No file available
To read the file of this research,
you can request a copy directly from the authors.
Public Responses to Airborne Wind Energy: A Literature Review
Abstract
Airborne wind energy (AWE) systems use tethered flying devices to harvest higher-altitude winds to produce electricity. For a successful deployment of these systems, it is crucial to understand how the public perceives them. If public concerns about the technology are not taken seriously, implementation could be delayed or, in some cases, prevented, resulting in increased costs for project developers and a lower contribution of the sector to renewable energy targets. This literature review assessed the current state of knowledge on public responses to AWE. An exhaustive literature search led to the identification of 40 relevant publications that were reviewed. The literature assumed that the safety, visibility, acoustic emissions, ecological impacts, and the siting of AWE systems shape public responses to the technology. The reviewed literature views people’s responses to AWE very optimistically but lacks scientific evidence to back up its claims. It seems to overlook that the influence of AWE’s characteristics (e.g., visibility) on public responses will also depend on a range of situational and psychological factors (e.g., people’s general attitude towards AWE, the public’s trust in project developers). Therefore, empirical social scientific research is needed to increase the field’s understanding of public responses to AWE and thereby facilitate deployment.
... The visual impact of AWE systems is considered to be lower than that of conventional WTs, due to the fact that these systems fly at greater altitudes and do not occupy any airspace while off-operation [150,161]. The airborne system's smaller size and aesthetic flight pattern result in a lower visual impact. ...
... Similarly to visibility of AWE systems, the sound emissions are also expected to be lower than for conventional WTs. It is crucial to abide by local noise limitations since noise can make people uncomfortable and cause health problems such as sleep disturbances [161]. Sound pressure levels above 40 dB are reported to cause these problems [163]. ...
... Due to the use of lighter materials than rigid or hybrid wings, people may believe soft wings to be safer [151]. This lower risk is not entirely evident, though, as soft wings are more likely to hurt people in an uncontrolled crash (rigid wings have higher controllability, as seen in Section 8.2.2) [161]. Additionally, how electricity is produced affects how the public views safety: using on-board generation may cause people to worry about electric tethers flying through the air [172]. ...
Airborne wind energy (AWE) has received increasing attention during the last decade, with the goal of achieving electricity generation solutions that may be used as a complement or even an alternative to conventional wind turbines. Despite that several concepts have already been proposed and investigated by several companies and research institutions, no mature technology exists as yet. The mode of energy generation, the type of wing, the take-off and landing approaches, and the control mechanisms, to name a few, may vary among AWE crosswind systems. Given the diversity of possibilities, it is necessary to determine the most relevant factors that drive AWE exploration. This paper presents a review on the characteristics of currently existing AWE technological solutions, focusing on the hardware architecture of crosswind systems, with the purpose of providing the information required to identify and assess key factors to be considered in the choice of such systems. The identified factors are categorized into four distinct classes: technical design factors (aerodynamic performance, mass-to-area ratio, durability, survivability); operational factors (continuity of power production, controllability, take-off and landing feasibility); fabrication and logistical factors (manufacturability, logistics); and social acceptability factors (visual impact, noise impact, ecological impact, safety).
... Noise may lead to annoyance in people, which includes health complaints such as sleep-disturbance, thus it is of great importance to comply with local noise limits (Schmidt et al., 2021). These disturbances are reported for sound pressure levels over 40 dB (Knopper et al., 2014). ...
... People might perceive soft wings as safer than rigid or hybrid wings due to the use of lighter materials (Paulig et al., 2014). However, the smaller risk is not that clear, since one may note that soft wings are more likely to cause harm due to an uncontrolled crash (Schmidt et al., 2021) (rigid wings have higher controllability, as discussed earlier). Furthermore, the mode of electricity production influences the social perception of safety: the use of on-board generation might raise concerns about electric tethers moving through the air (Abbate and Saraceno, 2019). ...
Over the last decade, the Airborne Wind Energy (AWE) innovation has been evolving with the development of several prototypes by various companies/research institutions. AWE crosswind systems may differ in the electricity generation mode, the wing type, the take-off/landing approaches and the control mechanisms, to name a few. Each system has characteristics which enhance their performance regarding key factors of AWE exploration at the expense of penalizing others. Hence, deciding for the most appropriate system in a possible AWE implementation, targeting a certain location, is a difficult and uncertain scenario. This paper presents a Multi-Criteria Decision Analysis (MCDA) approach, using the Fuzzy Analytic Network Process (FANP), aiming to determine, from nine alternatives, the most suitable AWE crosswind system for two distinct exploration sites: onshore rural and offshore. The importance of key selection criteria for AWE is presented and discussed, alternatives in each criterion are evaluated and compared and, finally, a prioritization of both alternatives and criteria is obtained. The FANP methodology indicates rigid wing pumping-cycle systems with horizontal takeoff as the most suitable solution for both investigated sites, revealing Aerodynamic Performance, Mass-to-Area Ratio and Controlability as the most relevant factors in the decision.
Airborne wind energy (AWE) is a new power generation technology that harvests wind energy at high altitudes using tethered wings. The potentially higher energy yield, combined with expected lower costs compared to traditional wind turbines (WTs), motivates interest in further developing this technology. However, commercial systems are currently unavailable to provide more detailed information on costs and power generation. This study estimates the economic value of AWE in the future electricity system, and by that indicates which cost levels are required for AWE to be competitive. A specific focus is put on the relation between AWE systems (AWESs) and WTs. For this work, ERA‐5 wind data are used to compute the power generation of the wind power technologies, which is implemented in a cost‐minimizing electricity system model. By forcing a certain share of the annual electricity demand to be supplied by AWESs, the marginal system value (MSV) of AWE is investigated. The MSV is found to be affected by the AWE share, the wind resource, and the temporal distribution of the AWES's electricity generation. The MSV of AWE is location‐ and system‐dependent and ranges between 1.4 and 2.2 at a low share of AWE supply (0%–30%). At higher shares, the MSV drops. The power generation of WTs and AWESs are related, implying that the wind technologies present a similar power source and can be used interchangeably. Thus, the introduction of AWESs will have a low impact on the cost‐optimal wind power share in the electricity system, unless an AWES cost far below the system‐specific MSV is attained.
