Tidal stream turbines: With or without a Gearbox?

This paper proposes a review-based comparative study addressing the critical issue of tidal stream turbine drivetrain options. Indeed, tidal stream turbines are still in development stages with few industrial project deployments. Their technology is not as mature as wind turbine technology, while facing immersion constraints where have to withstand high loading and harsh submarine conditions. These constraints make tidal stream turbines potentially suffering from higher failures rate. Evidence of this potential higher failures rate highlights the need for adopting the most resilient drivetrain options with a higher degree of maintainability. Indeed, even though tidal stream and wind turbine drivetrains remain similar, the load variability differs. In competitiveness and large deployment contexts, tidal stream turbines are facing many challenges. The drivetrain configuration choice is one of the most important one that should address the question: with or without a gearbox? Indeed, the gearbox should be one of the important concerns for future tidal farm operators (as it is for wind farm operators), mainly because of its highest downtime per failure amongst all the tidal stream turbine drivetrain components. This paper will therefore address this critical issue by proposing a review-based drivetrain options comparison and discussing potential and promising topology options as the magnetic gearbox.