CA2662225A1

CA2662225A1 - Methods and systems for assembling electrolyzer stacks

Info

Publication number: CA2662225A1
Application number: CA002662225A
Authority: CA
Inventors: Dana Ray Swalla
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 2008-06-10
Filing date: 2009-04-09
Publication date: 2009-12-10
Also published as: NO20091421L; DE102009003777A1; US20090301868A1

Abstract

The present techniques provide systems and methods for assembling electrolyzers (66) from parts which have internal structures that form fluid flow channels (34, 35, 60, 64) when placed adjacent to one another. In a contemplated embodiment, the assembly technique may use alignment bars (98, 100), inserted through openings in the individual parts to hold the parts in alignment, while other structures apply pressure to hold the structure together. In another contemplated embodiment, the parts may be aligned by having ridges, or other protrusions (102), formed on the parts that mate with openings on adjacent parts. The applied pressure seals fluid flow channels (34, 35, 60, 64) formed in the electrolyzer (66) and extending through the joined parts. The use of pressure to hold the structure together allows for the servicing and replacement of individual parts.

Description

METHODS AND SYSTEMS FOR ASSEMBLING
ELECTROLYZER STACKS
BACKGROUND

This invention generally relates to methods of assembling electrolyzer stacks, and in particular to a method of sealing electrolyzer cells together to form fluid channels in electrolyzer stacks.

Electrochemical devices are useful in chemical reactions in which electrons may participate as reactants or products. For example, an electrolytic cell may use electrical energy to split lower energy reactants into higher energy products, which may then be used as materials, reactants, or in power generation. In another example, voltaic cells and fuel cells may be used to chemically combine higher energy products to form lower energy products, releasing electrons that may be used to power other devices. While in voltaic cells, the electrode may be consumed during the reaction, in a number of other electrochemical devices, such as electrolytic cells and fuel cells, the electrode is not intended to be a reactant, but merely to catalyze the reaction and collect or donate the current from the reaction.

Electrolytic cells may be useful in a number of processes, such as the splitting of water into oxygen and hydrogen in an electrolyzer. The hydrogen generated may be used in chemical processes, such as hydroformulation or hydrocracking in refineries, or may be stored for later use, such as in the generation of energy in a fuel cell. Electrolyzers may be assembled from a stack of individual plastic components that are joined together to form a contiguous structure, generally by adhesives or welding.

However, permanently joining the components may be disadvantageous for a number of reasons. For example, the failure of an individual part in an electrolyzer stack my require replacement of the entire electrolyzer stack, particularly if individual modules, sections or parts cannot be serviced or replaced. Accordingly, it would be desirable to have techniques for assembling electrolyzer stacks to form a hermetic seal between the individual parts in ways that permit disassembly, servicing, and replacement.

BRIEF DESCRIPTION OF THE INVENTION

An embodiment of the present techniques provides an electrolyzer that includes a plurality of electrolyzer cells placed adjacent to one another to form a stack. Each electrolyzer cell includes an electrode assembly and a diaphragm assembly, and the diaphragm assembly of each electrolyzer cell is placed adjacent to an electrode assembly of another electrolyzer cell. An internal fluid channel through the stack is formed by an internal structure of each of the electrolyzer cell, and a mounting configured to maintain a compressive force on the stack seals the internal fluid channel.

Another embodiment provides a method of assembling an electrolyzer that includes assembling a plurality of cells in an aligned stack. Each cell includes a metal plate and a diaphragm, and has apertures, that when aligned with an adjacent cell, form a fluid channel. The fluid channel is sealed by maintaining a compressive force on the stack.

Another embodiment provides a method of assembling an electrolyzer, which includes assembling a plurality of electrolyzer cells. Each electrolyzer cell includes a metal plate and a diaphragm, and has a structure configured to form a fluid channel when aligned with other electrolyzer cells. The electrolyzer cells are aligned to form an electrolyzer stack having a first end, a second end, and an internal fluid channel. A body is placed around the electrolyzer stack and an end cap is placed over an end of the body. The end cap has an aperture aligned with the channel in the electrolyzer stack. A base plate over another end of the body to create a compressive force to seal the internal channel in the electrolyzer stack securing the end cap and the base plate to the body.

DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawing.

