Direct air capture system and method

Abstract

A direct air capture (DAC) system (100) includes a plurality of DAC units (102, 104). Each DAC unit (102, 104) of the plurality of DAC units (102, 104) includes at least one housing (112), at least one absorber (114) disposed within the at least housing (112), and at least one fan (116) mounted to the at least one housing (112) to generate an airflow (118). The airflow (118) exits the at least one housing (112) as an exit airflow (120) and flows towards a downstream DAC unit (104) of the plurality of DAC units (102, 104). At least one structure (136) is disposed between an upstream DAC unit (102) and the downstream DAC unit (104) of the plurality of DAC units (102, 104). The at least one structure (136) generates one or more wind eddies (146) from a surrounding air and mixes the one or more wind eddies (146) with the exit airflow (120) of the upstream DAC unit (102).

Description

[0001] DIRECT AIR CAPTURE SYSTEM AND METHOD

[0002] FIELD OF THE DISCLOSURE

[0003] The present disclosure relates to a direct air capture system, and a method of operating the direct air capture system.

[0004] BACKGROUND

[0005] Greenhouse gases, such as, carbon dioxide (CO2), are naturally occurring chemical compounds present in Earth's atmosphere. Increasing concentrations of greenhouse gases in the atmosphere has been a growing concern as they increase a risk of global warming. CO2 is a by-product of combustion of hydrocarbon fuels used in plants and factories, which are primary emission sources. Systems and methods are being implemented around the world to reduce CO2 in the atmosphere in an effort to achieve the goal of net zero emissions and reduce global warming.

[0006] Direct air capture (DAC) system is one such method to reduce the amount of CO2 in the atmosphere. DAC system captures CC from surrounding air and creates a concentrated CO2 product stream that can be sold, utilized, upgraded, or sequestered underground. The DAC system uses a sorbent medium to capture CO2 from the atmosphere. In order to capture large amounts of CO2 from the atmosphere, DAC systems typically include a plurality of DAC units that may be installed in a spaced apart manner. Each DAC unit treats air to reduce CC from the air such that CO2 depleted air exits the corresponding DAC unit. Typically, the CO2 depleted air exiting an upstream DAC unit is directed towards a downstream DAC unit. If the CO2 depleted air is directly introduced into the downstream DAC unit, the downstream DAC unit may not be used to its full capacity as the CO2 depleted air already contains low amounts of CO2. This phenomenon may decrease an efficiency of the DAC system.

[0007] In some cases, the DAC units may have to be separated from each other by a substantial distance for the downstream DAC unit to receive air that has near normal atmospheric concentrations of CO2. Such a separation distance may be hundreds of times of a height of the DAC units. This technique may impose a dilemma on the design of the DAC system as a large footprint of the DAC system may not be desirable. Therefore, it may be desirable to have a technique that facilitates usage of the DAC system to their full capacity for separating CC from the atmosphere and also increases the efficiency of the DAC system.

[0008] SUMMARY

[0009] In a first aspect, there is provided a direct air capture (DAC) system. The DAC system includes a plurality of DAC units spaced apart from each other. Each DAC unit of the plurality of DAC units includes at least one housing, at least one absorber disposed within the at least one housing, and at least one fan mounted to the at least one housing. The at least one fan is configured to generate an airflow. The airflow exits the at least one housing as an exit airflow and flows towards a downstream DAC unit of the plurality of DAC units. The DAC system further includes at least one structure disposed between an upstream DAC unit and a downstream DAC unit of the plurality of DAC units. The at least one structure is configured to generate one or more wind eddies from a surrounding air and to mix the one or more wind eddies with the exit airflow of the upstream DAC unit, such that a carbon dioxide (CO2) concentration of an inlet airflow provided to the downstream DAC unit is greater than a CO2 concentration of the exit airflow of the upstream DAC unit.

[0010] Further, the one or more wind eddies may create a large-scale dynamic flow structure that may cause a mixing of the exit airflow exiting the DAC unit with the surrounding air present downstream of the upstream DAC unit. The mixing of the CO2 depleted exit airflow with the surrounding air may prevent ingestion of air containing low amounts of CO2 into the downstream DAC unit and may direct substantially fresh air with near normal CO2 concentrations into the downstream DAC unit. Accordingly, the mixing of the exit airflow with the surrounding air may allow the downstream DAC unit to capture higher quantities of CO2 which may allow usage of the DAC system to its full capacity and may also increase an efficiency of the DAC system.

[0011] Thus, the principal advantage of the DAC system described herein is that the downstream DAC unit may be fed with the inlet airflow having near normal CO2 concentrations. Further, the at least one structure provides a means for mixing air present at higher elevations with the exit airflow. Such air present at higher elevation would otherwise simply blow over the DAC system and may contribute to global warming due to CO2 concentrations present therein. Essentially, an effective air collector area of the DAC system may increase to a height of the at least one structure, thereby increasing CO2 absorption by the DAC system. The structure may embody any mixing device known in the art.

