TWO-STEP HYDROGEN PRODUCTION

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63/334,898 filed on April 26, 2022. The contents of the aforementioned application are incorporated by reference herein.

TECHNICAL FIELD

[0002] The present disclosure generally relates to methods, processes and systems for hydrogen production. In particular, the present disclosure generally relates to a two-step hydrogen production process from a saline water feedstock without substantial purification.

BACKGROUND

[0003] There is significant interest in the use of hydrogen as an energy source in the power and transport industries and as a chemical feedstock. The demand for hydrogen production is rapidly increasing, in particular because no carbon dioxide is generated upon combustion of hydrogen. Hydrogen may be produced via a number of different processes, the most common being by thermochemical synthesis from a carbon containing feedstock or by electrochemical methods.

[0004] Thermochemical methods are currently the most widely used methods for hydrogen production, generally employing fossil fuels as feedstock via processes such as Steam-Methane Reforming (SMR), Partial Oxidation (PO), Auto Thermal Reforming (ATR) and Coal Gasification. In these processes, the carbonaceous material in the fossil fuels is converted to carbon dioxide, which unless captured may be emitted to the atmosphere

[0005] Electrochemical methods involving the splitting of water into oxygen and hydrogen gases, such as through Solid Oxide Electrolysis (SOE), Alkaline Electrolysis (AE) and Polymer Electrolyte Membrane Electrolysis (PEM), while currently more expensive than the thermochemical examples listed above, may be increasingly desirable as low-carbon alternatives. In such methods, water typically is fed into an electrolytic cell with one or more pairs of electrodes, each pair comprising an anode and a cathode. An electrical voltage is applied to the electrodes in order to drive redox reactions at each to produce hydrogen at the cathode and oxygen at the anode.

[0006] However, when employed on a commercial scale the methods outlined above generally require highly treated and purified water as a feedstock, which adds to the complexity and cost, either through the need for onsite water treatment or from the requirements to obtain and water source of sufficient purity. This is because the methods may be sensitive to small variations in parameters such as the salinity, scaling tendency, pH, Total Organic Content (TOC) and sulfur content of the water. For example, sulfur is known to foul electrodes, leading to a reduction in efficiency and eventually to failure of the electrodes.

[0007] Thus, there is a continuing need to provide improved methods and processes for the production of hydrogen.

SUMMARY

[0008] According to an embodiment of the present disclosure, there is provided a system for producing at least hydrogen and oxygen from a water source, the system comprising: (a) a hydrogen generation unit operable to produce the hydrogen and a hypochlorite containing stream from the water source and (b) an oxygen generation unit, operable to produce oxygen from the hypochlorite containing stream.

[0009] In some embodiments the water source comprises a brine. In some embodiments the water source is oilfield water, mining water, sea water, fresh water or a mixture thereof. In some embodiments the oilfield water is produced water or flowback water. In some embodiments the brine has a chloride ion concentration between about 2,000 ppm and about 30,000 ppm.

[0010] In some embodiments the hydrogen generation unit comprises an electrochemical cell. In some embodiments the electrochemical cell is an unpartitioned bipolar electrochemical cell. In some embodiments the electrochemical cell comprises a plurality of electrodes.

[0011] In some embodiments at least one of the plurality of electrodes comprises a bipolar electrode. In some embodiments at least one of the plurality of electrodes comprises an intermediate electrode. In some embodiments at least one of the plurality of electrodes comprises a non-conductive electrode. In some embodiments at least one of the plurality of electrodes comprises a nickel, stainless steel, titanium, cobalt or conductive polymer electrode. In some embodiments, at least one of the plurality of electrodes comprises a platinum group metal. In some embodiments, the platinum group metal comprises platinum, iridium or ruthenium. In some embodiments, at least one of the plurality of electrodes comprises an electrode catalyst coating. In some embodiments, the electrode catalyst coating comprises an element from row 4 of the periodic table. In some embodiments, the element comprises nickel or iron. In some embodiments at least one of the plurality of electrodes a comprises rod, plate, pipe, pellet or foam electrode.

[0012] In some embodiments the electrochemical cell operates at a pH of between about 6 to about 8. In some embodiments the electrochemical cell operates at a current density of between about 0.05 and about 4 amp/cm ² . In some embodiments the electrochemical cell operates at a temperature of between about 15 °C and about 30 °C.

[0013] In some embodiments the water source flows through the electrochemical cell at a fluid velocity. In some embodiments the fluid velocity is between about 1 meters per hour about 5 meters per hour. In some embodiments the fluid velocity is periodically increased to remove solid deposits within the electrochemical cell. In some embodiments the fluid velocityis increased to about 250 meters per hour or more.

[0014] In some embodiments the system further comprises a hydrogen cleaning unit operable to receive the hydrogen produced by the hydrogen generation unit and remove impurities from the oxygen. In some embodiments the hydrogen cleaning unit is a wash tower. In some embodiments the hydrogen produced by the hydrogen generation unit is contacted by a wash fluid in the wash tower.

[0015] In some embodiments the wash fluid comprises an aqueous fluid, a scale inhibiting agent, a surfactant or a mixture thereof. In some embodiments the aqueous fluid comprises a brine. In some embodiments the aqueous fluid is oilfield water, mining water, sea water, fresh water or a mixture thereof. In some embodiments the oilfield water is produced water or flowback water. In some embodiments the surfactant comprises lauramine oxide, D- Limonene or a mixture thereof. In some embodiments, the scale inhibiting agent comprises a mineral acid, an organic acid, an aminophosphate, a polyphosphate, a phosphate ester or a mixture thereof.

[0016] In some embodiments the system further comprises a water/gas separator configured to receive the hypochlorite containing stream and separate a waste gas stream from the hypochlorite containing stream.

[0017] In some embodiments the oxygen generation unit comprises a catalysis unit configured to receive the hypochlorite containing stream. In some embodiments the catalysis unit comprises a catalyst to catalytically decompose the hypochlorite in the hypochlorite containing stream. In some embodiments the catalyst comprises nickel oxide or cobalt oxide or a mixture thereof. In some embodiments wherein the catalyst is precipitated on a solid support. In some embodiments the solid support is alumina or a zeolite. In some embodiments the catalyst is a surface coating on a metal substrate. In some embodiments the metal substrate comprises pellets, powder or foam. In some embodiments, the foam is a nickel foam. In some embodiments, the catalyst is protected from corrosion using an impressed current, sacrificial anode or a combination thereof.

[0018] In some embodiments the oxygen generation unit also produces a processed brine from the hypochlorite containing stream. In some embodiments the processed brine is received by the hydrogen generation unit to produce the hydrogen and the hypochlorite containing stream. In some embodiments the oxygen generation unit operates at a temperature of between about 15 °C and about 200 °C.

[0019] In some embodiments the system further comprises an oxygen cleaning unit operable to receive the oxygen produced by the oxygen generation unit and remove impurities from the oxygen. In some embodiments the oxygen cleaning unit is a wash tower. In some embodiments the oxygen produced by the oxygen generation unit is contacted by a wash fluid in the wash tower. In some embodiments the wash fluid comprises an aqueous fluid, a scale inhibiting agent, a surfactant or a mixture thereof. In some embodiments the surfactant comprises lauramine oxide, D-Limonene or a mixture thereof. In some embodiments, the scale inhibiting agent comprises a mineral acid, an organic acid, an aminophosphate, a polyphosphate, a phosphate ester or a mixture thereof. [0020] In some embodiments the hydrogen generation unit and the oxygen generation are cleaned by injection of a cleaning solution. In some embodiments the cleaning solution comprises an organic solvent, an aqueous acid, a surfactant or a mixture thereof. In some embodiments the organic solvent comprises a terpene. In some embodiments the terpene comprises D-Limonene. In some embodiments the aqueous acid comprises hydrochloric acid, citric acid, lactic acid or a mixture thereof. In some embodiments wherein the surfactant comprises lauramine oxide, D-Limonene or a mixture thereof.

[0021] In some embodiments the hydrogen generation unit and the oxygen generation can be cleaned by application of an electrical charge to the hydrogen generation unit and the oxygen generation unit.

[0022] According to another embodiment, there is provided a method of producing hydrogen and oxygen from a water source, the method comprising: (a) electrolyzing the water source in a hydrogen generation unit to produce the hydrogen and a hypochlorite containing stream and (b) contacting the hypochlorite containing stream with a catalyst in an oxygen generation unit to produce the oxygen.

[0023] In some embodiments the water source comprises a brine. In some embodiments the water source is oilfield water, mining water, sea water, fresh water or a mixture thereof. In some embodiments the oilfield water is produced water or flowback water. In some embodiments the brine has a chloride ion concentration between about 10,000 ppm and about 30,000 ppm.

[0024] In some embodiments the hydrogen generation unit comprises an electrochemical cell. In some embodiments the electrochemical cell is an unpartitioned bipolar electrochemical cell. In some embodiments the electrochemical cell comprises a plurality of electrodes.

[0025] In some embodiments at least one of the plurality of electrodes comprises a bipolar electrode. In some embodiments at least one of the plurality of electrodes comprises an intermediate electrode. In some embodiments at least one of the plurality of electrodes comprises a non-conductive electrode. In some embodiments at least one of the plurality of electrodes comprises a nickel, stainless steel, titanium, cobalt or conductive polymer electrode. In some embodiments, at least one of the plurality of electrodes comprises a platinum group metal. In some embodiments, the platinum group metal comprises platinum, iridium or ruthenium. In some embodiments, at least one of the plurality of electrodes comprises an electrode catalyst coating. In some embodiments, the electrode catalyst coating comprises an element from row 4 of the periodic table. In some embodiments, the element comprises nickel or iron. In some embodiments at least one of the plurality of electrodes a comprises rod, plate, pipe, pellet or foam electrode.

[0026] In some embodiments the electrochemical cell operates at a pH of between about 6 to about 8. In some embodiments the electrochemical cell operates at a current density of between about 0.05 and about 4 amp/cm ² . In some embodiments the electrochemical cell operates at a temperature of between about 15 °C and about 30 °C.

