Wind Energy

An Investigation into Ridge-Top Turbulence Characteristics During Neutral and Weakly Stable Conditions: Velocity Spectra and Isotropy

by Marwan Katurji

Co-authored with Andrew Sturman and Peyman Zawar-Reza

An investigation into high Reynolds number turbulent flow over a ridge top in New Zealand is described based on... more An investigation into high Reynolds number turbulent flow over a ridge top in New Zealand is described based on high-resolution in-situ measurements, using ultrasonic anemometers for two separate locations on the same ridge with differing upwind terrain complexity. Twelve 5-h periods during neutrally stratified and weakly stable atmospheric conditions with strong wind speeds were sampled at 20 Hz. Large (and small) turbulent length scales were recorded for both vertical and longitudinal velocity components in the range of 7–23 m (0.7–3.3 m) for the vertical direction and 628–1111 m (10.5–14.5 m) for the longitudinal direction. Large-scale eddy sizes scaled to the WRF (Weather Research and Forecasting) numerical model simulated boundary-layer thickness for both sites, while small-scale turbulent features were a function of the complexity of the upwind terrain. Evidence of a multi-scale turbulent structure was obtained at the more complex terrain site, while an assessment of the three-dimensional isotropy assumption in the inertial subrange of the spectrum showed anisotropic turbulence at the less complex site and evidence of isotropic turbulence at the more complex site, with a spectral ratio convergence deviating from the 4/3 or unity values suggested by previous theory and practice. Existing neutral spectral models can represent locations along the ridge top with simple upwind complexity, especially for the vertical wind spectra, but sites with more orographic complexity and strong vertical wind speeds are often poorly represented using these models. Measured spectra for the two sites exhibited no significant diurnal variation and very similar large-scale and small-scale turbulent length scales for each site, but the turbulence energy measured by the variances revealed a strong diurnal difference.
Keywords: Isotropy – Mountain ridge top – Turbulence – Velocity spectra

Discussion of wind farm development in the South-west of Wales.

by Philip Southwood

Wind is one of the most cleanest and most environmentally friendly energy sources and unlike fossil fuels, the wind... more Wind is one of the most cleanest and most environmentally friendly energy sources and unlike fossil fuels, the wind will never be depleted (Bilgili, et al., 2011). For this reason it is important to be able to find the most feasible areas in the UK to build wind farms.

Visual preferences for wind turbines: Location, numbers and respondent characteristics

by Elizabeth Brabec

A high order Discontinuous Galerkin - Fourier incompressible 3D Navier-Stokes solver with rotating sliding meshes

by Esteban Ferrer

Journal of Computational Physics

Received 28 July 2011. Revised 23 April 2012. Accepted 27 April 2012. Available online 9 May 2012.

We present the development of a sliding mesh capability for an unsteady high order (order>3) h/p Discontinuous... more We present the development of a sliding mesh capability for an unsteady high order (order>3) h/p Discontinuous Galerkin solver for the three-dimensional incompressible Navier-Stokes equations. A high order sliding mesh method is developed and implemented for flow simulation with relative rotational motion of an inner mesh with respect to an outer static mesh, through the use of curved boundary elements and mixed triangular-quadrilateral meshes.

A second order stiffly stable method is used to discretise in time the Arbitrary Lagrangian-Eulerian form of the incompressible Navier-Stokes equations. Spatial discretisation is provided by the Symmetric Interior Penalty Galerkin formulation with modal basis functions in the it x-y plane, allowing hanging nodes and sliding meshes without the requirement to use mortar type techniques. Spatial discretisation in the z-direction is provided by a purely spectral method that uses Fourier series and allows computation of spanwise periodic three-dimensional flows. The developed solver is shown to provide high order solutions, second order in time convergence rates and spectral convergence when solving the incompressible Navier-Stokes equations on meshes where fixed and rotating elements coexist.

In addition, an exact implementation of the no-slip boundary condition is included for curved edges; circular arcs and NACA 4-digit airfoils, where analytic expressions for the geometry are used to compute the required metrics.

The solver capabilities are tested for a number of two dimensional problems governed by the incompressible Navier-Stokes equations on static and rotating meshes: the Taylor vortex problem, a static and rotating symmetric NACA0015 airfoil and flows through three bladed cross-flow turbines. In addition, three dimensional flow solutions are demonstrated for a three bladed cross-flow turbine and a circular cylinder shadowed by a pitching NACA0012 airfoil.

