Energy utilization system, and method for manufacturing carbon-containing material

Abstract

An energy utilization system and a method for manufacturing a carbon-containing material are provided that make it possible to obtain a carbon-containing material while suppressing release of carbon dioxide and reducing carbon dioxide. An energy utilization system (1) comprises: a heat utilization cycle (30) that has a high-temperature-utilizing heat exchange unit (36) for adjusting the temperature of a heat medium by utilizing energy obtained from renewable energy or waste heat, the heat utilization cycle (30) having a heat medium circulating therein; and an electrolytic reduction device (70) for electrolytically reducing an electrolytic solution in which carbon dioxide is dissolved. The electrolytic reduction device (70) electrolytically reduces the electrolytic solution of which the temperature has been adjusted by being in thermal contact with the heat medium. The electrolytic reduction device (70) includes: a cylindrical electrolytic cell casing (79) extending in a first direction; an anode (71) provided inside the electrolytic cell casing (79) and extending in the first direction; a cylindrical cathode (72) which is positioned inside the electrolytic cell casing (79) and outside the anode (71) when viewed in the first direction, and which extends in the first direction; and an electrolytic solution flow path (73) for allowing the electrolytic solution to flow in the first direction between the anode (71) and the cathode (72).

Description

Energy utilization system and method for producing carbon-containing material

[0001] The present invention relates to an energy utilization system and a method for producing a carbon-containing material.

[0002] In recent years, from the viewpoint of reducing carbon dioxide and other carbon dioxide as a measure against global warming, progress has been made in the development of carbon recycling technology, which involves reducing carbon dioxide to obtain carbon compounds and the like for reuse.

[0003] For example, Patent Document 1 (JP 2016-89230 A) proposes producing a carbon material by electrolytic reduction of carbon dioxide in a sealed reaction vessel. Furthermore, Patent Document 2 (JP 2023-15104 A) proposes producing carbon monoxide and various organic compounds (hydrocarbons, ethers, cyclic ethers, alcohols, or carbonyl compounds) by similarly electrolytic reduction of carbon dioxide.

[0004] Here, in order to produce a carbon-containing material from carbon dioxide with the aim of reducing carbon dioxide, it is desirable to efficiently electrolytically reduce carbon dioxide while suppressing the use of energy that would increase carbon dioxide.

[0005] An energy utilization system according to a first aspect includes a circulation circuit and an electrolytic reduction device. The circulation circuit has a temperature adjustment unit. A heat medium circulates through the circulation circuit. The temperature adjustment unit adjusts the temperature of the heat medium by utilizing renewable energy or energy obtained from exhaust heat. The electrolytic reduction device electrolytically reduces an electrolyte solution having dissolved carbon dioxide. The electrolytic reduction device electrolytically reduces the electrolyte solution whose temperature has been adjusted by thermal contact with the heat medium. The electrolytic reduction device has a casing, a first electrode, a second electrode, and an electrolyte flow path. The casing is cylindrical and extends in a first direction. The first electrode is provided inside the casing and extends in the first direction. The second electrode is cylindrical and extends in the first direction. The second electrode is located inside the casing and outside the first electrode when viewed in the first direction. The electrolyte flow path allows the electrolyte to flow in the first direction between the first electrode and the second electrode.

[0006] Here, renewable energy may be energy obtained by one or more types selected from the group consisting of, for example, solar power generation, wind power generation, hydroelectric power generation, biomass power generation, geothermal power generation, tidal power generation, hydrogen combustion power generation, and ammonia combustion power generation. This renewable energy may be unstable in that the amount of energy obtained is not constant depending on the time of day, etc., compared to energy such as electricity supplied via a major power network operated by a power company.

[0007] Here, the waste heat is not particularly limited, and examples thereof include heat discharged from thermal power plants, nuclear power plants, chemical plants, refineries, waste incineration plants, geothermal energy, hot spring water, and the like.

[0008] According to this energy utilization system, the temperature of a heat medium is adjusted using energy obtained from renewable energy or waste heat. The temperature-adjusted heat medium then circulates through a circulation circuit and thermally contacts the electrolyte, adjusting the temperature of the electrolyte containing dissolved carbon dioxide. This improves the reduction efficiency of the electrolyte. Furthermore, in the electrolyte flow path of the electrolytic reduction device, the electrolyte flows in a first direction between the first electrode and the second electrode. This makes it possible to perform electrolytic reduction of the electrolyte while continuously supplying the electrolyte between the first electrode and the second electrode. This also improves the reduction efficiency of the electrolyte, as it is easier to maintain a high concentration of carbon dioxide or carbonate ions in the electrolyte near the first electrode and the second electrode. Furthermore, since the temperature of the electrolyte can be adjusted using a temperature-adjusted heat medium utilizing energy obtained from renewable energy or waste heat during the electrolytic reduction of carbon dioxide, it is possible to reduce carbon dioxide emissions while suppressing carbon dioxide emissions.

[0009] An energy utilization system according to a second aspect is the energy utilization system according to the first aspect, wherein the first electrode is an anode and the second electrode is a cathode.

[0010] In this energy utilization system, carbon dioxide can be reduced at the cathode that is provided outside the anode when viewed in the first direction. Therefore, compared to when the cathode is provided inside the anode, when the cathode is provided outside the anode, a larger surface area of ​​the cathode can be ensured, and carbon dioxide can be reduced more efficiently.

[0011] An energy utilization system according to a third aspect is the energy utilization system according to the second aspect, wherein the anode is tubular and extends in a first direction. The electrolytic reduction device has a first gas flow path. The first gas flow path is provided inside the anode as viewed in the first direction, and allows gas generated by an oxidation reaction of the electrolytic solution to pass through.

[0012] In this energy utilization system, the gas generated by the oxidation reaction of the electrolyte is prevented from accumulating on the spot and is sent in the first direction, thereby making it possible to increase the efficiency of the oxidation reaction at the anode.

[0013] An energy utilization system according to a fourth aspect is the energy utilization system according to the third aspect, wherein the anode has an anode catalyst layer and an anode gas diffusion layer. The anode catalyst layer is cylindrical and extends in a first direction. The anode gas diffusion layer is provided inside the anode catalyst layer and outside the first gas flow path when viewed in the first direction. The anode gas diffusion layer is cylindrical and extends in the first direction.

[0014] In this energy utilization system, the oxidation reaction at the anode can be carried out efficiently.

[0015] An energy utilization system according to a fifth aspect is the energy utilization system according to any one of the second to fourth aspects, wherein the electrolytic reduction device has a second gas flow path. The second gas flow path is provided outside the cathode and inside the casing when viewed in the first direction, and allows gas generated by a reduction reaction of the electrolytic solution to pass through.

[0016] In this energy utilization system, the gas generated by the reduction reaction of the electrolyte is prevented from accumulating on the spot and is sent in the first direction, thereby making it possible to increase the efficiency of the reduction reaction at the cathode.