[0012] In some embodiments, the at least one structure is a wind turbine. The wind turbine generates the one or more wind eddies from the surrounding air to mix the exit airflow exiting the upstream DAC unit with the surrounding air. Further, the wind turbine is a source of green energy and advantageously provides a low- carbon power solution of operating the DAC system. The wind turbine may further ensure that the DAC system has a stronger net negative CO2 emission profile.

[0013] In some embodiments, a rotor diameter of the wind turbine is greater than a vertical height of each DAC unit. The wind turbine having a large rotor diameter may sweep a larger area between adjacent DAC units and generate large wind eddies that may further promote mixing of the exit airflow with the surrounding air. The large rotor diameter may also serve to effectively bring in fresh air having higher concentrations of CO2 from above an installation site of the DAC system.

[0014] In some embodiments, a vertical height of the wind turbine is equal to or greater than a distance between the upstream DAC unit and the downstream DAC unit. Since the installation site in general may be limited for the installation of DAC systems, the wind turbine with the vertical height greater than or equal to the distance between two adjacent DAC units may be considered in order to produce the large wind eddies while simultaneously saving land areas which may be utilized for objectives other than DAC system installation.

[0015] In some embodiments, each DAC unit comprises a plurality of housings disposed adjacent to each other, a plurality of absorbers disposed within the corresponding plurality of housings, and a plurality of corresponding fans mounted to the corresponding plurality of housings. The plurality of housings provide a corresponding plurality of exit airflows. Thus, the DAC unit may include an array of modules, such that each module includes a corresponding housing, a corresponding absorber, and a corresponding fan. The wind eddies may cause mixing of the surrounding air with the exit airflows from each module of the DAC unit which may in turn direct substantially fresh air with near normal CO2 concentrations into the downstream DAC unit. Further, the array of modules may also allow capture of increased amounts of CO2 from the surrounding air passing through the DAC unit.

[0016] In some embodiments, the at least one structure is further configured to mix the plurality of exit airflows from the plurality of housings of the upstream DAC unit with the surrounding air. The at least one structure may allow mixing of the exit airflows with the surrounding air such that the inlet airflow being directed to the downstream DAC unit may have near normal CO2 concentration.

[0017] In some embodiments, the at least one structure comprises a plurality of structures. Each structure of the plurality of structures is disposed between a corresponding upstream DAC unit and a corresponding downstream DAC unit of the plurality of DAC units. The at least one structure may include any number of structures depending upon the application and design requirements for the DAC system. In some examples, a number of the structures disposed between the upstream DAC unit and the downstream DAC unit may be based on a distance between the upstream DAC unit and the downstream DAC unit. Further, such structures may be disposed so that the corresponding downstream DAC unit may receive the inlet airflow with near normal CO2 concentration due to adequate mixing of the exit airflow with the surrounding air present downstream of the upstream DAC unit.

[0018] In some embodiments, the absorber is configured to absorb at least a portion of CO2 present in the airflow generated by the fan. The absorber may be a liquid or a solid absorbent to effectively absorb CC from the airflow such that the airflow exiting a particular DAC unit has lower levels of CO2. The extracted CO2 may be collected to produce fuel for aircrafts or automobiles, ceramics, carbonated drinks, and the like. In some embodiments, the plurality of DAC units are arranged in a rectangular arrangement, a circular arrangement, a chevron arrangement, a horse-shoe arrangement, an angled arrangement, or a staggered arrangement. Such an arrangement of the DAC unit together with the wind eddies generated by the at least one structure may cause mixing of the surrounding air with the exit airflows from the DAC units which may in turn direct substantially fresh air with near normal CO2 concentrations into the downstream DAC unit. The plurality of DAC units may be arranged in any regular or irregular patterns as per operational requirements, or spatial constraints of the installation site of the DAC system.

[0019] In a second aspect, there is provided a method. The method includes providing a plurality of DAC units spaced apart from each other. Each DAC unit of the plurality of DAC units includes at least one housing, at least one absorber disposed within the at least one housing, and at least one fan mounted to the at least one housing and configured to generate an airflow. The airflow exits the at least one housing as an exit airflow and flows towards a downstream DAC unit of the plurality of DAC units. The method further includes providing at least one structure between an upstream DAC unit and the downstream DAC unit of the plurality of DAC units. The method further includes generating, via the at least one structure, one or more wind eddies from a surrounding air. The method further incudes mixing the one or more wind eddies with the exit airflow of the upstream DAC unit, such that a CO2 concentration of an inlet airflow provided to the downstream DAC unit is greater than a CO2 concentration of the exit airflow of the upstream DAC unit.

