Co-electrolysis system linked with carbon dioxide capture

Abstract

A co-electrolysis system according to one embodiment of the present invention may comprise: a mixed gas supplier for supplying a mixed gas containing carbon dioxide and water vapor; a co-electrolysis device for co-electrolyzing the mixed gas to generate a synthetic gas containing carbon monoxide and hydrogen; a carbonator for mixing an alkaline earth metal oxide-containing material with the synthetic gas and carbonating the alkaline earth metal oxide-containing material and carbon dioxide to obtain a carbonate; and a calciner for calcining the carbonate to regenerate the carbonate into an alkaline earth metal oxide-containing material.

Description

Co-electrolysis system linked to carbon dioxide capture

[0001] The present invention relates to a co-electrolysis system linked with carbon dioxide capture.

[0002] As industrial development progresses, energy consumption increases, leading to climate change caused by rising carbon dioxide (CO2) emissions. As part of efforts to address the climate crisis, research is being conducted on technologies to chemically convert emitted carbon dioxide into high-value compounds.

[0003] Among these, carbon dioxide electrolysis technology is a carbon dioxide conversion technology that electrochemically produces synthesis gas using carbon dioxide and steam as raw materials on a Solid Oxide Electrolysis Cell (SOEC), and is classified into high-temperature and low-temperature types depending on the electrolyte. High-temperature electrolysis technology has significant advantages in terms of thermodynamics and reaction kinetics compared to the low-temperature type, and at the same time, it can achieve synergistic effects by utilizing waste heat and surplus electricity from carbon dioxide emitting facilities.

[0004] On the other hand, when the co-electrolysis reaction temperature is reduced, a significant amount of carbon dioxide remains in the co-electrolysis product due to thermodynamic equilibrium limitations of the RWGS (Reverse Water Gas Shift Reaction (rWGS)) reaction. When the co-electrolysis product is utilized as a raw material for the synthetic fuel production process, the residual carbon dioxide that does not participate in the reaction reduces process efficiency during pressurization and heating, and there is a problem of concentration within the reactor during the synthetic fuel production process. In addition, there is a problem that high energy input costs are required because operation must be performed at higher temperatures to reduce the amount of residual carbon dioxide in the co-electrolysis product.

[0005] According to one embodiment of the present invention, a co-electrolysis system for producing industrially useful synthesis gas with reduced residual carbon dioxide can be provided.

[0006] According to one embodiment of the present invention, a co-electrolysis system capable of reducing carbon dioxide emissions and creating added value can be provided.

[0007] According to one embodiment of the present invention, a co-electrolysis system with reduced energy input costs can be provided.

[0008] The problems of the present invention are not limited to those described above. A person skilled in the art to which the present invention pertains will have no difficulty understanding additional problems of the present invention from the overall contents of this specification.

[0009] A co-electrolysis system according to one embodiment of the present invention comprises: a mixed gas supplyer that supplies a mixed gas containing carbon dioxide and water vapor; a co-electrolysis device that co-electrolyzes the mixed gas to produce a synthesis gas containing carbon monoxide and hydrogen; a carbonator that mixes an alkaline earth metal oxide-containing material with the synthesis gas and carbonates the alkaline earth metal oxide-containing material with carbon dioxide to obtain a carbonate; and a calciner that calcines the carbonate to regenerate it into an alkaline earth metal oxide-containing material.

[0010] The oxygen generated in the above-mentioned co-electrolysis device can be supplied to the above-mentioned calcination chamber.

[0011] The above calcination device can generate carbon dioxide and water vapor by combusting methane with pure oxygen.

[0012] The carbon dioxide and water vapor generated in the above calcination furnace may be supplied to the above electrolysis device.

[0013] The operating temperature of the above-mentioned firing furnace may be 900℃ or higher.

[0014] The calcium oxidizing agent produced in the above calcination furnace may be supplied back to the above carbonation furnace.

