WO2012131621A2

WO2012131621A2 - Wave energy converter with desalination plant

Info

Publication number: WO2012131621A2
Application number: PCT/IB2012/051523
Authority: WO
Inventors: James G. P. Dehlsen
Original assignee: Dehlsen Associates, Llc
Priority date: 2011-03-31
Filing date: 2012-03-29
Publication date: 2012-10-04
Also published as: WO2012131621A3

Abstract

A power-generating device (10, 150) located on an ocean=s surface coupled to a deeply-submerged tray structure (40) suspended from its underside, which is used to produce desalinated water by the process of reverse osmosis driven by hydrostatic pressure at depth and augmented by power from the device that is delivered to pumps (60) on the tray (40). A traveling hoist (65, 70) services and populates the tray (40) with reverse osmosis (RO) cartridges (50) lowered to the tray (40) from the ocean surface. In one embodiment, the power-generating device (10) is moored to incoming ocean waves, with a yawing capability to adjust to changes in wave direction. Rotary torque is produced when pods (30) move up and down according to wave motion, and the torque is transmitted to a generator to generate power, in another embodiment, a solar photovoltaic array (150) disposed on the ocean surface is the power-generating device for the desalination system (20), using a storage tank (158) for excess power.

Description

SPECIFICATIONS AND CLAIMS OF PATENT APPLICATION WAVE ENERGY CONVERTER WITH DESALINATION PLANT

PRIORITY CLAIM

This application claims the benefit of U. S. Provisional Application No. 61/516,327, which was filed on March 31 , 2011 in the United States Patent & Trademark Office.

BACKGROUND OF THE INVENTION

1 . Field of the Invention

The present invention relates to an apparatus that is powered by a device which captures energy resident in the motion of ocean waves or solar energy and converts it to energy used to operate a desalination plant. The process of desalination uses reverse osmosis driven by hydrostatic pressure at depth.

2. Description of Related Art

U. S. Patent Application Publication US 201 1/0025072 to Ovadia, titled "System And Method For Water Desalination And Other Uses", discloses a system for converting wave energy into rotary motion, which is used for electric power generation for sea water desalination. The system uses buoyancy means upon sea waves, whereby the buoyancy means move according to the motion of sea waves. A piston containing fluid is pivotally attached to the buoyancy means, thereby converting mechanical kinetic energy of wave motion into hydraulic pressure of fluid. A hydraulic system includes pipes and one or more one-directional valves for allowing pressure conservation in the hydraulic system, even after releasing the piston. The fluid pressure is preferably stored in a pressure container. The system further includes a hydraulic motor or a turbine that is operatively connected to the hydraulic system, whereby the hydraulic pressure creates a flow of fluid that operatively rotates the hydraulic motor or the turbine. The resulting rotary motion is used to operate a seawater desalination system without the use of electrical energy from an external source and/or fuel energy. However, the application does not address using hydrostatic pressure for reverse osmosis to accomplish seawater desalination.

U. S. Patent 7,023,104 to Kobashikawa, et al., titled "Wave Energy Conversion Device for Desalination, etc." discloses an impulse-type "wave motor" that employs a seabed-mounted or supported structure, mounting a wave-energy-absorbing panel on a hinged lever arm for reciprocating motion in order to obtain optimal absorption of wave energy from the motion of sea waves. For deepwater wavelengths of L, the panel is optimally positioned in a region within L/2 depth from the sea surface. The panel=s motion is coupled by a connecting rod to a fluid pump, which generates a high-pressure fluid output that may be used to drive a reverse osmosis desalination unit. Seawater is desalinated through reverse osmosis membranes to produce desalinated water. The submerged operating environment of the device in a region of one-half the design wavelength provides the maximum available energy flux and forced oscillations. The pump may be of the positive-displacement piston type, plunger type, or multi-staging driver type, or a variable volume pump. The main disadvantage of Kobashikawa, et al. is the requirement that it be anchored to the ocean floor close to shore and located such that the operating environment of the device is restricted to deployment in a region of one-half the design wavelength. This means that the device cannot be deployed in the open ocean.

What is needed is a self-contained desalination system that includes a power- generating device for capturing power from the motion of ocean waves or solar energy, the device providing a stable platform for the system, so that it can be deployed in the open ocean. The system should permit desalination at depth using hydrostatic pressure for water production, reducing or eliminating the need for pumping to drive the reverse osmosis processes and using the electric power generated by the device for other operational needs of the reverse osmosis system, such as activating valves and pumping the product water to shore.

