System and method for producing hydrogen and purified water from non-purified water

Abstract

The present invention relates to a system and method for producing hydrogen and purified water from non-purified water, the system comprising: a forward osmosis unit wherein a draw solution is an aqueous solution of a thermally decomposed salt, the forward osmosis unit comprising a forward osmosis treatment module, a draw solution pyrolysis module and a draw solution storage module, the forward osmosis treatment module is used for implementing forward osmosis between non-purified water and a draw solution to generate a used draw solution, and the draw solution pyrolysis module is used for accommodating the used draw solution from the forward osmosis treatment module and pyrolyzing the used draw solution to generate gas and primarily purified water; the gas generated by pyrolyzing the used draw solution is conveyed to the draw solution storage module and reacts to generate a draw solute, and the waste heat generated by the electrolysis unit is conveyed to the draw solution pyrolysis module for pyrolysis.

Description

Technical Field

[0001] The present invention relates to the field of environmental protection and energy conservation, and more specifically, to a system and method for generating green hydrogen and pure water from impure water. Background Art

[0002] As environmental issues become increasingly severe, the use of renewable energy is gaining increasing attention. Achieving net-zero emissions, in particular, has become a key research topic. However, the mismatch between the random and uncontrollable supply of renewable energy and energy demand results in a significant amount of unused electricity. Conventional approaches in this area utilize energy storage devices to store excess energy and release it for use when needed.

[0003] Hydrogen produced by water splitting using renewable energy, often referred to as "green hydrogen," is a common energy carrier for grid energy storage due to its high energy density and low cost. However, water splitting requires large quantities of high-purity freshwater, and the current shortage of freshwater resources makes it difficult to meet the demand for green hydrogen energy storage. While some groundwater and seawater purification technologies exist, these technologies are energy-intensive or have very low production capacity, making them inadequate for renewable energy storage.

[0004] After extensive and in-depth research, the inventors of this case discovered that the forward osmosis (FO) process can achieve an excellent mode of action for the water-energy relationship, thereby completing the present invention. Summary of the Invention

[0005] In a first aspect of the present invention, a system for generating hydrogen and pure water from impure water is provided, the system comprising: a forward osmosis unit for generating preliminary purified water through a forward osmosis process between impure water and a draw liquid; a purification treatment unit for treating the preliminary purified water into pure water; an electrolysis unit for electrolyzing the pure water into oxygen and hydrogen; an energy supply unit for providing energy to the system; wherein the draw liquid is an aqueous solution of a thermally decomposed salt; wherein the forward osmosis unit comprises a forward osmosis treatment module, a draw liquid pyrolysis module and a draw liquid storage module, the forward osmosis treatment module being used to perform forward osmosis between impure water and the draw liquid to generate a used draw liquid, the draw liquid pyrolysis module being used to accommodate the used draw liquid from the forward osmosis treatment module and pyrolyze the used draw liquid to generate gas and preliminary purified water, the gas generated by pyrolyzing the used draw liquid being transported to the draw liquid storage module and reacting to generate a draw solute, and the waste heat generated by the electrolysis unit being transported to the draw liquid pyrolysis module for the pyrolysis.

[0006] In some embodiments, the forward osmosis treatment module further comprises a forward osmosis membrane. In a specific embodiment, the forward osmosis membrane can be an asymmetric cellulose acetate membrane, a polyamide composite membrane, a cellulose acetate membrane or a polybenzimidazole membrane. In some embodiments, the draw liquid is an aqueous solution of a thermally decomposed salt. In a specific embodiment, the draw liquid can be an aqueous solution of ammonium bicarbonate or ammonium carbonate. In a preferred embodiment, the initial concentration of the aqueous solution of ammonium bicarbonate before the implementation of forward osmosis is 1.5 to 2 M, and the concentration after dilution with forward osmosis water is 0.25 M. In other embodiments, the draw liquid pyrolysis module operates in a temperature range of 40-80°C.

[0007] In some embodiments, the purification treatment unit includes one or more ion exchange modules, wherein the pre-purified water passes through the ion exchange modules in sequence. In a preferred embodiment, the purification treatment unit includes, in sequence, a weak cation exchange module, a strong cation exchange module, and a weak anion exchange module. In a specific embodiment, the purification treatment unit includes, in sequence, a draw solute-based weak cation exchange resin module, a proton-based strong cation exchange resin module, and a carbonate / bicarbonate-based weak anion exchange resin module.