[0015] It may further include a first heat exchanger that exchanges heat between the mixed gas discharged from the mixed gas supply unit and the heat generated in the carbonation unit.

[0016] It may further include a second heat exchanger that exchanges heat between the mixed gas discharged from the mixed gas supply unit and the synthetic gas discharged from the carbonation unit.

[0017] It may further include a third heat exchanger that heat exchanges the mixed gas discharged from the mixed gas supply unit with the alkaline earth metal oxide-containing material supplied from the calciner to the carbonator.

[0018] A co-electrolysis system, which is one embodiment of the present invention, can produce industrially useful synthesis gas by reducing the residual amount of carbon dioxide.

[0019] An electrolysis system, which is an embodiment of the present invention, can reduce carbon dioxide emissions and create added value.

[0020] An electrolysis system, which is an embodiment of the present invention, can reduce energy input costs.

[0021] FIG. 1 is a schematic diagram showing a co-electrolysis system which is an embodiment of the present invention.

[0022] FIG. 2 is a schematic diagram showing a co-electrolysis device in one embodiment of the present invention.

[0023] Preferred embodiments of the present invention will be described below with reference to the attached drawings. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

[0024] In addition, embodiments of the present invention are provided to more fully explain the present invention to those with average knowledge in the relevant technical field.

[0025] In drawings, the shapes and sizes of elements may be exaggerated for clearer explanation.

[0026] In describing the embodiments of the present invention, if it is determined that a detailed description of known technology related to the present invention may unnecessarily obscure the essence of the present invention, such detailed description will be omitted. Furthermore, the terms described below are defined considering their functions in the present invention, and these may vary depending on the intentions or conventions of the user or operator. Therefore, such definitions should be based on the content throughout this specification. The terms used in the detailed description are merely for describing the embodiments of the present invention and should not be limited in any way. Unless explicitly stated otherwise, expressions in the singular form include the meaning of the plural form.

[0027] In this description, expressions such as “include” or “equipped” are intended to refer to certain characteristics, numbers, steps, actions, elements, parts or combinations thereof, and should not be interpreted to exclude the existence or possibility of one or more other characteristics, numbers, steps, actions, elements, parts or combinations thereof other than those described.

[0028] Unless otherwise specifically defined in the specification of the present invention, % units mean weight %.

[0029] In this specification, terms such as 'top', 'upper', 'upper surface', 'lower', 'lower surface', 'lower surface', and 'side surface' are based on the drawings and may actually vary depending on the direction in which the elements or components are arranged.

[0030] Additionally, throughout the specification, when it is said that one part is 'connected' to another part, this includes not only cases where they are 'directly connected,' but also cases where they are 'indirectly connected' with other elements in between.

[0031] The present invention will be described in detail below through each embodiment or example of the invention. It should be noted that each embodiment or example described in this specification is not limited to a single embodiment or example, but may also be combined with other embodiments or examples. Accordingly, the citation of claims in the patent claims is merely an example of an embodiment, and the technical concept of the present invention should not be interpreted as being limited only to a combination with the cited claims; rather, combinations with various claims are also included within the scope of the technical concept of the present invention.

[0032] An electrolysis system (10) of one embodiment of the present invention can convert carbon dioxide using an electrolysis device (200), and can increase the efficiency of the electrolysis device (200) by capturing and reusing the unremoved carbon dioxide.

[0033] In addition, one embodiment of the present invention can easily create a high-temperature environment to maintain high energy efficiency.

[0034] FIG. 1 is a schematic diagram showing a co-electrolysis system (10) which is an embodiment of the present invention. Referring to FIG. 1, a co-electrolysis system (10) which is an embodiment of the present invention may include: a mixed gas supply unit (100) that supplies a mixed gas containing carbon dioxide and water vapor; a co-electrolysis device (200) that co-electrolyzes the mixed gas to produce a synthesis gas containing carbon monoxide and hydrogen; a carbonator (300) that mixes an alkaline earth metal oxide-containing material with the synthesis gas and carbonates the alkaline earth metal oxide-containing material with carbon dioxide to obtain a carbonate; and a calcinerator (400) that calcines the carbonate to regenerate it into an alkaline earth metal oxide-containing material.

