The invention is related to an electrolyser and a method for performing electrolysis using the electrolyser. The invention may be of particular benefit for the large scale production of hydrogen.

Hydrogen energy technology is a field of energy technology that forms a part of energy transition plans in many countries due to the possibility of creating, storing, transporting, and burning hydrogen in a sustainable fashion. In particular, green hydrogen - produced from electricity from renewable sources - fulfils criteria of sustainability with net-zero emissions. To be economically and practically viable hydrogen typically has to be produced on a large scale level, e.g. corresponding to individual electrolysers having an electrical capacity of Megawatts per year, even tens or hundreds of Megawatts.

Large scale production of green hydrogen presents challenges for known electrolysers such as challenges relating to scalability of known electrolysers, e.g. in view of production of the electrolysers. Many presently proposed electrolysers are technically complex, both in terms of their production and their internal structure. For example, many high efficiency electrolysers rely on very narrow flow channels for the electrolyte. Therefore, in view of the need for GW/year production levels, scaling up is complex and intricate high efficiency electrolyser appear not attractive.

Another challenge relates to the water needed in large scale hydrogen production. To produce enormous amounts of hydrogen a large amount of water is needed. However, known electrolysers require a very high degree of purity of the water to prevent the electrolyser from malfunctioning, e.g. due to contaminants in the water reacting with electrodes of the electrolyser. Creating sufficiently pure water, with few contaminants, may constraint the scaling up of such electrolysers.

It is an object of the invention to provide an electrolyser design that allows for (very) large scale electrolysis, e.g. above 1 MW electrical power rating, preferably even more than 10 MW. It is a further object of the invention to provide an electrolyser having an improved design, e.g. in view of mass production and/or maintenance and/or reliability.

The object of the invention is achieved by an electrolyser according to claim 1 .

The electrolyser comprises a multitude, for example at least 20, electrode assemblies and a multitude of electrolyte feed tubes in each array. For example, the electrolyser comprises at least 100 electrode assemblies and associated electrolyte feed tubes within the vessel, e.g. at least 1000 electrode assemblies and associated electrolyte feed tubes within the vessel. The electrolyser comprises a vessel and at least three horizontal manifold plates which are vertically spaced from one another within the vessel. For example, the manifold plates divide the vessel into compartments, each compartment containing an array of a multitude of electrode assemblies and of a multitude of electrolyte feed tube members, each array being confined between two of the manifold plates.

The electrolyser has at least two arrays of a multitude of electrode assemblies and of a multitude of electrolyte feed tube members, each array being confined between two of the manifold plates. In practical embodiments, a vessel may have at least 10 arrays above one another, possibly more than 100 arrays above one another.

Each electrode assembly comprises:

- a vertically arranged elongated core body having a vertical main axis and having at least three electrode support portions distributed about the main axis of the core body,

- an electrode structure that extends about the core body.

The electrode structure has at least three straight sections, each straight section between adjacent electrode support portions. The straight sections of the electrode structure define at least three vertically extending planar electrode faces of an outer contour of the electrode assembly seen in horizontal cross-section. In practical embodiments, the core body has between three and eight electrode support portions distributed about the main axis of the core body. In a practical embodiment, the core body has three electrode support portions. In another practical embodiment, the core body has four electrode support portions. In a practical embodiment, the number of straight section is equal to the number of electrode support portions. In another practical embodiment, the number of straight sections is fewer than the number of electrode support portions, e.g. some adjacent electrode support portions do not have a straight section therebetween. In another practical embodiment, the number of straight sections is greater than the number electrode support portions, e.g. some adjacent electrode support portions have multiple straight sections therebetween.

Within each electrode assembly, at least one vertically extending electrode assembly flow channel is delimited which extends along the inner side of each planar electrode face. For example, the electrode assembly flow channel extends between two adjacent electrode support portions of the core body.

Preferably, all electrode assemblies of the electrolyser are identical. This facilitates production. In other embodiments, each array is composed of two versions of the electrode assembly having different outer contours, e.g. octagonal electrode assemblies and square electrode assemblies combined into an array.

