Subsea Cables Research Articles

Digital recognition: cybersecurity and internet infrastructure in UAE–Israel diplomacy

Abstract The 2020 Israel–UAE Abraham Accords normalized these states' relations, with heavy emphasis on digital technologies. International Relations theories of recognition, however, hardly consider the role digital technologies play in establishing recognition between states. What role, then, did digital technologies play in this landmark shift in UAE–Israel recognition? This article uses three aspects of digital technologies in the UAE–Israel case—cybersecurity cooperation, cloud computing, and subsea cables—to inductively develop three propositions regarding the role of digital technologies in state recognition. First, states use digital technologies—and private sector companies that own and operate them—as diplomatic lubrication: a means to navigate around and overcome difficult diplomatic relationships, building momentum towards recognition. Second, digital competition between states leads them to conform their national economic structures towards global technology companies in similar ways, thereby recognizing each other as equal participants in a global market—which we term market-oriented homogenization. Third, states involved in transnational internet infrastructure projects together develop technical working practices, interests, and dependencies that facilitate diplomatic recognition—which we term infrastructural integration. Building on these three propositions, we put forward an overall concept of ‘digital recognition’ to capture their common theme: the influence of digital technologies, their owners or their operators on state recognition.

Large-scale geohazards risk of submarine landslides considering the subsea cables vulnerability: A case study from the northern continental slopes of South China Sea

Submarine landslides pose significant threats to subsea cables distributed on the global seabed. However, regional scale risk assessment of landslide geohazards is rarely reported. This study introduces a methodology for regional-scale geohazard risk prediction of submarine landslides, focusing on the northern continental slopes of the South China Sea. Initially, the study employed the infinite-slope method to calculate safety factors for typical submarine slopes. Addressing uncertainties in geotechnical and seismic parameters, Monte Carlo simulations determine slope failure probabilities. Using kriging interpolation, localized failure probabilities are extrapolated to regional scales, establishing a spatiotemporal distribution method for large-scale geohazard susceptibility. Hazard levels are subsequently determined considering the volumes of potential landslides. The density of subsea cables is used as a vulnerability factor to guide the regional-scale assessment of cable vulnerability. Finally, integrating vulnerability with hazard levels provides a comprehensive assessment of landslide-induced large-scale geohazard risks. The findings highlight elevated geohazard risks in the Taiwan Bank slope segment, moderate risks in the Zhujiang Valley and Shenhu slope segments, with lower risks in other areas.

Accurate modeling and assessment of subsea cable’s unbalanced induced current for subsea cable considering the amore wires

AC subsea cables are grounded at both ends via two metal layers, namely metallic screen (normally made by lead for high voltage subsea cable as radial water barrier) and armor, which consists of wires. This topology leads to induced current in the two grounded layers. Field test shows that occasionally unbalanced induced current is observed in grounded layers (lead and armor) between two cable ends. The difference of induced current between two cable ends can be as high as half of the load current. The cause for such unbalance is not clear and it may endanger the cable system. To analyze the phenomena and prevent potential failure, detailed analytical modeling assisted with finite-element method (FEM) is proposed in this paper to accurately analyze the unbalanced induced current for AC subsea cable. FEM is utilized to model the armor wires as an equivalent homogeneous layer. With this validated method, comprehensive analysis is performed for unbalanced induced current of AC subsea cable. It is shown that the unbalanced current is due to the inequal impedances between grounding points at two cable ends and/or the extra introduced resistor between lead sheath and armor. Based on these findings grounding status and connection status between lead and armor can be evaluated via the induced currents. An evaluation tree is then proposed to help identify the cable defects.

