Dispersive methanation system

Abstract

A distributed methanation system (1) of the present disclosure comprises: a methane generation system (10) including a co-electrolysis device (11) and a methane reactor (12), to which power, water, and carbon dioxide are supplied to generate methane; a fuel cell power generation system (20) is provided with a reformer (21) that converts methane supplied from a methane generation system (10) into hydrogen, and a fuel cell (22) that generates power using the hydrogen supplied from the reformer (21), the fuel cell power generation system (20) is provided with a circulation flow path for recirculating hydrogen exhaust gas generated in the fuel cell (22), and a separator (24) for separating carbon dioxide from the hydrogen exhaust gas. The distributed methanation system (1) is further provided with a carbon dioxide recovery device (40) for recovering the carbon dioxide separated by the separator (24).

Description

Technical Field

[0001] The present disclosure relates to decentralized methanation systems. Background Art

[0002] Patent Document 1 discloses a device for producing methane using carbon dioxide and water. The device reduces water and carbon dioxide to obtain synthesis gas containing hydrogen and carbon monoxide. The device generates methane from the synthesis gas.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2022-22978 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] In such an apparatus, efficient recovery of carbon dioxide as a raw material is sought.

[0008] In view of the above circumstances, an object of the present disclosure is to provide a decentralized methanation system capable of efficiently recovering carbon dioxide.

[0009] Means used to solve problems

[0010] One mode of the distributed methanation system disclosed in the present invention comprises: a methane generation system, wherein the methane generation system includes a co-electrolysis device and a methane reactor, and is supplied with electricity, water and carbon dioxide to generate methane; and a fuel cell power generation system, wherein the fuel cell power generation system includes a reformer and a fuel cell, wherein the reformer converts methane supplied from the methane generation system into hydrogen, and the fuel cell generates electricity using the hydrogen supplied from the reformer, wherein the fuel cell power generation system comprises a circulation flow path and a separator, wherein the circulation flow path recirculates the exhaust gas of hydrogen generated in the fuel cell, and the separator separates carbon dioxide from the exhaust gas of the hydrogen, and the distributed methanation system further comprises a carbon dioxide recovery device, and the carbon dioxide recovery device recovers the carbon dioxide separated by the separator.

[0011] Effects of the Invention

[0012] According to the present disclosure, it is possible to provide a decentralized methanation system capable of efficiently recovering carbon dioxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of a decentralized methanation system according to Embodiment 1.

[0014] Figure 2 This is a block diagram of a decentralized methanation system according to the first embodiment.

[0015] Figure 3 This is a schematic diagram of a decentralized methanation system according to the second embodiment.

[0016] Figure 4 This is a schematic diagram of a decentralized methanation system according to Embodiment 3. DETAILED DESCRIPTION

[0017] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In addition, the scope of the present disclosure is not limited to the following embodiments, and any changes can be made within the scope of the technical concept of the present disclosure. Implementation method 1.

[0018] Figure 1 This is a schematic diagram showing the distributed methanation system 1 in the first embodiment. Figure 2 This is a block diagram showing the distributed methanation system 1 in the first embodiment.

[0019] (Decentralized methanation system 1)

[0020] The decentralized methanation system 1 generates methane from electricity, water and carbon dioxide. The decentralized methanation system 1 generates electricity from the generated methane.

[0021] like Figure 1 As shown, the distributed methanogenization system 1 is supplied with electric power from an external power generation system 2. As the power generation system 2, a renewable energy power generation system can be cited. As the renewable energy power generation system, for example, a solar power generation system, a wind power generation system, etc. can be cited. However, the power generation system 2 is not limited to the renewable energy power generation system. For example, the power generation system 2 may also be a power generation system using thermal power, etc.

[0022] The decentralized methanation system 1 is supplied with water from an external water supply system 3. The decentralized methanation system 1 is supplied with carbon dioxide from an external carbon dioxide supply system 4. As the water supply system 3 and the carbon dioxide supply system 4, known structures can be adopted. In addition, in the present embodiment, the decentralized methanation system 1 recovers at least a part of the carbon dioxide required for generating methane. In the case where the decentralized methanation system 1 recovers all the carbon dioxide required for generating methane, the carbon dioxide supply system 4 does not need to supply carbon dioxide to the decentralized methanation system 1.

[0023] The distributed methanogenation system 1 supplies the generated power to, for example, a regional system power supply. The regional system power supply is managed and operated, for example, by the regional energy management system (regional EMS5). The distributed methanogenation system 1 is connected to the regional EMS5. The regional EMS5 can be supplied with power not only from the distributed methanogenation system 1 but also from the power generation system 2.

[0024] like Figure 1 and Figure 2 As shown, the distributed methanation system 1 includes a methane generation system 10 , a fuel cell power generation system 20 , a gas supply path 30 , a carbon dioxide recovery device 40 , a carbon dioxide storage device 50 , and a control device 60 .

