Search Results (1,343)

The North Sea is becoming a shared renewable energy space in which offshore wind deployment, grid planning, market operation and environmental governance increasingly cross borders. This article asks how wind-resource complementarity can inform legal and institutional design for cross-border offshore wind cooperation. It combines a five-year representative-point wind-resource screening analysis using NASA POWER hourly data from 2021 to 2025 with functional legal–institutional analysis. The empirical analysis covers seven offshore or near-offshore representative screening points, hub-height correction to 100 m and 150 m, a wind-power proxy and wind-power-density proxy, low-wind frequency and low-wind event duration, monthly and interannual variability, pairwise correlation, CWCI and weighting sensitivity. The representative-point results suggest a mean 100 m corrected wind-speed range of 8.52 to 9.88 m/s, 4 m/s low-wind frequencies of 8.69% to 12.64%, and a maximum 4 m/s low-wind event of 173.0 h at NO_SOUTH. The baseline CWCI screening identifies DK West–BE Coast, DK West–FR Channel and UK East–FR Channel as leading within-sample pairs. The legal analysis uses these results as screening evidence for questions of data compatibility, hub-height assumptions, low-wind consultation, hybrid offshore grid governance, market coordination, cumulative environmental assessment, investment regulatory space and crisis dispute prevention. The article proposes an operational five-pillar framework with institutions, instruments, implementation steps and compliance pathways. It should be read as an exploratory evidence-to-law screening analysis, not a definitive wind-resource assessment, turbine-output model, capacity-factor estimate or grid-dispatch simulation. Full article

This paper analyzes the fatigue loads of wind turbines in a floating offshore wind farm (FOWF) whose layout can be reconfigured. Such wind farm reconfiguration will be useful for wake effect mitigation in varying wind conditions. As an example FOWF, a farm with three 5 MW floating offshore wind turbine (FOWT) models on semi-submersible platforms, developed by the National Laboratory of the Rockies (NLR) (formerly the National Renewable Energy Laboratory (NREL)), is considered. Simulations for the example FOWF are conducted with various realistic turbulent wind and irregular wave conditions in the medium-fidelity wind farm simulator FAST.Farm. Using the simulation data, fatigue analysis is conducted by calculating the damage equivalent loads (DELs) using the computational tool MLife at critical components of the three FOWTs. The analysis results demonstrate the potential of reconfigurable FOWFs in not only increasing power outputs but also reducing fatigue loads for many critical components of turbines. Full article

The purpose of this paper is to present a techno-economic methodology for assessing the economic sustainability of offshore wind energy development within the Romanian exclusive economic zone (EEZ) of the Black Sea. The methodology illustrates nine key cases in this area that are grouped into three classes, each positioned at a greater distance from the Romanian coast and thus generating different environments given the water depth and wind climate. The data used for the analysis came from the ERA5 database and covered a 20-year span. Six types of wind turbines with capacities ranging from 5 to 9.5 MW were considered. In determining the levelized cost of energy (LCOE), the turbine with the highest production was considered, which turned out to be the Seimens Gamesa 8 MW, and for the economic model, the components related to both capital and operating costs were considered. Following the analysis, it was observed that the B2 site presents the best wind resources, also leading to the highest energy production of x. Regarding the LCOE analysis, values between 66.86 EUR/MWh and 87.39 EUR/MWh were obtained if the entire energy production is considered. Following the simulation with losses, the LCOE increases to values between 92.19 EUR/MWh and 121.85 EUR/MWh. Finally, an optimization calculation was also performed for the site with the highest LCOE considering another foundation time, after which the LCOE decreased to approximately 111.09 EUR/MWh, if we refer to energy production with losses. The results contribute to the economic sustainability evaluation of offshore wind projects in the Romanian Black Sea and influence future investment plans, sustainable energy planning, and renewable energy infrastructure development. Full article

