HVDC Offshore Return Electrodes; light or heavy?

The number of HVDC plants is continuously increasing, basically due to practical reasons -i.e. frequent impossibility to develop a terrestrial routing- and to the better exploitation of renewable energy sources. Therefore, the number of sea return electrodes increases, and the risk of damage due to impact with objects such as anchors and fishing nets becomes more probable. One issue that should be analyzed is thus the overall structural resistance of offshore sea electrodes to such kinds of events. Of course, electrode module weight has a significant impact on the time and cost of electrode laying, so it is necessary to find a good compromise between these two conflicting requirements. This paper is aimed at providing an overview of the main arising issues and of the guidelines that can be followed.