[0017] An energy utilization system according to a sixth aspect is the energy utilization system according to the fifth aspect, wherein the cathode has a cathode catalyst layer and a cathode gas diffusion layer. The cathode catalyst layer is cylindrical and extends in a first direction. The cathode gas diffusion layer is cylindrical and extends in the first direction. The cathode gas diffusion layer is provided outside the cathode catalyst layer and inside the second gas flow path when viewed in the first direction.

[0018] In this energy utilization system, the reduction reaction at the cathode can be carried out efficiently.

[0019] An energy utilization system according to a seventh aspect is the energy utilization system according to any one of the first to sixth aspects, further comprising a heat pump. The heat pump is driven by electricity generated from renewable energy. A first refrigerant circulates through the heat pump. The temperature adjustment unit adjusts the temperature of the heat medium using heat from the first refrigerant whose temperature has been adjusted by the heat pump.

[0020] In this energy utilization system, the heat pump is driven using electricity generated from renewable energy, and therefore the environmental load associated with driving the heat pump can be reduced.

[0021] An energy utilization system according to an eighth aspect is the energy utilization system according to any one of the first to seventh aspects, further comprising a heat engine. The heat engine generates electricity by utilizing heat from the heat medium. The electrolytic reduction device applies a voltage to the electrolyte by utilizing the electricity generated by the heat engine.

[0022] In this energy utilization system, the heat of the heat medium that is not used to adjust the temperature of the electrolyte is utilized to generate power, and the voltage obtained can be used for electrolytic reduction.

[0023] An energy utilization system according to a ninth aspect is the energy utilization system according to any one of the first to eighth aspects, wherein the circulation circuit has a storage unit. The storage unit stores heat of the heat medium as stored energy.

[0024] In this energy utilization system, even if the supply of renewable energy or exhaust heat is unstable at times, the instability can be alleviated by storing the heat of the heat medium as stored energy.

[0025] Even if the temperature of the heat medium flowing through the circulation circuit fluctuates due to instability in the renewable energy or energy obtained from exhaust heat, the temperature fluctuations can be leveled out, making it possible to utilize high-quality thermal energy. As a result, it becomes possible to adjust the temperature of the electrolyte to be electrolytically reduced to a temperature at which electrolytic reduction can proceed efficiently.

[0026] A tenth aspect of the present invention relates to a method for producing a carbon-containing material, the method comprising the steps of: adjusting the temperature of a heat medium circulating through a circulation circuit by using renewable energy or energy obtained from exhaust heat; adjusting the temperature of an electrolytic solution; and electrolytically reducing the temperature-adjusted electrolytic solution. The temperature-adjusted electrolytic solution is an electrolytic solution having carbon dioxide dissolved therein. The temperature of the electrolytic solution is adjusted by thermal contact with the heat medium. In the electrolytically reducing step, the electrolytic solution flows in a first direction between a first electrode extending in a first direction and a cylindrical second electrode extending in the first direction so as to surround the first electrode when viewed in the first direction.

[0027] Here, renewable energy may be energy obtained by one or more types selected from the group consisting of, for example, solar power generation, wind power generation, hydroelectric power generation, biomass power generation, geothermal power generation, tidal power generation, hydrogen combustion power generation, and ammonia combustion power generation. This renewable energy may be unstable in that the amount of energy obtained is not constant depending on the time of day, etc., compared to energy such as electricity supplied via a major power network operated by a power company.

[0028] Here, the waste heat is not particularly limited, and examples thereof include heat discharged from thermal power plants, nuclear power plants, chemical plants, refineries, waste incineration plants, geothermal energy, hot spring water, and the like.

[0029] In this method for producing a carbon-containing material, the temperature of a heat medium is adjusted using energy obtained from renewable energy or exhaust heat. The temperature-adjusted heat medium then circulates through a circulation circuit and thermally contacts the electrolyte, thereby adjusting the temperature of the electrolyte in which carbon dioxide has been dissolved. This improves the reduction efficiency of the electrolyte. Furthermore, the electrolytic reduction is performed while the electrolyte is flowing in a first direction between the first electrode and the second electrode. This makes it possible to perform the electrolytic reduction of the electrolyte while continuously supplying the electrolyte between the first electrode and the second electrode. This also makes it easier to maintain a high concentration of carbon dioxide or carbonate ions in the electrolyte near the first electrode and the second electrode, thereby improving the reduction efficiency of the electrolyte. Furthermore, in the electrolytic reduction of carbon dioxide, the temperature of the electrolyte is adjusted using a heat medium whose temperature is adjusted using energy obtained from renewable energy or exhaust heat, making it possible to reduce carbon dioxide while suppressing carbon dioxide emissions.

[0030] A method for producing a carbon-containing material according to an eleventh aspect is the method for producing a carbon-containing material according to the tenth aspect, wherein the first electrode is an anode and the second electrode is a cathode.

[0031] In this method for producing a carbon-containing material, carbon dioxide can be reduced at the cathode that is provided outside the anode when viewed in the first direction. Therefore, compared to when the cathode is provided inside the anode, when the cathode is provided outside the anode, a larger surface area of ​​the cathode can be ensured, and carbon dioxide can be reduced more efficiently.

[0032] A method for producing a carbon-containing material according to a twelfth aspect is the method for producing a carbon-containing material according to the tenth or eleventh aspect, wherein the temperature of the heat medium is adjusted by heat of a first refrigerant using a heat pump through which the first refrigerant circulates. The heat pump is driven by electricity generated by renewable energy.

[0033] In this method for producing a carbon-containing material, the heat pump is driven using electricity generated from renewable energy, thereby reducing the environmental load associated with driving the heat pump.

[0034] A method for producing a carbon-containing material according to a thirteenth aspect is the method for producing a carbon-containing material according to any one of the tenth to twelfth aspects, further comprising a step of generating electricity in a heat engine by utilizing heat from the heat medium. In the electrolytic reduction step, a voltage is applied to the electrolytic solution by utilizing the electricity generated by the heat engine.

[0035] In this method for producing a carbon-containing material, the heat of the heat medium that is not used to adjust the temperature of the electrolyte is utilized to generate electricity, and the electricity can be used for electrolytic reduction.

[0036] A fourteenth aspect of the present invention relates to the method for producing a carbon-containing material according to the thirteenth aspect, wherein the circulation circuit has a storage section that stores heat of the heat medium as stored energy.

[0037] In this method for producing a carbon-containing material, even if the supply of renewable energy or exhaust heat is unstable, the instability can be alleviated by storing the heat of the heat medium as stored energy.

[0038] Even if the temperature of the heat medium flowing through the circulation circuit fluctuates due to instability in the renewable energy or energy obtained from exhaust heat, the temperature fluctuations can be leveled out, making it possible to utilize high-quality thermal energy. As a result, it becomes possible to adjust the temperature of the electrolyte to be electrolytically reduced to a temperature at which electrolytic reduction can proceed efficiently.

