Science.gov

Sample records for international wind farm

  1. International wind farm markets: An overview

    SciTech Connect

    Rackstraw, K.

    1996-12-31

    More wind energy capacity was installed in 1995 than in any previous year. Two markets, Germany and India, accounted for nearly two-thirds of those installations, while the largest single market in the world historically, the US, ground nearly to a halt. Market supports in Germany and India, however, are vulnerable to political forces largely beyond the control of the wind industry. This paper examines the growth of international wind farm markets worldwide and notes that future markets will be more broadly based, leaving the industry less vulnerable to political changes. The paper also concludes that an additional 18,500 MW could be installed by the year 2005 even without assuming a dire ecological scenario that would create environmental drivers to accelerate wind market growth. 4 figs.

  2. Wind farm electrical system

    DOEpatents

    Erdman, William L.; Lettenmaier, Terry M.

    2006-07-04

    An approach to wind farm design using variable speed wind turbines with low pulse number electrical output. The output of multiple wind turbines are aggregated to create a high pulse number electrical output at a point of common coupling with a utility grid network. Power quality at each individual wind turbine falls short of utility standards, but the aggregated output at the point of common coupling is within acceptable tolerances for utility power quality. The approach for aggregating low pulse number electrical output from multiple wind turbines relies upon a pad mounted transformer at each wind turbine that performs phase multiplication on the output of each wind turbine. Phase multiplication converts a modified square wave from the wind turbine into a 6 pulse output. Phase shifting of the 6 pulse output from each wind turbine allows the aggregated output of multiple wind turbines to be a 24 pulse approximation of a sine wave. Additional filtering and VAR control is embedded within the wind farm to take advantage of the wind farm's electrical impedence characteristics to further enhance power quality at the point of common coupling.

  3. Wind Farm Recommendation Report

    SciTech Connect

    John Reisenauer

    2011-05-01

    On April 21, 2011, an Idaho National Laboratory (INL) Land Use Committee meeting was convened to develop a wind farm recommendation for the Executive Council and a list of proposed actions for proceeding with the recommendation. In terms of land use, the INL Land Use Committee unanimously agrees that Site 6 is the preferred location of the alternatives presented for an INL wind farm. However, further studies and resolution to questions raised (stated in this report) by the INL Land Use Committee are needed for the preferred location. Studies include, but are not limited to, wind viability (6 months), bats (2 years), and the visual impact of the wind farm. In addition, cultural resource surveys and consultation (1 month) and the National Environmental Policy Act process (9 to 12 months) need to be completed. Furthermore, there is no documented evidence of developers expressing interest in constructing a small wind farm on INL, nor a specific list of expectations or concessions for which a developer might expect INL to cover the cost. To date, INL assumes the National Environmental Policy Act activities will be paid for by the Department of Energy and INL (the environmental assessment has only received partial funding). However, other concessions also may be expected by developers such as roads, fencing, power line installation, tie-ins to substations, annual maintenance, snow removal, access control, down-time, and remediation. These types of concessions have not been documented, as a request, from a developer and INL has not identified the short and long-term cost liabilities for such concessions should a developer expect INL to cover these costs. INL has not identified a go-no-go funding level or the priority this Wind Farm Project might have with respect to other nuclear-related projects, should the wind farm remain an unfunded mandate. The Land Use Committee recommends Legal be consulted to determine what, if any, liabilities exist with the Wind Farm Project and

  4. Wake effects between two neighbouring wind farms

    NASA Astrophysics Data System (ADS)

    Gayle Nygaard, Nicolai; Damgaard Hansen, Sidse

    2016-09-01

    We address the issue of wake effects between two neighbouring offshore wind farms by analysing simultaneous production data from Rodsand II and Nysted. The upstream wind farm is found to not just perturb the flow in its wake, but also to cause speed-ups at the positions of some downstream turbines. We use the data to perform a validation of a simple wake model for flow cases corresponding to wind directions of maximum internal and external wake effects.

  5. Wind Farm Feasibility Study

    SciTech Connect

    Richard Curry; Erik Foley; DOE Project Officer - Keith Bennett

    2007-07-11

    Saint Francis University has assessed the Swallow Farm property located in Shade Township, Somerset County, Pennsylvania as a potential wind power development site. Saint Francis worked with McLean Energy Partners to have a 50-meter meteorological tower installed on the property in April 2004 and continues to conduct a meteorological assessment of the site. Results suggest a mean average wind speed at 80 meters of 17 mph with a net capacity factor of 31 - 33%. Approximate electricity generation capacity of the project is 10 megawatts. Also, the University used matching funds provided by the federal government to contract with ABR, Inc. to conduct radar studies of nocturnal migration of birds and bats during the migrations seasons in the Spring and Fall of 2005 with a mean nocturnal flight altitude of 402 meters with less than 5% of targets at altitudes of less than 125 meters. The mean nocturnal passage rate was 166 targets/km/h in the fall and 145 targets/km/h in the spring. Lastly, University faculty and students conducted a nesting bird study May - July 2006. Seventy-three (73) species of birds were observed with 65 determined to be breeding or potentially breeding species; this figure represents approximately 30% of the 214 breeding bird species in Pennsylvania. No officially protected avian species were determined to be nesting at Swallow Farm.

  6. Wind Farms and Weather Modification.

    NASA Astrophysics Data System (ADS)

    Barrie, D. B.; Kirk-Davidoff, D. B.

    2008-12-01

    Electrical generation by wind turbines is increasing rapidly, and has been projected to satisfy 15 percent of world electric demand by 2030. The extensive installation of wind farms would alter surface roughness and significantly impact the atmospheric circulation. This forcing could be changed deliberately by adjusting the attitude of the turbine blades with respect to the wind. Using the NCAR Community Atmosphere Model, we model the impact of time-dependent surface roughness changes due to manipulation of a continent-scale wind farm. We show that initial disturbances caused by a step change in roughness grow within four days such that the flow is altered at synoptic scales. The growth rate of the induced perturbations is largest in regions of high atmospheric instability. For a roughness change imposed over North America, the induced perturbations involve substantial changes in the track and development of cyclones over the North Atlantic. For example, in some cases, weather over the British Isles changes from cloudy to clear, depending on whether wind turbines in the American Midwest are "on" or "off" three days beforehand. We explore the dependence of the downstream effects on the size and roughness of the wind farm installation, showing that as the size of individual wind farms and turbines grows, the scale of atmospheric impacts increases in extent and magnitude. We also look at the dependence of the wind farm impacts on the initial state of the atmosphere, confirming that the impacts are largest when the wind farm perturbation projects onto growing error modes in the atmosphere. In particular, rapid growth occurs when the initial disturbance is carried into regions of high baroclinic instability such as the North Atlantic. By running ensemble experiments, we estimate the robustness of the wind farm impacts with respect to realistic uncertainty in the initial conditions. Our results suggest the possibility of a method for weather modification that in some

  7. Offshore wind farm layout optimization

    NASA Astrophysics Data System (ADS)

    Elkinton, Christopher Neil

    Offshore wind energy technology is maturing in Europe and is poised to make a significant contribution to the U.S. energy production portfolio. Building on the knowledge the wind industry has gained to date, this dissertation investigates the influences of different site conditions on offshore wind farm micrositing---the layout of individual turbines within the boundaries of a wind farm. For offshore wind farms, these conditions include, among others, the wind and wave climates, water depths, and soil conditions at the site. An analysis tool has been developed that is capable of estimating the cost of energy (COE) from offshore wind farms. For this analysis, the COE has been divided into several modeled components: major costs (e.g. turbines, electrical interconnection, maintenance, etc.), energy production, and energy losses. By treating these component models as functions of site-dependent parameters, the analysis tool can investigate the influence of these parameters on the COE. Some parameters result in simultaneous increases of both energy and cost. In these cases, the analysis tool was used to determine the value of the parameter that yielded the lowest COE and, thus, the best balance of cost and energy. The models have been validated and generally compare favorably with existing offshore wind farm data. The analysis technique was then paired with optimization algorithms to form a tool with which to design offshore wind farm layouts for which the COE was minimized. Greedy heuristic and genetic optimization algorithms have been tuned and implemented. The use of these two algorithms in series has been shown to produce the best, most consistent solutions. The influences of site conditions on the COE have been studied further by applying the analysis and optimization tools to the initial design of a small offshore wind farm near the town of Hull, Massachusetts. The results of an initial full-site analysis and optimization were used to constrain the boundaries of

  8. Wind tunnel measurements of a large wind farm model approaching the infinite wind farm regime

    NASA Astrophysics Data System (ADS)

    Bossuyt, Juliaan; Howland, Michael; Meneveau, Charles; Meyers, Johan

    2016-11-01

    A scaled wind farm, with 100 porous disk models of wind turbines, is used to study the effect of wind farm layout on the wind farm power output and its variability, in a wind tunnel study. The wind farm consists of 20 rows and 5 columns. The porous disk models have a diameter of 0 . 03 m and are instrumented with strain gages to measure the thrust force, as a surrogate for wind turbine power output. The frequency response of the measurements goes up to the natural frequency of the models and allows studying the spatio-temporal characteristics of the power output for different layouts. A variety of layouts are considered by shifting the individual rows in the spanwise direction. The reference layout has a regular streamwise spacing of Sx / D = 7 and a spanwise spacing of Sy / D = 5 . The parameter space is further expanded by considering layouts with an uneven streamwise spacing: Sx / D = 3 . 5 & 10 . 5 and Sx / D = 1 . 5 & 12 . 5 . We study how the mean row power changes as a function of wind farm layout and investigate the appearance of an asymptotic limiting behavior as previously described in the literature by application of the top-down model for the spatially averaged wind farm - boundary layer interaction. Work supported by ERC (Grant No. 306471, the ActiveWindFarms project) and by NSF (OISE-1243482, the WINDINSPIRE project).

  9. Wind Farm Power System Model Development: Preprint

    SciTech Connect

    Muljadi, E.; Butterfield, C. P.

    2004-07-01

    In some areas, wind power has reached a level where it begins to impact grid operation and the stability of local utilities. In this paper, the model development for a large wind farm will be presented. Wind farm dynamic behavior and contribution to stability during transmission system faults will be examined.

  10. Flow Structure and Turbulence in Wind Farms

    NASA Astrophysics Data System (ADS)

    Stevens, Richard J. A. M.; Meneveau, Charles

    2017-01-01

    Similar to other renewable energy sources, wind energy is characterized by a low power density. Hence, for wind energy to make considerable contributions to the world's overall energy supply, large wind farms (on- and offshore) consisting of arrays of ever larger wind turbines are being envisioned and built. From a fluid mechanics perspective, wind farms encompass turbulent flow phenomena occurring at many spatial and temporal scales. Of particular interest to understanding mean power extraction and fluctuations in wind farms are the scales ranging from 1 to 10 m that comprise the wakes behind individual wind turbines, to motions reaching 100 m to kilometers in scale, inherently associated with the atmospheric boundary layer. In this review, we summarize current understanding of these flow phenomena (particularly mean and second-order statistics) through field studies, wind tunnel experiments, large-eddy simulations, and analytical modeling, emphasizing the most relevant features for wind farm design and operation.

  11. INL Wind Farm Project Description Document

    SciTech Connect

    Gary Siefert

    2009-07-01

    The INL Wind Farm project proposes to install a 20 MW to 40 MW wind farm on government property, consisting of approximately ten to twenty full-sized (80-meter hub height) towers with 2 MW turbines, and access roads. This includes identifying the optimal turbine locations, building access roads, and pouring the tower foundations in preparation for turbine installation. The project successfully identified a location on INL lands with commercially viable wind resources (i.e., greater than 11 mph sustained winds) for a 20 to 40 MW wind farm. Additionally, the proposed Wind Farm was evaluated against other General Plant Projects, General Purpose Capital Equipment projects, and Line Item Construction Projects at the INL to show the relative importance of the proposed Wind Farm project.

  12. Wind farms production: Control and prediction

    NASA Astrophysics Data System (ADS)

    El-Fouly, Tarek Hussein Mostafa

    Wind energy resources, unlike dispatchable central station generation, produce power dependable on external irregular source and that is the incident wind speed which does not always blow when electricity is needed. This results in the variability, unpredictability, and uncertainty of wind resources. Therefore, the integration of wind facilities to utility electrical grid presents a major challenge to power system operator. Such integration has significant impact on the optimum power flow, transmission congestion, power quality issues, system stability, load dispatch, and economic analysis. Due to the irregular nature of wind power production, accurate prediction represents the major challenge to power system operators. Therefore, in this thesis two novel models are proposed for wind speed and wind power prediction. One proposed model is dedicated to short-term prediction (one-hour ahead) and the other involves medium term prediction (one-day ahead). The accuracy of the proposed models is revealed by comparing their results with the corresponding values of a reference prediction model referred to as the persistent model. Utility grid operation is not only impacted by the uncertainty of the future production of wind farms, but also by the variability of their current production and how the active and reactive power exchange with the grid is controlled. To address this particular task, a control technique for wind turbines, driven by doubly-fed induction generators (DFIGs), is developed to regulate the terminal voltage by equally sharing the generated/absorbed reactive power between the rotor-side and the gridside converters. To highlight the impact of the new developed technique in reducing the power loss in the generator set, an economic analysis is carried out. Moreover, a new aggregated model for wind farms is proposed that accounts for the irregularity of the incident wind distribution throughout the farm layout. Specifically, this model includes the wake effect

  13. Potential market of wind farm in China

    SciTech Connect

    Pengfei Shi

    1996-12-31

    Wind energy resources are abundant in China, in southeast coast area along with the rapid economic growth, electricity demand has been sharply increased, due to complex terrain detailed assessments are in urgent need. Advanced methodology and computer model should be developed. In this paper the existing wind farms, installed capacity, manufacturers share and projects in the near future are presented. For further development of wind farm in large scale, different ways of local manufacturing wind turbine generators (WTG) are going on. Current policy and barriers are analyzed. 4 refs., 2 figs., 4 tabs.

  14. Investigation of Wind Turbine Rotor Concepts for Offshore Wind Farms

    NASA Astrophysics Data System (ADS)

    Ceyhan, Özlem; Grasso, Francesco

    2014-06-01

    Current plans in offshore wind energy developments call for further reduction of cost of energy. In order to contribute to this goal, several wind turbine rotor concepts have been investigated. Assuming the future offshore wind turbines will operate only in the offshore wind farms, the rotor concepts are not only evaluated for their stand-alone performances and their potential in reducing the loads, but also for their performance in an offshore wind farm. In order to do that, the 10MW reference wind turbine designed in Innwind.EU project is chosen as baseline. Several rotor parameters have been modified and their influences are investigated for offshore wind turbine design purposes. This investigation is carried out as a conceptual parametrical study. All concepts are evaluated numerically with BOT (Blade optimisation tool) software in wind turbine level and with Farmflow software in wind farm level for two wind farm layouts. At the end, all these concepts are compared with each other in terms of their advantages and disadvantages.

  15. Wake Measurements in ECN's Scaled Wind Farm

    NASA Astrophysics Data System (ADS)

    Wagenaar, J. W.; Schepers, J. G.

    2014-12-01

    In ECN's scaled wind farm the wake evolution is studied in two different situations. A single wake is studied at two different locations downstream of a turbine and a single wake is studied in conjunction with a triple wake. Here, the wake is characterized by the relative wind speed, the turbulence intensity, the vertical wind speed and the turbulence (an)isotropy. Per situation all wake measurements are taken simultaneously together with the inflow conditions.

  16. IEA-Task 31 WAKEBENCH: Towards a protocol for wind farm flow model evaluation. Part 2: Wind farm wake models

    NASA Astrophysics Data System (ADS)

    Moriarty, Patrick; Sanz Rodrigo, Javier; Gancarski, Pawel; Chuchfield, Matthew; Naughton, Jonathan W.; Hansen, Kurt S.; Machefaux, Ewan; Maguire, Eoghan; Castellani, Francesco; Terzi, Ludovico; Breton, Simon-Philippe; Ueda, Yuko

    2014-06-01

    Researchers within the International Energy Agency (IEA) Task 31: Wakebench have created a framework for the evaluation of wind farm flow models operating at the microscale level. The framework consists of a model evaluation protocol integrated with a web-based portal for model benchmarking (www.windbench.net). This paper provides an overview of the building-block validation approach applied to wind farm wake models, including best practices for the benchmarking and data processing procedures for validation datasets from wind farm SCADA and meteorological databases. A hierarchy of test cases has been proposed for wake model evaluation, from similarity theory of the axisymmetric wake and idealized infinite wind farm, to single-wake wind tunnel (UMN-EPFL) and field experiments (Sexbierum), to wind farm arrays in offshore (Horns Rev, Lillgrund) and complex terrain conditions (San Gregorio). A summary of results from the axisymmetric wake, Sexbierum, Horns Rev and Lillgrund benchmarks are used to discuss the state-of-the-art of wake model validation and highlight the most relevant issues for future development.

  17. Wind farm optimization using evolutionary algorithms

    NASA Astrophysics Data System (ADS)

    Ituarte-Villarreal, Carlos M.

    In recent years, the wind power industry has focused its efforts on solving the Wind Farm Layout Optimization (WFLO) problem. Wind resource assessment is a pivotal step in optimizing the wind-farm design and siting and, in determining whether a project is economically feasible or not. In the present work, three (3) different optimization methods are proposed for the solution of the WFLO: (i) A modified Viral System Algorithm applied to the optimization of the proper location of the components in a wind-farm to maximize the energy output given a stated wind environment of the site. The optimization problem is formulated as the minimization of energy cost per unit produced and applies a penalization for the lack of system reliability. The viral system algorithm utilized in this research solves three (3) well-known problems in the wind-energy literature; (ii) a new multiple objective evolutionary algorithm to obtain optimal placement of wind turbines while considering the power output, cost, and reliability of the system. The algorithm presented is based on evolutionary computation and the objective functions considered are the maximization of power output, the minimization of wind farm cost and the maximization of system reliability. The final solution to this multiple objective problem is presented as a set of Pareto solutions and, (iii) A hybrid viral-based optimization algorithm adapted to find the proper component configuration for a wind farm with the introduction of the universal generating function (UGF) analytical approach to discretize the different operating or mechanical levels of the wind turbines in addition to the various wind speed states. The proposed methodology considers the specific probability functions of the wind resource to describe their proper behaviors to account for the stochastic comportment of the renewable energy components, aiming to increase their power output and the reliability of these systems. The developed heuristic considers a

  18. Volumetric characterization of the flow over miniature wind farms: An experimental study

    NASA Astrophysics Data System (ADS)

    Wing, Lai; Troolin, Dan; Hyun, Jin Kim; Tobin, Nicolas; Zuniga Zamalloa, Carlo; Chamorro, Leonardo P.

    2014-11-01

    An internal boundary layer is known to develop from the interaction between wind farms and the atmospheric boundary layer. It possesses characteristic features able to modulate the turbulence dynamics over large regions and eventually modify the micro climate in the vicinity of the wind farm. In this study, we examine the structure of the turbulence above various miniature wind farm configurations using 3D Particle Image velocimetry (PIV). Each miniature wind farm is placed in the boundary-layer wind tunnel at the Mechanical Science Engineering, UIUC. The turbines are fabricated using 3D printing and have a loading system that controls their tip-speed ratio and allows for characterizing the loads. Volumetric PIV is performed at various locations over and downstream a series of wind farm layouts. High-order turbulence statistics, turbulence structure and characteristic coherent motions are obtained and discussed in terms of the wind farm layout.

  19. IEA Wind Task 26: Offshore Wind Farm Baseline Documentation

    SciTech Connect

    Smart, Gavin; Smith, Aaron; Warner, Ethan; Sperstad, Iver Bakken; Prinsen, Bob; Lacal-Arantegui, Roberto

    2016-06-02

    This document has been produced to provide the definition and rationale for the Baseline Offshore Wind Farm established within IEA Wind Task 26--Cost of Wind Energy. The Baseline has been developed to provide a common starting point for country comparisons and sensitivity analysis on key offshore wind cost and value drivers. The baseline project reflects an approximate average of the characteristics of projects installed between 2012 and 2014, with the project life assumed to be 20 years. The baseline wind farm is located 40 kilometres (km) from construction and operations and maintenance (O&M) ports and from export cable landfall. The wind farm consists of 100 4-megawatt (MW) wind turbines mounted on monopile foundations in an average water depth of 25 metres (m), connected by 33-kilovolt (kV) inter-array cables. The arrays are connected to a single offshore substation (33kV/220kV) mounted on a jacket foundation, with the substation connected via a single 220kV export cable to an onshore substation, 10km from landfall. The wind farm employs a port-based O&M strategy using crew-transfer vessels.

  20. Wind farm array wake losses

    SciTech Connect

    Baker, R.W.; McCarthy, E.F.

    1997-12-31

    A wind turbine wake study was conducted in the summer of 1987 at an Altamont Pass wind electric generating facility. The wind speed deficits, turbulence, and power deficits from an array consisting of several rows of wind turbines is discussed. A total of nine different test configurations were evaluated for a downwind spacing ranging from 7 rotor diameters (RD) to 34 RD and a cross wind spacing of 1.3 RD and 2.7 RD. Wake power deficits of 15% were measured at 16 RD and power losses of a few percent were even measurable at 27 RD for the closer cross wind spacing. For several rows of turbines separated by 7-9 RD the wake zones overlapped and formed compound wakes with higher velocity deficits. The wind speed and direction turbulence in the wake was much higher than the ambient turbulence. The results from this study are compared to the findings from other similar field measurements.

  1. Numerical investigation of wind turbine and wind farm aerodynamics

    NASA Astrophysics Data System (ADS)

    Selvaraj, Suganthi

    A numerical method based on the solution of Reynolds Averaged Navier Stokes equations and actuator disk representation of turbine rotor is developed and implemented in the OpenFOAM software suite for aerodynamic analysis of horizontal axis wind turbines (HAWT). The method and the implementation are validated against the 1-D momentum theory, the blade element momentum theory and against experimental data. The model is used for analyzing aerodynamics of a novel dual rotor wind turbine concept and wind farms. Horizontal axis wind turbines suffer from aerodynamic inefficiencies in the blade root region (near the hub) due to several non-aerodynamic constraints (e.g., manufacturing, transportation, cost, etc.). A new dual-rotor wind turbine (DRWT) concept is proposed that aims at mitigating these losses. A DRWT is designed using an existing turbine rotor for the main rotor (Risoe turbine and NREL 5 MW turbine), while the secondary rotor is designed using a high lift to drag ratio airfoil (the DU 96 airfoil from TU Delft). The numerical aerodynamic analysis method developed as a part of this thesis is used to optimize the design. The new DRWT design gives an improvement of about 7% in aerodynamic efficiency over the single rotor turbine. Wind turbines are typically deployed in clusters called wind farms. HAWTs also suffer from aerodynamic losses in a wind farm due to interactions with wind turbine wakes. An interesting mesoscale meteorological phenomenon called "surface flow convergence" believed to be caused by wind turbine arrays is investigated using the numerical method developed here. This phenomenon is believed to be caused by the pressure gradient set up by wind turbines operating in close proximity in a farm. A conceptual/hypothetical wind farm simulation validates the hypothesis that a pressure gradient is setup in wind farms due to turbines and that it can cause flow veering of the order of 10 degrees. Simulations of a real wind farm (Story County) are also

  2. Stability analysis of offshore wind farm and marine current farm

    NASA Astrophysics Data System (ADS)

    Shawon, Mohammad Hasanuzzaman

    Renewable energy has been playing an important role to meet power demand and 'Green Energy' market is getting bigger platform all over the world in the last few years. Due to massive increase in the prices of fossil fuels along with global warming issues, energy harvesting from renewable energy sources has received considerable interest, nowadays, where extensive researches are going on to ensure optimum use of renewable sources. In order to meet the increasing demand of electricity and power, integration of renewable energy is getting highest priorities around the world. Wind is one of the most top growing renewable energy resources and wind power market penetration is expected to reach 3.35 percent by 2013 from its present market of about 240 GW. A wind energy system is the most environmental friendly, cost effective and safe among all renewable energy resources available. Another promising form of renewable energy is ocean energy which covers 70 % of the earth. Ocean energy can be tapped from waves, tides and thermal elements. Offshore Wind farm (OWF) has already become very popular for large scale wind power integration with the onshore grid. Recently, marine current farm (MCF) is also showing good potential to become mainstream energy sources and already successfully commissioned in United Kingdom. However, squirrel cage induction generator (SCIG) has the stability problem similar to synchronous generator especially during fault location to restore the electromagnetic torque. Series dynamic braking resistor (SDBR) has been known as a useful mean to stabilize fixed speed wind generator system. On the other hand, doubly fed induction generator (DFIG) has the capability of coupling the control of active and reactive power and to provide necessary reactive power demand during grid fault conditions. Series dynamic braking resistor (SDBR) can also be employed with DFIG to limit the rotor over current. An integration of wind and tidal energy represents a new

  3. Wind farms model aggregation using probabilistic clustering

    NASA Astrophysics Data System (ADS)

    Fernandes, Paula Odete; Ferreira, Ángela Paula

    2013-10-01

    The main objective of this research is the identification of homogeneous groups within wind farms of a major operator playing in the energy sector in Portugal, based on two multivariate analyses: Hierarchical Cluster Analysis and Discriminant Analysis, by using two independent variables: annual liquid hours and net production. From the produced outputs there were identified three homogenous groups of wind farms: (1) medium Installed Capacity and Induction Generator based Technology, (2) high Installed Capacity and Synchronous Generator based Technology and (3) medium Installed Capacity and Synchronous Generator based Technology, which includes the wind farms with the higher annual liquid hours. It has been found that the results obtained by cluster analysis are well classified, with a total percentage of correct classification of 97,1%, which can be considered excellent.

  4. Effect of Large Finite-Size Wind Farms and Their Wakes on Atmospheric Boundary Layer Dynamics

    NASA Astrophysics Data System (ADS)

    Wu, Ka Ling; Porté-Agel, Fernando

    2016-04-01

    Through the use of large-eddy simulation, the effect of large finite-size wind farms and their wakes on conventionally-neutral atmospheric boundary layer (ABL) dynamics and power extraction is investigated. Specifically, this study focuses on a wind farm that comprises 25 rows of wind turbines, spanning a distance of 10 km. It is shown that large wind farms have a significant effect on internal boundary layer growth both inside and downwind of the wind farms. If the wind farm is large enough, the internal boundary layer interacts with the thermally-stratified free atmosphere above, leading to a modification of the ABL height and power extraction. In addition, it is shown that large wind farms create extensive wakes, which could have an effect on potential downwind wind farms. Specifically, for the case considered here, a power deficit as large as 8% is found at a distance of 10 km downwind from the wind farm. Furthermore, this study compares the wind farm wake dynamics for cases in which the conventionally neutral ABLs are driven by a unidirectional pressure gradient and Coriolis forces.

  5. Wind farm turbine type and placement optimization

    SciTech Connect

    Graf, Peter; Dykes, Katherine; Scott, George; Fields, Jason; Lunacek, Monte; Quick, Julian; Rethore, Pierre -Elouan

    2016-10-03

    The layout of turbines in a wind farm is already a challenging nonlinear, nonconvex, nonlinearly constrained continuous global optimization problem. Here we begin to address the next generation of wind farm optimization problems by adding the complexity that there is more than one turbine type to choose from. The optimization becomes a nonlinear constrained mixed integer problem, which is a very difficult class of problems to solve. Furthermore, this document briefly summarizes the algorithm and code we have developed, the code validation steps we have performed, and the initial results for multi-turbine type and placement optimization (TTP_OPT) we have run.

  6. Wind Farm Turbine Type and Placement Optimization

    NASA Astrophysics Data System (ADS)

    Graf, Peter; Dykes, Katherine; Scott, George; Fields, Jason; Lunacek, Monte; Quick, Julian; Rethore, Pierre-Elouan

    2016-09-01

    The layout of turbines in a wind farm is already a challenging nonlinear, nonconvex, nonlinearly constrained continuous global optimization problem. Here we begin to address the next generation of wind farm optimization problems by adding the complexity that there is more than one turbine type to choose from. The optimization becomes a nonlinear constrained mixed integer problem, which is a very difficult class of problems to solve. This document briefly summarizes the algorithm and code we have developed, the code validation steps we have performed, and the initial results for multi-turbine type and placement optimization (TTP_OPT) we have run.

  7. Wind height distribution influence on offshore wind farm feasibility study

    NASA Astrophysics Data System (ADS)

    Benassai, Guido; Della Morte, Renata; Matarazzo, Antonio; Cozzolino, Luca

    2015-04-01

    The economic feasibility of offshore wind power utilization depends on the favourable wind conditions offshore as compared to sites on land. The higher wind speeds have to compensate the additional cost of offshore developments. However, not only the mean wind speed is different, but the whole flow regime, as can be seen in the vertical wind speed profile. The commonly used models to describe this profile have been developed mainly for land sites, so they have to be verified on the basis of field data. Monin-Obukhov theory is often used for the description of the wind speed profile at a different height with respect to a measurement height. Starting from the former, , the profile is predicted using two parameters, Obukhov length and sea surface roughness. For situations with near-neutral and stable atmospheric stratification and long (>30km) fetch, the wind speed increase with height is larger than what is predicted from Monin-Obukhov theory. It is also found that this deviation occurs at wind speeds important for wind power utilization, mainly at 5-9 ms-1. In the present study the influence of these aspects on the potential site productivity of an offshore wind farm were investigated, namely the deviation from the theory of Monin-Obukhov due to atmospheric stability and the influence of the fetch length on the Charnock model. Both these physical effects were discussed and examined in view of a feasibility study of a site for offshore wind farm in Southern Italy. Available data consisted of time histories of wind speeds and directions collected by National Tidegauge Network (Rete Mareografica Nazionale) at the height of 10m a.s.l. in ports. The theory of Monin-Obukhov was used to extrapolate the data to the height of the wind blades, while the Charnock model was used to extend the wind speed on the sea surface from the friction velocity on the ground. The models described were used to perform calculations for a feasibility study of an offshore wind farm in Southern

  8. Optimizing Baseload Power of Interconnected Wind Farms

    NASA Astrophysics Data System (ADS)

    Kobrin, B. H.

    2010-12-01

    Interconnecting wind farms has been proposed as a way to reduce the natural unreliability of wind power caused by the intermittency of winds. In a previous study, the benefits of interconnecting up to 19 sites in the Midwestern United States were evaluated with the assumption that the same number of turbines would be installed at each site. The goal of this study was to avoid this assumption and examine the advantages of optimizing the ratio of turbines at each site. An optimization algorithm based on the gradient method was used to maximize the baseload power, or guaranteed power 87.5% of the year, using hourly wind speed data for the same 19 sites. The result was a significant improvement in the reliability of the array, increasing the baseload power by 38% compared to the array with equally-weighted sites. Further analysis showed that the turbines were generally distributed according to the average wind power at each site and the wind correlation among sites. In addition to optimizing the average baseload of the array, this study examined the benefits of optimizing the baseload for peak usage time (between noon and 7 p.m), and thus a simplified model was created to analyze how interconnecting wind farms could increase correlation with energy consumption. Optimization for peak usage hours, however, provided no additional benefit over the original optimized array because the variation of average hourly wind speeds was well-correlated among the sites.

  9. Development of a Scaled Smart Wind Farm

    NASA Astrophysics Data System (ADS)

    Pol, Suhas; Taylor, Amelia; McKeon, Dalton; Castillo, Luciano; Perez, Isaias; Beibei, Ren; Sheng, Jian; Westergaard, Carsten; Burak, Aksak; Araya, Guillermo; Hussain, Fazle

    2013-11-01

    A model wind farm consisting of 3X5 horizontal axis turbines with a rotor diameter of 4 m (to be expanded to 5X20 turbines of 2 m diameter) is being developed on TTU campus. Real field turbine wake evolution and interactions will be studied by employing particle image velocimetry. A 10 m tower upstream of the wind farm as well as a 200 m tower located 500 m from the site will be used to characterize the atmospheric condition and its influence on the wake evolution. Of particular interest is the role of coherent structures in the atmosphere and the wake on the downward transport of overhead momentum--hence the effectiveness of the wind farm. From the recorded data episodes of stable, unstable and neutral atmosphere will be conditionally sampled to understand the effect of atmospheric stability on wind farm dynamics. The effect of various turbine-turbine separation and orientation on the downward momentum transport will be studied - quite feasible since the turbine models are portable. In addition to aerodynamic studies the facility we will also test control algorithms.

  10. Economics of wind farm layout

    SciTech Connect

    Germain, A.C.; Bain, D.A.

    1997-12-31

    The life cycle cost of energy (COE) is the primary determinant of the economic viability of a wind energy generation facility. The cost of wind turbines and associated hardware is counterbalanced by the energy which can be generated. This paper focuses on the turbine layout design process, considering the cost and energy capture implications of potential spacing options from the viewpoint of a practicing project designer. It is argued that lateral spacings in the range of 1.5 to 5 diameters are all potentially optimal, but only when matched to wind resource characteristics and machine design limits. The effect of wakes on energy capture is quantified while the effect on turbine life and maintenance cost is discussed qualitatively. Careful optimization can lower COE and project designers are encouraged to integrate the concepts in project designs.

  11. Lightning hazard reduction at wind farms

    SciTech Connect

    Kithil, R.

    1997-12-31

    The USA wind farm industry (WFI) largely is centered in low-lightning areas of the State of California. While some evidence of lightning incidents is reported here, the problem is not regarded as serious by most participants. The USA WFI now is moving eastward, into higher areas of lightning activity. The European WFI has had many years experience with lightning problems. One 1995 German study estimated that 80% of wind turbine insurance claims paid for damage compensation were caused by lightning strikes. The European and USA WFI have not adopted site criteria, design fundamentals, or certification techniques aimed at lightning safety. Sufficient evidence about lightning at wind farms is available to confirm that serious potential problems exist.

  12. Mesoscale to microscale wind farm flow modeling and evaluation: Mesoscale to Microscale Wind Farm Models

    SciTech Connect

    Sanz Rodrigo, Javier; Chávez Arroyo, Roberto Aurelio; Moriarty, Patrick; Churchfield, Matthew; Kosović, Branko; Réthoré, Pierre-Elouan; Hansen, Kurt Schaldemose; Hahmann, Andrea; Mirocha, Jeffrey D.; Rife, Daran

    2016-08-31

    The increasing size of wind turbines, with rotors already spanning more than 150 m diameter and hub heights above 100 m, requires proper modeling of the atmospheric boundary layer (ABL) from the surface to the free atmosphere. Furthermore, large wind farm arrays create their own boundary layer structure with unique physics. This poses significant challenges to traditional wind engineering models that rely on surface-layer theories and engineering wind farm models to simulate the flow in and around wind farms. However, adopting an ABL approach offers the opportunity to better integrate wind farm design tools and meteorological models. The challenge is how to build the bridge between atmospheric and wind engineering model communities and how to establish a comprehensive evaluation process that identifies relevant physical phenomena for wind energy applications with modeling and experimental requirements. A framework for model verification, validation, and uncertainty quantification is established to guide this process by a systematic evaluation of the modeling system at increasing levels of complexity. In terms of atmospheric physics, 'building the bridge' means developing models for the so-called 'terra incognita,' a term used to designate the turbulent scales that transition from mesoscale to microscale. This range of scales within atmospheric research deals with the transition from parameterized to resolved turbulence and the improvement of surface boundary-layer parameterizations. The coupling of meteorological and wind engineering flow models and the definition of a formal model evaluation methodology, is a strong area of research for the next generation of wind conditions assessment and wind farm and wind turbine design tools. Some fundamental challenges are identified in order to guide future research in this area.

  13. Study of a Wind Farm Power System: Preprint

    SciTech Connect

    Muljadi, E.; Wan, Y.; Butterfield, C. P.; Parsons, B.

    2002-01-01

    A wind power system differs from a conventional power system. In a conventional power plant, the operator can control the plant's output. The output of a wind farm cannot be controlled because the output fluctuates with the wind. In this paper, we investigate the power-system interaction resulting from power variations at wind farms using steady-state analysis.

  14. Wind Speed Estimation and Wake model Re-calibration for Downregulated Offshore Wind Farms

    NASA Astrophysics Data System (ADS)

    Göçmen Bozkurt, Tuhfe; Giebel, Gregor; Kjølstad Poulsen, Niels; Réthoré, Pierre-Elouan; Mirzaei, Mahmood

    2014-05-01

    In recent years, the wind farm sizes have increased tremendously and with increasing installed capacity, the wind farms are requested to downregulate from their maximum possible power more frequently, especially in the offshore environment. Determination of the possible (or available) power is crucial not only because the reserve power has considerable market value but also for wind farm developers to be properly compensated for the loss during downregulation. While the available power calculation is straightforward for a single turbine, it gets rather complicated for the whole wind farm due to the change in the wake characteristics. In fact, the wake losses generated by the upstream turbine(s) decrease during downregulation and the downstream turbines therefore see more wind compared to the normal operation case. Currently, the Transmission System Operators (TSOs) have no real way to determine exactly the available power of a whole wind farm which is downregulated. Therefore, the PossPOW project aims to develop a verified and internationally accepted way to determine the possible power of a down-regulated offshore wind farm. The first phase of the project is to estimate the rotor effective wind speed. Since the nacelle anemometers are not readily available and are known to have reliability issues, the proposed method is to use power, pitch angle and rotational speed as inputs and combine it with a generic Cp model to estimate the wind speed. The performance of the model has been evaluated for both normal operation and downregulation periods using two different case studies: Horns Rev-I wind farm and NREL 5MW single turbine. During downregulation, the wake losses are not as severe and the velocity deficits at the downstream turbines are smaller as if also the wake is "downregulated". On the other hand, in order to calculate the available power, the wakes that would have been produced normally (if the turbines were not curtailed) are of importance, not the

  15. Maiden Wind Farm Draft Environmental Impact Statement

    SciTech Connect

    N /A

    2002-03-29

    In February 2001, Washington Winds Inc. (the project developer) submitted a proposal to Bonneville Power Administration (BPA) for a site north of the cities of Sunnyside and Prosser in Washington where wind power facilities could be developed. After considering preliminary information, BPA decided to examine the proposed project and consider purchasing and transmitting power from the project. The project developer also submitted Conditional use Permit (CUP) applications to Benton and Yakima Counties. Benton County, serving as the lead agency for the State Environmental Policy Act (SEPA), issued a Determination of Significance on June 11, 2001. The action proposed by BPA is to: (1) execute a 20-year power purchase agreement with the project developer for up to 50 average megawatts (aMW) (up to about 200 megawatts [MW]) of electrical energy from the proposed Maiden Wind Farm; and (2) execute construction and generation interconnection agreements with the project developer to integrate the power generated by the proposed Maiden Wind Farm into BPA's transmission system. The need for the proposed action arises primarily from BPA's statutory obligations and planning directives. BPA will consider the information in this Environmental Impact Statement (EIS), public comments, and other factors when deciding whether to purchase power from the proposed wind project and transmit it over BPA transmission lines. Benton and Yakima County Planning Departments will consider information in this EIS when deciding whether to grant a CUP and allow the proposed project to be developed.

  16. Offshore wind farm electrical cable layout optimization

    NASA Astrophysics Data System (ADS)

    Pillai, A. C.; Chick, J.; Johanning, L.; Khorasanchi, M.; de Laleu, V.

    2015-12-01

    This article explores an automated approach for the efficient placement of substations and the design of an inter-array electrical collection network for an offshore wind farm through the minimization of the cost. To accomplish this, the problem is represented as a number of sub-problems that are solved in series using a combination of heuristic algorithms. The overall problem is first solved by clustering the turbines to generate valid substation positions. From this, a navigational mesh pathfinding algorithm based on Delaunay triangulation is applied to identify valid cable paths, which are then used in a mixed-integer linear programming problem to solve for a constrained capacitated minimum spanning tree considering all realistic constraints. The final tree that is produced represents the solution to the inter-array cable problem. This method is applied to a planned wind farm to illustrate the suitability of the approach and the resulting layout that is generated.

  17. Outer layer effects in wind-farm boundary layers: Coriolis forces and boundary layer height

    NASA Astrophysics Data System (ADS)

    Allaerts, Dries; Meyers, Johan

    2015-11-01

    In LES studies of wind-farm boundary layers, scale separation between the inner and outer region of the atmospheric boundary layer (ABL) is frequently assumed, i.e., wind turbines are presumed to fall within the inner layer and are not affected by outer layer effects. However, modern wind turbine and wind farm design tends towards larger rotor diameters and farm sizes, which means that outer layer effects will become more important. In a prior study, it was already shown for fully-developed wind farms that the ABL height influences the power performance. In this study, we use the in-house LES code SP-Wind to investigate the importance of outer layer effects on wind-farm boundary layers. In a suite of LES cases, the ABL height is varied by imposing a capping inversion with varying inversion strengths. Results indicate the growth of an internal boundary layer (IBL), which is limited in cases with low inversion layers. We further find that flow deceleration combined with Coriolis effects causes a change in wind direction throughout the farm. This effect increases with decreasing boundary layer height, and can result in considerable turbine wake deflection near the end of the farm. The authors are supported by the ERC (ActiveWindFarms, grant no: 306471). Computations were performed on VSC infrastructiure (Flemish Supercomputer Center), funded by the Hercules Foundation and the Flemish Government-department EWI.

  18. CFD modeling of wind turbine wake in wind farms

    NASA Astrophysics Data System (ADS)

    Sun, Lijian

    Wind energy is one of the most common and preferred renewable energy sources. Accurate predictions of atmospheric boundary layer flow, wind turbine induced wakes and their interaction are essential to maximize wind power output and efficiently harness wind energy. In this dissertation, a computational fluid dynamics (CFD) flow model is developed utilizing a three dimensional weighted essentially non-oscillatory (WENO) high order Finite Volume Model system including Large Eddy Simulation (LES) and the Actuator Line Method (ALM). The developed model system is thus able to accurately capture and simulate wind turbine wakes and their interaction with the atmospheric boundary layer, thereby providing insight into the phenomenon of turbine wake interaction and its effect on the external aerodynamic loads on wind turbines. This enables the wind energy production to be maximized and also minimizes turbine fatigue loading in the evaluation of wind farm layouts. By using LES model to simulate the Atmospheric Boundary Layer flow rather than the Reynolds-Averaged Navier-Stokes (RANS) model, the error introduced by turbulence modeling is reduced. The Actuator Line Model, ALM, is used to model the rotor by replacing the rotor with radially distributed body forces. It is more accurate than the actuator disc method as it captures the influence of the blade tip vortices. It can focus on a larger portion of the wake without resolving the actual wind turbine blades' geometry, thereby reducing computational cost. It is suitable and a promising method for wind turbine wake simulation. Classic non-trivial turbulent benchmark cases are used to validate the high order LES algorithms. Simulation results are compared with available results whenever possible, with good agreement observed. Results for the atmospheric boundary layer under neutral conditions are presented. By using LES coupled with the Actuator Line model, simulation results are obtained for detailed wake flow features around

  19. A model to predict the power output from wind farms

    SciTech Connect

    Landberg, L.

    1997-12-31

    This paper will describe a model that can predict the power output from wind farms. To give examples of input the model is applied to a wind farm in Texas. The predictions are generated from forecasts from the NGM model of NCEP. These predictions are made valid at individual sites (wind farms) by applying a matrix calculated by the sub-models of WASP (Wind Atlas Application and Analysis Program). The actual wind farm production is calculated using the Riso PARK model. Because of the preliminary nature of the results, they will not be given. However, similar results from Europe will be given.

  20. 76 FR 35882 - Paulding Wind Farm II, LLC, et al.;

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-20

    ....] Paulding Wind Farm II, LLC, et al.; Notice of Effectiveness of Exempt Wholesale Generator Status Docket Nos. Paulding Wind Farm II LLC EG11-61-000 Macho Springs Power I, LLC EG11-63-000 Alta Wind III Owner Lessor A EG11-64-000 Alta Wind III Owner Lessor B EG11-65-000 Alta Wind III Owner Lessor C EG11-66-000 Alta...

  1. Real time wind farm emulation using SimWindFarm toolbox

    NASA Astrophysics Data System (ADS)

    Topor, Marcel

    2016-06-01

    This paper presents a wind farm emulation solution using an open source Matlab/Simulink toolbox and the National Instruments cRIO platform. This work is based on the Aeolus SimWindFarm (SWF) toolbox models developed at Aalborg university, Denmark. Using the Matlab Simulink models developed in SWF, the modeling code can be exported to a real time model using the NI Veristand model framework and the resulting code is integrated as a hardware in the loop control on the NI 9068 platform.

  2. Could Crop Roughness Impact the Wind Resource at Agriculturally Productive Wind Farm Sites?

    NASA Astrophysics Data System (ADS)

    Vanderwende, B. J.; Lundquist, J. K.

    2014-12-01

    The high concentration of both large-scale agriculture and wind power production in the United States Midwest region raises new questions concerning the interaction of the two activities. For instance, it is known from internal boundary layer theory that changes in the roughness of the land-surface resulting from crop choices could modify the momentum field aloft. Upward propagation of such an effect might impact the properties of the winds encountered by modern turbines, which typically span a layer from about 40 to 120 meters above the surface. As direct observation of such interaction would require impractical interference in the planting schedules of farmers, we use numerical modeling to quantify the magnitude of crop-roughness effects. To simulate a collocated farm and turbine array, we use version 3.4.1 of the Weather Research and Forecasting model (WRF). The hypothetical farm is inserted near the real location of the 2013 Crop Wind Energy Experiment (CWEX). Reanalyses provide representative initial and boundary conditions. A month-long period spanning August 2013 is used to evaluate the differences in flows above corn (maize) and soybean crops at the mature, reproductive stage. Simulations are performed comparing the flow above each surface regime, both in the absence and presence of a wind farm, which consists of a parameterized 11x11 array of 1.8 MW Vestas V90 turbines. Appreciable differences in rotor-layer wind speeds emerge. The use of soybeans results in an increase in wind speeds and a corresponding reduction in rotor-layer shear when compared to corn. Despite the turbulent nature of flow within a wind farm, high stability reduces the impact of crop roughness on the flow aloft, particularly in the upper portion of the rotor disk. We use these results to estimate the economic impact of crop selection on wind power producers.

  3. Impacts of wind farms on surface air temperatures

    PubMed Central

    Baidya Roy, Somnath; Traiteur, Justin J.

    2010-01-01

    Utility-scale large wind farms are rapidly growing in size and numbers all over the world. Data from a meteorological field campaign show that such wind farms can significantly affect near-surface air temperatures. These effects result from enhanced vertical mixing due to turbulence generated by wind turbine rotors. The impacts of wind farms on local weather can be minimized by changing rotor design or by siting wind farms in regions with high natural turbulence. Using a 25-y-long climate dataset, we identified such regions in the world. Many of these regions, such as the Midwest and Great Plains in the United States, are also rich in wind resources, making them ideal candidates for low-impact wind farms. PMID:20921371

  4. Impacts of wind farms on surface air temperatures.

    PubMed

    Baidya Roy, Somnath; Traiteur, Justin J

    2010-10-19

    Utility-scale large wind farms are rapidly growing in size and numbers all over the world. Data from a meteorological field campaign show that such wind farms can significantly affect near-surface air temperatures. These effects result from enhanced vertical mixing due to turbulence generated by wind turbine rotors. The impacts of wind farms on local weather can be minimized by changing rotor design or by siting wind farms in regions with high natural turbulence. Using a 25-y-long climate dataset, we identified such regions in the world. Many of these regions, such as the Midwest and Great Plains in the United States, are also rich in wind resources, making them ideal candidates for low-impact wind farms.

  5. A canopy-type similarity model for wind farm optimization

    NASA Astrophysics Data System (ADS)

    Markfort, Corey D.; Zhang, Wei; Porté-Agel, Fernando

    2013-04-01

    The atmospheric boundary layer (ABL) flow through and over wind farms has been found to be similar to canopy-type flows, with characteristic flow development and shear penetration length scales (Markfort et al., 2012). Wind farms capture momentum from the ABL both at the leading edge and from above. We examine this further with an analytical canopy-type model. Within the flow development region, momentum is advected into the wind farm and wake turbulence draws excess momentum in from between turbines. This spatial heterogeneity of momentum within the wind farm is characterized by large dispersive momentum fluxes. Once the flow within the farm is developed, the area-averaged velocity profile exhibits a characteristic inflection point near the top of the wind farm, similar to that of canopy-type flows. The inflected velocity profile is associated with the presence of a dominant characteristic turbulence scale, which may be responsible for a significant portion of the vertical momentum flux. Prediction of this scale is useful for determining the amount of available power for harvesting. The new model is tested with results from wind tunnel experiments, which were conducted to characterize the turbulent flow in and above model wind farms in aligned and staggered configurations. The model is useful for representing wind farms in regional scale models, for the optimization of wind farms considering wind turbine spacing and layout configuration, and for assessing the impacts of upwind wind farms on nearby wind resources. Markfort CD, W Zhang and F Porté-Agel. 2012. Turbulent flow and scalar transport through and over aligned and staggered wind farms. Journal of Turbulence. 13(1) N33: 1-36. doi:10.1080/14685248.2012.709635.

  6. Research on large-scale wind farm modeling

    NASA Astrophysics Data System (ADS)

    Ma, Longfei; Zhang, Baoqun; Gong, Cheng; Jiao, Ran; Shi, Rui; Chi, Zhongjun; Ding, Yifeng

    2017-01-01

    Due to intermittent and adulatory properties of wind energy, when large-scale wind farm connected to the grid, it will have much impact on the power system, which is different from traditional power plants. Therefore it is necessary to establish an effective wind farm model to simulate and analyze the influence wind farms have on the grid as well as the transient characteristics of the wind turbines when the grid is at fault. However we must first establish an effective WTGs model. As the doubly-fed VSCF wind turbine has become the mainstream wind turbine model currently, this article first investigates the research progress of doubly-fed VSCF wind turbine, and then describes the detailed building process of the model. After that investigating the common wind farm modeling methods and pointing out the problems encountered. As WAMS is widely used in the power system, which makes online parameter identification of the wind farm model based on off-output characteristics of wind farm be possible, with a focus on interpretation of the new idea of identification-based modeling of large wind farms, which can be realized by two concrete methods.

  7. NREL Studies Wind Farm Aerodynamics to Improve Siting (Fact Sheet)

    SciTech Connect

    Not Available

    2012-04-01

    NREL researchers have used high-tech instruments and high-performance computing to understand atmospheric turbulence and turbine wake behavior in order to improve wind turbine design and siting within wind farms.

  8. Wind tunnel testing of a closed-loop wake deflection controller for wind farm power maximization

    NASA Astrophysics Data System (ADS)

    Campagnolo, Filippo; Petrović, Vlaho; Schreiber, Johannes; Nanos, Emmanouil M.; Croce, Alessandro; Bottasso, Carlo L.

    2016-09-01

    This paper presents results from wind tunnel tests aimed at evaluating a closed- loop wind farm controller for wind farm power maximization by wake deflection. Experiments are conducted in a large boundary layer wind tunnel, using three servo-actuated and sensorized wind turbine scaled models. First, we characterize the impact on steady-state power output of wake deflection, achieved by yawing the upstream wind turbines. Next, we illustrate the capability of the proposed wind farm controller to dynamically driving the upstream wind turbines to the optimal yaw misalignment setting.

  9. Impact Wind Farms on the Marine Atmospheric Boundary Layer

    NASA Astrophysics Data System (ADS)

    Volker, P.; Capps, S. B.; Huang, H. J.; Sun, F.; Badger, J.; Hahmann, A.

    2012-12-01

    We introduce a new, validated wind farm parametrization (Explicit Wake Parametrization, EWP) which is based on the assumption that the downstream propagation of a single turbine wake can be described by a turbulent diffusion process. Thus, the downstream velocity deficit distribution can be described explicitly. Additionally, it allows us to take into account turbine interactions, making it possible to determine the unresolved turbine hub height velocities. Both the EWP wind farm parametrization and the wind farm scheme available in the Weather Research & Forecasting Model (WRF) have been validated against in situ measurements from Horns Rev I (A large offshore wind farm consisting of 80 2MW turbines situated near the west coast of Denmark). The main quantities of interest are the thrust applied to the flow, a consequence of the energy extracted by the wind turbines which determines mainly the wind farm wake extension (around 50 km for Horns Rev I) and the vertical velocity deficit distribution. Results show that the thrust in the WRF-WF scheme is overestimated inside the wind farm. We noticed that the velocity deficit propagates from the first turbine-containing-grid-cell up to the boundary layer top, which is in contrast to the theoretical expected expansion (confirmed by turbulence resolving models and wind tunnel results). The vertical expansion of the velocity deficit is a consequence of the additional turbulence source term in the WRF-WF scheme. The EWP scheme estimates the total amount of thrust correctly and is also able to follow the reduced thrust downstream since it considers the turbine interaction. From the good agreement with the far wake measurement, we can conclude that the formulation of the sub grid scale vertical extension of the velocity deficit must be correct. We will present results from WRF simulations in which we analyze the atmospheric response within the wake of wind farms resulting from the energy extraction of wind turbines. We place

  10. Mapping Seabird Sensitivity to Offshore Wind Farms

    PubMed Central

    Bradbury, Gareth; Trinder, Mark; Furness, Bob; Banks, Alex N.; Caldow, Richard W. G.; Hume, Duncan

    2014-01-01

    We present a Geographic Information System (GIS) tool, SeaMaST (Seabird Mapping and Sensitivity Tool), to provide evidence on the use of sea areas by seabirds and inshore waterbirds in English territorial waters, mapping their relative sensitivity to offshore wind farms. SeaMaST is a freely available evidence source for use by all connected to the offshore wind industry and will assist statutory agencies in assessing potential risks to seabird populations from planned developments. Data were compiled from offshore boat and aerial observer surveys spanning the period 1979–2012. The data were analysed using distance analysis and Density Surface Modelling to produce predicted bird densities across a grid covering English territorial waters at a resolution of 3 km×3 km. Coefficients of Variation were estimated for each grid cell density, as an indication of confidence in predictions. Offshore wind farm sensitivity scores were compiled for seabird species using English territorial waters. The comparative risks to each species of collision with turbines and displacement from operational turbines were reviewed and scored separately, and the scores were multiplied by the bird density estimates to produce relative sensitivity maps. The sensitivity maps reflected well the amassed distributions of the most sensitive species. SeaMaST is an important new tool for assessing potential impacts on seabird populations from offshore development at a time when multiple large areas of development are proposed which overlap with many seabird species’ ranges. It will inform marine spatial planning as well as identifying priority areas of sea usage by marine birds. Example SeaMaST outputs are presented. PMID:25210739

  11. Mapping seabird sensitivity to offshore wind farms.

    PubMed

    Bradbury, Gareth; Trinder, Mark; Furness, Bob; Banks, Alex N; Caldow, Richard W G; Hume, Duncan

    2014-01-01

    We present a Geographic Information System (GIS) tool, SeaMaST (Seabird Mapping and Sensitivity Tool), to provide evidence on the use of sea areas by seabirds and inshore waterbirds in English territorial waters, mapping their relative sensitivity to offshore wind farms. SeaMaST is a freely available evidence source for use by all connected to the offshore wind industry and will assist statutory agencies in assessing potential risks to seabird populations from planned developments. Data were compiled from offshore boat and aerial observer surveys spanning the period 1979-2012. The data were analysed using distance analysis and Density Surface Modelling to produce predicted bird densities across a grid covering English territorial waters at a resolution of 3 km×3 km. Coefficients of Variation were estimated for each grid cell density, as an indication of confidence in predictions. Offshore wind farm sensitivity scores were compiled for seabird species using English territorial waters. The comparative risks to each species of collision with turbines and displacement from operational turbines were reviewed and scored separately, and the scores were multiplied by the bird density estimates to produce relative sensitivity maps. The sensitivity maps reflected well the amassed distributions of the most sensitive species. SeaMaST is an important new tool for assessing potential impacts on seabird populations from offshore development at a time when multiple large areas of development are proposed which overlap with many seabird species' ranges. It will inform marine spatial planning as well as identifying priority areas of sea usage by marine birds. Example SeaMaST outputs are presented.

  12. The Problems with "Noise Numbers" for Wind Farm Noise Assessment

    ERIC Educational Resources Information Center

    Thorne, Bob

    2011-01-01

    Human perception responds primarily to sound character rather than sound level. Wind farms are unique sound sources and exhibit special audible and inaudible characteristics that can be described as modulating sound or as a tonal complex. Wind farm compliance measures based on a specified noise number alone will fail to address problems with noise…

  13. Exploring the wakes of large offshore wind farms

    NASA Astrophysics Data System (ADS)

    Emeis, S.; Siedersleben, S.; Lampert, A.; Platis, A.; Bange, J.; Djath, B.; Schulz-Stellenfleth, J.; Neumann, T.

    2016-09-01

    Offshore meteorological characteristics set specific conditions for the operation of offshore wind farms. One specific feature is low turbulence intensity which on the one hand reduces loads on turbines but on the other hand is the reason for much longer turbine and farm wakes than over land. The German Government is presently funding a research project called WIPAFF (Wind PArk Far Field) which heads for the analysis of properties and impacts of offshore wind park far fields. The focus is on the analysis of wind farm wakes, their interaction among each other and their regional climate impact. This is done by in-situ, extensive aircraft and satellite measurements and by operating meso-scale wind field models and an analytical wind farm model.

  14. Statistical and physical modelling of large wind farm clusters

    NASA Astrophysics Data System (ADS)

    Barthelmie, R.; Pryor, S.; Frandsen, S.

    2003-04-01

    As the first large wind farms are constructed the issue of the effect of large wind farms on local climates is being raised. The main concern currently is that, in some countries, areas in which large offshore wind farms can be constructed over the next 10 to 20 years are fairly limited due to technical and economic constraints. This means that wind farms will be built in clusters of up to 100 wind turbines but within 20 km of the nearest cluster. Theoretical considerations suggest that the effects of a wind farm on a downwind wind farm maybe more noticeable offshore than onshore where higher turbulence assists wind speed recovery. Added to this many offshore areas are dominated by stable and neutral atmospheres where wakes propagate over longer distances than on land where unstable conditions also occur for a significant fraction of the time. On the other hand the large turbulence generated by the wind farm itself may be sufficient to assist wind recovery but possibly provide a higher than expected turbulence at the neighbouring wind farm or cluster. While some progress has been made with single wake modelling offshore, these models have not been evaluated for more than 5 wakes. Hence it is difficult to evaluate the impact of large wind farms and to optimise the spacing of clusters. A new project STORPARK is underway which is using statistical and physical modelling methods to make preliminary estimates of large wind farm impacts. The work described in this paper is a combination of statistical methods using observations from offshore wind monitoring sites at Vindeby/Omø Stålgrunde and Rødsand/Gedser in Denmark to evaluate in the first instance how far the effects of land can be detected on wind speed and turbulence intensity. These results will be compared with model simulations from WAsP and the Coastal Discontinuity Model (CDM) where large wind farms are currently represented by large roughness elements in accord with models developed by Crespo, Frandsen and

  15. Analysis of wind farm energy produced in the United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The electricity generated by wind farms in almost every state in the United States with over 10 MW of wind turbine capacity was analyzed over a five-year period (2002 to 2006). The total amount of wind generated electricity in the United States for 2006 was estimated at 26.3 terawatt-hours which wa...

  16. Optimal coordinated control of energy extraction in LES of wind farms: effect of turbine arrangement patterns

    NASA Astrophysics Data System (ADS)

    Meyers, Johan; Munters, Wim; Goit, Jay

    2015-11-01

    We investigate optimal control of wind-farm boundary layers, considering the individual wind turbines as flow actuators. By controlling the thrust coefficients of the turbines as function of time, the energy extraction can be dynamically regulated with the aim to optimally influence the flow field and the vertical energy transport. To this end, we use Large-Eddy Simulations (LES) of wind-farm boundary layers in a receding-horizon optimal control framework. Recently, the approach was applied to fully developed wind-farm boundary layers in a 7D by 6D aligned wind-turbine arrangement. For this case, energy extraction increased up to 16%, related to improved wake mixing by slightly anti-correlating the turbine thrust coefficient with the local wind speed at the turbine level. Here we discuss optimal control results for finite wind farms that are characterized by entrance effects and a developing internal boundary layer above the wind farm. Both aligned and staggered arrangement patterns are considered, and a range of different constraints on the controls is included. The authors acknowledge support from the European Research Council (FP7-Ideas, grant no. 306471). Simulations were performed on the infrastructure of the Flemish Supercomputer Center, funded by the Hercules Foundation and the Flemish Governement.

  17. Effects of Turbine Spacing in Very Large Wind Farms

    NASA Astrophysics Data System (ADS)

    Andersen, Søren Juhl; Sørensen, Jens Nørkær; Mikkelsen, Robert Flemming

    2015-11-01

    The Dynamic Wake Meandering model(DWM) by Larsen et al. (2007) is considered state of the art for modelling the wake behind a wind turbine. DWM assumes a quasi-steady wake deficit transported as a passive tracer by large atmospheric scales. The approach is also applied to wake interaction within wind farms, although certain aspects of the complex wake interaction are not captured, see Churchfield et al. (2014). Recent studies have shown how turbines introduce low frequencies in the wake, which could describe some of the shortcomings. Chamorro et al. (2015) identified three regions of different lengths scales. Iungo et al. (2013) related low frequencies to the hub vortex instability. Okulov et al. (2014) found Strouhal numbers in the far wake stemming from the rotating helical vortex core. Simulations by Andersen et al. (2013) found low frequencies to be inherent in the flow inside an infinite wind farm. LES simulations of large wind farms are performed with full aero-elastic Actuator Lines. The simulations investigate the inherent dynamics inside wind farms in the absence of atmospheric turbulence compared to cases with atmospheric turbulence. Resulting low frequency structures are inherent in wind farms for certain turbine spacings and affect both power production and loads. Funded by Danish Council for Strategic Research (grant 2104-09-067216/DSF), the Nordic Consortium on Optimization and Control of Wind Farms, and EuroTech wind project. The proprietary data for Vestas' NM80 turbine has been used.

  18. Using Wind Tunnels to Predict Bird Mortality in Wind Farms: The Case of Griffon Vultures

    PubMed Central

    de Lucas, Manuela; Ferrer, Miguel; Janss, Guyonne F. E.

    2012-01-01

    Background Wind farms have shown a spectacular growth during the last 15 years. Avian mortality through collision with moving rotor blades is well-known as one of the main adverse impacts of wind farms. In Spain, the griffon vulture incurs the highest mortality rates in wind farms. Methodology/Principal Findings As far as we know, this study is the first attempt to predict flight trajectories of birds in order to foresee potentially dangerous areas for wind farm development. We analyse topography and wind flows in relation to flight paths of griffon vultures, using a scaled model of the wind farm area in an aerodynamic wind tunnel, and test the difference between the observed flight paths of griffon vultures and the predominant wind flows. Different wind currents for each wind direction in the aerodynamic model were observed. Simulations of wind flows in a wind tunnel were compared with observed flight paths of griffon vultures. No statistical differences were detected between the observed flight trajectories of griffon vultures and the wind passages observed in our wind tunnel model. A significant correlation was found between dead vultures predicted proportion of vultures crossing those cells according to the aerodynamic model. Conclusions Griffon vulture flight routes matched the predominant wind flows in the area (i.e. they followed the routes where less flight effort was needed). We suggest using these kinds of simulations to predict flight paths over complex terrains can inform the location of wind turbines and thereby reduce soaring bird mortality. PMID:23152764

  19. Onshore Wind Farms: Value Creation for Stakeholders in Lithuania

    NASA Astrophysics Data System (ADS)

    Burinskienė, Marija; Rudzkis, Paulius; Kanopka, Adomas

    With the costs of fossil fuel consistently rising worldwide over the last decade, the development of green technologies has become a major goal in many countries. Therefore the evaluation of wind power projects becomes a very important task. To estimate the value of the technologies based on renewable resources also means taking into consideration social, economic, environmental, and scientific value of such projects. This article deals with economic evaluation of electricity generation costs of onshore wind farms in Lithuania and the key factors that have influence on wind power projects and offer a better understanding of social-economic context behind wind power projects. To achieve these goals, this article makes use of empirical data of Lithuania's wind power farms as well as data about the investment environment of the country.Based on empirical data of wind power parks, the research investigates the average wind farm generation efficiency in Lithuania. Employing statistical methods the return on investments of wind farms in Lithuania is calculated. The value created for every party involved and the total value of the wind farm is estimated according to Stakeholder theory.

  20. Turbulence and entrainment length scales in large wind farms.

    PubMed

    Andersen, Søren J; Sørensen, Jens N; Mikkelsen, Robert F

    2017-04-13

    A number of large wind farms are modelled using large eddy simulations to elucidate the entrainment process. A reference simulation without turbines and three farm simulations with different degrees of imposed atmospheric turbulence are presented. The entrainment process is assessed using proper orthogonal decomposition, which is employed to detect the largest and most energetic coherent turbulent structures. The dominant length scales responsible for the entrainment process are shown to grow further into the wind farm, but to be limited in extent by the streamwise turbine spacing, which could be taken into account when developing farm layouts. The self-organized motion or large coherent structures also yield high correlations between the power productions of consecutive turbines, which can be exploited through dynamic farm control.This article is part of the themed issue 'Wind energy in complex terrains'.

  1. Statistics of LES Simulations of Large Wind Farms

    NASA Astrophysics Data System (ADS)

    Juhl Andersen, Søren; Nørkær Sørensen, Jens; Mikkelsen, Robert; Ivanell, Stefan

    2016-09-01

    Numerous large eddy simulations are performed of large wind farms using the actuator line method, which has been fully coupled to the aero-elastic code, Flex5. The higher order moments of the flow field inside large wind farms is examined in order to determine a representative reference velocity. The statistical moments appear to collapse and hence the turbulence inside large wind farms can potentially be scaled accordingly. The thrust coefficient is estimated by two different reference velocities and the generic CT expression by Frandsen. A reference velocity derived from the power production is shown to give very good agreement and furthermore enables the very good estimation of the thrust force using only the steady CT -curve, even for very short time samples. Finally, the effective turbulence inside large wind farms and the equivalent loads are examined.

  2. 79. COVERED CONDUIT ACROSS ANTELOPE VALLEY WITH WIND FARM IN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    79. COVERED CONDUIT ACROSS ANTELOPE VALLEY WITH WIND FARM IN DISTANCE - Los Angeles Aqueduct, From Lee Vining Intake (Mammoth Lakes) to Van Norman Reservoir Complex (San Fernando Valley), Los Angeles, Los Angeles County, CA

  3. Regional Offshore Wind Farm Optimization Using Wind Climatology and the Weather Research and Forecasting Model

    NASA Astrophysics Data System (ADS)

    Veron, D. E.; Brodie, J. F.; Archer, C. L.; Veron, F.