Airborne Wind Energy (AWE) technology provides an interesting re-design for energy generation from the wind. The value of renewable energy systems is their ability to generate electricity with reduced environmental impacts, most crucially being the Global Warming Potential. In this project, it is assessed what the impacts of a potential Multi-Megawatt AWE system would be. Firstly to determine where its impact hot-spots are located and secondly to assess how this new technology would compare to conventional wind energy systems operating in the same farm. The location of the farm is included as a sensitivity parameter to assess the advantages and disadvantages of both systems for operation in various locations under different environmental conditions. The technologies were assessed and compared using a Life Cycle Assessment (LCA) method. The LCA is used to assess the systems for their Global Warming Potentials (GWP) and their Cumulative Energy Demands (CED). The CED is subsequently also used to determine the Energy Payback Time (EPBT) and the Energy Return of Investment (EROI) of both systems. The assessment of the impacts was performed on models that first had to be designed. The many unknowns and variables in both designs meant that modelling accounted for a large fraction of the project. The AWE system is modelled as a Ground-Gen, Rigid-Wing system based on the design of Ampyx Power. The HAWT system is designed to represent an accurate comparison model for the AWE system. It is fully based on various literature sources, primarily on optimisations of the NREL 5MW. It was found that the impacts of the HAWT system greatly depends on environmental conditions at the location for which it is designed. The AWE system does however only minimally depend on the environmental conditions. Thereby, it can be evaluated where AWE would have the largest advantage over HAWT technology and where HAWT technology may be better. The project is carried out in collaboration with Airborne Wind Europe and Ampyx Power. Data was intended to come from Ampyx Power. However, the project started too early into delayed feasibility studies which limited the availability of design data and even concept plans. The report therefore presents the impacts of a potential future 5 MW system. Modelled to the best ability at this time, with an hydraulic drivetrain and a hub-less drum design. Additional focus is placed on the availability of improvement potentials and assessment of design variables. Thereby aiming to further improve general sustainable knowledge within the AWE sector. The AWE system is found to use significantly less materials and to produce electricity at notably lower impacts compared to the HAWT system. AWE is found to be most advantageous for operation at unfavourable environmental conditions, where the wind speed is low, and the HAWT system requires a large hub-height. The Land and Launch Apparatus (LLA) and the Power Generation Apparatus (PGA) subsystems are found to be the largest impact contributors within the AWE system. The largest impact component is found to be the hydraulic accumulator system in the PGA, primarily due to its large mass. Its high impacts are closely followed by the light weight tether and aircraft subsystems that require materials with high specific impacts.
Airborne wind energy systems convert wind energy into electricity using tethered flying devices, typically flexible kites or aircraft. Replacing the tower and foundation of conventional wind turbines can substantially reduce the material use and, consequently, the cost of energy, while providing access to wind at higher altitudes. Because the flight operation of tethered devices can be adjusted to a varying wind resource , the energy availability increases in comparison to conventional wind turbines. Ultimately, this represents a rich topic for the study of real-time optimal control strategies that must function robustly in a spatiotemporally varying environment. With all of the opportunities that airborne wind energy systems bring, however, there are also a host of challenges, particularly those relating to robustness in extreme operating conditions and launching/landing the system (especially in the absence of wind). Thus, airborne wind energy systems can be viewed as a control system designer's paradise or nightmare, depending on one's perspective. This survey article explores insights from the development and experimental deployment of control systems for airborne wind energy platforms over approximately the past two decades, highlighting both the optimal control approaches that have been used to extract the maximal amount of power from tethered systems and the robust modal control approaches that have been used to achieve reliable launch, landing, and extreme wind operation. This survey will detail several of the many prototypes that have been deployed over the last decade and will discuss future directions of airborne wind energy technology as well as its nascent adoption in other domains, such as ocean energy.
Airborne wind energy is a novel form of wind power. Through the use of lightweight
wings and tethers it aims to access locations out of reach to current wind harvesting
devices, at a lower cost and with a lower impact on the environment. There are multiple
airborne wind energy systems currently under development, one group of these, referred
to as rotary systems, use multiple wings networked together to form rotors. This thesis
presents an analysis on the design and operation of rotary systems, with a particular
focus on the power transmission from the airborne components down to the ground.
There are various power transmission methods used for rotary systems, among them
tensile rotary power transmission uses multiple networked tethers held apart by a small
number of rigid components to transfer torque from a flying rotor down to a ground
station.
The aim of this research is to improve the design and operation of rotary airborne wind
energy systems that incorporate tensile rotary power transmission, and to assess system
performance based on mathematical modelling and test data. It focuses on the Daisy
Kite system design, a rotary system, being developed by Windswept and Interesting.
Included in this thesis work is the development of three mathematical representations to
support systematic analysis and design improvement. The first representation, a steady
state model, is used to analyse rotary system design. The second and third models
are dynamic representations of varying complexity. Also included is an experimental
campaign conducted on the Daisy Kite in collaboration with Windswept and Interesting.
Field tests are carried out on nine different Daisy Kite prototypes at their test site on
the Isle of Lewis, Scotland. Measured data is collected for the various prototype designs under different operating conditions. The measured data is used to assess the reliability
of the three mathematical representations. This allows the models to be validated and
compared to one another in terms of their accuracy and computational efficiency. During
the experimental campaign several design and operational improvements are made that
increase the power output and lead to more reliable operation. The mathematical
representations are used to identify key design factors and to optimise rotary system
design. Improved understanding and design of the rotary airborne wind energy system
has been achieved through this holistic investigation.
In January 2020, a rumor from California in the United States reached researchers and entrepreneurs in Europe, a thriving hub for the small, mostly trans-Atlantic field of engineering research and development called airborne wind energy (AWE): Alphabet, American technology giant Google’s parent company, was quietly closing down Makani, the AWE subsidiary it had nurtured into the world’s most advanced, visible, and well-funded enterprise designing and building tethered flying machines—kites in AWE parlance—intended ultimately to produce megawatts of wind energy.
