The Impact of Electromagnetic Fields and Chemicals from Offshore Wind Farm Subsea Power Cables on Marine Environment

Abstract

For many years, Subsea Power Cables (SPCs) have been installed across creeks and bays, connecting near-shore islands to the mainland. In more recent times, SPCs have been applied to supply power from offshore renewable energy installations to onshore substations, with little consideration for possible impacts of Electro-Magnetic Fields (EMFs) and chemicals from SPCs on marine species. Hence, this study unravelled the electromagnetic impacts by quantifying and characterising the EMFs produced by current and potential future SPCs. The Alternating Current cables produced magnetic field strengths ranging between 0.69 and 4.86 µT, and induced field strengths varying from 2.19 × 10 ^(-4) to 1.53 ×10^(-3) V/m. On the other hand, the Direct Current cables produced magnetic fields of 56.20 105.59 µT and induced electric fields from 2.87 × 10^(-5) to 2.30 × 10^(-4) V/m. The calculated intensities were then compared with the sensitivity threshold values of priority marine species with electromagnetic sensory capabilities, to establish the spectrum of species that are affected by the cables. In addition to this, an easy-to-use EMF estimation tool was developed to enable non-specialist users to model and estimate underwater cable emissions.

This study also investigated the toxicity of power cables: concentration of heavy metals (i.e. Al, Fe, Pb, Mn, As, Hg, Cd, Cu, and Ni) and abundance of microplastics released by four SPCs using different experimental procedures, an area of study which was hitherto relatively unresearched. The results revealed varying concentrations of the selected heavy metals. In addition, the study observed low levels of microplastic particles that were discharged by the cables. Collectively, the results provided new insights into the extent of pollution caused by SPCs. Finally, future research directions in this field were suggested.