AU2009290161A1 - Electrochemical production of an alkaline solution using CO2 - Google Patents

Description

INTERNATIONAL PATENT APPLICATION ELECTROCHEMICAL PRODUCTION OF AN ALKALINE SOLUTION USING C02 Inveptor(s): Ryan J. Gilliam 350 Budd Avenue, Unit M-11, Campbell, CA 95008 (Citizen of Canada) Valentin Decker 1342 Sherman Avenue, Menlo Park, CA 94025 (Citizen of U.S.A.) Nigel Antony Knott 350 Budd Avenue, Unit L-10, Campbell, CA 95008 (Citizen of Canada) Michael Kostowskyj 350 Budd Avenue, Unit L-10, Campbell, CA 95008 (Citizen of Canada) Bryan Boggs 225 Union Avenue, Apt.#148, Campbell, CA 95008 (Citizen of U.S.A.) Entity: Small Business Concern C CALERA Green Cement for a Blue Planet 14600 Winchester Blvd, Los Gatos, California 95032 (408) 340-4600 (Main) (408) 340-4650 (Facsimile) Filed Electronically on: November 12, 2009 LECTROCHEMICAL PRODUCTION OF AN ALKALINE SOLUTION USING CO 2 CROSS-REFERENCE 10001] This application is a continuation-in-part of, and claims priority to, US Patent Application No. 5 12/541,055 f led on August 13, 2009, titled "Gas Diffusion Anode and CO 2 Cathode Electrolyte System" which is a ccntinuation-in-part of US Patent Application No. 12/503557 filed on July 16, 2009, titled: "C02 Utilization In Electrochemical Systems", both of which are herein incorporated by reference in their entirety. 10 BACKGROUND OF THE INVENTION [00021 In nany chemical processes an alkaline solution is required to achieve a chemical reaction, e.g., to neutralize an acid, or buffer the pH of a solution, or precipitate an insoluble hydroxide and/or carbonate and/or bicarbonate from a solution. One method by which the alkaline solution is produced is by an electrochemi al system as disclosed in the above-referenced US patent applications, herein incorporated 15 by reference in their entirety. In producing an alkaline solution electrochemically, a large amount of energy, salt ind water may be used; consequently, lowering the energy and material used is highly desired. An Ilkaline solution includes a solution comprising hydroxide ions, and/or carbonate ions, and/or bicarbonate ons. 20 SUMMARY OF THE INVENTION [00031 in one embodiment, this invention pertains to an electrochemical system comprising a cathode electrolyte comprising added carbon dioxide, and contacting a cathode; and a first cation exchange m mbrane separating the cathode electrolyte from an anode electrolyte contacting an anode. In another emb diment, the invention pertains to an electrochemical method comprising adding carbon 25 dioxide into a cathode electrolyte separated from an anode electrolyte by a first cation exchange membrane; and producing an alkaline solution in the cathode electrolyte without producing a gas at the anode in co tact with the anode electrolyte. In another embodiment, the invention pertains to a method comprising producing an acid in an electrochemical system comprising added carbon dioxide in the cathode electrolyte; and contacting a mineral with the acid. 30 [0004] in some embodiments, the system comprises a second cation exchange membrane contacting the anode electrolyte; the carbon dioxide is contained in a waste gas; the waste gas comprises emissions fr m an electrical power generating plant, a cement plant, an ore processing facility or a fermentation system; atmospheric carbon dioxide is excluded from the cathode electrolyte; the cathode electrolyte is operatively connected to the industrial facility; the pH of the cathode electrolyte is 7 and 35 above; the pi of the cathode electrolyte is between 7 and 14; the pH of the cathode electrolyte is between 7 and 9; the H of the cathode electrolyte is between 8 and 11; the pH of the anode electrolyte is less than 7; the p of the anode electrolyte is less than 4; the cathode electrolyte comprises hydroxide ions and/or bicarbonate ions and/or carbonate ions; the cathode electrolyte comprises sodium ions; the cathode ele trolyte is operatively connected to a carbonate and/or bicarbonate precipitator; the 40 carbonates and/or bicarbonates comprise calcium and/or magnesium; hydrogen is oxidized at the anode; the cathode s configured to produce hydrogen gas; a gas delivery system is configured to direct hydrogen -2gas from the cathode to the anode; the anode electrolyte comprises an acid and a salt solution; the salt solution co prises sodium ions and chloride ions; the system is configured to produce hydrogen ions at the anode with less than 1V across the anode and cathode, without producing a gas at the anode; the system is co figured to migrate hydrogen ions into the anode electrolyte; the system is configured to 5 produce hyd oxide ions at the cathode; the system is configured to migrate hydroxide ions into the cathode electrolyte; the system is configured to migrate cations from the anode electrolyte into the cathode electrolyte; the cations comprise sodium ions; the anode electrolyte is operatively connected to a mineral dissolution system configured to dissolve minerals; the mineral solution comprises calcium ions and/or mag esium ions; the minerals comprises mafic minerals; the mineral dissolution system is 10 operatively connected to a separator configured to separate sodium ions and chloride ions from the mineral solu ion; a concentrator is configured to concentrate sodium ions and chloride ions into a salt solution. [00051 n some embodiments, the method comprises applying a voltage across the cathode in contact with he cathode electrolyte and the anode in contact with the anode electrolyte, wherein a gas is 15 not produced at the anode; and wherein the voltage is less than 1V; and wherein the anode comprises a second caticn exchange membrane contacting the anode electrolyte. In some embodiments, the method comprises p oducing hydroxide ions and/or bicarbonate ions and/or carbonate ions in the cathode electrolyte; therein the carbon dioxide is contained in a waste gas, e.g., an industrial waste gas; wherein the waste g s is emitted from an industrial plant; wherein the industrial plant comprises an electrical 20 power gene ting plant, a cement production plant or an ore processing facility and the like; wherein carbon dioxide in ambient air is excluded from the cathode electrolyte. In some embodiments, the method comprises maintaining a pH of 7 or greater in the cathode electrolyte; maintaining a pH of between 7 and 9 in the cath de electrolyte; maintaining a pH of between 8 and 11 in the cathode electrolyte; maintaining a pH of less han 7 in the anode electrolyte; maintaining a pH of less than 4 in the anode electrolyte; 25 oxidizing hydrogen gas at the anode to produce hydrogen ions; migrating the hydrogen ions through the second cation exchange membrane into the anode electrolyte; producing hydroxide ions and hydrogen gas at the cathode and migrating hydroxide ions into the cathode electrolyte; directing hydrogen gas from the cathode o the anode; migrating cations ions through the first cation exchange membrane into the cathode ele trolyte, wherein the cations comprise sodium ions; and producing an acid in the anode 30 electrolyte. [00061 n some embodiments, the method comprises producing an acid in the anode electrolyte, without genE rating a gas at the anode; oxidizing hydrogen gas at the anode; wherein the acid produced comprises h drochloric acid; producing hydrogen gas at the cathode; producing an alkaline solution in the cathode elet trolyte; migrating sodium ions into the cathode electrolyte; wherein the alkaline solution 35 comprises sodium hydroxide, sodium bicarbonate and/or sodium carbonate; the voltage is less than 1V; the anode electrolyte is separated from the cathode electrolyte by first cation exchange membrane; the anode comp ises a second cation exchange membrane in contact with the anode electrolyte; the anode electrolyte comprises a salt; the salt comprises sodium chloride. In some embodiments, the method comprises d ssolving a mineral with the acid to produce a mineral solution; producing calcium ions and/or 40 magnesium ons; the mineral comprises a mafic mineral; and the mineral solution is filtered to produce a filtrate comp-ising sodium ions and chloride ions solution. In other embodiments, the method includes; -3concentrati g the filtrate to produce a salt solution; utilizing the salt solution as the anode electrolyte; precipitating a carbonate and/or bicarbonate with the cathode electrolyte, wherein the carbonate and/or bicarbonate comprises calcium and/or magnesium carbonate and/or bicarbonate. [0007] Ac rdingly, with the system and method, by selectively placing ion exchange membranes, e.g., 5 cation exch nge membranes, between the anode electrolyte and the cathode electrolyte; and by controlling the voltage across the anode and cathode, e.g., maintaining less than 2V; and by controlling the pH of th cathode electrolyte and/or the anode electrolyte; and by oxidizing hydrogen gas at the anode with ut producing a gas at the anode, an alkaline solution comprising hydroxide ions and/or carbonate ions and/or bicarbonate ions is produced in the cathode electrolyte; hydrogen gas is produced 10 at the catho e; hydrogen ions are produced at the anode from hydrogen gas supplied to the anode, without proc ucing a gas at the anode, and hydrogen ions are migrated into an electrolyte, e.g., the anode electrolyte, o produce an acid in the anode electrolyte. In various embodiments, utilizing hydrogen gas at the anode f om hydrogen generated at the cathode, eliminates the need for an external supply of hydrogen; consequently, the overall utilization of energy by the system to produce the alkaline solution is 15 reduced. [00081 In some embodiments, the alkaline solution produced is utilized to sequester carbon dioxide, e.g., from industrial waste gases, into cementitous carbonate materials as disclosed, for example, in US Patent Appl cation no. 12/126,776 filed on May 23, 2008 and titled "Hydraulic Cements Comprising Carbonate Compound Compositions", herein incorporated by reference in its entirety. 20 [00091 A vantageously, with the present system and method, since a relatively low voltage is utilized across the znode and cathode to produce the alkaline solution, and since hydrogen generated at the cathode is L tilized at the anode, a relatively low amount of energy is utilized to produce the alkaline solution. Al o, by the system and method, since carbon dioxide from industrial waste gases is utilized to produce the alkaline solution, the system and method can be utilized to sequester large amounts of 25 carbon diox de and thus reduce carbon dioxide emissions into the atmosphere. Further, the acid produced can be utilized in various ways including dissolving materials, e.g., minerals and biomass. BRIEF DESCRIPTION OF THE DRAWINGS 100101 The following drawings illustrate by way of examples and not by limitation some embodiments 30 of the present system and method. [00111 Fig. 1 is an illustration of an embodiment of the present system. [00121 Fig. 2 is an illustration of an embodiment of the anode portion of the system. [00131 Fig. 3 is a flow chart of an embodiment of the method. [00141 Fig. 4 is an illustration of an embodiment of the system. 35 [00151 Fig. 5 is an illustration of the carbonate/bicarbonate ion speciation in H 2 0 v. the pH of the solution at 25 OC. [0016] Fig. 6 is an illustration of a voltage difference across the anode and cathode v. pH of the cathode electrolyte in an embodiment of the system. [0017] Fig. 7 is an illustration of an embodiment of the system. 40 [00181 Fig. 8 is an illustration of an embodiment of the system. -4- [00191 Fig. 9 is an illustration of an embodiment of the system. [00201 Fig. 10 is a flow chart of an embodiment of the method. [00211 Fig. 11 is a flow chart of an embodiment of the method. 5 DETAILED DESCRIPTION OF THE INVENTION [0022] rhis invention provides systems and methods for an electrochemical production of an alkaline solution in a cathode electrolyte and an acid in an electrolyte, e.g., the anode electrolyte. In various embodiments, carbon dioxide is added to the cathode electrolyte and a gas is not produced at the anode; 10 in various embodiments, an alkaline solution comprising, e.g., sodium hydroxide and/or sodium carbonate and/or sodiu bicarbonate is produced in the cathode electrolyte. In various embodiments, a salt solution comprising, .g., sodium chloride, is used as the anode electrolyte to produce the alkaline solution. Also, as described herein, an acid solution, e.g., hydrochloric acid, is produced in the anode electrolyte by hydrogen iods migrating from the anode into the anode electrolyte, and with cations, e.g., chloride ions, 15 present in thi anode electrolyte. [00231 n some embodiments, the acid solution produced is utilized to dissolve a mineral, e.g., serpentine o olivine, to obtain a divalent cation solution, e.g., calcium and magnesium ion solution, which may in somE embodiments be used with the alkaline solution to precipitate carbonates and/ or bicarbonate derived from carbon dioxide in a waste gas stream, e.g., carbon dioxide in the exhaust 20 gases of a fossil fuelled power generating plant or a cement producing plant. In some embodiments, a sodium chloride solution is used as the anode electrolyte. [0024] Also, as disclosed herein, on applying a voltage across the anode and cathode, cations, e.g., sodium ions in the anode electrolyte, migrate from the anode electrolyte through the first cation exchange membrane into the cathode electrolyte to produce an alkaline solution comprising, sodium hydroxide 25 and/or sodiu carbonate and/or sodium bicarbonate in the cathode electrolyte; and anions in the anode electrolyte, E.g., chloride ions, and hydrogen ions migrated from the anode to produce an acid, e.g., hydrochloric acid in the anode electrolyte. [00251 -urther, as described herein, hydrogen gas and hydroxide ions are produced at the cathode, and in some embodiments, some or all of the hydrogen gas produced at the cathode is directed to the 30 anode wher it is oxidized to produce hydrogen ions. [00261 However, as can be appreciated by one ordinarily skilled in the art, since the present system and method can be configured with an alternative, equivalent salt solution in the anode electrolyte, e.g., a potassium sulfate solution, to produce an equivalent alkaline solution, e.g., potassium hydroxide and/or potassium carbonate and/or potassium bicarbonate in the cathode electrolyte, and an equivalent acid, 35 e.g., sulfuriciacid in the anode electrolyte, by applying the voltage as disclosed herein across the anode and cathode, the invention is not limited to the exemplarary embodiments described herein, but is adaptable for use with an equivalent salt solution, e.g., potassium sulfate, to produce an alkaline solution in the catho e electrolyte, e.g., potassium carbonate and/or potassium bicarbonate and an acid, e.g., sulfuric acid in the anode electrolyte. 