ENERGY SYSTEM USING BYPRODUCTS GENERATED FROM SEAWATER ELECTROLYZER

Abstract

Disclosed is a technique for capturing, refining and storing byproduct hydrogen generated by a seawater electrolyzer, using the byproduct hydrogen in an energy system, and producing high-purity magnesium oxide from alkali byproducts additionally produced after seawater electrolysis. An energy system 100 may include a seawater electrolyzer 110 generating a chlorine substance by electrolyzing seawater, a hydrogen storage unit 120 capturing, refining, and storing byproduct hydrogen generated in the electrolysis process by the seawater electrolyzer, a fuel cell 130 using, as fuel, the byproduct hydrogen stored in the hydrogen storage unit, an MgO acquisition unit 140 converting, into magnesium oxide, magnesium hydroxide additionally generated from the seawater in the seawater electrolyzer, a hydrogen capture pipe 150 having one side coupled to the seawater electrolyzer and other side coupled to the hydrogen storage unit and transferring the byproduct hydrogen from the seawater electrolyzer to the hydrogen storage unit.

Claims

1. An energy system using byproducts generated by a seawater electrolyzer, comprising: the seawater electrolyzer configured to generate a chlorine substance by electrolyzing seawater; a hydrogen storage unit configured to capture, refine, and store byproduct hydrogen generated in the electrolysis process by the seawater electrolyzer; a fuel cell configured to use, as fuel, the byproduct hydrogen stored in the hydrogen storage unit; and a magnesium oxide (Mg0) acquisition unit configured to convert, into magnesium oxide, magnesium hydroxide additionally generated from the seawater in the seawater electrolyzer.

2. The energy system of claim 1, wherein the hydrogen storage unit stores the byproduct hydrogen in a metal hydroxide form.

3. The energy system of claim 1, wherein the hydrogen storage unit stores the byproduct hydrogen by using a hydrogen storage alloy.

4. The energy system of claim 3, wherein the hydrogen storage alloy is selected from LaNi.sub.3BH.sub.3, Li.sub.2NH, TiCl.sub.3, Li.sub.2O—Li.sub.3N, Li.sub.2MgN.sub.2H.sub.2, Li.sub.3N, Li.sub.2NH, Li.sub.3BN.sub.2H.sub.8, and LiB.sub.4.½MgH.sub.2.

5. The energy system of claim 1, further comprising a hydrogen capture pipe configured to have one side coupled to the seawater electrolyzer and other side coupled to the hydrogen storage unit and to transfer the byproduct hydrogen from the seawater electrolyzer to the hydrogen storage unit.

6. The energy system of claim 1, further comprising a hydrogen supply pipe configured to have one side coupled to the hydrogen storage unit and other side connected to the fuel cell and to transfer the byproduct hydrogen from the hydrogen storage unit to the fuel cell.

7. The energy system of claim 1, wherein the MgO acquisition unit converts the magnesium hydroxide (Mg(OH).sub.2) into the magnesium oxide (MgO) through a pyrolytic reaction.

8. The energy system of claim 7, wherein the pyrolytic reaction is performed in a temperature of 350 to 450° C.

9. The energy system of claim 1, further comprising a magnesium hydroxide transfer pipe configured to have one side coupled to the seawater electrolyzer and other side coupled to the MgO acquisition unit and to transfer the magnesium hydroxide from the seawater electrolyzer to the MgO acquisition unit.

10. The energy system of claim 1, wherein the fuel cell is selected from a molten carbonate fuel cell (MCFC), a polyelectrolyte fuel cell (PEMFC), a solid oxide fuel cell (SOFC), a direct methanol fuel cell (DMFC), a direct ethanol fuel cell (DEFC), a phosphoric acid fuel cell (PAFC), and a direct carbon fuel cell (DCFC).

Description

DESCRIPTION OF THE DRAWINGS

[0016] The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

[0017] FIG. 1 is a diagram illustrating a structure of an energy system according to an embodiment of the present disclosure.

[0018] FIG. 2 is a diagram illustrating a structure of an energy system according to another embodiment of the present disclosure.

DETAILED DESCRIPTION

[0019] While illustrative embodiments have been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.

