At Sea Experiment of a Hybrid Spar for Floating Offshore Wind Turbine Using 1/10 Scale Model

Abstract

This study aims at development of a costeffective, floating offshore wind turbine. The prototype model considered herein is composed of (1) 2MW horizontalaxis wind turbine (HAWT) of downwind type, (2) steel monotower with 55m hub height above sea level, (3) steelprestressed concrete (PC) hybrid SPARtype foundation with 70m draft, and (4) catenary mooring system using anchor chains. In order to demonstrate the feasibility of the concept, an atsea experiment using a 1/10scale model of the prototype has been made. The demonstrative experiment includes (1) construction of the hybrid SPAR foundation using PC and steel, the same as the prototype; (2) drytowing and installation to the atsea site at 30m distance from the quay of the Sasebo shipbuilding yard; (3) generating electric power using a 1 kW HAWT; and (4) removal from the site. During the atsea experiment, wind speed, wind direction, tidal height, wave height, motion of the SPAR, tension in a mooring chain, and strains in the tower and the SPAR foundation have been measured. Motion of the SPAR has been numerically simulated and compared with the measured values, where basically good agreement is observed.