    2014-12-01

    The impact of turbulent wakes on the power production of wind farms is a very active area of research as society continues to increase its commitment to renewable energy. The areas offshore of the mid-Atlantic and northeast states are highly favorable to the development of offshore wind farms, and determining the optimal layout for these wind farms is key to their success. We utilize the Weather Research and Forecasting (WRF) model to study the influence of wake effects from different wind farm array geometries on the power production of each farm. Using an idealized version of WRF, we are able to use the wind climatology from a NOAA observational buoy near the Delaware Wind Energy Area (WEA) to evaluate the potential wind farm performance during a climatological average year. We then extend these techniques on a regional scale, evaluating performance of farms located in different offshore WEAs. Finally, by using WRF to model the entire region, we evaluate the wind farms' interactions with one another under various meteorological scenarios in order to account for seasonal wind variability and load requirements.

  4. Numerical simulations of flow fields through conventionally controlled wind turbines & wind farms

    NASA Astrophysics Data System (ADS)

    Emre Yilmaz, Ali; Meyers, Johan

    2014-06-01

    In the current study, an Actuator-Line Model (ALM) is implemented in our in-house pseudo-spectral LES solver SP-WIND, including a turbine controller. Below rated wind speed, turbines are controlled by a standard-torque-controller aiming at maximum power extraction from the wind. Above rated wind speed, the extracted power is limited by a blade pitch controller which is based on a proportional-integral type control algorithm. This model is used to perform a series of single turbine and wind farm simulations using the NREL 5MW turbine. First of all, we focus on below-rated wind speed, and investigate the effect of the farm layout on the controller calibration curves. These calibration curves are expressed in terms of nondimensional torque and rotational speed, using the mean turbine-disk velocity as reference. We show that this normalization leads to calibration curves that are independent of wind speed, but the calibration curves do depend on the farm layout, in particular for tightly spaced farms. Compared to turbines in a lone-standing set-up, turbines in a farm experience a different wind distribution over the rotor due to the farm boundary-layer interaction. We demonstrate this for fully developed wind-farm boundary layers with aligned turbine arrangements at different spacings (5D, 7D, 9D). Further we also compare calibration curves obtained from full farm simulations with calibration curves that can be obtained at a much lower cost using a minimal flow unit.

  5. Dynamic Federalism and Wind Farm Siting

    DTIC Science & Technology

    2014-05-18

    drawbacks, however. Among these, the mechanical and electromagnetic properties of wind turbines pose significant hazards and complications to U.S...have drawbacks, however. Among these, the mechanical and electromagnetic properties of wind turbines pose significant hazards and complications to...benefits. Wind energy conversion systems are no exception. Wind power systems use elevated turbines to capture mechanical energy from the wind

  6. Wind farm induced changes in wind speed and surface fluxes over the North Sea

    NASA Astrophysics Data System (ADS)

    Chatterjee, Fabien; van Lipzig, Nicole; Meyers, Johan

    2016-04-01

    Offshore wind farm deployment in the North Sea is foreseen to expand dramatically in the coming years. The strong expansion of offshore wind parks is likely to affect the regional climatology on the North Sea. We assess this impact by conducting a regional climate model simulation over future wind farms built near the German coast. In order to achieve this, the wind farm parameterisation of Fitch et al. 2012, where wind farms are parameterised as elevated sources of turbulent kinetic energy and sinks of momentum ( Blahak et al 2010 and Fitch et al 2012) is implemented in COSMO-CLM at a 1.5 km resolution. As a first step, COSMO-CLM's ability to reproduce wind profiles over the North Sea is evaluated using wind speed data from the FINO1 meteorological mast, toghether with QuikScat scatterometer data, for a time period of 2000-2008. Subsequently, the impact of windfarms on the regional climate over a period of ten years (1999-2008) is assessed. A large scale wind farm can create wakes which depending on the wind direction could affect the power production of a neighbouring farm. Furthermore, wind farms decelerate the flow and create a vertical circulation in the inflow region. As a result, changes in vertical fluxes of moisture are observed. This leads to enhanced low level cloud cover which may trigger changes in precipitation.

  7. Analysis on Lightning Surge Propagation in Wind Farm

    NASA Astrophysics Data System (ADS)

    Yasuda, Yoh; Hara, Takehisa; Funabashi, Toshihisa

    Wind power generation is expected to become more important in the future distribution system. Although several prospective reports such as IEC 61400-24 and NREL SR-500-31115 indicate on insulation scheme and grounding design for lightning protection, it still seems that there are not many investigations on the problems. This paper therefore discusses lightning surge analysis using wind farm model with 2 or 10 ideal wind turbines. Changing parameters such as grounding resistance and lightning strike points, several cases were studied. As the result of the analysis using digital simulator ARENE, it is clear that the surge tends to propagate toward the end of a distribution line in a wind farm and there is possibility of insulation accidents at the other wind turbines when lightning attacks a wind turbine.

  8. DOE/SNL-TTU scaled wind farm technology facility :

    SciTech Connect

    Barone, Matthew Franklin; White, Jonathan

    2011-09-01

    The proposed DOE/Sandia Scaled Wind Farm Technology Facility (SWiFT) hosted by Texas Tech University at Reese Technology Center in Lubbock, TX, will provide a facility for experimental study of turbine-turbine interaction and complex wind farm aerodynamics. This document surveys the current status of wind turbine wake and turbine-turbine interaction research, identifying knowledge and data gaps that the proposed test site can potentially fill. A number of turbine layouts is proposed, allowing for up to ten turbines at the site.

  9. Use of meteorological information in the risk analysis of a mixed wind farm and solar

    NASA Astrophysics Data System (ADS)

    Mengelkamp, H.-T.; Bendel, D.

    2010-09-01

    Use of meteorological information in the risk analysis of a mixed wind farm and solar power plant portfolio H.-T. Mengelkamp*,** , D. Bendel** *GKSS Research Center Geesthacht GmbH **anemos Gesellschaft für Umweltmeteorologie mbH The renewable energy industry has rapidly developed during the last two decades and so have the needs for high quality comprehensive meteorological services. It is, however, only recently that international financial institutions bundle wind farms and solar power plants and offer shares in these aggregate portfolios. The monetary value of a mixed wind farm and solar power plant portfolio is determined by legal and technical aspects, the expected annual energy production of each wind farm and solar power plant and the associated uncertainty of the energy yield estimation or the investment risk. Building an aggregate portfolio will reduce the overall uncertainty through diversification in contrast to the single wind farm/solar power plant energy yield uncertainty. This is similar to equity funds based on a variety of companies or products. Meteorological aspects contribute to the diversification in various ways. There is the uncertainty in the estimation of the expected long-term mean energy production of the wind and solar power plants. Different components of uncertainty have to be considered depending on whether the power plant is already in operation or in the planning phase. The uncertainty related to a wind farm in the planning phase comprises the methodology of the wind potential estimation and the uncertainty of the site specific wind turbine power curve as well as the uncertainty of the wind farm effect calculation. The uncertainty related to a solar power plant in the pre-operational phase comprises the uncertainty of the radiation data base and that of the performance curve. The long-term mean annual energy yield of operational wind farms and solar power plants is estimated on the basis of the actual energy production and it

  10. Assessing Wind Farm Reliability Using Weather Dependent Failure Rates

    NASA Astrophysics Data System (ADS)

    Wilson, G.; McMillan, D.

    2014-06-01

    Using reliability data comprising of two modern, large scale wind farm sites and wind data from two onsite met masts, a model is developed which calculates wind speed dependant failure rates which are used to populate a Markov Chain. Monte Carlo simulation is then exercised to simulate three wind farms which are subjected to controlled wind speed conditions from three separate potential UK sites. The model then calculates and compares wind farm reliability due to corrective maintenance and component failure rates influenced by the wind speed of each of the sites. Results show that the components affected most by changes in average daily wind speed are the control system and the yaw system. A comparison between this model and a more simple estimation of site yield is undertaken. The model takes into account the effects of the wind speed on the cost of operation and maintenance and also includes the impact of longer periods of downtime in the winter months and shorter periods in the summer. By taking these factors into account a more detailed site assessment can be undertaken. There is significant value to this model for operators and manufacturers.

  11. Prospects for generating electricity by large onshore and offshore wind farms

    NASA Astrophysics Data System (ADS)

    Volker, Patrick J. H.; Hahmann, Andrea N.; Badger, Jake; Jørgensen, Hans E.

    2017-03-01

    The decarbonisation of energy sources requires additional investments in renewable technologies, including the installation of onshore and offshore wind farms. For wind energy to remain competitive, wind farms must continue to provide low-cost power even when covering larger areas. Inside very large wind farms, winds can decrease considerably from their free-stream values to a point where an equilibrium wind speed is reached. The magnitude of this equilibrium wind speed is primarily dependent on the balance between turbine drag force and the downward momentum influx from above the wind farm. We have simulated for neutral atmospheric conditions, the wind speed field inside different wind farms that range from small (25 km2) to very large (105 km2) in three regions with distinct wind speed and roughness conditions. Our results show that the power density of very large wind farms depends on the local free-stream wind speed, the surface characteristics, and the turbine density. In onshore regions with moderate winds the power density of very large wind farms reaches 1 W m‑2, whereas in offshore regions with very strong winds it exceeds 3 W m‑2. Despite a relatively low power density, onshore regions with moderate winds offer potential locations for very large wind farms. In offshore regions, clusters of smaller wind farms are generally preferable; under very strong winds also very large offshore wind farms become efficient.

  12. Wake Mitigation Strategies for Optimizing Wind Farm Power Production

    NASA Astrophysics Data System (ADS)

    Dilip, Deepu; Porté-Agel, Fernando

    2016-04-01

    Although wind turbines are designed individually for optimum power production, they are often arranged into groups of closely spaced turbines in a wind farm rather than in isolation. Consequently, most turbines in a wind farm do not operate in unobstructed wind flows, but are affected by the wakes of turbines in front of them. Such wake interference significantly reduces the overall power generation from wind farms and hence, development of effective wake mitigation strategies is critical for improving wind farm efficiency. One approach towards this end is based on the notion that the operation of each turbine in a wind farm at its optimum efficiency might not lead to optimum power generation from the wind farm as a whole. This entails a down regulation of individual turbines from its optimum operating point, which can be achieved through different methods such as pitching the turbine blades, changing the turbine tip speed ratio or yawing of the turbine, to name a few. In this study, large-eddy simulations of a two-turbine arrangement with the second turbine fully in the wake of the first are performed. Different wake mitigation techniques are applied to the upstream turbine, and the effects of these on its wake characteristics are investigated. Results for the combined power from the two turbines for each of these methods are compared to a baseline scenario where no wake mitigation strategies are employed. Analysis of the results shows the potential for improved power production from such wake control methods. It should be noted, however, that the magnitude of the improvement is strongly affected by the level of turbulence in the incoming atmospheric flow.

  13. Adjustment of mean velocity and turbulence due to a finite-size wind farm in a neutral ABL - A LES study

    NASA Astrophysics Data System (ADS)

    Sharma, Varun; Parlange, Marc B.; Calaf, Marc

    2015-11-01

    Large-eddy simulation (LES) has become a well-established tool to simulate and understand the interaction between wind farms and the atmospheric boundary layer (ABL). A popular simulation technique considers wind turbines as actuator disks and simulates `infinite' wind farms due to periodic boundary conditions in the horizontal directions. These simulations have indicated the presence of a fully developed internal boundary layer (IBL) due to `wind farm roughness', which has been shown to have important implications, especially in stratified flow conditions. However, the relationship between the length of the wind farm and the resulting IBL vis-à-vis the asymptotic IBL and its relevance in real-world wind farms is not well understood at present. To address this issue, simulations of wind farms with different horizontal extents are performed in a neutral ABL using an extremely elongated computational domain. Results focus on identifying length scales defining the adjustment of the ABL to a new equilibrium within the wind farm and comparing it to the infinite wind farm case. Furthermore, analyses shall be extended upstream as well as downstream of the wind farm to determine the `impact' region and the `exit' region of the wind farm.

  14. Onshore wind farm modelling using high performance computing

    NASA Astrophysics Data System (ADS)

    Folch, A.; Avila, M.; Houzeaux, G.; Egukitza, B.; Prieto, L.

    2013-12-01

    Numerical modelling has become a basic tool for the design and exploitation of wind energy resources. The Barcelona Supercomputing Center, the national supercomputing facility in Spain, and Iberdrola Renovables S.A., an industry world leader in the sector, are working in close cooperation in the development of a Computational Fluid Dynamics (CFD) wind farm modelling strategy in the frame of high performance computing. The first objective is to optimize the design of wind farms using a k-e turbulence model specially designed for atmospheric flow in complex terrains. An actuator disk model is used to account for the wake effects of wind turbines that, for optimization of farm design, are placed using a chimera method. The model has been implemented in Alya, a multi-physics parallel code specially designed for massive parallel execution. The second objective, yet under development, is the short-term forecast of wind farm production considering a nest-down from mesoscale numerical weather prediction models to CFD in order to obtain high-resolution hourly wind fields.

  15. A wake detector for wind farm control

    NASA Astrophysics Data System (ADS)

    Bottasso, C. L.; Cacciola, S.; Schreiber, J.

    2015-06-01

    The paper describes an observer capable of detecting the impingement on a wind turbine rotor of the wake of an upstream machine. The observer estimates the local wind speed and turbulence intensity on the left and right parts of the rotor disk. The estimation is performed based on blade loads measured by strain gages or optical fibers, sensors which are becoming standard equipment on many modern machines. A lower wind speed and higher turbulence intensity on one part of the rotor, possibly in conjunction with other information, can then be used to infer the presence of a wake impinging on the disk. The wake state information is useful for wind plant control strategies, as for example wake deflection by active yawing. In addition, the local wind speed estimates may be used for a rough evaluation of the vertical wind shear.

  16. Avian collision risk at an offshore wind farm

    PubMed Central

    Desholm, Mark; Kahlert, Johnny

    2005-01-01

    We have been the first to investigate whether long-lived geese and ducks can detect and avoid a large offshore wind farm by tracking their diurnal migration patterns with radar. We found that the percentage of flocks entering the wind farm area decreased significantly (by a factor 4.5) from pre-construction to initial operation. At night, migrating flocks were more prone to enter the wind farm but counteracted the higher risk of collision in the dark by increasing their distance from individual turbines and flying in the corridors between turbines. Overall, less than 1% of the ducks and geese migrated close enough to the turbines to be at any risk of collision. PMID:17148191

  17. Mapping surface disturbance from wind farms

    NASA Astrophysics Data System (ADS)

    Diffendorfer, James E.

    2013-04-01

    Wind energy is one of the fastest growing segments of the electricity market and this trend will likely continue as countries strive to reduce CO2 production while meeting growing energy demands. One impact of wind facilities is surface disturbance, including roads, that lead to habitat loss and fragmentation. Numerous studies of wind power utilize estimates of surface disturbance for GIS-based modeling or basic calculations of the land area required to generate energy using wind. However published estimates of the land use required for a MW of electricity from wind facilities vary by more than 10 times (0.83 to 250 MW/Km2). We report results from a geospatial analysis of 39 wind facilities in the United States that we fully digitized using high resolution photo-imagery. The selected sites and analyses were designed to elucidate the effects of turbine size, topography, and land use on the area requirements of wind facilities. The results indicate point estimates of average surface disturbance/MW have wide levels of variation, explained primarily by Landcover and Topography. Wind facilities in agricultural landscapes had smaller surface disturbance/ha than facilities in forests and shrublands, and facilities in relatively flat topography had smaller surface disturbance/ha than facilities on hills, ridges, or mesas. Land use, topography, and turbine size all influenced turbine spacing. The statistical models suggest we can predict geographic locations where new wind facilities could be placed with minimized surface disturbance.

  18. Introduction Wind farms in complex terrains: an introduction

    PubMed Central

    Alfredsson, P. H.; Segalini, A.

    2017-01-01

    Wind energy is one of the fastest growing sources of sustainable energy production. As more wind turbines are coming into operation, the best locations are already becoming occupied by turbines, and wind-farm developers have to look for new and still available areas—locations that may not be ideal such as complex terrain landscapes. In these locations, turbulence and wind shear are higher, and in general wind conditions are harder to predict. Also, the modelling of the wakes behind the turbines is more complicated, which makes energy-yield estimates more uncertain than under ideal conditions. This theme issue includes 10 research papers devoted to various fluid-mechanics aspects of using wind energy in complex terrains and illustrates recent progress and future developments in this important field. This article is part of the themed issue ‘Wind energy in complex terrains’. PMID:28265020

  19. Introduction Wind farms in complex terrains: an introduction.

    PubMed

    Alfredsson, P H; Segalini, A

    2017-04-13

    Wind energy is one of the fastest growing sources of sustainable energy production. As more wind turbines are coming into operation, the best locations are already becoming occupied by turbines, and wind-farm developers have to look for new and still available areas-locations that may not be ideal such as complex terrain landscapes. In these locations, turbulence and wind shear are higher, and in general wind conditions are harder to predict. Also, the modelling of the wakes behind the turbines is more complicated, which makes energy-yield estimates more uncertain than under ideal conditions. This theme issue includes 10 research papers devoted to various fluid-mechanics aspects of using wind energy in complex terrains and illustrates recent progress and future developments in this important field.This article is part of the themed issue 'Wind energy in complex terrains'.

  20. Simulation and optimal control of wind-farm boundary layers

    NASA Astrophysics Data System (ADS)

    Meyers, Johan; Goit, Jay

    2014-05-01

    In large wind farms, the effect of turbine wakes, and their interaction leads to a reduction in farm efficiency, with power generated by turbines in a farm being lower than that of a lone-standing turbine by up to 50%. In very large wind farms or `deep arrays', this efficiency loss is related to interaction of the wind farms with the planetary boundary layer, leading to lower wind speeds at turbine level. Moreover, for these cases it has been demonstrated both in simulations and wind-tunnel experiments that the wind-farm energy extraction is dominated by the vertical turbulent transport of kinetic energy from higher regions in the boundary layer towards the turbine level. In the current study, we investigate the use of optimal control techniques combined with Large-Eddy Simulations (LES) of wind-farm boundary layer interaction for the increase of total energy extraction in very large `infinite' wind farms. We consider the individual wind turbines as flow actuators, whose energy extraction can be dynamically regulated in time so as to optimally influence the turbulent flow field, maximizing the wind farm power. For the simulation of wind-farm boundary layers we use large-eddy simulations in combination with actuator-disk and actuator-line representations of wind turbines. Simulations are performed in our in-house pseudo-spectral code SP-Wind that combines Fourier-spectral discretization in horizontal directions with a fourth-order finite-volume approach in the vertical direction. For the optimal control study, we consider the dynamic control of turbine-thrust coefficients in an actuator-disk model. They represent the effect of turbine blades that can actively pitch in time, changing the lift- and drag coefficients of the turbine blades. Optimal model-predictive control (or optimal receding horizon control) is used, where the model simply consists of the full LES equations, and the time horizon is approximately 280 seconds. The optimization is performed using a

  1. Offshore wind turbine foundation monitoring, extrapolating fatigue measurements from fleet leaders to the entire wind farm

    NASA Astrophysics Data System (ADS)

    Weijtens, Wout; Noppe, Nymfa; Verbelen, Tim; Iliopoulos, Alexandros; Devriendt, Christof

    2016-09-01

    The present contribution is part of the ongoing development of a fatigue assessment strategy driven purely on in-situ measurements on operational wind turbines. The primary objective is to estimate the remaining life time of existing wind farms and individual turbines by instrumenting part of the farm with a load monitoring setup. This load monitoring setup allows to measure interface loads and local stress histories. This contribution will briefly discuss how these load measurements can be translated into fatigue assessment of the instrumented turbine. However, due to different conditions at the wind farm, such as turbulence, differences in water depth and foundation design this turbine will not be fully representable for all turbines in the farm. In this paper we will use the load measurements on two offshore wind turbines in the Northwind offshore wind farm to discuss fatigue progression in an operational wind farm. By calculating the damage equivalent loads on the two turbines the fatigue progression is quantified for every 10 minute interval and can be analyzed against turbulence and site conditions. In future work these results will be used to predict the fatigue life progression in the entire farm.

  2. Numerical study of ocean wave effect on offshore wind farm

    NASA Astrophysics Data System (ADS)

    Shen, Lian; Yang, Di; Meneveau, Charles

    2013-11-01

    Wind power at sea has become increasingly important in renewable energy study. For energy harvesting, winds over oceans have many advantages over winds on land, for example, larger and open surface area, faster wind speed, and more wind resource close to high population regions. On the other hand, the presence of ocean waves introduces complexities to wind turbines. There is a critical need to study the dynamical interactions among marine atmospheric boundary layer, ocean wave field, and floating turbines. In this research, we study offshore wind farm by performing large-eddy simulations for winds coupled with potential-flow-theory based simulations for broadband irregular waves, with the wind turbines represented by an actuator disk model. Our results show that windseas at different development stages result in different sea-surface roughness and have an appreciable effect on wind profile and the energy extraction rate of the turbines. If swells are present, swell-to-wind momentum and energy transfer further changes the wind field to introduce oscillations in as well as modify the mean of the wind power. DY and LS acknowledge the support of NSF-CBET-1341062. CM acknowledges the support of NSF-AGS-1045189 and NSF-OISE-1243482.

  3. Avian sensitivity to mortality: prioritising migratory bird species for assessment at proposed wind farms.

    PubMed

    Desholm, Mark

    2009-06-01

    Wind power generation is likely to constitute one of the most extensive human physical exploitation activities of European marine areas in the near future. The many millions of migrating birds that pass these man-made obstacles are protected by international obligations and the subject of public concerns. Yet some bird species are more sensitive to bird-wind turbine mortality than others. This study developed a simple and logical framework for ranking bird species with regard to their relative sensitivity to bird-wind turbine-collisions, and applied it to a data set comprising 38 avian migrant species at the Nysted offshore wind farm in Denmark. Two indicators were selected to characterize the sensitivity of each individual species: 1) relative abundance and 2) demographic sensitivity (elasticity of population growth rate to changes in adult survival). In the case-study from the Nysted offshore wind farm, birds of prey and waterbirds dominated the group of high priority species and only passerines showed a low risk of being impacted by the wind farm. Even where passerines might be present in very high numbers, they often represent insignificant segments of huge reference populations that, from a demographic point of view, are relatively insensitive to wind farm-related adult mortality. It will always be important to focus attention and direct the resources towards the most sensitive species to ensure cost-effective environmental assessments in the future, and in general, this novel index seems capable of identifying the species that are at high risk of being adversely affected by wind farms.

  4. Observed Thermal Impacts of Wind Farms Over Northern Illinois.

    PubMed

    Slawsky, Lauren M; Zhou, Liming; Baidya Roy, Somnath; Xia, Geng; Vuille, Mathias; Harris, Ronald A

    2015-06-25

    This paper assesses impacts of three wind farms in northern Illinois using land surface temperature (LST) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments onboard the Terra and Aqua satellites for the period 2003-2013. Changes in LST between two periods (before and after construction of the wind turbines) and between wind farm pixels and nearby non-wind-farm pixels are quantified. An areal mean increase in LST by 0.18-0.39 °C is observed at nighttime over the wind farms, with the geographic distribution of this warming effect generally spatially coupled with the layout of the wind turbines (referred to as the spatial coupling), while there is no apparent impact on daytime LST. The nighttime LST warming effect varies with seasons, with the strongest warming in winter months of December-February, and the tightest spatial coupling in summer months of June-August. Analysis of seasonal variations in wind speed and direction from weather balloon sounding data and Automated Surface Observing System hourly observations from nearby stations suggest stronger winds correspond to seasons with greater warming and larger downwind impacts. The early morning soundings in Illinois are representative of the nighttime boundary layer and exhibit strong temperature inversions across all seasons. The strong and relatively shallow inversion in summer leaves warm air readily available to be mixed down and spatially well coupled with the turbine. Although the warming effect is strongest in winter, the spatial coupling is more erratic and spread out than in summer. These results suggest that the observed warming signal at nighttime is likely due to the net downward transport of heat from warmer air aloft to the surface, caused by the turbulent mixing in the wakes of the spinning turbine rotor blades.

  5. Observed Thermal Impacts of Wind Farms Over Northern Illinois

    PubMed Central

    Slawsky, Lauren M.; Zhou, Liming; Baidya Roy, Somnath; Xia, Geng; Vuille, Mathias; Harris, Ronald A.

    2015-01-01

    This paper assesses impacts of three wind farms in northern Illinois using land surface temperature (LST) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments onboard the Terra and Aqua satellites for the period 2003–2013. Changes in LST between two periods (before and after construction of the wind turbines) and between wind farm pixels and nearby non-wind-farm pixels are quantified. An areal mean increase in LST by 0.18–0.39 °C is observed at nighttime over the wind farms, with the geographic distribution of this warming effect generally spatially coupled with the layout of the wind turbines (referred to as the spatial coupling), while there is no apparent impact on daytime LST. The nighttime LST warming effect varies with seasons, with the strongest warming in winter months of December-February, and the tightest spatial coupling in summer months of June-August. Analysis of seasonal variations in wind speed and direction from weather balloon sounding data and Automated Surface Observing System hourly observations from nearby stations suggest stronger winds correspond to seasons with greater warming and larger downwind impacts. The early morning soundings in Illinois are representative of the nighttime boundary layer and exhibit strong temperature inversions across all seasons. The strong and relatively shallow inversion in summer leaves warm air readily available to be mixed down and spatially well coupled with the turbine. Although the warming effect is strongest in winter, the spatial coupling is more erratic and spread out than in summer. These results suggest that the observed warming signal at nighttime is likely due to the net downward transport of heat from warmer air aloft to the surface, caused by the turbulent mixing in the wakes of the spinning turbine rotor blades. PMID:26121613

  6. Two-scale momentum theory for very large wind farms

    NASA Astrophysics Data System (ADS)

    Nishino, Takafumi

    2016-09-01

    A new theoretical approach is proposed to predict a practical upper limit to the efficiency of a very large wind farm. The new theory suggests that the efficiency of ideal turbines in an ideal very large wind farm depends primarily on a non-dimensional parameter λ/Cf0, where λ is the ratio of the rotor swept area to the land area (for each turbine) and Cf0 is a natural friction coefficient observed before constructing the farm. When X/Cf approaches to zero, the new theory goes back to the classical actuator disc theory, yielding the well-known Betz limit. When λ/Cf0 increases to a large value, the maximum power coefficient of each turbine reduces whilst a normalised power density of the farm increases asymptotically to an upper limit. A CFD analysis of an infinitely large wind farm with ‘aligned’ and ‘displaced’ array configurations is also presented to validate a key assumption used in the new theory.

  7. Wind tunnel measurements of wake structure and wind farm power for actuator disk model wind turbines in yaw

    NASA Astrophysics Data System (ADS)

    Howland, Michael; Bossuyt, Juliaan; Kang, Justin; Meyers, Johan; Meneveau, Charles

    2016-11-01

    Reducing wake losses in wind farms by deflecting the wakes through turbine yawing has been shown to be a feasible wind farm control approach. In this work, the deflection and morphology of wakes behind a wind turbine operating in yawed conditions are studied using wind tunnel experiments of a wind turbine modeled as a porous disk in a uniform inflow. First, by measuring velocity distributions at various downstream positions and comparing with prior studies, we confirm that the nonrotating wind turbine model in yaw generates realistic wake deflections. Second, we characterize the wake shape and make observations of what is termed a "curled wake," displaying significant spanwise asymmetry. Through the use of a 100 porous disk micro-wind farm, total wind farm power output is studied for a variety of yaw configurations. Strain gages on the tower of the porous disk models are used to measure the thrust force as a substitute for turbine power. The frequency response of these measurements goes up to the natural frequency of the model and allows studying the spatiotemporal characteristics of the power output under the effects of yawing. This work has been funded by the National Science Foundation (Grants CBET-113380 and IIA-1243482, the WINDINSPIRE project). JB and JM are supported by ERC (ActiveWindFarms, Grant No. 306471).

  8. Residents' Perceptions toward Utility-Scale Wind Farm Development

    ERIC Educational Resources Information Center

    Campbell, Joseph; Romich, Eric

    2015-01-01

    Increased development of wind farms in the U.S. has fostered debates surrounding the siting and support for the projects. Prior research demonstrates the importance of understanding the attitudes and opinions of community members when developing projects. This article reviews a case study of an Ohio community that integrated a local survey to…

  9. Assessing vulnerability of marine bird populations to offshore wind farms.

    PubMed

    Furness, Robert W; Wade, Helen M; Masden, Elizabeth A

    2013-04-15

    Offshore wind farms may affect bird populations through collision mortality and displacement. Given the pressures to develop offshore wind farms, there is an urgent need to assess population-level impacts on protected marine birds. Here we refine an approach to assess aspects of their ecology that influence population vulnerability to wind farm impacts, also taking into account the conservation importance of each species. Flight height appears to be a key factor influencing collision mortality risk but improved data on flight heights of marine birds are needed. Collision index calculations identify populations of gulls, white-tailed eagles, northern gannets and skuas as of particularly high concern in Scottish waters. Displacement index calculations identify populations of divers and common scoters as most vulnerable to population-level impacts of displacement, but these are likely to be less evident than impacts of collision mortality. The collision and displacement indices developed here for Scottish marine bird populations could be applied to populations elsewhere, and this approach will help in identifying likely impacts of future offshore wind farms on marine birds and prioritising monitoring programmes, at least until data on macro-avoidance rates become available.

  10. Linearized simulation of flow over wind farms and complex terrains.

    PubMed

    Segalini, Antonio

    2017-04-13

    The flow over complex terrains and wind farms is estimated here by numerically solving the linearized Navier-Stokes equations. The equations are linearized around the unperturbed incoming wind profile, here assumed logarithmic. The Boussinesq approximation is used to model the Reynolds stress with a prescribed turbulent eddy viscosity profile. Without requiring the boundary-layer approximation, two new linear equations are obtained for the vertical velocity and the wall-normal vorticity, with a reduction in the computational cost by a factor of 8 when compared with a primitive-variables formulation. The presence of terrain elevation is introduced as a vertical coordinate shift, while forestry or wind turbines are included as body forces, without any assumption about the wake structure for the turbines. The model is first validated against some available experiments and simulations, and then a simulation of a wind farm over a Gaussian hill is performed. The speed-up effect of the hill is clearly beneficial in terms of the available momentum upstream of the crest, while downstream of it the opposite can be said as the turbines face a decreased wind speed. Also, the presence of the hill introduces an additional spanwise velocity component that may also affect the turbines' operations. The linear superposition of the flow over the hill and the flow over the farm alone provided a first estimation of the wind speed along the farm, with discrepancies of the same order of magnitude for the spanwise velocity. Finally, the possibility of using a parabolic set of equations to obtain the turbulent kinetic energy after the linearized model is investigated with promising results.This article is part of the themed issue 'Wind energy in complex terrains'.

  11. 75 FR 23666 - Huron-Manistee National Forests, White Pines Wind Farm Project, Mason County, MI

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-04

    ... Forest Service Huron-Manistee National Forests, White Pines Wind Farm Project, Mason County, MI AGENCY... Pines Wind Farm Project on National Forest System (NFS) lands managed by the Huron-Manistee National... process for the White Pines Wind Farm Project. DATES: The Notice of Intent to prepare the White Pines...

  12. Optimization of wind farm performance using low-order models

    NASA Astrophysics Data System (ADS)

    Dabiri, John; Brownstein, Ian

    2015-11-01

    A low order model that captures the dominant flow behaviors in a vertical-axis wind turbine (VAWT) array is used to maximize the power output of wind farms utilizing VAWTs. The leaky Rankine body model (LRB) was shown by Araya et al. (JRSE 2014) to predict the ranking of individual turbine performances in an array to within measurement uncertainty as compared to field data collected from full-scale VAWTs. Further, this model is able to predict array performance with significantly less computational expense than higher fidelity numerical simulations of the flow, making it ideal for use in optimization of wind farm performance. This presentation will explore the ability of the LRB model to rank the relative power output of different wind turbine array configurations as well as the ranking of individual array performance over a variety of wind directions, using various complex configurations tested in the field and simpler configurations tested in a wind tunnel. Results will be presented in which the model is used to determine array fitness in an evolutionary algorithm seeking to find optimal array configurations given a number of turbines, area of available land, and site wind direction profile. Comparison with field measurements will be presented.

  13. Simulation of wake effects between two wind farms

    NASA Astrophysics Data System (ADS)

    Hansen, K. S.; Réthoré, P.-E.; Palma, J.; Hevia, B. G.; Prospathopoulos, J.; Peña, A.; Ott, S.; Schepers, G.; Palomares, A.; van der Laan, M. P.; Volker, P.

    2015-06-01

    SCADA data, recorded on the downstream wind farm, has been used to identify flow cases with visible clustering effects. The inflow condition is derived from a partly undisturbed wind turbine, due to lack of mast measurements. The SCADA data analysis concludes that centre of the deficit for the downstream wind farm with disturbed inflow has a distinct visible maximum deficit zone located only 5-10D downstream from the entrance. This zone, representing 20-30% speed reduction, increases and moves downstream for increasing cluster effect and is not visible outside a flow sector of 20-30°. The eight flow models represented in this benchmark include both RANS models, mesoscale models and engineering models. The flow cases, identified according to the wind speed level and inflow sector, have been simulated and validated with the SCADA results. The model validation concludes that all models more or less are able to predict the location and size of the deficit zone inside the downwind wind farm.

  14. Modeling velocity space-time correlations in wind farms

    NASA Astrophysics Data System (ADS)

    Lukassen, Laura J.; Stevens, Richard J. A. M.; Meneveau, Charles; Wilczek, Michael

    2016-11-01

    Turbulent fluctuations of wind velocities cause power-output fluctuations in wind farms. The statistics of velocity fluctuations can be described by velocity space-time correlations in the atmospheric boundary layer. In this context, it is important to derive simple physics-based models. The so-called Tennekes-Kraichnan random sweeping hypothesis states that small-scale velocity fluctuations are passively advected by large-scale velocity perturbations in a random fashion. In the present work, this hypothesis is used with an additional mean wind velocity to derive a model for the spatial and temporal decorrelation of velocities in wind farms. It turns out that in the framework of this model, space-time correlations are a convolution of the spatial correlation function with a temporal decorrelation kernel. In this presentation, first results on the comparison to large eddy simulations will be presented and the potential of the approach to characterize power output fluctuations of wind farms will be discussed. Acknowledgements: 'Fellowships for Young Energy Scientists' (YES!) of FOM, the US National Science Foundation Grant IIA 1243482, and support by the Max Planck Society.

  15. Wind tunnel study of the power output spectrum in a micro wind farm

    NASA Astrophysics Data System (ADS)

    Bossuyt, Juliaan; Howland, Michael F.; Meneveau, Charles; Meyers, Johan

    2016-09-01

    Instrumented small-scale porous disk models are used to study the spectrum of a surrogate for the power output in a micro wind farm with 100 models of wind turbines. The power spectra of individual porous disk models in the first row of the wind farm show the expected -5/3 power law at higher frequencies. Downstream models measure an increased variance due to wake effects. Conversely, the power spectrum of the sum of the power over the entire wind farm shows a peak at the turbine-to-turbine travel frequency between the model turbines, and a near -5/3 power law region at a much wider range of lower frequencies, confirming previous LES results. Comparison with the spectrum that would result when assuming that the signals are uncorrelated, highlights the strong effects of correlations and anti-correlations in the fluctuations at various frequencies.

  16. Could Crop Height Affect the Wind Resource at Agriculturally Productive Wind Farm Sites?

    NASA Astrophysics Data System (ADS)

    Vanderwende, Brian; Lundquist, Julie K.

    2016-03-01

    The collocation of cropland and wind turbines in the US Midwest region introduces complex meteorological interactions that could influence both agriculture and wind-power production. Crop management practices may affect the wind resource through alterations of land-surface properties. We use the weather research and forecasting (WRF) model to estimate the impact of crop height variations on the wind resource in the presence of a large turbine array. A hypothetical wind farm consisting of 121 1.8-MW turbines is represented using the WRF model wind-farm parametrization. We represent the impact of selecting soybeans rather than maize by altering the aerodynamic roughness length in a region approximately 65 times larger than that occupied by the turbine array. Roughness lengths of 0.1 and 0.25 m represent the mature soy crop and a mature maize crop, respectively. In all but the most stable atmospheric conditions, statistically significant hub-height wind-speed increases and rotor-layer wind-shear reductions result from switching from maize to soybeans. Based on simulations for the entire month of August 2013, wind-farm energy output increases by 14 %, which would yield a significant monetary gain. Further investigation is required to determine the optimal size, shape, and crop height of the roughness modification to maximize the economic benefit and minimize the cost of such crop-management practices. These considerations must be balanced by other influences on crop choice such as soil requirements and commodity prices.

  17. Could crop height affect the wind resource at agriculturally productive wind farm sites?

    SciTech Connect

    Vanderwende, Brian; Lundquist, Julie K.

    2015-11-07

    The collocation of cropland and wind turbines in the US Midwest region introduces complex meteorological interactions that could influence both agriculture and wind-power production. Crop management practices may affect the wind resource through alterations of land-surface properties. We use the weather research and forecasting (WRF) model to estimate the impact of crop height variations on the wind resource in the presence of a large turbine array. A hypothetical wind farm consisting of 121 1.8-MW turbines is represented using the WRF model wind-farm parametrization. We represent the impact of selecting soybeans rather than maize by altering the aerodynamic roughness length in a region approximately 65 times larger than that occupied by the turbine array. Roughness lengths of 0.1 and 0.25 m represent the mature soy crop and a mature maize crop, respectively. In all but the most stable atmospheric conditions, statistically significant hub-height wind-speed increases and rotor-layer wind-shear reductions result from switching from maize to soybeans. Based on simulations for the entire month of August 2013, wind-farm energy output increases by 14 %, which would yield a significant monetary gain. Further investigation is required to determine the optimal size, shape, and crop height of the roughness modification to maximize the economic benefit and minimize the cost of such crop-management practices. As a result, these considerations must be balanced by other influences on crop choice such as soil requirements and commodity prices.

  18. Optimization of rotating equipment in offshore wind farm

    NASA Astrophysics Data System (ADS)

    Okunade, O. A.

    2014-07-01

    The paper considered the improvement of rotating equipment in a wind farm, and how these could maximise the farm power capacity. It aimed to increase capacity of electricity generation through a renewable source in UK and contribute to 15 per cent energy- consumption target, set by EU on electricity through renewable sources by 2020. With reference to a case study in UK offshore wind farm, the paper analysed the critique of the farm, as a design basis for its optimization. It considered power production as design situation, load cases and constraints, in order to reflect characteristics and behaviour of a standard design. The scope, which considered parts that were directly involved in power generation, covered rotor blades and the impacts of gearbox and generator to power generation. The scope did not however cover support structures like tower design. The approaches of detail data analysis of the blade at typical wind load conditions, were supported by data from acceptable design standards, relevant authorities and professional bodies. The findings in proposed model design showed at least over 3 per cent improvement on the existing electricity generation. It also indicated overall effects on climate change.

  19. Spatiotemporal structure of wind farm-atmospheric boundary layer interactions

    NASA Astrophysics Data System (ADS)

    Cervarich, Matthew; Baidya Roy, Somnath; Zhou, Liming

    2013-04-01

    Wind power is currently one of the fastest growing energy sources in the world. Most of the growth is in the utility sector consisting of large wind farms with numerous industrial-scale wind turbines. Wind turbines act as a sink of mean kinetic energy and a source of turbulent kinetic energy in the atmospheric boundary layer (ABL). In doing so, they modify the ABL profiles and land-atmosphere exchanges of energy, momentum, mass and moisture. This project explores theses interactions using remote sensing data and numerical model simulations. The domain is central Texas where 4 of the world's largest wind farms are located. A companion study of seasonally-averaged Land Surface Temperature data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on TERRA and AQUA satellites shows a warming signal at night and a mixed cooling/warming signal during the daytime within the wind farms. In the present study, wind farm-ABL interactions are simulated with the Weather Research and Forecasting (WRF) model. The simulations show that the model is capable of replicating the observed signal in land surface temperature. Moreover, similar warming/cooling effect, up to 1C, was observed in seasonal mean 2m air temperature as well. Further analysis show that enhanced turbulent mixing in the rotor wakes is responsible for the impacts on 2m and surface air temperatures. The mixing is due to 2 reasons: (i) turbulent momentum transport to compensate the momentum deficit in the wakes of the turbines and (ii) turbulence generated due to motion of turbine rotors. Turbulent mixing also alters vertical profiles of moisture. Changes in land-atmosphere temperature and moisture gradient and increase in turbulent mixing leads to more than 10% change in seasonal mean surface sensible and latent heat flux. Given the current installed capacity and the projected installation across the world, wind farms are likely becoming a major driver of anthropogenic land use change on Earth. Hence

  20. MOD-2 wind turbine farm stability study

    NASA Technical Reports Server (NTRS)

    Hinrichsen, E. N.

    1980-01-01

    The dynamics of single and multiple 2.5 ME, Boeing MOD-2 wind turbine generators (WTGs) connected to utility power systems were investigated. The analysis was based on digital simulation. Both time response and frequency response methods were used. The dynamics of this type of WTG are characterized by two torsional modes, a low frequency 'shaft' mode below 1 Hz and an 'electrical' mode at 3-5 Hz. High turbine inertia and low torsional stiffness between turbine and generator are inherent features. Turbine control is based on electrical power, not turbine speed as in conventional utility turbine generators. Multi-machine dynamics differ very little from single machine dynamics.

  1. Control voltage and power fluctuations when connecting wind farms

    NASA Astrophysics Data System (ADS)

    Berinde, Ioan; Bǎlan, Horia; Oros Pop, Teodora Susana

    2015-12-01

    Voltage, frequency, active power and reactive power are very important parameters in terms of power quality. These parameters are followed when connecting any power plant, the more the connection of wind farms. Connecting wind farms to the electricity system must not cause interference outside the limits set by regulations. Modern solutions for fast and automatic voltage control and power fluctuations using electronic control systems of reactive power flows. FACTS (Flexible Alternating Current Transmision System) systems, established on the basis of power electronic circuits ensure control of electrical status quantities to achieve the necessary transfer of power to the power grid. FACTS devices can quickly control parameters and sizes of state power lines, such as impedance line voltages and phase angles of the voltages of the two ends of the line. Their use can lead to improvement in power system operation by increasing the transmission capacity of power lines, power flow control lines, improved static and transient stability reserve.

  2. Control voltage and power fluctuations when connecting wind farms

    SciTech Connect

    Berinde, Ioan Bălan, Horia Oros, Teodora Susana

    2015-12-23

    Voltage, frequency, active power and reactive power are very important parameters in terms of power quality. These parameters are followed when connecting any power plant, the more the connection of wind farms. Connecting wind farms to the electricity system must not cause interference outside the limits set by regulations. Modern solutions for fast and automatic voltage control and power fluctuations using electronic control systems of reactive power flows. FACTS (Flexible Alternating Current Transmision System) systems, established on the basis of power electronic circuits ensure control of electrical status quantities to achieve the necessary transfer of power to the power grid. FACTS devices can quickly control parameters and sizes of state power lines, such as impedance line voltages and phase angles of the voltages of the two ends of the line. Their use can lead to improvement in power system operation by increasing the transmission capacity of power lines, power flow control lines, improved static and transient stability reserve.

  3. Field test of wake steering at an offshore wind farm

    DOE PAGES

    Fleming, Paul; Annoni, Jennifer; Shah, Jigar J.; ...

    2017-02-06

    In this study, a field test of wake steering control is presented. The field test is the result of a collaboration between the National Renewable Energy Laboratory (NREL) and Envision Energy, a smart energy management company and turbine manufacturer. In the campaign, an array of turbines within an operating commercial offshore wind farm in China have the normal yaw controller modified to implement wake steering according to a yaw control strategy. The strategy was designed using NREL wind farm models, including a computational fluid dynamics model, SOWFA, for understanding wake dynamics and an engineering model, FLORIS, for yaw control optimization.more » Results indicate that, within the certainty afforded by the data, the wake-steering controller was successful in increasing power capture, by amounts similar to those predicted from the models.« less

  4. Short-term Wind Forecasting at Wind Farms located on Mountainous Terrains

    NASA Astrophysics Data System (ADS)

    Kirkil, Gokhan

    2016-04-01

    Power uncertainty and fluctuations are recognized as major challenges for expanding wind energy. Here we aim at better understanding and characterizing fluctuations in wind power caused by rapid changes in wind resource. By means of Large Eddy Simulations (LES), we expect to gain new knowledge about the sources of spatial and temporal variability of wind fluctuations such as different configurations of wind turbines and complex topography. We will present the recent progress on our LES simulations for a wind farm located near a mountainous terrain. We performed multi-scale simulations using WRF's different Planetary Boundary Layer (PBL) parameterizations as well as Large Eddy Simulation (LES). WRF ensembles with different PBL parameterizations showed little spread for wind speed forecasts. LES models improved the forecasts. Statistical error analysis is performed and ramp events are analyzed.

  5. A Predictive Model for Wind Farms Using Dynamic Mode Decomposition

    NASA Astrophysics Data System (ADS)

    Thomas, Vaughan; Meneveau, Charles; Gayme, Dennice

    2016-11-01

    In this work we extend traditional dynamic mode decomposition (DMD) to develop a linear predictive model for the time evolution of the velocity field for a multiple-turbine wind farm. Traditional DMD identifies a set of DMD modes which can be used to produce a linear system that approximates the dynamics of the original system. Typically, these DMD modes consist of those that both grow and decay, but in order to develop a predictive model we need a system that evolves along a manifold that neither grows nor decays. Here we modify the DMD calculation to build such a model. We then apply this method to three dimensional large eddy simulations (LES) of a multi-turbine wind farm. Our predictive wind farm model is initialized with a small time series of data independent of the original data used to create the system. When initialized in this manner our DMD based model can reproduce the subsequent time evolution of the velocity field over ten inter-turbine convective timescales with a gradual falloff in performance. This work is supported by the National Science Foundation (Grants ECCS-1230788 and OISE-1243482, the WINDINSPIRE project).

  6. Response to noise from modern wind farms in The Netherlands.

    PubMed

    Pedersen, Eja; van den Berg, Frits; Bakker, Roel; Bouma, Jelte

    2009-08-01

    The increasing number and size of wind farms call for more data on human response to wind turbine noise, so that a generalized dose-response relationship can be modeled and possible adverse health effects avoided. This paper reports the results of a 2007 field study in The Netherlands with 725 respondents. A dose-response relationship between calculated A-weighted sound pressure levels and reported perception and annoyance was found. Wind turbine noise was more annoying than transportation noise or industrial noise at comparable levels, possibly due to specific sound properties such as a "swishing" quality, temporal variability, and lack of nighttime abatement. High turbine visibility enhances negative response, and having wind turbines visible from the dwelling significantly increased the risk of annoyance. Annoyance was strongly correlated with a negative attitude toward the visual impact of wind turbines on the landscape. The study further demonstrates that people who benefit economically from wind turbines have a significantly decreased risk of annoyance, despite exposure to similar sound levels. Response to wind turbine noise was similar to that found in Sweden so the dose-response relationship should be generalizable.

  7. Factoid forensics: have "more than 40" Australian families abandoned their homes because of wind farm noise?

    PubMed

    Chapman, Simon

    2014-01-01

    Anti-wind farm activists repeatedly claim that families said to be adversely affected by noise from wind turbines "abandon" their homes. In Australia, a claim of "more than 40 families" has been made by a prominent anti-wind farm activist. Six sources (parliamentary submissions, media reports, an anti-wind farm website, wind industry sources, correspondence with known anti-wind farm activists and with three politicians opposed to wind farms) were used to find evidence of home "abandonments." Claims about 12 Australian households permanently (n = 10) or periodically (n = 2) leaving their homes were found. However, no house appears to have been permanently "abandoned" without sale, as the expression implies. These 12 cases need contextualizing against considerations that several of those involved were either dedicated activists against wind farms from times sometimes pre-dating their construction, were engaged in protracted negotiations for home purchase with wind companies, had pre-existing health problems, grievances with the wind company over employment or had left the area for unrelated reasons of employment elsewhere. The statement that "more than 40" houses have been "abandoned" because of wind turbines in Australia is a factoid promoted by wind farm opponents for dramatic, rhetorical impact. Other considerations are often involved in abandonment unrelated to the claims made about wind farm noise.

  8. Large Wind Farms and the Scalar Flux over an Heterogeneously Rough Land Surface

    NASA Astrophysics Data System (ADS)

    Calaf, Marc; Higgins, Chad; Parlange, Marc B.

    2014-12-01

    The influence of surface heterogeneities extends vertically within the atmospheric surface layer to the so-called blending height, causing changes in the fluxes of momentum and scalars. Inside this region the turbulence structure cannot be treated as horizontally homogeneous; it is highly dependent on the local surface roughness, the buoyancy and the horizontal scale of heterogeneity. The present study analyzes the change in scalar flux induced by the presence of a large wind farm installed across a heterogeneously rough surface. The change in the internal atmospheric boundary-layer structure due to the large wind farm is decomposed and the change in the overall surface scalar flux is assessed. The equilibrium length scale characteristic of surface roughness transitions is found to be determined by the relative position of the smooth-to-rough transition and the wind turbines. It is shown that the change induced by large wind farms on the scalar flux is of the same order of magnitude as the adjustment they naturally undergo due to surface patchiness.

  9. An optimal sizing method for energy storage system in wind farms based on the analysis of wind power forecast error

    NASA Astrophysics Data System (ADS)

    Ye, R. L.; Guo, Z. Z.; Liu, R. Y.; Liu, J. N.

    2016-11-01

    Energy storage system (ESS) in a wind farm can effectively compensate the fluctuations of wind power. How to determine the size of ESS in wind farms is an urgent problem to be solved. A novel method is proposed for designing the optimal size of ESS considering wind power uncertainty. This approach uses non-parametric estimation method to analysis the wind power forecast error (WPFE) and the cumulative wind power deviation (CWPD) within the scheduling period. Then a cost-benefit analysis model is established to obtain the optimal size of ESS based on the analysis of WPFE and CWPD. A series of wind farm data in California are used as numerical cases, which presents that the algorithm presented in this paper has good feasibility and performance in optimal ESS sizing in wind farms.

  10. Prediction of the far field noise from wind energy farms

    NASA Technical Reports Server (NTRS)

    Shepherd, K. P.; Hubbard, H. H.

    1986-01-01

    The basic physical factors involved in making predictions of wind turbine noise and an approach which allows for differences in the machines, the wind energy farm configurations and propagation conditions are reviewed. Example calculations to illustrate the sensitivity of the radiated noise to such variables as machine size, spacing and numbers, and such atmosphere variables as absorption and wind direction are presented. It is found that calculated far field distances to particular sound level contours are greater for lower values of atmospheric absorption, for a larger total number of machines, for additional rows of machines and for more powerful machines. At short and intermediate distances, higher sound pressure levels are calculated for closer machine spacings, for more powerful machines, for longer row lengths and for closer row spacings.

  11. Optimizing wind farm layout via LES-calibrated geometric models inclusive of wind direction and atmospheric stability effects

    NASA Astrophysics Data System (ADS)

    Archer, Cristina; Ghaisas, Niranjan

    2015-04-01

    The energy generation at a wind farm is controlled primarily by the average wind speed at hub height. However, two other factors impact wind farm performance: 1) the layout of the wind turbines, in terms of spacing between turbines along and across the prevailing wind direction; staggering or aligning consecutive rows; angles between rows, columns, and prevailing wind direction); and 2) atmospheric stability, which is a measure of whether vertical motion is enhanced (unstable), suppressed (stable), or neither (neutral). Studying both factors and their complex interplay with Large-Eddy Simulation (LES) is a valid approach because it produces high-resolution, 3D, turbulent fields, such as wind velocity, temperature, and momentum and heat fluxes, and it properly accounts for the interactions between wind turbine blades and the surrounding atmospheric and near-surface properties. However, LES are computationally expensive and simulating all the possible combinations of wind directions, atmospheric stabilities, and turbine layouts to identify the optimal wind farm configuration is practically unfeasible today. A new, geometry-based method is proposed that is computationally inexpensive and that combines simple geometric quantities with a minimal number of LES simulations to identify the optimal wind turbine layout, taking into account not only the actual frequency distribution of wind directions (i.e., wind rose) at the site of interest, but also atmospheric stability. The geometry-based method is calibrated with LES of the Lillgrund wind farm conducted with the Software for Offshore/onshore Wind Farm Applications (SOWFA), based on the open-access OpenFOAM libraries. The geometric quantities that offer the best correlations (>0.93) with the LES results are the blockage ratio, defined as the fraction of the swept area of a wind turbine that is blocked by an upstream turbine, and the blockage distance, the weighted distance from a given turbine to all upstream turbines

  12. Assessing Possible Climatic Impacts of Large Wind Farms Using Satellite Data

    NASA Astrophysics Data System (ADS)

    Zhou, Liming; Tian, Yuhong; Baidya Roy, Somnath

    2013-04-01

    This is an invited talk. A growing number of numerical simulations with hypothetical wind farms generally agree that large wind farms might affect local to regional weather and climate. Here we present observational evidence for such impacts based on analyses of satellite derived land surface temperature (LST) data at ~1.1 km for the period of 2003-2011 over a region in West-Central Texas, where four of the world's largest wind farms are located. A warming effect is observed at nighttime over wind farms relative to nearby non-wind-farm regions while the effect at daytime is small. Its spatial pattern couples very well with wind turbines geographically, particularly at nighttime in summer, and its magnitude exhibits a persistent upward trend, corresponding to the increase of operating wind turbines with time. There are no evident changes in land surface properties over the wind farm region. No warming effects are seen for a nearby non-wind-farm region with similar topography, particularly over high elevation ridges where the wind turbines are mostly built. Together, these results suggest that the warming effect observed in MODIS over wind farms are very likely attributable to the development of wind farms. This inference is also consistent with the diurnal and seasonal variations in the frequency of wind speed and direction distribution and the changes in near-surface atmospheric boundary layer (ABL) conditions due to wind farm operations. The nocturnal ABL is typically stable and much thinner than the daytime ABL and hence the turbine enhanced vertical mixing produces a stronger nighttime effect. The stronger wind speed and the higher frequency of the wind speed within the optimal power generation range in summer than winter and at nighttime than daytime likely drives wind turbines to generate more electricity and turbulence and consequently results in the strongest warming effect at nighttime in summer. Overall, the warming effect reported here is local and small

  13. Wind farm production cost: Optimum turbine size and farm capacity in the actual market

    SciTech Connect

    Laali, A.R.; Meyer, J.L.; Bellot, C.; Louche, A.

    1996-12-31

    Several studies are undertaken in R&D Division of EDF in collaboration with ERASME association in order to have a good knowledge of the wind energy production costs. These studies are performed in the framework of a wind energy monitoring project and concern the influence of a few parameters like wind farm capacity, turbine size and wind speed on production costs, through an analysis of the actual market trend. Some 50 manufacturers and 140 different kind of wind turbines are considered for this study. The minimum production cost is situated at 800/900 kW wind turbine rated power. This point will probably move to more important powers in the future. This study is valid only for average conditions and some special parameters like particular climate conditions or lack of infrastructure for a special site the could modify the results shown on the curves. The variety of wind turbines (rated power as a function of rotor diameter, height and specific rated power) in the actual market is analyzed. A brief analysis of the market trend is also performed. 7 refs., 7 figs.

  14. Proposal of a methodology for the design of offshore wind farms

    NASA Astrophysics Data System (ADS)

    Esteban, Dolores; Diez, J. Javier; Santos Lopez, J.; Negro, Vicente

    2010-05-01

    In fact, the wind power installed in the sea is still very scarce, with only 1,500 megawatts in operation in the middle of 2009. Although the first offshore wind farm experiment took place in 1990, the facilities built up to now have been mainly pilot projects. These previous statements confirm the incipient state of offshore wind power, Anyway, in this moment this technology is being strongly pushed, especially by the governments of some countries - like the United Kingdom, Germany, etc. - which is due above all to the general commitments made to reduce the emission of greenhouses gases. All of these factors lead to predict a promising future for offshore wind power. Nevertheless, it has not been still established a general methodology for the design and the management of this kind of installations. This paper includes some of the results of a research project, which consists on the elaboration of a methodology to enable the optimization of the global process of the operations leading to the implantation of offshore wind facilities. The proposed methodology allows the planning of offshore wind projects according to an integral management policy, enabling not only technical and financial feasibility of the offshore wind project to be achieved, but also respect for the environment. For that, it has been necessary to take into account multiple factors, including the territory, the terrain, the physical-chemical properties of the contact area between the atmosphere and the ocean, the dynamics resulting in both as a consequence of the Earth's behaviour as a heat machine, external geodynamics, internal geodynamics, planetary dynamics, biokenosis, the legislative and financial framework, human activities, wind turbines, met masts, electric substations and lines, foundations, logistics and the project's financial profitability. For its validation, this methodology has been applied to different offshore wind farms in operation.

  15. Power Performance Verification of a Wind Farm Using the Friedman’s Test

    PubMed Central

    Hernandez, Wilmar; López-Presa, José Luis; Maldonado-Correa, Jorge L.

    2016-01-01

    In this paper, a method of verification of the power performance of a wind farm is presented. This method is based on the Friedman’s test, which is a nonparametric statistical inference technique, and it uses the information that is collected by the SCADA system from the sensors embedded in the wind turbines in order to carry out the power performance verification of a wind farm. Here, the guaranteed power curve of the wind turbines is used as one more wind turbine of the wind farm under assessment, and a multiple comparison method is used to investigate differences between pairs of wind turbines with respect to their power performance. The proposed method says whether the power performance of the specific wind farm under assessment differs significantly from what would be expected, and it also allows wind farm owners to know whether their wind farm has either a perfect power performance or an acceptable power performance. Finally, the power performance verification of an actual wind farm is carried out. The results of the application of the proposed method showed that the power performance of the specific wind farm under assessment was acceptable. PMID:27271628

  16. Power Performance Verification of a Wind Farm Using the Friedman's Test.

    PubMed

    Hernandez, Wilmar; López-Presa, José Luis; Maldonado-Correa, Jorge L

    2016-06-03

    In this paper, a method of verification of the power performance of a wind farm is presented. This method is based on the Friedman's test, which is a nonparametric statistical inference technique, and it uses the information that is collected by the SCADA system from the sensors embedded in the wind turbines in order to carry out the power performance verification of a wind farm. Here, the guaranteed power curve of the wind turbines is used as one more wind turbine of the wind farm under assessment, and a multiple comparison method is used to investigate differences between pairs of wind turbines with respect to their power performance. The proposed method says whether the power performance of the specific wind farm under assessment differs significantly from what would be expected, and it also allows wind farm owners to know whether their wind farm has either a perfect power performance or an acceptable power performance. Finally, the power performance verification of an actual wind farm is carried out. The results of the application of the proposed method showed that the power performance of the specific wind farm under assessment was acceptable.

  17. Could crop height affect the wind resource at agriculturally productive wind farm sites?

    DOE PAGES

    Vanderwende, Brian; Lundquist, Julie K.

    2015-11-07

    The collocation of cropland and wind turbines in the US Midwest region introduces complex meteorological interactions that could influence both agriculture and wind-power production. Crop management practices may affect the wind resource through alterations of land-surface properties. We use the weather research and forecasting (WRF) model to estimate the impact of crop height variations on the wind resource in the presence of a large turbine array. A hypothetical wind farm consisting of 121 1.8-MW turbines is represented using the WRF model wind-farm parametrization. We represent the impact of selecting soybeans rather than maize by altering the aerodynamic roughness length inmore » a region approximately 65 times larger than that occupied by the turbine array. Roughness lengths of 0.1 and 0.25 m represent the mature soy crop and a mature maize crop, respectively. In all but the most stable atmospheric conditions, statistically significant hub-height wind-speed increases and rotor-layer wind-shear reductions result from switching from maize to soybeans. Based on simulations for the entire month of August 2013, wind-farm energy output increases by 14 %, which would yield a significant monetary gain. Further investigation is required to determine the optimal size, shape, and crop height of the roughness modification to maximize the economic benefit and minimize the cost of such crop-management practices. As a result, these considerations must be balanced by other influences on crop choice such as soil requirements and commodity prices.« less

  18. Principal wind turbines for a conditional portfolio approach to wind farms

    NASA Astrophysics Data System (ADS)

    Lopes, Vitor V.; Scholz, Teresa; Raischel, Frank; Lind, Pedro G.

    2014-06-01

    We introduce a measure for estimating the best risk-return relation of power production in wind farms within a given time-lag, conditioned to the velocity field. The velocity field is represented by a scalar that weighs the influence of the velocity at each wind turbine at present and previous time-steps for the present "state" of the wind field. The scalar measure introduced is a linear combination of the few turbines, that most influence the overall power production. This quantity is then used as the condition for computing a conditional expected return and corresponding risk associated to the future total power output.

  19. Could Crop Height Impact the Wind Resource at Agriculturally Productive Wind Farm Sites?

    NASA Astrophysics Data System (ADS)

    Vanderwende, B. J.; Lundquist, J. K.

    2013-12-01

    The agriculture-intensive United States Midwest and Great Plains regions feature some of the best wind resources in the nation. Collocation of cropland and wind turbines introduces complex meteorological interactions that could affect both agriculture and wind power production. Crop management practices may modify the wind resource through alterations of land-surface properties. In this study, we used the Weather Research and Forecasting (WRF) model to estimate the impact of crop height variations on the wind resource in the presence of a large turbine array. We parameterized a hypothetical array of 121 1.8 MW turbines at the site of the 2011 Crop/Wind-energy Experiment field campaign using the WRF wind farm parameterization. We estimated the impact of crop choices on power production by altering the aerodynamic roughness length in a region approximately 65 times larger than that occupied by the turbine array. Roughness lengths of 10 cm and 25 cm represent a mature soy crop and a mature corn crop respectively. Results suggest that the presence of the mature corn crop reduces hub-height wind speeds and increases rotor-layer wind shear, even in the presence of a large wind farm which itself modifies the flow. During the night, the influence of the surface was dependent on the boundary layer stability, with strong stability inhibiting the surface drag from modifying the wind resource aloft. Further investigation is required to determine the optimal size, shape, and crop height of the roughness modification to maximize the economic benefit and minimize the cost of such crop management practices.

  20. Surrogate based wind farm layout optimization using manifold mapping

    NASA Astrophysics Data System (ADS)

    Kaja Kamaludeen, Shaafi M.; van Zuijle, Alexander; Bijl, Hester

    2016-09-01

    High computational cost associated with the high fidelity wake models such as RANS or LES serves as a primary bottleneck to perform a direct high fidelity wind farm layout optimization (WFLO) using accurate CFD based wake models. Therefore, a surrogate based multi-fidelity WFLO methodology (SWFLO) is proposed. The surrogate model is built using an SBO method referred as manifold mapping (MM). As a verification, optimization of spacing between two staggered wind turbines was performed using the proposed surrogate based methodology and the performance was compared with that of direct optimization using high fidelity model. Significant reduction in computational cost was achieved using MM: a maximum computational cost reduction of 65%, while arriving at the same optima as that of direct high fidelity optimization. The similarity between the response of models, the number of mapping points and its position, highly influences the computational efficiency of the proposed method. As a proof of concept, realistic WFLO of a small 7-turbine wind farm is performed using the proposed surrogate based methodology. Two variants of Jensen wake model with different decay coefficients were used as the fine and coarse model. The proposed SWFLO method arrived at the same optima as that of the fine model with very less number of fine model simulations.

  1. Wind energy potential assessment of Cameroon's coastal regions for the installation of an onshore wind farm.

    PubMed

    Arreyndip, Nkongho Ayuketang; Joseph, Ebobenow; David, Afungchui

    2016-11-01

    For the future installation of a wind farm in Cameroon, the wind energy potentials of three of Cameroon's coastal cities (Kribi, Douala and Limbe) are assessed using NASA average monthly wind data for 31 years (1983-2013) and compared through Weibull statistics. The Weibull parameters are estimated by the method of maximum likelihood, the mean power densities, the maximum energy carrying wind speeds and the most probable wind speeds are also calculated and compared over these three cities. Finally, the cumulative wind speed distributions over the wet and dry seasons are also analyzed. The results show that the shape and scale parameters for Kribi, Douala and Limbe are 2.9 and 2.8, 3.9 and 1.8 and 3.08 and 2.58, respectively. The mean power densities through Weibull analysis for Kribi, Douala and Limbe are 33.7 W/m2, 8.0 W/m2 and 25.42 W/m2, respectively. Kribi's most probable wind speed and maximum energy carrying wind speed was found to be 2.42 m/s and 3.35 m/s, 2.27 m/s and 3.03 m/s for Limbe and 1.67 m/s and 2.0 m/s for Douala, respectively. Analysis of the wind speed and hence power distribution over the wet and dry seasons shows that in the wet season, August is the windiest month for Douala and Limbe while September is the windiest month for Kribi while in the dry season, March is the windiest month for Douala and Limbe while February is the windiest month for Kribi. In terms of mean power density, most probable wind speed and wind speed carrying maximum energy, Kribi shows to be the best site for the installation of a wind farm. Generally, the wind speeds at all three locations seem quite low, average wind speeds of all the three studied locations fall below 4.0m/s which is far below the cut-in wind speed of many modern wind turbines. However we recommend the use of low cut-in speed wind turbines like the Savonius for stand alone low energy needs.