[0035] The carbon dioxide contained in the mixed gas of the above-mentioned mixed gas supply device (100) may be derived from ordinary air as well as byproduct gas. Examples of byproduct gas may include those generated in processes such as COG (Cokes oven gas) and FOG (Finex off gas), but are not specifically limited.

[0036] The water vapor contained in the mixed gas of the above mixed gas supply device (100) can be stored in a gaseous state, as well as in a solid or liquid state.

[0037] The steam contained in the mixed gas of the above-mentioned mixed gas supply unit (100) may originate from steam generated by utilizing process waste heat from a steel mill, power plant, etc.

[0038] The mixed gas of the above mixed gas supply device (100) may further include gases such as hydrogen and nitrogen in addition to carbon dioxide and water vapor.

[0039] The mixed gas can be heated and supplied from the above mixed gas supply unit (100) to the above electrolysis device (200) before being supplied.

[0040] The molar ratio of gas components included in the mixed gas supplied from the mixed gas supply unit (100) to the co-electrolysis device (200) may be, for example, carbon dioxide : water vapor = 1 : 1 to 1 : 4.

[0041] FIG. 2 is a schematic diagram showing a co-electrolysis device (200) in one embodiment of the present invention. Referring to FIG. 2, in one embodiment of the present invention, a steam electrolysis reaction, a carbon dioxide electrolysis reaction, and a reverse water-gas shift reaction may be carried out at the fuel electrode of the co-electrolysis device (200).

[0042] The steam electrolysis reaction produces hydrogen (H2) and oxygen ions (O2) from water vapor (H2O). 2- It is a reaction that produces ). The reaction equation for the steam electrolysis reaction is shown in Equation 1 below.

[0043] [Equation 1]

[0044] H2O + 2e - → H2 + O 2-

[0045] The carbon dioxide electrolysis reaction produces carbon monoxide (CO) and oxygen ions (O) from carbon dioxide (CO2). 2- It is a reaction that produces ). The reaction equation for the carbon dioxide electrolysis reaction is shown in Equation 2 below.

[0046] [Equation 2]

[0047] CO2 + 2e - → CO + O 2-

[0048] In the case of the electrolysis reaction occurring in the co-electrolysis device (200) of the present invention, the electrolysis reaction of water vapor may be dominant over the electrolysis reaction of carbon dioxide, and the electrolysis reaction of water vapor may proceed primarily. That is, the carbon dioxide conversion reaction by the reverse water-gas shift reaction, which proceeds using hydrogen produced from the electrolysis reaction of water vapor, may proceed predominantly rather than the carbon dioxide conversion through electrolysis.

[0049] The Reverse Water Gas Shift (RWGS) reaction is a reaction that produces carbon monoxide (CO) and water vapor (H2O) from carbon dioxide (CO2) and hydrogen (H2). The reaction equation for the Reverse Water Gas Shift reaction is shown in Equation 3 below.

[0050] [Equation 3]

[0051] CO2 + H2 ↔ CO + H2O

[0052] In the above-mentioned co-electrolysis device (200), in one embodiment of the present invention, the air electrode of the co-electrolysis device (200) may be positioned to face the fuel electrode with the electrolyte in between. The air electrode may receive oxygen ions from the fuel electrode through the electrolyte. The air electrode may produce oxygen according to a reaction such as Equation 4 below.

[0053] [Equation 4]

[0054] O2- → 1 / 2O2+ 2e -

[0055] The operating temperature of the above-mentioned co-electrolysis device (200) may be 650 to 900°C, specifically 700 to 800°C. The operating temperature of the co-electrolysis device (200) may affect the equilibrium conversion rate of the reverse water-gas shift reaction, and if the operating temperature of the co-electrolysis device (200) is 650°C or higher, the equilibrium of the reverse water-gas shift reaction may be shifted, thereby increasing the carbon dioxide conversion rate. If the operating temperature of the co-electrolysis device (200) is less than 650°C, the electrolysis reaction may not proceed easily, and if it exceeds 900°C, problems such as high energy consumption and reduced device durability due to high-temperature reaction conditions may occur.