The role of inter-island transmission in full decarbonisation scenarios for Indonesia’s power sector

Indonesia has large renewable energy resources that are not always located in regions where they are needed. Sub-sea power transmission cables, or island links, could connect Indonesia’s high-demand islands, like Java, to large-resource islands. However, the role of island links in Indonesia’s energy transition has been explored in a limited fashion. Considering Indonesia’s current fossil fuel dependency, this is a critical knowledge gap. Here we assess the role of island links in Indonesia’s full power sector decarbonisation via energy system optimisation modelling and an extensive scenario and sensitivity analysis. We find that island links could be crucial by providing access to the most cost-effective resources across the country, like onshore photovoltaics (PV) and hydropower from Kalimantan and geothermal from Sumatera. In 2050, 43 GW of inter-island transmission lines enable 410 GWp of PV providing half of total generation, coupled with 100 GW of storage, at levelised system costs of 60 US$(2021)/MWh. Without island links, Java could still be supplied locally, but at 15% higher costs due to larger offshore floating PV and storage capacity requirements. Regardless of the degree of interconnection, biomass, large hydro, and geothermal remain important dispatchable generators with at least 62 GW and 23% of total generation throughout all tested scenarios. Full decarbonisation by 2040 mitigates an additional 464 MtCO2e compared to decarbonisation by 2050, but poses more challenges for renewables upscaling and fossil capacity retirement.

Distributed acoustic sensing for seismic surface wave data acquisition in an intertidal environment

The application of distributed acoustic sensing (DAS) for shallow marine seismic investigations is assessed, in particular with respect to the collection of seismic surface wave data in an intertidal setting. Appropriate selection and directional sensitivity of fiber-optic cables is considered and the measured data is validated with respect to conventional seismic data acquisition approaches, using geophones and hydrophones, along with independent borehole and seismic cone penetration test (SCPT) data. In terms of cable selection, a reduction in amplitude and frequency response of an armored cable is observed, when compared with an unarmored cable. For seismic surface wave surveys in an offshore environment where the cable would need to withstand significant stresses, the use of the armored variant with limited loss in frequency response may be acceptable from a practical perspective. The DAS approach also has indicated good consistency with conventional means of surface wave data acquisition, and the inverted [Formula: see text] also is very consistent with downhole SCPT data. Observed differences in phase velocity between high tide (Scholte wave propagation) and low tide (Rayleigh wave propagation) are not thought to be related to the particular type of interface wave due to shallow water depth. These differences are more likely to be related to the development of capillary forces in the partially saturated granular medium at low tide. Overall, this study demonstrates that our novel approach of DAS using seabed fiber-optic cables in the intertidal environment is capable of rapidly providing near-surface S-wave velocity data across considerable spatial scales (multikilometer) at high resolution, which is beneficial for the design of subsea cables routes and landfall locations. The associated reduction in deployment and survey duration, when compared with conventional approaches, is particularly important when working in the marine environment due to potentially short weather windows and expensive downtime.

Attitude-Independent Route Tracking for Subsea Power Cables Using a Scalar Magnetometer under High Sea Conditions

To overcome the shortcoming wherein the accuracy of subsea cable detection can be affected by the determination of the bias vector, scale factors, and non-orthogonality corrections of the vector magnetometer, a real-time attitude-independent route tracking method for subsea power cables is investigated theoretically and experimentally by means of scalar magnetic field checking. The measurement of the magnetic field Bc produced by the current in a cable is made immune to the influence of the platform attitude by extracting the component of Bc along the geomagnetic field using a high-bandwidth self-oscillating optically pumped magnetometer. The self-oscillating frequency is proved to be independent of the attitude of the magnetometer with the theoretical model. Experiments are carried out to test the attitude-independent performance, and the effectiveness of route tracking is verified by the results of the sea experiment. The proposed method will effectively improve the ability to locate subsea cables under high sea conditions.

Electromagnetic Localization and Tracking Control of Underactuated Autonomous Underwater Vehicle for Subsea Cable Detection

Electromagnetic Localization and Tracking Control of Underactuated Autonomous Underwater Vehicle for Subsea Cable Detection

Optimizing Optical Engine Features for Subsea Cable Systems

Optimizing Optical Engine Features for Subsea Cable Systems

Alternatives for Transport, Storage in Port and Bunkering Systems for Offshore Energy to Green Hydrogen

