WO2021038588A1 - Osmotic power generation system - Google Patents

Osmotic power generation system Download PDF

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Publication number
WO2021038588A1
WO2021038588A1 PCT/IN2020/050739 IN2020050739W WO2021038588A1 WO 2021038588 A1 WO2021038588 A1 WO 2021038588A1 IN 2020050739 W IN2020050739 W IN 2020050739W WO 2021038588 A1 WO2021038588 A1 WO 2021038588A1
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Prior art keywords
membrane
scalable
electrolyte
range
chamber
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PCT/IN2020/050739
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French (fr)
Inventor
Vishal V.R. NANDIGANA
Pramoda Kumar NAYAK
Sivarama Krishnan
Sharad Kumar Yadav
Aswathy GOPALAKRISHNAN
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INDIAN INSTITUTE OF TECHNOLOGY MADRAS (IIT Madras)
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Publication of WO2021038588A1 publication Critical patent/WO2021038588A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/02—Inorganic material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0039—Inorganic membrane manufacture
    • B01D67/0053—Inorganic membrane manufacture by inducing porosity into non porous precursor membranes
    • B01D67/006—Inorganic membrane manufacture by inducing porosity into non porous precursor membranes by elimination of segments of the precursor, e.g. nucleation-track membranes, lithography or laser methods
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/02—Inorganic material
    • B01D71/021—Carbon
    • B01D71/0211—Graphene or derivates thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/02—Inorganic material
    • B01D71/0215—Silicon carbide; Silicon nitride; Silicon oxycarbide
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03G—SPRING, WEIGHT, INERTIA OR LIKE MOTORS; MECHANICAL-POWER PRODUCING DEVICES OR MECHANISMS, NOT OTHERWISE PROVIDED FOR OR USING ENERGY SOURCES NOT OTHERWISE PROVIDED FOR
    • F03G7/00—Mechanical-power-producing mechanisms, not otherwise provided for or using energy sources not otherwise provided for
    • F03G7/005—Electro-chemical actuators; Actuators having a material for absorbing or desorbing gas, e.g. a metal hydride; Actuators using the difference in osmotic pressure between fluids; Actuators with elements stretchable when contacted with liquid rich in ions, with UV light, with a salt solution
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M14/00—Electrochemical current or voltage generators not provided for in groups H01M6/00 - H01M12/00; Manufacture thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/02—Details relating to pores or porosity of the membranes
    • B01D2325/0283—Pore size
    • B01D2325/02833—Pore size more than 10 and up to 100 nm
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/04—Characteristic thickness
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/30—Energy from the sea, e.g. using wave energy or salinity gradient

Definitions

  • the invention generally relates to renewable energy generation and in particular to an osmotic power generation system that uses a scalable porous membrane.
  • renewable energy is the need of the hour for the growing population.
  • the present renewable energy sources are solar, wind, and tidal energy. These sources of energy are discontinuous which may cause problem in power generation and storage. Generating power using salinity gradients was started in 2009 and companies in Denmark and Netherlands started the technology but not on commercial scale.
  • An osmotic power generator using saltwater and freshwater separated by an osmotic membrane may be used to generate electricity in abundance as seawater is available in large quantities and may also be reused.
  • the power generated is harvested, stored, and used in energy conversion devices like a fuel cell, water battery, and power generator.
  • the membranes used are made with large variety of materials to obtain satisfactory results.
  • the membranes are of organic, inorganic, biomimetic, polymeric, stimuli responsive, PH- responsive types.
  • the types of materials membranes include boron nitride and aramid nanofibers.
  • the batteries produced using the membrane are renewable and non- toxic, unlike conventional batteries.
  • the compositions and the method of preparation for the membranes vary for every membrane. The membranes are affected by the salinity, PH, concentration, temperature conditions in the osmotic power generation.
  • the patent EP3475567B1 discloses the process of osmotic power generation comprising an active membrane supported in housing for receiving electrolyte liquids from two chambers.
