Patent ID: 7902687

Claim:
A submersible turbine-generator unit for generating electricity from ocean or tidal currents, comprising: a. a generator; b. a shaft for driving said generator; c. two or more unidirectional turbines capable of rotation under reversible fluid flow, each of which is mounted on said shaft at either side of said generator such that the shaft, the two or more turbines and the generator are coaxial, wherein i. a removable shaft extension system is disposed along the shaft between the generator and the two or more turbines such that the generator is removable without requiring disassembly of the two or more unidirectional turbines and ii. no gears exist between the generator and the turbines; and d. a framework for supporting said generator, said shaft, said removable shaft extension system and said two or more turbines wherein i. the framework surrounds the two or more turbines in interconnected individual turbine chambers defining a fluid flow path across the turbine; ii. the rotatable shaft is transversely mounted through the interconnected turbine chambers; iii. at least one turbine blade support member is fixedly mounted to the rotatable shaft for rotation therewith in a plane perpendicular to said shaft axis; iv. the two or more turbines each comprise a plurality of turbine blades fixedly mounted to the at least one blade support member such that the plurality of turbine blades are oriented parallel to and radially spaced apart from the rotatable shaft; and v. each of the plurality of blades has an airfoil shape having a leading edge and a trailing edge and a chord there between, said airfoil shape oriented transversely to said flow path with said chord lying generally along a circular rotation path, so that each of the plurality of blades is oriented for rotation along said rotation path in a plane parallel to said flow path in the direction of said leading edge.