[0020] The method of this disclosure teaches generation of the one or more wind eddies by the at least one structure that may create a large-scale dynamic flow structure. The dynamic flow structure may cause a mixing of the exit airflow exiting the DAC unit with the surrounding air present downstream of a particular DAC unit. The mixing of the CO2 depleted exit airflow with the surrounding air may prevent ingestion of air containing low amounts of CO2 into the downstream DAC unit and may direct substantially fresh air with near normal CO2 concentrations into the downstream DAC unit. Accordingly, the mixing of the exit airflow with the surrounding air may allow the downstream DAC unit to capture higher quantities of CO2 which may allow usage of the DAC system to its full capacity and may also increase an efficiency of the DAC system.

[0021] Thus, the principal advantage of the method described herein is that the downstream DAC unit may be fed with the inlet airflow having near normal CO2 concentrations. Further, the at least one structure provides a means for mixing air present at higher elevations with the exit airflow. Such air present at higher elevation would otherwise simply blow over the DAC system and may contribute to global warming due to CO2 concentrations present therein. Essentially, an effective air collector area of the DAC system may increase to a height of the at least one structure, thereby increasing CO2 absorption by the DAC system.

[0022] In some embodiments, each DAC unit comprises a plurality of housings disposed adjacent to each other, a plurality of absorbers disposed within the corresponding plurality of housings, and a plurality of corresponding fans mounted to the corresponding plurality of housings. The plurality of housings provide a corresponding plurality of exit airflows. The method further includes mixing, by the at least one structure, the plurality of exit airflows from the plurality of housings of the upstream DAC unit with the surrounding air. The one or more wind eddies create coherent swirling flow and transport low concentration CO2 air up into the atmosphere while bringing high CO2 concentration air down to a ground level where it may be extracted by the DAC units for adsorption or absorption of CO2. Further, the wind eddies may also cause mixing of the surrounding air with the exit airflows from the plurality of corresponding fans which may in turn direct substantially fresh air with near normal CO2 concentrations into the downstream DAC unit.

[0023] In some embodiments, the at least one absorber absorbs at least a portion of CO2 present in the airflow generated by the fan. The absorber may be a liquid or a solid absorbent to effectively absorb CO2 from the airflow flowing through the absorber, such that the exit airflow exiting a particular DAC unit has lower levels of CO2. The extracted CO2 may be collected to produce fuel for aircrafts or automobiles, ceramics, carbonated drinks, and the like. In some embodiments, the at least one structure includes a plurality of structures. Each structure of the plurality of structures is disposed between a corresponding upstream DAC unit and a corresponding downstream DAC unit of the plurality of DAC units. The at least one structure may include any number of structures depending upon the application and design requirements for the DAC system. In some examples, a number of the structures disposed between the upstream DAC unit and the downstream DAC unit may be based on a distance between the upstream DAC unit and the downstream DAC unit. Further, such structures may be disposed so that the corresponding downstream DAC unit may receive the inlet airflow with near normal CO2 concentration due to adequate mixing of the exit airflow with the surrounding air present downstream of the upstream DAC unit.

[0024] The skilled person will appreciate that except where mutually exclusive, a feature or parameter described in relation to any one of the above aspects may be applied to any other aspect. Furthermore, except where mutually exclusive, any feature or parameter described herein may be applied to any aspect and / or combined with any other feature or parameter described herein.

[0025] BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Embodiments will now be described by way of example only, with reference to the Figures, in which:

[0027] Figure 1 is a schematic view illustrating a direct air capture (DAC) system having two DAC units, according to an embodiment of the present disclosure;

[0028] Figure 2 is a schematic block diagram illustrating the DAC system of Figure 1 , according to an embodiment of the present disclosure;

[0029] Figure 3 is a schematic perspective view illustrating a DAC unit of Figure 1 having multiple DAC modules, according to an embodiment of the present disclosure;

[0030] Figure 4 is a schematic view illustrating a DAC system, according to another embodiment of the present disclosure;

[0031] Figures 5A, 5B, 5C, and 5D are schematic top views illustrating different arrangements of DAC units, according to an embodiment of the present disclosure;

[0032] Figure 6A and 6B are schematic top views illustrating different arrangements of DAC units, according to another embodiment of the present disclosure; and Figure 7 is a flowchart of a method of operating the DAC system of Figure 1 , according to an embodiment of the present disclosure.

[0033] DETAILED DESCRIPTION

[0034] Aspects and embodiments of the present disclosure will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art.

[0035] Figure 1 shows a schematic view illustrating a direct air capture (DAC) system 100, according to an embodiment of the present disclosure. The DAC system 100 is embodied as a system capable of separating carbon dioxide (CO2) from ambient air in order to tackle global warming. The DAC system 100 may be installed at an installation site.