Other methods of providing power to a self-contained desalination system can be provided when the system is merely submerged at depth.

The system must have minimal impact on the marine environment, such as fishing grounds and the beach shoreline, and its operation must not interfere with ocean navigation.

It is desirable to provide a method and apparatus for seawater desalination that is efficient, cost-effective to manufacture and to maintain, and capable of withstanding severe weather events.

It is also desirable to combine efficient renewable energy resources (wave, solar, wind, ocean currents) with deep water reverse osmosis which, as an integrated system, can deliver both fresh water and electric power to shore at competitive prices, through the added utility gained in said combination.

It is further desirable to have a method and apparatus that is scalable in order to gain economies in deployment and servicing of the desalination system.

It is also desirable to provide a method and apparatus of configuring a desalination system that it is capable of being transported to and from port without interference with ocean navigation and which can then be assembled at sea.

It is also desirable for the desalination system to be compatible with the wave energy converter device described in the related PCT application, such that it has an active yaw system to enable optimum/maximum exposure to oncoming waves to maximize energy capture.

It is also desirable for the desalination system to be compatible with an ocean surface platform with photovoltaic panels to provide power to the reverse osmosis system and for pumping product water to shore. SUMMARY OF THE INVENTION

The present invention is related to the invention that is the subject of International Patent Application No. PCT/IB2009/006614, "Method and Apparatus for Converting Ocean Wave Energy into Electricity", filed on August 24. 2009, the disclosure of which is incorporated herein by reference

Briefly, the present invention relates to an apparatus comprising: a wave energy conversion device for converting wave energy captured from ocean wave motion to a power output, said device located on the surface of the ocean; and a desalination plant comprising a tray holding reverse osmosis (RO) cartridges, the tray suspended from said wave energy conversion device, the desalination plant operating at a depth below the ocean surface.

In another embodiment of the present invention, energy for the desalination plant is provided by the use of photovoltaic cells, which is delivered to power the desalination plant, which comprises a tray holding reverse osmosis (RO) cartridges, the desalination plant operating at a depth below the ocean surface. Power generated beyond the requirements of pumping and plant operation is delivered to the shore substation of the electric grid.

In accordance with an aspect of the invention, the desalination plant is of a type operating by reverse osmosis driven by hydrostatic pressure at depth.

In accordance with a further aspect of the invention the wave energy conversion device supplies power to the desalination plant primarily for pumping desalinated water to shore, as well as to equipment used for operating and servicing the desalination plant.

In accordance with a further aspect of the invention the wave power is converted to electrical power and/or hydraulic power.

The invention provides a means for regular servicing of individual reverse osmosis cartridges by enabling the hoisting of each cartridge to the surface and its reinstallation from the surface to the operating depth.

As an additional advantage offered by the invention, both the wave energy converter and the desalination plant share mooring points, as well as access route infrastructure to shore for both water delivery and electric power.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a perspective view of the wave energy converter device and the desalination plant of the present invention, which is suspended therefrom.

Figs. 2 and 3 are perspective close-up views of the submerged tray structure of the desalination plant.

Fig. 4 is a detail view of an RO cartridge, showing one of its modules.

Figs. 5 and 6 are end views of the reverse osmosis cartridges disposed in the tray structure shown in Figs. 2 and 3.

Figs. 7 and 8 are perspective views of the crane and hoist system affixed to the wave energy converter device, which is used to transport the cartridges of the desalination plant of the present invention.

Fig. 9 is a perspective view of the submerged tray structure illustrating the lowering of a reverse osmosis cartridge into the tray grid.

Fig. 10 is a perspective view of a reverse osmosis cartridge held by a lifting frame which uses a mechanical attachment device or which has been electromagnetically energized to grip the cartridge.

Fig. 1 1 is a perspective view of a reverse osmosis cartridge after it has been released by a lifting frame which has been either mechanically unlatched or has been electromagnetically de-energized to release the cartridge.

Fig. 12 is a plan view of the reverse osmosis cartridge of Fig. 1 1 , showing the alignment of the lifting frame to the cartridge, and the positioning of the cartridge over the tray structure.

