ELECTROCHEMICAL PROCESSES FOR PRODUCING DIFFERENT RATIOS OF H2 TO CO2 GASES

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001]This application claims priority under 35 U.S.C. § 119 (c) to U.S. Provisional Application Ser. No. 63/705,277, titled “ELECTROCHEMICAL PROCESSES FOR PRODUCING DIFFERENT RATIOS OF H₂ TO CO₂ GASES,” filed on Oct. 9, 2024, the subject matter of same being incorporated herein by reference in its entirety for all purposes.

GOVERNMENT LICENSE RIGHTS

[0002]This invention was made with U.S. government support under Contract No. N00014-21-C-1019 awarded by the Department of the Navy. The government has certain rights in the invention.

FIELD OF TECHNOLOGY

[0003]The present disclosure pertains electrochemical devices and processes that combine an Electrolytic—Cation Exchange Module (ECEM) process and electrolysis to produce different ratios of H₂ gas and CO₂ gas. These devices and processes can also be used for other applications where acidification of a stream and simultaneous production of gases from electrode reactions are desired.

SUMMARY

[0004]In accordance with one aspect, there is provided an apparatus for generation of carbon dioxide and hydrogen from a saline water source. The apparatus comprises an electrolytic-cation exchange module (E-CEM) cell unit including an E-CEM anodic compartment, an E-CEM cathodic compartment, a center compartment defined between the E-CEM anodic compartment and the E-CEM cathodic compartment, a first E-CEM cation permeable fluidic separator disposed between the center compartment and the E-CEM anodic compartment, and a second E-CEM cation permeable fluidic separator disposed between the center compartment and the E-CEM cathodic compartment. The apparatus further includes at least one electrolyzer including an electrolyzer anodic compartment, an electrolyzer cathodic compartment, and an electrolyzer cation permeable fluidic separator disposed between the electrolyzer anodic compartment and the electrolyzer cathodic compartment. Each of the E-CEM cell unit and the at least one electrolyzer are disposed between a set of endplates and endblocks.

[0005]In some embodiments, the apparatus comprises two electrolyzers, a first of the two electrolyzers being disposed on an opposite side of the E-CEM anodic compartment from the center compartment, a second of the two electrolyzers being disposed on an opposite side of the E-CEM cathodic compartment from the center compartment.

[0006]In some embodiments, the apparatus further comprises a first solid bipolar electrode disposed between the first of the two electrolyzers and the E-CEM anodic compartment.

[0007]In some embodiments, the apparatus further comprises a second solid bipolar electrode disposed between the second of the two electrolyzers and the E-CEM cathodic compartment.

[0008]In some embodiments, the apparatus further comprises a controller configured to control flow rates of fluids through the E-CEM cell unit and the at least one electrolyzer and current across the E-CEM cell unit and the at least one electrolyzer to achieve a target ratio of H₂:CO₂ produced by the apparatus.

[0009]In some embodiments, the controller is configured to control the flow rates of the fluids through the E-CEM cell unit and the at least one electrolyzer and the current across the E-CEM cell unit and the at least one electrolyzer that minimizes energy consumption of the apparatus while achieving the target ratio of H₂:CO₂ and target volumes of H₂ and CO₂ produced by the apparatus.

[0010]In some embodiments, the at least one electrolyzer includes two electrolyzers disposed adjacent one another.

[0011]In some embodiments, the two electrolyzers are separated from the E-CEM cell unit by a first solid bipolar electrode.

[0012]In some embodiments, the two electrolyzers are separated from one another by a second solid bipolar electrode.

[0013]In some embodiments, the apparatus comprises two electrolyzers, a first of the two electrolyzers being disposed on an opposite side of the E-CEM anodic compartment from the center compartment, a second of the two electrolyzers being disposed on an opposite side of the E-CEM cathodic compartment from the center compartment, a first mesh electrode forming both the E-CEM anode and an electrolyzer anode of the first of the two electrolyzers.