[0039] The electrolytic reduction device according to Supplementary Note 1 is an electrolytic reduction device that performs electrolytic reduction of an electrolyte solution having carbon dioxide dissolved therein, and includes a cylindrical casing extending in a first direction, an anode provided inside the casing and extending in the first direction, a cylindrical cathode located inside the casing and outside the anode when viewed in the first direction, and extending in the first direction, and an electrolyte flow path that allows the electrolyte solution to flow in the first direction between the anode and the cathode.

[0040] It is a schematic configuration diagram of an energy utilization system according to a first embodiment. It is a schematic configuration diagram of a carbon dioxide treatment device. It is a partial cross-sectional view of an electrolytic reduction device as seen in the longitudinal direction. It is a schematic configuration diagram of a network used in a microgrid system.

[0041] The energy utilization system and the material manufacturing method according to this embodiment will be described below with reference to examples.

[0042] (1) First Embodiment The energy utilization system 1 is a system that uses renewable energy to obtain and utilize thermal energy, electricity, and carbon-containing materials, and as shown in FIG. 1, includes a heat pump 10, a heat engine 20, a heat utilization cycle 30, and a carbon dioxide treatment device 40.

[0043] (1-1) Heat Pump The heat pump 10 includes a first refrigerant circuit 11 filled with a first refrigerant. Examples of the first refrigerant that can be used include R1233zd(E), R1234yf, R1234ze(E), R1234ze(Z), R134a, R32, R410a, R245fa, water, and carbon dioxide. Using these first refrigerants can improve the efficiency of the operation of the heat pump 10 when heating the heat medium to a temperature range below 200°C. The first refrigerant circuit 11 includes a first compressor 12, a first high-temperature heat exchanger 13, an expansion valve 15, a first low-temperature heat exchanger 16, and a first intermediate heat exchanger 14.

[0044] The first compressor 12 uses, as its power source, renewable energy supplied via a renewable energy supply unit 91. Note that, for drive control of the heat pump 10, only the renewable energy supplied via the renewable energy supply unit 91 may be used as a power source, or both the renewable energy and power supplied from an electric power company may be used as power sources. Note that, when both renewable energy and power supplied from an electric power company are used, it is preferable that more power from the renewable energy be used than power supplied from the electric power company.

[0045] Renewable energy is energy obtained, for example, from solar power generation, wind power generation, hydroelectric power generation, biomass power generation, geothermal power generation, tidal power generation, hydrogen combustion power generation, ammonia combustion power generation, etc., and among these, solar power generation, wind power generation, and geothermal power generation are preferred because they allow for relatively steady power generation and also reduce the amount of carbon dioxide emitted.

[0046] The first high-temperature heat exchanger 13 heats the first heat medium and cools the first refrigerant by performing heat exchange between the first refrigerant flowing through the first high-temperature heat exchanger 13 and the first heat medium flowing through the high-temperature utilization heat exchange section 36 of the heat utilization cycle 30 without mixing with each other. The first refrigerant that has passed through the first high-temperature heat exchanger 13 is sent to the first intermediate heat exchange section 14a, where it exchanges heat with the first refrigerant flowing through the first intermediate heat exchanger 14 without mixing with each other. The first refrigerant that has passed through the first intermediate heat exchange section 14a is reduced in pressure by the expansion valve 15 and sent to the first low-temperature heat exchanger 16.

[0047] In the first low-temperature heat exchanger 16, heat is exchanged between the first refrigerant flowing through the first low-temperature heat exchanger 16 and the exhaust gas flowing through the exhaust heat supply unit 92, thereby heating the first refrigerant and cooling the exhaust gas. Note that the exhaust heat supply unit 92 may use high-temperature exhaust gas that is 80°C to 120°C and contains a large amount of carbon dioxide, such as combustion gas used in a factory, etc. Note that the amount of thermal energy of the exhaust heat supplied to the exhaust heat supply unit 92 is adjusted by an exhaust gas transport means (not shown).

[0048] The first refrigerant that has passed through the first low-temperature heat exchanger 16 is sent to the first intermediate heat exchanger 14. In the first intermediate heat exchanger 14, as described above, the first refrigerant flowing through the first intermediate heat exchange section 14a is heated by the first refrigerant that has passed through the first intermediate heat exchanger 14. The first refrigerant that has passed through the first intermediate heat exchanger 14 is drawn into the first compressor 12.

[0049] (1-2) Heat Engine The heat engine 20 includes a second refrigerant circuit 21 filled with a second refrigerant. Examples of the second refrigerant that can be used include R1233zd(E), R1234yf, R1234ze(E), R1234ze(Z), R134a, R32, R410a, R245fa, water, and carbon dioxide.

[0050] The second refrigerant circuit 21 includes a second pump 22 , a second high-temperature heat exchanger 23 , an expander 24 , a second low-temperature heat exchanger 26 , and a second intermediate heat exchanger 28 .

[0051] The second pump 22 forms a flow of the second refrigerant in the second refrigerant circuit 21. The second refrigerant flowing out of the second pump 22 is sent to the second high-temperature heat exchange section 23 via the second intermediate heat exchange section 28a.

[0052] The second high-temperature heat exchange unit 23 performs heat exchange between the second refrigerant flowing through the second high-temperature heat exchange unit 23 and the first heat medium flowing through the low-temperature utilization heat exchanger 34 of the heat utilization cycle 30 without mixing with each other, thereby heating the second refrigerant and cooling the first heat medium. The second refrigerant that has passed through the second high-temperature heat exchange unit 23 is sent to the expander 24. The second refrigerant sent to the expander 24 is decompressed and sent to the second intermediate heat exchanger 28. The expander 24 generates electricity using energy recovered when the second refrigerant is decompressed. The electricity generated by the expander 24 can be used as a power source for the first compressor 12 of the heat pump 10, a power source for voltage applied to the electrolytic reduction device 70, etc.

[0053] In the second intermediate heat exchanger 28, heat exchange occurs between the second refrigerant flowing through the second intermediate heat exchanger 28 and the second refrigerant flowing through the second intermediate heat exchange section 28a from the second pump 22 toward the second high-temperature heat exchange section 23, without the refrigerants being mixed with each other. The second low-temperature heat exchanger 26 exchanges heat between the second refrigerant flowing through the second low-temperature heat exchanger 26 and air supplied from outdoors via the second refrigerant cooling section 93. The second refrigerant that has passed through the second low-temperature heat exchanger 26 is sent to the second pump 22.

[0054] (1-3) Heat Utilization Cycle The heat utilization cycle 30 includes a heat utilization circuit 31 filled with a heat medium. From the viewpoint of enabling the storage of high-temperature thermal energy, the heat medium can be, for example, a mixed fluid containing sand or rock and air, water, thermal oil, ionic liquid, molten salt, or other latent heat storage materials. The heat utilization circuit 31 includes a heat medium pump 32, an electrolytic reduction temperature adjustment unit 33, a low-temperature utilization heat exchanger 34, a pressure line 38, a low-temperature tank 35, a high-temperature utilization heat exchange unit 36, and a high-temperature tank 37.

