Offshore Projects Research Articles

A Raster-Based Multi-Objective Spatial Optimization Framework for Offshore Wind Farm Site-Prospecting

Siting an offshore wind project is considered a complex planning problem with multiple interrelated objectives and constraints. Hence, compactness and contiguity are indispensable properties in spatial modeling for Renewable Energy Sources (RES) planning processes. The proposed methodology demonstrates the development of a raster-based spatial optimization model for future Offshore Wind Farm (OWF) multi-objective site-prospecting in terms of the simulated Annual Energy Production (AEP), Wind Power Variability (WPV) and the Depth Profile (DP) towards an integer mathematical programming approach. Geographic Information Systems (GIS), statistical modeling, and spatial optimization techniques are fused as a unified framework that allows exploring rigorously and systematically multiple alternatives for OWF planning. The stochastic generation scheme uses a Generalized Hurst-Kolmogorov (GHK) process embedded in a Symmetric-Moving-Average (SMA) model, which is used for the simulation of a wind process, as extracted from the UERRA (MESCAN-SURFEX) reanalysis data. The generated AEP and WPV, along with the bathymetry raster surfaces, are then transferred into the multi-objective spatial optimization algorithm via the Gurobi optimizer. Using a weighted spatial optimization approach, considering and guaranteeing compactness and continuity of the optimal solutions, the final optimal areas (clusters) are extracted for the North and Central Aegean Sea. The optimal OWF clusters, show increased AEP and minimum WPV, particularly across offshore areas from the North-East Aegean (around Lemnos Island) to the Central Aegean Sea (Cyclades Islands). All areas have a Hurst parameter in the range of 0.55–0.63, indicating greater long-term positive autocorrelation in specific areas of the North Aegean Sea.

Offshore wind project installations: an advanced approach for weather risk assessments

Abstract This paper presents the development of a sequence-based simulation tool for the weather risk assessment of offshore work processes. The approach developed at the Fraunhofer Institute for Wind Energy Systems is the Advanced Weather Time Series Scheduling (Ad-WATSS) method. For statistical significance, this method combines hindcast weather time series of many years with the weather restrictions associated with offshore activities. The method is incorporated into the software tool COAST, where a project plan schedule is simulated by placing activities according to their operational limits, constraints and relationships, and minimum-required time for each operation. A scenario of an offshore wind installation project in the North Sea is used as reference test case for a weather risk assessment using the developed tool and ERA5 weather data. The assessment is then compared with the weather window statistics approach, based on the same weather data sets. The results from both approaches are analysed and compared on a project and task level detail. The results from the sequence-based simulations show that the method is able to capture the long-term variability and extreme events in weather conditions, making it a reliable tool for the simplification of the weather data-based planning, validation, and assessment of offshore projects.

Increasing revenues of offshore wind farms with co-located energy storage systems

Abstract Co-located onshore and offshore energy storage systems exhibit the potential of diversifying and increasing revenue streams of offshore wind farms. However, these systems should be designed and sized considering the power generation profile, the route to market of these assets, i.e. power trading strategy, and dynamics of the various segments of the power market. In this study, the feasibility of deploying subsea hydro-pneumatic storage systems was investigated. It was seen that if a 50MW capacity system with a storage duration of 4 hours is deployed in an offshore wind farm of 1000MW capacity, the wind farm can potentially participate in the day-ahead and ancillary services markets more confidently from a risk perspective. The relatively higher volatility in these markets presents an opportunity to improve economics of these offshore wind projects as long as costs can be kept under control.

Evaluating constraints on offshore wind farm installation across the Taiwan Strait by exploring the influence of El Niño-Southern Oscillation on weather window assessment