The core body may be manufactured from a non-conducting material, e.g. a plastic, such that the core body does not conduct electrical current when the electrolyser is in operation. For example, the core body is a monolithic component, e.g. of plastic material. For example, the core body is molded or extruded, e.g. from plastic material. For example, the core body has a solid cross-section, so devoid of internal spaces, channels, etc.

For example, the core body is manufactured first and the electrode structure is applied at a later manufacturing step. In another example, the core body is molded onto the electrode structure, e.g. the electrode structure being placed in a mold, ahead of introduction (injection) of the plastic material that forms the core body and at the same time fixes the electrode structure to the core body.

For example, each electrode body is between 80mm and 120mm in height.

The array of electrode assemblies is such that that planar electrode faces of adjacent electrode assemblies are parallel to and spaced from one another by an inter-electrode gap thereby forming an electrolyte flow channel between.

Most preferably, the electrolyser is devoid of a membrane in the inter-electrode gaps. So, most preferably, the electrolyser is a membraneless electrolyser.

The vertically extending planar electrode faces comprise flow openings, e.g. gaps between windings of the coil or openings in a mesh type electrode, such that a fluid connection between the electrode assembly flow channel(s) of the assembly and the electrolyte flow channel(s) adjacent the assembly is formed. The fluid connection allows electrolyte to flow from the electrolyte flow channel to the electrode assembly flow channels of the adjacent electrode assemblies.

At each junction of electrolyte flow channels in the array, an electrolyte feed tube member is present. This electrolyte feed tube member comprises a vertically arranged elongated tube body having an electrolyte inlet at at least one of the lower end and upper end thereof, and having multiple outlet orifices distributed over the height of the tube body, which outlet orifices are preferably aligned with the electrolyte flow channels, e.g. arranged in vertical rows.

One or more of the manifold plates, preferably all, are provided with an electrolyte feed flow channel arrangement connected to the electrolyte inlets of the electrolyte feed tube members in the array provided above and/or below the manifold plate allowing to feed, in operation of the electrolyser, electrolyte into the inlets of the electrolyte feed tube members, which electrolyte then flows via the outlet orifices into the electrolyte flow channels.

One or more of the manifold plates, preferably all, are provided with an electrical wiring connected to the electrode structures of electrolyser assemblies in the array provided above and/or below the manifold plate so as to create an alternating arrangement of anodic electrode assemblies and cathodic electrode assemblies in the array, the electric wiring allowing to establish, in operation of the electrolyser, an electrolyzing current between adjacent electrode assemblies in an array allowing to form electrolysis products in the electrolyte by electrolyzing the electrolyte.

One or more of the manifold plates, preferably all, are provided with an electrolysis products discharge flow channel arrangement for extracting electrolysis products from the electrode assemblies in the array below the manifold plate, wherein the electrolysis products discharge flow channel arrangement comprises, for each electrode assemblies in the array below the manifold plate, at least one port in communication with the at least one vertically extending electrode assembly flow channel of the electrode assembly.

In practical embodiments, a manifold plate has a two separated electrolysis products discharge flow channel arrangements, e.g. one generally above the other, wherein a first flow channel arrangement is associated with the anodic electrode assemblies, and wherein a second flow channel arrangement is associated with the cathodic electrode assemblies.

In practical embodiments, the electrolyte is/contains water, wherein a first electrolysis products discharge flow channel arrangement associated with the anodic electrode assemblies discharges electrolysis products containing oxygen gas, and a second electrolysis products discharge flow channel arrangement associated with the cathodic electrode assemblies discharges electrolysis products containing hydrogen gas.

In practical embodiments, the electrolyser is configured such that the electrolyte passes through only one array before being discharged from the electrolyser.

In practical embodiments, the gases are removed from the electrolysis product flows and the remaining electrolyte, e.g. water, is fed back into the electrolyser. For example, the gases are stored, e.g. for later use as a fuel or for another purpose.

