Integrated Investigation of Biofouling Impact on Dynamic Subsea Cables and Characterization of Dynamic Cable Motion for Floating Wind Systems

Project Description:

The incorporation of renewable energy sources into the UK’s energy mix has sparked a significant investigation into offshore solutions. The vast wind resources and limited land restrictions present favourable prospects for sustainable electricity generation. Within the realm of offshore technologies, dynamic subsea cables and floating wind systems are crucial components that facilitate power transmission and provide structural support for turbines. Nevertheless, both encounter unique obstacles that can greatly affect their form, fitness and function.

As per the research conducted by Maduka, et al. (2022), Maksassi, et al. (2022), and Salimi (2023), one of the significant challenges faced by the dynamic submarine cable is the widespread impact of biofouling. This phenomenon refers to the buildup of microorganisms and marine organisms on surfaces submerged underwater. Biofouling can result in higher resistance (drag), changes in hydrodynamic properties, and corrosion, which can undermine the effectiveness and dependability of underwater cables (Hussien, 2023). Furthermore, according to the research conducted by Vinagre, et al. (2020) and Gorostidi, et al. (2022), the accumulation of biofouling on the dynamic cables not only increases the expenses associated with maintenance but also heightens the risk of cable failure. This highlights a notable obstacle in the long-term viability and effectiveness of floating wind farms. Bakhtiari, et al. (2020) and Liu, et al. (2024) proposed a similar idea, suggesting that the accumulation of weight and surface roughness caused by biofouling can reduce the flexibility of dynamic cables and hinder their ability to withstand fatigue. Constraints of fatigue resistance may result in a reduction in the cable’s longevity. Another result of the author’s research revealed that certain substances (foulants) can adhere to the cable and become minor drifters, leading to occasional vortex-induced vibration (VIV).

In addition, the consequences of biofouling go beyond causing structural fatigue and impacting the heat transfer capabilities of the cables. This highlights the importance of implementing comprehensive management strategies (Maksassi,2022).

Cable motion dynamics becomes vital as the renewable energy business grows offshore with floating wind installations. FOWTs’  structure is subject to complex tides, waves, and winds, unlike fixed-foundation wind farms (Formosa and Sant, 2022). Due to its design, the floater requires a flexible mooring system.

Gan (2023) posited that the excursion motion on a spar or semi-submersible floaters can reach up to 10 metres. This means power-transmitting undersea cables must be flexible enough to tolerate floater movement. comprehending the cable motion is a highly intricate endeavour due to the multifaceted influence of wave and tidal forces, as well as its complex interaction with both the continuously moving six-degree-of-freedom floater structure and the environment. One solution to aid the cables’ ability to withstand the movement according to Gan (2023) is installing lazy wave buoyancy modules midway along the cable. That said, tidal currents and floater activity bend and twist these cables, causing mechanical damage in different portions depending on the mounting type and induced motion (Formosa, 2021) and (Gan, 2023).

Gaining a comprehensive understanding of the intricate connection between these challenges necessitates a meticulous examination to fully comprehend the impact of biofouling on subsea cables and characterize the dynamics of the cables’ motion in floating wind systems. By linking these fields of study, this research is expected to produce holistic strategies to enhance offshore renewable energy systems’ effectiveness, reliability, and performance. Through experimental studies, numerical simulations and field observations, the research aims to elucidate the harsh environmental conditions prevailing in distant offshore regions.

Presently, there is limited understanding of the contribution of marine growth to vortex-induced vibrations in submarine cables or general cable dynamic behaviour due to this phenomenon, Kurian, et al. (2017).

In addition, Zhang, et al. (2023) argue that the current landscape lacks a dedicated industry standard tailored for FOWTs or any functional model that can furnish the sector with insights into the intricate behaviour of dynamic cables. Therefore, the development of a high-accuracy model to predict the cable motion and curvatures, specific to FOWT and for a variety of hydrodynamic and environmental loadings, becomes imperative to inform applications like cable ancillary hardware designs.

By fostering a deeper understanding of biofouling impacts and dynamic cable motion, this integrated investigation seeks to inform the development of targeted mitigation strategies, advanced materials, and optimized designs for offshore renewable energy infrastructure. Ultimately, the research endeavours to contribute to the advancement of sustainable energy solutions and the realization of a cleaner, greener future.

Objectives

• Quantify biofouling effects on dynamic cables
• Examine the risk and economic implications of biofouling effects on subsea dynamic cables.
• Assess dynamic cable motion
• How biofouling changes the cross-sectional shape of cables and their VIV as well as motion characteristics.
• Develop numerical models and simulations to assess cable fatigue life and reliability considering dynamic loading conditions, material properties, and environmental factors.
• Identify biofouling mitigation strategies.