Review of Cabling Techniques and Environmental Effects Applicable
Review of Cabling Techniques and Environmental Effects Applicable
Review of Cabling Techniques and Environmental Effects Applicable
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<strong>Review</strong> <strong>of</strong> <strong>Cabling</strong> <strong>Techniques</strong> <strong>and</strong> <strong>Environmental</strong> <strong>Effects</strong> <strong>Applicable</strong> to the Offshore Wind<br />
Farm Industry – Technical Report<br />
It is currently unknown which invertebrate species could be affected but<br />
magnetic sensitivity has been demonstrated for the following: Decapoda<br />
(Crangon crangon), Isopoda (Idotea baltica) <strong>and</strong> Amphipoda (Talorchestia<br />
martensii <strong>and</strong> Talitrus saltator) (Greater Gabbard Offshore Winds Ltd., 2005). In<br />
all cases, magnetic sensitivity is understood to be associated with orientation<br />
<strong>and</strong> direction finding ability such that the animal may become disorientated;<br />
depending on the magnitude <strong>and</strong> persistence <strong>of</strong> the confounding magnetic field<br />
the impact could be a trivial temporary change in swimming direction or a more<br />
serious impact on migration (Greater Gabbard Offshore Winds Ltd., 2005).<br />
Although there has been no targeted monitoring specifically to investigate<br />
whether distributions <strong>of</strong> crustaceans <strong>and</strong> molluscs have been affected by the<br />
presence <strong>of</strong> submarine power cables <strong>and</strong> associated magnetic fields, monitoring<br />
to meet other specific objectives relating to <strong>of</strong>fshore wind farms has not revealed<br />
any evidence to show such an effect. There are therefore uncertainties regarding<br />
the significance <strong>of</strong> this potential impact. However, it is not expected that the<br />
impact would be <strong>of</strong> significance, since the species that could be affected are<br />
known to be mobile <strong>and</strong>, as such, are able to avoid impacted areas. Generally<br />
the habitats that they inhabit are widespread <strong>and</strong> the effects <strong>of</strong> magnetic fields<br />
are usually highly localised around the cable.<br />
Potential heating effects<br />
The effect <strong>of</strong> radiated heat from cables buried in the seabed has been considered<br />
by the Connecticut Siting Council (CSC, 2001) as part <strong>of</strong> the ‘Cross Sound Cable<br />
Interconnector’ project, a high voltage DC buried cable system between New<br />
Engl<strong>and</strong> <strong>and</strong> Long Isl<strong>and</strong> New York. The CSC estimated a rise in temperature<br />
at the seabed immediately above the buried cable <strong>of</strong> 0.19 o C <strong>and</strong> an associated<br />
increase in seawater temperature <strong>of</strong> 0.000006 o C.<br />
The potential rise in temperature is therefore considered to be impossible to<br />
detect against natural fluctuations in the surrounding sediments.<br />
Cable coating effects<br />
The leaching <strong>of</strong> chemicals <strong>and</strong> substances from cable coatings <strong>and</strong> cable<br />
sheaths are likely to have a minimal impact on the surrounding environment.<br />
Burial <strong>of</strong> the cable will further reduce possible environmental effects. Research<br />
conducted on the environmental impact <strong>of</strong> a submarine cable used to transmit<br />
hydrophonic data to shore from an acoustic hydrophone array in Monterey<br />
Bay, California reported no apparent effect on infaunal abundance (Kogan et<br />
al., 2003). Where the cable had become exposed, colonisation had occurred by<br />
encrusting species such as anemones, echinoderms <strong>and</strong> sponges (Figure 5.1),<br />
with fish congregating near the cable in places.<br />
At present, no specific regulations or st<strong>and</strong>ards exist for submarine cable<br />
coatings with respect to environment impacts arising from their constituents<br />
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