[0014]In some embodiments, a single anodic compartment forms both of the E-CEM anodic compartment and the electrolyzer anodic compartment of the first of the two electrolyzers.

[0015]In some embodiments, the apparatus further comprises a second mesh electrode that forms both the E-CEM cathode and an electrolyzer cathode of the second of the two electrolyzers.

[0016]In some embodiments, a single cathodic compartment forms both of the E-CEM cathodic compartment and the electrolyzer cathodic compartment of the second of the two electrolyzers.

[0017]In some embodiments, the apparatus comprises three electrolyzers and three E-CEM cell units, a first of the three electrolyzers being disposed on an opposite side of the E-CEM anodic compartment of a first of the three E-CEM cell units from the center compartment of the first of the three E-CEM cell units, a second of the two electrolyzers being disposed on an opposite side of the E-CEM cathodic compartment of the first of the three E-CEM cell units from the center compartment of the first of the three E-CEM cell units, a second of the three E-CEM cell units being disposed on an opposite side of the first of the three electrolyzers from the first of the three E-CEM cell units, a third of the three E-CEM cell units being disposed on an opposite side of the second of the three electrolyzers from the first of the three E-CEM cell units, and a third of the three electrolyzers being disposed on an opposite side of the third of the three E-CEM cell units from the second of the three electrolyzers.

[0018]In some embodiments, anodes and cathodes of each of the three electrolyzers and three E-CEM cell units are mesh electrodes.

[0019]In some embodiments, the apparatus comprises a plurality of electrolyzers and two E-CEM cell units, the plurality of electrolyzers being disposed between a first of the two E-CEM cell units and a second of the two E-CEM units.

[0020]In some embodiments, the apparatus further comprises a first mesh electrode forming both a cathode of one of the two E-CEM cell units and an electrolyzer cathode of one of the plurality of electrolyzers.

[0021]In some embodiments, the apparatus further comprises a second mesh electrode forming a cathode of both of two adjacent ones of the plurality of electrolyzers.

[0022]In some embodiments, the apparatus further comprises a third mesh electrode forming an anode of both of two adjacent ones of the plurality of electrolyzers.

[0023]In some embodiments, the electrolyzer cation permeable fluidic separator is formed of a different material from either of the first E-CEM cation permeable fluidic separator and the second E-CEM cation permeable fluidic separator.

[0024]In accordance with another aspect, there is provided an apparatus for generation of hydrogen and carbon dioxide from seawater. The apparatus comprises at least one electrolytic-cation exchange module (E-CEM) cell unit and a plurality of electrolyzers each disposed between a set of endplates and endblocks.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025]The accompanying drawings are not drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in the various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:

[0026]FIG. 1 is a schematic drawing of the E-CEM process;

[0027]FIG. 2 is a diagram illustrating the equilibrium for inorganic carbonic species in seawater at 10° C.;

[0028]FIG. 3A is a graph illustrating H₂/CO₂ ratio and residence time required to achieve a target seawater effluent pH of 4.0, plotted vs. current density;

[0029]FIG. 3B is a graph illustrating H₂/CO₂ ratio and residence time required to achieve a target seawater effluent pH of 3.0, plotted vs. current density;

[0030]FIG. 4 is a schematic diagram of an example of an E-CEM/electrolyzer device as disclosed herein;

[0031]FIG. 5 is a schematic diagram of another example of an E-CEM/electrolyzer device as disclosed herein;

[0032]FIG. 6 is a schematic diagram of another example of an E-CEM/electrolyzer device as disclosed herein; and

[0033]FIG. 7 is a schematic diagram of another example of an E-CEM/electrolyzer device as disclosed herein.

