GB2571691A

GB2571691A - Water desalination

Info

Publication number: GB2571691A
Application number: GB1909592.6A
Authority: GB
Inventors: King Lee
Original assignee: Hydro Wind Energy Ltd
Current assignee: Hydro Wind Energy Ltd
Priority date: 2019-07-03
Filing date: 2019-07-03
Publication date: 2019-09-04
Anticipated expiration: 2039-07-03
Also published as: GB2571691B; GB201909592D0

Abstract

A water desalination system 100 using wind energy and subsea pressure, comprises a buoy 102 disposed on a surface 106 of a water body 104; a first pulley wheel 108 disposed on the buoy; a pressure vessel 110 submerged in the water body, the pressure vessel having air 112, an inlet valve 114, an outlet valve 116, and a valve control mechanism operably connected with the inlet valve and the outlet valve and one or more reverse osmosis membranes 118; a second pulley wheel 122 disposed on the pressure vessel; one or more sails 126 disposed above the water body; a sail control mechanism 128 engaged with the one or more sails and a tether 130 connecting the second pulley wheel with the one or more sails, through the first pulley wheel. The tether is configured to convert the motion of the sail(s) into vertical motion of the pressure vessel using the first and second pulley wheel. The sail may be a selected from a group of a kite and an extent of fabric. The tether may be a nylon rope, wire cable, chain or a carbon nanotube-based tether. A second aspect relates to a method for desalination of water.

Description

Α SYSTEM AND A METHOD FOR DESALINATION OF WATER OF A WATER BODY, USING WIND ENERGY AND SUBSEA PRESSURE

TECHNICAL FIELD [001] The present disclosure, generally, relates to water purification and more particularly relates to a system and a method for desalination of water of a water body, using wind energy and subsea pressure.

BACKGROUND [002] The global population is expected to reach 8 to 9 billion by 2050, with 70 percent of people concentrated in cities and slums. This will lead to increased pressure on local water resources, stemming from greater withdrawals and pollution. Globally, it will lead to increased water withdrawals for food, energy and industrial production. An already competitive water landscape will become even more so. Usage will be stretched to the limit, and tensions will arise between countries that depend on a shared source of water.

[003] 1.5 billion people worldwide live in areas plagued by water scarcity, with twothirds of the world’s population living in water-stressed regions. 800 million people do not have access to clean water and almost 2.5 billion do not have access to adequate sanitation. 8.5 million people die annually from the consequences of water-related diseases. Viable and cost effective solutions are required to supply freshwater in the face of increasing water scarcity and escalating global demand. The urgent need to secure additional water supply sources sustainably and globally while simultaneously avoiding tradeoffs on land usage, geopolitical considerations and environmental impact.

[004] Conventional desalination technologies such as reverse osmosis and thermal desalination which are capital and energy intensive with significant environmental impact. The largest cost component in conventional reverse osmosis desalination plants is the energy input required to pressurize seawater through a reverse osmosis membrane at between 5500 kPa to 7000 kPa. Energy is the largest single expense for desalination plants in general, accounting for over 60% of the total costs of desalinating seawater into potable fresh water.

-1[005] Therefore, there is a need in the art for an efficient, sustainable, renewable and cost-effective desalination system, which ameliorates all or some of the deficiencies of the prior art or at least provides a viable alternative.

SUMMARY [006] According to a first aspect of the present disclosure, there is provided a water desalination system, using wind energy and subsea pressure, the system comprises a buoy disposed on a surface of a water body, a first pulley wheel disposed on the buoy, a pressure vessel submerged in the water body, the pressure vessel having air, an inlet valve, an outlet valve, a valve control mechanism operably connected with the inlet valve and the outlet valve and one or more reverse osmosis membranes, a second pulley wheel disposed on the pressure vessel, one or more sails disposed above the water body, sail control mechanism engaged with the one or more sails and a tether connecting the second pulley wheel with the one or more sails, through the first pulley wheel. Further, the buoy is configured to float on the surface of the water body. Further, the valve control mechanism is configured to open the inlet valve to allow water of the water body to enter into the pressure vessel through the one or more reverse osmosis membranes, when the pressure vessel reaches a first operational depth. Further, the one or more sails is configured to pull and release the tether under influence of a wind. Further, the sail control mechanism is configured to control orientation of the one or more sails with respect to the wind. Further, the tether is configured to convert the motion of the one or more sails into vertical motion of the pressure vessel using the first pulley wheel and the second pulley wheel.

