Module, system, and method

Abstract

The present invention provides a module for use in a direct air capture (DAC) system, the module comprising: a humidifying section, the humidifying section being configured to increase the humidity of an air stream to provide a humidified air stream; and an absorber section located downstream of the humidifying section, the absorber section being configured to contact the humidified air stream with a sorbent and thereby capture at least a portion of the carbon dioxide from the humidified air stream.

Description

[0001] MODULE, SYSTEM, AND METHOD

[0002] INTRODUCTION

[0003] The present invention relates to a module for use in a direct air capture (DAC) system, to a system comprising the module, and to uses of the module and the system. The present invention also relates to a method of DAC.

[0004] BACKGROUND

[0005] Direct Air Capture (DAC) is the capture of carbon dioxide (or CO2) from atmospheric air. Such a process may be used to reduce atmospheric carbon dioxide, in order to mitigate the anthropogenic emissions that are associated with global warming, or climate change.

[0006] Direct air capture (DAC) of atmospheric carbon dioxide typically involves encouraging an incoming air stream to interact with a sorbent in an absorber section of a DAC system. The sorbent absorbs some portion of the carbon dioxide from the air stream, with a carbon dioxide depleted air stream exiting the absorber section. Further, the carbon dioxide may subsequently be separated from the sorbent during a desorption process, allowing the carbon dioxide to be captured and stored.

[0007] In typical DAC systems, an air stream is flowed into the volume of an absorber section, where it is exposed to a large surface area of sorbent. With the large surface area in contact between the air and aqueous sorbent, there is significant evaporation of water from the sorbent into the air stream. The flowing air stream takes moisture with it, removing water from the system.

[0008] Top-up water must therefore be added to the sorbent to keep it within a desired concentration range for carbon dioxide capture. Over time, a large volume of such top- up water may need to be purchased to compensate for evaporative losses.

[0009] Moreover, as water is evaporated, any dissolved solids or minerals may concentrate in the system. This may necessitate regular cleaning operations and downtime. Alternatively, the operator will be required to purchase highly pure water - such as demineralised water - as top-up water, in order to maintain low levels of fouling in the plant. Both of these factors add to the expense of the process.

[0010] Especially on days where the humidity of ambient atmospheric air is low, the top- up water consumption in a location may be excessive, with a water demand that is too high. This may be particularly true if the DAC system is located in an arid environment.

[0011] 38265848-2 Evaporative loss from the sorbent employed in DAC is thus problematic, potentially limiting the locations where DAC can be operated and adding to expense. There is therefore a need to reduce water loss from the sorbent in DAC systems and methods.

[0012] US 2021 / 101107 A1 relates to techniques for humidifying a gas stream. CN 118681384 A relates to a system and method for mineralizing carbon dioxide in air.

[0013] SUMMARY OF THE INVENTION

[0014] Viewed from a first aspect, the present invention provides a module for use in a direct air capture (DAC) system, the module comprising: a humidifying section, the humidifying section being configured to increase the humidity of an air stream to provide a humidified air stream; and an absorber section located downstream of the humidifying section, the absorber section being configured to contact the humidified air stream with a sorbent and thereby capture at least a portion of the carbon dioxide from the humidified air stream.

[0015] The humidifying section of the module of the present invention provides a humidified air stream from which carbon dioxide can subsequently be captured in the downstream absorber section. Increasing the humidity of the air stream prior to its passage to the downstream absorber section reduces the driving force for evaporative losses from the sorbent in the absorber section. Water demands and the build-up of solid impurities in the absorber section are therefore both desirably reduced.

[0016] Viewed from a further aspect, the present invention provides a module for use in a direct air capture (DAC) system, the module comprising: a humidifying section, the humidifying section being configured to increase the humidity of an air stream to provide a humidified air stream having a humidity of between 70 to 97.5 %; and an absorber section located downstream of the humidifying section, the absorber section being configured to contact the humidified air stream with a sorbent and thereby capture at least a portion of the carbon dioxide from the humidified air stream, wherein the sorbent comprises one or more amino acid salts.

[0017] Viewed from a further aspect, the present invention provides a module for use in a direct air capture (DAC) system, the module comprising: a humidifying section, the humidifying section being configured to increase the humidity of an air stream and to cool the air stream to provide a humidified air stream; and

[0018] 38265848-2 an absorber section located downstream of the humidifying section, the absorber section being configured to contact the humidified air stream with a sorbent and thereby capture at least a portion of the carbon dioxide from the humidified air stream.

[0019] Viewed from a further aspect, the present invention provides a module for use in a direct air capture (DAC) system, the module comprising: a humidifying section, the humidifying section being configured to increase the humidity of an air stream and to cool the air stream to provide a humidified air stream having a humidity of between 70 to 97.5 %; and an absorber section located downstream of the humidifying section, the absorber section being configured to contact the humidified air stream with a sorbent and thereby capture at least a portion of the carbon dioxide from the humidified air stream, wherein the sorbent comprises one or more amino acid salts.

[0020] Viewed from another aspect, the present invention provides a direct air capture (DAC) system, the system comprising a module as hereinbefore described.

[0021] Viewed from another aspect, the present invention provides use of a module as hereinbefore described for the manufacture of a direct air capture (DAC) system.

[0022] Viewed from another aspect, the present invention provides a method of direct air capture of carbon dioxide from an air stream, the method comprising: providing a module or a system as hereinbefore described; and passing an air stream through the apparatus or system.

[0023] Viewed from another aspect, the present invention provides use of a module or system as hereinbefore described for the direct air capture (DAC) of carbon dioxide from an air stream.

[0024] Viewed from another aspect, the present invention provides a method for the direct air capture of carbon dioxide from an air stream, the method comprising: passing an air stream through a humidifying section, wherein the humidifying section increases the humidity of the air stream to provide a humidified air stream; and passing the humidified air stream through an absorber section, wherein the humidified air stream is contacted with a sorbent and at least a portion of the carbon dioxide is thereby removed from the humidified air stream.

[0025] Viewed from another aspect, the present invention provides a method for the direct air capture of carbon dioxide from an air stream, the method comprising: passing an air stream through a humidifying section, wherein the humidifying section increases the humidity of the air stream to provide a humidified air stream having a humidity of between 70 to 97.5 %; and

[0026] 38265848-2 passing the humidified air stream through an absorber section, wherein the humidified air stream is contacted with a sorbent and at least a portion of the carbon dioxide is thereby removed from the humidified air stream, wherein the sorbent comprises one or more amino acid salts.

[0027] Viewed from another aspect, the present invention provides a method for the direct air capture of carbon dioxide from an air stream, the method comprising: passing an air stream through a humidifying section, wherein the humidifying section increases the humidity of the air stream and cools the air stream to provide a humidified air stream; and passing the humidified air stream through an absorber section, wherein the humidified air stream is contacted with a sorbent and at least a portion of the carbon dioxide is thereby removed from the humidified air stream.

[0028] Viewed from another aspect, the present invention provides a method for the direct air capture of carbon dioxide from an air stream, the method comprising: passing an air stream through a humidifying section, wherein the humidifying section increases the humidity of the air stream and cools the air stream to provide a humidified air stream having a humidity of between 70 to 97.5 %; and passing the humidified air stream through an absorber section, wherein the humidified air stream is contacted with a sorbent and at least a portion of the carbon dioxide is thereby removed from the humidified air stream, wherein the sorbent comprises one or more amino acid salts.

[0029] DEFINITIONS

[0030] As used herein, the term “sorbent” refers to a reagent suitable for capturing carbon dioxide from air.

[0031] As used herein, the term “humidity” refers to relative humidity. Humidity can be increased by decreasing the temperature of an air stream and / or, preferably, by increasing the water content of an air stream. Increasing the water content of an air stream may be desirably less complex, and may have reduced energy and equipment demands, as compared with decreasing the temperature of the air stream. Humidity may, for example, be measured using bulb thermometers (for example wet and dry bulb thermometers) or, preferably, using capacitive sensors.

[0032] As used herein, the term “module” refers to an apparatus with its own independent function, but which may also be suitable for use as a component part of a system.

[0033] 38265848-2 As used herein, taking an illustrative example, an increase in humidity from 50 % to 80 % can be described as an increase in humidity of 30 percentage points.

[0034] DETAILED DESCRIPTION

[0035] The present invention provides a module for use in a direct air capture (DAC) system, the module comprising: a humidifying section, the humidifying section being configured to increase the humidity of an air stream to provide a humidified air stream; and an absorber section located downstream of the humidifying section, the absorber section being configured to contact the humidified air stream with a sorbent and thereby capture at least a portion of the carbon dioxide from the humidified air stream.

[0036] The module of the present invention operates by increasing in a humidifying section the humidity of an air stream from which carbon dioxide is to be captured. This occurs upstream of an absorber section, in which the capture of carbon dioxide is effected by contact of the humidified air stream with a sorbent. Advantageously, the action of the humidifying section reduces evaporative losses from the sorbent in the downstream absorber section. This reduces water demands by better keeping the sorbent at a desired concentration for carbon dioxide capture and avoids fouling of the controlled reaction environment in the absorber section.

[0037] A particularly preferred module of the present invention is a module for use in a direct air capture (DAC) system, the module comprising: a humidifying section, the humidifying section being configured to increase the humidity of an air stream and to cool the air stream to provide a humidified air stream; and an absorber section located downstream of the humidifying section, the absorber section being configured to contact the humidified air stream with a sorbent and thereby capture at least a portion of the carbon dioxide from the humidified air stream.

[0038] Colder air has lower relative humidity and provides less of driving force for evaporative losses from a sorbent. A reduction in temperature is also advantageously associated with improved efficiency of carbon dioxide capture by sorbent in the absorber section: this may be particularly true of certain sorbents, for example when the sorbent includes a compound comprising an amine group, such as wherein the sorbent comprises an amino acid, such as wherein the sorbent comprises one or more amino acid salts. Accordingly, it is particularly preferred that the sorbent includes a compound comprising an amine group, more preferably wherein the sorbent comprises an amino

[0039] 38265848-2 acid, still more preferably wherein the sorbent comprises one or more amino acid salts. Most preferably, the sorbent comprises one or more amino acid salts, preferably wherein the humidity of the humidified air stream is less than 100%.

[0040] The humidifying section preferably comprises humidifying means, preferably wherein the humidifying means are configured to provide contact between water and the air stream. The water is preferably chilled water. As used herein, the term “chilled” refers to water cooled below an ambient temperature. For example, the water may be chilled to about 5 to 20 °C, or about 10 to 15 °C. Preferably, the water is chilled to less than 25, less than 20, less than 15, less than 10, or less than 5 °C. Preferably, the water is chilled to between 0 to 25, 5 to 20, 5 to 15, or 5 to 10 °C. The water may, for example, be chilled to a temperature greater than 0 °C. The water may preferably be chilled to a temperature below that of the air stream provided to the humidifying section. The humidifying section is preferably configured to provide water at these temperatures.

[0041] The module may preferably comprise a cooler for chilling water or, said another way, providing the chilled water. The cooler is preferably configured to provide chilled water at the above-mentioned temperatures. Suitable coolers will be known to those skilled in the art. The cooler may comprise refrigeration means or a heat exchanger. The heat taken from the water may advantageously be provided to a sorbent regeneration unit, where the heat can be usefully applied to separating sorbent from the carbon dioxide captured from the humidified air stream. A sorbent regeneration unit may, together with the module of the present invention, form part of a DAC system.

[0042] Another particularly preferred module of the present invention is a module for use in a direct air capture (DAC) system, the module comprising: a humidifying section, the humidifying section being configured to increase the humidity of an air stream to provide a humidified air stream having a humidity of between 70 to 97.5 %; and an absorber section located downstream of the humidifying section, the absorber section being configured to contact the humidified air stream with a sorbent and thereby capture at least a portion of the carbon dioxide from the humidified air stream, wherein the sorbent comprises one or more amino acid salts.

[0043] Amino acid salts are non-volatile components of a sorbent (e.g. a sorbent solution, e.g. an aqueous sorbent solution). The vapour pressure of sorbent comprising one or more amino acid salts may therefore be lower than a sorbent based on volatile components, such as conventional volatile amines. Vapour pressure of the sorbent (e.g. sorbent solution) may decrease as a function of amino acid concentration, which may be

[0044] 38265848-2 rationalised by considering increased intermolecular force strength between the amino acids and a solvent (e.g. water). Accordingly, a humidified air stream need not have a 100% humidity to reduce evaporation from a sorbent comprising one or more amino acid salts to adequate levels.

[0045] Accordingly, the humidified air stream preferably has a humidity of less than 100 %. The humidified air stream preferably has a humidity of less than 97.5 %. The humidified air stream may preferably have a humidity of less than or equal to 95 %, e.g. less than or equal to 90 %.

[0046] A preferred humidity for the humidified air stream may be between 80 to 97.5 %, more preferably 85 to 97.5 %, still more preferably 85 to 95 %.

[0047] A preferred humidity for the humidified air stream may be between 80 to 97.5 %, more preferably 85 to 97.5 %, still more preferably 90 to 95 %.

[0048] The humidified air stream preferably has a humidity of between 70 to 97.5 %, more preferably 75 to 97.5 %, still more preferably 80 to 97.5 %, still more preferably 85 to 97.5 %, still more preferably 85 to 95 %.

[0049] The humidified air stream preferably has a humidity of between 70 to 97.5 %, more preferably 70 to 95 %, still more preferably 70 to 90 %, still more preferably 75 to 90 %, still more preferably 80 to 90 %.

[0050] The humidified air stream may for example have a humidity of greater than or equal to 70 %, greater than or equal to 75 %, greater than or equal to 80 %, or greater than or equal to 85 %.

[0051] The humidifying section is preferably configured to provide a humidified air stream having the above-mentioned humidity values. The above-mentioned values are particularly preferred when the sorbent comprises one or more non-volatile components, more particularly when the sorbent comprises one or more amino acid salts.

[0052] Preferably, the module comprises a measuring system for measuring the humidity of the humidified air stream yielded by the humidifying section. Preferably, the module further comprises a control unit for adjusting the operation of the humidifying section, based on the measurements from the measuring system to provide said humidity of between 70 to 97.5 % to the humidified air stream. Preferred humidities are discussed above. Example adjustments are discussed below.

[0053] Another particularly preferred module of the present invention is a module for use in a direct air capture (DAC) system, the module comprising:

[0054] 38265848-2 a humidifying section, the humidifying section being configured to increase the humidity of an air stream and to cool the air stream to provide a humidified air stream having a humidity of between 70 to 97.5 %; and an absorber section located downstream of the humidifying section, the absorber section being configured to contact the humidified air stream with a sorbent and thereby capture at least a portion of the carbon dioxide from the humidified air stream, wherein the sorbent comprises one or more amino acid salts.

[0055] Preferred embodiments of the module of the present invention, applying also to the particularly preferred modules already discussed above, will now be described.

[0056] Humidifying section

[0057] The module of the present invention comprises a humidifying section. The humidifying section is configured to increase the humidity of an air stream to provide a humidified air stream. The humidified air stream is subsequently fed to the downstream absorber section. It will be understood that the humidifying section can be considered upstream of the absorber section.

[0058] The driving force for evaporative losses from a sorbent is greater when the sorbent is in contact with an air stream having lower humidity. Providing an air stream to the absorber section having increased humidity therefore reduces the driving force for evaporative losses from the sorbent in the absorber section. Water demands and the build-up of solid impurities in the controlled reaction environment of the absorber section are therefore desirably reduced by provision of the upstream humidifying section.

[0059] The air stream provided to the humidifying section is preferably a stream of atmospheric air. It will be appreciated that the humidity of atmospheric air will vary greatly depending on geographic location and local weather conditions. The module of the present invention is particularly effective when the air stream provided to the humidifying section is of low humidity, which ordinarily provides the greatest driving force for evaporative loss from the sorbent in the absorber section. Low humidities may, for example, be found in desert or other dry environments.

[0060] The air stream provided to the humidifying section preferably has a humidity of less than 100 %, preferably less than 99 %, more preferably less than 97.5 % more preferably less than 95 %, still more preferably less than 90 %, still more preferably less than 80 %, still more preferably less than 75 %, still more preferably less than 70 %, still more preferably less than 60 %, still more preferably less than 50 %. For example, the air stream provided to the humidifying section may have a humidity of less than 40 %,

[0061] 38265848-2 less than 30 %, less than 20 %, or less than 10 %. The air stream provided to the humidifying section may, for example, have a humidity of greater than 0 %, greater than 10 %, or greater than 20 %.

