Vertical Axis Wind Turbines, Wind Harvesters

Wind Harvest Company’s Windstar 480-4 took the previous iteration, the Windstar 256 model, beefed it up, and increased its size by adding a third module and increased blade length from 8 to 10 feet and thus rotor height from 16 to 30 ft. This model also featured a newly designed drive train/generator/control system and brake.

Windstar 480-5 Prototype

Author: Kevin Wolf

Publication: Wind Harvest International

Year Published: 1984

Prototypes, Vertical Axis Wind Turbines, Wind Harvesters

Windstar 530 Prototype

Author: Kevin Wolf

Publication: Wind Harvest International

Year Published: 1994

North America, Prototypes, Riverside County, San Gorgonio Pass Wind Resource Area, Vertical Axis Wind Turbines, Wind Harvesters

The model 530 was designed for Chinese manufacturing, first starting with a prototype.

Windstar 530G Prototype

Author: Kevin Wolf

Publication: Wind Harvest International

Year Published: 2001

Prototypes, Vertical Axis Wind Turbines, Wind Harvesters

The Windstar 530G was a three turbine array designed to test the coupled vortex effect, a phenomenon first hypothesized by Wind Harvest founder Bob Thomas in the early 1990’s. The array was placed in one of the highly energetic wind farms of San Gorgonio Pass Wind Resource Area in California.

Windstar Camarillo Prototype

Author: Kevin Wolf

Publication: Wind Harvest International

Year Published: 1976

Bob Thomas’ first Vertical Axis Wind Turbine (VAWT) was a proof of concept model built in 1976. He built it with modest funds and observed it operating in low winds.

The test turbine was mounted on a small trailer and pulled out of a hangar at the Camarillo Airport to see how it responded to the light breezes. We had a small handheld anemometer to measure wind speed. The rotor quickly responded to the light breezes starting in wind sof 5 mph or less. It easily self-started, which was encouraging.

WWEA Half-Year Report: Worldwind Wind Capacity Reached 456 GW

Publication: World Wind Energy Association

Year Published: 2016

Country-by-Country Resources, Horizontal Axis Wind Turbines, North America, Vertical Axis Wind Turbines, Wind Farms, Wyoming

“Worldwide wind capacity reached 456 GWs” and would likely grow at 8-10% in 2016, a slower pace than had been achieve in recent years. A growth of 50,000 MWs per year would be slow, and in 13 years, would result in the 1M+ MWs of installed world wide.

Wyoming Mid-Level Wind Resources in Wind Farms

Summary of onshore wind farms
Existing GWs of HAWT wind farms in state	3.1
GWs of HAWTs over 6.5m/s at 20m agl (projected)	2.8
% of wind farms over 6.5m/s at 20m agl	93%

HAWT: Horizontal Axis Wind Turbine

This data came from thewindpower.net and UL’s Windnavigator.

Publication: Wind Harvest International

Wind Farm Summary & Details