[0027] In some embodiments the water source flows through the electrochemical cell at a fluid velocity. In some embodiments the fluid velocity is between about 1 meters per hour about 5 meters per hour. In some embodiments the fluid velocityis periodically increased to remove solid deposits within the electrochemical cell. In some embodiments the fluid velocityis increased to about 1250 meters per hour or more.

[0028] In some embodiments the method further comprises the step of passing the hydrogen through a hydrogen cleaning unit to remove impurities from the hydrogen produced by the hydrogen generation unit. In some embodiments the hydrogen cleaning unit is a wash tower. In some embodiments the hydrogen produced by the hydrogen generation unit is contacted by a wash fluid in the wash tower.

[0029] In some embodiments the wash fluid comprises an aqueous fluid, a scale inhibiting agent, a surfactant or a mixture thereof. In some embodiments the aqueous fluid comprises a brine. In some embodiments the aqueous fluid is oilfield water, mining water, sea water, fresh water or a mixture thereof. In some embodiments the oilfield water is produced water or flowback water. In some embodiments the surfactant comprises lauramine oxide, D- Limonene or a mixture thereof. In some embodiments, the scale inhibiting agent comprises a mineral acid, an organic acid, an aminophosphate, a polyphosphate, a phosphate ester or a mixture thereof. [0030] In some embodiments the method further comprises passing the hypochlorite containing stream through a water/gas separator configured to separate a waste gas stream from the hypochlorite containing stream.

[0031] In some embodiments the oxygen generation unit comprises a catalysis unit configured to receive the hypochlorite containing stream. In some embodiments the catalysis unit comprises a catalyst to catalytically decompose the hypochlorite in the hypochlorite containing stream. In some embodiments the catalyst comprises nickel oxide or cobalt oxide or a mixture thereof. In some embodiments wherein the catalyst is precipitated on a solid support. In some embodiments the solid support is alumina or a zeolite. In some embodiments the catalyst is a surface coating on a metal substrate. In some embodiments the metal substrate comprises pellets, powder or foam. In some embodiments, the foam is a nickel foam. In some embodiments, the catalyst is protected from corrosion using an impressed current, sacrificial anode or a combination thereof.

[0032] In some embodiments the oxygen generation unit also produces a processed brine from the hypochlorite containing stream. In some embodiments the processed brine is received by the hydrogen generation unit to produce the hydrogen and the hypochlorite containing stream. In some embodiments the oxygen generation unit operates at a temperature of between about 15 °C and about 100 °C.

[0033] In some embodiments the method further comprises passing the oxygen through an oxygen cleaning unit operable to remove impurities the oxygen produced by the oxygen generation unit. In some embodiments the oxygen cleaning unit is a wash tower. In some embodiments the oxygen produced by the oxygen generation unit is contacted by a wash fluid in the wash tower. In some embodiments the wash fluid comprises an aqueous fluid, a scale inhibiting agent, a surfactant or a mixture thereof. In some embodiments the surfactant comprises lauramine oxide, D-Limonene or a mixture thereof. In some embodiments, the scale inhibiting agent comprises a mineral acid, an organic acid, an aminophosphate, a polyphosphate, a phosphate ester or a mixture thereof.

[0034] In some embodiments the hydrogen generation unit and the oxygen generation are cleaned by injection of a cleaning solution. In some embodiments the cleaning solution is continuously injected. In some embodiments the cleaning solution comprises an organic solvent, an aqueous acid, a surfactant or a mixture thereof. In some embodiments the organic solvent comprises a terpene. In some embodiments the terpene comprises D-Limonene. In some embodiments the aqueous acid comprises hydrochloric acid, citric acid, lactic acid or a mixture thereof. In some embodiments wherein the surfactant comprises lauramine oxide, D-Limonene or a mixture thereof.

[0035] In some embodiments the hydrogen generation unit and the oxygen generation can be cleaned by application of an electrical charge to the hydrogen generation unit and the oxygen generation unit.

[0036] In some embodiments, step (a) is performed at a pH of between about 6 to about 8.

[0037] In some embodiments, steps (a) and (b) are performed at a temperature between about 15 °C to about 100 ^q C.

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In drawings which illustrate embodiments of the invention,

[0039] FIG. 1 is a schematic block diagram of a method for generating hydrogen and oxygen according to an embodiment of the present disclosure;

[0040] FIG. 2 schematically illustrates a system for generating hydrogen and oxygen according to another embodiment;

[0041] FIG. 3 is a plan view of an electrochemical cell according to an embodiment of the present disclosure;

[0042] FIG. 4 is a cross sectional view of another electrochemical cell according to another embodiment;

[0043] FIG. 5 is a cross sectional view of another electrochemical cell according to another embodiment;

[0044] FIG. 6 schematically illustrates a wash tower according to an embodiment of the present disclosure; and [0045] FIG. 7 schematically illustrates a catalysis unit according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

[0046] The following terms shall have the following meanings:

[0047] The term "comprising" and derivatives thereof are not intended to exclude the presence of any additional component, step or procedure, whether or not the same is disclosed herein. In order to avoid any doubt, all compositions claimed herein through use of the term "comprising" may include any additional additive or compound, unless stated to the contrary. In contrast, the term, "consisting essentially of" if appearing herein, excludes from the scope of any succeeding recitation any other component, step or procedure, except those that are not essential to operability and the term "consisting of", if used, excludes any component, step or procedure not specifically delineated or listed. The term "or", unless stated otherwise, refers to the listed members individually as well as in any combination.

[0048] The articles "a" and "an" are used herein to refer to one or to more than one (i.e. to at least one) of the grammatical objects of the article. By way of example, "a solvent" means one solvent or more than one solvent. The phrases "in one embodiment", "according to one embodiment" and the like generally mean the particular feature, structure, or characteristic following the phrase is included in at least one embodiment of the present disclosure and may be included in more than one embodiment of the present disclosure. Importantly, such phrases do not necessarily refer to the same aspect. If the specification states a component or feature "may", "can", "could", or "might" be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.

[0049] The term “about” as used herein can allow for a degree of variability in a value or range, for example, it may be within 10%, within 5%, or within 1% of a stated value or of a stated limit of a range.

[0050] Values expressed in a range format should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but to also include all of the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a range such as from 1 to 6, should be considered to have specifically disclosed sub-ranges, such as, from 1 to 3, from 2 to 4, from 3 to 6, etc., as well as individual numbers within that range, for example, 1 , 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.

[0051] The terms “preferred” and “preferably” refer to embodiments that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the present disclosure.

[0052] The term “optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

[0053] The term “substantially free” refers to a composition in which a particular constituent or moiety is present in an amount that has no material effect on the overall composition. In some embodiments, “substantially free” may refer to a composition in which the particular constituent or moiety is present in the composition in an amount of less than about 10 wt.% or less than about 5 wt.%, or less than about 4 wt.%, or less than about 3 wt.% or less than about 2 wt.% or less than about 1 wt.%, or less than about 0.5 wt.%, or less than about 0.1 wt.%, or less than about 0.05 wt.%, or even less than about 0.01 wt.% based on the total weight of the composition, or that no amount of that particular constituent or moiety is present in the respective composition.

[0054] The term “substantially” means a proportion of at least about 60%, or preferably at least about 70% or at least about 80%, or at least about 90%, at least about 95 wt.%, at least about 97% or at least about 99% or more, or any integer between about 70% and about 100%. For example, removing substantially all of a component from a composition may be the removal of at least about 60 wt.% or at least about 70 wt.%, etc. of the component from the composition.

[0055] The term “wt.%” means weight percent. [0056] The term “ppm” means parts per million and refers to the weight of the component (in milligrams) per liter of solution, i.e. , mg/L.

[0057] The term “oilfield water” as used herein refers to water emanating from oil and gas operations, for example such as produced water or flowback water. Produced water may refer to water that is brought to the surface when extracting oil and gas from the reservoir. Flowback water may refer to water that flows back to the surface upon completion of hydraulic fracturing.

[0058] The present disclosure generally relates to a method and system for producing hydrogen and oxygen from a water feedstock. It has surprisingly been found that the method and system of the present disclosure can tolerate a saline water feedstock without substantial purification. Thus, the methods, and system of the present disclosure are more economical and environmentally friendlier than state of the art methods, processes and systems.

[0059] With reference to FIG.1 , a method 100 for generating hydrogen and oxygen from water feedstock 102 may generally include steps 104 (hydrogen generation) and 106 (oxygen generation). In step 104, hydrogen 108 and hypochlorite solution 110 are generated from water feedstock 102. In some embodiments hydrogen 108 is further purified in a hydrogen cleaning unit. In some embodiments, the method may optionally include the step of pretreating water feedstock 102 in a pretreatment unit. In step 106, oxygen 1 12 and processed brine 114 are generated from hypochlorite solution 110. In some embodiments oxygen 1 12 is purified in an oxygen cleaning unit. In further embodiments, processed brine 1 14 is recycled in step 104 instead of or in addition to water feedstock 102.

[0060] In some embodiments, the method may optionally include the step of injecting a cleaning solution during step 104 and/or step 106 to dislodge and/or dissolve deposits that may form.

[0061] Water feedstock 102 may be an aqueous fluid such as a brine. For example, water feedstock 102 may be oilfield water, such as produced or flowback water emanating from oil and gas operations. In another example water feedstock 102 may be mining water, such as water emanating from mining operations, such as from a lithium chloride mine. In other embodiments, water feedstock 102 may be fresh water, a high salinity brine, or ocean water. Water feedstock 102 may be from any suitable water source. In some embodiments, water feedstock 102 may be used without removal of contaminants, such as hydrogen sulfide (H ₂ S) or organic compounds.

[0062] According to another embodiment, a system 200 operable for performing the method above to produce hydrogen product 208 and oxygen product 212 from water feedstock 202 is generally shown in FIG. 2. Water feedstock 202 may be similar to water feedstock 102 described above. As illustrated, the system 200 may include a hydrogen generation unit 204. The hydrogen generation unit 204 is operable to perform step 104 above and may include an electrolysis unit 216 configured to receive water feedstock 202 and produce hydrogen containing stream 218 and hypochlorite containing stream 220. Hypochlorite containing stream 220 may be an aqueous stream containing hypochlorite ions (and salts thereof) in solution. Hypochlorite containing stream 220 may also contain hypochlorous acid.