[0036] The DAC system 100 includes a plurality of DAC units 102, 104 spaced apart from each other. In the illustrated embodiment of Figure 1 , the DAC system 100 includes two DAC units 102, 104. However, any number of DAC units may be installed to form the DAC system 100 as per operational requirements of the DAC system 100. Further, the plurality of DAC units 102, 104 may be spaced apart from each other by a distance D1. The distance D1 may be any integral or fractional value and may be chosen to improve an efficiency of the DAC system 100 and to judiciously utilize the installation site. The DAC unit 102 is embodied as an upstream DAC unit 102 and the DAC unit 104 is embodied as a downstream DAC unit 104. In the following disclosure, the terms upstream and downstream are considered to be relative to a direction of air flowing through the DAC units 102, 104. Further, the DAC units 102, 104 are identical to each other in design and functionality. An airflow 118 with normal or relatively high concentrations of CO2 enters the DAC unit 102. Further, an exit airflow 120 exits the DAC unit 102. The exit airflow 120 includes low or zero concentrations of CO2. The exit airflow 120 flows towards the downstream DAC unit 104 of the plurality of DAC units 102, 104. In some examples, at least a portion of the exit airflow 120 exiting the DAC unit 102 may be received by the downstream DAC unit 104. In other words, an inlet airflow 119 entering the DAC unit 104 may contain some amounts of the exit airflow 120. Further, based on a treatment of the inlet airflow 119 within the DAC unit 104, an exit airflow 121 having low levels of CO2 may exit the DAC unit 104.

[0037] Referring now to Figure 2, a schematic block diagram of the DAC system 100 for capturing CO2 from a CO2 containing stream of gas is illustrated. For the sake of simplicity, Figure 2 will now be described in relation to treatment of the airflow 118 flowing through the DAC unit 102. However, the description provided herein is equally applicable to treatment of the inlet airflow 119 (see Figure 1 ) flowing through the DAC unit 104 (see Figure 1 ).

[0038] The DAC system 100 is embodied as a liquid-absorbent DAC system herein. Alternatively, the DAC system 100 may be embodied as a solid-absorbent DAC system that is conventionally known in the art. Further, the CO2 containing stream of gas includes the airflow 118 that enters the DAC unit 102. The DAC unit 102 of the plurality of DAC units 102, 104 includes at least one housing 112. The at least one housing 112 may have any shape and size as per the operational requirements of the DAC system 100. For example, the at least one housing 112 may have a box-shape. Further, the housing 112 may be made from any suitable material known in the art.

[0039] Furthermore, the DAC unit 102 includes at least one absorber 114 disposed within the at least one housing 112, and at least one fan 116 mounted to the at least one housing 112. In other embodiments, the absorber 114 may be replaced by an adsorber. The airflow 118 exits the at least one housing 112 as an exit airflow 120 and flows towards the downstream DAC unit 104 of the plurality of DAC units 102, 104. Thus, the airflow 118 is received within the DAC unit 102, the airflow 118 is treated within the DAC unit 102, and the airflow 118 exits the DAC unit 102 as the exit airflow 120 containing low levels of CO2. The fan 116 may include a plurality of blades (not shown) that may be rotated by withdrawing power from an electric motor (not shown). In some embodiments, the fan 116 may be located before (or upstream of) the absorber 114 in the housing 112. However, in some embodiments, the fan 116 may be located after (or downstream of) the absorber 114 in the housing 112. In some embodiments, more than one fan 116 may be associated with a corresponding absorber 114. Alternatively, multiple absorbers 114 may share a single fan 116.

[0040] Further, the at least one absorber 114 is configured to absorb at least a portion of CO2 present in the airflow 118 generated by the fan 116. Further, a sorbent flows through the absorber 114 and interacts with the airflow 118 received within the absorber 114. The sorbent may include any conventional sorbent that may absorb CC from the airflow 118. In some examples, the sorbent may be an aqueous potassium hydroxide solution or potassium carbonate. In the illustrated embodiment of Figure 2, a lean stream 124 of the sorbent enters the absorber 114. The term “lean stream” as used throughout the disclosure relates to a stream of the sorbent that has low values of CO2. The lean stream 124 contacts the airflow 118 within the absorber 114 and absorbs CO2 therefrom to become a rich stream 126. The term “rich stream” as used throughout the disclosure relates to a stream of the sorbent that has high values of CO2. The lean stream 124 is converted to the rich stream 126 based on the absorption of CC from the airflow 118 flowing through the absorber 114. Further, a recirculation stream 122 of the sorbent may be recirculated within the absorber 114. The recirculation stream 122 may increase an effective residence time of each portion of the lean stream 124 of the sorbent in the absorber 114.

[0041] Further, the DAC system 100 includes a heat exchanger 128. The rich stream 126 passes through the heat exchanger 128 to recover heat from the lean stream 124 returning from a desorber 130 of the DAC system 100. Based on the heat exchange at the heat exchanger 128, a temperature of the rich stream 126 exiting the heat exchanger 128 is slightly increased. Further, the desorber 130 receives the rich stream 126 from the heat exchanger 128 and heats it up to a temperature that causes CO2 to be released form the rich stream 126. The DAC system 100 further includes a heating means 132. The heating means 132 is embodied as a reboiler herein. The heating means 132 increases the temperature of the rich stream 126 by circulating a heated stream 133 of the sorbent through the desorber 130. Specifically, the heating means 132 receives a portion of the lean stream 124 exiting the desorber 130. Further, the heating means 132 heats the lean stream 124 to form the heated stream 133 that is introduced in the desorber 130. The heating means 132 may also generate steam to form vapour bubbles into which the desorbed CO2 can diffuse, leaving the lean stream 124 of the sorbent to return to the absorber 114 to repeat the process. Further, a mixture 131 of the vapour and desorbed CO2 exits the desorber 130. The DAC system 100 further includes a condenser 134 in fluid communication with the desorber 130. The condenser 134 receives the mixture 131 of the vapour and desorbed CO2 from the desorber 130 and may cool the mixture 131 causing the vapour to condense leaving a CO2 product stream 135. The CO2 product stream 135 may be collected to produce fuel for aircrafts or automobiles, ceramics, carbonated drinks, and the like.

