Annex IV distributes metadata forms (questionnaires) to solicit information from researchers around the world who are exploring the environmental effects of marine renewable energy. This page provides a description and contact information related to the research. Content is updated on an annual basis.

Collaborative Offshore Wind Research into the Environment Electromagnetic Field (COWRIE EMF) Research

Research Study Annex IV

Title: Collaborative Offshore Wind Research into the Environment Electromagnetic Field (COWRIE EMF) Research
Start Date:
January 01, 2003
Research End Date:
December 31, 2009
Country:
Stressor:
Info Updated:
December 04, 2014
Study Status: 
Completed
Princple Investigator Contact Information: 

Name: Andrew Gill

Email: a.b.gill@cranfield.ac.uk

Project Description: 

COWRIE (Collaborative Offshore Wind Research into the Environment) was set up by The Crown Estate as an independent body to carry out research into the impact of offshore wind farm development on the environment and wildlife, evolving into a charity which has gained global recognition for its scientific and educational work.  A priority research issue identified by COWRIE was the possible effects of electromagnetic fields (EMF) generated by offshore windfarm power cables on organisms that are sensitive to these fields.  As a result a consortium, led by Centre for Marine and Coastal Studies (CMACS), was contracted to carry out a Stage 1 investigation into the physical aspect of emitted EMFs.  Phase 2 followed the development of this baseline and resulted in two reports.  The COWRIE 1.5 review was published in 2005, conducted jointly by CMACS and Cranfield University.  This review considered the potential effects of EMFs generated by sub-sea power cables associated with offshore wind farm developments on electrically and magnetically sensitive marine organisms.  The following project, COWRIE 2.0 which was published in 2009, set out to determine if electromagnetic sensitive fish species are affected by anthropogenic EMFs.

Funding Source: 

COWRIE, NERC and Fisheries Society of the British Isles.

Location of Research: 

UK

Project Aims: 

Phase 1: Baseline

Investigate:

  • The likely EMF emitted from a sub-sea power cable;
  • A suggested method to measure EMF in the field, which could be applied by windfarm developers or in future projects;
  • Guidance on mitigation measures to reduce EMFs; and
  • Consideration of the results for the next stage of investigation into the effects of EMFs on electro-sensitive species.

 

Phase 1: COWRIE 1.5, Electromagnetic Fields Review

The aim of the review was to allow COWRIE to prioritise Phase 2 research relating to EMFs associated with offshore wind farms and EM-sensitive species.

 

Phase 2: COWRIE 2.0, Electromagnetic Fields (EMF)

To answer the primary research question:

  • Do electromagnetically (EM) sensitive organisms respond to anthropogenic EMFs of the type and magnitude generated by offshore wind farms?
Project Progress: 

All reports have been completed and published.

Key Findings: 

Note that these are the summarised findings of each publication.  For more detail consult the ‘Publications’ section

 

Phase 1: Baseline:

Modelling based on EMFs generated by a 132kV XLPE (cross-linked polyethylene) three phase submarine cable designed by Pirelli for a cable modelled with perfect shielding showed that:

  • The cable did not directly generate an E-field outside the cable.
  • B-fields generated by the cable created 'induced' E-fields outside the cable, irrespective of shielding.
  • Maxwell's Eddy Current Field Solver model showed that B-fields are present in close proximity to the cable and that the sediment type in which a cable is buried has no effect on the magnitude of B-field generated.
  • The magnitude of the B-field on the ‘skin’ of the cable (i.e. within millimetres) is approximately 1.6μT which will be superimposed on any other B-fields (eg. earth’s geomagnetic field).
  • The magnitude of the B-field associated with the cable falls to background levels within 20m.

For a cable modelled with non-perfect shielding/earthing:

  • An E-field is generated outside the cable.
  • This additional E-field is smaller than the normal induced E-field and decreases with the distance from the cable.

To directly measure the electromagnetic emissions from undersea cables two sensors were developed to detect electric and magnetic fields.

 

In terms of the potential significance of the modelled results to electro-sensitive fish the following conclusions were made:

  • The model resulted in a predicted E-field of approximately 91μV/m (=0.9 μV/cm) at the seabed adjacent to a cable buried to 1m.  This level of E-field is on the boundary of E-field emissions that are expected to attract and those that repel elasmobranchs.
  • The induced E-fields calculated from the B-fields measured in-situ were also within the lower range of detection by elasmobranchs.
  • The options for mitigation using either changes in permeability or conductivity indicate that the induced E-fields can be effectively reduced, however, unless very high permeability materials are used in the cable these E-fields are still within the lower range of detection of elasmobranchs. Hence any reduction in E-field emission would minimise the potential for an avoidance reaction by a fish if it encountered the field but may still result in an attraction response.
  • Another important consideration is the relationship between the amount of cable, either buried or on the seabed surface, producing induced E-fields and the available habitat of electro-sensitive species.
  • There is also a need to determine if the power cable operating frequency (50Hz) and associated sub harmonic frequencies have any effect on the EMFs that are detectable by UK elasmobranchs.

Phase 1: COWRIE 1.5, Electromagnetic Fields Review

  • There are many electro-sensitive fish which are potentially capable of responding to anthropogenic sources of E field. However, it is not known whether the interaction between the fish and the artificial E field will result in a response or have any consequences for the fish.
  • Whilst the information available on magnetic fields is limited, it does suggest that potential interactions between B field emissions, of the order likely to be associated with wind farm cables, and coastal organisms could occur from the cellular through to the behavioural level.

Phase 2: COWRIE 2.0, Electromagnetic Fields (EMF)

  • Overall, the COWRIE 2.0 EMF mesocosm study and wind farm surveys have provided evidence that the benthic, elasmobranch species studied can respond to the presence of EMF that is of the type and intensity associated with sub-sea cables.
  • The response is not predictable and appears to be species specific and perhaps individual specific, meaning that some species and their individuals are more likely to respond by focussing movement within the zone of EMF.
  • Furthermore, the field measuring of EMF at offshore wind farms sites showed that there are both magnetic and electric field emissions associated with the main feeder cables to shore and these EMFs are comparable, and in some cases, greater than the EMF produced in the experimental mesocosm study.

The zone of EMF that is potentially within the range of detection of the elasmobranchs spans several hundred metres. The project has met its objective by demonstrating that some electro-sensitive elasmobranchs will respond to the EMF emitted in terms of both the overall spatial distribution of one of the species tested and at the finer scale level of individual fish of different species.

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