Carbon dioxide storage system

Abstract

We provide a carbon dioxide storage system utilizing wind turbine equipment. [Solution] A carbon dioxide storage system comprising a cylindrical tower, a wind turbine device positioned on the tower, a carbon dioxide separation and recovery device driven by the rotational shaft power obtained from the wind turbine device to separate and recover carbon dioxide from gas drawn in through an opening in the tower, a carbon dioxide gas compressor driven by the rotational shaft power obtained from the wind turbine device to compress the carbon dioxide gas separated and recovered by the carbon dioxide separation and recovery device, an injection pump driven by the rotational shaft power obtained from the wind turbine device to pump the compressed carbon dioxide into an underground carbon dioxide storage tank, and an injection well for injecting and storing the carbon dioxide separated and recovered from the gas into the underground carbon dioxide storage tank, wherein the carbon dioxide separation and recovery device, the carbon dioxide gas compressor, and the injection pump are located inside the cylinder of the tower.

Description

Technical Field

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[0001] The present invention relates to a carbon dioxide storage system.

Background Art

[0002] In Patent Document 1, a wind power generation unit, a air compressor unit, an air expander unit and an electric generator provided in a wind power generation engine room, and a composite air storage device provided outside the wind power generation engine room are provided. The electric generator includes a first input shaft and a first output shaft. The first input shaft is connected to the wind power generation unit via a first switch, the first output shaft is connected to the air compressor unit, the composite air storage device includes a first air storage device provided in a tower-shaped cylinder and a second air storage device provided underground, the internal cavities of the first air storage device and the second air storage device communicate with each other, the input end of the composite air storage device is connected to the air compressor unit, and the output end of the composite air storage device is connected to the air expander unit. An onshore wind power generation unit with a compressed air storage system is disclosed.

[0003] Further, in Patent Document 2, a wind turbine comprising at least two separate units assembled to form a nacelle coupled to a wind turbine tower is disclosed. The two separate units include a first unit incorporating a rotor support assembly and a second unit incorporating an electrolytic cell stack powered by a generator.

Prior Art Documents

Patent Documents

[0005] Oil and gas fields that have finished extracting oil and natural gas have voids left in the underground geological formations. In these voids, carbon capture and storage (CCS) is sometimes performed, where carbon dioxide gas separated and recovered from power plants is pressurized and injected into the ground for storage. Alternatively, enhanced recovery (EOR) and exhaust gas recirculation (EGR) are performed, where carbon dioxide is injected to push out the remaining oil and natural gas in the voids. However, separating and recovering carbon dioxide at the source of injection consumes a large amount of electricity and heat. Furthermore, because of the distance to the oil and gas fields where the carbon dioxide is stored, the process of transporting high-pressure carbon dioxide gas via long-distance pipelines or transporting the compressed and liquefied carbon dioxide to the storage sites by vehicles or ships incurs significant costs and energy consumption. Moreover, if fossil fuel-derived energy is consumed during the separation, recovery, and transportation of carbon dioxide, the carbon dioxide emitted during these processes reduces the reduction effect of storing carbon dioxide in oil and gas fields.

[0006] Furthermore, while it is possible to obtain renewable energy without carbon dioxide emissions by developing wind power generation facilities on land or offshore where wind conditions are favorable, the locations of onland and offshore power generation facilities are often far from the power consumption areas. This necessitates the development of long-distance transmission networks to transmit the generated electricity to the consumption areas, which requires significant costs and time for network development. Moreover, in areas where the transmission distance is too long, it becomes impossible to develop wind power generation facilities and utilize the power even if wind conditions are favorable.

[0007] On the other hand, while suitable locations for onshore and offshore wind power generation with favorable wind conditions, and depleted onshore and offshore oil and gas fields suitable for carbon dioxide storage are both far from areas where electricity and fuel are consumed, their proximity makes it possible to efficiently separate and capture carbon dioxide using untapped wind energy and store it in depleted oil and gas fields. However, the specific methods and equipment for this have not been disclosed. For example, areas where offshore oil and natural gas are extracted and transported using offshore platforms have favorable wind conditions and are suitable for wind power generation, but the construction of a power grid is difficult, so wind energy is not utilized. Furthermore, there is a problem in that offshore oil and gas fields after extraction are not being effectively utilized as carbon dioxide storage sites. The present invention aims to efficiently separate, recover, and store carbon dioxide underground in locations where suitable wind energy utilization sites and suitable carbon dioxide storage sites are close together, without requiring the development of a power transmission network or the long-distance transport of carbon dioxide, by utilizing wind energy that does not emit carbon dioxide. [Means for solving the problem]

[0008] The carbon dioxide storage system to which the present invention applies comprises a cylindrical tower, a wind turbine device arranged in the tower, a carbon dioxide separation and recovery device that separates and recovers carbon dioxide from a gas drawn in through an opening in the tower by the supply of rotating shaft power obtained from the wind turbine device or generated electricity obtained from a generator connected to the wind turbine device, a carbon dioxide gas compressor that is driven by the supply of rotating shaft power obtained from the wind turbine device or generated electricity obtained from a generator connected to the wind turbine device and compresses the carbon dioxide gas separated and recovered by the carbon dioxide separation and recovery device, an injection pump that is driven by the supply of rotating shaft power obtained from the wind turbine device or generated electricity obtained from a generator connected to the wind turbine device and pumps the carbon dioxide compressed by the compressor into an underground carbon dioxide storage tank, and an injection well that pressurizes and stores the carbon dioxide separated and recovered from the gas into the underground carbon dioxide storage tank, wherein the carbon dioxide separation and recovery device, the carbon dioxide gas compressor, and the injection pump are located inside the cylinder of the tower.

[0009] Here, the gas supplied through the air intake, which is an opening at the top of the tower, may be air that can be drawn in from around the tower, biogas obtained from a methane fermentation tank installed close to the tower, combustion exhaust gas obtained when biomethane obtained after separating carbon dioxide from the biogas is burned, or combustion exhaust gas generated when fossil fuels are burned.