[0056] According to one embodiment of the present invention, the electrolysis rate of the reactant (H2O+CO2) electrolyzed at the fuel electrode in the co-electrolysis device (200) may be 50 to 90%. The electrolysis rate can be calculated through the following Equation 5.

[0057] [Equation 5]

[0058] Electrolysis rate = (Moles of reactant (CO2+H2O) being electrolyzed) / (Moles of reactant (CO2+H2O) supplied to the co-electrolysis device (200)

[0059] The electrolysis rate of the above-mentioned co-electrolysis device (200) can be controlled by adjusting the power supplied to the above-mentioned co-electrolysis device (200). Even when using reaction gas of the same composition, as the electrolysis rate of the reactant increases, the electrolysis of water vapor proceeds, and the concentration of hydrogen, which is a reactant of the reverse water-gas shift reaction, increases, thereby increasing the equilibrium conversion rate of carbon dioxide.

[0060] If the electrolysis rate of the above-mentioned co-electrolysis device (200) is less than 50%, the conversion rate of carbon dioxide may be lowered, and if the electrolysis rate exceeds 90%, problems with the durability of the device may occur due to overvoltage and carbon deposition of the co-electrolysis device.

[0061] The above-mentioned co-electrolysis device (200) can generate oxygen at the air electrode and generate carbon monoxide and hydrogen at the fuel electrode. The synthesis gas containing carbon monoxide and hydrogen generated at the fuel electrode, and unreacted feedstocks such as carbon dioxide and water vapor, can be supplied to the carbonator (300).

[0062] In this specification, synthesis gas may refer to a gas comprising carbon monoxide and hydrogen, and may further include gases of other components in addition to carbon monoxide and hydrogen.

[0063] In one embodiment of the present invention, an oxygen storage tank (600) for storing oxygen generated in the co-electrolysis device (200) may be further included.

[0064] The carbonation device (300) may be a device that carbonates carbon dioxide by mixing carbon dioxide contained in the synthesis gas obtained from the above-mentioned electrolytic device (200) with a substance containing alkaline earth metal oxide. In the carbonation device (300), a reaction such as the following Equation 6 may proceed to capture carbon dioxide from the synthesis gas components.

[0065] [Equation 6]

[0066] CaO + CO2 → CaCO3

[0067] If carbon dioxide in the product of the co-electrolysis device (200) is utilized without capture, unreacted carbon dioxide in the product remains when linked with the synthetic fuel production process, which reduces process efficiency during the pressurization and heating process, and may cause a problem where carbon dioxide is concentrated in the reactor during the synthetic fuel production process.

[0068] However, in one embodiment of the present invention, high-quality synthesis gas can be produced because carbon dioxide in the product is captured and discharged through chemical looping based on an alkaline earth metal oxide-containing material.

[0069] The temperature of the carbonator (300) may be 550 to 700°C, specifically 600 to 650°C. If the temperature of the carbonator (300) is less than 550°C, the carbonation reaction may not occur easily, and if it exceeds 700°C, the carbonate may decompose and the captured carbon dioxide may be re-emitted.

[0070] The carbonate produced in the carbonator (300) can be supplied to the calciner (400). Additionally, the synthesis gas remaining after producing carbonate in the carbonator (300) can be supplied to the gas-liquid separator (500) described later.

[0071] The above calcination device (400) receives oxygen from the above electrolysis device (200) and can regenerate the carbonate supplied from the above carbonation device (300) into an alkaline earth metal oxide-containing material by calcining it.

[0072] The above alkaline earth metal oxide-containing material is not particularly limited, but may be, for example, at least one selected from the group consisting of calcium oxide (CaO) and magnesium oxide (MgO).

