Over the past few decades, marine current energy utilization has transitioned from conceptual demonstrations to industrial-scale prototypes. This progression now approaches a crucial phase emphasizing the need for industrialization and commercialization. This paper provides an in-depth examination of the developmental status of large-scale marine current turbines and arrays, underscoring the promising prospects for marine current energy systems. Despite the significant advancements, the deployment of these systems has revealed several challenges, including blade design optimization, transmission system selection, and the establishment of appropriate test sites. Addressing these issues is essential for technological maturity and economic feasibility, which will foster the next wave of innovation in marine energy systems. Furthermore, the paper offers various perspectives for future applications.

Accurate prediction of the dynamic responses of the floating offshore wind turbine (FOWT) under the blade pitch motion is quite challenging because of the strong nonlinear effects. In this study, a fully coupled and highly elaborated model was established based on the computational fluid dynamics, with the dynamic fluid body interaction method. The multi-stage movements consisting of the six degrees of freedom motions of the platform, the rotation of the rotor, and the blade pitch motion were defined by the superposition motion technologies. The blade pitch control module was created through the user-defined function to regulate the blade pitch motion. Then, several coupled dynamic simulations of the full-configuration DeepCwind floating wind turbine system were performed in power production, shutdown, and startup cases. The simulation results in the power production case indicate that the blade pitch motion decreases the generated aerodynamic loads and amplifies the response amplitude of the platform as negative damping is introduced in the FOWT system. The simulation results in the shutdown and startup cases indicate that the extreme motion responses are enlarged, and the mooring line tension oscillates dramatically when it is in high-tension states. In addition, the nonlinear interference effects in the unsteady flow fields, such as the shedding vortices broken by the blade pitch motion, are visualized and investigated in detail.

The rivers connecting oceans generally carry sediment due to water and soil losses in China. Additionally, the maximum sediment concentration is 300 g/L, which is much higher than that of other countries. It is unknown whether seawater with sand particles will affect the power of tidal current turbine blades. It is therefore necessary to study the capture power of tidal current turbines in the water-sediment environment. In this study, the blade was divided into a number of transversal airfoil elements based on the blade element theory. The CFD-DPM model was employed to study the lift and drag coefficients of airfoil under multiphase flow, and the fluid–particle interaction was considered. The accuracy of this presented model was assessed using the experimental data of a 120 kW tidal current turbine in a water-sediment environment. Good agreement between the predictions and experimental data was observed. The effect of particle properties on the lift coefficient and the drag coefficient of airfoil were investigated in detail. Furthermore, the 120 kW tidal current turbine power was calculated based on the Blade Element Momentum theory under different particle concentrations. The results show that small diameter particles can improve the tidal current turbine power and the large diameter particle can reduce the power.