Site-specific Modeling of self-reacting point absorber in real wave spectrum

Abstract

Power performance of floating wave energy converters is typically performed under regular wave conditions or using standard ocean spectrum models with one peak. We explore the effect of device geometry of a self-reacting point absorber (SRPA) for real wave spectrum having multiple peaks. Different float and torus designs are evaluated to alter the cut-off frequency of the SRPA to extract more power in operating wave periods representative of two real ocean sites. A float with a damping plate was more suitable for higher wave periods, while a slender body float was preferred for lower wave periods. Increasing the torus outer diameter increased the absorbed power by 20% for low wave period while the absorbed power was reduced by 5% for a high wave period site. The modified SRPA with slender body float showed a four-fold increase in annual energy production when compared to regular wave conditions for the low wave period site. For the high wave period sea site, a modified SRPA with a damping plate showed a 6% increase in annual energy production. The study shows that while the geometry of the SRPA determines the operating period, the PTO damping can be varied to determine the operating bandwidth.