Near-shore Wind Farm Research Articles

Autonomous thermal tracking reveals spatiotemporal patterns of seabird activity relevant to interactions with floating offshore wind facilities

Planning is underway for placement of infrastructure needed to begin offshore wind (OSW) energy generation along the West Coast of the United States and elsewhere in the Pacific Ocean. In contrast to the primarily nearshore windfarms currently in the North Atlantic, the seabird communities inhabiting Pacific Wind Energy Areas (WEAs) include significant populations of species that fly by dynamic soaring, a behavior dependent on wind and in which flight height increases steeply with wind speed. Therefore, a more precise and detailed assessment of their 3D airspace use is needed to better understand the potential collision risks that OSW turbines may present to these seabirds. Toward this end, a novel technology called the ThermalTracker-3D (TT3D), which uses thermal imaging and stereo vision, was developed to render high-resolution (on average within ±5 m) flight tracks and related behavior of seabirds. The technology was developed and deployed on a wind-profiling LiDAR buoy in the Humboldt WEA, located 34 to 57 km off California’s coast. During the at-sea deployment between 24 May and 13 August 2021, the TT3D successfully tracked birds moving between 10 and 500 m from the device, around the clock, and in all weather conditions; a total of 1407 detections and their corresponding 3D flight trajectories were recorded. Mean altitudes of detections ranged 6-295 m above sea level (asl). Considering the degree of overlap with anticipated rotor swept zones (RSZ), which extend 25-260 m asl, 79% of detected birds (per m3 of airspace) moved below the RSZ, 21% moved at heights overlapping the RSZ, and another 0.04% occurred at heights exceeding the RSZ. The high-resolution tracks provided valuable insight into seabird space use, especially at heights that make them vulnerable to collision during various environmental conditions (e.g., darkness, strong winds). Observations made by the TT3D will be useful in filling critical knowledge gaps related to estimating collision and avoidance between seabirds and OSW facilities in the Pacific and elsewhere. Future research will focus on enhancing the TT3D’s identification capabilities to the lowest taxon through validation studies and artificial intelligence, further contributing to seabird conservation efforts associated with OSW.

Comprehensive layout optimization of the transmission system in a deepwater wind farm cluster

Compared to nearshore wind farms, deepwater offshore wind farms have better wind resources and broader development space and will be the main trend of wind power development in the future. Due to the long distance from the shore, the investment and operation costs of the transmission system in a deepwater wind farm cluster are high and the electricity generated by the cluster is commonly transmitted by high-voltage direct current transmission technology to decrease power losses. For a given converter station, the comprehensive optimization of the layouts of the substations, AC export cables from the substation to the converter station, and cable arrays within each wind farm are complex and have not been well studied. This paper proposes a multi-level nested optimization strategy to minimize the total cost of the collection cables for a deepwater offshore wind farm cluster. The proposed method applies the Informed-RRT* method to optimize the layout of AC export cables while the cable arrays are arranged by Prim’s algorithm. During the optimization process, the gradient descent algorithm is used to optimize the positions of the substations, obtaining the transmission system scheme with the minimum cable investment. For a certain deepwater wind farm cluster, the total cable cost after optimization is reduced by 3.58%, which indicates the effectiveness of this method.

Danish nearshore wind energy policy: Exploring actors, ideas, discursive processes and institutions via discursive institutionalism

AbstractThis article explores Danish renewable energy policy and policymaking, focusing on the development of nearshore wind energy and the role played by various actors, their competing ideas, the discursive processes in which they participate, and the institutional settings where exchanges occur. The research employs a case study design, concentrating on the Vesterhav Syd nearshore windfarm project. Drawing on semi‐structured interviews, the paper exploits Discursive Institutionalism and one of its recent refinements, labelled Ideational Power that highlights power over, through and in ideas. The data gathered provides compelling evidence of the ways in which actors struggle for dominance, each seeking to persuade others of their preferred policy problem definition and solutions: a process that oscillates between highly technical coordinative discourses among government agencies and business organisations and more politicised communicative discourses among a wider set of actors that includes community groups. Significantly, this case reveals the power of various policy stakeholders in Danish energy policy, suggesting that once decisions are taken at the national level of governance to construct a windfarm, only limited influence can be exerted by local groups on the outcomes. Our findings raise wider questions about such processes beyond the Danish case.