Offshore electricity production, mainly by wind turbines, and, eventually, floating PV, is expected to increase renewable energy generation and their dispatchability. In this sense, a significant part of this offshore electricity would be directly used for hydrogen generation. The integration of offshore energy production into the hydrogen economy is of paramount importance for both the techno-economic viability of offshore energy generation and the hydrogen economy. An analysis of this integration is presented. The analysis includes a discussion about the current state of the art of hydrogen pipelines and subsea cables, as well as the storage and bunkering system that is needed on shore to deliver hydrogen and derivatives. This analysis extends the scope of most of the previous works that consider port-to-port transport, while we report offshore to port. Such storage and bunkering will allow access to local and continental energy networks, as well as to integrate offshore facilities for the delivery of decarbonized fuel for the maritime sector. The results of such state of the art suggest that the main options for the transport of offshore energy for the production of hydrogen and hydrogenated vectors are through direct electricity transport by subsea cables to produce hydrogen onshore, or hydrogen transport by subsea pipeline. A parametric analysis of both alternatives, focused on cost estimates of each infrastructure (cable/pipeline) and shipping has been carried out versus the total amount of energy to transport and distance to shore. For low capacity (100 GWh/y), an electric subsea cable is the best option. For high-capacity renewable offshore plants (TWh/y), pipelines start to be competitive for distances above approx. 750 km. Cost is highly dependent on the distance to land, ranging from 35 to 200 USD/MWh.

Cryogenic Comminution of Subsea Cables and Flowlines: A Pathway for Circular Recycling of End-of-Life Offshore Infrastructure

Hundreds of thousands of kilometers of communication and power (umbilical) cables and flowlines lie undersea worldwide. Most of these offshore cables and flowlines have reached or will soon be nearing the end of their service life, prompting the need for a viable recycling approach to recover some valuable material, e.g., copper. However, separation into constituent materials has proven very challenging due to the highly robust design of the composite cables (and flowlines) to withstand service conditions and the tough external plastic sheaths that protect against seawater corrosion. This study aims at promoting sustainable practices in the offshore energy sector. Here, we summarize the findings of the cryogenic comminution of subsea cables and flowlines for an effective separation and recovery of component materials. Heat transfer analyses of complex multilayer flowlines and umbilicals were conducted to evaluate the time required for these structures to reach their respective critical brittle-transition temperatures. Subsequently, the time was used as a guide to crush the flowline and umbilical cables under cryogenic conditions. The results show that the flowlines and umbilical cables will reach the brittle-transition temperature after approximately 1000s (i.e., 17 min) of submergence in liquid nitrogen (LN). Comminution of the materials at temperatures near the brittle-transition temperature was proven relatively efficient compared to room-temperature processing. The present evaluation of heat transfer and lab-scale crushing will afford accurate process modelling and design of a pilot cryogenic comminution of decommissioned subsea cables and flowlines, enabling the sustainable recovery of valuable materials that can provide a new stream of waste-to-wealth economy.

Adaptive Neural Control of Flight-Style AUV for Subsea Cable Tracking Under Electromagnetic Localization Guidance

This article focuses on an industrial system for the intelligent inspection of subsea cables based on a flight-style autonomous underwater vehicle (AUV) that tracks the route of subsea cable guided by electromagnetic localization signals. The intelligent inspection system consists of electromagnetic localization and autonomous tracking control modules. The electromagnetic localization algorithm for subsea cable is geometrically derived based on the electromagnetic sequences measured with two triaxial sensors that are symmetrically mounted on the forewings of a flight-style AUV. The argument results on the singularity, sensitivity, and consistency of the localization algorithm provide guidelines for designing the cable-tracking AUV prototypes and planning the near-bottom cable-tracking tasks. Subsequently, the cable-tracking control schemes for decoupled AUV heading and diving subsystems are developed by using the localization results. Particularly, the vector field guidance based on the localization results is designed to overcome the challenges, including underactuation and the lack of cable-tracking error dynamics. To minimize the electromagnetic noise interference and to relax the dependence on the accurate AUV hydrodynamics, the kinematic virtual control signals are filtered with low-pass filters, and neural networks are applied to approximate dynamics. Finally, an integrated simulation study is presented to demonstrate the effectiveness and robustness of the proposed electromagnetic localization-guided autonomous cable-tracking system.