[0062] The humidifying section is configured to increase the humidity of an air stream to provide a humidified air stream. It will be understood that an air stream entering the humidifying section will therefore have a lower humidity than the humidified air stream exiting the humidifying section. Preferably the humidity of the air stream is increased by at least 5 percentage points, more preferably by at least 10 percentage points, still more preferably by at least 20 percentage points, still more preferably by at least 30 percentage points, still more preferably by at least 40 percentage points. It will be appreciated that the amount of increase will depend on the humidity of the air stream provided to the humidifying section and the desired humidity of the humidified air stream (which may, for example, be related to a desired sorbent concentration in the absorber section). Operational adjustments can be made to the module to achieve a desired increase in humidity.

[0063] The humidified air stream preferably has a humidity greater than the humidity of ambient atmospheric air in the location in which the module is situated.

[0064] The humidified air stream provided by the humidifying section preferably has a humidity of greater than 80 %, more preferably greater than 90 %, still more preferably greater than 95 %, still more preferably greater than 98 %, still more preferably greater than 99 %, e.g. about 100 %. A preferred humidity for the humidified air stream may be between 80 to 100 %, more preferably 90 to 100 %, still more preferably 95 to 100 %, still more preferably than 98 to 100 %, still more preferably 99 to 100 %. A preferred humidity for the humidified air stream may be between 80 to 100 %, more preferably 85 to 97.5 %, still more preferably 90 to 95 %.

[0065] In some cases, it may be preferable to provide a humidity of less than 100 %, for example to better match the vapour pressure of a sorbent. By way of illustration, a contrast is drawn between sorbents comprising non-volatile components (for example a sorbent comprising one or more amino acid salts) and sorbents comprising volatile components (for example a sorbent comprising conventional volatile amines). The sorbent comprising one or more amino acid salts will have a lower vapour pressure than a sorbent comprising a conventional volatile amine. Accordingly, a humidified air stream need not have so high a humidity to reduce evaporation from the sorbent comprising one or more amino acid salts to adequate levels. Vapour pressure of the sorbent (e.g. sorbent solution) may decrease as a function of amino acid concentration, which may be

[0066] 38265848-2 rationalised by considering increased intermolecular force strength between the amino acids and the solvent (e.g. water).

[0067] Accordingly, the humidified air stream preferably has a humidity of less than 100 %. The humidified air stream preferably has a humidity of less than 97.5 %. The humidified air stream may preferably have a humidity of less than or equal to 95 %, e.g. less than or equal to 90 %.

[0068] A preferred humidity for the humidified air stream may be between 80 to 97.5 %, more preferably 85 to 97.5 %, still more preferably 85 to 95 %.

[0069] A preferred humidity for the humidified air stream may be between 80 to 97.5 %, more preferably 85 to 97.5 %, still more preferably 90 to 95 %.

[0070] The humidified air stream preferably has a humidity of between 70 to 97.5 %, more preferably 75 to 97.5 %, still more preferably 80 to 97.5 %, still more preferably 85 to 97.5 %, still more preferably 85 to 95 %.

[0071] The humidified air stream preferably has a humidity of between 70 to 97.5 %, more preferably 70 to 95 %, still more preferably 70 to 90 %, still more preferably 75 to 90 %, still more preferably 80 to 90 %.

[0072] The humidified air stream may for example have a humidity of greater than or equal to 70 %, greater than or equal to 75 %, greater than or equal to 80 %, or greater than or equal to 85 %.

[0073] As noted already, in a particularly preferred embodiment, the humidified air stream has a humidity of 70 to 97.5 %, while the sorbent comprises one or more amino acid salts.

[0074] The humidifying section is preferably configured to provide a humidified air stream having the above-mentioned humidity values. The above-mentioned values are particularly preferred when the sorbent comprises one or more non-volatile component, more particularly when the sorbent comprises one or more amino acid salts.

[0075] The humidifying section preferably comprises humidifying means. It will be understood that humidifying means are configured to increase the humidity of the air stream to provide the humidified air stream.

[0076] The humidifying means may be configured to cool the air stream. Colder air has lower relative humidity and provides less of driving force for evaporative losses from a sorbent. Such humidifying means may comprise refrigeration means. Humidifying means may be configured according to a system described in WO / 2024 / 126356 or similar. The humidifying means is preferably not configured to warm the air stream

[0077] 38265848-2 The humidifying means are preferably configured to provide water, more preferably to provide contact between water and the air stream. Contact may preferably be by intercepting the air stream with water, or may be by providing a water-air interface. The greater the area of contact between a source of water and an air stream, the greater the increase of humidity to the air stream. The humidifying means are therefore preferably selected so as to provide a large area of contact between water and the air stream.

[0078] Accordingly, the humidifying section is preferably configured to provide water to the air stream, and more preferably is configured to contact the air stream with water. Contact may preferably be by intercepting the air stream with water, or may be by providing a water-air interface.

[0079] It will be appreciated that preferred humidifying means will consume water. However, if water is to be lost somewhere in the system, it is better to be from a standard water supply used in the upstream humidifying section than from the sorbent in the absorber section. This is because water lost from the absorbent requires top-up, and any top-up water generally needs to be of high purity to prevent build-up of solids from the evaporating water in the controlled reaction environment of the absorber section. Solids building up in the upstream humidifying section are easily accessible for cleaning, and is less problematic than build up in the controlled reaction environment of the absorber section.

[0080] Example humidifying means are discussed below, which may be used alone or in combination.

[0081] The humidifying means may preferably comprise means for providing a water spray. Such a water spray will contact the air stream over a large surface area, increasing the humidity of the air stream. Additionally or alternatively, the humidifying means may comprise means for providing a rain wash, which can again contact the air stream, increasing the humidity of the air stream.

[0082] Rain washes are differentiated from water sprays by having generally larger droplet sizes. In other words, water sprays have finer droplet sizes. Nozzles configured to produce water sprays will generally operate at lower pressures than nozzles configured to produce rain washes.

[0083] Compared to rain washes, water sprays may be more suitable for humidifying sections having smaller volume and / or for humidifying sections which are upstream of a single absorber section. Compared to water sprays, rain washes may be more suitable

[0084] 38265848-2 for humidifying sections having larger volume and / or for humidifying sections which are upstream of a plurality of absorber sections.

[0085] The humidifying means may preferably comprise a water nozzle. The water nozzle may, for example, be configured to provide a water spray or a rain wash.

[0086] Water sprays and / or rain washes will advantageously act to at least partially clean the incoming air of airborne impurities and particulates. Impurities may include solid deposits, contaminants, airborne particles, insects, and similar. This means that the humidified air stream is cleaner than the initial air stream, avoiding contamination of the controlled reaction environment in the downstream absorber section. Any impurities thus collected in the upstream humidifying section are more easily dealt with, as the upstream section is more accessible for cleaning.

[0087] The air stream may also comprise gaseous pollutants, such as ozone, NOx, SOx, methane. Such pollutants, e.g. ozone, NOx, SOx, may advantageously be absorbed by the water droplets, which may reduce their effect on degradation of sorbent in the absorber section.

[0088] The humidifying means may comprise layers of open packing, configured for the dripping of water through the layers. The air stream passing through such packing may experience a large area of contact with the water, increasing the humidity of the air stream.

[0089] The humidifying means may comprise one or more water sheets, preferably vertical water sheets. A water sheet may be a 2D film of water, or a pseudo-2D film of water created by a line of adjacent water drips. Water sheets can provide a water-air interface over a large planar area. Evaporation of water from the one or more water sheets into the air stream at this interface will increase the humidity of the air stream. The one or more water sheets may be aligned with or may be angled to the flow direction of the air stream. Water sheets may be able to channel an air stream, meaning a plurality of water sheets can be arranged in a zig-zag configuration to afford the air flow a zig-zag path with more effective evaporation area.

[0090] The humidifying means may comprise one or more trays of standing or moving, e.g. gently moving, water. Such means can provide a water-air interface over a large planar area. Evaporation of water from the one or more trays into the air stream at this interface will increase the humidity of the air stream.

[0091] The humidifying means may comprise wetted material. The material may be in the form of a wall, sheeting, or matting. The material may be a fibrous material (for example blotting paper) or sponge (for example in the form of a sponge wall).

[0092] 38265848-2 Evaporation of water from the wetted material into the air stream will increase the humidity of the air stream.

[0093] The humidifying section may be located proximal to a body of water. Areas proximal to bodies of water have naturally higher levels of ambient humidity. Locating the humidifying section proximal to such a body of water may desirably therefore reduce the extent to which the humidity of the air stream needs to be increased.

[0094] The humidifying section, more preferably the humidifying means, is preferably connected to a supply of water. It will be understood that the water provided by the water supply can be used to increase the humidity of the air stream.

[0095] The water may be pure water. However, given that the humidifying section is located upstream of the absorber section, the need for pure water is reduced. This is because the water for use in the humidifying section is not intended to be brought into direct contact with the controlled reaction environment of the downstream absorber section, where there is greater need for higher purity conditions. Moreover, water evaporating from the humidifying section and associating with the air stream will be deprived of any solid impurities. For reasons of expense and logistical ease, it may therefore be preferred that the water is not pure water.

[0096] The water may, for example, be mains water, rainwater, or water from a body of water. The body of water may be located proximal to the module. In the present invention, a body of water may for example be a river, lake, or sea or ocean.

[0097] The water may optionally be filtered or desalinated, especially in the case of water from a body of water. This may reduce potential damage to or contamination of the module. The water may alternatively be condensate from an industrial process.

[0098] The water may optionally be provided in the form of ice, though it is preferred that the water is liquid water.

[0099] In addition to reducing evaporative losses from the sorbent in the downstream absorber section, the evaporation of water in the humidifying section also acts to reduce the temperature of the air stream. Such a reduction in temperature is advantageously associated with improved efficiency of carbon dioxide capture by sorbent in the absorber section. It is therefore preferred that the water is not heated. For example, the water is preferably provided at ambient temperature.

[0100] As noted, the water is preferably chilled water. As used herein, the term “chilled” refers to cooling water below an ambient temperature. For example, the water may be chilled to about 5 to 20 °C, or about 10 to 15 °C. Preferably, the water is chilled to less than 25, less than 20, less than 15, less than 10, or less than 5 °C. Preferably, the water

[0101] 38265848-2 is chilled to between 0 to 25, 5 to 20, 5 to 15, or 5 to 10 °C. The water may, for example, be chilled to a temperature greater than 0 °C. The water may preferably be chilled to a temperature below that of the air stream provided to the humidifying section. The humidifying section is preferably configured to provide water at these temperatures.

[0102] As noted, the module may preferably comprise a cooler for chilling water or, said another way, providing chilled water. The cooler is preferably configured to provide chilled water at the above-mentioned temperatures. Suitable coolers will be known to those skilled in the art. The cooler may comprise refrigeration means or a heat exchanger. The heat taken from the water may advantageously be provided to a sorbent regeneration unit, where the heat can be usefully applied to separating sorbent from the carbon dioxide captured from the humidified air stream. A sorbent regeneration unit may, together with the module of the present invention, form part of a DAC system.

[0103] The temperature of the humidified air stream is preferably lower than the temperature of the air stream provided to the humidifying section. For example, the temperature of the humidified air stream is preferably less than ambient temperature. For example, the temperature of the humidified air stream is preferably 5 to 20 °C, or about 10 to 15 °C. Preferably, the temperature of the humidified air stream is less than 25, less than 20, less than 15, less than 10, or less than 5 °C. Preferably, the temperature of the humidified air stream is between 0 to 25, 5 to 20, 5 to 15, or 5 to 10 °C. The temperature of the humidified air stream may, for example, be a temperature greater than 0 °C.

[0104] The temperature of the humidified air stream may preferably be at least 1 , at least 2, at least 5, or at least 10 °C lower than the temperature of the air stream provided to the humidifying section.

[0105] Reducing the temperature of an air stream, e.g. by providing chilled water, may be particularly beneficial when handling warmer air streams, which might otherwise comprise the efficiency of carbon dioxide capture using the sorbent. Warm air streams may, for example, be encountered in warmer climates, such as desert environments. For example, the present invention may preferably be applied to air streams having a temperature of greater than 5, 10, 15, 20, 25, 30, or 35 °C.

[0106] The humidifying section preferably does not (e.g. is not configured to) increase the temperature of the air stream. Preferably, the humidifying section does not (e.g. is not configured to) provide warmed water (i.e. water above ambient temperature). Preferably, the humidifying section does not comprise heating means.

[0107] 38265848-2 The water may optionally comprise one or more additives, for example one or more agents for inhibiting bacterial growth, such as growth of Legionella. This may advantageously reduce contamination of the module. Certain additives may be required by health and safety regulations. Other additives may include antioxidants, preferably configured for the removal of ozone, NOx, SOx, methane and free radicals, which may otherwise degrade sorbent in the absorber section. Example antioxidants include ascorbic acid, tocopherol, and similar.

[0108] The humidifying section preferably comprises packing for capturing water droplets from the humidified air stream. As noted, water provided in the humidifying section may be of lower purity than that used in the absorber section. Providing packing may therefore be desirable to prevent this lower purity water contaminating the controlled reaction environment in the absorber section. Capturing the water droplets from the humidified air stream also reduces dilution of the sorbent in the absorber section, for example on contact of the water droplets with sorbent packing. Such a dilution might negatively affect the desired level of carbon dioxide capture.

[0109] The humidifying means may provide water in excess of that required to provide a desired level of humidity to the humidified air stream. For example, if the air stream becomes saturated, some water from, for example, a water spray may not fully associate with the air stream, and might instead pool at the base of the humidifying section.

[0110] Accordingly, the humidifying section preferably comprises a liquid collector for collecting excess water from the humidifying means. When packing is present, as described above, the liquid collector is preferably configured to capture water droplets from the packing. The liquid collector is preferably configured to collect excess water derived from the humidifying means and / or captured by the packing.

[0111] The liquid collector may, for example, comprise a tray or a plurality of trays. The liquid collector may preferably be located at the base of the humidifying section (as judged with respect to the direction of gravity).

[0112] Liquid, e.g. water, collected by the liquid collector may be disposed of - for example released to the environment, such as to a body of water - and / or may be put to use in the DAC process of which the module forms a part - e.g. by recycling to the humidifying means. Preferably, the humidifying section comprises a recycling system for recycling water from the liquid collector to the humidifying means. The recycling is of at least a portion of the water from the liquid collector. Advantageously, water throughput losses are thereby reduced.

[0113] 38265848-2 In the liquid collector, certain impurities may accumulate over time. This may include matter originally carried by the air stream, or it may include impurities present in water supplied by the humidifying section. Impurities may include solid deposits, contaminants, airborne particles, insects, and similar.

[0114] The humidifying section therefore preferably comprises a purification system for treating the water from the liquid collector. A purification desirably improves the quality of the water either prior to disposal, prior to further use of the water, or in particular prior to recycling through a recycling system as hereinbefore described.

[0115] The purification system preferably comprises filtering and / or straining means. Preferred filtering or straining means include wire mesh filters, strainer filters, fine filters, cyclone filters, and / or settling or sedimentation tanks.

[0116] For example, the purification system may preferably comprise a settling tank configured for the collection of solid sediment. Some sediment may gather at the base of the tank, while other sediment may float and can be collected by surface filtration or mechanical means, for example by surface skimming or similar.

[0117] In one embodiment, the humidifying section may comprise a water supply from a body of water, for example a river. The humidifying section may provide the water from the body of water to the air stream via humidifying means, such as a nozzle configured to provide a water spray. Excess water may then be returned to the body of water, preferably without recycling, subsequent to collection in a liquid collector. This provides a simple and efficient way of using fresh untreated water, from a body of water which may be located proximal to the humidifying section. As the humidifying section is located upstream of the controlled reaction environment of the absorber section, the water need not be of high purity.