[0025] The methane generation system 10 generates methane by receiving electricity, water, and carbon dioxide. The methane generation system 10 includes a co-electrolysis device 11 , a methane reactor 12 , a first circulation flow path 13 , and a first separator 14 .

[0026] The co-electrolysis device 11 includes, for example, a solid oxide electrolysis cell (SOEC) having a cathode electrode and an anode electrode. The solid oxide electrolysis cell uses, for example, a solid oxide having oxygen ion conductivity. As an electrolyte, a zirconium oxide-based oxide or the like is used.

[0027] The co-electrolysis device 11 supplies water supplied from the water supply system 3 to the cathode electrode of the solid oxide type electrolytic cell. Preferably, the water used for co-electrolysis in the solid oxide type electrolytic cell is water vapor. The co-electrolysis device 11 supplies carbon dioxide supplied from the carbon dioxide supply system 4 or the like to the cathode electrode of the solid oxide type electrolytic cell.

[0028] The co-electrolysis device 11 may include a heating device for heating the solid oxide type electrolysis cell. The heating device can adjust the temperature inside the solid oxide type electrolysis cell to a temperature suitable for the co-electrolysis reaction.

[0029] The ratio of carbon dioxide and water supplied to the solid oxide electrolytic cell can be determined according to the ratio of the components (carbon monoxide and hydrogen) of the target mixed gas.

[0030] The co-electrolysis device 11 obtains a mixed gas containing carbon monoxide (CO) and hydrogen (H2) from carbon dioxide (CO2) and water (H2O) by co-electrolysis. The co-electrolysis is performed, for example, according to the following formula (I). This reaction is an endothermic reaction.

[0031] CO2+H2O→CO+H2+O2…(I)

[0032] In the co-electrolysis device 11, for example, the co-electrolysis can be performed using electricity generated using renewable energy (e.g., solar power generation, wind power generation, etc.). Methane obtained using renewable energy does not produce additional carbon dioxide even when burned and utilized, and can therefore be considered a carbon-neutral fuel that does not affect global warming.

[0033] The methane reactor 12 obtains a fuel gas containing methane (CH4) and water (H2O) from carbon monoxide (CO) and hydrogen (H2) by a methanation reaction. The methanation reaction is performed, for example, according to the following formula (II). This reaction is an exothermic reaction.

[0034] CO + 3H2 → CH4 + H2O… (II)

[0035] The methane reactor 12 preferably includes a methanation catalyst that contacts the mixed gas. Examples of the methanation catalyst include a Ni catalyst and a Ru catalyst. The methanation catalyst promotes the methanation reaction.

[0036] The first circulation flow path 13 circulates the exhaust gas (hereinafter referred to as the first exhaust gas) in the methane reactor 12 in the co-electrolysis device 11 and the methane reactor 12. The first exhaust gas mainly contains hydrogen and water vapor. The first circulation flow path 13 is branched into two branch paths in the middle. Among the two branch paths, the first branch path 13a is connected to the co-electrolysis device 11, and the second branch path 13b is connected to the methane reactor 12.

[0037] The first separator 14 is provided at a branch point in the first circulation flow path 13. The first separator 14 separates the first exhaust gas into a first gas and a second gas. The first gas mainly contains water vapor. The water vapor concentration of the first gas is higher than the water vapor concentration of the first exhaust gas. The second gas mainly contains hydrogen. The hydrogen concentration of the second gas is higher than the hydrogen concentration of the first exhaust gas. The first separator 14 separates the first exhaust gas into water vapor (first gas) and hydrogen (second gas).

[0038] The first separator 14 supplies the first gas (water vapor) to the co-electrolysis device 11 through the first branch path 13a. The first separator 14 supplies the second gas (hydrogen) to the methane reactor 12 through the second branch path 13b. In addition, the heat generated by the exothermic reaction in the methane reactor 12 can be used for the endothermic reaction in the co-electrolysis device 11 by supplying a portion of the first exhaust gas (first gas) to the co-electrolysis device 11 through the first separator 14.

[0039] The fuel cell power generation system 20 includes a reformer 21 , a fuel cell 22 , a second circulation flow path 23 , and a second separator 24 .

[0040] The reformer 21 converts methane supplied from the methane generation system 10 into hydrogen. The reformer 21 is supplied with fuel gas from the methane generation system 10. In the present embodiment, the fuel gas from the methane generation system 10 is supplied via a gas supply path 30. The gas supply path 30 supplies the methane (fuel gas) generated in the methane reactor 12 to the reformer 21 via a methane storage device 31 or a gas infrastructure 32. Here, supplying methane to the reformer 21 via the gas infrastructure 32 includes, for example, supplying methane through an existing pipe for city gas, supplying methane through a transport cylinder, and the like.

