Offshore Installations Research Articles

Innovative Photovoltaic Cooling System

With the ever-increasing adoption of solar energy and the lack of space for PV installations, targeting maximum photovoltaic operational efficiencies has become essential. One of the key challenges faced by PV installations in warm climates is thermal management, which is caused by increasing temperatures due to PV conversion inefficiencies and limited ventilation possibilities in certain installations. Despite prior art, further improvement is still needed to provide a novel system that can offer more efficient and controllable temperature decrease of photovoltaic modules in both land and offshore installations. The present invention, termed IPCoSy, satisfies the aforementioned needs in the art by providing a novel system for cooling a solar panel assembly, including at least one photovoltaic module having a plurality of solar cells generating electrical power and a PV junction box attached to the back of the photovoltaic module. A part of this invention discloses a new type of PV module that is a modification of standard commercial modules. This new PV module incorporates a water chamber at the back of a solar cell assembly to regulate operational temperatures. Another part of this invention presents an after-market cooling system that can be fitted to existing standard PV modules to add the cooling effect. This part of the invention presents solid and flexible water tanks that can be fitted directly into a gap at the back of standard PV modules. Moreover, this invention presents details on parts that distinguish this cooling system from prior art, such as an internal stream spreader to obtain better fluid dynamics and external fittings that allow the PV module to be installed at any tilt angle without jeopardising the cooling effect. Finally, this invention discloses different application areas of this cooling system, such as residential and industrial water heating, reverse osmosis plants and offshore photovoltaic installations, showcasing the product's versatility, adaptability and large market suitability.

EL FUTURO DE LOS AEROGENERADORES OFFSHORE: EVOLUCIÓN Y PERSPECTIVA DE LAS TECNOLOGÍAS DIRECT-DRIVE Y CON CAJA DE CAMBIOS TRADICIONAL

Currently, the installed wind power capacity around the world in offshore installations is more than 60 GW, with a much higher growth rate than traditional onshore installations. This is due to the lack of barriers in the high seas, which means that air flows at a higher and more regular speed, allowing a greater amount of energy to be generated than in traditional onshore installations, which can even double it.

Mechanical characterization procedure of HMPE fiber for offshore mooring in deep waters

For several offshore installations, especially those for exploration of offshore resources, such as Floating Production Storage and Offloading (FPSO), the stability of subsea pipelines and exploration risers are closely related to the mooring system. High performance polymeric fibers have been used in recent decades for offshore mooring, more recently polyester has been challenged by advancement in ultra-deep waters due to its considerable elongation. A candidate fiber for lower elongation mooring systems is high modulus polyethylene (HMPE). The work describes mechanical characterization procedures in high modulus polyethylene fibers envisioning the possibility of offshore mooring systems made entirely with HMPE, which allow deeper water depths, as well as stability to the pipelines. As a result, the fiber is suitable for mechanical strength and linear tenacity. It still shows good performance in abrasion resistance, and loss of inelastic portions in cyclic loads. However, the behavior in creep, due to its slightly high strain rates, restricts its use, but recent fibers known as "Low creep" can be studied, allowing complete mooring systems made with HMPE.

The stress-strain state of an underwater offshore gas pipeline and installation of compensators-stops intended to prevent its ascent

The brief information contains information about the surfacing of pipes at the underwater crossing of the Bovanenkovo-Ukhta gas pipeline, laid in the Kara Sea, and describes the design features of the concreted pipes. In the formulation of the problem of the stressstrain state (SSS) of the underwater crossing of an offshore gas pipeline, it is conventionally divided into the middle and extreme parts. In the middle part, the pipe is completely flooded and exposed due to the erosion of soil from it. In the extreme underground parts in which expansion joints are installed, the pipe is not exposed; it remains in the trench, covered with soil during the construction of the pipeline. The problem was solved by the finite element method in displacements. Calculations of the SSS of the gas pipeline section were carried out taking into account the uneven settlement of the foundation soil, different values of operating parameters and the installation of compensator stops of various designs. Using a numerical experiment, critical values of operating parameters were found and the effective operation of compensator stops of various designs was revealed. Keywords: gas pipeline; concreted pipe; soil; bending; deflection; stress; pressure; force; ascent; compensator-stop.