DETAILED DESCRIPTION

[0034]The total carbon content of the world's oceans is approximately 38,000 gigatons (GT). Over 95% of this carbon is in the form of dissolved bicarbonate ion (HCO₃⁻). This bicarbonate ion, along with the carbonate ion (CO₃²⁻), is responsible for buffering and maintaining the pH of the ocean which is relatively constant below the first 100 meters of ocean depth. The dissolved bicarbonate and carbonate ions present in the ocean are effectively bound CO₂, and the sum of the concentrations of these species, along with dissolved gaseous CO₂, represents the total carbon dioxide concentration [CO₂]_T, of seawater.

[0035]At a typical ocean pH of 7.8, kept relatively constant by a complex bicarbonate-carbonate buffer system, [CO₂]_T is about 2000 μmoles/kg near the surface and about 2400 μmoles/kg at depths below 300 meters. This equates to approximately 100 mg/L of [CO₂]_T. Of the total CO₂ in the ocean, about 2-3% is dissolved gaseous CO₂, about 1% is present as the dissolved carbonate ion, and the remainder, about 96%, is present as the dissolved bicarbonate ion. It is known that the equilibrium form and concentration of water containing CO₂ and its various ionic forms is dependent on the pH of the water. For example, at a seawater pH of 4.5, 99% of all carbonate species in seawater exist as carbonic acid, H₂CO₃. Thus, to convert HCO₃⁻ to H₂CO₃, the pH of seawater may be lowered.

[0036]CO₂ dissolved in water is in equilibrium with H₂CO₃ as shown in equation 1:

[0037]The hydration equilibrium constant is 1.70×10⁻³. This indicates that H₂CO₃ is not stable in water and gaseous CO₂ readily dissociates at pH of 4.5, allowing CO₂ to be easily removed by degassing or stripping once the seawater has been acidified such that the unstable H₂CO₃ is deprotonated to the predominant carbonate species.

[0038]Electrochemical cells are used in marine, offshore, municipal, industrial, and commercial implementations. The design parameters of electrochemical cells, for example, inter-electrode spacing, thickness of electrodes and coating density, electrode areas, methods of electrical connections, etc., can be selected for different implementations. Aspects and embodiments disclosed herein are not limited to the number of electrodes, the space between electrodes, the electrode material, material of any spacers between electrodes, number of passes within the electrochemical cells, or electrode coating material.

[0039]The Electrolytic-Cation Exchange Module (E-CEM) process is an electrochemical process to reduce seawater pH and convert dissolved bicarbonate ions to CO₂ gas while simultaneously producing hydrogen gas through electrolytic dissociation of water in a cathode compartment.

[0040]FIG. 1 is a schematic of an example of an E-CEM device/process. The E-CEM device of FIG. 1 consists of three compartments: an anode compartment 5, a center compartment 10 (also referred to as a seawater compartment herein), and cathode compartment 15, separated by cation exchange membranes (CEM). The anode and cathode compartments 5, 15 are fed with conductive solutions, such as reverse osmosis (RO) product water with conductivity <200 μS/cm or sodium sulfate solution with conductivity of ˜200-3000 μS/cm.

[0041]With an applied DC current, H⁺ ions generated at the anode are transported through a CEM into the center compartment 10. Seawater feed to the center compartment 10 is acidified and the bicarbonate ions are converted to H₂CO₂. Cations in the seawater are transported through the second CEM into the cathode compartment 15. OH⁻ ions and H₂(g) are generated at the cathode.

[0042]The reactions in the compartments are:

[0043]The pK₁ and pK₂ values are for seawater at 10° C. Other ions may react with the H⁺, such as conversion of borate to boric acid.

[0044]Seawater has a pH of ˜8. FIG. 2 shows the equilibrium diagram for inorganic carbonic species in seawater at 10° C. At pH<4, Over 99.2% of the inorganic carbon is in the form of H₂CO₃.

[0045]CO₂ gas can be extracted from the seawater compartment effluent by vacuum or by membrane degasification, for example. The H₂ gas from the cathode compartment and the CO₂ gas can be used as feedstock to a modified Fischer Tropsch process to produce jet fuel. A molar ratio of 3 H₂ to 1 CO₂ is required for the overall reaction.