[0010] Furthermore, as a method for separating and recovering carbon dioxide from the supply air, one may use shaft power obtained by the rotational driving force of a wind turbine or generated electricity to drive a compressor to compress the supply air and supply the high-pressure supply air gas to a carbon dioxide separation membrane for separation, or a separation membrane method in which a suction pump for separating and sucking carbon dioxide gas is installed in the carbon dioxide gas flow path downstream of the carbon dioxide separation membrane, and this suction pump is operated using shaft power obtained by the rotational driving force of a wind turbine or generated electricity for separation and sucking. Alternatively, a pressure vessel containing a carbon dioxide adsorbent may be installed in the tower, and high-pressure supply air gas, which has been pressurized via a compressor, is supplied to the pressure vessel to adsorb carbon dioxide in the supply gas onto the adsorbent, and then the pressure vessel is depressurized via a suction pump to desorb and recover the carbon dioxide by adsorption. Furthermore, as a method for separating and recovering carbon dioxide from the supply air, a separation and recovery tower using a carbon dioxide absorbent liquid may be provided within the tower. The gas supplied to the separation and recovery tower is supplied through an air inlet, which is an opening at the top of the tower. The air supply and absorption liquid circulation are performed by an air blower and an absorption liquid circulation pump, which are driven by the rotating shaft power obtained from the wind turbine device or the power generated from a generator connected to the wind turbine device. At the same time, the absorption liquid that has absorbed carbon dioxide is heated and regenerated using the power generated from the generator connected to the wind turbine device, and the absorption liquid is circulated and pumped in this manner, thereby separating and recovering carbon dioxide from the supply air.

[0011] Furthermore, the carbon dioxide gas separated and recovered by the above method is compressed into the ground through an injection well, which is used to inject the carbon dioxide gas separated and recovered from the gas into an underground carbon dioxide storage tank located directly below or near the tower installation site. This is done by using a carbon dioxide gas compressor, which is powered by the rotating shaft power obtained from the wind turbine device or the power generated by a generator connected to the wind turbine device, to compress the carbon dioxide gas separated and recovered by the carbon dioxide gas separation and recovery device, and an injection pump, which is powered by the rotating shaft power obtained from the wind turbine device or the power generated by a generator connected to the wind turbine device, to pump the compressed carbon dioxide into an underground carbon dioxide storage tank.

[0012] Here, the gas, from which carbon dioxide has been separated by the carbon dioxide separation and recovery device and whose carbon dioxide concentration has decreased, can be configured to be exhausted through an exhaust port, which is an opening in the tower located below the position of the air intake port. [Effects of the Invention]

[0013] According to the present invention, in locations where suitable wind energy utilization sites are close to suitable carbon dioxide storage sites, where the development of a power transmission network is difficult, it becomes possible to efficiently separate, recover, and store carbon dioxide underground without developing a power transmission network or requiring long-distance transportation of carbon dioxide, by utilizing unused wind energy that does not emit carbon dioxide. [Brief explanation of the drawing]

[0014] [Figure 1] This is a diagram showing the overall carbon dioxide storage system according to the first embodiment. [Figure 2] This is a schematic diagram showing an example of the configuration inside a wind turbine tower according to the first embodiment. [Figure 3] This figure shows an example of the configuration of a separation unit using a carbon dioxide separation membrane. [Figure 4]It is a schematic diagram showing an example of a wind power drive unit and an in-tower configuration according to Modification 1 of the first embodiment. [Figure 5] It is a diagram showing an example of the configuration of a separation unit using a carbon dioxide adsorbent. [Figure 6] It is a diagram showing an example of the configuration of a separation unit using a carbon dioxide absorption liquid. [Figure 7] It is a diagram showing the whole carbon dioxide storage system according to the second embodiment. [Figure 8] It is a schematic diagram showing an example of a wind power drive unit and an in-tower configuration according to the second embodiment.

Mode for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. 〔Overall Configuration of Carbon Dioxide Storage System〕 FIG. 1 is a diagram showing the whole carbon dioxide storage system 1 according to the first embodiment. The carbon dioxide storage system 1 takes in ambient air, separates and recovers carbon dioxide in the atmosphere, and injects and stores carbon dioxide underground. The carbon dioxide storage system 1 includes an offshore platform 100 installed on the seabed at the mining site of a depleted oil field or depleted gas field on the seabed, a tower 90, a wind power drive unit 10, and a carbon dioxide injection pipe 8. Hereinafter, the direction in which the tower 90 extends may be referred to as the vertical direction, the side where the wind power drive unit 10 is provided may be referred to as the upper side, and the side of the offshore platform 100 may be referred to as the lower side. The offshore platform 100 includes a plurality of legs 110 fixed to the seabed and extending to the sea surface, and a deck 120 fixed to the ends of the plurality of legs 110 on the sea surface. In the present embodiment, the offshore platform 100 uses an offshore platform on a seabed oil field where oil has been depleted and is no longer used in a sea area favored by a wind condition where it is difficult to maintain power transmission lines. The tower 90 is provided on the deck 120 of the offshore platform 100 from which a drilling rig for excavating oil has been removed.

[0016] The carbon dioxide injection pipe 8 can reuse, for example, the pipes for oil extraction provided in oil wells that were used to pump oil. The carbon dioxide injection pipe 8 extends from a later-described injection pump 51 in the tower 90 and reaches an air void layer after oil extraction that is deeper than the rock formation or strata that do not allow carbon dioxide to pass through, that is, a subsurface injection storage tank for carbon dioxide.

