Electrolyser

Abstract

An electrolyser 10 which provides a hydrogen gas containing stream and a separate oxygen gas containing stream from an aqueous electrolyte is described. The electrolyser comprises a hollow locating me

Description

The present invention relates to an electrolyser for providing separate hydrogen gas and oxygen gas streams from an aqueous electrolyte. The present invention also relates to a method of obtaining separate hydrogen gas and oxygen gas streams from an aqueous electrolyte. BACKGROUND OF INVENTION Electrolysis of water has been known for around 200 years, and this technique has received increased attention in recent years because of its potential role in the hydrogen energy economy. Demand for hydrogen is increasing as hydrogen provides a convenient means to store electrical energy generated from the growing deployment of clean and renewable energy sources. However, current electrolysis methods for hydrogen production are comparatively inefficient and not amenable to large-scale implementation. The efficiency of the electrolysis system is critical both technically and economically for electrochemical hydrogen generation using renewable energy. Water is split into its constituent elements of hydrogen and oxygen within an electrolyser according to the following reaction equation: + -a. x- --y -• A single electrolyser cell consists of an anode and a cathode connected via a DC power supply, the anode and cathode are separated by a chamber containing an electrolyte (such as water). When operating, a current flows across the cell, and electrons on the cathode surface are consumed by hydrogen ions, forming hydrogen gas. To maintain equilibrium, hydroxide ions transfer through the chamber towards the anode, releasing electrons at the anode surface thereby forming oxygen. The electrochemical reactions occurring at the cathode and anode are given by: Cathode- 4- Ze“ -* Anode 02 -f 4e The electrolytic reactions described above are heterogeneous reactions, meaning that they take place at the boundary between the electrode and the electrolyte. At this interface there exists a galvanic potential gradient in the boundary layer, and this two-phase layer has a dramatic effect on the efficiency of the conversion process. Electrical resistances that degrade the performance of the cell can be classified into two groups. The first is "reaction resistance" due to the overpotential required to overcome activation energies of the hydrogen and oxygen evolution reactions at the electrode surface, which increases the overall cell potential. Secondly, "transport resistance" involving physical resistances originating from gas bubbles covering the electrode surface and in the electrolyte solution, and finally the resistances to ionic transfer within the electrolyte, which relates to mass transfer. Known electrolysers often use expensive materials in the electrodes within the cell and typically use membranes between the electrodes to separate the gas species, which are expensive. The use of caustic substances within the electrolyte are also common in existing electrolysers and there are frequently cost and / or safety issues relating to the use of such substances. The cost to construct and maintain an electrolyser affect the economics of the use of the electrolyser and therefore the use of expensive components undermines the desirability of the use of the electrolyser. It is therefore an object of the invention to improve upon the known art. SUMMARY OF INVENTION According to a first aspect of the present invention, there is provided an electrolyser for providing a hydrogen gas containing stream and a separate oxygen gas containing stream from an aqueous electrolyte, the electrolyser comprising: a hollow locating member defining a fluid conduit for receiving an electrolyte, in which the hollow locating member comprises at least one opening, a fluid pump configured in use to pump electrolyte into and through the fluid conduit of the hollow locating member; a stacked arrangement received on the locating member, in which the stacked arrangement comprises at least one electrolysis cell, each electrolysis cell comprising: a anode having a first side and a second opposed side; a cathode having a first side and a second opposed side, in which the first side of the anode is positioned adjacent the first side of the cathode; a reaction chamber defined between the first side of the anode and the first side of the cathode, in which the reaction chamber is in fluid communication with the at least one opening of the hollow locating member; a magnet positioned adjacent the second side of the anode; a first gas collection chamber positioned adjacent the second side of the anode, in which the first gas collection chamber is in fluid communication with the reaction chamber; and a second gas collection chamber positioned adjacent the second side of the cathode, in which the second gas collection chamber is in fluid communication with the reaction chamber; and a power supply for providing a DC power source to the anode and cathode of each electrolysis cell. The electrolyser of the present invention allows separated streams of hydrogen and oxygen to be collected from each respective gas collection chamber. The hydrogen gas stream is distinct from the oxygen gas stream. Hydrogen is collected from the second gas collection chamber adjacent the cathode. Oxygen is collected from the first gas collection chamber of the anode. The electrolyser therefore removes the need for any downstream gas separation processing (for example in order to separate hydrogen gas from oxygen gas) and as a result provides a more efficient means for generating two distinct gas streams: a hydrogen gas stream; and an oxygen gas stream from the electrolysis of an aqueous electrolyte. In one embodiment, the stacked arrangement is located substantially centrally on the locating member. The anode is preferably disc-shaped. The cathode is preferably disc-shaped. Preferably, each of the anode and cathode provides at least one opening configured in use to receive the locating member therethrough. The opening of the anode is preferably aligned with the opening of the cathode. Preferably, the at least one opening of the anode and cathode is substantially centrally