Electromagnetic fields (EMF) are physical fields that consists of both electric and magnetic components and are generated by electrically charged objects. In the case of wind energy and marine renewable energy devices, EMF may be generated around dynamic devices, substations, and most commonly, transmission cables. The distance over which EMF persist is typically dependent on the strength of the electrical charge, characteristics of the surrounding environment, and characteristics of the cable or device. For example, electric fields can typically be contained by burial of or shielding within a subsea transmission cable; however, magnetic fields are not as easily contained.
Marine organisms at high risk of EMF impacts are typically electro- and/or magneto-sensitive organisms such as elasmobranchs (i.e. sharks, skates, rays), some fish species (e.g. eels, sturgeon), sea turtles, and benthic invertebrates. Some of these organisms use Earth’s naturally occurring geomagnetic fields for navigation, orientation and predation. Thus, the addition of anthropogenic EMF may alter organisms’ movement, migration, and foraging behavior. High intensity EMF may additionally affect organisms’ developmental physiology. Current levels of EMF emitted from offshore wind and marine renewable energy devices have not yet reached high intensities, however, as the offshore energy industry expands, greater levels of EMF may result in additional effects on the marine environment.
For more information, check out the EMF Short Science Summary produced by OES-Environmental.
Photo Credit: ABB