The transition towards more renewable energy will substantially increase voters’ involvement in the political decision-making process in the energy domain. Decisions such as whether to approve or reject large-scale energy programs can be complex, especially when available information cues are numerous and conflicting. Here, we hypothesize that political ideology is a strong determinant in this process, serving as a filter that voters apply when evaluating the relevance of provided information cues. We tested this hypothesis in the context of the 2017 Public Vote on the Swiss Energy Act. A sample of n = 931 Swiss voters were presented with arguments in favor or against the Energy Act, which were framed in terms of values found to be relevant for liberal and conservative ideologies, respectively. Political ideology strongly determined individual attitudes and voting preferences. Political ideology moreover moderated the influence of information provision on decisions, in that arguments congruent with voters’ political ideology were more likely to be evaluated as personally relevant and integrated into their decisions. We discuss the implications of our findings for measures on how to address ideology-based decision-making in order to ensure a well-informed electorate.
This thesis investigates crosswind Airborne Wind Energy Systems (AWESs) in terms of power production and potential role in future electricity generation systems. The perspective ranges from the small scale, modelling AWE as a single system, to the large, implementing AWESs in regional electricity systems.
To estimate the AWES power production, the thesis provides a dynamic system model that serves as the basis for all the work. The model describes the flight dynamics of a rigid wing that is exposed to tether and aerodynamic forces controlled by flight control surfaces. Index-3 Differential Algebraic Equations (DAEs) based on Lagrangian mechanics describe the dynamics.
This model is validated by fitting it to real flight measurements obtained with a pumping-mode AWES, the prototype AP2 by Ampyx Power. The optimal power production of an AWES depends on complex trade-offs; this motivates formulating the power production computation as an Optimal Control Problem (OCP). The thesis presents the numerical methods needed to discretize the OCP and solve the resulting Nonlinear Program (NLP).
Large-scale implementation of AWESs raises challenges related to variability in power production on the time scale of minutes to weeks. For the former, we investigate the periodic fluctuations in the power output of a single AWES. These fluctuations can be severe when operating a wind farm and have to be considered and reduced for an acceptable grid integration. We analyse the option of controlling the flight trajectories of the individual systems in a farm so that the total power output of the farm is smoothed. This controlled operation fixes the system's trajectory, reducing the ability to maximize the power output of individual AWESs to local wind conditions. We quantify the lost power production if the systems are controlled such that the total farm power output is smoothed. Results show that the power difference between the optimal and fixed trajectory does not exceed 4% for the systems modelled in the study.
The variations in AWESs power production on the timescale of hours to weeks are particularly relevant to the interaction between AWE and other power generation technologies. Investigating AWESs in an electricity system context requires power-generation profiles with high spatio-temporal resolution, which means solving a large number of OCPs. In order to efficiently solve these numerous OCPs in a sequential manner, this thesis presents a homotopy-path-following method combined with modifications to the NLP solver. The implementation shows a 20-fold reduction in computation time compared to the original method for solving the NLP for AWES power optimization. For large wind-data sets, a random forest regression model is trained to a high accuracy, providing an even faster computation.
The annual generation profiles for the modelled systems are computed using ERA5 wind data for several locations and compared to the generation profile for a traditional wind turbine. The results show that the profiles are strongly correlated in time, which is a sobering fact in terms of technology competition. However, the correlation is weaker in locations with high wind shear.
The potential role of AWESs in the future electricity system is further investigated. This thesis implements annual AWE-farm generation profiles into a cost-optimizing electricity system model. We find that AWE is most valuable to the electricity system if installed at sites with low wind speed within a region. At greater shares of the electricity system, even if AWESs could demonstrate lower costs compared to wind turbines, AWE would merely substitute for them instead of increasing the total share of wind energy in the system. This implies that the economic value of an AWES is limited by its cost relative to traditional wind turbines.
Societal opposition has the potential to slow down the implementation of Carbon Capture and Storage (CCS). One of the difficulties is that the perceived benefits associated with a CCS facility for local communities tend to be low compared to its perceived burdens. As is the case for other low carbon technologies, community compensation (or community benefits) has been suggested as a way to restore this perceived imbalance. A diverse literature has looked into the role of community compensation across various land uses and research fields. Synthesis is limited, while at the same time, the provision of community compensation in practice is moving from an ad hoc to a more institutionalized approach. Therefore, it is important to take stock of the literature. This paper provides a review of the community compensation literature in the form of four debates, drawing together environmental social science research on different low carbon technologies (e.g. CCS, renewable energy). In addition, current practices in community compensation for four European countries are discussed. The two parts of this paper are brought together in a set of lessons for the provision of community compensation for future CCS projects; in turn, suggestions for further research are made to address remaining knowledge gaps.
Fossil fuel is the major source of energy and is a fast depleting resource. The phenomenal increase in fossil fuel consumption has adversely affected carbon footprint impacting our environment. With strict environmental regulations in place, the focus towards renewable sources of energy is gaining momentum supported by recent advancement in technologies in wind, hydro and solar. Wind turbines were the first forms of clean energy has seen a major increase in power production. The site restrictions, have limited the wind turbine from being used to its maximum potential. In recent years, the concept of some unconventional methods is being proposed. In this review, the various types of wind turbines are emphasized with their recent advances and depicting the challenges faced in various aspects. The reviews contain details mainly about 4 types of wind turbines i.e. floating offshore wind turbine, airborne wind turbine, highway wind turbine systems and locomotive mounted wind turbine.
Social sciences have been very prolific in the last decades in publishing research that attempts to better understand the social acceptance of renewable energy technologies and associated infrastructures (RET) – such as high voltage power lines – and processes – such as communities’ participation in related decision-making processes. This Perspective proposes that this might be a good point in time, roughly 30 years after social sciences begun looking at the social side of RET, to offer a (over)view on that research, if and how it has changed over time and where it leaves us currently or, in other words, which directions we should follow in the future. I first provide an overview of research on the social acceptance of RET, suggesting that it can be roughly organized around three waves - normative, criticism and critical -; for then identifying and discussing some avenues for future research.
Airborne wind energy systems use tethered flying devices to harvest wind energy beyond the height range accessible to tower‐based wind turbines. Current commercial prototypes have reached power ratings of up to several hundred kilowatts, and companies are aiming at long‐term operation in relevant environments. As consequence, system reliability, operational robustness, and safety have become crucially important aspects of system development. In this study, we analyze the reliability and safety of a 100‐kW technology development platform with the objective of achieving continuous automatic operation. We first outline the different components of the kite power system and its operational modes. In the next step, we identify failure modes, their causes, and effects by means of failure mode and effects analysis (FMEA) and fault tree analysis (FTA). Potentially hazardous situations and mechanisms which can render the system nonoperational are identified, and mitigation measures are proposed. We find that the majority of these measures can be performed by a failure detection, isolation, and recovery (FDIR) system for which we present a hierarchical architecture adapted from space industry.