[0118] Absorber Section

[0119] The module of the present invention comprises an absorber section. The absorber section is located downstream of the humidifying section and is configured to contact the humidified air stream with a sorbent and thereby capture at least a portion of the carbon dioxide from the humidified air stream. The absorber section can be considered to provide a CO2 depleted air stream. Configurations for absorber sections are known in the art. In the present invention, provision of the absorber section downstream of the humidifying section, such that the absorber section receives a humidified air stream, advantageously reduces evaporative losses from the sorbent.

[0120] 38265848-2 The absorber section preferably comprises one or more contactors for contacting the humidified air stream with a sorbent. The one or more contactors is preferably selected from a sorbent sprayer and / or sorbent packing. More preferably, the absorber section comprises a sorbent sprayer and sorbent packing.

[0121] A sorbent sprayer is preferably configured to produce an aerosol of sorbent, providing a high contact area between the solvent and the humidified air stream for carbon dioxide capture. The sorbent sprayer may be in the form of one or more nozzles configured to provide a sorbent spray.

[0122] Sorbent packing is preferably configured to provide liquid films of sorbent propagated across solid surfaces, such as conventional structured packing and / or film fill.

[0123] The sorbent is preferably a wet sorbent, more preferably an aqueous sorbent. Said another way, the sorbent is preferably a sorbent solution, more preferably an aqueous sorbent solution. As discussed previously, conventional DAC systems are vulnerable to evaporative losses from the sorbent. This problem is addressed by the present invention through provision of an upstream humidifying section.

[0124] The sorbent may be any sorbent suitable for carbon capture, in particular DAC. The sorbent may have a changing equilibrium between a carbonate form and being in solution with CO2 that depends on temperature. The sorbent may preferably be carried in a solvent, for example, water, which may contain further additives that can function as catalysts, modify the solution physical properties, and / or reduce degradation or other desirable properties. The sorbent may include alkaline sorbents such as hydroxides or organic sorbents. Alkaline sorbents may include, for example, potassium hydroxide or calcium hydroxide. Organic sorbents may include, for example, amines and amino acids. Amines may include, for example, ethanolamine. Preferred sorbents may include, for example, amino acids or alkali salt solutions of amino acids. The amino acids may be selected from the group consisting of alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, histidine, isoleucine, leucine, lysine, methionine, ornithine, phenylalanine, proline, sarcosine, selenocysteine, serine, taurine, threonine, tryptophan, tyrosine, or valine. Suitable derivatives of amino acids include, e.g. methyl amine or diethyl amine. Preferred alkali salts of amino acid salts include potassium or sodium.

[0125] It is particularly preferred that the sorbent includes a compound comprising an amine group, more preferably wherein the sorbent comprises an amino acid, still more

[0126] 38265848-2 preferably wherein the sorbent comprises an amino acid salt. Most preferably, the sorbent comprises one or more amino acid salts.

[0127] It is preferred that the sorbent comprises one or more non-volatile components. It is preferred that the sorbent comprises one or more amino acid salts.

[0128] Amino acid salts present particular challenges when used as a sorbent, or as part of a sorbent (e.g. a sorbent solution). Following evaporative losses (e.g. of water) from a sorbent, amino acid salts have a tendency to precipitate. This may lead to damage in an absorber section, for example fouling of sorbent packing or blockage of sorbent processing lines. Following large amounts of evaporation, the salts may crystalise, which creates the risk of a positive feedback loop where crystal growth occurs as a result of new liquid covering the crystals and drying out forming new crystal growth on top. This may lead to progressive damage - e.g. fouling and blocking - in the absorber section. Accordingly, there is a particular need when using amino acid salts to manage evaporative losses from a sorbent. As discussed elsewhere, a lower vapour pressure provided by sorbents comprising one or more amino acid salts may make it beneficial to provide a humidified air stream having a humidity of less than 100 %, while still being able to reduce evaporative losses from the sorbent.

[0129] Preferably, the sorbent may comprise top-up water. Evaporative losses from sorbent associated with conventional DAC systems leads to the sorbent solution becoming more concentrated than desired over time. Additional top-up water is thus required to maintain water balance and achieve the desired concentration. As discussed, the module of the present invention reduces evaporative losses from the sorbent, by provision of an upstream humidifying section. The need for top-up water is thus desirably reduced. However, in certain operations, for example in particularly arid environments or on days with particularly low ambient atmospheric humidity, some top-up water may still be required.

[0130] The top-up water is preferably a pure form of water. For example, the top-up water is preferably deionised or demineralised water.

[0131] The absorber section preferably comprises a source of sorbent. As noted, it is particularly preferred that the sorbent comprises one or more amino acid salts. Accordingly, the absorber unit preferably comprises a source of sorbent, wherein the sorbent comprises one or more amino acid salts.

[0132] The sorbent is preferably provided at ambient temperature, or cooler than ambient temperature. In other words, the sorbent is preferably not heated or warmed.

[0133] 38265848-2 Humidity control

[0134] The module of the present invention is preferably configured to provide control over the humidity of the humidified air stream.

[0135] Accordingly, the apparatus preferably comprises a measuring system for measuring one or more of: the humidity of the air stream upstream of the humidifying section; a predicted future humidity of the air stream upstream of the humidifying section; the humidity of the humidified air stream yielded by the humidifying section; and / or the sorbent concentration in the absorber section.

[0136] Additionally or alternatively (preferably additionally), the measuring system may be for measuring one or more of: the temperature of the air stream upstream of the humidifying section; the temperature of the humidified air stream yielded by the humidifying section; the temperature of water provided by the humidifying section.

[0137] Additionally or alternatively (preferably additionally), the measuring system may be for measuring one or more of: the temperature of sorbent provided to the absorber section; the temperature of sorbent after contact with the humidified air stream; the concentration of sorbent provided to the absorber section; the concentration of sorbent after contact with the humidified air stream; the flow rate of sorbent provided to the absorber section; the flow rate of sorbent after contact with the humidified air stream.

[0138] Preferably, the measuring system measures the humidity of the air stream upstream of the humidifying section. Preferably, this is a measurement of the ambient air humidity, i.e. the humidity of ambient atmospheric air. Such measurements could also be inputted to the measuring system from, for example, local weather stations. The lower the humidity of the air provided to the module, the greater the driving force for evaporative losses from the sorbent in the absorber section, unless adequate humidification can be provided by the humidifying section. Such a measurement can therefore provide useful information on the increase in humidity which needs to be achieved by the humidifying section. Adjustments to the operating configuration of the module can then be made accordingly.

[0139] Preferably, the measuring system measures a predicted future humidity of the air stream upstream of the humidifying section. Preferably, this is a prediction of the ambient

[0140] 38265848-2 air humidity, i.e. the humidity of ambient atmospheric air. Such predictions could be inputted to the measuring system from, for example, local weather stations. The lower the humidity of the air provided to the module, the greater the driving force for evaporative losses from the sorbent in the absorber section, unless adequate humidification can be provided by the humidifying section. Such a prediction can therefore pre-emptively provide useful information on the increase in humidity which needs to be achieved by the humidifying section. Pre-emptive adjustments to the operating configuration of the module can then be made accordingly.

[0141] Preferably, the measuring system measures the humidity of the humidified air stream yielded by the humidifying section. This can provide useful information on how effective the current operating configuration of the humidifying section has been at increasing the humidity of the air stream. Adjustments to the operating configuration of the module can then be made accordingly.

[0142] Preferably, the measuring system measures the sorbent concentration in the absorber section. For example, the sorbent concentration provided by one or more contactors can be measured. This may give useful information on the scale of evaporative losses from the sorbent under the current operating configuration of the module. Adjustments to the operating configuration of the module can then be made accordingly.

[0143] Preferably, the measuring system measures the temperature of the air stream upstream of the humidifying section; the temperature of the humidified air stream yielded by the humidifying section; and / or the temperature of water provided by the humidifying section. This may give useful information on the extent to which the air stream needs to be cooled, e.g. by providing chilled water. Adjustments to the operating configuration of the module, e.g. by adjusting the operation of a cooler for chilling water (e.g. by increasing or decreasing the level of cooling provided), can then be made accordingly.

[0144] Preferably, the apparatus further comprises a control unit for adjusting the operation of module, based on the measurements from the measuring system. The adjustment is preferably made to provide a target humidity to the humidified air stream and / or to provide a target sorbent concentration in the absorber section. Targets may be absolute values, or ranges. The control system may preferably employ active feedback control to maintain the targets.

[0145] Adjusting the operation of the module may preferably be by adjusting the operation of the humidifying section, more preferably by adjusting the operation of humidifying means. For example, adjusting the operation of the humidifying section

[0146] 38265848-2 preferably comprises increasing or decreasing a volume of water supplied by the humidifying means. Adjusting the operation of the humidifying section preferably comprises adjusting the flow rate of water through the humidifying section, preferably through humidifying means. Adjusting the operation of the humidifying section preferably comprises adjusting the total effective surface area of water delivered by the humidifying section, preferably by the humidifying means. Adjusting the operation of the humidifying means may preferably comprise activating or deactivating certain humidifying means, i.e. by adjusting the number of active humidifying means. Adjusting the operation of the humidifying means may preferably comprise increasing or decreasing the degree of contact between water and the air stream in the humidifying section.

[0147] In an illustrative example where the humidifying section comprises humidifying means in the form of nozzles configured to provide a water spray, adjusting the operation may comprise increasing or decreasing the volume of water supplied by each nozzle; increasing or decreasing the surface area of water supplied by each nozzle; increasing or decreasing the flow rate through each nozzle; and / or activating or deactivating certain nozzles.

[0148] As discussed below, the module may comprise a plurality of humidifying sections. Adjusting the operation of the module may comprise deploying a different number of humidifying sections upstream of a single absorber section. For example, when a larger increase in humidity is required, the air stream might be routed through a greater number of upstream humidifying sections before its passage to a given absorber section. Alternatively, a certain number of the humidifying sections upstream of a given absorber section may have their humidifying means newly activated. The integrated effect of all upstream humidifying sections may therefore contribute to a desired humidity of a humidified air stream passed to a given absorber section and / or to a described concentration of sorbent in that given absorber section.

[0149] In a further alternative, the module may comprise a plurality of absorber sections, each having a single upstream humidifying section, which are each independently activatable. During operation, a fraction (e.g. 60 %) of the humidifying sections may be activated such that the average humidity of the air stream passed to the absorbers overall is increased (e.g. from 55 to 85 %). In the event a higher humidity level is required, one or more additional humidifying sections may be activated.

[0150] As noted, the adjustment is preferably made to provide a target humidity to the humidified air stream. The target humidity may depend on the sorbent used. However, a preferred humidity for the humidified air stream may be greater than 80 %, more

[0151] 38265848-2 preferably greater than 90 %, still more preferably greater than 95 %, still more preferably greater than 98 %, still more preferably greater than 99 %, e.g. about 100 %. A preferred humidity for the humidified air stream may be between 80 to 100 %, more preferably 90 to 100 %, still more preferably 95 to 100 %, still more preferably than 98 to 100 %, still more preferably 99 to 100 %. A preferred humidity for the humidified air stream may be between 80 to 100 %, more preferably 85 to 97.5 %, still more preferably 90 to 95 %.

[0152] In some cases, it may be preferable to provide a humidity of less than 100 %, for example to better match the vapour pressure of a sorbent. By way of illustration, a contrast is drawn between sorbents comprising non-volatile components (for example a sorbent comprising one or more amino acid salts) and sorbents comprising volatile components (for example a sorbent comprising conventional volatile amines). The sorbent comprising one or more amino acid salts will have a lower vapour pressure than a sorbent comprising a conventional volatile amine. Accordingly, a humidified air stream need not have so high a humidity to reduce evaporation from the sorbent comprising one or more amino acid salts. Vapour pressure of the sorbent (e.g. sorbent solution) may decrease as a function of amino acid concentration, which may be rationalised by considering increased intermolecular force strength between the amino acids and the solvent (e.g. water).

[0153] Accordingly, the humidified air stream preferably has a humidity of less than 100 %. The humidified air stream preferably has a humidity of less than 97.5 %. The humidified air stream may preferably have a humidity of less than or equal to 95 %, e.g. less than or equal to 90 %.

[0154] A preferred humidity for the humidified air stream may be between 80 to 97.5 %, more preferably 85 to 97.5 %, still more preferably 85 to 95 %.

[0155] A preferred humidity for the humidified air stream may be between 80 to 97.5 %, more preferably 85 to 97.5 %, still more preferably 90 to 95 %.

[0156] The humidified air stream preferably has a humidity of between 70 to 97.5 %, more preferably 75 to 97.5 %, still more preferably 80 to 97.5 %, still more preferably 85 to 97.5 %, still more preferably 85 to 95 %.

[0157] The humidified air stream preferably has a humidity of between 70 to 97.5 %, more preferably 70 to 95 %, still more preferably 70 to 90 %, still more preferably 75 to 90 %, still more preferably 80 to 90 %.

[0158] The humidified air stream may for example have a humidity of greater than or equal to 70 %, greater than or equal to 75 %, greater than or equal to 80 %, or greater than or equal to 85 %.

[0159] 38265848-2 As noted already, in a particularly preferred embodiment, the humidified air stream has a humidity of 70 to 97.5 %, while the sorbent comprises one or more amino acid salts.

[0160] The humidifying section is preferably configured to provide a humidified air stream having the above-mentioned humidity values. The above-mentioned values are particularly preferred when the sorbent comprises one or more non-volatile component, more particularly when the sorbent comprises one or more amino acid salts. As noted, the adjustment is preferably made to provide a target sorbent concentration in the absorber section. For example, this may be a sorbent concentration measured in one or more contactors, for example in each of the one or more contactors. Such a target value will depend on factors such as the sorbent used and the temperature of the absorber section.

[0161] The adjustment is preferably to provide a target temperature of the humidified air stream. This may be achieved by adjusting the operation of a cooler configured to chill water, i.e. by increasing or decreasing the temperature of chilled water provided by the cooler. Preferred temperatures of the humidified air stream may be 5 to 20 °C, or about 10 to 15 °C. Preferably, the temperature of the humidified air stream is less than 25, less than 20, less than 15, less than 10, or less than 5 °C. Preferably, the temperature of the humidified air stream is between 0 to 25, 5 to 20, 5 to 15, or 5 to 10 °C. The temperature of the humidified air stream may, for example, be a temperature greater than 0 °C. The temperature of the humidified air stream is preferably lower than the temperature of the air stream provided to the humidifying section. The temperature of the humidified air stream may preferably be at least 1 , at least 2, at least 5, or at least 10 °C lower than the temperature of the air stream provided to the humidifying section.

[0162] The adjustment is preferably to provide a target temperature of water provided by a humidifying section, e.g. the temperature of chilled water. This may be achieved by adjusting the operation of a cooler configured to chill water, i.e. by increasing or decreasing the temperature of chilled water provided by the cooler. For example, the water may be chilled to about 5 to 20 °C, or about 10 to 15 °C. Preferably, the water is chilled to less than 25, less than 20, less than 15, less than 10, or less than 5 °C. Preferably, the water is chilled to between 0 to 25, 5 to 20, 5 to 15, or 5 to 10 °C. The water may, for example, be chilled to a temperature greater than 0 °C. The water may preferably be chilled to a temperature below that of the air stream provided to the humidifying section.

[0163] 38265848-2 Module Features

[0164] The module may comprise an inlet and an outlet. The inlet may be for an air stream, preferably an ambient air stream. The outlet may be for a CO2 deficient air stream, a product of carbon dioxide capture from the initial air stream provided to the module. The inlet may preferably comprise louvres. The angle of the louvres may be adjustable, such that the inlet can be closed or such that air enters the inlet with adjustable directionality. Louvres can advantageously function to prevent entry of large objects, animals and persons into the module; to smooth air flow and dampen out gusts; to reduce escape of sorbent or liquid from the module; and / or to seal the module under extreme conditions or for shut-down or maintenance. In addition to or as an alternative to louvres, the inlet may also comprise fixed packing or other forms of filter, such as mesh filters.

[0165] The module is preferably configured for the passage of an air stream through the module. The passage of air is preferably between the humidifying section and the absorber section, e.g. from the humidifying section to the absorber section. It will be understood that passing an air stream through the module results in the capturing of at least a portion of the carbon dioxide present in the air stream entering the module. The module can thus be considered to yield a CO2 depleted air stream.