FIG. 1 is a diagrammatic representation of an electrolyzer system according to embodiments of the present techniques;

FIG. 2 is a perspective view of an exemplary assembled electrolyzer;

FIG. 3 is an exploded view of the electrolyzer of FIG. 2, showing the individual parts of the assembly;

FIG. 4 is a perspective view of an exemplary electrolytic cell that may be used in the electrolyzer of FIG. 3;

FIG. 5 is an exploded view of the electrolyzer of FIG. 2, showing the use of a protruding lip on the end cap that may be used to place pressure on the electrolyzer stack;

FIG. 6 is a magnified view of the protruding lip of FIG. 5; and FIG. 7 is diagram illustrating exemplary steps in a method for assembling an electrolyzer in accordance with embodiments of the present techniques.

DETAILED DESCRIPTION

As discussed in detail below, the present techniques provide systems and methods for assembling electrolyzers from parts which have internal structures that form fluid flow channels when placed adjacent to one another. In a contemplated embodiment, the assembly technique may use alignment bars, inserted through openings in the individual parts to hold the parts in alignment, while other structures apply pressure to hold the structure together. In another contemplated embodiment, the parts may be aligned by having ridges, or other protrusions, formed on the parts that mate with openings on adjacent parts. The applied pressure seals fluid flow channels formed in the electrolyzer and extending through the joined parts.
The use of pressure to hold the structure together allows for the servicing and replacement of individual parts.

An example of an electrolyzer system 10 that may be assembled by the present techniques is illustrated by the schematic diagram of FIG. 1. In the electrolyzer system 10, water 12 is split into hydrogen 14 and oxygen 16 by an electrolyzer stack 18. In operation, a pump 20 maintains a continuous flow of an electrolyte solution 22 through the electrolyzer stack 18. Generally, the electrolyte solution 22 is an aqueous solution of about 20 wt % to about 40 wt. %, or about 30 wt %, potassium hydroxide (KOH) or sodium hydroxide (NaOH), although any number of other ionic solutions may be used. For example, the electrolyte solution 22 may contain lithium hydroxide or other metals.

As a portion of the water 12 is converted to hydrogen 14 and oxygen 16, additional water 12 is added prior to returning the electrolyte solution 22 to the electrolyzer stack 18. As discussed in further detail below, the electrolyzer stack 18 produces a hydrogen stream 24 containing bubbles of hydrogen 14 in the electrolyte solution 22. The hydrogen stream 24 is directed to a hydrogen separator 26, where the hydrogen 14 separates out and is collected for storage or use. The electrolyzer stack 18 also produces a separate oxygen stream 28 containing bubbles of oxygen 16 in the electrolyte solution 22, which is directed to an oxygen separator 30.
In the oxygen separator 30, the oxygen 16 is separated from the electrolyte solution 22. The hydrogen separator 26 and oxygen separator 30 may generally function as reservoirs for the electrolyte solution 22. From the separators 26, 30 a return electrolyte solution 32 may be directed to the pump 20, where it is circulated to the electrolyzer stack 18.

In the electrolyzer stack 18, two inlet channels 34, 35 direct the electrolyte solution 22 to a number of individual electrolyzer cells 36. The inlet channels 34, 35 are formed by adjacently aligned apertures formed in each of the electrolyzer cells 36.
The electrolyzer cells 36 are stacked and electrically connected in series by the electrolyte solution 22. Generally, the electrolyzer cells 36 are joined, for example, by welding, to form a single structure, in which the inlet channels 34, 35 form one of two sets of flow paths through the structure. However, embodiments of the present techniques allow for assembling an electrolyzer stack 18 without forming a permanent bond between the electrolyzer cells 36, by placing the electrolyzer stack 18 under pressure during assembly and use. This holds the electrolyzer cells 36 together with sufficient pressure to form a hermetic seal between the individual electrolyzer cells 36. Further, these techniques may allow the electrolyzer stack 18 to be serviced by the replacement of or access to individual cells 36.

In the illustrated embodiment, the electrolyzer stack 18 contains 10 electrolyzer cells 36, although any number may be included, such as 50, 75, 100, or more electrolyzer cells 36 depending on the current available and the production rates desired. At one end of the electrolyzer stack 18, a positive source 38 is connected to a positive current collector 40. At the other end of the stack, a negative source 42 is connected to a negative current collector 44. A metal plate 46 disposed within each of the electrolyzer cells 36 functions as a bipolar electrode. As current is passed through the electrolyte solution 22, a positive charge is induced on the side of the metal plate 46 closest to the positive electrode 38, forming an anodic surface 48.
Similarly, a negative charge is induced on the side of the metal plate 46 closest to the negative electrode, fonning a cathodic surface 50. The metal plate 46 may have a wire mesh welded to the surfaces 48, 50 to increase the surface area.

