JP7487590B2 - Carbon dioxide capture device and carbon dioxide capture method - Google Patents

Description

The present invention relates to a carbon dioxide capture device and a carbon dioxide capture method.

Methods of capturing carbon dioxide from the atmosphere have been attracting attention as a way to reduce the concentration of greenhouse gases in the atmosphere in the context of global warming.

Non-Patent Document 1 describes a method for recovering carbon dioxide taken from the atmosphere using potassium hydroxide.

Joule, August 15, 2018, Volume 2, Issue 8, pp. 1573-1594

However, the method described in Non-Patent Document 1 is estimated to require 8.81 GJ of energy per ton of carbon dioxide to capture carbon dioxide. In addition, a large amount of fan power is required to introduce air.

The present invention has been made in consideration of the above circumstances, and a problem that one embodiment of the present invention aims to solve is to provide a carbon dioxide capture device that efficiently captures carbon dioxide from the atmosphere and converts it into fuel.
Another problem to be solved by another embodiment of the present invention is to provide a carbon dioxide capture method for efficiently capturing carbon dioxide from the atmosphere and converting it into fuel.

The present invention includes the following aspects.
<1> A carbon dioxide capture device comprising a combustor that takes in air and generates combustion gas, a hydrogen supply source that supplies hydrogen, and a carbon dioxide capture reducer that captures carbon dioxide contained in the combustion gas and contains a material that converts the captured carbon dioxide into fuel using hydrogen.
<2> The carbon dioxide recovery device according to <1>, wherein the material is a carbon dioxide occlusion/reduction catalyst containing a metal oxide having carbon dioxide occlusion performance and a metal having methanation catalytic performance.
<3> The carbon dioxide capture device described in <2>, further comprising: a gas exhaust flow path for exhausting to the atmosphere the residual gas after the carbon dioxide has been captured by the carbon dioxide occlusion reduction catalyst; a methane separator for separating a portion of the methane from a methane-containing gas containing methane obtained by the conversion of carbon dioxide; and a methane gas supply flow path for supplying the low-concentration methane-containing gas separated in the methane separator to at least one of the combustor and the carbon dioxide capture reduction device.
<4> The carbon dioxide capture device according to <3>, wherein the methane gas supply passage is a passage for supplying low-concentration methane-containing gas separated in the methane separator to the combustor.
<5> A carbon dioxide capture device according to any one of <1> to <4>, further comprising a carbon dioxide absorber between the combustor and the carbon dioxide capture and reduction device, the carbon dioxide absorber housing an adsorbent material having carbon dioxide absorption capacity.
<6> The carbon dioxide capture device described in <5>, further comprising a methane separator that separates a portion of methane from a methane-containing gas containing methane obtained by conversion of carbon dioxide, a combustion gas supply flow path for supplying combustion gas to the carbon dioxide absorption device, a hydrogen supply flow path for supplying hydrogen from a hydrogen supply source to the carbon dioxide absorption device, a gas supply flow path for supplying gas from the carbon dioxide absorption device to the carbon dioxide capture and reduction device, and a methane-containing gas supply flow path for supplying methane-containing gas from the carbon dioxide capture and reduction device to the methane separator.
<7> The carbon dioxide capture device described in <5>, further comprising a methane separator that separates a portion of methane from a methane-containing gas containing methane obtained by conversion of carbon dioxide, a combustion gas supply flow path for supplying combustion gas to the carbon dioxide capture and absorption device, a first gas supply flow path for supplying gas from the carbon dioxide capture and absorption device to the carbon dioxide capture and reduction device, a hydrogen supply flow path for supplying hydrogen from a hydrogen supply source to the carbon dioxide capture and reduction device, a second gas supply flow path for supplying gas from the carbon dioxide capture and reduction device to the carbon dioxide capture and reduction device, and a methane-containing gas supply flow path for supplying methane-containing gas from the carbon dioxide capture and reduction device to the methane separator.
<8> The carbon dioxide capture device according to <6>, further comprising a methane converter between the methane separator and the carbon dioxide capture and reduction device, which converts carbon dioxide into methane.
<9> The carbon dioxide recovery apparatus according to <7>, further comprising a methane converter between the methane separator and the carbon dioxide absorber, which converts carbon dioxide into methane.
<10> The carbon dioxide capture device according to any one of <5> to <9>, further comprising a dehumidifier for removing moisture between the carbon dioxide capture reduction device and the carbon dioxide absorption device.
<11> A carbon dioxide capture method including the steps of taking in air and generating combustion gas, supplying hydrogen, and capturing carbon dioxide contained in the combustion gas and converting the captured carbon dioxide into fuel using hydrogen.

The present invention makes it possible to efficiently capture carbon dioxide from the atmosphere and convert it into fuel.

FIG. 1 is a schematic diagram showing a carbon dioxide capture device according to a first embodiment. FIG. 2 is a flowchart showing a carbon dioxide capture method using the carbon dioxide capture device of the first embodiment. FIG. 3 is a schematic diagram showing a carbon dioxide capture device according to the second embodiment. FIG. 4 is a flowchart showing a carbon dioxide capture method using the carbon dioxide capture device of the second embodiment. FIG. 5 is a schematic diagram showing a carbon dioxide capture device according to the third embodiment. FIG. 6 is a flowchart showing a carbon dioxide capture method using the carbon dioxide capture device of the third embodiment. FIG. 7 is a schematic diagram showing a carbon dioxide capture device according to the fourth embodiment. FIG. 8 is a schematic diagram showing a carbon dioxide capture device according to the fifth embodiment. FIG. 9 is a schematic diagram showing a carbon dioxide capture apparatus of Comparative Example 2.

The following describes in detail an embodiment of the present invention with reference to the drawings.

[First embodiment]
Fig. 1 is a schematic diagram showing a carbon dioxide capture device of a first embodiment. As shown in Fig. 1, the carbon dioxide capture device 100 includes a combustor A, a heat utilization device B, a carbon dioxide capture reducer C, a methane separator D, a hydrogen/methane gas storage E, a hydrogen supply source H, and a methane storage M.

Combustor A is a device for burning gas. Combustor A is connected to an air supply passage 11, a combustion gas supply passage 12, and a hydrogen/methane gas supply passage 17. The operation of combustor A is controlled by a control unit (not shown).

In combustor A, fuel (specifically, hydrogen, methane, etc.) is burned to generate combustion gas. The combustion temperature is not particularly limited, but is, for example, 800°C to 1500°C. Examples of heaters used for combustion include burners, gas turbines, and boilers.

