Part 2 – EMF Cable issues on Marine Life 

Under Construction – these references to be further reviewed

Electrical cables, especially export cables, are a key issue of offshore wind farms and have attracted a huge research and development focus. Further research activities have generally been recommended – especially by cross-disciplinary teams

4 challenges to overcome when transmitting offshore wind power – “Procuring, routing, and protecting offshore wind cables is essential to getting the power to the grid. So is environmental stewardship.

  • Supply chain constraints for the manufacturing of export cables – procurement is taking longer
  • Routing the export cables to an onshore point of interconnection
  • Protecting the export cables – According to reports from insurers, approximately three-quarters of all offshore wind insurance claims are related to cables. And 88% of those cable-insurance claims are related to the export cables, which transport the power to shore. Cable failures are costly to repair. It is not only the cost of the cables but also the lost revenue from the outage. According CIGRE Technical Brochure 815, it takes more than three months to get a system back online after a cable failure. 
  • Minimizing the environmental impact of installed cables – The primary environmental concerns with offshore wind transmission are the impact to the seafloor, sensitive coastal environments, and other marine life. There is also concern with potential conflict with other ocean uses.

Further information to be reviewed

  • Effects of EMFs from Undersea Power Cables on Elasmobranchs and Other Marine Species – Anthropogenic electromagnetic fields (EMFs) have been introduced into the marine environmentaround the world and from a wide variety of sources for well over a century. Despite this, littleis known about potential ecological impacts from EMFs. 

  • Effects of EMF emissions from undersea electric cables on coral reef fish –  “AC power transmission cables are the industry standard for offshore renewable energy facilitiesin Europe and those proposed in the US (to date, mostly wind power). DC cables will likely be used more often for future projects that are sited farther from shore. Except for the unlikely proposition of a DC cable system using sea electrodes (or for unshielded cables), it is common practice to block the direct electric field from the external environment by using conductive sheathing. Thus, the EMFs and DC power cables emitted into the marine environment are the magnetic field and the resultant induced electric field … Many fundamental questions about sensory system mechanisms and life functions supported by these senses have not been resolved. Just a small fraction of marine species have been directly studied for magnetic or electric senses. Even for studied species, work has often focused on a particular life history stage, such that sensory capabilities for certain stages (e.g., larval fish and invertebrates) are unknown. Research has also focused on natural behaviors and interactions,and studies that evaluate response to EMFs from power cables are almost entirely absent from the literature. … The intensity of modeled magnetic fields around DC cables is higher than fields around AC cables of similar voltages, and magnetosensitive organisms are likely equipped to detect low intensity (<10 nT [<0.01 µT]) DC magnetic fields, well below the levels predicted for the cables examined (Figure ES-2). The question has arisen as to whether the alteration in the magnetic field around a DC cable may interfere with orientation or navigation by magnetoreceptive species. DC electric fields are also generated by the flow of charged ions (e.g., seawater, amoving organism) moving through a DC magnetic field. Electrosensitive fish are highly sensitive to DC electric field gradients as low as 5 nV/cm as they swim through them. The bioelectric fields that are produced by living organisms are primarily DC fields produced by ion gradients within the organism (although AC fields are also generated). Although induced electric fields from undersea cables may not directly mimic bioelectric prey, conspecifics, or predators, these resultant fields may affect the behavior of electrosensitive species…. there are several engineering solutions that can be considered to reduce EMF emissions. As some of these simultaneously provide protection for the cable, incorporation into the project design can be done without significant additional cost implications, often an impediment to achieving developer buy-in for mitigation. Design considerations include current flow, cable configuration, and sheath/armoring characteristics. Cable design and voltage are the factors that are likely to have the greatest effect on magnetic field generation. AC cables appear to generate lower magnetic field strengths than DC cables for about the same voltage. Higher voltage cables produce lower magnetic fields than lower voltage cables for the same power delivered. Magnetic fields from can be minimized by placing the cables close together allowing the field vectors from each cable to cancel each other out. Sheathing the cable and increasing the conductivity and permeability of the sheaths also reduce the magnetic field.“

  • 2002 – The potential effects of electromagnetic fields generated by cabling between offshore wind turbines upon elasmobranch fishes – “Sharks, skates and rays (subclass Elasmobranchii) have long been known to exploit the electric outputs of organisms in
    saltwater, to detect and capture their prey. Therefore, there exists the potential for electrosensitive species to detect and respond to the electromagnetic fields produced

    by offshore power installations … There is a dearth of objective and definitive published information relating to the question of whether electric fields produced by underwater cables have any effect on electrosensitive species.The pilot experimental research demonstrated that there is a differential effect in terms of the behavioural response of dogfish to simulated electric fields emitted by prey and those from undersea power cables.These results, however, should be interpreted from two perspectives in an unbiased and balanced manner. Firstly, in light of the present and future importance placed on renewable energy resources we need to be confident that associated human activity will not be significantly detrimental to a component of the coastal marine ecosystem not previously considered ie. the elasmobranchs. Secondly, we need to be conscious of the real need for alternative energy resources and not use the effects predicted from controlled laboratory investigations to take precedence or unnecessarily influence the prioritisation of renewable energy resource utilisation. To address these future information requirements there are three areas of work to focus on based on the findings of the present study:•  Further directed biological research, concentrating on species use of the inshore habitats and behavioural responses to electric fields
    .• Electric field research, in particular the quantification of fields within different substrata and insitu measurement .
    • GIS mapping and interrogation, to provide a database, which can guide decisions \ on the location of offshore windpower sites taking into account potential conflicts with elasmobranchs… it is considered that the flora and fauna at the Vindeby site has increased in diversity since the construction of the wind farm. Despite this evidence, it is still a possibility that the benthic communities that colonise the foundations may not be native to the area of the wind farm, and so, may have an impact on the ecosystem. However, due to the ban on commercial fishing around the site of the wind farm, there will be no impact on the benthos from trawling, so fish stocks may increase… Definitive longer term studies (at least 3-5 years) are required to ascertain the relevance of avoidance behaviour by elasmobranchs from an ecological perspective ie certain individuals are affected does this reduce/increase their likelihood of survival, gaining resources and/or reproduction and potential recruitment. These are inevitable questions that arise from these types of   investigations but they should remain the central focus of studies into the ‘effects of wind power derived electricity’
    .• Shorter term species specific studies to determine the potential degree