[007] In accordance with an embodiment of the present disclosure, the valve control mechanism is further configured to open the outlet valve to allow the desalinated water inside the pressure vessel to be pumped out of the pressure vessel, when the pressure vessel reaches a second operational depth.

[008] In accordance with an embodiment of the present disclosure the one or more sails are selected from a group consisting of a kite and an extent of a fabric.

[009] In accordance with an embodiment of the present disclosure the tether is one of a group comprising nylon rope, nylon webbing, wire cable, chain and carbon nano-tube based tether.

-3[0010] According to another aspect of the invention, there is provided a method for desalination of water of a water body, using wind energy and subsea pressure, the method comprising the steps of disposing a buoy on a surface of a water body, such that the buoy floats on the surface of the water body and disposing a first pulley wheel on the buoy, disposing a second pulley wheel on a pressure vessel, the pressure vessel having an inlet valve and outlet valve, disposing one or more sails above the water body, connecting the one or more sails with the second pulley wheel through the first pulley wheel using a tether, submerging the pressure vessel having air, to a first operational depth in the water body, opening the inlet valve to allow water of the water body to enter into the pressure vessel through one or more reverse osmosis membranes, when the pressure vessel reaches the first operational depth and converting a motion of the one or more sails into a vertical motion of the pressure vessel, with the help of the tether, the first pulley wheel and the second pulley wheel.

[0011] In accordance with an embodiment of the present invention, the method further comprises a step of opening the outlet valve to allow desalinated water inside the pressure vessel to be pumped out of the pressure vessel, when the pressure vessel reaches a second operational depth.

BRIEF DESCRIPTION OF THE DRAWINGS [0012] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may have been referred by embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments.

[0013] These and other features, benefits, and advantages of the present disclosure will become apparent by reference to the following text figure, with like reference numbers referring to like structures across the views, wherein:

[0014] Fig. 1A illustrates a first stage of a system for desalination of water of a water body, in accordance with an embodiment of the present invention;

[0015] Fig. IB illustrates the first stage of a system for desalination of water of a water body, in accordance with another embodiment of the present invention;

-4[0016] Fig. 2A illustrates a second stage of the system for desalination of the water of the water body, in accordance with an embodiment of the present invention;

[0017] Fig. 2B illustrates the second stage of the system for desalination of the water of the water body, in accordance with another embodiment of the present invention; and [0018] Fig. 3 illustrates a method for desalination of water of a water body, using wind energy and subsea pressure, in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION [0019] Detailed embodiments of the present disclosure are described herein; however, it is to be understood that disclosed embodiments are merely exemplary of the present disclosure, which may be embodied in various alternative forms. Specific process details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present disclosure in any appropriate process.

[0020] The terms used herein are for the purpose of describing exemplary embodiments only and are not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” or “comprising,” when used in this specification, do not preclude the presence or addition of one or more components, steps, operations, and/or elements other than a mentioned component, step, operation, and/or element.

[0021] The present disclosure may be embodied in a variety of different forms and, example embodiments are provided merely to be illustrative. Among other things, for example, the present disclosure may be embodied as methods, devices, components, or systems. Accordingly, embodiments may, for example, take the form of hardware, software, firmware or any combination thereof (other than software per se). Although the exemplary embodiments will be generally described in the context of software modules running in a mobile device, those skilled in the art will recognize that the present disclosure also can be implemented in conjunction with other program modules for other types of computing environments. For example, execution of the program modules may occur locally in a stand-alone manner or remotely in a client/server manner.

[0022] The embodiments of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, which form a part hereof, and

-5which show, by way of illustration, specific example embodiments. The following detailed description is not intended to be taken in a limiting sense.