Fig. 13 is an alternate embodiment of the present invention wherein a desalination plant platform is positioned in the ocean at a depth below the ocean surface and is held in position by cables providing tension legs.

Fig. 14 is a perspective view of yet another alternate embodiment of the present invention wherein energy is generated an solar array of photovoltaic cells at the ocean surface, and the desalination plant of the present invention is suspended therefrom. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention can be operated in conjunction with a power-generating device called a wave energy converter (WEC), which is a marine floating structure designed to convert wave energy to electric power. A typical floating structure that converts wave energy to electric power is described in the International Patent Application No. PCT/IB2009/006614, referred to supra. In accordance with the present invention, suspended from the wave energy converter is a deeply-submerged tray structure holding a plurality of cartridges, which are used for the production of desalinated water by reverse osmosis (RO), and which are driven by hydrostatic pressure at depth. It should be noted that the present invention can operate using power generated by another source, such as an offshore wind generator, a gasoline engine on a marine vessel, or marine current turbines.

Fig. 1 is a perspective view of the wave energy converter (WEC) 10 and the desalination plant 20 of the present invention. The WEC is described in detail in the PCT application referred to supra. Generally, each of a plurality of pods 30 is mounted to a lever assembly/arm 31. Each of the arms 31 is hinged to an upper support member 33, 34 of a base structure. The base structure is generally constructed as a rigid truss system, comprising two tubes 35, 36 arranged in parallel to the upper support members 33, 34, so that the tubes 35, 36 and the upper support members 33, 34 form a rectangular shape, with the tubes 35, 36 and the upper support members 33, 34 in the corners of the rectangle. Between the upper support members 33. 34 and the tubes 35, 36 there are stabilizer tubes or truss rails 37, 38, which provide stiffness in torsion, tension and bending of the truss system. The base structure length is such that the entire structure straddles two or three waves, minimizing the pitching up and down, bow to stern of the structure, thereby causing the wave action to be concentrated on driving the pods 30 up and down as the waves pass by. The submerged portion of the base structure is also less subject to the forces of the passing waves, providing a stable platform and forcing maximum movement to the pumping action of the pods 30. Coupled to the arms 31 are hydraulic pistons 32, which are actuated by the relative motion between the pods 30 and the base member when the pods 30 are moved by the waves in an up-and-down motion. In this example, one piston 32 is actuated by each pod 30. It should be understood that some or all of the pods 30 and lever assemblies/arms 31 can drive one or more linear electric motors in addition to or as an alternative to the hydraulic pistons 32.

The main body length of the WEC 10 is such that the assembled length of modules will ensure optimal deflection of the pods 30 for energy capture. The wave energy converter (WEC) 10 extracts power from waves on both the up and the down movements of the waves. The passing of the waves causes multiple pods 30 to move up and down. The up motion of the pods 30 is driven by displacement of the wave and actuates hydraulic pistons 32 that pump hydraulic fluid to a nozzle that drives an impulse turbine or hydraulic motor; a Pelton wheel is an example of such an impulse turbine. The down motion of the pods 30 capture the gravity effect on the pod 30 and its mass to also drive a hydraulic piston. The action of the water under pressure is accelerated when it is forced to flow through the nozzle. The high-velocity jet from the nozzle impinges on buckets around the turbine wheel, causing the wheel to rotate about a shaft, which is connected to an electric generator. The impulse turbine can be replaced with any hydraulic motor that takes energy from moving fluid, including a impulse turbine or a Pelton wheel. Alternatively, the pod movement could be coupled to a linear electric motor to generate electricity directly.

The floating wave energy converter 10 structure serves as a platform from which to deploy and service the desalination plant 20. The tray structure 40 is supported by suspension cables 42, 44, 46, 48, beneath the wave energy converter 10 at a depth of approximately 300-400m. The tray structure 40 contains receptacles 41 for inserting a number of reverse osmosis (RO) cartridges 50 that desalinate seawater and deliver desalinated water through water pipe 52 for transport to shore by pipeline 54, or to tanker ships designed to transport liquids in bulk. The submerged tray structure 40 suspended at each end by cables 42, 44, 46, 48 attached to the wave energy converter 10 also provides pitch stability to the wave energy converter 10, thereby causing the pods 30 to have a greater displacement, converting more energy. Floats 53 keep the pipeline 54 from kinking.