The electrolyser allows large amounts of electrolyte, e.g. water, to pass through the electrolyser and allows electrolysis to be performed on the electrolyte. Possibly, efficiency may lag behind more intricate designs, yet the scalability of the inventive design offsets that drawback, at least in economic terms. Because of the repeating pattern formed by alternating anodes and cathodes in the array, a large volume of electrolyte may pass through the electrolyser at any given time.

In a practical embodiments, all manifold plates in the vessel are identical.

In a practical embodiment, all manifold plates have a body that is made of plastic or another non- conductive material. In a practical embodiment, the body of a manifold plate is made (in part) by a 3D-printing technique, which allows to create the flow channel arrangements with ease as well as paths for the electric wiring.

In an embodiment, the manifold comprises a stack of one or more sheets of plastic material having ports therein, and one or more sheets having the flow channel arrangements therein that adjoin the ports.

The electric wiring of a manifold plate may be composed of electrically conductive cables and/or strips, but may also be created by 3D-printing, e.g. ahead of or simultaneous with the printing of the manifold plates.

In an embodiment, the electrode structure of an electrode assembly is an electrically conductive mesh, e.g. of a metal, e.g. of stainless steel wire or nickel wire or metal alloy. For example, the mesh is a woven mesh or an expanded mesh.

In an embodiment, the electrode structure of an electrode assembly is a perforated electrically conductive plate, e.g. of stainless steel or nickel or another metal or metal alloy.

In view of effective large scale production of the electrode assemblies needed to create a large capacity electrolyser, in an embodiment, the electrode structure of electrode assembly is embodied as a helical coil of electrically conductive wire that extends about the core body in multiple windings, the wire being supported by the electrode support portions so that the windings are vertically spaced from one another, forming the flow openings. Herein each winding of the wire has at least three straight wire sections, each straight wire section between adjacent electrode support portions. The straight wire sections of the windings define the at least three vertically extending planar electrode faces of an outer contour of the electrode assembly seen in horizontal cross-section. For example, the wire is made of stainless steel wire or nickel wire or metal alloy wire.

Preferably, each electrode support portion delimits a vertically extending coil support face, wherein the helical coil of electrically conductive wire is wrapped around the core body in multiple windings, the wire being supported by the coil support faces so that the windings are vertically spaced from one another. Wrapping can be carried out highly effectively. As indicated already, an alternative production technique would be to arrange the coil in a mould, and then inject plastic material to form the core body and at the same time secure the coil to the core body. The coil support face can comprise notches to receive therein the windings, but other designs are also possible.

A voltage may be applied to the coil, such that a current may flow between electrode assemblies and the electrode assembly is an anode or a cathode depending on the direction of the electrical current. In practical embodiments, one or more, preferably all, of manifold plates are configured to comprise or comprise:

- the electrolyte feed arrangement connected to the electrolyte inlets of the electrolyte feed tube members in the array above the manifold plate,

- the electrical wiring connected to the electrode structures of electrode assemblies in the array above and/or below the manifold plate,

- an electrolysis products discharge flow channel arrangement for extracting electrolysis products from the electrode assemblies in the array below the manifold plate, e.g. with first and second electrolysis products discharge flow channel arrangements to discharge the created hydrogen and oxygen separated from one another.

In practical embodiments, the core body has between three and eight electrode support portions distributed about the main axis of the core body, e.g. three, or four.

Generally, it is preferred to embody the electrode assemblies with an outer contour that allows for a dense packing of the assemblies in an array, yet with interstices remaining between the densely packed assemblies, e.g. at junctions in the array, so that the electrolyte feed tube members can be arranged at these interstices so that they communicate with the flow channels between neighbouring electrode assemblies.

In practical embodiments, the core body has a core portion from which vertically arranged ribs extend to define the at least three support portions distributed about the main axis of the core body, e.g. each rib delimiting a vertically extending support face of the core body, wherein between each pair of adjacent ribs a vertically extending electrode assembly flow channel is delimited which extends along the inner side of each planar electrode face. Preferably, the core portion has at least the height of the ribs or the same height as the ribs.

