bluuebunny/crossref_metadata_2025_split huggingface dataset:
Overview of the potential of floating wind in Europe based on met-ocean data derived from the ERA5-dataset
Authors: Messmer Thomas , Ran Xiaoming , Benifla Victor , Lutz Marco , Adam Frank , Bachynski-Polić Erin E. , Hölling Michael 
Published: November 2023

Abstract
This paper provides an overview of the potential of floating wind in Europe. Wind and wave data from the ERA5 dataset as well as bathymetry data are analysed to identify regions suitable for floating wind deployment. The most promising areas are quantified according to different characteristics (wind resource, bathymetry, distance to the coast). The wind resource is quantified in terms of averaged wind velocity and wind availability at 100 m height above sea level. The results show the great potential of Ireland, Iceland, Norway and the United Kingdom. Indeed, a large part of the seas of these countries is located in water depths between 60 and 1000 meters and has a very high wind resource despite stronger wave conditions than in other countries. In addition, Spain, France, Sweden, Finland and Greece all exhibit good potential.
Triple-lidar measurements of wind across a virtual rotor plane over a sea surface
Authors: Nafisifard M , Jakobsen J B , Snæbjörnsson J T , Sjöholm M , Mann J 
Published: November 2023

Abstract
An improved understanding of the spatiotemporal characteristics of the wind velocity field above the sea surface will benefit the design of modern offshore wind turbines. This study examines wind velocity data recorded on a bow-tie-like measurement pattern, approximately covering a rotor area diameter of about 70 m. The measurement data are obtained by triple continuous-wave Doppler lidars (short-range WindScanners). Two of the instruments are installed on a stable platform in the form of a suspension bridge deck, whereas the third is stationed on the ground nearby. Data from sonic anemometers installed above the bridge deck are used to validate the wind characteristics observed by the lidars. The lidar measurement data are explored in terms of wind flow mapping, mean flow characteristics and co-coherences. The results demonstrate the difference between the co-coherence at lateral and vertical separations and also differences from the coherence model in the IEC standard. The results further show the potential of lidar measurements to provide new insight into mean wind flow and turbulence characteristics applicable for offshore wind turbine design.
Operational Expenditure Modelling of the X-Rotor Offshore Wind turbine concept: Sensitivity of Key Modelling Assumptions
Authors: Anderson Fraser , Carroll James , Leithead William 
Published: November 2023

Abstract
The focus of this paper is operational expenditure modelling of the novel X-Rotor offshore wind turbine concept. The X-Rotor presents significant opportunities for operational expenditure reduction. There are, however, numerous uncertainties associated with modelling of those costs. Namely; failure rates for a novel concept are difficult to quantify, and the design of the concept is still being refined. These uncertainties may be addressed via simple sensitivity analyses. Here, three such sensitivity analyses are presented: one focusing on the main bearing failure rate, one on the generator failure rate, and one exploring the provision of redundancy via the operational strategy of secondary rotors. The main bearing failure rate had a particularly significant impact on operations and maintenance costs, accounting for approximately 22% of costs under baseline assumptions. The generator was less impactful as a cost driver, accounting for approximately 10% of costs under baseline assumptions. Lastly, assuming the X-Rotor could operate at 50% capacity upon failure of one of the secondary rotors decreases the operational expenditure by 8% compared to full turbine unavailability.
On the Sensitivity of Wind Turbine Failure Rate Estimates to Failure Definitions
Authors: Anderson F , Dawid R , McMillan D , Cava D García 
Published: November 2023

Abstract
This study presents a wind turbine reliability analysis at the turbine and assembly level. It is concerned with the uncertainties associated with data-processing for wind turbine failure rate figures. These uncertainties are prominent in discussions of failure data in the literature. In particular, the influence of different failure definitions on failure rate estimates are investigated. The baseline estimate is 9.06 failures per turbine per year. This figure changes significantly when introducing a lower downtime limit, repair limit or limit on time between subsequent downtimes of the same turbine for a downtime event to be considered a failure. It changes significantly depending on which maintenance actions are categorised as corrective and by what data points represent an intervention. From the one dataset analysed here, results show derived failure rates ranging from below 1 failures per turbine per year to over 10 failures per turbine per year using failure definitions which have previously been used in the literature. When restricting failures to those that can be attributed to a particular assembly, the failure rate estimate reduces to 7.47 failures per turbine per year. Assemblies that fail the most are the frequency converter (at around 1 failures per turbine per year) and the cooling system (at around 0.9 failure per turbine per year). The gearbox, blades, yaw system and hydraulic group were the next most frequently failing assemblies.
Multi Rotor Wind Turbine Systems: An Exploration of Failure Rates and Failure Classification
Authors: McMorland Jade , Khisraw Abdullah , Dalhoff Peter , Störtenbecker Sven , Jamieson Peter 
Published: November 2023