  • US20090250392A describes the method of power generation using semi-permeable porous and non-porous membranes in elevated osmotic pressure.
  • the patent US10233098B2 discusses the method of desalination of saltwater using a free-standing single layer nanoporous graphene membrane having a first planar side in contact with saltwater and opposing the second side from which desalinated water exists.
  • the patent application US20190224628A1 discloses a process of preparing porous graphene-based films having reduced graphene oxide with different zones of different porosity that are used in infiltration processes.
  • an osmotic power generator system includes a housing, a porous scalable membrane having a first surface and a second surface placed within the housing, a first chamber disposed on the first surface of the membrane and having a first electrode and a first electrolyte and a second chamber disposed on the second surface of the membrane and comprising a second electrode and a second electrolyte.
  • a load is connected between the first electrode and the second electrode.
  • the porous scalable membrane includes a first membrane that is selected from SiNx (Silicon nitride) or Cu (Copper) membrane and a monolayer graphene membrane is mounted on a surface of the first membrane.
  • the first membrane and the monolayer graphene membrane have one or more pores.
  • the system is configured to pass ions between the first and second surfaces of the porous membrane due to an osmotic gradient between the first and the second electrolytes to generate a difference in potential and an ionic current between the first and second electrodes.
  • a size of the pore in the monolayer membrane is in a range of 0.5mm to 2mm.
  • a pore density is in a range of 4 to 7 pores in the scalable membrane of dimension lcmxlcm.
  • a thickness of the scalable membrane is in a range 16 to 20 pm.
  • a thickness of the monolayer membrane is in a range 0.342 to 0.345 nm.
  • the first electrolyte is salt water or sea water.
  • the second electrolyte is fresh water or river water.
  • the power generated is in the range of 58 to 70 mW/mm 2 of pore area.
  • the pore area / a membrane area is in the range 0.025 to 0.88
  • FIG. 1 shows the schematic representation of osmotic power generation using salinity gradient.
  • FIG. 2A shows the porous membrane with multiple pores and an inter pore distance of l.
  • FIG 3A shows Graphene/ Copper sheet showing 1mm single and multiple holes formed using Femtosecond laser.
  • FIG. 3B illustrates Graphene/ Copper sheet showing 2mm single and multiple holes formed using Femtosecond laser.
  • FIG. 4A illustrates the Scanning Electron Microscopy showing commercially available Graphene/Copper membrane.
  • FIG. 4B illustrates the Raman spectroscopic analysis for graphene in copper membrane.
  • FIG. 5A illustrates the potassium concentration for a single 1 mm pore in a graphene on copper membrane of size 1 cm by 1 cm.
  • FIG. 5B illustrates the potential concentration for a single 1 mm pore in a graphene on copper membrane of size 1 cm by 1 cm.
  • FIG. 6A illustrates the power in a scalable porous membrane with pore area with a single pore.
  • FIG. 6B illustrates the power in a scalable porous membrane with pore area with 4 pores.
  • FIG. 6C illustrates the power in a scalable porous membrane with pore area with 7 pores.
  • FIG. 6D illustrates the individual (potassium and chlorine) and total current (I total) in a scalable porous membrane with pore area with a single pore.
  • the invention in its various embodiments discloses an osmotic power generation system.
  • the osmotic power generation system has a scalable porous membrane that has graphene.
  • the system is capable of generating power when the membrane is kept in a concentration gradient.
  • the invention discloses an osmotic power generation system 100 as shown in FIG. 1.
  • the system includes a housing 101, a scalable porous membrane 160 is placed within the housing such that the membrane 160 partitions the housing into a first chamber and a second chamber as shown in FIG. 1.
  • the scalable porous membrane 160 includes a first membrane 170 selected from SiNx (Silicon nitride) or Cu (Copper) membrane as shown in FIG. 2A.