40 [00271 Accordingly, to the extent that such equivalents are based on or suggested by the present system and method, these equivalents are within the scope of the appended claims. -5- 100281 Nith reference to Fig. 7, in one embodiment, the system 700 comprises a cathode 106 in contact with a cathode electrolyte 108 comprising added carbon dioxide 107, wherein the cathode electrolyte is separated from an anode electrolyte 104 by first cation exchange membrane 116. In an embodiment as is illustrated in Fig. 8, the system 800 comprises an anode 102 that is separated from the 5 anode electr lyte by a second cation exchange membrane 122 that is in contact with the anode 102. 100291 n systems 700, 800 as illustrated in Figs. 7 and 8, the first cation exchange membrane 116 is located be een the cathode 106 and anode 102 such it separates the cathode electrolyte 108 from the anode electrolyte 104. Thus as is illustrated in Figs. 7 and 8, on applying a relatively low voltage, e.g., less than 2V or Iss than 1V, across the anode 102 and cathode 106, hydroxide ions (OH~) and hydrogen gas 10 (H 2 ) are pro uced at the cathode 106, and hydrogen gas is oxidized at the anode 102 to produce hydrogen io s at the anode 102, without producing a gas at the anode. In certain embodiments, the hydrogen gas produced at the cathode is directed to the anode through a hydrogen gas delivery system 112, and is oxidized to hydrogen ions at the anode. In various embodiments, utilizing hydrogen gas at the anode from hydrogen generated at the cathode, eliminates the need for an external supply of hydrogen, 15 consequentl , the utilization of energy by the system to produce the alkaline solution is reduced. [00301 n certain embodiments as illustrated in Figs. 7 and 8, under the applied voltage 114 across the anode 1 2 and cathode 106, hydroxide ions are produced at the cathode 106 and migrate into the cathode electrolyte 108, and hydrogen gas is produced at the cathode. In certain embodiments, the hydrogen gas produced at the cathode 106 is collected and directed to the anode, e.g., by a hydrogen gas 20 delivery system 122, where it is oxidized to produce hydrogen ions at the anode. Also, as illustrated in Figs. 7 and , under the applied voltage 114 across the anode 102 and cathode 106, hydrogen ions produced at the anode 102 migrate from the anode 102 into the anode electrolyte 104 to produce an acid, e.g., hydrochloric acid. [00311 n certain embodiments, the first cation exchange membrane 116 is selected to allow passage 25 of cations th rethrough while restricting passage of anions therethrough. Thus, as is illustrated in Figs.7 and 8, on applying the low voltage across the anode 102 and cathode 106, cations in the anode electrolyte 1 4 , e.g., sodium ions in the anode electrolyte comprising sodium chloride, migrate into the cathode elect trolyte through the first cation exchange membrane 116, while anions in the cathode electrolyte 1 )8, e.g., hydroxide ions, and/or carbonate ions, and/or bicarbonate ions, are prevented from 30 migrating frcm the cathode electrolyte through the first cation exchange membrane 116 and into the anode elect lyte 104. 100321 rhus, as is illustrated in Figs. 7 and 8, where the anode electrolyte 104 comprises an aqueous sal solution such as sodium chloride in water, a solution, e.g., and alkaline solution, is produced in the catho e electrolyte 108 comprising cations, e.g., sodium ions, that migrate from the anode 35 electrolyte 1 4, and anions, e.g., hydroxide ions produced at the cathode 106, and/or carbonate ions and or bicarbonate ions produced by dissolving carbon dioxide 107 in the cathode electrolyte. [0033] :oncurrently, in the anode electrolyte 104, an acid, e.g., hydrochloric acid is produced from hydrogen ions migrating from the anode 102 and anions, e.g., chloride ions, present from the anode electrolyte. 40 [00341 Nith reference to Fig. 8, an anode comprising a second cation exchange membrane 122 is utilized to s parate the anode 102 from the anode electrolyte 104 such that on a first surface, the cation -6exchange m 1 mbrane 122 is in contact with the anode 102, and an opposed second surface it is in contact with the ano Je electrode electrolyte 104. Thus, as can be appreciated, in this embodiment, since the second caticn exchange membrane is permeable to cations, e.g., hydrogen ions, the anode is in electrical contact with the anode electrolyte through the second cation exchange membrane. In some 5 embodiments, the anode as illustrated in Fig. 8 may comprise a gas diffusion anode as described below. [00351 Thus, in the embodiment of Fig. 8, as with the embodiment illustrated in Fig.7, on applying the low voltage across the anode 102 and cathode 106, hydrogen ions produced at the anode 102 from oxidation of ydrogen gas at the anode migrate through the second cation exchange membrane 122 into the anode e ctrolyte 104. At the same time, cations in the anode electrolyte, e.g., sodium ions in the 10 anode electrolyte comprising sodium chloride, migrate from the anode electrolyte 104 into the cathode electrolyte 108 through the first cation exchange membrane 116, while anions in the cathode electrolyte 108, e.g., hydroxide ions, and/or carbonate ions, and/or bicarbonate ions, are prevented from migrating from the cathode electrolyte 108 to the anode electrolyte 104 through the first cation exchange membrane 116. 15 [00361 PIso, in the embodiment as illustrated in Fig. 8, hydrogen ions migrating from the anode 102 through the econd cation exchange membrane 122 into the anode electrolyte 104 will produce an acid, e.g., hydrochloric acid with the cations, e.g., chloride ions, present in the anode electrolyte; and in the cathode electrolyte 108, an alkaline solution is produce from cations present in the cathode electrolyte and anions, a.g., sodium ions, that migrate from the anode to the cathode electrolyte through the first 20 cation exch nge membrane 116. [00371 n some embodiments, cation exchange membranes 116 and 122 are conventional and are available fro , for example, Asahi Kasei of Tokyo, Japan; or from Membrane International of Glen Rock, NJ, or DuPont, in the USA. However, it will be appreciated that in some embodiments, depending on the need to rest ict or allow migration of a specific cation or an anion species between the electrolytes, a 25 cation exch nge membrane that is more restrictive and thus allows migration of one species of cations while restric ing the migration of another species of cations may be used as, e.g., a cation exchange membrane t at allows migration of sodium ions into the cathode electrolyte from the anode electrolyte while restric ing migration of hydrogen ions from the anode electrolyte into the cathode electrolyte, may be used. Such estrictive cation exchange membranes are commercially available and can be selected by 30 one ordinari y skilled in the art. [00381 As is illustrated in Fig. 8, the anode 102 comprises a second cation exchange membrane 112 that separat s the anode 102 from the anode electrolyte 104 and is attached to the anode. Thus, in some embodimen s, the anode and second cation exchange membrane may comprise an integral gas diffusion anode that is commercially available, or can be fabricated as described for example in co-pending and 35 commonly assigned US Provisional Patent Application no. 61/151,484, titled "Electro-catalyst Electrodes for Low-voltage electrochemical Hydroxide System", filed February 10, 2009, herein fully incorporated by reference. However, as can be appreciated by one ordinarily skilled in the art, notwithstanding that a gas diffusion andde is illustrated and utilized in Figs. 7 and 8 and described herein, in the some embodiments, any convent onal anode that can be configured to oxidize hydrogen gas to produce hydrogen ions as 40 described h rein can be utilized. -7- [00391 With reference to Fig. 7 and 8, in some embodiments, the cathode electrolyte 108 is operatively connected to a supply of carbon dioxide gas 107, contained, e.g., in an industrial plant, e.g., a power generating plant, a cement plant, or an ore smelting plant. If necessary, this source of carbon dioxide comprises a gas wherein the concentration of carbon dioxide is greater than the concentration of carbon 5 dioxide in the ambient atmosphere. This source of carbon dioxide may also contain other gaseous and non-gaseou components of a combustion process, e.g., nitrogen gas, SOx, NOx, as is described in co pending and commonly assigned US Provisional Patent application no. 61/223,657, titled "Gas, Liquids, Solids Contacting Methods and Apparatus", filed July 7, 2009 herein fully incorporated by reference. However, as can be appreciated, this source of carbon dioxide can be cleaned and utilized as the carbon 10 dioxide added to the cathode electrolyte 108. [00401 Allhough carbon dioxide is present in ordinary ambient air, in view of its very low concentration, ambient car on dioxide may not provide sufficient carbon dioxide to achieve the results obtained with the present system and method that utilize carbon dioxide taken from an industrial waste gas steam, e.g., from the stapk gases of a fossil fuelled power generating plant or a cement production plant. Also, in some 15 embodimen s of the system and method, since the cathode electrolyte is contained in closed system wherein the pressure of the added carbon dioxide gas within the system is greater than the ambient atmospheri pressure, ambient air and hence ambient carbon dioxide is typically prevented from infiltrating in o the cathode electrolyte. [00411 In some embodiments, and with reference to Figs. 5 - 8, carbon dioxide is added to the cathode 20 electrolyte to dissolve and produce carbonic acid that dissociates to hydrogen ions and carbonate ions and/or bicarbonate ions, depending on the pH of the cathode electrolyte. Concurrently, as described above, hydr xide ions, produced from electrolyzing water in the cathode electrolyte, may react with the hydrogen ions to produce water in the cathode electrolyte. Thus, depending on the degree of alkalinity desired in the cathode electrolyte, the pH of the cathode electrolyte may be adjusted and in some 25 embodiments is maintained between and 7 and 14 or greater; or between 7 and 9; or between 8 and 11 as is well un derstood in the art, and as illustrated in carbonate speciation diagram of Fig. 5. In some embodiments, the pH of the cathode electrolyte may be adjusted to any value between 7 and 14 or greater, including a pH 7.0, 7.5, 8.0, 8.5. 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12.0, 12.5, 13.0, 13.5, 14.0 and greater. 30 [00421 Sirilarly, in some embodiments of the system, the pH of the anode electrolyte is adjusted and is maintained etween less than 0 and up to 7 and/or between less than 0 and up to 4, by regulating the concentration of hydrogen ions that migrate into the anode electrolyte from oxidation of hydrogen gas at the anode, and/or the withdrawal and replenishment of anode electrolyte in the system. In this regard and as can be appreciated by one ordinarily skilled in the art and with reference to Fig. 6, since the voltage 35 across the anode and cathode is dependent on several factors including the difference in pH between the anode elect olyte and the cathode electrolyte as can be determined by the Nerst equation, in some embodiments, the pH of the anode electrolyte is adjusted to a value between 0 and 7, including 0, 0.5, 1.0, 1.5, 2.0 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5 and 7, depending on the desired operating voltage across the anode and cathode. Thus, as can be appreciated, in equivalent systems, where it is desired to 40 reduce the Energy used and/ or the voltage across the anode and cathode, e.g., as in the Chloralkali process, carbon dioxide can be added to the electrolyte as disclosed herein to achieve a desired pH -8difference bEtween the anode electrolyte and cathode electrolyte. Thus, to the extent that such systems utilize carbon dioxide, these equivalent systems are within the scope of the present invention. [00431 Wit reference to Fig. 7 and 8, in some embodiments, the anode electrolyte 102 comprises a salt solution that includes sodium ions and chloride ions; the system 700, 800 is configured to produce the 5 alkaline solu ion in the cathode electrolyte 108 while also producing hydrogen ions at the anode 106, with less than 1V across the anode 122 and cathode 106, without producing a gas at the anode; the system 700, 800 is configured to migrate hydrogen ions from the anode into the anode electrolyte; the anode electrolyte comprises an acid; the system 700, 800 is configured to produce bicarbonate ions and/or carbonate io s in the cathode electrolyte 108; migrate hydroxide ions from the cathode 106 into the 10 cathode electrolyte; migrate cations, e.g., sodium ions, from the anode electrolyte 104 into the cathode electrolyte t rough