[0073] The above carbonate is not particularly limited, but may be at least one selected from the group consisting of calcium carbonate (CaCO3) and magnesium carbonate (MgCO3), for example.

[0074] In addition, the alkaline earth metal oxide-containing material produced in the above calcination furnace (400) can be supplied back to the above carbonation furnace (300).

[0075] In the above calcination furnace (400), a reaction such as the following Equation 7 can proceed to produce carbon dioxide.

[0076] [Equation 7]

[0077] CaCO3 → CaO + CO2

[0078] Meanwhile, the operating temperature of the above-mentioned calcination furnace (400) may be 900°C or higher, specifically 900 to 1100°C. In the above temperature range, carbonates may be calcined and carbon dioxide may be regenerated. If the operating temperature of the above-mentioned calcination furnace (400) is less than 900°C, the calcination of carbonates may be insufficient, and pure oxygen combustion may not occur smoothly.

[0079] One embodiment of the present invention can maintain the internal temperature of the calcinerator (400) within the temperature range through the oxy-fuel combustion of methane. The oxy-fuel combustion of methane can produce carbon dioxide and water vapor as shown in Equation 8 below.

[0080] [Equation 8]

[0081] CH4 + 2O2 → CO2 + 2H2O

[0082] Additionally, the oxygen supplied to the above-mentioned calcination furnace (400) may be part of the oxygen produced in the above-mentioned co-electrolysis device (200). Chemical looping technology based on alkaline earth metal oxide-containing materials supplies a heat source through the pure oxygen combustion of methane in the calcination furnace (400) to recover high concentrations of carbon dioxide during the regeneration (CaCO3 → CaO + CO2) of the used adsorbent, but there is a limitation in that it is essential to operate an Air Separation Unit (ASU), which consumes a high amount of energy, to produce the pure oxygen used at this time.

[0083] However, in the present invention, the pure oxygen produced at the air electrode of the co-electrolysis device (200) is directly supplied to the calcination device (400) to reduce process costs and create added value by utilizing the surplus pure oxygen produced.

[0084] In one embodiment of the present invention, a methane supply unit (700) for supplying methane to the calcination unit (400) may be further included.

[0085] The molar ratio of methane and oxygen supplied to the above calcination furnace (400) is not particularly limited, but may be, for example, about 1:1 to 1:5.

[0086] In one embodiment of the present invention, a process for separating moisture from the synthesis gas discharged from the carbonator (300) may be additionally included.

[0087] Specifically, it may further include a cooler (510) for cooling the synthetic gas discharged from the carbonation unit, and may further include a gas-liquid separator (520) for removing water vapor cooled in the cooler (510).

[0088] The above cooler (510) is a device for removing water vapor contained in the above synthesis gas, and any device that cools water vapor can be a device commonly used in the industry.

[0089] The above gas-liquid separator (520) separates the cooled water vapor from the synthesis gas discharged from the cooler (510) and can obtain a synthesis gas mixed with hydrogen, carbon monoxide, carbon dioxide, etc. The molar ratio of carbon dioxide contained in the synthesis gas mixed with hydrogen, carbon monoxide, carbon dioxide, etc. may be less than 5 mol%.

[0090] The above gas-liquid separator (520) is not particularly limited to any conventional gas-liquid separator used in the industry.

[0091] A co-electrolysis system (10) of one embodiment of the present invention can convert about 95 mol% of the supplied carbon compound into carbon monoxide and discharge it, and can produce high-quality synthesis gas with a carbon dioxide concentration of less than 5 mol% and a molar ratio of hydrogen to carbon monoxide of about 1:1 to 4:1.

[0092] Meanwhile, the co-electrolysis system (10), which is an embodiment of the present invention, may further include a heat exchanger to heat carbon dioxide and water vapor supplied from a mixed gas supply unit (100) to a co-electrolysis device (200).

[0093] The above heat exchanger is not particularly limited as long as it is a heat exchanger commonly used in the industry.