[0041] In addition, the methane storage device 31 and the gas infrastructure 32 may be omitted. In addition, not only the fuel gas from the methane generation system 10 but also the city gas (fuel gas, methane gas) from the city gas supply network 6 may be supplied to the reformer 21 .

[0042] The reformer 21 obtains a reformed gas containing carbon monoxide (CO) and hydrogen (H 2 ) from methane and water (steam) contained in the fuel gas through a reforming reaction. The reforming reaction proceeds, for example, according to the following formula (III).

[0043] CH4+H2O→CO+3H2…(III)

[0044] The reformer 21 preferably includes a reforming catalyst that contacts the fuel gas. Examples of the reforming catalyst include Ni catalysts and Ru catalysts. The reforming catalyst promotes the reforming reaction.

[0045] It is desirable that the reformer 21 includes a carbon monoxide converter and a carbon monoxide remover. The reformed gas can reduce the concentration of carbon monoxide by passing through the carbon monoxide converter and the carbon monoxide remover. The carbon monoxide converter includes a carbon monoxide conversion catalyst such as a Cu catalyst and an Fe catalyst. In the carbon monoxide converter, a portion of the carbon monoxide is converted into carbon dioxide. The carbon monoxide remover includes a methanogenic catalyst for methanating the carbon monoxide. Examples of the methanogenic catalyst include a Ru catalyst and the like. In the carbon monoxide remover, a portion of the carbon monoxide is converted into methane.

[0046] Since the reformed gas passes through the carbon monoxide converter and the carbon monoxide remover to reduce the concentration of carbon monoxide, the reformed gas becomes a gas containing hydrogen (H2) as a main component.

[0047] The fuel cell 22 generates electricity using hydrogen supplied from the reformer 21. The fuel cell 22 is, for example, a solid oxide fuel cell (SOFC; Solid Oxide Fuel Cell). A reformed gas is supplied to the anode of the fuel cell 22. An oxygen-containing gas (oxidant-containing gas) is supplied to the cathode of the fuel cell 22. The oxygen-containing gas is, for example, air. In the fuel cell 22, electricity is generated by the reaction of the reformed gas containing hydrogen (H2) with the oxygen-containing gas. This reaction is an exothermic reaction. In the fuel cell 22, a product gas containing water (water vapor) is obtained by the reaction of the reformed gas with the oxygen-containing gas. The product gas contains not only water (water vapor), but also unreacted hydrogen (H2) and carbon dioxide.

[0048] The second circulation flow path 23 circulates the exhaust gas (hereinafter referred to as the second exhaust gas) in the fuel cell 22 in the fuel cell 22. The second exhaust gas mainly contains hydrogen and carbon dioxide. The second circulation flow path 23 branches into two branches midway. The third branch 23a of the two branches is connected to the reformer 21, and the fourth branch 23b is connected to the carbon dioxide recovery device 40. The second circulation flow path 23 recirculates the second exhaust gas (the exhaust gas of hydrogen generated in the fuel cell 22) in the fuel cell 22 through the third branch 23a and the reformer 21. In addition, the third branch 23a can also be connected to the fuel cell 22 instead of being connected to the reformer 21.

[0049] The second separator 24 is provided at a branch point in the second circulation flow path 23. The second separator 24 separates the second exhaust gas into a third gas and a fourth gas. The third gas mainly contains hydrogen. The hydrogen concentration of the third gas is higher than the hydrogen concentration of the second exhaust gas. The fourth gas mainly contains carbon dioxide. The carbon dioxide concentration of the fourth gas is higher than the carbon dioxide concentration of the second exhaust gas. For example, the fourth gas is a high-concentration carbon dioxide gas having a carbon dioxide concentration of 50% or more. The second separator 24 separates carbon dioxide from the second exhaust gas (hydrogen exhaust gas). The second separator 24 separates the second exhaust gas into hydrogen (third gas) and carbon dioxide (fourth gas).

[0050] The second separator 24 supplies the third gas (hydrogen) to the fuel cell 22 through the third branch 23a. The second separator 24 supplies the fourth gas (carbon dioxide) to the carbon dioxide recovery device 40 through the fourth branch 23b. In addition, a portion of the second exhaust gas may be supplied to the carbon dioxide recovery device 40 through the second separator 24, so that the heat (exhaust heat) generated by the exothermic reaction in the fuel cell 22 is used for the endothermic reaction in the carbon dioxide recovery device 40.

[0051] The carbon dioxide recovery device 40 recovers carbon dioxide (carbon dioxide separated by the second separator 24) from the fourth gas which is a part of the second exhaust gas. The carbon dioxide recovery device 40 adopts separation methods such as adsorption separation, membrane separation, cooling separation, centrifugal separation, gravity separation, gas-liquid separation, etc. The carbon dioxide recovery device 40 may adopt one of these separation methods or a combination of two or more separation methods.