[0055] The heat medium pump 32 generates a flow that circulates the heat medium through the heat utilization cycle 30. The heat medium that has passed through the heat medium pump 32 is sent to the electrolytic reduction temperature adjustment unit 33. The electrolytic reduction temperature adjustment unit 33 passes through a constant temperature bath 33x in a constant temperature container 70x of the electrolytic reduction device 70 (described later). The constant temperature bath 33x is filled with a heat retention medium. The heat medium heats the heat retention medium in the constant temperature bath 33x. The heat retention medium heats the electrolytic solution in the electrolytic cell casing 79. The heat medium sent to the electrolytic reduction temperature adjustment unit 33 adjusts the temperature of the electrolytic solution by, for example, heating the electrolytic solution that is electrolytically reduced in the electrolytic reduction device 70.

[0056] The heat medium that has passed through the electrolytic reduction temperature adjustment unit 33 is sent to the low-temperature utilization heat exchanger 34. A pressure line 38 is connected between the electrolytic reduction temperature adjustment unit 33 and the low-temperature utilization heat exchanger 34, and pressurizes and injects the heat medium into the heat utilization circuit 31. The pressure line 38 is provided with an on-off valve 38a that can be controlled to open and close. The pressure line 38 pressurizes the heat medium circulating in the heat utilization circuit 31, thereby preventing the heat medium from vaporizing even at high temperatures. For example, when water is used as the heat medium, vaporization is prevented even at temperatures exceeding 100°C.

[0057] The low-temperature heat exchanger 34 heats the second refrigerant and cools the heat medium by performing heat exchange between the heat medium flowing through the low-temperature heat exchanger 34 and the second refrigerant flowing through the second high-temperature heat exchange section 23 of the heat engine 20 without mixing with each other. The heat medium that has passed through the low-temperature heat exchanger 34 is sent to the low-temperature tank 35. The temperature of the heat medium stored in the low-temperature tank 35 is, for example, 80°C or higher and 120°C or lower, and may be 90°C or higher and 110°C or lower. The heat medium that has passed through the low-temperature tank 35 is sent to the high-temperature heat exchange section 36.

[0058] The heat medium flowing through the high-temperature utilization heat exchange section 36 exchanges heat with the first refrigerant flowing through the first high-temperature heat exchanger 13 of the heat pump 10 without mixing with each other, and is heated. The heat medium that has passed through the high-temperature utilization heat exchange section 36 is sent to the high-temperature tank 37. The temperature of the heat medium stored in the high-temperature tank 37 is, for example, 120°C or higher and 150°C or lower, and may be 130°C or higher and 140°C or lower. The heat medium that has passed through the high-temperature tank 37 is sent to the heat medium pump 32.

[0059] It is preferable that both the low temperature tank 35 and the high temperature tank 37 are surrounded by a heat insulating material.

[0060] (1-4) Carbon Dioxide Treatment Device As shown in FIG. 2, the carbon dioxide treatment device 40 is a device for obtaining a carbon-containing material by dissolving carbon dioxide in an electrolyte, recovering the carbon dioxide, heating the electrolyte to an appropriate temperature using a heat medium circulating in the heat utilization cycle 30, and performing electrolytic reduction.

[0061] The carbon dioxide treatment device 40 includes a carbon dioxide recovery device 50, an electrolytic reduction device 70, an electrolyte pump 42, and an electrolyte heat exchanger 43, and is provided with an electrolyte circuit 41 through which the electrolyte circulates.

[0062] The electrolyte pump 42 takes in and delivers the electrolyte, thereby circulating the electrolyte within the electrolyte circuit 41. The electrolyte flowing out from the electrolyte pump 42 is cooled in the electrolyte heat exchanger 43 by heat exchange with a cooling medium such as water or air supplied from an external cooling source to the electrolyte cooling unit 94. The temperature of the cooling medium supplied to the electrolyte cooling unit 94 may be, for example, 15°C or higher and 35°C or lower, and preferably 20°C or higher and 30°C or lower. The cooled electrolyte is sent to the carbon dioxide capture device 50. Because the electrolyte sent to the carbon dioxide capture device 50 is sufficiently cooled, the carbon dioxide captured in the carbon dioxide capture device 50 is easily dissolved in the electrolyte. The electrolyte with carbon dioxide dissolved in the carbon dioxide capture device 50 is sent to the electrolytic reduction device 70. The carbon dioxide contained in the electrolyte sent to the electrolytic reduction device 70 is electrolytically reduced to become a carbon-containing substance.

[0063] The electrolyte can be selected from the group consisting of imidazolium-based ionic liquids, aromatic-based ionic liquids, pyrrolidinium-based ionic liquids, ammonium-based ionic liquids, piperidinium-based ionic liquids, and quaternary phosphonium-based ionic liquids. The electrolyte can be an ionic liquid with high carbon dioxide solubility and low viscosity, or an ionic liquid solution containing an aqueous solution containing additives such as a supporting electrolyte or a basic catalyst. The electrolyte can be one with a sufficiently wide electrochemical window for the electrolytic reaction of carbon dioxide and water.

[0064] Examples of ionic liquids constituting such preferred electrolytes include [BuMePyrr][TFO], [BMIm][TFO], [DEME][BF4], [P2225][TFSI], [BMIM][BF4], [BMIM][TFSI], and [PP13][TFSI]. Examples of supporting electrolytes include MCl, M ２ CO ３ , M.H.C.O. ３ , MBF ４ , MPF ６, MClO ４ , MAsF ６ ,MTf,MTFSI,M(CF ３ SO ２ ) ２ N, M.H.P.O. ４ (M=Li, Na, K, Rb, Cs), etc. Examples of basic catalysts include LiOH, NaOH, KOH, CsOH, and Ca(OH). ２ and the like. Such an electrolyte solution is preferable not only because it can be operated at room temperature but also because it can be operated in a high-temperature environment of 80°C or higher and 150°C or lower to increase efficiency. In addition, such an electrolyte solution is preferable because it has a high carbon dioxide absorption capacity and enables continuous recovery and decomposition of carbon dioxide. Furthermore, such an electrolyte solution is preferable because it is liquid at room temperature and has a relatively low vapor pressure, so that there is little dissipation or loss of the electrolyte solution due to evaporation during operation, and the air sent out to the outside of the device does not substantially contain chemical substances derived from the electrolyte solution other than water vapor.

[0065] (1-4-1) Carbon Dioxide Capture Device The carbon dioxide capture device 50 is a device that captures carbon dioxide supplied from the outside via a carbon dioxide supply line 81 and dissolves it in an electrolytic solution. The carbon dioxide supply line 81 is a flow path for capturing carbon dioxide from exhaust gases containing a large amount of carbon dioxide, such as combustion gases used in factories, etc. In this embodiment, in addition to carbon dioxide, gases containing moisture also flow through the carbon dioxide supply line 81, and these gases are supplied to the carbon dioxide capture device 50. In this case, the gas may be ambient air containing a low concentration of carbon dioxide. The amount of carbon dioxide supplied to the carbon dioxide supply line 81 is adjusted by a carbon dioxide transport means (not shown).