[0046]Experiments using a laboratory E-CEM module were carried out with different current densities, seawater flow rates (residence times), seawater compartment thickness, and target pH in the seawater effluent. Calculations were carried out using the data to estimate the H₂:CO₂ ratio. The ratio and the residence time required to achieve specific target pH are plotted in FIGS. 3A and 3B vs. current density. The highest H₂:CO₂ ratio of ˜1.9 is achieved with a current density of ˜900 A/m² and target pH of 3.0.

[0047]Higher H₂:CO₂ ratios are possible by further increasing the current density. The maximum current density with polarity reversal is limited by the type of electrodes. Current densities over 2000 A/m² may be possible but may result in increased energy consumption and unnecessary reduction of pH in the seawater effluent below what is required for conversion of all HCO₃ and CO₃ to H₂CO₃. Electrode life may be shortened.

[0048]The present disclosure proposes an E-CEM process with additional compartments for electrolysis to supply additional H₂ without significant increase in current density. More specifically, aspects and embodiments disclosed herein include an electrochemical process with electrolysis compartments in parallel with the E-CEM cells.

[0049]FIG. 4 shows an electrochemical device 100 with an E-CEM cell unit 102 separated by solid bipolar electrodes 104 from electrolyzers 106 at both ends. The E-CEM cell unit 102 and electrolyzers 106 in this embodiment as well as those described below would take the place of the electrochemical unit in the E-CEM device of FIG. 1 and would thus be disposed between pairs of endplates and endblocks such as illustrated in FIG. 1.

[0050]The E-CEM cell unit 102 includes an E-CEM anodic compartment 112, an E-CEM cathodic compartment 132, and a center compartment 152 (seawater compartment) defined between the E-CEM anodic compartment 112 and the E-CEM cathodic compartment 132. A first E-CEM cation permeable fluidic separator CEM is disposed between the center compartment 152 and the E-CEM anodic compartment 112. A second E-CEM cation permeable fluidic separator CEM is disposed between the center compartment 152 and the E-CEM cathodic compartment 132. An anolyte 165, for example, deionized water or a sodium sulfate solution is fed to the anodic compartment 112 and a catholyte 170, for example, deionized water or a sodium sulfate solution is fed to the cathodic compartment 132. Saline water, for example, seawater 175 is fed to the center compartment 152.

[0051]A first of the two electrolyzers 106 is disposed on an opposite side of the E-CEM anodic compartment 112 from the center compartment 152, and a second of the two electrolyzers 106 is disposed on an opposite side of the E-CEM cathodic compartment 132 from the center compartment 152. A first solid bipolar electrode 104 is disposed between the first of the two electrolyzers 106 and the E-CEM anodic compartment 112. A second solid bipolar electrode 104 is disposed between the second of the two electrolyzers 106 and the E-CEM cathodic compartment 132.

[0052]Each of the electrolyzers 106 includes an electrolyzer anodic compartment 116, an electrolyzer cathodic compartment 136, and an electrolyzer cation permeable fluidic separator CEM disposed between the electrolyzer anodic compartment 116 and the electrolyzer cathodic compartment 136. The E-CEM cation permeable fluidic separators CEM are not necessarily formed of the same material as the electrolyzer cation permeable fluidic separator CEM. Liquid fed to the electrolyzer anodic compartment 116 and/or electrolyzer cathodic compartment 136 may be, for example, deionized water, for example, RO product water, or tap water.

[0053]The electrochemical device 100 further includes, or is in communication with a controller, for example, a specially-programmed general purpose computer, an ASIC, a PLC, or other form of controller known in the art that is configured to receive input regarding the amounts of CO₂ and H₂ produced in the different compartments of the E-CEM cell unit 112 and electrolyzers 106 and/or a ratio of H₂:CO₂ produced by the electrochemical device 100. The controller may utilize this input to modulate one or more operating parameters of the electrochemical device 100, for example, current or power applied across the anode 120 and cathode 140 and/or fluid flow through any of the compartments of the E-CEM cell unit 112 and/or electrolyzers 106 using one or more pumps or valves (not shown so as not to obscure the figure) to achieve a target ratio of H₂:CO₂ produced by the electrochemical device 100.