[0166] Natural wind conditions and / or buoyancy effects may result in an air stream passing through the module under ambient conditions. However, the module preferably comprises means of generating an air stream. The means of generating an air stream is preferably a fan. Such a fan may be located upstream or downstream of the absorber section. Such a fan may be located upstream or downstream of the humidifying section.

[0167] The module preferably comprises a source of air, preferably ambient or atmospheric air, preferably downstream of the humidifying section. Preferred humidity is as hereinbefore discussed.

[0168] The module may further comprise a mist eliminator, which is preferably configured to capture sorbent drift and droplets, reducing loss of sorbent. Such a mist eliminator may form part of the absorber section or may be located downstream of the absorber section. In either case, the mist eliminator is preferably located downstream of the one or more contactors when such contactors are present in the absorber section.

[0169] Module Arrangements

[0170] 38265848-2 As has been described, the module of the present invention comprises a humidifying section and an absorber section. The humidifying section and the absorber section are preferably adjacent to one another. In other words, a humidified air stream leaving the humidifying section is preferably passed immediately to the absorber section. Alternatively, the humidifying section and the absorber section may be separated by one or more intermediate sections or by a duct.

[0171] The humidifying section and absorber section may be housed in the same enclosed volume. Alternatively, each may be housed in separate enclosed volumes. For example, each may be housed in its own unit. The absorber section is preferably housed in an absorber unit and the humidifying section is preferably located in an inlet to the absorber unit.

[0172] The module is preferably modular in nature. For example, the humidifying section is preferably configured to be releasably securable to the absorber section, e.g. via releasable securing means. This means that the sections can easily be separated for cleaning. This also permits design flexibility, with the exact configuration of the module then being adaptable to different locations or local humidity levels.

[0173] It will be understood that the module of the present invention comprises at least one humidifying section and at least one absorber section. However, the module may preferably comprise a plurality of absorber sections and / or a plurality of humidifying sections. In such a case, the module can be arranged in a number of different ways.

[0174] When a plurality of a certain section is provided, the plurality of those sections may be arranged in series, optionally separated by one or more intermediate sections or ducts, or in parallel. The plurality of those sections are preferably arranged in parallel, for example stacked on top of one another. Stacking may be, for example, two or more high, three more high, four or more high, five or more high, or higher.

[0175] A plurality of absorber sections may preferably be located downstream of a single humidifying section (an illustrative example is shown in Figure 7). In other words, a single humidifying section may provide a humidified air stream to a plurality of downstream absorber sections. Said another way, the humidified air stream from a single humidifying section may be divided between a plurality of downstream absorber sections. The plurality of downstream absorber sections may, for example, be two or more, three or more, four or more, or five or more absorber sections. The plurality of downstream absorber sections may, for example, be arranged in parallel, for example stacked on top of one another. Stacking may be, for example, two or more high, three more high, four or more high, five or more high, or higher.

[0176] 38265848-2 A single absorber section may preferably receive a humidified air stream from each of a plurality of upstream humidifying sections (an illustrative example is shown in Figure 8). In other words, a plurality of upstream humidifying sections may each provide a humidified air stream to a single shared downstream absorber section. In such a case, the humidified air stream received by the absorber section in question is derived from more than one upstream humidifying sections. The plurality of upstream humidifying sections may, for example, be two or more, three or more, four or more, or five or more humidifying sections. The plurality of upstream humidifying sections may, for example, be arranged in parallel, for example stacked on top of one another. Stacking may be, for example, two or more high, three more high, four or more high, five or more high, or higher.

[0177] Where a plurality of humidifying sections are stacked on top of one another, the plurality of humidifying sections are preferably configured to allow water, for example excess water as hereinbefore discussed, to drip down from an upper section to a lower section. This may be made possible by holes in the base of an upper humidifying section.

[0178] System

[0179] The present invention also provides a kit for assembling a module as hereinbefore described, the kit comprising: an absorber section as hereinbefore described; a a humidifying section as hereinbefore described; and optionally, one or more securing means, preferably releasable securing means, for securing the absorber section to the humidifying section.

[0180] The present invention also provides a direct air capture (DAC) system, the system comprising a module as hereinbefore described.

[0181] In addition to the module as hereinbefore described, the system may comprise one or more further modules. Other modules for use in a DAC system are known in the art. Preferably, the system further comprises a solvent regeneration unit configured to separate sorbent from the carbon dioxide captured from the humidified air stream.

[0182] The present invention provides use of a module as hereinbefore described for the manufacture of a direct air capture (DAC) system. The system may be as hereinbefore described.

[0183] Method

[0184] 38265848-2 The present invention also provides use of a module or system as hereinbefore described for the direct air capture (DAC) of carbon dioxide from an air stream.

[0185] The present invention provides a method of direct air capture of carbon dioxide from an air stream, the method comprising: providing a module or a system as hereinbefore described; and passing an air stream through the apparatus or system.

[0186] It will be understood that the air stream is passed through the humidifying section prior to the passage of the resultant humidified air stream through the downstream absorber section.

[0187] Natural wind conditions and / or buoyancy effects may result in an air stream passing through a module or system under ambient conditions. However, the module or system preferably comprises means of generating an air stream. The method therefore preferably comprises generating an air stream, e.g. between the humidifying section and the absorber section. The means of generating an air stream is preferably a fan. Such a fan may be located upstream or downstream of the absorber section. Such a fan may be located upstream or downstream of the humidifying section.

[0188] The present invention provides a method for the direct air capture of carbon dioxide from an air stream, the method comprising: passing an air stream through a humidifying section, wherein the humidifying section increases the humidity of the air stream to provide a humidified air stream; and passing the humidified air stream through an absorber section, wherein the humidified air stream is contacted with a sorbent and at least a portion of the carbon dioxide is thereby removed from the humidified air stream.

[0189] The method is preferably performed using a module or system as hereinbefore described.

[0190] The method of the present invention operates by increasing in a humidifying section the humidity of an air stream from which carbon dioxide is to be captured. This occurs prior to passage of the humidified air stream through an absorber section, in which the capture of carbon dioxide is effected by contact of the humidified air stream with a sorbent. Advantageously, the action of the humidifying section reduces evaporative losses from the sorbent in the downstream absorber section. This reduces water demands by better keeping the sorbent at a desired concentration for carbon dioxide capture and avoids fouling of the controlled reaction environment in the absorber section.

[0191] 38265848-2 A particularly preferred method of the present invention is a method for the direct air capture of carbon dioxide from an air stream, the method comprising: passing an air stream through a humidifying section, wherein the humidifying section increases the humidity of the air stream and cools the air stream to provide a humidified air stream; and passing the humidified air stream through an absorber section, wherein the humidified air stream is contacted with a sorbent and at least a portion of the carbon dioxide is thereby removed from the humidified air stream.

[0192] Colder air has lower relative humidity and provides less of driving force for evaporative losses from a sorbent. A reduction in temperature is also advantageously associated with improved efficiency of carbon dioxide capture by sorbent in the absorber section: this may be particularly true of certain sorbents, for example when the sorbent includes a compound comprising an amine group, such as wherein the sorbent comprises an amino acid, such as wherein the sorbent comprises one or more amino acid salts. Accordingly, it is particularly preferred that the sorbent includes a compound comprising an amine group, more preferably wherein the sorbent comprises an amino acid, still more preferably wherein the sorbent comprises one or more amino acid salts. Most preferably, the sorbent comprises one or more amino acid salts, preferably wherein the humidity of the humidified air stream is less than 100%.

[0193] The humidifying section preferably comprises humidifying means, preferably wherein the humidifying means are configured to provide contact between water and the air stream. In other words, the method preferably comprises contacting the air stream with water in the humidifying section. The water is preferably chilled water. As used herein, the term “chilled” refers to water cooled below an ambient temperature. For example, the water may be chilled to about 5 to 20 °C, or about 10 to 15 °C. Preferably, the water is chilled to less than 25, less than 20, less than 15, less than 10, or less than 5 °C. Preferably, the water is chilled to between 0 to 25, 5 to 20, 5 to 15, or 5 to 10 °C. The water may, for example, be chilled to a temperature greater than 0 °C. The water may preferably be chilled to a temperature below that of the air stream provided to the humidifying section. The humidifying section is preferably configured to provide water at these temperatures. The method preferably comprises chilling water to these temperatures.

[0194] The module may preferably comprise a cooler for chilling water or, said another way, providing the chilled water. The cooler is preferably configured to provide chilled water at the above-mentioned temperatures. Suitable coolers will be known to those

[0195] 38265848-2 skilled in the art. The cooler may comprise refrigeration means or a heat exchanger. The heat taken from the water may advantageously be provided to a sorbent regeneration unit, where the heat can be usefully applied to separating sorbent from the carbon dioxide captured from the humidified air stream. A sorbent regeneration unit may, together with the module of the present invention, form part of a DAC system.

[0196] Another particularly preferred method of the present invention is a method for the direct air capture of carbon dioxide from an air stream, the method comprising: passing an air stream through a humidifying section, wherein the humidifying section increases the humidity of the air stream to provide a humidified air stream having a humidity of between 70 to 97.5 %; and passing the humidified air stream through an absorber section, wherein the humidified air stream is contacted with a sorbent and at least a portion of the carbon dioxide is thereby removed from the humidified air stream, wherein the sorbent comprises one or more amino acid salts.

[0197] Amino acid salts are non-volatile components of a sorbent (e.g. a sorbent solution, e.g. an aqueous sorbent solution). The vapour pressure of sorbent comprising one or more amino acid salts may therefore be lower than a sorbent based on volatile components, such as conventional volatile amines. Vapour pressure of the sorbent (e.g. sorbent solution) may decrease as a function of amino acid concentration, which may be rationalised by considering increased intermolecular force strength between the amino acids and a solvent (e.g. water). Accordingly, a humidified air stream need not have a 100% humidity to reduce evaporation from a sorbent comprising one or more amino acid salts to adequate levels.

[0198] Accordingly, the humidified air stream preferably has a humidity of less than 100 %. The humidified air stream preferably has a humidity of less than 97.5 %. The humidified air stream may preferably have a humidity of less than or equal to 95 %, e.g. less than or equal to 90 %.

[0199] A preferred humidity for the humidified air stream may be between 80 to 97.5 %, more preferably 85 to 97.5 %, still more preferably 85 to 95 %.

[0200] A preferred humidity for the humidified air stream may be between 80 to 97.5 %, more preferably 85 to 97.5 %, still more preferably 90 to 95 %.

[0201] The humidified air stream preferably has a humidity of between 70 to 97.5 %, more preferably 75 to 97.5 %, still more preferably 80 to 97.5 %, still more preferably 85 to 97.5 %, still more preferably 85 to 95 %.

[0202] 38265848-2 The humidified air stream preferably has a humidity of between 70 to 97.5 %, more preferably 70 to 95 %, still more preferably 70 to 90 %, still more preferably 75 to 90 %, still more preferably 80 to 90 %.

[0203] The humidified air stream may for example have a humidity of greater than or equal to 70 %, greater than or equal to 75 %, greater than or equal to 80 %, or greater than or equal to 85 %.

[0204] The humidifying section is preferably configured to provide a humidified air stream having the above-mentioned humidity values. The method is preferably operated, e.g. the humidifying section is preferably operated, to provide the above-mentioned humidity values, The above-mentioned values are particularly preferred when the sorbent comprises one or more non-volatile component, more particularly when the sorbent comprises one or more amino acid salts.

[0205] Preferably, the method comprises measuring (e.g. using a measuring system) the humidity of the humidified air stream yielded by the humidifying section. Preferably, the module further adjusting (e.g. using a control system) the operation of the humidifying section, based on the measurements from the measuring system to provide said humidity of between 70 to 97.5 % to the humidified air stream. Preferred humidities are discussed above. Example adjustments are discussed below.

[0206] Another particularly preferred method of the present invention is a method for the direct air capture of carbon dioxide from an air stream, the method comprising: passing an air stream through a humidifying section, wherein the humidifying section increases the humidity of the air stream and cools the air stream to provide a humidified air stream having a humidity of between 70 to 97.5 %; and passing the humidified air stream through an absorber section, wherein the humidified air stream is contacted with a sorbent and at least a portion of the carbon dioxide is thereby removed from the humidified air stream, wherein the sorbent comprises one or more amino acid salts.

[0207] Preferred embodiments of the method of the present invention, applying also to the particularly preferred methods already discussed above, will now be described.

[0208] Humidifying

[0209] The method of the present invention comprises passing an air stream through a humidifying section. The humidifying section increases the humidity of the air stream to provide a humidified air stream. The humidified air stream is subsequently passed through an absorber section. It will be understood that the humidifying section can be

[0210] 38265848-2 considered upstream of the absorber section, while the absorber section can be considered downstream of the humidifying section.

[0211] The driving force for evaporative losses from a sorbent is greater when the sorbent is in contact with an air stream having lower humidity. Providing an air stream to the absorber section having increased humidity therefore reduces the driving force for evaporative losses from the sorbent in the absorber section. Water demands and the build-up of solid impurities in the absorber section are therefore desirably reduced by provision of the upstream humidifying section.

[0212] The air stream passed through the humidifying section is preferably a stream of atmospheric air. It will be appreciated that the humidity of atmospheric air will vary greatly depending on geographic location and local weather conditions. The method of the present invention is particularly effective when the air stream provided to the humidifying section is of low humidity, which ordinarily provides the greatest driving force for evaporative loss from the sorbent in the absorber section. Low humidities may, for example, be found in desert or other dry environments.

[0213] The air stream provided to the humidifying section preferably has a humidity of less than 100 %, preferably less than 99 %, more preferably less than 97.5 %, more preferably less than 95 %, still more preferably less than 90 %, still more preferably less than 80 %, still more preferably less than 75 %, still more preferably less than 70 %, still more preferably less than 60 %, still more preferably less than 50 %. For example, the air stream provided to the humidifying section may have a humidity of less than 40 %, less than 30 %, less than 20 %, or less than 10 %. The air stream provided to the humidifying section may, for example, have a humidity of greater than 0 %, greater than 10 %, or greater than 20 %.

[0214] The humidifying section is configured to increase the humidity of an air stream to provide a humidified air stream. It will be understood that an air stream entering the humidifying section will therefore have a lower humidity than the humidified air stream exiting the humidifying section. Preferably the humidity of the air stream is increased by at least 5 percentage points, more preferably by at least 10 percentage points, still more preferably by at least 20 percentage points, still more preferably by at least 30 percentage points, still more preferably by at least 40 percentage points. It will be appreciated that the amount of increase will depend on the humidity of the air stream provided to the humidifying section and the desired humidity of the humidified air stream (which may, for example, be related to a desired sorbent concentration in the absorber

[0215] 38265848-2 section). Operational adjustments can be made to the module to achieve a desired increase in humidity.

[0216] The humidified air stream preferably has a humidity greater than the humidity of ambient atmospheric air in the location in which the module is situated.

[0217] The humidified air stream provided by the humidifying section preferably has a humidity of greater than 80 %, more preferably greater than 90 %, still more preferably greater than 95 %, still more preferably greater than 98 %, still more preferably greater than 99 %, e.g. about 100 %. A preferred humidity for the humidified air stream may be between 80 to 100 %, more preferably 90 to 100 %, still more preferably 95 to 100 %, still more preferably than 98 to 100 %, still more preferably 99 to 100 %. A preferred humidity for the humidified air stream may be between 80 to 100 %, more preferably 85 to 97.5 %, still more preferably 90 to 95 %.

[0218] In some cases, it may be preferable to provide a humidity of less than 100 %, for example to better match the vapour pressure of a sorbent. By way of illustration, a contrast is drawn between sorbents comprising non-volatile components (for example a sorbent comprising one or more amino acid salts) and sorbents comprising volatile components (for example a sorbent comprising conventional volatile amines). The sorbent comprising one or more amino acid salts will have a lower vapour pressure than a sorbent comprising a conventional volatile amine. Accordingly, a humidified air stream need not have so high a humidity to reduce evaporation from the sorbent comprising one or more amino acid salts to adequate levels. Vapour pressure of the sorbent (e.g. sorbent solution) may decrease as a function of amino acid concentration, which may be rationalised by considering increased intermolecular force strength between the amino acids and the solvent (e.g. water).

[0219] Accordingly, the humidified air stream preferably has a humidity of less than 100 %. The humidified air stream preferably has a humidity of less than 97.5 %. The humidified air stream may preferably have a humidity of less than or equal to 95 %, e.g. less than or equal to 90 %.

[0220] A preferred humidity for the humidified air stream may be between 80 to 97.5 %, more preferably 85 to 97.5 %, still more preferably 85 to 95 %.

[0221] A preferred humidity for the humidified air stream may be between 80 to 97.5 %, more preferably 85 to 97.5 %, still more preferably 90 to 95 %.

[0222] The humidified air stream preferably has a humidity of between 70 to 97.5 %, more preferably 75 to 97.5 %, still more preferably 80 to 97.5 %, still more preferably 85 to 97.5 %, still more preferably 85 to 95 %.

[0223] 38265848-2 The humidified air stream preferably has a humidity of between 70 to 97.5 %, more preferably 70 to 95 %, still more preferably 70 to 90 %, still more preferably 75 to 90 %, still more preferably 80 to 90 %.

[0224] The humidified air stream may for example have a humidity of greater than or equal to 70 %, greater than or equal to 75 %, greater than or equal to 80 %, or greater than or equal to 85 %.

[0225] As noted already, in a particularly preferred embodiment, the humidified air stream has a humidity of 70 to 97.5 %, while the sorbent comprises one or more amino acid salts.

[0226] The humidifying section is preferably configured to provide a humidified air stream having the above-mentioned humidity values. The above-mentioned values are particularly preferred when the sorbent comprises one or more non-volatile component, more particularly when the sorbent comprises one or more amino acid salts.

[0227] The humidifying section is preferably configured to provide a humidified air stream having the above-mentioned humidity values.

[0228] The humidifying section preferably comprises humidifying means. It will be understood that humidifying means are configured to increase the humidity of the air stream to provide the humidified air stream. The method therefore preferably comprises increasing the humidity of the air using humidifying means.

[0229] The humidifying means may be configured to cool the air stream. The method may therefore comprise cooling the air stream, e.g. using the humidifying means. Colder air has lower relative humidity and provides less of driving force for evaporative losses from a sorbent. Such humidifying means may comprise refrigeration means. Humidifying means may be configured according to a system described in WO / 2024 / 126356 or similar. The humidifying means is preferably not configured to warm the air stream. The air stream is preferably not warmed or heated.

[0230] However, the humidifying means are preferably configured to provide water, more preferably to provide contact between water and the air stream. The method therefore preferably comprises contacting the air stream with water, e.g. using humidifying means. Contact may preferably be by intercepting the air stream with water, or may be by providing a water-air interface. The greater the area of contact between a source of water and an air stream, the greater the increase of humidity to the air stream. The humidifying means are therefore preferably selected so as to provide a large area of contact between water and the air stream.

[0231] 38265848-2 Accordingly, the humidifying section preferably provides water to the air stream, and more preferably contacts the air stream with water. Contact may preferably be by intercepting the air stream with water, or may be by providing a water-air interface.

[0232] It will be appreciated that preferred humidifying means will consume water. However, if water is to be lost somewhere in the system, it is better to be from a standard water supply used in the upstream humidifying section than from the sorbent in the absorber section. This is because water lost from the absorbent requires top-up, and any top-up water generally needs to be of high purity to prevent build-up of solids from the evaporating water in the controlled reaction environment of the absorber section. Solids building up in the upstream humidifying section are easily accessible for cleaning, and is less problematic than build up in the controlled reaction environment of the absorber section.

[0233] Example humidifying means are discussed below, which may be used alone or in combination.

[0234] The humidifying means may preferably comprise means for providing a water spray. The method may therefore comprise subjecting the air stream to a water spray. Such a water spray will contact the air stream over a large surface area, increasing the humidity of the air stream. Additionally or alternatively, the humidifying means may comprise means for providing a rain wash, which can again contact the air stream, increasing the humidity of the air stream. The method may therefore comprise subjecting the air stream to a rain wash.

[0235] Rain washes are differentiated from water sprays by having generally larger droplet sizes. In other words, water sprays have finer droplet sizes. Nozzles configured to produce water sprays will generally operate at lower pressures than nozzles configured to produce rain washes.

[0236] Compared to rain washes, water sprays may be more suitable for humidifying sections having smaller volume and / or for humidifying sections which are upstream of a single absorber section. Compared to water sprays, rain washes may be more suitable for humidifying sections having larger volume and / or for humidifying sections which are upstream of a plurality of absorber sections.

[0237] The humidifying means may preferably comprise a water nozzle. The water nozzle may, for example, be configured to provide a water spray or a rain wash. The method may therefore comprise applying water from a water nozzle to the air stream, preferably in the form of a water spray or a rain wash.

[0238] 38265848-2 Water sprays and / or rain washes will advantageously act to at least partially clean the incoming air of airborne impurities and particulates. Impurities may include solid deposits, contaminants, airborne particles, insects, and similar. This means that the humidified air stream is cleaner than the initial air stream, avoiding contamination of the controlled reaction environment in the downstream absorber section. Any impurities thus collected in the upstream humidifying section are more easily dealt with, as the upstream section is more accessible for cleaning.

[0239] The air stream may also comprise gaseous pollutants, such as ozone, NOx, SOx, methane. Such pollutants, e.g. ozone, NOx, SOx, may advantageously be absorbed by the water droplets, which may reduce their effect on degradation of sorbent in the absorber section.

[0240] The humidifying means may comprise layers of open packing, configured for the dripping of water through the layers. The air stream passing through such packing may experience a large area of contact with the water, increasing the humidity of the air stream. The method therefore preferably comprises passing the air stream over layers of open packing, configured for the dripping of water through the layers.

[0241] The humidifying means may comprise one or more water sheets, preferably vertical water sheets. A water sheet may be a 2D film of water, or a pseudo-2D film of water created by a line of adjacent water drips. Water sheets can provide a water-air interface over a large planar area. Evaporation of water from the one or more water sheets into the air stream at this interface will increase the humidity of the air stream. The one or more water sheets may be aligned with or may be angled to the flow direction of the air stream. The method may therefore comprise passing the air stream over or between one or more water sheets. Water sheets may be able to channel an air stream, meaning a plurality of water sheets can be arranged in a zig-zag configuration to afford the air flow a zig-zag path with more effective evaporation area.

[0242] The humidifying means may comprise one or more trays of standing or moving, e.g. gently moving, water. Such means can provide a water-air interface over a large planar area. Evaporation of water from the one or more trays into the air stream at this interface will increase the humidity of the air stream. The method may therefore comprise passing the air stream over or between one or more trays of standing or moving, e.g. gently moving, water.

[0243] The humidifying means may comprise wetted material. The material may be in the form of a wall, sheeting, or matting. The material may be a fibrous material (for example blotting paper) or sponge (for example in the form of a sponge wall).

[0244] 38265848-2 Evaporation of water from the wetted material into the air stream will increase the humidity of the air stream. The method may therefore comprise passing the air stream over wetted material.

[0245] The humidifying section may be located proximal to a body of water. Areas proximal to bodies of water have naturally higher levels of ambient humidity. Locating the humidifying section proximal to such a body of water may desirably therefore reduce the extent to which the humidity of the air stream needs to be increased.

[0246] The humidifying section, more preferably the humidifying means, is preferably connected to a supply of water. It will be understood that the water provided by the water supply can be used to increase the humidity of the air stream.

[0247] The water may be pure water. However, given that the humidifying section is located upstream of the absorber section, the need for pure water is reduced. This is because the water for use in the humidifying section is not intended to be brought into direct contact with the controlled reaction environment of the downstream absorber section, where there is greater need for higher purity conditions. Moreover, water evaporating from the humidifying section and associating with the air stream will be deprived of any solid impurities. For reasons of expense and logistical ease, it may therefore be preferred that the water is not pure water.

[0248] The water may, for example, be mains water, rainwater, or water from a body of water. The body of water may be located proximal to the module. In the present invention, a body of water may for example be a river, lake, or sea or ocean.

[0249] The water may optionally be filtered or desalinated, especially in the case of water from a body of water. This may reduce potential damage to or contamination of the module. The water may alternatively be condensate from an industrial process.

[0250] The water may optionally be provided in the form of ice, though it is preferred that the water is liquid water.

[0251] In addition to reducing evaporative losses from the sorbent in the downstream absorber section, the evaporation of water in the humidifying section also acts to reduce the temperature of the air stream. Such a reduction in temperature is advantageously associated with improved efficiency of carbon dioxide capture by sorbent in the absorber section. It is therefore preferred that the water is not heated. For example, the water is preferably provided at ambient temperature.

[0252] As noted, the water is preferably chilled water. Accordingly, the method may comprise chilling the water. As used herein, the term “chilled” refers to cooling water below an ambient temperature. For example, the water may be chilled to about 5 to 20

[0253] 38265848-2 °C, or about 10 to 15 °C. Preferably, the water is chilled to less than 25, less than 20, less than 15, less than 10, or less than 5 °C. Preferably, the water is chilled to between 0 to 25, 5 to 20, 5 to 15, or 5 to 10 °C. The water may, for example, be chilled to a temperature greater than 0 °C. The water may preferably be chilled to a temperature below that of the air stream provided to the humidifying section. The humidifying section is preferably configured to provide water at these temperatures.

[0254] As noted, the module may preferably comprise a cooler for chilling water or, said another way, providing chilled water. The cooler is preferably configured to provide chilled water at the above-mentioned temperatures. Suitable coolers will be known to those skilled in the art. The cooler may comprise refrigeration means or a heat exchanger. The heat taken from the water may advantageously be provided to a sorbent regeneration unit, where the heat can be usefully applied to separating sorbent from the carbon dioxide captured from the humidified air stream. A sorbent regeneration unit may, together with the module of the present invention, form part of a DAC system.

[0255] The temperature of the humidified air stream is preferably lower than the temperature of the air stream provided to the humidifying section. For example, the temperature of the humidified air stream is preferably less than ambient temperature. For example, the temperature of the humidified air stream is preferably 5 to 20 °C, or about 10 to 15 °C. Preferably, the temperature of the humidified air stream is less than 25, less than 20, less than 15, less than 10, or less than 5 °C. Preferably, the temperature of the humidified air stream is chilled between 0 to 25, 5 to 20, 5 to 15, or 5 to 10 °C. The temperature of the humidified air stream may, for example, be a temperature greater than 0 °C.

[0256] The temperature of the humidified air stream may preferably be at least 1 , at least 2, at least 5, or at least 10 °C lower than the temperature of the air stream provided to the humidifying section.

[0257] Reducing the temperature of an air stream, e.g. by providing chilled water, may be particularly beneficial when handling warmer air streams, which might otherwise comprise the efficiency of carbon dioxide capture using the sorbent. Warm air streams may, for example, be encountered in warmer climates, such as desert environments. For example, the present invention may preferably be applied to air streams having a temperature of greater than 5, 10, 15, 20, 25, 30, or 35 °C.

[0258] The humidifying section preferably does not (e.g. is not configured to) increase the temperature of the air stream. Preferably, the humidifying section does not (e.g. is not configured to) provide warmed water (i.e. water above ambient temperature).

[0259] 38265848-2 Preferably, the humidifying section does not comprise heating means. Preferably, the water is not heated. Preferably, the temperature of the air stream is not increased in other words, the temperature of the humidified air stream is preferably lower than the temperature of the air stream provided to the humidifying section.

[0260] The water may optionally comprise one or more additives, for example one or more agents for inhibiting bacterial growth, such as growth of Legionella. This may advantageously reduce contamination of the module. Certain additives may be required by health and safety regulations. Other additives may include antioxidants, preferably configured for the removal of ozone, NOx, SOx, methane and free radicals, which may otherwise degrade sorbent in the absorber section. Example antioxidants include ascorbic acid, tocopherol, and similar.

[0261] The humidifying section preferably comprises packing for capturing water droplets from the humidified air stream. As noted, water provided in the humidifying section may be of lower purity than that used in the absorber section. Providing packing may therefore be desirable to prevent this lower purity water contaminating the controlled reaction environment in the absorber section. Capturing the water droplets from the humidified air stream also reduces dilution of the sorbent in the absorber section, for example on contact of the water droplets with sorbent packing. Such a dilution might negatively affect the desired level of carbon dioxide capture. The method therefore preferably comprises contacting the humidified air stream with such packing.

[0262] The humidifying means may provide water in excess of that required to provide a desired level of humidity to the humidified air stream. For example, if the air stream becomes saturated, some water from, for example, a water spray may not fully associate with the air stream, and might instead pool at the base of the humidifying section.

[0263] Accordingly, the humidifying section preferably comprises a liquid collector for collecting excess water from the humidifying means. The method preferably comprises collecting excess water from the humidifying means in the liquid collector. When packing is present, as described above, the liquid collector is preferably configured to capture water droplets from the packing. The method thus preferably comprises capturing water droplets from the packing in the liquid collector. The liquid collector is preferably configured to collect excess water derived from the humidifying means and / or captured by the packing. The method thus preferably comprises collecting in the liquid collector excess water derived from the humidifying means and / or captured by the packing.

[0264] 38265848-2 The liquid collector may, for example, comprise a tray or a plurality of trays. The liquid collector may preferably be located at the base of the humidifying section (as judged with respect to the direction of gravity).

[0265] Liquid, e.g. water, collected by the liquid collector may be disposed of - for example released to the environment, such as to a body of water - and / or may be put to use in the DAC process of which the module forms a part - e.g. by recycling to the humidifying means. Preferably, the humidifying section comprises a recycling system for recycling water from the liquid collector to the humidifying means. The method therefore preferably comprises recycling at least a portion of the water from the liquid collector to the humidifying means. The recycling is of at least a portion of the water from the liquid collector. Advantageously, water throughput losses are thereby reduced.

[0266] In the liquid collector, certain impurities may accumulate over time. This may include matter originally carried by the air stream, or it may include impurities present in water supplied by the humidifying section. Impurities may include solid deposits, contaminants, airborne particles, insects, and similar.

[0267] The humidifying section therefore preferably comprises a purification system for treating the water from the liquid collector. The method therefore preferably comprises treating, preferably purifying, water from the liquid collector, preferably using such a purification system. A purification desirably improves the quality of the water either prior to disposal, prior to further use of the water, or in particular prior to recycling through a recycling system as hereinbefore described.

[0268] The purification system preferably comprises filtering and / or straining means. Preferred filtering or straining means include wire mesh filters, strainer filters, fine filters, cyclone filters, and / or settling or sedimentation tanks.

[0269] For example, the purification system may preferably comprise a settling tank configured for the collection of solid sediment. Some sediment may gather at the base of the tank, while other sediment may float and can be collected by surface filtration or mechanical means, for example by surface skimming or similar.

[0270] In one embodiment, the humidifying section may comprise a water supply from a body of water, for example a river. The humidifying section may provide the water from the body of water to the air stream via humidifying means, such as a nozzle configured to provide a water spray. Excess water may then be returned to the body of water, preferably without recycling, subsequent to collection in a liquid collector. This provides a simple and efficient way of using fresh untreated water, from a body of water which may be located proximal to the humidifying section. As the humidifying section is located

[0271] 38265848-2 upstream of the controlled reaction environment of the absorber section, the water need not be of high purity.

[0272] Absorbing

[0273] The method of the present invention comprises passing the humidified air stream through an absorber section. In the absorber section, the humidified air stream is contacted with a sorbent and at least a portion of the carbon dioxide is thereby removed from the humidified air stream. The absorber section can be considered to provide a CO2 depleted air stream. Configurations for absorber sections are known in the art. In the present invention, passage of the air through a humidifying section prior to its passage through the absorber section, such that the absorber section receives a humidified air stream, advantageously reduces evaporative losses from the sorbent.

[0274] The absorber section preferably comprises one or more contactors for contacting the humidified air stream with a sorbent. The method therefore preferably comprises contacting the humidified air stream with the one or more contactors. The one or more contactors is preferably selected from a sorbent sprayer and / or sorbent packing. More preferably, the absorber section comprises a sorbent sprayer and sorbent packing.

