Effects of wind turbine dimensions on the collision risk of raptors: A simulation approach based on flight height distributions

Wind energy is one of the fastest growing renewable energy sources in the United States and has the potential to reduce the use of traditional nonrenewable energy. However, there is concern for potential short- and long-term influences on wildlife populations, such as bird collisions with turbine blades, habitat loss, habitat fragmentation, and habitat avoidance. Bird flight heights are indicative of collision risks, but knowledge of their distributions is limited. Our goal was to examine the diurnal flight heights of bird species to assess which are at greatest risk of collision with wind turbine blades. During October 2008–August 2009, we estimated the flight heights of 66 bird species at a planned wind energy facility on the southern Great Plains. Flight heights were estimated by measuring angle of incline with a clinometer and ground distance with a laser rangefinder. Previous work has been limited to flight height measurements categorized to site-specific rotor swept zone (RSZ) specifications that has resulted in limited applicability to other wind turbine RSZ specifications. Our research is distinctive because it provides more resolution in flight height estimates than those categorized into bins and allows application to wind turbines with different RSZs. We found that the flight heights of six bird species varied among seasons, indicating their risk of collision changed throughout the year. Observations indicated that the average flight heights of 28 bird species were within the potential RSZ (32–124 m above ground level) at our study site and that two species exhibited mean flight heights above the RSZ. Fifteen of those species were wetland-associated species, 7 were raptor or vulture species, and 6 were listed as species of greatest conservation need by Texas Parks and Wildlife Department. We observed 14 bird species (1 vulture, 2 raptors, 7 wetland-associated species, and 4 passerines or other species) with greater than 25% of their observed flight heights within the RSZ. Our results indicate that raptors and wetland-associated species are the avian groups at greatest risk of collision with wind turbines due to their diurnal flight heights. However, the resolution of our data will allow assessment of which bird species are at greatest risk of collision for various wind turbine specifications. This information can help guide site assessment and placement for wind energy facilities across the southern Great Plains and help mitigate potential collision impacts on bird species.

The risk posed by offshore wind farms to seabirds through collisions with turbine blades is greatly influenced by species-specific flight behaviour. Bird-borne telemetry devices may provide improved measurement of aspects of bird behaviour, notably individual and behaviour specific flight heights. However, use of data from devices that use the GPS or barometric altimeters in the gathering of flight height data is nevertheless constrained by a current lack of understanding of the error and calibration of these methods. Uncertainty remains regarding the degree to which errors associated with these methods can affect recorded flight heights, which may in turn have a significant influence on estimates of collision risk produced by Collision Risk Models (CRMs), which incorporate flight height distribution as an input. Using GPS/barometric altimeter tagged Lesser Black-backed Gulls Larus fuscus from two breeding colonies in the UK, we examine comparative flight heights produced by these devices, and their associated errors. We present a novel method of calibrating barometric altimeters using behaviour characterised from GPS data and open-source modelled atmospheric pressure. We examine the magnitude of difference between offshore flight heights produced from GPS and altimeters, comparing these measurements across sampling schedules, colonies, and years. We found flight heights produced from altimeter data to be significantly, although not consistently, higher than those produced from GPS data. This relationship was sustained across differing sampling schedules of five minutes and of 10 s, and between study colonies. We found the magnitude of difference between GPS and altimeter derived flight heights to also vary between individuals, potentially related to the robustness of calibration factors used. Collision estimates for theoretical wind farms were consequently significantly higher when using flight height distributions generated from barometric altimeters. Improving confidence in telemetry-obtained flight height distributions, which may then be applied to CRMs, requires sources of errors in these measurements to be identified. Our study improves knowledge of the calibration processes for flight height measurements based on telemetry data, with the aim of increasing confidence in their use in future assessments of collision risk and reducing the uncertainty over predicted mortality associated with wind farms.