Technology costs for the first wave of wind farms in Vietnam: Paying extra for better wind nearshore

Technology analysts often dichotomize wind power projects as onshore vs offshore. They neglect nearshore projects installed in the intertidal flats. We explore the characteristics of this intermediate category using an original sample of Vietnam's wind power projects for the 2018–2021 period. The median investment for onshore wind power projects in Vietnam is 1695 USD/kW. It is 2011 USD/kW for nearshore projects. Nearshore wind-power generation capacity requires about 20 % more investment per MW than onshore, inter-quartile range of 0 % – 45 %. Nevertheless, nearshore projects remain much less capital-intensive than far-offshore projects – projected at 3150 USD/kWh in Vietnam based on experience in OECD countries with fixed-bottom projects. Escaping the onshore vs offshore dichotomy allows us to consider a different policy direction for the industry. Rather than pursuing bluefield mega-projects far offshore, a “small steps” policy to extend nearshore wind farms may be cheaper, faster, and more institutionally feasible.

Tourists are people too: Nonresidents’ values, beliefs, and acceptance of a nearshore wind farm

Decision makers frequently voice concerns regarding potential impacts of offshore wind development to coastal tourism; yet, little research has tracked tourists' attitudes towards an offshore wind project over time. In this study, an intercept survey captured viewpoints of visitors to and seasonal residents of Block Island (U.S.A.) prior to, during, and after construction of a nearshore, five-turbine development. A novel two-item measure reveals increased levels of acceptance over time and positive correlations between acceptance and having seen construction activities or the completed project. Regression and path analyses are consistent with values-beliefs-norms (VBN) theory, with underlying values (particularly altruism) and beliefs about the ocean and effects of the wind energy development explaining a substantial share of tourists' acceptance of the project. These findings suggest that rather than following narrow desires for an uninterrupted seascape, tourists’ responses to offshore wind energy developments are influenced by deeper beliefs and guiding principles.

Layout optimization of offshore wind farm considering spatially inhomogeneous wave loads

Monopile-supported wind turbines are usually placed in a harsh ocean environment and wave load becomes a major consideration in the nearshore wind farm design. Affected by the coastal geography and seabed terrain, the wave field inside a wind farm is usually spatially inhomogeneous and the wave load on each turbine can be greatly different. However, current practice for wind farm layout design is based on a passive strategy in which the layout is determined first, then followed by the wave load calculation and support structure design. Such a passive design strategy does not take inhomogeneous wave loads into consideration and may inappropriately place some turbines into the intense wave load regions, e.g., high wave or breaking wave zones, which is uneconomic and even risky for structural safety. In this paper, a novel coupling approach considering inhomogeneous wave loads on monopile-supported wind turbines in wind farm layout optimization is presented. The main goal is to arrange all turbines in an optimal layout, in which the total wave load of the wind farm is minimized while simultaneously maintaining the favorable AEP (annual energy production). The inhomogeneous wave field is characterized using either an analytical wave model or a numerical wave model. The wind energy production and wave loads are investigated and coupled in the layout optimization. A user-defined knockdown coefficient is employed in the coupling optimization to allow the users to customize the exact tradeoffs between AEP and wave load. The optimization is driven by the Multistart algorithm to efficiently approximate the best layout. It is discovered that the coupling optimization shows apparent benefits in producing satisfactory layouts, in which the total wave loads are significantly reduced by 20.1%-40.5% while maintaining a favorable amount of AEP. The presented coupling approach provides a useful alternative optimization strategy for offshore wind farm layout design to reduce the costs related to wave loads, especially in the harsh sea regions.