The transition to renewable energy sources, such as offshore wind farms, is essential in mitigating climate change. Taiwan has set ambitious targets to harness wind energy from the Taiwan Strait, but offshore wind farm installations are highly dependent on weather conditions, particularly wind speeds. This study examines the relationship between the El Niño-Southern Oscillation (ENSO) and offshore wind farm installation by assessing weather windows—periods with wind speeds below 12 meters per second at a height of 100 meters for at least 12 hours. Our analysis shows that during La Niña years, the number of feasible weather windows decreases by up to 40%, particularly between October and June, compared to neutral and El Niño years. This decrease can be as high as fourfold in December, significantly impacting installation schedules. Seasonal variations are also notable, with wind speeds exceeding 12 m/s in winter 66.4% of the time, compared to 29.4% in spring, making spring and summer the most favorable periods for installation. However, even during these favorable seasons, La Niña years can bring higher wind speeds, necessitating careful planning. These results underscore the importance of integrating ENSO forecasts into project planning to avoid installation delays and optimize installation timelines. By leveraging seasonal and interannual climate variability predictions, decision-makers can improve the resilience of offshore wind farm projects and ensure efficient energy transition strategies.

Investigation of the Mechanical Properties of Reinforced Calcareous Sand Using a Permeable Polyurethane Polymer Adhesive

Calcareous sand has been widely used as a construction material for offshore projects; however, the problem of foundation settlement caused by particle crushing cannot be ignored. Although many methods for reinforcing calcareous sands have been proposed, they are difficult to apply on-site. In this study, a permeable polyurethane polymer adhesive (PPA) was used to reinforce calcareous sands, and its mechanical properties after reinforcement were investigated through compression creep, direct shear, and triaxial shear tests. The reinforcement mechanism was analyzed using optical microscopy, CT tomography, and mercury intrusion porosimetry. The experimental results indicate that there is a critical time during the compression creep process. Once the critical time is surpassed, creep accelerates again, causing failure of the traditional Burgers and Murayama models. The direct shear strength of the fiber- and geogrid-reinforced calcareous sand reinforced by PPA was approximately nine times greater than that without PPA. The influence of normal stress was not significant when the moisture content was less than 10%, but when the moisture content was more than 10%, the shear strength increased with an increase in vertical normal stress. Strain-softening features can be observed in triaxial shear tests under conditions of low confining pressure, and the relationship between the deviatoric stress and strain can be described using the Duncan–Chang model before softening occurs. The moisture content also has a significant influence on the peak strength and cohesive force but has little influence on the internal friction angle and Poisson’s ratio. This influence is caused by the different PPA structures among the particles. The higher the moisture content, the greater the number of pores left after grouting PPA.

High-Resolution Wind Speed Estimates for the Eastern Mediterranean Basin: A Statistical Comparison Against Coastal Meteorological Observations

Wind speed (and direction) estimated from numerical weather prediction (NWP) models is essential to wind energy applications, especially in the absence of reliable fine scale spatio-temporal wind information. This study evaluates four high-resolution wind speed numerical datasets (UERRA MESCAN-SURFEX, CERRA, COSMO-REA6, and NEWA) against in situ observations from coastal meteorological stations in the eastern Mediterranean basin. The evaluation is based on statistical comparisons of long-term wind speed data from 2009 to 2018 and involves an in-depth statistical comparison as well as a preliminary wind power density assessment at or near the meteorological station locations. The results show that while all datasets provide valuable insights into regional wind variability, there are notable differences in model performance. COSMO-REA6 and UERRA exhibit higher variability in wind speed but tend to underestimate extreme values, particularly in the southern coastal areas, whereas CERRA and NEWA provided closer fits to observed wind speeds, with CERRA showing the highest correlation at most stations. NEWA data, where available, overestimate average wind speeds but capture extreme values well. The comparison reveals that while all datasets provide valuable insights into the spatial and temporal variability of wind resources, their performance varies by location and season, emphasizing the need for the careful selection and potential calibration of these models for accurate wind energy assessments. The study provides essential groundwork for leveraging these datasets in planning and optimizing offshore wind energy projects, contributing to the region’s transition to renewable energy sources.