[0052] The carbon dioxide recovery device 40 using adsorption separation is separated, for example, by adsorbing a specific component on an adsorbent, an adsorbent liquid, etc. As the adsorbent, silica gel, zeolite, activated carbon, etc. can be cited. Specifically, by adsorbing the component containing carbon dioxide on the adsorbent, the component can be separated from other components. The adsorbent can be granular, powdery, etc. Granular, for example, is beaded (spherical), pellet (cylindrical), etc. In the case of using a powdered adsorbent, the adsorbent can be supported on the surface of the substrate. The substrate can be, for example, in the shape of a honeycomb.

[0053] The carbon dioxide recovery device 40 using adsorption separation has the function of separating carbon dioxide from the adsorbent. The carbon dioxide recovery device 40 is provided with a heating device, for example. The heating device separates carbon dioxide from the adsorbent by heating the adsorbent. The carbon dioxide recovery device 40 may also be provided with a decompression device such as a decompression pump. The decompression device separates carbon dioxide from the adsorbent by placing the adsorbent under reduced pressure.

[0054] The carbon dioxide recovery device 40 using membrane separation uses, for example, a permeable membrane through which low molecular weight components can pass to separate a specific component from other components. Specifically, a palladium permeable membrane can be used to separate a component containing hydrogen (H2) from a component containing carbon dioxide.

[0055] The carbon dioxide recovery device 40 using cooling separation liquefies a specific component by cooling, for example, and separates it from other components (gases). Specifically, it is possible to liquefy a component including water and separate it from a gas including carbon dioxide.

[0056] The carbon dioxide recovery device 40 using centrifugal separation, for example, liquefies a specific component (a component containing water) by cooling, and separates the component from other components (gas containing carbon dioxide) by centrifugal force. The carbon dioxide recovery device 40 using gravity separation, for example, liquefies a specific component (a component containing water) by cooling, and separates the component from other components (gas containing carbon dioxide) by gravity. The carbon dioxide recovery device 40 using gas-liquid separation, for example, liquefies a specific component (a component containing water) by cooling, and separates the component from other components (gas containing carbon dioxide) by gravity, centrifugal force, surface tension, etc.

[0057] In this embodiment, in addition to the carbon dioxide emitted from the fuel cell power generation system 20, the carbon dioxide recovery device 40 also recovers carbon dioxide from other carbon dioxide recovery sources. The other carbon dioxide recovery sources are at least one of the atmosphere, indoor air, and factory exhaust. However, the carbon dioxide recovery device 40 may only recover the carbon dioxide emitted from the fuel cell power generation system 20.

[0058] The carbon dioxide recovery device 40 may also supply the recovered carbon dioxide directly to the co-electrolysis device 11. The carbon dioxide recovery device 40 may supply the recovered carbon dioxide to the carbon dioxide storage device 50. The carbon dioxide storage device 50 supplies the stored carbon dioxide to the co-electrolysis device 11. The carbon dioxide recovery device 40 may also supply the recovered carbon dioxide indirectly to the co-electrolysis device 11 via the carbon dioxide storage device 50. In addition, the carbon dioxide storage device 50 may not be provided.

[0059] like Figure 2 As shown, the control device 60 controls each component of the distributed methanation system 1. The control device 60 controls the methane generation system 10, the fuel cell power generation system 20, the gas supply path 30, the carbon dioxide recovery device 40, and the carbon dioxide storage device 50.

[0060] The control device 60 includes artificial intelligence that performs machine learning on the demand / supply of electricity. The artificial intelligence predicts the demand / supply of electricity. As the demand for electricity, for example, the amount of electricity required by the regional EMS 5 can be cited. As the supply of electricity, for example, the amount of electricity generated by the power generation system 2 (renewable energy power generation system) can be cited. The artificial intelligence predicts (outputs) the demand / supply of electricity using, for example, date and time data, weather data, etc. as input values. In addition, there may be no artificial intelligence.

[0061] (Operation method of the decentralized methanation system 1)

[0062] Next, explain how Figure 1 and Figure 2 The examples of the operation method of the above-mentioned distributed methanation system 1 are shown. However, the operation method is not limited to part or all of the following examples.

[0063] The control device 60 can also control the operating status of the distributed methanation system 1 based on the prediction results of the demand / supply of electricity by artificial intelligence. The operating status of the distributed methanation system 1 is the ratio of resource recovery operation to power generation operation. Here, resource recovery operation refers to, for example, generating methane or recovering carbon dioxide based on the electricity supplied from the power generation system 2, and storing gases such as methane and carbon dioxide. Power generation operation is, for example, generating electricity using methane. Power generation operation is, for example, generating electricity using stored methane, or generating methane using stored carbon dioxide and generating electricity using the methane. Power generation operation generates electricity using methane supplied from the city gas supply network 6, or generates methane using carbon dioxide supplied from the carbon dioxide supply system 4 and generates electricity using the methane.

