Methods for extracting and sequestering carbon dioxide

Abstract

Disclosed herein are methods and apparatuses for providing a hydroxide pump, The hydroxide pump can be used for capturing and sequestering carbon dioxide from a gas stream. The methods include producing a basic stream and an acidic stream from a solution; reacting carbonate with a first acid from the acidic stream to increase a dissolution rate of the carbonate to produce bicarbonate; and reacting carbon dioxide with a base from the basic stream to produce bicarbonate, the carbon dioxide derived from the reaction of the first acid with the carbonate.

Description

METHODS FOR EXTRACTING AND SEQUESTERING CARBON DIOXIDEFIELD

[0001] The present disclosure relates to the field of extracting and sequestering carbon dioxide and, in particular, to hydroxide pumps for accelerated limestone weathering.BACKGROUND

[0002] Global industrialization has led to increased levels of CO2 emissions, contributing to global warming and ocean acidification. The climate crisis has prompted stringent measures to be proposed by the EPA and other regulatory bodies requiring industrial emitters to capture and store a substantial portion of their CO2 emissions. The need for efficient, cost- effective, and permanent solutions for CO2 capture and sequestration is, therefore, more critical than ever.

[0003] Methods for capturing and storing CO2 include geological sequestration or chemical reactions to create solid carbonates. These known methods are often costly, energy- intensive, and can pose risks to the environment. Proposed solutions have also been described that involve methods for increasing the alkalinity of the ocean to increase the potential of the ocean to store carbon, however, such methods also present prohibitive challenges that include difficult measurement and verification of storage. One such example involves the use of electrolysis or electrodialysis to create separate acidic and basic (alkaline) streams for the purpose of using the basic stream to enhance ocean alkalinity and thereby the potential for carbon storage. While this method can be effective, it has the prohibitive drawback of producing a massive amount of acidic ocean water (commonly referred to as HC1) that creates a further environmental issue for disposal. For these reasons, such methods have not been proven successful.

[0004] Methods involving the accelerated weathering of limestone (AWL) for CO2 neutralization and storage have been proposed to address these shortcomings. United StatesPatent No. 6,890,497 (Rau el al.) describes a gas / water / calcium carbonate (limestone) reactor process for extracting CO2 from an exhaust gas stream. AWL is a chemical process (1) by which CO2 dissolves in water to form carbonic acid, which in turn dissolves limestone, neutralizing the acid. The resulting aqueous solution contains calcium and bicarbonate ions, which are both common in the ocean and non-toxic.

[0005] The stepwise progression of AWL involves CO2 in the gas phase (atmospheric or flue gas) to be dissolved in the liquid phase (2). The aqueous CO2 will then become hydrated to form carbonic acid (3), which then quickly loses a proton (H+) to become bicarbonate (4). The proton then attacks the limestone surface and causes dissolution.

[0006] A known challenge of AWL is that it is kinetically limited. In particular, the step of limestone dissolution in the presence of carbonic acid (5) is prohibitively slow and has resulted in the limited applicability of AWL for CO2 capture.

[0007] There is, therefore, an unmet need for a method that addresses these shortcomings and that can both capture CO2 efficiently from various industrial sources and ensure that the CO2 remains sequestered from both the ocean and the atmosphere. Furthermore, there is a need for a method that ensures bicarbonate created from CO2 in the oceanic environment for extended periods, which is vital for any long-term climate change mitigation strategy.

[0008] This background information is provided for the purpose of making known information believed by the applicant to be of possible relevance to the present disclosure.No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.SUMMARY

[0009] An object is to provide a method for extracting and sequestering carbon dioxide. In accordance with one aspect, there is provided a method of capturing and sequestering carbon dioxide from a gas stream comprising a hydroxide pump, wherein the hydroxide pump carries out the following steps: producing a basic stream and an acidic stream from a solution by electrodialysis; reacting carbonate with a first acid from the acidic stream to increase a dissolution rate of the carbonate to produce bicarbonate; and reacting carbon dioxide with a base from the basic stream to produce bicarbonate, the carbon dioxide derived from the reaction of the first acid with the carbonate.

[0010] In some embodiments, excess base from the basic stream is reacted with carbon dioxide gas from a carbon dioxide gas stream to produce bicarbonate.

[0011] In accordance with another aspect, there is provided a hydroxide pump for carbon dioxide sequestration, comprising: an acid-base generator configured to receive a solution and produce a basic stream and an acidic stream from the solution by electrodialysis; an acid neutralizer configured to receive carbonate and the acidic stream from the acid-base generator, wherein the carbonate reacts with a first acid from the acidic stream to increase a dissolution rate of the carbonate to produce bicarbonate; and a vessel for capturing carbon dioxide off-gas from the acid neutralizer, the vessel configured to receive at least half of the basic stream from the acid-base generator wherein the carbon dioxide off-gas reacts with a base from the basic stream to produce bicarbonate. .BRIEF DESCRIPTION OF THE DRAWINGS

[0012] These and other features will become more apparent in the following detailed description in which reference is made to the appended drawings.