The atmospheric air supply passage 11 is a passage for supplying atmospheric air to the combustor A. An atmospheric air supply valve V1 is provided on the atmospheric air supply passage 11. When the atmospheric air supply valve V1 is open, atmospheric air is supplied to the combustor A. On the other hand, when the atmospheric air supply valve V1 is closed, the supply of atmospheric air to the combustor A is stopped. The opening and closing of the atmospheric air supply valve V1 is controlled by a control unit. The atmospheric air contains oxygen, nitrogen, carbon dioxide, etc.

The hydrogen/methane gas supply passage 17 is a passage for supplying a mixed gas of hydrogen and methane to the combustor A. A hydrogen/methane gas supply valve V7 is provided on the hydrogen/methane gas supply passage 17. When the hydrogen/methane gas supply valve V7 is open, the mixed gas of hydrogen and methane is supplied to the combustor A. On the other hand, when the hydrogen/methane gas supply valve V7 is closed, the supply of the mixed gas of hydrogen and methane to the combustor A is stopped. The opening and closing of the hydrogen/methane gas supply valve V7 is controlled by the control unit.

The first combustion gas supply passage 12 is a passage for supplying the combustion gas generated in the combustor A to the heat utilization equipment B. A first combustion gas supply valve V2 is provided on the first combustion gas supply passage 12. When the first combustion gas supply valve V2 is open, the combustion gas is supplied to the heat utilization equipment B. On the other hand, when the first combustion gas supply valve V2 is closed, the supply of the combustion gas to the heat utilization equipment B is stopped. The opening and closing of the first combustion gas supply valve V2 is controlled by a control unit. The combustion gas contains carbon dioxide, nitrogen, water vapor, etc.

The heat utilization equipment B is an equipment that utilizes the thermal energy of the combustion gas generated in the combustor A. After the thermal energy of the combustion gas is used in the heat utilization equipment B, the temperature of the combustion gas decreases. Examples of the heat utilization equipment B include a water heater and an air conditioner. A first combustion gas supply flow path 12 and a second combustion gas supply flow path 13 are connected to the heat utilization equipment B.

The second combustion gas supply passage 13 is a passage for supplying the combustion gas discharged from the heat utilization equipment B to the carbon dioxide capture and reduction device C. A second combustion gas supply valve V3 is provided on the second combustion gas supply passage 13. When the second combustion gas supply valve V3 is open, the combustion gas is supplied to the carbon dioxide capture and reduction device C. On the other hand, when the second combustion gas supply valve V3 is closed, the supply of the combustion gas to the carbon dioxide capture and reduction device C is stopped. The opening and closing of the second combustion gas supply valve V3 is controlled by the control unit.

The carbon dioxide capture and reduction device C is a device for capturing carbon dioxide contained in the combustion gas and converting the captured carbon dioxide into fuel. The carbon dioxide capture and reduction device C contains a material that captures carbon dioxide contained in the combustion gas and converts the captured carbon dioxide into fuel using hydrogen. The material contained in the carbon dioxide capture and reduction device C is a carbon dioxide storage and reduction catalyst that includes a metal oxide having carbon dioxide storage capacity and a metal having methanation catalytic capacity.

The carbon dioxide storage/reduction catalyst is preferably a catalyst in which a metal oxide having carbon dioxide storage capacity and a metal having methanation catalytic capacity are supported on a carrier. The carrier is alumina, the metal oxide having carbon dioxide storage capacity is calcium oxide, and the metal having methanation catalytic capacity is ruthenium (Ru).

In addition to alumina, examples of the carrier include silica, silica-alumina, titania, zirconia, ceria, and ceria-zirconia. Examples of metal oxides having carbon dioxide storage capacity include alkali metal oxides and alkaline earth metal oxides, and in addition to calcium oxide, examples of the metals having methanation catalytic capacity include nickel (Ni), platinum (Pt), palladium (Pd), rhodium (Rd), cobalt (Co), iron (Fe), and manganese (Mn). These metals may be used alone or in combination of two or more.

The carbon dioxide capture and reduction device C is connected to a second combustion gas supply passage 13, a gas exhaust passage 14, a generated gas supply passage 15, and a hydrogen supply passage 18.

The carbon dioxide capture and reduction device C is also fitted with a carbon dioxide detection sensor (not shown) and a methane detection sensor (not shown) as concentration detection units. The carbon dioxide detection sensor is a device that detects the carbon dioxide concentration in the atmosphere of the carbon dioxide capture and reduction device C, and is connected to the control unit. The methane detection sensor is a device that detects the methane concentration in the atmosphere of the carbon dioxide capture and reduction device C, and is connected to the control unit.

The gas exhaust flow path 14 is a flow path that exhausts the residual gas after carbon dioxide is absorbed in the carbon dioxide reduction catalyst to the atmosphere. The residual gas is gas that has not been absorbed in the carbon dioxide reduction catalyst contained in the carbon dioxide capture and reduction device C, and is mainly composed of nitrogen and water vapor. A gas exhaust valve V4 is provided on the gas exhaust flow path 14. When the gas exhaust valve V4 is open, the residual gas is exhausted to the atmosphere. On the other hand, when the gas exhaust valve V4 is closed, the exhaust of the residual gas to the atmosphere is stopped. The opening and closing of the gas exhaust valve V4 is controlled by the control unit.

The product gas supply flow path 15 is a flow path for supplying the product gas obtained by the methanation reaction of the carbon dioxide stored in the carbon dioxide reduction catalyst to the methane separator D. The product gas mainly consists of hydrogen and methane. A product gas supply valve V5 is provided on the product gas supply flow path 15. When the product gas supply valve V5 is open, the product gas is supplied to the methane separator D. On the other hand, when the product gas supply valve V5 is closed, the supply of the product gas to the methane separator D is stopped. The opening and closing of the product gas supply valve V5 is controlled by the control unit.

The hydrogen supply flow path 18 is a flow path for supplying hydrogen from the hydrogen supply source H to the carbon dioxide capture and reduction device C. A hydrogen supply valve V8 is provided on the hydrogen supply flow path 18. When the hydrogen supply valve V8 is open, hydrogen is supplied to the carbon dioxide capture and reduction device C. On the other hand, when the hydrogen supply valve V8 is closed, the supply of hydrogen to the carbon dioxide capture and reduction device C is stopped. The opening and closing of the hydrogen supply valve V8 is controlled by the control unit.