[0017] FIG. 2 is a diagram showing an example of the configuration of the wind power drive unit 10 according to the first embodiment and the inside of the tower 90. The tower 90 includes a gas compression unit 20, a separation unit 30, a liquefaction unit 40, and an injection unit 50. The tower 90 has a cylindrical shape with a hollow interior. The tower 90 includes a cylindrical side surface 91. The side surface 91 includes a gas intake port 911 for taking in air in the atmosphere and a gas discharge port 912 for discharging air with a reduced carbon dioxide concentration. The gas intake port 911 is arranged above the gas discharge port 912. The gas intake port 911 is an example of an air supply port. The dimensions of the tower 90 are not particularly limited, but for example, the height in the vertical direction can be exemplified as 100 to 200 m, and the diameter of the cross-section in the direction perpendicular to the vertical direction can be exemplified as 5 to 10 m.

[0018] In the present embodiment, the wind power drive unit 10 is provided above the tower 90, and then the gas compression unit 20, the separation unit 30, the liquefaction unit 40, and the injection unit 50 are arranged side by side in the vertical direction from the upper side in this order. The gas compression unit 20 and the separation unit 30 are connected via a pipe 93, and the separation unit 30 and the liquefaction unit 40 are connected via a pipe 93. Also, the liquefaction unit 40 and the injection pump 51 (described later) of the injection unit 50 are connected via a pipe 93.

[0019] Also, in the present embodiment, the wind power drive unit 10 includes a wind power nacelle unit 12 incorporating an orthogonal gear transmission 16 that converts the horizontal axis rotational power obtained by the rotating unit 11, which obtains rotational power by wind power, into vertical axis rotational power for driving a gas compressor or an injection pump arranged in the tower 90. The rotating unit 11 includes a rotor shaft 13 that serves as a rotating shaft, a hub 14 fixed to one end of the rotor shaft 13, and a plurality of blades 15 fixed to the hub 14. Multiple blades 15 are attached to a hub 14, and the blades 15 rotate around the hub 14 when they receive wind. The number of blades 15 is not particularly limited, but Figure 1 shows three blades 15.

[0020] The wind turbine nacelle 12 is also equipped with a control device 17 that detects the rotational force of the rotor shaft 13 and stops gas compression and pump operation, or closes a carbon dioxide backflow prevention valve provided on the injection piping, when wind conditions are poor and the rotational force of the rotor shaft 13 is insufficient. When wind conditions improve and sufficient rotational force is obtained for carbon dioxide separation, recovery and injection into the ground, the gas compressor and injection pump are restarted, and the opening of the carbon dioxide backflow prevention valve is controlled to start and stop carbon dioxide separation, recovery and injection, and to control the injection amount according to the wind conditions.

[0021] In the wind power drive unit 10, when the blades 15 receive wind force, the blades 15 rotate around the hub 14. The rotation of the hub 14 causes the rotor shaft 13 to rotate. The orthogonal gear transmission 16 converts the rotational energy of the rotor shaft 13 into vertical rotational force within the tower 90. The rotational driving force, converted vertically by the orthogonal gear transmission 16 and whose rotational speed is controlled by the speed governor, is supplied as rotational driving force to the compressor and pumps that constitute the carbon dioxide storage system 1 via the power transmission shaft 94 that extends vertically.

[0022] Here, the power transmission shaft 94 transmits the rotational power of the rotor shaft 13 to the gas compression unit 20, the separation unit 30, the carbon dioxide compressor 41, and the injection pump 51. However, if the rotational speed of the power transmission shaft 94 differs from the optimal operating rotational speed of each component of the gas compressor, carbon dioxide compressor, and injection pump, a transmission may be provided on the rotating shaft of each component and connected to it so that the rotational driving force of the power transmission shaft can be changed to the optimal rotational speed for each component to operate at the optimal rotational speed. Alternatively, if there is no need to change the speed, the power transmission shaft may be directly connected. In this way, the rotational driving force obtained from the wind power drive unit 10 is transmitted to the rotational driving force of the gas compressor in the gas compression unit 20, the carbon dioxide compressor 41 in the liquefaction unit 40, and the injection pump 51 in the injection unit 50, so that the rotational shaft power obtained from the wind power drive unit is efficiently used directly for gas compression and carbon dioxide injection without going through a generator.

[0023] Furthermore, the control device 17 is connected to a solar power generation facility (not shown) installed on the top surface of the wind turbine nacelle 12. By storing surplus electricity generated by the solar power generation facility using a battery installed inside the wind turbine nacelle 12, the control device 17 is constantly supplied with power. This allows the control device 17 to monitor the operating status of the carbon dioxide storage system 1, including when wind conditions are poor and carbon dioxide separation, recovery, or injection is not possible, by supplying power to sensors that monitor the status of the equipment constituting the carbon dioxide storage system 1.

[0024] The gas compression unit 20 is a compressor that compresses gas. In this embodiment, the gas compression unit 20 compresses air from the atmosphere and supplies the compressed air to the separation unit 30. In this embodiment, the gas compression unit 20 is driven by rotational driving force obtained from the wind drive unit 10 via the orthogonal gear transmission 16. The gas compression unit 20 only needs to be able to compress gas, and the means of compression are not particularly limited. The gas compression unit 20 can be exemplified by a turbo compressor or a positive displacement compressor. Examples of turbo compressors include axial flow compressors and centrifugal compressors. Examples of positive displacement compressors include reciprocating compressors and rotary compressors.

[0025] Furthermore, the separation unit 30 is an example of a carbon dioxide separation and recovery device that separates and recovers carbon dioxide contained in the compressed air supplied from the gas compression unit 20 via a carbon dioxide separation membrane. The separation unit 30 will now be explained with reference to Figure 3. Figure 3 is a diagram showing an example of the configuration of the separation unit 30. The separation unit 30 comprises one or more separation membrane modules 31 and one or more carbon dioxide gas suction pumps 32. The number of separation membrane modules 31 is not particularly limited, but in the illustrated example, the separation unit 30 comprises three separation membrane modules 31a, 31b, and 31c. The separation membrane modules 31a to 31c are arranged in series, with separation membrane module 31a located at the upstream end, separation membrane module 31c located at the downstream end, and separation membrane module 31b located between separation membrane modules 31a and 31c. Each separation membrane module 31 comprises a housing 311, an inlet 312, a separation membrane 313, an upstream outlet 314, and a downstream outlet 315.