Hybrid offshore wind projects. Social desirability vs. incentives to invest

To unlock the full potential of offshore wind requires investment in a more integrated offshore grid infrastructure combining generation and interconnection between countries in so-called hybrid projects. Taking the perspective of a social planner, these projects may result in more efficient allocation of scarce resources. Alas, the distribution of this welfare gain may result in disagreement on what grid design is the most attractive, what markets should be connected and whether and when to invest. To examine these dilemmas, we apply real options theory to investments projects with different grid design and market characteristics. We compare the incentives to invest in a) only the wind farm and b) both the wind farm and the grid infrastructure, assuming the project value of the last alternative can serve as a proxy for social welfare. Solutions are derived using a simulation approach called least squares Monte Carlo method. We find: 1) Non-stationary stochastic prices and/or decreasing costs may make it socially optimal as well as commercially beneficial to postpone even profitable investments. 2) Connecting markets is socially desirable but may reduce the offshore wind investor's project value. 3) Connecting markets with different characteristics is socially desirable but reduce the offshore wind investors' project value.

Well control technology and digital intelligent management practice in Zhaodong Oilfield

Abstract Zhao-dong Oilfield is an offshore cooperation project in the mode of “international operation and PetroChina control”, adheres to the principle of “safety and environmental protection first, equal emphasis on production and efficiency”, practices the well control management concept of the whole life cycle, and consolidates the foundation of well control management by continuously optimizing the system and system, adheres to the integrated design of geology and engineering to control the source risk, implements fine trajectory control and anti-collision management to control the process risk, and The digital and intelligent production monitoring system is applied to control dynamic risks and realize the safe, efficient and sustainable development of Zhao-dong Oilfield.

Influence of increasing noise at the offshore wind farm area on fish vocalization phenology: A long-term marine acoustical monitoring off the foremost offshore wind farm in Taiwan

The rapid increase of offshore projects at Taiwan Strait in recent decade has been debated for elevated noise levels. However, there are no studies on long-term assessment of noise levels and impact of noise on marine organisms. The passive acoustic monitoring was conducted at the foremost wind farm area in Taiwan to assess the sound levels and the impact of noise on fish vocalization behavior. Predominately, in the soundscape around the Taiwan Strait, two chorusing types (Type 1 and Type 2) from the Sciaenid family of fishes exist. Ambient sound levels significantly increased from 2014 to 2019, while the chorusing Types 1 and 2 were observed in a lower percentage of the recordings. Additionally, chorusing peak intensity and duration significantly reduced over the years for both choruses. This is the first field-based evidence to demonstrate the consequences of increasing anthropogenic noise having the potential to alter the vocalization behavior of the fish.

Simulating cross-scale flow dynamics around offshore monopile foundations with a GFD-CFD coupled model

Flow dynamics are complex and undergo significant impact from offshore engineering infrastructures, such as wind turbines, involving interactions across different temporal and spatial scales. Individual numerical models of geophysical fluid dynamics (GFD) or computational fluid dynamics (CFD) face challenges in accurately representing these dynamics. To effectively capture the three-dimensional cross-scale flow around offshore infrastructures, we propose a generalized coupling framework that integrates the unstructured-grid Finite-Volume Community Ocean Model (FVCOM) for GFD and the Open Field Operation and Manipulation (OpenFOAM) for CFD. With the validation against the flume experiment, the common-boundary nesting method was developed to allow an accurate representation of flow dynamics around offshore hydraulic infrastructures. Idealized monopile foundation experiments demonstrate the model's capability to capture the formation of Karman vortex street, rotating horseshoe vortex under realistic astronomical tidal conditions. Application of this coupling framework to the offshore wind farm in Yangjiang, China, reveals flow direction lagging of 15° in the wake of a monopile under diurnal tide. This coupling approach, leveraging the strengths of both CFD and GFD models, provides a universal downscaling methodology in geophysical conditions, for a better understanding of the impact of offshore hydraulic infrastructures on the surrounding environment and further planning offshore engineering projects.

Methodology for Generating a Reference Wind Year for Offshore Wind Energy: A Case Study in La Guajira, Colombia

Due to its excellent potential, wind power has gained importance as a renewable energy source in Colombia, especially in the offshore Caribbean region. However, one of the main challenges in the development of offshore wind projects is the analysis of the wind resource. This study presents the generation of a specific typical meteorological year (TMY) for wind energy in the Colombian Caribbean region, known in the literature as Reference Wind Year (RWY). The methodology used was based on the Sandia method, widely accepted in the analysis of wind resources. A comparison between the cumulative distribution function (CDF) and the statistic approach Finkelstein-Schafer (FS) was applied to evaluate multiple meteorological parameters in the study area associated with wind resource potential assessment, such as wind speed and direction, temperature and atmospheric pressure, compiled for 10 years (2012-2021). The representative years were weighted according to their importance and combined into a dataset. The results indicated that the proposed method was able to generate highly representative and accurate data for the case study in La Guajira, Colombia, guaranteeing its suitability for implementation in other locations with different climatic conditions.