The methane separator D is a device that separates a portion of methane from a methane-containing gas that contains methane obtained by converting carbon dioxide. In the first embodiment, the methane separator D separates a portion of methane from the product gas obtained in the carbon dioxide capture and reduction device C. The methane separator D is connected to a product gas supply flow path 15, a hydrogen/methane gas supply flow path 16, which is an example of a gas supply flow path, and a methane recovery flow path 19.

Methods for separating methane include, for example, the PSA method and membrane separation method.

The hydrogen/methane gas supply passage 16 is a passage for supplying the residual gas remaining after a portion of the methane has been separated in the methane separator D to the hydrogen/methane gas storage vessel E. The residual gas contains a lower concentration of methane, hydrogen, etc. than the product gas obtained in the carbon dioxide capture and reduction vessel C. A hydrogen/methane gas supply valve V6 is provided on the hydrogen/methane gas supply passage 16. When the hydrogen/methane gas supply valve V6 is open, the residual gas is supplied to the hydrogen/methane gas storage vessel E. On the other hand, when the hydrogen/methane gas supply valve V6 is closed, the supply of the residual gas to the hydrogen/methane gas storage vessel E is stopped. The opening and closing of the hydrogen/methane gas supply valve V6 is controlled by a control unit.

The methane recovery flow path 19 is a flow path for recovering the methane separated in the methane separator D. A methane recovery valve V9 is provided on the methane recovery flow path 19. When the methane recovery valve V9 is open, methane is supplied to the methane storage tank M. On the other hand, when the methane recovery valve V9 is closed, the supply of methane to the methane storage tank M is stopped. The opening and closing of the methane recovery valve V9 is controlled by the control unit.

The hydrogen/methane gas storage tank E is a tank for storing the residual gas remaining after a portion of the methane is separated in the methane separator D. The hydrogen/methane gas storage tank E is connected to a hydrogen/methane gas supply flow path 16 and a hydrogen/methane gas supply flow path 17.

The hydrogen/methane gas storage device is not particularly limited as long as it is a container capable of storing gas, and examples thereof include storage tanks.

The hydrogen supply source H is a supply source for supplying hydrogen to the carbon dioxide capture and reduction device C. A hydrogen supply flow path 18 is connected to the hydrogen supply source H. It is preferable that hydrogen is supplied as hydrogen gas.

The methane storage tank M is a tank for storing the methane separated by the methane separator. A methane recovery passage 19 is connected to the methane storage tank M.

Next, a carbon dioxide capture method using the carbon dioxide capture device of the first embodiment will be described with reference to FIG. 2. FIG. 2 is a flowchart showing a carbon dioxide capture method using the carbon dioxide capture device of the first embodiment.

Initially, the atmospheric supply valve V1, the first combustion gas supply valve V2, the second combustion gas supply valve V3, the gas exhaust valve V4, the product gas supply valve V5, the hydrogen/methane gas supply valve V6, the hydrogen/methane gas supply valve V7, the hydrogen supply valve V8, and the methane recovery valve V9 are closed. Also, it is assumed that methane and hydrogen are stored in the hydrogen/methane gas storage tank E beforehand. Although not shown, each valve is electrically connected to a control unit (e.g., a computer) and can be opened and closed by a signal from the control unit.

First, the control unit starts the operation of combustor A and opens the atmosphere supply valve V1, the first combustion gas supply valve V2, the second combustion gas supply valve V3, the gas exhaust valve V4, and the hydrogen/methane gas supply valve V7 (step S11).

When the atmospheric supply valve V1 is opened, atmospheric air is supplied to combustor A via the atmospheric supply passage 11. The carbon dioxide concentration in the atmosphere is approximately 400 ppm. When the hydrogen/methane gas supply valve V7 is opened, hydrogen/methane gas is supplied to combustor A via the hydrogen/methane gas supply passage 17. The hydrogen/methane gas is combusted in combustor A, generating combustion gas.

When the first combustion gas supply valve V2 is opened, combustion gas is supplied from the combustor A to the heat utilization device B via the combustion gas supply passage 12. In the heat utilization device B, the thermal energy of the combustion gas is used, and the temperature of the combustion gas is reduced.

When the second combustion gas supply valve V3 is opened, combustion gas is supplied from the heat utilization equipment B to the carbon dioxide capture and reduction device C via the second combustion gas supply passage 13.

In the carbon dioxide capture and reduction device C, the carbon dioxide contained in the combustion gas is absorbed in the carbon dioxide absorption and reduction catalyst. Specifically, in the carbon dioxide capture and reduction device C, the calcium oxide contained in the carbon dioxide absorption and reduction catalyst reacts with carbon dioxide to form calcium carbonate. As a result, the carbon dioxide concentration at the gas exhaust port of the carbon dioxide capture and reduction device C is lower than the carbon dioxide concentration at the gas supply port.

When the gas exhaust valve V4 is opened, the residual gas in the carbon dioxide capture and reduction device C is exhausted to the atmosphere through the gas exhaust passage 14. The residual gas contains nitrogen, water vapor, and carbon dioxide. The carbon dioxide concentration contained in the residual gas exhausted to the atmosphere is 10 ppm or less.

The control unit then determines whether or not a condition for stopping the supply of combustion gas has been met (step S12). An example of the supply stopping condition is that the amount of combustion gas supplied to the carbon dioxide capture and reduction device C has reached a preset supply amount. Another example of the supply stopping condition is that the carbon dioxide concentration at the gas outlet of the carbon dioxide capture and reduction device C has exceeded a preset concentration (e.g., 10 ppm).

When the control unit determines that the combustion gas supply stop condition is met (step S12: YES), it stops the operation of the combustor A and closes the atmosphere supply valve V1, the first combustion gas supply valve V2, the second combustion gas supply valve V3, the gas exhaust valve V4, and the hydrogen/methane gas supply valve V7 (step S13). Until the control unit determines that the combustion gas supply stop condition is met, combustion gas is supplied from the heat utilization equipment B to the carbon dioxide capture and reduction device C, and the residual gas in the carbon dioxide capture and reduction device C is exhausted to the atmosphere via the gas exhaust passage 14 (step S12: NO).

Next, the control unit opens the product gas supply valve V5, the hydrogen/methane gas supply valve V6, the hydrogen supply valve V8, and the methane recovery valve V9 (step S14).

When the hydrogen supply valve V8 is opened, hydrogen gas is supplied from the hydrogen supply source H to the carbon dioxide capture and reduction device C via the hydrogen supply passage 18.

In the carbon dioxide capture and reduction device C, the carbon dioxide stored in the carbon dioxide storage and reduction catalyst is desorbed and reduced by hydrogen. This produces a product gas that mainly contains methane and hydrogen.