For example, a horizontal cross section of the core body has a Y-shape, having three vertically arranged ribs, or horizontal cross section of the core body has an X-shape having four vertically arranged ribs.

Preferably, the horizontal cross section of the core body is uniform over the height or the core body, e.g. allowing for production using extrusion of the core body.

In practical embodiments, the manifold plates each rest on the core bodies and/or the electrolyte feed tube members of the array below the manifold plate so as to transmit vertical load, preferably the core bodies and/or the electrolyte feed tube members of the arrays below and above the manifold plate being vertically aligned. So, it is envisaged that the core bodies and/or electrolyte feed tube members effectively act to support the manifold plates, so that - as preferred - the electrolyser is devoid of further support members between manifold plates, in particular remote from the wall of the vessel. This allows for optimal use of the space within the vessel.

In practical embodiments, the core body is a monolithic core body, e.g. of plastic material, e.g. molded or extruded of plastic material.

In practical embodiments, the tube body of the electrolyte feed tube member is a monolithic tube body, e.g. of plastic material, e.g. molded or extruded of plastic material.

In practical embodiments, the vertical spacing between manifold plates is between 80 mm and 120 mm, e.g. 100mm, e.g. this spacing being defined by the height of the core bodies and/or the electrolyte feed tube members between the manifold plates. For example, this allows electrolyte to flow with a sufficient flow velocity while still allowing sufficient time in an electrolysis zone, wherein the electrolyte is experiencing electrolysis due to electric current of the electrode assemblies.

In practical embodiments, each array comprises at least 20 electrode assemblies, possibly more than 100 electrode assemblies.

In practical embodiments, the core body has three support portions distributed about the main axis of the core body, wherein the electrode assembly has three vertically extending planar electrode faces of the outer contour of the electrode assembly seen in horizontal cross-section, wherein the electrode assemblies are arranged in the array in a pattern so that six electrode assemblies are disposed about one electrolyte feed tube member.

In practical embodiments, the core body has four support portions distributed about the main axis of the core body, wherein the electrode assembly has four vertically extending planar electrode faces of the outer contour of the electrode assembly seen in horizontal cross-section, wherein the electrode assemblies are arranged in the array in a pattern so that four electrode assemblies are disposed about one electrolyte feed tube member.

In practical embodiments, each electrolyte feed tube member has a number of vertical rows of outlet orifices, the number corresponding to the number of electrolyte flow channels adjoining the junction where the electrolyte feed tube member is arranged, wherein each row of orifices is directed to a respective electrolyte flow channel.

In practical embodiments, each electrode assembly comprises one or more vertically extending conductors that electrically interconnect the windings of the coil.

In practical embodiments, the one or more vertically extending conductor wires are mounted to, e.g. embedded in one or more of the at least three electrode support portions. In practical embodiments, the electrolyser is configured for a pressure of the electrolyte at or above 5 bar, e.g. at least 10 bar. For example, a pump causes a pressure gradient that allows the electrolyte to flow through the electrolyser. It was found that electrolysis is performed efficiently when the electrolyte has a pressure above 5 bar.

In practical embodiments, the electrolyte feed tube members are secured at one of the upper end and the lower end thereof to a manifold plate. For example, the electrolyte feed tube members are secured at their lower end to a manifold plate.

In practical embodiments, the electrode assemblies are individually removable from the array.

In embodiments, the electrode assemblies are each readily removable from a respective vertical slot in the array, e.g. such that the electrolyser is a modular electrolyser. This allows a single or multiple electrode assemblies to be removed from respective slots such that the electrode assemblies may be easily cleaned, repaired, or replaced. An electrode assembly may be removable by an operator by pulling or pushing the electrode assembly in the longitudinal direction thus removing the assembly from the slot. In other embodiments, e.g. in embodiments of the electrolyser assembly, groups of electrode assemblies may be removable from the electrolyser assembly. This further allows to remove, replace, or clean parts of the electrolyser.

In practical embodiments, the electrolyser comprises multiple vessels arranged in an outer housing.

In practical embodiments, the electrolyser is devoid of a membrane in the inter-electrode gaps.