We compare the available wind resources for conventional wind turbines and for airborne wind energy systems. Accessing higher altitudes and continuously adjusting the harvesting operation to the wind resource substantially increases the potential energy yield. The study is based on the ERA5 reanalysis data which covers a period of 7 years with hourly estimates at a surface resolution of 31 31 km and a vertical resolution of 137 barometric altitude levels. We present detailed wind statistics for a location in the English Channel and then expand the analysis to a surface grid of Western and Central Europe with a resolution of 110 x 110 km. Over the land mass and coastal areas of Europe we find that compared to a fixed harvesting height at the approximate hub height of wind turbines, the wind power density which is available for 95% of the time increases by a factor of two.
We present a computational fluid dynamic analysis of boundary layer transition on leading edge inflatable kite airfoils used for airborne wind energy generation. Because of the operation in pumping cycles, the airfoil is generally subject to a wide range of Reynolds numbers. The analysis is based on the combination of the shear stress transport turbulence model with the
γ
-
R
˜
e
θ
t
transition model, which can handle the laminar boundary layer and its transition to turbulence. The implementation of both models in OpenFOAM is described. We show a validation of the method for a sailwing (ie, a wing with a membrane) airfoil and an application to a leading edge inflatable kite airfoil. For the sailwing airfoil, the results computed with transition model agree well with the existing low Reynolds number experiment over the whole range of angles of attack. For the leading edge inflatable kite airfoil, the transition modeling has both favorable and unfavorable effects on the aerodynamics. On the one hand, the aerodynamics suffer from the laminar separation. But, on the other hand, the laminar boundary layer thickens slower than the turbulent counterpart, which, in combination with transition, delays the separation. The results also indicate that the aerodynamics of the kite airfoil could be improved by delaying the boundary layer transition during the traction phase and tripping the transition in the retraction phase.
Information on the size of academic search engines and bibliographic databases (ASEBDs) is often outdated or entirely unavailable. Hence, it is difficult to assess the scope of specific databases, such as Google Scholar. While scientometric studies have estimated ASEBD sizes before, the methods employed were able to compare only a few databases. Consequently, there is no up-to-date comparative information on the sizes of popular ASEBDs. This study aims to fill this blind spot by providing a comparative picture of 12 of the most commonly used ASEBDs. In doing so, we build on and refine previous scientometric research by counting query hit data as an indicator of the number of accessible records. Iterative query optimization makes it possible to identify a maximum number of hits for most ASEBDs. The results were validated in terms of their capacity to assess database size by comparing them with official information on database sizes or previous scientometric studies. The queries used here are replicable, so size information can be updated quickly. The findings provide first-time size estimates of ProQuest and EbscoHost and indicate that Google Scholar’s size might have been underestimated so far by more than 50%. By our estimation Google Scholar, with 389 million records, is currently the most comprehensive academic search engine.
Despite the increasing importance of studies dealing with acceptance in the field of land use, few theoretical-conceptual reflections and reviews have been published. To address this gap, this paper offers a critical and systematic review of recent literature regarding acceptance and land use. Our aim is to synthesise the contributions of these publications in order to advance scientific debate on this topic. The data set consists of 132 peer-reviewed journal articles and book chapters and is dominated by empirical papers (mostly quantitative studies) and European case studies. Renewable energy appears as the most important thematic issue, followed by sustainable land use. In these studies, many researchers did not define acceptance or apply a theory. It seems to be perceived as an everyday term with a clear meaning. However, this review reveals that there is no common understanding of acceptance; instead, the given definitions and characteristics are sometimes even contradictory. Acceptance is often considered a positive and desirable outcome of planning projects. Only a few authors understand acceptance as a complex phenomenon. As a cross-sectoral research topic, it applies theories from different disciplines and research fields (psychology, sociology, and innovation research), even though the use of these theories within disciplines is not consistent. Most empirical studies address influencing factors with the aim of explaining decisions about acceptance. However, the theoretical foundation underlying the selection of factors is often weak. Therefore, we recommend that researchers engage in a thorough reflection of notions and concepts , suitable and sound identification of influencing factors. In concluding with our own theoretical-conceptual reflections, we support the idea that acceptance and acceptability should be distinguished to gain more clarity in the use of terms. Thus, acceptability encompasses actor-based and dynamic decision processes. The decisions are products of interactions among the actors, the object, and the context. They can be assigned to a particular degree (from rejection to acceptance or engagement) and made at the attitude, action, or utilization level. Finally, we believe that further research can benefit from this advanced concept of acceptability.
Precise estimation of position, velocity, and orientation is crucial for robust control in airborne applications such as the fast maneuvering power kites for airborne wind energy generators. In this paper we present a sensor fusion approach for the measurements of a global navigation satellite system receiver and an inertial measurement unit, using methods from direct optimal control. The resulting optimization problem is based on the minimization of the weighted squared residuals between model predictions and measurements and solved using a direct collocation discretization strategy. The framework allows the formulation of a batch and filter estimator which include beside the estimation of the navigational states the identification of sensor parameters such as biases of the inertial measurement unit. The results of the algorithms are evaluated against a reference trajectory of a maneuvering single propeller aircraft and achieve root mean squared errors below 1 m in position, 0.4 ms⁻¹ in velocity, and 0.5 deg in orientation for the batch estimator. The contribution in this paper is a first step towards the required robustness of state estimation for airborne applications.
Thirty years of North American research on public acceptance of wind energy has produced important insights, yet knowledge gaps remain. This review synthesizes the literature, revealing the following lessons learned. (1) North American support for wind has been consistently high. (2) The NIMBY explanation for resistance to wind development is invalid. (3) Socioeconomic impacts of wind development are strongly tied to acceptance. (4) Sound and visual impacts of wind facilities are strongly tied to annoyance and opposition, and ignoring these concerns can exacerbate conflict. (5) Environmental concerns matter, though less than other factors, and these concerns can both help and hinder wind development. (6) Issues of fairness, participation, and trust during the development process influence acceptance. (7) Distance from turbines affects other explanatory variables, but alone its influence is unclear. (8) Viewing opposition as something to be overcome prevents meaningful understandings and implementation of best practices. (9) Implementation of research findings into practice has been limited. The paper also identifies areas for future research on wind acceptance. With continued research efforts and a commitment toward implementing research findings into developer and policymaker practice, conflict and perceived injustices around proposed and existing wind energy facilities might be significantly lessened.