  • a monolayer graphene membrane 180 is mounted on a surface of the first membrane 170 as shown in FIG. 2B.
  • the first membrane 170 is mounted on the monolayer graphene membrane 180.
  • the membranes have one or more pores 182 as shown in FIG.
  • the one or more pores on the membrane are punched using a femto second laser beam.
  • the pores are made continuously from the monolayer graphene membrane to the first membrane.
  • the pore size is in the range 0.5mm to 2mm.
  • the spacing between the pores 182 is ‘l ⁇
  • the pore density in the porous membrane is in a range of 4 to 7 pores in the scalable membrane of dimension lcmxlcm.
  • the thickness of the scalable membrane is in a range 16 to 20 pm, wherein the thickness of the monolayer graphene membrane 180 is in a range 0.342 to 0.345 nm.
  • the pore area / a membrane area is in the range 0.025 to 0.88.
  • the membrane has a first surface and a second surface.
  • the chamber disposed on the first surface of the membrane is the first chamber.
  • the first chamber 110 has a first electrode 130 and a first electrolyte 112.
  • the first electrolyte 112 is salt water or sea water.
  • the chamber disposed on the second surface of the membrane is the second chamber.
  • the second chamber 120 has a second electrode 140 and a second electrolyte 122.
  • the second electrolyte 122 is fresh water or river water.
  • the system 100 is configured to pass ions between the first and second surfaces of the porous membrane due to an osmotic gradient between the first 112 and the second electrolytes 122 to generate a difference in potential to generate an ionic current between the first electrode 130 and second electrode 140.
  • a load 150 is connected between the first electrode 130 and the second electrode 140 and is configured to receive power from the system.
  • the power generated is in the range of 58 to 70 mW/mm 2 of pore area.
  • the power generation is scalable to large scale power generation as illustrated further in the examples.
  • the osmotic power generation system is useful for energy harvesting, energy storage and in energy conversion devices like fuel-cell, water battery and power generator.
  • the battery is renewable and non-toxic.
  • the fuel-cell is made with conventional fuel-cell set-up using the scalable porous membranes.
  • Example. 1 Power generation in an Osmotic power generation system that uses graphene in copper membrane of varying dimensions:
  • FIG.4A The Raman spectroscopic analysis as shown in FIG. 4B shows the L D /I G value as 1.8 which is greater than 1.5 indicating the presence of monolayer of graphene.
  • the first chamber had salt water as electrolyte and the second chamber had fresh water.
  • the power generation was done with membranes of varying dimensions.
  • the power calculation was validated using analytical and continuum simulations of 2D Poisson- Nemst- Plank equations with Navier- Stokes equations.
  • FIG. 6A The theoretical power vs pore area with a single pore is illustrated in FIG. 6A.
  • the size of the single pore is varied from 0.2mm to 1mm. The power increases as the size of the pore increases.
  • FIG. 6B and FIG. 6C illustrates the power with pore area for multiple pores drilled inside the lcm 1cm membrane. The number of holes punched is 4 and 7 respectively, in FIG. 6B and FIG. 6C, respectively.
  • FIG. 6D shows the individual theoretical potassium and Chlorine current and the total current with pore area for a single punched pore in a 1cm c 1cm graphene/copper membrane.
  • Example. 2 Experimental power generation in Osmotic power generation systems that uses graphene in copper membrane and varying electrolytes with 1 cm c 1cm graphene/copper membrane and single punched pore of 1mm to validate the theoretical calculations.
  • This experimental constructed Osmotic generator having a graphene/Cu membrane had a single pore of 1mm diameter. The thickness of graphene/copper is 18pm similar to theoretical calculations.
  • the electrolytes were water or KC1 solution of different concentrations. Each experiment was repeated for four times minimum to ensure repeatability of results.
  • the output power is 48 mW as shown in Table. 2.