Figs. 2 and 3 show the features of the desalination plant 20 in more detail, which uses the process of reverse osmosis. Reverse osmosis (RO) is a widely used filtration method that removes salt from seawater by applying pressure to the seawater when it is on one side of a selective membrane. The result is that the salt is retained on the pressurized side of the membrane and the filtered pure water is allowed to pass to the other side. Each of the RO cartridges 50 fits into a receptacle 41 of the tray structure 40, which is supported by suspension cables 42, 44, 46, 48. Pumps 60 on the tray structure 40 pump desalinated water through outlet pipe 52 to pipeline 54 or to a tanker ship. The pumps 60 may be driven by electric power generated by the wave energy converter 10 at the ocean surface, or by a hydraulic drive on the wave energy converter 10. Power is delivered to the pumps 60 by power cable 55, which is aligned with suspension cable 44.

Alternatively, the submersible RO cartridge tray 40 may be extended to depth from a barge or tanker ship as a floating "water factory" to supply military requirements, cruise ship water restocking needs, or for other applications.

Fig. 4 is a detail drawing an RO cartridge 50, showing one of its reverse osmosis modules 62 comprising a surface membrane 63, covering an interior porous portion 64, having a breather pipe 59 on its top side, and a drain pipe 61 for desalinated water on its bottom side. The hydrostatic pressure differential on each side of the membrane 63 drives reverse osmosis functions for desalinization. The salt water pressure at 300 meters+ forces the desalination process through the surface membrane 63 since the interior portion of the module 62 is porous and vented to atmospheric pressure at the ocean surface. Desalinated water collects within the module 62 and flows out through drain pipe 61 .

As shown in Figs. 5 and 6, which are end views of the tray 40 shown in Figs. 2 and 3, each of the cartridges 50 containing the RO membrane modules (62) fits into a rectangular receptacle 41 in the tray 40, forming a grid-like arrangement. Upon full insertion of each RO cartridge 50 into the receptacle 41 , the RO cartridge pipe interconnections 89,59 to the breather pipe and 61 ,57 to the product water outlet pipe 52 (details shown in phantom) are completed. This design allows each cartridge 50 to interconnect with a slip connector with breather pipe 59, which leads to the ocean surface, and product water outlet with a slip connector to a collection manifold 57 located on the bottom of the tray 40 that pipes desalinated water to shore via outlet pipe 52. Figs. 7 and 8 are perspective views of the jib crane system 65 and hoist system 70, which is affixed to the wave energy converter 10. Periodic servicing of the cartridges 50, including cleaning of marine growth, repair, and membrane replacement, are critical to viable economic operation. To accomplish this task, the wave energy converter 10 structure has a built-in jib crane system 65, and a traveling hoist system 70, which allows horizontal movement over the full length and width of the RO cartridge tray structure 40. Control of the hoist movement to the horizontal location of the RO cartridge 50 to be installed, serviced or replaced, is accomplished with a control system similar to that used for automated warehousing, but applied to horizontal positioning rather than vertical positioning for conventional warehouse shelves. The jib crane 65 located topside is used for lifting components from a surface vessel to the deck platform 72 located on the top of the WEC 10 and for lifting the cartridge 50 to the deck platform 72. The jib crane 65. generally floor-mounted has a horizontal frame member supporting a moveable trolley, is fixed to a pillar. The jib crane may swing through an arc, to give additional lateral movement, or be fixed. The jib crane 65 shown in Fig. 6 includes a stationary crane-rail I- beam frame 74 fixed to a floor-mounted cane pillar 75 that is rotatable about a pivot point 76. The crane-rail I-beam frame 74 acts as an overhead monorail upon which the trolley 78 runs. The trolley 78 is suspended from the overhead crane rail I-beam frame member 74 by means of four rollers 79 that straddle the crane rail I-beam frame member 74. One or more of the rollers 79 are connected to a longitudinal motion trolley actuator, such as a servomotor, which, when actuated causes the trolley 78 to move in a longitudinal direction along the crane-rail I-beam frame member 74. Alternatively, a cable and pulley longitudinal motion actuator may be used to achieve longitudinal motion. Because the jib crane 65 I- beam frame 74 is moveable about the pivot point 76, RO cartridges 50 on a vessel deck alongside the WEC 10 are therefore accessible.