[0008] In some embodiments, the purification treatment unit further comprises a degassing module, wherein the water purified by the ion exchange module is degassed in the degassing module and then transported to the electrolysis unit. In a specific embodiment, the degassing module can be a blast degassing tower, a vacuum degassing tower or a membrane degassing tower. In some embodiments, the purification treatment unit further comprises a regeneration treatment module, wherein the ion exchange module is regenerated by the regeneration liquid in the regeneration treatment module, and the spent regeneration liquid is recycled to the regeneration treatment module, wherein the heat generated by the electrolysis unit is transported to the regeneration treatment module to heat the spent regeneration liquid, and the generated gas is transported to the draw liquid storage module. In a preferred embodiment, the regeneration treatment module comprises a measuring instrument for measuring the changes in the components in the ion exchange module, and a heater for compensating for the heating of the spent regeneration liquid. In a further embodiment, the regeneration treatment module operates at a temperature range of 40-80°C.

[0009] In some embodiments, the electrolysis unit is a high-temperature electrolysis cell, wherein heat is transported by an organic Rankine cycle and a coil. In specific embodiments, the electrolysis unit may be a polymer electrolyte membrane electrolysis cell or a solid oxide electrolysis cell. In preferred embodiments, the electrolysis unit outputs hot water at a temperature of 60-80°C. In some embodiments, the energy supply unit is a renewable energy supply device. In specific embodiments, the energy supply unit may be a solar panel or a wind turbine.

[0010] In some embodiments, the impure water is groundwater, municipal wastewater, or seawater, the draw solution in the forward osmosis unit is a 1.5-2 M aqueous solution of ammonium bicarbonate, the electrolysis unit is a polymer electrolyte membrane electrolysis cell or a solid oxide electrolysis cell, and the electrolysis unit produces 1 kg of hydrogen and the forward osmosis unit processes 20 L of the impure water. In other embodiments, the system includes a pumping unit, and the energy supply unit provides energy only to the electrolysis unit and the pumping unit.

[0011] In a second aspect of the present invention, a method for generating hydrogen and pure water from impure water is provided, the method comprising operating the system described herein, wherein the system comprises: a forward osmosis unit for generating preliminary purified water by a forward osmosis process between impure water and an intake liquid; a purification treatment unit for treating the preliminary purified water into pure water; an electrolysis unit for electrolyzing the pure water into oxygen and hydrogen; an energy supply unit for providing energy to the system; wherein the intake liquid is an aqueous solution of a thermally decomposed salt; and wherein the forward osmosis unit is used to generate purified water. The unit includes a forward osmosis treatment module, an draw liquid pyrolysis module and a draw liquid storage module, wherein the forward osmosis treatment module is used to implement forward osmosis between impure water and draw liquid to produce used draw liquid, the draw liquid pyrolysis module is used to accommodate the used draw liquid from the forward osmosis treatment module and pyrolyze the used draw liquid to generate gas and preliminarily purified water, the gas generated by pyrolyzing the used draw liquid is transported to the draw liquid storage module and reacts to generate draw solutes, and the waste heat generated by the electrolysis unit is transported to the draw liquid pyrolysis module to perform the pyrolysis.

[0012] In some embodiments, the forward osmosis treatment module further comprises a forward osmosis membrane. In a specific embodiment, the forward osmosis membrane can be an asymmetric cellulose acetate membrane, a polyamide composite membrane, a cellulose acetate membrane or a polybenzimidazole membrane. In some embodiments, the draw liquid is an aqueous solution of a thermally decomposed salt. In a specific embodiment, the draw liquid can be an aqueous solution of ammonium bicarbonate or ammonium carbonate. In a preferred embodiment, the initial concentration of the aqueous solution of ammonium bicarbonate before the implementation of forward osmosis is 1.5 to 2 M, and the concentration after dilution with forward osmosis water is 0.25 M. In other embodiments, the draw liquid pyrolysis module operates in a temperature range of 40-80°C.

[0013] In some embodiments, the purification treatment unit includes one or more ion exchange modules, wherein the pre-purified water passes through the ion exchange modules in sequence. In a preferred embodiment, the purification treatment unit includes, in sequence, a weak cation exchange module, a strong cation exchange module, and a weak anion exchange module. In a specific embodiment, the purification treatment unit includes, in sequence, a draw solute-based weak cation exchange resin module, a proton-based strong cation exchange resin module, and a carbonate / bicarbonate-based weak anion exchange resin module.