the first cation exchange membrane 116; hydrogen gas is provided to the anode; and a hydrogen gas delivery system 112 is configured to direct hydrogen gas from the cathode to the anode. [0044] With reference to Figs. 7 - 9, in some embodiments the cathode electrolyte 108 may be operatively connected to a system for further processing of the cathode electrolyte, e.g., a carbonate 15 and/or bicarbonate precipitating system 912 comprising a precipitator configured to precipitate carbonates and/or bicarbonates from a solution, wherein in some embodiments the carbonates and/or bicarbonates comprise ca cium and/or magnesium carbonate and/or bicarbonate. Also as illustrated in Fig. 9, in some embodiments, the anode electrolyte 104 comprising an acid, e.g., hydrochloric acid, and a depleted salt solution comprising low amount sodium ions, is operatively connected to a system for further processing 20 of an acid, e g., a mineral dissolution system 904 that is configured to dissolve minerals and produce a mineral solu ion comprising calcium ions and/or magnesium ions, e.g., mafic minerals such as olivine and serpentine. In some embodiments, not shown in Fig. 9, the acid may used for other purposes in addition to or instead of mineral dissolution. Such use includes use as a reactant in production of cellulosic biofules, use the production of polyvinyl chloride (PVC), and the like. System appropriate to such uses 25 may be operatively connected to the electrochemistry unit, or the acid may be transported to the appropriate site for use. [0045] In the some embodiments, the mineral dissolution system 904 is operatively connected to nano filtration sys em 910 that is configured to separate sodium ions and chloride ions from the mineral solution comprising, .g., calcium ions, magnesium ions, silica, hydrochloric acid and/or sodium hydroxide. In 30 some embodiments, the nano-filtration system 910 is configured with a reverse osmosis system 914 that is capable o concentrating sodium ions and chloride ions into a salt solution that is used as the anode electrolyte 134 . [0046] With reference to Figs. 1 - 10, the method 1000 in some embodiments comprises a step 1002 of adding carbon dioxide into a cathode electrolyte 108 in contact with a cathode 106 wherein the cathode 35 electrolyte is separated from an anode electrolyte 104 by a first cation exchange membrane 116; and producing an alkaline solution in the cathode electrolyte by applying a voltage 114 of less that 1V across the cathode 106 and an anode 102 in contact with the anode electrolyte without producing a gas at the anode. [00471 In some embodiments of the method 1000, the anode 102 is in contact with a second cation 40 exchange membrane 122 that separates the anode from the anode electrolyte; the alkaline solution 108 comprises h droxide ions and/or bicarbonate ions and/or carbonate ions; the carbon dioxide 107 is -9contained in wastes gases of an industrial plant, e.g., an electrical power generating plant, a cement production plant, a fermentation process or an ore processing facility. [00481 In 1 ome embodiments, by the method 1000, ambient air is excluded the cathode electrolyte 108; a pH of bet een and 7 and 14 or greater us maintained in the cathode electrolyte; a pH of between 7 and 5 9 is maintain ed in the cathode electrolyte; a pH of between 8 and 11 is maintained in the cathode electrolyte; a pH of from less than 0 and up to 7 is maintained in the anode electrolyte; a pH of from less than 0 and up to 4 is maintained in the anode electrolyte; hydrogen gas is oxidized at the anode 102 to produce hydrogen ions and hydrogen ions are migrated from the anode through the second cation exchange membrane 122 into the anode electrolyte; hydroxide ions and hydrogen gas are produced at 10 the cathode 106; hydroxide ions are migrated from the cathode 106 into the cathode electrolyte 108; hydrogen gas is directed from the cathode 106 to the anode 102; cations ions are migrated from the anode electrolyte 104 through the first cation exchange membrane 122 into the cathode electrolyte 108 wherein the nations comprise sodium ions. [00491 In some embodiments, the method 1000 comprises producing sodium hydroxide and/or sodium 15 carbonate icns and/or sodium bicarbonate ions in the cathode electrolyte 108; producing an acid and a depleted sal solution in the anode electrolyte 104 comprising sodium ions and chloride ions; utilizing the anode electrolyte to dissolve minerals 904 and produce a mineral solution comprising calcium ions and/or magnesium ons, wherein the minerals comprises mafic minerals; filtering the mineral solution 914 to produce a filtrate comprising sodium ions and chloride ions; concentrating the filtrate to produce the salt 20 solution, wherein the concentrator comprises a reverse osmosis system 914; utilizing the salt solution as the anode el ectrolyte 104; precipitating a carbonate and/or bicarbonate with the cathode electrolyte 912; wherein the arbonate and/or bicarbonate comprises calcium and/or magnesium carbonate and/or bicarbonate. In some embodiments, the method includes disposing of the acid in an underground storage site where th e acid can be stored in an un-reactive salt or rock formation and hence does not an 25 environmental acidification. 100501 With reference to Figs. 1 - 9 and 11, the method 1100 in another embodiment comprises a step 1102 of pro ucing an acid 124 in an electrochemical system, e.g., system 900, comprising added carbon dioxide 106A, 107 in the cathode electrolyte 108; and contacting a mineral 906 with the acid 124. In some embodiment the method further producing the acid in the anode electrolyte 104, without generating a gas 30 at the anode 102, and oxidizing hydrogen gas 112 at the anode, wherein the acid comprises hydrochloric acid 124; and wherein the hydrogen gas 112 is produced at the cathode 106; producing an alkaline solution in t e cathode electrolyte 108; migrating sodium ions into the cathode electrolyte; wherein the alkaline solution comprises sodium hydroxide, sodium bicarbonate and/or sodium carbonate; wherein the voltage is lets than 2 V or less than 1V; wherein the anode electrolyte 104 is separated from the cathode 35 electrolyte 108 by first cation exchange membrane 116; wherein the anode 102 comprises a second cation exchange membrane 122 in contact with the anode electrolyte 102; wherein the anode electrolyte comprises a salt, e.g., sodium chloride; dissolving a mineral 906 with the acid 124 to produce a mineral solution; producing calcium ions and/or magnesium ions; wherein the mineral comprises a mafic mineral, e.g.. olivine or serpentine; filtering the mineral solution to produce a filtrate comprising sodium ions and 40 chloride ions solution; concentrating the filtrate to produce a salt solution; utilizing the salt solution as the anode elect olyte 104; precipitating a carbonate and/or bicarbonate with the cathode electrolyte; wherein -10the carbonate and/or bicarbonate comprises calcium and/or magnesium carbonate and/or bicarbonate. In some embodiments, the method includes disposing of the acid in an underground storage site where the acid can be stored in an un-reactive salt or rock formation and hence does not an environmental acidification. 5 [0051] vith reference to Figs. 1 - 6, as disclosed in U.S. Patent Application No. 12/503557 filed on July 16, 2009, tiled: "C02 Utilization In Electrochemical Systems", herein incorporated by reference in its entirety, in some embodiments, carbon dioxide is absorbed into the cathode electrolyte utilizing a gas mixer/gas absorber. In one embodiment, the gas mixer/gas absorber comprises a series of spray nozzles that produc s a flat sheet or curtain of liquid into which the gas is absorbed; in another embodiment, the 10 gas mixer/g s absorber comprises a spray absorber that creates a mist and into which the gas is absorbed; ii other embodiments, other commercially available gas/liquid absorber, e.g., an absorber available fr m Neumann Systems, Colorado, USA is used. [00521 'The carbon dioxide used in the system may be obtained from various industrial sources that releases ca bon dioxide including carbon dioxide from combustion gases of fossil fuelled power plants, 15 e.g., conve tional coal, oil and gas power plants, or IGCC (Integrated Gasification Combined Cycle) power plan s that generate power by burning sygas; cement manufacturing plants that convert limestone to lime; ore processing plants; fermentation plants; and the like. In some embodiments, the carbon dioxide may compri e other gases, e.g., nitrogen, oxides of nitrogen (nitrous oxide, nitric oxide), sulfur and sulfur gases (sulf r dioxide, hydrogen sulfide), and vaporized materials. In some embodiments, the system 20 includes a cas treatment system that removes constituents in the carbon dioxide gas stream before the gas is utilized in the cathode electrolyte. In some embodiments, a portion of, or the entire amount of, cathode ele trolyte comprising bicarbonate ions and/or carbonate ions/ and or hydroxide ions is withdrawn from the system and is contacted with carbon dioxide gas in an exogenous carbon dioxide gas/liquid contactor to increase the absorbed carbon dioxide content in the solution. In some 25 embodiments, the solution enriched with carbon dioxide is returned to the cathode compartment; in other embodimen s, the solution enriched with carbon dioxide is reacted with a solution comprising divalent cations to p oduce divalent cation hydroxides, carbonates and/or bicarbonates. In some embodiments, the pH of the c thode electrolyte is adjusted upwards by hydroxide ions that migrate from the cathode, and/or downwards by dissolving carbon dioxide gas in the cathode electrolyte to produce carbonic acid and 30 carbonic iors that react with and remove hydroxide ions. Thus it can be appreciated that the pH of the cathode ele trolyte is determined, at least in part, by the balance of these two processes. [00531 Referring to Fig.1 herein, the system 100 in one embodiment comprises a gas diffusion anode 102 and a cathode 106 in contact with a cathode electrolyte 108, 108A, 108B comprising dissolved carbon diox de 107A. The system in some embodiments includes a gas delivery system 112 configured to 35 deliver hydr gen gas to the anode 102; in some embodiments, the hydrogen gas is obtained from the cathode 106. In the system, the anode 102 is configured to produce protons, and the cathode 106 is configured t) produce hydroxide ions and hydrogen gas when a low voltage 114, e.g., less than 2V is applied acr ss the anode and the cathode. In the system, a gas is not produced at the anode 102. 10054] in the system as illustrated in Fig. 1, first cation exchange membrane 116 is positioned 40 between thE cathode electrolyte 108, 108 A, 108B and a salt solution 118; and an anion exchange membrane 20 is positioned between the salt solution 118 and the anode electrolyte 104 in a -11configuration where the anode electrolyte 104 is separated from the anode 102 by second cation exchange membrane 122. In the system, the second cation exchange membrane 122 is positioned between the anode 102 and the anode electrolyte 104 such that anions may migrate from the salt solution 118 to the anode electrolyte 104 through the anion exchange membrane 120; however, anions are 5 prevented from contacting the anode 102 by the second cation exchange membrane 122 adjacent to the anode 102. [00551 n some embodiments, the system is configurable to migrate anions, e.g., chloride ions, from the salt solu ion 118 to the anode electrolyte 104 through the anion exchange membrane 120; migrate cations, e.g. sodium ions from the salt solution 118 to the cathode electrolyte 108, 108A, 108B through 10 the first cati n exchange membrane 116; migrate protons from the anode 102 to the anode electrolyte 104; and mi rate hydroxide ions from the cathode 106 to the cathode electrolyte 108, 108A, 108B. Thus, in some em odiments, the system can be configured to produce sodium hydroxide and/or sodium bicarbonate and/or sodium carbonate in the cathode electrolyte 108, 108A, 108B; and produce an acid e.g., hydroc loric acid 124 in the anode electrolyte. 15 [0056] n some embodiments as illustrated in Fig. 1, the system comprises a partition 126 that partitions the cathode electrolyte 108 into a first cathode electrolyte portion 108A and a second cathode electrolyte portion 108B, wherein the second cathode electrolyte portion 108B, comprising dissolved carbon dioxi e, contacts the cathode 106; and wherein the first cathode electrolyte portion 108A comprising dissolved carbon dioxide and gaseous carbon dioxide is in contact with the second cathode 20 electrolyte portion108B under the partition 126. In the system, the partition is positioned in the cathode electrolyte s ch that a gas, e.g., carbon dioxide in the first cathode electrolyte portion 108A is isolated from cathode electrolyte in the second cathode electrolyte portion 108B. Thus, for example, where a gas, e.g., hydrogen, is generated at the cathode and it is desired to separate this cathode gas from a gas or vapor that ray evolve from the cathode electrolyte, the partition may serve as a means to prevent mixing 25 of the gases form the cathode and the gases and or vapor from the cathode electrolyte. While this system is illustrated in Fig. 1, it is applicable to any of the electrochemical system described herein, e.g., the systems illustrated in Figs. 4, 7 and 8. [00571 Thus, as can be appreciated, in some embodiments, on applying the present voltage across the anode a d cathode, the system can be configured to produce hydroxide ions and hydrogen gas at the 30 cathode 10E; migrate hydroxide ions from the cathode into the cathode electrolyte 108, 108B, 108A; migrate cations from the salt solution 118 to the cathode electrolyte through the first cation exchange membrane 16; migrate chloride ions from the salt solution 118 to the anode electrolyte 104 through the anion exchange membrane 120; and migrate protons from the anode 102 to the anode electrolyte 104. Hence, depending on the salt solution 118 used, the system can be configured to produce an alkaline 35 solution, e.g., sodium hydroxide in the cathode electrolyte. [00581 n some embodiments, the system is operatively connected to a carbon dioxide gas/liquid contactor 128 configured to remove cathode electrolyte from the system and dissolve carbon dioxide in the cathode electrolyte in the gas/liquid contactor before the cathode electrolyte is returned to the system. 