  2. Maiden Wind Farm, Final NEPA/SEPA Environmental Impact Statement

    SciTech Connect

    N /A

    2003-01-03

    BPA's proposed action is the execution of power purchase and construction and generation interconnection agreements to acquire and transmit up to 50 aMW (up to about 200 MW) of output from the proposed Maiden Wind Farm, which would be developed to generate up to 494 MW. Benton and Yakima Counties' proposed action is to grant Conditional Use Permits (CUPs) and other required permits for full build-out of the project, which would require construction of up to 549 wind turbines for a 494-MW project. The EIS evaluates two alternatives--the Proposed Action (which means that part or all of the proposed project would be built) and No Action. BPA would not purchase or transmit power from the project under the No Action Alternative and it is therefore likely that the project would not be constructed. Washington Winds Inc. proposes to construct and operate up to 494 megawatts (MW) of wind generation on privately- and publicly-owned property in Benton and Yakima Counties, Washington. This EIS evaluates the environmental effects of BPA's Proposed Action to execute power purchase and interconnection agreements for the purpose of acquiring up to 50 average megawatts (aMW) (up to about 200 MW) of the project developer's proposed Maiden Wind Farm. The project developer has requested a CUP for up to 494 MW. Although the full 494 MW of power may or may not be constructed, this EIS evaluates impacts from full buildout of the project. The project would be located about 10 miles northeast of Sunnyside in the Rattlesnake Hills and would occupy approximately 251 acres of land. Approximately 1,063 acres would be temporarily occupied during construction by facilities such as staging areas, equipment laydown areas, and rock quarries. Except for portions of two sections of land owned by the Washington Department of Natural Resources (DNR), the project would be constructed on privately-owned farm and ranch land in Benton and Yakima Counties. The major facilities of the project include up to

  3. Development of FAST.Farm: A New Multiphysics Engineering Tool for Wind Farm Design and Analysis: Preprint

    SciTech Connect

    Jonkman, Jason; Annoni, Jennifer; Hayman, Greg; Jonkman, Bonnie; Purkayastha, Avi

    2017-01-01

    This paper presents the development of FAST.Farm, a new multiphysics tool applicable to engineering problems in research and industry involving wind farm performance and cost optimization that is needed to address the current underperformance, failures, and expenses plaguing the wind industry. Achieving wind cost-of-energy targets - which requires improvements in wind farm performance and reliability, together with reduced uncertainty and expenditures - has been eluded by the complicated nature of the wind farm design problem, especially the sophisticated interaction between atmospheric phenomena and wake dynamics and array effects. FAST.Farm aims to balance the need for accurate modeling of the relevant physics for predicting power performance and loads while maintaining low computational cost to support a highly iterative and probabilistic design process and system-wide optimization. FAST.Farm makes use of FAST to model the aero-hydro-servo-elastics of distinct turbines in the wind farm, and it is based on some of the principles of the Dynamic Wake Meandering (DWM) model, but avoids many of the limitations of existing DWM implementations.

  4. Why the Coriolis force turns a wind farm wake to the right in the Northern Hemisphere

    NASA Astrophysics Data System (ADS)

    van der Laan, M. P.; Sørensen, N. N.

    2016-09-01

    The interaction between the Coriolis force and a wind farm wake is investigated by Reynolds-Averaged Navier-Stokes simulations, using two different wind farm representations: a high roughness and 5×5 actuator disks. Surprisingly, the calculated wind farm wake deflection is opposite in the two simulations. A momentum balance in the cross flow direction shows that the interaction between the Coriolis force and the 5 × 5 actuator disks is complex due to turbulent mixing of fresh momentum from above into the wind farm, which is not observed for the interaction between the Coriolis force and a roughness change.

  5. Grid connection of large offshore wind farms using HVDC

    NASA Astrophysics Data System (ADS)

    Xu, Lie; Andersen, Bjarne R.

    2006-07-01

    This article describes the use of high-voltage DC (HVDC) transmission systems for connection of large offshore wind farms using doubly fed induction generators (DFIGs) to the main grid. HVDC systems based on voltage source converters (VSC transmission) and on line-commutated converters (LCC HVDC) are discussed. The article describes proposed system configurations, operating principles and controls for the two technologies. PSCAD/EMTDC simulations are presented to demonstrate the robust performance of the proposed systems during variation of generation and onshore AC fault conditions. Copyright

  6. The consideration of atmospheric stability within wind farm AEP calculations

    NASA Astrophysics Data System (ADS)

    Schmidt, Jonas; Chang, Chi-Yao; Dörenkämper, Martin; Salimi, Milad; Teichmann, Tim; Stoevesandt, Bernhard

    2016-09-01

    The annual energy production of an existing wind farm including thermal stratification is calculated with two different methods and compared to the average of three years of SCADA data. The first method is based on steady state computational fluid dynamics simulations and the assumption of Reynolds-similarity at hub height. The second method is a wake modelling calculation, where a new stratification transformation model was imposed on the Jensen an Ainslie wake models. The inflow states for both approaches were obtained from one year WRF simulation data of the site. Although all models underestimate the mean wind speed and wake effects, the results from the phenomenological wake transformation are compatible with high-fidelity simulation results.

  7. Airborne sound propagation over sea during offshore wind farm piling.

    PubMed

    Van Renterghem, T; Botteldooren, D; Dekoninck, L

    2014-02-01

    Offshore piling for wind farm construction has attracted a lot of attention in recent years due to the extremely high noise emission levels associated with such operations. While underwater noise levels were shown to be harmful for the marine biology, the propagation of airborne piling noise over sea has not been studied in detail before. In this study, detailed numerical calculations have been performed with the Green's Function Parabolic Equation (GFPE) method to estimate noise levels up to a distance of 10 km. Measured noise emission levels during piling of pinpiles for a jacket-foundation wind turbine were assessed and used together with combinations of the sea surface state and idealized vertical sound speed profiles (downwind sound propagation). Effective impedances were found and used to represent non-flat sea surfaces at low-wind sea states 2, 3, and 4. Calculations show that scattering by a rough sea surface, which decreases sound pressure levels, exceeds refractive effects, which increase sound pressure levels under downwind conditions. This suggests that the presence of wind, even when blowing downwind to potential receivers, is beneficial to increase the attenuation of piling sound over the sea. A fully flat sea surface therefore represents a worst-case scenario.

  8. Unraveling the Mysteries of Turbulence Transport in a Wind Farm

    SciTech Connect

    Jha, Pankaj K.; Duque, Earl P. N.; Bashioum, Jessica L.; Schmitz, Sven

    2015-06-26

    A true physical understanding of the mysteries involved in the recovery process of the wake momentum deficit, downstream of utility-scale wind turbines in the atmosphere, has not been obtained to date. Field data are not acquired at sufficient spatial and temporal resolutions to dissect some of the mysteries of wake turbulence. It is here that the actuator line method has evolved to become the technology standard in the wind energy community. This work presents the actuator line method embedded into an Open source Field Operation and Manipulation (OpenFOAM) large-eddy simulation solver and applies it to two small wind farms, the first one consisting of an array of two National Renewable Energy Laboratory 5 Megawatt (NREL 5-MW) turbines separated by seven rotor diameters in neutral and unstable atmospheric boundary-layer flow and the second one consisting of five NREL 5-MW wind turbines in unstable atmospheric conditions arranged in two staggered arrays of two and three turbines, respectively. Detailed statistics involving power spectral density (PSD) of turbine power along with standard deviations reveal the effects of atmospheric turbulence and its space and time scales. In conclusion, high-resolution surface data extracts provide new insight into the complex recovery process of the wake momentum deficit governed by turbulence transport phenomena.

  9. Unraveling the Mysteries of Turbulence Transport in a Wind Farm

    DOE PAGES

    Jha, Pankaj K.; Duque, Earl P. N.; Bashioum, Jessica L.; ...

    2015-06-26

    A true physical understanding of the mysteries involved in the recovery process of the wake momentum deficit, downstream of utility-scale wind turbines in the atmosphere, has not been obtained to date. Field data are not acquired at sufficient spatial and temporal resolutions to dissect some of the mysteries of wake turbulence. It is here that the actuator line method has evolved to become the technology standard in the wind energy community. This work presents the actuator line method embedded into an Open source Field Operation and Manipulation (OpenFOAM) large-eddy simulation solver and applies it to two small wind farms, themore » first one consisting of an array of two National Renewable Energy Laboratory 5 Megawatt (NREL 5-MW) turbines separated by seven rotor diameters in neutral and unstable atmospheric boundary-layer flow and the second one consisting of five NREL 5-MW wind turbines in unstable atmospheric conditions arranged in two staggered arrays of two and three turbines, respectively. Detailed statistics involving power spectral density (PSD) of turbine power along with standard deviations reveal the effects of atmospheric turbulence and its space and time scales. In conclusion, high-resolution surface data extracts provide new insight into the complex recovery process of the wake momentum deficit governed by turbulence transport phenomena.« less

  10. Risk analysis for U.S. offshore wind farms: the need for an integrated approach.

    PubMed

    Staid, Andrea; Guikema, Seth D

    2015-04-01

    Wind power is becoming an increasingly important part of the global energy portfolio, and there is growing interest in developing offshore wind farms in the United States to better utilize this resource. Wind farms have certain environmental benefits, notably near-zero emissions of greenhouse gases, particulates, and other contaminants of concern. However, there are significant challenges ahead in achieving large-scale integration of wind power in the United States, particularly offshore wind. Environmental impacts from wind farms are a concern, and these are subject to a number of on-going studies focused on risks to the environment. However, once a wind farm is built, the farm itself will face a number of risks from a variety of hazards, and managing these risks is critical to the ultimate achievement of long-term reductions in pollutant emissions from clean energy sources such as wind. No integrated framework currently exists for assessing risks to offshore wind farms in the United States, which poses a challenge for wind farm risk management. In this "Perspective", we provide an overview of the risks faced by an offshore wind farm, argue that an integrated framework is needed, and give a preliminary starting point for such a framework to illustrate what it might look like. This is not a final framework; substantial work remains. Our intention here is to highlight the research need in this area in the hope of spurring additional research about the risks to wind farms to complement the substantial amount of on-going research on the risks from wind farms.

  11. The impact of wakes on power output at large offshore wind farms

    NASA Astrophysics Data System (ADS)

    Barthelmie, R. J.; Frandsen, S.; Hansen, K.; Schepers, G.; Rados, K.; Schlez, W.; Cabezon, D.; Jensen, L.; Neckelmann, S.

    2010-12-01

    The size of planned offshore wind farms is in the range 100 MW to 1 GW requiring tens to hundreds of wind turbines typically arranged in a large array. As wind farms offshore increase in size, one of the research challenges is to model interactions between the individual turbines, the atmosphere and neighbouring turbines to accurately predict power output before wind farm construction in addition to evaluation during the operation phase. The aim of the research described (part of the UpWind project) is to improve wind farm modelling and address the issue of providing more accurate power output predictions accounting for wind turbine wakes. DONG Energy and Vattenfall have allowed data from a number of cases studies to be used in this project. Detailed case studies of power losses due to wakes at the large wind farms at Nysted and Horns Rev have been analysed and are presented. A focus of the data analysis has been to understand the importance of turbulence and atmospheric stability at these offshore sites. It is evident that the magnitude of wake losses is primarily driven by wind speed but that signals from turbine spacing, turbulence and atmospheric stability can be determined. The case studies are simulated with a range of wind farm and computational fluid dynamics (CFD) models. The UpWind project presents a unique platform for model evaluation because the co-operation of a number of groups means that more models can be evaluated on standardised cases. Results shown indicate power losses due to wakes can be modelled, provided that the standard models are subject to some modifications. We also present some of the first full simulations of large offshore wind farms using CFD. Despite this progress, wake modelling of large wind farms is still subject to an unacceptably high degree of uncertainty requiring further work to understand the physical flow processes within and downwind of large wind farms.

  12. Investigation of modified AD/RANS models for wind turbine wake predictions in large wind farm

    NASA Astrophysics Data System (ADS)

    Tian, L. L.; Zhu, W. J.; Shen, W. Z.; Sørensen, J. N.; Zhao, N.

    2014-06-01

    Average power losses due to multiple wind turbine wakes in the large offshore wind farm is studied in this paper using properly modified k-ω SST turbulence models. The numerical simulations are carried out by the actuator disc methodology implemented in the flow solver EllipSys3D. In these simulations, the influence of different inflow conditions such as wind direction sectors are considered and discussed. Comparisons with measurements in terms of wake speed ratio and the corresponding power outputs show that the modified turbulence models had significant improvements; especially the SST-Csust model reflects the best ability in predicting the wake defect. The investigations of various inflow angles reveal that the agreement between predicted and measured data is improved for the wider sector case than the narrow case because of the wind direction uncertainty.

  13. Yaw-Misalignment and its Impact on Wind Turbine Loads and Wind Farm Power Output

    NASA Astrophysics Data System (ADS)

    van Dijk, Mike T.; van Wingerden, Jan-Willem; Ashuri, Turaj; Li, Yaoyu; Rotea, Mario A.

    2016-09-01

    To make wind energy cost competitive with traditional resources, wind turbines are commonly placed in groups. Aerodynamic interaction between the turbines causes sub-optimal energy production. A control strategy to mitigate these losses is by redirecting the wake by yaw misalignment. This paper aims to assess the influence of load variations of the rotor due to partial wake overlap and presents a combined optimization of the power and loads using wake redirection. For this purpose, we design a computational framework which computes the wind farm power production and the wind turbine rotor loads based on the yaw settings. The simulation results show that partial wake overlap can significantly increase asymmetric loading of the rotor disk and that yaw misalignment is beneficial in situations where the wake can be sufficiently directed away from the downstream turbine.

  14. Impacts of Wake Effect and Time Delay on the Dynamic Analysis of Wind Farms Models

    ERIC Educational Resources Information Center

    El-Fouly, Tarek H. M.; El-Saadany, Ehab F.; Salama, Magdy M. A.

    2008-01-01

    This article investigates the impacts of proper modeling of the wake effects and wind speed delays, between different wind turbines' rows, on the dynamic performance accuracy of the wind farms models. Three different modeling scenarios were compared to highlight the impacts of wake effects and wind speed time-delay models. In the first scenario,…

  15. DOE/NREL Wind Farm Monitoring: Annual Report, July 2000-July 2001

    SciTech Connect

    Smith, J. W.

    2002-04-01

    The Wind Program and the wind power industry currently do not have the ability to accurately assess ancillary service burdens or benefits of wind-powered electricity. This evaluation can help in determining if efforts should be expended in beginning to examine possible mitigation strategies by including detailed data analysis from two wind farm facilities.

  16. Estimating the Power Characteristics of Clusters of Large Offshore Wind Farms

    NASA Astrophysics Data System (ADS)

    Drew, D.; Barlow, J. F.; Coceal, O.; Coker, P.; Brayshaw, D.; Lenaghan, D.

    2014-12-01

    The next phase of offshore wind projects in the UK focuses on the development of very large wind farms clustered within several allocated zones. However, this change in the distribution of wind capacity brings uncertainty for the operational planning of the power system. Firstly, there are concerns that concentrating large amounts of capacity in one area could reduce some of the benefits seen by spatially dispersing the turbines, such as the smoothing of the power generation variability. Secondly, wind farms of the scale planned are likely to influence the boundary layer sufficiently to impact the performance of adjacent farms, therefore the power generation characteristics of the clusters are largely unknown. The aim of this study is to use the Weather Research and Forecasting (WRF) model to investigate the power output of a cluster of offshore wind farms for a range of extreme events, taking into account the wake effects of the individual turbines and the neighbouring farms. Each wind farm in the cluster is represented as an elevated momentum sink and a source of turbulent kinetic energy using the WRF Wind Farm Parameterization. The research focuses on the Dogger Bank zone (located in the North Sea approximately 125 km off the East coast of the UK), which could have 7.2 GW of installed capacity across six separate wind farms. For this site, a 33 year reanalysis data set (MERRA, from NASA-GMAO) has been used to identify a series of extreme event case studies. These are characterised by either periods of persistent low (or high) wind speeds, or by rapid changes in power output. The latter could be caused by small changes in the wind speed inducing large changes in power output, very high winds prompting turbine shut down, or a change in the wind direction which shifts the wake effects of the neighbouring farms in the cluster and therefore changes the wind resource available.

  17. Evaluation of wind energy cost and site selection for a wind-farm in the south of Algeria

    NASA Astrophysics Data System (ADS)

    Benmemdejahed, M.; Mouhadjer, S.

    2016-07-01

    The aim of this paper is to evaluate the wind resource on five sites situated in Algerian Sahara, namely Adrar, Ain Salah, Bordj Badji Mokhtar, Hassi R'Mel and Tindouf. The hourly data used in this study span a period of last five years. The parameters considered are the wind speed. After the evaluation of wind energy, the economic evaluation was conducted for wind farm (18 MW). We select the best site from the five sites and an appropriate wind turbine from nine wind turbine, according to the lowest possible unity cost of energy. Hassi R'Mel is favorable site for installed wind frame In order to reach the rated power 18 MW of the wind farm; our choice is focused on one row of twelve wind turbines (wgt1.5MW) from East South East (ESE) to West North West (WNW), 320 m of distance between each two turbines.

  18. 76 FR 75542 - Rail Splitter Wind Farm, LLC v. Ameren Services Company Midwest Independent Transmission, System...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-02

    ... Federal Energy Regulatory Commission Rail Splitter Wind Farm, LLC v. Ameren Services Company Midwest... Regulatory Commission's (Commission) Rules of Practice and Procedures, 18 CFR 385.206, Rail Splitter Wind Farm, LLC (Rail Splitter or Complainant) filed a formal complaint against Ameren Services...

  19. Evaluating internalization of multifunctionality by farm diversification: evidence from educational dairy farms in Japan.

    PubMed

    Ohe, Yasuo

    2011-03-01

    Farm diversification by farmers' open-door policy generates opportunities for farmers to internalize externalities of multifunctionality. Although the educational function of agriculture is an example of such an open-door policy and is attracting growing attention, this function has been little explored. To promote farm diversification in this direction, this paper examined how and to what degree farmers internalize externalities of multifunctionality by focusing on the educational function provided by dairy farming, i.e., farming experience services, in Japan. The main findings were as follows. First, we can say that the educational function is determined by ordinary technical jointness as well as institutional jointness, which is represented by food culture and the agrarian heritage. Both the technical and institutional jointness enhanced the externality. Because of these two working factors, there is a U-shaped relationship between farm diversification and provision of farming experience services. Second, however, an empirical evaluation indicated that farmers only partially internalize educational externalities by treating them as supplementary services combined with processed milk products. Therefore, appropriate integrated management of these newly emerging educational services to become a viable market should be fully addressed in the future, especially for family farms.

  20. Dynamic response improvement of doubly fed induction generator-based wind farm using fuzzy logic controller

    NASA Astrophysics Data System (ADS)

    Hasanien, Hany M.; Al-Ammar, Essam A.

    2012-11-01

    Doubly fed induction generator (DFIG) based wind farm is today the most widely used concept. This paper presents dynamic response enhancement of DFIG based wind farm under remote fault conditions using the fuzzy logic controller. The goal of the work is to improve the dynamic response of DFIG based wind farm during and after the clearance of fault using the proposed controller. The stability of wind farm during and after the clearance of fault is investigated. The effectiveness of the fuzzy logic controller is then compared with that of a PI controller. The validity of the controllers in restoring the wind farms normal operation after the clearance of fault is illustrated by the simulation results which are carried out using MATLAB/SIMULINK. Simulation results are analyzed under different fault conditions.

  1. 75 FR 26747 - Meadow Lake Wind Farm IV LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-12

    ...] Meadow Lake Wind Farm IV LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request...-referenced proceeding of Meadow Lake Wind Farm IV LLC's application for market-based rate authority, with...

  2. 75 FR 26747 - Meadow Lake Wind Farm III LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-12

    ...-1176-000] Meadow Lake Wind Farm III LLC; Supplemental Notice That Initial Market-Based Rate Filing... above-referenced proceeding of Meadow Lake Wind Farm III LLC's application for market-based...

  3. 77 FR 60281 - Regarding the Acquisition of Four U.S. Wind Farm Project Companies by Ralls Corporation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-03

    ... Documents#0;#0; ] Order of September 28, 2012 Regarding the Acquisition of Four U.S. Wind Farm Project... proposed to construct wind farms (including alternate sites) that are identified in the notice filed...

  4. Wind tunnel measurements of the power output variability and unsteady loading in a micro wind farm model

    NASA Astrophysics Data System (ADS)

    Bossuyt, Juliaan; Howland, Michael; Meneveau, Charles; Meyers, Johan

    2015-11-01

    To optimize wind farm layouts for a maximum power output and wind turbine lifetime, mean power output measurements in wind tunnel studies are not sufficient. Instead, detailed temporal information about the power output and unsteady loading from every single wind turbine in the wind farm is needed. A very small porous disc model with a realistic thrust coefficient of 0.75 - 0.85, was designed. The model is instrumented with a strain gage, allowing measurements of the thrust force, incoming velocity and power output with a frequency response up to the natural frequency of the model. This is shown by reproducing the -5/3 spectrum from the incoming flow. Thanks to its small size and compact instrumentation, the model allows wind tunnel studies of large wind turbine arrays with detailed temporal information from every wind turbine. Translating to field conditions with a length-scale ratio of 1:3,000 the frequencies studied from the data reach from 10-4 Hz up to about 6 .10-2 Hz. The model's capabilities are demonstrated with a large wind farm measurement consisting of close to 100 instrumented models. A high correlation is found between the power outputs of stream wise aligned wind turbines, which is in good agreement with results from prior LES simulations. Work supported by ERC (ActiveWindFarms, grant no. 306471) and by NSF (grants CBET-113380 and IIA-1243482, the WINDINSPIRE project).

  5. LES of wind farm response to transient scenarios using a high fidelity actuator disk model

    NASA Astrophysics Data System (ADS)

    Moens, M.; Duponcheel, M.; Winckelmans, G.; Chatelain, P.

    2016-09-01

    Large eddy simulations coupled to Actuator Disks are used to investigate wake effects in wind farms. An effort is made on the wind turbine model: it uses the prevailing velocities at each point of the disk to estimate the aerodynamic loads and is improved using a tip-loss correction and realistic control schemes. This accurate and efficient tool is used to study the wind farm response in terms of flow and power production during an unsteady scenario: this work focuses on an emergency shutdown of one rotor inside a wind farm.

  6. Modelling one row of Horns Rev wind farm with the Actuator Line Model with coarse resolution

    NASA Astrophysics Data System (ADS)

    Draper, M.; Guggeri, A.; Usera, G.

    2016-09-01

    Actuator models have been used to represent the presence of wind turbines in a simulation in the past few years. The Actuator Line Model (ALM) has shown to reproduce with reasonable accuracy the wind flow through wind turbines under different operational conditions. Nevertheless, there are not many simulations of wind farms performed with the ALM mainly because of its computational cost. The aim of the present paper is to evaluate the ALM in spatial resolutions coarser than what is generally recommended, also using larger time steps, in a simulation of a real wind farm. To accomplish this, simulations of one row of Horns Rev wind farm are performed, for different wind directions. It is concluded that the ALM is able to capture the main features of the interaction between wind turbines relaxing its resolution requirements. A sensitivity analysis is performed to assess the influence of the smearing factor and the spatial resolution.

  7. Simulation of an offshore wind farm using fluid power for centralized electricity generation

    NASA Astrophysics Data System (ADS)

    Jarquin-Laguna, A.

    2016-09-01

    A centralized approach for electricity generation within a wind farm is explored through the use of fluid power technology. This concept considers a new way of generation, collection and transmission of wind energy inside a wind farm, in which electrical conversion does not occur during any intermediate conversion step before the energy has reached the offshore central platform. A numerical model was developed to capture the relevant physics from the dynamic interaction between different turbines coupled to a common hydraulic network and controller. This paper presents two examples of the time-domain simulation results for an hypothetical hydraulic wind farm subject to turbulent wind conditions. The performance and operational parameters of individual turbines are compared with those of a reference wind farm with conventional technology turbines, using the same wind farm layout and environmental conditions. For the presented case study, results indicate that the individual wind turbines are able to operate within operational limits with the current pressure control concept. Despite the stochastic turbulent wind input and wake effects, the hydraulic wind farm is able to produce electricity with reasonable performance in both below and above rated conditions.

  8. Polynomial chaos for the computation of annual energy production in wind farm layout optimization

    NASA Astrophysics Data System (ADS)

    Padrón, A. S.; Stanley, A. P. J.; Thomas, J. J.; Alonso, J. J.; Ning, A.

    2016-09-01

    Careful management of wake interference is essential to further improve Annual Energy Production (AEP) of wind farms. Wake effects can be minimized through optimization of turbine layout, wind farm control, and turbine design. Realistic wind farm optimization is challenging because it has numerous design degrees of freedom and must account for the stochastic nature of wind. In this paper we provide a framework for calculating AEP for any relevant uncertain (stochastic) variable of interest. We use Polynomial Chaos (PC) to efficiently quantify the effect of the stochastic variables—wind direction and wind speed—on the statistical outputs of interest (AEP) for wind farm layout optimization. When the stochastic variable includes the wind direction, polynomial chaos is one order of magnitude more accurate in computing the AEP when compared to commonly used simplistic integration techniques (rectangle rule), especially for non grid-like wind farm layouts. Furthermore, PC requires less simulations for the same accuracy. This allows for more efficient optimization and uncertainty quantification of wind farm energy production.

  9. Fatigue minimising power reference control of a de-rated wind farm

    NASA Astrophysics Data System (ADS)

    Jensen, T. N.; Knudsen, T.; Bak, T.

    2016-09-01

    Modern wind farms (cluster of wind turbines) can be required to control the total power output to meet a set-point, and would then profit by minimising the structural loads and thereby the cost of energy. In this paper, we propose a new control strategy for a derated wind farm with the objective of maintaining a desired reference power production for the wind farm, while minimising the sum of fatigues on the wind turbines in steady-state. The controller outputs a vector of power references for the individual turbines. It exploits the positive correlation between fatigue and added turbulence to minimise fatigue indirectly by minimising the added turbulence. Simulated results for a wind farm with three turbines demonstrate the efficacy of the proposed solution by assessing the damage equivalent loads.

  10. Potential Impacts of Offshore Wind Farms on North Sea Stratification

    PubMed Central

    Carpenter, Jeffrey R.; Merckelbach, Lucas; Callies, Ulrich; Clark, Suzanna; Gaslikova, Lidia; Baschek, Burkard

    2016-01-01

    Advances in offshore wind farm (OWF) technology have recently led to their construction in coastal waters that are deep enough to be seasonally stratified. As tidal currents move past the OWF foundation structures they generate a turbulent wake that will contribute to a mixing of the stratified water column. In this study we show that the mixing generated in this way may have a significant impact on the large-scale stratification of the German Bight region of the North Sea. This region is chosen as the focus of this study since the planning of OWFs is particularly widespread. Using a combination of idealised modelling and in situ measurements, we provide order-of-magnitude estimates of two important time scales that are key to understanding the impacts of OWFs: (i) a mixing time scale, describing how long a complete mixing of the stratification takes, and (ii) an advective time scale, quantifying for how long a water parcel is expected to undergo enhanced wind farm mixing. The results are especially sensitive to both the drag coefficient and type of foundation structure, as well as the evolution of the pycnocline under enhanced mixing conditions—both of which are not well known. With these limitations in mind, the results show that OWFs could impact the large-scale stratification, but only when they occupy extensive shelf regions. They are expected to have very little impact on large-scale stratification at the current capacity in the North Sea, but the impact could be significant in future large-scale development scenarios. PMID:27513754

  11. Potential Impacts of Offshore Wind Farms on North Sea Stratification.

    PubMed

    Carpenter, Jeffrey R; Merckelbach, Lucas; Callies, Ulrich; Clark, Suzanna; Gaslikova, Lidia; Baschek, Burkard

    2016-01-01

    Advances in offshore wind farm (OWF) technology have recently led to their construction in coastal waters that are deep enough to be seasonally stratified. As tidal currents move past the OWF foundation structures they generate a turbulent wake that will contribute to a mixing of the stratified water column. In this study we show that the mixing generated in this way may have a significant impact on the large-scale stratification of the German Bight region of the North Sea. This region is chosen as the focus of this study since the planning of OWFs is particularly widespread. Using a combination of idealised modelling and in situ measurements, we provide order-of-magnitude estimates of two important time scales that are key to understanding the impacts of OWFs: (i) a mixing time scale, describing how long a complete mixing of the stratification takes, and (ii) an advective time scale, quantifying for how long a water parcel is expected to undergo enhanced wind farm mixing. The results are especially sensitive to both the drag coefficient and type of foundation structure, as well as the evolution of the pycnocline under enhanced mixing conditions-both of which are not well known. With these limitations in mind, the results show that OWFs could impact the large-scale stratification, but only when they occupy extensive shelf regions. They are expected to have very little impact on large-scale stratification at the current capacity in the North Sea, but the impact could be significant in future large-scale development scenarios.

  12. Optimization of Wind Turbine Airfoils/Blades and Wind Farm Layouts

    NASA Astrophysics Data System (ADS)

    Chen, Xiaomin

    by the turbine can be significantly increased. Parametric studies are also conducted by varying the turbine diameter. In addition, a simplified dynamic inflow model is integrated into the BEM theory. It is shown that the improved BEM theory has superior performance in capturing the instantaneous behavior of wind turbines due to the existence of wind turbine wake or temporal variations in wind velocity. The dissertation also considers the Wind Farm layout optimization problem using a genetic algorithm. Both the Horizontal --Axis Wind Turbines (HAWT) and Vertical-Axis Wind Turbines (VAWT) are considered. The goal of the optimization problem is to optimally position the turbines within the wind farm such that the wake effects are minimized and the power production is maximized. The reasonably accurate modeling of the turbine wake is critical in determination of the optimal layout of the turbines and the power generated. For HAWT, two wake models are considered; both are found to give similar answers. For VAWT, a very simple wake model is employed. Finally, some preliminary investigation of shape optimization of 3D wind turbine blades at low Reynolds numbers is conducted. The optimization employs a 3D straight untapered wind turbine blade with cross section of NACA 0012 airfoils as the geometry of baseline blade. The optimization objective is to achieve maximum Cl/Cd as well as maximum Cl. The multi-objective genetic algorithm is employed together with the commercially available software FLUENT for calculation of the flow field using the Reynolds-Averaged Navier-Stokes (RANS) equations in conjunction with a one-equation Sparlart-Allmaras turbulence model. The results show excellent performance of the optimized wind turbine blade and indicate the feasibility of optimization on real wind turbine blades with more complex shapes in the future. (Abstract shortened by UMI.)

  13. 75 FR 52374 - National Environmental Policy Act; NASA Glenn Research Center Plum Brook Station Wind Farm Project

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-25

    ... Environmental Policy Act; NASA Glenn Research Center Plum Brook Station Wind Farm Project AGENCY: National... scoping and prepare an Environmental Impact Statement (EIS) for the NASA GRC Plum Brook Station Wind Farm... scoping is for NASA to obtain public comments on construction and operation of the wind farm. The...

  14. Smoothing of wind farm output power using prediction based flywheel energy storage system

    NASA Astrophysics Data System (ADS)

    Islam, Farzana

    Being socially beneficial, economically competitive and environment friendly, wind energy is now considered to be the world's fastest growing renewable energy source. However, the stochastic nature of wind imposes a considerable challenge in the optimal management and operation of wind power system. Wind speed prediction is critical for wind energy conversion system since it greatly influences the issues related to effective energy management, dynamic control of wind turbine, and improvement of the overall efficiency of the power generation system. This thesis focuses on integration of energy storage system with wind farm, considering wind speed prediction in the control scheme to overcome the problems associated with wind power fluctuations. In this thesis, flywheel energy storage system (FESS) with adjustable speed rotary machine has been considered for smoothing of output power in a wind farm composed of a fixed speed wind turbine generator (FSWTG). Since FESS has both active and reactive power compensation ability, it enhances the stability of the system effectively. An efficient energy management system combined with supervisory control unit (SCU) for FESS and wind speed prediction has been developed to improve the smoothing of the wind farm output effectively. Wind speed prediction model is developed by artificial neural network (ANN) which has advantages over the conventional prediction scheme including data error tolerance and ease in adaptability. The model for prediction with ANN is developed in MATLAB/Simulink and interfaced with PSCAD/EMTDC. Effectiveness of the proposed control system is illustrated using real wind speed data in various operating conditions.

  15. A survey of modelling methods for high-fidelity wind farm simulations using large eddy simulation.

    PubMed

    Breton, S-P; Sumner, J; Sørensen, J N; Hansen, K S; Sarmast, S; Ivanell, S

    2017-04-13

    Large eddy simulations (LES) of wind farms have the capability to provide valuable and detailed information about the dynamics of wind turbine wakes. For this reason, their use within the wind energy research community is on the rise, spurring the development of new models and methods. This review surveys the most common schemes available to model the rotor, atmospheric conditions and terrain effects within current state-of-the-art LES codes, of which an overview is provided. A summary of the experimental research data available for validation of LES codes within the context of single and multiple wake situations is also supplied. Some typical results for wind turbine and wind farm flows are presented to illustrate best practices for carrying out high-fidelity LES of wind farms under various atmospheric and terrain conditions.This article is part of the themed issue 'Wind energy in complex terrains'.

  16. LES of large wind farm during a diurnal cycle: Analysis of Energy and Scalar flux budgets

    NASA Astrophysics Data System (ADS)

    Sharma, V.; Calaf, M.; Parlange, M. B.

    2014-12-01

    With an expanding role of wind energy in satisfying energy demands around the world, wind farms are covering increasingly larger surfaces to the point where interaction between wind farms and the atmospheric boundary layer (ABL) might have significant implications. Furthermore, many wind farm sites lie over existing farmland for which water is a precious resource. In this context, a relevant question yet to be fully understood, is whether large wind farms alter near surface temperatures and evaporation rates and if so, by how much. In the present study, Large Eddy Simulation (LES) of a geostrophic wind driven ABL with two active scalars, temperature and specific humidity, in the presence of Coriolis forces with an embedded wind farm are performed. Multiple 'synthetic' diurnal cycles are simulated by imposing a time-varying surface temperature and specific humidity. Wind turbines are modeled using the "actuator disk" approach along with the flexibility to reorient according to varying flow directions. LES is performed using the "pseudo-spectral" approach implying that an infinitely large wind farm is simulated. Comparison of simulations with and without wind farms show clear differences in vertical profiles of horizontal velocity magnitude and direction, turbulent kinetic energy and scalar fluxes. To better understand these differences, a detailed analysis of the constituent terms of budget equations of mean and turbulent kinetic energy and sensible and latent heat fluxes has been performed for different stratification regimes as the ABL evolves during the diurnal cycle. The analyses help explain the effect of wind farms on the characteristics of the low-level jet, depth of the stable boundary layer, formation and growth of the convective boundary layer (CBL) and scalar fluxes at the surface.

  17. Climate Impacts of Large-scale Wind Farms as Parameterized in a Global Climate Model

    NASA Astrophysics Data System (ADS)

    Fitch, Anna

    2015-04-01

    The local, regional and global climate impacts of a large-scale global deployment of wind power in regionally high densities over land is investigated for a 60 year period. Wind farms are represented as elevated momentum sinks, as well as enhanced turbulence to represent turbine blade mixing in a global climate model, the Community Atmosphere Model version 5 (CAM5). For a total installed capacity of 2.5 TW, to provide 16% of the world's projected electricity demand in 2050, minimal impacts are found, both regionally and globally, on temperature, sensible and latent heat fluxes, cloud and precipitation. A mean near-surface warming of 0.12+/-0.07 K is seen within the wind farms. Impacts on wind speed and turbulence are more pronounced, but largely confined to within the wind farm areas. Increasing the wind farm areas to provide an installed capacity of 10 TW, or 65% of the 2050 electricity demand, causes further impacts, however, they remain slight overall. Maximum temperature changes are less than 0.5 K in the wind farm areas. Impacts, both within the wind farms and beyond, become more pronounced with a doubling in turbine density, to provide 20 TW of installed capacity, or 130% of the 2050 electricity demand. However, maximum temperature changes remain less than 0.7 K. Representing wind farms instead as an increase in surface roughness generally produces similar mean results, however, maximum changes increase and influences on wind and turbulence are exaggerated. Overall, wind farm impacts are much weaker than those expected from greenhouse gas emissions, with global mean climate impacts very slight.

  18. CgWind: A high-order accurate simulation tool for wind turbines and wind farms

    SciTech Connect

    Chand, K K; Henshaw, W D; Lundquist, K A; Singer, M A

    2010-02-22

    CgWind is a high-fidelity large eddy simulation (LES) tool designed to meet the modeling needs of wind turbine and wind park engineers. This tool combines several advanced computational technologies in order to model accurately the complex and dynamic nature of wind energy applications. The composite grid approach provides high-quality structured grids for the efficient implementation of high-order accurate discretizations of the incompressible Navier-Stokes equations. Composite grids also provide a natural mechanism for modeling bodies in relative motion and complex geometry. Advanced algorithms such as matrix-free multigrid, compact discretizations and approximate factorization will allow CgWind to perform highly resolved calculations efficiently on a wide class of computing resources. Also in development are nonlinear LES subgrid-scale models required to simulate the many interacting scales present in large wind turbine applications. This paper outlines our approach, the current status of CgWind and future development plans.

  19. Different shades of green: a case study of support for wind farms in the rural midwest.

    PubMed

    Mulvaney, Kate K; Woodson, Patrick; Prokopy, Linda Stalker

    2013-05-01

    Benton County, in north-central Indiana, USA has successfully sited more than 500 turbines. To understand Benton County's acceptance of wind farms, a holistic case study was conducted that included a document review, a survey of local residents and interviews with key stakeholders. Survey questionnaires were sent to 750 residents asking questions about attitudes toward the wind farms, perceived benefits and impacts from the wind farms, environmental attitudes, and demographic information. Key stakeholders were also interviewed for a deeper understanding of the historical timeline and community acceptance of the wind farm development. While there is limited opposition to the turbines, on the whole the community presents a front of acceptance. Financial, rather than environmental, benefits are the main reason for the acceptance. Although significant in other case studies, transparency and participation do not play a large role in Benton County's acceptance. Most residents are not concerned with either visual impacts or noise from the wind turbines. More concrete benefits to the community, such as reduced energy bills for county residents, could help to extend acceptance even further within the community. Although there are concerns about the acceptance of wind farms and the impacts of those farms on local residents in both peer-reviewed literature and popular media, we found little evidence of those concerns in Benton County. Instead, we found Benton County to be a community largely accepting of wind farms.

  20. Different Shades of Green: A Case Study of Support for Wind Farms in the Rural Midwest

    NASA Astrophysics Data System (ADS)

    Mulvaney, Kate K.; Woodson, Patrick; Prokopy, Linda Stalker

    2013-05-01

    Benton County, in north-central Indiana, USA has successfully sited more than 500 turbines. To understand Benton County's acceptance of wind farms, a holistic case study was conducted that included a document review, a survey of local residents and interviews with key stakeholders. Survey questionnaires were sent to 750 residents asking questions about attitudes toward the wind farms, perceived benefits and impacts from the wind farms, environmental attitudes, and demographic information. Key stakeholders were also interviewed for a deeper understanding of the historical timeline and community acceptance of the wind farm development. While there is limited opposition to the turbines, on the whole the community presents a front of acceptance. Financial, rather than environmental, benefits are the main reason for the acceptance. Although significant in other case studies, transparency and participation do not play a large role in Benton County's acceptance. Most residents are not concerned with either visual impacts or noise from the wind turbines. More concrete benefits to the community, such as reduced energy bills for county residents, could help to extend acceptance even further within the community. Although there are concerns about the acceptance of wind farms and the impacts of those farms on local residents in both peer-reviewed literature and popular media, we found little evidence of those concerns in Benton County. Instead, we found Benton County to be a community largely accepting of wind farms.

  1. Wind farms providing secondary frequency regulation: Evaluating the performance of model-based receding horizon control

    NASA Astrophysics Data System (ADS)

    Shapiro, Carl R.; Meyers, Johan; Meneveau, Charles; Gayme, Dennice F.

    2016-09-01

    We investigate the use of wind farms to provide secondary frequency regulation for a power grid. Our approach uses model-based receding horizon control of a wind farm that is tested using a large eddy simulation (LES) framework. In order to enable real-time implementation, the control actions are computed based on a time-varying one-dimensional wake model. This model describes wake advection and interactions, both of which play an important role in wind farm power production. This controller is implemented in an LES model of an 84-turbine wind farm represented by actuator disk turbine models. Differences between the velocities at each turbine predicted by the wake model and measured in LES are used for closed-loop feedback. The controller is tested on two types of regulation signals, “RegA” and “RegD”, obtained from PJM, an independent system operator in the eastern United States. Composite performance scores, which are used by PJM to qualify plants for regulation, are used to evaluate the performance of the controlled wind farm. Our results demonstrate that the controlled wind farm consistently performs well, passing the qualification threshold for all fastacting RegD signals. For the RegA signal, which changes over slower time scales, the controlled wind farm's average performance surpasses the threshold, but further work is needed to enable the controlled system to achieve qualifying performance all of the time.

  2. Changes in fluxes of heat, H2O, CO2 caused by a large wind farm

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Crop Wind Energy Experiment (CWEX) provides a platform to investigate the effect of wind turbines and large wind farms on surface fluxes of momentum, heat, moisture and carbon dioxide (CO2). In 2010 and 2011, eddy covariance flux stations were installed between two lines of turbines at the south...

  3. Supplying Reliable Electricity and Reducing Transmission Requirements by Interconnecting Wind Farms

    NASA Astrophysics Data System (ADS)

    Archer, C. L.; Jacobson, M. Z.

    2007-12-01

    Wind is the world's fastest growing electric energy source. Because it is intermittent, though, wind is not used to supply baseload electric power today. Interconnecting wind farms through the transmission grid is a simple and effective way of reducing deliverable wind power swings caused by wind intermittency. As more farms are interconnected in an array, wind speed correlation among sites decreases and so does the probability that all sites experience the same wind regime at the same time. Consequently, the array behaves more and more similarly to a single farm with steady wind speed and thus steady deliverable wind power. In this study, benefits of interconnecting wind farms were evaluated for 19 sites, located in the Midwestern United States, with annual average wind speeds at 80 m above ground, the hub height of modern wind turbines, greater than 6.9 m/s (class 3 or greater). It was found that an average of 33% and a maximum of 47% of yearly-averaged wind power from interconnected farms can be used as reliable, baseload electric power. Equally significant, interconnecting multiple wind farms to a common point, then connecting that point to a far-away city can allow the long-distance portion of transmission capacity to be reduced, for example, by 20% with only a 1.6% loss of energy. Although most parameters, such as intermittency, improved less than linearly as the number of interconnected sites increased, no saturation of the benefits was found. Thus, the benefits of interconnection continue to increase with more and more interconnected sites.

  4. The structure and strength of public attitudes towards wind farm development

    NASA Astrophysics Data System (ADS)

    Bidwell, David Charles

    A growing social science literature seeks to understand why, despite broad public support for wind energy, proposals for specific projects are often met with strong local opposition. This gap between general and specific attitudes is viewed as a significant obstacle to the deployment of wind energy technologies. This dissertation applies theoretical perspectives and methodological tools from social psychology to provide insights on the structure and strength of attitudes towards the potential development of commercial wind farm in three coastal areas of Michigan. A survey of attitudes was completed by 375 residents in these communities and structural equation modeling was used to explore the relationship among variables. The analysis found that attitudes towards wind farm development are shaped by anticipated economic benefits to the community, but expectations of economic benefit are driven by personal values. Social psychology has long recognized that all attitudes are not created equal. Weak attitudes are fleeting and prone to change, while strong attitudes are stable over time and resistant to change. There are two fundamental paths to strong attitudes: repeated experience with an attitude object or the application of deeply held principles or values to that object. Structural equation models were also used to understand the strength of attitudes among the survey respondents. Both the anticipated effects of wind farm development and personal values were found to influence the strength of attitudes towards wind farms. However, while expectations that wind farm development will have positive effects on the economy bolster two measures of attitude strength (collective identity and importance), these expectations are associated with a decline in a third measure (confidence). A follow-up survey asking identical questions was completed by completed by 187 respondents to the initial survey. Linear regressions models were used to determine the effects of attitude

  5. ENDOW (efficient development of offshore wind farms): modelling wake and boundary layer interactions

    NASA Astrophysics Data System (ADS)

    Barthelmie, Rebecca; Larsen, Gunner; Pryor, Sara; Jørgensen, Hans; Bergström, Hans; Schlez, Wolfgang; Rados, Kostas; Lange, Bernhard; Vølund, Per; Neckelmann, Søren; Mogensen, Søren; Schepers, Gerard; Hegberg, Terry; Folkerts, Luuk; Magnusson, Mikael

    2004-07-01

    While experience gained through the offshore wind energy projects currently operating is valuable, a major uncertainty in estimating power production lies in the prediction of the dynamic links between the atmosphere and wind turbines in offshore regimes. The objective of the ENDOW project was to evaluate, enhance and interface wake and boundary layer models for utilization offshore. The project resulted in a significant advance in the state of the art in both wake and marine boundary layer models, leading to improved prediction of wind speed and turbulence profiles within large offshore wind farms. Use of new databases from existing offshore wind farms and detailed wake profiles collected using sodar provided a unique opportunity to undertake the first comprehensive evaluation of wake models in the offshore environment. The results of wake model performance in different wind speed, stability and roughness conditions relative to observations provided criteria for their improvement. Mesoscale model simulations were used to evaluate the impact of thermal flows, roughness and topography on offshore wind speeds. The model hierarchy developed under ENDOW forms the basis of design tools for use by wind energy developers and turbine manufacturers to optimize power output from offshore wind farms through minimized wake effects and optimal grid connections. The design tools are being built onto existing regional-scale models and wind farm design software which was developed with EU funding and is in use currently by wind energy developers. Copyright

  6. Investigation of wake characteristics in wind farm varying turbulent inflow condition

    NASA Astrophysics Data System (ADS)

    Na, Jisung; Koo, Eunmo; Domingo, Munoz-Esparza; Jin, Emilia Kyung; Linn, Rodman; Lee, Joon Sang

    2016-11-01

    In this study, we investigate the wake characteristics in wind farm varying turbulent property at inlet condition. To solve the flow with wind turbines and its wake, we use large eddy simulation (LES) technique with actuator line method (ALM). The wake characteristics in wind farm is important mainly in performance of wind farm because non-fully recovered wake induced by upstream wind turbines interferes power generation at downstream wind turbines. Turbulent inflow which contains the information of turbulence in atmospheric boundary layer is one of the key factors for describing the wake in wind farm accurately. We perform the quantitative analysis of velocity deficit and turbulent intensity in whole cases. In the comparison between cases with and without turbulent inflow, we observe that wake in case with turbulent inflow is more diffused to span-wise direction. And we analyze the coherent structures behind wind turbines at each row. Through above-analysis, we reveal how the wake is interacted with performance of wind farm. This work was supported by the National Research Foundation of Korea (NRF) Grant funded by the Korean Government (MSIP) (No.2015R1A5A1037668).

  7. Impacts of an offshore wind farm on the lower marine atmosphere

    NASA Astrophysics Data System (ADS)

    Volker, P. J.; Huang, H.; Capps, S. B.; Badger, J.; Hahmann, A. N.; Hall, A. D.

    2013-12-01

    Due to a continuing increase in energy demand and heightened environmental consciousness, the State of California is seeking out more environmentally-friendly energy resources. Strong and persistent winds along California's coast can be harnessed effectively by current wind turbine technology, providing a promising source of alternative energy. Using an advanced wind farm parameterization implemented in the Weather Research & Forecast model, we investigate the potential impacts of a large offshore wind farm on the lower marine atmosphere. Located offshore of the Sonoma Coast in northern California, this theoretical wind farm includes 200-7 megawatt, 125 m hub height wind turbines which are able to provide a total of 1.4 TW of power for use in neighboring cities. The wind turbine model (i.e., the Explicit Wake Parameterization originally developed at the Danish Technical University) acts as a source of drag where the sub-grid scale velocity deficit expansion is explicitly described. A swath consisting of hub-height velocity deficits and temperature and moisture anomalies extends more than 100 km downstream of the wind farm location. The presence of the large modern wind farm also creates flow distortion upstream in conjunction with an enhanced vertical momentum and scalar transport.

  8. Effect of wind turbine response time on optimal dynamic induction control of wind farms

    NASA Astrophysics Data System (ADS)

    Munters, Wim; Meyers, Johan

    2016-09-01

    In this work, we extend recent research efforts on induction-based optimal control in large-eddy simulations of wind farms in the turbulent atmospheric boundary layer. More precisely, we investigate the effect of wind turbine response time to requested power setpoints on achievable power gains. We do this by including a time-filtering of the thrust coefficient setpoints in the optimal control framework. We consider simulation cases restricted to underinduction compared to the Betz limit, as well as cases that also allow overinduction. Optimization results show that, except for the most restrictive underinductive slow-response case, all cases still yield increases in energy extraction in the order of 10% and more.

  9. Effects of an Offshore Wind Farm (OWF) on the Common Shore Crab Carcinus maenas: Tagging Pilot Experiments in the Lillgrund Offshore Wind Farm (Sweden)

    PubMed Central

    Langhamer, Olivia; Holand, Håkon; Rosenqvist, Gunilla

    2016-01-01

    Worldwide growth of offshore renewable energy production will provide marine organisms with new hard substrate for colonization in terms of artificial reefs. The artificial reef effect is important when planning offshore installations since it can create habitat enhancement. Wind power is the most advanced technology within offshore renewable energy sources and there is an urgent need to study its impacts on the marine environment. To test the hypothesis that offshore wind power increases the abundance of reef species relative to a reference area, we conduct an experiment on the model species common shore crab (Carcinus maenas).Overall, 3962 crabs were captured, observed, marked and released in 2011 and 1995 crabs in 2012. Additionally, carapace size, sex distribution, color morphs and body condition was recorded from captured crabs. We observed very low recapture rates at all sites during both years which made evaluating differences in population sizes very difficult. However, we were able to estimate population densities from the capture record for all three sites. There was no obvious artificial reef effect in the Lillgrund wind farm, but a spill-over effect to nearby habitats cannot be excluded. We could not find any effect of the wind farm on either, morphs, sex distribution or condition of the common shore crab. Our study found no evidence that Lillgrund wind farm has a negative effect on populations of the common shore crab. This study provides the first quantitative and experimental data on the common shore crab in relation to offshore wind farms. PMID:27780212

  10. Array Effects in Large Wind Farms. Cooperative Research and Development Final Report, CRADA Number CRD-09-343

    SciTech Connect

    Moriarty, Patrick

    2016-02-23

    The effects of wind turbine wakes within operating wind farms have a substantial impact on the overall energy production from the farm. The current generation of models drastically underpredicts the impact of these wakes leading to non-conservative estimates of energy capture and financial losses to wind farm operators and developers. To improve these models, detailed research of operating wind farms is necessary. Rebecca Barthelmie of Indiana University is a world leader of wind farm wakes effects and would like to partner with NREL to help improve wind farm modeling by gathering additional wind farm data, develop better models and increase collaboration with European researchers working in the same area. This is currently an active area of research at NREL and the capabilities of both parties should mesh nicely.

  11. Hot air ablowin! 'Media-speak', social conflict, and the Australian 'decoupled' wind farm controversy.

    PubMed

    Hindmarsh, Richard

    2014-04-01

    In work in science, technology, and society social conflict around wind farms has a growing profile, not least because it draws our attention to two key interrelated themes: 'science, technology and governance' and 'socio-technological systems'. In this article on Australian wind farm development and siting, these themes are highlighted in contexts of sustainability, legitimacy, and competency for policy effectiveness. There is enduring social conflict around wind farms at the local community level, but little government understanding of this conflict or willingness to respond adequately to resolve it. This article examines the conflict through the lens of print media analysis. A key finding of the five identified is that people seeing wind farms as spoiling a sense of place is a primary cause of enduring social conflict at the local community level around wind farms, alongside significant environmental issues and inadequate community engagement; this finding also indicates a central reason for the highly problematic state of Australian wind energy transitions. In turn, by identifying this problematic situation as one of a significantly 'decoupled' and 'dysfunctional' condition of the Australian socio-technological wind farm development and siting system, I suggest remedies including those of a deliberative nature that also respond to the Habermas-Mouffe debate. These inform a socio-technical siting approach or pathway to better respect and navigate contested landscapes for enhanced renewable energy transitions at the local level.

  12. Modelling potential changes in marine biogeochemistry due to large-scale offshore wind farms

    NASA Astrophysics Data System (ADS)

    van der Molen, Johan; Rees, Jon; Limpenny, Sian

    2013-04-01

    Large-scale renewable energy generation by offshore wind farms may lead to changes in marine ecosystem processes through the following mechanism: 1) wind-energy extraction leads to a reduction in local surface wind speeds; 2) these lead to a reduction in the local wind wave height; 3) as a consequence there's a reduction in SPM resuspension and concentrations; 4) this results in an improvement in under-water light regime, which 5) may lead to increased primary production, which subsequently 6) cascades through the ecosystem. A three-dimensional coupled hydrodynamics-biogeochemistry model (GETM_ERSEM) was used to investigate this process for a hypothetical wind farm in the central North Sea, by running a reference scenario and a scenario with a 10% reduction (as was found in a case study of a small farm in Danish waters) in surface wind velocities in the area of the wind farm. The ERSEM model included both pelagic and benthic processes. The results showed that, within the farm area, the physical mechanisms were as expected, but with variations in the magnitude of the response depending on the ecosystem variable or exchange rate between two ecosystem variables (3-28%, depending on variable/rate). Benthic variables tended to be more sensitive to the changes than pelagic variables. Reduced, but noticeable changes also occurred for some variables in a region of up to two farm diameters surrounding the wind farm. An additional model run in which the 10% reduction in surface wind speed was applied only for wind speeds below the generally used threshold of 25 m/s for operational shut-down showed only minor differences from the run in which all wind speeds were reduced. These first results indicate that there is potential for measurable effects of large-scale offshore wind farms on the marine ecosystem, mainly within the farm but for some variables up to two farm diameters away. However, the wave and SPM parameterisations currently used in the model are crude and need to be

  13. Measurements of Heat Flux Differences Within a Large Wind Farm During the 2013 Crop/Wind-Energy Experiment (CWEX-13)

    NASA Astrophysics Data System (ADS)

    Rajewski, D. A.

    2015-12-01

    Wind farms are an important resource for electrical generation in the Central U.S., however with each installation there are many poorly documented interactions with the local and surrounding environment. The impact of wind farms on surface microclimate is largely understood conceptually using numerical or wind tunnel models or ex situ satellite-detected changes. Measurements suitable for calibration of numerical simulations are few and of limited applicability but are urgently needed to improve parameterization of wind farm aerodynamics influenced by the diurnal evolution of the boundary layer. Among large eddy simulations of wind farm wakes in thermally stable stratification, there are discrepancies on the influence of turbine-induced mixing on the surface heat flux. We provide measurements from seven surface flux stations, vertical profiling LiDARs located upwind and downwind of turbines, and SCADA measurements from turbines during the 2013 Crop Wind Energy Experiment (CWEX-13) as the best evidence for the variability of turbine induced heat flux within a large wind farm. Examination of ambient conditions (wind direction, wind veer, and thermal stratification) and on turbine operation factors (hub-height wind speed, normalized power) reveal conditions that lead to the largest modification of heat flux. Our results demonstrate the highest flux change from the reference station to be where the leading few lines of turbines influence the surface. Under stably stratified conditions turbine-scale turbulence is highly efficient at bringing warmer air aloft to the surface, leading to an increase in downward heat flux. Conversely we see that the combination of wakes from several lines of turbines reduces the flux contrast from the reference station. In this regime of deep wind-farm flow, wake turbulence is similar in scale and intensity to the reference conditions. These analysis tools can be extended to other turbine SCADA and microclimate variables (e.g. temperature

  14. Wind Turbine Wake Variability in a Large Wind Farm, Observed by Scanning Lidar

    NASA Astrophysics Data System (ADS)

    Lundquist, J. K.; Xiaoxia, G.; Aitken, M.; Quelet, P. T.; Rana, J.; Rhodes, M. E.; St Martin, C. M.; Tay, K.; Worsnop, R.; Irvin, S.; Rajewski, D. A.; Takle, E. S.

    2014-12-01

    Although wind turbine wake modeling is critical for accurate wind resource assessment, operational forecasting, and wind plant optimization, verification of such simulations is currently constrained by sparse datasets taken in limited atmospheric conditions, often of single turbines in isolation. To address this knowledge gap, our team deployed a WINDCUBE 200S scanning lidar in a 300-MW operating wind farm as part of the CWEX-13 field experiment. The lidar was deployed ~2000 m from a row of four turbines, such that wakes from multiple turbines could be sampled with horizontal scans. Twenty minutes of every hour were devoted to horizontal scans at ½ degree resolution at six different elevation angles. Twenty-five days of data were collected, with wind speeds at hub height ranging from quiescent to 14 m/s, and atmospheric stability varying from unstable to strongly stable. The example scan in Fig. 1a shows wakes from a row of four turbines propagating to the northwest. This extensive wake dataset is analyzed based on the quantitative approach of Aitken et al. (J. Atmos. Ocean. Technol. 2014), who developed an automated wake detection algorithm to characterize wind turbine wakes from scanning lidar data. We have extended the Aitken et al. (2014) method to consider multiple turbines in a single scan in order to classify the large numbers of wakes observed in the CWEX-13 dataset (Fig. 1b) during southerly flow conditions. The presentation will explore the variability of wake characteristics such as the velocity deficit and the wake width. These characteristics vary with atmospheric stability, atmospheric turbulence, and inflow wind speed. We find that the strongest and most persistent wakes occur at low to moderate wind speeds (region 2 of the turbine power curve) in stable conditions. We also present evidence that, in stable conditions with strong changes of wind direction with height, wakes propagate in different directions at different elevations above the surface

  15. Growian 2 for more wind power and first European solar farm inaugurated

    NASA Technical Reports Server (NTRS)

    1980-01-01

    A wind power installation with a power of five megawatts to be used in the Federal Republic of Germany is described. The first European solar farm was inaugurated in Madrid, and its operation is discussed.

  16. Monitoring and Mitigation Alternatives for Protection of North Atlantic Right Whales during Offshore Wind Farm Installation

    SciTech Connect

    Carlson, Thomas J.; Halvorsen, Michele B.; Matzner, Shari; Copping, Andrea E.; Stavole, Jessica

    2012-09-01

    Progress report on defining and determining monitoring and mitigation measures for protecting North Atlantic Right Whales from the effects of pile driving and other activities associated with installation of offshore wind farms.

  17. Barriers to movement: Modelling energetic costs of avoiding marine wind farms amongst breeding seabirds.

    PubMed

    Masden, Elizabeth A; Haydon, Daniel T; Fox, Anthony D; Furness, Robert W

    2010-07-01

    Proposals for wind farms in areas of known importance for breeding seabirds highlight the need to understand the impacts of these structures. Using an energetic modelling approach, we examine the effects of wind farms as barriers to movement on seabirds of differing morphology. Additional costs, expressed in relation to typical daily energetic expenditures, were highest per unit flight for seabirds with high wing loadings, such as cormorants. Taking species-specific differences into account, costs were relatively higher in terns, due to the high daily frequency of foraging flights. For all species, costs of extra flight to avoid a wind farm appear much less than those imposed by low food abundance or adverse weather, although such costs will be additive to these. We conclude that adopting a species-specific approach is essential when assessing the impacts of wind farms on breeding seabird populations, to fully anticipate the effects of avoidance flights.

  18. Risk formulation for the sonic effects of offshore wind farms on fish in the EU region.

    PubMed

    Kikuchi, Ryunosuke

    2010-02-01

    In 2007, European leaders agreed to source 20% of their energy needs from renewable energy; since that time, offshore wind farms have been receiving attention in the European Union (EU). In 2008, the European Community submitted a proposal to the United Nations Environment Program (UNEP) in order to combat marine noise pollution. In consideration of these facts, the present paper aims to deduce a preliminary hypothesis and its formulation for the effect of offshore wind farm noise on fish. The following general picture is drawn: the short-term potential impact during pre-construction; the short-term intensive impact during construction; and the physiological and/or masking effects that may occur over a long period while the wind farm is in operation. The EU's proposal to UNEP includes noise databases that list the origins of man-made sounds; it is advisable that offshore wind farms should be listed in the noise databases in order to promote rational environment management.

  19. Multi-Objective Random Search Algorithm for Simultaneously Optimizing Wind Farm Layout and Number of Turbines

    NASA Astrophysics Data System (ADS)

    Feng, Ju; Shen, Wen Zhong; Xu, Chang

    2016-09-01

    A new algorithm for multi-objective wind farm layout optimization is presented. It formulates the wind turbine locations as continuous variables and is capable of optimizing the number of turbines and their locations in the wind farm simultaneously. Two objectives are considered. One is to maximize the total power production, which is calculated by considering the wake effects using the Jensen wake model combined with the local wind distribution. The other is to minimize the total electrical cable length. This length is assumed to be the total length of the minimal spanning tree that connects all turbines and is calculated by using Prim's algorithm. Constraints on wind farm boundary and wind turbine proximity are also considered. An ideal test case shows the proposed algorithm largely outperforms a famous multi-objective genetic algorithm (NSGA-II). In the real test case based on the Horn Rev 1 wind farm, the algorithm also obtains useful Pareto frontiers and provides a wide range of Pareto optimal layouts with different numbers of turbines for a real-life wind farm developer.

  20. Atmospheric stability effects on wind farm performance using large-eddy simulation

    NASA Astrophysics Data System (ADS)

    Archer, C. L.; Ghaisas, N.; Xie, S.

    2014-12-01

    Atmospheric stability has been recently found to have significant impacts on wind farm performance, especially since offshore and onshore wind farms are known to operate often under non-neutral conditions. Recent field observations have revealed that changes in stability are accompanied by changes in wind speed, direction, and turbulent kinetic energy (TKE). In order to isolate the effects of stability, large-eddy simulations (LES) are performed under neutral, stable, and unstable conditions, keeping the wind speed and direction unchanged at a fixed height. The Lillgrund wind farm, comprising of 48 turbines, is studied in this research with the Simulator for Offshore/Onshore Wind Farm Applications (SOWFA) developed by the National Renewable Energy Laboratory. Unlike most previous numerical simulations, this study does not impose periodic boundary conditions and therefore is ideal for evaluating the effects of stability in large, but finite, wind farms. Changes in power generation, velocity deficit, rate of wake recovery, TKE, and surface temperature are quantified as a function of atmospheric stability. The sensitivity of these results to wind direction is also discussed.

  1. Simulation based study of the effect of ocean waves on floating wind farm

    NASA Astrophysics Data System (ADS)

    Yang, Di; Meneveau, Charles; Shen, Lian

    2012-11-01

    A hybrid numerical capability is developed for the simulation of floating wind farm offshore, in which large-eddy simulation is performed for wind turbulence, and a potential flow based method is used for the simulation of ocean wavefield. The wind and wave simulations are coupled through a two-way feedback scheme. The effect of wind turbines on the wind field is represented by an actuator disk model. A variety of fully-developed and fetch-limited wind-sea conditions are considered in the study. The simulation results indicate that the offshore wind farm obtains a higher wind power extraction rate under the fully-developed wind-sea condition compared with the fetch-limited condition. This higher extraction rate is caused by the faster propagating waves and the lower sea-surface resistance on the wind when the wind-seas are fully developed. Such wave effect becomes more prominent when the turbine density of the wind farm increases. DY and LS acknowledge the support of NSF-CBET-1133700. CM acknowledges the support of NSF-CBET-1133800 and NSF-AGS-1045189.

  2. 78 FR 6316 - Big Blue Wind Farm, LLC, et al.; Notice of Effectiveness of Exempt Wholesale Generator Status

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-30

    ... Energy Regulatory Commission Big Blue Wind Farm, LLC, et al.; Notice of Effectiveness of Exempt Wholesale Generator Status Docket Nos. Big Blue Wind Farm, LLC EG13-1-000 Calpine Bosque Energy Center, LLC EG13-2-000 Homer City Generation, L.P EG13-3-000 Texas Dispatchable Wind 1, LLC EG13-4-000 Blue Creek Wind Farm...

  3. Quantifying array losses due to spacing and staggering in offshore wind farms (Invited)

    NASA Astrophysics Data System (ADS)

    Archer, C. L.; Mirzaeisefat, S.; Lee, S.; Xie, S.

    2013-12-01

    The layout of wind turbines can have an impact on the power production of a wind farm. Design variables that define the layout of wind turbines within a wind farm include: orientation of the rows with respect to the prevailing wind direction, size and shape of the wind farm, spacing between turbines, and alignment of the turbines (i.e., whether in-line or staggered with one another). There are no universal layout recommendations for offshore wind farms, partly because isolating the contribution of each individual design variable is impossible at existing offshore wind farms, where multiple effects overlap non-linearly on one another, and partly because analyzing the sensitivity to design variables requires sophisticated and computer-intensive numerical codes, such as large-eddy simulations (LES), that can simulate the small-scale turbulent features of turbine wakes. The National Renewable Energy Laboratory (NREL) developed the only publicly available and open-source LES code that is capable of resolving wind turbine blades as rotating actuator lines (not fixed disks), includes both neutral and unstable atmospheric conditions (stable case is currently under development), and does not rely on periodic boundary conditions. This code, named Simulator for Offshore/Onshore Wind Farm Applications (SOWFA), is based on OpenFOAM and has been used successfully in the past for turbulent wake simulations. Here we address the issue of quantifying two design variables: turbine spacing (both along and across the prevailing wind direction) and alignment (in-line or staggered for consecutive rows). SOWFA is used to simulate an existing offshore wind farm in Lillgrund (Sweden), consisting of 48 Siemens 2.3 MW turbines with spacing of 3.2D across and 4.3D along the prevailing wind direction and without staggering, where D is the turbine diameter (93 m). This spacing is exceptionally tight, to our knowledge the tightest of all modern wind farms. While keeping the area and the shape of

  4. Quantifying array losses due to spacing and staggering in offshore wind farms (Invited)

    NASA Astrophysics Data System (ADS)

    Archer, C. L.; Mirzaeisefat, S.; Lee, S.; Xie, S.

    2011-12-01

    The layout of wind turbines can have an impact on the power production of a wind farm. Design variables that define the layout of wind turbines within a wind farm include: orientation of the rows with respect to the prevailing wind direction, size and shape of the wind farm, spacing between turbines, and alignment of the turbines (i.e., whether in-line or staggered with one another). There are no universal layout recommendations for offshore wind farms, partly because isolating the contribution of each individual design variable is impossible at existing offshore wind farms, where multiple effects overlap non-linearly on one another, and partly because analyzing the sensitivity to design variables requires sophisticated and computer-intensive numerical codes, such as large-eddy simulations (LES), that can simulate the small-scale turbulent features of turbine wakes. The National Renewable Energy Laboratory (NREL) developed the only publicly available and open-source LES code that is capable of resolving wind turbine blades as rotating actuator lines (not fixed disks), includes both neutral and unstable atmospheric conditions (stable case is currently under development), and does not rely on periodic boundary conditions. This code, named Simulator for Offshore/Onshore Wind Farm Applications (SOWFA), is based on OpenFOAM and has been used successfully in the past for turbulent wake simulations. Here we address the issue of quantifying two design variables: turbine spacing (both along and across the prevailing wind direction) and alignment (in-line or staggered for consecutive rows). SOWFA is used to simulate an existing offshore wind farm in Lillgrund (Sweden), consisting of 48 Siemens 2.3 MW turbines with spacing of 3.2D across and 4.3D along the prevailing wind direction and without staggering, where D is the turbine diameter (93 m). This spacing is exceptionally tight, to our knowledge the tightest of all modern wind farms. While keeping the area and the shape of

  5. Turbulent kinetics of a large wind farm and their impact in the neutral boundary layer

    DOE PAGES

    Na, Ji Sung; Koo, Eunmo; Munoz-Esparza, Domingo; ...

