Abstract
The COWRIE 1.5 Electromagnetic Fields Review specifically considers the potential effects of electromagnetic fields generated by sub-sea power cables associated with offshore wind farm developments on electrically and magnetically sensitive marine organisms. The review was conducted jointly by the Centre for Marine and Coastal Studies Ltd (CMACS) and Institute of Water and Environment, Cranfield University at Silsoe (CU@S). Additional input came from ECONNECT Ltd and the Centre for Intelligent Monitoring Systems (CIMS), University of Liverpool.
Throughout the course of the project there was some confusion about the term electromagnetic field and its present acronym, EMF, which has led to inconsistencies and mistakes in documentation and discussion. Here we suggest a set of unambiguous labels based on standard electrical nomenclature relating to the different components of an electromagnetic field (EMF) field for clarity in any future publication or communication.
The results of the COWRIE Phase 1 work demonstrated that the EMF emitted by industry standard AC offshore cables had a magnetic (B) field component and an induced electric (iE) field component. These EMF components were assessed as being within the range of detection by EM-sensitive aquatic species but whether any potential impact would result remained unknown. It was noted however that a number of monitoring studies for existing wind farms were underway and that these may assist in the determination of potential impact in the future. In addition, during 2003 further consents for development were issued for three strategic areas of the English/Welsh/Scottish coastal zone.
In light of the monitoring studies and the new plans for development, the report presented here provides a comprehensive review and analysis of all information currently available. The aim of the review was to allow COWRIE to prioritize Phase 2 research relating to EMFs associated with offshore wind farms and EM-sensitive species.
The review focused first on collation of up to date information on the biology of EM-sensitive species and the information from the offshore wind farm industry via published material and consultation. In addition, information from the first international conference dedicated to assessing the environmental impact of offshore wind farms was incorporated. The information collation phase provided the material for the subject specific literature reviews presented in the report and these were used as the basis for a set of specific recommendations that are presented for future COWRIE research relating to EMFs.
A review of material on electrosensitive species showed that there are many fish species within the UK waters 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 have any consequences for the fish.
The information available on magnetosensitive species is limited, however it does suggest that potential interactions between EM emissions, of the order likely to be associated with wind farm cables, and a number of UK coastal organisms could occur from the cellular through to the behavioral level.
The consultation and review of industry information showed that EM-sensitive species are present at a number of development sites however the present opinion is that whilst there could be an interaction between these species and the sub-sea cables used the result would not be of any significance. It was evident that the industry does try to take into consideration the environmental interaction of EMFs but it is hampered by a serious lack of information and understanding. Recent advances in modelling of cables confirm that EMFs are emitted but the intensity of emissions is location, cable and operation specific.
The offshore wind farm industry is a new and rapidly developing sector and needs to use very large amounts of electrical cabling. There are, however, other anthropogenic sources of electric and magnetic fields that have been present in the marine environment for many years. Whilst the existing E and B field sources (eg. offshore cables and pipelines) are more limited in their spatial extent they do have varying potential to produce electric and/or magnetic fields of comparable magnitude to those associated with the offshore wind farms.
It is clear from the review of industry based material that the issue of electromagnetic (both B and iE field) effects on electrically and magnetically sensitive species has not been addressed in a consistent manner and that there are a number of important misconceptions. The main reason for this is the lack of clear scientific guidance on the significance of effects on receptor species (if any).
Therefore for both B and E/iE fields associated with offshore wind farms we need to:
- Identify the species most likely to interact with the EMFs. This will vary between species according to their habits, conservation status and needs to consider different life stages
- Definitively determine whether these species will be affected
- Assess the potential significance of any effects
- Specifically consider the significance of larger (Round 2) offshore wind farm developments
- Specifically consider cumulative impacts of adjacent developments, not just wind farms.
For all the UK coastal species that are EM-sensitive it is evident that our knowledge of their interaction with anthropogenic EMFs is limited. In order to improve understanding and assist the offshore wind farm industry and regulators in appropriate management of EMFs in the environment we present a prioritised list of species that are most likely to interact with offshore wind farm generated EMFs. Species chosen are benthic species and those with specific life history stages that utilise inshore waters.
Owing to the lack of knowledge relating to EMF emissions and their environmental impact and the rapid pace of development of offshore wind farms it is evident that a fuller understanding of this subject area is urgently required. We envisage a two-stage research programme, with the first stage focusing on:
- A one-off mesocosm study involving the enclosure of a suitable area of seabed within which to study the response of a benthic EM-sensitive test species (e.g. an elasmobranch) to experimentally controlled B fields and induced electrical fields from a sub-sea cable.
- Monitoring of electrically and magnetically sensitive species at individual wind farms, probably under FEPA conditions, as appropriate to site-specific conditions.
Within the first stage, study 1 aims to definitively determine if there is a response by an electromagnetic sensitive species to the EMF associated with an industry standard offshore wind farm electricity cable. We consider such a study to be the priority for the COWRIE Phase 2 study.
If the mesocosm study and/or the monitoring provide data to conclude that there are effects of EMFs on receptor species then stage 2 should be implemented. Stage 2 should address the following specific studies:
- A collaborative study to monitor elasmobranch responses to submarine power cable emissions at one or more UK offshore wind farm sites.
- Collaborative study/studies to follow up potential impacts on magnetically sensitive species and/or non-elasmobranch electrically sensitive species at UK offshore wind farm sites.
- Specific research to investigate electric and magnetic field significance for UK fish species in controlled environments and in situ.
The environmental monitoring requirements for consented offshore wind farms are determined by FEPA licence conditions. The FEPA licence generally states the broad principals of monitoring but leaves the details of that monitoring open for discussions between the developer (and their scientific consultants) and statutory bodies. To assist in this process we have considered monitoring that would be appropriate to individual wind farms in light of the review undertaken. We then have endeavoured to suggest monitoring that would be suitable both for consented wind farms, should further monitoring be invoked, and for planned wind farms should future FEPA licence conditions specify such monitoring outright. We have included an overview of possible survey methods for electrically and magnetically sensitive species including advantages and disadvantages. Finally, we offer guidance for studies which seek to monitor fish at offshore wind farm sites in relation to E and B fields.