[0042] Referring now to Figure 3, the DAC unit 102 includes a plurality of DAC modules 110. In some embodiments, each DAC unit 102, 104 of the plurality of the DAC units 102, 104 includes a plurality of housings 112 disposed adjacent to each other, a plurality of absorbers 114 disposed within the corresponding plurality of housings 112, and a plurality of corresponding fans 116 mounted to the corresponding plurality of housings 112 such that the plurality of housings 112 provide a corresponding plurality of exit airflows 120. In other words, each DAC module 110 includes a corresponding housing 112, a corresponding absorber 114, and a corresponding fan 116. Alternatively, each DAC module 110 may include more than one absorber 114 and / or more than one fan 116, as per application requirements. The housings 112, the absorbers 114, and the fans 116 are schematically illustrated in Figure 3. Further, the array of the DAC modules 110 may allow capture of increased amounts of CO2 from the surrounding air passing through the DAC unit 102.

[0043] Referring again to Figure 1 , the exit airflow 120 that exits the upstream DAC unit contains low levels of CO2. If the exit airflow 120 is directly introduced into the downstream DAC unit 104, the downstream DAC unit 104 may not be utilized to its full capacity. Accordingly, the DAC system 100 includes at least one structure 136 disposed between the upstream DAC unit 102 and the downstream DAC unit 104 of the plurality of DAC units 102, 104. The at least one structure 136 is configured to generate one or more wind eddies 146 from a surrounding air and to mix the one or more wind eddies 146 with the exit airflow 120 of the upstream DAC unit 102, such that the CO2 concentration of the inlet airflow 119 provided to the downstream DAC unit 104 is greater than the CO2 concentration of the exit airflow 120 of the upstream DAC unit 102. In some embodiments, the at least one structure 136 is further configured to mix the plurality of exit airflows 120 from the plurality of housings 112 (as shown in Figure 3) of the upstream DAC unit 102 with the surrounding air. The at least one structure 136 may allow mixing of the exit airflows 120 with the one or more wind eddies 146 such that the inlet airflow 119 being directed to the downstream DAC unit 104 may have near normal CO2 concentration.

[0044] Thus, the principal advantage of the at least one structure 136 is that the downstream DAC unit 104 may be fed with the inlet airflow 119 having near normal CO2 concentrations. Further, the at least one structure 136 provides a means for mixing air present at higher elevations with the exit airflow 120. Such air present at higher elevation would otherwise simply blow over the DAC system 100 and may contribute to global warming due to CO2 concentrations present therein. Further, the at least one structure 136 allows the absorber (not shown) of the downstream DAC unit 104 to capture higher quantities of CC than would have been possible if they had just been supplied with the exit airflow 120 from the upstream DAC unit 102.

[0045] The at least one structure 136 may include any structure, such as, a mixing device, which may facilitate mixing of the exit airflow 120 with the surrounding air. In the illustrated embodiment of Figure 1 , the at least one structure 136 is a wind turbine 138. Further, the wind turbine 138 is a source of green energy and advantageously provides a low-carbon power solution of operating the DAC system 100 and may ensure that the DAC system 100 has a stronger net negative CO2 emission profile.

[0046] The wind turbine 138 includes a post 140, a hub 142, and a plurality of rotors 144 coupled to the hub 142. In some examples, one or more dimensions of the wind turbine 138 may depend on one or more dimensions of the DAC units 102, 104 and / or the distance D1 between the DAC units 102, 104. The wind turbine 138 has a vertical height H1 . By virtue of the wind turbine 138, an effective air collector area of the DAC system 100 may be increased to the vertical height H1 , thereby increasing CO2 absorption by the DAC system 100. Further, the hub 142 of the wind turbine 138 has a height H2 with respect to a ground level of the installation site.

[0047] Further, the wind turbine 138 has a rotor diameter D2. In some embodiments, the rotor diameter D2 of the wind turbine 138 is greater than a vertical height H3 of each DAC unit 102, 104. In some examples, the wind turbine 138 having the larger rotor diameter D2 may sweep a larger area between the DAC units 102, 104 and generate large wind eddies 146 that may further promote mixing of the exit airflow 120 with the surrounding air. The large rotor diameter D2 may also serve to effectively bring in fresh air having higher concentrations of CO2 from above the installation site of the DAC system 100 towards the ground level.