  • Another set of experiment varying the concentration of left reservoir and right reservoir where left reservoir is 2M and right reservoir is 0.2mM KC1 Solution the output power is 47mW as shown in Table. 3. Table.
  • Table.5 shows the output power when the right reservoir is changed from low salinity concentration KC1 to DI (Deionized water) to see the effect of water as a buffer solution.
  • the electrolyte is distilled water and KC1 solution for producing the power of 25 mW as tabulated in Table. 4.
  • the results tabulated in Table. 5 were produced when the right reservoir is tap water or low saline water and left reservoir is KC1 solution of 0.2mM concentration.
  • the said analytical open circuit potential for a concentration gradient of 1000, with high concentration solution in reservoir 1 is 0.6 M and low salinity concentration in reservoir 2 is 0.6 mM calculated using the famous Nemst equation is 0.4 V which is fairly matching the experiments showin in Table 2, which is 0.37 V.

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Abstract

The invention discloses an osmotic power generation system (100). The osmotic power generation system (100) incorporates a scalable porous membrane (160) that partitions the housing into a first chamber (110) and a second chamber (120). The first chamber has a first electrolyte (112) and an electrode (130) and the second chamber (120) has a second electrolyte (122) and an electrode (140). The system (100) is capable of generating power when the membrane (160) is kept in a concentration gradient. The scalable porous membrane (160) includes a first Cu membrane (170) a monolayer graphene membrane (180) mounted on the first membrane (170). The osmotic power generator system is configured to generate 58 to 70 mW/mm2 and thus produce megawatts power in relatively small membrane area. The system (100) is used for energy harvesting, energy storage and in energy conversion devices like fuel-cell, water battery and power generator.

Description

OSMOTIC POWER GENERATION SYSTEM
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a complete specification of provisional patent application no. 201941034016 entitled “A SCALABLE MEMBRANE FOR POWER GENERATION, ENERGY STORAGE, ENERGY HARVESTING, ENERGY CONVERSION, LIQUID ELECTRONICS AND ARTIFICIAL BRAIN CREATION USING SALT AND WATER” filed on 23.08.2019.
FIELD OF THE INVENTION
[0002] The invention generally relates to renewable energy generation and in particular to an osmotic power generation system that uses a scalable porous membrane.
DESCRIPTION OF RELATED ART
[0003] Renewable energy is the need of the hour for the growing population. The present renewable energy sources are solar, wind, and tidal energy. These sources of energy are discontinuous which may cause problem in power generation and storage. Generating power using salinity gradients was started in 2009 and companies in Denmark and Netherlands started the technology but not on commercial scale.
[0004] An osmotic power generator using saltwater and freshwater separated by an osmotic membrane may be used to generate electricity in abundance as seawater is available in large quantities and may also be reused. The power generated is harvested, stored, and used in energy conversion devices like a fuel cell, water battery, and power generator. The membranes used are made with large variety of materials to obtain satisfactory results. The membranes are of organic, inorganic, biomimetic, polymeric, stimuli responsive, PH- responsive types. The types of materials membranes include boron nitride and aramid nanofibers. The batteries produced using the membrane, are renewable and non- toxic, unlike conventional batteries. The compositions and the method of preparation for the membranes vary for every membrane. The membranes are affected by the salinity, PH, concentration, temperature conditions in the osmotic power generation.
[0005] The patent EP3475567B1, discloses the process of osmotic power generation comprising an active membrane supported in housing for receiving electrolyte liquids from two chambers. US20090250392A, describes the method of power generation using semi-permeable porous and non-porous membranes in elevated osmotic pressure. The patent US10233098B2, discusses the method of desalination of saltwater using a free-standing single layer nanoporous graphene membrane having a first planar side in contact with saltwater and opposing the second side from which desalinated water exists. The patent application US20190224628A1, discloses a process of preparing porous graphene-based films having reduced graphene oxide with different zones of different porosity that are used in infiltration processes. The article, “Atom-Thick Membranes for Water Purification and Blue Energy Harvesting”, David Pakulski et al.(2019), Advanced Functional Materials, disclosed the method of water purification and harvesting of osmotic power from the saline gradient between saltwater and freshwater. “New avenues for the large scale harvesting of blue energy”, Alessandro Siira et ah, Nature Reviews Chemistry, discusses current technologies for the conversion of blue energy and development of new classes of membranes combining considerations in nanoscale fluid dynamics and surface chemistry.