[0013] Figure l is a schematic view of a hydroxide pump according to an embodiment of the present disclosure;

[0014] Figure l is a schematic view of the hydroxide pump shown in Figure 1 used with an output of an accelerated limestone weathering process according to an embodiment of the present disclosure;

[0015] Figure 3 is a schematic view of the hydroxide pump shown in Figure 1 used in an accelerated limestone weathering process according to an embodiment of the present disclosure;

[0016] Figure 4 is a schematic view of the hydroxide pump for dissolution using HC1;

[0017] Figure 5 is a schematic view of the hydroxide pump for neutralization using a base from the hydroxide pump;

[0018] Figure 6 is a schematic view of the hydroxide pump for carbon dioxide capture using a base from the hydroxide pump; and

[0019] Figure 7 is a schematic view of the hydroxide pump for carbon dioxide sequestration and for neutralization each using a base from the hydroxide pump.DETAILED DESCRIPTION

[0020] Disclosed herein is a hydroxide pump for use in methods for extracting and sequestering CO2. In particular, a hydroxide pump is provided that overcomes the kinetic limitations of dissolving limestone and more rapidly produces a base (alkaline material) to convert CO2 into bicarbonate, in accordance with some embodiments. According toembodiments, a hydroxide pump is provided that can be incorporated into a system for sequestering carbon dioxide. In certain embodiments, a hydroxide pump is provided that is incorporated into a method for accelerated weathering of limestone (AWL).

[0021] Limestone is a rock containing a carbonate, i.e., a carbonate mineral, specifically, calcite. At very low pH (< 5), the calcite dissolution rate (to produce bicarbonate and Ca2+according to step (5)) is proportional to the proton (acid) concentration. At pH > 5, the calcite dissolution rate increases based on the partial pressure of CO2 (PC02). Accordingly, in some embodiments, the hydroxide pump generates an acidic stream effective for creating conditions suitable for overcoming the kinetic barrier of the reaction defined by step (5). Specifically, the hydroxide pump provides conditions in which the pH is low and the H+concentration is high, thereby exposing calcite to a very strong acid to increase the dissolution rate and significantly overcome the kinetic barrier in reaction step (5).

[0022] While conditions of low pH and high H+concentration is conducive to reaction step (5), a high concentration of H+can result in the undesirable reversal of chemical process (4). A high concentration of H+can drive step (4) in the opposite direction, leading to the formation of carbonic acid and the undesirable production of carbon dioxide gas. According to certain embodiments, the hydroxide pump simultaneously generates a basic stream effective for creating conditions suitable for inhibiting the reversal of step (4) and the production of carbon dioxide gas. Specifically, the hydroxide pump provides conditions in which a base is generated to reduce the concentration of H+and increase pH to produce a solution higher in bicarbonate.

[0023] In some embodiments, there is provided a hydroxide pump that includes a system that simultaneously generates an acidic stream and a basic stream (8) from salt water such as seawater, using an electrochemical membrane, reversible photoacid system, or system using electricity, solar energy, or other power source. For example, the electrochemical membrane can be any electrochemical membrane that generates an acid and base from salt water. In some embodiments, the hydroxide pump uses an electrodialytic process to separateH+from OH' in the salt water and produces hydrochloric acid and sodium hydroxide as the acidic stream (7a) and basic stream (7b).-> H + Cl' (acidic stream) (7a)H2O + OH' + H++ Na++ Cl'(basic stream) (7b)

[0024] In some embodiments, the acidic stream comprises a strong acid, and the basic stream comprises a strong base. According to certain embodiments, the strong acid has a pH of <5. According to other embodiments, the strong acid has a pH of 1-3. In some embodiments, the strong base has a pH of >8. In further embodiments, the strong base has a pH of 10-14.

[0025] According to embodiments, the hydroxide pump is incorporated into methods for sequestering carbon dioxide. In particular embodiments, the hydroxide pump is incorporated into a method for accelerated weathering of limestone (AWL). Other methods for sequestering carbon dioxide are known to those skilled in the art and adapting such methods to incorporate the hydroxide pump would be within the knowledge of the skilled person. In such embodiments, the strong acid is delivered to limestone to produce bicarbonate according to the chemical process (9). Where some of the bicarbonate reacts with H+to produce carbon dioxide according to the chemical process (10), the strong base from the basic stream is subsequently delivered to react with the carbon dioxide off-gas to produce bicarbonate according to the chemical process (11). In this way, the hydroxide pump can be used to improve the efficacy of methods for extracting and sequestering CO2 by overcoming the kinetic limitations of dissolving limestone and producing a base to convert undesirably produced CO2 off-gas into bicarbonate.