[0014] In some embodiments, the purification treatment unit further comprises a degassing module, wherein the water purified by the ion exchange module is degassed in the degassing module and then transported to the electrolysis unit. In a specific embodiment, the degassing module can be a blast degassing tower, a vacuum degassing tower or a membrane degassing tower. In some embodiments, the purification treatment unit further comprises a regeneration treatment module, wherein the ion exchange module is regenerated by the regeneration liquid in the regeneration treatment module, and the spent regeneration liquid is recycled to the regeneration treatment module, wherein the heat generated by the electrolysis unit is transported to the regeneration treatment module to heat the spent regeneration liquid, and the generated gas is transported to the draw liquid storage module. In a preferred embodiment, the regeneration treatment module comprises a measuring instrument for measuring the changes in the components in the ion exchange module, and a heater for compensating for the heating of the spent regeneration liquid. In a further embodiment, the regeneration treatment module operates at a temperature range of 40-80°C.

[0015] In some embodiments, the electrolysis unit is a high-temperature electrolysis cell, wherein heat is transported by an organic Rankine cycle and a coil. In specific embodiments, the electrolysis unit may be a polymer electrolyte membrane electrolysis cell or a solid oxide electrolysis cell. In preferred embodiments, the electrolysis unit outputs hot water at a temperature of 60-80°C. In some embodiments, the energy supply unit is a renewable energy supply device. In specific embodiments, the energy supply unit may be a solar panel or a wind turbine.

[0016] In some embodiments, the impure water is groundwater, municipal wastewater, or seawater, the draw solution in the forward osmosis unit is a 1.5-2 M aqueous solution of ammonium bicarbonate, the electrolysis unit is a polymer electrolyte membrane electrolysis cell or a solid oxide electrolysis cell, and the electrolysis unit produces 1 kg of hydrogen and the forward osmosis unit processes 20 L of the impure water. In other embodiments, the system includes a pumping unit, and the energy supply unit provides energy only to the electrolysis unit and the pumping unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are provided below to further describe the embodiments of the present invention and its effects. However, the accompanying drawings are only for those skilled in the art to better understand the disclosure of the present invention and are not intended to limit the scope of the present invention.

[0018] Figure 1 is a schematic diagram of a system according to one embodiment of the present invention. DETAILED DESCRIPTION

[0019] Hereinafter, the present invention will be further described according to specific embodiments. However, the specific embodiments listed are for illustrative purposes only and are not intended to limit the scope of the present invention. Those skilled in the art will recognize that the specific technical features provided in any embodiment can be used in any other embodiment, or can be combined with other specific technical features in other embodiments, as long as they do not deviate from the gist of the present invention.

[0020] The forward osmosis (FO) process uses a high-salinity draw solution to create an osmotic gradient, thereby purifying water. However, FO typically relies on a separate, energy-intensive step to separate the product water and recover the draw solution. The inventors of this case, through ingenious design and setup, have enabled the excess heat generated by water electrolysis to provide the heat energy required for draw solution recovery. This allows the FO process, ion exchange, and water splitting to be integrated into a system that produces large quantities of pure water and green hydrogen with remarkably low energy requirements.

[0021] like Figure 1 As shown, the system of the present invention includes a forward osmosis unit, a purification treatment unit, an electrolysis unit, an energy supply unit, and optionally a pumping unit and a heater.

[0022] In the forward osmosis unit, an aqueous solution of a thermally decomposed salt is used as the draw liquid, and preliminary purified water is produced by the forward osmosis process between the impure water and the draw liquid. Here, the thermally decomposed salt, also referred to as the draw solute, can be ammonium bicarbonate or ammonium carbonate. Preferably, the draw liquid is an aqueous solution of ammonium bicarbonate with a concentration of 1.5 to 2 M. Such a concentration can increase the water flux, while the reverse salt flux is relatively small. The product flow rate can be 1 to 2 L / min, for example, 1, 1.5 or 2 L / min. The impure water herein can be groundwater, municipal wastewater or seawater, wherein the municipal wastewater can be treated municipal wastewater, for example, municipal wastewater from which a large amount of solids has been filtered out. In this unit, the preliminary purified water is relatively pure water, but contains a small amount of pollutants (such as sodium ions, magnesium ions, chloride ions, sulfate radicals, etc.).

