An Experimental Study on the Performance of a Two-Body Point Absorber WEC

Abstract

Wave energy is a promising renewable resource, both abundant and consistent in the outer sea. However, development of commercial wave energy converters (WECs) require an extensive validation. For the two-body point absorbers, a critical aspect of WEC performance includes a wave absorption efficiency from the oscillating body and the efficiency of the power take-off (PTO) system, which converts the absorbed wave energy into usable electrical energy. This study presents an experimental investigation on the performance of a two-body point absorber WEC. The test model is based on RM3 model, including a floater and a spar part. However, the floater was optimized from the original RM3 model to enhance the wave absorption efficiency. Model tests were conducted in the KRISO Ocean Engineering Basin. The spar part was fixed to the towing carriage, assuming the stable motion of the spar and to focus on the energy absorption efficiency of floater and its PTO system. The PTO system consists of a ball-screw type mechanical system, which converts the floater's heave motion into rotational motion, and a generator with an electrical load, which transforms the rotational energy into an electrical energy. The model tests include three different scenarios: (1) the floater alone without the PTO system; (2) the floater with only the mechanical ball-screw system; and (3) the floater with the complete PTO system. Based on the model test re