[0026] According to embodiments, the chemical equation (12) summarizes the chemical processes implemented by the hydroxide pump, while the chemical equation (13) is a summation of the steps (8) to (11) showing that calcite (e.g., limestone) can be dissolved to produce a net basic solution using an acid and a base.

[0027] In such embodiments, the hydroxide pump produces the acid and the base in equal parts using electrodialysis of salt water. In certain embodiments, the acid and base produced by the hydroxide pump results in the chemical process that for each mole of calcite and two moles of H+consumed, one mole of hydroxide is consumed and one mole of hydroxide is unused which can be reserved or directed to another application. In other embodiments, for each two moles of acid that is produced, one mole of calcium carbonate and base are consumed, leaving one mole of base (OH ) for other use. In this way, according to such embodiments, the hydroxide pump further provides (unused) hydroxide to be fed into other parts of a system for sequestering carbon dioxide, for example, in a CO2 contactor.Definitions

[0028] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0029] As used herein, the term “about” and “approximately” refers to an approximately + / -10% variation from a given value. It is to be understood that such a variation is always included in any given value provided herein, whether or not it is specifically referred to.

[0030] As used herein, references to singular is understood to mean singular in some embodiments and plural or “at least one” in other embodiments.

[0031] As used herein, unless otherwise specified or understood from the context, references to carbonate, the carbonate, or a carbonate are understood, in some embodiments to include materials, such as limestone, calcite, aragonite, magnesium carbonate, and / orpotassium carbonate, that include the carbonate ion, CCh2', such as bound to a cation. As used herein, unless otherwise specified or understood from the context, a carbonate refers to a carbonate in solid form, such as a carbonate mineral. The carbonate is bound to a cation (e.g., potassium, calcium, magnesium, etc.), in some embodiments. For example, the carbonate can be calcite, aragonite, limestone, dolomite, magnesium carbonate, potassium carbonate, sodium carbonate, or other carbonate.

[0032] As used herein, in the context of a molecule being derived from other molecule(s), references to “derived” mean produced directly from or produced after two or more chemical reactions or both.

[0033] According to embodiments of the present disclosure, as shown in Figure 1, a hydroxide pump 100 includes an acid-base generator 110 and an acid neutralizer 120. The acid-base generator 110 is an electrochemical membrane, in some embodiments. In further embodiments, the acid-base generator 110 is a photoacid system. In some embodiments, hydroxide pump 100, at acid-base generator 110, is configured to generate a strong acid and a strong base from saltwater. The strong acid is used at acid neutralizer 120 to dissolve carbonate (e.g., limestone or calcite) at a lowered pH to accelerate the rate of its dissolution to bicarbonate (e.g., according to chemical process (9)), and convert (e.g., according to chemical process (11)) carbon dioxide produced from the system (e.g., according to chemical process (10)) to bicarbonate. In some embodiments, chemicals incorporating carbonate or from which carbonate can be derived can be used.

[0034] In some embodiments, hydroxide pump 100 can be incorporated into an AWL process and used to accelerate the dissolution of carbonate (e.g., limestone or calcite) in an AWL process such as described by United States Patent No. 6,890,497 (Rau et al.), specifically by accelerating chemical process (5).

[0035] An output of hydroxide pump 100 can include H2O, HCCh", calcium ions, chloride ions, sodium ions that can be safely streamed as effluent to the sea or further processed, forexample. The effluent can have a basic pH, and in some embodiments the basic pH is around 8.2 for example. This effluent, according to embodiments, is produced by the chemical process of the hydroxide pump’s acidic stream (9) to release HCCh' and calcium ions, in combination with the chemical processes of the hydroxide pump’s basic stream (10), (11) in which the base (from the basic stream) reacts with carbon dioxide produced as off-gas from the acidic stream reaction, of acid and bicarbonate ions, to produce H2O and HCCh'.

[0036] Hydroxide pump 100 can be used at, near, or in an environmental source of seawater or an output stream of an industrial apparatus or system, for example. This can facilitate the use of related materials or streams as inputs and / or safe disposal or outflow of products.Acid-Base Generator

[0037] According to embodiments, the hydroxide pump comprises an acid-base generator 110. Acid-base generator 110 is configured to receive a solution and produce a basic stream and an acidic stream from the solution. According to embodiments, the solution can be saltwater such as seawater or brine. In other embodiments, the solution can be a concentrated waste stream from a desalination process. For example, acid-base generator 110 is configured to carry out chemical process (8) in some embodiments. In some embodiments, acid-base generator 110 includes an electrochemical membrane. In some embodiments, acid-base generator 110 includes a reversible photoacid system. In some embodiments, acidbase generator 110 additionally includes an electrodialytic system. For example, acid-base generator 110 can separate H+and OH' in a saltwater solution and produce the basic stream and the acidic stream by using an electrochemical membrane, reversible photoacid system, or other system to split protons and hydroxide ions from the H2O.