SMART submarine cable technology can facilitate acoustics on the global scale

The submarine cable industry is beginning to share their infrastructure for ocean observing. Science Monitoring And Reliable Telecommunications (SMART) Subsea Cables is working to integrate temperature, pressure, and seismic acceleration sensors into commercial cables (∼70 km spacing) to support climate monitoring and disaster risk reduction on the global scale. The seismic and pressure sensors are expected to have sensitivity at low acoustic frequencies, (e.g., <50 Hz and <5 Hz, respectively); future systems could include hydrophones and other sensors. Further, telecom rated branching cables supporting multipurpose “nodes” are becoming a reality (per existing dedicated science cable systems). These can support low frequency transceivers and autonomous undersea vehicles (AUVs). With cabled power, these would be part of the fixed/mobile acoustic tomography system measuring ocean heat content and more generally for transporting energy, data, and acquiring multidisciplinary data throughout a large volume of the ocean. A 3700 km SMART ring system in Portugal will be ready in 2026 and one connecting Vanuatu and New Caledonia is starting. Others in planning stages that could include these concepts are: Far North Fiber connecting Norway/Finland/Ireland with Japan, the NSF proposed SMART cable connecting New Zealand with Antarctica, New Zealand-Chatham Islands, and Lisbon-Egypt through the Mediterranean.

Flying the skies to wire the seas: Subsea cables, remote work, and the social fabric of a media industry

Since the commercial aviation boom in the 1960s and 70s, the subsea cable industry has relied on global air travel for network development, infrastructure maintenance, and market penetration. However, COVID-19 disruptions forced a shift to remote work, challenging traditional travel practices and presenting an opportunity for carbon emission reduction. This study investigates the industry’s response to the “new normal” and its implications for mobility and sustainability. We employ a media industries approach and conduct open-ended interviews with industry leaders to examine the potential balance between remote work benefits and essential in-person aspects, questioning whether the industry should return to pre-pandemic travel levels or embrace remote work’s ecological and financial benefits. Our findings indicate that remote work suitability varies depending on project stage, involved personnel, and the existing social fabric. To facilitate travel-related carbon footprint monitoring for cable consortiums, we developed a calculator to determine the industry’s emissions when adopting remote work. Our interdisciplinary study also emphasizes mobility’s intricate role in subsea cable systems and broader media infrastructure studies. By scrutinizing corporate cultures, communication practices, and transportation infrastructures, we enhance the scholarly comprehension of the social fabric underpinning global digital networks and investigate potential shifts toward a more sustainable media industry.

Investigating Ice Loads on Subsea Pipelines with Cohesive Zone Model in Abaqus

Subsea pipelines and cables placed in ice-prone regions may be at risk of iceberg damage. In particular, pipes that are not buried may come in direct contact with iceberg keels. Knowing the range of interaction forces helps to assess the types and magnitudes of potential damage. Experimental studies provide the most valuable data about the interaction forces, while numerical modeling may give insight into configurations that are difficult to study experimentally. This work applies the cohesive zone model to investigate the fracture behavior of ice samples. Simulations are performed in 2D with Abaqus explicit solver. Modeled interaction forces from multiple simulations are recorded and compared to understand how the geometry of the samples affects the fracture. Repeat interactions with different grain configurations are conducted to investigate associated variance in fracture patterns and loads. t-tests show that the force application angle and the indenter’s position significantly affect the fracture force.

Subsea Power Cable Health Management Using Machine Learning Analysis of Low-Frequency Wide-Band Sonar Data