Energy dissipation methods and protection device synergy strategies for offshore wind power receiving end surplus power

Abstract Firstly, a theoretical analysis of the fault ride-through scheme is carried out based on the land-side AC faults in the offshore wind power delivery system. According to the topological structure of the DC energy consumption device, the working mode and switching of the DC energy consumption device are analyzed and studied. Secondly, the DC protection action of offshore wind power flexible and direct transmission systems was studied, and the switching strategy of energy-consuming devices was determined. Then the impact of the switching of the energy-consuming device on the DC protection function was studied, focusing on the synergy between the DC overvoltage protection and the switching judgment voltage of the energy-consuming device. Finally, based on a typical offshore wind power flexing project, a system model is built in PSCAD/EMTDC to verify the effectiveness of the proposed synergy strategy.

Towards sustainable energy: integrating ERA5 data for offshore wind farm planning in India

India’s pursuit of offshore wind energy development, particularly along the Tamil Nadu coastline within its Exclusive Economic Zone (EEZ), faces significant spatial and economic challenges due to existing industrial activities and water depth limitations. Motivated by the need to optimize offshore wind resources and bridge the gap between onshore and offshore wind energy achievements, this study hypothesizes that ERA5 reanalysis wind data can be relied upon for assessing offshore wind resources and optimizing wind farm layouts, especially in the absence of measured data. The research employs methods such as comparing ERA5 data with empirical wind measurements, generating wind rose diagrams for layout optimization, and conducting a comprehensive financial analysis to estimate the Levelized Cost of Energy (LCoE). The results confirm the efficacy of ERA5 data, identifying an optimal wind farm layout with a capacity density of 5.17 MW per square kilometer, turbine spacing of 7.22 meters, and an LCoE of Rs. 8.84 per kWh. The study concludes that significant financial support and strategic policy interventions are essential for minimizing wake losses, optimizing capacity density, and fostering the long-term growth of India’s offshore wind energy sector, providing critical insights for policymakers, developers, and investors. The novelty of this research lies in its detailed exploration of spatial optimization and cost-effective strategies to enhance the techno-economic viability of offshore wind projects in India.

Technology Selection of High-Voltage Offshore Substations Based on Artificial Intelligence

This paper proposes an automated approach to the technology selection of High-Voltage Alternating Current (HVAC) Offshore Substations (OHVS) for the integration of Oil & Gas (O&G) production and Offshore Wind Farms (OWF) based on Artificial Intelligence (AI) techniques. Due to the complex regulatory landscape and project diversity, this is enacted via a cost decision-model which was developed based on Knowledge-Based Systems (KBS) and incorporated into an optioneering software named Transmission Optioneering Model (TOM). Equipped with an interactive dashboard, it uses detailed transmission and cost models, as well as a technological and commercial benchmarking of offshore projects to provide a standardized selection approach to OHVS design. By automating this process, the deployment of a technically sound and cost-effective connection in an interactive sandbox environment is streamlined. The decision-model takes as primary inputs the power rating requirements and the distance of the offshore target site and tests multiple voltage/rating configurations and associated costs. The output is then the most technically and economically efficient interconnection setup. Since the TOM process relies on equivalent models and on a broad range of different projects, it is manufacturer-agnostic and can be used for virtually any site as a method that ensures both energy transmission and economic efficiency.