Capsule Local factors can lead to strong variation in mortality rate and collision risk that obscures possible effects of turbine size in wind farms.Aims The impact of bird collisions was studied at eight land-based wind farm sites with a total of 66 small to large turbines in order to assess the mortality rate and collision risk.Methods Searches for collision fatalities were performed under all turbines with a minimum search interval of 14 days. Mortality rate was calculated with corrections for available search area, scavenging and search efficiency. Flight movements of birds crossing five of the wind farm sites were recorded during a minimum of four days per site. Actual collision risk was then calculated as the number of collision fatalities relative to the average surveyed flight intensity.Results Mortality rate was 21 birds per turbine per year on average. Most fatalities were local common species (e.g. gulls) but rarer species were also found (e.g. terns, raptors and waders). Collision risk of gulls was 0.05% and 0.08% on average for birds, respectively, flying at turbine and rotor height through the wind farms (0.09% and 0.14% maximum). Large gulls had a significant higher collision risk than small gulls at rotor height. Mortality rate and collision risk were not significantly related to turbine size. The results were integrated in a widely used collision risk model to obtain information of micro-avoidance, i.e. the proportion of birds that fly through the wind farm but avoid passing through the rotor swept area of the turbines. For gulls, this micro-avoidance was 96.1% and 96.3% on average for birds, respectively, flying at turbine and rotor height through the wind farms.Conclusion The results indicate that local factors can lead to strong variation in mortality rate and collision risk that obscures possible effects of turbine size in wind farms. However, large turbines have more installed capacity (MW), so repowering wind farms with larger but fewer wind turbines, could reduce total mortality at certain locations.

Offshore wind farms are a key component of the transition to renewable energy generation and are planned globally. Procellariiformes (albatrosses, petrels, shearwaters and storm‐petrels) include the most threatened and abundant seabird families, yet their risk of collision with offshore wind turbines remains virtually unquantified because we lack the ecological information necessary to parametrise Collision Risk Models (CRMs) However, Procellariiformes are relatively well‐studied in academic literature, presenting the opportunity for systematic review through a collision‐risk lens. Here, we conduct meta‐analyses to calculate species‐level values for core CRM parameters: flight height, flight speed and nocturnal flight. Our systematic review returned 163 studies, providing excellent species coverage (>1 parameter value for 119 of the 145 Procellariiform species). We compiled a flight parameter database with the most values for flight speed and nocturnal flight, while values for Procellariiform flight height were scarce and lacked empirical data. Procellariiformes flew at speeds up to 28 ms−1 with species flight speeds generally prescribed by aerodynamic and flight morphology theory. Procellariiform flight activity varied across the diel cycle, with approximately a third of species flying more at night, a third flying more during the daytime and a third with no preference. Empirical studies characterised low (0–13 m) Procellariiform mean flight heights, but only for 21 species; expert opinion studies gave better coverage (104 species) but were highly uncertain when describing how frequently Procellariiformes may fly in a turbine's rotor swept zone. We make recommendations for how to best parameterise CRMs and identify priorities for further research, such as the importance of ‘instantaneous’ GPS biologger flight speeds, reconsidering how we model nocturnality in CRMs (given the abundance of night‐flying Procellariiformes), the merits of parameterising CRMs with site‐specific data over generic values and how new technologies can fill data gaps. Synthesis and applications. We present a database of mean flight parameter values and uncertainty for Procellariiform species and flight groups. Flight speed and nocturnal flight parameter values are ready for use in CRMs; but flight height results are too uncertain for useful parameterization. To fill this key information gap, we recommend mandatory Procellariiform flight height data collection at planned offshore wind farms.