Abstract
The Multi-Rotor System (MRS) is a proposed solution to the increasing costs associated with the manufacture and maintenance of large single-rotor wind turbines. The MRS consists of many small rotors that can capture the same amount of energy as a large turbine but with the added benefits of standardization, reduced system loads, and improved reliability due to the redundancy of components and smaller size. However, modelling the operation and maintenance (O&M) of the MRS presents several challenges, including a lack of available failure data. This work aims to determine, what failure rate reduction, can MRS be competitive with equivalent single-rotor wind farms, using existing single-rotor turbine data as a baseline. The key failure components are identified through the use of a cost-based comparison parameter. Statistical and theoretical approaches are then used to analyse the impact of fatigue on failure rates for downscaled turbines, to determine if the required reduction in failure rate is feasible. Using a case study, the sensitivity of availability, operational expenditure, and lost revenue to failure rates is also determined.
Effect of leading-edge erosion on the performance of offshore horizontal axis wind turbine using BEM method
Authors: Mian H H , Siddiqui M S , Yang L , Keprate A , Badar A W 
Published: November 2023

Abstract
This research focuses on the effect of leading-edge erosion on the performance of wind turbines, specifically the GE1.5XLE horizontal axis wind turbine. The blade element momentum (BEM) method is used to predict the performance of the eroded blade configurations, and the open-source code QBLADE is used for simulation. The importance of including the effects of blade erosion in the design phase is highlighted, as it can optimize turbine performance and ensure operational efficiency. The high blade tip velocity in large rotors, which can reach 90-110 m/s, makes them susceptible to sand and rain erosion, which can significantly affect the turbine’s performance. The research compares the performance of clean and eroded blade configurations, with different levels of leading-edge erosion as percentages of the chord (0.5%, 1.0%, 1.5%, and 2.0%). The results show that the worst-case scenario of 2.0% leading-edge erosion reduced the lift-to-drag ratio of an airfoil by 65% and reduced the power output by 20%. The low-fidelity analysis methodology presented in this research is fast and can be easily implemented in the early design phase of wind turbines to predict the effect of leading-edge blade erosion. This allows for cost-effective and efficient design solutions that take into account the effects of erosion on wind turbine performance. The research provides valuable insights for the wind energy industry to improve the reliability and performance of wind turbines.
Investigation of the effect of prescribed coupled motions on the power production of a floating offshore wind turbine
Authors: Ramponi R , Amaral R , Viré A 
Published: November 2023

Abstract
Floating offshore wind turbines are subjected to platform motions that modify the local velocity experienced by the rotor. This work analyzes how variations in the platform motions affect the aerodynamic power of a floating wind turbine. Idealized wind conditions and rigid wind turbine are considered. The platform motions are prescribed by the user and the coupled motions considered are pitch-surge, pitch-yaw and surge-yaw. The main novelties of the work consist in the fact that multiple motions are prescribed simultaneously, including yaw, and that the prescribed motions present a difference in phase. In absence of wind turbine controller, the pitch-surge coupling shows significant increase in average power production with respect to fixed conditions when either the amplitude or frequency are increased. This gain is maximum when surge and pitch are in phase, and is almost zero in phase opposition. The presence of the controller reverses the behavior and introduces a loss in average power along with increasing amplitudes. Phase shift analysis is particularly interesting in the surge and pitch cases: the controller introduces an upper limit in power, and phase opposition is now desirable. The yaw degree of freedom is shown to be of secondary importance in every condition.
Economic feasibility study for continued operation of German offshore wind farms
Authors: Walgern Julia , Baumgärtner David , Fricke Johannes , Requate Niklas , Kolios Athanasios , Dörenkämper Martin , Meyer Tobias , Vollmer Lukas 
Published: November 2023

Abstract
With a large number of wind farms already deployed in German waters and aiming to achieve a minimum of 70 GW of offshore wind capacity by 2045, investigating the potential for extended operation of existing assets is an important task. This paper documents the development of a life cycle cost/revenue framework capable of incorporating CAPEX and OPEX related elements, revenue factors, and deployment location specific aspects, in order to support decisions on the business case for continued operation beyond the nominal service life. The framework called ELSA (Economic Life cycle Simulation and Assessment) is applied to a cumulative scenario which classifies all existing offshore wind farms in Germany with respect to size and key dimensions. Outcomes of the analysis support the case for extended operation, while highlighting the importance of wake effects to AEP, the magnitude and variability of O&M costs and finally the influence of CAPEX and financial modelling.
Surrogate based sensitivity analysis and uncertainty quantification of floating wind turbine mooring systems
Authors: Dighe Vinit V. , Peeringa Johan , Hermans Koen , Swamy Siddharth Krishna , Bulder Bernard , Savenije Feike 
Published: November 2023