[0094] Specifically, it may further include a first heat exchanger (810) that exchanges heat between the mixed gas discharged from the mixed gas supply unit (100) and the heat generated in the carbonation unit (300).

[0095] The first heat exchanger (810) may be placed inside the carbonator (300) or outside the carbonator (300).

[0096] The heat generated in the carbonator (300) above may be heat generated according to a reaction such as Equation 6 above.

[0097] Additionally, a second heat exchanger (820) may be further included to exchange heat between the mixed gas discharged from the mixed gas supply unit (100) and the synthetic gas discharged from the carbonation unit (300). Since the heat exchange in the first heat exchanger (810) is insufficient, the temperature of the synthetic gas discharged from the carbonation unit (300) may be sufficiently high. Accordingly, the second heat exchanger (820) can recover the heat of the synthetic gas discharged from the carbonation unit (300) through heat exchange between the mixed gas discharged from the mixed gas supply unit (100) and the synthetic gas discharged from the carbonation unit (300).

[0098] Furthermore, it may further include a third heat exchanger (830) that heat exchanges the mixed gas discharged from the mixed gas supply unit (100) with the alkaline earth metal oxide-containing material supplied from the calcination unit (400) to the carbonation unit.

[0099] The heat generated in the above-mentioned calcination furnace (400) may be heat generated according to the reaction of the above-mentioned formula 8.

[0100] One embodiment of the present invention can recover waste heat and efficiently heat the mixed gas supplied to the above-described electrolysis device by further including a heat exchanger as described above.

[0101] Examples

[0102] The present invention will be described in detail below through examples. However, it should be noted that the examples described below are intended merely to illustrate and embody the present invention and are not intended to limit the scope of the present invention. This is because the scope of the present invention is determined by the matters described in the patent claims and matters reasonably inferred therefrom.

[0103] 1. Example 1

[0104] 2.5 LPM (Liter per min) of hydrogen, 8.2 LPM of carbon dioxide, and 20.5 LPM of water vapor were supplied from a mixed gas supply to the co-electrolyzer, power was supplied so that the electrolysis rate of the reactants (H2O+CO2) was 69%, and the co-electrolyzer was operated at a pressure of 1 bar and a temperature of 750°C.

[0105] The products generated as a result of the co-electrolysis reaction—hydrogen 17 LPM, carbon monoxide 8.7 LPM, carbon dioxide 4.7 LPM, and water vapor 8 LPM—and 21.3 g / min of an alkaline earth metal oxide-containing substance equivalent to 1.8 times the molar amount of CO2 supplied were supplied to a carbonator, and 90 mol% of carbon dioxide was captured at a temperature of 650°C, and 17 LPM of hydrogen, 8.7 LPM of carbon monoxide, 0.5 LPM of carbon dioxide, and 8 LPM of water vapor were discharged from the carbonator.

[0106] Hydrogen, carbon monoxide, carbon dioxide, and water vapor discharged from the carbonator were passed through a gas-liquid separator to condense the water vapor, yielding product gases of 17 LPM hydrogen, 8.7 LPM carbon monoxide, and 0.5 LPM carbon dioxide, and separating 8 LPM of water vapor. The molar ratios of each component contained in the product gas corresponded to 65 mol% hydrogen, 33 mol% carbon monoxide, and 2 mol% carbon dioxide, and 95% of the carbon compounds (CO2+CH4) supplied to the system were converted into carbon monoxide.

[0107] The alkaline earth metal oxide-containing material (CaCO3:CaO=1:1) generated in the carbonator was transferred to the calciner at a rate of 29.6 g / min, and a heat source was supplied to the calciner by pure oxygen combustion of 1 LPM of supplied methane using 2 LPM of oxygen produced at the air electrode of the co-electrolyte. The calciner was heated to 900°C by the supply of the heat source, and a total of 5.2 LPM of carbon dioxide and 2 LPM of steam were produced by adding 4.2 LPM of carbon dioxide generated during the carbonate regeneration process to 1 LPM of carbon dioxide and 2 LPM of steam generated during the methane combustion process. The generated alkaline earth metal oxide-containing material was transferred back to the carbonator, and 5.2 LPM of carbon dioxide and 2.0 LPM of steam were transferred to a mixed gas supply unit and recycled.

