Installation Of Offshore Wind Farms Research Articles

A computer tool for optimisation and simulation of marine operations for offshore wind farm installation

The installation process of offshore wind farms is complex and requires a high level of coordination, agile scheduling and systematic methods. High risks and costs are involved and especially weather conditions have an impact on the marine operations. A computer tool for optimisation and simulation of marine operations has been developed in close cooperation with a large actor in the offshore wind industry. The tool has a web-based user interface and an optimisation engine that is based on a version of a genetic algorithm and uses an agent-based simulation process to evaluate installation schedules with respect to weather risks, time and costs. The objective is to provide decision support for the early phase planning of wind farm installation by offering an efficient method for estimation of cost and time for future projects.

Dynamic Modeling of an Offshore Floating Wind Turbine for Application in the Mediterranean Sea

Wind power is emerging as one of the most sustainable and low-cost options for energy production. Far-offshore floating wind turbines are attractive in view of exploiting high wind availability sites while minimizing environmental and landscape impact. In the last few years, some offshore floating wind farms were deployed in Northern Europe for technology validation, with very promising results. At present time, however, no offshore wind farm installations have been developed in the Mediterranean Sea. The aim of this work is to comprehensively model an offshore floating wind turbine and examine the behavior resulting from a wide spectrum of sea and wind states typical of the Mediterranean Sea. The flexible and accessible in-house model developed for this purpose is compared with the reference model FAST v8.16 for verifying its reliability. Then, a simulation campaign is carried out to estimate the wind turbine LCOE (Levelized Cost of Energy). Based on this, the best substructure is chosen and the convenience of the investment is evaluated.

Development of offshore wind energy of Ukraine in the Sea of Azov: the geographical aspect

Formulation of the problem. Ukraine's energy sector is import-dependent, and one of the country’s sustainable development goals until 2030 is to ensure access to affordable, reliable, sustainable and modern energy sources. The wind potential of the mainland of our country has been thoroughly studied, so the focus of our interest is water areas, which are promising for the development of offshore wind energy. Offshore wind farms in Ukraine could improve the environmental situation and considerably contribute to the decarbonization of domestic energy. That is why the study considers the opportunity of offshore wind farms installation in the Sea of Azov. Methods. The analysis of literary and cartographic sources has been carried out. Mathematical methods have been used to calculate energy indicators. Using geoinformation modeling, taking into account limiting factors, suitable for the installation of offshore wind farms areas have been identified in the Sea of Azov. The purpose of the article is to geographically analyze the wind energy potential of the Sea of Azov with further assessment of the suitability of areas for the offshore wind farms location. Results. Our research has shown that the installation of offshore wind farms is appropriate in the Sea of Azov, because many areas are characterized by average annual wind speed above 6 meters per second. The most promising areas are the northern and northeastern coasts, where wind speed at different altitudes ranges from 8 to 9.3 meters per second. At altitudes of 50, 100 and 200 m, under the action of limiting factors, the most promising for offshore wind turbines areas are reduced by 8–22%. As considered limiting factors (territorial waters, nature protection objects, settlements and airports) have identical influence regardless of height, it is more effective to install wind turbines with a tower height of more than 100 m in the waters of the Sea of Azov. Interdisciplinary research is needed for the final answer on the effectiveness of offshore wind turbines in the Sea of Azov. Scientific novelty and practical significance. The results of the analysis of the wind energy potential of the Sea of Azov have been given, the tendency of its growth from the west to the east has been revealed. Attention has been paid to the method of geoinformation modeling of the location of offshore wind farms taking into account limiting factors. Maps of wind speed, potential of electricity generated by a single wind turbine and suitability of areas of the Sea of Azov for the location of offshore wind farms at an altitude of 200 m above sea level have been presented. These data can be used by designers of wind energy facilities as a basis for determining the optimal power of wind turbines and the type of energy for a particular area of the Sea of Azov.