[0066] The carbon dioxide recovery device 50 has a plurality of absorption flow paths 51 through which the electrolyte passes, a plurality of carbon dioxide flow paths 52 through which carbon dioxide supplied from the carbon dioxide supply line 81 passes, and hollow fiber membranes 53 provided between each absorption flow path 51 and each carbon dioxide flow path 52.

[0067] In the carbon dioxide capture device 50, the direction in which the electrolyte flows through the absorption flow path 51 and the direction in which carbon dioxide flows through the carbon dioxide flow path 52 are configured to be opposite to each other. This allows the electrolyte to take in more carbon dioxide that has passed through the hollow fiber membrane 53 as it progresses through the absorption flow path 51. The carbon dioxide-containing electrolyte may be an electrolyte having carbon dioxide gas dissolved therein, an electrolyte having carbonate ions or bicarbonate ions, or an electrolyte having carbon dioxide gas dissolved therein and having carbonate ions or bicarbonate ions.

[0068] The electrolyte that has absorbed a large amount of carbon dioxide flows through the electrolyte circuit 41 and is supplied to the electrolytic reduction device 70. Downstream of the carbon dioxide flow path 52, clean air with a reduced carbon dioxide concentration is collected in an air outflow line 82 and sent out to the outside of the carbon dioxide capture device 50.

[0069] (1-4-2) Electrolytic Reduction Device The electrolytic reduction device 70 is a device that obtains a carbon-containing material by electrolytically reducing an electrolyte solution containing carbon dioxide. Note that the electrolytic reduction device 70 of this embodiment preferably does not use a solid electrolyte membrane.

[0070] As shown in FIG. 2 and FIG. 3, which is a cross-sectional view of the S-S cross section in FIG. 2, the electrolytic reduction device 70 includes an electrolytic cell casing 79, a thermostatic chamber 33x, a thermostatic container 70x, an anode 71, a cathode 72, an electrolyte flow path 73, a first recovery path 83, and a second recovery path 84.

[0071] An electrolytic solution containing carbon dioxide passes through the electrolytic cell casing 79. The electrolytic cell casing 79 is configured in a generally cylindrical shape with the longitudinal direction of the electrolytic solution being the axial direction. The interior of the electrolytic cell casing 79 has an upstream region 77 to which the electrolytic solution that has flowed out of the carbon dioxide capture device 50 is supplied, and a downstream region 78 through which the electrolytically reduced electrolytic solution passes before flowing out of the electrolytic cell casing 79.

[0072] The thermostatic container 70x accommodates the electrolytic cell casing 79, the thermostatic bath 33x, and the electrolytic reduction temperature control unit 33 in the heat utilization cycle 30. The thermostatic bath 33x is configured by filling the interior of the thermostatic container 70x and the exterior of the electrolytic cell casing 79 with a heat retention medium. The heat retention medium is not particularly limited and may be water, metal, or the like. The heat retention medium in the thermostatic bath 33x is heated by heat exchange with the heat medium flowing through the electrolytic reduction temperature control unit 33 in the heat utilization cycle 30. This heated heat retention medium heats the electrolytic solution inside the electrolytic cell casing 79 by thermally contacting the electrolytic cell casing 79. This adjusts the temperature of the electrolytic solution to a temperature at which electrolytic reduction can be efficiently performed.

[0073] The anode 71 is provided inside the electrolytic cell casing 79, near the center of the electrolytic cell casing 79 as viewed in the longitudinal direction. The anode 71 extends along the longitudinal direction of the electrolytic cell casing 79, between an upstream region 77 and a downstream region 78 of the electrolytic cell casing 79. An anode recovery channel 71x is provided radially inward of the anode 71 as viewed in the longitudinal direction of the electrolytic cell casing 79. The anode 71 has an anode gas diffusion layer 71b provided in a cylindrical shape radially outward of the anode recovery channel 71x, and an anode catalyst layer 71a provided in a cylindrical shape radially outward of the anode gas diffusion layer 71b. The anode recovery channel 71x, the anode gas diffusion layer 71b, and the anode catalyst layer 71a all extend along the longitudinal direction of the electrolytic cell casing 79. The anode recovery path 71x radially penetrates part of the electrolyte flow path 73 and part of the cathode 72, and also has a portion that extends radially outward so as to radially penetrate the frame portion of the electrolytic cell casing 79, thereby connecting to the anode connection part 71c. The anode connection part 71c is connected to a first recovery path 83. The position of the anode connection part 71c is not particularly limited, and may be located, for example, on the upstream side of the electrolytic cell casing 79.

[0074] At the anode 71, an oxidation reaction of water occurs, as shown in the following formula (1), to generate oxygen and hydrogen ions. ２ O → 4H＋ +O ２ +4e － ...(1)

[0075] As the anode catalyst layer 71a, from the viewpoints of generating oxidation reaction products at high current density, being stable against oxidation reactions, and easily ensuring a large surface area, it is possible to preferably use silver fine particles, platinum mesh, porous nickel, carbon felt, etc.

[0076] As the anode gas diffusion layer 71b, graphite or the like can be preferably used from the viewpoints of being bonded to the catalyst layer with high strength, having high electrical conductivity, having small and uniform particles, and having excellent isotropy.

[0077] The cathode 72 is tubular and disposed outside the outer periphery of the anode 71 and inside the outer frame of the electrolytic cell casing 79 when viewed in the longitudinal direction of the electrolytic cell casing 79. The cathode 72 extends cylindrically along the longitudinal direction of the electrolytic cell casing 79 between an upstream region 77 and a downstream region 78 of the electrolytic cell casing 79. The cathode 72 has a cathode catalyst layer 72a that forms the inner circumferential portion of the cathode 72, and a cathode gas diffusion layer 72b that is disposed radially outward of the cathode catalyst layer 72a and has a cylindrical shape inside the frame of the electrolytic cell casing 79 when viewed in the longitudinal direction of the electrolytic cell casing 79. The cathode catalyst layer 72a, the cathode gas diffusion layer 72b, and the cathode recovery channel 72x all extend along the longitudinal direction of the electrolytic cell casing 79. The cathode recovery channel 72x penetrates the frame portion of the electrolytic cell casing 79 radially outward and is connected to the cathode connecting portion 72c. The cathode connecting portion 72c is connected to the second recovery channel 84. The position of the cathode connecting portion 72c is not particularly limited, and may be located, for example, on the downstream side of the electrolytic cell casing 79.