Social acceptance is a key challenge for the deployment of wind energy and could limit the overall wind resource we are able to exploit to meet climate change targets. Social acceptance can be influenced by a very wide range of factors, including project characteristics, perception of the distribution of costs and benefits, degree of public participation. Perceived impacts of projects on landscapes, property values, health and biodiversity also influence social acceptance. This complexity means that acceptance cannot be addressed through simple fixes such as community benefit funds or just more consultation, but we need a far more fundamental reform of how energy systems engage with communities and citizens.
Airborne Wind Energy (AWE) is an emerging field of technology that investigates wind power devices capable of remaining airborne either through aerostatic or aerodynamic forces. Consequently, the heavy and expensive tower of conventional horizontal-axis wind turbines is no longer needed, allowing the AWE device to operate at higher altitudes, where the wind tends to be steadier and stronger and, therefore, more power is available. Another claimed advantage is the reduction on overall costs, especially regarding transportation and installation, due to the absence of the tower to withstand the torque caused by the rotating turbine, thus also requiring a simpler foundation. Several AWE concepts have been proposed, among which the pumping kite stands out as one of the simplest and cheapest, essentially comprising a ground winch where energy is generated, and a tethered wing that can be either flexible or rigid. This dissertation contributes to the field of AWE by addressing the pumping kite in four different aspects. The goal is to serve both as a manuscript for the lay reader with some background on physics, aerodynamics, dynamic systems, classic control and optimization techniques, as well as by specialists in either of these areas who intend to carry out deeper investigations. The first contribution is to revisit in detail important models in the literature used to simulate the flight dynamics, to design and to validate control laws. Namely, the 3D two-tether point-mass wing (to which modifications are proposed), the massless wing in dynamic equilibrium, the course angle dynamics and the logarithmic wind shear model are addressed. The second contribution is a comparative study of flight controllers whose references are computed separately from the ground winch control, in a decentralized topology. A two-loop approach is considered, where the outer loop defines a reference trajectory and generates a reference for the course angle, which is then tracked in the inner loop by manipulating the steering input of the tethered wing. A third contribution is the formulation of an optimization problem to choose the operating parameters of the traction and retraction phases that yield the maximum cycle power. One of the main findings is that, by reeling out at a lower speed than the value that maximizes the traction power, the duty cycle increases and, thereby, also the cycle power. The last major contribution is to reinterpret Loyd’s lift (the pumping kite traction phase) and drag modes as particular cases of the actuator disc considered in the derivation of the Betz limit for power extraction from the wind. The expression for the lift mode power coefficient is formulated using blade element momentum theory.
Keywords: Airborne wind energy. Modeling. Flight control.
In many countries wind energy has become an indispensable part of the electricity generation mix. The opportunity for ground based wind turbine systems are becoming more and more constrained due to limitations on turbine hub heights, blade lengths and location restrictions linked to environmental and permitting issues including special areas of conservation and social acceptance due to the visual and noise impacts. In the last decade there have been numerous proposals to harness high altitude winds, such as tethered kites, airfoils and dirigible based rotors. These technologies are designed to operate above the neutral atmospheric boundary layer of 1300 m, which are subject to more powerful and persistent winds thus generating much higher electricity capacities. This paper presents an in-depth review of the state-of-the-art of high altitude wind power, evaluates the technical and economic viability of deploying high altitude wind power as a resource in Northern Ireland and identifies the optimal locations through considering wind data and geographical constraints. The key findings show that the total viable area over Northern Ireland for high altitude wind harnessing devices is 5109.6 km², with an average wind power density of 1998 W/m² over a 20-year span, at a fixed altitude of 3000 m. An initial budget for a 2 MW pumping kite device indicated a total cost £1,751,402 thus proving to be economically viable with other conventional wind-harnessing devices.
Airborne Wind Energy Converters (AWECs) are promising devices that, thanks to tethered airborne systems, are able to harvest energy of winds blowing at an altitude which is not reachable by traditional wind turbines. This paper is meant to provide an analysis and a preliminary evaluation of an AWEC installed on a floating offshore platform. A minimum complexity dynamic model is developed including a moored heaving platform coupled with the dynamics of an AWEC in steady crosswind flight. A numerical case study is presented through the analysis of different geometrical sizes for the platform and for the airborne components. The results show that offshore AWECs are theoretically viable and they may also be more efficient than grounded devices by taking advantage of a small amount of additionally harvested power from ocean waves.
Abstract Among novel technologies for producing electricity from renewable resources, a new class of wind energy converters has been conceived under the name of Airborne Wind Energy Systems (AWESs). This new generation of systems employs flying tethered wings or aircraft in order to reach winds blowing at atmosphere layers that are inaccessible by traditional wind turbines. Research on AWESs started in the mid seventies, with a rapid acceleration in the last decade. A number of systems based on radically different concepts have been analyzed and tested. Several prototypes have been developed all over the world and the results from early experiments are becoming available. This paper provides a review of the different technologies that have been conceived to harvest the energy of high-altitude winds, specifically including prototypes developed by universities and companies. A classification of such systems is proposed on the basis of their general layout and architecture. The focus is set on the hardware architecture of systems that have been demonstrated and tested in real scenarios. Promising solutions that are likely to be implemented in the close future are also considered.
As the significance of public opinion and practice for energy system change has become more widely understood, an expanding body of work is investigating drivers of social and public acceptance of a wide diversity of energy technologies, both infrastructure and end-user applications. The literature is large and spans multiple contexts, methods, theoretical and disciplinary perspectives and paradigms. While this diversity is in many ways healthy, experience suggests that it can be confusing for those without close knowledge of its constituent parts. Here we set out a framework for thinking about energy technology ‘acceptance’ that is relatively neutral in normative and theoretical terms, while acknowledging that a full integration of perspectives and complete theoretical neutrality are not possible. We do not claim a comprehensive review base, but draw on our experience to illustrate the diversity of what we regard as the more influential perspectives in the literature.