Scheduling of Offshore Wind Farm Installation using Simulated Annealing

Abstract This paper focuses on the scheduling problem in the offshore wind farm installation process, which is strongly influenced by the offshore weather condition. Due to the nature of the offshore weather condition, i.e., partially predictable and uncontrollable, it is urgent to find a way to schedule the offshore installation process effectively and economically. For this purpose, this work presents a model based on Timed Petri Nets (TPN) approach for the offshore installation process and applies simulated annealing algorithm to find the optimal schedule.

Response of a self-powered offshore floating support structure with an OWC for powering a LIDAR device

To give an effective response to the increasing demand to characterise wind availability and intensity for the installation of future offshore wind farms, SPAR buoy OWCs with LIDAR present a clear benefit, due to their stability, mechanical and operational simplicity and lower cost, when compared to wind measuring towers, serving as an alternative to the latter, mainly for deep water.This paper proposes a compromise between a stable SPAR buoy for wind measurements (average speed, gusts, etc.) and a sufficiently capable energy generating OWC device for long-term self-sustainability. Key parameters such as mass distribution and geometry were accounted for, in order to achieve both outcomes.The performance of an oceanic SPAR buoy OWC was analysed numerically and experimentally tested at 1:16 scale, under regular and irregular sea states, in order to quantify its hydrodynamic behaviour and capability to generate electrical energy, using two different PTO configurations. Depending on the sea-states, different PTO configurations result in better performance. For higher significant wave heights, the 39% porosity membrane used as a PTO performed better from a power perspective, whereas for lower significant wave height, the 70% porosity membrane presented better results. Low energy consumption wind measuring equipment may benefit from this application.

Setting the Context for Offshore Wind Development Effects on Fish and Fisheries

Changes to fisheries that result from offshore wind farm (OWF) installations may be considered good or bad depending on various stakeholders’ perspectives. OWFs can act as artificial reefs that may benefit secondary fish production, but such effects may also have ecological consequences. The fisheries exclusion effect that turns some OWFs into no-go areas, hence effectively no-take zones, could provide resource enhancements or redistribution. However, the displacement of fishing effort may have consequences to fisheries elsewhere. Changes in the sensory environment related to sound, as well as electromagnetic fields and physical alterations of current and wind wakes, may have as yet unknown impacts on fisheries resources. Understanding the interactions among effect type, OWF development phase, and spatiotemporal population dynamics of commercial and recreational species remains chal-lenging, exemplified by the commercial fishery lobster genus Homarus in European and North American waters. While knowledge of the interactions between resource species and OWFs is improving, there remain questions on the wider interaction between and consequences of OWFs and fisheries. Studies of this wider relevance should aim to improve understanding of the economic and societal impacts of OWFs linked to ecosystem services that support fisheries. Furthermore, assisting fisheries management and providing advice requires monitoring and survey data collection at appropriate spatiotemporal scales. This information will help to determine whether OWFs have any meaningful impact on regional fisheries, and increased investments will be needed to target scientifically appropriate monitoring of OWFs and fisheries, which is supported by better integrated policy and regulation.

Comparison of Weather Window Statistics and Time Series Based Methods Considering Risk Measures

Offshore projects, like the installation of offshore wind farms, consist of a number of different and often weather dependent activities. These tasks and their relations are defined in project schedules, which have to be assessed for weather effects before the project realization. Here, often Weather Window Statistics are used to calculate probable weather delay times using relative frequencies of weather windows. Another possible approach is the Weather Time Series Scheduling (WaTSS) method which combines the given project schedule, weather restrictions and historical weather time series data for several decades. The aim of this paper is a comparison of the two approaches especially when it comes to risk analysis for project schedules using percentile values or related risk measures. The same ERA5 model data is used both as basis for the Weather Window Statistics and the WaTSS method. We calculate weather downtimes for each task, as well as for the total project, and apply the risk measures Value at Risk (VaR), Conditional Value at Risk (cVaR) and Upper Partial Moments (UPM). This is followed by an analysis of the results from Weather Window Statistics and the WaTSS method considering their applicability and consistence. We obtain that risk measurement for project schedules under use of Weather Window Statistics is not always practicable because certain risk values tend to overestimation. WaTSS method provides project adjusted modeling and leads to more realistic risk measurement for complex project schedules.