By opening the product gas supply valve V5, the product gas is supplied from the carbon dioxide capture and reduction device C to the methane separator D via the product gas supply passage 15. In the methane separator D, the product gas is separated by membrane separation into gas with a relatively high methane concentration (high-concentration methane-containing gas) and gas with a relatively low methane concentration (low-concentration methane-containing gas).

When the methane recovery valve V9 is opened, the high-concentration methane-containing gas separated in the methane separator D is supplied from the methane separator D to the methane storage tank M via the methane recovery passage 19 and stored in the methane storage tank M. The high-concentration methane-containing gas contains hydrogen and methane.

When the hydrogen/methane gas supply valve V6 is opened, the low-concentration methane-containing gas separated in the methane separator D is supplied from the methane separator D to the hydrogen/methane gas storage tank E via the hydrogen/methane gas supply passage 16. The low-concentration methane-containing gas contains hydrogen and methane.

Next, the control unit determines whether or not the hydrogen supply stop condition is satisfied (step S15). For example, the hydrogen supply stop condition is that the amount of hydrogen supplied to the carbon dioxide capture and reduction device C reaches a preset supply amount. In addition, for example, the hydrogen supply stop condition is that the methane concentration at the gas outlet of the carbon dioxide capture and reduction device C falls below a preset concentration (for example, 1% by volume).

When the control unit determines that the hydrogen supply stop condition is met (step S15: YES), it closes the product gas supply valve V5, the hydrogen/methane gas supply valve V6, the hydrogen supply valve V8, and the methane recovery valve V9 (step S16). Hydrogen is supplied to the carbon dioxide recovery and reduction unit C until the control unit determines that the hydrogen supply stop condition is met (step S15: NO).

The control unit determines whether there is a heat request from heat utilization device B (step S17).

When the control unit determines that there is a heat request from heat utilization device B (step S17: YES), it returns to step S11 and repeats the process from step S11 onward. When the control unit determines that there is no heat request from heat utilization device B (step S17: NO), it ends this process.

When the carbon dioxide capture device 100 of the first embodiment is used, it is possible to directly take in the atmosphere. The carbon dioxide storage reduction catalyst housed in the carbon dioxide capture reducer C contains calcium oxide. Calcium oxide reacts with carbon dioxide to become calcium carbonate. By reacting carbon dioxide with calcium oxide, it is possible to make the carbon dioxide concentration contained in the gas discharged from the gas exhaust passage 14 to the atmosphere lower than the carbon dioxide concentration in the atmosphere. In other words, when the carbon dioxide capture device 100 of the first embodiment is used, it is possible to take in the atmosphere and capture the carbon dioxide contained in the taken-in atmosphere. In addition, the carbon dioxide storage reduction catalyst housed in the carbon dioxide capture reducer C contains ruthenium (Ru), and by supplying hydrogen to the carbon dioxide capture reducer C, it is possible to convert calcium carbonate to methane.

Normally, in order to desorb carbon dioxide from calcium carbonate, it is necessary to heat it to about 1000°C. When desorbing carbon dioxide from calcium carbonate, if the temperature rise is 1000°C, the sensible heat of calcium carbonate is about 83 kJ per mole, and the heat of desorption is 175 kJ per mole of carbon dioxide. When carbon dioxide is converted to methane, 177 kJ of heat is generated per mole of carbon dioxide. In contrast, the reaction of converting calcium carbonate to methane proceeds at about 300°C. In the carbon dioxide capture device 100 of the first embodiment, the heat (177 kJ per mole of carbon dioxide) generated when obtaining 1 mole of methane and 2 moles of water from 1 mole of carbon dioxide and 4 moles of hydrogen can be used to supplement the energy (175 kJ per mole of carbon dioxide) required to desorb carbon dioxide from calcium carbonate. In other words, when the carbon dioxide capture device 100 of the first embodiment is used, carbon dioxide can be efficiently taken in from the atmosphere and converted into methane, which is a fuel, with low energy.

In the first embodiment, the carbon dioxide concentration in the atmosphere is about 400 ppm, but the carbon dioxide concentration is not particularly limited. In addition, in the first embodiment, the carbon dioxide storage reduction catalyst includes calcium oxide and ruthenium (Ru), but the carbon dioxide storage reduction catalyst is not limited to the above.

[Second embodiment]
3 is a schematic diagram showing a carbon dioxide capture device of the second embodiment. Note that, in the carbon dioxide capture device of the second embodiment, the same components and functions as those of the carbon dioxide capture device of the first embodiment are denoted by the same reference numerals and will not be described.

The following describes the configuration of the carbon dioxide capture device 200 of the second embodiment that differs from the carbon dioxide capture device 100 of the first embodiment.

The carbon dioxide capture device 200 of the second embodiment is provided with a carbon dioxide adsorbent F that contains an adsorption material having carbon dioxide adsorption capacity between the heat utilization equipment B and the carbon dioxide capture and reduction device.

The carbon dioxide absorber F contains zeolite as an adsorption material. The carbon dioxide absorber F is connected to the second combustion gas supply passage 13a, the hydrogen supply passage 18a, and the gas supply passage 20.

In addition to zeolites, other adsorbent materials include activated carbon, silica gel, and amine-supported solids.

The carbon dioxide absorber F is also fitted with a carbon dioxide detection sensor (not shown) as a concentration detector. The carbon dioxide detection sensor is a device that detects the carbon dioxide concentration in the atmosphere of the carbon dioxide absorber F and is connected to the control unit.

The second combustion gas supply passage 13a is a passage for supplying the combustion gas discharged from the heat utilization equipment B to the carbon dioxide absorber F. A second combustion gas supply valve V3a is provided on the second combustion gas supply passage 13a. When the second combustion gas supply valve V3a is open, the combustion gas is supplied to the carbon dioxide absorber F. On the other hand, when the second combustion gas supply valve V3a is closed, the supply of the combustion gas to the carbon dioxide absorber F is stopped. The opening and closing of the second combustion gas supply valve V3a is controlled by the control unit.

The gas supply flow path 20 is a flow path for supplying the residual gas after the carbon dioxide is absorbed in the carbon dioxide absorber F to the carbon dioxide capture and reduction device C. A gas supply valve V10 is provided on the gas supply flow path 20. When the gas supply valve V10 is open, the residual gas is supplied to the carbon dioxide capture and reduction device C. On the other hand, when the gas supply valve V10 is closed, the supply of the residual gas to the carbon dioxide capture and reduction device C is stopped. The opening and closing of the gas supply valve V10 is controlled by the control unit.