[0023] The forward osmosis unit may also include a storage module for storing impure water, such as a impure water storage tank. The supplied impure water can be first stored in the storage module and then supplied to the forward osmosis treatment module (such as a forward osmosis tank) as needed according to the progress of the forward osmosis, and the wastewater generated by the forward osmosis treatment module can also flow back to the storage module.

[0024] In the forward osmosis unit, a draw solution pyrolysis module, such as a draw solution pyrolysis tank, receives spent draw solution from the forward osmosis treatment module, such as a 0.25M aqueous solution of ammonium bicarbonate, and pyrolyzes the spent draw solution to produce gases (carbon dioxide and ammonia) and pre-purified water. Waste heat from the electrolysis unit is transferred to the draw solution pyrolysis module to perform the pyrolysis. The draw solution pyrolysis module preferably operates at a temperature range of 40-80°C.

[0025] Forward osmosis unit can also comprise and draws the liquid storage module, for example draws the liquid storage tank, and the gas (carbon dioxide and ammonia) that draws the liquid that has been used by pyrolysis and generates is transported to and draws the liquid storage module, and reaction generates and draws solute, for example volatile organic compound or bicarbonate of ammonia.Draw in the liquid storage module, can have water input source, so that the solute that draws above-mentioned generation is configured to this paper as described in drawing solution.In addition, the CO that obtains in degassing module hereinafter described 2 also can be transported to and draws the liquid storage module so that reaction generates and draws solute.

[0026] In the purification treatment unit, preliminary purified water is processed into pure water, for example, by a plurality of ion exchange resins. For example, the purification treatment unit comprises weak cation exchange resin, strong cation exchange resin and weak anion exchange resin in sequence, and these exchange resins can be stored in tank containers respectively. In order to mate with the ammonium bicarbonate of this paper drawing liquid, the purification treatment unit can comprise drawing solute base (for example ammonium group) weak cation exchange resin, proton base strong cation exchange resin and carbonate / bicarbonate base weak anion exchange resin in sequence. Owing to drawing the gas after solute decomposition and possibly be entrained in the product, the purification treatment unit also comprises a degassing module, for example, a degassing tank, wherein the water purified by the ion exchange module is degassed and is transported to the electrolysis unit. The CO2 produced by the degassing module is transported to the drawing liquid storage module so that the reaction generates and draws the solute. The degassed pure water in the degassing module can be transported to a subsequent electrolysis unit, or can be directly transported to an outside for other purposes.

[0027] After the ion exchange resin in the purification treatment unit reaches a certain level of wear, it can be replaced or regenerated. Therefore, the purification treatment unit can also include a regeneration treatment module. Specifically, the weak cation exchange resin is regenerated using a thermally decomposed salt (e.g., ammonium bicarbonate) used as the draw solute, the strong cation exchange resin is regenerated using hydrochloric acid, and the weak anion exchange resin is regenerated using carbonate / bicarbonate. The spent regeneration liquid is recycled to the regeneration treatment module, for example, a regeneration treatment tank, where the heat generated by the electrolysis unit is transferred to the regeneration treatment module to heat the spent regeneration liquid, and the generated gases (carbon dioxide and ammonia) are transferred to the draw liquid storage module. The regeneration treatment module operates in a temperature range of 40-80°C and can be supplemented by a heater when necessary. Similarly, the regeneration treatment module includes a measuring instrument for measuring composition changes in the ion exchange module. When it detects that the ion exchange resin in the purification treatment unit has reached a set threshold, the regeneration process is initiated. For example, the regeneration chemical storage tank can flow ammonium bicarbonate, hydrochloric acid, and carbonate / bicarbonate into the three ion exchange resin tanks respectively to regenerate the ion exchange resin.

[0028] In the electrolysis unit, pure water is electrolyzed into oxygen and hydrogen. The electrolysis unit is preferably a high-temperature electrolysis cell, such as a polymer electrolyte membrane (PEM) electrolysis cell or a solid oxide electrolysis cell. The electrolysis unit transports heat through an organic Rankine cycle and a coil. Preferably, the heat generated by the electrolysis unit is transported to the draw liquid pyrolysis module of the forward osmosis unit and the regeneration treatment module of the purification treatment unit. Given that the electrolysis unit operates in a temperature range of 60-80°C, the waste heat generated by the reaction can be used to heat the draw liquid pyrolysis module and the regeneration treatment module, both of which can operate in a temperature range of 40-80°C, such as a temperature range of 40-60°C or 60-80°C. This thermal cycle can significantly reduce the overall heat demand of the system and maintain the water flux of the forward osmosis. The hydrogen produced by the electrolysis unit is transported to an external device for other applications, and the oxygen produced can be discharged after passing through a separator or transported to an external device for other applications.