Distance to offshore wind farms, onshore wind power spillover relationships, and the willingness to pay for farshore, large-scale wind power development

ABSTRACT As demands for clean energy mount to meet international and national climate goals, constant tension and trade-offs regarding where to site large-scale offshore wind farms (OWF) remain. Using data from a choice experiment to elicit preferences for large-scale, 3.6 gigawatts OWFs in Denmark, we find that respondents living far from a proposed or existing offshore wind power projects have a lower willingness to pay (WTP) to locate new OWFs at 12 km, 18 km, or 50 km relative to 8 km from the coast. Furthermore, based on the estimated densities of existing onshore wind turbines at a given respondent’s postal (ZIP) code level, we find evidence of a significant relationship between existing onshore wind power development and preferences for proposed OWF locations.

PVSails: Harnessing Innovation With Vertical Bifacial PV Modules in Floating Photovoltaic Systems

AbstractIn the context of offshore floating photovoltaic systems (FPVs), this paper explores the use of bifacial photovoltaic modules installed in the vertical position. The energy harvested from the rear face of vertically configured bifacial PV modules compensates for the reduced production at the front face of the module, and this demonstrates the potential of bifacial technology for offshore applications. By comparison, most existing horizontally tilted bifacial FPV systems gain only a small benefit in production from the rear face of the module due to the minimum radiation received, and what also must be taken into consideration is the negative effect of significant soiling owing to the low tilt angle of the PV modules. Hence, to overcome these drawbacks, we have developed the innovative “PVSail” concept, which explores the deployment of vertical FPV systems on floats, buoys, or poles/minipiles. Floating vertical bifacial PV systems (VBPVs) have huge potential to harness all the energy generation capabilities enhance by reflected light, especially from snow‐covered surfaces in northern regions. Our analysis considers a patented mooring and vertical PV system that allows the VBPV structure to align with the prevailing wind direction to shed wind loads, and our numerical analysis explores the potential of VBPV applied to Catania in Italy and Nigg Bay in the United Kingdom. Our analysis study has revealed that across an azimuth angle range (0°–180°), vertical bifacial modules experience roughly a 9% decrease in energy yield at Catania and about a 5% energy yield gain in higher latitude regions like Nigg Bay. Additionally, increasing the latitude of the installation location of VBPV reduces the energy yield sensitivity to the orientation, that is, azimuth angle. The PVSail concept opens the door to novel deployment possibilities in offshore renewable energy projects.

Dynamic response of seabed in wind power of deep-shallow sea induced by internal solitary waves

With the development of offshore wind power projects worldwide, the stability of deep and shallow sea wind power sites has become a crucial concern. Internal solitary waves (ISWs) are nonlinear and large amplitude waves in the stratified ocean. Their strong vertical and horizontal motion and vorticity and turbulence caused by fragmentation have an important impact on the marine environment, seabed sediments, and marine engineering. This study focuses on the interaction between ISWs and the seabed of wind power sites in deep and shallow seas. Specifically, we investigate the interaction between ISWs and monopile foundations or floating fan plate anchor structures in the seabed. Through the simulation of CFD software and Comsol software, a law of seabed pore pressure variation during the effect of ISWs on the structure can be well demonstrated. Our results demonstrate that ISWs induce the accumulation of excess pore water pressure around the structures. The monopile foundation experiences negative excess pore water pressure at its bottom and the plate anchor at its top. The pore water pressure at the bottom of the monopile foundation initially decreases and then increases. In contrast, the pore water pressure at the right side of the monopile foundation increases, decreases, and then increases. This phenomenon promotes the settlement of the structure. At the bottom of the plate anchor, there is a sharp increase in positive excess pore water pressure by ISW. The pore water pressure above the plate anchor structure initially decreases and then increases, while below the plate anchor, it increases and then decreases. This phenomenon leads to the movement of the anchorage structure and instability of the surrounding soil. The influence of ISWs on the seabed bottom intensifies with the obstruction of the structure, resulting in significant positive pressure at the bottom. Between the two anchoring structures, there is increased seepage of pore water, making the seabed more prone to instability. Through the study of this article, we know that ISW has different effects on the force of monopile foundation and plate anchor structure, which provides a favorable basis for its design and maintenance.