In times of increasingly selective interpretations of research results, sound decision-making in environmental management can be complicated. Actors compete for opinion leadership over relevant findings. A recent example is the agitated debate over the study “Prognosis and assessment of collision risks of birds at wind turbines in northern Germany” (PROGRESS). This debate, arising in the science-policy-practice interface, challenges research results and subsequent implications for planning and decision-making processes. We used the PROGRESS discourse to conduct a “frame analysis” and identified relevant actors, their argumentation patterns and potential motives. Discourses reveal patterns of perception that can be spotted by content analyses of available statements. It became obvious that research results do not necessarily just reduce knowledge gaps. The frames “wildlife protection and conservation” and “research methods” were of major importance in the discourse, addressing the paramount question of whether wind energy development actually affects raptor populations. The discourse indicated, inter alia, that uncertainties still revolve around collision risk estimators, demographic population models, the efficacy of mitigation measures and whether the challenges at hand might be dealt with on a case-by-case or a metalevel planning approach. In conclusion, the question remains: Who might unanimously communicate both findings and implications? A thorough and bias-sensitive communication of research results might foster sound decision-making processes in the wind and wildlife sector, particularly based on “best available science” efforts.

The development and utilization of wind power to meet the electrical demand has recently received significant consideration. Additionally, one of the substantial roles of transmission system operators is to balance reactive power within a network in the sense that with the development of wind energy, wind turbines are expected to contribute towards reactive power generation. So far, there is not a wide range of attention being paid to reactive power in reliability evaluation including wind farms contribution. In this article, wind farms with several identical wind turbines are incorporated in reliability assessment while considering reactive power shortage. Fuzzy C-Means clustering method is used for the output power of wind turbines for analyzing power system reliability with wind farms integration. The application of this concept has been also utilized in developing multistep load levels in the illustrated load buses. Reactive power deficiency and the relevant voltage violations caused by the failure of reactive power generations are studied in this article. Load shedding and power injection techniques are employed to determine possible reactive power shortage required for alleviating network violations with and without wind power integration. Composite system reliability analysis in the existence of wind farms is implemented to assess indices affiliated with curtailed energy at various load points. The RBTS 6-bus system has been proportionally modified and studied to demonstrate the procedure. The results indicate the importance of wind power integration in improving both active and reactive reliability indices which in turn provide system planners with long-range planning for system development.

Countries promoting renewable energies encounter a variety of phenomena that can challenge the implementation of further onshore wind energy development. Those challenges can be observed in many multi-level governance systems, as exhibited in the U.S., Germany, and Mexico, where various regulatory and institutional levels must agree on goals and responsibilities. This is a challenge, as both forms of governance (top-down and bottom-up dominated) are present in wind energy planning and policy. (1) Political and market phenomena, (2) siting issues, (3) the vs. dilemma, and (4) social acceptance are selected challenges within the different levels of decision-making processes in wind energy implementation. (1) Political and financial factors can influence the development by implementing incentive- and market-based policies, command-and-control policies, and feed-in tariffs. However, success of these policy designs for renewable energies is based on different political environments, and their electricity markets nationally, regionally, or statewide. (2) Spatial limitations in planning are created based on limited land availability due to conflicts with other land uses such as aviation, nature reserves, residential areas, their respective buffers. (3) The vs. green dilemma involves the incoherent relationship between policies promoting renewable energies with policies protection species and their environments, becoming a major point of concern during siting and operations of wind energy. (4) Lastly, while there is a general overall support for wind energy, social acceptance on a local level is influenced by institutional settings i.e. information availability, as well as public and stakeholder concerns. Involvement in decision-making as well as financial participation (e.g. community-ownership) affects public participation and acceptance. This paper goes into detail on these phenomena and discusses case studies in Europe and North America. Often, these challenges can enhance outlooks in policy and planning, posing solutions to wind energy challenges even in sensitive environments and triggering innovations such as adaptive management.

