Inertial wave energy converter
A wave energy converter generates power from a wave-induced separation of a positively buoyant flotation module and a submerged negatively buoyant mass, using a rotating pulley to drive a power-take-off system.
1. An inertial wave energy converter, comprising:
a positively buoyant flotation module adapted to float on a surface of a body of water;
a pulley mounted rotatably at the positively buoyant flotation module;
a power-take-off system configured to resist rotation of said pulley;
an inertial mass suspended in said body of water; and
a flexible connector having a first portion coupled to said inertial mass and a second portion engaging said pulley, said flexible connector including a ribbon;
wherein said ribbon comprises a plurality of flexible subconnectors arranged side-by-side and engaging said pulley;
wherein said power-take-off system resists rotation of said pulley with a first resistive torque;
wherein said flexible connector applies a first driving torque to rotate said pulley in a first direction when a separation distance between said positively buoyant flotation module and said inertial mass increases, said first driving torque exceeding said first resistive torque; and
wherein said pulley is biased to rotate in a second direction when said separation distance decreases.
2. The inertial wave energy converter of claim 1 , wherein said pulley is biased to rotate in said second direction by a restoring weight, said restoring weight gravitationally energized when a separation distance between said positively buoyant flotation module and said inertial mass increases.
3. The inertial wave energy converter of claim 1 , wherein said pulley is biased to rotate in said second direction by a pressurized gas.
4. The inertial wave energy converter of claim 1 , wherein said pulley is biased to rotate in said second direction by an electric motor.
5. The inertial wave energy converter of claim 1 , wherein said inertial mass encloses water.
6. The inertial wave energy converter of claim 5 , wherein a ratio of a hydrodynamic added mass of said inertial mass to a mass of an included water of said inertial mass is less than 1:1.
7. The inertial wave energy converter of claim 6 , wherein said included water consists of water located inside a convex hull defined by said inertial mass.
8. The inertial wave energy converter of claim 1 , wherein an exterior of said inertial mass is coated with drag-reducing surface coating.
9. The inertial wave energy converter of claim 8 , wherein the drag-reducing surface coating is hydrophobic.
10. The inertial wave energy converter of claim 1 , wherein said inertial mass has a curved upper surface.
11. The inertial wave energy converter of claim 1 , wherein said inertial mass has a curved lower surface.
12. An inertial wave energy converter, comprising:
a positively buoyant flotation module adapted to float on a surface of a body of water;
a pulley mounted rotatably at the positively buoyant flotation module;
a power-take-off system configured to resist rotation of said pulley;
an inertial mass suspended in said body of water;
a restoring weight suspended in said body of water, said restoring weight having a lesser wet weight than said inertial mass;
a first flexible connector having a first flexible connector portion coupled to said inertial mass and a second flexible connector portion engaging said pulley;
a second flexible connector having a third flexible connector portion coupled to said restoring weight and a fourth flexible connector portion engaging said pulley;
wherein said first flexible connector applies a driving torque to said pulley to drive said power-take-off system when a separation distance between said inertial mass and said positively buoyant flotation module increases; and
wherein said restoring weight reduces slack in said first flexible connector when a separation distance between said inertial mass and said positively buoyant flotation module decreases.
13. The inertial wave energy converter of claim 12 , wherein said inertial mass encloses water.
14. The inertial wave energy converter of claim 12 , wherein a quotient of a hydrodynamic added mass of said inertial mass to a mass of an included water of said inertial mass is less than unity.
15. The inertial wave energy converter of claim 14 , wherein said included water consists of water located inside a convex hull defined by said inertial mass.
16. The inertial wave energy converter of claim 12 , wherein the first flexible connector is continuous with the second flexible connector.
17. The inertial wave energy converter of claim 12 , wherein the second flexible connector portion is fixedly attached to a surface feature of said pulley.
18. The inertial wave energy converter of claim 17 , wherein said surface feature protrudes from a surface of said pulley.
19. The inertial wave energy converter of claim 12 , wherein the power-take-off system includes a hydraulic transmission.
20. The inertial wave energy converter of claim 19 , wherein the hydraulic transmission includes hydraulic cylinders engaged with a crankshaft.
21. The inertial wave energy converter of claim 12 , wherein an exterior of said inertial mass is coated with drag-reducing surface coating.
22. The inertial wave energy converter of claim 12 , wherein the drag-reducing surface coating is hydrophobic.
23. The inertial wave energy converter of claim 12 , wherein said inertial mass has a curved upper surface.
24. The inertial wave energy converter of claim 12 , wherein said inertial mass has a curved lower surface.
25. The inertial wave energy converter of claim 12 , wherein at least one of the first flexible connector and second flexible connector comprises a ribbon.