Sensitivity analysis of cost parameters for floating offshore wind farms: an application to Italian waters

Floating offshore wind farms represent the next frontier in wind power industry. However, the development of this technology is strongly dependent on its economic feasibility. There follows that the development of economic analyses is crucial to highlight the possible greater potential of floating offshore wind farms and to support their sustainability and technical value.In this context, the purpose of this paper is to present a sensitivity analysis of the main cost parameters for floating offshore wind farms, namely the distance from the coast, the distance from the closest port and the sea depth. It can give specific information on which parameters are more important, and how much they affect the total cost.To this aim, a comprehensive life cycle cost assessment of floating offshore wind farms has been developed. In this study the cost model has been applied to the Italian waters.The results shown should provide guidance on how to preliminary assess the quality of a given site for floating offshore wind farm installation, and should be helpful for future development of decision-making procedures in the offshore wind sector.

A spatial food web model to investigate potential spillover effects of a fishery closure in an offshore wind farm

There is a growing interest in the development of offshore wind farms to provide a sustainable source of renewable energy and contribute to the reduction of carbon emissions. In parallel, there is a need to better understand the effects of these installations on coastal marine ecosystems and identify potential sea use conflicts, especially when the area is subject to access restrictions. This study investigated the effects of a spatial closure during the exploitation phase of an offshore wind farm in the extended Bay of Seine (English Channel, France) using Ecospace, a spatially and temporally explicit module of Ecopath with Ecosim. To address this question, simulations were conducted through the evaluation of “what-if scenarios” to assess the effectiveness of a fishing exclusion zone inside and surrounding the offshore wind farm. Several biomass, catch and trophic level-based indicators were calculated to evaluate how the exclusion zone could affect fishing activities and main components of the food web. All the indicators were estimated in the extended Bay of Seine and summarized by sub-area. Findings suggested that the spillover effect could mitigate the negative impact of access loss on fishing activities, in a scenario of simulated closure of the area of the wind farm. The Ecospace model predicted an increase of catches (up to 7% near the wind farm) and a slight increase in the proportion of high trophic level species. However, the influence of spillover effects is limited in space and the expected increase of biomass and catches are highly localized in areas around the offshore wind farm installations. At the scale of the Bay of Seine, further analysis of the spillover effects revealed a spatial pattern and suggested that the implementation of an exclusion zone inside the offshore wind farm could concentrate highly mobile predators.

Organic matter assimilation by hard substrate fauna in an offshore wind farm area: a pulse-chase study

AbstractThe installation of offshore wind farms (OWFs) adds artificial hard substrates into naturally soft-bottom areas, changing the local biodiversity. The turbine foundations are rapidly colonized by colonizing organisms, mainly consisting of suspension feeders that can potentially reduce the local primary producer standing stock. In this study, we estimated the amount of organic matter processed by colonizing assemblages of OWFs. We conducted a laboratory pulse-chase experiment, by offering 13C-labelled fragmented microalgae to PVC panels colonized by OWF colonizing fauna. The blue mussel Mytilus edulis showed the highest biomass-specific carbon assimilation, while the high densities of the amphipod Jassa herdmani resulted in the highest total carbon assimilation. By upscaling our results to the total number of the installed offshore wind turbines in the Belgian part of the North Sea, we estimate that these species can reduce the local primary producer standing stock in the area by ca. 1.3%. Mytilus edulis and J. herdmani communities colonizing offshore wind turbine foundations significantly increase carbon assimilation compared to natural soft sediment macrofauna inhabiting the same surface area (i.e. footprint of the turbines).