The behaviour of breeding Montagu’s harriers towards wind farms in Schleswig-Holstein in Northern Germany was investigated in a two years telemetry study. A total of 11 breeding birds were fitted with VHF transmitters. The home ranges varied between 340 and 1560 ha (kernel). Males had larger home ranges than females. Centres of flight activity (50% kernel) were in the surroundings of nests and comprised between 41 and 252 ha. The salt marshes of the intertidal zone and large extensive grasslands rich in ecotones were important foraging grounds. Wind farms within the home range were used without avoidance of the close-up area of wind turbines. The intensity of use depended on location and distance of wind turbines from the centre of activity (nest) and available foraging grounds. The results gave no hint of displacement effects in the selection of the nest site or avoidance behaviour in the use of the habitat. 60–70% of the flight heights of Montagu’s harriers were below 10 m, rarely reaching the risk area of currently installed wind turbines. Flight activities in critical heights were concentrated on the nest site with 50% of the recorded locations within a radius of 182–497 m around the nest. With increasing distance from the nest, the flight activity per area was decreasing considerably. Due to hunting flights, mainly below 10 m height, low collision risk occured in the periphery of the home range. The distance between nest and wind turbine was a decisive factor for the collision risk. Habitat management concepts in order to lower the collision risk by relocating breeding sites to locations outside the impact range of wind turbines and by channeling flight activity along suitable created foraging grounds are discussed.

Large wind-turbine projects in the United States wind energy program

Mapping the collision risk between two gull species and offshore wind turbines: Modelling and validation

Wind energy is one of the fastest-growing renewable energy technologies. One of the environmental concerns associated with wind energy development is noise emission from wind energy facilities, especially the low-frequency noise and infrasound that allegedly raises public health concerns. In order to analyze the noise emission from wind turbines and to aid future wind energy development, a numerical simulation tool for the prediction of low-frequency noise and infrasound emission from wind turbines is developed. The simulation tool is a low-order model developed by combining aerodynamic noise theories and basic working principles of wind turbines. 2-D airfoil aerodynamics calculation is coupled with a subroutine that solves Ffowcs Williams-Hawkings (FW-H) equation in time domain. By omitting unsteady aeroacoustics mechanisms, the low-order simulation model is capable of computing infrasound emissions from multiple wind turbines simultaneously. By utilizing the low-order simulation model, the effects of wind directions, wind turbine locations, and phases of wind turbine rotations on the consequent aerodynamic infrasound are studied. Results of aerodynamic infrasound computation imply that wind farm configuration or wind turbine phase adjustment can help reduce the noise level at certain locations, which makes the low-order simulation model a useful tool to aid wind farm siting and controlling.

Even though the proportion of wind farm victims compared to general bird species mortality is relatively low, there is necessity to limit direct and indirect losses to the bird populations caused by this kind of human activity. Estimation of threats to the birds resulting from building of wind farms is a very difficult task and it must take into account several constrains. The basic task is to build farms in localities that are the safest to birds. This can be achieved by pre-investment monitoring and direct observations at the spot and then evaluation of potential threats and risks. Field methods typical for the studies on bird populations are usually applied in such monitoring. The procedure described below includes four steps: screening (starts the process and sets preliminary constrains of the location), monitoring (standardised data are collected at the location), estimations of potential collision risk and evaluation of the location. The key parameters determining collision risk of bird species are: (1) the number of individuals utilising the monitored area in different seasons, (2) air space utilization (height and directions of flights), as well as (3) characteristics of the species behaviour. The starting data set contains: species name, number of individuals, height of flight (three layers - below, in, above the rotor), and distance from the observer. The final estimation of the collision index (the most probable number of collisions per turbine a year) is based on (1) estimation of the total number of individuals that use the defined area during a year and (2) estimation of probability that the individual will collide. In the latter (i.e. 2) the most important is that birds can actively avoid passing through the rotor swept (active avoidance rate) and that even birds, which crossed the rotor swept area not necessarily will be killed. Calculations are performed for each species separately and then are summarised to get the farm index as well as season indices. Some values of indices for raptors studied at 76 localities in Poland are given in the table. The final evaluation of the site is made as shown in a parametric analysis table, discussion of cumulative and barrier effects and the discussion of species specific risk to species of high conservation concern.

