East Anglia ONE
EMF Assessment
1. Introduction
Having been awarded a licence by the Crown Estate to develop a total of approximately 7,200MW of wind capacity under the Round 3 Offshore Wind Licensing Arrangements, Scottish Power Renewables (SPR) and Vattenfall Wind Power Limited (VWP) have formed a joint venture, East Anglia Offshore Wind Ltd (EAOW), to develop the East Anglia zone with six 1,200MW projects. The first of these projects will be the East Anglia ONE Offshore Wind Farm (EAONE).
Centre for Marine and Coastal Studies Ltd (CMACS) has been contracted by EAOW to provide advice on the likely environmental impacts of magnetic and electric fields generated by the subsea cable network associated with the proposed EAONE wind farm upon marine fauna. This work forms part of a wider Environmental Impact Assessment.
Anthropogenic (i.e. human produced) magnetic and electric fields are of interest in the marine environment since a relatively large number of marine species are sensitive to magnetic and/or electric fields and adapted to utilise naturally occurring fields as environmental cues. If artificial fields are present and detected by marine organisms there is potential for environmental effects.
Research into possible interactions between marine fauna and anthropogenic electromagnetic fields (EMF) is at an early stage and uncertainties remain. Hence, there are no specific limits imposed on subtidal EMF generation from a marine biological perspective (in contrast to emissions in the terrestrial environment). However, fields of the magnitude anticipated from submarine power cabling have been both modelled and, in limited situations, measured. They have also been demonstrated by experimental studies to lie within the sensitivity ranges of a variety of marine organisms (CMACS 2003; Gill et al 2009). In view of this overlap, and given the burgeoning UK offshore renewable energy industry and the related expansion in offshore grid connections, there is concern that potential effects should be considered (Gill 2005; Gill & Kimber 2005; Ohman et al 2007; Sutherland et al 2008); especially bearing in mind that many electromagnetically sensitive species are also commercially exploited (e.g. salmon, thornback rays), with some having suffered severe population declines in recent decades (e.g. skates and rays: Baum et al 2003; Myers & Worm 2003). Accordingly, regulators, key consultees and statutory advisers are keen to ensure EMF is considered, as far as possible, during the planning, construction and operation phases of offshore grid connection projects and offshore renewable energy developments.
To date, the majority of assessments of EMF generation in the marine environment have concerned 50 Hz alternating current (AC) cables used extensively in the relatively small, inshore, Round 1 wind farms. These assessments largely drew upon industry research supported by the Collaborative Offshore Wind Research into the Environment (COWRIE) charity. As demand upon the UK transmission network and associated supporting infrastructure increases, and as offshore wind farms become larger and are installed further offshore (Rounds 2 & 3), high voltage direct current (HVDC) cables are increasingly being proposed, especially given recent
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