[0026] The housing 311 is a roughly cylindrical container. The inlet 312 is an opening for allowing gas to flow into the housing 311. The separation membrane 313 selectively permeates carbon dioxide gas from the high-pressure side to the low-pressure side when there is a gas pressure difference in the region on either side of the membrane 313. The separation membrane 313 is fixed inside the housing 311 and divides the inside of the housing 311 into two regions. Hereinafter, the region on the side where the inlet 312 is located will be referred to as the upstream region, and the other side will be referred to as the downstream region. The upstream outlet 314 and the downstream outlet 315 are openings for discharging gas from inside the housing 311 to the outside of the housing 311. The upstream outlet 314 is located in the upstream region of the housing 311, and the downstream outlet 315 is located in the downstream region of the housing 311. In the illustrated example, it is shown that nitrogen (N2) and oxygen (O2), which remain after carbon dioxide has been separated and recovered from compressed air, are discharged from the upstream outlet 314.

[0027] The carbon dioxide gas suction pump 32 draws in gas from the upstream side and sends it to the downstream side. In the illustrated example, the separation unit 30 is equipped with two carbon dioxide gas suction pumps 32a and 32b. The carbon dioxide gas suction pump 32a is installed between the separation membrane module 31a and the separation membrane module 31b, and depressurizes the downstream region of the separation membrane module 31a and pressurizes the upstream region of the separation membrane module 31b to pump the gas. The carbon dioxide gas suction pump 32b is installed between the separation membrane module 31b and the separation membrane module 31c, and depressurizes the downstream region of the separation membrane module 31b and pressurizes the upstream region of the separation membrane module 31c to pump the gas.

[0028] Here, similar to the gas compression unit 20, the rotational drive shaft of the carbon dioxide gas suction pump 32 also utilizes the rotational drive force obtained from the wind drive unit 10 via the orthogonal gear transmission 16 to be transmitted to the power transmission shaft 94, thereby directly using the wind's rotational drive force as the pump drive force. The method of depressurization and suction of the carbon dioxide gas suction pump 32 is not particularly limited, but a vacuum pump or a depressurization pump is one example. When pressurizing and pumping the gas sucked in by the pump, a gas compressor or blower can be driven.

[0029] As shown in Figure 2, the liquefaction unit 40 comprises a carbon dioxide compressor 41 and a turbo chiller 42. The carbon dioxide compressor 41 is supplied with the carbon dioxide gas separated by the separation unit 30 and pressurizes the supplied carbon dioxide gas. The carbon dioxide compressor 41 only needs to be able to compress gas, and the means of compression are not particularly limited. Similar to the gas compression unit 20, the carbon dioxide compressor 41 can be a turbo compressor or a positive displacement compressor. The turbo chiller 42 has a compressor inside and uses the compressor to compress a refrigerant and execute the refrigeration cycle. The carbon dioxide gas cooled by this turbo chiller 42 is liquefied to become liquefied carbon dioxide. In this example, both the compressors of the carbon dioxide compressor 41 and the turbo chiller 42 are driven by rotational driving force obtained via the power transmission shaft 94 in the tower, so that the rotational driving force of the wind is directly used to compress the separated and recovered carbon dioxide gas and to drive the compressor of the turbo chiller, and is also used for the liquefaction of carbon dioxide.

[0030] Furthermore, when injecting carbon dioxide into the ground, it is desirable to convert the carbon dioxide gas into a supercritical fluid by applying pressure to it to 7.38 MPa or higher. A supercritical fluid is one state of carbon dioxide in which the distinction between gas and liquid disappears, resulting in a smaller volume, lower viscosity, and easier injection. Carbon dioxide becomes a supercritical fluid when the pressure is 7.38 MPa or higher and the temperature is 31.1°C or higher. The supercritical carbon dioxide is pressurized by the injection pump 51 of the injection section 50, which is driven by power via the power transmission shaft 94, and then flowed into the carbon dioxide injection pipe 8. The carbon dioxide flowed into the carbon dioxide injection pipe 8 flows through the check valve 55 to the carbon dioxide storage tank.

[0031] Here, the injection section 50 is equipped with an injection pump 51, a flow control valve 52, and pressure measuring instruments 53 and 54. The injection pump 51 is connected to the carbon dioxide injection piping 8 and adds energy to the carbon dioxide liquefied in the liquefaction section 40 to inject the liquefied carbon dioxide into the geological formation. The injection pump 51 is also connected to the power transmission shaft 94 within the tower 90 and is driven by the rotational driving force obtained from the wind drive unit 10 via the orthogonal gear transmission 16, thereby directly utilizing the rotational driving force of the wind to inject the separated and recovered carbon dioxide gas into the ground. Here, the injection pump 51 could be, for example, a positive displacement pump, but it could also be a non-positive displacement pump. Examples of non-positive displacement pumps include centrifugal pumps and propeller pumps.

[0032] Furthermore, the flow control valve 52 is installed in the middle of the carbon dioxide injection pipe 8 and adjusts the flow rate of liquefied carbon dioxide flowing through the carbon dioxide injection pipe 8. The flow control valve 52 can be exemplified as a solenoid valve. In this case, the flow control valve 52 adjusts the valve opening by controlling the magnitude of the current flowing through the solenoid valve. The flow control valve 52 may also be a backflow prevention valve that allows liquefied carbon dioxide to flow in only one direction to prevent backflow. Pressure gauges 53 and 54 measure the pressure of liquefied carbon dioxide flowing through the carbon dioxide injection pipe 8. Pressure gauge 53 is located upstream of the flow control valve 52, and pressure gauge 54 is located downstream of the flow control valve 52.

