Submersible turbine-generator unit for ocean and tidal currents
A submersible turbine-generator unit includes two or more turbines mounted on a common shaft with a generator therebetween. Each such turbine is capable of providing relatively low-speed, unidirectional rotation under a reversible ultra low head pressure and/or low velocity fluid flow. A plurality of airfoil-shaped turbine blades mount parallel to the common shaft and transversely to the direction of fluid flow for rotation in a plane parallel to the fluid flow. The turbines convert energy in the waterway currents into mechanical energy that will transfer through the turbine shaft to a cylindrical permanent magnet generator which will convert mechanical energy in the form of RPM and torque into electricity. Electricity from the variable speed electric generator is controlled, synchronized, conditioned and transformed into utility-grade electricity using a power electronics system in each module.
1. 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.
2. The unit according to claim 1 , further comprising a support structure adapted for safe navigation upon the water and submersion and surfacing within the ocean or tidal currents.
3. The unit according to claim 2 , wherein said support structure further comprises one or more ballast tanks and means for flooding and blowing said ballast tanks.
4. The unit according to claim 1 , further comprising means for mooring said module within a flow of the ocean or tidal currents.
5. The unit of claim 4 , further comprising a plurality of submersible turbine-generator units, each of which is separately coupled to said mooring means.
6. The unit of claim 5 , further comprising a plurality of submersible turbine-generator units, which are arrayed together and coupled to said mooring means.
7. The system according to claim 5 , further comprising a plurality of submersible turbine-generator units forming a plurality of arrays of said submersible turbine-generator units, each said array being separately coupled to said mooring means.
8. The unit according to claim 1 , further comprising means for transmitting electricity generated by said generator to shore.
9. The unit according to claim 1 , further comprising means for storing electricity generated by said generator.
10. The unit according to claim 1 , further comprising means for generating and storing by-products of the electricity generated by said generator.
11. The unit according to claim 10 , wherein said by-products comprise hydrogen.
12. The unit according to claim 10 , wherein said by-products comprise potable water.
13. The unit according to claim 1 , wherein said turbine chamber has a curved configuration having opposite elevations in the plane parallel to said flow path, said elevations being offset in a direction of rotation of said leading edge to rotatably channel fluid in said flow path and to direct fluid flow to said plurality of blades with a radial component of flow relative to said blades.
14. The unit of claim 1 , wherein said generator comprises:
a plurality of stator segments;
a plurality of rotor segments;
wherein said plurality of stator segments and said plurality of rotor segments are adapted for modular assembly.
15. The unit of claim 14 , wherein one or more of the plurality of stator segments and/or rotor segments are selectively replaceable.
16. The unit of claim 14 , further comprising a watertight housing having one or more removable endcaps.
17. The unit of claim 14 , further comprising a stuffing box for sealing a shaft-endcap intersection.