Rüzgar Enerjisinde Yenilikçi Bir Teknoloji Kambur Balinalar

by mehmet cem ates

Enerji arz ve talebinde her geçen gün artan dengesizlik bir yana dünyanın son yirmi yılda hem siyasal hem de ekonomik olarak geldiği nokta alternatif enerji kaynaklarına olan ihtiyacı zorunlu kılıyor. Yenilenebilir enerji kaynaklarından olan rüzgar enerjisi uzun süredir üzerinde kafa yorulan seçeneklerden olmasına rağmen istenilen patlamayı bir türlü gerçekleştiremedi. Bunun en önemli nedenleri rüzgar enerjisinin kesin olarak getirisi tahmin edilebilen bir enerji kaynağı olmaması, deviniminin diğer yatırımlara göre daha uzun sürede olması, donanım, bilgi ve teknoloji eksikliği sayılabilir.  Rüzgar santrali kurulması önerilen yerlerde dahi uzun süre rüzgarın istenilen miktarda ve sürede esmediği sık rastlanılan bir durum. Bu yüzden zaten oldukça ciddi sermaye gerektiren rüzgar santralleri bu tarz çekinceler nedeniyle özel sektör tarafından yeterince kuvvetli desteklenmiyor. Fakat doğa bu çekincelerin kaldırılması için bize önemli bir ipucu veriyor. Kambur balinaların yüzgeçlerinden ilham alan araştırmacılar hem verimliliği maksimize eden hem de rüzgarın yavaş estiği zamanlar da bile ciddi enerji üretebilen kanat üzerinde önemli mesafe kaydettiler. Bu yeni teknolojinin orta vadede rüzgar enerjisinin enerji yatırımlardan hak ettiği payı almasında önemli katkı sağlayabileceği düşünülüyor.

What is Influencing Renewable Energy Infrastructure Deployment? A Multi-State Study of U.S. Wind Generation Deployment Efforts

by Larry Helwig

Recent research has determined what influences the adoption of state renewable energy policy instruments. At present,... more Recent research has determined what influences the adoption of state renewable energy policy instruments. At present, nearly all of the U.S. states have deployed or have begun to deploy infrastructure that derives energy from renewable resources. This multiple U.S. State study represents an effort to determine the factors that are influencing wind renewable energy infrastructure deployment efforts in thirty-eight U.S. states that have widely varying wind power potential capacities, different capacities of wind generation infrastructure deployed and varying Renewable Portfolio Standard (RPS) policy goals. This study utilizes the internal determinants and regional diffusion theoretical models of government policy innovation to determine the ability of each model to explain variation in state renewable infrastructure deployment efforts. The fraction of each state’s total deployed wind energy capacity as a function of its total wind potential capacity was used as the dependent variable and state economic factors, geographic and electric system factors and political and ideological factors were used as independent variables representing internal determinants. The effect of regional diffusion was determined by examining the potential wind capacities and actual deployment levels of wind infrastructure in each state’s neighbor states. Preliminary results indicate that the internal determinants model was a better predictor of current state renewable energy deployment efforts than the regional diffusion model. In particular, the density of high-voltage transmission lines (circuit miles/square mile) was a very strong predictor of state deployment success. If this is the case, it may be necessary for states who wish increase their levels of renewable wind energy capacity to place a greater focus on the amount of available transmission infrastructure and factor this into the design of their RPS policy instruments.

Small-Scale Wind Power Generation

by Jamie Bull

The impact of climate change on generation and transmission in the Australian National Electricity Market

by William Paul Bell

Working paper

Ethnographies of wind and power (with Dorle Dracklé)

by Werner Krauss

Anthropology News 52, 2011 (5), p.9

The 'Dingpolitik' of Wind Energy in Northern German Landscapes: An Ethnographic Case Study.

by Werner Krauss

In: Landscape Research (special edition: Emerging Energy Landscapes) 2010, Vol. 35 /2, 195-208

Abstract

Germany has assumed a leading position in the global wind energy market, with its coastal... more Abstract

Germany has assumed a leading position in the global wind energy market, with its coastal districts of North Frisia and Dithmarschen as two outstanding locations. These coastal landscapes are the outcome of interaction between human and non-human forces throughout the centuries, and they are characterized by the wind, the tides and the sea as well as the building of dikes, technological innovations and the interplay of regional, national and trans-national forces. Against this background, the short but complex transition from a mainly agricultural landscape into a wind energy landscape is interpreted here following Latour's (2005b) concept of a Dingpolitik (politics of things) and complementary assumptions suggested by the European Landscape Convention. I will argue that the rise of wind energy in Northern Germany is not only the result of top-down governance strategies, but of a collective effort based on the dynamics of the collective of people and things that make up these landscapes. Based on ethnographic examples, this article analyses the emergence of wind energy landscapes in Northern Germany from the first implementation of wind turbines to civic wind parks as a form of social practice.