[0038] In some embodiments, acid-base generator 110 produces a basic stream containing a strong base and produces an acidic stream containing a strong acid. In some embodiments, acid-base generator 110 produces a basic stream containing at least one base capable of increasing the pH of an output of AWL to above 7. In certain embodiments, the basic streamis capable of increasing the pH of an output of AWL to a pH of 8 to 9. In some embodiments, acid-base generator 110 produces a basic stream containing at least one base capable of reacting with carbon dioxide to produce bicarbonate such as in a chemical process (11). In some embodiments, acid-base generator 110 produces an acidic stream containing an acid capable of lowering a pH to less than 5 and / or reacting with carbonate (e.g., limestone or calcite) to produce bicarbonate. For example, the acid is capable of increasing the rate of chemical process (5) by lowering the pH.

[0039] In some embodiments, acid-base generator 110 produces a basic stream comprising hydroxide (OH ) and an acidic stream comprising proton (H+) in a 1 : 1 ratio (e.g., two moles of each produced for each two moles of H2O) and hydroxide pump 100 consumes the hydroxide, the protons, and calcite (CaCCh) in a 1 :2: 1 ratio. In some embodiments, the hydroxide pump is configured to direct half of the hydroxide produced for consumption by the acid neutralizer 120, for reaction with carbon dioxide off-gas (chemical process 11), and to direct the remaining half of the hydroxide produced in the basic stream for other applications.Acid Neutralizer

[0040] Acid neutralizer 120 is configured to carry out the chemical processes (9), (10), and (11) using acid from the acidic stream produced by acid-base generator 110 and base from the basic stream produced by acid-base generator 110. For example, acid neutralizer 120 is configured to expose the carbonate to an acid from the acidic stream to increase a dissolution rate of the carbonate to produce bicarbonate. Acid neutralizer 120 is configured to react the carbonate with an acid from the acidic stream to increase a dissolution rate of the carbonate to produce bicarbonate. The carbonate can be in the form of limestone, calcite, or aragonite, for example, and can be received by acid neutralizer 120 in the form of a limestone slurry, for example. More specifically, protons are reacted with carbonate (e.g., limestone or calcite) to produce bicarbonate (9). This allows for the dissolution of carbonate (e.g., limestone or calcite) to produce bicarbonate (9). The protons can be derived from the acidic stream and / or from AWL, for example, from carbonic acid produced by the hydration ofcarbon dioxide in a solution from a gas stream (3), (4). Acid (e.g., protons) from the acidic stream is added to further lower the pH at which the carbonate is dissolved to produce bicarbonate (9). When the acid dissolves the carbonate, a cation can be released. For example, CaCCh releases Ca2+and MgCCh releases Mg2+. In some embodiments, the acid is introduced to the system via an acid delivery unit.

[0041] In some embodiments, the increased acid in the system can result in the production of carbon dioxide off-gas according to chemical process (10). This may be undesirable where hydroxide pump 100 is used in a carbon capture and sequestering system, such as AWL. The presence of excess acid in the system leading to chemical process (10) and the production of carbon dioxide is one major drawback of simply adding acid to increase the dissolution rate of carbonate (e.g., limestone or calcite). Increasing the dissolution rate of carbonate may be desirable where it advantageously allows for the consumption of acid (protons) which may be an important step for driving a carbon capture reaction, such as according to chemical processes (3), (4) in AWL, however, carbon dioxide off gassing can be an undesirable result. To address this undesirable effect, in some embodiments, acid neutralizer 120 is configured to expose carbon dioxide off-gas (e.g., derived from the bicarbonate) to a base from the basic stream, such that the base reacts with the carbon dioxide off-gas to produce bicarbonate according to chemical process (11). This can advantageously reduce the amount of carbon dioxide that is produced using hydroxide pump 100 and enable hydroxide pump 100 to effectively enhance the efficacy of a carbon capture system, such as AWL. In some embodiments, the base is introduced to the system via a base delivery unit.

[0042] In some embodiments, the carbon dioxide off-gas is captured in a vessel and the base from the basic stream is reacted with the carbon dioxide in the vessel. For example, in some embodiments, hydroxide pump 100 is implemented as follows. At a first step, acid from the acidic stream is added to the carbonate (e.g., calcium carbonate) to neutralize the acid, which can cause the CO2 to off-gas. Next, at a second step, the off-gassed CO2 is captured in a vessel, where base from the basic stream is added to convert the CO2 into bicarbonate.

[0043] In some embodiments, the acid from the acidic stream is mixed with the carbonate (e.g., limestone) and, subsequently, approximately half of the base produced in the basic stream is exposed to released CO2 in a downstream vessel. In some embodiments, the other approximately half of the base produced in the basic stream is used or diverted to a different purpose, such as in a neutralization step (e.g., neutralizing an acidic output from AWL) such as shown in FIG. 2 and / or to capture CO2 in flue gas such as shown in FIG. 3.