Risk-based maintenance planning of offshore wind turbine farms

A risk-based maintenance planning for offshore wind farm installations is developed. Initially, the optimal number of monopile offshore wind turbines to be installed in an offshore wind farm is estimated, targeting a minimum levelised cost of energy. To this end, a sufficient number of design combinations for monopile support structure is generated by the design of experiment technique and then analysed based on the fatigue limit state. Following the fatigue reliability analysis performed for the monopile designs, an analytical relation between manufacturing cost and the structural safety regarding fatigue is developed to be used in the life-cycle cost analysis. The offshore wind farm is considered here as a system consisting of correlated components. The system reliability is estimated by using Ditlevsen bounding technique, which uses a time-variant correlation matrix of offshore wind turbines. The event tree method is employed to assess the expected cost of failure to be included in the capital investment as the structural risk premium, and the total expected cost to be included in the operational cost. Furthermore, different inspection policies are studied, and the most cost-effective inspection and maintenance policy is found for each studied wind farm. The present study also develops a novel framework for inspection and maintenance planning that maximises the benefits of performing inspections for a multi-unit system. Finally, the developed framework is applied to an offshore wind farm with sixty installations, and the detailed description of the planned inspections are discussed.

Observed onshore precipitation changes after the installation of offshore wind farms

The goal of this study is to assess the extent to which offshore wind farms can inadvertently affect precipitation at nearby onshore locations. As the winds slow down over an offshore wind farm due to the extraction of kinetic energy from the air flow by the turbines, a pattern of convergence upstream and divergence downstream of the farm is formed, which respectively may enhance precipitation offshore and reduce precipitation near the shore. To verify this hypothesis, we used observed precipitation data collected near two offshore wind farms in the western UK: Walney and Burbo Bank, built in 2011–2014 and 2005–2007, respectively. For each farm, we identified a “treatment” site, a meteorological station likely to be affected by the wake of the wind farm for a certain wind direction range, and a “control” site, unaffected by the farm for the same wind direction range. We used a difference-in-differences (DiD) approach between the precipitation data at the treatment and control sites before and after the construction of the wind farms to determine the net impact of the offshore farms on precipitation patterns at the shore. We found the following statistically significant signals at Walney after the construction of the wind farms: decreased wind speed (− 1.1 knots on average), reduced precipitation rate (− 0.003 mm/h), and reduced positive precipitation rate (i.e., only including hours with non-zero precipitation, − 0.080 mm/h). At Burbo Bank, wind speed and positive precipitation were reduced after the farm was built (− 1.45 knots and − 0.080 mm/h, respectively) with statistical significance, but no statistically significant drop in the hourly precipitation rate was found. All observed statistically significant changes were small in magnitude (order of 11% of the average or less). We speculate that, since Burbo Bank is very close to the shore (distance < 8 km), the divergence pattern cannot always form with sufficient strength to cause a precipitation suppression at the shore, which may explain the a less clear signal at that site. By contrast, the Walney farm is located ∼ 15 km away from the shore, which, we believe, is sufficient for the divergence zone to reach the shore.

Evaluation of Loading Bay Restrictions for the Installation of Offshore Wind Farms Using a Combination of Mixed-Integer Linear Programming and Model Predictive Control

The installation of offshore wind farms poses particular challenges due to expensive resources and quickly changing weather conditions. Model-based decision-support systems are required to achieve an efficient installation. In the literature, there exist several models for scheduling offshore operations, which focus on vessels but neglect the influence of resource restrictions at the base port and uncertainties involved with weather predictions. This article proposes a Mixed-Integer Linear Programming model for the scheduling of installation activities, which handles several installation vessels as well as restrictions about available cargo bridges at the port. Additionally, the article explains how this model can be combined with a Model Predictive Control scheme to provide decision support for the scheduling of offshore installation operations. The article presents numerical studies of the effects induced by resource restrictions and of different parametrizations for this approach. Results show that even small planning windows, paired with comparably low computational times, achieve reasonably good results. Moreover, the results show that an increase in vessels comes at diminishing returns concerning the installation efficiency. Therefore, the results indicate that available good-weather windows primarily limit efficiency.