Next, a carbon dioxide capture method using the carbon dioxide capture device 200 of the second embodiment will be described with reference to FIG. 4. FIG. 4 is a flowchart showing a carbon dioxide capture method using the carbon dioxide capture device of the second embodiment.

Initially, the atmospheric supply valve V1, the first combustion gas supply valve V2, the second combustion gas supply valve V3a, the gas exhaust valve V4, the product gas supply valve V5, the hydrogen/methane gas supply valve V6, the hydrogen/methane gas supply valve V7, the hydrogen supply valve V8a, the methane recovery valve V9, and the gas supply valve V10 are closed.

First, the control unit starts the operation of combustor A and opens the atmosphere supply valve V1, the first combustion gas supply valve V2, the second combustion gas supply valve V3a, the gas exhaust valve V4, the hydrogen/methane gas supply valve V7, and the gas supply valve V10 (step S21).

The gas flow caused by opening the atmospheric supply valve V1, the first combustion gas supply valve V2, the gas exhaust valve V4, and the hydrogen/methane gas supply valve V7 is the same as in the first embodiment.

When the second combustion gas supply valve V3a is opened, combustion gas is supplied from the heat utilization device B to the carbon dioxide absorber F via the second combustion gas supply passage 13a. The carbon dioxide concentration contained in the combustion gas supplied to the carbon dioxide absorber F is, for example, 10% by volume.

In the carbon dioxide absorber F, the carbon dioxide contained in the combustion gas is absorbed into the zeolite. This reduces the carbon dioxide concentration at the gas exhaust port compared to the carbon dioxide concentration at the gas supply port of the carbon dioxide absorber F.

When the gas supply valve V10 is opened, the residual gas in the carbon dioxide absorber F is supplied to the carbon dioxide recovery reducer C via the gas supply passage 20. The residual gas contains nitrogen, water vapor, and carbon dioxide. The carbon dioxide concentration contained in the residual gas supplied to the carbon dioxide recovery reducer C is, for example, 3000 ppm.

In the carbon dioxide capture and reduction device C, the carbon dioxide contained in the residual gas is absorbed in the carbon dioxide absorption and reduction catalyst. Specifically, in the carbon dioxide capture and reduction device C, the calcium oxide contained in the carbon dioxide absorption and reduction catalyst reacts with carbon dioxide to form calcium carbonate. As a result, the carbon dioxide concentration at the gas exhaust port of the carbon dioxide capture and reduction device C is lower than the carbon dioxide concentration at the gas supply port.

When the gas exhaust valve V4 is opened, the residual gas in the carbon dioxide capture and reduction device C is exhausted to the atmosphere through the gas exhaust passage 14. The residual gas contains nitrogen, water vapor, and carbon dioxide. The carbon dioxide concentration contained in the residual gas exhausted to the atmosphere is 10 ppm or less.

Next, the control unit determines whether or not the supply stop condition for the combustion gas is satisfied (step S22). The supply stop condition may be the same as that in the first embodiment.

When the control unit determines that the combustion gas supply stop condition is met (step S22: YES), it stops the operation of the combustor A and closes the atmosphere supply valve V1, the first combustion gas supply valve V2, the second combustion gas supply valve V3a, the gas exhaust valve V4, the hydrogen/methane gas supply valve V7, and the gas supply valve V10 (step S23). Until the control unit determines that the combustion gas supply stop condition is met, the combustion gas is supplied from the heat utilization equipment B to the carbon dioxide absorber F, and the residual gas in the carbon dioxide capture and reduction device C is exhausted to the atmosphere via the gas exhaust passage 14 (step S22: NO).

After step S23, the same processing as steps S14 to S16 in the first embodiment is performed (steps S24 to S26), except that the hydrogen supply valve V8a is opened and closed instead of the hydrogen supply valve V8, and the gas supply valve V10 is additionally opened and closed.

The gas flow caused by opening the product gas supply valve V5, the hydrogen/methane gas supply valve V6, and the methane recovery valve V9 is the same as in the first embodiment.

When the hydrogen supply valve V8a is opened, hydrogen gas is supplied from the hydrogen supply source H to the carbon dioxide absorber F via the hydrogen supply passage 18a.

In the carbon dioxide absorber F, the carbon dioxide absorbed in the zeolite is desorbed by applying heat.

When the gas supply valve V10 is opened, hydrogen and the carbon dioxide desorbed in the carbon dioxide absorber F are supplied to the carbon dioxide recovery reducer C via the gas supply passage 20.

In the carbon dioxide capture and reduction device C, the carbon dioxide stored in the carbon dioxide storage and reduction catalyst is desorbed and reduced by hydrogen together with the carbon dioxide supplied from the carbon dioxide storage device F. This produces a product gas that mainly contains methane and hydrogen.

After step S26, the control unit determines whether there is a heat request from heat utilization device B (step S27).

When the control unit determines that there is a heat request from heat utilization device B (step S27: YES), the control unit returns to step S21 and repeats the process from step S21 onward. When the control unit determines that there is no heat request from heat utilization device B (step S27: NO), the control unit ends this process.

In the second embodiment of the carbon dioxide capture device 200, a carbon dioxide absorber F is provided between the combustor A and the carbon dioxide capture and reduction device C, so that more carbon dioxide can be captured and converted to methane.

The adsorption material contained in the carbon dioxide absorber F tends to have a lower storage capacity when the carbon dioxide concentration is low. On the other hand, the calcium oxide contained in the carbon dioxide capture and reduction device C does not have a lower storage capacity even when the carbon dioxide concentration is low. However, the energy required to desorb carbon dioxide is greater for calcium oxide than for the adsorption material. In the carbon dioxide capture device 200 of the second embodiment, high-concentration carbon dioxide is absorbed by the adsorption material, and low-concentration carbon dioxide is absorbed by calcium oxide, thereby further reducing the carbon dioxide concentration and reducing the energy required to desorb carbon dioxide.

In addition, in the carbon dioxide capture device 200 of the second embodiment, exhaust heat can be used to desorb carbon dioxide from the adsorption material. The reaction between the gaseous carbon dioxide desorbed from the adsorption material and hydrogen proceeds more easily than the reaction between calcium carbonate and hydrogen, making it possible to efficiently obtain methane from the high concentration of carbon dioxide occluded in the adsorption material.