[0048] The structure in general needs to have a vertical dimension H1 that is at least half the distance D1 between adjacent DAC units in the direction the prevailing wind is blowing. If the structure is at least this height, the eddies generated will promote stirring of the air between the DAC exhaust and the fresh air above. A taller structure will create larger scale eddies and greater mixing, so a structure that has a vertical height H1 equal to or greater than the distance D1 would be advantageous.

[0049] The structure may have a wind diverter as part of the upper part of the structure. The wind diverter will be shaped to cause eddies that divert the prevailing wind downward and promote mixing of the air. When the structure is a wind turbine, the nacelle of the wind turbine may be tilted to cause the wake of the wind turbine to be diverted. The tilt of the turbine may set to divert the wake downwards to cause the mixed wave to enter the inlet of downstream DAC units. The tilt of multiple wind turbines may be controlled to both divert mixed air into downstream DAC units and also to avoid wake of a first turbine interfering with generation by a downstream turbine.

[0050] In some embodiments, the vertical height H1 of the wind turbine 138 is equal to or greater than the distance D1 between the upstream DAC unit 102 and the downstream DAC unit 104. Since, the installation site in general may be limited for the installation of DAC systems 100, the wind turbine 138 with the vertical height H1 greater than or equal to the distance D1 between two adjacent DAC units 102, 104 may be considered in order to produce large wind eddies 146 while simultaneously saving land areas which may be utilized for other objectives than installation of the DAC system 100.

[0051] By way of example, if the distance D1 between the two DAC units 102, 104 is up to 100 metres (m), then large wind eddies 146 in the range of 100 m may be required to promote mixing of the exit airflow 120 with the surrounding air. This may be accomplished by the wind turbine 138 whose hub height H2 is between 50 m and 200 m, and whose rotor diameter D2 is approximately between 25 m and 75 m. The wind turbine 138 with these dimensions may also serve to effectively bring in fresh air from around 200 m to 300 m above the installation site towards the ground level. In other words, rather than the DAC system 100 extracting CC from the surrounding air up to the vertical height H3 of each DAC unit 102, 104, now the same size DAC system 100 may extract a proportion of CO2 present in the surrounding air up to the vertical height H1 of the wind turbine 138. Thus, the effective air collector area may be increased to the vertical height H1 of the wind turbine 138.

[0052] Referring now to Figure 4, in some embodiments, the at least one structure 136 comprises a plurality of structures 436A, 436B. Further, each structure 436A, 436B of the plurality of structures 436A, 436B is disposed between the corresponding upstream DAC unit 102 and the corresponding downstream DAC unit 104 of the plurality of DAC units 102, 104. A number of the structures 436A, 436B may depend upon the application and design requirements for the DAC system 100. In some examples, a number of the structures 436A, 436B disposed between the upstream DAC unit 102 and the downstream DAC unit 104 may be based on a distance D3 between the upstream DAC unit 102 and the downstream DAC unit 104. For example, if the distance D3 is large, the DAC system 100 may include the two structure 436A, 436B or more. Further, such structures 436A, 436B may be disposed so that the downstream DAC unit 104 may receive the inlet airflow 119 with near normal CO2 concentration due to adequate mixing of the exit airflow 120 with the surrounding air present downstream of the upstream DAC unit 102. Referring now to Figures 5A to 6B, the plurality of DAC units 502A, 504A, 502B, 502C, 502D, 602A, 604A, 602B, 604B may be arranged in different arrangements, such as, a rectangular arrangement, a circular arrangement, a chevron arrangement, a horse-shoe arrangement, an angled arrangement, or a staggered arrangement. As shown in Figure 5A, the plurality of DAC units 502A, 504A are arranged in the rectangular arrangement with a wind turbine 538A positioned between the DAC units 502A, 504A. Alternatively, two wind turbines 538A that may be laterally or longitudinally spaced apart from each other may be disposed between the DAC units 502A, 504A. Furthermore, as shown in Figure 5B, the plurality of DAC units 502B may be arranged in a circular arrangement with one wind turbine 538B disposed between adjacent DAC units 502B. Moreover, as shown in Figure 5C, the plurality of DAC units 502C may be arranged in a chevron arrangement with one wind turbine 538C disposed between adjacent DAC units 502C. Further, as shown in Figure 5D, the plurality of DAC units 502D may be arranged in a horseshoe arrangement with one wind turbine 538D disposed between adjacent DAC units 502D.