[0006] There is a need to generate low cost, eco-friendly, renewable energy that may be harvested and stored in a large scale. The invention discloses a membrane and an osmotic power generation system that addresses some of the drawbacks of existing methods. SUMMARY OF THE INVENTION
[0007] In various embodiments an osmotic power generator system is disclosed. The system includes a housing, a porous scalable membrane having a first surface and a second surface placed within the housing, a first chamber disposed on the first surface of the membrane and having a first electrode and a first electrolyte and a second chamber disposed on the second surface of the membrane and comprising a second electrode and a second electrolyte. A load is connected between the first electrode and the second electrode.
[0008] In various embodiments the porous scalable membrane includes a first membrane that is selected from SiNx (Silicon nitride) or Cu (Copper) membrane and a monolayer graphene membrane is mounted on a surface of the first membrane. In various embodiments the first membrane and the monolayer graphene membrane have one or more pores. In various embodiments the system is configured to pass ions between the first and second surfaces of the porous membrane due to an osmotic gradient between the first and the second electrolytes to generate a difference in potential and an ionic current between the first and second electrodes.
[0009] In various embodiments a size of the pore in the monolayer membrane is in a range of 0.5mm to 2mm. In various embodiments a pore density is in a range of 4 to 7 pores in the scalable membrane of dimension lcmxlcm. In various embodiments a thickness of the scalable membrane is in a range 16 to 20 pm. In various embodiments a thickness of the monolayer membrane is in a range 0.342 to 0.345 nm. In various embodiments the first electrolyte is salt water or sea water. In various embodiments the second electrolyte is fresh water or river water. In various embodiments the power generated is in the range of 58 to 70 mW/mm2 of pore area. In various embodiments the pore area / a membrane area is in the range 0.025 to 0.88
[0010] This and other aspects are disclosed herein. BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The invention has other advantages and features which will be more readily apparent from the following detailed description of the invention and the appended claims, when taken in conjunction with the accompanying drawings, in which:
[0012] FIG. 1 shows the schematic representation of osmotic power generation using salinity gradient.
[0013] FIG. 2A shows the porous membrane with multiple pores and an inter pore distance of l.
[0014] FIG 3A shows Graphene/ Copper sheet showing 1mm single and multiple holes formed using Femtosecond laser.
[0015] FIG. 3B illustrates Graphene/ Copper sheet showing 2mm single and multiple holes formed using Femtosecond laser.
[0016] FIG. 4A illustrates the Scanning Electron Microscopy showing commercially available Graphene/Copper membrane.
[0017] FIG. 4B illustrates the Raman spectroscopic analysis for graphene in copper membrane.
[0018] FIG. 5A illustrates the potassium concentration for a single 1 mm pore in a graphene on copper membrane of size 1 cm by 1 cm.
[0019] FIG. 5B illustrates the potential concentration for a single 1 mm pore in a graphene on copper membrane of size 1 cm by 1 cm.
[0020] FIG. 6A illustrates the power in a scalable porous membrane with pore area with a single pore.
[0021] FIG. 6B illustrates the power in a scalable porous membrane with pore area with 4 pores.
[0022] FIG. 6C illustrates the power in a scalable porous membrane with pore area with 7 pores. [0023] FIG. 6D illustrates the individual (potassium and chlorine) and total current (I total) in a scalable porous membrane with pore area with a single pore.
[0024] Referring to the drawings, like numbers indicate like parts throughout the views.