Contentious governance around climate change measures in the Netherlands

ABSTRACT Conflicts over mitigation measures involve processes of contentious governance in which governmental and non-governmental players contest policies proposed or implemented by other governmental players or their business partners. Comparing a case of carbon capture and storage (CCS) with that of a nearshore windfarm in the Netherlands, I ask: how did local governmental players and their non-governmental allies succeed in getting the CCS project in Barendrecht taken off the table, while unable to block plans for the nearshore windfarm off the coast of Katwijk, Noordwijk and Zandvoort? Focusing on persuasion, I find that rhetorical framing based on expertise and ‘not in my backyard’ (NIMBY) escapist framing did not make much difference in either case. In the CCS case, a process of scaling up procedural critique to the national level led to repeal of the plan. A similar process did not happen in the windfarm case.

An economic assessment of near-shore wind farm development using a weather research forecast-based genetic algorithm model

Faced with the impacts of climate change, countries around the world are striving to adopt renewable sources of energy in order to reduce their emission of CO2 gases. There are several planned onshore wind farms at advanced stages that are soon to be made operational, but there is an increasing issue in the form of land area scarcity, hence highlighting the importance of alternatives scenarios offshore. In this paper, a methodology is proposed for assessing and optimizing wind turbines placement in offshore wind farms. In this research, the design method considers the optimal wind farm location and wind turbine layout, developed using an approach that couples a Weather Research and Forecasting (WRF) mesoscale model with a Genetic algorithm (GA). Even though increased numbers of turbines result in greater energy production, wake effects are seen to cause steeply increasing marginal costs. A comparative cost study is further performed for the different arrangements; GA model, linear line and block arrangement. It is first demonstrated that optimizing wind farm layout with the GA results in somewhat lower installation cost (4.4%) than a standard linear wind farm arrangement. The GA is then used to optimize layouts for increasing numbers of wind turbines and generate a full marginal cost (or supply) functions for wind energy at the case-study site. Turbine density is thus shown to be a critical consideration for wind farm economics at the study site. The methods presented in this study are easily adaptable to offshore wind farm design and economic assessment in other locations.

Local government innovation in the energy sector: A study of key actors’ strategies and arguments

Local governments will play an important role in the transition towards fully renewable energy systems. In order to develop new roles for themselves in climate and energy planning, they have to be creative and find new ways of acting within existing regulatory frameworks. The objective of this paper is to explore the kinds of arguments and discussions local key actors use and encounter when developing innovative activities. We study two exemplary cases using a qualitative research approach based on interviews with key informants: a municipality-owned nearshore wind farm, and a local funding scheme for energy-efficiency refurbishment in single-family houses. Our findings indicate that i) innovative projects grow out of the momentum of previous visions and experiences; ii) key actors balance ‘green’ and economic arguments in order to gain project approval; and iii) innovative projects can sometimes only be realized by drawing on resources from outside the municipal sphere. Even though committed key actors may be successful, it is worth considering how the grip of narrow economic motives can be loosened in order to support the local experimentation and innovation that will become more and more important in green energy transitions.

Local support for renewable energy technologies? Attitudes towards local near-shore wind farms among second home owners and permanent area residents on the Danish coast

This paper documents different attitudes towards local renewable energy technology (RET) projects in Denmark among two key RET stakeholder groups, permanent area residents (PRs) and second home owners (SHOs). It does so via survey data collected from almost 2000 respondents during a Danish near-shore wind farm tender. Judging by this data, local PRs are positive towards the planned local RETs, while SHOs are less so. This emphasizes that potential RET project stakeholders and stakeholder groups may have very different RET project perceptions and opinions. The planned RET projects were subject to widespread critique in the public and political RET project related debate, but the documented PR RET project support was rather silent support. This is a noteworthy inconsistency calling for further research. Drawing upon research insights from the interdisciplinary socially focused energy transitions body of literature, the paper suggests that particular uses of and attachments to particular places may inform stakeholder perceptions of RET related local change. The research findings have significant implications for RET planning, practice and policy more broadly.