Assessing areas suitable for offshore wind energy considering potential risk to breeding seabirds in northern Japan

Offshore wind energy is expected to play a major role in realizing carbon neutrality. However, the installation of offshore wind turbines is of concern for breeding seabirds. Identifying areas with low potential risk for breeding seabirds in Japan is urgently needed. This study identified technically and legally potential areas for wind energy development that are suitable for breeding seabirds by integrating risk assessment models through a spatial approach using Geographic Information System (GIS). While many studies and the government have assessed the potential areas for offshore wind energy in northern Japan, this study shows that most of these legally potential areas overlap with major concern areas for breeding seabirds. Currently, Japanese rules do not sufficiently consider the risk to seabirds when zoning areas for installing offshore wind energy system. The results imply that the risk to breeding seabirds should be carefully examined when zoning areas for local offshore wind energy installations. The approach developed in this study is expected to aid in clearly identifying areas suitable for the installation of offshore wind turbines and minimize the impacts on breeding seabirds. It provides a balance between the expansion of offshore wind energy and conservation biology.

Research on Pneumatic Control of a Pressurized Self-Elevating Mat for an Offshore Wind Power Installation Platform.

Efficient deep-water offshore wind power installation platforms with a pressurized self-elevating mat are a new type of equipment used for installing offshore wind turbines. However, the unstable internal pressure of the pressurized self-elevating mat can cause serious harm to the platform. This paper studies the pneumatic control system of the self-elevating mat to improve the precision of its pressure control. According to the pneumatic control system structure of the self-elevating mat, the pneumatic model of the self-elevating mat is established, and a conventional PID controller and fuzzy PID controller are designed and established. It can be seen via Simulink simulation that the fuzzy PID controller has a smaller adjustment time and overshoot, but its anti-interference ability is relatively weak. The membership degree and fuzzy rules of the fuzzy PID controller are optimized using a neural network algorithm, and a fuzzy neural network PID controller based on BP neural network optimization is proposed. The simulation results show that the overshoot of the optimized controller is reduced by 9.71% and the stability time is reduced by 68.9% compared with the fuzzy PID. Finally, the experiment verifies that the fuzzy neural network PID controller has a faster response speed and smaller overshoot, which improves the pressure control accuracy and robustness of the self-elevating mat and provides a scientific basis for the engineering applications of the self-elevating mat.

Hydrogen for harvesting the potential of offshore wind: A North Sea case study

Economical offshore wind developments depend on alternatives for cost-efficient transmission of the generated energy to connecting markets. Distance to shore, availability of an offshore power grid and scale of the wind farm may impede export through power cables. Conversion to H2 through offshore electrolysis may for certain offshore wind assets be a future option to enable energy export. Here, we analyse the cost sensitivity of offshore electrolysis for harvesting offshore wind in the North Sea using a technology-detailed multi-carrier energy system modelling framework for analysis of energy export. We include multiple investment options for electric power and hydrogen export including HVDC cables, new hydrogen pipelines, tie-in to existing pipelines and pipelines with linepacking. Existing hydropower is included in the modelling, and the effect on offshore electrolysis from increased pumping capacity in the hydropower system is analysed. Considering the lack of empirical cost data on offshore electrolysis, as well as the high uncertainty in future electricity and H2 prices, we analyse the cost sensitivity of offshore electrolysis in the North Sea by comparing costs relative to onshore electrolysis and energy prices relative to a nominal scenario. Offshore electrolysis is shown to be particularly sensitive to the electricity price, and an electricity price of 1.5 times the baseline assumption was needed to provide sufficient offshore energy for any significant offshore electrolysis investments. On the other hand, too high electricity prices would have a negative impact on offshore electrolysis because the energy is more valuable as electricity, even at the cost of increased wind power curtailment. This shows that there is a window-of-opportunity in terms of onshore electricity where offshore electrolysis can play a significant role in the production of H2. Pumped hydropower increases the maximum installed offshore electrolysis at the optimal electricity and H2 prices and makes offshore electrolysis more competitive at low electricity prices. Linepacking can make offshore electrolysis investments more robust against low H2 and high electricity prices as it allow for more variable H2 production through storing excess energy from offshore. The increased electrolysis capacity needed for variable electrolyser operation and linepacking is installed onshore due to its lower CAPEX compared to offshore installations.