El Pasaje y la Transición Energética: Comparando el Surgimiento de Paisajes de energía eólica en Francia, Alemania y Portugal.

by Werner Krauss

with Nadai, Alain; Afonso, Ana Isabel; Dracklé, Dorle; Hinkelbein, Oliver; Labussière, Olivier and Carlos Mendes. )In: Nimbus: Revista de Climatología, Meteorología y Paisaje, 2010, Vol 25-26, 155-174

Wind Turbine Power Curves

by Iain Staffell

This working paper collates data on the power curves for 16 recent and forthcoming models of wind turbine from four... more This working paper collates data on the power curves for 16 recent and forthcoming models of wind turbine from four major manufacturers: Siemens, Vestas, REpower and Nordex.

The potential of hydrogen and electricity production from wind power

by Robert Paynter

Robert JH Paynter, Norman H Lipman, James E Foster
Report of the Energy Research Unit, Rutherford Appleton Laboratory
1991

This report summarises current hydrogen production and usage, the market and the technologies. An integration study is... more This report summarises current hydrogen production and usage, the market and the technologies. An integration study is then reported including hydrogen as a product from the otherwise rejected wind energy.:

Windpower contribution to sustainable development in Brazil

by Moana Simas

Article presented in the World Renewable Energy Congress, in Linköping, Sweden, March 2011

Global electricity consumption rose exponentially over the last decades powered by fossil fueled thermal power plants.... more Global electricity consumption rose exponentially over the last decades powered by fossil fueled thermal power plants. In comparison, Brazil relies on large hydroelectric plants to generate most of its electricity. Nevertheless, the share of thermal electricity generation in Brazil has increased because thermal power can balance the seasonality of the hydroelectric based system and is cost competitive. Regardless its great wind potential, the use of this technology in Brazil is still timid. The country had only 835 MW of installed windpower capacity until November 2010, or 0.75% of its total. An aggressive wind power deployment has been constrained by its cost until recently. However, windpower has potential to act as a complementary energy source to hydropower during dry seasons, and its development could displace thermal power plants. This paper aims to quantify potential greenhouse gas (GHG) emission reductions and jobs creation in three different scenarios of wind energy development up to 2019. In the baseline scenario, windpower will create over 93,000 jobs and reduce up to 96 million tones of CO2 by 2019. In comparison, a massive windpower deployment scenario, , foresees the reduction of up to 176 million tones of CO2 and the generation of more than 225,000 jobs, most of them in the manufacturing sector. Therefore, wind power is an important alternative for promoting sustainable development in Brazil because it reduces GHG emissions and creates green jobs.

A energia eólica e o desenvolvimento sustentável no Brasil

by Moana Simas

Published in the electronic press of the International Relations department of Faculdade Santa Marcelina. Available at: http://www.fasm.edu.br/interrelacoes/33/005.html

WIND PUMPS – KEY TO WATER PROBLEMS IN UASIN GISH DISTRICT, KENYA

by moses marani

Change in climatic pattern has led to widespread drought causing famine and lack of clean drinking water. Uasin Gishu... more Change in climatic pattern has led to widespread drought causing famine and lack of clean drinking water. Uasin Gishu district despite its shallow water body suffers water adverse shortages which can be solved by proper analysis of wind power and ground water levels. This project deals with forecasting of available wind and evaluation of uncertainties of the forecast in order to establish a confidence interval. Statistical methods (windographer) alongside Weibul functions were used not only to predict power output but also an upper and lower limit for the accuracy for each time stamp. Mean wind speeds and general wind characteristics were used to define wind turbine parameters and general design. Both environmental and techno-economic analysis of the wind pumps have been covered to justify that wind pumping units can be used to efficiently harness water for the region.

Near-wake flow structure downwind of a wind turbine in a turbulent boundary layer