    2015-12-28

    High-resolution large-eddy simulation of the flow over a large wind farm (64 wind turbines) is performed using the HIGRAD/FIRETEC-WindBlade model, which is a high-performance computing wind turbine–atmosphere interaction model that uses the Lagrangian actuator line method to represent rotating turbine blades. These high-resolution large-eddy simulation results are used to parameterize the thrust and power coefficients that contain information about turbine interference effects within the wind farm. Those coefficients are then incorporated into the WRF (Weather Research and Forecasting) model in order to evaluate interference effects in larger-scale models. In the high-resolution WindBlade wind farm simulation, insufficient distance between turbines createsmore » the interference between turbines, including significant vertical variations in momentum and turbulent intensity. The characteristics of the wake are further investigated by analyzing the distribution of the vorticity and turbulent intensity. Quadrant analysis in the turbine and post-turbine areas reveals that the ejection motion induced by the presence of the wind turbines is dominant compared to that in the other quadrants, indicating that the sweep motion is increased at the location where strong wake recovery occurs. Regional-scale WRF simulations reveal that although the turbulent mixing induced by the wind farm is partly diffused to the upper region, there is no significant change in the boundary layer depth. The velocity deficit does not appear to be very sensitive to the local distribution of turbine coefficients. However, differences of about 5% on parameterized turbulent kinetic energy were found depending on the turbine coefficient distribution. Furthermore, turbine coefficients that consider interference in the wind farm should be used in wind farm parameterization for larger-scale models to better describe sub-grid scale turbulent processes.« less

  6. Turbulent kinetics of a large wind farm and their impact in the neutral boundary layer

    SciTech Connect

    Na, Ji Sung; Koo, Eunmo; Munoz-Esparza, Domingo; Jin, Emilia Kyung; Linn, Rodman; Lee, Joon Sang

    2015-12-28

    High-resolution large-eddy simulation of the flow over a large wind farm (64 wind turbines) is performed using the HIGRAD/FIRETEC-WindBlade model, which is a high-performance computing wind turbine–atmosphere interaction model that uses the Lagrangian actuator line method to represent rotating turbine blades. These high-resolution large-eddy simulation results are used to parameterize the thrust and power coefficients that contain information about turbine interference effects within the wind farm. Those coefficients are then incorporated into the WRF (Weather Research and Forecasting) model in order to evaluate interference effects in larger-scale models. In the high-resolution WindBlade wind farm simulation, insufficient distance between turbines creates the interference between turbines, including significant vertical variations in momentum and turbulent intensity. The characteristics of the wake are further investigated by analyzing the distribution of the vorticity and turbulent intensity. Quadrant analysis in the turbine and post-turbine areas reveals that the ejection motion induced by the presence of the wind turbines is dominant compared to that in the other quadrants, indicating that the sweep motion is increased at the location where strong wake recovery occurs. Regional-scale WRF simulations reveal that although the turbulent mixing induced by the wind farm is partly diffused to the upper region, there is no significant change in the boundary layer depth. The velocity deficit does not appear to be very sensitive to the local distribution of turbine coefficients. However, differences of about 5% on parameterized turbulent kinetic energy were found depending on the turbine coefficient distribution. Furthermore, turbine coefficients that consider interference in the wind farm should be used in wind farm parameterization for larger-scale models to better describe sub-grid scale turbulent processes.

  7. A new concept for superconducting DC transmission from a wind farm

    NASA Astrophysics Data System (ADS)

    Østergaard, Jacob; Tønnesen, Ole; Kaas-Pedersen, Jørgen; Nielsen, Arne Hejde; Træholt, Chresten

    2002-08-01

    Projects with large offshore wind farms (up to 500 MW) are in progress. Connecting the parks to the power grid with conventional AC transmission technique is difficult due to non-controllable power flow and voltage stability problems. A new concept for connecting remotely located wind farms is suggested and described. The concept is based on combining superconducting DC power transmission and cooled power electronic.

  8. Economic analysis of the use of wind power for electrical generation on midwestern dairy farms

    SciTech Connect

    Reinemann, D.J.; Koegel, R.G.; Straub, R.J.

    1982-12-01

    The optimum size WECS for dairy farm electrical production, and return on investment thereof depend greatly on utility regulations, load management techniques, and the future of the economy. Seasonal and daily fluctuations in available wind power and electric demand together with existing or expected rate schedules must be considered in choosing an appropriate load management system. An economic analysis is done investigating optimal system size and use strategies for the use of wind generated electrical power on midwestern dairy farms.

  9. Building a stakeholder's vision of an offshore wind-farm project: A group modeling approach.

    PubMed

    Château, Pierre-Alexandre; Chang, Yang-Chi; Chen, Hsin; Ko, Tsung-Ting

    2012-03-15

    This paper describes a Group Model Building (GMB) initiative that was designed to discuss the various potential effects that an offshore wind-farm may have on its local ecology and socioeconomic development. The representatives of various organizations in the study area, Lu-Kang, Taiwan, have held several meetings, and structured debates have been organized to promote the emergence of a consensual view on the main issues and their implications. A System Dynamics (SD) model has been built and corrected iteratively with the participants through the GMB process. The diverse interests within the group led the process toward the design of multifunctional wind-farms with different modalities. The scenario analyses, using the SD model under various policies, including no wind-farm policy, objectively articulates the vision of the local stakeholders. The results of the SD simulations show that the multifunctional wind-farms may have superior economic effects and the larger wind-farms with bird corridors could reduce ecological impact. However, the participants of the modeling process did not appreciate any type of offshore wind-farm development when considering all of the identified key factors of social acceptance. The insight gained from the study can provide valuable information to actualize feasible strategies for the green energy technique to meet local expectations.

  10. Minimizing Collision Risk Between Migrating Raptors and Marine Wind Farms: Development of a Spatial Planning Tool

    NASA Astrophysics Data System (ADS)

    Baisner, Anette Jægerfeldt; Andersen, Jonas Lembcke; Findsen, Anders; Yde Granath, Simon Wilhelm; Madsen, Karin Ølgaard; Desholm, Mark

    2010-11-01

    An increased focus on renewable energy has led to the planning and construction of marine wind farms in Europe. Since several terrestrial studies indicate that raptors are especially susceptible to wind turbine related mortality, a Spatial Planning Tool is needed so that wind farms can be sited, in an optimal way, to minimize risk of collisions. Here we use measurements of body mass, wingspan and wing area of eight European raptor species, to calculate their Best Glide Ratio (BGR). The BGR was used to construct a linear equation, which, by the use of initial take-off altitude, could be used to calculate a Theoretical Maximum Distance (TMD) from the coast, attained by these soaring-gliding raptor species. If the nearest turbine, of future marine wind farms, is placed farther away from the coast than the estimated TMD, the collision risk between the turbine blades and these gliding raptors will be minimized. The tool was demonstrated in a case study at the Rødsand II wind farm in Denmark. Data on raptor migration altitude were gathered by radar. From the TMD attained by registered soaring-gliding raptors in the area, we concluded that the Rødsand II wind farm is not sited ideally, from an ornithological point of view, as potentially all three registered species are at risk of gliding through the area swept by the turbine rotor blades, and thereby at risk of colliding with the wind turbines.

  11. Minimizing collision risk between migrating raptors and marine wind farms: development of a spatial planning tool.

    PubMed

    Baisner, Anette Jaegerfeldt; Andersen, Jonas Lembcke; Findsen, Anders; Yde Granath, Simon Wilhelm; Madsen, Karin Olgaard; Desholm, Mark

    2010-11-01

    An increased focus on renewable energy has led to the planning and construction of marine wind farms in Europe. Since several terrestrial studies indicate that raptors are especially susceptible to wind turbine related mortality, a Spatial Planning Tool is needed so that wind farms can be sited, in an optimal way, to minimize risk of collisions. Here we use measurements of body mass, wingspan and wing area of eight European raptor species, to calculate their Best Glide Ratio (BGR). The BGR was used to construct a linear equation, which, by the use of initial take-off altitude, could be used to calculate a Theoretical Maximum Distance (TMD) from the coast, attained by these soaring-gliding raptor species. If the nearest turbine, of future marine wind farms, is placed farther away from the coast than the estimated TMD, the collision risk between the turbine blades and these gliding raptors will be minimized. The tool was demonstrated in a case study at the Rødsand II wind farm in Denmark. Data on raptor migration altitude were gathered by radar. From the TMD attained by registered soaring-gliding raptors in the area, we concluded that the Rødsand II wind farm is not sited ideally, from an ornithological point of view, as potentially all three registered species are at risk of gliding through the area swept by the turbine rotor blades, and thereby at risk of colliding with the wind turbines.

  12. Enhanced Kalman Filtering for a 2D CFD NS Wind Farm Flow Model

    NASA Astrophysics Data System (ADS)

    Doekemeijer, B. M.; van Wingerden, J. W.; Boersma, S.; Pao, L. Y.

    2016-09-01

    Wind turbines are often grouped together for financial reasons, but due to wake development this usually results in decreased turbine lifetimes and power capture, and thereby an increased levelized cost of energy (LCOE). Wind farm control aims to minimize this cost by operating turbines at their optimal control settings. Most state-of-the-art control algorithms are open-loop and rely on low fidelity, static flow models. Closed-loop control relying on a dynamic model and state observer has real potential to further decrease wind's LCOE, but is often too computationally expensive for practical use. In this paper two time-efficient Kalman filter (KF) variants are outlined incorporating the medium fidelity, dynamic flow model “WindFarmSimulator” (WFSim). This model relies on a discretized set of Navier-Stokes equations in two dimensions to predict the flow in wind farms at low computational cost. The filters implemented are an Ensemble KF and an Approximate KF. Simulations in which a high fidelity simulation model represents the true wind farm show that these filters are 101 —102 times faster than a regular KF with comparable or better performance, correcting for wake dynamics that are not modeled in WFSim (noticeably, wake meandering and turbine hub effects). This is a first big step towards real-time closed-loop control for wind farms.

  13. Energy Storage and Reactive Power Compensator in a Large Wind Farm: Preprint

    SciTech Connect

    Muljadi, E.; Butterfield, C. P.; Yinger, R.; Romanowitz, H.

    2003-10-01

    The size of wind farm power systems is increasing, and so is the number of wind farms contributing to the power systems network. The size of wind turbines is also increasing--from less than 1 MW a few years ago to the 2- to 3-MW machines being installed today and the 5-MW machines under development. The interaction of the wind farm, energy storage, reactive power compensation, and the power system network is being investigated. Because the loads and the wind farms' output fluctuate during the day, the use of energy storage and reactive power compensation is ideal for the power system network. Energy storage and reactive power compensation can minimize real/reactive power imbalances that can affect the surrounding power system. In this paper, we will show how the contribution of wind farms affects the power distribution network and how the power distribution network, energy storage, and reactive power compensation interact when the wind changes. We will also investigate the size of the components in relation to each other and to the power system.

  14. Patterns of migrating soaring migrants indicate attraction to marine wind farms.

    PubMed

    Skov, Henrik; Desholm, Mark; Heinänen, Stefan; Kahlert, Johnny A; Laubek, Bjarke; Jensen, Niels Einar; Žydelis, Ramūnas; Jensen, Bo Præstegaard

    2016-12-01

    Monitoring of bird migration at marine wind farms has a short history, and unsurprisingly most studies have focused on the potential for collisions. Risk for population impacts may exist to soaring migrants such as raptors with K-strategic life-history characteristics. Soaring migrants display strong dependence on thermals and updrafts and an affinity to land areas and islands during their migration, a behaviour that creates corridors where raptors move across narrow straits and sounds and are attracted to islands. Several migration corridors for soaring birds overlap with the development regions for marine wind farms in NW Europe. However, no empirical data have yet been available on avoidance or attraction rates and behavioural reactions of soaring migrants to marine wind farms. Based on a post-construction monitoring study, we show that all raptor species displayed a significant attraction behaviour towards a wind farm. The modified migratory behaviour was also significantly different from the behaviour at nearby reference sites. The attraction was inversely related to distance to the wind farm and was primarily recorded during periods of adverse wind conditions. The attraction behaviour suggests that migrating raptor species are far more at risk of colliding with wind turbines at sea than hitherto assessed.

  15. International Collaboration on Offshore Wind Energy Under IEA Annex XXIII

    SciTech Connect

    Musial, W.; Butterfield, S.; Lemming, J.

    2005-11-01

    This paper defines the purpose of IEA Annex XXIII, the International Collaboration on Offshore Wind Energy. This international collaboration through the International Energy Agency (IEA) is an efficient forum from which to advance the technical and environmental experiences collected from existing offshore wind energy projects, as well as the research necessary to advance future technology for deep-water wind energy technology.

  16. Atmospheric Stability Impacts on Power Curves of Tall Wind Turbines - An Analysis of a West Coast North American Wind Farm

    SciTech Connect

    Wharton, S; Lundquist, J K

    2010-02-22

    Tall wind turbines, with hub heights at 80 m or above, can extract large amounts of energy from the atmosphere because they are likely to encounter higher wind speeds, but they face challenges given the complex nature of wind flow and turbulence at these heights in the boundary layer. Depending on whether the boundary layer is stable, neutral, or convective, the mean wind speed, direction, and turbulence properties may vary greatly across the tall turbine swept area (40 to 120 m AGL). This variability can cause tall turbines to produce difference amounts of power during time periods with identical hub height wind speeds. Using meteorological and power generation data from a West Coast North American wind farm over a one-year period, our study synthesizes standard wind park observations, such as wind speed from turbine nacelles and sparse meteorological tower observations, with high-resolution profiles of wind speed and turbulence from a remote sensing platform, to quantify the impact of atmospheric stability on power output. We first compare approaches to defining atmospheric stability. The standard, limited, wind farm operations enable the calculation only of a wind shear exponent ({alpha}) or turbulence intensity (I{sub U}) from cup anemometers, while the presence at this wind farm of a SODAR enables the direct observation of turbulent kinetic energy (TKE) throughout the turbine rotor disk. Additionally, a nearby research meteorological station provided observations of the Obukhov length, L, a direct measure of atmospheric stability. In general, the stability parameters {alpha}, I{sub U}, and TKE are in high agreement with the more physically-robust L, with TKE exhibiting the best agreement with L. Using these metrics, data periods are segregated by stability class to investigate power performance dependencies. Power output at this wind farm is highly correlated with atmospheric stability during the spring and summer months, while atmospheric stability exerts

  17. Improved electrical load match in California by combining solar thermal power plants with wind farms

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The ability of wind and solar electrical energy generation to match the current utility electrical load in California was analyzed. We compared the renewable electrical generation and the utility load in California using actual hourly wind farm data at two different locations and predicted hourly p...

  18. Integrative modeling and novel particle swarm-based optimal design of wind farms

    NASA Astrophysics Data System (ADS)

    Chowdhury, Souma

    To meet the energy needs of the future, while seeking to decrease our carbon footprint, a greater penetration of sustainable energy resources such as wind energy is necessary. However, a consistent growth of wind energy (especially in the wake of unfortunate policy changes and reported under-performance of existing projects) calls for a paradigm shift in wind power generation technologies. This dissertation develops a comprehensive methodology to explore, analyze and define the interactions between the key elements of wind farm development, and establish the foundation for designing high-performing wind farms. The primary contribution of this research is the effective quantification of the complex combined influence of wind turbine features, turbine placement, farm-land configuration, nameplate capacity, and wind resource variations on the energy output of the wind farm. A new Particle Swarm Optimization (PSO) algorithm, uniquely capable of preserving population diversity while addressing discrete variables, is also developed to provide powerful solutions towards optimizing wind farm configurations. In conventional wind farm design, the major elements that influence the farm performance are often addressed individually. The failure to fully capture the critical interactions among these factors introduces important inaccuracies in the projected farm performance and leads to suboptimal wind farm planning. In this dissertation, we develop the Unrestricted Wind Farm Layout Optimization (UWFLO) methodology to model and optimize the performance of wind farms. The UWFLO method obviates traditional assumptions regarding (i) turbine placement, (ii) turbine-wind flow interactions, (iii) variation of wind conditions, and (iv) types of turbines (single/multiple) to be installed. The allowance of multiple turbines, which demands complex modeling, is rare in the existing literature. The UWFLO method also significantly advances the state of the art in wind farm optimization by

  19. Assessing the impact of marine wind farms on birds through movement modelling

    PubMed Central

    Masden, Elizabeth A.; Reeve, Richard; Desholm, Mark; Fox, Anthony D.; Furness, Robert W.; Haydon, Daniel T.

    2012-01-01

    Advances in technology and engineering, along with European Union renewable energy targets, have stimulated a rapid growth of the wind power sector. Wind farms contribute to carbon emission reductions, but there is a need to ensure that these structures do not adversely impact the populations that interact with them, particularly birds. We developed movement models based on observed avoidance responses of common eider Somateria mollissima to wind farms to predict, and identify potential measures to reduce, impacts. Flight trajectory data that were  collected post-construction of the Danish Nysted offshore wind farm were used to parameterize competing models of bird movements around turbines. The model most closely fitting the observed data incorporated individual variation in the minimum distance at which birds responded to the turbines. We show how such models can contribute to the spatial planning of wind farms by assessing their extent, turbine spacing and configurations on the probability of birds passing between the turbines. Avian movement models can make new contributions to environmental assessments of wind farm developments, and provide insights into how to reduce impacts that can be identified at the planning stage. PMID:22552921

  20. Assessing the impact of marine wind farms on birds through movement modelling.

    PubMed

    Masden, Elizabeth A; Reeve, Richard; Desholm, Mark; Fox, Anthony D; Furness, Robert W; Haydon, Daniel T

    2012-09-07

    Advances in technology and engineering, along with European Union renewable energy targets, have stimulated a rapid growth of the wind power sector. Wind farms contribute to carbon emission reductions, but there is a need to ensure that these structures do not adversely impact the populations that interact with them, particularly birds. We developed movement models based on observed avoidance responses of common eider Somateria mollissima to wind farms to predict, and identify potential measures to reduce, impacts. Flight trajectory data that were collected post-construction of the Danish Nysted offshore wind farm were used to parameterize competing models of bird movements around turbines. The model most closely fitting the observed data incorporated individual variation in the minimum distance at which birds responded to the turbines. We show how such models can contribute to the spatial planning of wind farms by assessing their extent, turbine spacing and configurations on the probability of birds passing between the turbines. Avian movement models can make new contributions to environmental assessments of wind farm developments, and provide insights into how to reduce impacts that can be identified at the planning stage.

  1. Effects of wave induced motion on power generation of offshore floating wind farms

    NASA Astrophysics Data System (ADS)

    Shoele, Kourosh

    2014-11-01

    Wind power has been the world's fastest growing energy source for more than a decade. There is a continuous effort to study the potentials of offshore floating wind farms in producing electricity. One of the major technical challenges in studying the performance of offshore floating wind farms is the hydrodynamic and aerodynamic interactions between individual turbines. In this study, a novel approach is presented to study the hydrodynamic interaction between group of floating wind turbines and determine how wave induced motion of the platforms modifies the power generation of the farm. In particular, exact analytical models are presented to solve the hydrodynamic diffraction and radiation problem of a group of floating wind turbine platforms, to model the aerodynamic interaction between turbines, and to quantify the nonlinear dynamic of the mooring lines used to stabilize the floating platforms through connecting them to the seabed. The overall performance of the farm with different configuration and at different wind and wave conditions are investigated and the effects of the sea state condition as well as the distance between the turbines in the farm on the low frequency temporal variation of the power output are discussed.

  2. Development of short-term forecast quality for new offshore wind farms

    NASA Astrophysics Data System (ADS)

    Kurt, M.; Lange, B.

    2014-06-01

    As the rapid wind power build-out continues, a large number of new wind farms will come online but forecasters and forecasting algorithms have little experience with them. This is a problem for statistical short term forecasts, which must be trained on a long record of historical power production - exactly what is missing for a new farm. Focus of the study was to analyse development of the offshore wind power forecast (WPF) quality from beginning of operation up to one year of operational experience. This paper represents a case study using data of the first German offshore wind farm "alpha ventus" and first German commercial offshore wind farm "Baltic1". The work was carried out with measured data from meteorological measurement mast FINO1, measured power from wind farms and numerical weather prediction (NWP) from the German Weather Service (DWD). This study facilitates to decide the length of needed time series and selection of forecast method to get a reliable WPF on a weekly time axis. Weekly development of WPF quality for day-ahead WPF via different models is presented. The models are physical model; physical model extended with a statistical correction (MOS) and artificial neural network (ANN) as a pure statistical model. Selforganizing map (SOM) is investigated for a better understanding of uncertainties of forecast error.

  3. COE projection for the modular WARP{trademark} wind power system for wind farms and electric utility power transmission

    SciTech Connect

    Weisbrich, A.L.; Ostrow, S.L.; Padalino, J.

    1995-09-01

    Wind power has emerged as an attractive alternative source of electricity for utilities. Turbine operating experience from wind farms has provided corroborating data of wind power potential for electric utility application. Now, a patented modular wind power technology, the Toroidal Accelerator Rotor Platform (TARP{trademark}) Windframe{trademark}, forms the basis for next generation megawatt scale wind farm and/or distributed wind power plants. When arranged in tall vertically clustered TARP{trademark} module stacks, such power plant units are designated Wind Amplified Rotor Platform (WARP{trademark}) Systems. While heavily building on proven technology, these systems are projected to surpass current technology windmills in terms of performance, user-friendly operation and ease of maintenance. In its unique generation and transmission configuration, the WARP{trademark}-GT System combines both electricity generation through wind energy conversion and electric power transmission. Furthermore, environmental benefits include dramatically less land requirement, architectural appearance, lower noise and EMI/TV interference, and virtual elimination of bird mortality potential. Cost-of-energy (COE) is projected to be from under $0.02/kWh to less than $0.05/kWh in good to moderate wind resource sites.

  4. Incorporating atmospheric stability effects into the FLORIS engineering model of wakes in wind farms

    DOE PAGES

    Gebraad, Pieter M. O.; Churchfield, Matthew J.; Fleming, Paul A.

    2016-10-03

    Atmospheric stability conditions have an effect on wind turbine wakes. This is an important factor in wind farms in which the wake properties affect the performance of downstream turbines. In the stable atmosphere, wind direction shear has a lateral skewing effect on the wakes. In this study, we describe changes to the FLOw Redirection and Induction in Steady-state (FLORIS) wake engineering model to incorporate and parameterize this effect.

  5. A predictive control framework for optimal energy extraction of wind farms

    NASA Astrophysics Data System (ADS)

    Vali, M.; van Wingerden, J. W.; Boersma, S.; Petrović, V.; Kühn, M.

    2016-09-01

    This paper proposes an adjoint-based model predictive control for optimal energy extraction of wind farms. It employs the axial induction factor of wind turbines to influence their aerodynamic interactions through the wake. The performance index is defined here as the total power production of the wind farm over a finite prediction horizon. A medium-fidelity wind farm model is utilized to predict the inflow propagation in advance. The adjoint method is employed to solve the formulated optimization problem in a cost effective way and the first part of the optimal solution is implemented over the control horizon. This procedure is repeated at the next controller sample time providing the feedback into the optimization. The effectiveness and some key features of the proposed approach are studied for a two turbine test case through simulations.

  6. Distribution of mean kinetic energy around an isolated wind turbine and a characteristic wind turbine of a very large wind farm

    NASA Astrophysics Data System (ADS)

    Cortina, Gerard; Calaf, Marc; Cal, Raúl Bayoán

    2016-11-01

    An isolated wind turbine and a very large wind farm are introduced into large-eddy simulations of an atmospheric boundary layer. The atmospheric flow is forced with a constant geostrophic wind and a time-varying surface temperature extracted from a selected period of the CASES-99 field experiment. A control volume approach is used to directly compare the transfer of mean kinetic energy around a characteristic wind turbine throughout a diurnal cycle considering both scenarios. For the very large wind farm case, results illustrate that the recovery of mean kinetic energy around a wind turbine is dominated by the vertical flux, regardless of atmospheric stratification. Contrarily, for an isolated wind turbine, the recovery is dependent on the background atmospheric stratification and it is produced by a combination of advection, vertical flux, and pressure redistribution. The analysis also illustrates that during the unstable stratification periods vertical entrainment of mean kinetic energy dominates, whereas during the stable regime horizontal entrainment is predominant. Finally, it is observed that in both scenarios, the single wind turbine and the large wind farm cases, turbulent mixing is driven by the background convective stratification during the unstable period and by the effect of the wind turbine during the stable regime.

  7. Analyzing complex wake-terrain interactions and its implications on wind-farm performance.

    NASA Astrophysics Data System (ADS)

    Tabib, Mandar; Rasheed, Adil; Fuchs, Franz

    2016-09-01

    Rotating wind turbine blades generate complex wakes involving vortices (helical tip-vortex, root-vortex etc.).These wakes are regions of high velocity deficits and high turbulence intensities and they tend to degrade the performance of down-stream turbines. Hence, a conservative inter-turbine distance of up-to 10 times turbine diameter (10D) is sometimes used in wind-farm layout (particularly in cases of flat terrain). This ensures that wake-effects will not reduce the overall wind-farm performance, but this leads to larger land footprint for establishing a wind-farm. In-case of complex-terrain, within a short distance (say 10D) itself, the nearby terrain can rise in altitude and be high enough to influence the wake dynamics. This wake-terrain interaction can happen either (a) indirectly, through an interaction of wake (both near tip vortex and far wake large-scale vortex) with terrain induced turbulence (especially, smaller eddies generated by small ridges within the terrain) or (b) directly, by obstructing the wake-region partially or fully in its flow-path. Hence, enhanced understanding of wake- development due to wake-terrain interaction will help in wind farm design. To this end the current study involves: (1) understanding the numerics for successful simulation of vortices, (2) understanding fundamental vortex-terrain interaction mechanism through studies devoted to interaction of a single vortex with different terrains, (3) relating influence of vortex-terrain interactions to performance of a wind-farm by studying a multi-turbine wind-farm layout under different terrains. The results on interaction of terrain and vortex has shown a much faster decay of vortex for complex terrain compared to a flatter-terrain. The potential reasons identified explaining the observation are (a) formation of secondary vortices in flow and its interaction with the primary vortex and (b) enhanced vorticity diffusion due to increased terrain-induced turbulence. The implications of

  8. An integrated methodology on the suitability of offshore sites for wind farm development

    NASA Astrophysics Data System (ADS)

    Patlakas, Platon; Galanis, George; Péray, Marie; Filipot, Jean-François; Kalogeri, Christina; Spyrou, Christos; Diamantis, Dimitris; Kallos, Gerorge

    2016-04-01

    During, the last decades the potential and interest in wind energy investments has been constantly increasing in the European countries. As technology changes rapidly, more and more areas can be identified as suitable for energy applications. Offshore wind farms perfectly illustrate how new technologies allow to build bigger, more efficient and resistant in extreme conditions wind power plants. The current work proposes an integrated methodology to determine the suitability of an offshore marine area for the development of wind farm structures. More specifically, the region of interest is evaluated based both on the natural resources, connected to the local environmental characteristics, and potential constrains set by anthropogenic or other activities. State of the art atmospheric and wave models and a 10-year hindcast database are utilized in conjunction with local information for a number of potential constrains, leading to a 5-scale suitability index for the whole area. In this way, sub regions are characterized, at a high resolution mode, as poorly or highly suitable for wind farm development, providing a new tool for technical/research teams and decision makers. In addition, extreme wind and wave conditions and their 50-years return period are analyzed and used to define the safety level of the wind farms structural characteristics.

  9. Evaluation of Quality of Life of Those Living near a Wind Farm

    PubMed Central

    Mroczek, Bożena; Banaś, Joanna; Machowska-Szewczyk, Małgorzata; Kurpas, Donata

    2015-01-01

    Objectives: Health-related quality of life (HRQoL) can serve as a multidimensional means of evaluating the relationship between the presence of wind turbines in residential areas and their consequence for health. The purpose of this study was to determine whether a relationship exists between the presence of wind farms at different stages of development and the HRQoL of people living in their vicinity in Poland. Method: The instruments employed in this study were the SF-36v2, a questionnaire measuring self-reported health problems, and a sociodemographic questionnaire. The study involved 1277 people who lived within 2 km from a wind turbine. Results: The highest overall QoL scores were obtained by respondents living the closest to wind turbines. The mental health, role emotional, and social functioning scores were significantly higher among respondents living near wind farms and wind-farm construction sites than among those living close to locations where wind farms were planned but where construction had not yet begun. Positive correlations were found between physical and mental component scores and reactions to the news of plans to construct a wind farm. Significant differences in physical and mental component scores were observed between residents who reacted calmly and those who responded with apprehension. Residents who expected the improvement of their financial standing as a result of the wind farm assessed their general health higher than those who did not expect to receive any economic benefits. The lowest QoL scores corresponded to frequent headaches, stomach aches, and back pain over the previous three months, as well as recurrent problems with falling asleep, anxiety, and a lack of acceptance of the project. Conclusion: The lowest overall QoL and general health scores were noted among residents of places where wind-farm developments were either at the stage of planning or under construction. In order to find ways of reducing environmental stress and its

  10. Measurement of rotor centre flow direction and turbulence in wind farm environment

    NASA Astrophysics Data System (ADS)

    Pedersen, T. F.; Demurtas, G.; Sommer, A.; Højstrup, J.

    2014-06-01

    The measurement of inflow to a wind turbine rotor was made with a spinner anemometer on a 2 MW wind turbine in a wind farm of eight wind turbines. The wind speed, yaw misalignment and flow inclination angle was measured during a five months measurement campaign. Angular measurements were calibrated by yawing the wind turbine in and out of the wind in stopped conditions. Wind speed was calibrated relative to a met mast in a wake-free wind sector during operation. The calibration measurements were used to determine the basic k1 and k2 constants of the spinner anemometer and a four parameter induction factor function. Yaw measurements and turbulence measurements, where the average wind speed was corrected to the far field with the induction function, showed good correlation with mast measurements. The yaw misalignment measurements showed a significant yaw misalignment for most of the wind speed range, and also a minor symmetric yaw misalignment pattern. The flow inclination angle showed slight variation of inflow angle with wind speed and clear wake swirl patterns in the wakes of the other wind turbines. Turbulence intensity measurements showed clear variations from low turbulence in the wake-free wind sector to high turbulence in the wakes of the other wind turbines.

  11. 2013-2014 Lidar Campaign: Measurements of Inflow at a Northern Oklahoma Wind Farm

    SciTech Connect

    Wharton, Sonia; Newman, Jennifer; Irons, Zack; Miller, Wayne O.

    2014-10-25

    In November 2013, LLNL deployed two vertically-profiling, Doppler Laser Detection and Ranging (lidar) instruments at Enel Green Power North America’s 235 MW wind farm in Northern Oklahoma to collect wind measurements. The lidars were used to measure wake-free observations of the free-stream wind flow (i.e., inflow) for purposes of quantifying rotor-disk wind characteristics under varying atmospheric conditions. The measurements included horizontal wind speed, vertical wind speed, wind direction, and turbulence intensity, taken at a ~1 Hz sampling rate and averaged over 10-minute intervals. From these measurements we also calculated wind shear across the turbine rotor disk and turbulence kinetic energy (TKE).

  12. Wind-farms in shallow conventionally neutral boundary layers: effects of transition and gravity waves on energy budget

    NASA Astrophysics Data System (ADS)

    Meyers, Johan; Allaerts, Dries

    2016-11-01

    Conventionally neutral boundary layers (CNBL) often arise in offshore conditions. In these situations the neutral boundary layer is capped by a strong inversion layer and a stably stratified free atmosphere aloft. We use large-eddy simulations to investigate the interaction between a CNBL and a large wind farm. Following the approach of Allaerts & Meyers (2015), a set of equilibrium CNBLs are produced in a precursor simulation, with a height of approx. 300, 500, and 1000m, respectively. These are used at the inlet of a large wind-farm with a fetch of 15 km, and 20 rows of turbines. We find that above the farm, an internal boundary layer (IBL) develops. For the two lower CNBL cases, the IBL growth is stopped by the overlying capping inversion. Moreover, the upward displacement of the CNBL excites gravity waves in the inversion layer and the free atmosphere above. For the lower CNBL cases, these waves induce significant pressure gradients in the farm. A detailed energy budget analysis of the CNBL is further presented. The authors acknowledge support from the European Research Council (FP7-Ideas, Grant No. 306471).

  13. Characteristics of Wind-Infective Farms of the 2006 Bluetongue Serotype 8 Epidemic in Northern Europe.

    PubMed

    Sedda, Luigi; Morley, David; Brown, Heidi E

    2015-09-01

    Bluetongue is a Culicoides-borne viral disease of livestock. In 2006, northern Europe experienced a major outbreak of this disease with devastating effects on the livestock industry. The outbreak quickly spread over the region, primarily affecting cattle and sheep. A previous analysis of the role of vector flight and wind in the spread of this virus across northern Europe indicated that infection at 1,326 (65%) of the reported infected farms could be traced back to just 599 (29%) farms (wind-infective farms). Rather than focusing on presence or absence of vectors or difference between infected and non-infected farms, we investigate the zoological and environmental characteristics of these 599 wind-infective farms (which can be thought of as super-spreaders) in order to characterize what makes them distinct from non-infective farms. Differences in temperature, precipitation, and the density of sheep at individual farms were identified between these two groups. These environmental and zoological factors are known to affect vector abundance and may have promoted bluetongue virus transmission. Identifying such ecological differences can help in the description and quantification of relative risk in affected areas.

  14. Optimal control of wind-farm boundary layers: effect of turbine response time

    NASA Astrophysics Data System (ADS)

    Munters, Wim; Meyers, Johan

    2016-11-01

    Complex turbine wake interactions play an important role in overall energy extraction in large wind farms. Current control strategies optimize individual turbine power, and lead to significant energy losses in wind farms compared to lone-standing turbines. In recent work, an optimal control framework for dynamic induction control of wind farms and their interaction with the atmospheric boundary layer (ABL) was introduced, with the aim of mitigating such losses. The framework applies a receding horizon methodology, in which the ABL state is modeled through large-eddy simulations. Previously, the framework was applied to both fully-developed and spatially developing wind farms, for which respective energy gains of 16% and 7% were obtained, albeit at the cost of additional turbine loading variability. Here, we quantify the trade-off between increased power extraction and smoothed turbine dynamics by varying the turbine response time in the control framework. We consider simulation cases restricted to underinduction compared to Betz-optimal induction, as well as cases that also allow overinduction. In addition, efforts on replicating optimized power gains with practical controllers are presented. The authors are supported by the ERC (ActiveWindFarms, Grant No.: 306471).

  15. A preliminary benefit-cost study of a Sandia wind farm.

    SciTech Connect

    Ehlen, Mark Andrew; Griffin, Taylor; Loose, Verne W.

    2011-03-01

    In response to federal mandates and incentives for renewable energy, Sandia National Laboratories conducted a feasibility study of installing an on-site wind farm on Sandia National Laboratories and Kirtland Air Force Base property. This report describes this preliminary analysis of the costs and benefits of installing and operating a 15-turbine, 30-MW-capacity wind farm that delivers an estimated 16 percent of 2010 onsite demand. The report first describes market and non-market economic costs and benefits associated with operating a wind farm, and then uses a standard life-cycle costing and benefit-cost framework to estimate the costs and benefits of a wind farm. Based on these 'best-estimates' of costs and benefits and on factor, uncertainty and sensitivity analysis, the analysis results suggest that the benefits of a Sandia wind farm are greater than its costs. The analysis techniques used herein are applicable to the economic assessment of most if not all forms of renewable energy.

  16. On the Impact of Wind Farms on a Convective Atmospheric Boundary Layer

    NASA Astrophysics Data System (ADS)

    Lu, Hao; Porté-Agel, Fernando

    2015-10-01

    With the rapid growth in the number of wind turbines installed worldwide, a demand exists for a clear understanding of how wind farms modify land-atmosphere exchanges. Here, we conduct three-dimensional large-eddy simulations to investigate the impact of wind farms on a convective atmospheric boundary layer. Surface temperature and heat flux are determined using a surface thermal energy balance approach, coupled with the solution of a three-dimensional heat equation in the soil. We study several cases of aligned and staggered wind farms with different streamwise and spanwise spacings. The farms consist of Siemens SWT-2.3-93 wind turbines. Results reveal that, in the presence of wind turbines, the stability of the atmospheric boundary layer is modified, the boundary-layer height is increased, and the magnitude of the surface heat flux is slightly reduced. Results also show an increase in land-surface temperature, a slight reduction in the vertically-integrated temperature, and a heterogeneous spatial distribution of the surface heat flux.

  17. Distributed Wind Case Study: Cross Island Farms, Wellesley Island, New York

    SciTech Connect

    2012-04-30

    Installing a small wind turbine can sometimes be challenging due to economics, zoning issues, public perception, and other barriers. Persistence and innovation, however, can result in a successful installation. Dani Baker and David Belding own Cross Island Farms, a 102-acre certified organic farm on Wellesley Island in northern New York. In 2009, they took their interest in renewable energy to the next level by researching the logistics of a small wind installation on their land to make their farm even more sustainable. Their renewable energy system consists of one 10-kilowatt Bergey Excel wind turbine, a solar array, and a propane-powered generator. This case study describes funding for the project and the installation process.

  18. Distributed Wind Case Study: Cross Island Farms, Wellesley Island, New York (Fact Sheet)

    SciTech Connect

    Not Available

    2012-04-01

    Installing a small wind turbine can sometimes be difficult due to economics, zoning issues, public perception, and other barriers. Persistence and innovation, however, can result in a successful installation. Dani Baker and David Belding own Cross Island Farms, a 102-acre certified organic farm on Wellesley Island in northern New York. In 2009, they took their interest in renewable energy to the next level by researching the logistics of a small wind installation on their land to make their farm even more sustainable. Their renewable energy system consists of one 10-kilowatt Bergey Excel wind turbine, a solar array, and a propane-powered generator. This case study describes funding for the project and the installation process.

  19. Avoidance of wind farms by harbour seals is limited to pile driving activities.

    PubMed

    Russell, Debbie J F; Hastie, Gordon D; Thompson, David; Janik, Vincent M; Hammond, Philip S; Scott-Hayward, Lindesay A S; Matthiopoulos, Jason; Jones, Esther L; McConnell, Bernie J

    2016-12-01

    As part of global efforts to reduce dependence on carbon-based energy sources there has been a rapid increase in the installation of renewable energy devices. The installation and operation of these devices can result in conflicts with wildlife. In the marine environment, mammals may avoid wind farms that are under construction or operating. Such avoidance may lead to more time spent travelling or displacement from key habitats. A paucity of data on at-sea movements of marine mammals around wind farms limits our understanding of the nature of their potential impacts.Here, we present the results of a telemetry study on harbour seals Phoca vitulina in The Wash, south-east England, an area where wind farms are being constructed using impact pile driving. We investigated whether seals avoid wind farms during operation, construction in its entirety, or during piling activity. The study was carried out using historical telemetry data collected prior to any wind farm development and telemetry data collected in 2012 during the construction of one wind farm and the operation of another.Within an operational wind farm, there was a close-to-significant increase in seal usage compared to prior to wind farm development. However, the wind farm was at the edge of a large area of increased usage, so the presence of the wind farm was unlikely to be the cause.There was no significant displacement during construction as a whole. However, during piling, seal usage (abundance) was significantly reduced up to 25 km from the piling activity; within 25 km of the centre of the wind farm, there was a 19 to 83% (95% confidence intervals) decrease in usage compared to during breaks in piling, equating to a mean estimated displacement of 440 individuals. This amounts to significant displacement starting from predicted received levels of between 166 and 178 dB re 1 μPa(p-p). Displacement was limited to piling activity; within 2 h of cessation of pile driving, seals were distributed as per

  20. Assessment of weather downtime for the construction of offshore wind farm by using wind and wave simulations

    NASA Astrophysics Data System (ADS)

    Kikuchi, Yuka; Ishihara, Takeshi

    2016-09-01

    In this study, numerical simulations for winds and waves were carried out using WRF and WW3 and the predicted wind speed, wave height and wave period were validated with measurement. Annual average values of absolute monthly error of wind speed, wave height and wave period were 4.30%, 12.3% and 7.8%. The prediction accuracy were improved by bias modification in the region of low wave height and short wave period. Predicted seasonal frequency distributions showed good agreement with measurements. The criteria of experienced construction methods were investigated at Choshi and Kitakyushu wind farm and the sensitivity of environmental conditions on weather downtime were clarified. At Choshi, the weather downtime was predicted by using wind and wave simulations and showed good agreement with the actual weather downtime.

  1. Seasonal variations of wind farm impacts on land surface temperature and vegetation over northern Illinois

    NASA Astrophysics Data System (ADS)

    Slawsky, Lauren

    Operating wind turbines enhance near surface turbulence and alter the exchanges of surface energy, water, and momentum, thus affecting local micrometeorology. Climatic impacts of three wind farms in northern Illinois are assessed using land surface temperature (LST) from the Moderate Resolution Imaging Spectroradiometer (MODIS) data onboard the Terra and Aqua satellites for the period 2003-2013. Changes in LST between two periods (before and after construction of the wind turbines) and between wind farm pixels (WFPs) and nearby non wind farm pixels (NNWFPs) are quantified. An increase in LST is observed at nighttime over each wind farm, with the pattern of this warming effect generally spatially coupled with the wind turbines, while there is no apparent impact on daytime LST. The nighttime LST warming effect varies with the seasons, with the strongest warming in winter months of December, January, and February, and the tightest spatial coupling in summer months of June, July, and August. Analysis of seasonal variations in wind speeds from weather balloon sounding data taken at the 80 meter turbine hub height and Automated Surface Observing System hourly observations at 10 meters from nearby stations suggest stronger winds correspond to seasons with greater warming. The 12:00 Greenwich Mean Time (early morning in Illinois) soundings are representative of the nighttime boundary layer and exhibit strong temperature inversions across all seasons. This supports the idea that the observed warming effect is caused by warm air aloft brought down to the surface by the spinning turbine rotor blades. In addition, MODIS measured vegetation greenness is used to assess the potential impact of this warming on underlying vegetation growth. A decrease in vegetation greenness is seen, particularly during the summer peak growing season, indicating that the turbine enhanced turbulence may promote evapotranspiration and thus reduce soil moisture available for plant photosynthesis.

  2. Large-eddy simulations of wind farm production and long distance wakes

    NASA Astrophysics Data System (ADS)

    Eriksson, O.; Nilsson, K.; Breton, S.-P.; Ivanell, S.

    2015-06-01

    The future development of offshore wind power will include many wind farms built in the same areas. It is known that wind farms produce long distance wakes, which means that we will see more occasions of farm to farm interaction, namely one wind farm operating in the wake of another wind farm. This study investigates how to perform accurate power predictions on large wind farms and how to assess the long distance wakes generated by these farms. The focus of this paper is the production's and wake's sensitivity to the extension of the grid as well as the turbulence when using Large-eddy simulations (LES) with pregenerated Mann turbulence. The aim is to determine an optimal grid which minimizes blockage effects and ensures constant resolution in the entire wake region at the lowest computational cost. The simulations are first performed in the absence of wind turbines in order to assess how the atmospheric turbulence and wind profile are evolving downstream (up to 12,000 m behind the position where the turbulence is imposed). In the second step, 10 turbines are added in the domain (using an actuator disc method) and their production is analyzed alongside the mean velocities in the domain. The blockage effects are tested using grids with different vertical extents. An equidistant region is used in order to ensure high resolution in the wake region. The importance of covering the entire wake structure inside the equidistant region is analyzed by decreasing the size of this region. In this step, the importance of the lateral size of the Mann turbulence box is also analyzed. In the results it can be seen that the flow is acceptably preserved through the empty domain if a larger turbulence box is used. The relative production is increased (due to blockage effects) for the last turbines using a smaller vertical domain, increased for a lower or narrower equidistant region (due to the smearing of the wake in the stretched area) and decreased when using a smaller turbulence

  3. Effects of Offshore Wind Farms on the Early Life Stages of Dicentrarchus labrax.

    PubMed

    Debusschere, Elisabeth; De Coensel, Bert; Vandendriessche, Sofie; Botteldooren, Dick; Hostens, Kris; Vincx, Magda; Degraer, Steven

    2016-01-01

    Anthropogenically generated underwater noise in the marine environment is ubiquitous, comprising both intense impulse and continuous noise. The installation of offshore wind farms across the North Sea has triggered a range of ecological questions regarding the impact of anthropogenically produced underwater noise on marine wildlife. Our interest is on the impact on the "passive drifters," i.e., the early life stages of fish that form the basis of fish populations and are an important prey for pelagic predators. This study deals with the impact of pile driving and operational noise generated at offshore wind farms on Dicentrarchus labrax (sea bass) larvae.

  4. Wind Power Curve Modeling Using Statistical Models: An Investigation of Atmospheric Input Variables at a Flat and Complex Terrain Wind Farm

    SciTech Connect

    Wharton, S.; Bulaevskaya, V.; Irons, Z.; Qualley, G.; Newman, J. F.; Miller, W. O.

    2015-09-28

    The goal of our FY15 project was to explore the use of statistical models and high-resolution atmospheric input data to develop more accurate prediction models for turbine power generation. We modeled power for two operational wind farms in two regions of the country. The first site is a 235 MW wind farm in Northern Oklahoma with 140 GE 1.68 turbines. Our second site is a 38 MW wind farm in the Altamont Pass Region of Northern California with 38 Mitsubishi 1 MW turbines. The farms are very different in topography, climatology, and turbine technology; however, both occupy high wind resource areas in the U.S. and are representative of typical wind farms found in their respective areas.

  5. Wake interaction and power production of variable height model wind farms

    NASA Astrophysics Data System (ADS)

    Vested, M. H.; Hamilton, N.; Sørensen, J. N.; Cal, R. B.

    2014-06-01

    Understanding wake dynamics is an ongoing research topic in wind energy, since wakes have considerable effects on the power production when wind turbines are placed in a wind farm. Wind tunnel experiments have been conducted to study the wake to wake interaction in a model wind farm in tandem with measurements of the extracted power. The aim is to investigate how alternating mast height influences the interaction of the wakes and the power production. Via the use of stereo-particle image velocimetry, the flow field was obtained in the first and last rows of the wind turbine array as a basis of comparison. It was found that downstream of the exit row wind turbine, the power was increased by 25% in the case of a staggered height configuration. This is partly due to the fact that the taller turbines reach into a flow area with a softened velocity gradient. Another aspect is that the wake downstream of a tall wind turbine to some extent passes above the standard height wind turbine. Overall the experiments show that the velocity field downstream of the exit row changes considerably when the mast height is alternating.

  6. Increase in fault ride through capability of direct drive permanent magnet based wind farm using VSC-HVDC

    NASA Astrophysics Data System (ADS)

    Maleki, Hesamaldin; Ramachandaramurthy, V. K.; Lak, Moein

    2013-06-01

    Burning of fossil fuels and green house gasses causes global warming. This has led to governments to explore the use of green energies instead of fossil fuels. The availability of wind has made wind technology a viable alternative for generating electrical power. Hence, many parts of the world, especially Europe are experiencing a growth in wind farms. However, by increasing the number of wind farms connected to the grid, power quality and voltage stability of grid becomes a matter of concern. In this paper, VSC-HVDC control strategy which enables the wind farm to ride-through faults and regulate voltage for fault types is proposed. The results show that the wind turbine output voltage fulfills the E.ON grid code requirements, when subjected to three phase to ground fault. Hence, continues operation of the wind farm is achieved.

  7. Gis-Based Wind Farm Site Selection Model Offshore Abu Dhabi Emirate, Uae

    NASA Astrophysics Data System (ADS)

    Saleous, N.; Issa, S.; Mazrouei, J. Al

    2016-06-01

    The United Arab Emirates (UAE) government has declared the increased use of alternative energy a strategic goal and has invested in identifying and developing various sources of such energy. This study aimed at assessing the viability of establishing wind farms offshore the Emirate of Abu Dhabi, UAE and to identify favourable sites for such farms using Geographic Information Systems (GIS) procedures and algorithms. Based on previous studies and on local requirements, a set of suitability criteria was developed including ocean currents, reserved areas, seabed topography, and wind speed. GIS layers were created and a weighted overlay GIS model based on the above mentioned criteria was built to identify suitable sites for hosting a new offshore wind energy farm. Results showed that most of Abu Dhabi offshore areas were unsuitable, largely due to the presence of restricted zones (marine protected areas, oil extraction platforms and oil pipelines in particular). However, some suitable sites could be identified, especially around Delma Island and North of Jabal Barakah in the Western Region. The environmental impact of potential wind farm locations and associated cables on the marine ecology was examined to ensure minimal disturbance to marine life. Further research is needed to specify wind mills characteristics that suit the study area especially with the presence of heavy traffic due to many oil production and shipping activities in the Arabian Gulf most of the year.

  8. Improved Electrical Load Match In California By Combining Solar Thermal Power Plants with Wind Farms

    SciTech Connect

    Vick, B. D.; Clark, R. N.; Mehos, M.

    2008-01-01

    California with its hydro, geothermal, wind, and solar energy is the second largest producer of renewable electricity in the United States (Washington state is the largest producer of renewable energy electricity due to high level of hydro power). Replacing fossil fuel electrical generation with renewable energy electrical generation will decrease the release of carbon dioxide into the atmosphere which will slow down the rapid increase in global warming (a goal of the California state government). However, in order for a much larger percentage of the total electrical generation in California to be from renewable energies like wind and solar, a better match between renewable energy generation and utility electrical load is required. Using wind farm production data and predicted production from a solar thermal power plant (with and without six hours of storage), a comparison was made between the renewable energy generation and the current utility load in California. On a monthly basis, wind farm generated electricity at the three major wind farm areas in California (Altamont Pass, east of San Francisco Bay area; Tehachapi Pass in the high desert between Tehachapi and Mojave; and San Gorgonio Pass in the low desert near Palm Springs) matches the utility load well during the highest electrical load months (May through September). Prediction of solar thermal power plant output also indicates a good match with utility load during these same high load months. Unfortunately, the hourly wind farm output during the day is not a very good match to the utility electrical load (i.e. in spring and summer the lowest wind speed generally occurs during mid-day when utility load is highest). If parabolic trough solar thermal power plants are installed in the Mojave Desert (similar to the 354 MW of plants that have been operating in Mojave Desert since 1990) then the solar electrical generation will help balance out the wind farm generation since highest solar generated electricity

  9. 77 FR 62509 - Big Blue Wind Farm, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-15

    ... Energy Regulatory Commission Big Blue Wind Farm, LLC; Supplemental Notice That Initial Market- Based Rate...-referenced proceeding, of Big Blue Wind Farm, LLC's application for market-based rate authority, with an.... Dated: October 5, 2012. Nathaniel J. Davis, Sr., Deputy Secretary. BILLING CODE 6717-01-P...

  10. 76 FR 72697 - Heritage Garden Wind Farm I, LLC; Supplemental Notice That Initial Market-Based Rate Filing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-25

    ... From the Federal Register Online via the Government Publishing Office ] DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Heritage Garden Wind Farm I, LLC; Supplemental Notice That Initial... notice in the above-referenced proceeding of Heritage Garden Wind Farm I, LLC's application for...

  11. 75 FR 71426 - Blue Creek Wind Farm, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-23

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Blue Creek Wind Farm, LLC; Supplemental Notice That Initial Market-Based... supplemental notice in the above-referenced proceeding, of Blue Creek Wind Farm, LLC's application for...

  12. 75 FR 63466 - Flat Water Wind Farm, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-15

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Flat Water Wind Farm, LLC; Supplemental Notice That Initial Market-Based... supplemental notice in the above-referenced proceeding of Flat Water Wind Farm, LLC's application for...

  13. 75 FR 48665 - Heritage Stoney Corners Wind Farm I, LLC; Supplemental Notice That Initial Market-Based Rate...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-11

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Heritage Stoney Corners Wind Farm I, LLC; Supplemental Notice That Initial... supplemental notice in the above-referenced proceeding, of Heritage Stoney Corners Wind Farm I,...

  14. 75 FR 27339 - Blackstone Wind Farm II, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes...

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    2010-05-14

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Blackstone Wind Farm II, LLC; Supplemental Notice That Initial Market-Based... notice in the above-referenced proceeding of Blackstone Wind Farm, LLCs application for market-based...

  15. 76 FR 10581 - Settlers Trail Wind Farm, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes...

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    2011-02-25

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Settlers Trail Wind Farm, LLC; Supplemental Notice That Initial Market-Based... above-referenced proceeding of Settlers Trail Wind Farm, LLC's application for market-based...

  16. 76 FR 23580 - Dempsey Ridge Wind Farm, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes...

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    2011-04-27

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Dempsey Ridge Wind Farm, LLC; Supplemental Notice That Initial Market-Based... above-referenced proceeding of Dempsey Ridge Wind Farm, LLC's application for market-based...

  17. 77 FR 36529 - Patton Wind Farm, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-19

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Patton Wind Farm, LLC; Supplemental Notice That Initial Market- Based Rate...-referenced proceeding of Patton Wind Farm, LLC's application for market-based rate authority, with...

  18. 77 FR 20380 - Wildcat Wind Farm I, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes...

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    2012-04-04

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Wildcat Wind Farm I, LLC; Supplemental Notice That Initial Market-Based Rate...-referenced proceeding of Wildcat Wind Farm I, LLC's application for market-based rate authority, with...

  19. 76 FR 11774 - Paulding Wind Farm II LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes...

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    2011-03-03

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Paulding Wind Farm II LLC; Supplemental Notice That Initial Market-Based... above-referenced proceeding of Paulding Wind Farm II LLC's application for market-based rate...

  20. 76 FR 10581 - Pioneer Trail Wind Farm, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-25

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Pioneer Trail Wind Farm, LLC; Supplemental Notice That Initial Market-Based... above-referenced proceeding of Pioneer Trail Wind Farm, LLC's application for market-based...

  1. Ground-level climate at a peatland wind farm in Scotland is affected by wind turbine operation

    NASA Astrophysics Data System (ADS)

    Armstrong, Alona; Burton, Ralph R.; Lee, Susan E.; Mobbs, Stephen; Ostle, Nicholas; Smith, Victoria; Waldron, Susan; Whitaker, Jeanette

    2016-04-01

    The global drive to produce low-carbon energy has resulted in an unprecedented deployment of onshore wind turbines, representing a significant land use change for wind energy generation with uncertain consequences for local climatic conditions and the regulation of ecosystem processes. Here, we present high-resolution data from a wind farm collected during operational and idle periods that shows the wind farm affected several measures of ground-level climate. Specifically, we discovered that operational wind turbines raised air temperature by 0.18 °C and absolute humidity (AH) by 0.03 g m-3 during the night, and increased the variability in air, surface and soil temperature throughout the diurnal cycle. Further, the microclimatic influence of turbines on air temperature and AH decreased logarithmically with distance from the nearest turbine. These effects on ground-level microclimate, including soil temperature, have uncertain implications for biogeochemical processes and ecosystem carbon cycling, including soil carbon stocks. Consequently, understanding needs to be improved to determine the overall carbon balance of wind energy.

  2. High-resolution computational algorithms for simulating offshore wind turbines and farms: Model development and validation

    SciTech Connect

    Calderer, Antoni; Yang, Xiaolei; Angelidis, Dionysios; Feist, Chris; Guala, Michele; Ruehl, Kelley; Guo, Xin; Boomsma, Aaron; Shen, Lian; Sotiropoulos, Fotis

    2015-10-30

    The present project involves the development of modeling and analysis design tools for assessing offshore wind turbine technologies. The computational tools developed herein are able to resolve the effects of the coupled interaction of atmospheric turbulence and ocean waves on aerodynamic performance and structural stability and reliability of offshore wind turbines and farms. Laboratory scale experiments have been carried out to derive data sets for validating the computational models.

  3. A high performance finite element model for wind farm modeling in forested areas

    NASA Astrophysics Data System (ADS)

    Owen, Herbert; Avila, Matias; Folch, Arnau; Cosculluela, Luis; Prieto, Luis

    2015-04-01

    Wind energy has grown significantly during the past decade and is expected to continue growing in the fight against climate change. In the search for new land where the impact of the wind turbines is small several wind farms are currently being installed in forested areas. In order to optimize the distribution of the wind turbines within the wind farm the Reynolds Averaged Navier Stokes equations are solved over the domain of interest using either commercial or in house codes. The existence of a canopy alters the Atmospheric Boundary Layer wind profile close to the ground. Therefore in order to obtain a more accurate representation of the flow in forested areas modification to both the Navier Stokes and turbulence variables equations need to be introduced. Several existing canopy models have been tested in an academic problem showing that the one proposed by Sogachev et. al gives the best results. This model has been implemented in an in house CFD solver named Alya. It is a high performance unstructured finite element code that has been designed from scratch to be able to run in the world's biggest supercomputers. Its scalabililty has recently been tested up to 100000 processors in both American and European supercomputers. During the past three years the code has been tuned and tested for wind energy problems. Recent efforts have focused on the canopy model following industry needs. In this work we shall benchmark our results in a wind farm that is currently being designed by Scottish Power and Iberdrola in Scotland. This is a very interesting real case with extensive experimental data from five different masts with anemometers at several heights. It is used to benchmark both the wind profiles and the speed up obtained between different masts. Sixteen different wind directions are simulated. The numerical model provides very satisfactory results for both the masts that are affected by the canopy and those that are not influenced by it.

  4. Simulation and Study of Power Quality Issues in a Fixed Speed Wind Farm Substation

    PubMed Central

    Magesh, T.; Chellamuthu, C.

    2015-01-01

    Power quality issues associated with the fixed speed wind farm substation located at Coimbatore district are investigated as the wind generators are tripping frequently. The investigations are carried out using two power quality analyzers, Fluke 435 and Dranetz PX5.8, with one of them connected at group control breaker of the 110 kV feeder and the other at the selected 0.69 kV generator busbar during the period of maximum power generation. From the analysis of the recorded data it is found that sag, swell, and transients are the major events which are responsible for the tripping of the generators. In the present study, simulation models for wind, turbine, shaft, pitch mechanism, induction generator, and grid are developed using DIgSILENT. Using the turbine characteristics, a two-dimensional lookup table is designed to generate a reference pitch angle necessary to simulate the power curve of the passive stall controlled wind turbine. Various scenarios and their effects on the performance of the wind farm are studied and validated with the recorded data and waveforms. The simulation model will be useful for the designers for planning and development of the wind farm before implementation. PMID:25950016

  5. Simulation and study of power quality issues in a fixed speed wind farm substation.

    PubMed

    Magesh, T; Chellamuthu, C

    2015-01-01

    Power quality issues associated with the fixed speed wind farm substation located at Coimbatore district are investigated as the wind generators are tripping frequently. The investigations are carried out using two power quality analyzers, Fluke 435 and Dranetz PX5.8, with one of them connected at group control breaker of the 110 kV feeder and the other at the selected 0.69 kV generator busbar during the period of maximum power generation. From the analysis of the recorded data it is found that sag, swell, and transients are the major events which are responsible for the tripping of the generators. In the present study, simulation models for wind, turbine, shaft, pitch mechanism, induction generator, and grid are developed using DIgSILENT. Using the turbine characteristics, a two-dimensional lookup table is designed to generate a reference pitch angle necessary to simulate the power curve of the passive stall controlled wind turbine. Various scenarios and their effects on the performance of the wind farm are studied and validated with the recorded data and waveforms. The simulation model will be useful for the designers for planning and development of the wind farm before implementation.

  6. Environmental management framework for wind farm siting: methodology and case study.

    PubMed

    Tegou, Leda-Ioanna; Polatidis, Heracles; Haralambopoulos, Dias A

    2010-11-01

    This paper develops an integrated framework to evaluate land suitability for wind farm siting that combines multi-criteria analysis (MCA) with geographical information systems (GIS); an application of the proposed framework for the island of Lesvos, Greece, is further illustrated. A set of environmental, economic, social, and technical constraints, based on recent Greek legislation, identifies the potential sites for wind power installation. Furthermore, the area under consideration is evaluated by a variety of criteria, such as wind power potential, land cover type, electricity demand, visual impact, land value, and distance from the electricity grid. The pair-wise comparison method in the context of the analytic hierarchy process (AHP) is applied to estimate the criteria weights in order to establish their relative importance in site evaluation. The overall suitability of the study region for wind farm siting is appraised through the weighted summation rule. Results showed that only a very small percentage of the total area of Lesvos could be suitable for wind farm installation, although favourable wind potential exists in many more areas of the island.

  7. Regional climate model simulations indicate limited climatic impacts by operational and planned European wind farms.

    PubMed

    Vautard, Robert; Thais, Françoise; Tobin, Isabelle; Bréon, François-Marie; Devezeaux de Lavergne, Jean-Guy; Colette, Augustin; Yiou, Pascal; Ruti, Paolo Michele

    2014-01-01

    The rapid development of wind energy has raised concerns about environmental impacts. Temperature changes are found in the vicinity of wind farms and previous simulations have suggested that large-scale wind farms could alter regional climate. However, assessments of the effects of realistic wind power development scenarios at the scale of a continent are missing. Here we simulate the impacts of current and near-future wind energy production according to European Union energy and climate policies. We use a regional climate model describing the interactions between turbines and the atmosphere, and find limited impacts. A statistically significant signal is only found in winter, with changes within ±0.3 °C and within 0-5% for precipitation. It results from the combination of local wind farm effects and changes due to a weak, but robust, anticyclonic-induced circulation over Europe. However, the impacts remain much weaker than the natural climate interannual variability and changes expected from greenhouse gas emissions.

  8. Regional climate model simulations indicate limited climatic impacts by operational and planned European wind farms

    NASA Astrophysics Data System (ADS)

    Vautard, Robert; Thais, Françoise; Tobin, Isabelle; Bréon, François-Marie; de Lavergne, Jean-Guy Devezeaux; Colette, Augustin; Yiou, Pascal; Ruti, Paolo Michele

    2014-02-01

    The rapid development of wind energy has raised concerns about environmental impacts. Temperature changes are found in the vicinity of wind farms and previous simulations have suggested that large-scale wind farms could alter regional climate. However, assessments of the effects of realistic wind power development scenarios at the scale of a continent are missing. Here we simulate the impacts of current and near-future wind energy production according to European Union energy and climate policies. We use a regional climate model describing the interactions between turbines and the atmosphere, and find limited impacts. A statistically significant signal is only found in winter, with changes within ±0.3 °C and within 0-5% for precipitation. It results from the combination of local wind farm effects and changes due to a weak, but robust, anticyclonic-induced circulation over Europe. However, the impacts remain much weaker than the natural climate interannual variability and changes expected from greenhouse gas emissions.

  9. Anisotropy stress invariants of a large eddy simulation during a diurnal cycle for very large wind farms

    NASA Astrophysics Data System (ADS)

    Cal, Raúl; Ali, Naseem; Hamilton, Nicholas; Cortina, Gerard; Calaf, Marc

    2016-11-01

    Reynolds stress invariants of the turbulent flow within large wind farms under different atmospheric flow stratification (stable, unstable and neutral); cases without turbines is also evaluated. Lumley triangle and barycentric map are used to quantify the anisotropic stress tensor within the wind farm and atmospheric boundary layer. Dependent on the thermal stratification, the unstable and neutral cases of the wind farm and no wind farm display the minimum second invariant in contrast to the stable case that shows the maximum invariants. Scaled color is used to present the invariant as a function of domain height. The unstable stratification approaches the isotropy limit at high layers of the domain and the stable stratification leads the turbulence flow to be one component flow. The principle eigenvalues are also shown, where they show its effects on the vicinity of the swept area of the rotor. Finally, spheroid visualization is pursued to understand and interpret the realizable turbulence flow within the wind farm and atmospheric boundary layer.

  10. Transient stability enhancement of wind farms using power electronics and facts controllers

    NASA Astrophysics Data System (ADS)

    Mohammadpour, Hossein Ali

    Nowadays, it is well-understood that the burning of fossil fuels in electric power station has a significant influence on the global climate due to greenhouse gases. In many countries, the use of cost-effective and reliable low-carbon electricity energy sources is becoming an important energy policy. Among different kinds of clean energy resources- such as solar power, hydro-power, ocean wave power and so on, wind power is the fastest-growing form of renewable energy at the present time. Moreover, adjustable speed generator wind turbines (ASGWT) has key advantages over the fixed-speed generator wind turbines (FSGWT) in terms of less mechanical stress, improved power quality, high system efficiency, and reduced acoustic noise. One important class of ASGWT is the doubly-fed induction generator (DFIG), which has gained a significant attention of the electric power industry due to their advantages over the other class of ASGWT, i.e. fully rated converter-based wind turbines. Because of increased integration of DFIG-based wind farms into electric power grids, it is necessary to transmit the generated power from wind farms to the existing grids via transmission networks without congestion. Series capacitive compensation of DFIG-based wind farm is an economical way to increase the power transfer capability of the transmission line connecting wind farm to the grid. For example, a study performed by ABB reveals that increasing the power transfer capability of an existing transmission line from 1300 MW to 2000 MW using series compensation is 90% less than the cost of building a new transmission line. However, a factor hindering the extensive use of series capacitive compensation is the potential risk of sub- synchronous resonance (SSR). The SSR is a condition where the wind farm exchanges energy with the electric network, to which it is connected, at one or more natural frequencies of the electric or mechanical part of the combined system, comprising the wind farm and the

  11. Wind farm micro-siting optimization using novel cell membrane approach

    NASA Astrophysics Data System (ADS)

    Huang, W.; Che, W. X.; Tan, R. S.; Li, M. X.; Liu, Q.

    2016-08-01

    Micro-siting aims to determine every wind turbine's position to reduce velocity deficits caused by the wake effect. The Novel CMO (cell membrane optimization) approach is proposed to overcome this weakness. It plays a vital role to utilize more wind resources while the type of wind turbine and the area to build a wind farm have been determined. The work is based on the Jensen wake model, and the hypothetical situations are the same as those used by the former researchers. There are three wind cases: constant speed with one direction, constant speed with variable directions and variable speeds with variable directions. The area of wind farm is assumed to be a plane 2km×2km square. The numbers of the wind turbines is 26, 19 and 15 in three cases respectively. Compared with Gene Algorithm introduced by G. Mosetti, CMO's results are acceptable and the velocity deficit is smaller, which results from that CMO's variables is continuous and can make the most of the area the wind turbines can be placed. Moreover, it performs well to avoid the local optimal solutions by dividing the searching particles into different types which move according to different rules.