In practical embodiments, the electrolyser has an electrical power rating of at least 1 MW, preferably at least 10 MW, more preferably at least 100 MW, e.g. at least 1 GW.

In an embodiment the electrolyser comprises:

- a vessel,

- at least three horizontal manifold plates which are vertically spaced from one another within the vessel,

- at least two arrays of a multitude of electrode assemblies and of a multitude of electrolyte feed tube members, each array being confined between two of the manifold plates, wherein each electrode assembly comprises:

- a vertically arranged elongated core body having a vertical main axis and having at least three electrode support portions distributed about the main axis of the core body,

- a helical coil of electrically conductive wire that extends about the core body in multiple windings, the wire being supported by the electrode support portions so that the windings are vertically spaced from one another, wherein each winding of the wire has at least three straight wire sections, each straight wire section between adjacent electrode support portions, wherein the straight wire sections of the windings define at least three vertically extending planar coil faces of an outer contour of the electrode assembly seen in horizontal cross-section, wherein, within each electrode assembly, at least one vertically extending electrode assembly flow channel is delimited which extends along the inner side of each planar coil face, wherein the array of electrode assemblies is such that that planar coil faces of adjacent electrode assemblies are parallel to and spaced from one another by an inter-electrode gap thereby forming an electrolyte flow channel between, wherein at each junction of electrolyte flow channels in the array an electrolyte feed tube member is present, wherein the electrolyte feed tube member comprises a vertically arranged elongated tube body having an electrolyte inlet at at least one of the lower end and upper end thereof, and having multiple outlet orifices distributed over the height of the tube body, wherein one or more of the manifold plates are provided with an electrolyte feed flow channel arrangement connected to the electrolyte inlets of the electrolyte feed tube members in the array above and/or below the manifold plate allowing to feed, in operation of the electrolyser, electrolyte into the inlets of the electrolyte feed tube members, which electrolyte then flows via the outlet orifices into the electrolyte flow channels, wherein one or more of the manifold plates are provided with an electrical wiring connected to the coils of electrolyser assemblies in the array above and/or below the manifold plate so as to create an alternating arrangement of anodic electrode assemblies and cathodic electrode assemblies in the array, the electric wiring allowing to establish, in operation of the electrolyser, an electrolyzing current between adjacent electrode assemblies in an array allowing to form electrolysis products in the electrolyte by electrolyzing the electrolyte, wherein one or more of the manifold plates are provided with an electrolysis products discharge flow channel arrangement for extracting electrolysis products from the electrode assemblies in the array below the manifold plate, wherein the electrolysis products discharge flow channel arrangement comprises, for each electrode assemblies in in the array below the manifold plate, at least one port in communication with the at least one vertically extending electrode assembly flow channel of the electrode assembly.

The present invention also relates to an array of a multitude of electrode assemblies and of a multitude of electrolyte feed tube members configured for assembly of an electrolyser as described herein.

The present invention also relates to an electrode assemblies configured for assembly of an electrolyser as described herein. The present invention also relates to an electrolyte feed tube member configured for assembly of an electrolyser as described herein.

The present invention also relates to the combination a multitude of electrode assemblies and a multitude of electrolyte feed tube members configured for assembly of an electrolyser as described herein.

The present invention also relates to a method for performing electrolysis, wherein use is made of an electrolyser as described herein, e.g. to create hydrogen, e.g. as a fuel. For example, the hydrogen is stored for later use.

The invention will be explained below with reference to the drawing in which:

Fig. 1 shows a schematic view of an embodiment of the electrolyser,

Fig. 2 shows an enlarged part of figure 1 ,

Fig. 3 shows schematically a vertical cross-section of the electrolyser of figure 1 ,

Fig. 4 shows a detail of the electrolyser of figure 1 ,

Fig. 5 shows a schematic view of another embodiment of the electrolyser.

With reference to the figures 1 - 4 a first embodiment of an electrolyser according to the invention will be discussed.

In figure 1 only a portion of the electrolyser 1 is depicted. This includes a part of the vessel 2 and one of the at least three horizontal manifold plates 10 which are vertically spaced from one another within the vessel 2.