Abstract
A Floater module containing several empirical parameters has been added to the TNO’s Cost model in order to include the analysis of floating wind turbine support structures and mooring systems. It is of our interest to know which model parameters within the Floater module contribute most significantly to the mooring system costs and ultimately to the levelized cost of energy (LCOE). The strategy employed relies on constructing a surrogate model (based on Kriging), which is then used to perform global sensitivity analysis. For the scenarios studied here, it was found that the model parameter related to the mooring line breaking load coefficient remained the most sensitive to the capital expenditure (CapEx) cost, while the model parameter related to the failure event cost for mooring line repair remained most sensitive to the operational expenditure (OpEx) cost. Additionally, the study aimed at expanding the deterministic Cost model to systematically account for stochastic model parameter inputs in order to reduce modelling uncertainties and contribute towards more reliable mooring line designs.
Quantifying the effect of rock armour scour protection on eigenfrequencies of a monopile supported OHVS
Authors: Winkler K. , Weil M. , Sastre Jurado C. , Stuyts B. , Weijtjens W. , Devriendt C. 
Published: November 2023

Abstract
It is common practice to install scour protection systems during the construction of offshore wind farms. This is because the guidelines allow for a more optimal structural design, as the potential effects of scouring may be ignored. However, multiple sources, as well as measurements, suggest that there is an additional gain in stiffness which is not being taken into account by current guidelines. Scour protection has the ability to provide extra foundational stiffness to the monopile, which results in higher natural eigenfrequencies and mode shapes. In this paper the focus will be on an offshore high voltage station (OHVS) located in the North Sea and the impact of a rubble riprap scour protection on the foundational stiffness of the structure. Furthermore, a proposal is made on how to take these effects into account when calculating for design. This site was equipped with a mobile measurement system containing a multi-axial accelerometer, which was active in a period both before and after installation of the scour protection rock armour layer. In case of similar environmental circumstances, the eigenfrequencies of the OHVS were noticeably higher after the scour protection was installed, thus substantiating the claim of increased foundational stiffness. To perform numerical studies on the impact of the scour protection system on structural dynamics, an OHVS support structure finite element model was built. As no formally agreed upon formulation to include scour protection exists, two possible methods are proposed. One is adding a global accretion layer to model the scour protection as an additional soil layer. The other calculates an overburden pressure due to the scour protection weight, which translates to the stiffening of the upper soil layers of the foundation. Both methods have their own strengths and weaknesses, but more research on different locations and offshore structures is needed to formalize the definitive description for modelling scour protection.
Application of CFD on VIM of semi-submersible FOWT: A Case Study
Authors: Jiang Fengjian , Yin Decao , Califano Andrea , Berthelsen Petter Andreas 
Published: November 2023

Abstract
This study examines the Vortex Induced Motions (VIM) of the INO WINDMOOR 12 MW semi-submersible Floating Offshore Wind Turbine (FOWT) platform using three-dimensional Computational Fluid Dynamics (CFD). The results from both model- and full-scale simulations are presented. The model scale results reveal varying VIM performances at different current headings, with detailed flow visualizations and analyses of hydrodynamic loads on FOWT components providing insights into the underlying wake interaction scenarios. One simulation shows bifurcated VIM, where regular motions are intermittently interrupted due to simultaneous suppression of vortex shedding on all FOWT columns. Preliminary full-scale CFD results suggest a strong scale effect. The paper concludes with a discussion on how CFD simulation can be more effectively used in VIM research.
A study of the towing characteristics of a semi-submersible floating offshore wind platform
Authors: Ramachandran R. C. , Otter A. , Serraris JJ , Ridder EJ de , Desmond C. , Murphy J. 
Published: November 2023

Abstract
A robust pipeline of floating wind energy has emerged with a general trend of projects becoming larger, further from shore, and placed in increasingly energetic seas. The installation process for these farms involves the pre-assembly of components onshore or in sheltered waters before towing the platform to the operational location using tugs. It can be expected that such marine operations will be repeated in reverse at the time of decommissioning. The cost and safety of these operations will be influenced by the tugs used, towing speed, the local metocean conditions, the platform/turbine characteristics and other factors. This paper investigates the hydrodynamic characteristics of a large semi-submersible floating offshore wind turbine (FOWT) under tow. The motions of the FOWT are analysed using a numerical tool and validated using a towing test. A framework is proposed for the assessment of FOWT towing operations. Various limiting factors have been identified and the hydrodynamic performance of the system has been evaluated using the framework.
Mitigation of assembly constraints for floating offshore wind turbines using discrete event simulation
Authors: Smith B Moverley , Ongley J , Angeloudis A , Thies P R 
Published: November 2023