  12. Evaluation of Dynamical Downscaling Resolution Effect on Wind Energy Forecast Value for a Wind Farm in Central Sweden

    NASA Astrophysics Data System (ADS)

    Rosgaard, Martin; Hahmann, Andrea; Skov Nielsen, Torben; Giebel, Gregor; Ejnar Sørensen, Poul; Madsen, Henrik

    2014-05-01

    For any energy system relying on wind power, accurate forecasts of wind fluctuations are essential for efficient integration into the power grid. Increased forecast precision allows end-users to plan day-ahead operation with reduced risk of penalties which in turn supports the feasibility of wind energy. This study aims to quantify value added to wind energy forecasts in the 12-48 hour leadtime by downscaling global numerical weather prediction (NWP) data using a limited-area NWP model. The accuracy of statistical wind power forecasting tools depends strongly on this NWP input. Typical performance metrics are mean absolute error or root mean square error for predicted- against observed wind power production, and these metrics are closely related to wind speed forecast bias and correlation with observations. Wind speed bias can be handled in the statistical wind power forecasting model, though it is entirely up to it's NWP input to describe the wind speed correlation correctly. The basis of comparison for forecasts is data from the Stor-Rotliden wind farm in central Sweden. The surrounding forest adds to the forecasting challenge, thus motivating the downscaling experiment as the potential for wind power forecast improvement is higher in complex terrain. The 40 Vestas V90 turbines were erected in 2009 and correspond to 78MWe installed electrical capacity. Forecasts from global and limited-area NWP models, together covering five different horizontal computational grid spacings of ~50km down to ~1km, are studied for a yearlong, continuous time period. The preliminary results shown quantify forecast strengths and weaknesses for each NWP model resolution.

  13. 75 FR 19959 - Uilk Wind Farm, LLC; Notice of Effectiveness of Exempt Wholesale Generator Status

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-16

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Uilk Wind Farm, LLC; Notice of Effectiveness of Exempt Wholesale Generator Status April 9, 2010. Take notice that during the month March, 2010, the status of the...

  14. USDA's Vick tells radio audience wind farms mean huge water savings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Since most of the electricity in the U.S. is generated using coal and natural gas as fuel, almost every wind farm announcement includes the estimated amount of carbon dioxide which was not released to the atmosphere. According to Wikipedia, 2.25 tons of CO2 and 1.14 tons of CO2 were released for eve...

  15. Modeling and simulation of offshore wind farm O&M processes

    SciTech Connect

    Joschko, Philip; Widok, Andi H.; Appel, Susanne; Greiner, Saskia; Albers, Henning; Page, Bernd

    2015-04-15

    This paper describes a holistic approach to operation and maintenance (O&M) processes in the domain of offshore wind farm power generation. The acquisition and process visualization is followed by a risk analysis of all relevant processes. Hereafter, a tool was designed, which is able to model the defined processes in a BPMN 2.0 notation, as well as connect and simulate them. Furthermore, the notation was enriched with new elements, representing other relevant factors that were, to date, only displayable with much higher effort. In that regard a variety of more complex situations were integrated, such as for example new process interactions depending on different weather influences, in which case a stochastic weather generator was combined with the business simulation or other wind farm aspects important to the smooth running of the offshore wind farms. In addition, the choices for different methodologies, such as the simulation framework or the business process notation will be presented and elaborated depending on the impact they had on the development of the approach and the software solution. - Highlights: • Analysis of operation and maintenance processes of offshore wind farms • Process modeling with BPMN 2.0 • Domain-specific simulation tool.

  16. Modelling the wind-borne spread of highly pathogenic avian influenza virus between farms.

    PubMed

    Ssematimba, Amos; Hagenaars, Thomas J; de Jong, Mart C M

    2012-01-01

    A quantitative understanding of the spread of contaminated farm dust between locations is a prerequisite for obtaining much-needed insight into one of the possible mechanisms of disease spread between farms. Here, we develop a model to calculate the quantity of contaminated farm-dust particles deposited at various locations downwind of a source farm and apply the model to assess the possible contribution of the wind-borne route to the transmission of Highly Pathogenic Avian Influenza virus (HPAI) during the 2003 epidemic in the Netherlands. The model is obtained from a Gaussian Plume Model by incorporating the dust deposition process, pathogen decay, and a model for the infection process on exposed farms. Using poultry- and avian influenza-specific parameter values we calculate the distance-dependent probability of between-farm transmission by this route. A comparison between the transmission risk pattern predicted by the model and the pattern observed during the 2003 epidemic reveals that the wind-borne route alone is insufficient to explain the observations although it could contribute substantially to the spread over short distance ranges, for example, explaining 24% of the transmission over distances up to 25 km.

  17. In search for a canonical design ABL stability class for wind farm turbines

    NASA Astrophysics Data System (ADS)

    Larsen, G. C.; Verelst, D. R.; Bertagnolio, F.; Ott, S.; Chougule, A.

    2016-09-01

    Production as well as loading of wake exposed wind turbines is known to depend significantly on stability of the Atmospheric Boundary Layer (ABL), which adds a new dimension to design of wind farm turbines. Adding this new aspect in wind turbine design makes the number of design cycle computations to blow up with a factor equal to the number of representative stability bin classes. The research question to be answered in this paper is: Can an ABL stability probability distribution in a meaningful way be collapsed into a representative design stability class as based on a (predefined) confidence level.

  18. Observed impacts of wind farms on land surface temperature in Inner Mongolia

    NASA Astrophysics Data System (ADS)

    Tang, B.; Zhao, X.; Wu, D.; Zhao, W.; Wei, H.

    2015-12-01

    Abstract: The wind turbine industry in china has experienced a dramatic increase in recent years and wind farms (WFs) have an impact on the underlying surface conditions of climate system. This paper assesses the impacts of wind farms by analyzing the variations of the land surface temperature (LST) data for the period of 2003-2014 over a region consisted of 1097 turbines in the Huitengxile Wind Farm, the largest wind farm in Asia. We first compare the spatial coupling between the geographic layouts of the WFs and the spatial patterns of LST changes of two periods (post- versus pre- wind turbines construction) and then employ the difference of LST between WF pixels and surrounding non-WF pixels to quantify the effects of WFs. The results reveal that the LST at daytime increases by 0.52-0.86°C in winter, spring and autumn and decreases by about 0.56°C in summer over the WFs on average, with the spatial pattern of this warming or cooling generally coupled with the geographic distribution of the wind turbines, while the changes in LST at nighttime are much noisier. The daytime LST warming or cooling effects vary with seasons, and the strongest warming and tightest spatial coupling are in autumn months of September-November. The seasonal variations in albedo due to the construction of wind turbines are primarily responsible for the daytime LST changes. Areal mean decreases in winter, spring and autumn and increase in summer in albedo are observed over the WFs and the spatial pattern and magnitude of the changes in albedo couple very well with the layouts of the wind turbines. The increase (decrease) in albedo over the WFs indicates that WFs across the Huitengxile grassland absorb less (more) incoming radiation, thus resulting in a decrease (increase) in LST at daytime. The inter-annual variations in areal mean LST differences at daytime are highly correlated with those in areal mean albedo differences for all four seasons (R2=0.48~0.67). Our findings are in contrast

  19. Effect of Wind Turbine Noise on Workers' Sleep Disorder: A Case Study of Manjil Wind Farm in Northern Iran

    NASA Astrophysics Data System (ADS)

    Abbasi, Milad; Monnazzam, Mohammad Reza; Zakerian, Sayedabbolfazl; Yousefzadeh, Arsalan

    2015-04-01

    Noise from wind turbines is one of the most important factors affecting the health, welfare, and human sleep. This research was carried out to study the effect of wind turbine noise on workers' sleep disorder. For this, Manjil Wind Farm, because of the greater number of staff and turbines than other wind farms in Iran, was chosen as case study. A total number of 53 participants took part in this survey. They were classified into three groups of mechanics, security, and official. In this study, daytime sleepiness data of workers were gathered using Epworth Sleepiness Scales (ESS) was used to determine the level of daytime sleepiness among the workers. The 8-h equivalent sound level (LAeq,8h) was measured to determine the individuals' exposure at each occupational group. Finally, the effect of sound, age, and workers' experience on individuals' sleep disorder was analyzed through multiple regression analysis in the R software. The results showed that there was a positive and significant relationship between age, workers' experience, equivalent sound level, and the level of sleep disorder. When age is constant, sleep disorder will increase by 26% as per each 1 dB increase in equivalent sound level. In situations where equivalent sound level is constant, an increase of 17% in sleep disorder is occurred as per each year of work experience. Because of the difference in sound exposure in different occupational groups. The effect of noise in repairing group was about 6.5 times of official group and also 3.4 times of the security group. Sleep disorder effect caused by wind turbine noise in the security group is almost two times more than the official group. Unlike most studies on wind turbine noise that address the sleep disorder among inhabitants nearby wind farms, this study, for the first time in the world, examines the impact of wind turbine noise on sleep disorder of workers who are more closer to wind turbines and exposed to higher levels of noise. So despite all the

  20. Estimating direct fatality impacts at wind farms: how far we’ve come, where we have yet to go

    USGS Publications Warehouse

    Huso, Manuela M.; Schwartz, Susan Savitt

    2013-01-01

    Measuring the potential impacts of wind farms on wildlife can be difficult and may require development of new statistical tools and models to accurately reflect the measurement process. This presentation reviews the recent history of approaches to estimating wildlife fatality under the unique conditions encountered at wind farms, their unifying themes and their potential shortcomings. Avenues of future research are suggested to continue to address the needs of resource managers and industry in understanding direct impacts of wind turbine-caused wildlife fatality.

  1. Crop/Wind-energy Experiment (CWEX): Observations of surface-layer, boundary-layer and mesoscale interactions with a wind farm

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Perturbations of mean and turbulent wind characteristics by large wind turbines modify fluxes between the vegetated surface and the lower boundary layer. While simulations have suggested that wind farms could significantly change surface fluxes of heat, momentum, moisture, and CO2 over hundreds of s...

  2. CWEX: Crop/wind-energy experiment: Observations of surface-layer, boundary-layer and mesoscale interactions with a wind farm

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Large wind turbines perturb mean and turbulent wind characteristics, which modify fluxes between the vegetated surface and the lower boundary layer. While simulations have suggested that wind farms could create significant changes in surface fluxes of heat, momentum, moisture, and CO2 over hundreds ...

  3. Operating Reserves and Wind Power Integration: An International Comparison; Preprint

    SciTech Connect

    Milligan, M.; Donohoo, P.; Lew, D.; Ela, E.; Kirby, B.; Holttinen, H.; Lannoye, E.; Flynn, D.; O'Malley, M.; Miller, N.; Eriksen, P. B.; Gottig, A.; Rawn, B.; Gibescu, M.; Lazaro, E. G.; Robitaille, A.; Kamwa, I.

    2010-10-01

    This paper provides a high-level international comparison of methods and key results from both operating practice and integration analysis, based on an informal International Energy Agency Task 25: Large-scale Wind Integration.

  4. 77 FR 48138 - Topaz Solar Farms LLC; High Plains Ranch II, LLC; Bethel Wind Energy LLC; Rippey Wind Energy LLC...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-13

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket Nos. EG12-63-000; EG12-64-000; EG12-65-000; EG12-66-000; EG12- 67-000; EG12-68-000; EG12-69-000] Topaz Solar Farms LLC; High Plains Ranch II, LLC; Bethel Wind...

  5. Multiscale aeroelastic simulations of large wind farms in the atmospheric boundary layer

    NASA Astrophysics Data System (ADS)

    Vitsas, Athanasios; Meyers, Johan

    2016-09-01

    In large wind farms, the turbulence induced by each turbine results in high overall turbulence levels that can be detrimental for downstream wind turbine components. In the current study, we scrutinize structural loads and dynamics, and their correlation to turbulent flow structures by conducting aeroelastic simulations in wind farms. To this end, a pseudospectral large-eddy simulation solver is coupled with a multibody dynamics module in a multiscale framework. The multirate approach leads us naturally to the development of an aeroelastic actuator sector model that represents the wind turbine forces on the flow. This makes it computationally feasible to simulate long time horizons of the two-way coupled aeroelastic system. Hence, it allows us to look at the interaction of the turbine structure with the turbulent boundary layer and the wakes of multiple turbine arrays, and to get estimates of damage equivalent loads and structural loading statistics, as longer time series are available. Results are shown for two typical wind farm layouts, i.e. aligned and staggered, for above-rated flow regimes.

  6. Cumulative impact assessments and bird/wind farm interactions: Developing a conceptual framework

    SciTech Connect

    Masden, Elizabeth A.; Fox, Anthony D.; Furness, Robert W.; Bullman, Rhys; Haydon, Daniel T.

    2010-01-15

    The wind power industry has grown rapidly in the UK to meet EU targets of sourcing 20% of energy from renewable sources by 2020. Although wind power is a renewable energy source, there are environmental concerns over increasing numbers of wind farm proposals and associated cumulative impacts. Individually, a wind farm, or indeed any action, may have minor effects on the environment, but collectively these may be significant, potentially greater than the sum of the individual parts acting alone. EU and UK legislation requires a cumulative impact assessment (CIA) as part of Environmental Impact Assessments (EIA). However, in the absence of detailed guidance and definitions, such assessments within EIA are rarely adequate, restricting the acquisition of basic knowledge about the cumulative impacts of wind farms on bird populations. Here we propose a conceptual framework to promote transparency in CIA through the explicit definition of impacts, actions and scales within an assessment. Our framework requires improved legislative guidance on the actions to include in assessments, and advice on the appropriate baselines against which to assess impacts. Cumulative impacts are currently considered on restricted scales (spatial and temporal) relating to individual development EIAs. We propose that benefits would be gained from elevating CIA to a strategic level, as a component of spatially explicit planning.

  7. Toward understanding the physical link between turbines and microclimate impacts from in situ measurements in a large wind farm

    NASA Astrophysics Data System (ADS)

    Rajewski, Daniel A.; Takle, Eugene S.; Prueger, John H.; Doorenbos, Russell K.

    2016-11-01

    Recent wind farm studies have revealed elevated nighttime surface temperatures but have not validated physical mechanisms that create the observed effects. We report measurements of concurrent differences in surface wind speed, temperature, fluxes, and turbulence upwind and downwind of two turbine lines at the windward edge of a utility-scale wind farm. On the basis of these measurements, we offer a conceptual model based on physical mechanisms of how wind farms affect their own microclimate. Periods of documented curtailment and zero-power production of the wind farm offer useful opportunities to rigorously evaluate the microclimate impact of both stationary and operating turbines. During an 80 min nighttime wind farm curtailment, we measured abrupt and large changes in turbulent fluxes of momentum and heat leeward of the turbines. At night, wind speed decreases in the near wake when turbines are off but abruptly increases when turbine operation is resumed. Our measurements are compared with Moderate Resolution Imaging Spectroradiometer Terra and Aqua satellite measurements reporting wind farms to have higher nighttime surface temperatures. We demonstrate that turbine wakes modify surface fluxes continuously through the night, with similar magnitudes during the Terra and Aqua transit periods. Cooling occurs in the near wake and warming in the far wake when turbines are on, but cooling is negligible when turbines are off. Wind speed and surface stratification have a regulating effect of enhancing or decreasing the impact on surface microclimate due to turbine wake effects.

  8. Data-driven RANS for simulations of large wind farms

    NASA Astrophysics Data System (ADS)

    Iungo, G. V.; Viola, F.; Ciri, U.; Rotea, M. A.; Leonardi, S.

    2015-06-01

    In the wind energy industry there is a growing need for real-time predictions of wind turbine wake flows in order to optimize power plant control and inhibit detrimental wake interactions. To this aim, a data-driven RANS approach is proposed in order to achieve very low computational costs and adequate accuracy through the data assimilation procedure. The RANS simulations are implemented with a classical Boussinesq hypothesis and a mixing length turbulence closure model, which is calibrated through the available data. High-fidelity LES simulations of a utility-scale wind turbine operating with different tip speed ratios are used as database. It is shown that the mixing length model for the RANS simulations can be calibrated accurately through the Reynolds stress of the axial and radial velocity components, and the gradient of the axial velocity in the radial direction. It is found that the mixing length is roughly invariant in the very near wake, then it increases linearly with the downstream distance in the diffusive region. The variation rate of the mixing length in the downstream direction is proposed as a criterion to detect the transition between near wake and transition region of a wind turbine wake. Finally, RANS simulations were performed with the calibrated mixing length model, and a good agreement with the LES simulations is observed.

  9. Wake flow variability in a wind farm throughout the diurnal cycle

    NASA Astrophysics Data System (ADS)

    Abkar, Mahdi; Sharifi, Ahmad; Porté-Agel, Fernando

    2015-04-01

    The atmospheric boundary layer (ABL) undergoes substantial changes in its structure and dynamics in the course of a day due to the transient nature of forcing factors such as the surface fluxes of heat and momentum. The non-stationary nature of the mean wind and turbulence in the ABL, associated with the diurnal cycle, can in turn affect the structure of wind turbine wakes and their effects on power losses within wind farms. In this research, large-eddy simulation (LES) is used to study the evolution of the turbine wakes and their effects on power losses inside an idealized finite-size wind farm in the course of two full diurnal cycles. In the LES, turbulent subgrid-scale stresses are modeled using tuning-free Lagrangian scale-dependent dynamic models, while the turbine-induced forces are parameterized using a dynamic actuator disk model with rotation. To minimize the effects of the initial conditions on the results, our analysis is focused on the second diurnal cycle. The simulation results show a strong effect of atmospheric stability on the wind farm wakes and associated power losses. During the night, the relatively low turbulence intensity of the ambient ABL flow results in a relatively slow rate of entrainment of momentum into the wake and, consequently, a slow wake recovery. In contrast, during the day the positive buoyancy flux and associated turbulence production lead to a relatively high turbulence level in the background ABL flow, which enhances turbulent mixing and wake recovery. As a result, the averaged power deficit in the wind farm is found to increase with increasing thermal stability. In particular for that day, the averaged power deficit increased from 28% under the most convective condition to about 66% under the most stable condition.

  10. Scavenger removal: Bird and bat carcass persistence in a tropical wind farm

    NASA Astrophysics Data System (ADS)

    Villegas-Patraca, Rafael; Macías-Sánchez, Samuel; MacGregor-Fors, Ian; Muñoz-Robles, Carlos

    2012-08-01

    Energy produced by wind farms has diverse positive environmental effects, but can also be related to negative impacts, including wildlife mortality through collisions with wind turbines. Bird and bat mortality caused by collisions with wind turbines can be estimated indirectly by counting carcasses within wind farms. However, carcass removal by scavengers often biases such measurements. In this study, we identified the main scavengers removing bird and bat carcasses in a tropical wind farm. A known fate analysis was done to assess the effect of carcass type (i.e., small bird, large bird, bat), vegetation type (i.e., secondary vegetation, croplands) and season (dry and rainy seasons of 2009) on carcass persistence rates. We identified three main scavenger groups, with mammals being the most abundant group. Our results show high rates of carcass removal relative to previous studies, especially for bats; there were fewer remaining carcasses after 20 days in our tropical site than in non-tropical environments reported elsewhere. We found a higher carcass persistence rate during the rainy season than in the dry season, possibly due to a greater abundance of food resources for scavenger organisms in the rainy season. Although we found some evidence for higher persistence rates for large bird carcasses than for small bird and bat carcasses during the rainy season, overall carcass type was not a strong predictor of persistence rates. Similarly, we did not find a strong effect of vegetation type on carcass persistence rates. Results suggest that in order to estimate accurate bird and bat mortality in tropical wind farm areas, seasonality should be incorporated to correction factors of carcass removal rates.

  11. First comparison of LES of an offshore wind turbine wake with dual-Doppler lidar measurement in the offshore wind farm "alpha ventus"

    NASA Astrophysics Data System (ADS)

    Vollmer, L.; Trabucchi, D.; Witha, B.; van Dooren, M.; Trujillo, J. J.; Schneemann, J.; Kühn, M.

    2014-12-01

    The planning of offshore wind farms is still tainted with high risks due to unknown power losses and a higher level of fatigue loads due to wake effects. Recently, Large Eddy Simulations (LES) are more and more used for simulating offshore wind turbine wakes as they resolve the atmospheric turbulence as well as the wake turbulence.However, for an application of LES wind fields to assess offshore wind farm flow a proper validation with measured data is necessary.Several methods have been investigated at the University of Oldenburg to compare LES wind fields and lidar measurements. In this study we apply one of these methods to validate wake simulations of a single wake of a 5MW wind turbine in the German offshore wind farm "alpha ventus" with processed dual-Doppler lidar measurements in the same wind farm.The simulations are performed with the LES model PALM, which has been enhanced by two different approaches of actuator models to simulate the wake of single wind turbines and the interaction of wakes in wind farms. Effects of tower and nacelle are regarded as well as simple turbine control mechanisms. The simulations are initialized with comparable atmospheric conditions as during the time of lidar operation by using measurements from the adjacent meteorological mast FINO 1.Plan Position Indicator (PPI) measurements have been performed with two long-range wind lidars installed at different opposing platforms at the border of the wind farm. A Cartesian grid was overlapped to the scanned region and a dual-Doppler algorithm was applied in order to estimate the horizontal stationary wind field on the grid nodes. To our knowledge, the presented study is one of the first validations of LES wake simulations with lidar measurements and first which validates offshore LES wake simulations with 2D lidar data.

  12. 78 FR 57173 - Notice of Availability of the Record of Decision for the Mohave County Wind Farm Project, Mohave...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-17

    ... includes up to 243 wind turbine generators and associated infrastructure on approximately 35,329 acres of... Bureau of Land Management Notice of Availability of the Record of Decision for the Mohave County Wind... (ROD) for the Mohave County Wind Farm Project (Project). The Acting Assistant Secretary for Land...

  13. 75 FR 2138 - Interconnection of the Proposed Hermosa West Wind Farm Project, Wyoming (DOE/EIS-0438)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-14

    ... substantial natural resources conflicts. SWE's siting process for the wind turbine strings and associated... Area Power Administration Interconnection of the Proposed Hermosa West Wind Farm Project, Wyoming (DOE.... SUMMARY: Shell WindEnergy Inc. (SWE) applied to interconnect their proposed 300-megawatt (MW) Hermosa...

  14. Farm silo application of the 'TARP' wind energy conversion system

    NASA Astrophysics Data System (ADS)

    Duffy, R. E.; Butler, L.; Weisbrich, A.

    In this study, previously developed methods of determining wind turbine performance are adapted to the prediction of the performance of the silo application of the Toroidal Augmentor Rotor Platform (TARP). The system studied had three bladed turbines with untwisted, constant chord blades with a NACA 0015 airfoil section. Power coefficients of over one were predicted for two TARP configurations. The effects of varying blade chord, blade angle, and turbine angular velocity were evaluated. The economic feasibility of the silo application of the TARP was analyzed. It was found that this system could be economical in areas of high average wind velocity or where the cost of the energy available from other sources is high.

  15. Farm silo application of the ''TARP'' wind energy conversion system

    SciTech Connect

    Duffy, R.E.; Butler, L.; Weisbrich, A.

    1983-08-01

    In this study, previously developed methods of determining wind turbine performance are adapted to the prediction of the performance of the silo application of the Toroidal Augmentor Rotor Platform (TARP). The system studied had three bladed turbines with untwisted, constant chord blades with a NACA 0015 airfoil section. Power coefficients of over one were predicted for two TARP configurations. The effects of varying blade chord, blade angle, and turbine angular velocity were evaluated. The economic feasibility of the silo application of the TARP was analyzed. It was found that this system could be economical in areas of high average wind velocity or where the cost of the energy available from other sources is high.

  16. Diurnal and seasonal variations of wind farm impacts on land surface temperature over western Texas

    NASA Astrophysics Data System (ADS)

    Zhou, Liming; Tian, Yuhong; Baidya Roy, Somnath; Dai, Yongjiu; Chen, Haishan

    2013-07-01

    This paper analyzes seasonal and diurnal variations of MODerate resolution Imaging Spectroradiometer (MODIS) land surface temperature (LST) data at ~1.1 km for the period of 2003-2011 over a region in West-Central Texas, where four of the world's largest wind farms are located. Seasonal anomalies are created from MODIS Terra (~10:30 a.m. and 10:30 p.m. local solar time) and Aqua (~1:30 a.m. and 1:30 p.m. local solar time) LSTs, and their spatiotemporal variability is analyzed by comparing the LST changes between wind farm pixels (WFPs) and nearby non wind farm pixels (NNWFPs) using different methods under different quality controls. Our analyses show consistently that there is a warming effect of 0.31-0.70 °C at nighttime for the nine-year period during which data was collected over WFPs relative to NNWFPs, in all seasons for both Terra and Aqua measurements, while the changes at daytime are much noisier. The nighttime warming effect is much larger in summer than winter and at ~10:30 p.m. than ~1:30 a.m. and hence the largest warming effect is observed at ~10:30 p.m. in summer. The spatial pattern and magnitude of this warming effect couple very well with the geographic distribution of wind turbines and such coupling is stronger at nighttime than daytime and in summer than winter. Together, these results suggest that the warming effect observed in MODIS over wind farms are very likely attributable to the development of wind farms. This inference is consistent with the increasing number of operational wind turbines with time during the study period, the diurnal and seasonal variations in the frequency of wind speed and direction distribution, and the changes in near-surface atmospheric boundary layer (ABL) conditions due to wind farm operations. The nocturnal ABL is typically stable and much thinner than the daytime ABL and hence the turbine enhanced vertical mixing produces a stronger nighttime effect. The stronger wind speed and the higher frequency of the wind

  17. 3D augmented reality for improving social acceptance and public participation in wind farms planning

    NASA Astrophysics Data System (ADS)

    Grassi, S.; Klein, T. M.

    2016-09-01

    Wind energy is one of the most important source of renewable energy characterized by a significant growth in the last decades and giving a more and more relevant contribution to the energy supply. One of the main disadvantages of a faster integration of wind energy into the energy mix is related to the visual impact of wind turbines on the landscape. In addition, the siting of new massive infrastructures has the potential to threaten a community's well-being if new projects are perceived being unfair. The public perception of the impact of wind turbines on the landscape is also crucial for their acceptance. The implementation of wind energy projects is hampered often because of a lack of planning or communication tools enabling a more transparent and efficient interaction between all stakeholders involved in the projects (i.e. developers, local communities and administrations, NGOs, etc.). Concerning the visual assessment of wind farms, a critical gap lies in effective visualization tools to improve the public perception of alternative wind turbines layouts. In this paper, we describe the advantages of a 3D dynamical and interactive visualization platform for an augmented reality to support wind energy planners in order to enhance the social acceptance of new wind energy projects.

  18. Measurement of unsteady loading and power output variability in a micro wind farm model in a wind tunnel

    NASA Astrophysics Data System (ADS)

    Bossuyt, Juliaan; Howland, Michael F.; Meneveau, Charles; Meyers, Johan

    2017-01-01

    Unsteady loading and spatiotemporal characteristics of power output are measured in a wind tunnel experiment of a microscale wind farm model with 100 porous disk models. The model wind farm is placed in a scaled turbulent boundary layer, and six different layouts, varied from aligned to staggered, are considered. The measurements are done by making use of a specially designed small-scale porous disk model, instrumented with strain gages. The frequency response of the measurements goes up to the natural frequency of the model, which corresponds to a reduced frequency of 0.6 when normalized by the diameter and the mean hub height velocity. The equivalent range of timescales, scaled to field-scale values, is 15 s and longer. The accuracy and limitations of the acquisition technique are documented and verified with hot-wire measurements. The spatiotemporal measurement capabilities of the experimental setup are used to study the cross-correlation in the power output of various porous disk models of wind turbines. A significant correlation is confirmed between streamwise aligned models, while staggered models show an anti-correlation.

  19. The influence of wind farm development on the hydrochemistry and ecology of an upland stream.

    PubMed

    Millidine, K J; Malcolm, I A; McCartney, A; Laughton, R; Gibbins, C N; Fryer, R J

    2015-08-01

    Despite perceptions of pristine condition, upland environments are increasingly subject to a range of anthropogenic pressures including air pollution, climate change, land-use change and evolving land management strategies. Although they have received little attention to date, the large-scale development of upland wind farms also has the potential to disturb vegetation and soils, alter hydrology and water quality and, thus, impact freshwater ecosystems. This paper presents the findings of a 5-year study of the impacts of wind farm construction on the freshwater environment. Data on water quality, invertebrate and fish populations were collected for 2 years before construction and for the following 3 years covering the construction period and the initial period of the farm's operation. In contrast to previous studies, the impacts of the wind farm development were assessed for a suite of potentially affected hydrochemical variables using a before-after-control-impact (BACI) analysis that allowed separation of construction effects from spatial and temporal variability in hydroclimatological conditions, thereby providing an improved, more robust evidence base. There was a small but significant negative effect of construction on pH, alkalinity (Alk) and acid neutralising capacity (ANC) in the upper part of the treatment catchment, which was where the wind farm was situated. The effects were more marked under higher flow conditions. It is hypothesised that this reflects changes in hydrological processes with increased near-surface runoff or organic acid mobilisation. There was no indication that either invertebrate community structure or fish densities were impacted by construction and the resulting effects on water quality.

  20. Wind Farms in Rural Areas: How Far Do Community Benefits from Wind Farms Represent a Local Economic Development Opportunity?

    ERIC Educational Resources Information Center

    Munday, Max; Bristow, Gill; Cowell, Richard

    2011-01-01

    Although the large-scale deployment of renewable technologies can bring significant, localised economic and environmental changes, there has been remarkably little empirical investigation of the rural development implications. This paper seeks to redress this through an analysis of the economic development opportunities surrounding wind energy…

  1. Mapping Wind Farm Loads and Power Production - A Case Study on Horns Rev 1

    NASA Astrophysics Data System (ADS)

    Galinos, Christos; Dimitrov, Nikolay; Larsen, Torben J.; Natarajan, Anand; Hansen, Kurt S.

    2016-09-01

    This paper describes the development of a wind turbine (WT) component lifetime fatigue load variation map within an offshore wind farm. A case study on the offshore wind farm Horns Rev I is conducted with this purpose, by quantifying wake effects using the Dynamic Wake Meandering (DWM) method, which has previously been validated based on CFD, Lidar and full scale load measurements. Fully coupled aeroelastic load simulations using turbulent wind conditions are conducted for all wind directions and mean wind speeds between cut-in and cut-out using site specific turbulence level measurements. Based on the mean wind speed and direction distribution, the representative 20-year lifetime fatigue loads are calculated. It is found that the heaviest loaded WT is not the same when looking at blade root, tower top or tower base components. The blade loads are mainly dominated by the wake situations above rated wind speed and the highest loaded blades are in the easternmost row as the dominating wind direction is from West. Regarding the tower components, the highest loaded WTs are also located towards the eastern central location. The turbines with highest power production are, not surprisingly, the ones facing a free sector towards west and south. The power production results of few turbines are compared with SCADA data. The results of this paper are expected to have significance for operation and maintenance planning, where the schedules for inspection and service activities can be adjusted to the requirements arising from the varying fatigue levels. Furthermore, the results can be used in the context of remaining fatigue lifetime assessment and planning of decommissioning.

  2. Soaring Migratory Birds Avoid Wind Farm in the Isthmus of Tehuantepec, Southern Mexico

    PubMed Central

    Villegas-Patraca, Rafael; Cabrera-Cruz, Sergio A.; Herrera-Alsina, Leonel

    2014-01-01

    The number of wind farms operating in the Isthmus of Tehuantepec, southern Mexico, has rapidly increased in recent years; yet, this region serves as a major migration route for various soaring birds, including Turkey Vultures (Cathartes aura) and Swainson's Hawks (Buteo swainsoni). We analyzed the flight trajectories of soaring migrant birds passing the La Venta II wind farm during the two migratory seasons of 2011, to determine whether an avoidance pattern existed or not. We recorded three polar coordinates for the flight path of migrating soaring birds that were detected using marine radar, plotted the flight trajectories and estimated the number of trajectories that intersected the polygon defined by the wind turbines of La Venta II. Finally, we estimated the actual number of intersections per kilometer and compared this value with the null distributions obtained by running 10,000 simulations of our datasets. The observed number of intersections per kilometer fell within or beyond the lower end of the null distributions in the five models proposed for the fall season and in three of the four models proposed for the spring season. Flight trajectories had a non-random distribution around La Venta II, suggesting a strong avoidance pattern during fall and a possible avoidance pattern during spring. We suggest that a nearby ridgeline plays an important role in this pattern, an issue that may be incorporated into strategies to minimize the potential negative impacts of future wind farms on soaring birds. Studies evaluating these issues in the Isthmus of Tehuantepec have not been previously published; hence this work contributes important baseline information about the movement patterns of soaring birds and its relationship to wind farms in the region. PMID:24647442

  3. Soaring migratory birds avoid wind farm in the Isthmus of Tehuantepec, southern Mexico.

    PubMed

    Villegas-Patraca, Rafael; Cabrera-Cruz, Sergio A; Herrera-Alsina, Leonel

    2014-01-01

    The number of wind farms operating in the Isthmus of Tehuantepec, southern Mexico, has rapidly increased in recent years; yet, this region serves as a major migration route for various soaring birds, including Turkey Vultures (Cathartes aura) and Swainson's Hawks (Buteo swainsoni). We analyzed the flight trajectories of soaring migrant birds passing the La Venta II wind farm during the two migratory seasons of 2011, to determine whether an avoidance pattern existed or not. We recorded three polar coordinates for the flight path of migrating soaring birds that were detected using marine radar, plotted the flight trajectories and estimated the number of trajectories that intersected the polygon defined by the wind turbines of La Venta II. Finally, we estimated the actual number of intersections per kilometer and compared this value with the null distributions obtained by running 10,000 simulations of our datasets. The observed number of intersections per kilometer fell within or beyond the lower end of the null distributions in the five models proposed for the fall season and in three of the four models proposed for the spring season. Flight trajectories had a non-random distribution around La Venta II, suggesting a strong avoidance pattern during fall and a possible avoidance pattern during spring. We suggest that a nearby ridgeline plays an important role in this pattern, an issue that may be incorporated into strategies to minimize the potential negative impacts of future wind farms on soaring birds. Studies evaluating these issues in the Isthmus of Tehuantepec have not been previously published; hence this work contributes important baseline information about the movement patterns of soaring birds and its relationship to wind farms in the region.

  4. Modelling impacts of offshore wind farms on trophic web: the Courseulles-sur-Mer case study

    NASA Astrophysics Data System (ADS)

    Raoux, Aurore; Pezy, Jean-Philippe; Dauvin, Jean-Claude; Tecchio, samuele; Degraer, Steven; Wilhelmsson, Dan; Niquil, Nathalie

    2016-04-01

    The French government is planning the construction of three offshore wind farms in Normandy. These offshore wind farms will integrate into an ecosystem already subject to a growing number of anthropogenic disturbances such as transportation, fishing, sediment deposit, and sediment extraction. The possible effects of this cumulative stressors on ecosystem functioning are still unknown, but they could impact their resilience, making them susceptible to changes from one stable state to another. Understanding the behaviour of these marine coastal complex systems is essential in order to anticipate potential state changes, and to implement conservation actions in a sustainable manner. Currently, there are no global and integrated studies on the effects of construction and exploitation of offshore wind farms. Moreover, approaches are generally focused on the conservation of some species or groups of species. Here, we develop a holistic and integrated view of ecosystem impacts through the use of trophic webs modelling tools. Trophic models describe the interaction between biological compartments at different trophic levels and are based on the quantification of flow of energy and matter in ecosystems. They allow the application of numerical methods for the characterization of emergent properties of the ecosystem, also called Ecological Network Analysis (ENA). These indices have been proposed as ecosystem health indicators as they have been demonstrated to be sensitive to different impacts on marine ecosystems. We present here in detail the strategy for analysing the potential environmental impacts of the construction of the Courseulles-sur-Mer offshore wind farm (Bay of Seine) such as the reef effect through the use of the Ecopath with Ecosim software. Similar Ecopath simulations will be made in the future on the Le Tréport offshore wind farm site. Results will contribute to a better knowledge of the impacts of the offshore wind farms on ecosystems. They also allow to

  5. Engineering models for merging wakes in wind farm optimization applications

    NASA Astrophysics Data System (ADS)

    Machefaux, E.; Larsen, G. C.; Murcia Leon, J. P.

    2015-06-01

    The present paper deals with validation of 4 different engineering wake superposition approaches against detailed CFD simulations and covering different turbine interspacing, ambient turbulence intensities and mean wind speeds. The first engineering model is a simple linear superposition of wake deficits as applied in e.g. Fuga. The second approach is the square root of sums of squares approach, which is applied in the widely used PARK program. The third approach, which is presently used with the Dynamic Wake Meandering (DWM) model, assumes that the wake affected downstream flow field to be determined by a superposition of the ambient flow field and the dominating wake among contributions from all upstream turbines at any spatial position and at any time. The last approach developed by G.C. Larsen is a newly developed model based on a parabolic type of approach, which combines wake deficits successively. The study indicates that wake interaction depends strongly on the relative wake deficit magnitude, i.e. the deficit magnitude normalized with respect to the ambient mean wind speed, and that the dominant wake assumption within the DWM framework is the most accurate.

  6. Performance and wake predictions of HAWTs in wind farms

    SciTech Connect

    Leclerc, C.; Masson, C.; Paraschivoiu, I.

    1997-12-31

    The present contribution proposes and describes a promising way towards performance prediction of an arbitrary array of turbines. It is based on the solution of the time-averaged, steady-state, incompressible Navier-Stokes equations with an appropriate turbulence closure model. The turbines are represented by distributions of momentum sources in the Navier-Stokes equations. In this paper, the applicability and viability of the proposed methodology is demonstrated using an axisymmetric implementation. The k-{epsilon} model has been chosen for the closure of the time-averaged, turbulent flow equations and the properties of the incident flow correspond to those of a neutral atmospheric boundary layer. The proposed mathematical model is solved using a Control-Volume Finite Element Method (CVFEM). Detailed results have been obtained using the proposed method for an isolated wind turbine and for two turbines one behind another. In the case of an isolated turbine, accurate wake velocity deficit predictions are obtained and an increase in power due to atmospheric turbulence is found in agreement with measurements. In the case of two turbines, the proposed methodology provides an appropriate modelling of the wind-turbine wake and a realistic prediction of the performance degradation of the downstream turbine.

  7. Application of LES Technique to Diagnosis of Wind Farm by Using High Resolution Elevation Data

    NASA Astrophysics Data System (ADS)

    Uchida, Takanori; Ohya, Yuji

    We are developing the numerical model called the RIAM-COMPACT (Research Institute for Applied Mechanics, Kyushu University, Computational Prediction of Airflow over Complex Terrain). The object domain of this numerical model is from several m to several km, and can predict the airflow and the gas diffusion over complex terrain with high precision. The RIAM-COMPACT has already been marketed by certain tie-up companies. The estimation of the annual electrical power output is also possible now based on the field observation data. In the present study, wind simulation of an actual wind farm was executed using the high resolution elevation data. As a result, an appropriate point and an inappropriate point for locating a wind turbine generator were shown based on the numerical results obtained. This cause was found to be a topographical irregularity in front of the wind turbine generator.

  8. Final Report DE-EE0005380: Assessment of Offshore Wind Farm Effects on Sea Surface, Subsurface and Airborne Electronic Systems

    SciTech Connect

    Ling, Hao; Hamilton, Mark F.; Bhalla, Rajan; Brown, Walter E.; Hay, Todd A.; Whitelonis, Nicholas J.; Yang, Shang-Te; Naqvi, Aale R.

    2013-09-30

    Offshore wind energy is a valuable resource that can provide a significant boost to the US renewable energy portfolio. A current constraint to the development of offshore wind farms is the potential for interference to be caused by large wind farms on existing electronic and acoustical equipment such as radar and sonar systems for surveillance, navigation and communications. The US Department of Energy funded this study as an objective assessment of possible interference to various types of equipment operating in the marine environment where offshore wind farms could be installed. The objective of this project was to conduct a baseline evaluation of electromagnetic and acoustical challenges to sea surface, subsurface and airborne electronic systems presented by offshore wind farms. To accomplish this goal, the following tasks were carried out: (1) survey electronic systems that can potentially be impacted by large offshore wind farms, and identify impact assessment studies and research and development activities both within and outside the US, (2) engage key stakeholders to identify their possible concerns and operating requirements, (3) conduct first-principle modeling on the interactions of electromagnetic signals with, and the radiation of underwater acoustic signals from, offshore wind farms to evaluate the effect of such interactions on electronic systems, and (4) provide impact assessments, recommend mitigation methods, prioritize future research directions, and disseminate project findings. This report provides a detailed description of the methodologies used to carry out the study, key findings of the study, and a list of recommendations derived based the findings.

  9. Regional scale hydrodynamic modelling of offshore wind farm development areas off the east coast of Scotland

    NASA Astrophysics Data System (ADS)

    O'Hara Murray, Rory; Gallego, Alejandro

    2013-04-01

    There is considerable interest in Scotland, supported by the Scottish Government, in the expansion of renewable energy production. In particular, significant offshore wind energy developments are already planned in coastal waters to the east of the Forth and Tay estuaries. It is important to understand the local and cumulative environmental impact of such developments within this region, to aid licensing decisions but also to inform marine spatial planning in general. Substantial wind farm developments may affect physical processes within the region, such as tidal-, wind-, and wave-driven circulation, as well as coastal sediment transport and more complex estuarine dynamics. Such physical impacts could have ecological and, ultimately, socio-economic consequences. The Firth of Forth and Tay areas both exhibit complex estuarine characteristics due to fresh water input, complex bathymetry and coastline, and tidal mixing. Our goal is to construct an unstructured grid hydrodynamic model of the wider Firth of Forth and Tay region using the Finite-Volume Coastal Ocean Model (FVCOM), resolving the complex estuarine hydrography of the area and representing offshore wind developments. Hydrodynamic modelling will provide an accurate baseline of the hydrography in this region but also allow the assessment of the effect on the physical environment of multiple wind farm development scenarios.

  10. A case study of effects of atmospheric boundary layer turbulence, wind speed, and stability on wind farm induced temperature changes using observations from a field campaign

    NASA Astrophysics Data System (ADS)

    Xia, Geng; Zhou, Liming; Freedman, Jeffrey M.; Roy, Somnath Baidya; Harris, Ronald A.; Cervarich, Matthew Charles

    2016-04-01

    Recent studies using satellite observations show that operational wind farms in west-central Texas increase local nighttime land surface temperature (LST) by 0.31-0.70 °C, but no noticeable impact is detected during daytime, and that the diurnal and seasonal variations in the magnitude of this warming are likely determined by those in the magnitude of wind speed. This paper further explores these findings by using the data from a year-long field campaign and nearby radiosonde observations to investigate how thermodynamic profiles and surface-atmosphere exchange processes work in tandem with the presence of wind farms to affect the local climate. Combined with satellite data analyses, we find that wind farm impacts on LST are predominantly determined by the relative ratio of turbulence kinetic energy (TKE) induced by the wind turbines compared to the background TKE. This ratio explains not only the day-night contrast of the wind farm impact and the warming magnitude of nighttime LST over the wind farms, but also most of the seasonal variations in the nighttime LST changes. These results indicate that the diurnal and seasonal variations in the turbine-induced turbulence relative to the background TKE play an essential role in determining those in the magnitude of LST changes over the wind farms. In addition, atmospheric stability determines the sign and strength of the net downward heat transport as well as the magnitude of the background TKE. The study highlights the need for better understanding of atmospheric boundary layer and wind farm interactions, and for better parameterizations of sub-grid scale turbulent mixing in numerical weather prediction and climate models.

  11. Assessment of Subsynchronous Resonance in Series Compensated Type-1 Wind Farm

    NASA Astrophysics Data System (ADS)

    Gotmare, Gajanan V.; Virulkar, Vasudeo B.

    2014-07-01

    Series compensation is used in power systems for enhancing the power transfer capability of the transmission line when transmission distances are large. Now, it is well known fact that subsynchronous resonance (SSR) is predominant in traditional turbine-generators connected to series compensated transmission line. Although SSR and its mitigation techniques for conventional turbine-generator system are well documented, enough literature is not available on SSR phenomenon in the context of series compensated wind farm systems. This work addresses the assessment of SSR in wind farm connected to the series compensated electrical power system. The Eigen value analysis tool is used to ascertain the existence of SSR. The PSCAD/EMTDC software is used for simulation and validation of the results in this work.

  12. Electromagnetic Simulation of the Near-Field Distribution around a Wind Farm

    DOE PAGES

    Yang, Shang-Te; Ling, Hao

    2013-01-01

    An efficienmore » t approach to compute the near-field distribution around and within a wind farm under plane wave excitation is proposed. To make the problem computationally tractable, several simplifying assumptions are made based on the geometry problem. By comparing the approximations against full-wave simulations at 500 MHz, it is shown that the assumptions do not introduce significant errors into the resulting near-field distribution. The near fields around a 3 × 3 wind farm are computed using the developed methodology at 150 MHz, 500 MHz, and 3 GHz. Both the multipath interference patterns and the forward shadows are predicted by the proposed method.« less

  13. Economic analysis of wind-powered farmhouse and farm building heating systems. Final report

    SciTech Connect

    Stafford, R.W.; Greeb, F.J.; Smith, M.F.; Des Chenes, C.; Weaver, N.L.

    1981-01-01

    The study evaluated the break-even values of wind energy for selected farmhouses and farm buildings focusing on the effects of thermal storage on the use of WECS production and value. Farmhouse structural models include three types derived from a national survey - an older, a more modern, and a passive solar structure. The eight farm building applications that were analyzed include: poultry-layers, poultry-brooding/layers, poultry-broilers, poultry-turkeys, swine-farrowing, swine-growing/finishing, dairy, and lambing. These farm buildings represent the spectrum of animal types, heating energy use, and major contributions to national agricultural economic values. All energy analyses were based on hour-by-hour computations which allowed for growth of animals, sensible and latent heat production, and ventilation requirements. Hourly or three-hourly weather data obtained from the National Climatic Center was used for the nine chosen analysis sites, located throughout the United States and corresponding to regional agricultural production centers.

  14. Economic analysis of wind-powered farmhouse and farm building heating systems

    NASA Astrophysics Data System (ADS)

    Stafford, R. W.; Greeb, F. J.; Smith, M. H.; Deschenes, C.; Weaver, N. L.

    1981-01-01

    The break even values of wind energy for selected farmhouses and farm buildings focusing on the effects of thermal storage on the use of WECS production were evaluated. Farmhouse structural models include three types derived from a national survey: an older, a more modern, and a passive solar structure. The eight farm building applications include: (1) poultry layers; (2) poultry brooding/layers; (3) poultry broilers; (4) poultry turkeys; (5) swine farrowing; (6) swine growing/finishing; (7) dairy; and (8) lambing. The farm buildings represent the spectrum of animal types, heating energy use, and major contributions to national agricultural economic values. All energy analyses are based on hour by hour computations which allow for growth of animals, sensible and latent heat production, and ventilation requirements.

  15. An optimal control framework for dynamic induction control of wind farms and their interaction with the atmospheric boundary layer.

    PubMed

    Munters, W; Meyers, J

    2017-04-13

    Complex turbine wake interactions play an important role in overall energy extraction in large wind farms. Current control strategies optimize individual turbine power, and lead to significant energy losses in wind farms compared with lone-standing wind turbines. In recent work, an optimal coordinated control framework was introduced (Goit & Meyers 2015 J. Fluid Mech.768, 5-50 (doi:10.1017/jfm.2015.70)). Here, we further elaborate on this framework, quantify the influence of optimization parameters and introduce new simulation results for which gains in power production of up to 21% are observed.This article is part of the themed issue 'Wind energy in complex terrains'.

  16. Advanced Modeling System for Optimization of Wind Farm Layout and Wind Turbine Sizing Using a Multi-Level Extended Pattern Search Algorithm

    SciTech Connect

    DuPont, Bryony; Cagan, Jonathan; Moriarty, Patrick

    2016-07-01

    This paper presents a system of modeling advances that can be applied in the computational optimization of wind plants. These modeling advances include accurate cost and power modeling, partial wake interaction, and the effects of varying atmospheric stability. To validate the use of this advanced modeling system, it is employed within an Extended Pattern Search (EPS)-Multi-Agent System (MAS) optimization approach for multiple wind scenarios. The wind farm layout optimization problem involves optimizing the position and size of wind turbines such that the aerodynamic effects of upstream turbines are reduced, which increases the effective wind speed and resultant power at each turbine. The EPS-MAS optimization algorithm employs a profit objective, and an overarching search determines individual turbine positions, with a concurrent EPS-MAS determining the optimal hub height and rotor diameter for each turbine. Two wind cases are considered: (1) constant, unidirectional wind, and (2) three discrete wind speeds and varying wind directions, each of which have a probability of occurrence. Results show the advantages of applying the series of advanced models compared to previous application of an EPS with less advanced models to wind farm layout optimization, and imply best practices for computational optimization of wind farms with improved accuracy.

  17. Meeting the quest for spatial efficiency: progress and prospects of extensive aquaculture within offshore wind farms

    NASA Astrophysics Data System (ADS)

    Buck, B. H.; Krause, G.; Michler-Cieluch, T.; Brenner, M.; Buchholz, C. M.; Busch, J. A.; Fisch, R.; Geisen, M.; Zielinski, O.

    2008-09-01

    Along the German North Sea coast, the observed high spatial competition of stakeholders has encouraged the idea of integrating open ocean aquaculture in conjunction with offshore wind farms beyond the 12 miles zone. The article provides an overview on the current state of transdisciplinary research on a potential implementation of such a multifunctional use concept on a showcase basis, covering biological, technical, economic and social/policy aspects as well as private-public partnerships and the relevant institutional bodies. We show that the cultivation of seaweeds and blue mussels is biologically and technically feasible in a high-energy environment using modified cultivation strategies. The point of departure of our multi-use concept was that the solid groundings of wind turbines could serve as attachment points for the aquaculture installations and become the key to the successful commercial cultivation of any offshore aquatic organism. However, spaces in between the turbines are also attractive for farming projects, since public access is restricted and thus the cultivation site protected from outside influences. An economic analysis of different operation scenarios indicates that the market price and the annual settlement success of juvenile mussels are the main factors that determine the breakeven point. Social and policy science research reveals that the integration of relevant actors into the development of a multi-use concept for a wind farm-mariculture interaction is a complex and controversial issue. Combining knowledge and experience of wind farm planners as well as mussel fishermen and mariculturists within the framework of national and EU policies is probably the most important component for designing and developing an effective offshore co-management regime to limit the consumption of ocean space.

  18. Synergistic Effects of Turbine Wakes and Atmospheric Stability on Power Production at an Onshore Wind Farm

    SciTech Connect

    Wharton, S; Lundquist, J K; Marjanovic, N

    2012-01-25

    This report examines the complex interactions between atmospheric stability and turbine-induced wakes on downwind turbine wind speed and power production at a West Coast North American multi-MW wind farm. Wakes are generated when the upwind flow field is distorted by the mechanical movement of the wind turbine blades. This has two consequences for downwind turbines: (1) the downwind turbine encounters wind flows with reduced velocity and (2) the downwind turbine encounters increased turbulence across multiple length scales via mechanical turbulence production by the upwind turbine. This increase in turbulence on top of ambient levels may increase aerodynamic fatigue loads on the blades and reduce the lifetime of turbine component parts. Furthermore, ambient atmospheric conditions, including atmospheric stability, i.e., thermal stratification in the lower boundary layer, play an important role in wake dissipation. Higher levels of ambient turbulence (i.e., a convective or unstable boundary layer) lead to higher turbulent mixing in the wake and a faster recovery in the velocity flow field downwind of a turbine. Lower levels of ambient turbulence, as in a stable boundary layer, will lead to more persistent wakes. The wake of a wind turbine can be divided into two regions: the near wake and far wake, as illustrated in Figure 1. The near wake is formed when the turbine structure alters the shape of the flow field and usually persists one rotor diameter (D) downstream. The difference between the air inside and outside of the near wake results in a shear layer. This shear layer thickens as it moves downstream and forms turbulent eddies of multiple length scales. As the wake travels downstream, it expands depending on the level of ambient turbulence and meanders (i.e., travels in non-uniform path). Schepers estimates that the wake is fully expanded at a distance of 2.25 D and the far wake region begins at 2-5 D downstream. The actual distance traveled before the wake

  19. Energy profiling of demersal fish: a case-study in wind farm artificial reefs.

    PubMed

    De Troch, Marleen; Reubens, Jan T; Heirman, Elke; Degraer, Steven; Vincx, Magda

    2013-12-01

    The construction of wind farms introduces artificial hard substrates in sandy sediments. As Atlantic cod (Gadus morhua) and pouting (Trisopterus luscus) tend to aggregate in order to feed around these reefs, energy profiling and trophic markers were applied to study their feeding ecology in a wind farm in the Belgian part of the North Sea. The proximate composition (carbohydrates, proteins and lipids) differed significantly between liver and muscle tissue but not between fish species or between their potential prey species. Atlantic cod showed to consume more energy than pouting. The latter had a higher overall energy reserve and can theoretically survive twice as long on the available energy than cod. In autumn, both fish species could survive longer on their energy than in spring. Polyunsaturated fatty acids were found in high concentrations in fish liver. The prey species Jassa and Pisidia were both rich in EPA while Jassa had a higher DHA content than Pisidia. Energy profiling supported the statement that wind farm artificial reefs are suitable feeding ground for both fish species. Sufficient energy levels were recorded and there is no indication of competition.

  20. Investigation of sonar transponders for offshore wind farms: modeling approach, experimental setup, and results.

    PubMed

    Fricke, Moritz B; Rolfes, Raimund

    2013-11-01

    The installation of offshore wind farms in the German Exclusive Economic Zone requires the deployment of sonar transponders to prevent collisions with submarines. The general requirements for these systems have been previously worked out by the Research Department for Underwater Acoustics and Marine Geophysics of the Bundeswehr. In this article, the major results of the research project "Investigation of Sonar Transponders for Offshore Wind Farms" are presented. For theoretical investigations a hybrid approach was implemented using the boundary element method to calculate the source directivity and a three-dimensional ray-tracing algorithm to estimate the transmission loss. The angle-dependence of the sound field as well as the weather-dependence of the transmission loss are compared to experimental results gathered at the offshore wind farm alpha ventus, located 45 km north of the island Borkum. While theoretical and experimental results are in general agreement, the implemented model slightly underestimates scattering at the rough sea surface. It is found that the source level of 200 dB re 1 μPa at 1 m is adequate to satisfy the detectability of the warning sequence at distances up to 2 NM (≈3.7 km) within a horizontal sector of ±60° if realistic assumptions about signal-processing and noise are made. An arrangement to enlarge the angular coverage is discussed.

  1. Data-Mining-Based Intelligent Differential Relaying for Transmission Lines Including UPFC and Wind Farms.

    PubMed

    Jena, Manas Kumar; Samantaray, Subhransu Ranjan

    2016-01-01

    This paper presents a data-mining-based intelligent differential relaying scheme for transmission lines, including flexible ac transmission system device, such as unified power flow controller (UPFC) and wind farms. Initially, the current and voltage signals are processed through extended Kalman filter phasor measurement unit for phasor estimation, and 21 potential features are computed at both ends of the line. Once the features are extracted at both ends, the corresponding differential features are derived. These differential features are fed to a data-mining model known as decision tree (DT) to provide the final relaying decision. The proposed technique has been extensively tested for single-circuit transmission line, including UPFC and wind farms with in-feed, double-circuit line with UPFC on one line and wind farm as one of the substations with wide variations in operating parameters. The test results obtained from simulation as well as in real-time digital simulator testing indicate that the DT-based intelligent differential relaying scheme is highly reliable and accurate with a response time of 2.25 cycles from the fault inception.

  2. Peatland carbon cycling at a Scottish wind farm: the role of plant-soil interactions

    NASA Astrophysics Data System (ADS)

    Richardson, Harriett; Whitaker, Jeanette; Waldron, Susan; Ostle, Nick

    2013-04-01

    Peatlands play a fundamental role in the terrestrial carbon cycle by storing 1/3 of the world's soil carbon (Limpens et al. 2008). In the UK, peatlands are often located in areas with potential for electricity generation by harvesting wind energy. Concerns have been raised, however, over the stability of these carbon stocks when large scale wind developments are sited upon them. This project aims to improve understanding of the impact of wind farms on carbon sequestration in peatlands. Wind turbine 'wake-effects' can alter microclimatic conditions, as a result of significant differences in air temperature, humidity, wind speed and turbulence (Baidya Roy and Traiteur 2010). These changes are likely to have a significant impact on above and below ground abiotic conditions and biotic properties, together with the processes they regulate that govern peatland carbon cycling. Specifically, the effects of interactions between typical peatland plant functional types (graminoids, bryophytes and shrubs) (Ward et al. 2009) and peat microbial community composition and function are poorly resolved. We examined a spatial gradient across an area of blanket bog at Black Law wind farm (Lanarkshire, Scotland) and executed a series of controlled mesocosm experiments to examine the impacts of potential microclimatic changes on plant-soil interactions and carbon sequestration processes. In particular we focused on the form and function of plant and microbial communities as determinants of decomposition (Ward et al. 2010) and greenhouse gas (GHG) emissions (Artz 2009). Measurements of plant-litter-soil carbon, nitrogen, microbial community composition (i.e. phospholipid fatty acid biomarkers) and litter mass loss have been made across the wind farm peatland to attribute spatial variance in biotic and biogeochemical properties. In addition, multi-factorial mesocosm experiments have been made to determine how abiotic and biotic changes caused by wind farm effects could influence peat GHG

  3. Aquatic carbon export from peatland catchments recently undergone wind farm development

    NASA Astrophysics Data System (ADS)

    Smith, Ben; Waldron, Susan; Henderson, Andrew; Flowers, Hugh; Gilvear, David

    2013-04-01

    Scotland's peat landscapes are desirable locations for wind-based renewables due to high wind resources and low land use pressures in these areas. The environmental impact of sitting wind-based renewables on peats however, is unknown. Globally, peatlands are important terrestrial carbon stores. Given the topical nature of carbon-related issues, e.g. global warming and carbon footprints, it is imperative we help mitigate their degradation and maintain carbon sequestration. To do so, we need to better understand how peatland systems function with regards to their carbon balance (export versus sequestration) so we can assess their resilience and adaptation to hosting land-based renewable energy projects. Predicting carbon lost as a result of construction of wind farms built on peatland has not been fully characterised and this research will provide data that can supplement current 'carbon payback calculator' models for wind farms that aim to reinforce their 'green' credentials. Transfer of carbon from the terrestrial peatland systems to the aquatic freshwater and oceanic systems is most predominant during periods of high rainfall. It has been estimated that 50% of carbon is exported during only 10% of highest river flows, (Hinton et al., 1998). Furthermore, carbon export from peatlands is known to have a seasonal aspect with highest concentrations of dissolved organic carbon (DOC) found mostly in late summer months of August and September and lowest in December and January, (Dawson et al., 2004). Event sampling, where high intensity sample collection is carried out during high river flow periods, offers a better insight, understanding and estimation of carbon aquatic fluxes from peatland landscapes. The Gordonbush estate, near Brora, has an extensive peatland area where a wind farm development has recently been completed (April 2012). Investigations of aquatic carbon fluxes from this peatland system were started in July 2010, in conjunction with the start of

  4. Constant and seasonal drivers of bird communities in a wind farm: implications for conservation.

    PubMed

    Rosin, Zuzanna M; Skórka, Piotr; Szymański, Paweł; Tobolka, Marcin; Luczak, Andrzej; Tryjanowski, Piotr

    2016-01-01

    Background. One of the most difficult challenges for conservation biology is to reconcile growing human demands for resources with the rising need for protecting nature. Wind farms producing renewable energy have been recognised to be a threat for birds, but clear directives for environmental planning are still missing. Methods. Point counts were performed to study the relationship between eight environmental variables and bird populations in different parts of a year on the largest Polish wind farm between March 2011 and February 2013. Variables potentially related to species richness (Chao 1 estimator) and the abundance of the entire bird community as well as five selected farmland species were analysed with the use of generalized linear mixed models. Results. Some associations between the studied variables and bird populations were season/year specific, while others had a constant direction (positive or negative) across seasons and/or years. The latter were distance to the nearest turbine, field size, number of wind turbines, proximity of settlements and water bodies. Spatial autocorrelation and counting time were significantly correlated with bird population estimates but the directions of these relationships varied among seasons and years. Associations between abundance of individual species and environmental variables were species-specific. Conclusions. The results demonstrated a constant negative relationship between wind turbine proximity and bird numbers. Other environmental variables, such as field size, proximity of settlements and water bodies that also had constant associations with bird populations across seasons may be taken into account when minimizing adverse effects of wind farm development on birds or choosing optimal locations of new turbines.

  5. Constant and seasonal drivers of bird communities in a wind farm: implications for conservation

    PubMed Central

    Skórka, Piotr; Szymański, Paweł; Tobolka, Marcin; Luczak, Andrzej; Tryjanowski, Piotr

    2016-01-01

    Background. One of the most difficult challenges for conservation biology is to reconcile growing human demands for resources with the rising need for protecting nature. Wind farms producing renewable energy have been recognised to be a threat for birds, but clear directives for environmental planning are still missing. Methods. Point counts were performed to study the relationship between eight environmental variables and bird populations in different parts of a year on the largest Polish wind farm between March 2011 and February 2013. Variables potentially related to species richness (Chao 1 estimator) and the abundance of the entire bird community as well as five selected farmland species were analysed with the use of generalized linear mixed models. Results. Some associations between the studied variables and bird populations were season/year specific, while others had a constant direction (positive or negative) across seasons and/or years. The latter were distance to the nearest turbine, field size, number of wind turbines, proximity of settlements and water bodies. Spatial autocorrelation and counting time were significantly correlated with bird population estimates but the directions of these relationships varied among seasons and years. Associations between abundance of individual species and environmental variables were species-specific. Conclusions. The results demonstrated a constant negative relationship between wind turbine proximity and bird numbers. Other environmental variables, such as field size, proximity of settlements and water bodies that also had constant associations with bird populations across seasons may be taken into account when minimizing adverse effects of wind farm development on birds or choosing optimal locations of new turbines. PMID:27547516

  6. Modeling and resonance issues of wind farm integration with related facts applications

    NASA Astrophysics Data System (ADS)

    Auddy, Soubhik

    This thesis deals with electromechanical oscillations, torsional oscillations and resonance issues in power systems fed by conventional steam-turbine generators and emerging wind turbine generators. Solutions to several of these problems are proposed using Flexible AC Transmission Systems (FACTS) Controllers. Inter-area oscillations are investigated in the IEEE 39 bus system and are damped by a novel Static VAR Compensator (SVC) control signal utilizing a weighted sum of remote generator speeds derived from bus voltage angles. The weights are calculated from participation factor analysis using commercial software Dynamic Security Assessment (DSA) Power Tools and are validated by EMTDC/PSCAD simulations. Subsynchronous resonance (SSR) in steam-turbine generators has been traditionally damped with SVC using either local signals or signals derived from a combination of local signals. This thesis proposes a novel SVC controller based on remote generator speed for alleviating SSR. This controller is shown from EMTDC/PSCAD simulations to be much more effective than the previously reported controllers for the IEEE First SSR Benchmark system. The efficacy is demonstrated for all the four critical series compensation levels. With the worldwide growth of renewable energy, large wind farms are likely to be connected to series compensated networks for evacuation of bulk power. This may lead to the potential of SSR in the wind turbine generators. For the first time, a detailed electromagnetic transient study using EMTDC/PSCAD has been conducted in this thesis to demonstrate that subsynchronous resonance can be a cause of concern in series compensated wind farms at realistic levels of power flow and series compensation levels. Novel controllers for two FACTS devices - a Static VAR Compensator (SVC) and a Thyristor Controlled Series Capacitor (TCSC) - are proposed to mitigate SSR under all realistic compensation levels in a modified IEEE First Benchmark system. It is further

  7. IMPROVED CAPABILITIES FOR SITING WIND FARMS AND MITIGATING IMPACTS ON RADAR OBSERVATIONS

    SciTech Connect

    Chiswell, S.

    2010-01-15

    The development of efficient wind energy production involves challenges in technology and interoperability with other systems critical to the national mission. Wind turbines impact radar measurements as a result of their large reflectivity cross section as well as through the Doppler phase shift of their rotating blades. Wind farms can interfere with operational radar in multiple contexts, with degradation impacts on: weather detection such as tornado location, wind shear, and precipitation monitoring; tracking of airplanes where air traffic control software can lose the tracks of aircraft; and in identification of other low flying targets where a wind farm located close to a border might create a dead zone for detecting intruding objects. Objects in the path of an electromagnetic wave affect its propagation characteristics. This includes actual blockage of wave propagation by large individual objects and interference in wave continuity due to diffraction of the beam by individual or multiple objects. As an evolving industry, and the fastest growing segment of the energy sector, wind power is poised to make significant contributions in future energy generation requirements. The ability to develop comprehensive strategies for designing wind turbine locations that are mutually beneficial to both the wind industry that is dependent on production, and radar sites which the nation relies on, is critical to establishing reliable and secure wind energy. The mission needs of the Department of Homeland Security (DHS), Department of Defense (DOD), Federal Aviation Administration (FAA), and National Oceanographic and Atmospheric Administration (NOAA) dictate that the nation's radar systems remain uninhibited, to the maximum extent possible, by man-made obstructions; however, wind turbines can and do impact the surveillance footprint for monitoring airspace both for national defense as well as critical weather conditions which can impact life and property. As a result, a

  8. Exploring the influence of boundary layer stability on wind farms and their interplay with the surrounding environment

    NASA Astrophysics Data System (ADS)

    Vanderwende, Brian Joseph

    There is growing awareness in the wind power industry that boundary-layer stability influences wind turbine performance in meaningful ways. Stability is inextricably tied to the diurnal ebb and flow of heat, momentum, and moisture that drives weather. Boundary-layer stability is closely linked to low-level wind speeds, wind shear, wind veer, and turbulence. It is these myriad consequences of stability which directly impact turbines, both modifying performance and contributing to structural fatigue. I describe the influence of near-surface stability on the aggregate power output of a utility-scale wind farm in central North America. During convective conditions, the wind farm produced more power than during neutral conditions, while in stable conditions the farm underperformed. These results are statistically significant, despite the uncertainty involved in using nacelle anemometer measurements of wind speed. Next, I use lidar measurements from Iowa to categorize low-level jets and their impact on rotor-layer winds. Observed jets are similar to those studied in the Great Plains, though regional sloping terrain forcing is absent in Iowa. Rotor-layer wind speeds intensify during jet periods, but detrimental wind shear and veer also increase when jets occur. Simulations using the Weather Research and Forecasting (WRF) model with various input data and boundary-layer physics favorably reproduce jet features. I then utilize the same model to examine the impact of switching from maize to soybeans on rotor-layer winds during the peak of the growing season. The crop change was represented in the simulation by surface roughness. The switch produces a statistically significant increase in both wind speed and power output. Finally, I evaluate the performance of the wind farm parameterization (WFP) in WRF using high-resolution large eddy simulations (LES) from the same model. The wind speed and turbulence impacts estimated by the WFP compare favorably to LES flow for both

  9. Simulations of Vertical Axis Wind Turbine Farms in the Atmospheric Boundary Layer

    NASA Astrophysics Data System (ADS)

    Hezaveh, Seyed Hossein; Bou-Zeid, Elie; Lohry, Mark; Martinelli, Luigi

    2014-11-01

    Wind power is an abundant and clean source of energy that is increasingly being tapped to reduce the environmental footprint of anthropogenic activities. The vertical axis wind turbine (VAWT) technology is now being revisited due to some important advantages over horizontal axis wind turbines (HAWTS) that are particularly important for farms deployed offshore or in complex terrain. In this talk, we will present the implementation and testing of an actuator line model (ALM) for VAWTs in a large eddy simulation (LES) code for the atmospheric boundary layer, with the aim of optimizing large VAWT wind farm configurations. The force coefficients needed for the ALM are here obtained from blade resolving RANS simulations of individual turbines for each configuration. Comparison to various experimental results show that the model can very successfully reproduce observed wake characteristic. The influence of VAWT design parameters such as solidity, height to radius ratio, and tip speed ratio (TSR) on these wake characteristics, particularly the velocity deficit profile, is then investigated.