Subsea power cables are critical assets for electrical transmission and distribution networks, and highly relevant to regional, national, and international energy security and decarbonization given the growth in offshore renewable energy generation. Existing condition monitoring techniques are restricted to highly constrained online monitoring systems that only prioritize internal failure modes, representing only 30% of cable failure mechanisms, and has limited capacity to provide precursor indicators of such failures or damages. To overcome these limitations, we propose an innovative fusion prognostics approach that can provide the in situ integrity analysis of the subsea cable. In this paper, we developed low-frequency wide-band sonar (LFWBS) technology to collect acoustic response data from different subsea power cable sample types, with different inner structure configurations, and collate signatures from induced physical failure modes as to obtain integrity data at various cable degradation levels. We demonstrate how a machine learning approach, e.g., SVM, KNN, BP, and CNN algorithms, can be used for integrity analysis under a hybrid, holistic condition monitoring framework. The results of data analysis demonstrate the ability to distinguish subsea cables by differences of 5 mm in diameter and cable types, as well as achieving an overall 95%+ accuracy rate to detect different cable degradation stages. We also present a tailored, hybrid prognostic and health management solution for subsea cables, for cable remaining useful life (RUL) prediction. Our findings addresses a clear capability and knowledge gap in evaluating and forecasting subsea cable RUL. Thus, supporting a more advanced asset management and planning capability for critical subsea power cables.

An initial spatial conflict analysis for potential deep-sea mining of marine minerals in U.S. Federal Waters

Demand for critical minerals is projected to double or even triple by 2030 as the global energy and transportation sectors transition away from fossil fuels toward renewable energy. This anticipated demand raises interest in new critical mineral resources, including marine minerals, to supplement future supplies. While the environmental benefits of transitioning to green energy are many, there are inherent environmental costs. In this study, we compiled broad-scale datasets of prominent environmental features and human uses within four deep ocean regions of the U.S. Exclusive Economic Zone where marine minerals are predicted to occur, called prospective regions: they are the Blake Plateau, the Hawaiian Islands, Offshore California, and the Gulf of Alaska. We generated a normalized metric to score regions based on the co-occurrence of either environmental or human use variables within hexagonal grid cells, allowing us to assess the occurrence intensity and spatial patterns of environmental and/or human use variables within each region. Driven by the presence of threatened species and total species richness, the Blake Plateau and the Hawaiian Islands have the highest environmental occurrence scores, followed by Offshore California and the Gulf of Alaska. Offshore California is the busiest shipping region, followed by the Blake Plateau, the Gulf of Alaska and Hawaiian Islands, and subsea cables are densest in Offshore California, followed by Gulf of Alaska and Hawaiian Islands. The Gulf of Alaska has the largest reported fisheries landings. The sensitivities of biota and human uses to mining are highest for benthic or sessile species and infrastructure on or near ferromanganese crusts or manganese nodules that would be directly and physically altered through crust extraction or nodule removal. This study illustrates the usefulness of comprehensive, spatially explicit risk assessments to inform deep sea mining management and minimize ecological harm and human use conflicts. We assert that the relatively straightforward GIS-based methodology tested here can be applied and iterated upon elsewhere.

Formulation of Anchor and Chain Specifications for Establishing Subsea Cable Burial Depth

The penetration of ship anchor, which is a very important factor considered in the design stage of subsea cable burial, is highly dependent on the geometrical specifications and shapes of the anchor and chain. In order to facilitate predicting the anchor penetration depth by an arbitrary ship, formulations of the correlation between the ship mass and the existing anchor and chain specifications were attempted. In particular, for small ships with an equipment number of 40 (corresponding to DWT 90) or less, which were not covered by the existing classification data, a method for estimating the anchor mass, chain diameter, and mass per unit length was proposed.

Hydrodynamic Forces on a Near-Bottom Pipeline Subject to Wave-Induced Boundary Layer