DETAILED DESCRIPTION
[0025] While the invention has been disclosed with reference to certain embodiments, it will be understood by those skilled in the art, that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made, to adapt to a particular situation or material to the teachings of the invention, without departing from its scope.
[0026] Throughout the specification and claims, the following terms take the meanings explicitly associated herein unless the context clearly dictates otherwise. The meaning of "a", "an", and "the" include plural references. The meaning of "in" includes "in" and "on." Referring to the drawings, like numbers indicate like parts throughout the views. Additionally, a reference to the singular includes a reference to the plural unless otherwise stated or inconsistent with the disclosure herein.
[0027] The invention in its various embodiments discloses an osmotic power generation system. The osmotic power generation system has a scalable porous membrane that has graphene. The system is capable of generating power when the membrane is kept in a concentration gradient.
[0028] In various embodiments, the invention discloses an osmotic power generation system 100 as shown in FIG. 1. The system includes a housing 101, a scalable porous membrane 160 is placed within the housing such that the membrane 160 partitions the housing into a first chamber and a second chamber as shown in FIG. 1. The scalable porous membrane 160 includes a first membrane 170 selected from SiNx (Silicon nitride) or Cu (Copper) membrane as shown in FIG. 2A. A monolayer graphene membrane 180 is mounted on a surface of the first membrane 170 as shown in FIG. 2B. In various embodiments the first membrane 170 is mounted on the monolayer graphene membrane 180. In various embodiments the membranes have one or more pores 182 as shown in FIG. 2B and FIG. 2C. In various embodiments the one or more pores on the membrane are punched using a femto second laser beam. The pores are made continuously from the monolayer graphene membrane to the first membrane. The pore size is in the range 0.5mm to 2mm. In various embodiments, the spacing between the pores 182 is ‘l\ In various embodiments the pore density in the porous membrane is in a range of 4 to 7 pores in the scalable membrane of dimension lcmxlcm. In various embodiments the thickness of the scalable membrane is in a range 16 to 20 pm, wherein the thickness of the monolayer graphene membrane 180 is in a range 0.342 to 0.345 nm. In various embodiments for a membrane area of 1cm c 1cm the pore area / a membrane area is in the range 0.025 to 0.88.
[0029] In various embodiments the membrane has a first surface and a second surface. The chamber disposed on the first surface of the membrane is the first chamber. The first chamber 110 has a first electrode 130 and a first electrolyte 112. In various embodiments the first electrolyte 112 is salt water or sea water. The chamber disposed on the second surface of the membrane is the second chamber. The second chamber 120 has a second electrode 140 and a second electrolyte 122. In various embodiments the second electrolyte 122 is fresh water or river water. In various embodiments the system 100 is configured to pass ions between the first and second surfaces of the porous membrane due to an osmotic gradient between the first 112 and the second electrolytes 122 to generate a difference in potential to generate an ionic current between the first electrode 130 and second electrode 140. In various embodiments a load 150 is connected between the first electrode 130 and the second electrode 140 and is configured to receive power from the system. In various embodiments the power generated is in the range of 58 to 70 mW/mm2 of pore area. The power generation is scalable to large scale power generation as illustrated further in the examples. [0030] The osmotic power generation system is useful for energy harvesting, energy storage and in energy conversion devices like fuel-cell, water battery and power generator. The battery is renewable and non-toxic. The fuel-cell is made with conventional fuel-cell set-up using the scalable porous membranes.
[0031] EXAMPLES:
[0032] Example. 1: Power generation in an Osmotic power generation system that uses graphene in copper membrane of varying dimensions:
[0033] An Osmotic power generation system was constructed. A graphene in copper membrane having pores as shown in FIG. 3A and FIG. 3B was kept between the first chamber and the second chamber. Scanning electron microscopic view of commercially available graphene in copper membrane is shown in FIG.4A. The Raman spectroscopic analysis as shown in FIG. 4B shows the LD/IG value as 1.8 which is greater than 1.5 indicating the presence of monolayer of graphene. The first chamber had salt water as electrolyte and the second chamber had fresh water. The power generation was done with membranes of varying dimensions. The output ionic current was measured and the output power was calculated as output power = ionic current c applied voltage. The power calculation was validated using analytical and continuum simulations of 2D Poisson- Nemst- Plank equations with Navier- Stokes equations.