[0063] The hydrogen generation unit 204 may further include a hydrogen cleaning unit 222 configured to receive hydrogen containing stream 218 and remove contaminants from hydrogen containing stream 218 to produce hydrogen product 208.

[0064] In some embodiments, hypochlorite containing stream 220 may pass though water gas separator 226, to separate gases (such as hydrogen) from hypochlorite containing stream 220, to produce degassed hypochlorite containing stream 230 and waste gas stream 228. Waste gas stream 228 may be received by waste gas cleaning unit 240 configured to remove contaminants from waste gas stream 228 and produce hydrogen product 208. In some embodiments, hydrogen cleaning unit 222 and waste gas cleaning unit 240 may be a single gas cleaning unit that receives hydrogen containing stream 218 and waste gas stream 228, producing hydrogen product 208.

[0065] The system 200 may also include an oxygen generation unit 206. The oxygen generation unit 206 is operable to perform step 106 referred to in relation to FIG. 1 and may include a catalysis unit 232 configured to receive a source of hypochlorite ions such as hypochlorite containing stream 220 or degassed hypochlorite containing stream 230. Catalysis unit 232 may be configured to catalytically decompose chlorine and oxygen containing compounds and produce oxygen containing stream 234 and processed brine 214. [0066] The oxygen generation unit 206 may further include an oxygen cleaning unit 236 configured to receive oxygen containing stream 234 and remove contaminants from oxygen containing stream 234 to produce oxygen product 212.

[0067] Water feedstock 202 may undergo minimal treatment prior to being received by electrolysis unit 216. In some embodiments, water feedstock 202 may be fed into electrolysis unit 216 directly from a wastewater source without any treatment.

[0068] In some embodiments, system 200 may optionally include a pretreatment unit (not shown) to remove contaminants from water feedstock 202. For example, the pretreatment unit may be configured to perform steps such as filtration, gas flotation to remove suspended solids, organic matter (such as oil and grease) and other mineral matter. The pretreatment unit may be configured to achieve one or more target parameters for water feedstock 202, such as pH, total solids, total organic content, or salinity. In some embodiments, the pH of water feedstock 202 may be adjusted such that the pH within system 200 may be maintained between about 6 and about 8.

[0069] The pretreatment unit may also be configured to perform chemical injection into water feedstock 202. For example, any suitable corrosion inhibitor, scale inhibitor, defoamer/antifoamer, oxygen scavenger and/or hydrogen sulfide scavenger may be added to reduce corrosion, scale deposition, foaming, oxygen content or hydrogen sulfide content.

[0070] In some embodiments, a cleaning solution may be injected into any part of system 200 to dislodge and/or dissolve deposits within system 200. For example, as shown in FIG. 2, cleaning solution 224 may be injected into electrolysis unit 216 and cleaning solution 238 may be injected to catalysis unit 232.

[0071] In some embodiments, water feedstock 202 may include a portion of the tailings water (for example stored water at bitumen recovery mines) from mining and other industrial operations that may require bulk water removal before further concentration, evaporation or crystallization of dissolved and/or suspended solids.

[0072] In some embodiments, water feedstock 202 may comprise mining water (for example from a lithium chloride mine) that may require bulk water removal before further concentration, evaporation, or crystallization of dissolved and/or suspended solids. Hydrogen Generation (Step 104) in the Hydrogen Generation Unit (204)

[0073] As described above in respect of step 104, hydrogen 108 and hypochlorite solution 110 are generated from water feedstock 102. In the embodiment shown in FIG.2, this may be achieved through electrolysis of water feedstock 202 in electrolysis unit 216. Electrolysis unit 216 may be an electrochemical cell shaped, sized and configured to hold any suitable volume of electrolyte, such as water feedstock 202 introduced into electrolysis unit 216 through one or more inlet. The electrochemical cell may include one or more pairs of electrodes, each pair comprising and anode and a cathode. The electrochemical cell may be operated under any suitable conditions to generate hydrogen and a hypochlorite ion containing solution from water feedstock 202.

[0074] The electrochemical cell may be an unpartitioned (i.e., undivided) electrochemical cell, such that there is no physical barrier (such as a membrane) between each anode and cathode, thereby allowing a free flow of electrolyte solution (e.g., water feedstock 202) throughout the electrochemical cell. In some embodiments, the electrochemical cell is an unpartitioned bipolar electrolysis unit, having one or more pairs of driving electrodes and one or more bipolar electrodes in an electrolyte solution. When an electrical current is applied to the driving electrodes, the driving electrodes apply an electrical field across an electrolyte solution, driving electrochemical reactions at the bipolar electrodes.

[0075] Electrolysis unit 216 may be in communication with an alternating current (AC) or direct current (DC) power source that is adequate to provide the electrodes of electrochemical cell with electricity. In an embodiment, the electrical power supplied to the electrochemical cell may have a current density of about 0.1 to about 2 or more ampere per centimeter squared (A/cm ² ). In another embodiment, the electrical power supplied to the electrochemical cell may have a current density of about 0.05 to about 4 or more ampere per centimeter squared (A/cm ² ). The voltage and charge applied to the electrodes may be varied based on factors such as the composition of the electrolyte, the type and condition of the electrodes used, the desired hydrogen production rate, the cost of power, the degree of contaminant deposition on the electrodes and the degree of polarization of the electrode. When operating in DC mode, the electrical potential across the electrodes may be between about 1 and about 6 volts. However, when fouling of the electrodes occurs, the electrical potential may be increased as required to about 135 volts or greater. [0076] Without being limited to any particular theory, the primary reaction at the anode is shown in equation (1), where chloride ions in water feedstock 202 are oxidized to chlorine:

2CI (aq) — * Ch(aq) + 2e (1)

[0077] At a pH of above about 5.4, the chlorine may be retained in the electrolyte

5 solution and is not released as a gas.

[0078] The primary reaction at the cathode is shown in equation (2), where hydrogen ions from water are reduced to hydrogen gas, which also releases hydroxide ions into the solution.

2^0(1) + 2e~ H2(g) + 2OH“(aq) (2) 0 [0079] The overall reaction is shown in equation (3):

2NaCI(aq) + 2^0(1) — > 2NaOH(aq) + H2(g) + Cl2(aq) (3)

[0080] In an unpartitioned electrochemical cell, hydroxide ions produced at the cathode are able to diffuse throughout the electrolyte and may react with the chlorine produced in equation (1) to form hypochlorite ions and hydrogen via equation (4):

2OH (aq) + Cl2(aq) — * 2OCI (aq) + H2(g) (4)

[0081] At a pH of greater than 7, the reaction shown in equation (4) to produce hypochlorite ions may be favored due to the greater concentration of hydroxide ions.

[0082] The electrochemical cell may include one or more pairs of driving electrodes and one or more bipolar electrodes (BPEs). The driving electrodes may be connected to an0 electrical power source and apply a voltage to the electrolyte. The BPEs may not be directly connected to the electrical power source, but when a voltage is applied to the electrolyte in which the BPEs are immersed, the BPEs are inductively powered by potential difference between the driving electrodes. Further, both the driving electrodes and the BPEs provide potential to the electrolyte solution which forces oxidation and reduction reactions at both the5 BPEs and the driving electrodes. [0083] The electrodes of the electrochemical cell may be of any suitable size and shape and may be constructed from any suitable material. For example, the electrodes may be formed as plates, rods, pipes, pellets or as a metallic foam. Examples of suitable materials include, but are not limited to, titanium, nickel, cobalt and stainless steel. In an embodiment, the electrodes are formed from conductive polymer pellets, such as those formed from conducting polymers of polypyrrole, polythiophene, polyaniline and poly(3,4- ethylenedioxythiophene) (PEDOT).

[0084] In some embodiments, the conductive polymer pellets are formed from nonconducting polymers (such as polyvinyl chloride, polyethylene or polyethylene terephthalate) impregnated with a transition metal (such as finely divided nickel or finely divided titanium).

[0085] In some embodiments, one or more of the electrodes may have a surface coating of an electrochemical catalyst (known as an electrode catalyst coating) such as a platinum group metal catalyst such as platinum, iridium or ruthenium metal oxide. The electrochemical catalyst may include one or more other metals as a doping agent, such as copper, zinc or magnesium. A doping agent (or dopant) is a trace of impurity element that is introduced into the electrochemical catalyst to alter its original electrical properties. The amount of doping necessary to cause changes is typically very low.

[0086] In some embodiments, the surface coating of one or more of the electrodes may comprise one or more elements from row 4 of the periodic table, such as nickel or iron.

[0087] In some embodiments the driving electrodes are formed from the same material as the BPEs.

[0088] With reference to FIG. 3, an exemplary configuration for an electrochemical cell according to various embodiments of the invention is depicted at 300. Electrochemical cell 300 includes an outer wall 302 which defines an inner cavity 304 for holding electrolyte, such as water feedstock 202. Electrolyte may enter inner cavity 304 through inlet 306 and may exit through outlet 308. Product gases (such as hydrogen containing stream 212) may exit electrochemical cell 300 though outlet 309. In other embodiments, electrochemical cell 300 may have more than one inlet and/or outlet, which may be configured in any suitable arrangement. [0089] In some embodiments, electrochemical cell 300 may include a separate water/gas separator (not shown in FIG. 3 but may be similar to water/gas separator 226) at the outlet 308 or 309 for separation of product gases (i.e., hydrogen containing stream 212) and electrolyte (i.e., hypochlorite containing stream 220) produced by electrochemical cell 300. In the presence of a water/gas separator at outlets 308 or 309, one of more of outlets 308 or 309 may be eliminated. Electrochemical cell 300 includes central electrode 310 and outer electrodes 312a and 312b. Generally speaking, the central electrode will have an opposite charge to outer electrodes 312a and 312b. Electrodes 310, 312a, 312b may be driving electrodes as described above in electrical communication with a power source. Outer electrodes 312a and 312b may be positioned at opposite ends of electrochemical cell 300. In between electrodes 312a, 312b and central electrode 310 may be a series of bipolar electrodes 314. Electrochemical cell 300 may include between 2 and 8 bipolar electrodes 314 as described above.

[0090] In some embodiments, a water/gas separator for electrochemical cell 300 may not be required. For example, this may be the case in applications where the purity requirements for the oxygen product 212 is not high.