A Review on the Planning Problem for the Installation of Offshore Wind Farms

Offshore wind farms provide a promising technology to produce renewable and sustainable energy. Nevertheless, the installation and operation of offshore wind farms pose a particular challenge to the planning and execution of operations. This article aims to identify requirements towards a decision support tool for the installation planning. Therefore, it provides a review of existing research in planning approaches and summarizes the overall planning problem. Afterwards this problem is decomposed into single tasks, according to their planning horizons. This decomposition shows a high level of interconnection between tasks across all levels. Higher levels provide constraints for the tasks on lower levels, while the results of these tasks are incorporated at higher levels. Finally, the article discusses the advantages and disadvantages of different approaches to solve these tasks.

Impedance-based analysis of harmonic resonances in HVDC connected offshore wind power plants

During the last years, the installation and planning of offshore wind farms using HVDC-links to transmit power onshore has increased. After the first HVDC connected offshore wind power plant of this type had been commissioned, the electrical harmonic resonance at the offshore AC grid was observed. The phenomenon leads to unwanted outages on both wind turbines and the HVDC transmission system. This paper aims to present the harmonic resonances in power-electronics dominated grids such as HVDC connected wind power plants. The study focuses on harmonic frequencies identification which are excited through the resonance phenomena between the elements of the offshore AC network including power converters. The paper presents a comparison of three different methodologies existing in the literature for harmonic resonance analysis including stability analysis. Moreover, we analyse the impact of the different power converter models application. The models and methods are validated in different test cases in order to determine the relationship of such resonances with respect to the grid topology.

Assessing impacts of offshore pile driving noise on the antipredator defense and shoaling behaviors of squid (Doryteuthis pealeii)

Impulsive pile driving occurs during construction of marine platforms, producing intense sounds that may adversely impact animals’ physiology and behavior. Little is known regarding how this noise impacts sound-sensitive invertebrates such as squid, which is surprising given squids’ relative abundance and key ecological role. We quantified how a commercially important squid species (Doryteuthis pealeii) behaviorally responded (in a controlled environment) to pile driving sounds recorded from an offshore windfarm installation within this species' habitat. Both sound pressure and particle motion components of the sound were quantified. Fifteen-minute portions of the recordings were played to individual squid. Body pattern changes, inking, jetting, and startle responses were observed during sound exposure and all squid exhibited at least one response. These responses occurred primarily during the first few noise impulses and diminished quickly over the first minute of playback, indicating short-term habituation. Responses returned after a 24-hr rest, indicating re-sensitization. Separate experiments investigated changes in shoaling behaviors by quantifying shoal cohesion and polarity in groups of squid during ten-minute noise exposures. Rapid habituation of antipredator alarm responses and changes in shoaling dynamics may alter squids’ susceptibility to predation. Noise exposure may also disrupt normal intraspecific communication and ecologically relevant behavioral responses to sounds.Impulsive pile driving occurs during construction of marine platforms, producing intense sounds that may adversely impact animals’ physiology and behavior. Little is known regarding how this noise impacts sound-sensitive invertebrates such as squid, which is surprising given squids’ relative abundance and key ecological role. We quantified how a commercially important squid species (Doryteuthis pealeii) behaviorally responded (in a controlled environment) to pile driving sounds recorded from an offshore windfarm installation within this species' habitat. Both sound pressure and particle motion components of the sound were quantified. Fifteen-minute portions of the recordings were played to individual squid. Body pattern changes, inking, jetting, and startle responses were observed during sound exposure and all squid exhibited at least one response. These responses occurred primarily during the first few noise impulses and diminished quickly over the first minute of playback, indicating short-term habituat...