[0275] A sorbent sprayer is preferably configured to produce an aerosol of sorbent, providing a high contact area between the solvent and the humidified air stream for carbon dioxide capture. The sorbent sprayer may be in the form of one or more nozzles configured to provide a sorbent spray. The method therefore preferably comprises subjecting the humidified air stream to a sorbent spray, preferably from a nozzle as described.

[0276] Sorbent packing is preferably configured to provide liquid films of sorbent propagated across solid surfaces, such as conventional structured packing and / or film fill. The method therefore preferably comprises contacting the humidified air stream with sorbent packing.

[0277] The sorbent is preferably a wet sorbent, more preferably an aqueous sorbent. Said another way, the sorbent is preferably a sorbent solution, more preferably an aqueous sorbent solution. As discussed previously, conventional DAC systems are vulnerable to evaporative losses from the sorbent. This problem is addressed by passing an air stream through a humidifying section before passage of a humidified air stream through the absorber section.

[0278] The sorbent may be any sorbent suitable for carbon capture, in particular DAC. The sorbent may have a changing equilibrium between a carbonate form and being in

[0279] 38265848-2 solution with CO2 that depends on temperature. The sorbent may preferably be carried in a solvent, for example, water, which may contain further additives that can function as catalysts, modify the solution physical properties, and / or reduce degradation or other desirable properties. The sorbent may include alkaline sorbents such as hydroxides or organic sorbents. Alkaline sorbents may include, for example, potassium hydroxide or calcium hydroxide. Organic sorbents may include, for example, amines and amino acids. Amines may include, for example, ethanolamine. Preferred sorbents may include, for example, amino acids or alkali salt solutions of amino acids. The amino acids may be selected from the group consisting of alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, histidine, isoleucine, leucine, lysine, methionine, ornithine, phenylalanine, proline, sarcosine, selenocysteine, serine, taurine, threonine, tryptophan, tyrosine, or valine. Suitable derivatives of amino acids include, e.g. methyl amine or diethyl amine. Preferred alkali salts of amino acid salts include potassium or sodium.

[0280] It is particularly preferred that the sorbent includes a compound comprising an amine group, more preferably wherein the sorbent comprises an amino acid, still more preferably wherein the sorbent comprises an amino acid salt. Most preferably, the sorbent comprises one or more amino acid salts.

[0281] It is preferred that the sorbent comprises one or more non-volatile components. It is preferred that the sorbent comprises one or more amino acid salts.

[0282] Amino acid salts present particular challenges when used as a sorbent, or as part of a sorbent (e.g. a sorbent solution). Following evaporative losses (e.g. of water) from a sorbent, amino acid salts have a tendency to precipitate. This may lead to damage in an absorber section, for example fouling of sorbent packing or blockage of sorbent processing lines. Following large amounts of evaporation, the salts may crystalise, which creates the risk of a positive feedback loop where crystal growth occurs as a result of new liquid covering the crystals and drying out forming new crystal growth on top. This may lead to progressive damage - e.g. fouling and blocking - in the absorber section. Accordingly, there is a particular need when using amino acid salts to manage evaporative losses from a sorbent. As discussed elsewhere, a lower vapour pressure provided by sorbents comprising one or more amino acid salts may make it beneficial to provide a humidified air stream having a humidity of less than 100 %, while still being able to reduce evaporative losses from the sorbent.

[0283] Preferably, the sorbent may comprise top-up water. The method may preferably comprise supplying top-up water to the sorbent. Evaporative losses from sorbent

[0284] 38265848-2 associated with conventional DAC systems leads to the sorbent solution becoming more concentrated than desired over time. Additional top-up water is thus required to maintain water balance and achieve the desired concentration. As discussed, the module of the present invention reduces evaporative losses from the sorbent, by provision of an upstream humidifying section. The need for top-up water is thus desirably reduced. However, in certain operations, for example in particularly arid environments or on days with particularly low ambient atmospheric humidity, some top-up water may still be required.

[0285] The top-up water is preferably a pure form of water. For example, the top-up water is preferably deionised or demineralised water.

[0286] The absorber section preferably comprises a source of sorbent. As noted, it is particularly preferred that the sorbent comprises one or more amino acid salts. Accordingly, the absorber unit preferably comprises a source of sorbent, wherein the sorbent comprises one or more amino acid salts.

[0287] The sorbent is preferably provided at ambient temperature, or cooler than ambient temperature. In other words, the sorbent is preferably not heated or warmed.

[0288] Humidity control

[0289] The method of the present invention is preferably configured to provide control over the humidity of the humidified air stream.

[0290] Accordingly, the method preferably comprises measuring, e.g. using a measuring system, one or more of: the humidity of the air stream upstream of the humidifying section; a predicted future humidity of the air stream upstream of the humidifying section; the humidity of the humidified air stream yielded by the humidifying section; and / or the sorbent concentration in the absorber section.

[0291] Additionally or alternatively (preferably additionally), the method may comprise measuring (e.g. using a measuring system) one or more of: the temperature of the air stream upstream of the humidifying section; the temperature of the humidified air stream yielded by the humidifying section; the temperature of water provided by the humidifying section.

[0292] Additionally or alternatively (preferably additionally), the method may comprise measuring (e.g. using a measuring system) one or more of: the temperature of sorbent provided to the absorber section;

[0293] 38265848-2 the temperature of sorbent after contact with the humidified air stream; the concentration of sorbent provided to the absorber section; the concentration of sorbent after contact with the humidified air stream; the flow rate of sorbent provided to the absorber section; the flow rate of sorbent after contact with the humidified air stream.

[0294] Preferably, the method comprises measuring the humidity of the air stream upstream of the humidifying section. Preferably, this is a measurement of the ambient air humidity, i.e. the humidity of ambient atmospheric air. Such measurements could also be inputted to the measuring system from, for example, local weather stations. The lower the humidity of the air provided to the method, the greater the driving force for evaporative losses from the sorbent in the absorber section, unless adequate humidification can be provided by the humidifying section. Such a measurement can therefore provide useful information on the increase in humidity which needs to be achieved by the humidifying section. Adjustments to the operating configuration of the method can then be made accordingly.

[0295] Preferably, the method comprises measuring a predicted future humidity of the air stream upstream of the humidifying section. Preferably, this is a prediction of the ambient air humidity, i.e. the humidity of ambient atmospheric air. Such predictions could be inputted to a measuring system from, for example, local weather stations. The lower the humidity of the air provided to the method, the greater the driving force for evaporative losses from the sorbent in the absorber section, unless adequate humidification can be provided by the humidifying section. Such a prediction can therefore pre-emptively provide useful information on the increase in humidity which needs to be achieved by the humidifying section. Pre-emptive adjustments to the operating configuration of the method can then be made accordingly.

[0296] Preferably, the method comprises measuring the humidity of the humidified air stream yielded by the humidifying section. This can provide useful information on how effective the current operating configuration of the humidifying section has been at increasing the humidity of the air stream. Adjustments to the operating configuration of the method can then be made accordingly.

[0297] Preferably, the method comprises measuring the sorbent concentration in the absorber section. For example, the sorbent concentration provided by one or more contactors can be measured. This may give useful information on the scale of evaporative losses from the sorbent under the current operating configuration of the

[0298] 38265848-2 method. Adjustments to the operating configuration of the method can then be made accordingly.

[0299] Preferably, the method comprises measuring (e.g. using a measuring system) the temperature of the air stream upstream of the humidifying section; the temperature of the humidified air stream yielded by the humidifying section; and / or the temperature of water provided by the humidifying section. This may give useful information on the extent to which the air stream needs to be cooled, e.g. by providing chilled water. Adjustments to the operating configuration of the module, e.g. by adjusting the operation of a cooler for chilling water (e.g. by increasing or decreasing the level of cooling provided), can then be made accordingly.

[0300] Preferably, the method comprises adjusting, e.g. using a control unit, the operation of the method, based on the measurements from the measuring system. The adjustment is preferably made to provide a target humidity to the humidified air stream and / or to provide a target sorbent concentration in the absorber section. Targets may be absolute values, or ranges. The method, e.g. the control system, may preferably employ active feedback control to maintain the targets.

[0301] Adjusting the operation of the method may preferably be by adjusting the operation of the humidifying section, more preferably by adjusting the operation of humidifying means. For example, adjusting the operation of the humidifying section preferably comprises increasing or decreasing a volume of water supplied by the humidifying means. Adjusting the operation of the humidifying section preferably comprises adjusting the flow rate of water through the humidifying section, preferably through humidifying means. Adjusting the operation of the humidifying section preferably comprises adjusting the total effective surface area of water delivered by the humidifying section, preferably by the humidifying means. Adjusting the operation of the humidifying means may preferably comprise activating or deactivating certain humidifying means, i.e. by adjusting the number of active humidifying means. Adjusting the operation of the humidifying means may preferably comprise increasing or decreasing the degree of contact between water and the air stream in the humidifying section.

[0302] In an illustrative example where the humidifying section comprises humidifying means in the form of nozzles configured to provide a water spray, adjusting the operation may comprise increasing or decreasing the volume of water supplied by each nozzle; increasing or decreasing the surface area of water supplied by each nozzle; increasing or decreasing the flow rate through each nozzle; and / or activating or deactivating certain nozzles.

[0303] 38265848-2 As discussed below, a plurality of humidifying sections may be provided. Adjusting the operation of the method may comprise deploying a different number of humidifying sections upstream of a single absorber section. For example, when a larger increase in humidity is required, the air stream might be routed through a greater number of upstream humidifying sections before its passage to a given absorber section. Alternatively, a certain number of the humidifying sections upstream of given absorber section may have their humidifying means newly activated. The integrated effect of all upstream humidifying sections may therefore contribute to a desired humidity of a humidified air stream passed to a given absorber section and / or to a described concentration of sorbent in that given absorber section.

[0304] In a further alternative, a plurality of absorber sections may be provided, each having a single upstream humidifying section, which are each independently activatable. During operation, a fraction (e.g. 60 %) of the humidifying sections may be activated such that the average humidity of the air stream passed to the absorbers overall is increased (e.g. from 55 to 85 %). In the event a higher humidity level is required, one or more additional humidifying sections may be activated.

[0305] As noted, the adjustment is preferably made to provide a target humidity to the humidified air stream. The target humidity may depend on the sorbent used. However, a preferred humidity for the humidified air stream may be greater than 80 %, more preferably greater than 90 %, still more preferably greater than 95 %, still more preferably greater than 98 %, still more preferably greater than 99 %, e.g. about 100 %. A preferred humidity for the humidified air stream may be between 80 to 100 %, more preferably 90 to 100 %, still more preferably 95 to 100 %, still more preferably than 98 to 100 %, still more preferably 99 to 100 %. A preferred humidity for the humidified air stream may be between 80 to 100 %, more preferably 85 to 97.5 %, still more preferably 90 to 95 %.

[0306] In some cases, it may be preferable to provide a humidity of less than 100 %, for example to better match the vapour pressure of a sorbent. By way of illustration, a contrast is drawn between sorbents comprising non-volatile components (for example a sorbent comprising one or more amino acid salts) and sorbents comprising volatile components (for example a sorbent comprising conventional volatile amines). The sorbent comprising one or more amino acid salts will have a lower vapour pressure than a sorbent comprising a conventional volatile amine. Accordingly, a humidified air stream need not have so high a humidity to reduce evaporation from the sorbent comprising one or more amino acid salts. Vapour pressure of the sorbent (e.g. sorbent solution) may decrease as a function of amino acid concentration, which may be rationalised by

[0307] 38265848-2 considering increased intermolecular force strength between the amino acids and the solvent (e.g. water).

[0308] Accordingly, the humidified air stream preferably has a humidity of less than 100 %. The humidified air stream preferably has a humidity of less than 97.5 %. The humidified air stream may preferably have a humidity of less than or equal to 95 %, e.g. less than or equal to 90 %.

[0309] A preferred humidity for the humidified air stream may be between 80 to 97.5 %, more preferably 85 to 97.5 %, still more preferably 85 to 95 %.

[0310] A preferred humidity for the humidified air stream may be between 80 to 97.5 %, more preferably 85 to 97.5 %, still more preferably 90 to 95 %.

[0311] The humidified air stream preferably has a humidity of between 70 to 97.5 %, more preferably 75 to 97.5 %, still more preferably 80 to 97.5 %, still more preferably 85 to 97.5 %, still more preferably 85 to 95 %.

[0312] The humidified air stream preferably has a humidity of between 70 to 97.5 %, more preferably 70 to 95 %, still more preferably 70 to 90 %, still more preferably 75 to 90 %, still more preferably 80 to 90 %.

[0313] The humidified air stream may for example have a humidity of greater than or equal to 70 %, greater than or equal to 75 %, greater than or equal to 80 %, or greater than or equal to 85 %.

[0314] As noted already, in a particularly preferred embodiment, the humidified air stream has a humidity of 70 to 97.5 %, while the sorbent comprises one or more amino acid salts.

[0315] The humidifying section is preferably configured to provide a humidified air stream having the above-mentioned humidity values. The method is preferably operated to provide a humified air stream having the above-mentioned humidity values. The above-mentioned values are particularly preferred when the sorbent comprises one or more non-volatile component, more particularly when the sorbent comprises one or more amino acid salts.

[0316] As noted, the adjustment is preferably made to provide a target sorbent concentration in the absorber section. For example, this may be a sorbent concentration measured in one or more contactors, for example in each of the one or more contactors. Such a target value will depend on factors such as the sorbent used and the temperature of the absorber section.

[0317] The adjustment is preferably to provide a target temperature of the humidified air stream. This may be achieved by adjusting the operation of a cooler configured to chill water, i.e.

[0318] 38265848-2 by increasing or decreasing the temperature of chilled water provided by the cooler. Preferred temperatures of the humidified air stream may be 5 to 20 °C, or about 10 to 15 °C. Preferably, the temperature of the humidified air stream is less than 25, less than 20, less than 15, less than 10, or less than 5 °C. Preferably, the temperature of the humidified air stream is chilled between 0 to 25, 5 to 20, 5 to 15, or 5 to 10 °C. The temperature of the humidified air stream may, for example, be a temperature greater than 0 °C. The temperature of the humidified air stream is preferably lower than the temperature of the air stream provided to the humidifying section. The temperature of the humidified air stream may preferably be at least 1 , at least 2, at least 5, or at least 10 °C lower than the temperature of the air stream provided to the humidifying section.

[0319] The adjustment is preferably to provide a target temperature of water provided by a humidifying section, e.g. the temperature of chilled water. This may be achieved by adjusting the operation of a cooler configured to chill water, i.e. by increasing or decreasing the temperature of chilled water provided by the cooler. For example, the water may be chilled to about 5 to 20 °C, or about 10 to 15 °C. Preferably, the water is chilled to less than 25, less than 20, less than 15, less than 10, or less than 5 °C. Preferably, the water is chilled to between 0 to 25, 5 to 20, 5 to 15, or 5 to 10 °C. The water may, for example, be chilled to a temperature greater than 0 °C. The water may preferably be chilled to a temperature below that of the air stream provided to the humidifying section.

[0320] Method steps

[0321] The method preferably comprises passing the air stream between the humidifying section and the absorber section, e.g. from the humidifying section to the absorber section. It will be understood that passing an air stream through the absorber section results in the capturing of at least a portion of the carbon dioxide present in the original air stream. The method can thus be considered to yield a CO2 depleted air stream.

[0322] Natural wind conditions and / or buoyancy effects may result in the natural passage of the air stream through the humidifying section and the absorber section. However, the method preferably comprises generating an air stream, e.g. generating an air stream between the humidifying section and the absorber section. The means of generating an air stream is preferably a fan. Such a fan may be located upstream or downstream of the absorber section. Such a fan may be located upstream or downstream of the humidifying section.

[0323] 38265848-2 The method comprises passing an air stream. The air stream is preferably a stream of air, more preferably ambient or atmospheric air. Preferred humidity is as hereinbefore discussed. It will be appreciated that humidity of ambient or atmospheric air will depend on geographic location and / or local weather conditions.

[0324] Module Arrangements

[0325] The method is preferably conducted using a module, preferably a module as hereinbefore described. The module comprises: a humidifying section, the humidifying section being configured to increase the humidity of an air stream to provide a humidified air stream; and an absorber section located downstream of the humidifying section, the absorber section being configured to contact the humidified air stream with a sorbent and thereby capture at least a portion of the carbon dioxide from the humidified air stream.