[0033] In this embodiment, the press-in pump 51, the flow control valve 52, and the pressure measuring instruments 53 and 54 are connected to a solar power generation facility (not shown) installed on the top surface of the wind turbine nacelle 12, and power is supplied from a battery installed inside the wind turbine nacelle 12. The pressure measuring instruments 53 and 54 may also be powered by a battery installed inside the wind turbine nacelle 12, which is connected to, for example, a solar power generation panel installed on or near the tower surface, or a small wind turbine installed on the top surface of the wind turbine nacelle 12.

[0034] [The process of separating and recovering carbon dioxide] First, atmospheric air is supplied to the gas compression unit 20 from the gas intake port 911 of the tower 90. The gas compression unit 20 compresses the atmospheric air and supplies the compressed air to the separation unit 30. In the separation unit 30, air first flows into the upstream region of the separation membrane module 31a from the inlet port 312 of the separation membrane module 31a. Because the air in the upstream region of the separation membrane module 31a is compressed, the pressure is high, and carbon dioxide selectively flows through the separation membrane 313 to the downstream region of the separation membrane module 31a. The gas remaining in the upstream region of the separation membrane module 31a is discharged to the outside of the housing 311 from the upstream outlet port 314 and to the outside of the tower 90 from the gas outlet port 912.

[0035] The gas flowing into the downstream region of the separation membrane module 31a has a higher concentration of carbon dioxide. The gas in the downstream region of the separation membrane module 31a has a higher concentration of carbon dioxide than the gas in the upstream region. The gas in the downstream region of the separation membrane module 31a is supplied to the separation membrane module 31b by the carbon dioxide gas suction pump 32. A portion of the gas in the upstream region of the separation membrane module 31b flows through the separation membrane 313 to the downstream region of the separation membrane module 31b. The gas remaining in the upstream region of the separation membrane module 31b is discharged to the outside of the housing 311 from the upstream outlet 314 and to the outside of the tower 90 from the gas outlet 912.

[0036] Similarly, the gas flowing into the downstream region of the separation membrane module 31b has a higher concentration of carbon dioxide than the gas in the upstream region. The gas in the downstream region of the separation membrane module 31b is supplied to the separation membrane module 31c by the carbon dioxide gas suction pump 32. A portion of the gas in the upstream region of the separation membrane module 31c passes through the separation membrane 313 and is separated and recovered as high-concentration carbon dioxide gas and flows into the downstream region of the separation membrane module 31c. The gas remaining in the upstream region of the separation membrane module 31c is discharged to the outside of the housing 311 from the upstream outlet 314 and to the outside of the tower 90 from the gas outlet 912.

[0037] High-concentration carbon dioxide gas flowing in the downstream region of the separation membrane module 31c is supplied from the separation section 30 to the liquefaction section 40. The high-concentration carbon dioxide gas supplied to the liquefaction section 40 is pressurized by the carbon dioxide compressor 41 and cooled by the turbo chiller 42, thereby liquefying it. The liquefied carbon dioxide is pressurized by the injection pump 51 in the injection section 50 and flowed into the carbon dioxide injection piping 8. The liquefied carbon dioxide is transported to the seabed sediment after its flow rate is regulated by the flow control valve 52. The flow control valve 52 adjusts the flow rate according to the measurement results of the pressure gauges 53 and 54. For example, if the pressure upstream of the flow control valve 52 is lower than the pressure downstream, the valve is closed to prevent backflow of liquefied carbon dioxide. Alternatively, for example, if the upstream pressure is greater than the downstream pressure, the opening degree may be changed according to the difference between the upstream and downstream pressures.

[0038] In this embodiment, since the carbon dioxide storage system 1 is installed using an offshore platform 100 for drilling for oil and gas, it is possible to reduce or eliminate the transport pipelines for separated and recovered carbon dioxide, and to capture and fix carbon dioxide at the storage site. Furthermore, it is possible to significantly reduce the construction period and equipment / construction costs for building the offshore platform 100. In addition, by effectively utilizing existing depleted oil and gas fields for carbon dioxide storage and fixation, it is possible to eliminate the exploration and drilling development of carbon dioxide storage tanks, and to significantly reduce the construction period and costs of exploration and development of storage tanks.

[0039] Furthermore, in this embodiment, in offshore areas with favorable wind conditions far from power-consuming areas where laying power lines is difficult, the rotational drive shaft power, which does not involve carbon dioxide emissions, is directly utilized without power generation in the processes of carbon dioxide separation and recovery, compression and liquefaction of the recovered carbon dioxide, and injection and storage of the liquefied carbon dioxide in the ground. This makes it possible to efficiently achieve carbon dioxide separation, recovery, and sequestration using renewable energy.

[0040] In this embodiment, the gas intake port 911 is located at the top of the tower 90, and since air is drawn in from above, the intake of salt-containing air near the sea surface is suppressed.

[0041] [Variation 1] Figure 4 is a schematic diagram showing an example of the configuration of the wind power drive unit 10 and the tower 90 according to Modification 1 of the First Embodiment. The carbon dioxide storage system 2 according to Modification 1 of the First Embodiment comprises a wind turbine 18, a gas compression unit 20, a separation unit 130, a liquefaction unit 40, an injection unit 50, and a tower 90. The wind turbine 18, gas compression unit 20, separation unit 130, liquefaction unit 40, and injection unit 50 are housed in the tower 90. In this embodiment, the wind turbine 18 is provided on the upper side of the tower 90, followed by the gas compression unit 20, separation unit 130, liquefaction unit 40, and injection unit 50, which are arranged vertically from the top in that order.