by Corey Markfort

Zhang, W., C.D. Markfort, and F. Porté‐Agel

Wind turbines operate in the surface layer of the atmospheric boundary layer, where they are subjected to strong wind... more Wind turbines operate in the surface layer of the atmospheric boundary layer, where they are subjected to strong wind shear and relatively high turbulence levels. These incoming boundary layer flow characteristics are expected to affect the structure of wind turbine wakes. The near-wake region is characterized by a complex coupled vortex system (including helicoidal tip vortices), unsteadiness and strong turbulence heterogeneity. Limited information about the spatial distribution of turbulence in the near wake, the vortex behavior and their influence on the downwind development of the far wake hinders our capability to predict wind turbine power production and fatigue loads in wind farms. This calls for a better understanding of the spatial distribution of the 3D flow and coherent turbulence structures in the near wake. Systematic wind-tunnel experiments were designed and carried out to characterize the structure of the near-wake flow downwind of a model wind turbine placed in a neutral boundary layer flow. A horizontal-axis, three-blade wind turbine model, with a rotor diameter of 13 cm and the hub height at 10.5 cm, occupied the lowest one-third of the boundary layer. High-resolution particle image velocimetry (PIV) was used to measure velocities in multiple vertical stream-wise planes (x–z) and vertical span-wise planes (y–z). In particular, we identified localized regions of strong vorticity and swirling strength, which are the signature of helicoidal tip vortices. These vortices are most pronounced at the top-tip level and persist up to a distance of two to three rotor diameters downwind. The measurements also reveal strong flow rotation and a highly non-axisymmetric distribution of the mean flow and turbulence structure in the near wake. The results provide new insight into the physical mechanisms that govern the development of the near wake of a wind turbine immersed in a neutral boundary layer. They also serve as important data for the development and validation of numerical models.

Wind Power Development in Kazakhstan Potential and Obstacles

by Almaz Akhmetov

Co-authored with Yohji Uchiyama and Keiichi Okajima.

Oil, gas, coal and uranium reserves of Kazakhstan are among the biggest in the world. Therefore, energy production is... more Oil, gas, coal and uranium reserves of Kazakhstan are among the biggest in the world. Therefore, energy production is based on relatively cheap fossil fuels. However, it is little known about enormous renewable energy potential of Kazakhstan. In particular, as for wind power, nine sites are recognized by UNDP within Wind Power market development initiative as perspective. The average annual wind speed of all sites at a height of 80 meters is around 7.5 m/s and the estimated output can satisfy 2% of electricity demand of Kazakhstan by 2014. In this paper wind energy potential is assessed and power outputs for all locations are estimated using technical data of Vestas90-3MW turbine. Then, the obstacles preventing introduction of wind farms in Kazakhstan are discussed: a) problems related to the structure of energy sector; b) legislative issues and c) possible organizational and operational risks specific to each location. The paper describes existing barriers and suggests the possible changes to be made in order to introduce wind power in Kazakhstan.

Multi-criteria decision analysis for assessment of wind power in Kazakhstan

by Almaz Akhmetov

Co-authored with Yohji Uchiyama and Keiichi Okajima.

Kazakhstan is endowed with exceptional wind resources, which are sufficient for the introduction of industrial scale... more Kazakhstan is endowed with exceptional wind resources, which are sufficient for the introduction of industrial scale wind farms and development of the wind power in the country. The wind power development is of particular importance for Kazakhstan’s sustainable development. However, effective introduction of the wind energy projects requires multi-dimensional decision-making process. In this paper multi-criteria assessment of nine sites with high wind potential is performed. All alternatives have location specific criteria such as technical (including icing and earthquake risks), socioeconomic and environmental constraint. Since no previous studies have been performed by MCDA (Multi-Criteria Decision Analysis) of energy alternatives in Kazakhstan, entropy information method is used for weighting to neglect subjectivity in the process of decision making. The results of the study could be used to structure the decision process and provide a conceptual framework for analysts and decision makers.

Modelling of wind-induced currents in water bodies

by Roger Falconer - Cardiff University

Paper 81:  Kocyigit, M. and Falconer, R. A. 2004. Modelling of wind-induced currents in water bodies. Proceedings of the Institution of Civil Engineers, Water Management. 157(WM4), 197-210.

Abstract
This paper presents a numerical modelling study into wind-induced currents in shallow water basins. A... more Abstract
This paper presents a numerical modelling study into wind-induced currents in shallow water basins. A three-dimensional semi-implicit finite difference numerical model is described, incorporating non-hydrostatic pressure, based on sigma-transformed system in the vertical direction. The numerical model is first validated for sloshing in a rectangular tank, excellent agreement obtained against analytical solutions, provided the non-hydrostatic pressure is incorporated. The model is further verified against experimental data on wind-induced circulation in shallow rectangular tanks. It is then used to simulate wind-induced three-dimensional flow fields in idealised rectangular tanks. A parameter study is carried out for wind-induced flows in Esthwaite Water, and the predictions compared against field data. It is shown that the numerical model is capable of accurately simulating the wind-induced circulation in shallow enclosed water bodies and that the topography and wind stress are of primary importance. The non-hydrostatic pressure does not have a significant effect on the wind-induced flow fields considered herein.