[0078] At the cathode 72, a reduction reaction of carbon dioxide occurs. Specifically, as shown in the following formula (2), carbon dioxide reacts with hydrogen ions and electrons to produce carbon monoxide and water, which are carbon-containing substances. Depending on the electrolysis conditions, hydrogen may also be produced. ２ +4H ＋ +4e － → 2CO + 2H ２ O...(2)

[0079] As the cathode catalyst layer 72a, for example, a composite material film containing a high proportion of Cu nanocrystals having a (100) plane can be preferably used.

[0080] The cathode gas diffusion layer 72b can be preferably made of graphite or the like, from the viewpoints of being strongly bonded to the catalyst layer, having high electrical conductivity, having small and uniform particles, and having excellent isotropy.

[0081] In this embodiment, the cathode 72 is provided in a cylindrical shape radially outward of the anode 71, and therefore, a structure can be achieved in which the surface area where the reduction reaction occurs in the cathode 72 is more likely to be larger than the surface area where the oxidation reaction occurs in the anode 71. This makes it possible to efficiently obtain carbon-containing materials by reducing carbon dioxide.

[0082] The electrolyte flow path 73 is a tubular portion provided outside the anode 71 and inside the cathode 72 when viewed in the longitudinal direction of the electrolytic cell casing 79, and is a cylindrical portion through which the electrolyte flows along the longitudinal direction of the electrolytic cell casing 79. When the electrolyte passes through this electrolyte flow path 73, a voltage is applied to the anode 71 and the cathode 72, thereby electrolyzing the electrolyte. Note that the flow of the electrolyte in the electrolyte flow path 73 is formed by the electrolyte pump 42, so that the unelectrolyzed electrolyte is continuously supplied to the electrolyte flow path 73, and the electrolyzed electrolyte can be discharged from the electrolyte flow path 73. This enables efficient electrolytic reduction.

[0083] The first recovery path 83 is connected to the anode connection part 71c, and is a flow path that sends and recovers to the outside the products produced by electrolysis of the electrolytic solution at the anode 71. An open / close valve 83a is provided midway along the first recovery path 83. Note that the first recovery path 83 may be provided with a pressure reducing pump (not shown) or the like as needed, making it possible to recover reaction products and the like.

[0084] The second recovery path 84 is connected to the cathode connecting portion 72c, and is a flow path that sends and recovers to the outside the products produced by electrolysis of the electrolytic solution in the cathode 72. An open / close valve 84a is provided midway along the second recovery path 84. If necessary, the second recovery path 84 may be provided with a pressure reducing pump (not shown) or the like, which makes it possible to recover reaction products and the like.

[0085] The power of the voltage applied to the anode 71 and the cathode 72 during electrolytic reduction can be the power obtained by the expander 24 .

[0086] (1-5) Features of the First Embodiment According to the energy utilization system 1 of this embodiment, the heat pump 10 is driven by renewable energy. Compared to electricity provided by a general power company, the amount of renewable energy obtained is not constant depending on the time of day, etc., and there is a risk of the supply being unstable. However, the heat pump 10 converts the renewable energy into heat that is stored in the heat utilization cycle 30, making it possible to fully and effectively utilize the renewable energy.

[0087] Furthermore, according to the energy utilization system 1, the heat pump 10 uses the heat stored in the heat utilization cycle 30 to heat the second refrigerant, thereby recovering power in the expander 24 to generate electricity. The power obtained in the expander 24 can then be used to apply voltage to the electrolytic reduction device 70.

[0088] Furthermore, according to the energy utilization system 1, the heat stored in the heat utilization cycle 30 by the heat pump 10 can be used to heat the electrolyte in the electrolytic reduction device 70, thereby adjusting the temperature of the electrolyte. In this embodiment, by heating the electrolyte, it is possible to lower the absolute value of the potential required for electrolytic reduction, and also to increase the conductivity of the electrolyte by reducing its viscosity. These factors make it possible to improve the efficiency of electrolytic reduction.

[0089] Moreover, the electrolytic reduction device 70 makes it possible to obtain carbon-containing materials using carbon dioxide derived from exhaust gas or dilute carbon dioxide in the atmosphere.

[0090] As a result, it is possible to reduce the environmental load caused by carbon dioxide, effectively utilize renewable energy, and efficiently obtain useful carbon-containing substances derived from carbon dioxide.

[0091] In the present embodiment, the cathode 72 in the electrolytic reduction device 70 is provided in a cylindrical shape radially outward of the anode 71, and has a surface area that is sufficiently larger than that of the anode 71. This makes it possible to efficiently obtain carbon-containing materials obtained by reducing carbon dioxide.

[0092] Furthermore, the electrolytic reduction device 70 is configured such that an electrolytic solution is continuously supplied between the anode 71 and the cathode 72, and the electrolyzed electrolytic solution is continuously discharged. This prevents the surface of the anode 71 from being continuously covered with substances produced by the reaction, and also prevents the surface of the cathode 72 from being continuously covered with substances produced by the reaction, making it possible to perform electrolysis continuously and efficiently.

[0093] (2) Other Embodiments (2-1) Other Embodiment A In the above embodiment, the case where carbon monoxide is obtained as the carbon-containing substance has been described as an example.

[0094] In contrast, the carbon-containing material obtainable by reducing carbon dioxide is not particularly limited, and by changing various conditions such as the electrolyte and electrode material, it is possible to obtain, for example, one or more materials selected from the group consisting of carbon monoxide, diamond, graphite, glassy carbon, amorphous carbon, carbon nanotubes, carbon nanohorns, graphene, and metal carbides.

[0095] Furthermore, when the electrolytic solution to be electrolyzed contains water in addition to carbon dioxide, various organic compounds can be obtained by electrolytic reduction.

[0096] Examples of the organic compound include hydrocarbons, ethers, cyclic ethers, alcohols, and carbonyl compounds. More specifically, examples of the organic compound include one or more compounds selected from the group consisting of methane, methanol, ethane, ethylene, acetylene, ethanol, formic acid, formaldehyde, oxalic acid, acetic acid, propane, propylene, propanol, butane, butene, butanol, acetone, benzene, toluene, and xylene.

[0097] Furthermore, when the electrolytic solution to be electrolyzed further contains nitrogen, it is also possible to obtain amines and the like.

[0098] (2-2) Alternative Embodiment B In the above embodiment, an example was described in which one electrolytic reduction device 70 was provided for the flow of the electrolyte.

[0099] Alternatively, a plurality of electrolytic reduction devices 70 may be arranged in parallel with the flow of the electrolytic solution, which increases the number of locations where electrolytic reduction is performed, thereby enabling adjustment of the treatment scale.

[0100] (2-3) Other Embodiment C In the energy utilization system 1 according to the above embodiment, the first refrigerant circulating through the heat pump 10 driven by renewable energy heats the heat medium circulating through the heat utilization cycle 30, and the heat medium circulating through the heat utilization cycle 30 heats the electrolyte in the electrolytic reduction device 70.

[0101] In contrast, the energy utilization system 1 is not limited to a system that heats the electrolyte of the electrolytic reduction device 70, but may also cool the electrolyte of the electrolytic reduction device 70, or may be configured to be able to switch between heating and cooling the electrolyte of the electrolytic reduction device 70.