[0053] Referring now to Figure 6A, the plurality of DAC units 602A, 604A may be arranged in an angled arrangement. Specifically, the DAC units 602A are inclined to each other whereas the DAC units 604A are inclined to each other. Further, a wind turbine 638A is disposed between the upstream and downstream DAC units 602A, 604A. Alternatively, two wind turbines 638A that may be laterally or longitudinally spaced apart from each other may be disposed between the DAC units 602A, 604A. As shown in Figure 6B, the plurality of DAC units 602B, 604B may be arranged in a staggered arrangement with two wind turbines 638B spaced apart from each other between the upstream and downstream DAC units 602B, 604B. The arrangement of the DAC units 502A, 504A, 502B, 502C, 502D, 602A, 604A, 602B, 604B together with the wind eddies (not shown) generated by the corresponding wind turbines 538A, 538B, 538C, 538D, 638A, 638B may cause mixing of the surrounding air with the exit airflow (not shown) from the DAC units 502A, 502B, 502C, 502D, 602A, 602B which may in turn direct substantially fresh air with near normal CO2 concentrations into the downstream DAC units 504A, 502B, 502C, 502D, 604A, 604B. Figure 7 illustrates a flowchart for a method 700. Referring to Figures 1 , 2, 3, and 7, at step 702, the method 700 includes providing the plurality of DAC units 102, 104 spaced apart from each other. Each DAC unit 102, 104 of the plurality of DAC units 102, 104 includes the at least one housing 112, the at least one absorber 114 disposed within the at least one housing 112, and the at least one fan 116 mounted to the at least one housing 112 and configured to generate the airflow 118. The airflow 118 exits the at least one housing 112 as the exit airflow 120 and flows towards the downstream DAC unit 104 of the plurality of DAC units 102, 104.

[0054] At step 704, the method 700 includes providing the at least one structure 136 between the upstream DAC unit 102 and the downstream DAC unit 104 of the plurality of DAC units 102, 104. At step 706, the method 700 includes generating, via the at least one structure 136, the one or more wind eddies 146 from the surrounding air. At step 708, the method 700 includes mixing the one or more wind eddies 146 with the exit airflow 120 of the upstream DAC unit 102, such that the CO2 concentration of the inlet airflow 119 provided to the downstream DAC unit 104 is greater than the CO2 concentration of the exit airflow 120 of the upstream DAC unit 102.

[0055] Further, the method 700 teaches generation of the one or more wind eddies 146 by the at least one structure 136 that may create a large-scale dynamic flow structure. The dynamic flow structure may cause a mixing of the exit airflow 120 exiting the DAC unit 102 with the surrounding air present downstream of the DAC unit 102. The mixing of the CO2 depleted exit airflow 120 with the surrounding air may prevent ingestion of air containing low amounts of CO2 into the downstream DAC unit 104 and may direct substantially fresh air with near normal CO2 concentrations into the downstream DAC unit 104. Accordingly, the mixing of the exit airflow 120 with the surrounding air may allow the downstream DAC unit 104 to capture higher quantities of CO2 which may allow usage of the DAC system 100 to its full capacity and may also increase the efficiency of the DAC system 100.

[0056] Thus, the principal advantage of the method 700 is that the downstream DAC unit 104 may be fed with the inlet airflow 119 having near normal CO2 concentrations. Further, the at least one structure 136 provides a means for mixing air present at higher elevations with the exit airflow 120. Such air present at higher elevation would otherwise simply blow over the DAC system 100 and may contribute to global warming due to CO2 concentrations present therein. Essentially, the effective air collector area of the DAC system 100 may increase to the vertical height H1 of the at least one structure 136 and maximum possible amount of CO2 may be absorbed from the surrounding air.

[0057] Further, each DAC unit 102 includes the plurality of housings 112 disposed adjacent to each other, the plurality of absorbers 114 disposed within the corresponding plurality of housings 112, and the plurality of corresponding fans 116 mounted to the corresponding plurality of housings 112. The plurality of housings 112 provide the corresponding plurality of exit airflows 120. The method 700 further includes mixing, by the at least one structure 136, the plurality of exit airflows 120 from the plurality of housings 112 of the upstream DAC unit 102 with the surrounding air. Further, the wind eddies 146 may also cause mixing of the surrounding air with the exit airflows 120 from the plurality of corresponding fans 116 which may in turn direct substantially fresh air with near normal CO2 concentrations into the downstream DAC unit 104.

[0058] Further, the at least one absorber 114 absorbs at least the portion of CO2 present in the airflow 118 generated by the fan 116. The absorber 114 may be a liquid or solid absorbent to effectively absorb CC from the airflow 118 such that the exit airflow 120 exiting the DAC unit 102 has lower levels of CO2. The extracted CO2 may be collected to produce fuel for aircrafts or automobiles, ceramics, carbonated drinks, and the like.

[0059] As shown in Figures 4 and 7, in some embodiments, providing the at least one structure 136 further includes providing the plurality of structures 436A, 436B. Further, each structure 436A, 436B of the plurality of structures 436A, 436B is disposed between the corresponding upstream DAC unit 102 and the corresponding downstream DAC unit 104 of the plurality of DAC units 102, 104. It will be understood that the invention is not limited to the embodiments abovedescribed and various modifications and improvements can be made without departing from the concepts described herein. Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and subcombinations of one or more features described herein.