[0054]The controller may be configured to control the flow rates of the fluids through the E-CEM cell unit 102 and the at least one electrolyzer 106 using one or more pumps or valves (not shown so as not to obscure the figure) and/or the current across the E-CEM cell unit 102 and the at least one electrolyzer 106 that minimizes energy consumption of the electrochemical device 100 while achieving the target ratio of H₂:CO₂ and/or target volumes of H₂ and CO₂ produced by the electrochemical device 100.

[0055]The other embodiments disclosed herein include the same type of controller or controllers performing similar functions and the description of same will not be repeated.

[0056]The direction of current through the electrochemical device 100 can be reversed. The cathode compartments 136 in the electrolyzers 106 provide H₂(g) to supplement the product from the cathode compartment 132 in the E-CEM cell unit 102.

[0057]The electrode reactions in the electrolyzers 106 are as follows:

[0058]The flow rates through each compartment and the current density can be optimized to produce a target H₂:CO₂ ratio from the electrochemical device 100 while minimizing energy requirement as well as capital cost. In some embodiments, the target H₂:CO₂ ratio may be a molar ratio of 3 H₂ to 1 CO₂. The O₂(g) may be used in an adjacent process if, for example, the electrochemical device 100 is part of an energy production or carbon sequestration complex.

[0059]FIG. 5 shows another embodiment of the present disclosure indicated generally at 200, with electrolyzers 106 clustered at one end of the device 200 and adjacent to one another. The two electrolyzers 106 are separated from the E-CEM cell unit 102 by a first solid bipolar electrode 104. The two electrolyzers are separated from one another by a second solid bipolar electrode 104. Such a configuration may be an advantage from the viewpoint of mechanical design. Indicators with the same numbers in the embodiments of FIG. 4 and FIG. 5, as well as in the other embodiments illustrated in the figures represent the same features.

[0060]FIG. 6 shows an alternative embodiment 300 with mesh electrodes M. In the device 300 of FIG. 6 there are three E-CEM cell units 102A, 102B, 102C and three electrolyzers 106A, 106B, 106C. Working from inside to outside, a first of the three electrolyzers 106A is disposed on an opposite side of the E-CEM anodic compartment 11 of the centermost or first E-CEM cell unit 102A from the center compartment 152 of the centermost or first E-CEM cell unit 102A. A second of the three electrolyzers 106B is disposed on an opposite side of the E-CEM cathodic compartment 13 of the centermost or first E-CEM cell unit 102A from the center compartment 152 of the centermost or first E-CEM cell unit 102A.

[0061]A first mesh electrode M forms both the E-CEM anode of the centermost or first E-CEM cell unit 102A and an electrolyzer anode of the first of the three electrolyzers 106A. A single anodic compartment 11 forms both of the E-CEM anodic compartment of the centermost or first E-CEM cell unit 102A and the electrolyzer anodic compartment of the first of the three electrolyzers 106A. A second mesh electrode M forms both the E-CEM cathode of the centermost or first E-CEM cell unit 102A and an electrolyzer cathode of the second of the three electrolyzers 106B. A single cathodic compartment 13 forms both of the E-CEM cathodic compartment of the centermost or first E-CEM cell unit 102A and the electrolyzer cathodic compartment of the second of the three electrolyzers 106B.

[0062]A second of the three E-CEM cell units 102B is disposed on an opposite side of the first of the three electrolyzers 106A from the first of the three E-CEM cell units 102A. The third of the three E-CEM cell units 102C is disposed on an opposite side of the second of the three electrolyzers 106B from the first of the three E-CEM cell units 102A. A third of the three electrolyzers 106C is disposed on an opposite side of the third of the three E-CEM cell units 102C from the second of the three electrolyzers 106B. The anodes and cathodes of each of the three electrolyzers 106A, 106B, 106C and three E-CEM cell units 102A, 102B, 102C are mesh electrodes M. A second single cathodic compartment 13 forms both of the E-CEM cathodic compartment of the second E-CEM cell unit 102B and the electrolyzer cathodic compartment of the second of the three electrolyzers 106B. A third single cathodic compartment 13 forms both of the E-CEM cathodic compartment of the third E-CEM cell unit 102C and the electrolyzer cathodic compartment of the third of the three electrolyzers 106C. A second single anodic compartment 11 forms both of the E-CEM anodic compartment of the third E-CEM cell unit 102C and the electrolyzer anodic compartment of the second of the three electrolyzers 106B. The third of the three electrolyzers 106C includes an unshared electrolyzer anodic compartment 116 on an opposite side from the cathodic compartment 13 shared with the third E-CEM cell unit 102C. The second E-CEM cell unit 102B includes an unshared E-CEM anodic compartment 112 on a side of the second E-CEM cell unit 102B opposite the first of the three electrolyzers 106A.

[0063]Each of the E-CEM center compartments 152, anodic compartments, and cathodic compartments are separated from adjacent compartments with CEMs.

[0064]The total current into each of the mesh electrodes M in the embodiment 300 is double that in the electrodes in the first and second embodiments 100, 200. Thus, it is possible that the H₂ generation rate from each cathode is doubled. Multiple E-CEM cell unit seawater/center compartments 152 and shared electrode compartments 11, 13 may be stacked to increase the fluid throughput and gas production capacity. The polarity across each of the anodes and cathodes may also be reversed.

[0065]Each mesh electrode M is immersed in either the anolyte 165 or catholyte 170. Isolation of the anolyte 165 or catholyte 170 solutions on both sides of any of the mesh electrodes M is not necessary. An inert screen (not illustrated so as not to further complicate FIG. 6) is placed between each side of each mesh electrode M and the adjacent CEM to support the CEMs from deforming into the spaces in the mesh electrodes M and prevent direct electrical contact between the mesh electrode M and the CEMs. The screen can be fabricated from woven plastic strands or extruded plastic netting. The anolyte 165 or catholyte 170 solutions can flow between the adjacent CEMs through the screens and the mesh of the mesh electrodes M. The mesh can promote mixing in solution and enhance electrode reactions and ion transfer at the CEMs. Inert screens may also be placed between each side of each mesh electrode M and the adjacent CEM of the embodiment of FIG. 7, discussed below.

[0066]Each current arrow in FIG. 6 represents a current which depends on the average current density at the respective electrode and the electrode area. The actual surface area of a mesh electrode depends on the design of the mesh and may be higher than the “superficial” area (the area based on the overall width and length of the electrode). The current density is usually expressed as the current divided by the superficial area.

[0067]The anodes are electrically connected, as are the cathodes. The maximum number of electrochemical units in the module is limited by the maximum output current available from the power supply.

[0068]FIG. 7 shows a fourth embodiment 400 with the electrolyzer compartments 106D, 106E, 106F, 106G clustered in the middle of the device 400. This again may be an advantage from the viewpoint of mechanical design. The device 400 of FIG. 7 includes a plurality of electrolyzers 106D, 106E, 106F, 106G disposed between two E-CEM cell units 102D, 102E. In other embodiments a greater or lesser number of electrolyzers may be provided between the two E-CEM cell units 102D, 102E.