[0091] As shown in FIG. 3, electrodes 310, 312a, 312b, 314 are plate electrodes. Whilst as shown the electrodes 310, 312a, 312b, 314 are orientated generally horizontally within electrochemical cell 300, in other embodiments, the electrodes may be configured in other orientations, such as vertically. In some embodiments, adjacent electrodes may be separated by a gap (such as gap 316) of between about 2.5 mm and about 3.5 mm. In an embodiment, the gap is about 3 mm.

[0092] In various embodiments, electrodes 310, 312a, 312b, 314 are between about 0.25 mm and about 2 mm in thickness. In an embodiment, electrodes 310, 312a, 312b, 314 are about 0.5 mm in thickness.

[0093] In various embodiments, electrodes 310, 312a, 312b, 314 are plate electrodes having a thickness of about 0.5 mm and adjacent electrodes may be separated by a gap of about 3 mm. [0094] In various embodiments, electrodes 310, 312a, 312b, 314 are metal foam electrodes having a thickness of about 1 .6 mm or more and adjacent electrodes may be separated by a gap of about 3 mm.

[0095] Referring to FIG. 4, another exemplary configuration for an electrochemical cell is depicted at 400. Electrochemical cell 400 includes a central electrode 410 which may be a pipe or rod electrode. Electrochemical cell 400 also includes an outer electrode 412, which as shown in FIG. 4 is a pipe electrode that defines the inner cavity 404 of electrochemical cell 400. Electrodes 410, 412 may be driving electrodes as described above in electrical communication with a power source.

[0096] Electrochemical cell 400 may be oriented in any orientation such as vertically or horizontally. Similar to electrochemical cell 300, outlet wall 412 of electrochemical cell 400 may include one or more inlets for electrolyte and one or more outlets for electrolyte and/or product gases (not shown in FIG. 4). Similar to electrochemical cell 300, product gases and electrolyte may leave from separate outlets through outer wall 412 of electrochemical cell 400. Similar to some embodiments of electrochemical cell 300, in some embodiments of electrochemical cell 400, there is a separate water/hydrogen separator (not shown) at one of the outlets for separation of for separation of product gases (i.e. , hydrogen containing stream 212) and electrolyte (i.e., hypochlorite containing stream 220) leaving electrochemical cell 400. Electrochemical cell 400 includes one or more bipolar electrodes 414 (shown as white filled circles in FIG. 4), which may be similar to bipolar electrodes 314 described above. Bipolar electrodes 414 may be rod electrodes which may be hollow or made from metal foam.

[0097] Electrochemical cell 400 may also include one or more intermediate electrodes 418 (shown as grey filled circles in FIG. 4), which may be powered electrodes (i.e., driving electrodes), similar to central electrode 410 and outer electrode 412. In an embodiment, intermediate electrodes 418 are hollow electrodes.

[0098] The number of electrodes of electrochemical cell 400 that are powered (i.e., driving electrodes) may be selected according to factors such as the conductivity of the electrolyte and the diameter of outer electrode 412. For example, when outer electrode 412 is a positively charged driving electrode with a relatively large diameter (for example about 60 mm) and the electrolyte comprises about 3000 ppm NaCI, electrochemical cell 400 may comprise a first series of negatively charged powered intermediate electrodes arranged in a circular configuration. In some embodiments, the first series of negatively charged powered intermediate electrodes may be spaced from outer electrode 412 by about 14 mm.

[0099] In some embodiments electrochemical cell 400 may further comprise a second series of positively charged powered intermediate electrodes arranged in a circular configuration within the circle formed by the first series. In some embodiments, the second series of positively charged powered intermediate electrodes may be spaced from the first series of negatively charged powered intermediate electrodes by about 14 mm.

[00100] In other embodiments, electrochemical cell 400 may include any number of additional spaced apart series of negatively or positively charged powered intermediate electrodes.

[00101] In another example, when the electrolyte comprises a sufficiently high salt concentration, for example about 10,000 ppm NaCI or more electrochemical cell 400 may not require any intermediate electrodes regardless of the diameter of outer electrode 412, in part due to the high conductivity of the electrolyte.

[00102] Adjacent bipolar electrodes 414 and/or intermediate electrodes 418 may be separated by a gap (such as gap 416) of between about 2.5 mm and about 3.5 mm. In an embodiment, the gap is not greater than about 3.5 mm.

[00103] Electrodes 410, 412, 414 and 418 may have a circular cross-sectional shape or any other suitable shape such as square or triangular.

[00104] With reference to FIG. 5, another exemplary configuration for an electrochemical cell is depicted at 500. Electrochemical cell 500 may generally be similar to electrochemical cell 400 described above and may be oriented in any orientation such as vertically or horizontally. Electrochemical cell 500 includes a central electrode 510 and an outer electrode 512, which may be similar to central electrode 410 and outer electrode 412 described above in respect of FIG. 4.

[00105] Electrochemical cell 500 may also include one or more bipolar electrodes 514 (shown as white filled circles in FIG. 5), which may be similar to bipolar electrodes 314 and 414 described above in relation to FIG. 3 and FIG. 4. In some embodiments, bipolar electrodes 414 may be pellet electrodes formed from conductive polymer pellets. Electrochemical cell 500 may also include one or more intermediate electrodes 518 (shown as grey filled circles in FIG. 5), which may be similar to intermediate electrodes 418 described above in relation to FIG. 4. Electrochemical cell 500 may also include one or more non- conductive electrodes 520 (shown as hatched circles in FIG. 5) made from a mixture of conductive and non-conductive pellets. The pellets may be spherical or tablet shaped. The non-conductive electrodes may function to limit electrical short circuits within electrochemical cell 500.

[00106] The ratio of non-conductive to conductive pellets is driven by the need to minimize direct contact between conductive pellets to stop short-circuiting the electricity. The density and shape of the conductive and non-conductive pellets may be as close as practical to being identical, such that it is possible to easily mix both and arrive at a uniform mixture of conductive and non-conductive pellets. Theoretically, each conductive pellet should only be touching non-conductive pellets. This may be achieved by providing about 12 non-conducting pellets surrounding each conductive pellet. The optimal ratio may be dependent on the properties of the electrolyte and may be calculated or determined experimentally.

[00107] In various embodiments, bipolar and non-conductive electrodes 514, 520 may be between about 2 and about 3 mm in diameter.

[00108] The number, diameter and spacing of the driving, bipolar, intermediate and non-conductive electrodes described above may be selected, in part based on the properties of the electrolyte and therefore the properties of water feedstock 202. The optimal number of driving, bipolar, intermediate and non-conductive electrodes may be calculated or determined experimentally.

[00109] In an embodiment, when the electrolyte has a high carbonate concentration, a lower current density and a lower voltage may be beneficial in order to reduce solids deposition on the electrodes. In some embodiments, this may be achieved by providing an increased number of intermediate electrodes in the electrochemical cell. [00110] Without being limited to any particular theory, additional side-reactions may occur within the electrochemical cell as will be outlined below. Firstly, the following reaction as shown in equation (5) to produce hypochlorous acid (HOCI) is a side-reaction that may occur at the anode of the electrochemical cell :

Chfaq) + H2O(|) — HOCI(aq) + H ⁺ (aq) + Cl (aq) (5)

[00111] Secondly, the following reaction as shown in equation (6) may occur in the electrochemical cell at a pH in excess of 5.4:

HOCI(aq) + OH (aq) — OCI (aq) + H2O ) (6)

[00112] Hypochlorous acid (HOCI) is an important product for processes that generate biocides and when produced from brine that has undergone minimal water treatment, and increased production of Hypochlorous acid may indicate higher production of chlorine gas within the electrochemical cell. Hypochlorous acid and chlorine production may be minimized by controlling the pH and operating temperature of electrolysis unit 216. Any hypochlorous acid that is produced is decomposed, along with hypochlorite ions in oxygen generation unit 206.

[00113] The following reaction to produce oxygen is shown in equation (7) that may occur in the electrochemical cell and is more favored at a pH higher than 8:

4OH ^_ (aq) — > 02(g) + 2H2O(i> + 4e~ (7)

[00114] Further, the following minor side-reaction to produce oxygen shown in equation

8 may occur at the anode of the electrochemical cell:

2H2O“(aq) — > 02(g) + 4H ⁺ (aq) + 4e~ (8)

[00115] The reaction shown in equation 8 is the primary reaction at the positively charged electrode (anode) of many commercial water electrolyzers. However, in the process of the currently disclosed invention, the production of oxygen in the electrochemical cell is undesirable and may be minimized by selecting the chloride solution (i.e., water feedstock 202) for the electrolyte that enters the electrochemical cell. [00116] The following reaction to produce chlorate ion (CIOs-), an undesirable contaminant is shown in equation (9) and may occur within the electrochemical cell: q

6HOCI(aq) + SHsOfl) — > “02(g) + 4CI (aq) + 2CIOs (aq) + 12H ⁺ (aq) + 6e (9)

[00117] The above reaction products may be reduced or substantially eliminated by controlling the conditions within the electrochemical cell in order to produce the desired product and to minimize production of undesirable side products, as will be discussed in more detail below.

[00118] The electrolyte within the electrochemical cell (i.e., water feedstock 202) may be maintained at a relatively low temperature, which minimizes dissolution of chlorine gas from the electrolyte. A low temperature may also favor the production of hypochlorite ions via equation (4) as the reaction shown in equation (4) is promoted over the oxygen forming reactions shown in equations (7) and (8).

[00119] In some embodiments, the electrochemical cell may be operated at a temperature of between about 15 °C and about 30 °C.

[00120] According to some embodiments, the electrochemical cell of electrolysis unit 216 may be operated at an elevated pressure, i.e., by pumping water feedstock 202 into electrolysis unit 216 at an elevated pressure. Whilst operation at elevated pressure may result in reduced hydrogen production efficiency, it may be desirable to operate the electrochemical cell at an elevated pressure such that hydrogen is generated at an elevated pressure. This will reduce the cost of subsequently compressing hydrogen product 208. In some embodiments, the electrochemical cell of electrolysis unit 216 may be operated up to about 400 pounds per square inch gauge (psig).