[0102] In this case, the first refrigerant circulating through the heat pump 10 driven by renewable energy may be one that cools the heat medium circulating through the heat utilization cycle 30, or may be configured to be able to switch between heating and cooling.

[0103] By suppressing the temperature rise of the electrolyte, it is possible to minimize the decrease in the solubility of the electrolyte in carbon dioxide, and if a side reaction occurs during electrolytic reduction, it is possible to minimize the reaction rate of the side reaction.

[0104] Furthermore, in order to cool the electrolyte, a flow path may be provided through which a cooling medium such as water or air supplied from an external cooling source passes through the thermostatic bath 33x in the thermostatic container 70x.

[0105] (2-4) Other Embodiment D The form of use of the energy utilization system 1 of the first embodiment is not particularly limited, and it can be used in, for example, a microgrid system.

[0106] A microgrid system is an energy system that integrates and operates distributed energy resources (DERs), such as distributed energy and energy storage facilities, with an energy network on a certain scale. For example, a microgrid system may be a system that is completely disconnected from the main power network operated by a power company and always operates independently, or a system that is connected to the main power network operated by a power company under normal circumstances and disconnected from the network in an emergency such as a disaster and operates independently.

[0107] FIG. 4 shows an example of a network configuration of a microgrid system including the energy utilization system 1 of the first embodiment.

[0108] The microgrid system may include, for example, a renewable energy supply unit 91 such as a solar power plant, a wind power plant, a hydroelectric power plant, or the like, a renewable energy management device 180 that manages renewable energy, a heat pump 10, a heat engine 20, a heat utilization cycle 30, an exhaust heat supply unit 92, a carbon dioxide treatment device 40 including a carbon dioxide recovery device 50 and an electrolytic reduction device 70, an emission supply unit (not shown) such as a thermal power plant, a nuclear power plant, a plant, a hot spring, or the like, an emission management device 150 that manages the emission supply unit, consumer equipment (not shown) that consumes the electric energy generated by the heat engine 20, consumer terminals 160 that manage the consumer equipment, energy network equipment (not shown) that connects these facilities, an energy management controller 100 that appropriately controls the supply and consumption of energy, and a communication network 111 that communicatively connects the renewable energy management device 180, the consumer terminals 160, the energy management controller 100, and the like.

[0109] The renewable energy management device 180 includes a processor 181 such as a CPU, a memory 182 such as a ROM or a RAM, an electric energy amount grasping unit 183 that grasps the amount of electric power generated in the renewable energy supply unit 91, and the like, and is disposed in the renewable energy supply unit 91. The renewable energy management device 180 is connected to the energy management controller 100 via the communication network 111 so as to be able to communicate with the energy management controller 100.

[0110] The emission management device 150 has a processor 151 such as a CPU, a memory 152 such as a ROM or RAM, a thermal energy amount grasping unit 153, and an emission carbon dioxide amount grasping unit 154, and is disposed in an emission supply unit of a thermal power plant, a nuclear power plant, or the like. The emission management device 150 is communicably connected to the energy management controller 100 via a communication network 111. The thermal energy amount grasping unit 153 grasps the amount of thermal energy emitted from the emission supply unit of the thermal power plant, the nuclear power plant, or the like. The emission carbon dioxide amount grasping unit 154 grasps the amount of carbon dioxide emitted from the emission supply unit of the thermal power plant, or the like.

[0111] The consumer equipment is equipment that consumes the remaining electrical energy generated by the heat engine 20 after use in the electrolytic reduction device 70, the remaining thermal energy obtained by the heat pump 10 after use in the electrolytic reduction device 70, or both. Examples of such equipment include factories, office buildings, homes, power supply devices for electric vehicles, and plant factories. For example, the heat stored in the heat utilization cycle 30 is supplied to factories, office buildings, homes, and plant factories in response to requests from these facilities. Heat may be supplied to the consumer by transporting a heat storage material capable of storing heat to the location of the consumer equipment. Furthermore, the electrical energy generated by the heat engine 20 is supplied to factories, office buildings, homes, power supply devices for electric vehicles, and plant factories in response to requests from these facilities. Electric energy may be supplied by transporting it to the location of the consumer equipment using electric wires, storage batteries, or the like. These heat storage materials, electric wires, and storage batteries are used as energy network equipment. In response to requests from customers, the carbon-containing material obtained in the electrolytic reduction device 70 is supplied by transportation or the like.

[0112] The customer terminal 160 has a processor 161 such as a CPU, a memory 162, an input unit 163, etc., and is disposed in the customer facility. The customer terminal 160 is communicatively connected to the energy management controller 100 via the communication network 111. The input unit 163 is configured with a touch panel, a keyboard, etc., and receives at least one of a request for thermal energy supply, a request for electric energy supply, and a request for carbon-containing materials obtained by electrolytic reduction from the customer who is the owner of the customer terminal 160.

[0113] The energy management controller 100 has a processor 101 such as a CPU (Central Processing Unit) and memory 102 such as ROM and RAM. The energy management controller 100 is communicably connected to the heat pump 10, the heat engine 20, the heat utilization cycle 30, the exhaust heat supply unit 92, the carbon dioxide treatment device 40 including the carbon dioxide capture device 50 and the electrolytic reduction device 70, etc. The energy management controller 100 controls the operation of the heat pump 10, the heat engine 20, the heat utilization cycle 30, the exhaust heat supply unit 92, the carbon dioxide treatment device 40 including the carbon dioxide capture device 50 and the electrolytic reduction device 70, etc. based on various information received via a communication network 111.

[0114] The energy management controller 100 controls the rotation speed of the first compressor 12 of the heat pump 10 to convert the electric energy into stored thermal energy based on the amount of electric energy grasped by the renewable energy supply unit 91 of the renewable energy management device 180. Although the amount of renewable energy obtained by the renewable energy management device 180 tends to be more unstable than general electric energy provided by electric power companies, the energy supplied as renewable energy can be converted into thermal energy via the heat pump 10 and stored in the heat utilization cycle 30. The thermal energy stored in the heat medium in the heat utilization cycle 30 can then be used to electrolytically reduce the electrolyte in the electrolytic reduction device 70. Specifically, the thermal energy stored in the heat medium in the heat utilization cycle 30 is used to heat the electrolyte in the electrolytic reduction device 70, and the electric energy converted by the heat engine 20 from the thermal energy stored in the heat utilization cycle 30 is used to apply a voltage to the electrolyte in the electrolytic reduction device 70. This makes it possible to provide the energy required for heating and applying voltage to the electrolyte in the electrolytic reduction device 70 with the energy stored in the heat utilization cycle 30, rather than with unstable renewable energy, and to perform electrolytic reduction stably. Specifically, various data such as the desired temperature of the electrolyte to be electrolytically reduced in the electrolytic reduction device 70 and the desired applied voltage are stored in advance in the memory 102 provided in the energy management controller 100, and the flow rate of the heat medium in the heat medium pump 32, the flow rate of the electrolyte in the electrolyte pump 42, the amount of cold supplied to the electrolyte cooling unit 94, etc. are controlled based on this data so that the temperature conditions and applied voltage conditions of the electrolyte are satisfied.