[0064] Hereinafter, the power generated by the power generation system 2 is also referred to as first power, and the power generated by the distributed methanation system 1 is also referred to as second power. Resource recovery operation means, for example, converting the first power into gas (carbon dioxide or methane) and storing it. Power generation operation means, for example, generating the second power.

[0065] For example, when artificial intelligence predicts that there will be a power shortage after a certain period (for example, a few days, a few weeks, or a few months), the control device 60 may convert the first power into gas and store it to cope with the shortage. In this case, for example, the control device 60 may implement different controls in the first period and the second period in which the power demand is less than the first period. The first period may be, for example, the future in which a power shortage is predicted. The second period may be, for example, the present in which a power shortage is dealt with. In the second period, the control device 60 reduces the power generation of the fuel cell power generation system 20 compared with the first period. On the other hand, in the second period, the control device 60 increases the carbon dioxide recovery from the aforementioned other carbon dioxide recovery sources (at least one of the atmosphere, indoor air, and factory exhaust) compared with the first period. In the case where the control device 60 copes with a power shortage in the future (the first period) as described above, the control device 60 may increase the ratio of resource-saving operation in the present (the second period) and store methane or carbon dioxide. The first period or the second period may be, for example, a period of units such as a few days, a few weeks, or a few months. When the first period and the second period are measured in units of several months, in a region such as Japan where climate changes based on four seasons, for example, the first period may be summer and winter, and the second period may be spring and autumn.

[0066] In addition, the control device 60 may perform different controls during a third period when the regional power demand is tight and during a fourth period when the regional power demand is surplus. The regional power demand is tight, for example, when the power demand of each region is greater than a first ratio (for example, greater than 90%) relative to the amount of power that can be supplied to each region from the system power supply of each region. The regional power demand is surplus, for example, when the power demand of the region is not tight. The regional power demand is surplus, for example, when the power demand of each region is less than a second ratio (for example, less than 50%) relative to the amount of power that can be supplied to each region from the system power supply of each region. The control device 60 may, for example, simply obtain the judgment result from the regional EMS 5 to implement the judgment of whether the regional power demand is tight or whether the regional power demand is surplus.

[0067] The control device 60 supplies the power supplied to the distributed methanation system 1 to the regional power supply during the third period. Furthermore, the control device 60 releases the pre-stored methane during the third period to generate power in the fuel cell power generation system 20 and supplies the power to the power supply.

[0068] On the other hand, the control device 60 generates methane in the methane generation system 10 using at least a portion of the power supplied to the distributed methanation system 1, water, and carbon dioxide during the fourth period, and stores at least a portion of the generated methane in the tank. At this time, the control device 60 can supply methane to the fuel cell power generation system 20 and generate the second power.

[0069] In addition, the control device 60 can control the methane generation amount of the methane generation system 10 and the power generation amount of the fuel cell power generation system 20 according to the power supply and demand conditions of the regional EMS 5. In this case, for example, even if the control device 60 does not have artificial intelligence, by obtaining information on the power supply and demand of the regional EMS 5, for example, the ratio of resource recovery operation to power generation operation can be appropriately controlled.

[0070] As described above, according to the distributed methanation system 1 of the present embodiment, the carbon dioxide recovery device 40 recovers the carbon dioxide separated by the second separator 24. As a result, the high-concentration carbon dioxide concentrated in the fuel cell 22 can be recovered. As a result, the recovery cost of carbon dioxide can be reduced. In addition, the carbon dioxide required by the methane generation system 10 can be recovered and utilized.

[0071] The methane generation system 10 is provided with a methane storage device 31. Thereby, when the amount of power generated by the power generation system 2 is large, excessively generated methane can be stored. Also, when the amount of power generated by the power generation system 2 is small, power generation can be performed using the stored methane.

[0072] The carbon dioxide recovery device 40 is provided with a carbon dioxide storage device 50. Thus, for example, even when the power demand is small, carbon dioxide can be recovered by the carbon dioxide recovery device 40 to store carbon dioxide, which is a raw material of methane. As a result, the control range of the power generation of the distributed methanation system 1 can be improved.

[0073] The carbon dioxide recovery device 40 recovers carbon dioxide from other carbon dioxide recovery sources in addition to the carbon dioxide released from the fuel cell power generation system 20. Therefore, the distributed methanation system 1 can be made carbon dioxide emission-free or negative emission.

[0074] The control device 60 controls the operation of the distributed methanation system 1 based on the prediction results of the power demand / supply by artificial intelligence. As a result, the prediction accuracy of the power demand / supply is improved, making it possible to reduce the gap between energy demand and power generation in the entire region, and to operate the distributed methanation system 1 stably.

