Tidal stream turbine generator and drivetrain design options

This chapter has presented several design options for generators and drivetrains, which can be used for tidal stream generation to reach the challenging requirements of tidal energy generation in terms of cost, reliability, efficiency, and system integration: geared and direct-drive options (including rim-driven option) generators with several possible technological options (induction generators, synchronous generators, doubly fed induction generators, unconventional generators). The use of possible technological choices for gearboxes was also discussed, including conventional and specific magnetic gearboxes, which are a relevant way to improve powertrains in this context. Consequences of generators and drivetrains choices when using a specific optimal harnessing strategy (MPPT with power leveling) associated with several turbine technological options (horizontal or vertical axis turbines, fixed- or variable-pitch turbines) have also been discussed. This chapter will undoubtedly serve as a guide for generator and drivetrain choice which can be useful for prospective tidal turbine developers considering the main constraints related to the marine energy harnessing, including cost (i.e., OPEX and CAPEX), reliability, and efficiency.