[0069]A first mesh electrode M forms both a cathode of one of the two E-CEM cell units, for example, E-CEM unit 102D and an electrolyzer cathode of one of the plurality of electrolyzers, for example, electrolyzer 106D. The first mesh electrode M is disposed within a catholyte compartment 13 shared by the E-CEM unit 102D and electrolyzer 106D. Similarly, a mesh electrode M and a catholyte chamber 13 is shared by E-CEM unit 102E and electrolyzer 106G. A second mesh electrode M forms a cathode of both of two adjacent ones of the plurality of electrolyzers, for example, electrolyzers 106E and 106F. The catholyte chamber 136 shared by electrolyzers 106E and 106F and housing the second mesh electrode M is not shared with either of the E-CEM cell units. The device 400 further includes a third mesh electrode M forming an anode of both of two adjacent ones of the plurality of electrolyzers, for example, either of electrolyzers 106D and 106E or electrolyzers 106 F and 106 G. The third mesh electrode M is disposed within an electrolyzer anodic compartment 116 that is not shared with either of the E-CEM cell units. Further mesh electrodes are form anodes for the E-CEM units 102D, 102E and are disposed in E-CEM anodic chambers 112 on the opposite sides of center compartments 152 of the respective E-CEM units 102D, 102E from the electrolyzers 106D, 106E, 106F, 106G. These further mesh electrodes are not shared with any of the electrolyzers 106D, 106E, 106F, 106G.

[0070]It is to be appreciated that the anodic compartments and cathodic compartments and associated electrodes and power connections illustrated in the device 400 could be switched for one another.

[0071]In any of the embodiments disclosed herein the CEM used in the electrolyzer units may be different from those in the E-CEM units. Proton exchange membranes (PEM) such as, e.g., Nafion™ membranes may be used in the electrolyzer units because of their low permeability to H₂ and O₂ gases and high proton conductivity.

[0072]In any of the embodiments disclosed herein electrolyte provided to any of the electrolyzer anodic compartments, the electrolyzer cathodic compartments, or electrolyte compartments shared by an electrolyzer and a E-CEM cell unit may be deionized water, for example, RO product water, while electrolyte provided to E-CEM electrolyte compartments not shared with an electrolyzer may be deionized water, for example, RO product water, or a sodium sulfate aqueous solution.

[0077]It is to be understood that other arrangements of cells are possible and, thus, the present invention is not limited to the embodiments shown and described herein.

[0078]Aspects and embodiments disclosed herein also contemplate a method of facilitating generation of hydrogen and carbon dioxide from seawater. The method comprises providing an apparatus including at least one electrolytic-cation exchange module (E-CEM) cell unit and a plurality of electrolyzers each disposed between a set of endplates and endblocks and providing instructions to operate the apparatus, and remove hydrogen from cathodic compartments of each of the at least one E-CEM cell unit and plurality of electrolyzers and carbon dioxide from a center compartment of the E-CEM cell unit in amounts sufficient to achieve a target ratio of H₂:CO₂ produced by the apparatus.

[0079]The phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. As used herein, the term “plurality” refers to two or more items or components. The terms “comprising,” “including,” “carrying,” “having,” “containing,” and “involving,” whether in the written description or the claims and the like, are open-ended terms, i.e., to mean “including but not limited to.” Thus, the use of such terms is meant to encompass the items listed thereafter, and equivalents thereof, as well as additional items. Only the transitional phrases “consisting of” and “consisting essentially of,” are closed or semi-closed transitional phrases, respectively, with respect to the claims. Use of ordinal terms such as “first,” “second,” “third,” and the like in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements.

[0080]Having thus described several aspects of at least one embodiment, it is to be appreciated that various alterations, modifications, and improvements will readily occur to those skilled in the art. Any feature described in any embodiment may be included in or substituted for any feature of any other embodiment. Such alterations, modifications, and improvements are intended to be part of this disclosure and are intended to be within the scope of the invention. Accordingly, the foregoing description and drawings are by way of example only.

[0081]Those skilled in the art should appreciate that the parameters and configurations described herein are exemplary and that actual parameters and/or configurations will depend on the specific application in which the disclosed methods and materials are used. Those skilled in the art should also recognize or be able to ascertain, using no more than routine experimentation, equivalents to the specific embodiments disclosed.