[0326] The module may comprise an inlet and an outlet. The inlet may be for an air stream, preferably an ambient air stream. The outlet may be for a CO2 deficient air stream, a product of carbon dioxide capture from the initial air stream provided to the module. The inlet may preferably comprise louvres. The angle of the louvres may be adjustable, such that the inlet can be closed or such that air enters the inlet with adjustable directionality. Louvres can advantageously function to prevent entry of large objects, animals and persons into the module; to smooth air flow and dampen out gusts; to reduce escape of sorbent or liquid from the module; and / or to seal the module under extreme conditions or for shut-down or maintenance. In addition to or as an alternative to louvres, the inlet may also comprise fixed packing or other forms of filter, such as mesh filters.

[0327] The module may further comprise a mist eliminator, which is preferably configured to capture sorbent drift and droplets, reducing loss of sorbent. Such a mist eliminator may form part of the absorber section or may be located downstream of the absorber section. In either case, the mist eliminator is preferably located downstream of the one or more contactors when such contactors are present in the absorber section. The method may therefore comprise contacting a CO2 deficient air stream yielded by the absorber section with a mist eliminator.

[0328] Module Arrangements

[0329] As has been described, the module of the present invention comprises a humidifying section and an absorber section. The humidifying section and the absorber

[0330] 38265848-2 section are preferably adjacent to one another. In other words, a humidified air stream leaving the humidifying section is preferably passed immediately to the absorber section. Alternatively, the humidifying section and the absorber section may be separated by one or more intermediate sections or by a duct.

[0331] The humidifying section and absorber section may be housed in the same enclosed volume. Alternatively, each may be housed in separate enclosed volumes. For example, each may be housed in its own unit. The absorber section is preferably housed in an absorber unit and the humidifying section is preferably located in an inlet to the absorber unit.

[0332] The module is preferably modular in nature. For example, the humidifying section is preferably configured to be releasably securable to the absorber section, e.g. via releasable securing means. This means that the sections can easily be separated for cleaning. This also permits design flexibility, with the exact configuration of the module then being adaptable to different locations or local humidity levels.

[0333] It will be understood that the module of the present invention comprises at least one humidifying section and at least one absorber section. However, the module may preferably comprise a plurality of absorber sections and / or a plurality of humidifying sections. In such a case, the module can be arranged in a number of different ways.

[0334] When a plurality of a certain section is provided, the plurality of those sections may be arranged in series, optionally separated by one or more intermediate sections or ducts, or in parallel. The plurality of those sections are preferably arranged in parallel, for example stacked on top of one another. Stacking may be, for example, two or more high, three more high, four or more high, five or more high, or higher.

[0335] A plurality of absorber sections may preferably be located downstream of a single humidifying section (an illustrative example is shown in Figure 7). The method therefore preferably comprises passing the humidified air stream through a plurality of absorber sections. In other words, a single humidifying section may provide a humidified air stream to a plurality of downstream absorber sections. Said another way, the humidified air stream from a single humidifying section may be divided between a plurality of downstream absorber sections. The plurality of downstream absorber sections may, for example, be two or more, three or more, four or more, or five or more absorber sections. The plurality of downstream absorber sections may, for example, be arranged in parallel, for example stacked on top of one another. Stacking may be, for example, two or more high, three more high, four or more high, five or more high, or higher.

[0336] 38265848-2 A single absorber section may preferably receive a humidified air stream from each of a plurality of upstream humidifying sections (an illustrative example is shown in Figure 8). The method therefore preferably comprises passing an air stream through a plurality of humidifying sections to provide a plurality of humidified air streams. The method may then preferably comprise passing the plurality of humidified air streams through a single absorber section. In other words, a plurality of upstream humidifying sections may each provide a humidified air stream to a single shared downstream absorber section. In such a case, the humidified air stream received by the absorber section in question is derived from more than one upstream humidifying sections. The plurality of upstream humidifying sections may, for example, be two or more, three or more, four or more, or five or more humidifying sections. The plurality of upstream humidifying sections may, for example, be arranged in parallel, for example stacked on top of one another. Stacking may be, for example, two or more high, three more high, four or more high, five or more high, or higher.

[0337] Where a plurality of humidifying sections are stacked on top of one another, the plurality of humidifying sections are preferably configured to allow water, for example excess water as hereinbefore discussed, to drip down from an upper section to a lower section. This may be made possible by holes in the base of an upper humidifying section.

[0338] Preferred modules

[0339] Some preferred modules of the present invention are as described below.

[0340] A module for use in a direct air capture (DAC) system, the module comprising: a humidifying section, the humidifying section comprising humidifying means configured to increase the humidity of an air stream to provide a humidified air stream, preferably wherein the humidifying means are configured to provide contact between water and the air stream; and an absorber section located downstream of the humidifying section, the absorber section comprising one or more contactors for contacting the humidified air stream with a sorbent, preferably aqueous sorbent, and thereby capture at least a portion of the carbon dioxide from the humidified air stream, preferably wherein the one or more contactors is selected from a sorbent sprayer and / or sorbent packing, preferably wherein the module is configured for the passage of an air stream through the system, more preferably wherein the module comprises means of generating an air stream.

[0341] 38265848-2 A module for use in a direct air capture (DAC) system, the module comprising: a humidifying section, the humidifying section being configured to increase the humidity of an air stream to provide a humidified air stream; and an absorber section located downstream of the humidifying section, the absorber section comprising one or more contactors for contacting the humidified air stream with a sorbent, preferably aqueous sorbent, and thereby capture at least a portion of the carbon dioxide from the humidified air stream, preferably wherein the one or more contactors is selected from a sorbent sprayer and / or sorbent packing, wherein the humidifying means comprises a means for providing a water spray, preferably wherein the module is configured for the passage of an air stream through the system, more preferably wherein the module comprises means of generating an air stream.

[0342] A module for use in a direct air capture (DAC) system, the module comprising: a humidifying section, the humidifying section comprising humidifying means configured to increase the humidity of an air stream to provide a humidified air stream, preferably wherein the humidifying means are configured to provide contact between water and the air stream; and an absorber section located downstream of the humidifying section, the absorber section being configured to contact the humidified air stream with a sorbent, preferably an aqueous sorbent, and thereby capture at least a portion of the carbon dioxide from the humidified air stream; a measuring system for measuring one or more of: the humidity of the air stream upstream of the humidifying section; a predicted future humidity of the air stream upstream of the humidifying section; the humidity of the humidified air stream yielded by the humidifying section; and / or the sorbent concentration in the absorber section; and a control unit for adjusting the operation of the humidifying section, based on the measurements from the measuring system, wherein adjusting the operation of the humidifying section preferably comprises: increasing or decreasing a volume of water supplied by the humidifying means;

[0343] 38265848-2 adjusting the flow rate of water through the humidifying section, preferably through humidifying means; adjusting the total effective surface area of water delivered by the humidifying section; activating or deactivating certain humidifying means; increasing or decreasing the degree of contact between water and the air stream in the humidifying section, preferably wherein the module is configured for the passage of an air stream through the system, more preferably wherein the module comprises means of generating an air stream.

[0344] Preferred methods

[0345] Some preferred methods of the present invention are as described below.

[0346] A method for the direct air capture of carbon dioxide from an air stream, the method comprising: passing an air stream through a humidifying section, wherein the humidifying section contacts the air stream with water and increases the humidity of the air stream to provide a humidified air stream; and passing the humidified air stream through an absorber section, wherein the humidified air stream is contacted with one or more contactors contacting the humidified air stream with a sorbent, preferably an aqueous sorbent, and at least a portion of the carbon dioxide is thereby removed from the humidified air stream, wherein the air stream is a stream of ambient or atmospheric air; the method comprises passing the air stream between the humidifying section and the absorber section, preferably generating an air stream between the humidifying section and the absorber section; and preferably, the one or more contactors is selected from a sorbent sprayer and / or sorbent packing;

[0347] A method for the direct air capture of carbon dioxide from an air stream, the method comprising:

[0348] 38265848-2 passing an air stream through a humidifying section, wherein the humidifying section contacts the air stream with water and increases the humidity of the air stream to provide a humidified air stream; and passing the humidified air stream through an absorber section, wherein the humidified air stream is contacted with one or more contactors contacting the humidified air stream with a sorbent, preferably an aqueous sorbent, and at least a portion of the carbon dioxide is thereby removed from the humidified air stream, wherein the air stream is a stream of ambient or atmospheric air; the method comprises passing the air stream between the humidifying section and the absorber section, preferably generating an air stream between the humidifying section and the absorber section; the humidified air stream has a humidity between 80 to 100 %, more preferably 85 to 97.5 %, still more preferably 90 to 95 %; and preferably, the one or more contactors is selected from a sorbent sprayer and / or sorbent packing;

[0349] A method for the direct air capture of carbon dioxide from an air stream, the method comprising: passing an air stream through a humidifying section, wherein the air stream is subjected to a water spray and the humidifying section increases the humidity of the air stream to provide a humidified air stream; and passing the humidified air stream through an absorber section, wherein the humidified air stream is contacted with one or more contactors contacting the humidified air stream with a sorbent, preferably an aqueous sorbent, and at least a portion of the carbon dioxide is thereby removed from the humidified air stream, wherein the air stream is a stream of ambient or atmospheric air; the method comprises passing the air stream between the humidifying section and the absorber section, preferably generating an air stream between the humidifying section and the absorber section; and preferably, the one or more contactors is selected from a sorbent sprayer and / or sorbent packing.

[0350] 38265848-2 A method for the direct air capture of carbon dioxide from an air stream, preferably a stream of ambient or atmospheric air, the method comprising: passing an air stream through a humidifying section, the humidifying section comprising humidifying means to increase the humidity of an air stream to provide a humidified air stream, preferably wherein the humidifying means are configured to provide contact between water and the air stream; and passing the humidified air stream through an absorber section, wherein the humidified air stream is contacted with a sorbent, preferably an aqueous sorbent, and at least a portion of the carbon dioxide is thereby removed from the humidified air stream; measuring, e.g. using a measuring system, one or more of: the humidity of the air stream upstream of the humidifying section; a predicted future humidity of the air stream upstream of the humidifying section; the humidity of the humidified air stream yielded by the humidifying section; and / or the sorbent concentration in the absorber section; and adjusting, e.g. using a control unit, the operation of the humidifying section, based on the measurements from the measuring system, wherein adjusting the operation of the humidifying section preferably comprises: increasing or decreasing a volume of water supplied by the humidifying means; adjusting the flow rate of water through the humidifying section, preferably through humidifying means; adjusting the total effective surface area of water delivered by the humidifying section; activating or deactivating certain humidifying means; increasing or decreasing the degree of contact between water and the air stream in the humidifying section, preferably wherein the air stream is a stream of ambient or atmospheric air; and the method comprises passing the air stream between the humidifying section and the absorber section, preferably generating an air stream between the humidifying section and the absorber section.

[0351] 38265848-2 Clauses

[0352] The invention will now be described with reference to the following non-limiting numbered clauses:

[0353] 1 . A module for use in a direct air capture (DAC) system, the module comprising: a humidifying section, the humidifying section being configured to increase the humidity of an air stream to provide a humidified air stream; and an absorber section located downstream of the humidifying section, the absorber section being configured to contact the humidified air stream with a sorbent and thereby capture at least a portion of the carbon dioxide from the humidified air stream.

[0354] 2. A module according to clause 1 , wherein the humidifying section comprises humidifying means, preferably wherein the humidifying means are configured to provide contact between water and the air stream.

[0355] 3. A module according to clause 2, wherein the humidifying means comprises a means for providing a water spray, preferably wherein the humidifying means comprises a nozzle.

[0356] 4. A module according to any preceding clause, wherein the humidifying section is connected to a supply of water.

[0357] 5. A module according to clause 4, wherein the water is rainwater, mains water, or water from a body of water.

[0358] 6. A module according to any preceding clause, wherein the humidifying section comprises packing for capturing water droplets from the humidified air stream.

[0359] 7. A module according to any one of clauses 2 to 6, wherein the humidifying section comprises a liquid collector for collecting excess water from the humidifying means.

[0360] 8. A module according to clause 7, wherein the humidifying section comprises a recycling system for recycling water from the liquid collector to the humidifying means.

[0361] 9. A module according to any one of clauses 7 to 8, wherein the humidifying section comprises a purification system for treating the water from the liquid collector.

[0362] 38265848-2 10. A module according to any preceding clause, wherein the absorber section comprises one or more contactors for contacting the humidified air stream with a sorbent.

[0363] 11. A module according to clause 10, wherein the one or more contactors is selected from a sorbent sprayer and / or sorbent packing.

[0364] 12. A module according to any preceding clause, wherein the sorbent is aqueous sorbent.

[0365] 13. A module according to any preceding clause, wherein the module comprises a measuring system for measuring one or more of: the humidity of the air stream upstream of the humidifying section; a predicted future humidity of the air stream upstream of the humidifying section; the humidity of the humidified air stream yielded by the humidifying section; and / or the sorbent concentration in the absorber section.

[0366] 14. A module according to clause 13, wherein the module further comprises a control unit for adjusting the operation of the humidifying section, based on the measurements from the measuring system.

[0367] 15. A module according to any preceding clause, wherein the module is configured for the passage of an air stream through the system, preferably wherein the module comprises means of generating an air stream.

[0368] 16. A module according to any preceding clause, wherein the module comprises a plurality of absorber sections and / or a plurality of humidifying sections, preferably wherein: a plurality of absorber sections are located downstream of a single humidifying section; and / or a single absorber section receives a humidified air stream from each of a plurality of humidifying sections.

[0369] 38265848-2 17. A direct air capture (DAC) system, the system comprising a module according to any preceding clause.

[0370] 18. A DAC system according to clause 17, wherein the system further comprises a solvent regeneration unit configured to separate sorbent from the carbon dioxide captured from the humidified air stream.

[0371] 19. Use of a module according to any one of clauses 1 to 16 for the manufacture of a direct air capture (DAC) system, e.g. as recited in clause 17 or 18.

[0372] 20. A method of direct air capture of carbon dioxide from an air stream, the method comprising: providing a module according to any one of clauses 1 to 16 or a system according to clause 17 or 18; and passing an air stream through the module or system.

[0373] 21 . Use of a module according to any one of clauses 1 to 16 or a system according to clause 17 or 18 for the direct air capture (DAC) of carbon dioxide from an air stream.

[0374] 22. A method for the direct air capture of carbon dioxide from an air stream, the method comprising: passing an air stream through a humidifying section, wherein the humidifying section increases the humidity of the air stream to provide a humidified air stream; and passing the humidified air stream through an absorber section, wherein the humidified air stream is contacted with a sorbent and at least a portion of the carbon dioxide is thereby removed from the humidified air stream.

[0375] 23. A method according to clause 22, wherein the method is performed using a module according to any one of clauses 1 to 16 or a system according to clause 17 or 18.

[0376] 24. A method according to clause 22 or 23, wherein the humidity of the air stream is increased to of greater than 80 %, more preferably greater than 90 %, still more preferably greater than 95 %, still more preferably greater than 98 %, still more preferably greater than 99 %, e.g. about 100 %.

[0377] 38265848-2 25. A kit for assembling a module according to any one of clauses 1 to 16, the kit comprising: an absorber section as defined in any one of clauses 1 to 16; a a humidifying section as defined in any one of clauses 1 to 16; and optionally, one or more securing means, preferably releasable securing means, for securing the absorber section to the humidifying section.

[0378] DETAILED DESCRIPTION OF THE FIGURES

[0379] Figure 1 illustrates a schematic view of a module according to the present invention.

[0380] Figure 2 illustrates a schematic view of a module according to the present invention.

[0381] Figure 3 illustrates a schematic view of a module according to the present invention.

[0382] Figure 4 illustrates a schematic view of a module according to the present invention.

[0383] Figure 5 illustrates a schematic view of a module according to the present invention.

[0384] Figure 6 illustrates a schematic view of a module according to the present invention.

[0385] Figure 7 illustrates a schematic view of a module according to the present invention.

[0386] Figure 8 illustrates a schematic view of a module according to the present invention.