    of response of the Irish Sea species to electric fields produced by underwater cables. This may also include other species if the study is to be geographically extended. Temperature dependent studies to investigate how electroreceptive fish respond to electric fields under different temperature regimes. Temperature also has an influence on the extent to which electric fields dissipate in water hence these studies can address two important variables in the overall project.
    • Season dependent studies will be required owing to differential ecological requirements of species individuals, which are likely to be more or less sensitive to the predicted electric fields.• Habitat use by the different species at different life stages. These studies would consider whether species are likely to be attracted to a particular geographic location at any point in the lifecycle or at specific times of the day/year. These data would be a crucial aspect within the process of site location and cable laying routes and operations, as these may have to be reconsidered or timed appropriately. In addition, there is potential that there will be differential sensitivity with ontogenetic stage particularly in shallow nursery areas where the electric cables are likely to cross or be buried. Important note: laboratory based studies will require animal welfare licensing approval
    4 2 Electric Field Projects
    Through the present project it has become apparent that the greater use of
    undersea cables and the proposed increase in offshore structures associated with energy transmission has taken into consideration the potential effects on electrosensitive species. Many of the topics that need to be considered (such as effects on different species, temperature effects, depth effects, substratum effects, cabling combinations etc.) require the input of marine electrical engineers. The physics and mathematics involved with electromagnetic fields in the aquatic environment are central to our understanding hence there needs to be a significant component of the analyses of any effects of these fields to be discussed and considered by appropriately qualified personnel who are sympathetic to environmental considerations. Hence, a bi-disciplinary study is required to significantly promote the project bringing a marine biologist and marine electrical engineer into close collaboration to address the specific objectives.A major potential exists for projects to continue the development
    of methods for predicting and directly measuring the electromagnetic fields within the experimental tanks and also in situ.  A project of this nature can investigate the variability of field strength in relation to such factors as temperature and substratum, which would provide a close link with the biological projects.In addition, there is
    a requirement to further investigate how power generated offshore is transmitted through underwater cables, for example:
    • What are the maximum and minimum currents required to pass through the cables and is there a peak at a particular time of day?
    • of maxima and minima occur can the timing of electricity transmission be partitioned to reduce the likely effects owing to differences in time of year and/or diurnal variation in response of electrosensitive organisms?• What is the potential for storage facilities or staging posts to regulate the transmission of the electricity?• Which cable configurations are the best to minimise the potential effect of
    the electric fields generated and also maximise efficiency of power transmission?• What types of substratum are the best to reduce the electric field effect inrelation
    to the practicalities of actual burial? This aspect is also important inrelation to species habitat preferences and the potential conflict of preferred burial substratum.
    • Are magnetic fields a potential confounding influence on the electric fieldsemitted
    by undersea cables and therefore the response of  ?
  • 2018 – A review of potential impacts of submarine power cables on the marine environment: Knowledge gaps,recommendations and future directions – 
    Many marine species around the world are known to be sensitive to electromagnetic fields,  including elasmobranchs (rays and sharks), fishes, mammals, turtles, molluscs and crustaceans. Indeed, the majority of these taxa detect and utilize Earth’s geomagnetic field  for orientation and migration, Some are electrosensitive, like elasmobranchs, which are able to detect E-fields and iE-fields through specific organs called ampullae of Lorenzini [89,90]. This electrosense can be used to detect electric fields emitted by prey, conspecifics or potential predators, as well as for orientation A few incidents of bites observed on unburied SPC may also be linked to the electric field emitted by cables … Thus, SPC can possibly interact in a negative way with sensitive marine species, especially benthic and demersal organisms through:
    • effects on predator/prey interactions,
    • avoidance/attraction and other behavioural effects,
    • effects on species navigation/orientation capabilities,
    • and physiological and developmental effects.
    Elasmobranchs can detect very low electric fields( starting from 0.005 μV cm
    -1 ), and magnetic (20  ─  75 µT . Power cables inducing a strong electric field can repel many elasmobranch species, preventing some movement between important areas (such as feeding, mating and nursery areas). As part of the COWRIE (Collaborative Offshore Wind energy Research Into the Environment) project, Gill
    et al. reported that elasmobranchs are attracted by electric fields generated by DC between 0.005 and 1 µV cm -1 and repelled by electric fields of approximately 10 µV cm -1 and higher.  However, a recent experimental study performed by Hutchison
    et al.  highlights a subtle change in the behavioural activity of the American lobster (
     Homarus americanus) when exposed to EMF from a HVDC cable. Another noteworthy issue is that substantial data gaps exist between the interaction of pelagic species (like pelagic shark, marine mammals or fishes) and dynamic cables. These gaps remain partly owing to difficulties in evaluating impacts at population scale around these deployments
  • 2001 – Orientation and navigation in elasmobranchs: which way forward? – covers their behaviour but not specifically in relation to submarine cables

https://www.diigo.com/user/kerrieanne/Offshorewind_EMF