Wave-actuated system, wave energy converter subsystem, and method for operating a reverse-osmosis desalination subsystem
A wave-actuated system for desalination of water by reverse osmosis (RO) has at least one offshore wave energy converter subsystem for pumping salt water and supplying the pumped salt water via a water outlet, a pretreatment subsystem hydraulically connected to the water outlet of the at least one offshore wave energy converter subsystem, and a RO desalination subsystem receiving filtered water from the pretreatment subsystem. The at least one wave-energy converter has a float and a hydraulic cylinder pumping salt water to the RO desalination subsystem. A method for operating a reverse-osmosis desalination subsystem using pressurized salt water supplied by at least one wave energy converter subsystem is described. A method for making a hull is also described.
1 . A wave energy converter (WEC) subsystem comprising:
a float;
an anchor disposed below the float;
a hydraulic cylinder connected to the float, the hydraulic cylinder comprising:
a cylinder body defining a cylinder axis,
a piston slidably received in the cylinder body, and
a rod connected to the piston and having a portion extending outside of the cylinder body, the rod and the piston being movable together along the cylinder axis between a retracted position and an extended position; and
a line management system comprising:
a rod pulley connected to the portion of the rod extending outside of the cylinder body and being movable along the cylinder axis together with the piston and the rod,
a swivel bracket connected to the float,
a bottom pulley rotatably supported by the swivel bracket about a rotation axis, the swivel bracket pivotably connecting the bottom pulley to the float about a pivot axis such that the bottom pulley is pivotable relative to the float about the pivot axis, the pivot axis being orthogonal to the rotation axis, and
a line connected between the float and the anchor, the line engaging the rod pulley and the bottom pulley,
during a first stroke of the WEC subsystem:
float is moving upward, and
the piston and the rod are moving towards the retracted position; and
during a second stroke of the WEC subsystem:
the float is moving downward, and
the piston and the rod are moving toward the extended position.
2 . The WEC subsystem of claim 1 , wherein the hydraulic cylinder is disposed generally horizontally.
3 . The WEC subsystem of claim 1 , wherein the bottom pulley is disposed below the hydraulic cylinder.
4 . The WEC subsystem of claim 1 , wherein the line engages the bottom pulley such that a vertical segment of the line is laterally and longitudinally aligned with a center of floatation of the float.
5 . The WEC subsystem of claim 1 , wherein the float includes at least two hulls each having a top surface, and the hydraulic cylinder is disposed between the at least two hulls and entirely below top surfaces of the at least two hulls.
6 . A wave-actuated system for desalination of water by reverse osmosis (RO), comprising:
the WEC subsystem of claim 1 ; and
a RO cell hydraulically connected to the hydraulic cylinder, the hydraulic cylinder supplying salt water to the RO cell.
7 . The WEC subsystem of claim 1 , wherein:
the swivel bracket and the bottom pulley are part of a pulley assembly; and
the pulley assembly includes at least one tube;
the line passing through the at least one tube for maintaining the line engaged with the bottom pulley.
8 . The WEC subsystem of claim 1 , wherein the line management system further comprises a winch connected to the float, the winch being lockable to maintain a predetermined length in the line.
9 . The WEC subsystem of claim 8 , wherein the line management system further comprises a redirection pulley, and the line is engaged in the redirection pulley.
10 . The WEC subsystem of claim 9 , further comprising:
a power source connected to the float and being operatively connected to the winch, and
a communication device operatively connected to the power source and the winch for remotely operating the winch.
11 . A wave energy converter (WEC) subsystem comprising:
a float;
an anchor disposed below the float;
a hydraulic cylinder connected to the float, the hydraulic cylinder comprising:
a cylinder body defining a cylinder axis,
a piston slidably received in the cylinder body, and
a rod connected to the piston and having a portion extending outside of the cylinder body, the rod and the piston being movable together along the cylinder axis between a retracted position and an extended position; and
a line management system comprising:
a rod pulley connected to the portion of the rod extending outside of the cylinder body and being movable along the cylinder axis together with the piston and the rod,
a bottom pulley connected to the float,
a line connected between the float and the anchor, the line engaging the rod pulley and the bottom pulley,
a redirection pulley, the line being engaged in the redirection pulley,
a winch connected to the float, the winch being lockable to maintain a predetermined length in the line,
during a first stroke of the WEC subsystem:
float is moving upward, and
the piston and the rod are moving towards the retracted position; and
during a second stroke of the WEC subsystem:
the float is moving downward, and
the piston and the rod are moving toward the extended position;
the line defining:
a first segment extending between the winch and the redirection pulley;
a second segment extending between the redirection pulley and the rod pulley;
a third segment extending between the rod pulley and the bottom pulley, the third segment being disposed below the second segment; and
a fourth segment extending between the bottom pulley and the anchor;
a first pitch angle being defined between the second segment and the cylinder axis when the rod is in the retracted position, and a second pitch angle being defined between the second segment and the cylinder axis when the rod is in the extended position, the first pitch angle being greater than the second pitch angle.
12 . The WEC subsystem of claim 1 , wherein the line is one of a rope, a cable, a strap, a belt, and a tether.
13 . The WEC subsystem of claim 1 , wherein the line includes a device for maintaining tension in the line, the device including at least one of:
at least one of a spring and an elastic cord connected in parallel to the line, and
a mass connected to the line.
14 . The WEC subsystem of claim 5 , wherein the at least two hulls are fillable using expanding foam.
15 . The wave-actuated system of claim 6 , wherein:
the piston defines first and second variable volume chambers within the cylinder body; and
the RO cell is hydraulically connected to the first and second variable volume chambers for receiving salt water from the first and second variable volume chambers.