100591 n other embodiments, the cathode electrolyte is operatively connected to a system (not 40 shown) that is configured to precipitate divalent cation carbonates and/or divalent cation bicarbonates and/or divalent cation hydroxides from a solution comprising carbon dioxide gas and divalent cations. -12- [00601 ig. 2 illustrates a schematic of a suitable gas diffusion anode that can be used in embodiments of the system described herein. In some embodiments, the gas diffusion anode comprises a conductive substrate 130 infused with a catalyst 136 that is capable of catalyzing the oxidation of hydrogen gas to protons when the present voltages are applied across the anode and cathode. In some 5 embodiments the anode comprises a first side 132 that interfaces with hydrogen gas provided to the anode, and an opposed second side 134 that interfaces with the anode electrolyte 104. In some embodiments, the portion of the substrate 132 that interfaces with the hydrogen gas is hydrophobic and is relatively dry; and the portion of the substrate 134 that interfaces with the anode electrolyte 104 is hydrophilic and may be wet, which facilitates migration of protons from the anode to the anode electrolyte. 10 In various embodiments, the substrate is porous to facilitate the movement of gas from the first side 132 to the catalyst 136 that may be located on second side 134 of the anode; in some embodiments, the catalyst may also be located within the body of the substrate 130. The substrate 130 may be selected for its hydrophili:: or hydrophobic characteristics as described herein, and also for its low ohmic resistance to facilitate ele tron conduction from the anode through a current collector connected to the voltage supply 15 114; the su strate may also be selected for it porosity to ion migration, e.g., proton migration, from the anode to the anode electrolyte 116. 100611 n some embodiments, the catalyst may comprise platinum, ruthenium, iridium, rhodium, manganese, silver or alloys thereof. Suitable gas diffusion anodes are available commercially, e.g., from E-TEK (USA) and other suppliers. In some embodiments of the anode as is illustrated in Fig. 8, the anode 20 comprises a ion exchange membrane, .e.g., a cation exchange membrane 122 that contacts the second side 134 of the anode. In such embodiments, the ion exchange membrane can be used to allow or prevent migration of ions to or from the anode. Thus, for example, with reference to Fig. 8, when protons are generated at the anode, a cation exchange membrane may be used to facilitate the migration of the protons frorr the anode and/or block the migration of ions, e.g., cations to the substrate. In the some 25 embodiments, the ion exchange membrane may be selected to preferentially allow passage of one type of cation, e.g., ydrogen ions, while preventing the passage of another type of ions, e.g., sodium ions. [0062] As is illustrated in Fig. 1, the system includes a salt solution 118 located between the anode electrolyte 1)4 and the cathode electrolyte 108, 108A, 108B. In some embodiments, the cathode electrolyte i separated from the salt solution by a first cation exchange membrane 116 that is allows 30 migration of ations, e.g., sodium ions, from the salt solution to the cathode electrolyte. The first cation exchange membrane 116 is also capable of blocking the migration of anions from the cathode electrolyte 108, 108A, 108B to the salt solution 118. In some embodiments, the anode electrolyte 104 is separated from the salt solution 118 by an anion exchange membrane 108 that will allow migration of anions, e.g., chloride ions, from the salt solution 118 to the anode electrolyte 104. The anion exchange membrane, 35 however, wil block the migration of cations, e.g., protons from the anode electrolyte 104 to the salt solution 118 100631 ith reference to Figs. 1 and 2, the system includes a hydrogen gas supply system 112 configured to provide hydrogen gas to the anode 102. The hydrogen may be obtained from the cathode 106 or may be obtained from external source, e.g., from a commercial hydrogen gas supplier, e.g., at 40 start-up of t e system when the hydrogen supply from the cathode is insufficient. In the system, the -13hydrogen g s is oxidized to protons and electrons; un-reacted hydrogen gas is recovered and circulated 140 at the node. [0064] Referring to Fig. 1, in operation, the cathode electrolyte 108, 108A, 108B is initially charged with a alkali e electrolyte, e.g., sodium hydroxide solution, and the anode electrolyte 104 is initially 5 charged with an acidic electrolyte, e.g., dilute hydrochloric acid. The cathode electrolyte is also initially charged with carbon dioxide gas 107A, 128, and hydrogen gas is provided to the anode. In the system, on applying a voltage across the anode and cathode, protons produced at the anode will enter into the anode electrolyte and attempt to migrate from the anode electrolyte 104 to the cathode 106 via the salt solution 118 between the cathode and anode. However, since the anion exchange membrane will block the 10 migration oi protons to the salt solution, the protons will accumulate in the anode electrolyte 104. [00651 Simultaneously at the cathode 106, the voltage across the anode and cathode will produce hydroxide ions and hydrogen gas at the cathode. In some embodiments, the hydrogen produced at the cathode is recovered and directed to the anode 102 where it is oxidized to protons. In the system, hydroxide i ns produced at the cathode 106 will enter into the cathode electrolyte 108, 108A, 108B from 15 where they Nill attempt to migrate to the anode 102 via the salt solution 118 between the cathode and anode. Ho ever, since the cathode electrolyte 108, 108A, 108B is separated from the salt solution electrolyte ty the first cation exchange membrane 116 which will block the passage of anions, the first cation exchange membrane will block the migration of hydroxide ions from the cathode electrolyte to the salt solutior- consequently, the hydroxide ions will accumulate in the cathode electrolyte 108, 108A, 108B. 20 [00661 In the system as illustrated in Fig. 1, with the voltage across the anode and cathode, since the salt solution is separated from the cathode electrolyte by the first cation exchange membrane 116, cations in the salt s lution, e.g., sodium ions, will migrate through the first cation exchange membrane 116 to the cathode ele trolyte 108, 108A, 108B, and anions, e.g., chloride ions, will migrate to the anode electrolyte through thelanion exchange membrane 120. Consequently, in the system, as illustrated in Fig. 1, an acid, 25 e.g., hydrochloric acid 124 will be produced in the anode electrolyte 104, and alkaline solution, e.g., sodium hyd oxide will be produced in the cathode electrolyte. As can be appreciated, with the migration of cations and anions from the salt solution, the system in some embodiments can be configured to produce a partly de-ionized salt solution from the salt solution 118. In some embodiments, this partially de-ionized salt solution can be used as feed-water to a desalination facility (not shown) where it can be further 30 processed t produce desalinated water as described in commonly assigned U.S. Patent Application no. 12/163,205 filed on June 27, 2008, herein incorporated by reference in its entirety; alternatively, the solution can be used in industrial and agricultural applications where its salinity is acceptable. [00671 With reference to Fig. 1, the system in some embodiments includes a second cation exchange rnembrane 124, attached to the anode substrate 105, such that it separates the anode 102 from 35 the anode electrolyte. In this configuration, as the second cation exchange membrane 122 is permeable to cations, protons formed at the anode will migrate to the anode electrolyte as described herein; however, as the second cation exchange membrane 122 is impermeable to anions, anions, e.g., chloride ions, in the anode electrolyte will be blocked from migrating to the anode 102, thereby avoiding interaction between thE anode and the anions that may interact with the anode, e.g., by corrosion. 40 [0068] With reference to Fig. 1, in some embodiments, the system includes a partition 128 configured i to J-shape structure and positioned in the cathode electrolyte 108, 108A, 108B to define an -14upward-tapering channel 144 in the upper portion of the cathode electrolyte compartment. The partition also defines a downward-tapering channel 146 in lower portion of the cathode electrolyte. Thus, with the partition in the place, the cathode electrolyte 108 is partitioned into the first cathode electrolyte portion 108A and a second cathode electrolyte portion 108B. As is illustrated in Fig. 1, cathode electrolyte in the 5 first cathode electrolyte portion 108A is in contact with cathode electrolyte in the second cathode electrolyte portion 108B; however, a gas in the first electrolyte portion 108A, e.g., carbon dioxide, is prevented f om mixing with cathode electrolyte in the second cathode electrolyte 108B. Although this is illustrated ir for the system of Fig. 1, such a configuration may be used in any system where it is desired to partition an electrolyte solution, e.g., a cathode electrolyte such that a gas that is introduced into one 10 portion remains separate from another portion. For example, such a configuration may be used in any system as described herein as, e.g., in Figs. 7 and 8. [0069] With reference to Fig. 1, the system in some embodiments includes a cathode electrolyte circulating system 142 adapted for withdrawing and circulating cathode electrolyte in the system. In one embodiment, the cathode electrolyte circulating system comprises a carbon dioxide gas/liquid contactor 15 128 that is Adapted for dissolving carbon dioxide in the circulating cathode electrolyte, and for circulating the electrol te in the system. As can be appreciated, since the pH of the cathode electrolyte can be adjusted by withdrawing and/or circulating cathode electrolyte from the system, the pH of the cathode electrolyte compartment can be by regulated by regulating an amount of cathode electrolyte removed from the sys tem through the carbon dioxide gas/liquid contactor 128. 20 [0070] In an alternative as illustrated in Fig. 4, the system comprises a cathode 106 in contact with a cathode ele trolyte 108 and an anode 102 in contact with an anode electrolyte 104. In this system, the cathode ele trolyte comprises a salt solution that functions as the cathode electrolyte as well as a source of chloride and sodium ions for the alkaline and acid solution produced in the system. In this system, the cathode electrolyte is separated from the anode electrolyte by an anion exchange membrane 120 that 25 allows migration of anions, e.g., chloride ions, from the salt solution to the anode electrolyte. As is illustrated in Fig. 4, the system includes a hydrogen gas delivery system 112 configured to provide hydrogen gas to the anode. The hydrogen may be obtained from the cathode and/or obtained from an external souce, e.g., a commercial hydrogen gas supplier e.g., at start-up of operations when the hydrogen st pply from the cathode is insufficient. In some embodiments, the hydrogen delivery system is 30 configured t deliver gas to the anode where oxidation of the gas is catalyzed to protons and electrons. In some embo iments, un-reacted hydrogen gas in the system is recovered and re-circulated to the anode. [00711 Referring to Fig. 4, as with the system of Fig. 1, on applying a voltage across the anode and cathode, pr tons produced at the anode from oxidation of hydrogen will enter into the anode electrolyte from where hey will attempt to migrate to the cathode electrolyte across the anion exchange membrane 35 120. Howev r, since the anion exchange membrane120 will block the passage of cations, the protons will accumulate in the anode electrolyte. At the same time, however, the anion exchange membrane 120 being pervious to anions will allow the migration of anions, e.g., chloride ions from the cathode electrolyte to the anodE, thus in this embodiment, chloride ions will migrate to the anode electrolyte to produce hydrochloric acid in the anode electrolyte. In this system, the voltage across the anode and cathode is 40 adjusted to a level such that hydroxide ions and hydrogen gas are produced at the cathode without producing a gas, e.g., chlorine or oxygen, at the anode. In this system, since cations will not migrate from -15the cathode electrolyte across the anion exchange membrane 116, sodium ions will accumulate in the cathode ele trolyte 108 to produce an alkaline solution with hydroxide ions produced at the cathode. In embodimen s where carbon dioxide gas is dissolved in the cathode electrolyte, sodium ions may also produce soc ium bicarbonate and or sodium carbonate in the cathode electrolyte as described herein with 5 reference to Fig.1. 10072] With reference to Fig. 1, depending on the pH of the cathode electrolyte, carbon dioxide gas introduced i to the first cathode electrolyte portion 108A will dissolve in the cathode electrolyte and reversibly dissociate and equilibrate to produce carbonic acid, protons, carbonate and/or bicarbonate ions in the first cathode electrolyte compartment as follows: 10 C02 + H 2 0 <==> H 2