Adaptive dynamic positioning control of an offshore wind turbine installation vessel subjected to thruster dynamics and input constraints

This paper suggests an adaptive positioning control method for a DP-equipped offshore wind turbine installation vessel. The method combines a finite-time disturbance observer (FTDO) with adaptive command filtered backstepping (CFB) to handle issues related to thruster dynamics, input saturation, model parameter uncertainties, and unknown environmental disturbances. By analyzing the environmental loads acting on the pile legs, a mathematical model for the installation vessel is established. To counteract the unknown disturbance actively, a FTDO is utilized. Additionally, an auxiliary dynamic system (ADS) is used to mitigate the thruster input saturation issue. Then an adaptive positioning controller is designed based on the FTDO and ADS, and Lyapunov stability theory is used to prove that all signals in the control system remain uniformly ultimately bounded. Numerical simulations are conducted to verify the effectiveness of the proposed control approaches.

An approximated dynamic programming model for the supply vessel fleet sizing problem

The offshore oil and gas exploration and production activities heavily rely on a fleet of supply vessels, which play a crucial role in regularly providing necessary provisions from an onshore supply depot to the offshore installations. For Petrobras, the decision-making process concerning the number of supply vessels to be hired for the upcoming two years holds significant economic implications, given that the daily rates for a single supply vessel can soar to tens of thousands of USDs.In this study, we address the challenges of this heterogeneous fleet sizing problem by presenting an innovative approximated dynamic programming (ADP) model. The model takes into account the uncertainties associated with sea conditions and future demand, making it well-suited for real-world applications. To tackle this problem, we explored two types of approximate value functions: a piecewise linear concave value function and a neural network value function. Both methods underwent rigorous testing and demonstrated their capability to effectively address real-world problems. Consequently, our proposed method exhibits promising potential for practical implementation, allowing companies like Petrobras to accurately assess and determine the ideal fleet composition. By introducing this ADP model, we aim to provide valuable insights and solutions that enhance decision-making processes related to supply vessel fleet sizing in offshore operations. Through considering various uncertainties and complexities, our approach offers a robust and reliable framework to support critical economic decisions in this dynamic industry.

Feasibility Analysis of Offshore Wind Power Projects in the Caribbean Region of Colombia: A Case Study Using FAHP–GIS

Planning for offshore wind energy projects is intricate due to the consideration of multiple variables in identifying optimal project areas. The primary challenge lies in locating suitable sites, a process that often necessitates extensive feasibility studies spanning several years. The primary goal of this study is to apply the Fuzzy Analytic Hierarchy Process (FAHP) to prioritize criteria and sub-criteria, facilitating decision-making in choosing appropriate locations for offshore wind projects in the Colombian Caribbean Sea. The weights derived from FAHP were utilized in a Geographic Information System (GIS) to analyze the physical characteristics of the Caribbean Sea’s surface. This tool plays a critical role in evaluating and selecting sites that fulfill established criteria, providing a database of indicators and map visualizations. Four criteria were defined: technical, environmental, social, and economic, along with fourteen sub-criteria, which were prioritized through FAHP based on expert judgment. The results revealed that the most relevant sub-criteria were protected areas and wind speed. Utilizing the ArcGIS Pro software, five zones meeting the predetermined criteria were identified, defining the most feasible areas for offshore wind farm installation, located in the departments of Guajira, Magdalena, Atlántico and Bolívar. The GIS–FAHP methods proved to be useful for feasibility analysis.