[0115] In addition, the energy management controller 100 adjusts the amount of thermal energy of exhaust heat supplied to the exhaust heat supply unit 92 by controlling the exhaust gas transportation means, etc., based on the amount of thermal energy discharged from the exhaust supply unit of a thermal power plant, nuclear power plant, etc., as determined by the thermal energy amount determination unit 153, and information on the rotation speed control of the first compressor 12.

[0116] Furthermore, the energy management controller 100 adjusts the amount of carbon dioxide supplied to the carbon dioxide supply line 81 by controlling carbon dioxide transportation means, etc., based on the amount of carbon dioxide emitted from an exhaust supply unit such as a thermal power plant, as determined by the carbon dioxide emission amount determination unit 154.

[0117] In addition, when the amount of heat energy grasped by the heat energy amount grasping unit 153 is sufficient, the energy management controller 100 can improve operating efficiency by heating the first refrigerant in the first intermediate heat exchanger 14 of the heat pump 10 or by heating the heat medium in the low-temperature tank 35 and the high-temperature tank 37 of the heat utilization cycle 30.

[0118] (Note) Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure as defined in the claims.

[0119] 1 Energy utilization system 10 Heat pump 12 First compressor 13 First high-temperature heat exchanger 15 Expansion valve 20 Heat engine 23 Second high-temperature heat exchange section 24 Expander 30 Heat utilization cycle (circulation circuit) 32 Heat medium pump 34 Low-temperature utilization heat exchanger 35 Low-temperature tank 36 High-temperature utilization heat exchange section (temperature adjustment section) 37 High-temperature tank (storage section) 40 Carbon dioxide treatment device 41 Electrolyte circuit 42 Electrolyte pump 43 Electrolyte heat exchanger 50 Carbon dioxide recovery device 70 Electrolytic reduction device 70x Thermostatic container 71 Anode (first electrode) 71x Anode recovery path (first gas flow path) 71a Anode catalyst layer 71b Anode gas diffusion layer 72 Cathode (second electrode) 72a Cathode catalyst layer 72b Cathode gas diffusion layer 72x Cathode recovery path (second gas flow path) 73 Electrolyte flow path 79 Electrolyzer casing (casing) 81 Carbon dioxide supply line 82 Air outflow line 83 First recovery path 84 Second recovery path 91 Renewable energy supply unit 92 Exhaust heat supply unit 93 Second refrigerant cooling unit 94 Electrolyte cooling unit 100 Energy management controller

[0120] JP 2016-89230 A JP 2023-15104 A

Claims

1. An energy utilization system (1) having a temperature adjustment unit (36) that adjusts the temperature of a heat medium by utilizing energy obtained from renewable energy or exhaust heat, the energy utilization system including: a circulation circuit (30) through which the heat medium circulates; and an electrolytic reduction device (70) that electrolytically reduces an electrolyte having dissolved carbon dioxide, the electrolytic reduction device electrolytically reducing the electrolyte whose temperature has been adjusted by thermal contact with the heat medium, the electrolytic reduction device having: a cylindrical casing (79) extending in a first direction; a first electrode (71) provided inside the casing and extending in the first direction; a cylindrical second electrode (72) extending in the first direction, the second electrode being located inside the casing and outside the first electrode as viewed in the first direction; and an electrolyte flow path (73) through which the electrolyte flows in the first direction between the first electrode and the second electrode.

2. The energy utilization system according to claim 1, wherein the first electrode is an anode, and the second electrode is a cathode.

3. The energy utilization system described in claim 2, wherein the anode is cylindrical and extends in the first direction, and the electrolytic reduction device is provided inside the anode when viewed in the first direction and has a first gas flow path (71x) for passing gas generated by an oxidation reaction of the electrolyte.

4. The energy utilization system described in claim 3, wherein the anode has a cylindrical anode catalyst layer (71a) extending in the first direction, and a cylindrical anode gas diffusion layer (71b) extending in the first direction, which is provided inside the anode catalyst layer and outside the first gas flow path when viewed in the first direction.

5. An energy utilization system as described in any one of claims 2 to 4, wherein the electrolytic reduction device has a second gas flow path (72x) that is provided outside the cathode and inside the casing when viewed in the first direction, and that allows gas generated by a reduction reaction of the electrolyte to pass through.

6. The energy utilization system described in claim 5, wherein the cathode has a cylindrical cathode catalyst layer (72a) extending in the first direction, and a cylindrical cathode gas diffusion layer (72b) extending in the first direction, which is provided outside the cathode catalyst layer and inside the second gas flow path when viewed in the first direction.

7. An energy utilization system as described in any one of claims 1 to 6, further comprising a heat pump (10) driven by electricity generated by the renewable energy and through which a first refrigerant circulates, wherein the temperature adjustment unit adjusts the temperature of the heat medium by the heat of the first refrigerant, the temperature of which has been adjusted by the heat pump.

8. The energy utilization system according to any one of claims 1 to 7, further comprising a heat engine (20) that generates electricity by utilizing the heat of the heat medium, and the electrolytic reduction device applies a voltage to the electrolyte by utilizing the electricity generated by the heat engine.

9. The energy utilization system according to any one of claims 1 to 8, wherein the circulation circuit has a storage section (37) for storing the heat of the heat medium as stored energy.

10. A method for producing a carbon-containing material, comprising: a step of adjusting the temperature of a heat medium circulating in a circulation circuit (30) by utilizing renewable energy or energy obtained from exhaust heat; a step of adjusting the temperature of an electrolyte having dissolved carbon dioxide by thermally contacting the heat medium; and a step of electrolytically reducing the temperature-adjusted electrolyte, wherein in the electrolytic reduction step, the electrolyte flows in the first direction between a first electrode (71) extending in a first direction and a cylindrical second electrode (72) extending in the first direction so as to surround the first electrode when viewed in the first direction.

11. The method for producing a carbon-containing material according to claim 10, wherein the first electrode is an anode, and the second electrode is a cathode.

12. A method for producing a carbon-containing material as described in claim 10 or 11, wherein the temperature of the heat medium is adjusted by the heat of a first refrigerant using a heat pump (10) in which the first refrigerant circulates, and the heat pump is driven using electricity generated by the renewable energy.

13. A method for producing a carbon-containing material described in any one of claims 10 to 12, further comprising a step of generating electricity in a heat engine (20) by utilizing heat from the heat medium, and in the electrolytic reduction step, a voltage is applied to the electrolyte by utilizing the electricity generated by the heat engine.

14. The method for producing a carbon-containing material according to claim 13, wherein the circulation circuit has a storage section (37) for storing the heat of the heat medium as stored energy.

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