For example, the electrolyser 1 has an electrical power rating of at least 1 MW, preferably at least 100 MW, more preferably at least 100 MW, e.g. at least 1 GW. This entails that figure 1 (and figure 5) only shows a minute portion of the entire electrolyser, yet sufficient to appreciate the innovative design.

Generally, the vessel 2 accommodates at least two arrays of a multitude of electrode assemblies 20 and of a multitude of electrolyte feed tube members 40, each array being confined between two of the manifold plates 10.

In figures 1 - 4 all electrode assemblies 20 are identical.

In figure 2 one assembly 20 is shown in raised position to clarify the structure of the electrode assemblies 20.

Each electrode assembly 20 comprises a vertically arranged elongated core body 25 having a vertical main axis. As preferred, the core body is made of plastic, e.g. injection molded or extruded, The core body 25 has in horizontal cross-section an X-shape with a central core portion 26 from which four vertically arranged ribs 27a,b,c,d extend outwards in different angular directions to define four support portions distributed about the main axis of the core body. Herein each rib delimits a vertically extending support face of the core body.

Generally, an electrode structure 30 extends about the core body 25.

It is illustrated that the electrode structure of electrode assembly 20 is embodied as a helical coil of electrically conductive wire 31 that extends about the core body 25 in multiple windings, the wire being supported by the electrode support portions 27a,b,c,d so that the windings are vertically spaced from one another.

Each winding of the wire has four straight wire sections, each straight wire section between adjacent electrode support portions 27a,b,c,d.

These straight wire sections of the windings define the four vertically extending planar electrode faces

31 a, b, c, d of an outer contour of the electrode assembly 20 seen in horizontal cross-section.

It is illustrated that each electrode support portion or vertical rib 27a,b,c,d delimits a vertically extending coil support face of the core body 25.

It is illustrated that the helical coil of electrically conductive wire 31 is wrapped around the core body 25 in multiple windings, the wire being supported by the coil support faces so that the windings are vertically spaced from one another forming flow openings.

It is illustrated that each electrode assembly 20 comprises one or more vertically extending conductors

32 that electrically interconnect the windings of the coil 30. In the example, a vertically extending conductor wire 32 is embedded in each of the ribs 27a, b, c and in contact with the coil.

Between each pair of adjacent ribs 27a,b,c,d a vertically extending electrode assembly flow channel 28a, b, c, d is delimited which extends along the inner side of each planar electrode face 31 a, b.

It is illustrated that the array of electrode assemblies 20 is such that that planar electrode faces 31 a, b of adjacent electrode assemblies 20 are parallel to and spaced from one another by an inter-electrode gap 33 thereby forming an electrolyte flow channel 34 between them.

It is illustrated that no membrane is positioned in the inter-electrode gap 33. The electrolyser is membraneless. It is illustrated that at each junction of electrolyte flow channels 34 in the array an electrolyte feed tube member 40 is present.

The electrolyte feed tube member 40 comprises a vertically arranged elongated tube body 41 having an electrolyte inlet 42 at the lower end thereof and having multiple outlet orifices 43 distributed over the height of the tube body.

Each electrolyte feed tube member 40 has a number of vertical rows of outlet orifices 43, the number corresponding to the number of electrolyte flow channels 34 adjoining the junction where the electrolyte feed tube member 40 is ranged. Each row of orifices 43 is directed to a respective electrolyte flow channel 34.

It is illustrated that each of the manifold plates 10 is provided with an electrolyte feed flow channel arrangement 11 that is connected to the electrolyte inlets 41 of the electrolyte feed tube members 40 in the array above the manifold plate 10 allowing to feed, in operation of the electrolyser, electrolyte into the inlets 41 of the electrolyte feed tube members 40, which electrolyte then flows via the outlet orifices 43 into the electrolyte flow channels 34.

It is illustrated that each of the manifold plates 10 is provided with an electrical wiring 14a,b connected to the electrode structures, here coils, of electrolyser assemblies 20 in the array below the manifold plate 10 so as to create an alternating arrangement of anodic electrode assemblies 20a and cathodic electrode assemblies 20b in the array.