CO

3 <==> H* + HCO3 <==> H* + C032 In the system, as cathode electrolyte in the first cathode electrolyte portion 108A may mix with second cathode electrolyte portion 108B, the carbonic acid, bicarbonate and carbonate ions formed in the first cathode ele trolyte portion 108A by absorption of carbon dioxide in the cathode electrolyte may migrate and equilibrate with cathode electrolyte in the second cathode electrolyte portion 108B. Thus, in some 15 embodimen s, first cathode electrolyte portion 108A may comprise dissolved and un-dissolved carbon dioxide gas, and/or carbonic acid, and/ or bicarbonate ions and/or carbonate ions; while second cathode electrolyte portion 108B may comprise dissolved carbon dioxide, and/or carbonic acid, and/ or bicarbonate ions and/or carbonate ions. [00731 With reference to Fig. 1, on applying a voltage across anode 102 and cathode 108, the 20 system 100 may produce hydroxide ions and hydrogen gas at the cathode from water, as follows: 2H 2 0 + 2e~ = H 2 + 20H~ As cathode lectrolyte in first cathode electrolyte portion 108A can intermix with cathode electolyte in second cathode electrolyte portion 108B, hydroxide ions formed in the second cathode electrolyte portion may migrate and equilibrate with carbonate and bicarbonate ions in the first cathode electrolyte portion 25 108A. Thus, in some embodiments, the cathode electrolyte in the system may comprise hydroxide ions and dissolve d and/or un-dissolved carbon dioxide gas, and/or carbonic acid, and/ or bicarbonate ions and/or carbonate ions. In the system, as the solubility of carbon dioxide and the concentration of bicarbonate and carbonate ions in the cathode electrolyte are dependent on the pH of the electrolyte, the overall reaction in the cathode electrolyte 104 is either: 30 Scenario 1: 2H 2 0 + 2CO2 + 2e- = H 2 + 2HC0 3 ; or Scenario 2: H 2 0 + C02 + 2e- = H 2 + C032 or a combin tion of both, depending on the pH of the cathode electrolyte. This is illustrated in as a arbonate speciation diagram in Fig. 5. [0074] or either scenario, the overall cell potential of the system can be determined through the 35 Gibbs energy change of the reaction by the formula: Ecei = -AG/nF Or, at standard temperature and pressure conditions: E-cei = -AG*/nF where, Ecei i the cell voltage, AG is the Gibbs energy of reaction, n is the number of electrons transferred, 40 and F is the Faraday constant (96485 J/Vmol). The Eceji of each of these reactions is pH dependent based on the Nern t equestion as illustrated in Fig.6. -16- [0075] Also, for either scenario, the overall cell potential can be determined through the combination of Nernst equations for each half cell reaction: E = E'- R T ln(Q) / n F where, E 0 is he standard reduction potential, R is the universal gas constant, (8.314 J/mol K) T is the 5 absolute terry perature, n is the number of electrons involved in the half cell reaction, F is Faraday's constant (96485 J/V mol), and Q is the reaction quotient such that: Etotai = Ecathode + Eanode. When hydro en is oxidized to protons at the anode as follows:

H

2 = 2H* + 2e~, 10 E 0 is 0.00 V, n is 2, and Q is the square of the activity of H* so that: Eanode = +0.059 pHa, where pHa is the pH of the anode electrolyte. When water is reduced to hydroxide ions and hydrogen gas at the cathode as follows: 2H 2 0 + 2e- = H 2 + 20H~, 15 E is -0.83 n is 2, and Q is the square of the activity of OH so that: Ecathode = -0.059 pHe, where pHe i the pH of the cathode electrolyte. [0076] or either Scenario, the E for the cathode and anode reactions varies with the pH of the anode and cathode electrolytes. Thus, for Scenario 1 if the anode reaction, which is occurring in an acidic 20 environment is at a pH of 0, then the E of the reaction is OV for the half cell reaction. For the cathode reaction, if t e generation of bicarbonate ions occur at a pH of 7, then the theoretical E is 7 x (-0.059 V) -0.413V for the half cell reaction where a negative E means energy is needed to be input into the half cell or full cell fo the reaction to proceed. Thus, if the anode pH is 0 and the cathode pH is 7 then the overall cell potential would be -0.413V, where: 25 Etotai = -0.059 (pHa - pHc) = -0.059 ApH. [00771 For Scenario 2 in which carbonate ions are produced, if the anode pH is 0 and the cathode pH is 10, this would represent an E of 0.59 V. [0078] Thus, in some embodiments, directing C02 gas into the cathode electrolyte may lower the pH of the cathode e electrolyte by producing bicarbonate ions and/or carbonate ions in the cathode electrolyte, 30 which conse uently may lower the voltage across the anode and cathode in producing hydroxide, carbonate ard/or bicarbonate in the cathode electrolyte. 100791 hus, as can be appreciated, if the cathode electrolyte is allowed to increase to a pH of 14 or greater, the difference between the anode half-cell potential (represented as the thin dashed horizontal line, Scenario 1, above) and the cathode half cell potential (represented as the thick solid sloping line in 35 Scenario 1, bove) will increase to 0.83V. With increased duration of cell operation without C02 addition or other intervention, e.g., diluting with water, the required cell potential will continue to increase. The cell potential mail also increase due to ohmic resistance loses across the membranes in the electrolyte and the cell's ov rvoltage potential. [00801 Herein, an overvoltage potential refers to the voltage difference between a thermodynamically 40 determined half-cell reduction potential, and the experimentally observed potential at which the redox reaction occurs. The term is related to a cell voltage efficiency as the overvoltage potential requires more -17energy thar is thermodynamically required to drive a reaction. In each case, the extra energy is lost as heat. Overyoltage potential is specific to each cell design and will vary between cells and operational conditions ven for the same reaction. 100811 in embodiments wherein it is desired to produce bicarbonate and/or carbonate ions in the 5 cathode electrolyte, the system as illustrated in Figs. 1-2, and as described above with reference to production of hydroxide ions in the cathode electrolyte, can be configured to produce bicarbonate ions and/or car nate ions in the first cathode electrolyte by dissolving carbon dioxide in the first cathode electrolyte nd applying a voltage of less than 3V, or less than 2.5 V, or less than 2V, or less than 1.5V such as les than 1.OV, or even less than 0.8 V or 0.6V across the cathode and anode. 10 [00821 In some embodiments, hydroxide ions, carbonate ions and/or bicarbonate ions produced in the cathodE electrolyte, and hydrochloric acid produced in the anode electrolyte are removed from the system, wh le sodium chloride in the salt solution electrolyte is replenished to maintain continuous operation o the system. As can be appreciated, in some embodiments, the system can be configured to operate in Narious production modes including batch mode, semi-batch mode, continuous flow mode, with 15 or without t e option to withdraw portions of the hydroxide solution produced in the cathode electrolyte, or withdraw al or a portions of the acid produced in the anode electrolyte, or direct the hydrogen gas produced a the cathode to the anode where it may be oxidized. [00831 In some embodiments, hydroxide ions, bicarbonate ions and/or carbonate ion solutions are produced in the cathode electrolyte when the voltage applied across the anode and cathode is less than 20 3V, 2.9V or less, 2.8V or less, 2.7V or less, 2.6V or less, 2.5V or less, 2.4V or less, 2.3V or less, 2.2V or less, 2.1V or less, 2.OV or less, 1.9V or less, 1.8V or less, 1.7V or less, 1.6V, or less 1.5V or less, 1.4V or less, 1.3V or less, 1.2V or less, 1. 1V or less, 1.OV or less, 0.9V or less or less, 0.8V or less, 0.7V or less, 0.6V or less, 0.5V or less, 0.4V or less, 0.3V or less, 0.2V or less, or 0.1 V or less. [00841 In another embodiment, the voltage across the anode and cathode can be adjusted such that 25 gas will form at the anode, e.g., oxygen or chlorine, while hydroxide ions, carbonate ions and bicarbonate ions are prcld uced in the cathode electrolyte and hydrogen gas is generated at the cathode. However, in this embodi ent, hydrogen gas is not supplied to the anode. As can be appreciated by one ordinarily skilled in the art, in this embodiment, the voltage across the anode and cathode will be generally higher compared to the embodiment when a gas does not form at the anode. 30 [0085] With reference to Figs.1-2, in some embodiments, the invention provides for a system comprising one or more anion exchange membrane 120, and cation exchange membranes 116, 122 located between the gas diffusion anode 102 and the cathode 106. In some embodiments, the membranes should be selected such that they can function in an acidic and/or basic electrolytic solution as appropriate. Other desirable characteristics of the membranes include high ion selectivity, low ionic 35 resistance, high burst strength, and high stability in an acidic electrolytic solution in a temperature range of 0 0 C to 100 0 or higher, or a alkaline solution in similar temperature range may be used. In some embodimen s, a membrane that is stable in the range of 0 0C to 80 0C, or 0 0C to 90 0C, but not stable above thesE ranges may be used. For other embodiments, it may be useful to utilize an ion-specific ion exchange embranes that allows migration of one type of cation but not another; or migration of one type 40 of anion anc not another, to achieve a desired product or products in an electrolyte. In some embodimen s, the membrane should be stable and functional for a desirable length of time in the system, -18e.g., several days, weeks or months or years at temperatures in the range of 0 0C to 80 0C, or 0 0C to 90 0C and high r and/or lower. In some embodiments, for example, the membranes should be stable and functional f r at least 5 days, 10 days, 15 days, 20 days, 100 days, 1000 days or more in electrolyte temperature at 80 OC, 70 0C, 60 0C, 50 OC, 40 0C, 30 0C, 20 C, 10 0C, 50C and more or less. 5 [0086] s can be appreciated, the ohmic resistance of the membranes will affect the voltage drop across the anode and cathode, e.g., as the ohmic resistance of the membranes increase, the voltage drop across the a ode and cathode will increase, and vice versa. Membranes currently available can be used and they inc ude membranes with relatively low ohmic resistance and relatively high ionic mobility; similarly, membranes currently available with relatively high hydration characteristics that increase with 10 temperatures, and thus decreasing the ohmic resistance can be used. Consequently, as can be appreciated, by selecting currently available membranes with lower ohmic resistance, the voltage drop across the a iode and cathode at a specified temperature can be lowered. [00871 scattered through currently available membrane are ionic channels consisting of acid groups. These ionic hannels may extend from the internal surface of the matrix to the external surface and the 15 acid groups may readily bind water in a reversible reaction as water-of-hydration. This binding of water as water-of-hy ration follows first order reaction kinetics, such that the rate of reaction is proportional to temperature Consequently, currently available membranes can be selected to provide a relatively low ohmic and i nic resistance while providing for improved strength and resistance in the system for a range of operating temperatures. Suitable membranes are commercially available from Asahi Kasei of Tokyo, 20 Japan; or frc m Membrane International of Glen Rock, NJ, and USA. [0088] n some embodiments, the cathode electrolyte 108, 108A, 108B is operatively connected to a waste gas treatment system (not illustrated) where the alkaline solution produced in the cathode electrolyte is utilized, e.g., to sequester carbon dioxide contained in the waste gas by contacting the waste gas and the athode electrolyte with a solution of divalent cations to precipitate hydroxides, carbonates 25 and/or bicarbonates as described in commonly assigned U.S. Patent Application no. 12/344,019 filed on December 24, 2008, herein incorporated by reference in its entirety. The precipitates, comprising, e.g., calcium and magnesium hydroxides, carbonates and bicarbonates in some embodiments may be utilized as building materials, e.g., as cements and aggregates, as described in commonly assigned U.S. Patent Application no. 12/126,776 filed on May 23, 2008, supra, herein incorporated by reference in its entirety. 30 In some embodiments, some or all of the carbonates and/or bicarbonates are allowed to remain in an aqueous me ium, e.g., a slurry or a suspension, and are disposed of in an aqueous medium, e.g., in the ocean depths or a subterranean site. [0089] n some embodiments, the cathode and anode are also operatively connected to an off-peak electrical po er-supply system 114 that supplies off-peak voltage to the electrodes. Since the cost of off 35 peak power s lower than the cost of power supplied during peak power-supply times, the system can utilize off-peak power to produce an alkaline solution in the cathode electrolyte at a relatively lower cost. [0090] n another embodiment, the system produces an acid, e.g., hydrochloric acid 124 in the anode elect lyte 104. In some embodiments, the anode compartment is operably connected to a system for dissolving minerals and/or waste materials comprising divalent cations to produce a solution of divalent 40 cations, e.g. Ca++ and Mg++. In some embodiments, the divalent cation solution is utilized to precipitate hydroxides, :arbonates and/or bicarbonates by contacting the divalent cation solution with the present -19alkaline solution and a source of carbon dioxide gas as described in U.S. Patent Application no. 12/344,019 filed on December 24, 2008, supra, herein incorporated by reference in its entirety. In some embodiments, the precipitates are used as building materials e.g., cement and aggregates as described in commonly assigned U.S. Patent application no. 12/126,776, supra, herein incorporated by reference in its 5 entirety. [00911 Nith reference to Fig. 1, on applying a voltage across the anode 102 and cathode 106, protons will frm at the anode from oxidation of hydrogen gas supplied to the anode, while hydroxide ions and hydrogen gas will form at the cathode electrolyte from the reduction of water, as follows:

H

2 = 2H* + 2e (anode, oxidation reaction) 10 2H 2 0 + 2e- = H 2 + 20H~ (cathode, reduction reaction) [0092] Since protons are formed at the anode from hydrogen gas provided to the anode; and since a gas such as oxygen does not form at the anode; and since water in the cathode electrolyte forms hydroxide io is and hydrogen gas at the cathode, the system will produce hydroxide ions in the cathode electrolyte a ad protons in the anode electrolyte when a voltage is applied across the anode and cathode. 15 Further, as an be appreciated, in the present system since a gas does not form at the anode, the system will produce hydroxide ions in the cathode electrolyte and hydrogen gas at the cathode and hydrogen ions at the anode when less than 2V is applied across the anode and cathode, in contrast to the higher voltage that is required when a gas is generated at the anode, e.g., chlorine or oxygen. For example, in some embodiments, hydroxide ions are produced when less than 2.OV, 1.5V, 1.4V, 1.3V, 1.2V, 1.1V, 1.OV, 20 0.9V, 0.8V, 0.7V, 0.6V, 0.5V, 0.4V, 0.3V, 0.2V, 0.1 V or less is applied across the anode and cathode. [00931 As discussed above, in the system, on applying a voltage across the anode 102 and cathode 106, the positively charged protons formed at the anode will attempt to migrate to the cathode through the anode electrlyte 104, while the negatively charged hydroxide ions formed at the cathode will attempt to migrate to the anode through the cathode electrolyte 108, 108A, 108B. As is illustrated in Fig. 1 and with 25 reference to hydroxide ions in the cathode electrolyte 108, 108A, 108B, since the first cation exchange membrane 116 will restrict the migration of anions from the cathode electrolyte 108, 108A, 108B, and since the an on exchange membrane 120 will prevent the migration of anions from the anode electrolyte 104 to the salt solution 118, the hydroxide ions generated in the cathode electrolyte will be prevented from migrating out of the cathode electrolyte through the cation exchange membrane. Consequently, on 30 applying the voltage across the anode and cathode, the hydroxide ions produced at the cathode will be contained in the cathode electrolyte. Thus, depending on the flow rate of fluids into and out of the cathode electrolyte a d the rate of carbon dioxide dissolution in the cathode electrolyte, the pH of the cathode electrolyte will adjust, e.g., the pH may increase, decrease or remain the same. 100941 n some embodiments, depending on the ionic species desired in cathode electroyte 108, 35 108A, 108B nd/or the anode electolyte 104 and/or the salt solution 118, alternative reactants can be utilized. Thus, for example, if a potassium salt such as potassium hydroxide or potassium carbonate is desired in the cathode elelctolyte 1108, 108A, 108B, then a potassium salt such as potassium chloride can be utiliz d in the salt solution 118. Similarly, if sulfuric acid is desired in the anode electrolyte, then a sulfate such as sodium sulfate can be utilized in the salt solution 118. As described in some embodiments 40 herein, carbon dioxide gas is absorbed in the cathode electrolyte; however, it will be appreciated that other gases, including volatile vapors, can be absorbed in the electrolyte, e.g., sulfur dioxide, or organic -20vapors to pr duce a desired result. As can be appreciated, the gas can be added to the electrolyte in various ways, e.g., by bubbling it directly into the electrolyte, or dissolving the gas in a separate compartmen, connected to the cathode compartment and then directed to the cathode electrolyte as described herein. 5 [0095] /ith reference to Figs 1 and 3, method 300 in some embodiments comprises a step 302 of applying a voltage across a cathode 106 and a gas diffusion anode 102 in an electrochemical system 100, wherein the cathode contacts a cathode electrolyte comprising dissolved carbon dioxide. In some embodiments, the method includes a step of providing hydrogen to the gas diffusion anode 102; a step of contacting the cathode 106 with a cathode electrolyte 108, 108A, 108B comprising dissolved carbon 10 dioxide gas 07A; and a step of applying a voltage 114 across the anode and cathode; a step whereby protons are produced at the anode and hydroxide ions and hydrogen gas produced at the cathode; a step whereby a gas is not produced at the anode when the voltage is applied across the anode and cathode; a step wherein the voltage applied across the anode and cathode is less than 2V; a step comprising directing hy rogen gas from the cathode to the anode; a step comprising whereby protons are migrated 15 from the anode to an anode electrolyte; a step comprising interposing an anion exchange membrane between the anode electrolyte and the salt solution; a step comprising interposing a first cation exchange membrane tween the cathode electrolyte and the salt solution, wherein the salt solution is contained between the anion exchange membrane and the first cation exchange membrane; a step comprising whereby anions migrate from the salt solution to the anode electrolyte through the anion exchange 20 membrane, and cations migrate from the salt solution to the cathode electrolyte through the first cation exchange m mbrane; a step comprising producing hydroxide ions and/or carbonate ions and/or bicarbonate ons in the cathode electrolyte; a step comprising producing an acid in the anode electrolyte; a step comp ising producing sodium hydroxide and/or sodium carbonate and/or sodium bicarbonate in the cathode electrolyte; a step whereby hydrochloric acid is produced in the anode electrolyte; a step 25 comprising contacting the cathode electrolyte with a divalent cation solution, wherein the divalent cations comprise calcium and magnesium ions; a step comprising producing partially desalinated water from the salt solution; a step comprising withdrawing a first portion of the cathode electrolyte and contacting the first portion of cathode electrolyte with carbon dioxide; and a step comprising contacting the first portion of cathode electrolyte with a divalent cation solution. 30 [00961 n some embodiments, hydroxide ions are formed at the cathode 106 and in the cathode electrolyte 108, 108A, 108B by applying a voltage of less than 2V across the anode and cathode without forming a gas at the anode, while providing hydrogen gas at the anode for oxidation at the anode. In some embodiments, method 300 does not form a gas at the anode when the voltage applied across the anode and cathode is less than 3V or less, 2.9V or less, 2.8V or less, 2.7V or less, 2.6V or less, 2.5V or less, 35 2.4V or less, 2.3V or less, 2.2V or less, 2. 1V or less, 2.OV or less, 1.9V or less, 1.8V or less, 1.7V or less, 1.6V or less, 1.5V or less, 1.4V or less, 1.3V or less, 1.2V or less, 1.1V or less, 1.OV or less, 0.9V or less, 0.8V or less, 0.7V or less, 0.6V or less, 0.5V or less, 0.4V or less, 0.3V or less, 0.2V or less, or 0.1 V or less, while h drogen gas is provided to the anode where it is oxidized to protons. As will be appreciated by one ordin rily skilled in the art, by not forming a gas at the anode and by providing hydrogen gas to the 40 anode for ox dation at the anode, and by otherwise controlling the resistance in the system for example by decreasing the electrolyte path lengths and by selecting ionic membranes with low resistance and any -21other methOd know in the art, hydroxide ions can be produced in the cathode electrolyte with the present lower voltages. [00971 in some embodiments, hydroxide ions, bicarbonate ions and carbonate ions are produced in the cathodE electrolyte where the voltage applied across the anode and cathode is less than 3.OV, 2.9V, 5 2.8V, 2.7V, 2.6V, 2.5V, 2.4V, 2.3V, 2.2V, 2.1V, 2.OV, 1.9V, 1.8V, 1.7V, 1.6V, 1.5V, 1.4V, 1.3V, 1.2V, 1.1V, 1.OV, 0.9V, 0.8V, 0.7V, 0.6V, 0.5V, 0.4V, 0.3V, 0.2V, O.1V or less without forming a gas at the anode. In some emb diments, the method is adapted to withdraw and replenish at least a portion of the cathode electrolyte nd the acid in the anode electrolyte back into the system in either a batch, semi-batch or continuous mode of operation. 10 [0098] In an exemplarary embodiment, a system configured substantially as illustrated in Figs. 1 and 2 was ope ted with a constant current density applied across the electrodes at steady state conditions while carbc n dioxide gas was continuously dissolved into the cathode electrolyte, at various temperatures and voltages. In the system, a platinum catalyst, gas diffusion anode obtained from E-TEK Corporation, (USA) was used as the anode. A Raney nickel deposited onto a nickel gauze substrate was used as the 15 cathode. Ir the system, the initial acid concentration in the anode electrolyte was 1 M; the initial sodium chloride sa t solution was 5 M; and the initial concentration of the sodium hydroxide solution in the cathode co partment was 1 M. In the system, the pH of the cathode compartment was maintained at either 8 or 0 by regulating the amount of carbon dioxide dissolved in the cathode electrolyte. Ta>Ie 1: Experimental Current Density, Temperature and Voltage Characteristics of the System T (*C) Potential (V) pH Current density (mAlcm 2 ) 0.8 10 8.6 25 8 11.2 1.2 10 28.3 8 29.2 1.6 10 50.2 8 50.6 75 0.8 10 13.3 8 17.8 1.2 10 45.3 8 49.8 1.6 10 80.8 8 84.7 20 [00991 As is illustrated in Table 1, a range of current densities was achieved across the electrode in the system. As will be appreciated by one ordinarily skilled in the art, the current density that can be achieved vrith other configurations of the system may vary, depending on several factors including the cumulative electrical resistance losses in the cell, environmental test conditions, the over-potential 25 associated with the anodic and cathodic reactions, and other factors. -22- [001001 I will also be appreciated that the current densities achieved in the present configuration and as set forth in Table 1 are correlated with the production of hydroxide ions at the cathode, and thus are correlated with the production of sodium hydroxide and/or sodium carbonate and/or sodium bicarbonate in the cathode lectrolyte, as follows. With reference to Table 1, at 75 *C, 0.8 V and a pH of 10, each cm2 of 5 electrode passed 13.3 mA of current, where current is a measure of charge passed (Coulomb) per time (second). Based on Faraday's Laws, the amount of product, e.g., hydroxide ions, produced at an electrode is roportional to the total electrical charge passed through the electrode as follows: n = (I * t) / (F * z) where n is moles of product, I is a current, t is time, F is Faraday's constant, and z is the electrons 10 transferred per product ionic species (or reagent ionic species). Thus, based on the present example, 1.38x10- 4 m les of hydroxide ions are produced per second per cm 2 of electrode, which is correlated with the production of sodium hydroxide in the cathode electrolyte. In the system the production rate of NaOH dictates the Production rate of NaHCO 3 and Na 2

CO

3 through Le Chatelier's principle following the net chemical eq ilibria equations of 15

H

2

CO

3 + 0H- = H 2 0 + HC0 3 ~ and HC0 3 +01H~ =H 2 0 + C0 3 , where an in rease in concentration of one species in equilibria will change the concentration of all species so that the e juilibrium product maintains the equilibrium constant. Thus, in the system, the equilibrium concentratio s of H 2