Generally, during electrolysis, the difference in charge between the anodic surface 48 and cathodic surface 50 may be on the order of about 1.5 volts to about 2.2 volts. Accordingly, as the electrolyzer cells 36 are in series, the voltage supplied to the electrolyzer stack 18 will be increased to accommodate the number of electrolyzer cells 36 in the stack. For example, the voltage supplied to the electrolyzer stack 18 may range from about 15 to about 22 volts, for embodiments with 10 electrolyzer cells 36 and range from about 150 volts to about 220 volts, for embodiments with 100 electrolyzer cells 36. Other voltages, and indeed, other charge application schemes may also be envisaged.

During operation of the electrolyzer stack 18, the electrolyzer solution 22 is passed over the anodic surface 48 of the metal plate 46 through a channel 52 formed in each of the electrolyzer cells 36 and connected to inlet channel 34. A
second channel 54 directs electrolyte solution 22 from inlet channel 35 over the cathodic surface 50 of the metal plate 46. The water 12 in the electrolyte solution 22 is split into oxygen 16 at the anodic surface 48 and hydrogen 14 at the cathodic surface 50.

The bubbles of hydrogen 14 and oxygen 16 are isolated from each other by a liquid permeable membrane 56, which allows water and ions from the electrolyte solution 22 to flow conducting current, between the anodic surface 48 and the cathodic surface 50, but generally prevents the transfer of gas. The liquid permeable membrane may be made from any number of hydrophilic polymers, including, for example, polysulfones, polyacrylamides, and polyacrylic acids, among others.

The oxygen stream 28 formed at the anodic surface 48 in each of the electrolyzer cells 36 is directed through an oxygen channel 58 to an oxygen outlet channel 60. From the oxygen outlet channel 60, the oxygen stream 28 is directed to the oxygen separator 30. Similarly, the hydrogen stream 24 formed at the cathodic surface 50 of each of the electrolyzer cells 36 is directed through a hydrogen channel 62 to a hydrogen outlet channel 64. From the hydrogen outlet channel 64, the hydrogen stream 24 is directed to the hydrogen separator 26. As for the inlet channels 34, 35, the electrolyzer cells 36 have adjacently aligned apertures that form the outlet channels 60, 64 when electrolyzer cells 36 are joined together to form the final structure. Accordingly, it is desirable that the electrolyzer cells 36 be hermetically sealed to each other to prevent mixing of the hydrogen 14 and oxygen 16 between the outlet channels 60, 64, or other parts of the electrolyzer stack 18.

The electrolyzer stack 18 is generally mounted in an enclosure as illustrated in FIG. 2, forming an electrolyzer 66. The electrolyzer 66 has connections for the inlet channels 34, 35 to allow the flow of electrolyte solution 22 into the electrolyzer 66. The electrolyzer 66 also has connections for the oxygen outlet channel 60 to allow the oxygen stream 28 to be removed, and the hydrogen outlet channel 64 to allow the hydrogen stream 24 to be removed. In the illustrated embodiment, the structure forms a pressure vessel, and the connections are flanged connections for interfacing with mating piping. Other physical configurations may, of course, be envisaged. Generally, in a presently contemplated embodiment, the thickness 68 of the electrolyzer 66 may be about 150 cm, but the actual size and dimensions will vary depending upon the number of electrolyzer cells used. The details of the electrolyzer 66 may be seen more clearly in FIG. 3.

FIG. 3 illustrates an exploded view 70 showing the individually components of the electrolyzer 66. As shown in this view, the electrolyzer has an end cap 72, which has connections to the inlet channels 34, 35 and outlet channels 60, 64.
The body 74 of the electrolyzer has a number of connectors 76 mounted along the periphery to allow pressure to be applied during operation. The pressure applied is outside of the electrolyzer stack 18 (within the body 74) to reduce hoop stress on the electrolyzer stack 18 by generally equalizing or reducing the pressure differential between the interior and exterior regions of the stack.

The electrolyzer stack 18 is assembled by stacking the electrolyzer cells 36 together to form a single unit, with the apertures in each of the electrolyzer cells 36 aligned to form the inlet channels 34, 35 and outlet channels 60, 64. The alignment of the electrolyzer cells 36 may be performed by inserting an alignment bar 78 through the parts, for example, through the hydrogen outlet channel 64, as shown.
Other alignment bars (not shown) may be inserted through the other channels 34, 35, and 60 to further improve the alignment. Further, the electrolyzer cells 36 may be aligned by mating protrusions (not shown) in the surface of the electrolyzer cell 36 with corresponding indentations on adjoining electrolyzer cells 36.

A base plate 80 is mounted against the body 74 opposite the end cap 72. The base plate 80 may have depressions 81 into which the alignment bar 78 may be inserted, aligning the base plate 80 with the rest of the electrolyzer 66. The end cap 72, base plate 80, and body 74 may be constructed from any suitable materials, such as stainless steel, hastalloy, nickel, and so forth. Further, the parts do not have to be made from metal, as a high performance plastic may provide sufficient properties.
Suitable high performance plastics may include, for example, polyphenylene sulfide (PPS) or poly(ether-ether-ketone) (PEEK), among others. Moreover the parts may be made of the same material or may be of different materials. For example, the end cap 72 and the base plate 80 may be made from stainless steel, while the body 74 may be made from a high-performance plastic, thereby insulating the end cap 72 from the base plate 80. The end cap 72 may also be insulated from the base plate 80 by the use of gaskets (not shown) between end cap 72, the body 74, and the base plate 80.

To place the electrolyzer cells 36 under pressure, one or more spacer plates 82 may be inserted insulate the electrolyzer stack 18 from the end cap 72.
Further, a gasket 84 may be inserted to add additional pressure, and/or to insulate the stack from the base plate 80. The pressure applied to the electrolyzer stack 18 may be controlled by the number and thickness of the spacer plates 82. For example, two spacer plates 82 may provide a pressure of about 6.89 bar (100 psi). Other pressures that may be used in embodiments depend on the materials used, as discussed further below.
Other ways of imposing pressure on the electrolyzer stack 18 may be used, including an end cap 72 with a protruding lip, as discussed with respect to FIG. 5 below.

The entire assembly may be held together by bolts 86 inserted through the end cap 72 and base plate 80, which are threaded into nuts 88 after insertion through the base plate 80. The bolts 86 will apply the pressure used to seal the electrolyzer cells 36 against each other, forming the inlet channels 34, 35 and outlet channels 60, 64. A power terminal 90 may be welded onto the end cap 72 which may then function as one of the current collectors 40, 44. Another power terminal 92 welded onto the base plate 80 may allow the base plate 80 to function as the oppositely charged current collector.

It should be noted that additional elements may also be placed between the cells to aid in assembly and/or sealing. For example, the cells may be mated through the intermediary of a seal or seal assembly (not shown) that may be placed between adjacent cells or cell elements (i.e., adjacent electrode and diaphragm assemblies).
Such seals may be disposed on a surface of one or both of the adjacent elements, or may be recessed in grooves or other structures formed or machined into the elements.

An individual electrolyzer cell 36 that may be used in the electrolyzer stack 18 is shown in the perspective view of FIG. 4. The electrolyzer cell 36 generally includes two parts, an electrode assembly 94 mounted to a diaphragm assembly 96.
Both assemblies 94, 96 have apertures which align with one another, and with other electrolyzer cells to form the inlet channels 34, 35 and the outlet channels 60, 64. The electrode assembly 94 holds the metal plate 46 that forms the bipolar electrode. One side of the electrode assembly 94 has the channel 54 molded in to direct flow of the electrolyte from one of the inlet channels 35 across the cathodic surface 50 of the metal plate 46. The flow with entrained hydrogen bubbles is then directed to the hydrogen outlet channel 64 via hydrogen channel 62, which may also be molded into the electrode assembly 94. An analogous set of channels on the opposite side of the metal plate 46 directs the flow of oxygen 16.

The electrode assembly 94 and the diaphragm assembly 96 may be made from any number of materials, and in a presently contemplated embodiment, include a peripheral frame made of a non-conductive, chemically resistant plastic. The plastic material may generally be chemically resistant to an oxidative environment, a reducing environment, an acidic environment, a basic environment, or any combination thereof. For example, the frames of the assemblies 94, 96, may be made from polyimides, polyamides, polyetheretherketones, polyethylenes, fluorinated polymers, polypropylenes, polysulfones, polyphenylene oxides, polyphenylene sulfides, polyphenvlethers, polystyrenes, polyether imides, epoxies, polycarbonates, impact-modified polyethylene, impact-modified fluorinated polymers, impact-modified polypropylenes, impact-modified polysulfones, impact-modified polyphenylene oxides, impact-modified polyphenylethers, impact-modified polyphenylene sulfides, impact-modified polystyrene, impact-modified polyetherimide, impact-modified epoxies, impact-modified polycarbonates, or any combinations thereof. Other polymers that may be used include high performance blends, such as Noryl, which is a blend of polyphenylether and polystyrene (PS) (available from SABIC Innovative Plastics of Pittsfield, MA).

The materials selected for the electrode assembly 94 and diaphragm assembly 96 will determine the pressure that needs to be applied to the electrolyzer stack 18 to form a hermetic seal between each electrolyzer cell 36.
Specifically, the compliance, or modulus, of the plastic will determine what applied pressure will result in formation of a seal. If the pressure is too low relative to the compliance, the plastic may not adequately seal, allowing the hydrogen 14 and oxygen 16 to mix through leaks between the outlet channels 60, 64. If the pressure is too high, the plastic may crack, also allowing leaks to form. In presently contemplated embodiments, the pressure applied to the electrolyzer stack 18 may be about 2 bar, 3 bar, 5 bar, 7 bar, 9 bar, or higher.

The diaphragm assembly 96 may be permanently joined to the electrode assembly 94 to form the electrolyzer cell 36. The two assemblies 94, 96 may be joined by any number of techniques including adhesives, ultrasonic welding, thermal welding, compression, and so forth. The diaphragm assembly 96 holds the liquid permeable membrane 56, which prevents mixing of oxygen 16 formed on the anodic surface 48 of the metal plate 56 with hydrogen 14 formed on the cathodic surface 50 of an adjoining metal plate. In other contemplated embodiments, the electrode assembly 94 and diaphragm assembly 96 may be left as separate units, and held together by pressure in the final assembled electrolyzer 66.

The electrolyzer cell 36 may be slid onto alignment bars 98, 100 inserted through the channels 34 and 35 to align the electrolyzer cell 36 with adjoining electrolyzer cells 36, forming the electrolyzer stack 18. Other alignment bars (not shown) may be inserted through channels 60 and 64. The alignment bars may generally be cylindrical, but any shape that makes sufficient contact with the sides of the channels 34, 35, 60, and 64 may be used. The alignment bars may be plastic rods or cylinders and may also include plastic tubing and pipe. As previously mentioned, other techniques may be used to align the electrolyzer cells 36. Protrusions (not shown) may be molded or machined into the electrode assembly 94 or the diaphragm assembly 96, and designed to interface with matching holes or surface depressions in adjoining parts. The use of mating protrusions may be used in addition to or in place of the alignment bars.

In addition to the use of spacer plates 82, described above, another presently contemplated technique that may be used to apply pressure to the electrolyzer stack 18 is shown in the top view of the electrolyzer 66 in FIG. 5. In this configuration, the end cap 72 has a protruding lip 102 machined into the lower surface. The protruding lip 102 has an o-ring 104 set into a channel machined into the protruding lip 104. The procedure is generally the same as described for FIG. 3, with an alignment bar placed through at least one of the channels 64 formed by the aligned apertures in the electrolyzer cells 36. The spacer plates 82 and gasket 84 may be used to further increase the pressure on the electrolyzer stack 18. The protruding lip 102 is designed the closely fit within the body 74 of the electrolyzer 66, with the o-ring 104 forming a seal.

A closer view of the protruding lip 102 may be seen in the magnified view of FIG. 6, taken along cut line 6-6 in FIG. 5. In FIG. 6, it can be seen that the protruding lip 102 may be only slightly within the inside edge 106 of the body 74. This tight fit may enable the o-ring 104 to securely engage the inside edge 106 of the body forming the seal. As the nuts 88 are tightened onto the bolts 86, the protruding lip 102 may function as a piston, applying pressure to the electrolyzer stack 18, and sealing the channels 34, 35, 60, and 64.