The post-normal politics and science of wind power planning: Evidence from a Danish near-shore wind farm tender

Post-normal science (PNS) has long advocated the inclusion of stakeholders in scientific processes where there is uncertainty, urgency and high stakes. Increasingly, however, such conditions have become recognised as the norm. Using the theoretical perspective of PNS, we examine the interactions between public objection, unstable coalition politics and uncertain environmental assessment knowledge to understand the case study of a Danish near-shore wind farm tender. In this case the original distinction made by PNS between facts, judgements, politics and science are confirmed as difficult to separate in what has been described as a condition of post-normal politics. The case, taking place within Denmark’s relatively transparent and inclusive wind power governance system, offers insights into the challenges of managing long-term environmental and energy policy objectives. However the case also demonstrates the challenges to the policy prescriptions of PNS, specifically regarding the notion of extended peer review communities (EPCs). Here we propose that the de facto condition for energy siting controversies is one of multiple, often self-organised EPCs.

Barriers and Recommendations to Innovative Ownership Models for Wind Power

Local ownership models have proven to be an important way to avoid local resistance to onshore wind turbines. As wind power expands into onshore and nearshore wind farms, such ownership models become of increasing importance, while also undergoing further development. This paper uses the Choice Awareness theory to examine some of the barriers connected to the implementation of these new ownership models and presents recommendations to overcome such barriers. Choice Awareness addresses societal aspects (discourse, socioeconomics, and public regulation) mainly related to implementing alternatives to existing technologies. For the theory to be able to embrace the complexity of the transition of the energy system more holistically, we explore and specify the organizational dimension of choice-eliminating mechanisms. Based on the case of an NGO’s attempt to bid for a tender for nearshore wind turbines, it is shown how the central administration prevents new innovative ownership models from entering the tender. A strong path dependency has led to a conscious or unconscious elimination of projects based on organizational structures that do not fit the definition of large energy companies. As a result of this, the paper makes three recommendations for policy changes with the aim to secure equal possibilities for actors involved in nearshore wind power tenders.

Investigation of the Fetch Effect Using Onshore and Offshore Vertical LiDAR Devices

An offshore wind measurement campaign using vertical light detection and ranging (LiDAR) devices was conducted at the Hazaki Oceanographic Research Station (HORS) as part of an investigation into determining the optimal distance from the coast for a nearshore wind farm from a meteorological perspective. The research platform was a 427 m long pier located on a rectilinear coastline on the Pacific coast of the central Honshu Island in Japan. The relationship between the ratios of the increase of wind speed near the surface and fetch length within 5 km of the coast was analyzed via LiDAR observations taken at heights from 40 to 200 m. The results showed that the speed of the coastal wind blowing from land to sea gradually increased as the fetch length increased, by approximately 15–20% at 50 m above sea level around a fetch length of 2 km. Moreover, empirical equations were derived by applying the power law to the relationship between the increase of wind speed and fetch lengths at 1–5 km, as obtained from the LiDAR measurements. It was also found that the wind speed increase at a 2 km fetch length was equivalent to the effect of a 50–90 m vertical height increase on the coast in this region.

Effective soil-stiffness validation: Shaker excitation of an in-situ monopile foundation

In an attempt to decrease the modelling uncertainty associated with the soil-structure interaction of large-diameter monopile foundations, a hydraulic shaker was used to excite a real-sized, in-situ monopile foundation in stiff, sandy soil in a near-shore wind farm. The response in terms of natural frequency and damping of a pile-only system is significantly more influenced by the soil than a full offshore wind turbine structure, and therefore ensures a higher degree of certainty regarding the assessment of the soil reaction. Steady-state vibration amplitudes with frequencies between 1 and 9Hz were retrieved from strain gauges vertically spaced along the embedded pile, and accelerometers attached to the top of the pile and to the shaker. The measured response is used to validate an effective 1D stiffness method, which is applied as a smart initial guess for a model-based identification of the effective soil-structure interaction properties in terms of stiffness, damping and soil inertia. The performance of the stiffness method is compared to the currently employed p-y stiffness design method. While the effective stiffness method seems to overestimate the actual low-frequency stiffness with about 20%, the p-y method appears to underestimate this stiffness with 140%. The assumption of linear soil behaviour for most of the occurring pile displacements is shown to be acceptable. A damping ratio of 20% (critical) is identified as effective soil damping for the monopile, which is estimated to correspond to a 0.14% damping ratio contribution from the soil for the full structure. The unique measurement setup yielded a ‘first-off’ opportunity to validate a soil-structure interaction model for a rigidly behaving pile. We have shown that indeed such a pile reacts stiffer than predicted by the p-y curve method, and that its response can be modeled more accurately with our recently developed effective stiffness method.