[0075] The control device 60 controls the methane generation amount of the methane generation system 10 and the power generation amount of the fuel cell power generation system 20 according to the power supply and demand conditions of the regional EMS 5. Thus, for example, the mixed amount of methane supplied from the methane generation system 10 and the methane supplied from the city gas supply network 6 can be increased according to the power demand, and the power generation amount of the fuel cell power generation system 20 can be increased, thereby adjusting the operation balance.

[0076] In the second period when the power demand is small, the control device 60 reduces the power generation of the fuel cell power generation system 20 compared to the first period, and increases the carbon dioxide recovery from other carbon dioxide recovery sources compared to the first period. Thus, in accordance with the power demand, even when the power demand is small, the recovery amount of carbon dioxide that is easily in short supply during methane generation can be increased. Thus, for example, it can be stored in advance in the carbon dioxide storage device 50, etc.

[0077] During the third period when the power demand in the region is tight, the control device 60 supplies the power supplied to the distributed methanation system 1 to the system power supply in the region, and releases the methane stored in advance to generate power in the fuel cell power generation system 20 and supply it to the system power supply. During the fourth period when the power demand in the region is sufficient, the control device 60 generates methane through the methane generation system 10 using at least a part of the power supplied to the distributed methanation system 1, water and carbon dioxide, and stores part of the generated methane in a tank. In this way, according to the power supply and demand situation in the region, for example, switching is performed between the operation of supplying a large amount of power to the system power supply in the region as in the third period and the operation of methanating and storing at least a part of the power as in the fourth period. As a result, for example, even if the power is power from a renewable energy power generation system, it is possible to suppress the instability of power. Implementation method 2.

[0078] Next, a distributed methanation system 1A according to Embodiment 2 will be described. Since the basic structure of the distributed methanation system 1A according to this embodiment is the same as that of Embodiment 1, the description will be mainly focused on the differences.

[0079] In this embodiment, if Figure 3 As shown, in the decentralized methanation system 1A, the carbon dioxide recovery device 40 is a DAC device (Direct Air Capture). As such a carbon dioxide recovery device 40, for example, a DAC device that utilizes air supply power or cooling energy / heat energy of an air conditioning device can be cited. As the air supply power of the air conditioning device, an outdoor unit air blower and an indoor unit air blower can be cited. As the cooling energy / heat energy of the air conditioning device, cooling energy / heat energy generated by the refrigerant during cooling operation and heating operation can be cited.

[0080] In addition, a path switching device 70 and a carbon dioxide concentrator 80 are provided in the carbon dioxide recovery device 40. The path switching device 70 switches the recovery source of carbon dioxide of the carbon dioxide recovery device 40 between the fuel cell power generation system 20 and the aforementioned other carbon dioxide recovery sources (at least one of the atmosphere, indoor air and factory exhaust). As the path switching device 70, a known structure can be appropriately adopted, for example, a valve provided in the piping can be cited. The path switching device 70 can also be controlled by the control device 60, for example. In the case of increasing the recovery amount of carbon dioxide from the aforementioned other carbon dioxide recovery sources, the control device 60 can control the path switching device 70, for example.

[0081] The carbon dioxide-containing gas (hereinafter referred to as the fifth gas) recovered by the carbon dioxide recovery device 40 is transported to the carbon dioxide concentrator 80. The carbon dioxide concentrator 80 increases the carbon dioxide concentration in the fifth gas and transports it downstream as the sixth gas. For example, similar to the carbon dioxide recovery device 40, the carbon dioxide concentrator 80 can increase the carbon dioxide concentration of the sixth gas to be higher than the carbon dioxide concentration of the fifth gas by separation methods such as adsorption separation, membrane separation, cooling separation, centrifugal separation, gravity separation, and gas-liquid separation. The sixth gas is supplied to the co-electrolysis device 11 or stored in the carbon dioxide storage device 50.

[0082] As described above, according to the distributed methanation system 1A of this embodiment, the carbon dioxide recovery device 40 is a DAC device that utilizes the air supply power or cooling / heating energy of the air conditioning device. Thus, the air supply power or cooling / heating energy of the air conditioning device can be effectively utilized to increase the amount of carbon dioxide recovered.

[0083] The path switching device 70 switches the carbon dioxide recovery source of the carbon dioxide recovery device 40 between the fuel cell power generation system 20 and another carbon dioxide recovery source. Thus, the recovery path can be switched to recover carbon dioxide when the fuel cell power generation system 20 is activated and when it is not activated. Implementation method 3.

[0084] Next, a distributed methanation system 1B according to Embodiment 3 will be described. Since the basic structure of the distributed methanation system 1B according to this embodiment is the same as that of Embodiment 2, the description will be mainly focused on the differences.