The carbon dioxide capture device 200 of the second embodiment can utilize the heat (175 kJ per mole of carbon dioxide) generated when carbon dioxide is absorbed in the carbon dioxide capture and reduction device C and the heat (177 kJ per mole of carbon dioxide) generated when the absorbed carbon dioxide is converted to methane as energy for desorbing carbon dioxide from the carbon dioxide absorber F, resulting in excellent energy efficiency.

In the second embodiment, the carbon dioxide concentration in the combustion gas is 10% by volume, but the carbon dioxide concentration is not particularly limited. In addition, in the second embodiment, the carbon dioxide storage reduction catalyst contains calcium oxide and ruthenium (Ru), but the carbon dioxide storage reduction catalyst is not limited to the above.

[Third embodiment]
5 is a schematic diagram showing a carbon dioxide capture device of the third embodiment. Note that, in the carbon dioxide capture device of the third embodiment, the same configurations and effects as those of the carbon dioxide capture device 100 of the first embodiment and the carbon dioxide capture device 200 of the second embodiment are denoted by the same reference numerals and will not be described.

The following describes the configuration of the carbon dioxide capture device 300 of the third embodiment that differs from the carbon dioxide capture device 200 of the second embodiment.

The carbon dioxide capture device 300 of the third embodiment is provided with a methane converter G between the carbon dioxide capture reducer C and the methane separator D, which converts the mixed gas discharged from the carbon dioxide capture reducer C into methane. The carbon dioxide capture reducer C is connected to a gas discharge flow path 14, a product gas supply flow path 15a, and a gas supply flow path 20.

The product gas supply flow passage 15a is a flow passage for supplying the carbon dioxide desorbed from the zeolite contained in the carbon dioxide storage device F and the product gas obtained by the methanation reaction of the carbon dioxide stored in the carbon dioxide capture and reduction device C to the methane converter G. A product gas supply valve V5a is provided on the product gas supply flow passage 15a. When the product gas supply valve V5a is open, the product gas is supplied to the methane converter G. On the other hand, when the product gas supply valve V5a is closed, the supply of the product gas to the methane converter G is stopped. The opening and closing of the product gas supply valve V5a is controlled by the control unit.

The methane converter G is a device for converting the mixed gas discharged from the carbon dioxide capture and reduction device C into methane. The methane converter G contains a methanation catalyst. The product gas supply flow path 15a and the product gas supply flow path 21 are connected to the methane converter G. The methanation catalyst is a catalyst in which a metal having methanation catalytic performance is supported on a carrier. The metal having methanation catalytic performance is ruthenium (Ru), and the carrier is alumina.

In addition to ruthenium (Ru), examples of metals having methanation catalytic performance include nickel (Ni), platinum (Pt), palladium (Pd), rhodium (Rd), cobalt (Co), iron (Fe), and manganese (Mn). These metals may be used alone or in combination of two or more. In addition to alumina, examples of supports include silica, silica-alumina, titania, zirconia, ceria, and ceria-zirconia.

The product gas supply flow path 21 is a flow path for supplying the product gas generated in the methane converter G to the methane separator D. A product gas supply valve V11 is provided on the product gas supply flow path 21. When the product gas supply valve V11 is open, the product gas is supplied to the methane separator D. On the other hand, when the product gas supply valve V11 is closed, the supply of the product gas to the methane separator D is stopped. The opening and closing of the product gas supply valve V11 is controlled by the control unit.

Next, a carbon dioxide capture method using the carbon dioxide capture device 300 of the third embodiment will be described. Next, with reference to FIG. 6, a carbon dioxide capture method using the carbon dioxide capture device 300 of the third embodiment will be described. FIG. 6 is a flowchart showing a carbon dioxide capture method using the carbon dioxide capture device of the third embodiment.

Initially, the atmospheric supply valve V1, the first combustion gas supply valve V2, the second combustion gas supply valve V3a, the gas exhaust valve V4, the generated gas supply valve V5a, the hydrogen/methane gas supply valve V6, the hydrogen/methane gas supply valve V7, the hydrogen supply valve V8, the methane recovery valve V9, the gas supply valve V10, and the generated gas supply valve V11 are closed.

First, the same processing as steps S21 to S23 in the second embodiment is performed (step S31).

After step S31, the control unit opens the product gas supply valve V5a, the hydrogen/methane gas supply valve V6, the hydrogen supply valve V8, the methane recovery valve V9, the gas supply valve V10, and the product gas supply valve V11 (step S32).

After step S31, the same processing as steps S24 to S26 in the second embodiment is performed (steps S32 to S34), except that instead of opening and closing the generated gas supply valve V5, the generated gas supply valve V5a is opened and closed, and the generated gas supply valve V11 is additionally opened and closed.

The gas flow caused by opening the hydrogen/methane gas supply valve V6, hydrogen supply valve V8, methane recovery valve V9, and gas supply valve V10 is the same as in the second embodiment.

When the product gas supply valve V5a is opened, the product gas obtained in the carbon dioxide capture and reduction device C is supplied from the carbon dioxide storage device F to the methane converter G via the product gas supply passage 15a. The product gas mainly contains methane and hydrogen.

In the methane converter G, the carbon dioxide contained in the mixed gas supplied from the carbon dioxide capture and reduction device C is converted to methane by the methanation catalyst and hydrogen. This produces hydrogen and high-concentration methane.

When the product gas supply valve V11 is opened, the product gas obtained in the methane converter G is supplied from the methane converter G to the methane separator D via the product gas supply passage 21. The product gas contains hydrogen and a high concentration of methane.

After step S34, the control unit determines whether there is a heat request from heat utilization device B (step S35).

When the control unit determines that there is a heat request from heat utilization device B (step S35: YES), it returns to step S31 and repeats the process from step S31 onward. When the control unit determines that there is no heat request from heat utilization device B (step S35: NO), it ends this process.

In the third embodiment of the carbon dioxide capture device 300, a methane converter G is disposed downstream of the carbon dioxide capture reducer C and the carbon dioxide storage device F. When the rate at which a mixed gas of carbon dioxide desorbed from the carbon dioxide storage device F and circulating hydrogen is converted to methane in the carbon dioxide capture reducer C is low, a mixed gas of carbon dioxide and hydrogen is discharged from the carbon dioxide capture reducer C. By passing this mixed gas through the methane converter G, the carbon dioxide concentration of the gas supplied to the methane separator D can be reduced and the methane concentration can be improved.

[Fourth embodiment]
7 is a schematic diagram showing a carbon dioxide capture device of the fourth embodiment. Note that, in the carbon dioxide capture device of the fourth embodiment, the same configurations and effects as those of the carbon dioxide capture device 100 of the first embodiment, the carbon dioxide capture device 200 of the second embodiment, and the carbon dioxide capture device 300 of the third embodiment will be denoted by the same reference numerals and will not be described.