[0023] Figure 1A illustrates a first stage of a system 100 for desalination of water of a water body 104, in accordance with an embodiment of the present invention. In a preferred embodiment, a part of the system 100 is installed beneath the surface 106 of the water body 104 and a part of the system 100 is floating along the surface 106. The water body 104 may embody a sea, an ocean, or the like. Referring to figure 1A, system 100 includes a buoy 102 disposed on a surface 106 of a water body 104. The buoy 102 can also be referred to as a floating barge or a floating structure. The buoy 102 is disposed on the surface 106 of the water body 104, such that the buoy 102 moves in a vertical direction on the surface 106 of the water body 104. The buoy 102 moves in tandem with a motion of the plurality of sea waves. Also, a first pulley wheel 108 is disposed on the buoy 102.

[0024] Further, the system 100 includes a pressure vessel 110 submerged in the water body 104. In a preferred embodiment, the pressure vessel 110 is made of steel with a mass of 603,400 kilograms with a volume of approximately 502 cubic meters. The pressure vessel 110 further includes an inlet valve 114, an outlet valve 116, air 112 and one or more reverse osmosis membranes 118. Additionally, the pressure vessel 110 comprises a valve control mechanism 124 (not shown).

[0025] Reverse osmosis (RO) is a water purification technology that uses a semipermeable membrane (reverse osmosis membrane) to remove ions, molecules, and larger particles from water. In the reverse osmosis, an applied pressure is used to overcome an osmotic pressure, a colligative property that is driven by chemical potential differences of a solvent. The reverse osmosis can remove many types of dissolved and suspended species from the water, including bacteria, and is used in both industrial processes and the production of potable water. The result is that a solute is retained on a pressurized side of the reverse osmosis membrane and the pure solvent is allowed to pass to other side. Reverse osmosis is most commonly known for its use in drinking water purification from seawater, removing salt and other effluent materials from the water molecules.

[0026] Further, a second pulley wheel 122 is disposed on the pressure vessel 110. Also, the system 100 includes one or more sails 126 disposed above the water body 104. In accordance with an embodiment of the present invention, the one or more sails 126 are, for example, a kite, adapted to be flown at high altitudes. The one or more sails 126

-6comprise a cover consisting of a sheet of material, optionally affixed to structural components such as spurs, struts, or similar parts. Optionally the cover is made of a polymer material, such as polypropylene, nylon, cotton, carbon laminated or another suitable material.

[0027] Further, sail control mechanism 128 engaged with the one or more sails 126. Also, a tether 130 connects the second pulley wheel 122 with the one or more sails 126, through the first pulley wheel 108. The tether 130 is one of a group comprising nylon rope, nylon webbing, wire cable, chain, and carbon nano-tube based tether. The first pulley wheel 108 guides the tether 130 to the second pulley wheel 122 on the pressure vessel 110, and secures the pressure vessel 110 in place in a submerged position. Optionally, a brake is provided in the first pulley wheel 108. Optionally, a block and tackle system, or any other kind of mechanical advantage or gearing system can be used instead of the first pulley wheel 108 and the second pulley wheel 122.

[0028] In accordance with an embodiment of the present invention, the buoy 102 is configured to float on the surface 106 of the water body 104. And the pressure vessel 110 is configured to be submerged in the water body 106. As the pressure vessel 110 is negatively buoyant, the pressure vessel 110 configured to sink to a first operational depth DI under the gravitational force. To prevent any further sinking of the pressure vessel 110, a tension in the tether is adjusted to overcome a downward force on the pressure vessel 110. Or the brake can be applied to lock the movement of the first pulley wheel (108).

[0029] Further, the valve control mechanism 124 is configured to operate (preferably through an externally provided computing device) opening and closing of the inlet valve 114 and the outlet valve 116. When the pressure vessel 110 reaches the first operational depth DI, the valve control mechanism 124 is configured to open the inlet valve 114 to allow the saline water of the water body 104 to enter the pressure vessel 110 under the influence of a subsea pressure, through the one or more reverse osmosis membranes 118. When the pressure vessel 110 is filled to a predetermined level the inlet valve 114 is configured to be closed.