Spatio-Temporal Compressive Behaviors of River Pebble Concrete and Sea Pebble Concrete in Island Offshore Engineering

Obtaining river or sea pebbles from local resources for concrete production is considered an economical and eco-friendly alternative, particularly in marine and island-offshore engineering. However, the resulting changes in the mechanical properties of these concrete have attracted attention. This study investigates the compressive behavior of concretes where river or sea pebbles partially (i.e., 33% and 67%) or fully (i.e., 100%) replace traditional gravel as coarse aggregate, using a noncontact full-field deformation measurement system based on digital image correlation (DIC). Compared to the traditional gravel concrete (GC), compressive strengths of the river pebble concrete (RPC) at constitution rates of 33%, 67%, and 100% decreased by 6.5%, 29.8%, and 38.9% while those values of the sea pebble concrete (SPC) decreased by 13.1%, 32.7%, and 44.3%, respectively. Meanwhile, SPC exhibited slightly lower compressive strength than RPC. The peak strains of both SPC and RPC decreased at lower substitution rates, although their stress-strain curves resembled those of GC. In contrast, RPC and SPC at higher substitution rates exhibited a noticeable stage of load hardening. Full-field deformation data and interfacial characteristics indicated that the compressive failure modes of both RPC and SPC showed significant interfacial slipping between pebbles and mortar with increasing coarse aggregate substitution rates. In comparison, fractures in coarse aggregate and mortar were observed in damaged GC. The study demonstrated that the spatio-temporal compressive deformation response and failure modes of SPC and RPC were distinct due to the introduction of pebbles, providing insights for engineering applications of river/sea pebble concrete in practical offshore or island construction projects.

Evaluating soil thermal conductivity for buried infrastructure: Impact of water salinity, mineral composition, and moisture content on heat transfer

Thermal conductivity of soils is a critical soil property in geotechnics, which provides essential information about the soil's ability to conduct heat transfer. Erroneous data can be responsible for the inefficient design of buried infrastructure systems that rely on heat transfer, such as buried cables, piping, and geothermal systems. There is a lack of fundamental knowledge on the soil thermal conductivity under in-situ conditions factoring soil type, alteration in moisture content, and salinity. Our research aims to address how groundwater, flooding, or drought can impact thermal conductivity due to moderate-to-high soil salinity levels; as these may be critical factors to be considered in soil thermal conductivity testing for infrastructure. This study investigated the influence of salinity concentrations on soil thermal conductivity, with potential implications for areas with a high water table, rainfall, or flooding events, as well as offshore wind projects. This study accounted for variations in soil type and water salinity concentrations when testing for the thermal conductivity of soil. Twenty-three (23) experimental tests were conducted with a resulting 36 thermal conductivity data points recorded. The results were further analyzed in comparison with data results obtained from using the current industry-accepted methodology, which does not account for varying salinity concentrations. The results suggest that sand soil was most conductive when added with 15 g/L brine. Further, the salinity concentration or soil type can increase (silty clay) or decrease (sandy soil) soil thermal conductivity at varying moisture contents, which could provide a more informed, economical design for buried infrastructure that relies on heat transfer through soils.

Subsurface storage capacity in structural traps in underexplored sedimentary basins: Hydrogen (H 2 ) and carbon dioxide (CO 2 ) storage on the Irish Atlantic margin

Abstract Methodologies for storage assessment developed for basins with dense data coverage are typically not optimally applicable to underexplored sedimentary basins. To address this, a methodology and workflow for storage assessment in underexplored basins is presented which uses existing datasets to identify structural traps and populate a fluid-in-place equation which can be used for a variety of gases including CO 2 and H 2 . This is then applied to the Irish Atlantic margin; Jurassic, Triassic and Carboniferous reservoirs are investigated to understand their reservoir quality and extent, and related seals. Structural trap types are described and the theoretical capacities of three candidate sites with varying data coverage are calculated. The results highlight the potential for underexplored sedimentary basins on the Irish Atlantic margin to support offshore renewable energy projects and reduce Ireland's CO 2 emissions. This workflow is applicable to a variety of underexplored sedimentary basins and emphasises the utility of legacy hydrocarbon datasets for early-stage subsurface storage assessment. Other aspects of energy storage are also discussed, including man-made salt caverns, other candidate reservoir-seal pairs, and the potential for collaborative infrastructure development with CO 2 emitters and renewable energy projects.