The following describes the configuration of the carbon dioxide capture device 400 of the fourth embodiment that differs from the carbon dioxide capture device 300 of the third embodiment.

In the carbon dioxide capture device 400 of the fourth embodiment, unlike the carbon dioxide capture device 300 of the third embodiment, the gas supply flow path 22 and the product gas supply flow path 15b are connected to the carbon dioxide occlusion device F, and the hydrogen supply source H is not connected. The hydrogen supply source H is connected to the carbon dioxide capture reduction device C.

The gas supply flow path 22 is a flow path for supplying the product gas obtained by the methanation reaction of the carbon dioxide absorbed in the carbon dioxide capture and reduction device C to the carbon dioxide absorber F. A gas supply valve V12 is provided on the gas supply flow path 22. When the gas supply valve V12 is open, the product gas is supplied to the carbon dioxide absorber F. On the other hand, when the gas supply valve V12 is closed, the supply of the product gas to the carbon dioxide absorber F is stopped. The opening and closing of the gas supply valve V12 is controlled by the control unit.

The product gas supply flow passage 15b is a flow passage for supplying the product gas obtained by the methanation reaction of the carbon dioxide stored in the carbon dioxide capture and reduction device C and the carbon dioxide desorbed from the zeolite contained in the carbon dioxide storage device F to the methane converter G. A product gas supply valve V5b is provided on the product gas supply flow passage 15b. When the product gas supply valve V5b is open, the product gas is supplied to the methane converter G. On the other hand, when the product gas supply valve V5b is closed, the supply of the product gas to the methane converter G is stopped. The opening and closing of the product gas supply valve V5b is controlled by the control unit.

In the carbon dioxide capture device 400 of the fourth embodiment, the product gas is supplied from the carbon dioxide capture reducer C to the carbon dioxide occluder F via the gas supply passage 22. The product gas mainly contains hydrogen and methane. The methane converter G is supplied with the product gas obtained by the methanation reaction of the carbon dioxide occluded in the carbon dioxide capture reducer C and the carbon dioxide desorbed from the zeolite contained in the carbon dioxide occluder F. Since the methane converter G can utilize the hydrogen supplied in excess for the methanation reaction in the carbon dioxide capture reducer C, a higher concentration of methane can be obtained compared to the carbon dioxide capture device 300 of the third embodiment.

[Fifth embodiment]
8 is a schematic diagram showing a carbon dioxide capture device of the fifth embodiment. Note that, for the carbon dioxide capture device of the fourth embodiment, the same reference numerals are used for the same configurations and effects as those of the carbon dioxide capture device 100 of the first embodiment, the carbon dioxide capture device 200 of the second embodiment, the carbon dioxide capture device 300 of the third embodiment, and the carbon dioxide capture device 400 of the fourth embodiment, and the description thereof will be omitted.

The following describes the configuration of the carbon dioxide capture device 500 of the fifth embodiment that differs from the carbon dioxide capture device 400 of the fourth embodiment.

The fifth embodiment of the carbon dioxide capture device 500 further includes a dehumidifier K for removing moisture between the carbon dioxide capture and reduction device C and the carbon dioxide adsorber F.

There are no particular limitations on the dehumidifier K, so long as it is a device that has the function of removing moisture from the gas supplied from the carbon dioxide capture and reduction device to the carbon dioxide absorption device F. The dehumidifier K may contain a moisture absorbent such as silica gel. The dehumidifier K may also have the function of lowering the temperature of the gas to condense the water.

The carbon dioxide capture device 500 of the fifth embodiment is equipped with a dehumidifier K, so that the gas produced by the methanation reaction in the carbon dioxide capture reducer C from which water vapor has been removed is supplied to the carbon dioxide occlusion device F. Therefore, in the carbon dioxide occlusion device F, the adsorption of carbon dioxide is efficiently carried out without being inhibited by water vapor.

[Modification 1]
The carbon dioxide capture devices of the first to fifth embodiments may include a flow path for supplying the low-concentration methane-containing gas after methane separation in the methane separator D to the carbon dioxide capture and reducer C. Specifically, the hydrogen/methane gas supply flow path 16 connected to the hydrogen/methane gas storage device E may be branched to form a flow path for supplying to the carbon dioxide capture and reducer C. The low-concentration methane-containing gas after methane separation in the methane separator D contains hydrogen. By supplying the low-concentration methane-containing gas to the carbon dioxide capture and reducer C, the hydrogen contained in the low-concentration methane-containing gas can be used for the methanation reaction in the carbon dioxide capture and reducer C.

[Modification 2]
The carbon dioxide capture devices of the first to fifth embodiments include only one carbon dioxide capture/reducer C, but may include two or more carbon dioxide capture/reducers. By using two or more carbon dioxide capture/reducers in rotation, it is possible to capture carbon dioxide in some of the carbon dioxide capture/reducers and perform the methanation reaction in other parts of the carbon dioxide capture/reducers, and it is possible to continuously supply heat using a burner or the like and continuously capture carbon dioxide from the atmosphere.

[Modification 3]
As in Modification 2, the carbon dioxide capture devices of the second to fifth embodiments include only one carbon dioxide occluder F, but may include two or more carbon dioxide occluders. By using two or more carbon dioxide occluders in rotation, it is possible to occlude carbon dioxide in some of the carbon dioxide occluders and desorb carbon dioxide in other of the carbon dioxide occluders, and thus it is possible to continuously capture carbon dioxide from the atmosphere.

[Modification 4]
In the carbon dioxide capture devices of the fourth and fifth embodiments, the gas supply flow path 20 and the gas supply flow path 22 are connected between the carbon dioxide capture and reduction device C and the carbon dioxide occlusion device F, but only one gas supply flow path may be connected between the carbon dioxide capture and reduction device C and the carbon dioxide occlusion device F. This realizes a simplified configuration of the carbon dioxide capture device.

[Comparative Example 1]
Comparative Example 1 is a conventional carbon dioxide capture device described in Non-Patent Document 1. In the conventional carbon dioxide capture device, first, carbon dioxide taken in from the atmosphere is reacted with an aqueous potassium hydroxide solution to obtain an aqueous potassium carbonate solution. Next, the aqueous potassium carbonate solution is reacted with calcium hydroxide to obtain calcium carbonate. In a calcination furnace, carbon dioxide is desorbed from the calcium carbonate.