[0034] Theoretically calculated power generation using a membrane of size 1 cm by 1cm width graphene on copper membrane:
[0035] A graphene in copper membrane of 1 cm length and 1 cm width with single 1 mm pore was taken same as the experimental set up. A single 1 mm pore was drilled in the graphene/copper membrane using femtosecond laser. The potassium concentration in the membrane is shown in FIG. 5A and potential distribution in FIG. 5B. The output power calculated is shown in Table. 1. Table. 1: Output power using a membrane of size 1 cm c 1 cm
Figure imgf000011_0001
For a 1mm pore in a graphene/Copper membrane of 1cm 1cm the calculated power is 64 mW which is very closely matching the experiments. The theoretical power vs pore area with a single pore is illustrated in FIG. 6A. The size of the single pore is varied from 0.2mm to 1mm. The power increases as the size of the pore increases. FIG. 6B and FIG. 6C illustrates the power with pore area for multiple pores drilled inside the lcm 1cm membrane. The number of holes punched is 4 and 7 respectively, in FIG. 6B and FIG. 6C, respectively. FIG. 6D shows the individual theoretical potassium and Chlorine current and the total current with pore area for a single punched pore in a 1cm c 1cm graphene/copper membrane.
[0036] Example. 2: Experimental power generation in Osmotic power generation systems that uses graphene in copper membrane and varying electrolytes with 1 cm c 1cm graphene/copper membrane and single punched pore of 1mm to validate the theoretical calculations.
[0037] This experimental constructed Osmotic generator having a graphene/Cu membrane had a single pore of 1mm diameter. The thickness of graphene/copper is 18pm similar to theoretical calculations. The electrolytes were water or KC1 solution of different concentrations. Each experiment was repeated for four times minimum to ensure repeatability of results. For an osmotic power generator using 0.6M in the left reservoir and 0.6mM KC1 Solution in the right reservoir as electrolytes (same as theoretical predictions are considered) the output power is 48 mW as shown in Table. 2. Another set of experiment varying the concentration of left reservoir and right reservoir where left reservoir is 2M and right reservoir is 0.2mM KC1 Solution the output power is 47mW as shown in Table. 3. Table. 4 and Table.5 shows the output power when the right reservoir is changed from low salinity concentration KC1 to DI (Deionized water) to see the effect of water as a buffer solution. The electrolyte is distilled water and KC1 solution for producing the power of 25 mW as tabulated in Table. 4. The results tabulated in Table. 5 were produced when the right reservoir is tap water or low saline water and left reservoir is KC1 solution of 0.2mM concentration.
[0038] The experiments were matching with theoretical predictions where for a lmm pore diameter in a 18 pm graphene/copper membrane where the graphene monolayer membrane thickness is 0.345 nm and the copper membrane thickness is 18 pm, the theoretical power calculated by analytically solving 2D Poisson+Nemst Planck and Navier-Stokes equations over this embodiment is 62 mW which is very close to the experiments of 45 mW to 55 mW for a 1 mm diameter pore. Also, the said analytical open circuit potential for a concentration gradient of 1000, with high concentration solution in reservoir 1 is 0.6 M and low salinity concentration in reservoir 2 is 0.6 mM calculated using the famous Nemst equation is 0.4 V which is fairly matching the experiments showin in Table 2, which is 0.37 V.