A compact flight dynamics model of a kite is developed by using Lagrangian formulation. The lengths of the three ropes of the bridle and the tether of the kite depend on time and are used to implement an open-loop control scheme of the kite system. By imposing simple time-periodic control laws, two pumping strategies for wind-energy generation are explored. Periodic trajectories of the system and their stability properties (Floquet characteristic multipliers) are computed numerically. As the amplitudes of the figure-eight paths are increased, the system becomes more efficient but less stable. A cyclic-fold bifurcation is detected for a very large lateral displacement of the kite. The impact of the control-law parameters on the generated power, including the period and the amplitude, is investigated. The results indicate that a correct design of the control could provide an optimal energy-generation system and a robust scheme to exploit high-altitude winds.
The association between wind turbines and health effects is highly debated. Some argue that reported health effects are related to wind turbine operation [electromagnetic fields (EMF), shadow flicker, audible noise, low-frequency noise, infrasound]. Others suggest that when turbines are sited correctly, effects are more likely attributable to a number of subjective variables that result in an annoyed/stressed state. In this review, we provide a bibliographic-like summary and analysis of the science around this issue specifically in terms of noise (including audible, low-frequency noise, and infrasound), EMF, and shadow flicker. Now there are roughly 60 scientific peer-reviewed articles on this issue. The available scientific evidence suggests that EMF, shadow flicker, low-frequency noise, and infrasound from wind turbines are not likely to affect human health; some studies have found that audible noise from wind turbines can be annoying to some. Annoyance may be associated with some self-reported health effects (e.g., sleep disturbance) especially at sound pressure levels >40 dB(A). Because environmental noise above certain levels is a recognized factor in a number of health issues, siting restrictions have been implemented in many jurisdictions to limit noise exposure. These setbacks should help alleviate annoyance from noise. Subjective variables (attitudes and expectations) are also linked to annoyance and have the potential to facilitate other health complaints via the nocebo effect. Therefore, it is possible that a segment of the population may remain annoyed (or report other health impacts) even when noise limits are enforced. Based on the findings and scientific merit of the available studies, the weight of evidence suggests that when sited properly, wind turbines are not related to adverse health. Stemming from this review, we provide a number of recommended best practices for wind turbine development in the context of human health.
A frequent rationale of planning authorities and developers regarding local resistance to renewable energy facilities carries the assumption of people getting used to changes over time. This invokes a temporal dimension to the resolution of planning conflicts through processes of familiarisation and adaptation, which is also reflected in the so-called U-shaped curve indicating that local acceptance drops during the consenting process and increases again after deployment. However, in this explorative chapter, we caution against simplistic and short-sighted presumptions of post-construction acceptance. In doing so, we juxtapose notions of how the future is conceived and acted on in order to argue for less preemptive measures for gaining local acceptance and more locally beneficial renewable energy projects based on notions borrowed from prefigurative politics and radical planning.
Recent commentaries on the corpus of social acceptability research around renewable energy have identified the need for critical approaches that move beyond individualist and positivist methodologies. Many energy-related behaviours, much like the landscapes in which they play out, are recursively recreated and institutionalized as they are enacted, limiting the emergence and success of alternatives. We believe that quantitative methods—particularly household surveys—can generate relevant insights and illustrate this with recent quantitative surveys on energy transitions that explore, among other things, issues of materiality, social location and norms. We provide empirical examples of specific approaches for doing such work (e.g. question wording, experimental design) and make recommendations for a more fulsome engagement with critical approaches within a more positivist paradigm of data gathering.
In this part, we reflect upon the contributions of the presented chapters to a critical approach to research on the social acceptance of renewable energy technologies. First, we highlight the key transversal and common foci of the chapters and what they suggest in relation to core areas to be further developed within a critical approach. We then also identify and discuss what seem to be some of the ontological, epistemological and methodological tensions across the chapters and, namely, regarding their differential uptakes of two key dimensions of a critical approach: relationality and materiality. Finally, and based on those initial considerations, we suggest some avenues for future research on the social acceptance of renewable energy technologies based on a critical perspective.
Interdisciplinary working is increasingly common in academic research projects, but presents a number of challenges. This chapter focuses on terminology and language across disciplines, and explores why this matters for understanding social responses to renewable energy techology. It demonstrates that definitions are important not just to ensure that representatives from different disciplines can talk to each other, but that they have ramifications for how social responses themselves are conceptualised. Indeed, the nature of the issue itself depends on how concepts are defined. This chapter explores the impact of terminology; and suggests how to move forward in future interdisciplinary research.
“
At the height of laughter, the universe is flung into a kaleidoscope of new possibilities
.”—Jean Houston
United States offshore wind energy development (OWD) is poised to expand significantly in the coming decade as a result of substantial wind resources adjacent to large population and coastal load centers. A significant portion of OWD infrastructure may be sited within or adjacent to parks and protected areas, raising concerns about the potential social, situational, and ecological impacts upon coastal recreation. This novel study investigated the influence of perceived recreation impact and coping behaviors upon coastal recreationists’ general attitudes towards potential OWD at the New Hampshire seacoast. On-site surveys were used to collect data from New Hampshire coastal recreationists from June to September of 2019 (n = 553). The study sample’s perceptions towards the acceptance, support, fit, and recreation impact of OWD at the New Hampshire Seacoast was largely supportive and positive. The overall sample perceived the presence of OWD would not cause them to alter or substitute their recreation activities, behaviors, or experiences. Moreover, structural equation modeling suggests perceived recreation impact and coping behaviors are significant predictors of general attitudes towards OWD. Further, a lack of measurable effect from photo-elicitation priming suggests viewshed impacts and the spatial proximity of OWD siting did not have a significant influence upon general attitudes towards OWD. This research offers critical insights into the theories of stress-coping and landscape fit and calls into question the assumption that situational factors such as OWD act as a stressor on coastal recreation. This study found that OWD will likely have little impact on aggregate coastal recreation visitation, and in some instances, may even amplify visitation. This research demonstrates the importance of evaluating coastal recreationists’ perceptions, behaviors, and attitudes from a social-ecological approach when initiating OWD projects in the United States and abroad.