As mentioned above, it is usually necessary to heat calcium carbonate to about 1000°C in order to desorb carbon dioxide. In contrast, the reaction that converts calcium carbonate to methane proceeds at about 300°C. By using the carbon dioxide capture device 100 of the first embodiment, carbon dioxide can be efficiently captured from the atmosphere and converted into methane, a fuel, with low energy.

[Comparative Example 2]
9 is a schematic diagram showing a carbon dioxide capture device 600 of Comparative Example 2. Unlike the carbon dioxide capture device 300 of the third embodiment, the carbon dioxide capture device 600 does not include a carbon dioxide capture and reduction device C. A hydrogen supply flow path 18a for supplying hydrogen from a hydrogen supply source H and a gas exhaust flow path 14a for exhausting residual gas not absorbed in the carbon dioxide absorber F to the atmosphere are connected to the carbon dioxide occlusion device F. A hydrogen supply valve V8a is provided on the hydrogen supply flow path 18a, and a gas exhaust valve V4a is provided on the gas exhaust flow path 14a.

The adsorption material (e.g., zeolite) contained in the carbon dioxide absorber F has a small absorption capacity when the carbon dioxide concentration is low. If a system is considered in which the adsorption material absorbs carbon dioxide until the carbon dioxide concentration becomes low, the amount of carbon dioxide absorbed per weight or volume of the adsorption material is small, so the device for recovering carbon dioxide needs to be large.

In contrast, the carbon dioxide capture device of this embodiment is equipped with a carbon dioxide capture and reduction device C that houses a carbon dioxide storage and reduction catalyst. The calcium oxide contained in the carbon dioxide storage and reduction catalyst does not lose its storage capacity even when the carbon dioxide concentration is as low as about 400 ppm. Therefore, compared to Comparative Example 2, a device with a smaller volume can capture the same amount of carbon dioxide from the atmosphere.

11 Atmosphere supply flow path 12 First combustion gas supply flow path 13 Second combustion gas supply flow path 14, 14a Gas exhaust flow path 15, 15a, 15b Produced gas supply flow path 16 Hydrogen/methane gas supply flow path 17 Hydrogen/methane gas supply flow path 18, 18a Hydrogen supply flow path 19 Methane recovery flow path 20 Gas supply flow path 21 Gas supply flow path 22 Produced gas supply flow path 100, 200, 300, 400, 500, 600 Carbon dioxide recovery device A Combustor B Heat utilization equipment C Carbon dioxide recovery reducer D Methane separator E Hydrogen/methane gas storage device F Carbon dioxide storage device G Methane converter H Hydrogen supply source K Dehumidifier M Methane storage device V1 Atmosphere supply valve V2 First combustion gas supply valve V3 Second combustion gas supply valve V4, V4a Gas exhaust valve V5, V5a, V5b Produced gas supply valve V6 Hydrogen/methane gas supply valve V7 Hydrogen/methane gas supply valve V8, V8a Hydrogen supply valve V9 Methane recovery valve V10 Gas supply valve V11 Gas supply valve V12 Produced gas supply valve

Claims (11)

an atmosphere supply passage for taking in atmosphere;
a combustor to which air is supplied from the air supply passage and which generates a combustion gas;
A hydrogen source that supplies hydrogen;
A carbon dioxide capture and reduction device that captures carbon dioxide contained in the combustion gas and contains a material that converts the captured carbon dioxide into fuel using the hydrogen;
A carbon dioxide capture device comprising: The carbon dioxide capture device according to claim 1, wherein the material is a carbon dioxide storage/reduction catalyst that includes a metal oxide having carbon dioxide storage capability and a metal having methanation catalytic capability. a gas exhaust passage for exhausting residual gas after the carbon dioxide is captured by the carbon dioxide occlusion reduction catalyst to the atmosphere;
a methane separator for separating a portion of methane from a methane-containing gas containing methane obtained by the conversion of carbon dioxide;
The carbon dioxide capture device according to claim 2, further comprising a methane gas supply passage for supplying the low-concentration methane-containing gas separated in the methane separator to at least one of the combustor and the carbon dioxide capture and reduction device. The carbon dioxide capture device according to claim 3, wherein the methane gas supply passage is a passage for supplying the low-concentration methane-containing gas separated by the methane separator to the combustor. The carbon dioxide capture device according to any one of claims 1 to 4, further comprising a carbon dioxide adsorbent that contains an adsorbent material having carbon dioxide adsorption capacity, between the combustor and the carbon dioxide capture and reduction device. a methane separator for separating a portion of methane from a methane-containing gas containing methane obtained by the conversion of carbon dioxide;
a combustion gas supply passage for supplying the combustion gas to the carbon dioxide occlusion device;
a hydrogen supply flow path for supplying hydrogen from the hydrogen supply source to the carbon dioxide occlusion device;
a gas supply passage for supplying gas from the carbon dioxide occlusion device to the carbon dioxide capture and reduction device;
The carbon dioxide capture apparatus according to claim 5 , further comprising a methane-containing gas supply passage for supplying the methane-containing gas from the carbon dioxide capture reducer to the methane separator. a methane separator for separating a portion of methane from a methane-containing gas containing methane obtained by the conversion of carbon dioxide;
a combustion gas supply passage for supplying the combustion gas to the carbon dioxide occlusion device;
a first gas supply passage for supplying gas from the carbon dioxide occlusion device to the carbon dioxide capture and reduction device;
a hydrogen supply passage for supplying hydrogen from the hydrogen supply source to the carbon dioxide capture and reduction device;
a second gas supply passage for supplying gas from the carbon dioxide capture and reduction device to the carbon dioxide occlusion device;
The carbon dioxide capture apparatus according to claim 5 , further comprising a methane-containing gas supply passage for supplying the methane-containing gas from the carbon dioxide absorber to the methane separator. The carbon dioxide capture device according to claim 6, further comprising a methane converter between the methane separator and the carbon dioxide capture reducer for converting carbon dioxide to methane. The carbon dioxide capture device according to claim 7, further comprising a methane converter between the methane separator and the carbon dioxide storage device, for converting carbon dioxide to methane. The carbon dioxide capture device according to any one of claims 5 to 9, further comprising a dehumidifier for removing moisture between the carbon dioxide capture reducer and the carbon dioxide adsorber. Taking in atmospheric air;
the atmospheric air is supplied and a combustion gas is generated;
providing hydrogen;
A step of recovering carbon dioxide contained in the combustion gas and converting the recovered carbon dioxide into fuel using the hydrogen;
A method for capturing carbon dioxide, comprising: