Carbon dioxide capture system

Abstract

To provide a carbon dioxide recovery system which can recover carbon dioxide while avoiding influence of extrinsic factors.SOLUTION: A controller performs an electric power application control which applies adsorption voltage between an action electrode of an electrochemical cell and a counter electrode or applies desorption voltage therebetween, and performs a drive control of a pump where the pump performs suction and discharge of carbon dioxide at least when the electrochemical cell performs desorption of carbon dioxide. The controller acquires electric power information indicating electric power status of a renewable energy system and determines surplus electric power of the renewable energy system based on the electric power information (S400, S410). The controller switches, when the surplus electric power is low, the electric power supply source from the renewable energy system to a household power supply 32 so as to suppress power consumption of the renewable energy system 31 and perform the electric power application control and the driving control (S440).SELECTED DRAWING: Figure 11

Description

Technical Field

[0001] The present disclosure relates to a carbon dioxide recovery system for recovering carbon dioxide from a mixed gas containing carbon dioxide.

Background Art

[0002] In Patent Document 1, a gas separation system for separating carbon dioxide from a mixed gas containing carbon dioxide by an electrochemical reaction has been proposed. In this gas separation system, a mixed gas containing carbon dioxide is introduced into a housing in which an electrochemical cell is disposed. In a charging mode in which electrons are directed to the negative electrode of the electrochemical cell, the electroactive material provided at the negative electrode is reduced. For this reason, a bond between the electroactive material at the negative electrode and carbon dioxide occurs, and carbon dioxide is separated from the mixed gas. On the other hand, in a discharging mode in which an electron flow is generated in a direction opposite to the electron flow during the charging mode, the electroactive material at the negative electrode is oxidized. Thereby, carbon dioxide is released from the electroactive material of the negative electrode.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, carbon dioxide capture systems are expected to be powered by renewable energy systems such as solar, wind, geothermal, and hydroelectric power. However, renewable energy systems also supply power to other systems besides carbon dioxide capture systems. Therefore, the power surplus of renewable energy systems fluctuates depending on the status of other systems. Furthermore, the power surplus of renewable energy systems also fluctuates depending on weather conditions. Thus, carbon dioxide capture systems may not be able to obtain stable power from renewable energy systems due to the influence of external factors. Consequently, it is possible that carbon dioxide capture systems may not be able to capture carbon dioxide due to insufficient power supply.

[0005] This disclosure is made in view of the above-mentioned points and aims to provide a carbon dioxide capture system that can capture carbon dioxide while avoiding the influence of external factors. [Means for solving the problem]

[0006] To achieve the above objectives, the carbon dioxide capture system described herein is A carbon dioxide capture system that operates by receiving power from a renewable energy system (31) and recovers carbon dioxide from a mixed gas containing carbon dioxide through an electrochemical reaction, A carbon dioxide capture tank (16) for storing the captured carbon dioxide, An electrochemical cell having a working electrode containing an adsorbent material capable of adsorbing carbon dioxide, and a counter electrode paired with the working electrode, and a housing that houses the electrochemical cell, with at least one recovery unit (12) into which a mixed gas is supplied, When the adsorbent desorbs the carbon dioxide it has adsorbed, a pump (13) sucks the carbon dioxide desorbed from the adsorbent from the recovery unit and discharges it toward the carbon dioxide recovery tank. The system includes a control device (17) that controls the power application to either apply a first potential between the working electrode and the counter electrode so that the electrochemical cell adsorbs carbon dioxide, or apply a second potential between the working electrode and the counter electrode so that the electrochemical cell desorbs the adsorbed carbon dioxide, and also controls the drive of the pump so that the pump sucks in and discharges carbon dioxide when the electrochemical cell desorbs carbon dioxide. The control device is An acquisition step (S400) to acquire power information indicating the power status of a renewable energy system, A power determination step (S410) determines the power surplus of the renewable energy system based on power information, If the power determination step determines that there is insufficient power reserve, the system includes low-power operation steps (S440, S470) that control power application and drive while reducing the power consumption of the renewable energy system compared to when there is no determined insufficient power reserve.

[0007] Thus, carbon dioxide capture systems control power application and drive while suppressing the electricity consumption of renewable energy systems, enabling carbon dioxide capture even when the power supply from renewable energy systems is unstable due to external factors. In other words, carbon dioxide capture systems enable carbon dioxide capture while avoiding the effects of external factors.

[0008] The reference numbers in parentheses above are merely examples of correspondences with specific configurations in embodiments described later, in order to facilitate understanding of this disclosure, and are not intended to limit the scope of this disclosure in any way.

[0009] Furthermore, technical features described in each claim of the patent claims, other than those described above, will become clear from the description of the embodiments and the accompanying drawings, which will be discussed later. [Brief explanation of the drawing]

[0010] [Figure 1]This is a diagram showing the configuration of a carbon dioxide capture system according to an embodiment. [Figure 2] This is a flowchart showing the processing in a control device for executing a series of control sequences for carbon dioxide capture. [Figure 3] This is a time chart showing the operation of each part when the process shown in the flowchart in Figure 2 is performed. [Figure 4] This is an explanatory diagram illustrating the adsorption mode, scavenging mode, and desorption / recovery mode included in a series of control sequences. [Figure 5] This figure shows an example of adsorption amount change map data. [Figure 6] This figure shows an example of a map data showing changes in the amount of recovery. [Figure 7] This is an enlarged view of section VII in Figure 6. [Figure 8] This flowchart shows the process for creating a map to generate adsorption amount change map data. [Figure 9] This is an explanatory diagram illustrating an example of a method for estimating the maximum adsorption capacity and maximum adsorption time of an electrochemical cell. [Figure 10] This flowchart shows the process for setting the target carbon dioxide adsorption amount. [Figure 11] This flowchart shows the process for determining whether the control device is linked to a renewable energy system. [Figure 12] This flowchart shows the processing in the control unit for executing the control sequence in eco mode. [Modes for carrying out the invention]

[0011] Hereinafter, a carbon dioxide recovery system according to an embodiment of the present disclosure will be described in detail with reference to the drawings. In the plurality of drawings, the same reference numerals are assigned to portions that are identical or equivalent to each other. The carbon dioxide recovery system according to the present embodiment recovers carbon dioxide from a mixed gas containing carbon dioxide (for example, atmospheric gas). The mixed gas from which carbon dioxide has been removed is discharged to the outside (atmosphere). FIG. 1 shows the configuration of the carbon dioxide recovery system 10 according to the present embodiment.

[0012] The carbon dioxide recovery system 10 shown in FIG. 1 includes a flow path opening / closing valve 11, a recovery device 12, a pump 13, a flow path switching valve 14, a sensor 15, a CO2 recovery tank 16, a control device 17, and a blower 19.

[0013] The opening / closing state of the flow path opening / closing valve 11 is controlled by the control device 17. When the flow path opening / closing valve 11 is opened, the mixed gas containing carbon dioxide can be introduced into the recovery device 12 through the flow path piping that connects the outside (atmosphere) and the inside of the recovery device 12. On the other hand, when the flow path opening / closing valve 11 is closed, the flow path piping that connects the outside and the inside of the recovery device 12 is blocked, and the recovery device 12 is sealed from the outside.

[0014] The blower 19 is driven by the control device 17 when the flow path opening / closing valve 11 is open, and sends the mixed gas containing carbon dioxide into the recovery device 12 through the flow path piping that connects the outside and the inside of the recovery device 12. However, the blower 19 may be omitted. Alternatively, the role of the blower 19 may be performed by the pump 13. That is, when the flow path opening / closing valve 11 is open, the pump 13 may be driven to draw the mixed gas containing carbon dioxide from the outside into the recovery device 12 through the above flow path piping.

[0015] The recovery unit 12 includes an electrochemical cell, for example, located inside a metal casing. The electrochemical cell is capable of adsorbing carbon dioxide through an electrochemical reaction, separating it from the mixed gas, and desorbing the adsorbed carbon dioxide, which is then stored in the CO2 recovery tank 16 by a pump 13. The recovery unit 12 has two openings. One opening is an inlet for introducing a mixed gas containing carbon dioxide from the outside into the casing of the recovery unit 12. The other opening is an outlet for discharging the mixed gas from which carbon dioxide has been removed, or the carbon dioxide desorbed from the electrochemical cell. A flow channel piping connecting the outside and the inside of the recovery unit 12 is connected to the inlet, and a flow channel piping equipped with the pump 13 is connected to the outlet. Note that "inside the recovery unit 12" is synonymous with "inside the casing."

[0016] Multiple electrochemical cells are stacked inside the housing of the recovery unit 12. The stacking direction of the multiple electrochemical cells is perpendicular to the flow direction of the mixed gas. Each electrochemical cell is plate-shaped, and its plate surface is arranged to intersect with the cell stacking direction. A predetermined gap is provided between adjacent electrochemical cells. The gap provided between adjacent electrochemical cells serves as a gas channel through which the mixed gas flows.

[0017] Each electrochemical cell is constructed by stacking components such as a working electrode current collector layer, working electrode, separator, counter electrode, and counter electrode current collector layer in the order described. The working electrode is the negative electrode, and the counter electrode, which is paired with the working electrode, is the positive electrode. By changing the potential difference applied between the working electrode and the counter electrode, electrons can be supplied to the working electrode, causing carbon dioxide to be adsorbed onto the carbon dioxide adsorbent on the working electrode, or electrons can be released from the working electrode, causing the adsorbed carbon dioxide to be desorbed. The carbon dioxide adsorbent corresponds to the adsorbent material.

[0018] The working electrode current collector layer consists of a porous conductive material having pores through which a mixed gas containing carbon dioxide can pass. The working electrode current collector layer only needs to have gas permeability and conductivity, and materials such as metallic materials or carbonaceous materials can be used to form the working electrode current collector layer.

[0019] The working electrode is formed from a mixture of materials including a carbon dioxide adsorbent, a conductive material, and a binder. The carbon dioxide adsorbent has the property of adsorbing carbon dioxide by accepting electrons and desorbing the adsorbed carbon dioxide by releasing electrons. For example, polyanthraquinone can be used as the carbon dioxide adsorbent. The conductive material forms a conductive path to the carbon dioxide adsorbent. For example, carbon materials such as carbon nanotubes, carbon black, and graphene can be used as the conductive material. The binder is for holding the carbon dioxide adsorbent and the conductive material. For example, a conductive resin can be used as the binder. For example, the conductive resin can be an epoxy resin containing Ag as a conductive filler, or a fluororesin such as polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF).

[0020] The counter electrode is formed from a mixture of materials including an electroactivating auxiliary, a conductive substance, and a binder. The conductive substance and binder of the counter electrode are the same as those of the working electrode, so their explanation is omitted. The electroactivating auxiliary of the counter electrode is composed of a material having an active substance that acts as an electron donor. The electroactivating auxiliary of the counter electrode is an auxiliary electroactive species that facilitates electron transfer with the carbon dioxide adsorbent of the working electrode. As an electroactivating auxiliary, for example, a metal complex that enables electron transfer by changing the valence of metal ions can be used. Examples of such metal complexes include cyclopentadienyl metal complexes such as ferrocene, nickerosene, and cobaltocene, or porphyrin metal complexes. These metal complexes may be polymers or monomers. The counter electrode current collector layer is formed from a conductive material such as a metal material or a carbonaceous material, similar to the working electrode current collector layer.

[0021] A separator is placed between the working electrode and the counter electrode to separate them. The separator is an insulating ion-permeable membrane that prevents physical contact between the working electrode and the counter electrode, thereby suppressing electrical short circuits, while also allowing ions to pass through. Cellulose membranes, polymers, composite materials of polymers and ceramics, etc., can be used as separators.

[0022] Furthermore, the electrochemical cell is provided with an electrolyte that spans both the working electrode and the counter electrode. For example, an ionic liquid can be used as the electrolyte. An ionic liquid is a salt of a liquid that is non-volatile at room temperature and pressure.

[0023] Pump 13 sucks residual mixed gas remaining in the recovery unit 12 and releases it to the outside (i.e., scavenges the residual mixed gas in the recovery unit 12), and when the carbon dioxide adsorbent desorbs the carbon dioxide it has adsorbed, pump 13 sucks the desorbed carbon dioxide from the recovery unit 12 and discharges it toward the CO2 recovery tank 16. When pump 13 scavenges the residual mixed gas in the recovery unit 12, the flow path shut-off valve 11 shuts off the flow path piping that connects the outside and the inside of the recovery unit 12. Therefore, the scavenging of residual mixed gas in the recovery unit 12 is performed by vacuuming with pump 13. Furthermore, the subsequent discharge of carbon dioxide to the CO2 recovery tank 16 is also performed in a state closer to a vacuum than atmospheric pressure.

[0024] The flow path switching valve 14 is a three-way valve that switches the flow path of the gas flowing through the piping downstream of the pump 13. The switching of the flow path of the flow path switching valve 14 is controlled by the control device 17. Specifically, when a mixed gas containing carbon dioxide is introduced into the recovery unit 12, and when residual mixed gas in the recovery unit 12 is scavenged by the pump 13, the control device 17 controls the flow path switching valve 14 to connect the piping downstream of the pump 13 to the outside (atmosphere). As a result, the mixed gas from which carbon dioxide has been removed, and the residual mixed gas in the recovery unit 12, are released to the outside. On the other hand, when the carbon dioxide adsorbent desorbs the carbon dioxide, and the pump 13 sucks the desorbed carbon dioxide from the recovery unit 12 and discharges it, the control device 17 controls the flow path on / off valve 11 to connect the piping downstream of the pump 13 to the CO2 recovery tank 16. As a result, the carbon dioxide recovered by the recovery unit 12 can be stored in the CO2 recovery tank 16.

[0025] Sensor 15 detects the carbon dioxide concentration and flow rate of the gas flowing through the piping connected to the CO2 recovery tank 16 at predetermined time intervals. The control device 17 can calculate (detect) the amount of carbon dioxide recovered in the CO2 recovery tank 16 from the carbon dioxide concentration and flow rate detected by sensor 15. This amount of carbon dioxide recovered is the result detected via the sensor. Alternatively, the amount of carbon dioxide recovered may be calculated by sensor 15. In this case, sensor 15 outputs the amount of carbon dioxide recovered to the control device 17. The amount of carbon dioxide recovered can also be called the carbon dioxide monitor value. The amount of carbon dioxide recovered can also simply be called the recovered amount.

[0026] The control device 17 consists of a well-known microcomputer and its peripheral devices, including a CPU, ROM, RAM, and other storage devices. The storage devices store adsorption amount change map data and recovery amount change map data. The adsorption amount change map data can also be called adsorption amount change data. The recovery amount change map data can also be called recovery amount change data. As shown in Figure 5, the adsorption amount change map data is associated with the adsorption time and the target carbon dioxide adsorption amount. As shown in Figures 6 and 7, the recovery amount change map data is associated with the change in carbon dioxide recovery amount and the target carbon dioxide adsorption amount. The target carbon dioxide adsorption amount is also called the maximum adsorption amount. The adsorption time is also called the adsorption mode execution time. The adsorption amount change map data and recovery amount change map data will be explained in detail later.

[0027] The control device 17 performs various calculations based on a control program stored in a storage medium such as ROM, and controls the operation of various controlled devices such as the flow path on / off valve 11, the recovery unit 12, the pump 13, the flow path switching valve 14, and the blower 19. It can also be said that the control device 17 controls the drive of the pump 13. Furthermore, the targets of drive control may include not only the pump 13, but also the flow path on / off valve 11, the flow path switching valve 14, and the blower 19. In this embodiment, the control device 17 controls the operation of various controlled devices so that a series of control sequences for carbon dioxide recovery, including at least an adsorption mode and a desorption / recovery mode, are executed in the carbon dioxide recovery system 10. Note that the control sequence may also include a scavenging mode in addition to the above. The desorption / recovery mode indicates that the desorption mode and the recovery mode are combined into a single mode.

[0028] The carbon dioxide capture system 10 configured in this way is connected to a power switching circuit 20. The power switching circuit 20 is controlled by a control device 17.

[0029] The power switching circuit 20 is connected to multiple power supply systems. Here, as an example of a power supply system, a renewable energy system 31 and a household power supply 32 are used. The power switching circuit 20 is a circuit that switches the power supply source to the carbon dioxide capture system 10 between the renewable energy system 31 and the household power supply 32. In other words, the power switching circuit 20 selects one of the multiple power supply systems to be used as the power supply source for the carbon dioxide capture system 10.

[0030] The carbon dioxide capture system 10 is configured to operate by receiving power from either the renewable energy system 31 or the household power supply 32. Normally, the carbon dioxide capture system 10 operates by receiving power from the renewable energy system 31. However, if the power source is switched, the carbon dioxide capture system 10 operates by receiving power from the household power supply 32. In other words, the carbon dioxide capture system 10 receives power from the renewable energy system 31 or the like for the capture unit 12, pump 13, control unit 17, blower 19, etc. The household power supply 32 is a different power supply system from the renewable energy system 31.

[0031] The following describes a series of control sequences for carbon dioxide recovery performed in the carbon dioxide recovery system 10, including at least an adsorption mode, a scavenging mode, and a desorption / recovery mode. Figure 2 is a flowchart showing the processes performed in the control device 17 to execute the control sequence. Figure 3 is a time chart showing the operation of each part when the processes shown in the flowchart of Figure 2 are performed. Figure 4 is an explanatory diagram for describing the adsorption mode, scavenging mode, and desorption / recovery mode included in the series of control sequences.

[0032] As shown in the flowchart of Figure 2, the control device 17 first starts the adsorption mode, which is the first operating mode in a series of control sequences, in step S100. In this adsorption mode, as shown in Figure 3, the flow path valve 11 is opened to allow the mixed gas containing carbon dioxide to be introduced into the recovery device 12. If a blower 19 is provided, the blower 19 is driven to allow more of the mixed gas to be introduced into the recovery device 12. If the pump 13 also serves the role of the blower 19, the pump 13 is driven to suck in the mixed gas and draw it into the recovery device 12 from the outside. In this case, since the pump 13 is driven simply to suck in the mixed gas from the outside, the energy required for this suction is less than the energy required to drive the pump for vacuuming in the scavenging mode and desorption / recovery mode described later.

[0033] Furthermore, in adsorption mode, as shown in Figure 3, an adsorption potential (corresponding to the first potential) is applied between the working electrode and the counter electrode of the electrochemical cell of the recovery unit 12, enabling the carbon dioxide adsorbent of the working electrode to adsorb carbon dioxide. In other words, the control device 17 performs power application control to apply the adsorption potential. In addition, in adsorption mode, as shown in Figure 3, the flow path switching valve 14 is controlled to connect the downstream piping of the pump 13 to the outside.

[0034] Through the control of the flow control valve 11, the electrochemical cells of the recovery unit 12, and the flow control valve 14, in the adsorption mode, as shown by the dotted arrow in Figure 4(a), the mixed gas containing carbon dioxide (atmospheric gas) passes through the flow control valve 11 and enters the recovery unit 12. Once inside the recovery unit 12, the mixed gas is adsorbed by multiple electrochemical cells, removing the carbon dioxide. The mixed gas from which the carbon dioxide has been removed passes through the pump 13 and is guided by the flow control valve 14 to a flow pipe leading to the outside, and is released to the outside through that flow pipe.

[0035] In step S110 of the flowchart in Figure 2, the control device 17 determines whether the adsorption mode execution time has elapsed. The adsorption mode execution time is not constant and changes for several reasons, including estimating the maximum adsorption amount of the electrochemical cell in the map creation process described later, the maximum adsorption time which is the adsorption mode execution time required to obtain that maximum adsorption amount, and optimizing the carbon dioxide recovery amount and energy consumption when the carbon dioxide adsorption performance of the electrochemical cell changes due to environmental changes or aging. This changing adsorption mode execution time is set by the control device 17. In step S110, it is determined whether the set adsorption mode execution time has elapsed. In this embodiment, the maximum adsorption amount is used as the target carbon dioxide adsorption amount. Therefore, below, the maximum adsorption amount will also be referred to as the target carbon dioxide adsorption amount. The maximum adsorption amount can also be called the target adsorption amount.

[0036] In the determination process of step S110, if it is determined that the set adsorption mode execution time has elapsed, the process proceeds to step S120. On the other hand, if it is determined that the set adsorption mode execution time has not elapsed, the determination process of step S110 is repeatedly executed until the adsorption mode execution time has elapsed.

[0037] In step S120, the adsorption mode termination process is executed. Specifically, the control device 17 closes the flow path valve 11 to block the mixed gas flowing into the recovery unit 12 from the outside. If a blower 19 is provided, the control device 17 also stops the operation of the blower 19. The control device 17 also resets the count value of the counter that counts the adsorption mode execution time.

[0038] Thus, the control device 17 applies an adsorption potential to the carbon dioxide adsorbent so that it adsorbs carbon dioxide when the adsorption mode is being executed. The control device 17 applies the adsorption potential only for the duration of the adsorption mode, which corresponds to the target amount of carbon dioxide adsorbed.

[0039] The adsorption mode execution time can be obtained from the adsorption amount change map data. The target carbon dioxide adsorption amount can be obtained from the recovery amount change map data. The control device 17 obtains the target carbon dioxide adsorption amount associated with the carbon dioxide recovery amount detected via the sensor 15 from the recovery amount change map data. As shown in Figure 7, the target carbon dioxide adsorption amount in the recovery amount change map data is a correlation value that correlates with the carbon dioxide recovery amount detected via the sensor 15. Therefore, it can be said that the control device 17 obtains the correlation value that correlates with the carbon dioxide recovery amount detected via the sensor 15 as the target carbon dioxide adsorption amount. Then, the control device 17 obtains the adsorption mode execution time associated with the target carbon dioxide adsorption amount from the adsorption amount change map data. In the example in Figure 5, for example, if the target carbon dioxide adsorption amount is set to 80 [g], the adsorption mode execution time will be 80 [s].

[0040] As shown in Figure 6, the target carbon dioxide adsorption amount is updated according to the amount of carbon dioxide recovered detected via sensor 15. Also, as shown in Figure 5, the adsorption mode execution time changes each time the target carbon dioxide adsorption amount is updated. The target carbon dioxide adsorption amount may be stored in a memory device or the like as an initial calculation threshold or an update threshold.

[0041] In step S130, the control device 17 starts the scavenging mode, which is the second operating mode of the series of control sequences. In this scavenging mode, the flow path valve 11 remains closed, as shown in Figure 3. The adsorption potential applied between the working electrode and the counter electrode of the electrochemical cell of the recoverer 12 is maintained. Communication between the downstream piping of the pump 13 and the outside is also maintained by the flow path switching valve 14.

[0042] In scavenging mode, the pump 13 is started to operate as shown in Figure 3. As described above, the flow path valve 11 is closed, so the recovery unit 12 is sealed upstream of the pump 13. When the pump 13 is started in this state, the residual mixed gas from which carbon dioxide has been removed, which remains in the sealed recovery unit 12, is sucked out of the recovery unit 12 and released to the outside. This allows the residual mixed gas in the recovery unit 12 to be scavenged.

[0043] Furthermore, since the recovery unit 12 upstream of the pump 13 is sealed, the residual mixed gas in the recovery unit 12 is scavenged by vacuuming with the pump 13. For this reason, if the pump 13 also functions as a blower 19, the pump 13 continues to run, but its output is increased compared to the intake mode when the scavenging mode is initiated.

[0044] Through the control of the flow path switching valve 11, the electrochemical cell of the recovery unit 12, the pump 13, and the flow path switching valve 14, in the scavenging mode, as shown by the dotted arrow in Figure 4(b), the residual mixed gas from which carbon dioxide has been removed in the recovery unit 12 passes through the pump 13, is guided by the flow path switching valve 14 to a flow path piping leading to the outside, and is released to the outside through that flow path piping.

[0045] In step S140 of the flowchart in Figure 2, the control device 17 determines whether the scavenging mode execution time has elapsed. This scavenging mode execution time is predetermined to be sufficient time to scavenge the residual mixed gas in the recovery unit 12.

[0046] In the determination process of step S140, if it is determined that a predetermined scavenging mode execution time has elapsed, the process proceeds to step S150. On the other hand, if it is determined that the set scavenging mode execution time has not elapsed, the determination process of step S140 is repeatedly executed until the scavenging mode execution time has elapsed.

[0047] In step S150, the scavenging mode termination process is executed. Specifically, the control device 17 resets the count value of the counter that counts the scavenging mode execution time.

[0048] In step S160, the control device 17 initiates the desorption / recovery mode, which is the third operating mode in the series of control sequences. In this desorption / recovery mode, the flow path valve 11 is kept closed, as shown in Figure 3. The pump 13 also continues to operate with the same drive output as in the scavenging mode, as it draws in carbon dioxide desorbed from the electrochemical cell in a state closer to a vacuum than atmospheric pressure.

[0049] Meanwhile, between the working electrode and the counter electrode of the electrochemical cell of the recovery unit 12, a desorption potential (corresponding to a second potential) is applied, which causes electrons to be released from the working electrode, enabling the carbon dioxide adsorbent on the working electrode to desorb the carbon dioxide adsorbed therefrom. In other words, the control device 17 performs power application control to apply the desorption potential. Furthermore, in the desorption / recovery mode, as shown in Figure 3, the flow path switching valve 14 is controlled to connect the piping downstream of the pump 13 to the CO2 recovery tank 16.

[0050] Through the control of the flow path switching valve 11, the electrochemical cell of the recovery unit 12, the pump 13, and the flow path switching valve 14, in the desorption / recovery mode, as shown by the dotted arrow in Figure 4(c), carbon dioxide desorbed from the electrochemical cell passes through the pump 13 and is guided by the flow path switching valve 14 to a flow path pipe leading to the CO2 recovery tank 16, where it is accumulated. At this time, the concentration and flow rate of carbon dioxide flowing through the flow path pipe toward the CO2 recovery tank 16 are detected by the sensor 15. Based on the detection results of the sensor 15, the control device 17 can calculate the amount of carbon dioxide recovered in the CO2 recovery tank 16 by executing a series of control sequences. The concentration of carbon dioxide flowing through the flow path pipe toward the CO2 recovery tank 16 is usually close to 100%. For this reason, a sensor 15 capable of detecting the flow rate of carbon dioxide may be used.

[0051] Furthermore, the desorption / recovery mode does not necessarily perform carbon dioxide desorption and recovery simultaneously. Instead, carbon dioxide may be desorbed from the electrochemical cell first, and the recovery of the desorbed carbon dioxide may begin after a predetermined time has elapsed since the desorption. In other words, the desorption mode and the recovery mode can be separated, and the start time of the recovery mode can be delayed compared to the start time of the desorption mode, thereby shortening the execution time of the recovery mode. In this case, the pump 13 is temporarily stopped at the start of the desorption mode. With the pump 13 stopped, a desorption potential is applied between the working electrode and the counter electrode of the electrochemical cell to desorb carbon dioxide from the carbon dioxide adsorbent at the working electrode. After a predetermined time has elapsed since the start of the desorption mode and a certain amount of carbon dioxide desorption has progressed, the recovery mode is started and the pump 13 is restarted. As a result, the pump 13 only needs to be driven in the recovery mode, making it possible to drive the pump 13 efficiently. However, even during the recovery mode in which the pump 13 is driven, a desorption potential is applied between the working electrode and the counter electrode of the electrochemical cell, and the desorption of carbon dioxide from the electrochemical cell continues.

[0052] In step S170 of the flowchart in Figure 2, the control device 17 determines whether the desorption / recovery mode execution time or the recovery mode execution time (hereinafter, the desorption / recovery mode will be referred to as the recovery mode) has elapsed. The recovery mode execution time is not constant and changes for reasons such as optimizing the amount of carbon dioxide recovered and the energy consumed when the carbon dioxide adsorption performance of the electrochemical cell changes due to environmental changes or aging. This changing recovery mode execution time is set by the control device 17. In step S170, it is determined whether the set recovery mode execution time has elapsed.

[0053] In the determination process of step S170, if it is determined that the set recovery mode execution time has elapsed, the process proceeds to step S180. On the other hand, if it is determined that the set recovery mode execution time has not elapsed, the determination process of step S170 is repeatedly executed until the recovery mode execution time has elapsed. In this way, the control device 17 applies a desorption potential to the carbon dioxide adsorbent material to desorb the carbon dioxide it has adsorbed during the execution of the recovery mode in which carbon dioxide is recovered. The control device 17 applies the desorption potential only for the duration of the recovery mode execution time corresponding to the target amount of carbon dioxide adsorbed. The recovery mode execution time corresponds to the recovery time.

[0054] In step S180, the recovery mode termination process is executed. Specifically, the control device 17 opens the flow path valve 11 to connect the recovery unit 12 to the outside. The control device 17 stops applying the desorption potential to the electrochemical cell. The control device 17 stops driving the pump 13. The control device 17 switches the flow path switching valve 14 to connect the downstream piping of the pump 13 to the outside. Furthermore, the control device 17 also resets the count value of the counter that counts the recovery mode execution time.

[0055] It is assumed that the carbon dioxide adsorption performance of the electrochemical cell described above will change due to aging and other factors. However, it is not possible to directly detect the upper limit of carbon dioxide that the electrochemical cell can adsorb. Therefore, it cannot be ruled out that the adsorption mode may continue even if the carbon dioxide adsorption capacity of the electrochemical cell has reached its upper limit, or that the recovery mode may continue even if the recovery of carbon dioxide released from the electrochemical cell has substantially ended.

[0056] Thus, in an attempt to maximize the amount of carbon dioxide recovered, for example, if the adsorption mode is always run for a sufficient time to adsorb the upper limit of the amount of carbon dioxide that the electrochemical cell can adsorb, and the recovery mode is run for a sufficient time to recover all the carbon dioxide that the electrochemical cell has adsorbed, then the carbon dioxide recovery system 10 may consume an excessive amount of energy relative to the amount of carbon dioxide recovered.

[0057] Therefore, the carbon dioxide capture system 10 according to this embodiment has a configuration in which the storage device of the control device 17 stores adsorption amount change map data and recovery amount change map data.

[0058] The following provides a detailed explanation of the adsorption amount change map data and the recovery amount change map data. First, we will explain the map creation process for creating the adsorption amount change map data based on the flowcharts in Figures 8 and 9.

[0059] When the control device 17 performs map creation processing, it executes multiple adsorption modes at different execution times (elapsed time) and detects the amount of carbon dioxide recovered in the multiple recovery modes executed in accordance with each adsorption mode via the sensor 15. For example, Figure 3 shows an example in which three adsorption modes are executed at different execution times. Note that the number of times the multiple adsorption modes are executed may be as few as two.

[0060] In Figure 3, the execution time of the first adsorption mode is relatively short, and it is set so that the amount of carbon dioxide adsorbed by the electrochemical cell does not reach its upper limit. Therefore, the amount of carbon dioxide recovered when the recovery mode corresponding to the first adsorption mode is executed is less than the upper limit of the carbon dioxide adsorbed by the electrochemical cell.

[0061] The execution time for the second adsorption mode is relatively long, and it is set so that the amount of carbon dioxide adsorbed by the electrochemical cell reaches approximately its upper limit. Therefore, the amount of carbon dioxide recovered when the recovery mode corresponding to the second adsorption mode is executed is approximately equal to the upper limit of the carbon dioxide adsorption capacity of the electrochemical cell.

[0062] The execution time for the third adsorption mode is the longest, and it is set so that the adsorption mode continues for a certain period even after the carbon dioxide adsorption capacity of the electrochemical cell reaches its upper limit. Therefore, the amount of carbon dioxide recovered when the recovery mode corresponding to the third adsorption mode is executed is equal to the upper limit of the carbon dioxide adsorption capacity of the electrochemical cell.

[0063] Based on the sensor detection results during the execution of the multiple adsorption modes described above, and the multiple recovery modes corresponding to each adsorption mode, the maximum adsorption amount of the electrochemical cell and the maximum adsorption time, which is the execution time of the adsorption mode required to obtain that maximum adsorption amount, are estimated. Specific examples of the method for estimating the maximum adsorption amount and maximum adsorption time of the electrochemical cell are explained with reference to Figures 9(a), (b), and (c).

[0064] In step S200, it is determined whether or not the map creation criteria are met. The control device 17 determines that it is possible to plot the amount of carbon dioxide recovered in the three recovery modes described above for one adsorption amount change map data, and that there is a maximum value of carbon dioxide recovered that is not plotted on the same straight line. Note that tolerances may be included on the same straight line. If the control device 17 determines that the map creation criteria are met, it proceeds to step S210; if it determines that they are not met, it proceeds to step S240.

[0065] In step S240, a retry is performed. The control device 17 executes the adsorption mode again and detects the amount of carbon dioxide recovered in the recovery mode, which is executed in conjunction with the adsorption mode, via the sensor 15. At this time, the control device 17 sets the execution time of the adsorption mode to be longer than the previous time (third time).

[0066] Then, the control device 17 performs S200 using the amount of carbon dioxide recovered in the retry. The control device 17 repeatedly executes steps S200 and S240 until it determines YES in step S200. If the control device 17 executes step S240, in step S220 it adopts the amount of carbon dioxide recovered in the retry as the target amount of carbon dioxide adsorbed.

[0067] In step S210, the slope is calculated. Figure 9(a) is a graph showing the amount of carbon dioxide adsorbed by the electrochemical cell and the execution time of the first adsorption mode, based on the amount of carbon dioxide recovered when the recovery mode corresponding to the first adsorption mode is executed. Note that the amount of carbon dioxide adsorbed by the electrochemical cell can be considered equal to the amount of carbon dioxide recovered. As described above, the execution time of the first adsorption mode is relatively short and set so that the amount of carbon dioxide adsorbed by the electrochemical cell does not reach the upper limit. Therefore, as shown in Figure 9(a), based on the amount of carbon dioxide adsorbed by the electrochemical cell during the execution of the first adsorption mode, the increasing slope line (slope) can be determined by assuming that the amount of carbon dioxide adsorbed increases linearly as the execution time of the adsorption mode increases.

[0068] In step S220, the target carbon dioxide adsorption amount is calculated. Figure 9(b) is a graph showing the carbon dioxide adsorption amount of each electrochemical cell and the execution time of the second and third adsorption modes, based on the amount of carbon dioxide recovered when the recovery modes corresponding to the second and third adsorption modes are executed. As described above, the execution time of the second adsorption mode is relatively long, set so that the carbon dioxide adsorption amount of the electrochemical cell reaches almost the upper limit, and the execution time of the third adsorption mode is the longest, set so that the adsorption mode is executed for a certain period of time even after the carbon dioxide adsorption amount of the electrochemical cell has reached the upper limit. Therefore, as shown in Figure 9(b), an upper limit line for the carbon dioxide adsorption amount of the electrochemical cell can be determined based on the carbon dioxide adsorption amount of the electrochemical cell due to the execution of the second and third adsorption modes. The carbon dioxide adsorption amount corresponding to the upper limit line becomes the target carbon dioxide adsorption amount, which is the maximum adsorption amount that can be adsorbed.

[0069] Furthermore, the upper limit of the carbon dioxide adsorption capacity of the electrochemical cell may be determined based on the amount of carbon dioxide adsorbed by the electrochemical cell obtained through the execution of one adsorption mode and the corresponding recovery mode.

[0070] In step S230, as shown in Figure 9(c), the adsorption time, which is the maximum adsorption time and is the adsorption mode execution time required to obtain the maximum adsorption amount, can be determined from the intersection of the increasing gradient line in Figure 9(a) and the upper limit line in Figure 9(b).

[0071] In this way, the control device 17 estimates the maximum adsorption amount of the electrochemical cell as the target carbon dioxide adsorption amount based on the carbon dioxide recovery amount detected in multiple recovery modes, and also estimates the adsorption time required to obtain the maximum adsorption amount, thereby creating adsorption amount change data. The control device 17 then stores the created adsorption amount change map data in a storage device. The adsorption amount change map data is updated with the target carbon dioxide adsorption amount and adsorption time due to factors such as the aging of the electrochemical cell.

[0072] Next, the process for setting the target carbon dioxide adsorption amount in the recovery amount change map data will be explained based on the flowchart in Figure 10. The control device 17 determines whether to maintain or update the target carbon dioxide adsorption amount at its current value by executing the flowchart in Figure 10.

[0073] As shown in Figures 6 and 7, the recovery amount change map data is associated with different target carbon dioxide adsorption amounts for each cycle number of multiple control sequences. Here, we use an example where the target carbon dioxide adsorption amount is updated every 10 cycles. In addition, the recovery amount change map data is associated with the carbon dioxide recovery amount (carbon dioxide monitor value) detected via sensor 15 and the target carbon dioxide adsorption amount.

[0074] The initial calculated threshold is the initial target carbon dioxide adsorption amount adopted from the first pulse to the tenth cycle. The updated threshold is the updated target carbon dioxide adsorption amount. The updated threshold is the target carbon dioxide adsorption amount assumed due to aging degradation of the electrochemical cell, etc. Therefore, the updated threshold is a smaller value than the initial calculated threshold. Furthermore, the updated threshold decreases as the number of cycles increases.

[0075] Furthermore, the area between the initial calculated threshold and the updated threshold, and between the updated threshold and the next updated threshold, constitutes the adsorption amount retention region. The adsorption amount retention region is the area that maintains the current target carbon dioxide adsorption amount. On the other hand, the area outside the adsorption amount retention region is the adsorption amount update region. The adsorption amount update region is the area where the target carbon dioxide adsorption amount is updated from the current value.

[0076] In step S300, it is determined whether the recovered amount is within the adsorption amount retention range. The control device 17 determines whether the carbon dioxide monitor value as the recovered amount is within the adsorption amount retention range. If the control device 17 determines that the carbon dioxide monitor value is within the adsorption amount retention range, it proceeds to step S310; if it determines that it is not within the adsorption amount retention range, it proceeds to step S320.

[0077] In step S310, the target carbon dioxide adsorption amount is maintained. The control device 17 maintains the current target carbon dioxide adsorption amount. The control device 17 maintains the current target carbon dioxide adsorption amount when the carbon dioxide monitor value is as shown by the dot hatching in Figure 7.

[0078] In step S320, the target carbon dioxide adsorption amount is updated. The control device 17 updates the current target carbon dioxide adsorption amount to the new target carbon dioxide adsorption amount. The control device 17 updates the target carbon dioxide adsorption amount when the carbon dioxide monitor value is as shown by the hatched area in Figure 7.

[0079] In step S330, the target carbon dioxide adsorption amount is set. The control device 17 sets the current target carbon dioxide adsorption amount or the updated target carbon dioxide adsorption amount as the target carbon dioxide adsorption amount when setting the adsorption mode execution time. In this way, the control device 17 sets the target carbon dioxide adsorption amount from the carbon dioxide recovery amount.

[0080] As described above, the carbon dioxide capture system 10 is equipped with a control device 17 that detects the amount of carbon dioxide recovered from the capture device 12 to the CO2 recovery tank 16 via a sensor 15. The control device 17 then acquires a correlation value that correlates with the amount of carbon dioxide recovered, which is the result of detection via the sensor 15, as the target carbon dioxide adsorption amount. Therefore, the carbon dioxide capture system 10 is able to determine the target carbon dioxide adsorption amount.

[0081] Furthermore, the control device 17 executes multiple adsorption modes and determines the target carbon dioxide adsorption amount using adsorption amount change map data created from the carbon dioxide recovery amount detected via the sensor 15 during the multiple recovery modes executed in accordance with each adsorption mode. The control device 17 then applies the adsorption potential only during the duration of the adsorption mode execution obtained from the adsorption amount change map data. Therefore, the control device 17 can apply the adsorption potential only for the time necessary to obtain the maximum adsorption amount. In other words, the control device 17 can suppress the application of the adsorption potential for a longer time than necessary to obtain the maximum adsorption amount. Thus, the control device 17 can appropriately control the application time of the adsorption potential to obtain the maximum adsorption amount.

[0082] Furthermore, the control device 17 updates the adsorption amount change map data according to the amount of carbon dioxide recovered detected via the sensor 15. Therefore, even if the electrochemical cell deteriorates over time, the optimal target amount of carbon dioxide adsorption can be determined, and the application time of the adsorption potential can be appropriately controlled.

[0083] Incidentally, the renewable energy system 31 is a system that generates electricity using solar, wind, geothermal, and hydroelectric power. Therefore, the renewable energy system 31's power surplus fluctuates depending on weather conditions. Furthermore, since the renewable energy system 31 also supplies electricity to systems other than the carbon dioxide capture system 10, its power surplus fluctuates depending on the status of those other systems. In other words, the renewable energy system 31's power surplus that can be supplied to the carbon dioxide capture system 10 fluctuates due to the influence of external factors.

[0084] Therefore, the carbon dioxide capture system 10 performs processing in conjunction with the renewable energy system 31. Figure 11 is a flowchart showing the renewable energy linkage determination process performed by the control device 17 in conjunction with the renewable energy system 31. The control device 17 performs the renewable energy linkage determination process for each cycle of the control sequence. For example, the control device 17 performs the renewable energy linkage determination process for each cycle before starting the adsorption mode. Note that in the diagram, the renewable energy system 31 is abbreviated as "renewable energy".

[0085] However, when the control device 17 receives information indicating the power status from the renewable energy system 31, it starts the process shown in the flowchart of Figure 11. In this case, the control device 17 may start from step S410. The information indicating the power status can also be called power information. Furthermore, when the control device 17 receives power information from the renewable energy system indicating that there is little power surplus, it may perform renewable energy linkage determination processing. In this case, the control device 17 may start from step S430.

[0086] In addition, a low power surplus means that the renewable energy system 31 has insufficient power to supply the carbon dioxide capture system 10. Power surplus refers to, for example, the current power supplyable by the renewable energy system 31 or the power supplyable by the carbon dioxide capture system 10. A situation where this supplyable power falls below a predetermined power threshold can be described as a low power surplus. Furthermore, a low power surplus can also be described as a situation where there is no power available to supply the carbon dioxide capture system 10 (no power surplus).

[0087] In step S400, information indicating the power status is obtained from the renewable energy system 31 (acquisition step). The control device 17 obtains power information in order to determine whether or not the renewable energy system 31 has surplus power. The control device 17 obtains power information, for example, by sending a transmission request to the renewable energy system 31.

[0088] In step S410, it is determined whether or not there is a power surplus (power determination step). Based on the power information acquired in step S400, the control device 17 determines whether or not there is a power surplus in the renewable energy system 31. If the control device 17 determines that there is a power surplus, it proceeds to step S420; if it determines that there is no power surplus, it proceeds to step S430. For example, the control device 17 determines that there is a power surplus if the power indicated by the power information exceeds the power threshold, and determines that there is no power surplus if it does not exceed the power threshold.

[0089] In step S420, the current operation is maintained. The control device 17 terminates the renewable energy interlock determination process without outputting a control signal to the power switching circuit 20 to instruct it to switch the power supply system. Furthermore, the control device 17 terminates the renewable energy interlock determination process without performing any checks on the degradation of the electrochemical cell or transitioning to eco mode.

[0090] In step S430, it is determined whether or not there is little cell degradation (degradation determination step). The control device 17 determines the state of cell degradation of the electrochemical cell. In other words, the control device 17 determines the carbon dioxide recovery performance of the electrochemical cell. Cell degradation of the electrochemical cell can be determined based on, for example, the amount of carbon dioxide recovered detected via the sensor 15. If the control device 17 determines that there is little cell degradation, it proceeds to step S440; otherwise, it proceeds to step S450.

[0091] For example, if the carbon dioxide recovery performance of a new electrochemical cell is considered to be 100%, the control device 17 will determine that the cell degradation is minimal if the carbon dioxide recovery performance is 80% or higher. On the other hand, if the carbon dioxide recovery performance is lower than 80%, it will not determine that the cell degradation is minimal. Note that the threshold for determining whether or not the cell degradation is minimal is not limited to 80%. Furthermore, minimal cell degradation means that the cell can achieve carbon dioxide recovery performance at a level comparable to that of a new cell.

[0092] In step S440, the power system is switched (low-power operation step). The control device 17 switches the power source from the carbon dioxide capture system 10 to the household power supply 32. In other words, if the control device 17 determines that there is no surplus power, it controls the power switching circuit 20 to switch the power source from the renewable energy system 31 to the household power supply 32, thereby reducing the power consumption of the renewable energy system 31.

[0093] Thus, if the control device 17 determines in step S410 that there is no power surplus, it performs power application control and drive control while reducing the power consumption of the renewable energy system 31 compared to when it does not determine that there is no power surplus. In other words, the control device 17 executes a series of control sequences while reducing the power consumption of the renewable energy system 31 by switching the power source from the carbon dioxide capture system 10 to the household power supply 32. As a result, the carbon dioxide capture system 10 executes a series of control sequences while reducing the power consumption of the renewable energy system 31 simply by controlling the power switching circuit 20.

[0094] Furthermore, in this embodiment, as an example, a switch is made from the renewable energy system 31 to the household power supply 32 when it is determined that there is no power surplus and that cell degradation is minimal. In other words, the control device 17 switches to the household power supply 32 to prioritize carbon dioxide capture because, although there is no power surplus, cell degradation is minimal. As a result, the carbon dioxide capture system 10 can switch the power source and continue the control sequence only when cell degradation is minimal.

[0095] In step S450, it is determined whether or not there is significant cell degradation (degradation determination step). The control device 17 determines the state of cell degradation of the electrochemical cell based on the amount of carbon dioxide recovered, etc. If the control device 17 determines that there is significant cell degradation, it proceeds to step S460; otherwise, it proceeds to step S470.

[0096] For example, assuming a carbon dioxide recovery performance of 100% in a new electrochemical cell, the control device 17 determines that the cell is significantly degraded if the carbon dioxide recovery performance is 50% or less. On the other hand, if the carbon dioxide recovery performance exceeds 50%, it does not determine that the cell is significantly degraded. In other words, the control device 17 determines that the electrochemical cell is usable if the carbon dioxide recovery performance is lower than 80% but higher than 50%. Note that the threshold for determining whether the cell is significantly degraded is not limited to 50%. Furthermore, significant cell degradation is considered to be a condition where it is time to replace the electrochemical cell.

[0097] In step S460, the system is stopped (stop step). The control device 17 stops the power application control and drive control if it determines that there is no power surplus and that there is a lot of cell degradation. In other words, the control device 17 stops the series of control sequences without switching the power supply source. This prevents the carbon dioxide capture system 10 from continuing the control sequence when there is no power surplus in the renewable energy system 31 and there is a lot of cell degradation.

[0098] In step S470, the system switches to eco mode. The control device 17 switches to eco mode and executes a series of control sequences. Eco mode is an operating mode that reduces power consumption due to at least one of the power application control and drive control. Eco mode corresponds to a low power consumption mode.

[0099] Thus, if the control device 17 determines in step S410 that there is no power surplus, it performs power application control and drive control while reducing the power consumption of the renewable energy system 31 compared to when it does not determine that there is no power surplus. In other words, by switching to eco mode, the control device 17 executes a series of control sequences while reducing the power consumption of the renewable energy system 31. As a result, the carbon dioxide capture system 10 executes a series of control sequences while reducing the power consumption of the renewable energy system 31, even when there is no power supply source other than the renewable energy system 31.

[0100] Furthermore, in this embodiment, as an example, the system switches to eco mode when it is determined that there is no power surplus and that there is no significant cell degradation. In other words, the control device 17 executes a series of control sequences while imposing various restrictions to suppress energy consumption, because there is no power surplus but there is no significant cell degradation. As a result, the carbon dioxide capture system 10 can switch to eco mode and continue the control sequence only when it is determined that the electrochemical cells are usable despite cell degradation.

[0101] Eco-modes include restricting the conditions for executing the control sequence, reducing the number of recovery units 12 in operation, and switching the controlled equipment or control sequence. In the case of an eco-mode that restricts the conditions for executing the control sequence, for example, the control sequence is executed only during times of low humidity or at night when there is a surplus of power. In the case of reducing the number of recovery units 12 in operation, only recovery units 12 with minimal cell degradation are operated. In the case of an eco-mode that switches the controlled equipment, the blower 19 is stopped from being used and the control sequence is executed.

[0102] Furthermore, in eco mode, which switches the control sequence, the balance between carbon dioxide recovery amount and recovered energy is switched, and the desorption time is extended to minimize the operation of the energy-intensive pump 13, and the control sequence is executed. The balance between carbon dioxide recovery amount and recovered energy is switched from carbon dioxide recovery amount > recovered energy to carbon dioxide recovery amount < recovered energy. This point will be explained using Figure 12. When the control device 17 switches to eco mode, it executes the flowchart in Figure 12 instead of the flowchart in Figure 2. As shown in Figure 12, the control device 17 lowers the target rate of carbon dioxide adsorption amount in step S90 before step S100. Also, the control device 17 lowers the target rate of desorption and recovery in step S155 before step S160. The target rate of carbon dioxide adsorption amount is the ratio to the upper limit of the amount of carbon dioxide that can be adsorbed. Lowering the target rate of carbon dioxide adsorption amount shortens the execution time of the adsorption mode. The target rate of desorption and recovery is the ratio to the upper limit of the amount of carbon dioxide adsorbed on the electrochemical cell. By lowering the target rate of detachment and recovery, the recovery mode execution time is shortened.

[0103] Furthermore, when the flowchart in Figure 12 is started, the control device 17 may first determine whether or not it has switched to eco mode. In this case, if the control device 17 determines that it has switched to eco mode, it proceeds to step S90; otherwise, it proceeds to step S100. Similarly, when step S150 is completed, the control device 17 may determine whether or not it has switched to eco mode. In this case, if the control device 17 determines that it has switched to eco mode, it proceeds to step S155; otherwise, it proceeds to step S160.

[0104] This disclosure can also be adopted by a control device 17 that performs at least one of step S440 and step S470 as a low-power operation. If the control device 17 performs only step S440, it executes step S440 if the NO determination is made in step S410. In this case, steps S430 and steps S450 onward can be omitted. On the other hand, if the control device 17 performs only step S470, it executes step S470 if the NO determination is made in step S410. In this case, steps S430 to S460 can be omitted. Furthermore, the control device 17 may perform steps S450 and S460 while performing at least one of step S440 and step S470 as a low-power operation.

[0105] In this way, the carbon dioxide capture system 10 controls power application and drive while suppressing the power consumption of the renewable energy system 31. Therefore, the carbon dioxide capture system 10 can capture carbon dioxide even if the power supply from the renewable energy system 31 is unstable due to external factors. In other words, the carbon dioxide capture system 10 can capture carbon dioxide while avoiding the effects of external factors.