[00121] According to particular embodiments, the electrochemical cell may be operated at atmospheric pressure.

[00122] The chloride concentration of the water feedstock may be selected to provide a balance between greater electroconductivity whilst minimizing solids deposition. According to some embodiments, the water feedstock entering the electrochemical cell may have a chloride concentration of between about 1000 and about 100,000 parts per million of negatively charged chloride ions (Cl-) . In some embodiments, the chloride ion concentration is between about 2,000 ppm and about 30,000 ppm. In some embodiments, the chloride concentration is between about 10,000 ppm and about 30,000 ppm. In a specific embodiment the water feedstock 202 may have a chloride concentration of about 3000 parts per million of negatively charged chloride ions (Cl-) .

[00123] The electrolyte within the electrochemical cell may be maintained between pH levels of 6 and 8. This may be achieved through adjustment of the pH of water feedstock 202 prior to entering the electrochemical cell, or through injection of chemical additives to the electrochemical cell to adjust the pH during operation. Through maintaining the pH within this range, the optimal ratio of chlorine compounds may be maintained within the electrolyte, such that minimal chlorine gas (generated at lower pH) and oxygen (generated at higher pH) are produced in the electrochemical cell. Further, contamination of product gases (such as hydrogen containing stream 218) may be reduced and corrosion of components of system 200 may be reduced and the production of mineral scale may be reduced.

[00124] In some embodiments, the flow of electrolyte through the electrochemical cell may be between about 1 and about 5 meters per hour (m/h).

[00125] The deposition of solids within the electrochemical cell may undesirably affect performance such as by blocking and thereby reducing the performance of the electrodes or by inhibiting the flow of electrolyte within the electrochemical cell. This may be reduced by utilizing a relatively high velocity of electrolyte through the electrochemical cell during cleaning of system 200 (or components thereof) to minimize solid deposition.

[00126] In some embodiments, the velocity of the electrolyte through the electrochemical cell may be increased to 250 m/h or greater to remove/dislodge deposited solids.

[00127] In some embodiments, such as during extreme descaling of the electrochemical cell, the velocity of the electrolyte through the electrochemical cell may be increased to about 10 meters per second (m/s).

[00128] In some embodiments, a relatively high velocity of the electrolyte through the electrochemical cell may be used for about 15% of the time the electrochemical cell is operating. Increases in electrolyte velocity may be maintained for between about 5 and about 1000 seconds at a time.

[00129] In various embodiments, the bipolar electrochemical cell electrical efficiency of the electrolysis unit 216 may be between about 60 and 90% or higher when water feedstock 202 has a chloride ion concentration of 10,000 parts per million (ppm) or higher. Under these conditions, electrical consumption is typically above about 50 Kilowatts per kilogram (kW/kg) of hydrogen produced, however, this may vary in either direction based on factors such as the chloride ion concentration of water feedstock 202. By adjusting parameters such as the properties of water feedstock 202 and the operating conditions of the electrochemical cell a balance may maintained between hydrogen production rate versus scale deposition rate.

[00130] The following reaction shown in equation (10) may occur in the electrochemical cell is the decomposition of hypochlorous acid (HOCI) in the bulk of the electrolyte solution:

2HOCI( _aq ) — > 2HCI( _aq ) +O ₂ (g) (10)

[00131] Hydrochloric acid (HCI) remains in the electrolyte at pH equal to or less than about 6. This reaction is undesirable as it may lead to oxygen contamination of the hydrogen product. However, this reaction may be beneficial in minimizing deposits within the system, such as at the electrodes, in catalysis unit 232 and wherever there may be a flow eddy or stagnant fluid flow.

[00132] The following reaction shown in equation (11 ) occurs because the electrochemical cell has no physical barrier between the anode and cathode, resulting in the migration of negatively charged hypochlorite ions from the anode to the cathode.

OCI- + H ₂ O + 2e- Cl- + 2OH- (1 1 )

[00133] The reaction shown in equation (11 ) may be managed through control of electrolyte pH. At higher pH (with higher hydroxide concentrations), more oxygen is produced at the anode. However, the reaction shown in equation (11 ) may also beneficially maintain the concentration of hydroxide ions in the electrolyte available at the anode which, in turn, promotes the formation of hypochlorite ions via equation (4). [00134] The following reaction shown in equation (12) may occur in the electrochemical cell and may be favored at higher temperatures:

2HOCI( _aq) + OC|-( _aq) + 2OH CIO ₃ -(a _q) + 2HCI( _aq) + 2H ₂ O (12)

[00135] The reaction shown in equation (12) may be mitigated controlling and optimizing parameters such as electrolyte velocity in the electrochemical cell, maintaining temperatures in the electrolytic cell at or below about 30 °C, maintaining pH, maintaining current density at the electrode as high as possible, as well as sufficient chloride ion concentration in water feedstock 202.

[00136] For example, chlorate ion formation may approach zero at temperatures below about 15 °C, and near neutral pH. However, in some embodiments it may still be desirable to quickly destruct the hypochlorite (in in catalysis unit 232) or dilute hypochlorite containing stream 200 to reduce possible chlorate formation after the electrolyte leaves the electrochemical cell.

[00137] Further, the presence of hypochlorous acid may inhibit the formation of chlorate ions. Depending upon the composition of water feedstock 202, it may be advantageous to operate the electrochemical cell at a lower pH to promote formation of hypochlorous acid.

[00138] As described above, the formation of HCI may be beneficial, as it reduces deposit formation within the apparatus as described above.

[00139] The following reaction shown in equation (13) may occur in the electrochemical cell. It is favored by a temperature in excess of 30 degrees Celsius.

2HOCI(a _q ) — * OCI (a _q ) + H ₂ O(|) + Cl (a _q ) (13)

[00140] The reaction shown in equation (13) may proceed to completion in catalysis unit 232 due to the destruction of the hypochlorite ion, as will be discussed in more detail below.

[00141] Referring again to FIG. 2, hypochlorite containing stream 220 may exit electrolysis unit 216, such as through an outlet similar to through outlet 308 of electrochemical cell 300. Hypochlorite containing steam 220 may typically contain between about 1 and about 30,000 ppm hypochlorite ions (and accompanying hypochlorous acid), produced in electrochemical cell via equation (4). Hypochlorite containing steam 220 may also contain smaller qualities of chlorate ion (CIOs-).

[00142] At any time, hypochlorous acid and hypochlorite ion may co-exist in solution and will convert from one to the other, depending upon the solution pH. For example, at pH 6, about 3% of the hypochlorite in solution may exist as hypochlorite and 97% as hypochlorous acid, while if the pH is brought up to pH 8 about 25% of the solution may exist as hypochlorous acid and 75% as hypochlorite.

[00143] The presence of hypochlorous acid appears to inhibit the formation of chlorate, such that depending upon the composition of water feedstock 202, it may be advantageous to operate the electrochemical cell towards the lower part of the preferred pH range.

[00144] Chlorate formation may approach zero at temperatures of about 15 °C and lower and at near neutral pH. However, it is necessary to quickly destruct the hypochlorite or dilute it significantly to avoid possible chlorate formation after the electrolyte leaves the electrochemical cell.

[00145] As previously described, the electrochemical cell of electrolysis unit 216 may be operated at an elevated pressure. At elevated pressures, hypochlorite containing stream 220 may contain increased quantities of dissolved gases such as hydrogen produced via equation (2), due to their increased solubility at higher pressures. In some embodiments, hypochlorite containing stream 220 may pass through a pressure reduction apparatus (not shown in FIG. 2) located downstream of electrolysis unit 216 to reduce the pressure of hypochlorite containing stream 220 and cause dissolved gasses to leave solution. The pressure reduction apparatus may be any suitable apparatus for reducing the pressure of hypochlorite containing stream 220, such as any type of valve, orifice plate, flow resistance or vertical displacement. In embodiments where the electrochemical cell of electrolysis unit 216 operates at atmospheric pressure, the pressure reduction apparatus may not be required.

[00146] In some embodiments, the pressure reduction apparatus may include a heater, configured to maintain hypochlorite containing stream 220 within a temperature range of between about 15 °C and about 100 °C. [00147] As described above, hypochlorite containing stream 220 from electrolysis unit 216 may pass though water/gas separator 226, to separate gases from hypochlorite containing stream 220, to produce degassed hypochlorite containing stream 230 and waste gas stream 228. Waste gas stream 228 may be received by waste gas cleaning unit 240. In embodiments where system 200 includes a pressure reduction apparatus, the water/gas separator 226 may be located downstream from the pressure reduction apparatus.

[00148] In some embodiments, water/gas separator 226 may not be required. For example, this may be the case in applications where the purity requirements for the oxygen product 212 is not high.

[00149] According to various embodiments, waste gas stream 228 may comprise hydrogen and about 10% or less of contaminant gases such as chlorine, oxygen and water vapor.

[00150] According to various embodiments, degassed hypochlorite containing stream 230 may typically contain between about 1000 ppm and 5 ppm sodium hypochlorite (plus accompanying hypochlorous acid). Degassed hypochlorite containing stream 230 may also small quantities of chlorate ion (CIOs-).

[00151 ] Water gas separator 226 may be any suitable apparatus operable to separate gases from hypochlorite containing stream 220, such as a vertical or horizontal vapor-liquid separator.

[00152] In some embodiments, water/gas separator 226 may be part of a gas cleaning apparatus such as waste gas cleaning unit 240.

Hydrogen Cleaning Unit 222

[00153] According to various embodiments, hydrogen containing stream 218 exiting electrolysis unit 216 may contain at least about 90% hydrogen based on the total volume of the composition for example, at least about 92% hydrogen, at least about 94% hydrogen, at least about 96% hydrogen, at least about 98% hydrogen, or at least about 99% hydrogen based on the total volume of the composition. Hydrogen containing stream 218 may contain small amounts of other gases such as oxygen, chlorine and water vapor. Hydrogen containing stream 218 may be water saturated and the water vapor content may be pressure and temperature dependent.

[00154] As described earlier in respect of FIG. 2, hydrogen containing stream 218 may be received by hydrogen cleaning unit 222, which is configured to remove contaminants such as oxygen and water vapor and produce hydrogen product 208. Hydrogen cleaning unit 222 may be any gas cleaning apparatus suitable to remove impurities and contaminants from a gaseous mixture. In some embodiments, the gas cleaning apparatus is a washing unit such as a wash tower.