[0387] Like features are denoted by like reference numerals, wherein the following scheme is used:

[0388] 100 module

[0389] 101 air stream

[0390] 102 humidifying section

[0391] 103 absorber section

[0392] 104 humidifying means

[0393] 105 water supply

[0394] 106 sorbent packing

[0395] 38265848-2 107 excess water

[0396] 108 fan

[0397] 109 mist eliminator

[0398] 110 CO2 depleted air stream

[0399] 111 sorbent sprayer

[0400] 112 lean sorbent stream

[0401] 113 rich sorbent stream

[0402] 114 packing

[0403] 115 recycling system

[0404] 116 purification system

[0405] 117 sediment

[0406] 118 central plenum

[0407] 119 louvres

[0408] EXAMPLE EMBODIMENTS

[0409] Aspects and embodiments of the present disclosure will now be discussed with reference to the accompanying non-limiting figures.

[0410] Figure 1 illustrates a schematic view of a module 100 according to the present invention. The module can form part of a direct air capture (DAC) system. The module 100 is operated to capture carbon dioxide (CO2) from an air stream 101. The module 100 is embodied as a liquid-absorbent module herein.

[0411] The module comprises an absorber section 103 and a humidifying section 102. The module further comprises a fan 108 configured to generate an air stream 101 between the absorber section 103 and the humidifying section 102. The fan 108 may be disposed upstream or downstream of the absorber section 103. In the illustrated embodiment of Figure 1 , the fan 108 is disposed downstream of the absorber section 103.

[0412] Within the humidifying 102 section are located humidifying means 104, fed by a water supply 105. In Figure 1 , the humidifying means 104 are in the form of a nozzle providing a water spray in the form of a mist. The mist of water increases the humidity of the air stream passing through the humidifying section 102 to provide a humidified air stream for passage to the absorber section 103. Humidification may result in saturation of the air stream 101.

[0413] The humidifying section 102 may be provided with liquid collectors (not illustrated) for the collection of excess water from the humidifying means 104, for

[0414] 38265848-2 example in the form of trays at the base of the section. The positioning of the humidifying section 102 upstream of the absorber section 103 means that the humidifying means 104 and liquid collectors are easily accessible for removal and / or cleaning.

[0415] The absorber section 103 receives the humidified air stream from the humidifying section 102. The absorber section 103 as illustrated comprises a plurality of contactors 106 and 111 for contacting the humidified air stream with a sorbent so as to capture at least a portion of the carbon dioxide from the humidified air stream. In Figure 1 , the absorber section comprises a sorbent sprayer 111 , provided in the form of a nozzle, and sorbent packing 106.

[0416] The sorbent sprayer 111 can provide a fine mist of sorbent, which creates a large and efficient contacting area for capturing carbon dioxide from the humidified air stream. The sorbent packing 106 may be configured to provide a solid surface over which a liquid film of sorbent solution is propagated to provide a large surface area of fluid in contact with the humidified air stream at any one time. Other embodiments may comprise different types of contactors, e.g. comprising only sorbent sprayers 111 or only sorbent packing 106.

[0417] A sorbent flows through each of the contactors 106 and 111 and interacts with the humidified airflow 101 flowing through the absorber section 103. In the illustrated embodiment of Figure 1 , a lean stream 112 of the sorbent enters each of the contactors 106 and 111. The term “lean stream” as used herein relates to a stream of the sorbent that has relatively lower amounts of carbon dioxide. The lean stream 112 contacts the humidified air stream and absorbs at least a portion of the carbon dioxide therefrom to become a rich stream 113. The term “rich stream” as used herein relates to a stream of the sorbent that has relative higher values of carbon dioxide. The lean stream 112 is converted to the rich stream 113 based on the capture of carbon dioxide from the humidified air stream. Meanwhile, the humidified air stream from which carbon dioxide has been captured exits the absorber section 103 as a CO2 depleted air stream 110.

[0418] The lean stream of sorbent 112 is combined with top-up water to provide a desired concentration of the sorbent. The purity of the top-up water is high, to avoid accumulation of solid impurities in the absorber section, which might otherwise negatively impact levels of carbon dioxide capture.

[0419] By providing a humidifying section 102 upstream of the absorber section 103, evaporative losses from the sorbent are desirably minimised. This reduces the volume of top-up water required. Reduced evaporation also reduces the accumulation of solid impurities in the absorber section 103 over time.

[0420] 38265848-2 The module 100 optionally further includes a mist eliminator 109 configured to receive at least a portion of the airflow 101 from the absorber 106. The mist eliminator 109 may function as a drift / droplet capture structure that captures drift / droplets from the air stream before the air stream exits the absorber section 103. In the illustrated embodiment of Figure 1 , the mist eliminator 109 is disposed upstream of the fan 108. However, the mist eliminator 109 may equally be disposed downstream of the fan 108.

[0421] At the inlet of the module are provided louvres 119. The louvres 119 can function to prevent entry of large objects, animals and persons into the module; to smooth air flow and dampen out gusts; to reduce escape of sorbent or liquid from the module; and / or to seal the module under extreme conditions or for shut-down or maintenance. In addition to or as an alternative to louvres, the inlet may also comprise fixed packing or other forms of filter, such as mesh filters.

[0422] Figure 2 illustrates a schematic view of another module of the present invention. As with Figure 1 , the humidifying section 102 comprises humidifying means 104 in the form of a nozzle providing a water spray in the form of a mist. Downstream of the humidifying means 104, the humidifying section 102 also comprises packing 114 to catch water droplets in the humidified air stream and prevent them from entering the absorber section 103. This may be desirable to prevent lower quality water from water supply 105 contaminating the controlled reaction environment in absorber section 103.

[0423] Excess water 107 derived from the humidifying means 104 or captured by the packing 114 can together be caught in liquid collectors (not shown), for example in the form of trays at the base of the humidifying section 102.

[0424] Figure 3 illustrates a schematic view of another module of the present invention. As with Figure 2, the humidifying section 102 comprises humidifying means 104 in the form of a nozzle providing a water spray in the form of a mist, a packing section 114 for capturing water droplets, and a liquid collector (not shown) for collecting excess water 107 derived from the humidifying means 104 or captured by the packing 114. The liquid collector may be in the form of a tray. At least a portion of the excess water 107 collected in the liquid collector is recycled to the humidifying means 104 via a recycling system 115. Water throughput losses are thereby reduced.

[0425] Figure 4 illustrates a schematic view of another module of the present invention. As with Figure 3, the humidifying section 102 comprises humidifying means 104 in the form of a nozzle providing a water spray in the form of a mist, a packing section 114 for capturing water droplets, a liquid collector (not shown) for collecting excess water 107

[0426] 38265848-2 derived from the humidifying means 104 or captured by the packing 114, and a recycling system 115.

[0427] The humidifying section further comprises a purification system 116. In Figure 4, the purification system is embodied as a settling tank, although alternative purification systems can be used. Excess water 107 collected in the liquid collector (not shown) is processed through the purification system 116, with impurities forming a sediment 117 at the base of the tank. Impurities in the sediment 117 may include solid deposits, contaminants, airborne particles, insects, and similar.

[0428] Following treatment by the purification system, at least a portion of the excess water 107 is then recycled to the humidifying means 104 via the recycling system 115, while a further portion can be discharged. The purification step thus improves the purity of the recycled water, improving operation of the humidifying section as a whole.

[0429] Figure 5 illustrates a schematic view of another module of the present invention, having a modular arrangement. The module comprises six humidifying sections 102, downstream of each of which is an absorber section 103. The humidifying section 102 and absorber section 103 pairs are arranged around a central plenum 118. In Figure 5 the pairs are shown stacked three-high, on either side of the central plenum 118, but other arrangements are also possible.

[0430] The module is configured with the aid of a fan 108 to generate an air stream through each pair of humidifying section 102 and absorber section 103. The module is configured to combine the CO2 depleted air stream 110 yielded by each absorber section 103 into the central plenum 118. The combined CO2 depleted air streams 110 are together brought into contact with mist eliminator 109.

[0431] Figure 6 illustrates a schematic view of another module of the present invention, having a modular arrangement. The module is in accordance with Figure 5, but with each humidifying section additionally comprising packing 114 to catch water droplets in the humidified air stream and prevent them from entering the absorber section 103.

[0432] Figure 7 illustrates a schematic view of another module of the present invention, having a modular arrangement. On each side of the central plenum 118 is provided a single humidifying section 102. Each humidifying section 102 comprises humidifying means 104 in the form of a nozzle configured to provide a rain wash of water.

[0433] The module is configured with the aid of a fan 108 to generate an air stream between each humidifying section 102 and a plurality of absorber sections 103. The humidified air stream from each humidifying section 102 is divided between three absorber sections 103, stacked three high on each side of the central plenum 118.

[0434] 38265848-2 The module is further configured with the aid of fan 108 to combine the CO2 depleted air stream 110 yielded by each absorber section into the central plenum 118. The combined CO2 depleted air streams 110 are together brought into contact with mist eliminator 109.

[0435] Figure 8 illustrates a schematic view of another module of the present invention, having a modular arrangement. On each side of the central plenum 118 is provided a plurality of humidifying sections 102 and a plurality of absorber sections 103. On each side of the central plenum 118 are stacked six humidifying sections 102 and three absorber sections 103. Each humidifying section 102 comprises humidifying means 104 in the form of a nozzle providing a water spray in the form of a mist. Each humidifying section is also provided with holes at its base to facilitate dripping of the water from upper humidifying sections into lower humidifying sections. The holes may be provided within water trays, so a horizontal surface of water is also provided for contact with the air stream. Together, these factors act to increase the overall contact between the water and the air stream.

[0436] The module is configured with the aid of a fan 108 to generate an air stream between each of two humidifying sections 102 and a single absorber section 103.

[0437] The module is further configured with the aid of fan 108 to combine the CO2 depleted air stream 110 yielded by each absorber section 103 into the central plenum 118. The combined CO2 depleted air streams 110 are together brought into contact with mist eliminator 109.

[0438] 38265848-2

Claims

64CLAIMS:1 . A module for use in a direct air capture (DAC) system, the module comprising: a humidifying section, the humidifying section being configured to increase the humidity of an air stream to provide a humidified air stream having a humidity of between 70 to 97.5 %; and an absorber section located downstream of the humidifying section, the absorber section being configured to contact the humidified air stream with a sorbent and thereby capture at least a portion of the carbon dioxide from the humidified air stream, wherein the sorbent comprises one or more amino acid salts.

2. A module according to claim 1 , further comprising: a measuring system for measuring the humidity of the humidified air stream yielded by the humidifying section; a control unit for adjusting the operation of the humidifying section based on the measurements from the measuring system to provide said humidity of between 70 to 97.5 % to the humidified air stream.

3. A module for use in a direct air capture (DAC) system, the module comprising: a humidifying section, the humidifying section being configured to increase the humidity of an air stream and to cool the air stream to provide a humidified air stream; and an absorber section located downstream of the humidifying section, the absorber section being configured to contact the humidified air stream with a sorbent and thereby capture at least a portion of the carbon dioxide from the humidified air stream.

4. A module according to claim 3, wherein the sorbent comprises one or more amino acid salts, preferably wherein the humidified air stream has a humidity of less than 100 %.

5. A module according to any preceding claim, the module comprising: a humidifying section, the humidifying section being configured to increase the humidity of an air stream and to cool the air stream to provide a humidified air stream having a humidity of between 70 to 97.5 %; and38265848-265 an absorber section located downstream of the humidifying section, the absorber section being configured to contact the humidified air stream with a sorbent and thereby capture at least a portion of the carbon dioxide from the humidified air stream, wherein the sorbent comprises one or more amino acid salts.

6. A module according to any preceding claim, wherein the humidifying section comprises humidifying means.

7. A module according to claim 6, wherein the humidifying means are configured to provide contact between water and the air stream.

8. A module according to any one of claims 6 to 7, wherein the humidifying means comprise refrigeration means.

9. A module according to any one of claims 7 to 8, wherein the water is chilled water.

10. A module according to any claim 9, wherein the module comprises a cooler for providing the chilled water.

11. A module according to claim 10, wherein the cooler is configured to provide chilled water at a temperature of less than 25, preferably less than 20, more preferably less than 15, still more preferably less than 10, still more preferably less than 5 °C.

12. A module according to any preceding claim wherein the humidified air stream has a humidity of between 80 to 97.5 %, more preferably 85 to 97.5 %, still more preferably 85 to 95 %.

13. A module according to any preceding claim, wherein the humidified air stream has a humidity of 85 to 97.5 %, still more preferably 90 to 95 %.

14. A module according to any preceding claim, wherein the absorber section comprises a source of the sorbent.

15. A module according to any preceding claim, wherein the humidifying section is connected to a supply of water.38265848-26616. A module according to claim 15, wherein the water is rainwater, mains water, or water from a body of water.

17. A module according to any preceding claim, wherein the module comprises a plurality of absorber sections and / or a plurality of humidifying sections, preferably wherein: a plurality of absorber sections are located downstream of a single humidifying section; and / or a single absorber section receives a humidified air stream from each of a plurality of humidifying sections.

18. A direct air capture (DAC) system, the system comprising a module according to any preceding claim.

19. A DAC system according to claim 18, wherein the system further comprises a solvent regeneration unit configured to separate sorbent from the carbon dioxide captured from the humidified air stream.

20. Use of a module according to any one of claims 1 to 17 for the manufacture of a direct air capture (DAC) system, e.g. as claimed in claim 18 or 19.21 . A method of direct air capture of carbon dioxide from an air stream, the method comprising: providing a module according to any one of claims 1 to 16 or a system according to claim 18 or 19; and passing an air stream through the module or system.

22. Use of a module according to any one of claims 1 to 17 or a system according to claim 18 or 19 for the direct air capture (DAC) of carbon dioxide from an air stream.

23. A method for the direct air capture of carbon dioxide from an air stream, the method comprising:38265848-267 passing an air stream through a humidifying section, wherein the humidifying section increases the humidity of the air stream to provide a humidified air stream having a humidity of between 70 to 97.5 %; and passing the humidified air stream through an absorber section, wherein the humidified air stream is contacted with a sorbent and at least a portion of the carbon dioxide is thereby removed from the humidified air stream, wherein the sorbent comprises one or more amino acid salts.

24. A method for the direct air capture of carbon dioxide from an air stream, the method comprising: passing an air stream through a humidifying section, wherein the humidifying section increases the humidity of the air stream and cools the air stream to provide a humidified air stream; and passing the humidified air stream through an absorber section, wherein the humidified air stream is contacted with a sorbent and at least a portion of the carbon dioxide is thereby removed from the humidified air stream.

25. A method according to claim 24, wherein the sorbent comprises one or more amino acid salts, preferably wherein the humidified air stream has a humidity of less than 100 %.

26. A method according to any one of claims 23 to 25, the method comprising: passing an air stream through a humidifying section, wherein the humidifying section increases the humidity of the air stream and cools the air stream to provide a humidified air stream having a humidity of between 70 to 97.5 %; and passing the humidified air stream through an absorber section, wherein the humidified air stream is contacted with a sorbent and at least a portion of the carbon dioxide is thereby removed from the humidified air stream, wherein the sorbent comprises one or more amino acid salts.

27. A method according to any one of claims 23 to 26, comprising contacting the air stream with water in the humidifying section.

28. A method according to claim 27, wherein the water is chilled water.38265848-26829. A method according to claim 28, wherein the chilled water has a temperature of less than 25, preferably less than 20, more preferably less than 15, still more preferably less than 10, still more preferably less than 5 °C.

30. A method according to any one of claims 23 to 29, wherein the humidified air stream has a humidity of between 80 to 97.5 %, more preferably 85 to 97.5 %, still more preferably 85 to 95 %.

31. A method according to any one of claims 23 to 29, wherein the humidified air stream has a humidity of 85 to 97.5 %, preferably 90 to 95 %.

32. A method according to claim any one of claims 23 to 31 , wherein the method is performed using a module according to any one of claims 1 to 17 or a system according to claim 18 or 19.

33. A kit for assembling a module according to any one of claims 1 to 17, the kit comprising: an absorber section as defined in any one of claims 1 to 17; a a humidifying section as defined in any one of claims 1 to 17; and optionally, one or more securing means, preferably releasable securing means, for securing the absorber section to the humidifying section.38265848-2

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