Driven by the global low-carbon transition and the rapid expansion of marine energy development, offshore integrated energy systems are emerging as a critical configuration for coupling offshore renewable resources, geothermal and subsurface thermal resources, oil and gas infrastructure, hydrogen pathways, multi-carrier networks, and offshore loads. Unlike onshore integrated energy systems, offshore systems are constrained by resource intermittency, harsh marine environments, platform space and weight limits, long-distance transmission, operation and maintenance accessibility, safety risks, and cross-regional governance mechanisms. Recent studies have advanced offshore wind-to-hydrogen systems, oil and gas platform electrification, offshore energy hubs, platform repurposing, and offshore geothermal utilization. However, these studies remain fragmented in terms of system boundaries, multi-energy coupling mechanisms, engineering constraints, and optimization methods. This paper reviews offshore integrated energy systems from the perspectives of system configuration, key integration technologies, optimization and assessment methods, and future research needs. Offshore integrated energy systems are first classified into offshore renewable-energy-dominated systems, offshore wind–hydrogen systems, oil and gas platform integrated systems, offshore energy hubs and multi-carrier networks, decommissioned-platform repurposing systems, and offshore geothermal and repurposed-well systems. Resource-side, conversion-side, storage-side, network-side, and load-side integration technologies are then summarized. Capacity configuration, operational scheduling, stochastic and robust optimization, multi-objective optimization, energy, exergy, economic, and environmental (4E) assessment, advanced exergy analysis, and energy-hub modelling are further reviewed. Finally, key research gaps are identified, including resource uncertainty, offshore engineering constraints, multi-carrier network coupling, insufficient demonstration data, and policy and economic uncertainty. This review provides a structured reference for the modelling, integration, optimization, and demonstration of offshore integrated energy systems for low-carbon transition. Full article

Bolted joints are critical load-transfer components in bridges, wind turbines, aerospace systems, mechanical equipment, and offshore platforms, where preload loss can degrade stiffness, accelerate fatigue, and compromise safety. For structural health monitoring, early monitoring of preload reduction before marked loosening is essential, yet existing ultrasonic guided wave indicators remain affected by frequency dependence, non-monotonic responses, amplitude drift, and environmental disturbances. This study proposes an early-warning-oriented preload identification method that combines broadband excitation, multi-frequency narrowband reconstruction, spectral centroid extraction, optimized weighted fusion, and fixed SC-domain linear calibration from one reference loading group. Using a 20–250 kHz Chirp response, 14 narrowband signals from 50 to 180 kHz were reconstructed for an M20 single-bolt specimen tested over 50–90 N·m. The fused spectral centroid index exhibited a stable, monotonic, and approximately linear relationship with preload. When fixed weights and calibration coefficients were transferred to held-out repeated-loading groups, all Pearson correlation coefficients exceeded 0.99. Feature-level robustness tests showed that the arithmetic mean of the spectral centroid reduced temperature-induced Range% by 98.42–99.08% and RSD by 98.89–99.31% relative to energy-based features. This work provides an interpretable multi-frequency spectral descriptor and a calibration transfer framework for repeatable early warning of preload loss in a controlled single-bolt configuration. Full article

Offshore wind is expanding globally, driven by energy security and decarbonization goals. Brazil’s world-class potential for this resource is challenged by its unique context: an already clean electricity matrix and abundant, low-cost onshore alternatives, which reduce the immediate urgency for deployment. This paper starts with a global offshore wind market analysis, understanding why the main countries pursue this technology, in contrast with Brazil’s already high share of renewable generation. The following examination focuses on Brazil’s recently approved new offshore wind framework and the governance-related issues, revealing that the legislative process was distorted by unrelated riders mandating costly, non-competitive energy procurement. These riders threatened to absorb future market growth, undermining competition and jeopardizing the emergence of the entire offshore wind industry. While presidential vetoes of these riders were essential to preserve this opportunity, remaining market distortions still favor mature technologies. The study concludes that Brazil’s primary barrier to offshore wind is not technical or resource-based but institutional: the need for stable, transparent governance to foster a truly competitive and predictable policy environment. Full article

Offshore geothermal energy and the reuse of decommissioned oil and gas platforms are emerging as linked pathways for reducing the carbon intensity of marine energy supply while extending the value of mature offshore assets. This review examines offshore geothermal development from a full-chain perspective that connects resource assessment, platform and wellbore reuse, heat extraction, medium- and low-temperature conversion, multi-energy coupling, techno-economic evaluation and environmental risk management. The paper first clarifies the resource logic of offshore geothermal systems, especially sedimentary-basin resources that spatially overlap with mature petroleum provinces. It then analyzes two principal engineering routes: the reuse of existing offshore platforms as energy hubs and the reutilization of abandoned wells as open-loop or closed-loop heat-extraction systems. The review finds that platform and wellbore reuse can reduce drilling demand, shorten offshore construction cycles and lower life-cycle environmental burdens, but engineering feasibility remains constrained by wellbore integrity, thermal losses, corrosion and scaling, platform life extension, regulatory liability and the limited availability of field-scale demonstration data. Coupling geothermal energy with offshore wind power, hydrogen production, OTEC and desalination can improve system stability and equipment utilization; however, standardized assessment boundaries and comparable cost models are still insufficient. Future research should focus on resource-engineering-economic integrated assessment, standardized reuse packages, long-term offshore reliability databases, corrosion-resistant material systems, auditable TEA/LCA models and risk-based regulatory frameworks. This review provides a technical basis for offshore geothermal pilot projects and for the low-carbon transformation of offshore oil and gas infrastructure. Full article

The integration of wave energy converters with offshore wind foundations offers a potential route to improving the utilization of offshore renewable energy infrastructure. This study numerically investigates the power-load characteristics of fixed oscillating water column (OWC) chambers intended for potential installation near offshore wind jacket foundations. A preliminary jacket comparison is first used to delimit the scope, after which the main parametric study is performed on isolated OWC chambers so that pneumatic response and local chamber loads can be compared consistently. The simulations are conducted under regular waves with a wave height of H = 0.05 m, a water depth of h = 1.6 m, and wave periods of T = 0.9–1.7 s. Three baseline geometries, namely cylindrical, sandglass-shaped, and bottle-shaped OWCs, are first screened in order to identify the most suitable reference chamber family. The cylindrical chamber is then retained as the reference configuration for subsequent local parameter studies of the frustum-contraction parameter D₂ and the front-wall draft d₂. The results indicate that the geometric effect is strongly dependent on the incident-wave period. The sandglass-shaped and bottle-shaped chambers can enhance short-period pneumatic power or reduce loads at longer periods, whereas the cylindrical chamber provides a more consistent reference response over the tested range. Under the wave conditions adopted in this study, further analysis reveals that D₂ exerts a non-monotonic tuning effect varying with wave period. For the selected frustum-shaped configuration, increasing d₂ reduces hydrodynamic loads yet simultaneously weakens pneumatic power output and CWR. Because the air phase is treated as incompressible and the orifice represents an orifice-only damping condition rather than a turbine-controlled PTO system, the reported P_e should be interpreted as a pneumatic/hydrodynamic comparison metric and not as wave-to-wire electrical power. The conclusions are therefore positioned as regular-wave geometry-tuning trends for the present model scale rather than as full coupled jacket-OWC design rules. Full article

This paper systematically analyses the fault characteristics and investigates fault ride-through (FRT) control strategies for a low-frequency (LF) transmission system in offshore wind power based on Modular Multilevel Matrix Converter (M3C). The study addresses transient issues of power imbalance, submodule capacitor overvoltage, and bridge-arm overcurrent arising from three-phase ground faults on both the industrial-frequency (IF) and LF sides. The underlying mechanisms of power surplus and submodule capacitor overvoltage, induced by decoupling control and current-limiting protection during IF-side faults, are examined in detail, along with the transient characteristics of bridge-arm currents under voltage sags on the LF side. Two innovative control strategies are proposed to enhance system resilience: (1) For IF-side faults, a controllable energy dissipation device on the LF side achieves precise dissipation of surplus power via real-time monitoring of the average submodule capacitor voltage. (2) For LF-side faults, the FRT strategy based on dynamic adjustment of the LF modulation voltage rapidly reduces the reference to 0.1 p.u. and restores it linearly at a predefined rate, thereby enabling fault information transmission and wind turbine derating. The effectiveness and feasibility of the proposed scheme are verified through simulations on a 1000 MW system model. Full article