[00155] Referring to FIG. 6, a representative wash tower is shown generally at 600. Wash tower 600 and may include a vertically or horizontally orientated vessel 602. Vessel 602 may be any suitable size or shape and is configured to receive an input gas 604 at a lower end. Input gas 604 may pass through a gas distributor 606 operable to distribute input gas 602 across vessel 602.

[00156] Vessel 602 may also receive wash fluid 608 at an upper end, which may pass through a wash fluid distributor 610 operable to distribute wash fluid 608 across vessel 602. Wash fluid 608 may be continuously fed into wash tower 600 during operation of system 200 and is configured for the removal of contaminants from input gas 604. Wash fluid 608 may flow in a generally downwards direction in vessel 602. Input gas 604 mixture may flow in a generally upwards direction in vessel 602 and contacts wash fluid 608 in central region 612. As input gas 604 contacts wash fluid 608, impurities are removed from input gas 604 from the mixture. Washed gas 614, which in this case is hydrogen product 208 referred to in respect of FIG. 2, may be collected by outlet collector 620 and exit the upper end of vessel 602. Waste wash fluid 616, which is wash fluid 608 that now contains impurities or reaction products from impurities of input gas 604, may be collected in water collection tray 618 and exits the lower end of vessel 602. Waste wash fluid 616 may proceed to catalysis unit 232 described in respect of FIG.2, or to a separate catalysis unit entirely, which may be similar to catalysis unit 232. Alternatively, waste wash fluid 616 may be disposed of by any suitable method, such as injection into a disposal well. [00157] Wash tower 600 may also include trays or packing material in central region 612 such as are found in commercial distillation equipment, for example, those manufactured by Koch-Glitsch, to increase liquid vapor contact between wash fluid 608 and input gas 604. The packing material may comprise any suitable inert solid material such as pea gravel or glass beads

[00158] Wash fluid 608 may be any suitable fluid that is operable to remove impurities from input gas 604. This may be achieved for example, by absorption or by chemical reaction. In various embodiments, the wash fluid 608 includes an aqueous wash solution which may be configured to react with chlorine gas in input gas 604, forming hypochlorite and other chlorine containing compounds, which are carried in waste wash fluid 616.

[00159] Wash fluid 608 may be chemically treated prior to entering wash tower 600. For example, the pH of wash fluid 608 may be adjusted to have a higher pH that the electrolyte within the electrochemical cell of electrolysis unit 216. In an embodiment, wash fluid 608 may have a pH between about 7 and about 10.

[00160] In some embodiments, wash fluid 608 may comprise one or more chemical inhibitors which may be added to wash fluid 608 solution prior to injection into wash tower 600. For example, any suitable corrosion inhibitor, scale inhibitor (scale inhibiting agent), defoamer/antifoamer, oxygen scavenger and/or hydrogen sulfide scavenger may be added to reduce corrosion, scale deposition, foaming, oxygen content or hydrogen sulfide content within system 200. The type and concentration of chemical inhibitor may be selected based on the composition of water feed stock 202, wash fluid 608 and/or the cleaning solution (such as cleaning solutions 224 and 238).

[00161] The scale inhibitor may comprise one or more of: a citrate ion source, an aminophosphonate, a polyphosphate, a phosphate esters, a phosphonates, a polyphosphonate, a polycarboxylic, a phosphino polymer, a polyphospinate, a polysulfonate, an aminocarboxylate chelate and a aminophosphonate.

[00162] The corrosion inhibitor may comprise one or more of: a phosphate, a polyphosphate, a tungstate, a silicate, a nitrite, a molybdate, a pyrovanadates, a phosphate ester, an amine salt of a polycarboxylic acid, a quaternary ammonium salt, a quaternary iminium salts, an amidoamine, an imidazoline, a polyhydroxy amine or amide, an ethoxylated amine or amide, a methyl substituted nitrogen containing aromatic heterocycle, a thiosulphate, a mercaptocarboxylic acid and a polyaminoacids.

[00163] The defoamer/antifoamer may comprise one or more of: a silicone, a fluorosilicate and a polyglycol.

[00164] The oxygen and hydrogen sulfide scavengers may comprise one or more of: a bisulfide (such as sodium bisulfide), a sulfite (such as sodium sulfite), a metabisulfite, a dithionate salt, a hydrazine, a guanidine, a semicarbazide, a carbohydrazide, hydroxylamine, an oxime, a triazine and an aldehyde.

[00165] In various embodiments, wash fluid 608 may comprise an aqueous phase. Wash fluid 608 may also comprise an organic phase. In some embodiments, Wash fluid 608 may include an aqueous phase and an organic phase that are emulsified together, such as by addition of a suitable emulsifier.

[00166] In some embodiments, wash fluid 608 may include a surfactant to assist with dislodging and/or dissolving deposits within system 200. For example, the surfactant may include lauramine oxide or D-limonene.

[00167] In an embodiment, the hydrogen wash solution is water feedstock 202 which may be chemically treated prior to entering wash tower 600.

[00168] In some embodiments, wash fluid 608 is injected into the wash tower 600 at a temperature that is less than the temperature of the water feedstock entering electrolysis unit 216. For example, the temperature of the aqueous wash solution may be about 15 °C less than the temperature of the water feedstock entering electrolysis unit 216, which may improve chlorine gas removal from input gas 604.

[00169] In an embodiment the aqueous wash solution may include an oxygen scavenger, such as sodium bisulfide or sodium sulfite, to absorb oxygen and chlorine from the gaseous mixture. When an oxygen scavenger is employed, both oxygen and chlorine will be absorbed by the oxygen scavenger and hypochlorite ions may not be formed, which may reduce or eliminate the need for processing of hypochlorite ions of waste wash fluid 616 in a downstream catalysis unit.

[00170] In an embodiment, hydrogen cleaning unit 222 is a wash tower similar to wash tower 600 as described above, where input gas 604 is hydrogen containing stream 218 and washed gas 614 is hydrogen product 208.

[00171] As described above, waste gas stream 228 may be received by waste gas cleaning unit 240, which may be a wash tower constructed similarly and operating in a similar manner to wash tower 600 where input gas 604 is waste gas stream 228. In some embodiments, washed gas 614 is hydrogen product 208 that is produced from waste gas stream 228. In some embodiments, the hydrogen products from hydrogen cleaning unit 222 and waste gas cleaning unit 240 may be combined together or may proceed separately to downstream processing steps or use. The waste wash fluid exiting waste gas cleaning unit 240 may proceed to catalysis unit 232 or may proceed to a separate catalysis unit, which may be similar to catalysis unit 232.

[00172] In other embodiments, a waste gas product 242 is produced by waste gas cleaning unit 240, which may be vented to the atmosphere through an atmospheric vent (not shown in FIG. 2).

[00173] In some embodiments, hydrogen containing stream 218 and waste gas stream 228 may instead both be received by a single gas cleaning apparatus, which may be similar to wash tower 600 described above.

[00174] In another embodiment, the gas cleaning apparatus (e.g., hydrogen cleaning unit 222, waste gas cleaning unit 240 and/or oxygen cleaning unit 236) is a pressure swing absorber (PSA).

[00175] In another embodiment, the gas cleaning apparatus (e.g., hydrogen cleaning unit 222, waste gas cleaning unit 240 and/or oxygen cleaning unit 236) is an activated carbon/charcoal bed. The activated carbon/charcoal bed may be a chemically impregnated activated carbon/charcoal bed. [00176] In another embodiment the gas cleaning apparatus (e.g., hydrogen cleaning unit 222, waste gas cleaning unit 240 and/or oxygen cleaning unit 236) may comprise a wash tower similar to wash tower 600, followed by an additional purification step. In some embodiments the additional purification step may comprise a platinum group metal catalytic converter configured to remove oxygen from the washed gas exiting the wash tower. In other embodiments, the additional purification step may comprise a pressure swing absorber (PSA) or an activated carbon/charcoal bed. The activated carbon/charcoal bed may be a chemically impregnated activated carbon/charcoal bed.

[00177] Hydrogen product 208, produced as described herein, may be substantially free of impurities such as oxygen and chlorine. In some embodiments, hydrogen product 208 may contain less than about 100 ppm oxygen. In some embodiments, hydrogen product 208 may contain more than about 95% hydrogen by volume, based on the total volume of the hydrogen product 208. In other embodiments, hydrogen product 208 may contain more than about 96% hydrogen by volume, or more than about 97% hydrogen by volume, or more than about 98% hydrogen by volume, more than about 99% hydrogen by volume, or about based 99.999% hydrogen by volume based on the total volume of hydrogen product 208.

Oxygen Generation (Step 106) in the Oxygen Generation Unit (206)

[00178] As described above in reference to FIG. 1 , oxygen 112 and processed brine 1 14 are generated from hypochlorite solution 110 in step 106. In the embodiment shown in FIG.2, this may be achieved by oxygen generation unit 206 operable to perform step 106.

[00179] Oxygen generation unit 206 may include catalysis unit 232 configured to react a hypochlorite ion source, such as from hypochlorite ion containing stream 220 or degassed hypochlorite containing stream 230 (which may also contain hypochlorous acid) and produce oxygen containing stream 234 and processed brine 214. Catalysis unit 232 may include a catalyst bed over which oxygen and chlorine containing compounds such as hypochlorite and hypochlorous acid may be catalytically decomposed.

[00180] As shown in equation (13) below, hypochlorite ions may be decomposed over the catalyst bed of catalysis unit 232 to form chloride ions and release oxygen gas.

2OCI (aq) — * Cl (aq) + 02(g) (13) [00181] Further, as shown by equation (14), hypochlorous acid may first be converted to hypochlorite ion before being decomposed within catalysis unit 232 via equation (13).