  10. Negative long term effects on harbour porpoises from a large scale offshore wind farm in the Baltic—evidence of slow recovery

    NASA Astrophysics Data System (ADS)

    Teilmann, Jonas; Carstensen, Jacob

    2012-12-01

    Offshore wind farms constitute a new and fast growing industry all over the world. This study investigates the long term impact on harbour porpoises, Phocoena phocoena, for more than 10 years (2001-12) from the first large scale offshore wind farm in the world, Nysted Offshore Wind Farm, in the Danish western Baltic Sea (72 × 2.3 MW turbines). The wind farm was brought into full operation in December 2003. At six stations, acoustic porpoise detectors (T-PODs) were placed inside the wind farm area and at a reference area 10 km to the east, to monitor porpoise echolocation activity as a proxy of porpoise presence. A modified statistical BACI design was applied to detect changes in porpoise presence before, during and after construction of the wind farm. The results show that the echolocation activity has significantly declined inside Nysted Offshore Wind Farm since the baseline in 2001-2 and has not fully recovered yet. The echolocation activity inside the wind farm has been gradually increasing (from 11% to 29% of the baseline level) since the construction of the wind farm, possibly due to habituation of the porpoises to the wind farm or enrichment of the environment due to reduced fishing and to artificial reef effects.

  11. Short-term ecological effects of an offshore wind farm in the Dutch coastal zone; a compilation

    NASA Astrophysics Data System (ADS)

    Lindeboom, H. J.; Kouwenhoven, H. J.; Bergman, M. J. N.; Bouma, S.; Brasseur, S.; Daan, R.; Fijn, R. C.; de Haan, D.; Dirksen, S.; van Hal, R.; Hille Ris Lambers, R.; ter Hofstede, R.; Krijgsveld, K. L.; Leopold, M.; Scheidat, M.

    2011-07-01

    The number of offshore wind farms is increasing rapidly, leading to questions about the environmental impact of such farms. In the Netherlands, an extensive monitoring programme is being executed at the first offshore wind farm (Offshore Windfarm Egmond aan Zee, OWEZ). This letter compiles the short-term (two years) results on a large number of faunal groups obtained so far. Impacts were expected from the new hard substratum, the moving rotor blades, possible underwater noise and the exclusion of fisheries. The results indicate no short-term effects on the benthos in the sandy area between the generators, while the new hard substratum of the monopiles and the scouring protection led to the establishment of new species and new fauna communities. Bivalve recruitment was not impacted by the OWEZ wind farm. Species composition of recruits in OWEZ and the surrounding reference areas is correlated with mud content of the sediment and water depth irrespective the presence of OWEZ. Recruit abundances in OWEZ were correlated with mud content, most likely to be attributed not to the presence of the farm but to the absence of fisheries. The fish community was highly dynamic both in time and space. So far, only minor effects upon fish assemblages especially near the monopiles have been observed. Some fish species, such as cod, seem to find shelter inside the farm. More porpoise clicks were recorded inside the farm than in the reference areas outside the farm. Several bird species seem to avoid the park while others are indifferent or are even attracted. The effects of the wind farm on a highly variable ecosystem are described. Overall, the OWEZ wind farm acts as a new type of habitat with a higher biodiversity of benthic organisms, a possibly increased use of the area by the benthos, fish, marine mammals and some bird species and a decreased use by several other bird species.

  12. Wind Power Forecasting Error Distributions: An International Comparison; Preprint

    SciTech Connect

    Hodge, B. M.; Lew, D.; Milligan, M.; Holttinen, H.; Sillanpaa, S.; Gomez-Lazaro, E.; Scharff, R.; Soder, L.; Larsen, X. G.; Giebel, G.; Flynn, D.; Dobschinski, J.

    2012-09-01

    Wind power forecasting is expected to be an important enabler for greater penetration of wind power into electricity systems. Because no wind forecasting system is perfect, a thorough understanding of the errors that do occur can be critical to system operation functions, such as the setting of operating reserve levels. This paper provides an international comparison of the distribution of wind power forecasting errors from operational systems, based on real forecast data. The paper concludes with an assessment of similarities and differences between the errors observed in different locations.

  13. Site characterization of foundation soil for Offshore Wind Farms - an example from the German North Sea

    NASA Astrophysics Data System (ADS)

    Kreiter, Stefan; Mörz, Tobias; Metzen, Jan F.; Hepp, Daniel A.; Ossig, Benjamin; Otto, Daniel; Socko, Lukasz; Keil, Hanno; Spieß, Volkhard; Hebbeln, Dierk

    2010-05-01

    The promising possibility to reduce CO2 emissions from energy production by the erection of offshore wind farms caused a boom of wind farm projects in the German North Sea. The projected wind turbines have overall heights of up to 200 m above sea level and require considerable foundation depths of up to 50 m pile length in the subsoil. Little experience exists concerning the optimal geotechnical site characterisation for such projects. As approximately 80 considerable sized foundations are needed per wind farm, costs have to be minimized to help making renewable energies competitive. The cost effective and save design of the foundation depends on a reliable knowledge of the upper 50 to 100 m of the subsoil. The marine subsoil of the German North Sea is in general a favourable foundation soil, but Quaternary buried glacial and fluvial valleys introduce heterogeneities, which have to be accurately mapped and considered for the installation planning. Necessary site investigations combine geophysical exploration, core drilling and cone penetration testing. At the same time they have to be in accordance with the national approval procedure which is organised in Germany in several steps. Here, an industry-financed and scientifically-accompanied geotechnical site characterisation of one exemplary offshore wind farm project is presented (partners: RWE-Innogy, ENOVA and MARUM; Initiative "germanwind"). In order to image the lateral highly heterogeneous sedimentation environment in the North Sea a dense net of high resolution multichannel seismic lines was acquired using the University of Bremen shallow water seismic equipment. This provided seismic images of 1.5 m lateral resolution and 2-3 m vertical resolution therefore overcoming the low signal penetration of conventional boomer seimics and the low resolution of conventional multichannel seismics. The seismic survey was complemented with push cores and cone penetration tests at 14 sites, each reaching down to about 50 m

  14. Effects of the construction of Scroby Sands offshore wind farm on the prey base of Little tern Sternula albifrons at its most important UK colony.

    PubMed

    Perrow, Martin R; Gilroy, James J; Skeate, Eleanor R; Tomlinson, Mark L

    2011-08-01

    Despite widespread interest in the impacts of wind farms upon birds, few researchers have examined the potential for indirect or trophic (predator-prey) effects. Using surface trawls, we monitored prey abundance before and after construction of a 30 turbine offshore wind farm sited close to an internationally important colony of Little terns. Observations confirmed that young-of-the-year clupeids dominated chick diet, which trawl samples suggested were mainly herring. Multivariate modelling indicated a significant reduction in herring abundance from 2004 onwards that could not be explained by environmental factors. Intensely noisy monopile installation during the winter spawning period was suggested to be responsible. Reduced prey abundance corresponded with a significant decline in Little tern foraging success. Unprecedented egg abandonment and lack of chick hatching tentatively suggested a colony-scale response in some years. We urge a precautionary approach to the timing and duration of pile-driving activity supported with long-term targeted monitoring of sensitive receptors.

  15. Method for evaluating wind turbine wake effects on wind farm performance

    NASA Technical Reports Server (NTRS)

    Neustadter, H. E.; Spera, D. A.

    1985-01-01

    A method of testing the performance of a cluster of wind turbine units an data analysis equations are presented which together form a simple and direct procedure for determining the reduction in energy output caused by the wake of an upwind turbine. This method appears to solve the problems presented by data scatter and wind variability. Test data from the three-unit Mod-2 wind turbine cluster at Goldendale, Washington, are analyzed to illustrate the application of the proposed method. In this sample case the reduction in energy was found to be about 10 percent when the Mod-2 units were separated a distance equal to seven diameters and winds were below rated.

  16. Assessing environmental impacts of offshore wind farms: lessons learned and recommendations for the future

    PubMed Central

    2014-01-01

    Offshore wind power provides a valuable source of renewable energy that can help reduce carbon emissions. Technological advances are allowing higher capacity turbines to be installed and in deeper water, but there is still much that is unknown about the effects on the environment. Here we describe the lessons learned based on the recent literature and our experience with assessing impacts of offshore wind developments on marine mammals and seabirds, and make recommendations for future monitoring and assessment as interest in offshore wind energy grows around the world. The four key lessons learned that we discuss are: 1) Identifying the area over which biological effects may occur to inform baseline data collection and determining the connectivity between key populations and proposed wind energy sites, 2) The need to put impacts into a population level context to determine whether they are biologically significant, 3) Measuring responses to wind farm construction and operation to determine disturbance effects and avoidance responses, and 4) Learn from other industries to inform risk assessments and the effectiveness of mitigation measures. As the number and size of offshore wind developments increases, there will be a growing need to consider the population level consequences and cumulative impacts of these activities on marine species. Strategically targeted data collection and modeling aimed at answering questions for the consenting process will also allow regulators to make decisions based on the best available information, and achieve a balance between climate change targets and environmental legislation. PMID:25250175

  17. Assessing environmental impacts of offshore wind farms: lessons learned and recommendations for the future.

    PubMed

    Bailey, Helen; Brookes, Kate L; Thompson, Paul M

    2014-01-01

    Offshore wind power provides a valuable source of renewable energy that can help reduce carbon emissions. Technological advances are allowing higher capacity turbines to be installed and in deeper water, but there is still much that is unknown about the effects on the environment. Here we describe the lessons learned based on the recent literature and our experience with assessing impacts of offshore wind developments on marine mammals and seabirds, and make recommendations for future monitoring and assessment as interest in offshore wind energy grows around the world. The four key lessons learned that we discuss are: 1) Identifying the area over which biological effects may occur to inform baseline data collection and determining the connectivity between key populations and proposed wind energy sites, 2) The need to put impacts into a population level context to determine whether they are biologically significant, 3) Measuring responses to wind farm construction and operation to determine disturbance effects and avoidance responses, and 4) Learn from other industries to inform risk assessments and the effectiveness of mitigation measures. As the number and size of offshore wind developments increases, there will be a growing need to consider the population level consequences and cumulative impacts of these activities on marine species. Strategically targeted data collection and modeling aimed at answering questions for the consenting process will also allow regulators to make decisions based on the best available information, and achieve a balance between climate change targets and environmental legislation.

  18. Integrated Layout and Support Structure Optimization for Offshore Wind Farm Design

    NASA Astrophysics Data System (ADS)

    Ashuri, T.; Ponnurangam, C.; Zhang, J.; Rotea, M.

    2016-09-01

    This paper develops a multidisciplinary design optimization framework for integrated design optimization of offshore wind farm layout and support structure. A computational model is developed to characterize the physics of the wind farm wake, aerodynamic and hydrodynamic loads, response of the support structure to these loads, soil- structure interaction, as well as different cost elements. Levelized cost of energy is introduced as the objective function. The design constraints are the farm external boundary, and support structure buckling, first modal-frequency, fatigue damage and ultimate stresses. To evaluate the effectiveness of the proposed approach, four optimization scenarios are considered: a feasible baseline design, optimization of layout only, optimization of support structure only, and integrated design of the layout and support structure. Compared to the baseline design, the optimization results show that the isolated support structure design reduces the levelized cost of energy by 0.6%, the isolated layout design reduces the levelized cost of energy by 2.0%, and the integrated layout and support structure design reduces the levelized cost of energy by 2.6%.

  19. A system-level cost-of-energy wind farm layout optimization with landowner modeling

    SciTech Connect

    Chen, Le; MacDonald, Erin

    2013-10-01

    This work applies an enhanced levelized wind farm cost model, including landowner remittance fees, to determine optimal turbine placements under three landowner participation scenarios and two land-plot shapes. Instead of assuming a continuous piece of land is available for the wind farm construction, as in most layout optimizations, the problem formulation represents landowner participation scenarios as a binary string variable, along with the number of turbines. The cost parameters and model are a combination of models from the National Renewable Energy Laboratory (NREL), Lawrence Berkeley National Laboratory, and Windustiy. The system-level cost-of-energy (COE) optimization model is also tested under two land-plot shapes: equally-sized square land plots and unequal rectangle land plots. The optimal COEs results are compared to actual COE data and found to be realistic. The results show that landowner remittances account for approximately 10% of farm operating costs across all cases. Irregular land-plot shapes are easily handled by the model. We find that larger land plots do not necessarily receive higher remittance fees. The model can help site developers identify the most crucial land plots for project success and the optimal positions of turbines, with realistic estimates of costs and profitability. (C) 2013 Elsevier Ltd. All rights reserved.

  20. Offshore wind farm siting procedures applied offshore of Block Island, Rhode Island

    NASA Astrophysics Data System (ADS)

    O'Reilly, Christopher M.

    Since 2008, the Rhode Island Coastal Resources Management Council (CRMC) has been leading a Rhode Island Ocean Area Management Plan (RIOSAMP) in partnership with the University of Rhode Island, resulting in an extensive multidisciplinary analysis of the Rhode Island offshore environment and its suitability for siting an offshore wind farm. As part of the RIOSAMP project, a standard siting optimization approach was first developed based on a siting index defined as the ratio of costs associated with the wind farm deployment to the available wind resource. This index, combined within a marine spatial planning approach to address ecological and societal constraints, provided an initial macro-siting tool (Spaulding et al., 2010). The multiple GIS layers required in this approach and the absence of theoretical support to optimize the resulting zoning, led to an extension of the initial optimization approach into a more comprehensive macro-siting optimization tool, integrating societal and ecological constraints into the siting tool, the Wind Farm Siting Index (WIFSI) (Grilli et al, 2012). The projects led to the definition of several favorable development areas including a Renewable Energy Zone (REZ) off of Block Island, in State Waters. Deep Water Wind Inc. (DWW) plans to install and commission five 6 MW direct drive Siemens lattice jacket turbines in the REZ area, by 2014. In this thesis two major steps are accomplished to refine and expand the RIOSAMP macro-siting tool. First the macro-siting tool is expanded to include a model simulating the exclusionary zones defined by the Federal Aviation Administration (FAA) regulations. Second a micro-siting model is developed, optimizing the relative position of each turbine within a wind farm area. The micro-siting objective is to minimize, (1) the loss in power due to the loss of wind resource in the wake of the turbines (wake "effect"), and (2) the cable costs that inter-connect the turbines and connecting the farm to the

  1. Large eddy simulation of unsteady wind farm behavior using advanced actuator disk models

    NASA Astrophysics Data System (ADS)

    Moens, Maud; Duponcheel, Matthieu; Winckelmans, Gregoire; Chatelain, Philippe

    2014-11-01

    The present project aims at improving the level of fidelity of unsteady wind farm scale simulations through an effort on the representation and the modeling of the rotors. The chosen tool for the simulations is a Fourth Order Finite Difference code, developed at Universite catholique de Louvain; this solver implements Large Eddy Simulation (LES) approaches. The wind turbines are modeled as advanced actuator disks: these disks are coupled with the Blade Element Momentum method (BEM method) and also take into account the turbine dynamics and controller. A special effort is made here to reproduce the specific wake behaviors. Wake decay and expansion are indeed initially governed by vortex instabilities. This is an information that cannot be obtained from the BEM calculations. We thus aim at achieving this by matching the large scales of the actuator disk flow to high fidelity wake simulations produced using a Vortex Particle-Mesh method. It is obtained by adding a controlled excitation at the disk. We apply this tool to the investigation of atmospheric turbulence effects on the power production and on the wake behavior at a wind farm level. A turbulent velocity field is then used as inflow boundary condition for the simulations. We gratefully acknowledge the support of GDF Suez for the fellowship of Mrs Maud Moens.

  2. Boundary-layer flow and power output in large wind farms during transition from neutral to stable conditions

    NASA Astrophysics Data System (ADS)

    Allaerts, Dries; Meyers, Johan

    2016-11-01

    In wind farms, power deficits are directly related to ambient turbulence levels. Power deficits will therefore increase during the transition from a daytime, conventionally neutral boundary layer (CNBL) to the stable boundary layer (SBL) at night. Besides turbulent decay, a multitude of effects occurs during this transition. For instance, low-level jets may cause strong winds at high elevations, while the velocity near the surface generally decreases. Consequently, Coriolis forces induce a change in wind direction, which alters the apparent wind-farm layout in streamwise direction. In this study, we perform LES of a large onshore wind farm in the late-afternoon transition from an equilibrium CNBL to a surface-cooled SBL. The results of two different cooling rates are compared with the wind-farm performance in the CNBL. The power output decrease during the transition, with faster decrease for stronger surface cooling. However, the initial decrease is dominated by the reduction in wind speed, and the relative power deficits do not increase. Further, considerable wake deflection occurs, and a spatially heterogeneous distribution of temperature and heat flux is observed. The authors acknowledge support from the European Research Council (FP7-Ideas, Grant No. 306471).

  3. The Pattern of Complaints about Australian Wind Farms Does Not Match the Establishment and Distribution of Turbines: Support for the Psychogenic, ‘Communicated Disease’ Hypothesis

    PubMed Central

    Chapman, Simon; St. George, Alexis; Waller, Karen; Cakic, Vince

    2013-01-01

    Background and Objectives With often florid allegations about health problems arising from wind turbine exposure now widespread, nocebo effects potentially confound any future investigation of turbine health impact. Historical audits of health complaints are therefore important. We test 4 hypotheses relevant to psychogenic explanations of the variable timing and distribution of health and noise complaints about wind farms in Australia. Setting All Australian wind farms (51 with 1634 turbines) operating 1993–2012. Methods Records of complaints about noise or health from residents living near 51 Australian wind farms were obtained from all wind farm companies, and corroborated with complaints in submissions to 3 government public enquiries and news media records and court affidavits. These are expressed as proportions of estimated populations residing within 5 km of wind farms. Results There are large historical and geographical variations in wind farm complaints. 33/51 (64.7%) of Australian wind farms including 18/34 (52.9%) with turbine size >1 MW have never been subject to noise or health complaints. These 33 farms have an estimated 21,633 residents within 5 km and have operated complaint-free for a cumulative 267 years. Western Australia and Tasmania have seen no complaints. 129 individuals across Australia (1 in 254 residents) appear to have ever complained, with 94 (73%) being residents near 6 wind farms targeted by anti wind farm groups. The large majority 116/129(90%) of complainants made their first complaint after 2009 when anti wind farm groups began to add health concerns to their wider opposition. In the preceding years, health or noise complaints were rare despite large and small-turbine wind farms having operated for many years. Conclusions The reported historical and geographical variations in complaints are consistent with psychogenic hypotheses that expressed health problems are “communicated diseases” with nocebo effects likely to play an

  4. Experimental testing of axial induction based control strategies for wake control and wind farm optimization

    NASA Astrophysics Data System (ADS)

    Bartl, J.; Sætran, L.

    2016-09-01

    In state-of-the-art wind farms each turbine is controlled individually aiming for optimum turbine power not considering wake effects on downstream turbines. Wind farm control concepts aim for optimizing the overall power output of the farm taking wake interactions between the individual turbines into account. This experimental wind tunnel study investigates axial induction based control concepts. It is examined how the total array efficiency of two in-line model turbines is affected when the upstream turbine's tip speed ratio (λcontrol) or blade pitch angle (β-control) is modified. The focus is particularly directed on how the wake flow behind the upstream rotor is affected when its axial induction is reduced in order to leave more kinetic energy in the wake to be recovered by a downstream turbine. It is shown that the radial distribution of kinetic energy in the wake area can be controlled by modifying the upstream turbine's tip speed ratio. By pitching out the upstream turbine's blades, however, the available kinetic energy in the wake is increased at an equal rate over the entire blade span. Furthermore, the total array efficiency of the two turbine setup is mapped depending on the upstream turbines tip speed ratio and pitch angle. For a small turbine separation distance of x/D=3 the downstream turbine is able to recover the major part of the power lost on the upstream turbine. However, no significant increase in the two-turbine array efficiency is achieved by altering the upstream turbine's operation point away from its optimum.

  5. Proposed Columbia Wind Farm No. 1 : Final Environmental Impact Statement, Joint NEPA/SEPA.

    SciTech Connect

    United States. Bonneville Power Administration; Klickitat County

    1995-09-01

    CARES proposes to construct and operate the 25 megawatt Columbia Wind Farm No. 1 (Project) in the Columbia Hills area of Klickitat County, Washington known as Juniper Point. Wind is not a constant resource and based on the site wind measurement data, it is estimated that the Project would generate approximately 7 average annual MWs of electricity. BPA proposes to purchase the electricity generated by the Project. CARES would execute a contractual agreement with a wind developer, to install approximately 91 wind turbines and associated facilities to generate electricity. The Project`s construction and operation would include: install concrete pier foundations for each wind turbine; install 91 model AWT-26 wind turbines using 43 m high guyed tubular towers on the pier foundations; construct a new 115/24-kv substation; construct a 149 m{sup 2} steel operations and maintenance building; install 25 pad mount transformers along the turbine access roads; install 4.0 km of underground 24 kv power collection lines to collect power from individual turbines to the end of turbine strings; install 1.2 km of underground communication and transmission lines from each turbine to a pad mount transformer; install 5.6 km of 24 kv wood pole transmission lines to deliver electricity from the pad mount transformers to the Project substation; install 3.2 km of 115 kv wood pole transmission lines to deliver electricity from the Project substation to the Public Utility District No. 1 of Klickitat County(PUD)115 kv Goldendale line; interconnect with the BPA transmission system through the Goldendale line and Goldendale substation owned by the PUD; reconstruct, upgrade, and maintain 8.0 km of existing roads; construct and maintain 6.4 km of new graveled roads along the turbine strings and to individual turbines; and install meteorological towers guyed with rebar anchors on the Project site.

  6. A review of noise data collection at the central and south west wind farm in Texas

    SciTech Connect

    Moroz, E.

    1996-12-31

    Evaluation of data collected over a 1-year period from a 6 MW wind farm is presented in the paper. Noise propagation prediction methods are compared with each other and with field data. Three forms of regulating noise are also compared: minimum separation distance, absolute noise limit, and relative noise limit.Relative noise limits were found to offer the most comprehensive approach to regulating noise and to allow each location to be treated independently. A hemispherical spreading model appears to be a useful planning tool. 11 refs., 4 tabs.

  7. Review of Offshore Wind Farm Impact Monitoring and Mitigation with Regard to Marine Mammals.

    PubMed

    Verfuss, Ursula K; Sparling, Carol E; Arnot, Charlie; Judd, Adrian; Coyle, Michael

    2016-01-01

    Monitoring and mitigation reports from 19 UK and 9 other European Union (EU) offshore wind farm (OWF) developments were reviewed, providing a synthesis of the evidence associated with the observed environmental impact on marine mammals. UK licensing conditions were largely concerned with mitigation measures reducing the risk of physical and auditory injury from pile driving. At the other EU sites, impact monitoring was conducted along with mitigation measures. Noise-mitigation measures were developed and tested in UK and German waters in German government-financed projects. We highlight some of the review's findings and lessons learned with regard to noise impact on marine mammals.

  8. Offshore wind farms in the southwestern Baltic Sea: A model study of regional impacts on oxygen conditions

    NASA Astrophysics Data System (ADS)

    Janßen, Holger; Schröder, Toni; Zettler, Michael L.; Pollehne, Falk

    2015-01-01

    Offshore wind farm piles are secondary hard substrate and hence an attractive colonization surface for many species. Especially in marine areas dominated by soft sediments, wind farms may lead to a significant increase in biomass by enlarging habitats from benthos layers into the pelagic column. A concomitant effect is the increase in oxygen consumption through respiration of living biomass and especially through degradation of dead biomass, mainly Mytilus edulis. This leads to impacts on the regional oxygen budget, and local anoxia in the direct vicinity of wind farm piles has been documented in scientific literature. The present study investigates the regional impact of multiple wind farms on oxygen concentration levels and on the appearance of hypoxia. A five-year data sampling with a steel cylinder and fouling plates delivered data for a 3D ecosystem model. The results show that wind farms do not lead to a significant decrease in oxygen on the mesoscale level. But additional anoxia may occur locally, which may lead to the release of hydrogen sulfide on microscale level and potential subsequent regional impacts.

  9. Limitations to the validity of single wake superposition in wind farm yield assessment

    NASA Astrophysics Data System (ADS)

    Gunn, K.; Stock-Williams, C.; Burke, M.; Willden, R.; Vogel, C.; Hunter, W.; Stallard, T.; Robinson, N.; Schmidt, S. R.

    2016-09-01

    Commercially available wind yield assessment models rely on superposition of wakes calculated for isolated single turbines. These methods of wake simulation fail to account for emergent flow physics that may affect the behaviour of multiple turbines and their wakes and therefore wind farm yield predictions. In this paper wake-wake interaction is modelled computationally (CFD) and physically (in a hydraulic flume) to investigate physical causes of discrepancies between analytical modelling and simulations or measurements. Three effects, currently neglected in commercial models, are identified as being of importance: 1) when turbines are directly aligned, the combined wake is shortened relative to the single turbine wake; 2) when wakes are adjacent, each will be lengthened due to reduced mixing; and 3) the pressure field of downstream turbines can move and modify wakes flowing close to them.

  10. Turbulent transport in the atmospheric boundary layer with application to wind farm dynamics

    NASA Astrophysics Data System (ADS)

    Waggy, Scott B.

    With the recent push for renewable energy sources, wind energy has emerged as a candidate to replace some of the power produced by traditional fossil fuels. Recent studies, however, have indicated that wind farms may have a direct effect on local meteorology by transporting water vapor away from the Earth's surface. Such turbulent transport could result in an increased drying of soil, and, in turn, negatively affect the productivity of land in the wind farm's immediate vicinity. This numerical study will analyze four scenarios with the goal of understanding turbulence transport in the wake of a turbine: the neutrally-stratified boundary layer with system rotation, the unstably-stratified atmospheric boundary layer, and wind turbine simulations of these previous two cases. For this work, the Ekman layer is used as an approximation of the atmospheric boundary layer and the governing equations are solved using a fully-parallelized direct numerical simulation (DNS). The in-depth studies of the neutrally and unstably-stratified boundary layers without introducing wind farm effects will act to provide a concrete background for the final study concerning turbulent transport due to turbine wakes. Although neutral stratification rarely occurs in the atmospheric boundary layer, it is useful to study the turbulent Ekman layer under such conditions as it provides a limiting case when unstable or stable stratification are weak. In this work, a thorough analysis was completed including turbulent statistics, velocity and pressure autocorrelations, and a calculation of the full turbulent energy budget. The unstably-stratified atmospheric boundary layer was studied under two levels of heating: moderate and vigorous. Under moderate stratification, both buoyancy and shearing contribute significantly to the turbulent dynamics. As the level of stratification increases, the role of shearing is shown to diminish and is confined to the near-wall region only. A recent, multi

  11. Mean Kinetic Energy Budget of Wakes Within Model Wind Farms: Comparison of an Array of Model Wind Turbines and Porous Discs

    NASA Astrophysics Data System (ADS)

    Camp, E.; Cal, R. B.

    2015-12-01

    To optimize the power production of large wind farms, it is important to understand the flow within the wind turbine array as well as its interaction with the surrounding atmosphere. Computational simulations are often employed to study both the velocity field within and immediately above wind farms. In many computational studies, wind turbines are modeled as stationary, porous actuator discs. A wind tunnel study is done in order to compare the wakes within an array of porous discs and an equivalent array of model wind turbines. To characterize the wakes within a 4×3 model wind farm, stereoscopic particle image velocimetry (SPIV) is employed. SPIV measurements focus on the region along the centerline of the array upstream and downstream of the center turbine in the fourth row. The computed mean flow fields and turbulent stresses provide a basis to compare the near and far wakes of the turbines with those of the porous discs. The detailed analysis of the wakes for each case focus on the mean kinetic energy budget within the wakes. Examining the mean kinetic energy budget is done via computing the mean kinetic energy, flux of kinetic energy, and production of turbulence which are analogous to a measure of extracted power.

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

    PubMed

    Whittlesey, Robert W; Liska, Sebastian; Dabiri, John O

    2010-09-01

    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 neighboring turbines, HAWTs suffer from a reduced power coefficient. 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 neighbors, thus yielding much higher power outputs for a given area of land. A potential flow model of inter-VAWT interactions is developed to investigate the effect of changes in VAWT spatial arrangement on the array performance coefficient, which compares the expected average power coefficient of turbines in an array to a spatially isolated turbine. A geometric arrangement based on the configuration of shed vortices in the wake of schooling fish is shown to significantly increase the array performance coefficient based upon an array of 16 x 16 wind turbines. The results suggest increases in power output of over one order of magnitude for a given area of land as compared to HAWTs.

  13. International perspectives on psychosocial working conditions, mental health, and stress of dairy farm operators.

    PubMed

    Lunner Kolstrup, Christina; Kallioniemi, Marja; Lundqvist, Peter; Kymäläinen, Hanna-Riitta; Stallones, Lorann; Brumby, Susan

    2013-01-01

    Dairy farm operators-farmers, workers, and family members-are faced with many demands and stressors in their daily work and these appear to be shared across countries and cultures. Dairy operators experience high psychosocial demands with respect to a hard work and production ethos, economic influences, and social and environmental responsibility. Furthermore, both traditional and industrial farms are highly dependent on external conditions, such as weather, fluctuating markets, and regulations from government authorities. Possible external stressors include disease outbreaks, taxes related to dairy production, and recent negative societal attitudes to farming in general. Dairy farm operators may have very few or no opportunities to influence and control these external conditions, demands, and expectations. High work demands and expectations coupled with low control and lack of social support can lead to a poor psychosocial work environment, with increased stress levels, ill mental health, depression, and, in the worst cases, suicide. Internationally, farmers with ill mental health have different health service options depending on their location. Regardless of location, it is initially the responsibility of the individual farmer and farm family to handle mental health and stress, which can be of short- or long-term duration. This paper reviews the literature on the topics of psychosocial working conditions, mental health, stress, depression, and suicide among dairy farm operators, farm workers, and farm family members in an international perspective.

  14. Proper orthogonal decomposition of a large eddy simulation during a diurnal cycle for very large wind farms

    NASA Astrophysics Data System (ADS)

    Ali, Naseem; Cortina, Gerard; Hamilton, Nicholas; Calaf, Marc; Cal, Raúl

    2016-11-01

    The structure of the turbulent flow within large wind farms under different atmospheric flow stratification (stable, unstable and neutral) and compares it to the case when there are no turbines present. Spectral analysis is further applied to the corresponding proper orthogonal modes to identify the characteristic wavenumber and be able to relate it to the actual wind farm structure and wake-to-wake interactions. The variation in the number of needed modes between the different cases decreases with increasing value of cumulative energy, which confirms that the major difference between the different study cases resides at the largest turbulent kinetic energy containing scales of each case. The POD modes show the stratification impact of the flow structure and distinguish the flow layers. The spectral analysis displays the domain size and the distance between the rotors as distinctive scales within the wind farm.

  15. Long term estimations of low frequency noise levels over water from an off-shore wind farm.

    PubMed

    Bolin, Karl; Almgren, Martin; Ohlsson, Esbjörn; Karasalo, Ilkka

    2014-03-01

    This article focuses on computations of low frequency sound propagation from an off-shore wind farm. Two different methods for sound propagation calculations are combined with meteorological data for every 3 hours in the year 2010 to examine the varying noise levels at a reception point at 13 km distance. It is shown that sound propagation conditions play a vital role in the noise impact from the off-shore wind farm and ordinary assessment methods can become inaccurate at longer propagation distances over water. Therefore, this paper suggests that methodologies to calculate noise immission with realistic sound speed profiles need to be combined with meteorological data over extended time periods to evaluate the impact of low frequency noise from modern off-shore wind farms.

  16. Ant assemblage (Hymenoptera: Formicidae) in three wind farms in the State of Paraná, Brazil.

    PubMed

    Lutinski, J A; Baucke, L; Filtro, M; Busato, M A; Knakiewicz, A C; Garcia, F R M

    2017-03-01

    The transformation of natural habitats into areas destined to agriculture or projects of energy production has generated a growing concern about the impact on biological diversity. Thus, this study evaluated the diversity of ants in agroecosystems in the area of direct influence of three wind farms in the municipality of Marmeleiro, State of Paraná and examined the association of occurrences with sampling periods. To this end, four samplings were conducted in 2013, one per season. Pitfalls, Malaise trap and Net sweep were used. The assemblages were characterized and compared using richness and number of occurrences of ants. Chao 2 estimates were calculated and a comparison (rarefaction analysis) of the assemblages was performed. The association of the species with the samples was evaluated by a Principal Component Analysis (PCA). Altogether, there were 1,576 occurrences of ants, totaling 55 species. The obtained estimate indicated that richness may be up to 35% higher. Our study adds important information about richness and occurrence of ants in a region poorly analyzed for this group. Most of all, it presents a survey of species occurring in agricultural ecosystems that may serve as a parameter for future evaluations when wind farms are installed.

  17. Effect of nacelle on the wake meandering in Horns Rev wind farm

    NASA Astrophysics Data System (ADS)

    Yang, Xiaolei; Foti, Daniel; Sotiropoulos, Fotis

    2016-11-01

    Turbine wake meandering has considerable effects on the velocity deficit and turbulence intensity in the wake. However, the mechanism for wake meandering is still not well understood and low-order models cannot take into account the wake meandering effects accurately. A recent work by Kang, Yang and Sotiropoulos showed that the nacelle has a significant effect on the wake meandering of a hydrokinetic turbine. To examine the nacelle contributions to wake meandering and wake interactions in utility-scale wind farms, we simulate the atmospheric turbulent flow over the Horns Rev wind farm using large-eddy simulation with actuator type models. In a preliminary simulation on a coarse grid using actuator line model for turbine blades without a nacelle model, the computed power shows overall good agreement with field measurements. Fine grid simulations using an actuator surface model for turbine blades with and without a nacelle model are being carried out. The corresponding results will be presented with analysis on wake meandering dynamics using the technique proposed by Horward et al. and Foti et al.. This work was supported by DOE (DE-AC04-94AL85000), Xcel Energy (Grant RD4-13) and Sandia National Laboratories. Computational resources were provided by National Renewable Energy Laboratory and University of Minnesota Supercomputing Institute.

  18. Individual reactions to a multisensory immersive virtual environment: the impact of a wind farm on individuals.

    PubMed

    Ruotolo, Francesco; Senese, Vincenzo Paolo; Ruggiero, Gennaro; Maffei, Luigi; Masullo, Massimiliano; Iachini, Tina

    2012-08-01

    The aim of this study was to assess the impact of a wind farm on individuals by means of an audio-visual methodology that tried to simulate biologically plausible individual-environment interactions. To disentangle the effects of auditory and visual components on cognitive performances and subjective evaluations, unimodal (Audio or Video) and bimodal (Audio + Video) approaches were compared. Participants were assigned to three experimental conditions that reproduced a wind farm by means of an immersive virtual reality system: bimodal condition, reproducing scenarios with both acoustic and visual stimuli; unimodal visual condition, with only visual stimuli; unimodal auditory condition, with only auditory stimuli. While immersed in the virtual scenarios, participants performed tasks assessing verbal fluency, short-term verbal memory, backward counting, and distance estimations (egocentric: how far is the turbine from you?; allocentric: how far is the turbine from the target?). Afterwards, participants reported their degree of visual and noise annoyance. The results revealed that the presence of a visual scenario as compared to the only availability of auditory stimuli may exert a negative effect on resource-demanding cognitive tasks but a positive effect on perceived noise annoyance. This supports the idea that humans perceive the environment holistically and that auditory and visual features are processed in close interaction.

  19. Power output of offshore wind farms in relation to atmospheric stability

    NASA Astrophysics Data System (ADS)

    Alblas, Laurens; Bierbooms, Wim; Veldkamp, Dick

    2014-12-01

    Atmospheric stability is known to influence wind farm power output, by affecting power losses due to wakes. This research tries to answer what atmospheric stability does to the power production and how conventional simulations using the Jensen wake model compare and can be improved. Data is used from two offshore wind farms, Egmond aan Zee (OWEZ) and North Hoyle. Stability distributions are determined using metmast data. By combining this data with the production data, the influence of stability on the power output is studied. It is found that very unstable conditions result in higher power output (i.e. smaller wake losses) than near-neutral conditions, and these again show higher power output than during very stable conditions. Differences in normalized power output of 10-20% exist between the very unstable and very stable conditions. Simulations can be improved by adapting the wake decay constant (WDC). Observed WDC values are k >= TI, as opposed to the conventional k ≈ 0.5TI. A hypothesis for further research is proposed regarding the influence of vertical turbulence.

  20. Community investment in wind farms: funding structure effects in wind energy infrastructure development.

    PubMed

    Beery, Joshua A; Day, Jennifer E

    2015-03-03

    Wind energy development is an increasingly popular form of renewable energy infrastructure in rural areas. Communities generally perceive socioeconomic benefits accrue and that community funding structures are preferable to corporate structures, yet lack supporting quantitative data to inform energy policy. This study uses the Everpower wind development, to be located in Midwestern Ohio, as a hypothetical modeling environment to identify and examine socioeconomic impact trends arising from corporate, community and diversified funding structures. Analysis of five National Renewable Energy Laboratory Jobs and Economic Development Impact models incorporating local economic data and review of relevant literature were conducted. The findings suggest that community and diversified funding structures exhibit 40-100% higher socioeconomic impact levels than corporate structures. Prioritization of funding sources and retention of federal tax incentives were identified as key elements. The incorporation of local shares was found to mitigate the negative effects of foreign private equity, local debt financing increased economic output and opportunities for private equity investment were identified. The results provide the groundwork for energy policies focused to maximize socioeconomic impacts while creating opportunities for inclusive economic participation and improved social acceptance levels fundamental to the deployment of renewable energy technology.

  1. Impact hypothesis for offshore wind farms: Explanatory models for species distribution at extremely exposed rocky areas

    NASA Astrophysics Data System (ADS)

    Schläppy, Marie-Lise; Šaškov, Aleksej; Dahlgren, Thomas G.

    2014-07-01

    The increasing need for renewable and clean energy production is likely to result in a diversification of locations for the implementation of offshore wind farms which have been so far predominantly sited on soft substrata. In contrast, offshore wind turbines placed on rocky reefs in highly exposed areas are much less common and the impacts on local flora and fauna can only be hypothesized. On the Western coast of Norway, a rocky reef with a highly complex topography has been chosen to be the first full-scale offshore wind farm in the country. Underwater video analyses and multibeam bathymetry data with a generalized linear model were used opportunistically to investigate the influence of geomorphic explanatory variables on the occurrence of selected taxa (algae, sea urchins and sea stars) identified in the study area. Combining video observations and multibeam bathymetry in a generalized linear model revealed that the geomorphic descriptors: aspect, slope, rugosity, and benthic position indexes (BPI), were of significance for algae, sea urchins and sea stars at Havsul and served in showing their habitat preferences. Kelp occurred in areas of high rugosity, on gentle slopes, at elevated areas with a southerly orientation and on the sheltered side of rock or bedrock. Thus, construction disturbance that modify those variables may lead to a change in the area preferred by kelp. Turbines that shade southerly aspects may affect small kelp plants in reducing their available habitat. Sea urchins were more abundant on steep slopes and both sea stars and sea urchins showed a preference for a complex local relief (high rugosity) and heterogeneity in fine and broad elevation (shown by BPI). Thus, foundations and cable route preparation may significantly change the slope, rugosity of BPI broad, which will change the basis for sea urchin populations. It may likewise significantly change the rugosity or BPI (fine or broad), which may change the distribution of sea stars. The

  2. Laboratory modelling of resonant wave-current interaction in the vicinity wind farm masts

    NASA Astrophysics Data System (ADS)

    Gunnoo, Hans; Abcha, Nizar; Garcia-Hermosa, Maria-Isabel; Ezersky, Alexander

    2015-04-01

    In the nearest future, by 2020, about 4% of electricity in Europe will be supplied by sea stations operating from renewable sources: ocean thermal energy, wave and tidal energy, wind farms. By now the wind stations located in the coastal zone, provide the most part of electricity in different European countries. Meanwhile, effects of wind farms on the environment are not sufficiently studied. We report results of laboratory simulations aimed at investigation of hydrodynamic fields arising in the vicinity of wind farm masts under the action of currents and surface waves. The main attention is paid to modeling the resonance effects when the amplitude of velocity pulsations in the vicinity of the masts under the joint action of currents and harmonic waves demonstrate significant growth. This resonance can lead to an increase in Reynolds stress on the bottom, intensification of sediment transport and sound generation. The experiments are performed in the 17 meters hydrodynamical channel of laboratory Morphodynamique Continentale et Côtière UMR CNRS 6143. Mast are modeled by vertical cylinder placed in a steady flow. Behind the cylinder turbulent Karman vortex street occurs. Results are obtained in interval of Reynolds numbers Re=103 - 104(Re=Ud/v, where U is the velocity of the flow, d is diameter of the cylinder, ν is cinematic viscosity). Harmonic surface waves of small amplitude propagating upstream are excited by computer controlled wave maker. In the absence of surface waves, turbulent Karman street with averaged frequency f is observed. It is revealed experimentally that harmonic surface waves with a frequencies closed to 2f can synchronize vortex shedding and increase the amplitude of velocity fluctuations in the wake of the cylinder. Map of regimes is found on the parameter plane amplitude of the surface wave - wave frequency. In order to distinguish the synchronization regimes, we defined phase of oscillations using the Hilbert transform technique. We

  3. An analysis of offshore wind farm SCADA measurements to identify key parameters influencing the magnitude of wake effects

    NASA Astrophysics Data System (ADS)

    Mittelmeier, N.; Blodau, T.; Steinfeld, G.; Rott, A.; Kühn, M.

    2016-09-01

    Atmospheric conditions have a clear influence on wake effects. Stability classification is usually based on wind speed, turbulence intensity, shear and temperature gradients measured partly at met masts, buoys or LiDARs. The objective of this paper is to find a classification for stability based on wind turbine Supervisory Control and Data Acquisition (SCADA) measurements in order to fit engineering wake models better to the current ambient conditions. Two offshore wind farms with met masts have been used to establish a correlation between met mast stability classification and new aggregated statistical signals based on multiple measurement devices. The significance of these new signals on power production is demonstrated for two wind farms with met masts and validated against data from one further wind farm without a met mast. We found a good correlation between the standard deviation of active power divided by the average power of wind turbines in free flow with the ambient turbulence intensity when the wind turbines were operating in partial load.

  4. Environmental impacts of innovative dairy farming systems aiming at improved internal nutrient cycling: A multi-scale assessment.

    PubMed

    de Vries, W; Kros, J; Dolman, M A; Vellinga, Th V; de Boer, H C; Gerritsen, A L; Sonneveld, M P W; Bouma, J

    2015-12-01

    Several dairy farms in the Netherlands aim at reducing environmental impacts by improving the internal nutrient cycle (INC) on their farm by optimizing the use of available on-farm resources. This study evaluates the environmental performance of selected INC farms in the Northern Friesian Woodlands in comparison to regular benchmark farms using a Life Cycle Assessment. Regular farms were selected on the basis of comparability in terms of milk production per farm and per hectare, soil type and drainage conditions. In addition, the environmental impacts of INC farming at landscape level were evaluated with the integrated modelling system INITIATOR, using spatially explicit input data on animal numbers, land use, agricultural management, meteorology and soil, assuming that all farms practised the principle of INC farming. Impact categories used at both farm and landscape levels were global warming potential, acidification potential and eutrophication potential. Additional farm level indicators were land occupation and non-renewable energy use, and furthermore all farm level indicators were also expressed per kg fat and protein corrected milk. Results showed that both on-farm and off-farm non-renewable energy use was significantly lower at INC farms as compared with regular farms. Although nearly all other environmental impacts were numerically lower, both on-farm and off-farm, differences were not statistically significant. Nitrogen losses to air and water decreased by on average 5 to 10% when INC farming would be implemented for the whole region. The impact of INC farming on the global warming potential and eutrophication potential was, however, almost negligible (<2%) at regional level. This was due to a negligible impact on the methane emissions and on the surplus and thereby on the soil accumulation and losses of phosphorus to water at INC farms, illustrating the focus of these farms on closing the nitrogen cycle.

  5. Offshore Wind Farms in the North Sea: Is there an effect on the zooplankton community?

    NASA Astrophysics Data System (ADS)

    Auch, Dominik; Dudeck, Tim; Callies, Ulrich; Riethmüller, Rolf; Hufnagl, Marc; Eckhardt, André; Ove Möller, Klas; Haas, Bianca; Spreitzenbarth, Stefan; van Beusekom, Justus; Walter, Bettina; Temming, Axel; Möllmann, Christian; Floeter, Jens

    2016-04-01

    The climate conference in Paris 2015 has resulted in ambitious goals to mitigate the extent of global climate warming within this century. In Germany, the expansion of renewable energy sources is without any alternative to match the own aims of greenhouse gas reductions. Therefore, in the German EEZ of the North Sea around 10 offshore wind farms (OWFs) are already working and more are currently planned or already under construction. At this already substantial level of offshore wind energy production little is known about the effects of OWFs on the pelagic ecosystem. Earlier investigations have shown an increase of benthic organisms settling on hard substrates provided by the power plant foundations. However, the effects of offshore power plants on lower trophic level organisms within the water column are poorly understood. Thus, we investigated the abundance and distribution of zooplankton within and around OWFs. The analysis was based on optical data derived from a Video Plankton Recorder (VPR). The VPR was mounted on a TRIAXUS system including a suite of different sensors, hence allowing to combine zooplankton information with ambient hydrographic parameters. The combination of the VPR and the TRIAXUS system enabled us to analyse continuous zooplankton and hydrographic data with a high spatial resolution. In this study, we present results of transects through the OWFs Global Tech I, BARD Offshore 1, and Alpha Ventus. The analysis exhibits distinct pattern in the spatial distribution both of physical state variables and of plankton organisms within the vicinity of OWFs, especially of meroplankton, the larval phase of benthic organisms. Keywords: Offshore Wind Farms, Zooplankton, TRIAXUS, Video Plankton Recorder, Meroplankton Corresponding author: Dominik Auch, Institute for Hydrobiology and Fisheries Science, University of Hamburg, Olbersweg 24, 22767 Hamburg, Germany; auch.dominik@web.de

  6. Effects of offshore wind farms on marine wildlife—a generalized impact assessment

    NASA Astrophysics Data System (ADS)

    Bergström, Lena; Kautsky, Lena; Malm, Torleif; Rosenberg, Rutger; Wahlberg, Magnus; Åstrand Capetillo, Nastassja; Wilhelmsson, Dan

    2014-03-01

    Marine management plans over the world express high expectations to the development of offshore wind energy. This would obviously contribute to renewable energy production, but potential conflicts with other usages of the marine landscape, as well as conservation interests, are evident. The present study synthesizes the current state of understanding on the effects of offshore wind farms on marine wildlife, in order to identify general versus local conclusions in published studies. The results were translated into a generalized impact assessment for coastal waters in Sweden, which covers a range of salinity conditions from marine to nearly fresh waters. Hence, the conclusions are potentially applicable to marine planning situations in various aquatic ecosystems. The assessment considered impact with respect to temporal and spatial extent of the pressure, effect within each ecosystem component, and level of certainty. Research on the environmental effects of offshore wind farms has gone through a rapid maturation and learning process, with the bulk of knowledge being developed within the past ten years. The studies showed a high level of consensus with respect to the construction phase, indicating that potential impacts on marine life should be carefully considered in marine spatial planning. Potential impacts during the operational phase were more locally variable, and could be either negative or positive depending on biological conditions as well as prevailing management goals. There was paucity in studies on cumulative impacts and long-term effects on the food web, as well as on combined effects with other human activities, such as the fisheries. These aspects remain key open issues for a sustainable marine spatial planning.

  7. An optimal control framework for dynamic induction control of wind farms and their interaction with the atmospheric boundary layer

    PubMed Central

    Munters, W.

    2017-01-01

    Complex turbine wake interactions play an important role in overall energy extraction in large wind farms. Current control strategies optimize individual turbine power, and lead to significant energy losses in wind farms compared with lone-standing wind turbines. In recent work, an optimal coordinated control framework was introduced (Goit & Meyers 2015 J. Fluid Mech. 768, 5–50 (doi:10.1017/jfm.2015.70)). Here, we further elaborate on this framework, quantify the influence of optimization parameters and introduce new simulation results for which gains in power production of up to 21% are observed. This article is part of the themed issue ‘Wind energy in complex terrains’. PMID:28265024

  8. ANEMOS: Development of a next generation wind power forecasting system for the large-scale integration of onshore and offshore wind farms.

    NASA Astrophysics Data System (ADS)

    Kariniotakis, G.; Anemos Team

    2003-04-01

    Objectives: Accurate forecasting of the wind energy production up to two days ahead is recognized as a major contribution for reliable large-scale wind power integration. Especially, in a liberalized electricity market, prediction tools enhance the position of wind energy compared to other forms of dispatchable generation. ANEMOS, is a new 3.5 years R&D project supported by the European Commission, that resembles research organizations and end-users with an important experience on the domain. The project aims to develop advanced forecasting models that will substantially outperform current methods. Emphasis is given to situations like complex terrain, extreme weather conditions, as well as to offshore prediction for which no specific tools currently exist. The prediction models will be implemented in a software platform and installed for online operation at onshore and offshore wind farms by the end-users participating in the project. Approach: The paper presents the methodology of the project. Initially, the prediction requirements are identified according to the profiles of the end-users. The project develops prediction models based on both a physical and an alternative statistical approach. Research on physical models gives emphasis to techniques for use in complex terrain and the development of prediction tools based on CFD techniques, advanced model output statistics or high-resolution meteorological information. Statistical models (i.e. based on artificial intelligence) are developed for downscaling, power curve representation, upscaling for prediction at regional or national level, etc. A benchmarking process is set-up to evaluate the performance of the developed models and to compare them with existing ones using a number of case studies. The synergy between statistical and physical approaches is examined to identify promising areas for further improvement of forecasting accuracy. Appropriate physical and statistical prediction models are also developed for

  9. Proposed Columbia Wind Farm No. 1 : Draft Environmental Impact Statement, Joint NEPA/SEPA.

    SciTech Connect

    United States. Bonneville Power Administration; Klickitat County

    1995-03-01

    This Draft Environmental Impact Statement (DEIS) addresses the Columbia Wind Farm {number_sign}1 (Project) proposal for construction and operation of a 25 megawatt (MW) wind power project in the Columbia Hills area southeast of Goldendale in Klickitat County, Washington. The Project would be constructed on private land by Conservation and Renewable Energy System (CARES) (the Applicant). An Environmental Impact Statement is required under both NEPA and SEPA guidelines and is issued under Section 102 (2) (C) of the National Environmental Policy Act (NEPA) at 42 U.S.C. 4321 et seq and under the Washington State Environmental Policy Act (SEPA) as provided by RCW 43.21C.030 (2) (c). Bonneville Power Administration is the NEPA lead agency; Klickitat County is the nominal SEPA lead agency and CARES is the SEPA co-lead agency for this DEIS. The Project site is approximately 395 hectares (975 acres) in size. The Proposed Action would include approximately 91 model AWT-26 wind turbines. Under the No Action Alternative, the Project would not be constructed and existing grazing and agricultural activities on the site would continue.

  10. Development of an advanced actuator disk model for Large-Eddy Simulation of wind farms

    NASA Astrophysics Data System (ADS)

    Moens, Maud; Duponcheel, Matthieu; Winckelmans, Gregoire; Chatelain, Philippe

    2015-11-01

    This work aims at improving the fidelity of the wind turbine modelling for Large-Eddy Simulation (LES) of wind farms, in order to accurately predict the loads, the production, and the wake dynamics. In those simulations, the wind turbines are accounted for through actuator disks. i.e. a body-force term acting over the regularised disk swept by the rotor. These forces are computed using the Blade Element theory to estimate the normal and tangential components (based on the local simulated flow and the blade characteristics). The local velocities are modified using the Glauert tip-loss factor in order to account for the finite number of blades; the computation of this correction is here improved thanks to a local estimation of the effective upstream velocity at every point of the disk. These advanced actuator disks are implemented in a 4th order finite difference LES solver and are compared to a classical Blade Element Momentum method and to high fidelity wake simulations performed using a Vortex Particle-Mesh method in uniform and turbulent flows.

  11. Fluid power network for centralized electricity generation in offshore wind farms

    NASA Astrophysics Data System (ADS)

    Jarquin-Laguna, A.

    2014-06-01

    An innovative and completely different wind-energy conversion system is studied where a centralized electricity generation within a wind farm is proposed by means of a hydraulic network. This paper presents the dynamic interaction of two turbines when they are coupled to the same hydraulic network. Due to the stochastic nature of the wind and wake interaction effects between turbines, the operating parameters (i.e. pitch angle, rotor speed) of each turbine are different. Time domain simulations, including the main turbine dynamics and laminar transient flow in pipelines, are used to evaluate the efficiency and rotor speed stability of the hydraulic system. It is shown that a passive control of the rotor speed, as proposed in previous work for a single hydraulic turbine, has strong limitations in terms of performance for more than one turbine coupled to the same hydraulic network. It is concluded that in order to connect several turbines, a passive control strategy of the rotor speed is not sufficient and a hydraulic network with constant pressure is suggested. However, a constant pressure network requires the addition of active control at the hydraulic motors and spear valves, increasing the complexity of the initial concept. Further work needs to be done to incorporate an active control strategy and evaluate the feasibility of the constant pressure hydraulic network.

  12. Adding Complex Terrain and Stable Atmospheric Condition Capability to the Simulator for On/Offshore Wind Farm Applications (SOWFA) (Presentation)

    SciTech Connect

    Churchfield, M. J.

    2013-06-01

    This presentation describes changes made to NREL's OpenFOAM-based wind plant aerodynamics solver so that it can compute the stably stratified atmospheric boundary layer and flow over terrain. Background about the flow solver, the Simulator for Off/Onshore Wind Farm Applications (SOWFA) is given, followed by details of the stable stratification/complex terrain modifications to SOWFA, along with some preliminary results calculations of a stable atmospheric boundary layer and flow over a simple set of hills.

  13. Constraints on Development of Wind Energy in Poland due to Environmental Objectives. Is There Space in Poland for Wind Farm Siting?

    NASA Astrophysics Data System (ADS)

    Hajto, Małgorzata; Cichocki, Zdzisław; Bidłasik, Małgorzata; Borzyszkowski, Jan; Kuśmierz, Agnieszka

    2017-02-01

    The objective of the study was to evaluate spatial effects of adopting environmental criteria for wind farm siting, i.e., the criteria related to the settlement system and those with regards to landscape values. The set of criteria was elaborated on the basis of literature and experience-based knowledge. Some of the criteria selected are legally binding. The analyses were carried out with the use of GIS tools. Settlement areas with 1000 and 2000 m wide buffer zones, and the areas with the highest landscape values, were assumed as particularly sensitive receptors to wind farm impacts. The results show significant constraints on wind farm siting in Poland. Although the constraints are regionally diversified, they concern 93.9 % of the total country area (1000 m buffer zone) or 99.1 % (2000 m buffer zone). Presumably even greater constraints would be revealed by an additional detailed analysis at a local level. The constraints on wind farm siting in Poland cannot be decreased, because of both social attitudes and demand for appropriate environmental standards, which should be taken into account in spatial and energy policies at all decision making level.

  14. Constraints on Development of Wind Energy in Poland due to Environmental Objectives. Is There Space in Poland for Wind Farm Siting?

    PubMed

    Hajto, Małgorzata; Cichocki, Zdzisław; Bidłasik, Małgorzata; Borzyszkowski, Jan; Kuśmierz, Agnieszka

    2017-02-01

    The objective of the study was to evaluate spatial effects of adopting environmental criteria for wind farm siting, i.e., the criteria related to the settlement system and those with regards to landscape values. The set of criteria was elaborated on the basis of literature and experience-based knowledge. Some of the criteria selected are legally binding. The analyses were carried out with the use of GIS tools. Settlement areas with 1000 and 2000 m wide buffer zones, and the areas with the highest landscape values, were assumed as particularly sensitive receptors to wind farm impacts. The results show significant constraints on wind farm siting in Poland. Although the constraints are regionally diversified, they concern 93.9 % of the total country area (1000 m buffer zone) or 99.1 % (2000 m buffer zone). Presumably even greater constraints would be revealed by an additional detailed analysis at a local level. The constraints on wind farm siting in Poland cannot be decreased, because of both social attitudes and demand for appropriate environmental standards, which should be taken into account in spatial and energy policies at all decision making level.

  15. Wind and solar energy curtailment: A review of international experience

    SciTech Connect

    Bird, Lori; Lew, Debra; Milligan, Michael; Carlini, E. Maria; Estanqueiro, Ana; Flynn, Damian; Gomez-Lazaro, Emilio; Holttinen, Hannele; Menemenlis, Nickie; Orths, Antje; Eriksen, Peter Børre; Smith, J. Charles; Soder, Lennart; Sorensen, Poul; Altiparmakis, Argyrios; Yasuda, Yoh; Miller, John

    2016-11-01

    Greater penetrations of variable renewable generation on some electric grids have resulted in increased levels of curtailment in recent years. Studies of renewable energy grid integration have found that curtailment levels may grow as the penetration of wind and solar energy generation increases. This paper reviews international experience with curtailment of wind and solar energy on bulk power systems in recent years, with a focus on eleven countries in Europe, North America, and Asia. It examines levels of curtailment, the causes of curtailment, curtailment methods and use of market-based dispatch, as well as operational, institutional, and other changes that are being made to reduce renewable energy curtailment.

  16. A cultural resources study of the proposed CARES Columbia Wind Farm No. 1, Klickatat County, Washington. Appendix C

    NASA Astrophysics Data System (ADS)

    Galm, J. R.; Boreson, K.; Crisson, F.; Holstine, C.

    1995-02-01

    The purpose of this study is to conduct a cultural resources inventory to provide information for the environmental impact statement being jointly prepared by BPA and Klickatat County, Washington, on the Columbia Wind Farm No. 1 project. The investigation resulted in the identification of 75 isolated finds (mostly debitage) and nine recorded sites, in addition to two prehistoric sites previously recorded.

  17. Sandia Wake Imaging System Field Test Report: 2015 Deployment at the Scaled Wind Farm Technology (SWiFT) Facility.

    SciTech Connect

    Naughton, Brian Thomas; Herges, Thomas

    2015-10-01

    This report presents the objectives, configuration, procedures, reporting , roles , and responsibilities and subsequent results for the field demonstration of the Sandia Wake Imaging System (SWIS) at the Sandia Scaled Wind Farm Technology (SWiFT) facility near Lubbock, Texas in June and July 2015.

  18. Investigating the influences of two position (non-staggered and staggered) of wind turbine arrays to produce power in a wind farm

    NASA Astrophysics Data System (ADS)

    Ismail, Kamal, Samsul; Purnomo, Sarjiya

    2016-06-01

    This investigation was conducted to identify the influences of the two positions (non-staggered and staggered) of wind turbine arrays. Identification on down-scaled size wind turbine arrays was carried out in an open circuit, suction-type wind tunnel. Based on the results of the experiment, empirical relations for the centreline velocity deficit, tipline velocity deficit and wake radius are proposed. The non-staggered position results are larger power generated than that of the staggered position, this influenced by the trend deficit in velocity that makes wind turbine generated power difference between staggered position and non-stagger position. The area used non-staggered position larger than staggered position. Result staggered position has become one of the solutions to harness wind farms confined areas.

  19. Statistical and clustering analysis for disturbances: A case study of voltage dips in wind farms

    DOE PAGES

    Garcia-Sanchez, Tania; Gomez-Lazaro, Emilio; Muljadi, Eduard; ...

    2016-01-28

    This study proposes and evaluates an alternative statistical methodology to analyze a large number of voltage dips. For a given voltage dip, a set of lengths is first identified to characterize the root mean square (rms) voltage evolution along the disturbance, deduced from partial linearized time intervals and trajectories. Principal component analysis and K-means clustering processes are then applied to identify rms-voltage patterns and propose a reduced number of representative rms-voltage profiles from the linearized trajectories. This reduced group of averaged rms-voltage profiles enables the representation of a large amount of disturbances, which offers a visual and graphical representation ofmore » their evolution along the events, aspects that were not previously considered in other contributions. The complete process is evaluated on real voltage dips collected in intense field-measurement campaigns carried out in a wind farm in Spain among different years. The results are included in this paper.« less

  20. Computational modelling of a large dimension wind farm cluster using domain coupling

    NASA Astrophysics Data System (ADS)

    da Costa Gomes, V. M. M. G.; Palma, J. M. L. M.

    2016-09-01

    The accuracy of Computational Fluid Dynamics (CFD) models for Atmospheric Boundary Layer (ABL) flows relies largely on the placement of the domain boundaries and the quality of the imposed flow conditions, the inlet boundary in particular. Exploiting the parabolic nature of many ABL flows and of CFD modelled ABL flow in particular, a precursor simulation is used as source of flow data to improve the target domain's inlet flow description over the standard synthetic boundary conditions, one-directionally coupling the solutions to the two simulations. Using the approach, a case of flow over a two wind farm offshore cluster is modelled using two small coupled simulations, matching the results of a single simulation including the full cluster at a significant computational time saving, in the order of 70%. Further savings were shown to be possible by reducing the resolution of the precursor simulation, with negligible impact on the results at the target domain.

  1. Statistical and clustering analysis for disturbances: A case study of voltage dips in wind farms

    SciTech Connect

    Garcia-Sanchez, Tania; Kessler, Mathieu; Molina-Garcia, Angel

    2016-01-28

    This study proposes and evaluates an alternative statistical methodology to analyze a large number of voltage dips. For a given voltage dip, a set of lengths is first identified to characterize the root mean square (rms) voltage evolution along the disturbance, deduced from partial linearized time intervals and trajectories. Principal component analysis and K-means clustering processes are then applied to identify rms-voltage patterns and propose a reduced number of representative rms-voltage profiles from the linearized trajectories. This reduced group of averaged rms-voltage profiles enables the representation of a large amount of disturbances, which offers a visual and graphical representation of their evolution along the events, aspects that were not previously considered in other contributions. The complete process is evaluated on real voltage dips collected in intense field-measurement campaigns carried out in a wind farm in Spain among different years. The results are included in this paper.

  2. Wind Farm Facilities in Germany Kill Noctule Bats from Near and Far

    PubMed Central

    Lehnert, Linn S.; Kramer-Schadt, Stephanie; Schönborn, Sophia; Lindecke, Oliver; Niermann, Ivo; Voigt, Christian C.

    2014-01-01

    Over recent years, it became widely accepted that alternative, renewable energy may come at some risk for wildlife, for example, when wind turbines cause large numbers of bat fatalities. To better assess likely populations effects of wind turbine related wildlife fatalities, we studied the geographical origin of the most common bat species found dead below German wind turbines, the noctule bat (Nyctalus noctula). We measured stable isotope ratios of non-exchangeable hydrogen in fur keratin to separate migrants from local individuals, used a linear mixed-effects model to identify temporal, spatial and biological factors explaining the variance in measured stable isotope ratios and determined the geographical breeding provenance of killed migrants using isoscape origin models. We found that 72% of noctule bat casualties (n = 136) were of local origin, while 28% were long-distance migrants. These findings highlight that bat fatalities at German wind turbines may affect both local and distant populations. Our results indicated a sex and age-specific vulnerability of bats towards lethal accidents at turbines, i.e. a relatively high proportion of killed females were recorded among migratory individuals, whereas more juveniles than adults were recorded among killed bats of local origin. Migratory noctule bats were found to originate from distant populations in the Northeastern parts of Europe. The large catchment areas of German wind turbines and high vulnerability of female and juvenile noctule bats call for immediate action to reduce the negative cross-boundary effects of bat fatalities at wind turbines on local and distant populations. Further, our study highlights the importance of implementing effective mitigation measures and developing species and scale-specific conservation approaches on both national and international levels to protect source populations of bats. The efficacy of local compensatory measures appears doubtful, at least for migrant noctule bats

  3. Wind farm facilities in Germany kill noctule bats from near and far.

    PubMed

    Lehnert, Linn S; Kramer-Schadt, Stephanie; Schönborn, Sophia; Lindecke, Oliver; Niermann, Ivo; Voigt, Christian C

    2014-01-01

    Over recent years, it became widely accepted that alternative, renewable energy may come at some risk for wildlife, for example, when wind turbines cause large numbers of bat fatalities. To better assess likely populations effects of wind turbine related wildlife fatalities, we studied the geographical origin of the most common bat species found dead below German wind turbines, the noctule bat (Nyctalus noctula). We measured stable isotope ratios of non-exchangeable hydrogen in fur keratin to separate migrants from local individuals, used a linear mixed-effects model to identify temporal, spatial and biological factors explaining the variance in measured stable isotope ratios and determined the geographical breeding provenance of killed migrants using isoscape origin models. We found that 72% of noctule bat casualties (n = 136) were of local origin, while 28% were long-distance migrants. These findings highlight that bat fatalities at German wind turbines may affect both local and distant populations. Our results indicated a sex and age-specific vulnerability of bats towards lethal accidents at turbines, i.e. a relatively high proportion of killed females were recorded among migratory individuals, whereas more juveniles than adults were recorded among killed bats of local origin. Migratory noctule bats were found to originate from distant populations in the Northeastern parts of Europe. The large catchment areas of German wind turbines and high vulnerability of female and juvenile noctule bats call for immediate action to reduce the negative cross-boundary effects of bat fatalities at wind turbines on local and distant populations. Further, our study highlights the importance of implementing effective mitigation measures and developing species and scale-specific conservation approaches on both national and international levels to protect source populations of bats. The efficacy of local compensatory measures appears doubtful, at least for migrant noctule bats

  4. Large-Eddy Simulation of Atmospheric Boundary-Layer Flow Through a Wind Farm Sited on Topography

    NASA Astrophysics Data System (ADS)

    Shamsoddin, Sina; Porté-Agel, Fernando

    2017-04-01

    Large-eddy simulation (LES) has recently been well validated and applied in the context of wind turbines over flat terrain; however, to date its accuracy has not been tested systematically in the case of turbine-wake flows over topography. Here, we investigate the wake flow in a wind farm situated on hilly terrain using LES for a case where wind-tunnel experimental data are available. To this end, first boundary-layer flow is simulated over a two-dimensional hill in order to characterize the spatial distribution of the mean velocity and the turbulence statistics. A flow simulation is then performed through a wind farm consisting of five horizontal-axis wind turbines sited over the same hill in an aligned layout. The resulting flow characteristics are compared with the former case, i.e., without wind turbines. To assess the validity of the simulations, the results are compared with the wind-tunnel measurements. It is found that LES can reproduce the flow field effectively, and, specifically, the speed-up over the hilltop and the velocity deficit and turbulence intensity enhancement induced by the turbines are well captured by the simulations. Besides, the vertical profiles of the mean velocity and turbulence intensity at different streamwise positions match well those for the experiment. In addition, another numerical experiment is carried out to show how higher (and more realistic) thrust coefficients of the turbines lead to stronger wakes and, at the same time, higher turbulence intensities.