[0085] like Figure 4 As shown, the dispersed methanation system 1B of the present embodiment further includes a storage battery 90. The storage battery 90 is supplied with electric power from the power generation system 2 and stores electric power. The storage battery 90 can supply the stored electric power to the dispersed methanation system 1B.

[0086] (Operation method of decentralized methanation system 1B)

[0087] Next, examples of the operating method of the above-mentioned distributed methanation system 1B will be described. However, the operating method is not limited to these examples. Moreover, these examples can be used in combination.

[0088] The control device 60 performs different control in the fifth period and the sixth period. The fifth period is a period when the power generation of the power generation system 2 (renewable energy power generation system) is greater than the power required in the distributed methanation system 1. The sixth period is a period when the power generation of the power generation system 2 is less than the power required in the distributed methanation system 1. The control device 60 can, for example, calculate the power required in the distributed methanation system 1. The control device 60 can, for example, obtain the power generation of the power generation system 2 from the power generation system 2.

[0089] During the fifth period, the control device 60 stores (accumulates) surplus power from the renewable energy power generation system in the storage battery 90. Then, during the sixth period, the control device 60 may discharge from the storage battery 90 and cause the methane generation system 10 to generate methane, and may cause the carbon dioxide recovery device 40 to recover carbon dioxide. The methane and carbon dioxide generated during the sixth period are stored in the methane storage device 31 and the carbon dioxide storage device 50, respectively.

[0090] As described above, according to the decentralized methanation system 1 of the present embodiment, during the fifth period when the amount of power generated by the power generation system 2 is greater than the power required in the decentralized methanation system 1, the control device 60 stores the surplus power from the power generation system 2 in the storage battery 90. During the sixth period when the amount of power generated by the power generation system 2 is less than the power required in the decentralized methanation system 1, the control device 60 discharges from the storage battery 90 and causes the methane generation system 10 to generate methane, or causes the carbon dioxide recovery device 40 to recover carbon dioxide. Thus, uneven power generation of renewable energy can be reduced, and methane and carbon dioxide can be stably supplied.

[0091] In addition, the technical scope of the present disclosure is not limited to the above-mentioned embodiment, and various changes can be made within the scope not departing from the gist of the present disclosure.

[0092] In addition, the control device 60 has, for example, a computer system. Then, a program for realizing the functions of each structure of the above-mentioned decentralized methanation system 1 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into the computer system and executed, so that the processing in each structure described above can be performed. Here, "reading the program recorded on the recording medium into the computer system and executing it" includes installing the program in the computer system. The "computer system" here includes hardware such as an OS and peripheral devices.

[0093] In addition, the "computer system" may include a plurality of computer devices connected via the Internet or a network including a WAN, LAN, a dedicated line, or other communication line. In addition, the "computer-readable recording medium" refers to a portable medium such as a floppy disk, a magneto-optical disk, a ROM, and a CD-ROM, as well as a storage device such as a hard disk built into the computer system. In this way, the recording medium storing the program may be a non-temporary recording medium such as a CD-ROM.

[0094] In addition, the recording medium also includes an internal or external recording medium that can be accessed from a distribution server in order to distribute the program. In addition, it can also be a structure in which the program is divided into multiple parts, and after being downloaded at different time intervals, they are combined in each structure possessed by the decentralized methanogenesis system 1. In addition, the distribution servers that distribute each divided program can be different. In addition, "computer-readable recording medium" includes a recording medium that retains the program for a certain period of time, such as a volatile memory (RAM) inside a computer system that serves as a server or client when the program is sent via a network. In addition, the above-mentioned program can also be used to implement a part of the above-mentioned functions. In addition, it can be a file that implements the above-mentioned function by combining with a program already recorded in the computer system, that is, a so-called differential file (differential program).

[0095] In addition, all or part of each function of the control device 60 may be implemented using hardware such as an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array).

[0096] In addition, the above-mentioned embodiments and modifications may be combined as appropriate. Description of Reference Numerals

[0097] 1. 1A, 1B decentralized methanation system

[0098] 2 Power Generation System

[0099] 5 Regional EMS (Energy Management System)

[0100] 10Methane generation system

[0101] 11Co-electrolysis device

[0102] 12Methane Reactor

[0103] 20Fuel cell power generation system

[0104] 21 Modifier

[0105] 22 Fuel Cell

[0106] 23 Second circulation flow path

[0107] 24 Second separator

[0108] 30 Gas supply path

[0109] 31Methane storage device

[0110] 32Gas Infrastructure

[0111] 40 Carbon dioxide recovery device

[0112] 50 Carbon dioxide storage device

[0113] 60 Control Device

[0114] 70 Path Switching Device

[0115] 90 battery

Claims

1. A decentralized methanogenation system comprising: a methane generation system, the methane generation system comprising a co-electrolyzer and a methane reactor, supplied with electricity, water and carbon dioxide to generate methane; and A fuel cell power generation system, the fuel cell power generation system comprising a reformer and a fuel cell, the reformer converting methane supplied from the methane generation system into hydrogen, the fuel cell generating electricity using the hydrogen supplied from the reformer, wherein: The fuel cell power generation system includes a circulation flow path for recirculating hydrogen off-gas generated in the fuel cell and a separator for separating carbon dioxide from the hydrogen off-gas. The decentralized methanation system further includes a carbon dioxide recovery device that recovers the carbon dioxide separated by the separator.