The hoist system 70 includes a moveable hoist I-beam frame 80 movable laterally the entire length of the tray 40 (not shown). The hoist rail I-beam frame 80 acts as an overhead monorail upon which a hoist trolley 82 runs perpendicular to the length of the WEC 10. The hoist trolley 82 is suspended from the overhead hoist rail I-beam frame 80 by means of four rollers 85 that straddle the hoist rail I-beam frame 80. One or more of the rollers 85 are connected to a lateral motion trolley actuator, such as a servomotor, which when actuated causes the trolley to move in a lateral direction along the I-beam frame 80. Alternatively, a cable and pulley lateral motion actuator may be used to achieve lateral motion. The hoist trolley 82 holds a lifting frame 83 with an electromagnet or mechanical latching mechanism that can be raised and lowered by a cable 86 and winch (not shown).

The lifting frame 83 can be attached to a cartridge 50, for the purpose of transporting it to any one of the receptacles 41 in the tray 40 (not shown).

Fig. 9 is a perspective view of the submerged tray structure 40 illustrating the lowering of a RO 50 cartridge into one of the receptacles 41 in the tray 40. The hoist system 70, once in position over the RO cartridge 50 to be serviced, extends the hoist cables 86, lowering the lifting frame 83 to the desired position for attachment to the RO cartridge 50. The lifting frame 83 is equipped with thrusters and video monitoring equipment to control fine movements for attachment of the cartridge 50 to the lifting frame 83. Once the RO 50 cartridge has been serviced, it is ready to be positioned and lowered to its receptacle 41 in the tray 40. The operator on the deck platform 72 of the wave energy converter 10 directs the hoist 70 into position and lowers the lifting frame 83 with the RO cartridge 50 for final positioning by using thrusters, and thus readies it for insertion its respective receptacle 41. As the RO cartridge 50 reaches the point of full insertion, the breather pipe (not shown) and the desalinated water pipe connectors (not shown) are mated, and the cartridge 50 is locked into its operating position.

Fig. 10 is a detail view of the lifting frame 83 with a mechanical latch or an electromagnet 88 that was energized to grip a cartridge 50, while Fig. 1 1 is a detail view of the lifting frame 83 suspended by cable 86 showing the electromagnet 88 de-energized or the latch mechanically unlatched to release the cartridge 50 The top surface of the cartridge 50 is provided with male alignment pins 90, 92. The lifting frame 83 has complementary female counterparts (not visible) to the male alignment pins 90, 92. The side of the RO cartridge 50 has a breather pipe coupling 89 for connection to the surface breather pipe.

Fig. 12 is a plan view of the RO cartridge 50 of Fig. 10 under the de-energized electromagnet 88. The top surface of the cartridge 50 is provided with male alignment pins 90, 92. When the lifting frame 83 with electromagnet 88 is lowered onto the top of the cartridge 50, its female alignment pins 94,96 contact and are mated with the male alignment pins 90, 92. This ensures proper placement of the lifting frame 83, whereby it assumes an exact position for proper engagement. The top surface of each receptacle 41 in the tray 40 is provided with one or more manifold couplings 98. When the lifting frame 83 with electromagnet 88 holding the cartridge 50 is lowered, the desalinated water pipe coupling 100 is eased into contact with the manifold coupling 98. The side of the cartridge 50 has a breather pipe coupling 89 which is connected to the surface breather pipe. Proper placement of the cartridge 50 in the tray 40 ensures that the breather pipe coupling 89 is properly connected to the surface breather pipe and that the outlet pipe 52 can receive the desalinated water from the cartridges 50.

Fig. 13 shows an alternate embodiment of the present invention, wherein a desalination plant platform is positioned in the ocean at depth below the ocean surface and is held in position by cables providing tension legs. The desalination plant is a standalone stationary RO plant with subsurface storage capability. A buoyant tray structure 101 is held by cables 102, 104, 106, 108, below the water surface 110 and anchored to the ocean floor by anchors 112, 114, 116, 118. The tray structure 101 contains a number of reverse osmosis (RO) cartridges 50 that desalinate seawater and collect desalinated water that can be accessed by tanker ships designed to transport liquids in bulk.

