Ensuring a sustainable future for offshore wind farm cables

One of the key requirements in the UK’s growth in renewable energy is the ability to successfully install electrical cabling in the marine environment. There has been an increased focus on the effect of cabling on the seabed most notably placement of cable protection within marine protected areas. The potential interaction between cabling activities (especially cable protection) and protected seabed habitats represents an increased consent risk to projects in the UK.

Greater clarity and understanding on cable installation techniques and tools, and how these could impact on the seabed, ensures that consenting advice from regulators and nature conservation bodies is informed by the best evidence available; reducing project consent risks.

Project statistics

21
Cable installation methods reviewed from 21 offshore wind farm projects
>1000km2
of export cables had their data collected
>70
cable monitoring reports reviewed

Solution

In 2017, the Crown Estate announced plans to lease new areas of seabed for offshore wind developments. As part of this leasing process, they commissioned RPS to undertake a study, published this month, to review current cable installation methods and protection measures, and habitat recovery. This project was driven by the increasing interest from stakeholders on the effects of cabling on the local marine environment and was undertaken to support the ‘Plan Level Habitats Regulations Assessment’ for the new leasing round.

As part of this project, our in-house environmental and engineering specialists collaborated with offshore wind developers to collate information on existing cable installation methods and tools used. Within the final report, we consider the effectiveness of these tools in a variety of seabed types and highlighting lessons learned from previous offshore wind development rounds.

The final report also presents a comprehensive review of available evidence on the impacts of offshore wind farm cabling on seabed sediments and associated biological communities. This draws on data collected from offshore wind monitoring, peer reviewed scientific literature, and our team’s experience with offshore cabling and analogous offshore industries.

The RPS study has identified an information gap on the effect of cable protection on the seabed and the report has made recommendations on how to address this gap through targeted monitoring and/or wider industry research. The study also makes recommendations on what information should be shared by developers with consenting and nature conservation authorities during future consent applications (including those associated with the latest leasing round) and during post consent engagement with stakeholders. These recommendations are particularly relevant for cabling activities within marine protected areas, where a greater level of scrutiny and evidence is expected by stakeholders.

By providing a deeper understanding of the factors influencing successful cable installation, particularly cable protection (including ground conditions), and the environmental impact of these activities, the published report will aid regulators and nature conservation bodies to make evidence-based decisions based on the best available information.

If you’d like more information on this subject, please contact Kevin via the contact details provided.

offshore wind cables marine to land

Key details

Project name
Review of cable installation, protection, mitigation and habitat recoverability

Client
Crown Estate

Location
UK

Completed in
2019

Services provided

  • Renewable energy
  • Stakeholder engagement
  • Environmental assessment
  • Consenting advice
  • Project management
  • Cable engineering review

The Crown Estate (TCE) commissioned RPS to undertake a desk study to collate information on offshore electrical cable installation techniques and seabed recovery, in support of the Plan Level Habitats Regulations Assessment (HRA) for Offshore Wind Leasing Round 4. The main driver for this study was a concern that there is a lack of collated information on cable installation techniques used to install power cables in the offshore marine environment. A concern has also been raised by stakeholders about the use of cable protection (e.g. placement of rock and mattressing). Stakeholders had further noted that there is a paucity of information on impacts on seabed habitats from cable installation and the recoverability of these habitats. This study was therefore divided into two broad sections:

   • Effectiveness of Cable Installation and Cable Protection; and
   • Environmental Impacts and Recovery.

As this study has been undertaken to inform the Plan Level HRA for the next round of offshore wind leasing, many of the conclusions will be relevant to future cabling projects within those Marine Protected Areas (MPAs) with seabed features which may be impacted by subsea cabling (particularly Special Areas of Conservation; SACs). The recommendations made within this report have therefore been developed for projects which involve cabling within SACs, although some could equally be applied to other areas where cabling is a particular concern (e.g. Marine Conservation Zones (MCZs)).

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