[0029] The energy supply unit described herein is used to provide energy to the system, and the energy supply unit may be a solar panel or a wind power generator. The energy supply unit may provide energy to the electrolysis unit, the heater, and the pumping unit.

[0030] The system described herein can fully utilize the waste heat generated by the electrolysis process to provide heat for the forward osmosis process and regeneration treatment, while effectively cooling the electrolytic cell. For example, the water entering the electrolytic cell is at 20°C, which is then heated to 60-80°C by the waste heat. After heating the forward osmosis treatment module and / or the regeneration treatment module, the water temperature drops to 20°C, thereby lowering the temperature of the electrolytic cell upon reaching it. Through this ingenious combination, the inventors of this case have minimized the additional heat required for the entire system and avoided the separate treatment step of the electrolytic cell waste heat.

[0031] Furthermore, while conventional pyrolysis of pyrolytic salts requires waste heat from thermal power plants and other equipment, the system described herein utilizes only the heat from the internal pyrolysis cell. The water obtained after forward osmosis can be purified and used in the electrolysis cell, and water circulation can also cool the electrolysis cell. Specifically, the system described herein utilizes seawater, wastewater, and other resources, and utilizes internal heat supply to purify the water and regenerate the draw solution, achieving efficient heat and water circulation.

[0032] Example 1

[0033] use Figure 1 The configuration shown uses a 2M aqueous solution of ammonium bicarbonate as the draw solution, an asymmetric cellulose acetate membrane (purchased from Merck) as the forward osmosis membrane, seawater as the impure water, a solar cell (purchased from Longi Green Energy Technology Co., Ltd.) as the energy supply unit, and a polymer electrolyte membrane electrolyzer (purchased from CSIC Perri Hydrogen Energy Technology Co., Ltd.). In addition, a propylene / isobutylene weakly acidic cation exchange resin (DIAION TM WK40L), strong ion exchange resin (DIAION TM PK208L) and acrylic acid / styrene polyamine / styrene dimethylamine weak anion exchange resin (DIAION TM WA30) constitutes a purification processing unit.

[0034] When operating the system, the electrolyzer operates at 75% load and 80% efficiency (HHV). The electrolyzer wastes 20% of its energy input and recovers 15% of its energy input. Therefore, to produce 1kg of hydrogen, approximately 7.4kWh of energy is wasted as heat, and to produce 1kg of hydrogen, approximately 10-20 liters of pure water are required as feedstock for the electrolyzer.

[0035] After forward osmosis, an ammonium bicarbonate draw solution with a concentration of approximately 0.25M due to dilution with generated water maximizes energy recovery from waste heat. At this concentration, the energy required for pyrolysis at product flow rates of 1, 1.5, and 2 L / min is 0.31, 0.26, and 0.27 kWh / kg, respectively. Therefore, producing 20 L of water requires 5.2-6.2 kWh of thermal energy, while the electrolyzer generates approximately 7.4 kWh of waste heat for every kg of hydrogen produced, sufficient for post-processing and regeneration of the draw solution. Therefore, operating at this low draw solution concentration maximizes the synergistic energy savings of forward osmosis and PEM heat integration.

[0036] In addition to the aforementioned operating conditions, proper temperature control is also crucial for the regeneration process. The electrolyzer is operated at 60-80°C for optimal performance, as this temperature range increases reaction kinetics without degrading the polymer membrane. Simultaneously, the draw solution pyrolysis module is maintained at 40-60°C. Within this temperature range, the generated CO₂ and NH₃ gases can be effectively recovered by redissolving them in the draw solution, thereby regenerating ammonium bicarbonate and maintaining the draw solution concentration within the optimal range of 1.5-2 M.

[0037] The system is highly modular and scalable, offering advantages over traditional discrete unit operation configurations. Production can be scaled up through duplication of standardized process modules. This scalability will enable the system to flexibly meet a range of hydrogen production needs.

[0038] Although the embodiments of the present invention have been described above with reference to specific embodiments, it should be understood that those skilled in the art will be able to make various adjustments and changes thereto without departing from the scope and spirit of the present invention.