[0030] In accordance with an embodiment of the present invention, the one or more sails 126 are configured to pull and release the tether 130 under influence of a wind. At the first stage, one or more sails 126 are also configured to fly at a first predetermined altitude. This is done so as to keep the pressure vessel 110 steady, at the first operational depth DI. The sail control mechanism 128 is configured control the orientation of the

-7 one or more sails 126 with respect to wind. This helps to negotiate any changes in a direction of the wind flow and/or a speed of the wind. Therefore, the sail control mechanism 128 along with a certain flight maneuvers can be used to maintain the one or more sails 126 at the altitude indefinitely, until it is required for lifting of the pressure vessel 110.

[0031] In accordance with an embodiment of the present invention, the one or more sails 126 and the sail control mechanism 128 are further configured to adjust tension in the tether 130 in order to keep the pressure vessel steady at the first operational depth DI. Further, the tether 130 is configured to convert the motion of the one or more sails 126 into vertical motion of the pressure vessel 110 using the first pulley wheel 108 and the second pulley wheel 122.

[0032] Figure IB illustrates the first stage of the system 100 for desalination of the water of the water body 104, in accordance with another embodiment of the present invention. As shown in figure IB, the one or more sails 126 are extents of a fabric (such as, but not limited to, a canvas) by means of which wind is used to propel a watercraft 136, like boat or a ship, on the surface 106 of the water body 104. The one or more sails 126 under the influence of the wind causes the movement of the watercraft 136 which further causes a movement in the tether 130. The tether 130 is configured to convert the motion of the watercraft 136 into the vertical motion of the pressure vessel 110. The sail control mechanism 128 is configured to control the orientation of the one or more sails 126 and thereby maintaining the movement of the watercraft 126 within a predetermined range. This is done to ensure that the pressure vessel 110 is constantly maintained at the first operational depth DI during the first stage, with the help of the tether 130, the first pulley wheel 108 and the second pulley wheel 122.

[0033] For example, at the first operational depth DI of 600m, the pressure vessel 110 contains approximately 502 cubic meters (m³) of the air 112 at a pressure of about 101.3 kilo Pascal (kPa). The floating buoy 102 holds the pressure vessel 110 in place once submerged to the first operational depth DI, with the help of the tether 130, the first pulley wheel 108 and the second pulley wheel 122. The total combined mass of the pressure vessel 110 with the air 112 inside is given by equation 1.

M_T = 628 + 603400 = 604028 kg (1)

Total downward force is given by equation 2.

F_T = 604028 *9.81 = 5925.5 kilo Newton (kN) (2)

-8[0034] The water density is considered to be 1025 kg/m³, temperature 5°C and air 112 density 1.25 kg/m³ at 101.3 kPa. The next step is to calculate the buoyancy force acting on the pressure vessel 110 once submerged. Fb is the buoyancy force acting upwards on the pressure vessel 110, V is the volume submerged, p is the density of water of the water body 104, and g is the acceleration due to gravity. The buoyancy force is given by equation 3.

F_b = Vpg = (502.65 + 86.2) * 1025 * 9.81 = 5921 kN (3) [0035] Deducting the weight of the pressure vessel 110 against the buoyancy force; the total combined downward force is given by equation 4.

F = 5925.5 - 5921 = 4.5 kN (4) [0036] Hence, the state of the system once submerged fully in water is negatively buoyant by 4.5 kN or around 458 kg. The pressure vessel 110 once submerged in water will sink due to gravity by a force equivalent to 4.5 kN.

[0037] The inlet valve 114 at depth of around 600m, is opened and a pressure difference is created between the air 112 inside at 101.3 kPa and the hydrostatic water pressure at 600m (6132 kPa). The constant pressure difference causes the water of the water body 106 to filter through the reverse osmosis membranes 118 creating fresh potable desalinated water 132. The transient kinetic water flow into the pressure vessel 110 gradually compresses the air 112 inside to a small pocket of volume 46m³ and the remaining volume of 456.65m³ is filled with potable desalinated water 132. Almost all (around 95% to 99%) of dissolved salts are filtered and the residual impurities are discharged through the reject stream 134.

