Case Study

Electromagnetic Fields (EMFs) from subsea power cables in the natural marine environment

It is now recognised that interactions between natural and anthropogenic sources of electric and magnetic fields (EMFs), such as those produced by the currents in subsea power cables (as used for electricity transmission associated with offshore wind or interconnectors) may have effects on marine species. Therefore, EMFs are sometimes considered an environmental risk for marine species, however, there is a lot of uncertainty about the EMFs associated with subsea power cables and how they interact with the marine environment and species. This uncertainty can lead to questions by stakeholders or at the public consultation phase for offshore wind or subsea power cable plans and therefore delay the consenting process. There is evidently a need to set out the current consensus on EMFs associated with subsea power cables and how to both model and measure them in the marine environment, to facilitate proper consideration of the potential impact in environmental assessments.

To advance the understanding of anthropogenic EMFs from subsea power cables, an interdisciplinary expert workshop was facilitated by Cefas and the Scottish Government at the Royal institution, London on 17 and 18 January 2023. This was part of a project funded by the Offshore Wind Evidence and Change (OWEC) programme, led by The Crown Estate in partnership with the Department for Energy Security and Net Zero and Department for Environment, Food & Rural Affairs. Fifteen interdisciplinary participants from England, Scotland, Sweden, Belgium and the USA attended the workshop.  

A technical report was published following the workshop, which provides the consensus from an EMF expert technical group, on how best to determine EMFs in the marine environment. This report is a key resource for stakeholders seeking to understand species interactions with EMFs and their potential effects, and for environmental assessments as part of planning and consenting offshore wind.