[0106] While preferred embodiments of the Disclosure have been described above, the Disclosure is not limited to the above embodiments and can be implemented in various modifications without departing from the spirit of the Disclosure. The Disclosure also includes various modifications and variations within the scope of equivalents. In addition, while various combinations and forms are shown in the Disclosure, other combinations and forms that include only one, more, or fewer of these elements also fall within the scope and idea of ​​the Disclosure.

[0107] This specification discloses several technical ideas described in the following sections, and also discloses several combined technical ideas, shown by the alternative reference of preceding technical ideas in subsequent technical ideas.

[0108] Technical thought 1 A carbon dioxide capture system that operates by receiving power from a renewable energy system (31) and recovers carbon dioxide from a mixed gas containing carbon dioxide through an electrochemical reaction, A carbon dioxide capture tank (16) for storing the captured carbon dioxide, An electrochemical cell having a working electrode containing an adsorbent material capable of adsorbing carbon dioxide, and a counter electrode paired with the working electrode, and a housing for housing the electrochemical cell, wherein the mixed gas is supplied to the inside of the housing, When the adsorbent desorbs the carbon dioxide it has adsorbed, a pump (13) sucks the carbon dioxide desorbed from the adsorbent from the recovery device and discharges it toward the carbon dioxide recovery tank. The system includes a control device (17) that controls the application of power, such as applying a first potential between the working electrode and the counter electrode so that the electrochemical cell adsorbs carbon dioxide, or applying a second potential between the working electrode and the counter electrode so that the electrochemical cell desorbs the adsorbed carbon dioxide, and also controls the drive of the pump so that the pump sucks in and discharges carbon dioxide at least when the electrochemical cell desorbs carbon dioxide. The control device is The acquisition step (S400) involves acquiring power information indicating the power status of the renewable energy system, A power determination step (S410) is performed to determine the power surplus of the renewable energy system based on the aforementioned power information, A carbon dioxide capture system comprising: low-power operation steps (S440, S470) that, if the power surplus is determined to be low in the power determination step, perform power application control and drive control while reducing the power consumption of the renewable energy system compared to when the power surplus is not determined to be low.

[0109] Technical thought 2 It is configured to operate by receiving power from either the aforementioned renewable energy system or a power supply system (32) different from the aforementioned renewable energy system. A power switching circuit (20) is connected that can switch the power source between the renewable energy system and the power supply system. In the low-power operation step, if it is determined that there is insufficient power reserve, the power switching circuit is controlled to switch the power source from the renewable energy system to the power supply system, thereby reducing the power consumption of the renewable energy system, as described in Technical Concept 1, for the carbon dioxide capture system.

[0110] Technical thought 3 The carbon dioxide capture system according to technical concept 1 or 2, wherein in the low-power operation step, if it is determined that there is little power surplus, a low-power mode is executed that reduces power consumption by at least one of the power application control and the drive control compared to when it is determined that there is power surplus, thereby reducing the power consumption of the renewable energy system.

[0111] Technical thought 4 The control device is The electrochemical cell includes a degradation determination step (S430) for determining the state of cell degradation, The carbon dioxide capture system according to technical concept 2, wherein in the low-power operation step, if it is determined that there is little power surplus and that there is little cell degradation, the system switches from the renewable energy system to the power supply system.

[0112] Technical thought 5 The control device is The system includes a degradation determination step (S450) for determining the state of cell degradation in the electrochemical cell, The carbon dioxide capture system according to technical concept 3, wherein the low-power operation step is performed when it is determined that there is little power reserve and when it is not determined that there is a lot of cell degradation.

[0113] technical thought 6 The control device is A degradation determination step (S450) for determining the state of cell degradation in the electrochemical cell, A carbon dioxide capture system according to any one of technical ideas 1 to 5, comprising a stop step (S460) for stopping the power application control and the drive control when it is determined that the power surplus is low and the cell degradation is high. [Explanation of symbols]

[0114] 10: Carbon dioxide capture system, 11: Flow control valve, 12: Capturer, 13: Pump, 14: Flow switching valve, 15: Sensor, 16: CO2 capture tank, 17: Control device, 19: Blower, 20: Power switching circuit, 31: Renewable energy system, 32: Household power supply

Claims

1. A carbon dioxide capture system that operates by receiving power from a renewable energy system (31) and recovers carbon dioxide from a mixed gas containing carbon dioxide through an electrochemical reaction, A carbon dioxide capture tank (16) for storing the captured carbon dioxide, An electrochemical cell having a working electrode containing an adsorbent material capable of adsorbing carbon dioxide, and a counter electrode paired with the working electrode, and a housing for housing the electrochemical cell, wherein the mixed gas is supplied to the inside of the housing, at least one recovery unit (12), When the adsorbent desorbs the carbon dioxide it has adsorbed, a pump (13) sucks the carbon dioxide desorbed from the adsorbent from the recovery device and discharges it toward the carbon dioxide recovery tank. The system includes a control device (17) that controls the application of power, such as applying a first potential between the working electrode and the counter electrode so that the electrochemical cell adsorbs carbon dioxide, or applying a second potential between the working electrode and the counter electrode so that the electrochemical cell desorbs the adsorbed carbon dioxide, and also controls the drive of the pump so that the pump sucks in and discharges carbon dioxide at least when the electrochemical cell desorbs carbon dioxide. The control device is The acquisition step (S400) involves acquiring power information that indicates the power status of the renewable energy system, A power determination step (S410) is performed to determine the power surplus of the renewable energy system based on the power information, A carbon dioxide capture system comprising: low-power operation steps (S440, S470) that, if the power determination step determines that the power surplus is low, perform the power application control and the drive control while reducing the power consumption of the renewable energy system compared to when the power surplus is not determined to be low.

2. It is configured to operate by receiving power from either the aforementioned renewable energy system or a power supply system (32) different from the aforementioned renewable energy system. A power switching circuit (20) is connected that can switch the power source between the renewable energy system and the power supply system. The carbon dioxide capture system according to claim 1, wherein in the low-power operation step, if it is determined that there is little power surplus, the power switching circuit is controlled to switch the power source from the renewable energy system to the power supply system, thereby reducing the power consumption of the renewable energy system.

3. The carbon dioxide capture system according to claim 1, wherein in the low-power operation step, if it is determined that there is little power surplus, a low-power mode is executed that reduces the power consumption of at least one of the power application control and the drive control compared to when it is determined that there is power surplus, thereby reducing the power consumption of the renewable energy system.

4. The control device is The system includes a degradation determination step (S430) for determining the state of cell degradation in the electrochemical cell, The carbon dioxide capture system according to claim 2, wherein in the low-power operation step, if it is determined that there is little power reserve and that there is little cell degradation, the system switches from the renewable energy system to the power supply system.

5. The control device is The system includes a degradation determination step (S450) for determining the state of cell degradation in the electrochemical cell, The carbon dioxide recovery system according to claim 3, wherein the low-power operation step is performed when it is determined that there is little power reserve and when it is not determined that there is a lot of cell degradation.

6. The control device is A deterioration determination step (S450) for determining the state of cell deterioration in the electrochemical cell, The carbon dioxide recovery system according to claim 1, further comprising a stop step (S460) for stopping the power application control and the drive control when it is determined that the power surplus is low and that the cell degradation is high.

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