[0038] Once the pressure vessel 110 is filled with water, the buoyancy of the system 100 changes. The mass of air 112 inside the pressure vessel 110 is constant at 628.31 kg and the mass of the pressure vessel 110 is 603,400 kg (86.2m³ of steel) but the fresh desalinated water 132 with a lower density than water of the water body 104 displaces 456.65m³ of air 112. Hence, the total combined mass of the pressure vessel 110 with potable desalinated water 132 inside is given by equation 5.

M_T = 628.31 + 603400 + (456.65 * 1000) = 10405254.22 * 9.81 = 10405 kN (5) [0039] Total buoyancy force can be calculated from equation 6.

F_b = Vpg = (502.65 + 86.2) * 1025 = 603571.25 * 9.81 = 5921 kN (6) [0040] Deducting the weight of the pressure vessel 110 against the upward buoyancy force; the total combined downward force is given by equation 7.

-9F_T = 10405 - 5921 = 4484 kN (7) [0041] Hence, the state of the system once filled with desalinated water 132 is negatively buoyant by 4,484 kN or around 457 metric tons.

[0042] Figure 2A illustrates a second stage of the system for desalination of the water of the water body 104, in accordance with an embodiment of the present invention. As shown in the figure 2A, the pressure vessel 110 is filled with the desalinated water 132. At this stage, the pressure vessel 110 is configured to be lifted closer to the surface 106 of the water body 104 to a second operational depth D2. An energy input is required to lift the pressure vessel 110 from the first operational depth DI to the second operational depth D2. The one or more sails 126 are configured to use the wind to provide lifting force and lifting power. In accordance with an embodiment of the present invention, the one or more sails 126 include the kite capable of flying at high altitudes. The one or more sails 126 take advantage of increased wind speed with altitude due to an atmospheric boundary layer by flying downwind or by following a suitable flight pattern that can increase the apparent wind speed significantly compared to the true wind speed. As force is related to velocity squared, this relationship is beneficial for using the kite power for generating mechanical lift.

[0043] The one or more sails 126 are also configured to use the wind power to return to the first predetermined altitude. With the sail control mechanism 128 controlling and maintaining the proper orientation of the one or more sails 126, movement in any direction can be achieved relative to the direction of the wind by using the principles of aerodynamic lift and drag, and the reeling in of the one or more sails 126 thus require very little energy.

[0044] In accordance with an embodiment of the present invention, when the one or more sails 126 come under the influence of the wind, the one or more sails 126 are pushed to a direction of the wind, thereby, reaching a second predetermined altitude and thereby pulling the tether 130. Here, the second predetermined altitude is higher as compared to the first predetermined altitude. The tether 130 rotates the first pulley wheel 108 and the second pulley wheel 122 to convert the motion of the one or more sails 126 to the vertical motion of the pressure vessel 110. The pressure vessel 110 reaches the second operational depth D2. Also the sail control mechanism 128 is configured to control the orientation of the one or more sails to negotiate any changes in wind flow

-10direction and/or speed such that there are no problems during the lifting or submerging of the pressure vessel 110.

[0045] For example, a kite can operate at altitudes of 100m to 600m where considerably stronger, persistent and more stable winds prevail. At an altitude of 100m, an average wind speed is between 30% and 60% higher than the wind speed at an altitude of 10m, due to the absence of surface skin friction from the surfaces of earth and the water body 104. At 600m there is two to three times the wind velocity compared to ground or sea level. Wind power is a measure of the energy available in the wind. It is a function of the cube (third power) of the wind speed. If the wind speed is doubled, power in the wind increases by a factor of eight. This relationship means that small differences in wind speed lead to large differences in power. This indicates a very low variability of wind power, from around 10 W/m² in a light breeze up to 41,000 W/m² in a hurricane blowing at 40 m/s (144 km/h).

[0046] The standard power law for the atmospheric boundary layer (up to 1000m) was used to determine the wind speed is given by equation 8.

u = u_T a (8) a is assumed to be 1/7.

[0047] Basic force coefficient theory, used to investigate the force generated by the kite is given by the equation 9.

F=(£)pAC_ru² (9) where, p = density

A = Surface Area of kite u = velocity of the wind C_r= Coefficient [0048] Surface area of the kite suggested should be within 10% of that required to generate the predetermined forces. To allow a greater range of options, a mechanical leverage ratio of 10:1 is used (i.e. the kite moves 10m of the tether 130 for every lm lift of the pressure vessel 110 using the tether 130, the first pulley 108 and the second pulley 122. A mechanical efficiency of 90% is assumed).

[0049] With a true wind speed of 15 knots (7.71 m/s) at 10m above sea level, the lift and drag coefficient are assumed to be 0.8 and 0.13 respectively and the force coefficient is calculated to be 0.81. In the first instance the kite is navigated dynamically using the

-11 sail control mechanism 128 by performing flying manoeuvres such as the figure-of-eight. This increases the apparent wind speed significantly compared to the true wind speed. In that way the wind speed at the kite is increased and the lifting force is raised accordingly. A free flying kite flying in wind speeds of 15 knots (7.71 m/s) lifts the pressure vessel 110 of 400m² within 19 minutes. A kite of 800m² lifts the 460 tonnes mass by 600m in 15 minutes. In a scenario of not flying the kite dynamically (i.e. as in the figure-of-eight), the easiest and most inefficient form of wind generated force is for the kite to be blown directly downwind using pure drag. The control requirements are minimal and changes of direction are not required. Assuming the lift and drag coefficients are the same and the force coefficient as 0.81 then 5000m² of kite area at 15 knots lifts the pressure vessel 110 in 20 minutes.

[0050] Ultimately wind speeds will dictate the lifting force and speed but it can be assumed that energy captured can be optimized by either flying the kite at the altitude with the strongest wind or adapting the kite area to accommodate changes in wind speed. [0051] As shown in figure 2A, once the pressure vessel 110 reaches the second operational depth D2, the valve control mechanism 124 is configured to open the outlet valve 116 to allow a user to collect the desalinated potable water 132. Once the desalinated water 132 is pumped out of the pressure vessel 110, the outlet valve 116 is configured to be closed by the valve control mechanism 124.

[0052] After the desalinated water 132 is pumped out from the outlet valve 116, the pressure vessel 110 is closed with air 112 at atmospheric pressure and dropped back into the water body 104 (negatively buoyant by 458 kg once fully submerged). The pressure vessel 110 is allowed to sink back to the first operational depth DI dangling from the floating buoy 102. Having reached the second predetermined altitude, the one or more sails 126 is flown statically, out of the wind and in a low force position to start a retraction phase. The one or more sails 126 are reeled in to the first predetermined altitude from where the mechanical lift phase can re-start again.

[0053] Figure 2B illustrates the second stage of the system for desalination of the water of the water body, in accordance with another embodiment of the present invention. In figure 2B, the one or more sails 126 disposed on the watercraft 136 are used to harness wind energy. In accordance with an embodiment of the present invention, when the one or more sails 126 come under the influence of the wind, the one or more sails 126 are pushed in a direction of the wind, thereby, imparting motion to the

-12 watercraft 136. The water craft 136 being connected with one end of the tether 130, pulls the tether 130 in the direction of the watercraft 136. The tether 130 rotates the first pulley wheel 108 and the second pulley wheel 122 to convert the motion of the watercraft 136 to the vertical motion of the pressure vessel 110. The pressure vessel 110 reaches the second operational depth D2. Also the sail control mechanism 128 is configured to control the orientation of the one or more sails 126 to negotiate any changes in wind flow direction and/or speed such that there are no problems during the lifting or submerging of the pressure vessel 110.

[0054] Once the pressure vessel 110 reaches the second operation depth D2, the valve control mechanism 124 is configured to open the outlet valve 116, in accordance with an embodiment of the present invention. This allows a user to collect the desalinated potable water 132. Once the desalinated water 132 is pumped out of the pressure vessel 110, the outlet valve 116 is configured to be closed by the valve control mechanism.