  5. Large-Eddy Simulation of Atmospheric Boundary-Layer Flow Through a Wind Farm Sited on Topography

    NASA Astrophysics Data System (ADS)

    Shamsoddin, Sina; Porté-Agel, Fernando

    2016-11-01

    Large-eddy simulation (LES) has recently been well validated and applied in the context of wind turbines over flat terrain; however, to date its accuracy has not been tested systematically in the case of turbine-wake flows over topography. Here, we investigate the wake flow in a wind farm situated on hilly terrain using LES for a case where wind-tunnel experimental data are available. To this end, first boundary-layer flow is simulated over a two-dimensional hill in order to characterize the spatial distribution of the mean velocity and the turbulence statistics. A flow simulation is then performed through a wind farm consisting of five horizontal-axis wind turbines sited over the same hill in an aligned layout. The resulting flow characteristics are compared with the former case, i.e., without wind turbines. To assess the validity of the simulations, the results are compared with the wind-tunnel measurements. It is found that LES can reproduce the flow field effectively, and, specifically, the speed-up over the hilltop and the velocity deficit and turbulence intensity enhancement induced by the turbines are well captured by the simulations. Besides, the vertical profiles of the mean velocity and turbulence intensity at different streamwise positions match well those for the experiment. In addition, another numerical experiment is carried out to show how higher (and more realistic) thrust coefficients of the turbines lead to stronger wakes and, at the same time, higher turbulence intensities.

  6. Application of Static Var Compensator (SVC) With PI Controller for Grid Integration of Wind Farm Using Harmony Search

    NASA Astrophysics Data System (ADS)

    Keshta, H. E.; Ali, A. A.; Saied, E. M.; Bendary, F. M.

    2016-10-01

    Large-scale integration of wind turbine generators (WTGs) may have significant impacts on power system operation with respect to system frequency and bus voltages. This paper studies the effect of Static Var Compensator (SVC) connected to wind energy conversion system (WECS) on voltage profile and the power generated from the induction generator (IG) in wind farm. Also paper presents, a dynamic reactive power compensation using Static Var Compensator (SVC) at the a point of interconnection of wind farm while static compensation (Fixed Capacitor Bank) is unable to prevent voltage collapse. Moreover, this paper shows that using advanced optimization techniques based on artificial intelligence (AI) such as Harmony Search Algorithm (HS) and Self-Adaptive Global Harmony Search Algorithm (SGHS) instead of a Conventional Control Method to tune the parameters of PI controller for SVC and pitch angle. Also paper illustrates that the performance of the system with controllers based on AI is improved under different operating conditions. MATLAB/Simulink based simulation is utilized to demonstrate the application of SVC in wind farm integration. It is also carried out to investigate the enhancement in performance of the WECS achieved with a PI Controller tuned by Harmony Search Algorithm as compared to a Conventional Control Method.

  7. An ideal limit for the performance of a large, fully-developed wind farm

    NASA Astrophysics Data System (ADS)

    Luzzatto-Fegiz, P.; Caulfield, C. P.

    2014-11-01

    Wind turbines are often deployed in arrays of hundreds of units, where interactions lead to drastic losses in power output. Remarkably, while the theoretical ``Betz'' maximum has long been established for the output of a single turbine, no corresponding theory appears to exist for a generic, large-scale energy extraction system, although models exist for specific turbine designs and layouts. Recent work with vertical-axis turbines indicates that large performance gains may be achievable (Dabiri 2011), making the search for a theoretical upper bound even more compelling. We develop a model for an array of energy-extraction devices of arbitrary design and layout, first focusing on the fully-developed regime. When tailoring the model to reflect current designs, the predicted power output is in good agreement with field measurements. Furthermore, by considering a suitable ideal limit, we establish an upper bound on the performance of a large wind farm. This is found to be several times larger than the output of existing arrays, thus supporting the notion that performance improvements may be possible. Finally, we extend our model to include spatially developing flows, as well as to account for the effect of atmospheric stability, finding good agreement with laboratory and field data.

  8. Integration of offshore wind farms through high voltage direct current networks

    NASA Astrophysics Data System (ADS)

    Livermore, Luke

    The integration of offshore wind farms through Multi Terminal DC (MTDC) networks into the GB network was investigated. The ability of Voltage Source Converter (VSC) High Voltage Direct Current (HVDC) to damp Subsynchronous Resonance (SSR) and ride through onshore AC faults was studied. Due to increased levels of wind generation in Scotland, substantial onshore and offshore reinforcements to the GB transmission network are proposed. Possible inland reinforcements include the use of series compensation through fixed capacitors. This potentially can lead to SSR. Offshore reinforcements are proposed by two HVDC links. In addition to its primary functions of bulk power transmission, a HVDC link can be used to provide damping against SSR, and this function has been modelled. Simulation studies have been carried out in PSCAD. In addition, a real-time hardware-in-the-loop HVDC test rig has been used to implement and validate the proposed damping scheme on an experimental platform. When faults occur within AC onshore networks, offshore MTDC networks are vulnerable to DC overvoltages, potentially damaging the DC plant and cables. Power reduction and power dissipation control systems were investigated to ride through onshore AC faults. These methods do not require dedicated fast communication systems. Simulations and laboratory experiments are carried out to evaluate the control systems, with the results from the two platforms compared..

  9. Unstructured grid modelling of offshore wind farm impacts on seasonally stratified shelf seas

    NASA Astrophysics Data System (ADS)

    Cazenave, Pierre William; Torres, Ricardo; Allen, J. Icarus

    2016-06-01

    Shelf seas comprise approximately 7% of the world's oceans and host enormous economic activity. Development of energy installations (e.g. Offshore Wind Farms (OWFs), tidal turbines) in response to increased demand for renewable energy requires a careful analysis of potential impacts. Recent remote sensing observations have identified kilometre-scale impacts from OWFs. Existing modelling evaluating monopile impacts has fallen into two camps: small-scale models with individually resolved turbines looking at local effects; and large-scale analyses but with sub-grid scale turbine parameterisations. This work straddles both scales through a 3D unstructured grid model (FVCOM): wind turbine monopiles in the eastern Irish Sea are explicitly described in the grid whilst the overall grid domain covers the south-western UK shelf. Localised regions of decreased velocity extend up to 250 times the monopile diameter away from the monopile. Shelf-wide, the amplitude of the M2 tidal constituent increases by up to 7%. The turbines enhance localised vertical mixing which decreases seasonal stratification. The spatial extent of this extends well beyond the turbines into the surrounding seas. With significant expansion of OWFs on continental shelves, this work highlights the importance of how OWFs may impact coastal (e.g. increased flooding risk) and offshore (e.g. stratification and nutrient cycling) areas.

  10. Wind Farm Flow Modeling using an Input-Output Reduced-Order Model

    SciTech Connect

    Annoni, Jennifer; Gebraad, Pieter; Seiler, Peter

    2016-08-01

    Wind turbines in a wind farm operate individually to maximize their own power regardless of the impact of aerodynamic interactions on neighboring turbines. There is the potential to increase power and reduce overall structural loads by properly coordinating turbines. To perform control design and analysis, a model needs to be of low computational cost, but retains the necessary dynamics seen in high-fidelity models. The objective of this work is to obtain a reduced-order model that represents the full-order flow computed using a high-fidelity model. A variety of methods, including proper orthogonal decomposition and dynamic mode decomposition, can be used to extract the dominant flow structures and obtain a reduced-order model. In this paper, we combine proper orthogonal decomposition with a system identification technique to produce an input-output reduced-order model. This technique is used to construct a reduced-order model of the flow within a two-turbine array computed using a large-eddy simulation.

  11. Value of information of repair times for offshore wind farm maintenance planning

    NASA Astrophysics Data System (ADS)

    Seyr, Helene; Muskulus, Michael

    2016-09-01

    A large contribution to the total cost of energy in offshore wind farms is due to maintenance costs. In recent years research has focused therefore on lowering the maintenance costs using different approaches. Decision support models for scheduling the maintenance exist already, dealing with different factors influencing the scheduling. Our contribution deals with the uncertainty in the repair times. Given the mean repair times for different turbine components we make some assumptions regarding the underlying repair time distribution. We compare the results of a decision support model for the mean times to repair and those repair time distributions. Additionally, distributions with the same mean but different variances are compared under the same conditions. The value of lowering the uncertainty in the repair time is calculated and we find that using distributions significantly decreases the availability, when scheduling maintenance for multiple turbines in a wind park. Having detailed information about the repair time distribution may influence the results of maintenance modeling and might help identify cost factors.

  12. A balanced solution to the cumulative threat of industrialized wind farm development on cinereous vultures (Aegypius monachus) in south-eastern Europe.

    PubMed

    Vasilakis, Dimitris P; Whitfield, D Philip; Kati, Vassiliki

    2017-01-01

    Wind farm development can combat climate change but may also threaten bird populations' persistence through collision with wind turbine blades if such development is improperly planned strategically and cumulatively. Such improper planning may often occur. Numerous wind farms are planned in a region hosting the only cinereous vulture population in south-eastern Europe. We combined range use modelling and a Collision Risk Model (CRM) to predict the cumulative collision mortality for cinereous vulture under all operating and proposed wind farms. Four different vulture avoidance rates were considered in the CRM. Cumulative collision mortality was expected to be eight to ten times greater in the future (proposed and operating wind farms) than currently (operating wind farms), equivalent to 44% of the current population (103 individuals) if all proposals are authorized (2744 MW). Even under the most optimistic scenario whereby authorized proposals will not collectively exceed the national target for wind harnessing in the study area (960 MW), cumulative collision mortality would still be high (17% of current population) and likely lead to population extinction. Under any wind farm proposal scenario, over 92% of expected deaths would occur in the core area of the population, further implying inadequate spatial planning and implementation of relevant European legislation with scant regard for governmental obligations to protect key species. On the basis of a sensitivity map we derive a spatially explicit solution that could meet the national target of wind harnessing with a minimum conservation cost of less than 1% population loss providing that the population mortality (5.2%) caused by the operating wind farms in the core area would be totally mitigated. Under other scenarios, the vulture population would probably be at serious risk of extinction. Our 'win-win' approach is appropriate to other potential conflicts where wind farms may cumulatively threaten wildlife

  13. A balanced solution to the cumulative threat of industrialized wind farm development on cinereous vultures (Aegypius monachus) in south-eastern Europe

    PubMed Central

    Whitfield, D. Philip; Kati, Vassiliki

    2017-01-01

    Wind farm development can combat climate change but may also threaten bird populations’ persistence through collision with wind turbine blades if such development is improperly planned strategically and cumulatively. Such improper planning may often occur. Numerous wind farms are planned in a region hosting the only cinereous vulture population in south-eastern Europe. We combined range use modelling and a Collision Risk Model (CRM) to predict the cumulative collision mortality for cinereous vulture under all operating and proposed wind farms. Four different vulture avoidance rates were considered in the CRM. Cumulative collision mortality was expected to be eight to ten times greater in the future (proposed and operating wind farms) than currently (operating wind farms), equivalent to 44% of the current population (103 individuals) if all proposals are authorized (2744 MW). Even under the most optimistic scenario whereby authorized proposals will not collectively exceed the national target for wind harnessing in the study area (960 MW), cumulative collision mortality would still be high (17% of current population) and likely lead to population extinction. Under any wind farm proposal scenario, over 92% of expected deaths would occur in the core area of the population, further implying inadequate spatial planning and implementation of relevant European legislation with scant regard for governmental obligations to protect key species. On the basis of a sensitivity map we derive a spatially explicit solution that could meet the national target of wind harnessing with a minimum conservation cost of less than 1% population loss providing that the population mortality (5.2%) caused by the operating wind farms in the core area would be totally mitigated. Under other scenarios, the vulture population would probably be at serious risk of extinction. Our ‘win-win’ approach is appropriate to other potential conflicts where wind farms may cumulatively threaten wildlife

  14. Analysis of Debris Trajectories at the Scaled Wind Farm Technology (SWiFT) Facility

    SciTech Connect

    White, Jonathan R.; Burnett, Damon J.

    2016-01-01

    Sandia National Laboratories operates the Scaled Wind Farm Technology Facility (SWiFT) on behalf of the Department of Energy Wind and Water Power Technologies Office. An analysis was performed to evaluate the hazards associated with debris thrown from one of SWiFT’s operating wind turbines, assuming a catastrophic failure. A Monte Carlo analysis was conducted to assess the complex variable space associated with debris throw hazards that included wind speed, wind direction, azimuth and pitch angles of the blade, and percentage of the blade that was separated. In addition, a set of high fidelity explicit dynamic finite element simulations were performed to determine the threshold impact energy envelope for the turbine control building located on-site. Assuming that all of the layered, independent, passive and active engineered safety systems and administrative procedures failed (a 100% failure rate of the safety systems), the likelihood of the control building being struck was calculated to be less than 5/10,000 and ballistic simulations showed that the control building would not provide passive protection for the majority of impact scenarios. Although options exist to improve the ballistic resistance of the control building, the recommendation is not to pursue them because there is a low probability of strike and there is an equal likelihood personnel could be located at similar distances in other areas of the SWiFT facility which are not passively protected, while the turbines are operating. A fenced exclusion area has been created around the turbines which restricts access to the boundary of the 1/100 strike probability. The overall recommendation is to neither relocate nor improve passive protection of the control building as the turbine safety systems have been improved to have no less than two independent, redundant, high quality engineered safety systems. Considering this, in combination with a control building strike probability of less than 5/10,000, the

  15. Vegetation, soil property and climatic controls over greenhouse gas fluxes in a blanket peatland hosting a wind farm

    NASA Astrophysics Data System (ADS)

    Armstrong, Alona; Waldron, Susan; Ostle, Nick; Whitaker, Jeanette

    2013-04-01

    Peatlands are important carbon (C) stores, with boreal and subarctic peatlands containing 15-30 % of the world soil carbon stock (Limpens et al., 2008). Research has demonstrated that greenhouse gas (GHG) fluxes in peatlands are influenced by vegetation, soil property and climatic variables, including plant functional type (PFT), water table height and temperature. In this paper we present data from Black Law Wind Farm, Scotland, where we examined the effect of a predicted wind turbine-induced microclimatic gradient and PFT on carbon dioxide (CO2) and methane (CH4) fluxes. Moreover, we determined the role of vegetation, soil property and climatic variables as predictors of the variation in CO2 and CH4 emissions. We measured CO2 and CH4 at 48 plots within Black Law Wind Farm at monthly intervals from May 2011 to April 2012. Four sampling sites were located along a predicted wind turbine-induced microclimatic gradient. At each site four blocks were established, each with plots in areas dominated by mosses, sedges and shrubs. Plant biomass and PFT (vegetation factors); soil moisture, water table height, peat depth, C content, nitrogen (N) content and C:N (soil properties); and soil temperature and photosynthetically active radiation (PAR) (climatic variables) were measured. Analysis of variance (ANOVA) models based on the microclimatic gradient site, PFT and season when measurements were made explained 58 %, 44 % and 49 % of the variation in ecosystem respiration, photosynthesis and CH4, respectively. Site, PFT, season and their interactions were all significant for respiration and photosynthesis (with the exception of the PFT*site interaction) but for CH4 only the main effects were significant. Parsimonious ANOVA models using the biotic, soil property and climatic explanatory data explained 62 %, 55 % and 49 % of the variation in respiration, photosynthesis and CH4, respectively. Published studies (Baidya Roy and Traiteur 2010; Zhou et al., 2012) and preliminary

  16. Characterisation of impacts on the environment of an idealised offshore wind farm foundation, under waves and the combination of waves and currents

    NASA Astrophysics Data System (ADS)

    García-Hermosa, Isabel; Abcha, Nizar; Brossard, Jérôme; Bennis, Anne-Claire; Ezersky, Alexander; Gross, Marcus; Iglesias, Gregorio; Magar, Vanesa; Miles, Jon; Mouazé, Dominique; Perret, Gaële; Pinon, Grégory; Rivier, Aurélie; Rogan, Charlie; Simmonds, David

    2015-04-01

    system photographing the bed (Marin & Ezersky, 2007, and Jarno-Druaux et al., 2004). Velocity fields, and flow structures around the cylinder at low KC numbers (KC~1) were characterised and parameters such as vorticity, turbulent kinetic energy and bed shear stresses derived where possible. During the experiments vortex structures with a horizontal axis were observed in the vicinity of the cylinder and the bed even at low KC. The Keulegan-Carpenter number (KC) is defined as: KC = UmT- D, where Um is the bottom orbital velocity, T the peak period and D the pile diameter. As part of the project, the findings from the experiments fed into a regional numerical modelling (Rivier et al., 2014) to improve parametrisation of the representation of the within-cell processes (local to the mast). References García-Hermosa, M. I., Brossard, J., Cohen, Z., Perret, G. (2014). Experimental characterisation of wave induced flow fields due to an offshore wind farm mast. First International Conference on Renewable Energies Offshore (RENEW) Lisbon, Portugal. November 2014. Gunnoo, H., Abcha, N., Mouazé, D., Ezersky, A., García-Hermosa, M. I. (2014). Laboratory simulation of resonance amplification of the hydrodynamic fields in the vicinity of wind farm masts. Proceedings of the First International Conference on Renewable Energies Offshore (RENEW) Lisbon, Portugal. November 2014. Jarno-Druaux, A., Brossard, J., Marin, F. (2004). Dynamical evolution of ripples in a wave channel, European Journal of Mechanics B/Fluids 23: 695-708. Marin, F. and Ezersky, A. B. (2007). Formation dynamics of sand bedforms under solitons and bound states of solitons in a wave flume used in resonant mode. European Journal of Mechanics - B/Fluids, Elsevier, 2008, 27 (3), pp.251-267. Rivier, A., Bennis, A.-C., Pinon, G., Gross, M., Magar, V. (2014). Regional numerical modelling of offshore monopile wind turbine impacts on hydrodynamics and sediment transport. Proceeding of the 1st International Conference on

  17. Climate change impacts on the power generation potential of a European mid-century wind farms scenario

    NASA Astrophysics Data System (ADS)

    Tobin, Isabelle; Jerez, Sonia; Vautard, Robert; Thais, Françoise; van Meijgaard, Erik; Prein, Andreas; Déqué, Michel; Kotlarski, Sven; Fox Maule, Cathrine; Nikulin, Grigory; Noël, Thomas; Teichmann, Claas

    2016-03-01

    Wind energy resource is subject to changes in climate. To investigate the impacts of climate change on future European wind power generation potential, we analyze a multi-model ensemble of the most recent EURO-CORDEX regional climate simulations at the 12 km grid resolution. We developed a mid-century wind power plant scenario to focus the impact assessment on relevant locations for future wind power industry. We found that, under two greenhouse gas concentration scenarios, changes in the annual energy yield of the future European wind farms fleet as a whole will remain within ±5% across the 21st century. At country to local scales, wind farm yields will undergo changes up to 15% in magnitude, according to the large majority of models, but smaller than 5% in magnitude for most regions and models. The southern fleets such as the Iberian and Italian fleets are likely to be the most affected. With regard to variability, changes are essentially small or poorly significant from subdaily to interannual time scales.

  18. Large-eddy simulation of the diurnal variation of wake flows in a finite-size wind farm

    NASA Astrophysics Data System (ADS)

    Abkar, Mahdi; Sharifi, Ahmad; Porté-Agel, Fernando

    2015-06-01

    In this study, large-eddy simulation (LES) is used to study the evolution of the wind-turbine wakes and their effects on power losses inside an idealized finite-size wind farm in the course of a full diurnal cycle. In the LES, turbulent subgrid-scale stresses are modeled using tuning-free Lagrangian scale-dependent dynamic models, while the turbine-induced forces are parameterized using a dynamic actuator disk model with rotation. The simulation results show a strong effect of atmospheric stability on the wind farm wakes and associated power losses. During the night, the relatively low turbulence intensity of the ambient ABL flow results in a relatively slow rate of entrainment of momentum into the wake and, consequently, a slow wake recovery. In contrast, during the day the positive buoyancy flux and associated turbulence production lead to a relatively high turbulence level in the background ABL flow, which enhances turbulent mixing and wake recovery. As a result, the averaged power deficit in the wind farm is found to increase with increasing thermal stability. In particular for that day, the averaged power deficit increased from 28% under the most convective condition to about 57% under the most stable condition.

  19. Case study of preliminary cyclic load evaluation and triaxial soil testing in offshore wind farm planning

    NASA Astrophysics Data System (ADS)

    Otto, Daniel; Ossig, Benjamin; Kreiter, Stefan; Kouery, Saed; Moerz, Tobias

    2010-05-01

    In 2020 Germany aims to produce 20% of its electrical power trough renewable energy sources. Assigned Offshore Wind farms in the German exclusive economic zone of the North- and the Baltic Sea are important step toward a fulfilment of this goal. However the save erecting of 5-6 MW wind power plants (total construction size: > 200m) in water depth of around 40 m is related to unprecedented technical, logistical and financial challenges. With an intended lifetime expectation of 50 years for the foundations, construction materials and the soils around the foundation are subject to high and continued stresses from self-weight, waves, wind and current. These stresses are not only static, but have also a significant cyclic component. An estimated 250 million cyclic load changes may lead to an accumulation of plastic deformation in the soil that potentially may affect operability or lifespan of the plant. During a preliminary geotechnical site survey of one of the largest (~150 km2) offshore wind project sites within the German Bight (~45 km North off the island Juist) a total of 16 drill cores with in situ cone penetration data and a total sample length of ~800 m where recovered. Preliminary foundation designs and static self weight and lateral load calculations were used to design a cycling triaxial lab testing program on discrete natural soil samples. Individual tests were performed by foundation type and at vertical and lateral load maxima to evaluate the long-term soil behaviour under cyclic load. Tests have been performed on granular, cohesive and intermediate natural soils. Following an introduction to the unique MARUM triaxial apparatus and testing conditions, the cyclic triaxial test results are shown and explained. Furthermore cyclic shear strength and stiffness are compared to their static counterparts. Unique soil behaviour like abrupt partial failure, pore pressure response and unexpected in part load independent cyclic deformation behaviour is discussed and

  20. International wind power market: The US/ECRE

    SciTech Connect

    Lilley, A.

    1995-12-31

    Today, wind power is in its infancy, comprising less than .1% of the world`s total energy mix. However, the world installed base of wind turbines doubled in the period 1989 to 1994, from 1.7 GW to over 3.6 GW. More than 85% of this growth occurred outside the US. In a study commissioned by AWEA for the period 1994 to 2000, market growth in 10 target countries is projected to be from 2 GW to 3.5 GW. The World Energy Council projects a total installed base of nearly 10 GW by the year 2000. Much of this growth is expected to come in developing countries. Driven by market related factors, the US industry has recently turned its attention to the international arena. AWEA, US/ECRE, and their partners in government can play a critical supporting role to industry as they make the transition from a domestically focused industry to one that is globally focused.

  1. In situ observations of suspended particulate matter plumes at an offshore wind farm, southern North Sea

    NASA Astrophysics Data System (ADS)

    Baeye, Matthias; Fettweis, Michael

    2015-08-01

    Suspended particulate matter (SPM) plumes associated with the monopile foundations of the Belgian offshore wind farm (OWF) Belwind I were acoustically profiled by means of a Doppler current profiler (ADCP). Together with the analysis of a bottom lander dataset of optical and acoustic backscatter sensors (OBSs and ADPs respectively), the spatiotemporal SPM plume dynamics were inferred. The fieldwork comprised (1) near-bed measurements of hydrodynamics and SPM concentrations in the direct vicinity of the wind turbines, by means of a bottom lander over a spring-neap cycle in May 2010; this dataset represents a typically tide-driven situation because there was no significant meteorological forcing during the measurement period; (2) additional vessel-based measurements conducted in May 2013 to capture the SPM plumes inside and outside the OWF over part of a tidal cycle. Both in situ datasets revealed that the SPM plumes were generated at the turbine piles, consistent with aerial and space-borne imagery. The SPM plumes are well aligned with the tidal current direction in the wake of the monopiles, concentrations being estimated to reach up to 5 times that of the background concentration of about 3 mg/l. It is suggested that the epifaunal communities colonizing the monopile surface and the protective rock collar at the base play a key role as source of the suspended matter recorded in the plumes. The organisms filter and trap fine SPM from the water column, resulting in predominant accumulation of SPM, including detritus and (pseudo-) faeces, at the base of the piles. When tidal currents exceed a certain velocity, fine particles in the near-bed fluff layer are re-suspended and transported downstream in the wake of the piles.

  2. Population ecology of American marten in New Hampshire: Impact of wind farm development in high elevation habitat

    NASA Astrophysics Data System (ADS)

    Siren, Alexej Peder Kelly

    This study examined marten ecology relative to wind farm development using radio-marked marten, camera trapping, and snow track surveys to meet study objectives. The local population was mostly breeding adults and was considered near carrying capacity. Mortality (predation) was biased towards females and young. Seasonal home ranges were small overall, and largest during summer and when marten used more regenerating and softwood forest. Selection at the landscape scale was more pronounced than at the stand scale; regenerating forest was selected against year-round. Stand selection for mature mixed-wood and softwood occurred in winter. Disturbance from wind farm construction resulted in less use and periodic displacement of marten, although marten maintained presence in the study area. Winter access by competitor canids was enhanced by maintained roads and snowmobile trails at high elevation. A balanced approach is encouraged to minimize developmental impacts in prime, high elevation habitat of recovering marten populations.

  3. An Adaptive Coordinated Control for an Offshore Wind Farm Connected VSC Based Multi-Terminal DC Transmission System

    NASA Astrophysics Data System (ADS)

    Kumar, M. Ajay; Srikanth, N. V.

    2014-11-01

    The voltage source converter (VSC) based multiterminal high voltage direct current (MTDC) transmission system is an interesting technical option to integrate offshore wind farms with the onshore grid due to its unique performance characteristics and reduced power loss via extruded DC cables. In order to enhance the reliability and stability of the MTDC system, an adaptive neuro fuzzy inference system (ANFIS) based coordinated control design has been addressed in this paper. A four terminal VSC-MTDC system which consists of an offshore wind farm and oil platform is implemented in MATLAB/ SimPowerSystems software. The proposed model is tested under different fault scenarios along with the converter outage and simulation results show that the novel coordinated control design has great dynamic stabilities and also the VSC-MTDC system can supply AC voltage of good quality to offshore loads during the disturbances.

  4. Examples of the Influence of Turbine Wakes on Downwind Power Output, Surface Wind Speed, Turbulence and Flow Convergence in Large Wind Farms

    NASA Astrophysics Data System (ADS)

    Takle, E. S.; Rajewski, D. A.; Lundquist, J. K.; Doorenbos, R. K.

    2014-12-01

    We have analyzed turbine power and concurrent wind speed, direction and turbulence data from surface 10-m flux towers in a large wind farm for experiments during four summer periods as part of the Crop Wind Energy Experiment (CWEX). We use these data to analyze surface differences for a near-wake (within 2.5 D of the turbine line), far wake (17 D downwind of the turbine line), and double wake (impacted by two lines of turbines about 34 D downwind of the first turbine line) locations. Composites are categorized by10 degree directional intervals and three ambient stability categories as defined by Rajewski et al. (2013): neutral (|z/L|<0.05), stable (z/L>0.05) and unstable (z/L<-0.05), where z is the height of the measurement and L is the Monin-Obhukov length. The dominant influence of the turbines is under stably stratified conditions (i. e., mostly at night). A 25% to 40% increase in mean wind speed occurs when turbine wakes are moving over the downwind station at a distance of 2.8 D and 5.4 D (D = fan diameter). For the double wake condition (flux station leeward of two lines of turbines) we find a daytime (unstable conditions) speed reduction of 20% for southerly wind, but for nighttime (stable conditions) the surface speeds are enhancedby 40-60% for SSW-SW winds. The speedup is reduced as wind directions shift to the west. We interpret these speed variations as due to the rotation of the wake and interaction (or not) with higher speed air above the rotor layer in highly sheared nocturnal low-level jet conditions. From a cluster of flux stations and three profiling lidars deployed within and around a cluster of turbines in 2013 (CWEX-13) we found evidence of mesoscale influences. In particular, surface convergence (wind direction deflection of 10-20 degrees) was observed during periods of low nighttime winds (hub-height winds of 4-6 m/s) with power reduction of 50-75%. This is consistent with a similar range of deflection observed from a line of turbines in CWEX

  5. Assessing trophic linkages in and around offshore wind farms using two high-speed optical sensors

    NASA Astrophysics Data System (ADS)

    Dudeck, Tim; Hufnagl, Marc; Auch, Dominik; Eckhardt, André; Möller, Klas-Ove; van Beusekom, Justus; Walter, Bettina; Möllmann, Christian; Floeter, Jens

    2016-04-01

    In search for clean, renewable energy sources European countries have built and planned numerous Offshore Wind Farms (OWF) in the North Sea region. While some research has been carried out on their influence on marine mammals and bottom-dwelling organisms, less is known about fish and lower trophic levels in these areas. Yet, marine mammals purposely seek these structures and there are indications that there are higher chances of fish encounters. However, the local bottom-up effects probably driving these aggregations of higher trophic level organisms are poorly understood. In this study we show preliminary results of primary and secondary production in and around German OWFs in the North Sea using a Laser Optical Particle Counter and a Video Plankton Recorder. With the two sensors working simultaneously on the TRIAXUS system at high speed, we were able to investigate and ground-truth size-spectrum changes on a very high spatial resolution making it possible to detect OWF effects from local to larger scales. Our results show new possibilities in OWF research and the necessity to collect highly resolved field data for meaningful results in these dynamic environments. Furthermore, the use of size spectra simplifies the integration of energy flow through low and medium trophic levels into biogeochemical models by using only a single automatically measurable variable such as size.

  6. Ecological impact assessments fail to reduce risk of bat casualties at wind farms.

    PubMed

    Lintott, Paul R; Richardson, Suzanne M; Hosken, David J; Fensome, Sophie A; Mathews, Fiona

    2016-11-07

    Demand for renewable energy is rising exponentially. While this has benefits in reducing greenhouse gas emissions, there may be costs to biodiversity [1]. Environmental Impact Assessments (EIAs) are the main tool used across the world to predict the overall positive and negative effects of renewable energy developments before planning consent is given, and the Ecological Impact Assessments (EcIAs) within them assess their species-specific effects. Given that EIAs are undertaken globally, are extremely expensive, and are enshrined in legislation, their place in evidence-based decision making deserves evaluation. Here we assess how well EIAs of wind-farm developments protect bats. We found they do not predict the risks to bats accurately, and even in those cases where high risk was correctly identified, the mitigation deployed did not avert the risk. Given that the primary purpose of an EIA is to make planning decisions evidence-based, our results indicate that EIA mitigation strategies used to date have been ineffective in protecting bats. In the future, greater emphasis should be placed on assessing the actual impacts post-construction and on developing effective mitigation strategies.

  7. Coupling the Weather Research and Forecasting (WRF) model and Large Eddy Simulations with Actuator Disk Model: predictions of wind farm power production

    NASA Astrophysics Data System (ADS)

    Garcia Cartagena, Edgardo Javier; Santoni, Christian; Ciri, Umberto; Iungo, Giacomo Valerio; Leonardi, Stefano

    2015-11-01

    A large-scale wind farm operating under realistic atmospheric conditions is studied by coupling a meso-scale and micro-scale models. For this purpose, the Weather Research and Forecasting model (WRF) is coupled with an in-house LES solver for wind farms. The code is based on a finite difference scheme, with a Runge-Kutta, fractional step and the Actuator Disk Model. The WRF model has been configured using seven one-way nested domains where the child domain has a mesh size one third of its parent domain. A horizontal resolution of 70 m is used in the innermost domain. A section from the smallest and finest nested domain, 7.5 diameters upwind of the wind farm is used as inlet boundary condition for the LES code. The wind farm consists in six-turbines aligned with the mean wind direction and streamwise spacing of 10 rotor diameters, (D), and 2.75D in the spanwise direction. Three simulations were performed by varying the velocity fluctuations at the inlet: random perturbations, precursor simulation, and recycling perturbation method. Results are compared with a simulation on the same wind farm with an ideal uniform wind speed to assess the importance of the time varying incoming wind velocity. Numerical simulations were performed at TACC (Grant CTS070066). This work was supported by NSF, (Grant IIA-1243482 WINDINSPIRE).

  8. Real-time Environmental Monitoring from a Wind Farm Platform in the Texas Hypoxic Zone

    NASA Astrophysics Data System (ADS)

    Mullins, R. L.; Dimarco, S. F.; Walpert, J. N.; Guinasso, N. L.; Howard, M. K.

    2009-12-01

    Ocean observing systems (OOS) provide coastal managers with data for informed decision-making. OOS are designed to monitor oceanographic and atmospheric conditions from a variety of offshore platforms. In the summer of 2009, a multi-disciplinary system, the Galveston Instrument Garden for Environmental Monitoring (GIGEM), was deployed off the coast of Galveston, Texas (Location: 29o 08’ 29.654’’N, 94o 44’ 51.339’’W) to monitor coastal waters and provide real-time observations for investigating processes responsible for coastal Texas hypoxia. Hypoxia occurs in the Gulf of Mexico over the continental shelf and refers to low dissolved oxygen concentrations in the bottom waters caused by a combination of environmental and physical parameters. Events form rapidly, last for a few days to weeks, and commonly occur along the Louisiana and Texas coasts; however, little research has been conducted to investigate the processes responsible for Texas hypoxia formation. GIGEM was designed to study this problem by contributing real-time measurements to compare with historical coastal data series. Unlike most coastal OOS, GIGEM is installed on an experimental wind farm platform operated by Wind Energy System Technologies Inc. This platform is the first executed offshore wind energy lease in the United States. GIGEM is comprised of two components, the subsurface mooring and a nearby bottom package. The data telemetry system includes a unique design of underwater and surface inductive modems. GIGEM is the only coastal OOS currently collecting real-time environmental water quality measurements on the Texas shelf. The work presented describes: the obstacles and challenges associated with deploying GIGEM, the flow of information from the water column to the user, and how this type of OOS fulfills the societal goals for protecting coastal ecosystems and improving coastal weather and ocean predictions envisioned by the Integrated Ocean Observing System (IOOS). Data and

  9. 77 FR 22569 - Interconnection of the Grande Prairie Wind Farm, Holt County, NE

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-16

    ... Prairie Wind, LLC (Grande Prairie Wind), a majority- owned subsidiary of Midwest Wind Energy, LLC, has applied to Western to interconnect their proposed wind energy generation project to Western's power... interconnect their proposed wind energy generation Project to Western's Fort Thompson- Grand...

  10. Framework for assessing impacts of pile-driving noise from offshore wind farm construction on a harbour seal population

    SciTech Connect

    Thompson, Paul M.; Hastie, Gordon D.; Nedwell, Jeremy; Barham, Richard; Brookes, Kate L.; Cordes, Line S.; Bailey, Helen; McLean, Nancy

    2013-11-15

    Offshore wind farm developments may impact protected marine mammal populations, requiring appropriate assessment under the EU Habitats Directive. We describe a framework developed to assess population level impacts of disturbance from piling noise on a protected harbour seal population in the vicinity of proposed wind farm developments in NE Scotland. Spatial patterns of seal distribution and received noise levels are integrated with available data on the potential impacts of noise to predict how many individuals are displaced or experience auditory injury. Expert judgement is used to link these impacts to changes in vital rates and applied to population models that compare population changes under baseline and construction scenarios over a 25 year period. We use published data and hypothetical piling scenarios to illustrate how the assessment framework has been used to support environmental assessments, explore the sensitivity of the framework to key assumptions, and discuss its potential application to other populations of marine mammals. -- Highlights: • We develop a framework to support Appropriate Assessment for harbour seal populations. • We assessed potential impacts of wind farm construction noise. • Data on distribution of seals and noise were used to predict effects on individuals. • Expert judgement linked these impacts to vital rates to model population change. • We explore the sensitivity of the framework to key assumptions and uncertainties.

  11. The role of atmospheric stability/turbulence on wakes at the Egmond aan Zee offshore wind farm

    NASA Astrophysics Data System (ADS)

    Barthelmie, R. J.; Churchfield, M. J.; Moriarty, P. J.; Lundquist, J. K.; Oxley, G. S.; Hahn, S.; Pryor, S. C.

    2015-06-01

    The aim of the paper is to present results from the NREL SOWFA project that compares simulations from models of different fidelity to meteorological and turbine data from the Egmond aan Zee wind farm. Initial results illustrate that wake behavior and impacts are strongly impacted by turbulence intensity [1]. This includes both power losses from wakes and loading illustrated by the out of plane bending moment. Here we focus on understanding the relationship between turbulence and atmospheric stability and whether power losses due to wakes can effectively be characterized by measures of turbulence alone or whether atmospheric stability as a whole plays a fundamental role in wake behavior. The study defines atmospheric stability using the Monin-Obukhov length estimated based on the temperature difference between 116 and 70 m. The data subset selected using this method for the calculation of the Monin-Obukhov length indicate little diurnal or directional dependence of the stability classes but a dominance of stable classes in the spring/unstable classes in fall and of near-neutral classes at high wind speeds (Figure 2). The analysis is complicated by the need to define turbulence intensity. We can select the ratio of the standard deviation of wind speed to mean wind speed in each observation period using data from the meteorological mast, in which case a substantial amount of data must be excluded due to the presence of the wind farm. An alternative is to use data from the wind turbines which could provide a larger data set for analysis. These approaches are examined and compared to illustrate their robustness. Finally, power losses from wakes are categorized according to stability and/or turbulence in order to understand their relative importance in determining the behavior of wind turbine wakes.

  12. How to mitigate impacts of wind farms on bats? A review of potential conservation measures in the European context

    SciTech Connect

    Peste, Filipa; Paula, Anabela; Silva, Luís P. da; Bernardino, Joana; Pereira, Pedro; Mascarenhas, Miguel; Costa, Hugo; Vieira, José; Bastos, Carlos; Pereira, Maria João Ramos

    2015-02-15

    Wind energy is growing worldwide as a source of power generation. Bat assemblages may be negatively affected by wind farms due to the fatality of a significant number of individuals after colliding with the moving turbines or experiencing barotrauma. The implementation of wind farms should follow standard procedures to prevent such negative impacts: avoid, reduce and offset, in what is known as the mitigation hierarchy. According to this approach avoiding impacts is the priority, followed by the minimisation of the identified impacts, and finally, when residual negative impacts still remain, those must be offset or at least compensated. This paper presents a review on conservation measures for bats and presents some guidelines within the compensation scenario, focusing on negative impacts that remain after avoidance and minimisation measures. The conservation strategies presented aim at the improvement of the ecological conditions for the bat assemblage as a whole. While developed under the European context, the proposed measures are potentially applicable elsewhere, taking into consideration the specificity of each region in terms of bat assemblages present, landscape features and policy context regarding nature and biodiversity conservation and management. An analysis of potential opportunities and constraints arising from the implementation of offset/compensation programmes and gaps in the current knowledge is also considered. - Highlights: • Wind energy impacts bat populations in ways not yet fully understood. • As the use of windfarms is growing worldwide greater impacts on bat populations are also expected. • Mitigation hierarchy provides a way to reduce impacts from new wind farm facilities. • Compensation measures may be used to reduce the residual effects on bat populations. • Identify bats ecological needs and compensate according to the existing surroundings.

  13. Evaluation of surface energy and carbon fluxes within a large wind farm during the CWEX-10/11 Crop Wind-energy EXperiments

    NASA Astrophysics Data System (ADS)

    Rajewski, D. A.; Takle, E. S.; Prueger, J. H.; Oncley, S.; Horst, T. W.; Pfeiffer, R.; Hatfield, J.; Spoth, K. K.; Doorenbos, R.

    2012-12-01

    The Crop Wind-energy EXperiment conducted in summer 2010 (very moist conditions) and summer 2011 (abnormally dry) included measurements of wind speed, temperature, relative humidity, turbulence kinetic energy, H2O, and CO2 at stations north and south of a line of turbines at the southwest edge of a large-scale 200-turbine wind farm (prevailing wind from the south). In contrast to previous studies that have reported turbine influences on surface wind speed and temperature, this report focuses on scalar fluxes of heat, H2O, and CO2. From previous measurements in agricultural fields we recognize the importance of non-turbine factors in analysis of the flux differences: variability of soil characteristics, moisture content, crop cultivar, management practices, planting dates, etc., which can create differences in what looks like a uniform field of maize (corn). We conceptualize the influences of turbines at canopy height at a given location in the field to arise from (1) wakes of reduced wind speed and turbulence conditions different from ambient that intersect the surface, (2) wakes that are passing overhead and interrupt the ambient turbulence that scales with height, or (3) changes in static pressure upwind and downwind of lines of turbines that create small-scale pressure gradients, localized flows, and changes to the vertical exchange of scalar variables. The turbine SCADA wind speed and wind direction provided by the wind farm operator facilitated our comparison of surface fluxes upwind and downwind as wakes moved laterally throughout the day and night. We report multiple levels of evidence that wind turbines increase vertical exchange of carbon dioxide and water vapor over the canopy. Latent heat and carbon fluxes are responsive to slight changes in the turbine wake position, and the flux differences are maximized when the periphery of the wake edge is above the station. The flux stations north of the turbine line report a larger net ecosystem exchange

  14. Perturbations to the Spatial and Temporal Characteristics of the Diurnally-Varying Atmospheric Boundary Layer Due to an Extensive Wind Farm

    NASA Astrophysics Data System (ADS)

    Sharma, V.; Parlange, M. B.; Calaf, M.

    2016-08-01

    The effect of extensive terrestrial wind farms on the spatio-temporal structure of the diurnally-evolving atmospheric boundary layer is explored. High-resolution large-eddy simulations of a realistic diurnal cycle with an embedded wind farm are performed. Simulations are forced by a constant geostrophic velocity with time-varying surface boundary conditions derived from a selected period of the CASES-99 field campaign. Through analysis of the bulk statistics of the flow as a function of height and time, it is shown that extensive wind farms shift the inertial oscillations and the associated nocturnal low-level jet vertically upwards by approximately 200 m; cause a three times stronger stratification between the surface and the rotor-disk region, and as a consequence, delay the formation and growth of the convective boundary layer (CBL) by approximately 2 h. These perturbations are shown to have a direct impact on the potential power output of an extensive wind farm with the displacement of the low-level jet causing lower power output during the night as compared to the day. The low-power regime at night is shown to persist for almost 2 h beyond the morning transition due to the reduced growth of the CBL. It is shown that the wind farm induces a deeper entrainment region with greater entrainment fluxes. Finally, it is found that the diurnally-averaged effective roughness length for wind farms is much lower than the reference value computed theoretically for neutral conditions.

  15. Perturbations to the Spatial and Temporal Characteristics of the Diurnally-Varying Atmospheric Boundary Layer Due to an Extensive Wind Farm

    NASA Astrophysics Data System (ADS)

    Sharma, V.; Parlange, M. B.; Calaf, M.

    2017-02-01

    The effect of extensive terrestrial wind farms on the spatio-temporal structure of the diurnally-evolving atmospheric boundary layer is explored. High-resolution large-eddy simulations of a realistic diurnal cycle with an embedded wind farm are performed. Simulations are forced by a constant geostrophic velocity with time-varying surface boundary conditions derived from a selected period of the CASES-99 field campaign. Through analysis of the bulk statistics of the flow as a function of height and time, it is shown that extensive wind farms shift the inertial oscillations and the associated nocturnal low-level jet vertically upwards by approximately 200 m; cause a three times stronger stratification between the surface and the rotor-disk region, and as a consequence, delay the formation and growth of the convective boundary layer (CBL) by approximately 2 h. These perturbations are shown to have a direct impact on the potential power output of an extensive wind farm with the displacement of the low-level jet causing lower power output during the night as compared to the day. The low-power regime at night is shown to persist for almost 2 h beyond the morning transition due to the reduced growth of the CBL. It is shown that the wind farm induces a deeper entrainment region with greater entrainment fluxes. Finally, it is found that the diurnally-averaged effective roughness length for wind farms is much lower than the reference value computed theoretically for neutral conditions.

  16. A modelling framework to predict bat activity patterns on wind farms: An outline of possible applications on mountain ridges of North Portugal.

    PubMed

    Silva, Carmen; Cabral, João Alexandre; Hughes, Samantha Jane; Santos, Mário

    2017-03-01

    Worldwide ecological impact assessments of wind farms have gathered relevant information on bat activity patterns. Since conventional bat study methods require intensive field work, the prediction of bat activity might prove useful by anticipating activity patterns and estimating attractiveness concomitant with the wind farm location. A novel framework was developed, based on the stochastic dynamic methodology (StDM) principles, to predict bat activity on mountain ridges with wind farms. We illustrate the framework application using regional data from North Portugal by merging information from several environmental monitoring programmes associated with diverse wind energy facilities that enable integrating the multifactorial influences of meteorological conditions, land cover and geographical variables on bat activity patterns. Output from this innovative methodology can anticipate episodes of exceptional bat activity, which, if correlated with collision probability, can be used to guide wind farm management strategy such as halting wind turbines during hazardous periods. If properly calibrated with regional gradients of environmental variables from mountain ridges with windfarms, the proposed methodology can be used as a complementary tool in environmental impact assessments and ecological monitoring, using predicted bat activity to assist decision making concerning the future location of wind farms and the implementation of effective mitigation measures.

  17. Modeling turbine wakes and power losses within the Horns Rev offshore wind farm using large-eddy simulation

    NASA Astrophysics Data System (ADS)

    Wu, Yu-Ting; Porte-Agel, Fernando

    2013-04-01

    A recently-developed large-eddy simulations (LES) framework is implemented to predict multiple wake flows and the associated power losses within the Horns Rev offshore wind farm under near-neutral stability conditions. A tuning-free Lagrangian scale-dependent dynamic subgrid-scale (SGS) model is used for the parametrization of the SGS stresses. The turbine-generated power outputs and the turbine-induced forces (e.g., thrust, lift, drag) are parameterized using two models: (a) the traditional actuator-disk model without rotation (ADM-NR), which uses the 1D momentum theory to relate the power output and the thrust force with a representative velocity over the rotor (e.g., the disk-averaged velocity); and (b) the actuator-disk model with rotation (ADM-R), which adopts blade element theory to calculate the lift and drag forces (that produce thrust, rotor shaft torque, and power) based on the local blade and flow characteristics. In general, the predicted power outputs obtained using the ADM-R are in good agreement with observed power data from the Horns Rev wind farm. The ADM-NR tends to underestimate the power output. A similar under-prediction is obtained using industry-standard wind-farm models such as the Wind Atlas Analysis and Application Program (WAsP). Simulations using different inflow conditions show that the mean wind direction has a strong effect on the spatial distributions of the time-averaged velocity and the turbulence intensity within the farm. These, in turn, affect the power output and the fatigue loads on the turbines. When the prevailing wind direction is parallel to the turbine rows (i.e., a full wake condition), the velocity deficit and the power losses are largest, and the turbulence intensity levels are highest and have a symmetric pattern (dual-peak at hub height) on both sides of the turbine wakes. A detailed analysis of the turbulence kinetic energy budget in the full wake condition shows an important effect of the increased turbulence level

  18. Changes in fish communities on a small spatial scale, an effect of increased habitat complexity by an offshore wind farm.

    PubMed

    van Hal, R; Griffioen, A B; van Keeken, O A

    2017-01-31

    The number of offshore wind farms (OWF) is increasing to meet the demands for renewable energy. The piles and hard substrate surrounding these piles creates new habitat for species with preference to hard substrates. We studied the impact of this hard substrate on the fish community in a Dutch OWF in the sandy southern North Sea, which had been in operation for five years. Multi-mesh gillnets were placed near the OWF structures on the hard substrate protection revetments and on the sandy bottom in the middle of the farm. The catches indicated attraction of cod, pouting, bullrout and edible and velvet crab, while attraction to the sandy habitat was shown for flatfish and whiting. Further, two species previously not caught in this area, goldsinny wrasse and grey trigger fish, were caught on the hard substrate. In addition a Dual-Frequency Identification Sonar (DIDSON) was used to record transects through the farm to observe individual fish in the water column throughout the farm and very near the OWF structures. High abundances of fish near the structure were observed during some days, while during other days equal distribution of fish in the area was observed. The area around the structures is thus only used temporarily for shelter or feeding. The DIDSON also allowed looking at the aggregation level of the fish. Seasonally the aggregation level differed most likely due to different species occurring in the area. In April, most fish were aggregated in schools, while in summer most observations were individual fish or loose aggregations. The wind farm structures had limited effect on the aggregation level compared to season or weather conditions.

  19. Proactive monitoring of an onshore wind farm through lidar measurements, SCADA data and a data-driven RANS solver

    NASA Astrophysics Data System (ADS)

    Iungo, Giacomo Valerio; Camarri, Simone; Ciri, Umberto; El-Asha, Said; Leonardi, Stefano; Rotea, Mario A.; Santhanagopalan, Vignesh; Viola, Francesco; Zhan, Lu

    2016-11-01

    Site conditions, such as topography and local climate, as well as wind farm layout strongly affect performance of a wind power plant. Therefore, predictions of wake interactions and their effects on power production still remain a great challenge in wind energy. For this study, an onshore wind turbine array was monitored through lidar measurements, SCADA and met-tower data. Power losses due to wake interactions were estimated to be approximately 4% and 2% of the total power production under stable and convective conditions, respectively. This dataset was then leveraged for the calibration of a data driven RANS (DDRANS) solver, which is a compelling tool for prediction of wind turbine wakes and power production. DDRANS is characterized by a computational cost as low as that for engineering wake models, and adequate accuracy achieved through data-driven tuning of the turbulence closure model. DDRANS is based on a parabolic formulation, axisymmetry and boundary layer approximations, which allow achieving low computational costs. The turbulence closure model consists in a mixing length model, which is optimally calibrated with the experimental dataset. Assessment of DDRANS is then performed through lidar and SCADA data for different atmospheric conditions. This material is based upon work supported by the National Science Foundation under the I/UCRC WindSTAR, NSF Award IIP 1362033.

  20. Optimized solar-wind-powered drip irrigation for farming in developing countries

    NASA Astrophysics Data System (ADS)

    Barreto, Carolina M.

    The two billion people produce 80% of all food consumed in the developing world and 1.3 billion lack access to electricity. Agricultural production will have to increase by about 70% worldwide by 2050 and to achieve this about 50% more primary energy has to be made available by 2035. Energy-smart agri-food systems can improve productivity in the food sector, reduce energy poverty in rural areas and contribute to achieving food security and sustainable development. Agriculture can help reduce poverty for 75% of the world's poor, who live in rural areas and work mainly in farming. The costs associated with irrigation pumping are directly affected by energy prices and have a strong impact on farmer income. Solar-wind (SW) drip irrigation (DI) is a sustainable method to meet these challenges. This dissertation shows with onsite data the low cost of SW pumping technologies correlating the water consumption (evapotranspiration) and the water production (SW pumping). The author designed, installed, and collected operating data from the six SWDI systems in Peru and in the Tohono O'odham Nation in AZ. The author developed, tested, and a simplified model for solar engineers to size SWDI systems. The author developed a business concept to scale up the SWDI technology. The outcome was a simplified design approach for a DI system powered by low cost SW pumping systems optimized based on the logged on site data. The optimization showed that the SWDI system is an income generating technology and that by increasing the crop production per unit area, it allowed small farmers to pay for the system. The efficient system resulted in increased yields, sometimes three to four fold. The system is a model for smallholder agriculture in developing countries and can increase nutrition and greater incomes for the world's poor.

  1. Analysis of internal drive train dynamics in a wind turbine

    NASA Astrophysics Data System (ADS)

    Peeters, Joris L. M.; Vandepitte, Dirk; Sas, Paul

    2006-01-01

    Three types of multibody models are presented for the investigation of the internal dynamics of a drive train in a wind turbine. The first approach is limited to the analysis of torsional vibrations only. Then a rigid multibody model is presented with special focus on the representation of the bearings and gears in the drive train. The generic model implementation can be used for parallel as well as planetary gear stages with both helical and spur gears. Examples for different gear stages describe the use of the presented formulations. Furthermore, the influence of the helix angle and the flexibility of the bearings on the results of eigenmode calculations are discussed. The eigenmodes of a planetary stage are classified as rotational, translational or out-of-plane modes. Thirdly, the extension to a flexible multibody model is presented as a method to include directly the drive train components' flexibilities. Finally, a comparison of two different modelling techniques is discussed for a wind turbine's drive train with a helical parallel gear stage and two planetary gear stages. In addition, the response calculation for a torque input at the generator demonstrates which eigenmodes can be excited through this path. Copyright

  2. CRITICAL ASSUMPTIONS IN THE F-TANK FARM CLOSURE OPERATIONAL DOCUMENTATION REGARDING WASTE TANK INTERNAL CONFIGURATIONS

    SciTech Connect

    Hommel, S.; Fountain, D.

    2012-03-28

    The intent of this document is to provide clarification of critical assumptions regarding the internal configurations of liquid waste tanks at operational closure, with respect to F-Tank Farm (FTF) closure documentation. For the purposes of this document, FTF closure documentation includes: (1) Performance Assessment for the F-Tank Farm at the Savannah River Site (hereafter referred to as the FTF PA) (SRS-REG-2007-00002), (2) Basis for Section 3116 Determination for Closure of F-Tank Farm at the Savannah River Site (DOE/SRS-WD-2012-001), (3) Tier 1 Closure Plan for the F-Area Waste Tank Systems at the Savannah River Site (SRR-CWDA-2010-00147), (4) F-Tank Farm Tanks 18 and 19 DOE Manual 435.1-1 Tier 2 Closure Plan Savannah River Site (SRR-CWDA-2011-00015), (5) Industrial Wastewater Closure Module for the Liquid Waste Tanks 18 and 19 (SRRCWDA-2010-00003), and (6) Tank 18/Tank 19 Special Analysis for the Performance Assessment for the F-Tank Farm at the Savannah River Site (hereafter referred to as the Tank 18/Tank 19 Special Analysis) (SRR-CWDA-2010-00124). Note that the first three FTF closure documents listed apply to the entire FTF, whereas the last three FTF closure documents listed are specific to Tanks 18 and 19. These two waste tanks are expected to be the first two tanks to be grouted and operationally closed under the current suite of FTF closure documents and many of the assumptions and approaches that apply to these two tanks are also applicable to the other FTF waste tanks and operational closure processes.

  3. A telephone survey of internal parasite control practices on sheep farms in Spain.

    PubMed

    Rojo-Vázquez, Francisco A; Hosking, Barry C

    2013-02-18

    A telephone survey of farmers was conducted to determine current internal parasite control practices on sheep farms in Spain; the farmers were interviewed by their veterinarians. Anthelmintic choice was largely on veterinary advice and dominated by benzimidazoles and macrocyclic lactones. Anthelmintic rotation was separated into: no rotation (42% of farms); annual rotation (36%); rotate within year (20%); and rotate every second year (2%). The mean annual number of treatments varied subtly by region; ewes and rams 1.6-2.1, replacement lambs 1.7-2.1. Anthelmintics are administered primarily during spring and early summer (47% of treatments), and autumn (41%). Thirty-two percent of farmers introduced sheep to their properties and more than half did not quarantine drench the arrivals.

  4. Impact of assimilating met-tower, turbine nacelle anemometer and other intensified wind farm observation systems on 0 - 12h wind energy prediction using the NCAR WRF-RTFDDA model

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Cheng, W.; Liu, Y. W.; Wiener, G.; Frehlich, R.; Mahoney, W.; Warner, T.; Himelic, J.; Parks, K.; Early, S.

    2010-09-01

    In collaboration with Xcel Energy and Vasaila Inc., the National Center for Atmospheric Research (NCAR) conducts modeling study to evaluate the existing and the enhanced intensive observation systems for wind power nowcasting and short-range forecasting at a northern Colorado wind farm. The NCAR WRF (Weather Research and Forecasting model) based Real-Time Four-Dimensional Data Assimilation (RTFDDA) and forecasting system, which has been employed to support Xcel Energy operational wind forecast, was used in this study. The observational data include ten met-towers, a 915Hz wind profiler, a sodar and a Windcube Doppler lidar, besides the in-farm met-towers and wind speed and power reports from more than 300 of wind turbines. The WRF-RTFDDA 4-dimensioanl data assimilation algorithm allows to spread and propagate observation information in the WRF model space (x, y, z and time) with weighting functions built according to the observation location and time. The WRF-RTFDDA was set up to run with four nested domains with grid increments of 30, 10, 3.333 and 1.111km respectively. The standard and diverse non-conventional observations are assimilated on coarse grid domains along with the special wind farm observations. In this study, we investigate a) spread of surface observations in PBL according to PBL depth and regimes, b) optimization of horizontal influence radii and steep-terrain adjustment, and c) impact of different observation platforms and data types on 0 - 12 h wind prediction . It is found that PBL mixing and thermodynamic structures are greatly influenced by the PBL parameterization formulation. The range of the data assimilation effect on forecasts relies on weather and PBL regimes. In most cases, assimilation of in-farm and near-farm observations improves up to 12-hour wind power prediction and assimilation of in-farm data can significantly improves 0 - 6 hour forecasts.

  5. Wind resource characterization results to support the Sandia Wind Farm Feasibility Study : August 2008 through March 2009.

    SciTech Connect

    Deola, Regina Anne

    2010-01-01

    Sandia National Laboratories Wind Technology Department is investigating the feasibility of using local wind resources to meet the requirements of Executive Order 13423 and DOE Order 430.2B. These Orders, along with the DOE TEAM initiative, identify the use of on-site renewable energy projects to meet specified renewable energy goals over the next 3 to 5 years. A temporary 30-meter meteorological tower was used to perform interim monitoring while the National Environmental Policy Act (NEPA) process for the larger Wind Feasibility Project ensued. This report presents the analysis of the data collected from the 30-meter meteorological tower.

  6. A forensic investigation into the etiology of bat mortality at a wind farm: barotrauma or traumatic injury?

    PubMed

    Rollins, K E; Meyerholz, D K; Johnson, G D; Capparella, A P; Loew, S S

    2012-03-01

    Migrating bats have increased mortality near moving turbine blades at wind farms. The authors evaluated competing hypotheses of barotrauma and traumatic injury to determine the cause. They first examined the utility of lungs from salvaged bat carcasses for histopathologic diagnosis of barotrauma and studied laboratory mice as a model system. Postmortem time, environmental temperature, and freezing of carcasses all affected the development of vascular congestion, hemorrhage, and edema. These common tissue artifacts mimicked the diagnostic criteria of pulmonary barotrauma; therefore, lung tissues from salvaged bats should not be used for barotrauma diagnosis. The authors next compared wind farm (WF) bats to building collision (BC) bats collected near downtown Chicago buildings. WF bats had an increased incidence in fracture cases and specific bone fractures and had more external lacerations than BC bats. WF bats had additional features of traumatic injury, including diaphragmatic hernia, subcutaneous hemorrhage, and bone marrow emboli. In summary, 73% (190 of 262) of WF bats had lesions consistent with traumatic injury. The authors then examined for ruptured tympana, a sensitive marker of barotrauma in humans. BC bats had only 1 case (2%, 1 of 42), but this was attributed to concurrent cranial fractures, whereas WF bats had a 20% (16 of 81) incidence. When cases with concurrent traumatic injury were excluded, this yielded a small fraction (6%, 5 of 81) of WF bats with lesions possibly consistent with barotrauma etiology. Forensic pathology examination of the data strongly suggests that traumatic injury is the major cause of bat mortality at wind farms and, at best, barotrauma is a minor etiology.

  7. Adding concentrated solar power plants to wind farms to achieve a good utility electrical load match

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Texas has the greatest installed wind turbine capacity of any state in the United States, the percentage of wind capacity approaches 10% of the utilities capacity (in 2010 the total wind generated capacity in Texas was 8%). It is becomimg increasingly difficult for the utility to balance the elec...

  8. Using the coupled wake boundary layer model to evaluate the effect of turbulence intensity on wind farm performance

    NASA Astrophysics Data System (ADS)

    Stevens, Richard J. A. M.; Gayme, Dennice; Meneveau, Charles

    2015-06-01

    We use the recently introduced coupled wake boundary layer (CWBL) model to predict the effect of turbulence intensity on the performance of a wind farm. The CWBL model combines a standard wake model with a “top-down” approach to get improved predictions for the power output compared to a stand-alone wake model. Here we compare the CWBL model results for different turbulence intensities with the Horns Rev field measurements by Hansen et al., Wind Energy 15, 183196 (2012). We show that the main trends as function of the turbulence intensity are captured very well by the model and discuss differences between the field measurements and model results based on comparisons with LES results from Wu and Porté-Agel, Renewable Energy 75, 945-955 (2015).

  9. Wind-Farm Forecasting Using the HARMONIE Weather Forecast Model and Bayes Model Averaging for Bias Removal.

    NASA Astrophysics Data System (ADS)

    O'Brien, Enda; McKinstry, Alastair; Ralph, Adam

    2015-04-01

    Building on previous work presented at EGU 2013 (http://www.sciencedirect.com/science/article/pii/S1876610213016068 ), more results are available now from a different wind-farm in complex terrain in southwest Ireland. The basic approach is to interpolate wind-speed forecasts from an operational weather forecast model (i.e., HARMONIE in the case of Ireland) to the precise location of each wind-turbine, and then use Bayes Model Averaging (BMA; with statistical information collected from a prior training-period of e.g., 25 days) to remove systematic biases. Bias-corrected wind-speed forecasts (and associated power-generation forecasts) are then provided twice daily (at 5am and 5pm) out to 30 hours, with each forecast validation fed back to BMA for future learning. 30-hr forecasts from the operational Met Éireann HARMONIE model at 2.5km resolution have been validated against turbine SCADA observations since Jan. 2014. An extra high-resolution (0.5km grid-spacing) HARMONIE configuration has been run since Nov. 2014 as an extra member of the forecast "ensemble". A new version of HARMONIE with extra filters designed to stabilize high-resolution configurations has been run since Jan. 2015. Measures of forecast skill and forecast errors will be provided, and the contributions made by the various physical and computational enhancements to HARMONIE will be quantified.

  10. Brillouin distributed temperature sensing system for monitoring of submarine export cables of off-shore wind farms

    NASA Astrophysics Data System (ADS)

    Marx, Benjamin; Rath, Alexander; Kolm, Frederick; Schröder, Andreas; Buntebarth, Christian; Dreß, Albrecht; Hill, Wieland

    2016-05-01

    For high-voltage cables, the maximum temperature of the insulation must never be exceeded at any location and at any load condition. The local temperatures depend not only on the cable design and load history, but also on the local thermal environment of the cable. Therefore, distributed temperature monitoring of high-voltage cables is essential to ensure the integrity of the cable at high load. Especially, the load of the export cables of wind farms varies strongly in dependence on weather conditions. In this field study, we demonstrate the measurement performance of a new, robust Brillouin distributed temperature sensing system (Brillouin-DTS). The system is based on spontaneous Brillouin scattering and does not require a fibre loop. This is essential for long submarine high-voltage cables, where normally no loop can be formed in the seabed. It is completely passively cooled and does not contain any moving or wearing parts. The instrument is dedicated for use in industrial and other rough environments. With a measuring time below 10 min, the temperature resolution is better than 1 °C for distances up to 50 km. In the field study, the submarine export cable of an off-shore wind farm has been monitored. The temperature profile of the export cable shows several hot spots, mostly located at cable joints, and also several cold spots.

  11. Enhancing kinetic energy entrainment in LES of large wind farms by unconventional forcing at the turbine rotors

    NASA Astrophysics Data System (ADS)

    Verhulst, Claire; Meneveau, Charles

    2015-11-01

    Vertical entrainment of mean kinetic energy is believed to be a limiting factor for power generation in very large wind farms, which operate in the turbulent atmospheric boundary layer and experience detrimental wake effects. A new approach, meant to increase vertical entrainment and aid wake recovery, is proposed and evaluated with a preliminary ``proof of concept'' test using Large Eddy Simulation (LES) with periodic boundary conditions to obtain realistic fully developed flow. In addition to the traditional actuator thrust force, a synthetic vertical force is applied at the turbine rotors to force high-speed flow downward and low-speed flow upward. The ratio of the vertical force and the thrust force, held constant within each case, ranges from 0 to 1 across six cases and is applied independently at each turbine. The proposed approach is found to increase the power extraction and mean kinetic energy entrainment significantly, by up to 95% when the vertical force is similar in magnitude to the thrust force. The effect of the forcing scheme on the mean velocity field is considered in detail. In addition, a quadrant analysis is performed to determine how the synthetic forcing changes the statistical characteristics of the mean kinetic energy entrainment within the wind farm. This work was supported by NSF grant 1243482 (the WINDINSPIRE project).