2HOCI( _aq) + OH- 2H ₂ O + 2CI (a _q) + O _2(g) (14)

[00182] Referring to FIG. 7, an exemplary catalysis unit 700 is shown schematically, which may be operable to perform the function of catalysis unit 232 referred to in FIG. 2. One or more hypochlorite ion sources 702 (such as from hypochlorite ion containing stream 220 or degassed hypochlorite containing stream 230) may be received at an inlet distributor 704, which is configured to distribute hypochlorite ion sources 702 to catalyst bed 706. Hypochlorite ion sources 702 entering catalysis unit will pass over/through the catalyst within catalyst bed 706, whereby hypochlorite ions and hypochlorous acid will be decomposed to oxygen and chloride ions as described above. The mixture may proceed to outlet distributer 708, where a gaseous oxygen containing stream 734 (equivalent to oxygen containing stream 234 in FIG. 2) and liquid processed brine 714 (equivalent to processed brine 214 in FIG. 2) will exit catalysis unit 700.

[00183] Outlet distributer 708 be water/gas separator, similar to water gas separator 226 described above. In some embodiments, outlet distributer 708 may be a mechanical distributer, such as those manufactured by Koch-Glitsch.

[00184] Catalyst bed 706 includes a catalyst suitable to perform the reactions of equations (13) and (14). The catalyst may include a metal, such as cobalt, iron, nickel, magnesium or copper. For example, the catalyst may include or more of a metal oxide such as a cobalt oxide (such as Co ₂ O ₃ or CO3O4), a nickel oxide (such as NiO), a copper oxide (such as CuO), an iron oxide (such as FeO or Fe ₂ O ₃ ) or a titanium oxide (such as TiO ₂ ).

[00185] In some embodiments, the catalyst may be protected cathodically such as by employing an impressed current to the cathode and/or through the use of a sacrificial anode.

[00186] In some embodiments the catalyst may include one or more metal hydroxides such as a nickel hydroxide (such as Ni(OH) ₂ ), an iron hydroxide (such as Fe(OH) ₃ ), a copper hydroxide (such as Cu(OH) ₂ ), a magnesium hydroxide (such as Mg(OH) ₂ ) or a cobalt hydroxide (such as Co(OH) ₂ ). [00187] In some embodiments, the catalyst may include one or more mixed metal oxides such as NiCo2O4.

[00188] In some embodiments, the catalyst may be in form of a metal foam, such as a nickel or cobalt metal foam. A surface oxide or hydroxide coating of the metal foam may act as the active catalyst.

[00189] In some embodiments catalyst bed 706 may include a one or more of the catalysts described above in a powdered form.

[00190] The catalyst may be supported on an inert solid support that includes a stable media. Among the materials suitable as catalyst supports are silica, aluminas, silicates, zeolite, diatomaceous earth, alkaline earth metal and alkali metal silicates. Mixtures of more than one catalyst support may be used. The solid support may be in the form of a powder, metallic pellets or spherical balls.

[00191] In some embodiments, the catalyst may be applied as a surface coating on the catalyst support, such as by precipitation or evaporation.

[00192] Catalyst bed 706 may include a catalyst hold down to maintain the catalyst within position within catalyst bed 706. The catalyst hold down may be any suitable structure such as a metal/polymer perforated plates or screens, alumina or ceramic balls or other types of structures suitable to hold the catalyst in position.

[00193] Catalysis unit 700 may be configured such that hypochlorite ion sources 702 enter at an upper end (through inlet distributer 704) of catalysis unit 700, flowing in a generally horizontal direction and oxygen containing stream 234 and processed brine 214 exit at a lower end through outlet distributer 708. In another embodiment, catalysis unit 700 may be configured such that hypochlorite ion sources 702 enter at a lower end (through inlet distributer 704) of catalysis unit 700, flowing in a generally upwards direction and oxygen containing stream 234 and processed brine 214 exit at an upper end through outlet distributer 708.

[00194] In various embodiments, catalysis unit 700 may operate a temperature of between about 15 °C and about 200 °C. In some embodiments the catalysis unit may operate at a temperature at or above the temperature of electrolysis unit 216. The temperature may be varied as required in order to vary the hypochlorite concentration of processed brine 214.

[00195] Depending upon the temperature of hypochlorite ion solution entering catalysis unit 702 and the material chosen as catalyst and the configuration of the catalyst (in particular the amount of exposed surface area per unit volume of catalyst) the space velocity may be up to 4 hr ^-1 .

[00196] The choice of catalyst used in catalysis unit 700 may be selected based on factors such as the cost of the catalyst in comparison to the cost of heating catalysis unit 700 or the durability of the catalyst.

[00197] In various embodiments, catalysis unit 700 is configured to reduce the hypochlorite ion concentration such that the hypochlorite ion concentration of processed brine 214 is between 0 and about 100 parts per million (ppm). The desired hypochlorite ion concentration of processed brine 214 may be selected based on the end use of processed brine 214 and many be affected by factors such as the choice of catalyst, the operating temperature of catalysis unit 700 and the space velocity through catalysis unit 700.

[00198] According to some embodiments, oxygen containing stream 734 (or oxygen containing stream 234) can contain at least about 80% oxygen based on the total volume of the composition for example, at least about 84% oxygen, at least about 86% oxygen, at least about 88% oxygen, at least about 90% oxygen, at least about 92% oxygen, at least about 94% oxygen, at least about 96% oxygen, at least about 98% oxygen, or about 99% oxygen based on the total volume of the composition. Oxygen containing stream 734 may contain other gases such as chlorine, hydrogen and water vapor. Oxygen containing steam 734 (or oxygen containing stream 234) may be water saturated and the water vapor content may be pressure and temperature dependent.

[00199] Oxygen containing stream 234 may be received by oxygen cleaning unit 236 which is configured to remove contaminants from oxygen containing stream 234 to produce oxygen product 212. Oxygen cleaning unit 236 may be a wash tower constructed and operating in a similar manner to wash tower 600 described above and configured to remove contaminants such as chlorine from oxygen containing stream 234 and produce oxygen product 212. The waste wash fluid exiting oxygen cleaning unit 236 may proceed to catalysis unit 236 or may proceed to a separate catalysis unit, which may be similar to catalysis unit 236.

[00200] In various embodiments, oxygen product 212 may contain less than about 10% by volume of impurities, based on the total volume of the oxygen product 212. In other embodiments, oxygen product 212 may contain less than about 9% by volume, or less than about 8% by volume, or less than about 7% by volume, or less than about 6% by volume, or less than about 5% by volume, or less than about 4% by volume, or less than about 3% by volume, or less than about 2% by volume, or less than about 1% by volume, based on the total volume of oxygen product 212.

Cleaning Solution

[00201] During operation of system 200 described in respect of FIG. 2, buildup of deposits such as scale, organic compounds or other materials may occur. The buildup may occur upon any internal surface within system 200 and may undesirably restrict flow or reduce efficiency of system 200. For example, the buildup of deposits (known as fouling) upon electrodes, is known to reduce operating efficiency and may eventually lead to failure of the electrodes. Similarly, the buildup of deposits upon catalysts is known to reduce catalytic activity by blocking active sites.

[00202] In some embodiments, elements of system 200 may be cleaned and/or depolarized electrically. For example, the electrodes of electrolysis unit 216 may be configured such that the polarity of the electrodes may temporarily be reversed. This may be beneficial as the reversal in polarity may assist in cleaning the electrodes of deposits and/or corrosion. Similarly, other elements of electrolysis unit 216 and catalysis unit 232 may be configured such that a charge may be applied, reversed or removed to some or all components (as well as fluid adjacent to such components) to dislodge and/or dissolve deposits.

[00203] In various embodiments, a cleaning solution may be injected into system 200. The cleaning solution may be a fluid or a blend of fluids that may perform some or all of the beneficial functions as outlined below when introduced into system 200. Firstly, the cleaning solution may act to dislodge and/or dissolve scale and organic deposits on surfaces within system 200. The cleaning solution may also prevent or reduce future deposition of deposits on surfaces within system 200, such as by providing a surface coating (or film) on surfaces within system 200.

[00204] In some embodiments, the cleaning solution may comprise an aqueous phase that may be miscible with water feedstock 202. The cleaning solution may also comprise an organic phase. In some embodiments, the cleaning solution may include an aqueous phase and an organic phase that are emulsified together, such as by addition of a suitable emulsifier.

[00205] The cleaning solution may include a dilute acid such as hydrochloric acid, sulfuric acid, nitric acid, ethanoic acid, citric acid, lactic acid or tartaric acid. The dilute acid may function to dislodge and/or dissolve scale deposits.

[00206] The cleaning solution may also include an organic solvent or a blend of more than one organic solvents that may function to remove organic deposits such as oil and wax within system 200. In some embodiments, the organic solvent may comprise an aromatic solvent, which refers to a solvent comprising at least one aryl group. The term “aryl” as used herein, whether it is used alone or as part of another group refers to cyclic groups that contain at least one aromatic ring. In an embodiment, the aromatic solvent is benzene, toluene, orthoxylene, meta-xylene, para-xylene, ethylbenzene or trimethylbenzene. In other embodiments, the organic solvent comprises an aliphatic solvent or blend of more than one aliphatic solvent such as a straight or branched chain C4-C30 alkane or C4-C40 olefin. In various embodiments, the aliphatic solvent, is butane, pentane, cyclopentane, hexane, cylcohexane, heptane, octane, nonane, decane, undecane or dodecane, or a terpene such as limonene. In other embodiments the aliphatic solvent may be any suitable blend of more than one aliphatic solvents such as gasoline, diesel, petroleum distillate, petroleum ether, mineral spirits, naptha, kerosene or turpentine.

[00207] In other embodiments, the organic solvent comprises a ketone, for example a C3-C12 ketone such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone, or methyl acetate. [00208] In some embodiments cleaning solution may comprise one or more chemical additives such as a corrosion inhibitor, scale inhibitor or defoamer to reduce or prevent corrosion, scale deposition or foaming within system 200. The chemical additives may be similar to those that may be added to wash fluid 608, as previously described.

[00209] In some embodiments, the cleaning solution may include a surfactant to assist with dislodging and/or dissolving deposits within system 200. For example, the surfactant may comprise lauramine oxide and/or D-limonene.

[00210] The cleaning solution may be injected at any suitable location of system 200. The cleaning solution may be injected at locations when deposits are known to occur or at a point of system 200 such that the cleaning solution may reach downstream components of system 200.