Cables 102, 104, 106, 108, connect gravity anchors 112, 114, 116, 118 to one or more winches 120, 122, 124, 126 on the tray structure 101 , such that the structure=s positive buoyancy keeps the anchoring cables (tension legs 102, 104, 106, 108) taut. Releasing the winched anchoring cables 102, 104, 106, 108 allows the entire tray structure 101 to surface for servicing. For this embodiment, the breather pipe 128 from the RO cartridges rises to a buoy 130 on the ocean surface 110. The desalinated water travels through outlets 134, 136 and is collected in subsurface bladders 138, 140, which have pipes 142, 144 to the buoy 130 for evacuation of the desalinated water, as needed. Desalinated water is evacuated by an electric submersible pumps 145,146 disposed within each subsurface bladder 138,140, with the electric power transmitted by power cables 147,148 terminating at the buoy 130. A tanker ship connects its power source to the buoy 130, along with its water collection pipe (not shown). Water pumping to the tanker ship occurs when electric power is sent to the bladder pumps 145,146.

Fig. 14 is a perspective view of yet another alternate embodiment of the present invention, wherein energy for pumping desalinated water to shore is generated by a photovoltaic system 150 disposed on the ocean surface. The photovoltaic system 150 comprises an array of solar photovoltaic cells 155 supported by a platform 156. The yawing feature of the platform 156 allows the solar photovoltaic array 155 to be oriented (yawed) to optimum solar exposure. The same tray support 40 for the desalination plant 20 shown in Fig. 1 is suspended by cables 42,44,46,48, with breather tube 59 venting the RO cartridges 50, and with power delivered to the pumps 60 through power cable 55, and with servicing of the RO cartridges 50 performed using the same system. However, since photovoltaic power is generated only during daylight hours and the desalination process is continuous, the desalinated water produced flows out pipe 157 and is collected in a storage tank 158, for delivery to shore through pipeline 160 when photovoltaic power resumes. Such a system 150 is applicable to areas where there is not sufficient wave action to provide the power necessary for pumping the desalinated water to shore.

Operation of the System

For initial deployment of the wave energy converter 10 and the tray structure 40 to its operating site, the tray suspension cables 42, 44, 46, 48 are retracted until the top of the tray 40 contacts the bottom of the wave energy converter 10. Once in operating position, and with the wave energy converter 10 tethers anchored, the tray 40 is lowered to its operating depth. This process is reversed when the wave energy converter 10 needs to be returned to the shipyard for servicing.

A key feature of the wave energy converter 10 is its ability to yaw to optimize energy capture for seasonal and other effects on wave direction. Since the tray 40 is suspended below the wave energy converter 10, it will yaw in tandem with the wave energy converter 10. The electric power cable 55 from the wave energy converter 10 and the outlet pipe 52 from the RO cartridge 50 tray 40 exit to the ocean floor through the center of the tray 40, thereby providing a pivot point for yawing the entire assembly, both the wave energy converter 10 on the surface and the suspended tray structure 40 submerged at depth.

Being able to carry out regular maintenance and repair activities in normal sea-state conditions insures that O&M (Operations & Maintenance) costs are predictable, and, if a problem arises, it can be rectified in a timely manner. This requires personnel to be able to access and safely carry out operational activities on-board. Personnel transfer is accomplished by service boat or helicopter.

The ease of deployment of the system and the reduced installation costs are derived from being able to tow the wave energy converter 10 with the desalination plant 20 to a site and use gravity anchors for mooring, thereby avoiding ocean-floor-mounted structures as required by some wave devices and desalination plants. Redundancy is built into the desalination subsystems to gain high availability and to reduce the chance of a failure, which would result in a catastrophic loss.

Claims

1. An apparatus comprising:

a wave energy conversion device for converting wave energy from wave motion on a surface of an ocean to a power output, said device being 5 positioned on an ocean surface;

a desalination plant suspended under the wave energy conversion device

and positioned in the ocean at a depth below the surface of the ocean, the desalination plant having a tray structure holding a plurality of reverse osmosis cartridges and pumps;

o a means for supplying power from the wave energy conversion device to the pump for the desalination plant for pumping and transporting desalinated water; and

an outlet pipe for delivering desalinated water from the desalination plant to a destination.

5 2. The apparatus of claim 1 wherein the reverse osmosis cartridges installed in the tray structure use saltwater hydrostatic pressure at depth to effect desalinating ocean water.

