This study investigates the dynamics and energy production of a new offshore floating renewable energy system, which integrates an offshore floating wind turbine (OFWT), a wave energy converter (WEC) and two tidal turbines. The hybrid concept is proposed to enhance the energy production through the combination of the three types of renewable energy systems. Simulation results show that the combined concept achieves a synergy between the floating wind turbine, the wave energy converter and the tidal turbines. Compared with a single floating wind turbine, the combined concept undertakes reduced surge and pitch motions. The overall power production increases by approximately 15%.
Due to the issues like environmental pollution, energy crisis and sustainable development, the exploitation of offshore energy is boosted by the global pursuit of renewable energy. Coastal areas provide the renewable energy sources in the form of wind, sea currents, and waves. Theories and technologies have been developed to exploit these types of offshore renewable energy resources.
Over the last decade, a large number of offshore floating wind turbine concepts have been developed. Statoil Nielsen et al. (2006) proposed a SPAR-buoy floating wind turbine, namely the Hywind concept, which is the first full-scale floating wind turbine that has ever been built. Principle Power installed a full-scale 2MW WindFloat prototype near the coast of Portugal (Principle Power, 2017). Hu et al. (2016) investigated the dynamics of a semi-submersible floating wind turbine during normal operation state and emergency shutdown. Li et al. (2018a) measured the dynamic response of a floating wind turbine in experimental environment. Cheng et al. (2017b) numerically examined the dynamics of a vertical axis floating wind turbine.
Compared to wind, wave energy is a renewable resource with high power density and all-day availability. WECs with various operation mechanisms have been proposed. Zhang and Yang (2015) studied the power capture of a heaving point absorber in both regular and irregular waves. Henriques et al. (2016) enlarged the energy absorption of an oscillating-water-column WEC with latching control strategy. Babarit et al. (2017) utilized pressure-different mechanism to extract energy from the sea waves.