Optimal Expansion of a Hydrogen Storage System for Wind Power: A Real Options Analysis

This paper presents a real options-based techno-economic analysis of a hydrogen-based wind energy storage system (H2-WESS) deployed adjacent to a nearshore wind farm in northern Germany. The H2-WESS can be used to produce and store hydrogen when feed-in management takes place, in order to avoid the shutdown of wind turbines during times of excess electricity supply, or when the spot market electricity price falls below the estimated (efficiency-adjusted) market price of hydrogen. Moreover, an H2-WESS can provide negative minute reserve capacity. The modular design of the H2-WESS gives an investor the option to expand the capacity and gradually adapt to changing market conditions. The comprehensive and novel simulation model considers all relevant volatile inputs, such as stochastic wind conditions, feed-in management events, prices, and minute reserve calls. By means of a Monte Carlo simulation, annual revenues and their volatility are computed with a view on projected technology improvements until 2030. Based on the simulation results, a binomial real options pricing model is used to design four interdependent binominal trees and to evaluate a Bermuda-type compound expansion option. The decision trees, in which the investor can choose the maximum of the option to either upgrade the H2-WESS to the next expansion stage or to keep the real option alive, feature 390 time steps and 76,050 decision nodes each. Each compound decision takes the option of a smaller expansion stage explicitly into account. The compound expansion option to invest in a 5, 10, 15, or 20 MW H2-WESS has a 15-year expiration time and is found to have a value of about €2 million, compared to the net present value of a 5 MW H-WESS of about €-2.45 million. We conclude from the real options analysis that for a realistic valuation of modular energy projects subject to various uncertainties it is crucial to incorporate the value of managerial flexibility that is influenced. Due to the modular design, and in contrast to conventional power plants, the flexibility of the H2-WESS comprises many specific options.

Analysis of the reduced wake effect for available wind power calculation during curtailment

With the increase of installed wind power capacity, the contribution of wind power curtailment to power balancing becomes more relevant. Determining the available power during curtailment at the wind farm level is not trivial, as curtailment changes the wake effects in a wind farm. Current best practice to estimate the available power is to sum the available power calculated by every wind turbine. However, during curtailment the changed local wind conditions at the wind turbines lead to inaccurate results at the wind farm level. This paper presents an algorithm to determine the available power of a wind farm during curtailment. Moreover, results of curtailment experiments are discussed that were performed on nearshore wind farm Westermeerwind to validate the algorithm. For the case where a single turbine is being curtailed, it is shown that the algorithm reduces the estimation error for the first downstream turbine significantly. Further development of the algorithm is required for accurate estimation of the second turbine. All further downstream turbines did not experience a change in wake conditions.

Optimal expansion of a hydrogen storage system for wind power (H2-WESS): A real options analysis

Increasing penetration of wind energy in Germany challenges the transmission and distribution grid operators to ensure the sustained feed-in of wind energy. Energy storage technologies have become a widely discussed solution to balance intermittent electricity supply and demand. This paper introduces an economic real options-based analysis of a hydrogen wind energy storage system (H2-WESS) deployed adjacent to a nearshore wind farm in northern Germany. The H2-WESS can be used to produce and store hydrogen when feed-in management occurs to avoid the shutdown of wind turbines and when the spot market electricity price falls below the estimated (efficiency-adjusted) market price of hydrogen. Moreover, an H2-WESS can provide negative minute reserve capacity. The modular design of the H2-WESS gives an investor the option to expand its capacity and react to new project developments. A comprehensive simulation model considers all relevant volatile inputs such as stochastic wind conditions, feed-in management events, prices, and minute reserve calls. By means of a Monte Carlo simulation, the annual revenues and their volatility are computed with respect to forecasted technology improvements till 2030. On the basis of the simulation results, a binomial options pricing model is used to design four interdependent binominal trees and to evaluate a Bermuda-type compound expansion option. The decision trees, in which the investor can choose the maximum of the option to either expand to a further H2-WESS stage or to keep the option alive, uses 390 time steps and 76,050 decision nodes each. Every compound decision takes the option of smaller stages into account. The compound expansion option to invest in a 5, 10, 15 or 20 MW H2-WESS has a 15-year expiration time and is calculated to be about €2 million, compared to the net present value of a 5 MW H-WESS of about €-2.45 million. We conclude from the real options analysis that it is crucial for a realistic valuation of energy projects to incorporate the value of managerial flexibility that is influenced by various uncertainties. Compared to conventional power plants, and due to the modular design, the flexibility of the H2-WESS comprises many specific options.