Abstract
There is a large and increasing pipeline of floating offshore wind projects with total global floating offshore wind capacity projected to grow year on year by, on average, between 59 and 104 % in the 2020s. This will lead to competition for infrastructure resources, in particular, port facilities for the construction and marshalling of the floating foundations and turbines. It is likely that multiple ports will need to be combined to provide the necessary fabrication capacity for a floating offshore wind farm of commercial scale. To enable an efficient and coordinated utilisation of multiple fabrication ports, it is crucial to understand the likely duration of different assembly and construction activities at different locations. However, at present this task is difficult to perform using top-down estimation models, as commercial-scale floating offshore wind farms comprising many tens of units have not been built to date. In this work we present a methodology, based on discrete event simulation (DES) and time series analysis, to produce an explicit simulation-based estimate of assembly activity durations, which are sensitive to setting specific factors. Three example case studies are outlined to demonstrate the ability to capture the variation in activity duration due to resource availability, and the season and location of activity. The methodology will be of use to project planners as it can be used at an early stage in the project life-cycle to appraise and adopt different construction strategies.
Effects of negative shear on loads for a 15 MW offshore wind turbine during low-level jet events
Authors: Ahmed Fahim Masud , Paskyabi Mostafa Bakhoday 
Published: November 2023

Abstract
Wind turbines are more often interacting with the negative shear region of a low-level jet due to increasing turbine sizes. However, the effects of negative shear on wind turbines are not sufficiently studied, particularly for offshore wind applications. In this paper, we studied the effects of negative shear on wind turbine loading. This was done using user-defined wind profiles and a model chain. The model chain consisted of a turbulence generator and a wake modelling tool coupled to an aero-hydro-servo-elastic engineering tool. We observed significant variations in the structural loading in the case of low-level jets. We also observed changes in the power spectral density estimates. Additionally, we briefly examined the wake recovery distance.
Design and costs benefits of shared anchors and shared mooring lines of floating wind turbines at farm level
Authors: Chemineau M , Castillo F , Mechinaud L , Arramounet V , Gilloteaux J C 
Published: November 2023

Abstract
This paper focuses on innovative mooring layouts using shared anchors and shared mooring lines. Three studies with the ActiveFloat semi-submersible floater supporting a 15MW wind turbine are presented. Those include two studies of shared anchors layouts, with a semi-taut mooring system at a deep-water site subjected to extreme conditions (Morro Bay) and a catenary mooring at a moderate water depth with gentle environment (Gran Canaria). The third study focuses on shared mooring layout at Morro Bay. The mooring system at this site is semi-taut, made of polyester, with chain close to the sea surface and the anchors. At Gran Canaria, ActiveFloat is featured with a catenary mooring system made of chain lines. Both sites are subjected to irregular sea states and turbulent wind. Time domain simulations in ULS are performed using OrcaFlex models that combine potential flow theory and Morison drag coefficients. Aerodynamic load time series are applied at the tower top. Results show that shared anchor layouts are technically feasible but do not improve the mooring system procurement costs due to the spacing constraint between each turbine. Sharing mooring lines at farm level seems more promising and could help reduce costs, due to the decrease in amount of material use.
Investigation of the influence of sinusoidal internal waves on a SPAR buoy structure
Authors: Maertens Vivien , Blenkinsopp Chris , Milewski Paul 
Published: November 2023

Abstract
Offshore wind has a great potential as a competitive source of renewable energy, especially in deep waters where wind speeds are more consistent and fewer restrictions apply for running large wind turbines. Previous analyses of Floating Offshore Wind Turbines (FOWTs) mostly considered obvious sources of loading: surface waves, currents, wind and mooring. However, in some deep-water locations, internal waves can occur and these have been shown to significantly affect floating structures. Since the hydrodynamic response of an FOWT governs the structure’s general stability, the aim of this research is to investigate the impact of sinusoidal internal waves on the platform motion of a free-floating SPAR-type cylinder. A potential flow model and Morison’s equation are applied numerically to calculate the forces acting on a free-floating cylinder in an oscillating flow. The commercial Finite Element Analysis software OrcaFlex is verified by the potential flow model of the oscillating flow and is then used to mimic sinusoidal internal waves acting on a free-floating cylinder in a stratified flow. Three different internal wave amplitudes and peak velocities are analysed, and the nine resulting cases are investigated for the oscillating and stratified flow each. It has been found that the pitch rotations of the SPAR cylinder were small (< 0.1°) in all cases and can likely be disregarded. The surge displacements of the free-floating cylinder were substantial in both oscillating and stratified flows, with maximum surge magnitudes of 423m and 120m, respectively. Therefore, significant additional mooring loads due to internal waves could be sustained by SPAR-type FOWTs.