[0044] In some embodiments, acid neutralizer 120 does not neutralize acid, but may generate an output with increased pH, which may be acidic, neutral, or basic, in various embodiments. In some embodiments, the output stream of acid neutralizer 120 is slightly basic, for example, configured to match or slightly exceed the ambient pH of seawater that it is going into. An example desired pH is 8.2. Other pHs are possible.

[0045] To gain a better understanding of the disclosure described herein, the following examples are set forth. It will be understood that these examples are intended to describe illustrative embodiments and are not intended to limit the scope of the invention in any way.EXAMPLESEXAMPLE 1Application of Hydroxide Pump to Improve the Rate of Dissolution of Limestone in the Presence of Carbonic Acid in AWL

[0046] In some embodiments, hydroxide pump 100 is configured to improve the rate of dissolution of limestone in the presence of carbonic acid in AWL. More specifically, hydroxide pump 100 is configured to improve the rate of chemical process (5) which is a rate limiting step of AWL and prohibitive for the practical and efficient application of AWL for effective carbon capture. In particular, in some embodiments, carbonate (e.g., limestone or calcite) is exposed to acid from the acidic stream produced by acid-base generator 110 of hydroxide pump 100 to decrease the pH and increase the rate of chemical process (9), which reacts acid (H+) (such as acid from the carbonic acid produced from the hydration of carbondioxide in AWL or acid from the acidic stream, or both) with carbonate (e.g., limestone, calcite, or aragonite) to produce bicarbonate. Carbon dioxide, if any, produced from the reaction of excess acid (H+) with bicarbonate according to chemical process (10) is exposed to base from the basic stream produced by acid-base generator 110 of hydroxide pump 100 to produce bicarbonate according to chemical process (11). Advantageously, in some embodiments, the use of hydroxide pump 100 enables AWL to be used effectively for the conversion of carbon dioxide gas to output products that can more safely be dispersed into the environment.EXAMPLE 2:Application of Hydroxide Pump to Neutralize Output of AWL

[0047] According to embodiments of the present disclosure, as shown in Figure 2, a hydroxide pump 100 is used to raise the pH of the AWL output water to make it safer to disperse into the ocean. More specifically, a base produced from the basic stream produced by a hydroxide pump 100 is provided to an output stream of AWL. This lowers the pH of the products remaining after step (5) of AWL is complete. The output stream of AWL can be bicarbonate-rich seawater, for example, having an example acidic pH of 6.2. Following addition of the base, the bicarbonate-rich seawater can be raised to a basic pH, such as 8.5. For example, AWL can take in carbon dioxide from a gas stream as input (e.g., from flue gas), seawater (or other salt water in other embodiments), and carbonate (e.g., limestone or calcite) and produce bicarbonate-rich seawater with an acidic pH. This allows for carbon capture and conversion of carbon dioxide gas to output that can be more safely disposed of, such as by diversion to seawater as bicarbonate is common in seawater and non-toxic. Output from hydroxide pump 100, such as sodium bicarbonate water can also be mixed with the bicarbonate-rich seawater AWL output following neutralization of that bicarbonate-rich seawater with the base from the hydroxide pump 100. The resulting stream can be more safely mixed with seawater in the environment.EXAMPLE 3:a Scrubber byLimestone

[0048] According to embodiments of the present disclosure, as shown in Figure 3, a hydroxide pump 100 is used to capture carbon dioxide using hydroxide water in scrubber 300, which overcomes the kinetic challenges of neutralizing CO2 with limestone, which are typical in AWL. Limestone (or calcium carbonate or other carbonate) is dissolved in the acid neutralizer 120 of hydroxide pump 100, to consume the acid, which in some embodiments is an unwanted by-product. This causes chemical process (5) to occur more quickly. This advantageously allows scrubber 300 to practically be used for carbon capture, converting carbon dioxide gas pollutant to bicarbonate water that can more safely be dispersed into the ocean, according to some embodiments.

[0049] Excess base from the basic stream produced by hydroxide pump 100 is reacted with carbon dioxide gas from a carbon dioxide gas stream to produce bicarbonate. For example, base from a basic stream produced by hydroxide pump 100 is used to react with CO2, such as flue gas, at scrubber 300 to produce bicarbonate. This process can be performed at, near, or in seawater, with the output stream of scrubber 300 being mixed with environmental seawater. In some embodiments, an output stream described herein can be further processed before output into environmental seawater. In some embodiments, scrubber 300 is an AWL process, except with limestone replaced by NaOH.

[0050] According to embodiments of the present disclosure, base from basic stream produced by acid-base generator 110 of hydroxide pump 100 is contacted with (e.g., reacted with) carbon dioxide gas to produce bicarbonate. The bicarbonate can be dispersed into seawater at a basic pH, such as pH 8.5, for example. The base can be approximately half of the base produced by hydroxide pump, such as where hydroxide pump 100 splits H+and OH' streams from water in a 1 : 1 ratio, with hydroxide pump 100 consuming the H+and OH' in a 2: 1 ratio, with the excess OH' directed to another application, such as scrubber 300.