High variability and exceptionally low thermal conductivities in nearshore sediments: a case study from the Eckernförde Bay

Heat flow measurements are a standard technique in Geophysics both onshore and offshore. Recently, such measurements became increasingly important in shallow waters. The increasing amount of offshore power installations makes it necessary to have a good knowledge about the subsurface heat flow and the thermal properties of the sediments to optimize the construction of the necessary powerlines. While the thermal properties are well studied for deep ocean sediments, only few published data exist for nearshore sediments. In this study, we investigate the sediment temperatures and thermal conductivities of nearshore sediments in the German part of the Baltic Sea. The shallow sediment temperatures reflect the interplay of the response to the seasonal cycle in connection with the sediments’ thermal conductivity. We find thermal conductivity values ranging from 0.67 to 3.34 W/(m*K) for the sediments down to ~ 4.2 m below seafloor. This variability exceeds that of conservative estimates widely used for coastal sediments and is also much higher than the variability found in the deep oceans. Sandy sediments show thermal conductivities larger than 1 W/(m*K) whereas organic-rich muds have lower values (< 1 W/(m*K)). Furthermore, the thermal conductivities seem to decrease with increasing free gas content in the sediment. The latter needs to be confirmed by further investigations.

Research on process safety of offshore wind turbines installation: A theoretical model and empirical evidence

As the world energy problem becomes more and more prominent, offshore wind farms have made remarkable progress in the last few years. With the advent of the rush to install offshore wind turbines around the world, offshore wind turbine (OWT) installation accidents have gradually increased. The process safety associated with offshore wind turbine installations has been a growing concern in offshore wind industry. To address this issue, this study aims to identify the factors affecting offshore wind turbine installation process safety, and to evaluate the correlations among these factors. The study involved an investigation into the causes and procedures of accidents that occurred during offshore wind turbine installation, leading to the development of customized safety factors. A questionnaire survey was developed and administered by a team of offshore wind industry professionals, including scholars, managers, and workers, and the data collected was analyzed using a theoretical model based on structural equation modeling. The results show that environment and weather condition, organization and management, and OWT installation technology have a significant impact on OWT installation technology. Furthermore, OWT installation technology has the largest total effect on the process safety of OWT installation.

Solid Rubber Fenders to Prevent Structural Damage in a Lowspeed Collision Between a Ship-Shaped Offshore Installation and a Shuttle Tanker Working Side-by-Side in Offloading Operation

Ships and ship-shaped offshore installations are commonly equipped with pneumatic or solid rubber fenders to absorb kinetic energy during collisions, thereby reducing structural damage. The energy absorption capacity of these fenders must be precisely evaluated via reliable experimental, analytical, and numerical methods to ensure that the fenders are capable of preventing collision-associated structural failures. Accordingly, this study developed computational modelling techniques for analysing the energy absorption capacity of solid rubber fenders. Modelling was performed using LS-DYNA, a commercial software package for finite element simulation, and the developed models were validated by comparison with data from crushing tests on two types of solid rubber fender models – circular tube and V-shaped rubber fenders. The validated computational models were applied to examine a case study of a low-speed collision between a Suezmax class shuttle tanker and a very-large-crude-oil-carrier (VLCC) class ship-shaped offshore installation working side-by-side in offloading operation, with the latter equipped or not equipped with V-shaped rubber fenders, respectively. The results revealed that such fenders were effective protection against structural damage in such a collision scenario.

Numerical Investigations of Turbulent Flow Through A 90-Degree Pipe Bend And Honeycomb Straightener

Abstract Pipe bends are commonly used in piping systems in offshore and subsea installations. The present study explores the design considerations for the honeycomb straightener inserted downstream of a 90-degree pipe bend. The objective of the study is to evaluate the effectiveness of the honeycomb in suppressing the flow swirling for different distances from the bend outlet (Lb) and different values of the honeycomb thickness (t). The turbulent flow through the 90-degree circular pipe bend with the honeycomb straightener is investigated by carrying out numerical simulations using the Reynolds-Averaged Navier-Stokes (RANS) turbulence modeling approach. The Explicit Algebraic Reynolds Stress Model (EARSM) is adopted to resolve the Reynolds stresses. The honeycomb thickness to pipe diameter ratio (t/D) is varied between 0.1 and 1. The normalized distance from the bend outlet to the honeycomb straightener (Lb/D) is varied between 1 and 5. The disturbance in the velocity field is generated by the pipe bend with the curvature radius to pipe diameter ratio (Rc/D) of 2 and Reynolds number (Re) of 2×105. It is found that both the increase in Lb/D and t/D improves the performance of the device in removing the swirl behind the bend outlet. The best performance is observed for the honeycomb straightener with the distance Lb/D=5 and thickness t/D=0.5.