[0055] After the desalinated water 132 is pumped out from the outlet valve 116, the pressure vessel 110 is closed with air 112 at atmospheric pressure and dropped back into the water body 104 (negatively buoyant by 458 kg once fully submerged). The pressure vessel 110 is allowed to sink back to the first operational depth DI dangling from the floating buoy 102. The water craft 126, with the help of the one or more sails 126, is taken to the predetermined position ready to start the first stage again.

[0056] Figure 3 illustrates a method 300 for desalination of water of a water body 104, using wind energy and subsea pressure. The method 300 begins at a step 310 of disposing the buoy 102 on the surface 106 of the water body 104, such that the buoy 102 floats on the surface 106 of the water body 104 and disposing the first pulley wheel 108 on the buoy 102. At step 320, the second pulley wheel 122 is disposed on the pressure vessel 110. At step 330 the one or more sails 126 are disposed above the water body 104. At step 340, the one or more sails 126 are connected with the second pulley wheel 122 through the first pulley wheel 108 using a tether 130.

[0057] At step 350, the pressure vessel 110 having the air 112, is submerged to the first operational depth DI in the water body. The pressure vessel 110 is positioned in the water body 104 with the help of the tether 130, the first pulley 108 and the second pulley 122. The depth of the pressure vessel 110 is maintained using the one or more sails 126 connected to tether 130. The one or more sails 126 using the wind, keep adjusting the

-13 tension in the tether 130 to maintain the pressure vessel 110 at the first operational depth DI.

[0058] At step 360, the inlet valve 114 is opened to allow water of the water body 104 to enter into the pressure vessel 110 through the one or more reverse osmosis membranes 118, when the pressure vessel 110 reaches the first operational depth DI. This floods the pressure vessel 110, resulting in compression of the air 112 inside the pressure vessel 110 to the small pocket of volume 46m³ and the remaining 456.65m³ is filled with fresh potable desalinated water 132.

[0059] At step 370, the motion of the one or more sails 126 is converted into the vertical motion of the pressure vessel 110, with the help of the tether 130, the first pulley wheel 108 and the second pulley wheel 122. The one or more sails 126 pushes the tether 130 in the direction of wind. The tether 130 rotates the first pulley wheel 108 and the second pulley 122 to move and lift the pressure vessel 110 to the second operational depth D2.

[0060] In one embodiment of the invention, the method 300 further comprises a step of opening the outlet valve 116 to allow the desalinated water 132 inside the pressure vessel 110 to be pumped out of the pressure vessel 110, when the pressure vessel 110 reaches close to the surface 106 of water body 104 at the second operational depth D2.

[0061] The embodiments of the system and the method offer a number of advantages. The desalination system 100 is based on combining subsea pressure in the form of hydro energy with the wind energy to obtain fresh and potable water from the saline water of the water body 104. The system 100 makes use of one or more reverse osmosis (RO) membranes to desalinate the water. In conventional desalination plant to make the saline water pass through the one or more RO membranes, a pressure of about 5500 kPa to 7000 kPa is required. And to pressurise saline sea water to such a level a huge energy input is required. Energy is the largest single expense for desalination plants, accounting for over 60% of the total costs of desalinating seawater into potable fresh water. The present invention provides a solution to this challenge.

[0062] The system 100 uses subsea pressure at depths of the water body 104 to desalinate seawater using a submerged pressure vessel 110 with attached reverse osmosis membranes 118. Subsea pressure is a form of energy density. As the energy potential of water under pressure increases with depth, power generation is proportional. Further, the present invention harnesses the wind energy to lift and/or submerge the pressure vessel 110 to the predetermined depth. As a result, the energy requirements of the whole

-14process are easily fulfilled in a simple, cheap, environmental friendly and highly efficient way as no fossil fuels are required for the operation of the system 100. The present invention is an effective way to tackle the water scarcity problem as it is possible to desalinate huge volumes of water of the water body 104 in a few minutes. So, the daylong operation of the system 100 will yield highly significant results. Moreover, the present invention is zero carbon emissions technology with the lowest capital cost to deploy.

