Precision and Reliability in Subsea Cable Location

Offshore wind farms are at the forefront of the energy transition, playing a crucial role in the shift towards renewable energy sources. In Germany alone, there are ambitious plans to install at least 30 gigawatts’ (GW) worth of offshore wind energy by 2030. However, the process of transporting the electricity generated by these offshore wind farms from the North Sea and Baltic Sea to the mainland is a complex task that requires sophisticated infrastructure.

One of the key components in this process is the installation of undersea cables that connect the offshore wind farms to the onshore grid. Countries like Germany have stringent regulations in place for the installation of these undersea cables, with operators having to adhere to strict requirements during the planning and implementation stages. For instance, a post-burial survey (PBS) is typically conducted to ensure that the actual position of a cable matches the planned route, aiming to protect existing infrastructures and prevent potential damage from future construction activities.

As offshore wind farms and other offshore infrastructure projects continue to expand, the issue of cables crossing over one another is becoming more prevalent. Moreover, factors such as bottom currents and sediment movements can lead to the shifting positions of cables buried under the seabed over time. To address these challenges, it is essential to map the locations of cables before new infrastructures are installed or maintenance work is carried out.

Traditionally, acoustic or magnetic methods have been used for cable detection, but these methods are costly and may have reliability issues. This limitation means that existing systems cannot efficiently survey cables over large areas or may require the electricity to be switched off during the survey process. To overcome these challenges, the SASACD project (Seismo-Acoustic Synthetic Aperture Cable Detection) has been initiated, bringing together Fraunhofer IWES, the University of Bremen, and TenneT Offshore GmbH.

The innovative seismo-acoustic imaging method developed in the SASACD project enables precise location of offshore cables in the top layers of seabed sediment. This breakthrough technology not only enhances the efficiency of maintenance planning but also contributes to the overall reliability and cost-effectiveness of operating offshore wind farms. With Fraunhofer IWES leading the coordination of the project and receiving funding from the German Federal Ministry for Economic Affairs and Climate Action (BMWK), the future of offshore wind farm cable detection looks promising.