Mechanical Performance of Adhesive Connections in Structural Applications.

Adhesive bonding is an excellent candidate for realising connections for secondary structures in structural applications such as offshore wind turbines and installations, avoiding the risk and associated welding problems. The strength of the adhesive layer is an important parameter to consider in the design process it being lower than the strength capacity of the bonding material. The presence of defects in the adhesive materials undoubtedly influences the mechanical behaviour of bonded composite structures. More specifically, the reduction in strength is more pronounced as the presence of defects (voids) increases. For this reason, a correct evaluation of the presence of defects, which can be translated into damage parameters, has become essential in predicting the actual behaviour of the bonded joints under different external loading conditions. In this paper, an extensive experimental programme has been carried out on adhesively bonded connections subjected to Mode I and Mode II loading conditions in order to characterise the mechanical properties of a commercial epoxy resin and to define the damage parameters. The initial damage parameters of the adhesive layer have been identified according to the Kachanov-Sevostianov material definition, which is able to take into account the presence of diffuse initial cracking.

A prospect theory extension of data envelopment analysis model for wave‐wind energy site selection in New Zealand

AbstractRenewable energy sources have been utilized by countries worldwide, but offshore energy exploitation projects remain highly promising for both the world and New Zealand specifically. The selection of equipment installation locations can be challenging and requires significant investment, prompting the need for optimization in offshore energy exploitation. Wind and wave location (WWL) integrated sites offer a highly potential solution for reducing installation costs and enhancing efficiency in renewable energy exploitation. However, the decision‐making process for selecting equipment locations is crucial and directly affects the outcome. This study aims to evaluate and consider sustainable and effective equipment installation sites based on both quantitative indicators and behavioral psychology of decision making. To achieve this goal, the study utilizes the prospect theory Data Envelopment Analysis (PT‐DEA) model, which builds on PT to analyze and evaluate the effectiveness of offshore installation site selection with consideration for human psychology. By combining the results of quantitative indicators and decision‐making behavior, the study identifies sustainable and effective offshore installation sites, recommending appropriate equipment installation locations WWL. The study is also compared and referenced with relevant plans, projects, and development policies in New Zealand for confirmation.

A Simplified Approach for Predicting Bend Radius in HDPE Pipelines during Offshore Installation

Traditionally, subsea pipelines designed for the transportation of oil, gas, and water are constructed using carbon steel due to its strength, toughness, and ability to operate at temperatures up to 427 °C. However, polyethylene (PE), especially its high-density variant (HDPE), presents advantages such as reduced installation costs, diminished water leakage, and superior corrosion resistance. As research endeavours to enhance PE properties, its adoption for subsea applications is anticipated to rise. This study first delineates the mechanical behaviour of HDPE pipelines for offshore installation, identifying pulling tension, dimension ratio, water depth, and air fill ratio as the paramount lay parameters. Subsequently, a theoretical bend radius equation was derived from pipelaying mechanics using a purely geometric approach. Within this equation, two determinants, parameter X and parameter Y, dictate the sagbend bend radius. Regression analysis elucidated the relationships of lay parameters with both X and Y, yielding a general equation for X in terms of pull tension, water depth, and air fill ratio and another for Y as a function of water depth. Together, these geometric determinants underpin the sagbend bend radius estimation model. For overbend bend radius prediction, a lay index (IL) was fashioned from the aforementioned three parameters. Correlation assessments between the lay index and overbend bend radius revealed R2 values of 0.940, 0.836, and 0.712 for pipes with diameters of 2.0, 2.5, and 3.0 metres, respectively. This underscores the model’s proficiency in predicting the bend radius, albeit with decreasing precision for larger-diameter pipelines.