Nearshore Wind Resistance on Denmark’s Renewable Energy Island

The Danish island Samsø is world-famous as Denmark’s Renewable Energy Island. 21 wind turbines supply the island’s electricity. Today, public hostility toward a projected nearshore wind farm off the island’s preserved northern coast is growing. This paper takes its main theoretical cue from Gomart and Hajer’s (2003) call to open up political questions to empirical inquiry and to pay attention to the material settings in which political questions unfold. The paper seeks to make sense of the islanders’ unexpected opposition to a new wind farm, and it does so through a critique of the unexperimental and depoliticizing attitude – found in the empirical case as well as in some academic scholarship – of the NIMBY (Not In My BackYard) logic. Replacing the NIMBY logic of closing down deliberation with an empirical and ‘cosmopolitical’ (Stengers, 2005) approach to open up the space of politics to close investigation, the paper focuses on the empirical settings which give the controversy its specific shape and asks how the projected wind farm is interrogated, negotiated and recast as it travels through the socio-material politics of the wind controversy.

Effective stiffness method for rigid monopile foundations of offshore wind turbines and in-situ validation

It is widely accepted that the initial stiffness derived with the p-y methodology as prescribed by the American Petroleum Institute does not capture the true small-strain stiffness for rigidly behaving piles. We present an alternative method, capturing the 3D effects in the soil-pile interaction, in which the soil is characterized with in-situ seismic measurements. As the design of the foundations of offshore wind turbines often involves many expensive load simulations (load cases), the method also includes finding an effective 1D or Winkler stiffness yielding a similar pile response as in the 3D model. The method is exemplified for a real 5 m-diameter monopile embedded in stiff dense sand, in a near-shore wind farm in The Netherlands. The dynamic properties of this pile have been tested (prior to installation of the super-structure) with a unique measurement setup using a hydraulic shaker, exciting between 1 and 9 Hz. The response of this stand-alone pile is highly sensitive to the soil and allowed us to verify the effective 1D stiffness with much higher certainty as opposed to the usual situation including dynamic disturbances and uncertainties related to the interaction with the super-structure. The effective soil damping of the pile is estimated, and the performance of both the standard design (p-y) stiffness method and the proposed effective stiffness method is assessed in view of the measured strains and accelerations.

Hearing characteristics of cephalopods: modeling and environmental impact study.

Cephalopods (octopus, squid and cuttlefish) are some of the most intriguing molluscs, and they represent economically important commercial marine species for fisheries. Previous studies have shown that cephalopods are sensitive to underwater particle motion, especially at low frequencies in the order of 10 Hz. The present paper deals with quantitative modeling of the statocyst system in three cephalopod species: Octopus vulgaris, Sepia officinalis and Loligo vulgaris. The octopus's macula/statolith organ was modeled as a 2nd-order dynamic oscillator using parameter values estimated from scanning electron micrograph images. The modeling results agree reasonably well with experimental data (acceleration threshold) in the three cephalopod species. Insights made from quantitative modeling and simulating the particle motion sensing mechanism of cephalopods elucidated their underwater particle motion detection capabilities. Sensitivity to emerging environmental issues, such as low frequency noise caused by near-shore wind farms and increasing levels of carbon dioxide in the ocean, and sensitivity to sounds produced by impending landslides were investigated in octopus using the model.