By integrating ecological spatial data, offshore wind energy development zones, and the marine spatial planning (MSP) framework, it is possible to assess the relationship among Taiwan’s offshore renewable energy development, risks to marine biodiversity, and the effectiveness of marine spatial planning. The study adopts a mixed-method spatial–quantitative research design that integrates geospatial modelling, ecological risk assessment, spatial conflict analysis, and governance evaluation for quantification of biodiversity exposure to offshore wind infrastructure. Spatial overlay analysis is employed in the identification of geographic areas where offshore wind development intersects with high biodiversity vulnerability zones. Quantitative spatial indicators are used to assess the extent to which MSP reduces biodiversity exposure to offshore renewable energy infrastructure. The analytical framework integrates two parallel modelling domains including the ecological risk modelling domain and the spatial governance effectiveness domain. The spatial analysis of biodiversity vulnerability across Taiwan’s analyzed offshore areas revealed a BVI range of 0.12 to 0.88. The mean BVI value was 0.51 (S.D. = 0.18). The results further show that over 47% of the analyzed EEZ falls into high and very high vulnerability classes. The total offshore wind area located within high-risk and very high-risk zones accounted for 38% of the wind farm footprint. Smaller proportions occupy very low and low-risk zones, accounting for 7.1% and 21.4%, respectively, while 32.1% of wind infrastructure is in moderate-risk areas. Overlaying MSP boundaries with biodiversity risk zones showed that 62% of high-risk biodiversity areas are encompassed within MSP-designated protection, leaving 38% of high-risk zones unprotected. The findings show that biodiversity preservation and offshore wind development are not mutually exclusive but are rather dependent on efficient spatial planning, integrated governance, and flexible management to maintain sustainability. Full article

Sentinel-1 Synthetic Aperture Radar (SAR) is a multi-purpose monitoring satellite suite that, among many applications, provides sea surface wind speeds at high spatial resolution. The overall aim of the study is to quantify the accuracy of the SAR wind products from Copernicus Ocean Wind, called OCN OWI, and from the Technical University of Denmark (DTU) Department of Wind and Energy Systems’ product called DTU SAR. Both products serve as a basis for offshore wind resource mapping for offshore wind energy planning. With the growth in offshore wind farms, offshore wind resource information is highly relevant. However, a comparison between the two products is lacking. This study fills this gap by presenting a comprehensive validation of the two Sentinel-1 wind speed products using wind speed measurements from 18 weather buoys and 10 floating wind lidars in the European Seas. It is the first time a comprehensive wind lidar dataset has been used for SAR wind validation. Key findings: OCN OWI vs. lidar (buoy) shows R² = 0.93 (0.84), root mean square error (RMSE) = 1.18 m/s (1.61 m/s), mean absolute error (MAE) = 0.86 m/s (1.24 m/s), and bias = −0.5 m/s (−0.6 m/s). DTU SAR vs. lidar (buoy) shows R² = 0.88 (0.84), RMSE = 1.3 m/s (1.6 m/s), MAE = 0.92 m/s (1.22 m/s), and bias = 0.02 m/s (−0.04 m/s). OCN OWI provides a filtered dataset and validation vs. lidar shows R² = 0.95 and RMSE = 0.88 m/s; however, this is achieved at the expense of discarding more than 50% of all data. The lidar vs. SAR wind speed statistics outperformed the buoy comparison statistics for all metrics studied. Lidar wind speed data are more accurate than buoy data and give a more trustworthy validation of SAR wind speeds than buoy data. Lidar data are recommended for validation studies on Geophysical Model Functions on SAR winds. Full article

Low-frequency alternating current (LFAC) transmission has attracted increasing attention for medium- and long-distance offshore wind power transmission, as this application scenario is typically characterized by long transmission distance and large installed capacity. Converting offshore low-frequency alternating current into onshore power-frequency alternating current requires a dedicated frequency conversion device. Compared with power–electronic converter-based schemes represented by the modular multilevel matrix converter (M3C), grid connection via a motor–generator pair (M-G) enables the renewable energy port to retain intrinsic synchronous-machine characteristics, including inertial support, voltage support, and fault isolation. This paper elaborates the operating principles and mathematical models of the two types of frequency conversion solution for LFAC transmission systems, and systematically analyzes the frequency support, voltage support, and fault-isolation capabilities of the M-G scheme. Simulation results demonstrate that under a sudden increase in onshore active power load, the M-G system can provide strong frequency support by releasing rotor kinetic energy, and a larger inertia time constant mitigates the frequency drop more effectively. Under a sudden increase in onshore reactive power load, the M-G scheme offers a greater reactive power margin benefiting from its strong short-term overcurrent capability. Moreover, increasing the excitation gain on the motor side and installing shunt reactors at both ends of the submarine cable can effectively improve the voltage profile along the cable. Full article