  12. Epifauna dynamics at an offshore foundation--implications of future wind power farming in the North Sea.

    PubMed

    Krone, Roland; Gutow, Lars; Joschko, Tanja J; Schröder, Alexander

    2013-04-01

    In the light of the introduction of thousands of large offshore wind power foundations into the North Sea within the next decades, this manuscript focuses on the biofouling processes and likely reef effects. The study explores the macrozoobenthos (biofouling) colonization at an offshore platform which is comparable to offshore wind turbine foundations. A total of 183 single samples were taken and the parameters water depth and time were considered comparing biofouling masses and communities. The blue mussel Mytilus edulis, Anthozoa and the Amphipoda Jassa spp. were the dominant species. The community from the 1 m zone and those from the 5 and 20-28 m zones can clearly be differentiated. The 10 m zone community represents the transition between the M. edulis dominated 1 m and 5 m zones and the Anthozoa dominated 20-28 m zone. In the future offshore wind farms, thousands of wind turbine foundations will provide habitat for a hard bottom fauna which is otherwise restricted to the sparse rocky habitats scattered within extensive sedimentary soft bottoms of the German Bight. However, offshore wind power foundations cannot be considered natural rock equivalents as they selectively increase certain natural hard bottom species. The surface of the construction (1280 m²) was covered by an average of 4300 kg biomass. This foundation concentrates on its footprint area (1024 m²) 35 times more macrozoobenthos biomass than the same area of soft bottom in the German exclusive economic zone (0.12 kg m(-2)), functioning as a biomass hotspot. Concerning the temporal biomass variation, we assume that at least 2700 kg biomass was exported on a yearly basis. 345 × 10(4) single mussel shells of different sizes were produced during the study period. It is anticipated that the M. edulis abundance will increase in the North Sea due to the expansion of the offshore wind farm development. This will result in the enhanced production of secondary hard substrate (mussel shells

  13. Standardized Software for Wind Load Forecast Error Analyses and Predictions Based on Wavelet-ARIMA Models - Applications at Multiple Geographically Distributed Wind Farms

    SciTech Connect

    Hou, Zhangshuan; Makarov, Yuri V.; Samaan, Nader A.; Etingov, Pavel V.

    2013-03-19

    Given the multi-scale variability and uncertainty of wind generation and forecast errors, it is a natural choice to use time-frequency representation (TFR) as a view of the corresponding time series represented over both time and frequency. Here we use wavelet transform (WT) to expand the signal in terms of wavelet functions which are localized in both time and frequency. Each WT component is more stationary and has consistent auto-correlation pattern. We combined wavelet analyses with time series forecast approaches such as ARIMA, and tested the approach at three different wind farms located far away from each other. The prediction capability is satisfactory -- the day-ahead prediction of errors match the original error values very well, including the patterns. The observations are well located within the predictive intervals. Integrating our wavelet-ARIMA (‘stochastic’) model with the weather forecast model (‘deterministic’) will improve our ability significantly to predict wind power generation and reduce predictive uncertainty.

  14. Effects of pile-driving on harbour porpoises (Phocoena phocoena) at the first offshore wind farm in Germany

    NASA Astrophysics Data System (ADS)

    Dähne, Michael; Gilles, Anita; Lucke, Klaus; Peschko, Verena; Adler, Sven; Krügel, Kathrin; Sundermeyer, Janne; Siebert, Ursula

    2013-06-01

    The first offshore wind farm ‘alpha ventus’ in the German North Sea was constructed north east of Borkum Reef Ground approximately 45 km north off the German coast in 2008 and 2009 using percussive piling for the foundations of 12 wind turbines. Visual monitoring of harbour porpoises was conducted prior to as well as during construction and operation by means of 15 aerial line transect distance sampling surveys, from 2008 to 2010. Static acoustic monitoring (SAM) with echolocation click loggers at 12 positions was performed additionally from 2008 to 2011. SAM devices were deployed between 1 and 50 km from the centre of the wind farm. During aerial surveys, 18 600 km of transect lines were covered in two survey areas (10 934 and 11 824 km2) and 1392 harbour porpoise sightings were recorded. Lowest densities were documented during the construction period in 2009. The spatial distribution pattern recorded on two aerial surveys three weeks before and exactly during pile-driving points towards a strong avoidance response within 20 km distance of the noise source. Generalized additive modelling of SAM data showed a negative impact of pile-driving on relative porpoise detection rates at eight positions at distances less than 10.8 km. Increased detection rates were found at two positions at 25 and 50 km distance suggesting that porpoises were displaced towards these positions. A pile-driving related behavioural reaction could thus be detected using SAM at a much larger distance than a pure avoidance radius would suggest. The first waiting time (interval between porpoise detections of at least 10 min), after piling started, increased with longer piling durations. A gradient in avoidance, a gradual fading of the avoidance reaction with increasing distance from the piling site, is hence most probably a product of an incomplete displacement during shorter piling events.

  15. An assessment of non-volant terrestrial vertebrates response to wind farms--a study of small mammals.

    PubMed

    Łopucki, Rafał; Mróz, Iwona

    2016-02-01

    The majority of studies on the effects of wind energy development on wildlife have been focused on birds and bats, whereas knowledge of the response of terrestrial, non-flying vertebrates is very scarce. In this paper, the impact of three functioning wind farms on terrestrial small mammal communities (rodents and shrews) and the population parameters of the most abundant species were studied. The study was carried out in southeastern Poland within the foothills of the Outer Western Carpathians. Small mammals were captured at 12 sites around wind turbines and at 12 control sites. In total, from 1200 trap-days, 885 individuals of 14 studied mammal species were captured. There was no difference in the characteristics of communities of small mammals near wind turbines and within control sites; i.e. these types of sites were inhabited by a similar number of species of similar abundance, similar species composition, species diversity (H' index) and species evenness (J') (Pielou's index). For the two species with the highest proportion in the communities (Apodemus agrarius and Microtus arvalis), the parameters of their populations (mean body mass, sex ratio, the proportion of adult individuals and the proportion of reproductive female) were analysed. In both species, none of the analysed parameters differed significantly between sites in the vicinity of turbines and control sites. For future studies on the impact of wind turbines on small terrestrial mammals in different geographical areas and different species communities, we recommend the method of paired 'turbine-control sites' as appropriate for animal species with pronounced fluctuations in population numbers.

  16. Enrichment and shifts in macrobenthic assemblages in an offshore wind farm area in the Belgian part of the North Sea.

    PubMed

    Coates, Delphine A; Deschutter, Yana; Vincx, Magda; Vanaverbeke, Jan

    2014-04-01

    The growing development of offshore wind energy installations across the North Sea is producing new hard anthropogenic structures in the natural soft sediments, causing changes to the surrounding macrobenthos. The extent of modification in permeable sediments around a gravity based wind turbine in the Belgian part of the North Sea was investigated in the period 2011-2012, along four gradients (south-west, north-east, south-east, north-west). Sediment grain size significantly reduced from 427 μm at 200 m to 312 ± 3 μm at 15 m from the foundation along the south-west and north-west gradients. The organic matter content increased from 0.4 ± 0.01% at 100 m to 2.5 ± 0.9% at 15 m from the foundation. The observed changes in environmental characteristics triggered an increase in the macrobenthic density from 1390 ± 129 ind m⁻² at 200 m to 18 583 ± 6713 ind m⁻² at 15 m together with an enhanced diversity from 10 ± 2 at 200 m to 30 ± 5 species per sample at 15 m. Shifts in species dominance were also detected with a greater dominance of the ecosystem-engineer Lanice conchilega (16-25%) close to the foundation. This study suggests a viable prediction of the effects offshore wind farms could create to the naturally occurring macrobenthos on a large-scale.

  17. Adding Complex Terrain and Stable Atmospheric Condition Capability to the OpenFOAM-based Flow Solver of the Simulator for On/Offshore Wind Farm Applications (SOWFA): Preprint

    SciTech Connect

    Churchfield, M. J.; Sang, L.; Moriarty, P. J.

    2013-09-01

    This paper describes changes made to NREL's OpenFOAM-based wind plant aerodynamics solver such that it can compute the stably stratified atmospheric boundary layer and flow over terrain. Background about the flow solver, the Simulator for Off/Onshore Wind Farm Applications (SOWFA) is given, followed by details of the stable stratification/complex terrain modifications to SOWFA, along with somepreliminary results calculations of a stable atmospheric boundary layer and flow over a simply set of hills.

  18. Internal gravity wave-atmospheric wind interaction - A cause of clear air turbulence.

    NASA Technical Reports Server (NTRS)

    Bekofske, K.; Liu, V. C.

    1972-01-01

    The interaction between an internal gravity wave (IGW) and a vertical wind shear is discussed as a possible cause in the production of clear air turbulence in the free atmosphere. It is shown that under certain typical condition the interaction of an IGW with a background wind shear near a critical level provides a mechanism for depositing sufficient momentum in certain regions of the atmosphere to significantly increase the local mean wind shear and to lead to the production of turbulence.

  19. Visualization and Analysis of Vortex-Turbine Intersections in Wind Farms.

    PubMed

    Shafii, Sohail; Obermaier, Harald; Linn, Rodman; Koo, Eunmo; Hlawitschka, Mario; Garth, Christoph; Hamann, Bernd; Joy, Kenneth

    2013-02-13

    Characterizing the interplay between the vortices and forces acting on a wind turbine's blades in a qualitative and quantitative way holds the potential for significantly improving large wind turbine design. The paper introduces an integrated pipeline for highly effective wind and force field analysis and visualization. We extract vortices induced by a turbine's rotation in a wind field, and characterize vortices in conjunction with numerically simulated forces on the blade surfaces as these vortices strike another turbine's blades downstream. The scientifically relevant issue to be studied is the relationship between the extracted, approximate locations on the blades where vortices strike the blades and the forces that exist in those locations. This integrated approach is used to detect and analyze turbulent flow that causes local impact on the wind turbine blade structure. The results that we present are based on analyzing the wind and force field data sets generated by numerical simulations, and allow domain scientists to relate vortex-blade interactions with power output loss in turbines and turbine life-expectancy. Our methods have the potential to improve turbine design in order to save costs related to turbine operation and maintenance.

  20. Visualization and analysis of vortex-turbine intersections in wind farms.

    PubMed

    Shafii, Sohail; Obermaier, Herald; Linn, Rodman; Koo, Eunmo; Hlawitschka, Mario; Garth, Christoph; Hamann, Bernd; Joy, Kenneth I

    2013-09-01

    Characterizing the interplay between the vortices and forces acting on a wind turbine's blades in a qualitative and quantitative way holds the potential for significantly improving large wind turbine design. This paper introduces an integrated pipeline for highly effective wind and force field analysis and visualization. We extract vortices induced by a turbine's rotation in a wind field, and characterize vortices in conjunction with numerically simulated forces on the blade surfaces as these vortices strike another turbine's blades downstream. The scientifically relevant issue to be studied is the relationship between the extracted, approximate locations on the blades where vortices strike the blades and the forces that exist in those locations. This integrated approach is used to detect and analyze turbulent flow that causes local impact on the wind turbine blade structure. The results that we present are based on analyzing the wind and force field data sets generated by numerical simulations, and allow domain scientists to relate vortex-blade interactions with power output loss in turbines and turbine life expectancy. Our methods have the potential to improve turbine design to save costs related to turbine operation and maintenance.

  1. A feasibility assessment for the application of biogas and wind power in the farm environment as sustainable sources of energy

    NASA Astrophysics Data System (ADS)

    Carbo, Laura C.

    The depletion of energy sources and the ever-increasing energy demand---and consequently price escalation---is a problem that concerns the global population. Despite the concept of energy crisis being widely accepted nowadays, there is a lot of scepticism and misinformation on the possible alternatives to alleviate the environmental and economic impacts of conventional energy generation. Renewable energy technologies are constantly experiencing significant innovation and improvements. This thesis sought to assess the potential of small dairy farms to make an energy shift and identify the practical benefits and possible downfalls of this shift. Wind power and biogas digestion were analysed in this thesis, and a model to assess these technologies at any given farm was developed on VBA. For the case studied in this research both technologies were concluded to be feasible from an economic point of view. Although the initial investment can seem costly, considering the relatively low payback period and the currently available subsidies the economic implications are not an obstacle. The model developed on VBA is applicable to any region, given the right data is put into the programme. Considering the global energy concern, models such as the one developed in this thesis are an appropriate tool to identify potential shifts to greener solutions and prove to users that it can be economically profitable for them as well as environmentally beneficial.

  2. Offshore Wind Energy Market Overview (Presentation)

    SciTech Connect

    Baring-Gould, I.

    2013-07-01

    This presentation describes the current international market conditions regarding offshore wind, including the breakdown of installation costs, how to reduce costs, and the physical siting considerations considered when planning offshore wind construction. The presentation offers several examples of international existing and planned offshore wind farm sites and compares existing international offshore resources with U.S. resources. The presentation covers future offshore wind trends and cites some challenges that the United States must overcome before it will be able to fully develop offshore wind sites.

  3. Mitigating the Acoustic Impacts of Modern Technologies: Acoustic, Health, and Psychosocial Factors Informing Wind Farm Placement

    ERIC Educational Resources Information Center

    Shepherd, Daniel; Billington, Rex

    2011-01-01

    Wind turbine noise is annoying and has been linked to increased levels of psychological distress, stress, difficulty falling asleep, and sleep interruption. For these reasons, there is a need for competently designed noise standards to safeguard community health and well-being. The authors identify key considerations for the development of wind…

  4. The Undercutter Method of Dryland Wheat Farming to Reduce Wind Erosion in Western United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wind erosion is a major problem in the dryland winter wheat (Triticum aestivum L.) - summer fallow production region of the Columbia Plateau in eastern Washington and north-central Oregon. Several locations within the Columbia Plateau have failed to meet federal clean air standards for PM10 emission...

  5. Net energy payback and CO2 emissions from three midwestern wind farms: An update

    USGS Publications Warehouse

    White, S.W.

    2006-01-01

    This paper updates a life-cycle net energy analysis and carbon dioxide emissions analysis of three Midwestern utility-scale wind systems. Both the Energy Payback Ratio (EPR) and CO2 analysis results provide useful data for policy discussions regarding an efficient and low-carbon energy mix. The EPR is the amount of electrical energy produced for the lifetime of the power plant divided by the total amount of energy required to procure and transport the materials, build, operate, and decommission the power plants. The CO2 analysis for each power plant was calculated from the life-cycle energy input data. A previous study also analyzed coal and nuclear fission power plants. At the time of that study, two of the three wind systems had less than a full year of generation data to project the life-cycle energy production. This study updates the analysis of three wind systems with an additional four to eight years of operating data. The EPR for the utility-scale wind systems ranges from a low of 11 for a two-turbine system in Wisconsin to 28 for a 143-turbine system in southwestern Minnesota. The EPR is 11 for coal, 25 for fission with gas centrifuge enriched uranium and 7 for gaseous diffusion enriched uranium. The normalized CO2 emissions, in tonnes of CO2 per GW eh, ranges from 14 to 33 for the wind systems, 974 for coal, and 10 and 34 for nuclear fission using gas centrifuge and gaseous diffusion enriched uranium, respectively. ?? Springer Science+Business Media, LLC 2007.

  6. Assessment by regional modelling of the impact of monopile foundations on the hydrodynamics and sediment transport: case of Courseulles-sur-Mer (France) wind farm

    NASA Astrophysics Data System (ADS)

    Rivier, Aurélie; Bennis, Anne-Claire; Pinon, Grégory; Magar, Vanesa; Gross, Markus

    2015-04-01

    Offshore monopile foundations of wind turbines modify hydrodynamics and sediment transport at local scale and also at regional scale. The aim of this work is to assess these changes and to parametrize them in a regional model. These modifications were previously evaluated using the regional circulation model MARS3D (Lazure and Dumas, 2008) in tests-cases (Rivier et al., 2014) using two approaches: in the first approach, monopiles are explicitly modelled in the mesh as dry cells and in the second approach a sub-grid parametrization which considers the drag force exerted by a monopile on the flow is used. The sub-grid parametrization is improved close to the bed in this paper by adding a drag force term in the momentum equations, source terms in the turbulence model and by increasing the bed shear stress at monopile location. Changes in hydrodynamics regime, especially near-bed, affect sediment transport regime and modifications due to monopiles on sediment dynamics is also investigated using the MARS3D sediment transport module (Le Hir et al., 2011) which solves the advection-diffusion equations. Test-cases are run using hydrodynamical conditions and sediment grain sizes typical from the area located off Courseulles-sur-Mer (Normandy, France) where an offshore wind farm is planned to be built. Velocity, turbulent kinetic energy and bed thickness changes due to the monopile simulated by both approaches are compared to each other and to experimental measurements made in a flume at the University of Caen or to published data (e.g. Roulund et al., 2005; Dargahi,1989). Then the model is applied in a real configuration on an area including the future offshore wind farm of Courseulles-sur-Mer. Four monopiles are represented in the model using both approaches and modifications of the hydrodynamics and sediment transport are assessed along a tidal cycle. Currents increase at the side edge of the monopile and decrease in front of and downstream the monopile. Turbulent kinetic

  7. 2008 Wind Energy Projects, Wind Powering America (Poster)

    SciTech Connect

    Not Available

    2009-01-01

    The Wind Powering America program produces a poster at the end of every calendar year that depicts new U.S. wind energy projects. The 2008 poster includes the following projects: Stetson Wind Farm in Maine; Dutch Hill Wind Farm in New York; Grand Ridge Wind Energy Center in Illinois; Hooper Bay, Alaska; Forestburg, South Dakota; Elbow Creek Wind Project in Texas; Glacier Wind Farm in Montana; Wray, Colorado; Smoky Hills Wind Farm in Kansas; Forbes Park Wind Project in Massachusetts; Spanish Fork, Utah; Goodland Wind Farm in Indiana; and the Tatanka Wind Energy Project on the border of North Dakota and South Dakota.

  8. Heterogeneous Boundary Layers through the Diurnal Cycle: Evaluation of the WRF Wind Farm Parameterization using Scanning Lidar Observations and Wind Turbine Power Measurements during a Range of Stability Conditions

    NASA Astrophysics Data System (ADS)

    Lundquist, J. K.

    2015-12-01

    As wind energy deployment increases, questions arise regarding impacts on local climates and how these impacts evolve with the diurnal cycle of the boundary layer. Satellite observations suggest nocturnal increases of surface temperatures, and measurements of turbine wakes document stronger and more persistent reductions of wind speed and increases in turbulence downwind of turbines during stable conditions. Validations of mesoscale parameterizations of these effects have been constrained to idealized conditions defined by neutrally-stratified conditions and/or limited wind directions and wind speeds, or by comparison to idealized large-eddy simulations. Synthesis of conventional meteorological measurements and unconventional measurements can offer unique insights for validating models over a large heterogeneous domain. The CWEX-13 field experiment provides an extensive dataset for such validation at spatial scales on the order of 10 km in a range of atmospheric stability and wind conditions. CWEX-13 took place within a 300 MW wind farm in central Iowa during summer 2013 and featured strong diurnal cycles. The wind turbines are sited irregularly, creating a heterogenous "canopy". Three profiling lidars, numerous surface flux stations, and a scanning lidar sampled wakes from multiple turbines. Further, the wind farm owner/operator has provided access to turbine power production and wind speed measurement data for model validation, providing ~ 200 measurements of proxies that integrate the wind profile over the rotor disk, from 40 m to 120 m above the surface. Building on previous work that identified optimal physics options, grid configurations, and boundary condition data sets by comparison to lidar wind profile measurements, we execute simulations with the WRF Wind Farm Parameterization for a ten-day period featuring moderate winds and strong diurnal cycles. We evaluate simulations with different modeling choices (e.g., vertical resolution, approaches to

  9. Lidar-based wake tracking for closed-loop wind farm control

    NASA Astrophysics Data System (ADS)

    Raach, Steffen; Schlipf, David; Cheng, Po Wen

    2016-09-01

    This work presents two advancements towards closed-loop wake redirecting of a wind turbine. First, a model-based estimation approach is presented which uses a nacelle-based lidar system facing downwind to obtain information about the wake. A reduced order wake model is described which is then used in the estimation to track the wake. The tracking is demonstrated with lidar measurement data from an offshore campaign and with simulated lidar data from a SOWFA simulation. Second, a controller for closed-loop wake steering is presented. It uses the wake tracking information to set the yaw actuator of the wind turbine to redirect the wake to a desired position. Altogether, this paper aims to present the concept of closed-loop wake redirecting and gives a possible solution to it.

  10. Fostering a Renewable Energy Technology Industry: An InternationalComparison of Wind Industry Policy Support Mechanisms

    SciTech Connect

    Lewis, Joanna; Wiser, Ryan

    2005-11-15

    This article examines the importance of national and sub-national policies in supporting the development of successful global wind turbine manufacturing companies. We explore the motivations behind establishing a local wind power industry, and the paths that different countries have taken to develop indigenous large wind turbine manufacturing industries within their borders. This is done through a cross-country comparison of the policy support mechanisms that have been employed to directly and indirectly promote wind technology manufacturing in twelve countries. We find that in many instances there is a clear relationship between a manufacturer's success in its home country market and its eventual success in the global wind power market. Whether new wind turbine manufacturing entrants are able to succeed will likely depend in part on the utilization of their turbines in their own domestic market, which in turn will be influenced by the annual size and stability of that market. Consequently, policies that support a sizable, stable market for wind power, in conjunction with policies that specifically provide incentives for wind power technology to be manufactured locally, are most likely to result in the establishment of an internationally competitive wind industry.

  11. Off shore wind farms change the benthic pelagic coupling in the Belgian Part of the North Sea

    NASA Astrophysics Data System (ADS)

    Vanaverbeke, Jan; Coates, Delphine; Braeckman, Ulrike; Soetaert, Karline; Moens, Tom

    2016-04-01

    Since Europe enforced renewable energy target figures upon its member states through the implementation of two main European Directives 11 2001/77/EC and 2009/28/EC, the development of offshore wind farms (OWF) has accelerated. Belgium installed OWFs on sandbanks, characterized by permeable sediments, low in organic matter content and a species-poor macrofaunal community with species occurring in low densities. A detailed monitoring campaign in the immediate vicinity of a wind turbine (1-200m), revealed a significant decrease in median grain size and permeability, coinciding with a 6-fold increase in organic matter content. The observed fining of the sediment is explained by an altered benthic-pelagic coupling in the area. The wind turbines are colonized by an abundant fouling community producing high amounts of detritus and faeces, a continuous additional source of organic matter. The changes in sediment composition, and the availability of additional organic matter resulted in drastic increase in macrofaunal densities (from 1390 ind m-2 to 18600 ind m-2), and a change from a species-poor community to a species-rich community dominated by the ecosystem engineer Lanice conchilega. Large densities of L. conchilega, as observed in our samples, are known to trap fine material from the water column, which can result in a further decrease of sediment permeability in the vicinity of the wind turbines. A preliminary experiment, where permeable sediments were subjected to artificial fining, showed a decreased penetration depth of advective water currents and a reduced trapping of diatoms by the sediment in finer sediments. Additionally, sediment community oxygen consumption rates, and efflux of NH4+ from the sediment, measured after a simulated phytoplankton bloom, decreased significantly when sediment permeability was reduced. We hypothesize that the combination of the altered macrofaunal community composition, together with the changes in the physical properties of the

  12. Final Environmental Assessment: F. E. Warren Air Force Base Wind Farm Project Cheyenne, Wyoming

    DTIC Science & Technology

    2004-04-14

    those in a library ( Tipler 1991). The nearest residential developments are located 5,000 feet from the Proposed Action and 4,300 feet from the...and molt patterns of red bats. Bulletin of the Chicago Academy of Sciences 14: 1−7. Tipler , P.A. 1991. Physics for Scientists and Engineers...3rd Edition. Published by P.A. Tipler , 1,167 pp. Usgaard, R.E., D.E. Naugle, R.G. Osborn, and K.F. Higgins. 1997. Effects of wind turbines on

  13. First International Workshop on Grid Simulator Testing of Wind Turbine Drivetrains: Workshop Proceedings

    SciTech Connect

    Gevorgian, V.; Link, H.; McDade, M.; Mander, A.; Fox, J. C.; Rigas, N.

    2013-11-01

    This report summarizes the proceedings of the First International Workshop on Grid Simulator Testing of Wind Turbine Drivetrains, held from June 13 to 14, 2013, at the National Renewable Energy Laboratory's National Wind Technology Center, located south of Boulder, Colorado. The workshop was sponsored by the U.S. Department of Energy and cohosted by the National Renewable Energy Laboratory and Clemson University under ongoing collaboration via a cooperative research and development agreement. The purpose of the workshop was to provide a forum to discuss the research, testing needs, and state-of-the-art apparatuses involved in grid compliance testing of utility-scale wind turbine generators. This includes both dynamometer testing of wind turbine drivetrains ('ground testing') and field testing grid-connected wind turbines. Four sessions followed by discussions in which all attendees of the workshop were encouraged to participate comprised the workshop.

  14. Wind Farm Monitoring at Storm Lake I Wind Power Project -- Equipment Only: Cooperative Research and Development Final Report, CRADA Number CRD-10-369

    SciTech Connect

    Gevorgian, Vahan

    2015-07-09

    Long-term, high-resolution wind turbine and wind power plant output data are important to assess the impact of wind power on grid operations and to derive meaningful statistics for better understanding of the variability of wind power. These data are used for many research and analysis activities consistent with the Wind Program mission.

  15. Assessing bio-physical effects of Offshore Wind Farms on the North Sea pelagic ecosystem using a TRIAXUS ROTV

    NASA Astrophysics Data System (ADS)

    Floeter, Jens; Callies, Ulrich; Dudeck, Tim; Eckhardt, André; Gloe, Dominik; Hufnagl, Marc; Ludewig, Elke; Möller, Klas O.; North, Ryan P.; Pohlmann, Thomas; Riethmüller, Rolf; Temming, Axel; van Beusekom, Justus; Walter, Bettina; Möllmann, Christian

    2015-04-01

    The effects of Offshore Wind Farms (OWFs) on marine ecosystem functioning are largely unknown. OWF foundations may lead to locally increased turbulence levels in the pelagic zone, and as turbines deflect the wind field, the extraction of energy may induce up- and downwelling dipoles in the water column. As a consequence, upwelling cells and locally increased vertical mixing will likely transport nutrients and phytoplankton into the nutrient-depleted surface layer of the stratified water column in summer. Subsequently, locally enhanced primary production could potentially be channelled to higher trophic levels and may lead to an increased habitat quality for demersal & pelagic fish. Here, we present field measurements that allow us to assess the bio-physical effects of OWFs on the North Sea pelagic ecosystem. Data were obtained using a TRIAXUS (a remotely operated towed vehicle, ROTV) during a survey in summer 2014, which included three OWFs located in water depths between 20m and 40m. TRIAXUS is designed to record high-frequency synoptic measurements of biological and physical oceanographic properties. The instrument is equipped with CTD, oxygen, light and fluorescence sensors as well as a Laser Optical Plankton Counter (LOPC) and a Video Plankton Recorder (VPR). Fisheries hydroacoustic and ADCP data were recorded in parallel. Hydrodynamic modelling supported the analysis by backtracking the drift routes of water bodies from which nutrient contents were analysed. To isolate the OWF effects from natural variability in the bio-physical properties of the German Bight, we also analysed spatially and seasonally similar SCANFISH transect data from pre-OWF years (2010, 2011). The survey provided first insights into the potential bio-physical effects of OWFs on the North Sea pelagic ecosystem, e.g., small scale areas of increased mixing, local upwelling and changes in the magnitude of the surface layer with distinct phytoplankton discontinuities.

  16. Comment on Mroczek et al. Evaluation of Quality of Life of Those Living near a Wind Farm. Int. J. Environ. Res. Public Health, 2015, 12, 6066–6083

    PubMed Central

    Shepherd, Daniel

    2017-01-01

    An article published in the International Journal of Environmental Research and Public Health indicated that, far from degrading health, noise from wind turbines may actually be associated with positive health outcomes. Such a finding is counter to that reported elsewhere for general and wind turbine noise. This Commentary sets out to explore alternative explanations of these differences. PMID:28157146

  17. Comment on Mroczek et al. Evaluation of Quality of Life of Those Living near a Wind Farm. Int. J. Environ. Res. Public Health, 2015, 12, 6066-6083.

    PubMed

    Shepherd, Daniel

    2017-02-01

    An article published in the International Journal of Environmental Research and Public Health indicated that, far from degrading health, noise from wind turbines may actually be associated with positive health outcomes. Such a finding is counter to that reported elsewhere for general and wind turbine noise. This Commentary sets out to explore alternative explanations of these differences.

  18. The International Energy Agency`s role in world-wide wind energy development

    SciTech Connect

    Rangi, R.; Ancona, D.

    1997-12-31

    Wind energy is now being deployed world-wide at a rapidly increasing rate and the International Energy Agency (IEA) has a changing role in its growth. IEA was founded in 1974 within the framework of the Organization for Economic Cooperation and Development (OECD) to collaborate on comprehensive international energy programs. IEA membership consists of eighteen parties from sixteen countries and the European Commission. Recently there has been increasing interest in IEA participation from both OECD and non-OECD countries. Non-OECD countries participating in various IEA Agreements include: China, India, Israel, Korea, and Russia. Because of its diverse international makeup, the IEA is viewed as a source of reliable technical and economic information. The World Bank has approached the Executive Committee for Wind Energy R & D, through the IEA Renewable Energy Working Party, to assist in the expansion of wind deployment. In addition, IEA is moving from R & D programs to include tracking of implementation incentives offered by its members.

  19. Estimation of infection of internal parasites in horses from different type of farms.

    PubMed

    Sokół, Rajmund; Raś-Noryńska, Małgorzata; Michalczyk, Maria; Raś, Andrzej; Rapacz-Leonard, Anna; Koziatek, Sylwia

    2015-01-01

    Studies were carried out in year 2014 during the pasture period (from April to October) in Warmia and Mazury Region. Fecal samples were taken from cold- and warmblood horses from individual and agrotouristic farms with the different housing, feeding and pasture- care practices. Total of 512 horses were examined (320 mares, 170 geldings and 22 stallions). In the group of 185 horses from individual farms, 119 animals (64.3%) were infected with gastro-intestinal parasites. Among the 372 horses from agrotouristic farms 169 (51.7%) were infected with parasites. Most of the animals expelled the eggs of Cyathostominae. In some individuals occurred eggs of Strongylus spp., Parascaris equorum, Strongyloides westeri and tapeworm of Anoplocephala. The number of infected horses from agrotouristic farms was lower than from individual farms, probably due to more regular deworming (usually 2 times a year) and bigger care paid to cleaning pastures.

  20. Offshore wind farms as productive sites or ecological traps for gadoid fishes?--impact on growth, condition index and diet composition.

    PubMed

    Reubens, Jan T; Vandendriessche, Sofie; Zenner, Annemie N; Degraer, Steven; Vincx, Magda

    2013-09-01

    With the construction of wind farms all across the North Sea, numerous artificial reefs are created. These windmill artificial reefs (WARs) harbour high abundances of fish species which can be attracted from elsewhere or can be the result of extra production induced by these wind farms. To resolve the attraction-production debate in suddenly altered ecosystems (cf. wind farms), the possible consequences of attraction should be assessed; thereby bearing in mind that ecological traps may arise. In this paper we investigated whether the wind farms in the Belgian part of the North Sea act as ecological traps for pouting and Atlantic cod. Length-at-age, condition and diet composition of fish present at the windmill artificial reefs was compared to local and regional sandy areas. Fish data from the period 2009-2012 were evaluated. Mainly I- and II-group Atlantic cod were present around the WARs; while the 0- and I-group dominated for pouting. For Atlantic cod, no differences in length were observed between sites, indicating that fitness was comparable at the WARs and in sandy areas. No significant differences in condition index were observed for pouting. At the WARs, they were slightly larger and stomach fullness was enhanced compared to the surrounding sandy areas. Also diet differed considerably among the sites. The outcome of the proxies indicate that fitness of pouting was slightly enhanced compared to the surrounding sandy areas. No evidence was obtained supporting the hypothesis that the WARs act as an ecological trap for Atlantic cod and pouting.

  1. Likely effects of construction of Scroby Sands offshore wind farm on a mixed population of harbour Phoca vitulina and grey Halichoerus grypus seals.

    PubMed

    Skeate, Eleanor R; Perrow, Martin R; Gilroy, James J

    2012-04-01

    Scroby Sands offshore wind farm was built close to a haul-out and breeding site for harbour seal, a species of conservation concern. An aerial survey programme conducted during a five-year period spanning wind farm construction, revealed a significant post-construction decline in haul-out counts. Multivariate model selection suggested that the decline was not related to the environmental factors considered, nor did it mirror wider population trends. Although cause and effect could not be unequivocally established, the theoretical basis of hearing in pinnipeds and previous studies suggested that extreme noise (to 257 dB re 1 μ Pa(pp) @ 1m) generated by pile-driving of turbine bases led to displacement of seals. A lack of full recovery of harbour seal during the study was also linked to their sensitivity to vessel activity and/or rapid colonisation of competing grey seal. Any impact of offshore wind farm development upon pinnipeds would be much reduced without pile-driving.

  2. Careers in Wind Energy

    ERIC Educational Resources Information Center

    Liming, Drew; Hamilton, James

    2011-01-01

    As a common form of renewable energy, wind power is generating more than just electricity. It is increasingly generating jobs for workers in many different occupations. Many workers are employed on wind farms: areas where groups of wind turbines produce electricity from wind power. Wind farms are frequently located in the midwestern, western, and…

  3. Repeated mapping of reefs constructed by Sabellaria spinulosa Leuckart 1849 at an offshore wind farm site

    NASA Astrophysics Data System (ADS)

    Pearce, Bryony; Fariñas-Franco, Jose M.; Wilson, Christian; Pitts, Jack; deBurgh, Angela; Somerfield, Paul J.

    2014-07-01

    Sabellaria spinulosa reefs are considered to be sensitive and of high conservation status. This article evaluates the feasibility of using remote sensing technology to delineate S. spinulosa reefs. S. spinulosa reef habitats associated with the Thanet Offshore Windfarm site were mapped using high resolution sidescan sonar (410 kHz) and multibeam echo sounder (<1 m2) data in 2005 (baseline), 2007 (pre-construction baseline) and 2012 (post-construction). The S. spinulosa reefs were identified in the acoustic data as areas of distinct irregular texturing. Maps created using acoustic data were validated using quantitative measures of reef quality, namely tube density (as a proxy for the density of live S. spinulosa), percentage cover of S. spinulosa structures (both living and dead) and associated macrofauna derived from seabed images taken across the development site. Statistically significant differences were observed in all physical measures of S. spinulosa as well the number (S) and diversity (H') of associated species, derived from seabed images classified according to the presence or absence of reef, validating the use of high resolution sidescan sonar to map these important biogenic habitats. High precision mapping in the early stages allowed for the micro-siting of wind turbines in a way that caused minimal damage to S. spinulosa reefs during construction. These habitats have since recovered and expanded in extent. The surveys undertaken at the Thanet Offshore Windfarm site demonstrate the importance of repeat mapping for this emerging industry, allowing habitat enhancement to be attributed to the development whilst preventing background habitat degradation from being wrongly attributed to the development.

  4. Direct Detection Doppler Lidar Wind Measurements Obtained During the 2002 International H2O Project (IHOP)

    NASA Technical Reports Server (NTRS)

    Gentry, Bruce; Li, Steven; Chen, Huai-Lin; Comer, Joseph; Mathur, Savyasachee; Bobler, Jeremy

    2005-01-01

    The Goddard Lidar Observatory for Winds (GLOW) is a mobile Doppler lidar system that uses direct detection techniques for profiling winds in the troposphere and lower stratosphere. In May and June of 2002 GLOW was deployed to the Southern Great Plains of the US to participate in the International H2O Project (IHOP). GLOW was located at the Homestead profiling site in the Oklahoma panhandle about 15 km east of the SPOL radar. Several other Goddard lidars, the Scanning Raman Lidar (SRL) and HARLIE, as well as radars and passive instruments were permanently operated from the Homestead site during the IHOP campaign providing a unique cluster of observations. During the IHOP observation period (May 14, 2002 to June 25, 2002) over 240 hours of wind profile measurements were obtained with GLOW. In this paper we will describe the GLOW instrument as it was configured for the IHOP campaign and we will present examples of wind profiles obtained.

  5. Titan's rotation reveals an internal ocean and changing zonal winds

    USGS Publications Warehouse

    Lorenz, R.D.; Stiles, B.W.; Kirk, R.L.; Allison, M.D.; Del Marmo, P.P.; Iess, L.; Lunine, J.I.; Ostro, S.J.; Hensley, S.

    2008-01-01

    Cassini radar observations of Saturn's moon Titan over several years show that its rotational period is changing and is different from its orbital period. The present-day rotation period difference from synchronous spin leads to a shift of ???0.36?? per year in apparent longitude and is consistent with seasonal exchange of angular momentum between the surface and Titan's dense superrotating atmosphere, but only if Titan's crust is decoupled from the core by an internal water ocean like that on Europa.

  6. Co-location of passive gear fisheries in offshore wind farms in the German EEZ of the North Sea: A first socio-economic scoping.

    PubMed

    Stelzenmüller, V; Diekmann, R; Bastardie, F; Schulze, T; Berkenhagen, J; Kloppmann, M; Krause, G; Pogoda, B; Buck, B H; Kraus, G

    2016-12-01

    Worldwide the renewable energy sector is expanding at sea to address increasing demands. Recently the race for space in heavily used areas such as the North Sea triggered the proposal of co-locating other activities such as aquaculture or fisheries with passive gears in offshore wind farms (OWFs). Our interdisciplinary approach combined a quantification of spatial overlap of activities by using Vessel Monitoring System and logbook data with a stakeholder consultation to conclude and verify on the actual feasibility of co-location. In the German Exclusive Economic Zone (EEZ) of the North Sea up to 90% of Danish and 40% of German annual gillnet fleet landings of plaice overlapped with areas where OWFs are developed. Our results indicated further that the international gillnet fishery could lose up to 50% in landings within the North Sea German EEZ when OWF areas are closed entirely for fisheries. No spatial overlap was found for UK potters targeting brown crab in the German EEZ. We further identified a number of key issues and obstacles that to date hinder an actual implementation of co-location as a measure in the marine spatial planning process: defining the legal base; implementation of safety regulations; delineation of minimum requirements for fishing vessels such as capacities, quotas, technical equipment; implementation of a licensing process; and scoping for financial subsidies to set up business. The stakeholder consultation verified the scientific findings and highlighted that all those points need to be addressed in a planning process. In the German EEZ we have shown that the socio-economic importance of spatial overlap varies within planning boundaries. Therefore we recommend an interdisciplinary bottom-up approach when scoping for suitable areas of co-location. Hence, an informed marine spatial planning process requires comprehensive and spatial explicit socio-economic viability studies factoring in also ecological effects of OWFs on target species.

  7. Titan's rotation reveals an internal ocean and changing zonal winds.

    PubMed

    Lorenz, Ralph D; Stiles, Bryan W; Kirk, Randolph L; Allison, Michael D; Del Marmo, Paolo Persi; Iess, Luciano; Lunine, Jonathan I; Ostro, Steven J; Hensley, Scott

    2008-03-21

    Cassini radar observations of Saturn's moon Titan over several years show that its rotational period is changing and is different from its orbital period. The present-day rotation period difference from synchronous spin leads to a shift of approximately 0.36 degrees per year in apparent longitude and is consistent with seasonal exchange of angular momentum between the surface and Titan's dense superrotating atmosphere, but only if Titan's crust is decoupled from the core by an internal water ocean like that on Europa.

  8. Data Farming and the Exploration of Inter-Agency, Inter-Disciplinary, and International "What If?" Questions

    NASA Technical Reports Server (NTRS)

    Anderson, Steve; Horne, Gary; Meyer, Ted; Triola, Larry

    2012-01-01

    Data farming uses simulation modeling, high performance computing, and analysis to examine questions of interest with large possibility spaces.This methodology allows for the examination of whole landscapes of potential outcomes and provides the capability of executing enough experiments so that outlets might be captured and examined for insights. This capability may be quite informative when used to examine the plethora of "What if?" questions that result when examining potential scenarios that our forces may face in the uncertain world of the future. Many of theses scenarios most certainly will be challenging and solutions may depend on interagency and international collaboration as well as the need for inter-disciplinary scientific inquiry preceding these events. In this paper, we describe data farming and illustrate it in the context of application to questions inherent to military decision-making as we consider alternate future scenarios.

  9. 14th Annual international meeting of wind turbine test stations: Proceedings

    SciTech Connect

    Not Available

    1994-11-01

    These proceedings are of the 14th Annual International Meeting of Test Stations. As the original charter states these meetings are intended to be an international forum for sharing wind turbine testing experiences. By sharing their experiences they can improve testing skills and techniques. As with all new industries the quality of the products is marked by how well they learn from their experiences and incorporate this learning into the next generation of products. The test station`s role in this process is to provide accurate information to the companies they serve. This information is used by designers to conform and improve their designs. It is also used by certification agencies for confirming the quality of these designs. By sharing of experiences they are able to accomplished these goals, serve these customers better and ultimately improve the international wind energy industry.

  10. Farming Systems Design 2007: An International Symposium on Methodologies for Integrated Analysis of Farm Production Systems Book 1: Field-Farm Scale Design and Improvement; Book 2: Farm-Regional Scale Design and Improvement

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is a growing interest in agricultural systems that serve multiple purposes, in the context of driving factors such as climate change, liberalization, environmental concerns, and changing agricultural institutions. Farming systems face a continuous pressure to innovate. The drivers also strongl...

  11. Connecting wind-driven upwelling and offshore stratification to nearshore internal bores and oxygen variability

    NASA Astrophysics Data System (ADS)

    Walter, Ryan K.; Woodson, C. Brock; Leary, Paul R.; Monismith, Stephen G.

    2014-06-01

    This study utilizes field observations in southern Monterey Bay, CA, to examine how regional-scale upwelling and changing offshore (shelf) conditions influence nearshore internal bores. We show that the low-frequency wind forcing (e.g., upwelling/relaxation time scales) modifies the offshore stratification and thermocline depth. This in turn alters the strength and structure of observed internal bores in the nearshore. An internal bore strength index is defined using the high-pass filtered potential energy density anomaly in the nearshore. During weak upwelling favorable conditions and wind relaxations, the offshore thermocline deepens. In this case, both the amplitude of the offshore internal tide and the strength of the nearshore internal bores increase. In contrast, during strong upwelling conditions, the offshore thermocline shoals toward the surface, resulting in a decrease in the offshore internal tide amplitude. As a result, cold water accumulates in the nearshore (nearshore pooling), and the internal bore strength index decreases. Empirical orthogonal functions are utilized to support the claim that the bore events contribute to the majority of the variance in cross-shelf exchange and transport in the nearshore. Observed individual bores can drive shock-like drops in dissolved oxygen (DO) with rapid onset times, while extended upwelling periods with reduced bore activity produce longer duration, low DO events.

  12. The effects of farm management practices on liver fluke prevalence and the current internal parasite control measures employed on Irish dairy farms.

    PubMed

    Selemetas, Nikolaos; Phelan, Paul; O'Kiely, Padraig; de Waal, Theo

    2015-01-30

    Fasciolosis caused by Fasciola hepatica is responsible for major production losses in cattle farms. The objectives of this study were to assess the effect of farm management practices on liver fluke prevalence on Irish dairy farms and to document the current control measures against parasitic diseases. In total, 369 dairy farms throughout Ireland were sampled from October to December 2013, each providing a single bulk tank milk (BTM) sample for liver fluke antibody-detection ELISA testing and completing a questionnaire on their farm management. The analysis of samples showed that cows on 78% (n=288) of dairy farms had been exposed to liver fluke. There was a difference (P<0.05) between farms where cows were positive or negative for liver fluke antibodies in (a) the total number of adult dairy cows in herds, (b) the number of adult dairy cows contributing to BTM samples, and (c) the size of the total area of grassland, with positive farms having larger numbers in each case. There was no difference (P>0.05) between positive and negative farms in (a) the grazing of dry cows together with replacement cows, (b) whether or not grazed grassland was mowed for conservation, (c) the type of drinking water provision system, (d) spreading of cattle manure on grassland or (e) for grazing season length (GSL; mean=262.5 days). Also, there were differences (P<0.001) between drainage statuses for GSL with farms on good drainage having longer GSL than moderately drained farms. The GSL for dairy cows on farms with good drainage was 11 days longer than for those with moderate drainage (P<0.001). The percentage of farmers that used an active ingredient during the non-lactating period against liver fluke, gastrointestinal nematodes, lungworm, and rumen fluke was 96%, 85%, 77% and 90%, respectively. Albendazole was the most frequently used active ingredient for treatment against gastrointestinal nematodes (57%), liver fluke (40%) and lungworm (47%), respectively. There was a difference

  13. Wind Farms and Radar

    DTIC Science & Technology

    2008-01-01

    capabilities. The challenge is to evolve the current system, and to design future sytems to effectively distinguish and mitigate a source of clutter...not transponding) but also might also come close to solving the interference problem for transponding aircraft. 12 DISTRIBUTION LIST Assistant ...Secretary of the Navy (Research, Development & Acquisition) 1000 Navy Pentagon Washington, DC 20350-1000 Assistant Deputy Administrator for

  14. Stratigraphy of a proposed wind farm site southeast of Block Island: Utilization of borehole samples, downhole logging, and seismic profiles

    NASA Astrophysics Data System (ADS)

    Sheldon, Dane P. H.

    Seismic stratigraphy, sedimentology, lithostratigraphy, downhole geophysical logging, mineralogy, and palynology were used to study and interpret the upper 70 meters of the inner continental shelf sediments within a proposed wind farm site located approximately two to three nautical miles to the southeast of Block Island, Rhode Island. Core samples and downhole logging collected from borings drilled for geotechnical purposes at proposed wind turbine sites along with seismic surveys in the surrounding area provide the data for this study. Cretaceous coastal plain sediments that consist of non-marine to marine sand, silt, and clay are found overlying bedrock at a contact depth beyond the sampling depth of this study. The upper Cretaceous sediments sampled in borings are correlated with the Magothy/Matawan formations described regionally from New Jersey to Nantucket. An unconformity formed through sub-aerial, fluvial, marine, and glacial erosion marks the upper strata of the Cretaceous sediments separating them from the overlying deposits. The majority of Quaternary deposits overlying the unconformity represent the advance, pulsing, and retreat of the Laurentide ice sheet that reached its southern terminus in the area of Block Island approximately 25,000 to 21,000 years before present. The sequence consists of a basal glacial till overlain by sediments deposited by meltwater environments ranging from deltaic to proglacial lakefloor. A late Pleistocene to early Holocene unconformity marks the top of the glacial sequence and was formed after glacial retreat through fluvial and subaerial erosion/deposition. Overlying the glacial sequence are sediments deposited during the late Pleistocene and Holocene consisting of interbedded gravel, sand, silt, and clay. Sampling of these sediments was limited and surficial reflectors in seismic profiles were masked due to a hard bottom return. However, two depositional periods are interpreted as representing fluvial and estuarine

  15. FOREWORD: 6th International Conference on Pumps and Fans with Compressors and Wind Turbines (ICPF2013)

    NASA Astrophysics Data System (ADS)

    Wu, Yulin; Wang, Zhengwei; Yuan, Shouqi; Shi, Weidong; Liu, Shuhong; Luo, Xingqi; Wang, Fujun

    2013-12-01

    The 6th International Conference on Pumps and Fans with Compressors and Wind Turbines (ICPF 2013) was held in Beijing, China, 19-22 September 2013, which was jointly organized by Tsinghua University and Jiangsu University. The co-organizers were Zhejiang University, Zhejiang Sci-Tech University, The State Key Laboratory of Hydroscience and Engineering, The State Key Laboratory of Automotive Safety and Energy and Beijing International Science and Technology Cooperation Base for CO2 Utilization and Reduction. The sponsor of the conference was Concepts NREC. The First International Conference on Pumps and Systems (May 1992), the Second International Conference on Pumps and Fans (October 1995), the Third International Conference on Pumps and Fans (October 1998), and the Fourth International Conference on Pumps and Fans (26-29 August 2002) were all held in Beijing and were organized by the late famous Chinese professor on fluid machinery and engineering, Professor Zuyan Mei of Tsinghua University. The conference was interrupted by the death of Professor Mei in 2003. In order to commemorate Professor Mei, the organizing committee of ICPF decided to continue organizing the conference series. The Fifth Conference on Pumps and Systems (2010 ICPF) took place in Hangzhou, Zhejiang Province, China, 18-21 October 2010, and it was jointly organized by Zhejiang University and Tsinghua University. With the development of renewable energy and new energy in China and in the world, some small types of compressor and some types of pump, as well as wind turbines are developing very fast; therefore the ICPF2013 conference included compressors and wind turbines. The theme of the conference was the application of renewable energy of pumps, compressors, fans and blowers. The content of the conference was the basic study, design and experimental study of compressors, fans, blowers and pumps; the CFD application on pumps and fans, their transient behavior, unsteady flows and multi-phase flow

  16. Voltage Distribution of Internal Windings of Pole-Mounted Distribution Transformer by Lightning Surge and Measures for Voltage Reduction

    NASA Astrophysics Data System (ADS)

    Honda, Hideki; Asakawa, Akira; Yokoyama, Shigeru

    When steep lightning surge enters a pole-mounted distribution transformer, the voltage distribution of the internal windings is unbalanced. It is known that a layer-to-layer short or a turn-to-turn short occurs where the voltage distribution of windings is high. In this paper, the voltage distribution of the windings was measured at the primary and secondary sides of the transformer using a testing transformer. The point of the windings where the highest voltage occurred was clarified. At the primary windings, large voltage occurs at the layer nearest the primary bushing, and the possibility of breakdown at this point is high. By field test using several types of surge arrestor, it is found that the lower the operating voltage of the surge arrestor installed in the primary side, the lower the voltage occurring at the primary windings. At the secondary windings, large voltage occurs at the layer closer to the neutral terminal, and the possibility of breakdown at this point is high. The lower the operating voltage of the surge arrestor installed in the primary side, the lower the voltage occurring at the secondary windings, too. Adding the surge arrestor in the secondary side, although effectively reduce line-to-line voltage, does not effectively reduce the voltage of the secondary windings.

  17. [Suspension-sedimentation of sediment and release amount of internal load in Lake Taihu affected by wind].

    PubMed

    Pang, Yong; Yan, Run-run; Yu, Zhong-bo; Li, Yi-ping; Li, Rui-ling

    2008-09-01

    The water quality in Meiliang Bay of the Taihu Lake was totally tested five times in the four seasons. The suspension samples were obtained by using a sediment trap. The sediment settling flux and resuspended flux were calculated according to the observation data by using Gansith formula, and the relationships between these fluxes and wind speeds were established. Seven experiments were conducted in Laboratory for hydrostatic settling behavior of suspended matter affected by different wind speeds in Lake Taihu. The hydrostatic settling fluxes of suspended matter were calculated and the relationships between the fluxes and suspended matter concentrations were established. Base on these works, the suspension-sedimentation process was decomposed and generalized according to the critical wind speed of 3.7 m/s. Daily sediment resuspended amount and settling amount of the year 2005 was calculated and annual average release amount of internal load in Lake Taihu was estimated using the wind data of nearly 10 years. The results indicate that daily release amount of internal load in Lake Taihu significantly influenced by wind and have the same trend of change with wind, while the release amount of different nutrients in the same condition are different. The Lake Taihu has an annual average release amount of internal load with COD 49,600 t, TN 7773.0 t and TP 275.5 t, of which summer has the markedly highest release amount than other seasons.

  18. IEA-Task 31 WAKEBENCH: Towards a protocol for wind farm flow model evaluation. Part 1: Flow-over-terrain models

    NASA Astrophysics Data System (ADS)

    Sanz Rodrigo, Javier; Gancarski, Pawel; Chavez Arroyo, Roberto; Moriarty, Patrick; Chuchfield, Matthew; Naughton, Jonathan W.; Hansen, Kurt S.; Machefaux, Ewan; Koblitz, Tilman; Maguire, Eoghan; Castellani, Francesco; Terzi, Ludovico; Breton, Simon-Philippe; Ueda, Yuko; Prospathopoulos, John; Oxley, Gregory S.; Peralta, Carlos; Zhang, Xiadong; Witha, Björn

    2014-06-01

    The IEA Task 31 Wakebench is setting up a framework for the evaluation of wind farm flow models operating at microscale level. The framework consists on a model evaluation protocol integrated on a web-based portal for model benchmarking (www.windbench.net). This paper provides an overview of the building-block validation approach applied to flow-over-terrain models, including best practices for the benchmarking and data processing procedures for the analysis and qualification of validation datasets from wind resource assessment campaigns. A hierarchy of test cases has been proposed for flow-over-terrain model evaluation, from Monin- Obukhov similarity theory for verification of surface-layer properties, to the Leipzig profile for the near-neutral atmospheric boundary layer, to flow over isolated hills (Askervein and Bolund) to flow over mountaneous complex terrain (Alaiz). A summary of results from the first benchmarks are used to illustrate the model evaluation protocol applied to flow-over-terrain modeling in neutral conditions.

  19. Environmental impact of wind energy

    NASA Astrophysics Data System (ADS)

    Mann, J.; Teilmann, J.

    2013-09-01

    One purpose of wind turbines is to provide pollution-free electric power at a reasonable price in an environmentally sound way. In this focus issue the latest research on the environmental impact of wind farms is presented. Offshore wind farms affect the marine fauna in both positive and negative ways. For example, some farms are safe havens for porpoises while other farms show fewer harbor porpoises even after ten years. Atmospheric computer experiments are carried out to investigate the possible impact and resource of future massive installations of wind turbines. The following questions are treated. What is the global capacity for energy production by the wind? Will the added turbulence and reduced wind speeds generated by massive wind farms cool or heat the surface? Can wind farms affect precipitation? It is also shown through life-cycle analysis how wind energy can reduce the atmospheric emission of eight air pollutants. Finally, noise generation and its impact on humans are studied.

  20. Effects of internal loading on phosphorus distribution in the Taihu Lake driven by wind waves and lake currents.

    PubMed

    Huang, Lei; Fang, Hongwei; He, Guojian; Jiang, Helong; Wang, Changhui

    2016-12-01

    Wind-driven sediment resuspension exerts significant effects on the P behavior in shallow lake ecosystems. In this study, a comprehensive dynamic phosphorus (P) model that integrates hydrodynamic, wind wave and sediment transport is proposed to assess the importance of internal P cycling due to sediment resuspension on water column P levels. The primary contribution of the model is detailed modeling and rigorous coupling of sediment and P dynamics. The proposed model is applied to predict the P behavior in the shallow Taihu Lake, which is the third largest lake in China, and quantitatively estimate the effects of wind waves and lake currents on P release and distribution. Both the prevailing southeast winds in summer and northwest winds in winter are applied for the simulation, and different wind speeds of 5 m/s and 10 m/s are also considered. Results show that sediment resuspension and the resulting P release have a dominant effect on P levels in Taihu Lake, and likely similar shallow lakes. Wind-driven waves at higher wind speeds significantly enhance sediment resuspension and suspended sediment concentration (SSC). Total P concentration in the water column is also increased but not in proportion to the SSC. The different lake circulations resulting from the different prevailing wind directions also affect the distribution of suspended sediment and P around the lake ultimately influencing where eutrophication is likely to occur. The proposed model demonstrates that internal cycling in the lake is a dominant factor in the lake P and must be considered when trying to manage water quality in this and similar lakes. The model is used to demonstrate the potential effectiveness of remediation of an area where historical releases have led to P accumulation on overall lake quality.

  1. Preliminary Observing System Simulation Experiments for Doppler Wind Lidars Deployed on the International Space Station

    NASA Technical Reports Server (NTRS)

    Kemp, E.; Jacob, J.; Rosenberg, R.; Jusem, J. C.; Emmitt, G. D.; Wood, S.; Greco, L. P.; Riishojgaard, L. P.; Masutani, M.; Ma, Z.; Tucker, S.; Atlas, R.; Bucci, L.; Hardesty, M.

    2013-01-01

    NASA Goddard Space Flight Center's Software Systems Support Office (SSSO) is participating in a multi-agency study of the impact of assimilating Doppler wind lidar observations on numerical weather prediction. Funded by NASA's Earth Science Technology Office, SSSO has worked with Simpson Weather Associates to produce time series of synthetic lidar observations mimicking the OAWL and WISSCR lidar instruments deployed on the International Space Station. In addition, SSSO has worked to assimilate a portion of these observations those drawn from the NASA fvGCM Nature Run into the NASA GEOS-DAS global weather prediction system in a series of Observing System Simulation Experiments (OSSEs). These OSSEs will complement parallel OSSEs prepared by the Joint Center for Satellite Data Assimilation and by NOAA's Atlantic Oceanographic and Meteorological Laboratory. In this talk, we will describe our procedure and provide available OSSE results.

  2. Carbon Farming as a Carbon Negative Technology

    NASA Astrophysics Data System (ADS)

    Anderson, C.; Laird, D.; Hayes, D. J.

    2015-12-01

    Carbon farms have a pivotal role in national and international efforts to mitigate and adapt to climate change. A carbon farm in its broadest sense is one that reduces greenhouse gas (GHG) emissions or captures and holds carbon in vegetation and soils. Their capacity to remove carbon from the air and store it safely and permanently, while providing additional human and ecosystem benefits, means they could contribute significantly to national efforts to stabilize or reduce GHGs. We examine carbon farms in the context of corn and soybean production agriculture. We illustrate, using Iowa data but with relevance across United States corn and soybean production, the potential for carbon farms to reduce human GHG emissions and sequester carbon permanently at a rate that has meaningful impact on global greenhouse gas concentration. Carbon has been viewed as a next generation cash crop in Iowa for over a decade. The carbon farm perspective, however, goes beyond carbon as cash crop to make carbon the center of an entire farm enterprise. The transformation is possible through slight adjustment crop practices mixed with advances in technology to sequester carbon through biochar. We examine carbon balance of Iowa agriculture given only the combination of slight reduction in fertilizer and sequestration by biochar. We find the following. Iowa carbon farms could turn Iowa agriculture into a carbon sink. The estimated range of GHG reduction by statewide implementation of carbon farms is 19.46 to 90.27 MMt CO2-equivalent (CO2-e), while the current agricultural CO2-e emission estimate is 35.38 MMt CO2-e. Iowa carbon farm GHG reduction would exceed Iowa GHG reduction by wind energy (8.7 MMt CO2-e) and could exceed combined reductions from wind energy and corn grain ethanol (10.7 MMt CO2-e; 19.4 MMt CO2-e combined). In fact, Iowa carbon farms alone could exceed GHG reduction from national corn grain ethanol production (39.6 MMt CO2-e). A carbon price accessible to agricultural

  3. Residency, site fidelity and habitat use of Atlantic cod (Gadus morhua) at an offshore wind farm using acoustic telemetry.

    PubMed

    Reubens, Jan T; Pasotti, Francesca; Degraer, Steven; Vincx, Magda

    2013-09-01

    Because offshore wind energy development is fast growing in Europe it is important to investigate the changes in the marine environment and how these may influence local biodiversity and ecosystem functioning. One of the species affected by these ecosystem changes is Atlantic cod (Gadus morhua), a heavily exploited, commercially important fish species. In this research we investigated the residency, site fidelity and habitat use of Atlantic cod on a temporal scale at windmill artificial reefs in the Belgian part of the North Sea. Acoustic telemetry was used and the Vemco VR2W position system was deployed to quantify the movement behaviour. In total, 22 Atlantic cod were tagged and monitored for up to one year. Many fish were present near the artificial reefs during summer and autumn, and demonstrated strong residency and high individual detection rates. When present within the study area, Atlantic cod also showed distinct habitat selectivity. We identified aggregation near the artificial hard substrates of the wind turbines. In addition, a clear seasonal pattern in presence was observed. The high number of fish present in summer and autumn alternated with a period of very low densities during the winter period.

  4. Global Wind Map

    ERIC Educational Resources Information Center

    Journal of College Science Teaching, 2005

    2005-01-01

    This brief article describes a new global wind-power map that has quantified global wind power and may help planners place turbines in locations that can maximize power from the winds and provide widely available low-cost energy. The researchers report that their study can assist in locating wind farms in regions known for strong and consistent…

  5. Analysis of Variability and Uncertainty in Wind Power Forecasting: An International Comparison (Presentation)

    SciTech Connect

    Zhang, J.; Hodge, B.; Miettinen, J.; Holttinen, H.; Gomez-Lozaro, E.; Cutululis, N.; Litong-Palima, M.; Sorensen, P.; Lovholm, A.; Berge, E.; Dobschinski, J.

    2013-10-01

    This presentation summarizes the work to investigate the uncertainty in wind forecasting at different times of year and compare wind forecast errors in different power systems using large-scale wind power prediction data from six countries: the United States, Finland, Spain, Denmark, Norway, and Germany.

  6. Wind-Mediated Spread of Low-Pathogenic Avian Influenza Virus into the Environment during Outbreaks at Commercial Poultry Farms.

    PubMed

    Jonges, Marcel; van Leuken, Jeroen; Wouters, Inge; Koch, Guus; Meijer, Adam; Koopmans, Marion

    2015-01-01

    Avian influenza virus-infected poultry can release a large amount of virus-contaminated droppings that serve as sources of infection for susceptible birds. Much research so far has focused on virus spread within flocks. However, as fecal material or manure is a major constituent of airborne poultry dust, virus-contaminated particulate matter from infected flocks may be dispersed into the environment. We collected samples of suspended particulate matter, or the inhalable dust fraction, inside, upwind and downwind of buildings holding poultry infected with low-pathogenic avian influenza virus, and tested them for the presence of endotoxins and influenza virus to characterize the potential impact of airborne influenza virus transmission during outbreaks at commercial poultry farms. Influenza viruses were detected by RT-PCR in filter-rinse fluids collected up to 60 meters downwind from the barns, but virus isolation did not yield any isolates. Viral loads in the air samples were low and beyond the limit of RT-PCR quantification except for one in-barn measurement showing a virus concentration of 8.48 x 10(4) genome copies/m(3). Air samples taken outside poultry barns had endotoxin concentrations of ~50 EU/m(3) that declined with increasing distance from the barn. Atmospheric dispersion modeling of particulate matter, using location-specific meteorological data for the sampling days, demonstrated a positive correlation between endotoxin measurements and modeled particulate matter concentrations, with an R(2) varying from 0.59 to 0.88. Our data suggest that areas at high risk for human or animal exposure to airborne influenza viruses can be modeled during an outbreak to allow directed interventions following targeted surveillance.

  7. Tropospheric Wind Profiles Obtained with the GLOW Molecular Doppler Lidar during the 2002 International H2O Project

    NASA Technical Reports Server (NTRS)

    Gentry, Bruce M.; Chen, Huailin; Li, Steven X.; Mathur, Savy Asachee; Dobler, Jeremy; Hasselbrack, William

    2003-01-01

    The Goddard Lidar Observatory for Winds (GLOW) is a mobile direct detection Doppler lidar system hich uses the double edge technique to measure the Doppler shift of the molecular backscattered laser signal at a wavelength of 355 nm. In the spring of 2002 GLOW was deployed to the western Oklahoma profiling site (36 deg 33.500 min N, 100 deg 36.371 min W) to participate in the International H2O Project (MOP). During the MOP campaign over 240 hours of wind profiles were obtained with the GLOW lidar in support of a variety of scientific investigations.

  8. Tropospheric Wind Profiles Obtained with the GLOW Molecular Doppler Lidar during the 2002 International H2O Project

    NASA Technical Reports Server (NTRS)

    Gentry, Bruce M.; Chen, Huai-Lin; Li, Steven X.; Mathur, S.; Dobler, Jeremy; Hasselbrack, William

    2003-01-01

    The Goddard Lidar Observatory for Winds (GLOW) is a mobile direct detection Doppler lidar system which uses the double edge technique to measure the Doppler shift of the molecular backscattered laser signal at a wavelength of 355 nm. In the spring of 2002 GLOW was deployed to the western Oklahoma profiling site (36 deg 33.500 min N, 100 deg 36.371 min W) to participate in the International H2O Project (IHOP). During the IHOP campaign over 240 hours of wind profiles were obtained with the GLOW lidar in support of a variety of scientific investigations.

  9. 75 FR 47301 - Cedro Hill Wind LLC; Butler Ridge Wind Energy Center, LLC; High Majestic Wind Energy Center, LLC...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-05

    ...; EG10-36-000; EG10-37-000; EG10-38-000] Cedro Hill Wind LLC; Butler Ridge Wind Energy Center, LLC; High Majestic Wind Energy Center, LLC; Wessington Wind Energy Center, LLC; Juniper Canyon Wind Power LLC; Loraine Windpark Project, LLC; White Oak Energy LLC; Meadow Lake Wind Farm III LLC; Meadow Lake Wind...

  10. The gravitational signature of internal flows in giant planets: Comparing the thermal wind approach with barotropic potential-surface methods

    NASA Astrophysics Data System (ADS)

    Kaspi, Y.; Davighi, J. E.; Galanti, E.; Hubbard, W. B.

    2016-09-01

    The upcoming Juno and Cassini gravity measurements of Jupiter and Saturn, respectively, will allow probing the internal dynamics of these planets through accurate analysis of their gravity spectra. To date, two general approaches have been suggested for relating the flow velocities and gravity fields. In the first, barotropic potential surface models, which naturally take into account the oblateness of the planet, are used to calculate the gravity field. However, barotropicity restricts the flows to be constant along cylinders parallel to the rotation axis. The second approach, calculated in the reference frame of the rotating planet, assumes that due to the large scale and rapid rotation of these planets, the winds are to leading order in geostrophic balance. Therefore, thermal wind balance relates the wind shear to the density gradients. While this approach can take into account any internal flow structure, it is limited to only calculating the dynamical gravity contributions, and has traditionally assumed spherical symmetry. This study comes to relate the two approaches both from a theoretical perspective, showing that they are analytically identical in the barotropic limit, and numerically, through systematically comparing the different model solutions for the gravity harmonics. For the barotropic potential surface models we employ two independent solution methods - the potential-theory and Maclaurin spheroid methods. We find that despite the sphericity assumption, in the barotropic limit the thermal wind solutions match well the barotropic oblate potential-surface solutions.

  11. Sowing the Seeds for a Bountiful Harvest: Shaping the Rules and Creating the Tools for Wisconsin's Next Generation of Wind Farms

    SciTech Connect

    Vickerman, Michael Jay

    2012-03-29

    Project objectives