[0063] The terms and descriptions used herein are set forth by way of illustration only and are not meant as limitations. Examples and limitations disclosed herein are intended to be not limiting in any manner, and modifications may be made without departing from the spirit of the present disclosure. Those skilled in the art will recognize that many variations are possible within the spirit and scope of the disclosure, and their equivalents, in which all terms are to be understood in their broadest possible sense unless otherwise indicated.

[0064] Various modifications to these embodiments are apparent to those skilled in the art from the description and the accompanying drawings. The principles associated with the various embodiments described herein may be applied to other embodiments. Therefore, the description is not intended to be limited to the embodiments shown along with the accompanying drawings but is to be providing broadest scope of consistent with the principles and the novel and inventive features disclosed or suggested herein. Accordingly, the disclosure is anticipated to hold on to all other such alternatives, modifications, and variations that fall within the scope of the present disclosure and appended claims.

Claims

1. A water desalination system (100) using wind energy and subsea pressure, the water desalination system (100) comprising:

a buoy (102) disposed on a surface (106) of a water body (104);

a first pulley wheel (108) disposed on the buoy (102);

a pressure vessel (110) submerged in the water body (104), the pressure vessel (110) having air (112), an inlet valve (114), an outlet valve (116), a valve control mechanism (124) operably connected with the inlet valve (114) and the outlet valve (116) and one or more reverse osmosis membranes (118);

a second pulley wheel (122) disposed on the pressure vessel (110);

one or more sails (126) disposed above the water body (104);

a sail control mechanism (128) engaged with the one or more sails (126); and a tether (130) connecting the second pulley wheel (122) with the one or more sails (126), through the first pulley wheel (108);

wherein the buoy (102) is configured to float on the surface (106) of the water body (104);

wherein the valve control mechanism (124) is configured to open the inlet valve (114) to allow water of the water body (104) to enter into the pressure vessel (110) through the one or more reverse osmosis membranes (118), when the pressure vessel (110) reaches a first operational depth;

wherein the one or more sails (126) are configured to pull and release the tether (130) under influence of a wind;

wherein the sail control mechanism (128) is configured to control orientation of the one or more sails (126) with respect to the wind;

wherein the tether (130) is configured to convert the motion of the one or more sails (126) into vertical motion of the pressure vessel (110) using the first pulley wheel (108) and the second pulley wheel (122).

2. The water desalination system (100) as claimed in claim 1, wherein the valve control mechanism (124) is further configured to open the outlet valve (116) to allow the desalinated water (132) inside the pressure vessel (110) to be pumped out of the pressure vessel (110), when the pressure vessel (110) reaches a second operational depth.

3. The water desalination system (100) as claimed in claim 1, wherein the one or more sails (126) is selected from a group consisting of a kite and an extent of a fabric.

4. The system (100) as claimed in claim 1, wherein the tether (130) is selected from a group comprising:

nylon rope;

nylon webbing;

wire cable;

chain; and carbon nano-tube based tether.

5. A method (300) for desalination of water of a water body (104), using wind energy and subsea pressure, the method (300) comprising the steps of:

disposing (310) a buoy (102) on a surface of a water body (104), such that the buoy (102) floats on the surface (106) of the water body (104) and disposing a first pulley wheel (108) on the buoy (102);

disposing (320) a second pulley wheel (122) on a pressure vessel (110), the pressure vessel (110) having an inlet valve (114) and outlet valve (116);

disposing (330) one or more sails (126) above the water body (104); connecting (340) the one or more sails (126) with the second pulley wheel (122) through the first pulley wheel (108) using a tether (130);

submerging (350) the pressure vessel (110) having air (112), to a first operational depth in the water body (104);

opening (360) the inlet valve (114) to allow water of the water body (104) to enter into the pressure vessel (110) through one or more reverse osmosis membranes (118), when the pressure vessel (110) reaches the first operational depth; and converting (370) a motion of the one or more sails (126) into a vertical motion of the pressure vessel (110), with the help of the tether (130), the first pulley wheel (108) and the second pulley wheel (122).

6. A method (300) as claimed in claim 5, further comprising the step of opening the outlet valve (116) to allow desalinated water (132) inside the pressure vessel (110) to be pumped out of the pressure vessel (110), when the pressure vessel (110) reaches a second operational depth.