A method 108 for assembling an electrolyzer 66 is illustrated in the flow chart in FIG. 7. The method 108 begins with the formation of the sub-assemblies (block 110). The sub-assemblies include the electrolyzer cells 36 which are made by joining an electrode assembly 94 to a diaphragm assembly 96, as described above.
Once the sub-assemblies are made, they are placed onto an alignment bar 78 (block 112), to form an electrolyzer stack 18. Any other parts desired are then placed onto the alignment bars, such as the spacer plates 82 and gasket 84. In other contemplated embodiments, protrusions on each of the electrolyzer cells 36 may be matched to indentations on adjoining electrolyzer cells 36 to align the fluid channels 34, 35, 60, 64. In this contemplated embodiment, matching protrusions and indentations may also be formed into the spacer plates 82, gasket 84. In this embodiment, matching indentations or protrusions may also be machined into the end cap 72 and the base plate 74.

The aligned electrolyzer stack 18 is then assembled into the body 74 (block 114). The alignment bars are placed through the end cap 72 to align the channels 34, 35, 60, and 64 with the end cap72. The opposite end of the alignment bars may be placed into depressions in the base plate 80 to align the base plate 80 with the rest of the parts. After all parts are assembled, the bolts 86 are placed through the end cap 72 and base plate 80, and the nuts 88 are ed onto the bolts 86 (block 116).

Once the bolts 86 are attached to the nuts 88, they are tightened to apply pressure to the electrolyzer stack 18 (block 118). The pressure seals the electrolyzer cells 36 to each other, forming the inlet channels 34, 35 and outlet channels 60, 64.
Once the assembly is complete, the alignment bars are removed by pulling them from the channels 34, 35, 60, and 64 in the end cap 72 (block 120), leaving a fully assembled electrolyzer unit.

While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

Claims

1. An electrolyzer (66), comprising:
a plurality of electrolyzer cells (36) placed adjacent to one another to form a stack (18), wherein each electrolyzer cell (36) comprises an electrode assembly (94) and a diaphram assembly (96), and wherein the diaphragm assembly (96) of each electrolyzer cell (36) is placed adjacent to an electrode assembly (94) of another electrolyzer cell (36);
an internal fluid channel (34, 35, 60, 64) through the stack (18) formed by an internal structure of each of the electrolyzer cells (36);
a mounting configured to maintain a compressive force on the stack (18) sufficient to seal the internal fluid channel (34, 35, 60, 64).

2. The electrolyzer (66) of claim 1, wherein the compressive force creates a pressure between cells (36) of between about 3 bar and a pressure less than the maximum allowable compressive load of the cell material.

3. The electrolyzer (66) of claim 1, wherein the mounting is configured to be opened to permit access to any one of the plurality of electrolyzer cells (36).

4. T'he electrolyzer (66) of claim 1, wherein either the electrode assembly (94), the diaphragm assembly (96), or both, comprises a plastic material that is chemically resistant to an oxidative environment, a reducing environment, an acidic environment, a basic environment, or any combination thereof.

5. The electrolyzer (66) of claim 1, wherein the mounting comprises a body (74) around the stack (18), an end cap (72) comprising a manifold configured to be in fluid contact with the internal fluid channel (34, 35, 60, 64), and a base plate (80), wherein the end cap (72) and the base plate (80) are configured to maintain the compressive force.

6. The electrolyzer (66) of claim 5, wherein the end cap (72) comprises a lip (102) configured to extend into the body (74) and maintain the compressive force.

7. The electrolyzer (66) of claim 6, comprising a spacer (82) between the stack (18) and the end cap (72), wherein the spacer (82) maintains the compressive force.

8. The electrolyzer (66) of claim 1, wherein the electrode assembly (94) and the diaphragm assembly (96) of each electrolyzer cell (36) form a single unit.

9. The electrolyzer (66) of claim 1, wherein the electrode assembly (94) and the diaphragm assembly (96) of each electrolyzer cell (36) are held together by the compressive force.

10. The electrolyzer (66) of claim 1, comprising an inlet channel (34, 35) for introducing an electrolyte solution into the electrolyzer (66), a hydrogen outlet channel (64), an oxygen outlet channel (60), or any combination thereof.