Table. 2: Output Power Using 0.6M and 0.6mM KC1 Solutions
Figure imgf000013_0002
Table 3: Output Power Using 2M and 0.2mM KC1 Solutions
Figure imgf000013_0003
Table. 4: Output Power Using DI Water and KC1 solution
Figure imgf000013_0004
Table. 5: Output Power Using Tap Water and KC1 Solution
Figure imgf000013_0001
Figure imgf000014_0001
[0039] Although the detailed description contains many specifics, these should not be construed as limiting the scope of the invention but merely as illustrating different examples and aspects of the invention. It should be appreciated that the scope of the invention includes other embodiments not discussed herein. Various other modifications, changes and variations which will be apparent, to those skilled in the art, may be made in the arrangement, operation and details of the system and method of the present invention disclosed herein without departing from the spirit and scope of the invention as described here. While the invention has been disclosed with reference to certain embodiments, it will be understood by those skilled in the art, that various changes may be made and equivalents may be substituted, without departing from the scope of the invention. In addition, many modifications may be made to adapt to a particular situation or material the teachings of the invention without departing from its scope.

Claims

WE CLAIM:
1. An osmotic power generator system (160) comprising: a housing (101); a porous scalable membrane (160) having a first surface and a second surface placed within the housing (101), the porous scalable membrane (160) comprising: a first membrane (170) selected from SiNx (Silicon nitride) or Cu (Copper) membrane; and a monolayer graphene membrane (180) mounted on a surface of the first membrane (170), wherein the first membrane and the monolayer graphene membrane (180) have one or more pores (182); a first chamber (110) disposed on the first surface of the membrane and comprising a first electrode (130) and a first electrolyte (112); a second chamber (120) disposed on the second surface of the membrane and comprising a second electrode (140) and a second electrolyte (122); and a load connected between the first electrode (130) and the second electrode (140), wherein the system is configured to pass ions between the first and second surfaces of the porous membrane due to an osmotic gradient between the first (112) and the second electrolytes (122) to generate a difference in potential and an ionic current between the first (130) and second electrodes (140).
2. The system as claimed as in claim 1, wherein a size of the pore in the monolayer membrane is in a range of 0.5mm to 2mm.
3. The system as claimed as in claim 1, wherein a pore density is in a range of 4 to 7 pores in the scalable membrane of dimension lcmxlcm.
4. The system as claimed as in claim 1, wherein a thickness of the scalable membrane (160) is in a range 16 to 20 mih.
5. The system as claimed as in claim 1, wherein a thickness of the monolayer membrane (180) is in a range 0.342 to 0.345 nm.
6. The system as claimed as in claim 1, wherein the first electrolyte (112) is salt water or sea water.
7. The system as claimed as in claim 1, wherein the second electrolyte (122) is fresh water or river water or saline water of predetermined concentration.
8. The system as claimed as in claim 1, wherein the power generated is in the range of 58 to 70 mW/mm2.
9. The system as claimed as in claim 1, wherein the pore area / a membrane area is in the range 0.025 to 0.88.
PCT/IN2020/050739 2019-08-23 2020-08-24 Osmotic power generation system WO2021038588A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2017196559A (en) * 2016-04-26 2017-11-02 株式会社バイオレドックス研究所 Electrolytic water manufacturing device and operation method therefor
EP3344374A1 (en) * 2015-09-02 2018-07-11 Sweetch Energy Device for producing energy by salinity gradient through titanium oxide nanofluid membranes
EP3475567A1 (en) * 2016-06-28 2019-05-01 Ecole Polytechnique Federale de Lausanne (EPFL) Osmotic power generator

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3344374A1 (en) * 2015-09-02 2018-07-11 Sweetch Energy Device for producing energy by salinity gradient through titanium oxide nanofluid membranes
JP2017196559A (en) * 2016-04-26 2017-11-02 株式会社バイオレドックス研究所 Electrolytic water manufacturing device and operation method therefor
EP3475567A1 (en) * 2016-06-28 2019-05-01 Ecole Polytechnique Federale de Lausanne (EPFL) Osmotic power generator

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