[00211] In some embodiments, cleaning solution 224, which may be similar to the cleaning solution described above may be injected into electrolysis unit 216. The cleaning solution may be formulated to dislodge and/or dissolve deposits from the electrodes of the electrochemical cell of electrolysis unit 216.

[00212] In other embodiments, cleaning solution 238, which may be similar to the cleaning solution described above, may be injected into catalysis unit 232. The cleaning solution may be formulated to dislodge and/or dissolve deposits from the catalyst bed of catalysis unit 232.

[00213] In some embodiments, the cleaning of system 200 may be performed in a batch mode. A volume of cleaning solution may be added to an area of system 200 that is isolated (such as by closing control valves) from the rest of the system. For example, the electrochemical cell of electrolysis unit 216 may be isolated and a volume of cleaning solution 224 may be injected into the electrochemical cell to dislodge and/or dissolve deposits within the electrochemical cell. Cleaning solution 224 may be injected in the normal operating flow direction, i.e. , the same flow direction as water feedstock 202 flows during normal operation, in a reverse-flow direction, i.e., the opposite direction to water feedstock 202 during normal operation or in a cross-flow direction, i.e., perpendicular to water feedstock 202 during normal operation. [00214] Similarly, the catalysis unit 232 may be isolated and a volume of cleaning solution 238 may be injected into catalysis unit 232 to dislodge and/or dissolve deposits within the electrochemical cell. Cleaning solution 238 may be injected in the normal operating flow direction, i.e. , the same flow direction as hypochlorite ion sources entering catalysis unit 232 during normal operation, in a reverse-flow direction, i.e., the opposite direction to hypochlorite ion sources entering catalysis unit 232 during normal operation, or in a cross-flow direction, i.e., perpendicular to hypochlorite ion sources during normal operation.

[00215] In some embodiments, the cleaning solution may be added during operation to dislodge and/or dissolve deposits as they are formed during operation. In some embodiments, a constant volume of the cleaning solution may be continuously added to system 200. In another embodiment, the cleaning solution is added to system 200 in larger volumes intermittently as required during operation of system 200.

[00216] Accordingly, the products made in the methods and systems described herein may be suitable for use in a wide variety of applications, such as an energy source in the power and transport industries or as a chemical feedstock. The hydrogen product as produced herein may be of a suitable purity for use or may be further purified by any suitable process. The hydrogen product may be compressed for onsite storage or for transportation such as by tanker truck, rail or pipeline for further use, storage or processing elsewhere. In some embodiments the hydrogen product may be directly used on site for applications such as petroleum refining, in gas lift applications or for the production of ammonia for example.

[00217] The hydrogen product as produced herein may be of a suitable purity for use in fuel cells.

[00218] For applications involving transporting hydrogen made by the methods and systems described herein in a steel pipeline (for example when injecting hydrogen into an existing natural gas system), it may be necessary to leave a small quantity of oxygen in the hydrogen product 208 to protect the existing pipeline from hydrogen embrittlement or lamination.

[00219] In some embodiments, the methods and systems described herein may be employed for water desalination where sea water is used as the water feedstock to produce hydrogen which is used to then make relatively pure water using the hydrogen, along with air or the oxygen product.

[00220] The oxygen product as produced herein may be suitable for use in a wide variety of applications, such as for medical uses, steel production and as a chemical feedstock. The oxygen product may be compressed for onsite storage or for transportation such as by tanker truck, rail or pipeline for further use, storage or processing elsewhere.

[00221] Processed brine 214 may in some embodiments be recycled in electrolysis unit 216. For example, some or all of processed brine 214 produced by catalysis unit 232 may be co-blended with water feedstock 202. In some embodiments, processed brine 214 may be disposed of by any suitable method, such as by injection into a disposal well. Depending on the hypochlorite ion concentration, processed brine 214 may be suitable for use as a biocide or as an electrolyte used in the electrowinning of metals from their ore. In an embodiment, processed brine 214 may be suitable for use an oxidizing agent, such as for use in bleaching wood pulp.

[00222] In other embodiments, any of the intermediate products disclosed herein, such as the hypochlorite containing stream 220, degassed hypochlorite containing stream 230, hydrogen containing stream 218, waste gas stream 228, or oxygen containing stream 234 may be collected and transported to another location for further processing or use, which may include the steps described above or different method steps to produce any of the products described above.

[00223] For example, in some embodiments, hypochlorite containing stream 220 or degassed hypochlorite containing stream 230, rather than entering catalysis unit 232, may be transported such as by tanker truck, rail or pipeline for further use, storage or processing. In some embodiments, hypochlorite containing stream 220 or degassed hypochlorite containing stream 230 may be suitable for use as a biocide, as an electrolyte used in the electrowinning of metals from their ore or an oxidizing agent, such as for use in bleaching wood pulp.

[00224] In various embodiments, system 200, in association with a hydrogen storage facility (such as a cryogenic hydrogen storage tank or a pressurized underground salt dome) may act as a “battery” for an electrical energy production installation, such as a solar or wind installations. The battery may comprise an electrical energy production installation, a system such as system 200 and a storage facility whereby power generated by the electrical energy production installation is used to power system 200 to produce hydrogen, which is stored in the storage facility. The hydrogen may be generated during periods of low electricity demand (i.e., lower economic value). The hydrogen stored in the storage facility may be used to generate electricity such as in a fuel cell, a reciprocating engine or a gas turbine during times of high electricity demand (i.e., higher economic value)

[00225] System 200 may also include one or more heaters configured to maintain a temperature of between about 15 °C and about 100 °C within system 200.

[00226] System 200 may be controlled by a controller (not shown) configured to control some or all of the operations described herein. In particular, the controller may be configured to execute computer code for performing the operations described herein. In this regard, the controller may comprise a processor that may be a microprocessor or a controller for controlling the overall operation thereof. In some embodiments the processor may be particularly configured to execute program code instructions related to the functions described herein. The controller may also include a memory device. The memory device may include non-transitory and tangible memory that may be, for example, volatile and/or non-volatile memory. The memory device may be configured to store information, data, files, applications, instructions or the like. For example, the memory device could be configured to buffer input data for processing by the processor. Additionally or alternatively, the memory device may be configured to store instructions for execution by the processor.

[00227] The controller may also include a user interface that allows a user to interact therewith. For example, the user interface can take a variety of forms, such as a button, keypad, dial, touch screen, audio input interface, visual/image capture input interface, input in the form of sensor data, etc. Still further, the user interface may be configured to output information to the user through a display, speaker, or other output device. A communication interface may provide for transmitting and receiving data through, for example, a wired or wireless network such as a local area network (LAN), a metropolitan area network (MAN), and/or a wide area network (WAN), for example, the Internet. The communication interface may enable the controller to communicate with one or more further computing devices, either directly, or via a network. In this regard, the communication interface may include one or more interface mechanisms for enabling communication with other devices and/or networks. The communication interface may accordingly include one or more interface mechanisms, such as an antenna (or multiple antennas) and supporting hardware and/or software for enabling communications via wireless communication technology (e.g., a cellular technology, communication technology, Wi-Fi and/or other IEEE 802.11 technology, Bluetooth, Zigbee, wireless USB, NFC, RF-ID, WiMAX and/or other IEEE 802.16 technology, and/or other wireless communication technology) and/or a communication modem or other hardware/software for supporting communication via cable, digital subscriber line (DSL), USB, FireWire, Ethernet, one or more optical transmission technologies, and/or other wireline networking methods. Further, the controller may include various modules which may be configured to, in conjunction with the processor, direct operations for generating hydrogen in hydrogen generation unit 204 and/or producing oxygen in oxygen generation unit 206 as described herein.

[00228] The materials of construction of system 200 that are in contact with the process fluids may be corrosion resistant polymers such as fiberglass reinforced plastic, polyvinyl chloride, polyethylene or corrosion resistant metals, such as epoxy coated metal, titanium, Hastelloy or super duplex stainless steel.

[00229] Variations on the forgoing are contemplated. For example, in alterative embodiments only hydrogen generation unit 204 may be used to perform step 104 only. In this embodiment, hypochlorite containing stream 220 may be collected for alternative uses or may be disposed of by any suitable method, such as injection into a disposal well. In this example step 106 would not be performed.

[00230] In some embodiments, hydrogen cleaning unit 222 and oxygen cleaning unit 236 may receive and remove contaminants from respective streams of hydrogen and oxygen generated from other sources instead of or in addition to hydrogen containing stream 218 and oxygen containing stream 234 respectively.

[00231] In some embodiments, oxygen generation unit 206 may simultaneously receive more than one hypochlorite ion containing stream which may feed into a single catalysis unit, similar to catalysis unit 232. [00232] In other embodiments, hydrogen generation unit 204 may include multiple electrochemical cells. Each of the electrochemical cells may have identical configurations or some may have different configurations such that varying water feedstocks may be accommodated. This configuration may also allow for batch cleaning/maintenance of some or all of the electrochemical cells whilst the others are in operation. The multiple hydrogen containing streams may flow into a single hydrogen cleaning unit, such as hydrogen cleaning unit 222, or into multiple hydrogen cleaning units. Similarly, the hypochlorite ion containing streams generated by each of the electrochemical cells may flow into a single water/gas separator or into separate water/gas separators, similar to water/gas separator 226 described above. Where multiple water/gas separators are used, the waste gas streams generated by each of the water/gas separators may flow into a single waste gas cleaning unit, such as waste gas cleaning unit 240, or into multiple waste gas cleaning units.

[00233] In some embodiments, water/gas separators may not be required. For example, this may be the case in applications where the purity requirements for the oxygen product 212 is not high.

[00234] In other embodiments, oxygen generation unit 204 may include multiple catalyst units. Each of the catalysis units may be similar to catalysis unit 232 described above or some may have different configurations such that varying hypochlorite ion streams may be accommodated. This configuration may also allow for batch cleaning of a some or the catalysis units whilst others are in operation. This configuration may also allow for batch cleaning/maintenance of some or all of the catalysis whilst the others are in operation. The multiple oxygen containing streams may flow into a single oxygen cleaning unit, such as oxygen cleaning unit 236, or into multiple oxygen cleaning units.

[00235] Although making and using various embodiments of the present disclosure have been described in detail above, it should be appreciated that the present disclosure provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the invention.