Abstract Hydrodynamic forces on small diameter subsea pipelines and cables placed near seabed are important for their on-bottom stability design. In offshore environments, these pipelines are usually subjected to extreme wave conditions. The present study investigates hydrodynamic forces acting on a pipeline near a flat seabed subjected to a wave-induced boundary layer flow. The Keulegan–Carpenter numbers of the wave-induced boundary layer flow are 20, 140, and 200, defined based on the pipeline diameter (D), the maximum velocity of the undisturbed near-bed orbital velocity (Uw), and the period of the incoming oscillatory flow (Tw). Reynolds number is 1 × 104 based on Uw and D. A seabed roughness ratio ks/D (ks is the Nikuradse equivalent sand roughness) of up to 0.1 and different gap ratios of G/D = 0.05–0.5 between the pipeline and the seabed are considered. Numerical simulations have been carried out based on two-dimensional (2D) unsteady Reynolds-averaged Navier–Stokes equations combined with the k–ω shear stress transport turbulence model. A preliminary one-dimensional (1D) simulation is carried out to obtain a fully developed wave-induced boundary layer velocity profile, which is used as inlet flow for the 2D simulations. The numerical model is validated against the experimental data reported by Sumer et al. [1991, “Effect of a Plane Boundary on Oscillatory Flow Around a Circular Cylinder,” J. Fluid Mech., 225, pp. 271–300] at KC = 10. Influences of KC, ks/D, and G/D on the hydrodynamic forces and the surrounding flows are discussed in detail.

A Location-Allocation Model with Obstacle and Capacity Constraints for the Layout Optimization of a Subsea Transmission Network with Line-Shaped Conduction Structures

The idea of this paper comes from the need for a practical layout design for the subsea pipe line network and the power transmission network of offshore wind farms with subsea cables, which are both subsea transmission networks with line-shaped conduction structures. In this paper, this practical need is treated as an location-allocation problem, with the objective of minimizing the total cost, and a mixed-integer linear programming model (MILP) for layout optimization is developed. Through the model, the locations of service centers and theit corresponding sizes, the allocations between customers and service centers, as well as the transmission routes can all be figured out. This work makes two key contributions. First, facilities’ capacity restrictions and the avoidance of subsea obstacles are both integrated, making the description of the layout closer to practical situations. Secondly, a “global to local” search process based on the Delaunay triangulation method is constructed to solve the model, resulting in a high-quality solution. An offshore field layout design scenario is taken as a case study, through which the validity, feasibility, and stability of the proposed model, as well as the solution strategy, are presented. Furthermore, in the case study, the effect of the manifold number on the layout optimization is analyzed, indicating the flexibility of the model’s applications.

The offshore renewables industry may be better served by new bespoke design guidelines than by automatic adoption of recommended practices developed for oil and gas infrastructure: A recommendation illustrated by subsea cable design

IntroductionThere is an emerging need for the offshore renewable industry to have their own bespoke design guidelines because the associated projects and offshore facilities differ in fundamental ways to oil and gas facilities. Offshore renewable energy (ORE) facilities have already surpassed the numbers of installed facilities in the oil and gas industry by an order of magnitude and demand is forecast to continue growing exponentially. In addition ORE facilities often have different response characteristics and limit states or failure modes as well as profoundly different risk and consequence profiles given they are generally uncrewed and do not contain explosive hydrocarbon fluids which might be released into the environment. Therefore, the purpose of this paper is to advocate for licensing bodies and regulators (such as the various national PEL 114 committees) to challenge the process of automatic adoption of oil and gas design processes, while pushing for offshore renewables to be treated differently, when appropriate, with more relevant and applicable guidance.MethodsTo support this argument we present new bespoke design guidance developed for subsea cables based on specific modes of cable behaviour, which often differ from pipelines. We also show worked examples from recent project experience. The results from on-bottom stability analyses of a set of cables are compared between conventional oil and gas guidance following DNV-RP-F109 versus the stability using cable-optimised approaches.ResultsThe outcomes from the ‘conventional’ oil and gas results are not simply biased compared to cable-optimised design methods, with a trend of being either conservative or unconservative. Instead, the results of the two methods are very poorly correlated. This shows that the oil and gas approach isn't simply biased when applied to cables, but is instead unreliable because it doesn't capture the underlying failure conditions. These analytical comparisons are supported by field observation - the ocean doesn't lie, and makes short work of any anthropogenic structures which are designed with inadequate appreciation of the real world conditions.DiscussionTo support the rapid growth of ORE, we should therefore actively pursue opportunities to rewrite the design rules and standards, so that they better support the specific requirements of ORE infrastructure, rather than legacy oil and gas structures. With more appropriate design practices, we can accelerate the roll out of ORE to meet net zero, and mitigate the climate crisis.