Vertical-Axis Tidal Turbine
The horizontal flow of water can be harnessed to drive turbines as an intermittent but highly predictable source of renewable energy. Whether from ocean currents or tidal flow, the novel radial bearing and rotor from Plithos Renewables can enable a vertical-axis turbine to be suspended from a floating platform guided by piling.
As with the vertical-axis wind turbines, the intended application will influence the type of turbine used. Savonius scoops will provide a high torque output and Darrieus or H-rotor configurations with airfoil blades are more suited for electrical generation. The height of the rotor must be smaller than the water depth at low tide to prevent collision with the seafloor.
Having a pontoon mounted turbine rather than one fixed to the seafloor allows for the power-take-off to be held above water for easier maintenance access. This makes the length of the piles used the only unique part when planning for different tidal ranges.
The brick-based modular radial bearing is used to support the submerged rotor as with the wind turbine to provide ruggedness.
Partially enclosing an estuary with an array of the turbines to form a "tidal fence" can be a compromise between a tidal barrage that requires a large amount of concrete and the desire to reduce the impact on local ecosystems.
The Wave Thrust Bearing can be used in a hydrostatic transmission system for a tidal fence to connect the output of all individual turbines to a large hydraulic motor that is located on solid ground.