[0108] 2. Comparative Example 1

[0109] As a result of the co-electrolysis reaction, 17 LPM of hydrogen, 8.7 LPM of carbon monoxide, 4.7 LPM of carbon dioxide, and 8 LPM of water vapor were produced. The water vapor was condensed through a gas-liquid separator to obtain product gases of 17 LPM of hydrogen, 8.7 LPM of carbon monoxide, and 4.7 LPM of carbon dioxide, and 8 LPM of water vapor was separated. The molar ratio of each component contained in the product gas was 56 mol% of hydrogen, 29 mol% of carbon monoxide, and 15 mol% of carbon dioxide, and 65% of the carbon compounds (CO2) supplied to the system were converted into carbon monoxide.

[0110] Although embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and it will be obvious to those skilled in the art that various modifications and variations are possible within the scope of the technical concept of the present invention as described in the claims.

[0111] (Explanation of symbols)

[0112] 10: Electrolysis System 100: Mixed Gas Supply Unit

[0113] 200: Electrolyze device 300: Carbonate

[0114] 400: Firing furnace 510: Cooler

[0115] 520: Gas-liquid separator 600: Oxygen storage tank

[0116] 700: Methane feeder 810: First heat exchanger

[0117] 820: 2nd heat exchanger 830: 3rd heat exchanger

Claims

1. A mixed gas supply unit that supplies a mixed gas containing carbon dioxide and water vapor; A co-electrolysis device that co-electrolyzes the above mixed gas to generate a synthesis gas containing carbon monoxide and hydrogen; A carbonator that mixes an alkaline earth metal oxide-containing material with the above synthesis gas and carbonates the alkaline earth metal oxide-containing material with carbon dioxide to obtain a carbonate; and A co-electrolysis system comprising a calcinerator that calcines the above carbonate to regenerate it into an alkaline earth metal oxide-containing material.

2. In Paragraph 1, The above alkaline earth metal oxide-containing material is at least one selected from the group consisting of calcium oxide (CaO) and magnesium oxide (MgO), in a co-electrolysis system.

3. In Paragraph 1, A co-electrolysis system in which the carbonate is at least one selected from the group consisting of calcium carbonate (CaCO3) and magnesium carbonate (MgCO3).

4. In Paragraph 1, A co-electrolysis system that supplies oxygen generated in the above co-electrolysis device to the above calcination furnace.

5. In Paragraph 1, The above-mentioned calciner is a co-electrolysis system that generates carbon dioxide and water vapor by combusting methane with pure oxygen.

6. In Paragraph 5, A co-electrolysis system in which carbon dioxide and water vapor generated in the above-mentioned calcination furnace are supplied to the above-mentioned co-electrolysis device.

7. In Paragraph 1, A co-electrolysis system in which the operating temperature of the above-mentioned calcination furnace is 900℃ or higher.

8. In Paragraph 1, A co-electrolysis system in which the calcium oxidizing agent produced in the above calcination furnace is supplied back to the above carbonation furnace.

9. In Paragraph 1, A co-electrolysis system further comprising a first heat exchanger that exchanges heat between the mixed gas discharged from the mixed gas supply unit and the heat generated in the carbonation unit.

10. In Paragraph 1, A co-electrolysis system further comprising a second heat exchanger for heat-exchanging the mixed gas discharged from the mixed gas supply unit and the synthesis gas discharged from the carbonation unit.

11. In Paragraph 1, A co-electrolysis system further comprising a third heat exchanger for heat-exchanging the mixed gas discharged from the mixed gas supply unit and the alkaline earth metal oxide-containing material supplied from the calcination unit to the carbonation unit.

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