The influence of biofouling on power capture and the fatigue life of mooring lines and power cables used in wave energy converters

Paper in proceeding, 2016

This study presents an analysis of a wave energy converter (WEC) system consisting of a buoy, a mooring system and a power cable connected to a hub. The investigated WEC system is currently under full-scale testing near Runde in Norway. The purpose of the study was to investigate the characteristics of the entire system, primarily with regard to energy performance and the fatigue life of the mooring lines and power cable, considering the effects of marine biofouling and its growth on the system’s components. The energy performance of the system and the fatigue life of the mooring lines and the power cable were systematically studied via parameter variation analysis, considering different mooring configurations, biofouling conditions, and environmental loads (current and sea state conditions), among other factors. Hydrodynamic and structural response simulations were conducted in a coupled response analysis using the DNV-GL software SESAM. Energy performance analyses and stress-based rainflow counting fatigue calculations were performed separately using an in-house code. The results show that, for a WEC system which has been deployed for 25 years, biofouling can reduce the total power absorption by up to 10% and decrease the fatigue life of the mooring lines by approximately 20%.