2. The decentralized methanogenesis system according to claim 1, wherein: A gas supply path is further provided for supplying methane generated in the methane reactor to the reformer via a methane storage device or a gas infrastructure.

3. The decentralized methanogenesis system according to claim 1 or 2, wherein: A methane storage device is provided in the methane generation system.

4. The decentralized methanation system according to any one of claims 1 to 3, wherein: The carbon dioxide recovery device is provided with a carbon dioxide storage device.

5. The decentralized methanation system according to any one of claims 1 to 4, wherein: In addition to the carbon dioxide emitted from the fuel cell power generation system, the carbon dioxide recovery device also recovers carbon dioxide from other carbon dioxide recovery sources.

6. The decentralized methanogenesis system according to claim 5, wherein: The other carbon dioxide recovery source is at least one of the atmosphere, indoor air and factory exhaust.

7. The decentralized methanation system according to claim 5 or 6, wherein: The carbon dioxide recovery device is provided with a path switching device, and the path switching device switches the recovery source of the carbon dioxide of the carbon dioxide recovery device between the fuel cell power generation system and the other carbon dioxide recovery source.

8. The decentralized methanation system according to any one of claims 1 to 7, wherein: The carbon dioxide recovery device is a DAC device that utilizes the air supply power or cold energy / heat energy of an air conditioning device.

9. The decentralized methanation system according to any one of claims 1 to 8, wherein: A control device is further provided, and the control device controls the methane generation system, the fuel cell power generation system, and the carbon dioxide recovery device.

10. The decentralized methanation system according to claim 9, wherein: The decentralized methanation system is connected to an energy management system. The control device controls the methane generation amount of the methane generation system and the power generation amount of the fuel cell power generation system according to the power supply and demand status of the energy management system.

11. The decentralized methanation system according to claim 9 or 10, wherein: In addition to the carbon dioxide emitted from the fuel cell power generation system, the carbon dioxide recovery device also recovers carbon dioxide from other carbon dioxide recovery sources. The control device performs different control in a first period and a second period where the power demand is smaller than that in the first period, The control device reduces the amount of power generated by the fuel cell power generation system during the second period compared to the first period, and increases the amount of carbon dioxide recovered from the other carbon dioxide recovery source compared to the first period.

12. The decentralized methanation system according to any one of claims 9 to 11, wherein: The control device performs different controls in a third period when the regional power demand is tight and in a fourth period when the regional power demand is abundant. During the third period, the control device supplies the power supplied to the distributed methanogenesis system to the system power supply of the region, and releases the pre-stored methane to generate electricity through the fuel cell power generation system and supplies the electricity to the system power supply. During the fourth period, the control device generates methane from at least a portion of the electricity supplied to the decentralized methanation system, water, and carbon dioxide through the methane generation system, and stores at least a portion of the generated methane in a tank.

13. The decentralized methanation system according to any one of claims 9 to 12, wherein: supplying the decentralized methanation system with electricity from a renewable energy generation system, The decentralized methanation system further comprises a battery. The control device implements different controls in a fifth period and a sixth period, wherein the amount of power generated by the renewable energy power generation system in the fifth period is greater than the power required in the distributed methanation system, and the amount of power generated by the renewable energy power generation system in the sixth period is less than the power required in the distributed methanation system.

14. The decentralized methanation system according to claim 13, wherein: The control device stores surplus power from the renewable energy power generation system in the storage battery during the fifth period, and discharges the surplus power from the storage battery during the sixth period to cause the methane generation system to generate methane.

15. The decentralized methanation system according to claim 13, wherein: The control device stores surplus power from the renewable energy power generation system in the storage battery during the fifth period, and discharges the surplus power from the storage battery and causes the carbon dioxide recovery device to recover carbon dioxide during the sixth period.

16. The decentralized methanation system according to any one of claims 9 to 15, wherein: The control device includes artificial intelligence that has been machine-learned to determine the demand and supply of electricity. The control device controls the operation status of the decentralized methanation system based on the prediction result of the demand and supply of electric power by the artificial intelligence.

17. The decentralized methanation system according to claim 16, wherein: The operating status of the decentralized methanation system is a ratio of resource recovery operation to power generation operation.

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