[0051] In some embodiments, hydroxide pump 100 provides an unexpected and advantageous method that can be coupled with a CO2 capture process that uses a base (e.g.,NaOH) to react with the CO2, such as scrubber 300. Hydroxide pump 100 is not an expected solution as dissolving calcium carbonate (or other carbonate) with a strong acid can cause CO2 to offgas, which is undesired. However, hydroxide pump 100 can reduce any offgassing CO2 by reaction with hydroxide produced from hydroxide pump 100. Furthermore, in this novel method, in some embodiments, a portion of the base produced by hydroxide pump 100 is used for the excess CO2 capture in a subsequent vessel. Hydroxide pump 100 can be used in electrolytic processes for CO2 removal in the ocean, according to some embodiments.EXAMPLE 4:Application of Hydroxide Pump for Dissolution Using HC1

[0052] According to embodiments of the present disclosure, as shown in Figure 4, hydroxide pump 100 is configured to enhance dissolution of limestone (or other carbonate in other examples) using HC1 from an acidic stream produced by acid-base generator 110 of hydroxide pump 100. The HC1 is provided to a dissolution vessel in which excess limestone is dissolved and filtered out. The filtered limestone can be outputted in a limestone slurry and recycled.

[0053] Base from a basic stream produced by acid-base generator 110 of hydroxide pump 100 is provided to a neutralization vessel in which bi-carbonate-rich water from the dissolution vessel is also received. The remaining carbonic acid in the bicarbonate-rich water is reacted with base in the neutralization vessel to produce bicarbonate. This reaction drives the dissolution in the dissolution vessel forward and increases the dissolution rate of the carbonate to produce bicarbonate. Carbon dioxide or carbonic acid may be produced in the dissolution vessel and the base is reacted with the carbon dioxide or carbonic acid to produce bicarbonate. This can advantageously increase the rate of dissolution of the limestone in the dissolution tank, with the same resulting pH coming out of the neutralization tank to effectively decrease the required residence time of a carbon capture system.

[0054] The acid from the acidic stream and the base from the basic stream can be consumed in a 2: 1 ratio by the reaction of the carbonate with the acid and the reaction of the carbon dioxide with the base, respectively.

[0055] In the example embodiment shown in Figure 4, the acid stream from the hydroxide pump 100 is used to increase the rate of limestone dissolution, which reduces the required residence time of the process. The basic stream is used to buffer the final solution, such that the excess CO2 is less likely to exsolve. The final pH can be near, at, or above ambient ocean pH. In some embodiments, the final pH can be near, at, or above ambient pH of a body of water that the solution is to be delivered to. For example, the pH can be controlled to reach a threshold pH. The threshold pH can be pre-determined.EXAMPLE 5:Application of Hydroxide Pump for Neutralization Using a Base from the Hydroxide Pump

[0056] According to embodiments of the present disclosure, as shown in Figure 5, base from a basic stream produced by acid-base generator 110 of hydroxide pump 100 is provided to a neutralization vessel in which bi-carbonate-rich water from the dissolution vessel is also received.

[0057] The base can be used to achieve a desired pH level in neutralization vessel. This can allow the eventual output from the system (effluent) to match the pH of the seawater (or be within a desired amount) that the output is to be released into.

[0058] In the example embodiment shown in Figure 5, the basic stream is used to buffer the final solution, such that the excess CO2 is less likely to exsolve. The final pH can be near, at, or above ambient ocean pH or at a desired threshold pH. The acid stream from hydroxide pump 100 is treated as a waste stream and neutralized with limestone. Any excess CO2 produced from the process is captured with the remaining (approximately half) base stream in the hydroxide pump.EXAMPLE 6:of Hydroxide Pump for Carbon Dioxidea Base from the

[0059] According to embodiments of the present disclosure, as shown in Figure 6, base from a basic stream produced by acid-base generator 110 of hydroxide pump 100 is provided to a carbon dioxide absorption column (or other carbon dioxide extraction device or an input vessel) that is configured to extract carbon dioxide from flue gas or other input gas stream.

[0060] The base is reacted with carbon dioxide gas to produce bicarbonate. The bicarbonate is provided to a vessel containing a bicarbonate-rich solution, which can be outputted as effluent into seawater, for example. The vessel containing bicarbonate-rich solution can also receive discharge or output from hydroxide pump 100, in some embodiments.

[0061] In the example embodiment shown in Figure 6, the AWL process is replaced by using the basic stream to capture the CO2 and using the limestone to neutralize the waste acid that is produced. This can reduce water consumption significantly.EXAMPLE 7:Application of Hydroxide Pump for Carbon Dioxide Sequestration and for Neutralization Using a Base from the Hydroxide Pump

[0062] According to embodiments of the present disclosure, as shown in Figure 7, base from a basic stream produced by acid-base generator 110 of hydroxide pump 100 is provided to a neutralization vessel in which carbonate from the dissolution vessel is also received. The carbonate is reacted with excess carbonic acid in the neutralization vessel to produce bicarbonate. This can advantageously raise the pH, reducing the need to off gas CO2 and decreasing the water requirement per ton of captured and converted CO2using hydroxide pump 100 to effectively enhance the efficacy of a carbon capture system.