[0020] Hereinafter, embodiments of the present disclosure are described in detail with reference to the accompanying drawings. Embodiments of the present disclosure to be described hereinafter relate to an energy system, including a seawater electrolyzer, a hydrogen storage unit, a magnesium oxide (MgO) acquisition unit, and a fuel cell.

[0021] FIG. 1 is a diagram illustrating a structure of an energy system 100 according to an embodiment of the present disclosure. Referring to FIG. 1, the energy system 100 according to an embodiment of the present disclosure includes a seawater electrolyzer 110 for producing a chlorine substance by electrolyzing seawater, a hydrogen storage unit 120 for capturing, refining, and storing byproduct hydrogen generated in the electrolysis process by the seawater electrolyzer, a fuel cell 130 using, as fuel, the byproduct hydrogen stored in the hydrogen storage unit, and a magnesium oxide (MgO) acquisition unit 140 for converting, into magnesium oxide, magnesium hydroxide (Mg(OH).sub.2) additionally generated from the seawater in the seawater electrolyzer. The MgO acquisition unit 140 may convert the magnesium hydroxide (Mg(OH)2) into the magnesium oxide (MgO) through a pyrolytic reaction. For example, the pyrolytic reaction may be performed in a temperature of 350 to 450° C.

[0022] In an embodiment of the present disclosure, the seawater electrolyzer 110 generates a chlorine substance, such as chlorine, by electrolyzing seawater. Chlorine generated by electrolyzing seawater per one seawater electrolyzer module is 1,100 ppm. This may be represented as the number of moles per hour as follows.

NaOCl: 1,100 ppm (mg/L)*30 ton/hr=(33 kg/hr,Cl.sub.2)/(1 mol/35 g)=1,155 mol/hr

[0023] Byproduct hydrogen generated as byproducts in a process of electrolyzing seawater is generated as the same number of moles as chlorine. The amount of byproduct hydrogen generated through seawater electrolysis per one seawater electrolyzer module is about H.sub.2: 1,155 mol/hr*22.4 L/1M=26 m.sup.3/hr. In an embodiment of the present disclosure, the same amount of byproduct hydrogen additionally generated as much as the amount of chlorine generated through seawater electrolysis can be captured, stored and provided as an energy source, such as a fuel cell, without discharging the byproduct hydrogen into the atmosphere. For example, in the case of a polyelectrolyte fuel cell (PEMFC), electricity of about 1 kW (AC) can be produced using hydrogen of 1 m.sup.3/hr as fuel. Accordingly, an energy system according to an embodiment of the present disclosure can produce electricity of about 26 kW per hour through one seawater electrolyzer module.

[0024] In an embodiment of the present disclosure, the hydrogen storage unit 120 captures, refines and stores byproduct hydrogen generated by the seawater electrolyzer 110 through the electrolysis process of seawater, and can significantly reduce a storage volume by storing byproduct hydrogen in the form of metal hydroxide. In order to store byproduct hydrogen in the form of metal hydroxide, a hydrogen storage alloy may be used. The hydrogen storage alloy may be any one selected from LaNi.sub.3BH.sub.3, Li.sub.2NH, LiNH.sub.2—LiH, TiCl.sub.3, Li.sub.2O—Li.sub.3N, Li.sub.2MgN.sub.2H.sub.2, Li.sub.3N, Li.sub.2NH, Li.sub.3BN.sub.2H.sub.8, and LiB.sub.4.½MgH.sub.2.2 mol % (or LiB.sub.4.½MgH.sub.2).

[0025] As the hydrogen storage alloy and the byproduct hydrogen reach to each other, metal hydroxide is generated and simultaneously heat occurs. The pressure of hydrogen gas may be lowered due to the generated heat. In this case, the pressure of the hydrogen gas may be raised by applying heat to the metal hydroxide so that the hydrogen gas is discharged. A difference between the lowered pressure and raised pressure of the hydrogen gas at this time may be converted into motive power for driving the fuel cell to be described later.