The electric wiring 14a,b allows to establish, in operation of the electrolyser, an electrolyzing current between adjacent electrode assemblies 20a, b in an array allowing to form electrolysis products in the electrolyte by electrolyzing the electrolyte.

It is illustrated that each of the manifold plates 10 is provided with an electrolysis products discharge flow channel arrangement for extracting electrolysis products from the electrode assemblies in the array below the manifold plate, wherein the electrolysis products discharge flow channel arrangement comprises, for each electrode assemblies in in the array below the manifold plate, at least one port in communication with the at least one vertically extending electrode assembly flow channel of the electrode assembly.

In more detail the manifold plate 10 has a two separated discharge flow channel arrangements, one generally above the other, wherein a first flow channel arrangement 15 is associated with the anodic electrode assemblies 20a, and wherein a second flow channel arrangement 16 is associated with the cathodic electrode assemblies 20b. It is illustrated that the manifold plate 10 rest on the core bodies 25 and/or the electrolyte feed tube members 40 of the array below the manifold plate 10 so as to transmit vertical load. Preferably, the core bodies and/or the electrolyte feed tube members of the arrays below and above the manifold plate 10 are vertically aligned.

It is illustrated that the core body 25 is a monolithic core body, e.g. of plastic material, e.g. molded or extruded of plastic material.

It is illustrated that the tube body 41 of the electrolyte feed tube member 40 is a monolithic tube body, e.g. of plastic material, e.g. molded or extruded of plastic material.

It is illustrated that the vertical spacing between manifold plates 10 is between 80 and 120 mm, e.g. 100mm.

For example, each array comprises at least 20 electrode assemblies 20a, b.

The electrolyser 1 is configured for a pressure of the electrolyte at or above 5 bar, e.g. 10 bar.

It is illustrated that the electrode assemblies 20 are individually removable from the array.

For example, the electrolyser 1 comprises multiple vessels 2 arranged in an outer housing

In figure 5 the horizontal cross section of the core body 25 has a Y-shape so that the core body has three support portions distributed about the main axis of the core body. Thereby the electrode assembly 20 has three vertically extending planar electrode faces of the outer contour of the electrode assembly seen in horizontal cross-section. It is illustrated that the electrode assemblies 20 are arranged in the array in a pattern so that six electrode assemblies 20 are disposed about one electrolyte feed tube member 40.

For example, the electrolyser 1 has an electrical power rating of at least 1 MW, preferably at least 100 MW, more preferably at least 100 MW, e.g. at least 1 GW.

The operation of the electrolyser 1 can now be readily understood. An electrolyte, e.g. water, is circulated through the electrolyser 1 using a pump. The pump feeds electrolyte into the electrolyte feed flow channel arrangement 11 that is connected to the electrolyte inlets 41 of the electrolyte feed tube members 40 in the array above the manifold plate 10 so that electrolyte flows into the inlets 41 of the electrolyte feed tube members 40, which electrolyte then flows via the outlet orifices 43 into all of the electrolyte flow channels 34. The electrolyte is then subject to electrolysis, with oxygen gas being formed at the coils of the anode assemblies 20a and hydrogen gas being formed at the coils 30 of the cathode assemblies 20b. Due to the flow of the electrolyte from the flow channel 34 through the gaps between the windings of the coil into the vertically extending electrode assembly flow channels 28a, b, c the gas is entrained upward within the contour of the respective assembly. At the upper end of the respective assembly, the electrolysis product, so electrolyte plus oxygen gas or electrolyte plus hydrogen gas, enters the respective first flow channel arrangement 15 associated with the anodic electrode assemblies 20a, and the second flow channel arrangement 16 associated with the cathodic electrode assemblies 20b. Via further ducts of the electrolyser, e.g. fitted in/on the vessel 2, the electrolysis product flows leave the electrolyser. The gases are separated and the electrolyte, here water, is recirculated into the electrolyser 1 .