A comparison of extreme mooring loads and response of a spar-buoy wind turbine using conditional waves

Three-hour random sea-state evaluations for ultimate limit state design of floating offshore wind installations are time-consuming and prevent the use of high-fidelity numerical methods from being implemented. In this work, three conditional waves, Most-Likely Wave (MLW), Most-Likely Response Wave (MLRW) and Conditional Random Response Wave (CRRW), are experimentally investigated as alternative means to generate statistical extreme responses in surge and mooring line loads of a spar-buoy substructure, with shorter time-series duration compared to a 3-hour JONSWAP sea-state. MLW and MLRW are found to generate the greatest mooring line loads, far greater than the statistical expected maximum from a 3-hour random sea-state. However, MLW is uncorrelated with the substructure’s linear transfer function of response, and the MLRW includes no memory effects from a random background sea, indicating possible conservatism in the associated load magnitudes. CRRW is a MLRW embedded within a random background and is found to excite a similar mooring load as the 3-hour sea-state, with memory effects included. CRRW could thus be an appropriate method of generating statistically appropriate load responses within a reduced time-series. However, nonlinear effects on the mooring are not accounted for in any of the methods and will be included in future work.

Impact of steel grade on a ship colliding with an offshore wind turbine monopile supporting structure

Offshore wind power is experiencing rapid development around the world. The number of installations and their size is growing. Thousands of monopile support structures with diameters of 10 m and weights of 2000 tons will be installed in the coming years. Offshore wind power installations, often located close to the shore and shipping routes, pose a new challenge to ship safety. The study analyses the damages from an accidental collision between a 6500-tonne displacement Supply Offshore Vessel and the monopile support structure with a 10 m diameter and a 15 MW wind turbine. The head-on collision cases are performed according to the DNV-ST-0126, showing the consequences for the ship and the wind turbine support structure. In addition, simulation cases with an offset between the ship's plane of symmetry and the monopile axis showed a new form of damage to the ship's plating. During a head-on sliding collision, extensive plate tearing can occur due to its cutting at the deck line and concertina tearing under the pressure of the monopile. As a result, the hull may open over a large area, including the threat of unsealing the ship's collision bulkhead. The S355 grade steel can significantly reduce collision damage by up to 50% (from 20.6 m2 to 10.5 m2 for the case studied here).

Renewable energy integration in offshore oil and gas installations

As the oil and gas industry seeks to reduce its carbon footprint and align with global decarbonization goals, integrating renewable energy sources into offshore operations presents a promising pathway. This review examines the feasibility of incorporating renewable energy technologies such as offshore wind, solar, and marine energy into the power supply of oil and gas installations. Offshore wind energy, with its high potential and scalability, emerges as a viable option for powering rigs, as demonstrated by projects like Hywind Tampen in Norway, which uses floating wind turbines to supply energy to oil platforms. Solar energy, while more limited in offshore environments due to space and weather constraints, can be part of hybrid systems combining multiple renewable sources. Marine energy, including tidal and wave power, is still in its developmental stages but holds promise for future applications. The review explores hybrid energy systems that integrate renewable sources with conventional energy, such as gas turbines, to ensure continuous power supply. Microgrid technologies and energy storage solutions are also discussed as essential components for balancing renewable energy’s intermittency and optimizing power distribution. Key challenges, such as the harsh marine environment, high initial investment, and the need for new infrastructure, are analyzed alongside potential solutions like technological innovations in floating renewable systems and automated monitoring technologies. Economic feasibility is considered through a cost-benefit analysis, highlighting the potential long-term savings from reduced fuel use and the benefits of regulatory incentives for renewable energy integration. Ultimately, the integration of renewables not only supports decarbonization but also offers operational efficiency and cost reduction opportunities. This review concludes by examining future trends in renewable energy for offshore installations and the potential for fully electrified, sustainable oil and gas platforms.