CO

3 , HC0 3 ~, and C0 3 2 - vs. pH in the electrolyte will follow the carbonate speciation 20 diagram as c iscussed above. [00101] in the system as illustrated in Fig. 1 and as discussed with reference to the carbonate speciation graph, supra, the solubility of carbon dioxide in the cathode electrolyte is dependent on the pH of the electrolyte. Also in the system, the voltage across the cathode and anode is dependent on several factors inclu ing the pH difference between the anode electrolyte and cathode electrolyte. Thus, in some 25 embodiment the system can be configured to operate at a specified pH and voltage to absorb carbon dioxide and produce carbonic acid, carbonate ions and/or bicarbonate ions in the cathode electrolyte. In embodiments where carbon dioxide gas is dissolved in the cathode electrolyte, as protons are removed from the cathode electrolyte more carbon dioxide may be dissolved to form carbonic acid, bicarbonate ions and/or carbonate ions. Depending on the pH of the cathode electrolyte the balance is shifted toward 30 bicarbonate ons or toward carbonate ions, as is well understood in the art and as is illustrated in the carbonate sp eciation diagram, above. In these embodiments the pH of the cathode electrolyte solution may decre se, remain the same, or increase, depending on the rate of removal of protons compared to rate of introduction of carbon dioxide. It will be appreciated that no carbonic acid, hydroxide ions, carbonate io s or bicarbonate ions are formed in these embodiments, or that carbonic acid, hydroxide 35 ions, carbon te ions, bicarbonate ions may not form during one period but form during another period. [00102] In another embodiment, the present system and method are integrated with a carbonate and/or bicarbonate precipitation system (not illustrated) wherein a solution of divalent cations, when added to the present cathode electrolyte, causes formation of precipitates of divalent carbonate and/or bicarbonate compounds, e.g., calcium carbonate or magnesium carbonate and/or their bicarbonates. In 40 some emboc iments, the precipitated divalent carbonate and/or bicarbonate compounds may be utilized as building materials, e.g., cements and aggregates as described for example in commonly assigned U.S. -23- Patent Appli ation no. 12/126,776 filed on May 23, 2008, herein incorporated by reference in its entirety. [00103] n an alternative embodiment, the present system and method are integrated with a mineral and/or mate ial dissolution and recovery system (not illustrated) wherein the acidic anode electrolyte solution 104 or the basic cathode electrolyte 108 is utilized to dissolve calcium and/or magnesium-rich 5 minerals e.g , serpentine or olivine, or waste materials, e.g., fly ash, red mud and the like, to form divalent cation soluti ns that may be utilized, e.g., to precipitate carbonates and/or bicarbonates as described herein. In some embodiments, the precipitated divalent carbonate and/or bicarbonate compounds may be utilized as building materials, e.g., cements and aggregates as described for example in commonly assigned U. . Patent Application no. 12/126,776 filed on May 23, 2008, herein incorporated by reference 10 in its entirety. [001041 n an alternative embodiment, the present system and method are integrated with an industrial w te gas treatment system (not illustrated) for sequestering carbon dioxide and other constituents of industrial waste gases, e.g., sulfur gases, nitrogen oxide gases, metal and particulates, wherein by contacting the flue gas with a solution comprising divalent cations and the present cathode 15 electrolyte comprising hydroxide, bicarbonate and/or carbonate ions, divalent cation carbonates and/or bicarbonate are precipitated as described in commonly assigned U.S. Patent Application no. 12/344,019 filed on Dec mber 24, 2008, herein incorporated by reference in its entirety. The precipitates, comprising, e.g., calcium and/or magnesium carbonates and bicarbonates in some embodiments may be utilized as building materials, e.g., as cements and aggregates, as described in commonly assigned U.S. Patent 20 Application ro. 12/126,776 filed on May 23, 2008, herein incorporated by reference in its entirety. [001051 n another embodiment, the present system and method are integrated with an aqueous desalination system (not illustrated) wherein the partially desalinated water of the third electrolyte of the present syst m is used as feed-water for the desalination system, as described in commonly assigned U.S. Patent Application no. 12/163,205 filed on June 27, 2008, herein incorporated by reference in its 25 entirety. [00106] n an alternative embodiment, the present system and method are integrated with a carbonate and/or bicarbonate solution disposal system (not illustrated) wherein, rather than producing precipitates by contacting a solution of divalent cations with the first electrolyte solution to form precipitates, the system produces a solution, slurry or suspension comprising carbonates and/or bicarbonates. In some 30 embodiments, the solution, slurry or suspension is disposed of in a location where it is held stable for an extended pe iods of time, e.g., the solution/slurry/suspension is disposed in an ocean at a depth where the tempera ure and pressure are sufficient to keep the slurry stable indefinitely, as described in U.S. Patent Application no. 12/344,019 filed on December 24, 2008, herein incorporated by reference in its entirety; or ir a subterranean site. 35 -24-

Claims (78)

1. An electrochemical system comprising: a cathode electrolyte comprising added carbon dioxide, and in contact with a cathode; and 5 a first cation exchange membrane separating the cathode electrolyte from an anode electrolyte contacting a anode.

2. The system of claim 1, wherein the anode comprises a second cation exchange membrane contacting the anode electrolyte. 10

3. The system of claim 1 or 2, wherein the carbon dioxide is contained in a waste gas.

4. The system of claim 3, wherein the waste gas comprises emissions from and industrial operation. 15

5. The system of claim 4, wherein the industrial operation comprises an electrical power generating plant, a cement plant, an ore processing facility or a fermentation system.

6. The system of claim 5, wherein atmospheric carbon dioxide is excluded from the cathode electrolyte. 20

7. The system of claim 6, wherein the cathode electrolyte is operatively connected to the industrial facility.

8. The system of claim 7, wherein the pH of the cathode electrolyte is 7 and above. 25

9. The system of claim 8, wherein the pH of the cathode electrolyte is between 7 and 14.

10. The system of claim 9, wherein the pH of the cathode electrolyte is between 7 and 9. 30

11. The system of claim 10, wherein the pH of the cathode electrolyte is between 8 and 11.

12. The system of claim 11, wherein the pH of the anode electrolyte comprises is less than 7.

13. The system of claim 12, wherein the pH of the anode electrolyte is less than 4. 35

14. The system of claim 13, wherein the cathode electrolyte comprises hydroxide ions and/or bicarbonate ions and/or carbonate ions.

15. The system of claim 14, wherein the cathode electrolyte comprises sodium ions. 40

16. The system of claim 15, wherein the cathode electrolyte is operatively connected to a carbonate and/or bicar onate precipitator. -25-

17. The system of claim 16, wherein the carbonate and/or bicarbonate comprises calcium and/or magnesium. 5

18. The system of claim 17, comprising hydrogen gas at the anode.

19. The system of claim 18, wherein the anode comprises a gas diffusion anode.

20. The system of claim 19, wherein the cathode is configured to produce hydrogen gas. 10

21. The system of claim 20, comprising a gas delivery system configured to direct hydrogen gas from the cathode o the anode.

22. The system of claim 21, wherein the anode electrolyte comprises an acid and a salt solution. 15

23. The system of claim 22, wherein the salt solution comprises sodium ions and chloride ions.

24. The system of claim 23, configured to produce hydrogen ions at the anode with less than 1V across the a ode and cathode, without producing a gas at the anode. 20

25. The system of claim 24, configured to migrate hydrogen ions into the anode electrolyte.

26. The system of claim 25, configured to produce hydroxide ions at the cathode. 25

27. The system of claim 26, configured to migrate hydroxide ions into the cathode electrolyte.

28. The system of claim 27, configured to migrate cations from the anode electrolyte into the cathode electrolyte. 30

29. The system of claim 28, wherein the cations comprise sodium ions.

30. The system of claim 29, wherein the anode electrolyte is operatively connected to a mineral dissolution s stem configured to dissolve minerals. 35

31. The system of claim 30, wherein the mineral solution comprises calcium ions and/or magnesium ions.

32. The system of claim 31, wherein the minerals comprises mafic minerals. 40

33. The system of claim 32, wherein the mineral dissolution system is operatively connected to a separator c nfigured to separate sodium ions and chloride ions from the mineral solution. -26-

34. The system of claim 33, comprising a concentrator configured to concentrate sodium ions and chloride ion< into the salt solution.

35. An electrochemical method comprising: 5 add ng carbon dioxide into a cathode electrolyte separated from an anode electrolyte by a first cation ex change membrane; and producing an alkaline solution in the cathode electrolyte without producing a gas at the anode in contact wi h the anode electrolyte. 10

36. The method of claim 35, comprising applying a voltage across a cathode in contact with the cathode electrolyte and the anode.

37. The method of claim 36, wherein the voltage is less than 1V. 15

38. The method of claim 37, wherein the anode comprises a second cation exchange membrane contacting tlhe anode electrolyte.

39. The method of claim 38, wherein the anode comprises a gas diffusion anode. 20

40. The method of claim 39, comprising producing hydroxide ions and/or bicarbonate ions and/or carbonate icns in the cathode electrolyte.

41. The method of claim 40, wherein the carbon dioxide is contained in a waste gas. 25

42. The method of claim 41, wherein the waste gas is emitted from an industrial plant.

43. The method of claim 42, wherein the industrial plant comprises a fossil fuelled electrical power generating plant, a cement production plant or an ore processing facility. 30

44. The method of claim 43, wherein carbon dioxide in ambient air is excluded from the cathode electrolyte.

45. The method of claim 44, comprising maintaining a pH of 7 or greater in the cathode electrolyte. 35

46. The method of claim 45, comprising maintaining a pH of between 7 and 9 in the cathode electrolyte.

47. The method of claim 46, comprising maintaining a pH of between 8 and 11 in the cathode electrolyte. 40

48. The method of claim 47, comprising maintaining a pH of less than 7 in the anode electrolyte. -27-

49. The method of claim 48, comprising maintaining a pH of less than 4 in the anode electrolyte.

50. The method of claim 49, comprising oxidizing hydrogen gas to hydrogen ions at the anode. 5

51. The method of claim 50, comprising migrating the hydrogen ions through the second cation exchange membrane into the anode electrolyte.

52. The method of claim 51, comprising producing hydroxide ions and hydrogen gas at the cathode. 10

53. Th method of claim 52, comprising directing hydrogen gas from the cathode to the anode.

54. The method of claim 53, comprising migrating cations ions through the first cation exchange membrane into the cathode electrolyte. 15

55. Th a method of claim 54, wherein the cations comprise sodium ions.

56. Th a method of claim 55, comprising producing an acid in the anode electrolyte.

57. A method comprising: 20 producing an acid in an electrochemical system comprising added carbon dioxide in the cathode electrolyte; and con acting a mineral with the acid.

58. The method of claim 57, comprising producing the acid in the anode electrolyte, without 25 generating gas at the anode.

59. The method of claim 58, comprising oxidizing hydrogen gas at the anode.

60. The method of claim 59, wherein the acid comprises hydrochloric acid. 30

61. The method of claim 60, wherein the hydrogen gas is produced at the cathode.

62. The method of claim 61, comprising producing an alkaline solution in the cathode electrolyte. 35

63. The method of claim 62, comprising migrating sodium ions into the cathode electrolyte.

64. The method of claim 63, wherein the alkaline solution comprises sodium hydroxide, sodium bicarbonate and/or sodium carbonate. 40

65. The method of claim 64, wherein the voltage is less than 1V. -28-

66. The method of claim 65, wherein the anode electrolyte is separated from the cathode electrolyte by first catio exchange membrane.

67. The method of claim 66, wherein the anode comprises a second cation exchange membrane in 5 contact with the anode electrolyte.

68. The method of claim 67, wherein the anode electrolyte comprises a salt.

69. The method of claim 68, wherein the salt comprises sodium chloride. 10

70. The method of claim 69, dissolving a mineral with the acid to produce a mineral solution.

71. The method of claim 70, comprising producing calcium ions and/or magnesium ions. 15

72. The method of claim 71, wherein the mineral comprises a mafic mineral.

73. The method of claim 72, comprising filtering the mineral solution to produce a filtrate comprising sodium ions and chloride ions solution. 20

74. The method of claim 73, comprising concentrating the filtrate to produce a salt solution.

75. The method of claim 74, comprising utilizing the salt solution as the anode electrolyte.

76. The method of claim 75, comprising precipitating a carbonate and/or bicarbonate with the cathode 25 electrolyte.

77. The method of claim 76, wherein the carbonate and/or bicarbonate comprises calcium and/or magnesium carbonate and/or bicarbonate. 30

78. The method of claim 77, comprising disposing of the acid in an underground storage. -29-