Spatial planning plays a crucial role in implementing policies for renewable energy, especially when it comes to wind energy. At the same time, spatial planning can be the place where governmental support programs for renewable energy meet with local resistance. By comparing two inherently different spatial planning approaches for wind energy in two sub-national jurisdictions, this paper addresses the relationship between wind energy planning and the overall governance arrangement for renewable energy. It thereby contributes to an emerging understanding of spatial planning as the governance of place. Focusing on Ontario, Canada, and Brandenburg, Germany, as the two sub-national forerunners in wind energy development, the paper identifies spatial-discursive strategies employed by the government and the anti-wind movement. In anticipation of conflict, Ontario has chosen to raise planning responsibility for renewable energy facilities to the provincial level. In contrast, Brandenburg has chosen to endorse its regional planning approach. Drawing on document analysis and interviews with planners, policy-makers, and anti-wind protest groups in both jurisdictions, the paper finds that the design of spatial planning has played a crucial role in the governance and the contestation of sub-national policy schemes in both jurisdictions.

According to the characteristics of double fed asynchronous generator rotor energy flow, research and design based on the DSP control with two-way flow of energy function of Dual PWM converter and discusses the grid side converter control method of Dual PWM converter in particular. The wind turbine simulation model is established by using the electromagnetic transient PSCAD/EMTDC software. The simulation system is used to simulate the P, Q decoupling control and maximum wind energy tracking control of the generator. Wind is a natural phenomenon generated by the solar radiation heat, the earth's surface caused by uneven heating of the atmosphere. It is estimated that only 1% of the wind on the ground will be able to meet the needs of the world's energy. With the continuous improvement of the level of wind power generation technology, the cost of wind power gradually reduced, considering environmental benefits, the cost will be close to the cost of coal-fired power generation. Therefore, great efforts to develop wind energy as the representative of the renewable energy and new energy, to achieve sustainable development, has become the consensus of the whole society, strategic choice to solve the energy crisis and environmental problems. 2.Overview of control technology of doubly fed wind power gener ation Wind power is the kinetic energy contained in the natural wind into electrical energy in the process, the wind turbine wind energy capture and convert it into mechanical energy, driven by rotary generator, and the generator for converting mechanical energy conversion into electrical energy. As countries around the world pay more attention to wind power, wind power has become the world's fastest, most widely studied and applied new energy technology. With the development of wind power technology, wind turbine, wind turbine generator, converter and its control system and the way of the wind turbine, there are different types of. Among them, the doubly fed wind power generation system due to the converter control capacity is small, the speed of operation range wide characteristics become currently the world's most widely used VSCF wind power generation system. Variable speed constant frequency generator in asynchronous generator rotor side applied three-phase low frequency current to realize AC excitation, the output power is constant frequency and constant voltage amplitude, frequency, phase of the exciting current control. At the same time, the active power and reactive power decoupling control of the generator is realized by using the vector control technology. Control active power capable of adjusting the rotation speed of the wind turbine, to capture the maximum wind power tracking control; regulation of reactive power adjustable power factor and improve the dynamic and static stability of the wind turbine and power system operation. In addition, the VSCF wind power generation technology, so to achieve good flexible connection between the generator and power grid system, compared with the traditional constant speed constant frequency generation system easier to achieve grid connected operation and operation

The restructuring of the energy industry is imperative, as New Zealand strives to reduce greenhouse gas emissions. New Zealand has abundant renewable energy resources, and about 85% of current electricity generation is from renewable energy sources. However, in recent years, it appears that a considerable fraction of wind energy has been underutilized. This article reviews the history, current status, and future trends of wind energy development in New Zealand. The main challenges to the current development of wind energy are summarized compared to other countries. The main challenges come from the bi-cultural influence, environmental influence, and economic and social influence due to the variable nature of wind power, it is critical to store and operate power safely and reliably during peak power generation periods. This article compares seven mainstream wind energy storage technologies and analyzes the best solution for wind energy storage in New Zealand. This article analyzes the feasibility of using small-scale household (standard power rating range from 0.004 to 16 kW) wind turbines in New Zealand cities regarding their construction and operation process. The life cycle and the maximum capacity coefficient of such small-scale wind turbines are overviewed via three case studies and later compared with large commercial wind turbines (standard power rating ranges from 1 to 3 MW) in power generation capacity. It has been found that small-scale household wind turbines have notable power generation potential and economic benefits in the long term.