Despite potential benefits emerging energy technologies usually promise, the public often meets them with skepticism, resistance or even outright rejection. In this study, we investigated the potential role communication plays in the early stages of opinion formation. In particular, we examined the relationships among message framing, information processing, communication motivation and information seeking. Building on work examining uncertainty reduction, fairness, risk communication, and the theory of planned behaviors, we conducted an experiment in which a national sample of U.S. adults (N=1,042) were led to believe that enhanced geothermal systems (EGS) would be developed in their local community. Participants received initial information varying in degrees of uncertainty and procedural fairness about the EGS development. Subsequently, we offered them an opportunity to read additional articles about EGS, which was operationalized as actual information seeking behaviors. We found that predictors, such as affect, norm, current knowledge, and information need, explained information engagement intentions, which further predicted actual information seeking behaviors. In addition, systematic processing of the initial EGS information, perceived uncertainty, and perceived fairness had direct relations with actual information seeking. The discussion provides theoretical and practical implications.
Understanding the determinants of public acceptance is important for nuclear energy development. In the present study, we aim to explore the effects of perspective taking and energy policy involvement on public acceptance of nuclear energy. Following the motivated information processing theory, the current research proposes that perspective taking influences energy policy involvement, which in turn affects trust in government, risk perception, benefit perception, and ultimately influences public acceptance of nuclear energy. Based on an online questionnaire survey (valid samples were 933) conducted in China, results showed that perspective taking was positively and significantly related to energy policy involvement. Energy policy involvement was positively and significantly related to trust in government and benefit perception, while negatively and significantly related to risk perception. Trust in government and benefit perception were positively, while risk perception negatively and significantly related to public acceptance of nuclear energy. Theoretical and policy implications were discussed on the basis of these findings.
Installed wind energy capacity has been increasing steadily across the world and is expected to continue to do so in the future, in response to lowering costs of technology as well as increased renewable energy goals put forth by governments. Nonetheless, public opposition has been increasing and the discussion regarding siting wind turbines onshore or offshore is consistently present in public discourse. In combining a stated preference study with spatial data processed via GIS (Geographic Information Systems), spatial preferences for onshore and offshore wind turbines are explored while considering their visual impact and costs as well as controlling for the respondents' socioeconomic characteristics. In general, respondents state strong preferences towards offshore wind turbines as opposed to onshore. Furthermore, spatial data is found to be significant with regard to the preferences of the respondents, particularly respondents' distance to the coast and potential offshore wind farms and the number of wind turbines seen from the residence and the number of turbines in the postal area. As a secondary result, findings suggest socioeconomic characteristics such as age and income are significantly related to respondents’ preferences, in line with previous research.
The energy transition in Switzerland, as in many other countries, aims to increase the proportion of electricity produced using renewable energy technologies. In this context, governmental agencies and other institutions have attempted to communicate the implications of (domestic) electricity systems through the use of web-based and interactive decision support systems (DSSs). Studies show that, when no additional information is provided, preferences concerning the future electricity mix are mainly driven by the affective reactions that energy technologies evoke. A question remains, however, regarding how people engage with the information provided in a DSS, as well as whether such information is influential in terms of shaping people's choices. We asked our participants to build an electricity portfolio using a DSS, which modeled the Swiss electricity system. The participants' political orientation and their affective reactions to different energy technologies guided their information search, as well as the choice of energy technologies within their portfolio. The attention paid to the information provided was not directly related to the participants' portfolio choices. The selective processing of information, which was based on the participants' prior attitudes, suggests that they target information they are already familiar with in the DSS. However, this also illustrates a caveat previously identified in motivated political reasoning, since selective information processing, together with the tendency to disconfirm information that is incongruent with prior beliefs, can lead to the polarization of previously held views. As the information provided through the DSS we tested was unable to change the participants' affective-cognitive evaluation of energy technologies, its use should be carefully considered in light of the possible effects of consolidating existing beliefs.
To meet the worldwide requirements of carbon emission reduction, the European Council has set the UK a 15% energy target to come from renewable energy by 2020. The biggest renewable energy sources in the UK are bioenergy, wind, solar, and hydro. The UK is located in prime geography, considered to be the best in Europe, for harvesting, and over the last three decades, the number of wind farms has increased greatly. However, the interaction of wind speed and structural strength has limited the height of platform-based wind turbines to a maximum height of around 100 m. Airborne wind energy (AWE) systems enable the extraction of more energy from the wind at elevated altitudes beyond 150 m using a device termed a kite. A method is required to determine suitable locations for AWE system implementation. In this work, a regional feasibility study has been conducted to establish an ideal suitable location to implement AWE systems. Extensive research has been carried out to assess the electricity costs, energy savings, area availability, as well as regional airborne wind energy power densities at different regions within the UK. A standardized method has been developed to assess the viability of AWE in various geographical locations. It was found that Scotland was the most suitable location for the implementation of AWE systems due to the high wind power density in this region and existing high costs of electricity, thus greater potentials for energy cost savings.
In search of what else is emerging from the horizon in the renewable energy field, the key property to focus on is the auto-breeding capability, a feature that allows the success of an energy technology in a free competition. On the other hand, if a mature energy technology needs subsidy, this is a clear self-demonstration that auto-breeding is not possible for it. High-altitude wind is a concentrated, powerful and steady resource. Its potential has long been known, but only thanks to recent developments in the field of engineering and mechatronics, its exploitation is now possible. In the following, it will be described the state of the art of these new technologies, whose capital cost and LCOE projections clearly show the potential to auto-breed and really boost the quick replacement of fossil fuels. Among the others, we shall describe in more detail the KiteGen technology, because it is considered by several stakeholders the most advanced, being based on the vastest proprietary IP asset. Moreover, it is one the first players oriented towards large-scale devices.
Public acceptability is at the heart of changing the energy system toward a more sustainable way of energy production and use. Without public acceptability and support for changes, a sustainable energy transition is unlikely to be viable. We argue that public acceptability is often addressed too late and should be incorporated into the planning process from the start. Moreover, engineers, policy makers, and project developers tend to misjudge the complexity and causes of public resistance, trying to find the magic bullet to "solve" the lack of public acceptability. Such attempts are likely to be ineffective, or even counterproductive, if they fail to address people's key concerns surrounding energy projects. There is not a one-size-fits-all solution: public acceptability is a dynamic process that depends on the context, the specific project at stake, and the parties involved.