[0063] Base from the basic stream produced by acid-base generator 110 of hydroxide pump 100 is also provided to a secondary absorber column that receives outputted flue gas from a carbon dioxide absorption column (or other carbon dioxide extraction device or an input vessel) that is configured to extract carbon dioxide from flue gas or other input gas stream. The base is reacted with the outputted carbon dioxide that remains in the flue gas at the secondary absorber column to produce bicarbonate-rich water.

[0064] The bicarbonate-rich water from the secondary column is provided to a vessel containing a bicarbonate-rich solution, which can be outputted as effluent into seawater, for example. The vessel containing bicarbonate-rich solution can also receive discharge or output from hydroxide pump 100 as well as from a neutralization vessel (that receives output from the limestone dissolution vessel and receives base from hydroxide pump 100), in some embodiments.

[0065] The device is configured to release lean flue gas, which has less carbon dioxide gas, thereby improving carbon capture and sequestration, according to some embodiments.

[0066] In the example embodiment shown in Figure 7, the basic stream is used to buffer the final solution, such that the excess CO2 is less likely to exsolve. The final pH can be near, at, or above ambient ocean pH or at a desired threshold pH. The acid stream from hydroxide pump 100 is treated as a waste stream and neutralized with limestone. Excess CO2 produced from the process is captured with the remaining base stream from hydroxide pump 100. Excess base is used to capture CO2 that remains in the flue gas after the AWL capture step. This allow capture rates to increase to above 90%, according to some embodiments.

[0067] Table 1 shows estimated comparison data between an AWL process and each of the embodiments shown in Figure 4, Figure 5, Figure 6, and Figure 7.Table 1. Estimated Comparison Data Between AWL and Embodiments of Figures 4, 5, 6, and 7.FURTHER EXAMPLESOther Applications

[0068] Hydroxide pump 100 can be used with a variety of other applications, such as to consume unwanted acid by-product of electrolytic processes, consume unwanted acid, dissolve calcium or other carbonates (e.g., limestone, dolomite, calcite, aragonite, etc.), increase the rate of its dissolution, react with carbon dioxide such as for carbon capture, produce excess hydroxide, increase the pH of a solution, and / or other applications. For example, carbon dioxide removal can involve using electrolytic processes to produce hydroxide to capture CO2 in the ocean, but a major problem in existing solutions that do not use hydroxide pump 100 is that all the acid that is created cannot be disposed. Embodiments of hydroxide pump 100 can provide a feasible method of consuming the acid for safe disposal into the ocean.

[0069] The disclosures of all patents, patent applications, publications and database entries referenced in this specification are hereby specifically incorporated by reference in their entirety to the same extent as if each such individual patent, patent application, publicationand database entry were specifically and individually indicated to be incorporated by reference.

[0070] Although embodiments have been described with reference to certain specific embodiments, various modifications thereof will be apparent to those skilled in the art without departing from the spirit and scope of the disclosure. All such modifications as would be apparent to one skilled in the art are intended to be included within the scope of the following claims.

Claims

AMENDED CLAIMS received by the International Bureau on 12 December 2025 (12.12.2025)1. A method of capturing and sequestering carbon dioxide from a gas stream comprising a hydroxide pump, wherein the hydroxide pump carries out the following steps: producing a basic stream and an acidic stream from a solution by separating protons (H+) and hydroxide ions (OH") in the solution; reacting carbonate with a first acid from the acidic stream to increase a dissolution rate of the carbonate to produce bicarbonate; and reacting carbon dioxide with a base from the basic stream to produce bicarbonate, the carbon dioxide derived from the reaction of the first acid with the carbonate.

2. The method of claim 1, wherein the basic stream and the acidic stream are produced by electrodialysis.

3. The method of claim 2, wherein the basic stream and the acidic stream are produced using an electrochemical membrane.

4. The method of claim 2, wherein the basic stream and the acidic stream are produced using a reversible photoacid system.

5. The method of any one of claims 1 to 4, wherein the solution is saltwater.

6. The method of any one of claims 1 to 5, wherein the basic stream comprises a strong base and the acidic stream comprises a strong acid.

7. The method of any one of claims 2, 3, 5, and 6, wherein the basic stream and the acidic stream are produced from the electrodialysis of salt water using an electrochemical membrane, the salt water comprising H2O and NaCl, the basic stream comprising OH", and the acidic stream comprising H+.