[0042] This system differs from the first embodiment in that the compressors, pumps, and other components used to drive gas compression, carbon dioxide compression, liquefaction, and underground injection of liquefied carbon dioxide are powered by electricity generated by a wind turbine 18 located inside the wind turbine nacelle 12, and the configuration of the separation unit 130 that separates carbon dioxide is different. In other words, the equipment constituting the gas compression unit 20, the separation unit 30, and the liquefaction unit 40 consists of a group of electric motors that are consumed within the tower and driven by the power generated by the wind turbine 18, which is connected to the tower by power supply wiring (not shown). Furthermore, while the first embodiment separated carbon dioxide using a separation membrane module 31, the separation unit 130 of the modified example 1 of the first embodiment separates carbon dioxide by a physical adsorption separation method consisting of a plurality of pressure vessels filled with a carbon dioxide adsorbent. Examples of carbon dioxide adsorbents include zeolite and activated carbon. The same reference numerals are used for functions similar to those in the first embodiment, and their explanation is omitted here.

[0043] Figure 5 shows an example of a separation unit 130. The separation unit 130 comprises an adsorption tank 131, a heater 132, and a pressure reducing pump 133. The adsorption tank 131 is a pressure vessel that stores an adsorbent material for adsorbing carbon dioxide inside. The adsorption tank 131 also has an openable and closable outlet 131a. The outlet 131a is used to replace the gas inside the adsorption tank 131. A heater 132 heats the inside of the adsorption tank 131. An electric heater is one example of a heater 132. A pressure reducing pump 133 reduces the pressure inside the adsorption tank 131. The pressure reducing pump 133 is powered by electricity. [The process of separating and recovering carbon dioxide] In the physical adsorption method, as shown in Figure 5, carbon dioxide is separated from other gases using a pressure difference or temperature difference. Specifically, first, the outlet 131a of the adsorption tank 131 is closed and the gas compressor 20 is driven. Compressed air from the gas compressor 20 is supplied to the adsorption tank 131, increasing the pressure inside the adsorption tank 131. When the pressure inside the adsorption tank 131 increases, the adsorbent material adsorbs carbon dioxide. Next, the outlet 131a is opened and the gas with a lower carbon dioxide concentration is discharged. Then, after closing the outlet, the pressure reducing pump 133 is driven to reduce the pressure inside the adsorption tank 131. When the pressure inside the adsorption tank 131 decreases, carbon dioxide is desorbed from the adsorbent material, and the desorbed carbon dioxide can be recovered.

[0044] [Variation 2] Figure 6 shows an example of the configuration of the separation unit 230 that uses a carbon dioxide absorbent liquid. Modification 2 of the first embodiment differs from Modification 1 of the first embodiment in that the separation unit 130 is replaced with a separation unit 230 that utilizes a carbon dioxide absorbent. The separation unit 230 comprises an absorption tower 231, a microbubble supply pipe 232, a regeneration tower 233, a heating unit 234, and absorbent pipes 235 and 236. The absorption tower 231 stores an absorbent that absorbs carbon dioxide, and a microbubble supply pipe 232 into which compressed air from the gas compression unit 20 is injected is inserted. The absorbent is, for example, an aqueous amine solution. The microbubble supply tube 232 ejects microbubbles into the absorbent liquid. Microbubbles are gases that have been made into tiny bubbles so that carbon dioxide can be easily absorbed into the absorbent liquid. Examples include nanobubbles, which have a size of less than 0.001 mm, and microbubbles, which have a size between 0.001 mm and 0.1 mm.

[0045] The regeneration tower 233 recovers carbon dioxide by desorbing it from the absorbent liquid that has absorbed it. The heating unit 234 heats the absorbent liquid in the regeneration tower 233. The absorbent liquid piping 235 connects the absorption tower 231 and the regeneration tower 233. The absorbent liquid piping 235 is equipped with a liquid transfer pump 235a that transfers the absorbent liquid from the absorption tower 231 to the regeneration tower 233. The absorbent liquid piping 236 connects the absorption tower 231 and the regeneration tower 233. The absorbent liquid piping 236 is equipped with a liquid transfer pump 236a that transfers the absorbent liquid from the regeneration tower 233 to the absorption tower 231. Here, the electric heater that heats the carbon dioxide absorbent liquid and the liquid transfer pump that transfers the absorbent liquid are powered by electricity generated from the wind turbine 18.

[0046] [The process of separating and recovering carbon dioxide] First, atmospheric air is supplied to the gas compression unit 20 from the gas intake port 911 of the tower 90. The gas compression unit 20 compresses the atmospheric air and supplies the compressed air to the separation unit 230. The separation unit 230 supplies the supplied air into the absorption tower 231 via the microbubble supply pipe 232. A portion of the carbon dioxide in the air supplied into the absorption tower 231 is absorbed by the absorbent liquid. Hereinafter, the absorbent liquid that has absorbed carbon dioxide may be referred to as the rich absorbent liquid. The absorption tower 231 releases the air, which has absorbed carbon dioxide and whose carbon dioxide concentration has decreased, into the atmosphere via the gas outlet 912.

[0047] The rich absorbent liquid from the absorption tower 231 is supplied to the regeneration tower 233 via the absorbent liquid piping 235 by the liquid transfer pump 235a. In the regeneration tower 233, the heating unit 234 generates heat to heat the rich absorbent liquid. The heated rich absorbent liquid is separated into absorbent liquid and carbon dioxide. The separated carbon dioxide is then supplied to the liquefaction unit 40. The regenerated absorbent liquid is then supplied back to the absorption tower 231 via the absorbent liquid piping 236 by the liquid transfer pump 236a and circulated. The separation unit 230 is an example of a carbon dioxide separation device. However, even if the absorbent liquid has been heated and regenerated, if the temperature of the absorbent liquid is high, the absorption performance when absorbing carbon dioxide again will decrease. Therefore, a cooler for cooling the regenerated absorbent liquid may be provided in the absorbent liquid piping 236, and the cooling supplied to the cooler may be obtained from a chiller operated by electricity generated from the wind turbine 18. Furthermore, in the separation and recovery of carbon dioxide using a chemical absorbent, in addition to the method of releasing compressed air into the absorbent container by creating bubbles, an open-system absorption tower may be installed in which the air flowing down the wind tower comes into contact with the absorbent. Carbon dioxide is absorbed into the absorbent within the wind tower, and then the carbon dioxide absorbent accumulated at the bottom of the recovery section is heated and regenerated to separate and recover the carbon dioxide gas. Finally, the regenerated absorbent is pumped up to the top of the tower.