Claims

1. A system for generating hydrogen and purified water from impure water, comprising: A forward osmosis unit, the forward osmosis unit being used to produce preliminary purified water through a forward osmosis process between impure water and a drawn liquid; a purification treatment unit, the purification treatment unit being used to treat the preliminarily purified water into pure water; an electrolysis unit for electrolyzing pure water into oxygen and hydrogen; an energy supply unit, the energy supply unit being used to provide energy to the system; The drawn liquid is an aqueous solution of thermally decomposed salt; wherein the forward osmosis unit comprises a forward osmosis treatment module, a draw liquid pyrolysis module and a draw liquid storage module, wherein the forward osmosis treatment module is used to perform forward osmosis between impure water and draw liquid to produce used draw liquid, the draw liquid pyrolysis module is used to accommodate the used draw liquid from the forward osmosis treatment module and pyrolyze the used draw liquid to generate gas and preliminarily purified water, and the gas generated by pyrolyzing the used draw liquid is transported to the draw liquid storage module and reacts to generate draw solutes, and The waste heat generated by the electrolysis unit is transported to the draw liquid pyrolysis module to perform the pyrolysis. 2 . The system according to claim 1 , wherein the forward osmosis treatment module further comprises a forward osmosis membrane, such as an asymmetric cellulose acetate membrane, a polyamide composite membrane, a cellulose acetate membrane or a polybenzimidazole membrane.

3. The system according to claim 1 or 2, wherein the draw liquid is an aqueous solution of a thermally decomposed salt, such as an aqueous solution of ammonium bicarbonate or ammonium carbonate. Preferably, the initial concentration of the aqueous solution of ammonium bicarbonate before forward osmosis is 1.5 to 2 M, and the concentration after dilution with forward osmosis produced water is 0.25 M. The draw liquid pyrolysis module operates at a temperature range of 40-80°C.

4. The system according to claim 2, wherein the purification treatment unit comprises one or more ion exchange modules, wherein the preliminarily purified water passes through the ion exchange modules in sequence; Preferably, the purification treatment unit comprises a weak cation exchange module, a strong cation exchange module and a weak anion exchange module in sequence, such as a draw solute-based weak cation exchange resin module, a proton-based strong cation exchange resin module and a carbonate / bicarbonate-based weak anion exchange resin module.

5. The system according to claim 4, wherein the purification treatment unit further comprises a degassing module, such as a forced air degassing tower, a vacuum degassing tower, or a membrane degassing tower, wherein the water purified by the ion exchange module is degassed in the degassing module and then transported to the electrolysis unit; and wherein the purification treatment unit further comprises a regeneration treatment module, wherein the ion exchange module is regenerated by the regeneration liquid in the regeneration treatment module, and the spent regeneration liquid is recycled to the regeneration treatment module, wherein the heat generated by the electrolysis unit is transported to the regeneration treatment module to heat the spent regeneration liquid, and the generated gas is transported to the draw liquid storage module; Preferably, the regeneration processing module includes a measuring instrument for measuring the composition change in the ion exchange module, and a heater for compensating for the heating of the spent regeneration liquid. More preferably, the regeneration processing module operates at a temperature range of 40-80°C.

6. The system of claim 1 , wherein the electrolysis unit is a high temperature electrolyzer, such as a polymer electrolyte membrane electrolyzer or a solid oxide electrolyzer, and The electrolysis unit is heat transported via an organic Rankine cycle and a coil. Preferably, the electrolysis unit outputs hot water at 60-80°C.

7. The system according to claim 1, wherein the energy supply unit is a renewable energy supply device, such as a solar panel or a wind generator.

8. The system according to any one of claims 1 to 7, wherein the impure water is groundwater, municipal wastewater or seawater, the draw liquid in the forward osmosis unit is a 1.5-2 M aqueous solution of ammonium bicarbonate, the electrolysis unit is a polymer electrolyte membrane electrolyzer or a solid oxide electrolyzer, and wherein the electrolysis unit produces 1 kg of hydrogen and the forward osmosis unit processes 20 L of the impure water.

9. The system according to any one of claims 1 to 7, wherein the system comprises a pumping unit, and the energy supply unit only provides energy to the electrolysis unit and the pumping unit.

10. A method for generating hydrogen and purified water from impure water, the method comprising operating the system according to any one of claims 1 to 9.

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