Acceptance plays an important role in the successful adoption of wind energy technology. This article identifies factors influencing the acceptance of wind energy and selects those factors which have the highest relevance for wind energy acceptance in Bavaria. We decided to analyze the Federal State of Bavaria in Germany as its current policy governance decelerates the building-up of wind turbines in this federal state. Using a qualitative approach, the results indicate that the perception of political processes, such as the recent enacting of the 10-H regulation in Bavaria, influences the acceptance towards wind energy, as trust and transparency in political processes are essential. In addition, the paper reveals the importance of the distributive justice, focusing in particular on the subitem envy, which can be considered on a neighboring or regional level. Additionally it reveals additional factors which are relevant for wind energy acceptance in the specific case of the analyzed federal state.
This paper describes an analysis of airborne wind energy system (AWES) and its comparison with conventional wind energy conversion system. The study highlights key perspectives of the altitude wind data as observed in the global scenario and its impact on a continuous and sustainable power generation system that can be located anywhere on land due to higher availability of prime mover at altitudes. An effort is made to highlight all key points of this emerging technology and its benefit to under-developed, energy-deficit countries in South Asia. Moreover, cost analysis of AWES shows a tremendous reduction in financial budget for an equivalent production rate of electricity due to higher capacity of the airborne harvesters.
In this paper the authors present basic considerations on conceptual kite design in terms of overall system performance of an airborne wind energy system. This kite design process has been developed at SkySails GmbH for the design of large scale traction kites for sea-going vessels. All aspects are first presented in a brief discussion and then applied to the SkySails kite system. Further examples are provided where applicable. This chapter starts by introducing theoretical approaches for determining maximum system performance and certain other aspects of kite aerodynamics with respect to the SkySails kite system. An overview of the limitations considered during the kite design process is also presented. In the following sections, the in uence of kite steering, launch and landing is discussed. Further, structural weight aspects are addressed. The last sections deal with the implications of ground handling on kites.
The main contribution of this paper is to indicate the economical viability of a Pumping Kite (PK) system as an airborne wind energy approach for large-scale electricity generation. In our study case a 2 MW PK unit is compared to a horizontal-axis 3-bladed Wind Turbine (WT) of same rated power. The PK airfoil area corresponds to the area of the 3 blades, and the same aerodynamic characteristics were assumed. The PK capacity factor obtained is 45 %, compared to 31 % of the WT. Given conservative PK cost estimates we found the investment in a PK-based wind farm can be 74 % of that in a conventional wind farm. By adding 13 PKs to an existing wind farm with 21 WTs the Internal Rate of Return (IRR) practically doubles, whereas if each WT is replaced by a PK, the IRR is approximately multiplied by 3. We also show that PK wind farms can be economically attractive in locations where WTs are not.
The mitigation of climate change requires reductions in the amount of CO2 emitted into the atmosphere. One way to achieve this in the short run is through the implementation of CO2 capture and storage (CCS) technology. The viability of CCS not only depends on technical and regulatory issues, but also on public attitudes. Communication plays an important role in shaping these attitudes. This paper reports on two experiments performed to examine effects of emphasis framing in CCS communications, meaning that greater weight is given to advantages of CCS over disadvantages or vice versa. Although emphasis framing can be effective in shaping attitudes, our findings suggest that there may be long-term costs to using this communication technique as it can be perceived as manipulative. Moreover, emphasis framing is judged as relatively illegitimate when the source is expected to be impartial rather than biased.
Researcher excitement about Airborne Wind Energy (AWE) technology matches DoD aims to advance and employ renewable energy. AWE seeks to cost-effectively tap the vast supply of wind energy that is available at altitudes high above the reach of conventional, ground-based wind turbines (e.g. 500-12,000 m). This paper explores the viability and implementation of AWE technology for fulfilling USAF energy needs. The characteristics, potential, and developmental status of the AWE resource are presented. Research suggests three huge advantages over ground based wind power: 30 times higher power density, 2-3 times more persistent winds, and 7-13 times smaller land use footprint. A design tool for a rotor-based AWE system is developed, facilitating the analysis of blade performance to simplify design and to provide the best efficiencies for a range of conditions. USAF bases are evaluated based upon energy needs, design requirements, and other factors to determine which bases could benefit most from AWE. Bases most viable for an AWE project, with potential savings of 75% in energy costs per base (up to $40M annually for larger bases), are: Tinker, Vance, Wright-Patterson, Arnold, Ellsworth, and Grand Forks. Key results reveal it is possible to achieve notable benefits for the USAF using AWE technology.
The acronym NIMBY , known to stand for ‘Not‐In‐My‐Back‐Yard’, generally describes resistance to siting specific projects close to one's area of residence while exhibiting acceptance of similar projects elsewhere. As wind energy continues to be recognized as a successful technology for meeting renewable energy targets and decreasing carbon dioxide emissions, the siting of wind turbines is a growing challenge that policy makers, facility planners, and wind developers face. The most often cited motivations for public support and opposition are reviewed here with a focus on wind energy developments in the United States. The purpose is to present the existing state of research on community responses to wind energy and to answer the following questions: What motivates support and opposition to facility siting, and in particular to wind energy facilities? Does the literature provide substantial evidence that NIMBYism is the determining motivation for opposition in the United States and, by extension, does the term's widespread use help to explain opposition? What mechanisms have been proposed for ‘overcoming’ NIMBYism , if it is present? This paper, following the recommendations of other social scientists, provides a collective call for a significant course shift: rather than proposing strategies to ‘overcome’ opposition, research should focus on proposing how to make siting successful. Drawing on a review of the relevant literature, the ‘ ENUF ’ framework—which stands for ‘Engage, Never use NIMBY , Understand, and Facilitate’—is introduced as a step in that direction. WIREs Clim Change 2013, 4:575–601. doi: 10.1002/wcc.250
This article is categorized under: Perceptions, Behavior, and Communication of Climate Change > Behavior Change and Responses
The Carbon Economy and Climate Mitigation > Policies, Instruments, Lifestyles, Behavior