8. The method of any one of claims 2, 4, 5, and 6, wherein the basic stream and the acidic stream are produced from the electrodialysis of salt water using a photoacid system, the salt water comprising H2O and NaCl, the basic stream comprising OH", and the acidic stream comprising H+.

9. The method of any one of claims 1 to 8, wherein the base is included in a first subsfream from the basic stream and excess base from the basic stream is included in a second substream.

10. The method of claim 9, wherein the excess base from the basic stream is mixed with output produced from accelerated weathering of limestone to increase pH of the output.

11. The method of claim 9 or 10, wherein the excess base from the basic stream is reacted with carbon dioxide gas from a carbon dioxide gas stream to produce bicarbonate.

12. The method of any one of claims 1 to 11, wherein the acidic stream lowers or maintains the pH of the carbonate at less than 5.

13. The method of any one of claims 1 to 12, wherein the base from the basic stream and the first acid from the acidic stream are produced in a 1: 1 ratio, and wherein the first acid from the acidic stream and the base from the basic stream are consumed in a 2: 1 ratio by the reaction of the carbonate with the first acid and the reaction of the carbon dioxide with the base, the carbon dioxide being derived from the reaction of the first acid with the carbonate, respectively.

14. The method of any one of claims 1 to 13, wherein the carbonate comprises calcite, dolomite, aragonite, potassium carbonate, or magnesium carbonate.

15. The method of any one of claims 1 to 14, wherein a second acid is derived from the hydration of carbon dioxide from a carbon dioxide gas stream and the second acid reacts with the carbonate to produce bicarbonate.

16. The method of any one of claims 1 to 15, wherein the carbon dioxide is captured in a vessel and the base from the basic stream is reacted with the carbon dioxide in the vessel, the carbon dioxide being derived from the reaction of the first acid with the carbonate.

17. A hydroxide pump for carbon dioxide sequestration, comprising: an acid-base generator configured to receive a solution and produce a basic stream and an acidic stream from the solution by separating protons (H+) and hydroxide ions (OH") in the solution; an acid neutralizer configured to receive carbonate and the acidic stream from the acid-base generator, wherein the carbonate reacts with a first acid from the acidic stream to increase a dissolution rate of the carbonate to produce bicarbonate; and a vessel for capturing carbon dioxide off-gas from the acid neutralizer, the vesselconfigured to receive at least half of the basic stream from the acid-base generator wherein the carbon dioxide off-gas reacts with abase from the basic stream to produce bicarbonate.

18. The hydroxide pump of claim 17, wherein the basic stream and the acidic stream are produced by electrodialysis.

19. The hydroxide pump of claim 18, wherein the acid-base generator comprises an electrochemical membrane.

20. The hydroxide pump of claim 18, wherein the acid-base generator comprises a reversible photoacid system.

21. The hydroxide pump of any one of claims 17 to 20, wherein the solution is saltwater.

22. The hydroxide pump of any one of claims 17 to 21, wherein the basic stream comprises a strong base and the acidic stream comprises a strong acid.

23. The hydroxide pump of any one of claims 18, 19, 21, and 22, where the basic stream and the acidic stream are produced from the electrodialysis of salt water using an electrochemical membrane, the salt water comprising H2O and NaCl, the basic stream comprising OH", and the acidic stream comprising H+.

24. The hydroxide pump of any one of claims 18, 20, 21, and 22, wherein the basic stream and the acidic stream are produced from the electrodialysis of salt water using a photoacid system, the salt water comprising H2O and NaCl, the basic stream comprising OH", and the acidic stream comprising H+.

25. The hydroxide pump of any one of claims 17 to 24, wherein the base is included in a first subsfream from the basic stream and excess base from the basic stream is included in a second substream.

26. The hydroxide pump of claim 25, wherein excess base from the basic stream is mixed with output produced from accelerated weathering of limestone to increase pH of the output.

27. The hydroxide pump of claims 25 or 26, wherein excess base from the basic stream is reacted with carbon dioxide gas from a carbon dioxide gas stream to produce bicarbonate.

28. The hydroxide pump of any one of claims 17 to 1 wherein the acidic stream lowers or maintains the pH of the carbonate at less than 5.

29. The hydroxide pump of any one of claims 17 to 28, wherein the base from the basic stream and the first acid from the acidic stream are produced in a 1: 1 ratio, and wherein the first acid from the acidic stream and the base from the basic stream are consumed in a 2: 1 ratio by the reaction of the carbonate with the first acid and the reaction of the carbon dioxide with the base, the carbon dioxide being derived from the reaction of the first acid with the carbonate, respectively.

30. The hydroxide pump of any one of claims 17 to 29, wherein the carbonate comprises calcite, dolomite, aragonite, potassium carbonate, or magnesium carbonate.

31. The hydroxide pump of any one of claims 17 to 30, further comprising an accelerated limestone weathering apparatus configured to react a second acid derived from the hydration of carbon dioxide from a carbon dioxide gas stream with the carbonate to produce bicarbonate.

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