3. The apparatus of claim 2 wherein the reverse osmosis cartridges have a plurality of modules, each having a surface membrane and an interior porous portion, and which further comprises a breather pipe connecting the interior porous portion of each module in0 the reverse osmosis cartridges to the surface of the ocean, the breather pipe providing atmospheric pressure to vent the interior portion of each module, causing saltwater hydrostatic pressure on the surface membrane of each module to drive reverse osmosis processes, yielding desalinated water that drains from the module.

4. The apparatus of claim 1 wherein the power output is selected from the group consisting of electric power and hydraulic power.

5. The apparatus of claim 1 which further comprises means for suspending the tray holding the desalination plant in a manner permitting the tray to yaw in tandem with the wave energy conversion device.

6. The apparatus of claim 1 which further comprises a system for removing the reverse osmosis cartridges from the tray structure, bringing the cartridges to the surface for servicing, and returning the cartridges to the tray for reinstallation.

7. An apparatus using hydrostatic pressure at depth to desalinate ocean water, the apparatus comprising:

a buoyant desalination plant held by a plurality of cables, a first end of each cable being affixed to a winch on the desalination plant and the second end of each cable being anchored to an ocean floor, the desalination plant positioned in an ocean at a depth below a surface of an ocean, the desalination plant having a tray structure holding a plurality of reverse osmosis cartridges, wherein the reverse osmosis cartridges have a plurality of modules, each having a surface membrane and an interior porous portion, and which further comprises a breather pipe connecting the interior porous portion of each module in the reverse osmosis cartridges to a buoy at the surface of the ocean, the breather pipe providing atmospheric pressure to vent the interior porous portion of each module, causing saltwater hydrostatic pressure on the surface membrane of each module to drive reverse osmosis processes, yielding desalinated water that drains from the module; at least one outlet pipe for transporting desalinated water from the desalination plant to one or more subsurface bladders; and

a submersible electric pump disposed inside each of said bladders, the pump connected to the buoy by means of a power cable;

collection of desalinated water from the subsurface bladders being facilitated by means of a vessel with tankage for holding water, the vessel having means to attach to the buoy and electric power to actuate the bladder pumps to pump desalinated water to the tankage of the vessel.

8. The apparatus of claim 7 which further comprises one or more pipes connecting the bladders to the buoy at the surface of the ocean for recovery of the desalinated water.

9. The apparatus of claim 7 which further comprises a system for bringing the tray structure to the surface of the ocean for servicing, removing the reverse osmosis cartridges from the tray, and returning the cartridges to the tray for reinstallation.

10. The apparatus of claim 9 wherein the system for bringing the buoyant tray structure to the surface comprises means for releasing the plurality of cables until the tray structure rises to the surface.

1 1 . An apparatus comprising:

a photovoltaic system for generating power, said system being located on an ocean surface;

a desalination plant suspended under the photovoltaic system and positioned in the ocean at a depth below the surface of the ocean, the desalination plant having a tray structure holding a plurality of reverse osmosis cartridges and pumps; means for supplying power from the photovoltaic system to the pump on the desalination plant for pumping out and transporting desalinated water; and an outlet pipe for delivering desalinated water from the desalination plant to a destination.

12. The apparatus of claim 9 wherein the reverse osmosis cartridges installed in the tray structure use saltwater hydrostatic pressure at depth to effect desalinating water.

13. The apparatus of claim 12 wherein the reverse osmosis cartridges have a plurality of modules, each having a surface membrane and an interior porous portion, and which further comprises a breather pipe connecting the interior portion of each module in the reverse osmosis cartridges to the surface of the ocean, the breather pipe providing atmospheric pressure to vent the interior porous portion of each module, causing saltwater hydrostatic pressure on the surface membrane of each module to drive reverse osmosis processes, yielding desalinated water that drains from the module.

14. The apparatus of claim 9 which further comprises means for suspending the tray structure holding the desalination plant in a manner permitting the tray structure to yaw in tandem with the photovoltaic system.

15. The apparatus of claim 9 which further comprises a system for removing the reverse osmosis cartridges from the tray, bringing the cartridges to the surface for servicing, and returning the cartridges to the tray for reinstallation.

16. The apparatus of claim 9 which further comprises a storage tank for collecting and holding desalinated water when the photovoltaic system is not generating power for pumping the desalinated water to a destination.