This paper presents a part of the preliminary studies for the design and the construction of a barge-type floating offshore wind turbine demonstration project in Kitakyushu, Japan. The wind turbine's floating support structure is equipped with a moonpool and a bottom skirt and is moored with catenary lines. In this study, a 1/50 scaled model wave tank experiment and a numerical simulation analysis were conducted to grasp the dynamic response behavior of the wind turbine in regular and irregular waves. As the results, response amplitude operators, statistical values, and amplitude spectral densities of the wind turbine's motion responses are compared with the simulation results and showed a generally good agreement between the two.
To realize a low-carbon society, the development of renewable energy technologies including wind turbine in the world has been progressing steadily. In Japan itself, the development of offshore wind turbine has been increasing in the recent years for both fixed-foundation wind turbine and floating offshore wind turbine (FOWT). Several FOWTs have been installed in Japan in the past years (JWPA, 2017). In 2013, the first operational scale FOWT in Japan, a 2 MW spar-type FOWT was installed in Nagasaki (Ishida, 2018). Then, as part of the Fukushima FORWARD project (Suzuki, 2018), in 2013, a 2 MW semi-submersible (Imakita, 2018), in 2015, a 7 MW V-shaped semi-submersible (Komatsu et al, 2016), and in 2016, a 5 MW advanced spar-type (Kitakoji, 2018) FOWTs were installed in Fukushima.
For moderate water depth of 50–100 m, barge-type configuration is considered advantageous as the barge-type floating support structure (floater) usually has a shallow draught. Its shallow draught enables it to be installed in shallower water depth compared to other configurations with deeper draught such as the spar-type floater. Then, compared to a semi-submersible floater, a barge-type floater is also easier to design and manufacture. Its tower and rotor and nacelle assembly's (RNA) construction can be completed in a nearby dock before being towed to its designated installation location.