[0048] The carbon dioxide separated in this manner is liquefied in the liquefaction section 40 by pressurization with a carbon dioxide compressor 41 and cooling with a turbo chiller 42, similar to the first embodiment. The liquefied carbon dioxide is pressurized by the injection pump 51 in the injection section 50 and flowed into the carbon dioxide injection piping 8. The carbon dioxide compressor 41, turbo chiller 42, and injection pump 51 can each be operated by supplying power generated from the wind turbine 18 through wiring connections within the tower. If fluctuations in wind power generation cause fluctuations in the system's operating state and adversely affect the stable injection of carbon dioxide or the system's components, a large-capacity battery storage system may be installed on the wind tower and connected to the wind turbine. Power may then be supplied stably from the large-capacity battery storage system to mitigate fluctuations during operation and ensure long-term stable operation.

[0049] [Second Embodiment] Figure 7 shows the overall configuration of the carbon dioxide storage system 3 according to the second embodiment. The carbon dioxide storage system 3 according to the second embodiment differs from the first embodiment in that an onshore wind power utilization facility is installed on the above-ground portion of the carbon dioxide storage tank located on land, and a biogas fermentation tank 210, a purification filter 211, and a methane gas tank 220 are further provided in close proximity to the onshore wind power utilization facility. The same reference numerals are used for functions similar to those in the first embodiment, and their explanation is omitted here. The biogas fermentation tank 210 generates biogas, mainly composed of methane and carbon dioxide, from biomass resources 101 for methane fermentation, such as food waste, non-edible agricultural parts, or livestock excrement, using anaerobic methane fermenting bacteria. The purification filter 211 removes hydrogen sulfide and excessive moisture contained in the biogas generated from the biogas fermentation tank 210. The methane gas tank 220 is a tank for storing methane gas separated from biogas. The methane gas stored in the methane gas tank 220 may be used, for example, by filling it into gas cylinders. Alternatively, the methane gas may be used, for example, as fuel to drive one of the devices of the carbon dioxide storage system 4.

[0050] Figure 8 is a schematic diagram showing an example of the configuration of the wind power drive unit 10 and the tower 90 according to the second embodiment. The carbon dioxide storage system 3 according to the second embodiment comprises a wind-driven unit 10, a gas compression unit 20, a separation unit 30, a liquefaction unit 40, and an injection unit 50. These wind-driven unit 10, gas compression unit 20, separation unit 30, liquefaction unit 40, and injection unit 50 are housed in a tower 90. The wind-driven unit 10 is located on the upper side of the tower 90, followed by the gas compression unit 20, separation unit 30, liquefaction unit 40, and injection unit 50, arranged vertically from the top in that order.

[0051] [The process of separating and recovering carbon dioxide] The biogas produced from the biogas fermentation tank 210 is filtered by a purification filter 211 to remove impurities and excess moisture. The biogas that has passed through the purification filter 211 contains carbon dioxide and methane and is supplied to the gas compression unit 20 from the gas intake 911 of the tower 90. The gas compression unit 20 compresses the biogas and supplies the compressed biogas to the separation unit 30. In the separation unit 30, the biogas is separated into carbon dioxide and methane. The separated methane is transported from the gas outlet 912 to the methane tank 220 for storage.

[0052] The carbon dioxide gas separated in the separation unit 30 is supplied to the liquefaction unit 40. In the liquefaction unit 40, the carbon dioxide gas is pressurized by a carbon dioxide compressor 41 and cooled by a turbo chiller 42, thereby liquefying it. The liquefied carbon dioxide is pressurized by an injection pump 51 in the injection unit 50 and flowed into the carbon dioxide injection piping 8. Separate methane gas can also be cooled and liquefied by the turbo chiller 42 to produce liquefied methane that is easier to store and transport. In the second embodiment, carbon dioxide was separated and recovered from biogas. However, the gas from which carbon dioxide is separated and recovered is not limited to biogas; for example, carbon dioxide may be separated and recovered from exhaust gas generated when fossil fuels or biogas are burned. In the second embodiment, carbon dioxide was separated using the separation unit 30, but carbon dioxide may also be separated using the separation unit 130 and the separation unit 230.

[0053] 〔others〕 In the illustrated example, the rotor shaft 13 extends in a substantially horizontal direction. However, the orientation of the rotor shaft 13 is not particularly limited and may extend in a substantially vertical direction. That is, the rotating part 11 may be a so-called vertical-axis wind turbine. Examples of vertical-axis wind turbines include Darrieus wind turbines and Savonius wind turbines. For example, in the third embodiment, if a vertical-axis wind turbine is used, the rotor shaft 13 will be arranged along the vertical direction, and the rotor shaft 13 can be used as a power transmission shaft 94 to drive a carbon dioxide gas suction pump 32, etc.

[0054] In this embodiment, liquefied carbon dioxide was stored in an underground storage tank using a pressure pump 51, but liquefied carbon dioxide may also be used as a raw material gas for commercial and industrial purposes. In this case, the pressure pump 51 may be used to fill carbon dioxide cylinders with high-pressure carbon dioxide gas or to fill tank trucks, etc., with liquefied carbon dioxide. Alternatively, the recovered carbon dioxide may be solidified and used as dry ice. [Explanation of Symbols]

