Abstract
This paper presents a review-based comparative study of state-of-the-art technologies, technical challenges and research barriers, and development trends of gearboxes used in tidal current energy converters (TCECs). Currently, the development of commercial projects using TCECs is still in the demonstration phase. While many drivetrain designs and configurations of TCECs inherit from those of wind turbines, different operational constraints, e.g., high-torque and low-speed conditions, make TCECs potentially suffer from high failure rates in harsh deep-sea environments. Evidence of these potentially high failure rates highlights the need for adopting the most resilient drivetrain options with a high degree of maintainability. The gearbox option is a critical issue that needs to be addressed for the choice of the drivetrain configuration due to its longest downtime per failure among all drivetrain components of TCECs. The main purpose of this study is to review current gearbox technologies of TCECs with advantages and disadvantages as well as to identify future technical challenges and research barriers. Gearbox maintenance is also a focal point in this study. We present a discussion of the operation phase to highlight operational maintenance methods currently used in the tidal energy industry. This study will, therefore, address the critical issue by proposing a review-based gearbox option comparison and discussing potential solutions to reduce operation and maintenance costs of gearboxes of TCECs.