Development of Offshore Wind Power: Contrasting Optimal Wind Sites with Legal Restrictions in Galicia, Spain

The region of Galicia, in the northwest of the Iberian Peninsula, has a high wind potential for the installation of offshore wind farms (OWFs) in many areas of its surrounding marine waters. However, legal restrictions derived from the protection of other interests that converge in the marine environment (such as fishing, navigation, and biodiversity conservation) must be considered, along with technical limitations resulting from water depth. This study is aimed at analysing legal restrictions on the installation of OWFs in Galician waters and at identifying those zones of less conflict where the wind power density (WPD) is greater and the depths and distances from the coast are technically feasible given the current status of technology in Europe. To do this, a legal study was performed of both the strategic environmental assessment of the Spanish coast and the regulations of the different marine sectors at European, international, national, and regional levels. In addition, the WPD along the north-western area of the Iberian Peninsula and Europe was calculated, and an analysis of maximum and average depths and distances from the coast of planned and installed OWFs in Europe was made. Two main zones without legal and technical restrictions were identified in the north-eastern corner of Galicia and in the south of the Vigo estuary. The greatest WPD was identified in the north-western zone, from Cape Finisterre to Cape Ortegal, where there are small sites without legal or technical restrictions that are near several protected zones (such as a marine reserve, a special protected area, and a wetland and its buffer zone), making necessary a deeper analysis of the specific impacts of each OWF project in the Environmental Impact Assessment.

A discrete-event simulation approach to evaluate the effect of stochastic parameters on offshore wind farms assembly strategies

The wind industry is facing new challenges due to the planned construction of thousands of offshore wind turbines all around the world. However, with their increasing distance from the shore, greater water depths, and increasing sizes of the plants, the industry has to face the challenge to develop sustainable installation procedures. Important limiting factors for offshore wind farm installation are the weather conditions and installation strategies. In this context, the focus of this research is the investigation of the most effective approach to installing offshore wind farms at sea, including the effects of weather conditions. This target is achieved through the implementation of a discrete-event simulation approach which includes the analysis of the environmental conditions, distance matrix, vessel characteristics, and assembly scenarios. The model maps the logistics chain in the offshore wind industry. A deterministic and a probabilistic metocean data method have been compared and cross validated. The results point to a good agreement between the two considered models, while highlighting the huge risks to the time and cost of the installation due to the stochastic nature of the weather. We suggest that simulations may improve and reduce these risks in the planning process of offshore wind farms.

Resource Sharing in the Logistics of the Offshore Wind Farm Installation Process based on a Simulation Study

This present contribution examines by means of a discrete event and agent-based simulation the potential of a joint use of resources in the installation phase of offshore wind energy. To this end, wind farm projects to be installed simultaneously are being examined, the impact of weather restrictions on the processes of loading, transport and installation are also taken into consideration, and both the wind farm specific resource allocation and the approach of a resource pool or resource sharing, respectively, are being implemented. This study is motivated by the large number of wind farms that will be installed in the future and by the potential savings that might be realized through resource sharing. While, so far, the main driver of the resource sharing approach has been the end consumer market, it has been applied in more and more areas, even in relatively conservative industries such as logistics. After the presentation of the backgrounds and of the underlying methodology, and the description of the prior art in this context, the network of the offshore wind energy installation phase will be described. This is the basis for the subsequent determination of the savings potential of a shared resource utilization, which is determined by the performance indicators such as the total installation time and degree of utilization of the resources. The results of the simulation show that weather restrictions have a significant effect on the installation times and the usage times of the resources as well as on their degree of utilization. In addition, the resource sharing approach, has been identified to have significant savings potential for the offshore wind energy installation.

A mixed-method optimisation and simulation framework for supporting logistical decisions during offshore wind farm installations

With a typical investment in excess of £100 million for each project, the installation phase of offshore wind farms (OWFs) is an area where substantial cost-reductions can be achieved; however, to-date there have been relatively few studies exploring this. In this paper, we develop a mixed-method framework which exploits the complementary strengths of two decision-support methods: discrete-event simulation and robust optimisation. The simulation component allows developers to estimate the impact of user-defined asset selections on the likely cost and duration of the full or partial completion of the installation process. The optimisation component provides developers with an installation schedule that is robust to changes in operation durations due to weather uncertainties. The combined framework provides a decision-support tool which enhances the individual capability of both models by feedback channels between the two, and provides a mechanism to address current OWF installation projects. The combined framework, verified and validated by external experts, was applied to an installation case study to illustrate the application of the combined approach. An installation schedule was identified which accounted for seasonal uncertainties and optimised the ordering of activities.