[0026] In an embodiment of the present disclosure, the fuel cell 130 uses, as fuel, byproduct hydrogen stored in the hydrogen storage unit 120. Oxygen is supplied to the cathode of the fuel cell 130, and the byproduct hydrogen is supplied to the fuel pole of the fuel cell 130. As an electrochemical reaction occurs in the form of a reverse electrolysis reaction, electricity, heat, and water are generated, so that electrical energy can be produced with high efficiency while not causing pollution. In an embodiment of the present disclosure, the fuel cell 130 may systematically basically consist of a fuel cell stack for generating electrical energy, a fuel supply device for supplying fuel to the fuel cell stack, an air supply device for supplying the fuel cell stack with oxygen within the air, that is, an oxidant necessary for an electrochemical reaction, and a heat and water management device for removing reaction heat of the fuel cell stack toward the outside of the system and controlling an operating temperature of the fuel cell stack. For example, the fuel cell may be selected from a molten carbonate fuel cell (MCFC), a polyelectrolyte fuel cell (PEMFC), a solid oxide fuel cell (SOFC), a direct methanol fuel cell (DMFC), a direct ethanol fuel cell (DEFC), a phosphoric acid fuel cell (PAFC), and a direct carbon fuel cell (DCFC). Through such a construction, the fuel cell generates electricity by an electrochemical reaction between hydrogen, that is, fuel, and oxygen within the air, and discharges heat and water as reaction byproducts.

[0027] In an embodiment of the present disclosure, in the fuel cell 130, a given amount of byproduct hydrogen is supplied from the hydrogen repository 120, pumped by a compressor or blower for supplying hydrogen, and supplied to the fuel pole through the inlet of the fuel cell 130. At the same time, the air is supplied to the fuel cell and generates oxidation and reduction reactions along with the byproduct hydrogen supplied to the fuel pole, so that electrical energy is generated.

[0028] In an embodiment of the present disclosure, in order to transfer byproduct hydrogen by connecting the seawater electrolyzer 110 and the hydrogen storage unit 120, the energy system 100 of FIG. 1 may further include a hydrogen capture pipe 150 having one side coupled to the seawater electrolyzer 110 and the other side coupled to the hydrogen storage unit 120. Furthermore, the energy system 100 of FIG. 1 further includes a magnesium hydroxide transfer pipe 170 having one side coupled to the seawater electrolyzer 110 and the other side coupled to the MgO acquisition unit 140 and transferring magnesium hydroxide from the seawater electrolyzer 110 to the MgO acquisition unit 140.

[0029] FIG. 2 is a diagram illustrating a structure of an energy system 100 according to another embodiment of the present disclosure. Referring to FIG. 2, the energy system 100 according to an embodiment of the present disclosure includes a seawater electrolyzer 110 for producing a chlorine substance by electrolyzing seawater, a hydrogen storage unit 120 for capturing, refining, and storing byproduct hydrogen generated in the electrolysis process by the seawater electrolyzer, a fuel cell 130 using, as fuel, the byproduct hydrogen stored in the hydrogen storage unit, a magnesium oxide (MgO) acquisition unit 140 for converting, into magnesium oxide, magnesium hydroxide (Mg(OH).sub.2) additionally generated from the seawater in the seawater electrolyzer, a hydrogen capture pipe 150 having one side coupled to the seawater electrolyzer 110 and the other side coupled to the hydrogen storage unit 120 and transferring the byproduct hydrogen, and a magnesium hydroxide transfer pipe 170 having one side coupled to the seawater electrolyzer 110 and the other side coupled to the MgO acquisition unit 140 and transferring magnesium hydroxide. Furthermore, the energy system 100 of FIG. 2 may further include a hydrogen supply pipe 160 having one side coupled to the hydrogen storage unit 120 and the other coupled to the fuel cell 130 in order to transfer the byproduct hydrogen from the hydrogen storage unit 120 to the fuel cell 130.

[0030] The preferred embodiments of the present disclosure have been described so far. A person having common knowledge in a technical field to which the present invention pertains will understand that the present invention may be implemented in a modified form without departing from an intrinsic characteristic of the present disclosure. Accordingly, the disclosed embodiments should be considered from a descriptive viewpoint not from a limitative viewpoint. The range of the present disclosure is described in the claims not the above description, and all differences within an equivalent range thereof should be construed as being included in the present disclosure.

DESCRIPTION OF REFERENCE NUMERAL

[0031] 100: energy system

[0032] 110: seawater electrolyzer

[0033] 120: hydrogen storage unit

[0034] 130: fuel cell

[0035] 140: magnesium hydroxide acquisition unit

[0036] 150: hydrogen capture pipe

[0037] 160: hydrogen supply pipe

[0038] 170: magnesium hydroxide transfer pipe