Claims

CLAIMS: A direct air capture (DAC) system (100) comprising: a plurality of DAC units (102, 104) spaced apart from each other, each DAC unit (102, 104) of the plurality of DAC units (102, 104) comprising at least one housing (112), at least one absorber (114) disposed within the at least one housing (112), and at least one fan (116) mounted to the at least one housing (112) and configured to generate an airflow (118), wherein the airflow (118) exits the at least one housing (112) as an exit airflow (120) and flows towards a downstream DAC unit (104) of the plurality of DAC units (102, 104); and at least one structure (136) disposed between an upstream DAC unit (102) and a downstream DAC unit (104) of the plurality of DAC units (102, 104), wherein the at least one structure (136) is configured to generate one or more wind eddies (146) from a surrounding air and to mix the one or more wind eddies (146) with the exit airflow (120) of the upstream DAC unit (102), such that a carbon dioxide (CO2) concentration of an inlet airflow (119) provided to the downstream DAC unit (104) is greater than a CO2 concentration of the exit airflow (120) of the upstream DAC unit (102). The DAC system (100) of claim 1 , wherein the at least one structure (136) is a wind turbine (138). The DAC system (100) of claim 2, wherein a rotor diameter (D2) of the wind turbine (138) is greater than a vertical height (H3) of each DAC unit 102, 104. The DAC system (100) of claim 1 , 2 or claim 3, wherein a vertical height (H1 ) of the at least one structure (136) is equal to or greater than half the distance (D1 ) between the upstream DAC unit (102) and the downstream DAC unit (104). The DAC system (100) of any preceding claim, wherein each DAC unit (102, 104) comprises a plurality of housings (112) disposed adjacent toeach other, a plurality of absorbers (114) disposed within the corresponding plurality of housings (112), and a plurality of corresponding fans (116) mounted to the corresponding plurality of housings (112), and wherein the plurality of housings (112) provide a corresponding plurality of exit airflows (120). The DAC system (100) of claim 5, wherein the at least one structure (136) is further configured to mix the plurality of exit airflows (120) from the plurality of housings (112) of the upstream DAC unit (102) with the surrounding air. The DAC system (100) of any preceding claim, wherein the at least one structure (136) comprises a plurality of structures (436A, 436B), and wherein each structure (436A, 436B) of the plurality of structures (436A, 436B) is disposed between a corresponding upstream DAC unit (102) and a corresponding downstream DAC unit (104) of the plurality of DAC units (102, 104). The DAC system (100) of any preceding claim, wherein the at least one absorber (114) is configured to absorb at least a portion of CO2 present in the airflow (118) generated by the fan (116). The DAC system (100) of any preceding claim, wherein the plurality of DAC units (102, 104) are arranged in a rectangular arrangement, a circular arrangement, a chevron arrangement, a horse-shoe arrangement, an angled arrangement, or a staggered arrangement. A method (700) comprising: providing a plurality of direct air capture (DAC) units (102, 104) spaced apart from each other, each DAC unit (102, 104) of the plurality of DAC units (102, 104) comprising at least one housing (112), at least one absorber (114) disposed within the at least one housing (112), and at least one fan (116) mounted to the at least one housing (112) and configured to generate an airflow (118), wherein the airflow (118) exits the at least onehousing (112) as an exit airflow (120) and flows towards a downstream DAC unit (104) of the plurality of DAC units (102, 104); providing at least one structure (136) between an upstream DAC unit (102) and a downstream DAC unit (104) of the plurality of DAC units (102, 104); generating, via the at least one structure (136), one or more wind eddies (146) from a surrounding air; and mixing, via the at least one structure (136), the one or more wind eddies (146) with the exit airflow (120) of the upstream DAC unit (102), such that a carbon dioxide (CO2) concentration of an inlet airflow (119) provided to the downstream DAC unit (104) is greater than a CO2 concentration of the exit airflow (120) of the upstream DAC unit (102). The method (700) of claim 10, wherein each DAC unit (102, 104) comprises a plurality of housings (112) disposed adjacent to each other, a plurality of absorbers (114) disposed within the corresponding plurality of housings (112), and a plurality of corresponding fans (116) mounted to the corresponding plurality of housings (112), and wherein the plurality of housings (112) provide a corresponding plurality of exit airflows (120), the method (700) further comprising mixing, by the at least one structure (136), the plurality of exit airflows (120) from the plurality of housings (112) of the upstream DAC unit (102) with the surrounding air. The method (700) of claim 10 or claim 11 , further comprising absorbing, via the at least one absorber (114), at least a portion of CO2 present in the airflow (118) generated by the fan (116). The method (700) of any one of claims 10 to 12, wherein providing the at least one structure (136) further comprises providing a plurality of structures (436A, 436B), and wherein each structure (436A, 436B) of the plurality of structures (436A, 436B) is disposed between a corresponding upstream DAC unit (102) and a corresponding downstream DAC unit(104) of the plurality of DAC units (102, 104).

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