Ireland was an early offshore wind pioneer, with Arklow Bank Phase 1 commissioned in 2004 as one of the world’s first commercial offshore wind farms (OWFs). Despite this early start, offshore wind development (OWD) in Ireland remained limited for almost two decades. In recent years, however, the Government of Ireland has declared ambitious offshore renewable energy (ORE) targets, aiming to deliver up to 37 GW of capacity by 2050. One of the key constraints during this period has been the absence of a coherent and integrated marine planning and consenting framework capable of supporting large-scale ORE. This paper examines the evolution of Ireland’s ORE planning and consenting regime, tracing the transition from fragmented, largely “developer-led” arrangements toward a more coordinated and “state-led” framework. It reviews key legislative and policy developments, including the National Marine Planning Framework, the Maritime Area Planning (MAP) Act 2021, the establishment of the Maritime Area Regulatory Authority (MARA), and the introduction of Designated Maritime Area Plans (DMAPs), particularly the South Coast DMAP. The paper also situates Ireland’s recent reforms within selected leading European jurisdictions, highlighting persistent challenges related to governance coordination, permitting complexity, and regulatory sequencing in offshore wind deployment in Ireland. Full article

Offshore wind farms are increasingly and rapidly expanding due to their ability to harness strong and consistent wind energy resources. Large offshore wind farms are connected to mainland grids through High-Voltage Direct Current (HVDC) technology. However, offshore wind farms can often experience disturbances related to sudden wind changes, voltage drops/dips, faults related to converter switching, and unbalanced grid conditions which affect both the HVDC operation and wind turbine output. As a result, there is a growing need for more advanced and reliable modeling and monitoring tools. Moreover, traditional proportional-integral (PI) controllers are widely applied in wind turbines and HVDC systems due to their simple structure, easy implementation, and reliability. However, PI controllers perform poorly under non-linear and abnormal/fast-changing conditions, especially during sudden drops in wind power and grid faults. With this background, this paper first develops a digital twin model of an offshore wind farm that enables remote operation and monitoring of individual wind turbines. Also, an artificial intelligence (AI)-based controller, namely a fuzzy logic controller (FLC), is proposed to maintain transient stability of a full digital twin-based offshore wind farm connected to the HVDC grid under fault conditions. The effectiveness of the proposed FLC is demonstrated by considering a digital twin-enabled 700 MW offshore wind farm. The performance of the proposed FLC has been compared with that of the PI controller. Simulations performed by the MATLAB/Simulink software show that during the moderate voltage dip at 15 s, the PI controller experienced a 29.8% power reduction with a recovery time of approximately 9 s, whereas the FLC reduced the power drop to 23.1% and recovered within 6 s. During the severe converter disturbance at 15 s, the PI controller recorded a 36.9% power reduction compared to 23.4% for the FLC. Similarly, during the short-duration turbulence at 15 s, the PI controller exhibited a 36.73% power drop and recovered in approximately 7 s, while the FLC limited the power reduction to 19.17% and recovered within 5s. Overall, the FLC provided improved voltage stability, faster recovery, reduced oscillations, and superior fault ride-through capability compared with the conventional PI controller, demonstrating its effectiveness for digital twin-enabled offshore wind farm application. Full article

Offshore wind energy offers abundant resources and significant potential for large-scale development. Efficient design of collection systems is critical to the economic viability of offshore wind farms (OWFs). This study proposes an upper–lower level topology optimization framework based on the Artificial Lemming Algorithm (ALA) to address the complexity arising from large numbers of wind turbines (WTs). At the upper level, wind turbines can be partitioned into different numbers of regions according to practical engineering requirements using the Radial Fuzzy C-Means (RFCM) clustering algorithm. At the lower level, the ALA is applied to optimize the collection system topology within each region, aiming to minimize total construction cost while satisfying operational constraints. A case study involving a 75-WT offshore wind farm is conducted. Comparative simulations against various heuristic algorithms including Particle Swarm Optimization (PSO), Genetic Algorithm (GA), and Differential Evolution (DE) show that the proposed method achieves faster convergence, lower total costs and greater robustness. Specifically, the ALA reduces the best cost by 9.9% and improves average runtime by 28.5%, indicating its advantages in best-cost search and computational efficiency in the tested case. In addition, based on 10 independent runs, the ALA achieves the lowest median cost of $6684\times {10}^4$ CNY, with an interquartile range of 6593–$6813\times {10}^4$ CNY and a cost range of 6362–$7087\times {10}^4$ CNY. Overall, the proposed framework provides a practical optimization approach for obtaining low-cost feasible collection-system layouts in the studied offshore wind farm case. Full article