[0055] 1, 2, 3…Carbon dioxide storage system, 8…Carbon dioxide injection piping, 10…Wind power drive unit, 11…Rotating unit, 12…Wind nacelle unit, 13…Rotor shaft, 14…Hub, 15…Blade, 16…Right-angle gear transmission, 17…Control device, 18…Wind turbine generator, 20…Gas compression unit, 30, 130, 230…Separation unit, 31…Separation membrane module, 32…Pump, 40…Liquefaction unit, 41…Carbon dioxide compressor, 42…Turbo cooling Freezing machine, 50...Injection section, 51...Injection pump, 53, 54...Pressure gauge, 55...Check valve, 60...Biogas fermentation tank, 90...Tower, 91...Side view, 911...Gas intake, 912...Gas outlet, 94...Power transmission shaft, 100...Offshore platform, 311...Housing, 312...Inlet, 313...Separation membrane, 314...Upstream outlet, 315...Downstream outlet, 911...Gas intake, 912...Gas outlet

Claims

1. A cylindrical tower, The wind turbine device arranged in the aforementioned tower, A carbon dioxide separation and recovery device, driven by the rotational shaft power obtained from the wind turbine device, separates and recovers carbon dioxide from the gas drawn in through an opening in the tower, A carbon dioxide gas compressor, driven by the rotating shaft power obtained from the wind turbine device, compresses the carbon dioxide gas separated and recovered by the carbon dioxide separation and recovery device, A pressurized pump, driven by the rotating shaft power obtained from the wind turbine device, pumps the carbon dioxide compressed by the compressor into an underground carbon dioxide storage tank, The system includes an injection well for injecting and storing carbon dioxide separated and recovered from the aforementioned gas into an underground carbon dioxide storage tank, A carbon dioxide storage system comprising the carbon dioxide separation and recovery device, the carbon dioxide gas compressor, and the injection pump, located inside the cylinder of the tower.

2. A cylindrical tower, The wind turbine device arranged in the aforementioned tower, A carbon dioxide separation and recovery device, driven by the rotational shaft power obtained from the wind turbine device, separates and recovers carbon dioxide from the gas drawn in through an opening in the tower, A carbon dioxide gas liquefaction device, which is driven by the rotating shaft power obtained from the wind turbine device and liquefies the carbon dioxide gas separated and recovered by the carbon dioxide separation and recovery device, A pressurized pump, driven by the rotating shaft power obtained from the wind turbine device, pumps the carbon dioxide compressed by the compressor into an underground carbon dioxide storage tank, The system includes an injection well for injecting and storing carbon dioxide separated and recovered from the aforementioned gas into an underground carbon dioxide storage tank, A carbon dioxide storage system comprising the carbon dioxide separation and recovery device, the carbon dioxide gas compressor, and the injection pump, located inside the cylinder of the tower.

3. The carbon dioxide storage system according to claim 1 or 2, characterized in that one or more of the carbon dioxide separation and recovery device, the carbon dioxide gas compressor, the carbon dioxide gas liquefaction device, and the injection pump are driven via electricity generated by the rotating shaft power obtained from the wind turbine device.

4. The carbon dioxide separation device comprises a carbon dioxide separation membrane, The carbon dioxide storage system according to claim 1 or 2, characterized in that the gas supplied to the separation membrane is supplied from an air inlet which is an opening provided at the top of the tower, and the gas is pressurized by a gas compressor driven by rotating shaft power obtained from the wind turbine device or generated electricity obtained from a generator connected to the wind turbine device and supplied to the separation membrane, or carbon dioxide gas is separated by suction by a carbon dioxide gas suction pump provided on the carbon dioxide gas suction passage of the separation membrane and driven by rotating shaft power obtained from the wind turbine device or generated electricity obtained from a generator connected to the wind turbine device, thereby separating and recovering carbon dioxide gas from the supplied gas.

5. The carbon dioxide separation device comprises a pressure vessel containing a carbon dioxide adsorbent, The carbon dioxide storage system according to claim 1 or 2, characterized in that the gas supplied to the pressure vessel is supplied through an air inlet which is an opening provided at the top of the tower, and carbon dioxide is separated and recovered from the supplied gas by supplying high-pressure gas to the pressure vessel using a gas compressor driven by rotating shaft power obtained from the wind turbine device or generated electricity obtained from a generator connected to the wind turbine device, and by depressurizing and suctioning from the pressure vessel using a suction pump driven by rotating shaft power obtained from the wind turbine device or generated electricity obtained from a generator connected to the wind turbine device.

6. The carbon dioxide separation apparatus includes a separation and recovery tower that utilizes a carbon dioxide absorption liquid. The carbon dioxide storage system according to claim 1 or claim 2, characterized in that the gas supplied to the separation and recovery tower is supplied from an air inlet, which is an opening provided at the top of the tower, and the supply of air and circulation of the absorbent liquid are carried out by an air blower and an absorbent liquid circulation pump, which are driven by rotating shaft power obtained from the wind turbine device or power generated from a generator connected to the wind turbine device, and the absorbent liquid that has absorbed carbon dioxide is heated and regenerated using power generated from a generator connected to the wind turbine device while being circulated and delivered, thereby separating and recovering carbon dioxide from the supply gas.

7. A carbon dioxide storage system characterized in that, in a carbon dioxide separation apparatus according to claim 1 or claim 2, the gas from which carbon dioxide has been separated and whose carbon dioxide concentration has decreased is exhausted from an exhaust port provided in the tower.

8. A cylindrical tower, The wind turbine device arranged in the aforementioned tower, A carbon dioxide separation and recovery device, driven by the rotational shaft power obtained from the wind turbine device, separates and recovers carbon dioxide from the gas drawn in through an opening in the tower, A carbon dioxide separation and recovery system characterized by comprising a carbon dioxide gas liquefaction device that is driven by the rotating shaft power obtained from the wind turbine device and liquefies the carbon dioxide gas separated and recovered by the carbon dioxide separation and recovery device.

9. A cylindrical tower and The wind turbine device arranged in the aforementioned tower, The wind turbine device is equipped with a generator connected to the aforementioned wind turbine device, A carbon dioxide separation and recovery system characterized in that one or more of the carbon dioxide separation and recovery apparatus and the carbon dioxide gas liquefaction apparatus described in claim 8 are driven by power generated from the generator.

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