located. The anode preferably extends outwardly from and substantially perpendicular to a longitudinal axis defined by the locating member. The cathode preferably extends outwardly from and substantially perpendicular to a longitudinal axis defined by the locating member. The or each electrolysis cell preferably further comprises a spacer located between the cathode and the anode to provide the reaction chamber. The spacer is preferably located between the first side of the cathode and the first side of the anode. The locator is preferably shaped and dimensioned to provide a reaction chamber having predefined width (as measured between the first side of the anode and the first side of the cathode). The locator is preferably composed of insulating material, such as for example high density polymer. The locating member is preferably perforated. Preferably, the locating member comprises a plurality of openings. Each opening is preferably in fluid communication with an inlet (for example an annular spacing) of an electrolysis cell of the stacked arrangement. For example, the or each electrolysis cell is located along the length of the locating member such that an inlet (for example an annular spacing) of the or each electrolysis cell is aligned with or positioned adjacent an opening of the locating member. The inlet of the or each electrolysis cell is preferably in fluid communication with the reaction chamber. In one embodiment, the electrolyser further comprises a flow diverter. The flow diverter preferably extends into an inlet of the reaction chamber so as to disrupt the flow of electrolyte as it enters from the hollow locating member. The flow diverter is preferably planar. The flow diverter preferably extends in a direction extending substantially parallel to the first sides of the anode and / or cathode. The flow diverter is preferably configured to create laminar flow regime of the electrolyte within the reaction chamber. The flow diverter is preferably substantially centrally located within the inlet of the reaction chamber (ie. centrally positioned between the first surfaces of the anode and cathode of the cell). Under supersaturation conditions, the laminar flow of the electrolyte created by the flow diverter leverages the Segre-Silberberg effect in which the fluid velocity gradient causes bubbles to be pinned close to the electrode surface boundary layer thereby minimising hydrogen and oxygen gas crossover. The cell may further comprise a transfer ring located at an end of the anode and cathode adjacent the locating member. The transfer ring is preferably configured to be in fluid communication with the locating member and the reaction chamber. For example, the transfer ring is preferably configured to define a fluid pathway for electrolyte from the locating member to the reaction chamber. The electrolysis cell preferably further comprises at least one outlet in fluid communication with the first gas collection chamber and / or second gas collection chamber. The anode and / or cathode preferably further comprises at least one outlet in fluid communication with the first gas collection chamber and / or second gas collection chamber and the reaction chamber. The anode preferably comprises a first outlet in fluid communication with the first gas collection chamber. The cathode preferably comprises a second outlet in fluid communication with the second gas collection chamber. The at least one outlet is preferably provided at or adjacent the periphery of the respective anode or cathode. The inlet to the reaction chamber is preferably centrally located within the cell (for example disc shaped cell) and adjacent the locating member, and the outlet(s) are spaced apart from the inlet and positioned at or adjacent a periphery of the cell. In one embodiment, the or each outlet is T-shaped comprising a first outlet in fluid communication with the first gas collection chamber, and a second outlet in fluid communication with the second gas collection chamber. Preferably each outlet is T-shaped. The anode of the or each electrolysis cell is preferably annular in shape. The cathode of the or each electrolysis cell is preferably annular in shape. The reaction chamber is preferably annular in shape. The anode preferably comprises stainless steel. The first side of the anode is preferably nickel plated. The cathode preferably comprises stainless steel. The stacked arrangement preferably comprises a plurality of electrolysis cells. The first gas collection chamber is preferably in communication with a first anode of a first electrolysis cell and a second anode of an adjacent electrolysis cell. A second side of a first anode of a first electrolysis cell is preferably located adjacent and spaced apart from a second side of a second of a second anode of a second electrolysis cell to define the first gas collection chamber therebetween. The second gas collection chamber is preferably in communication with a second cathode of a first electrolysis cell and a second cathode of an adjacent electrolysis cell. A second side of a first cathode of a first electrolysis cell is preferably located adjacent and spaced apart from a second side of a second of a second cathode of a second electrolysis cell to define the second gas collection chamber therebetween. The first and / or second gas collection chamber(s) is preferably in communication with the locating member to return electrolyte to the fluid conduit. The magnet is preferably a permanent magnet. In one embodiment, the magnet is disc shaped. The reaction chamber may have any suitable thickness (as measured between the first surfaces of the adjacent anode and cathode). The first gas collection chamber preferably has a thickness which is greater than the reaction chamber. Thickness of the first gas collection chamber is measured in a direction extending between the second surface of the anode and the opposing side wall of the chamber, for example the second surface of a further anode of a further electrolysis cell). The second gas collection chamber preferably has a thickness which is greater than the reaction chamber. Thickness of the second gas collection chamber is measured in a direction extending between the second surface of the cathode and the opposing side wall of the chamber, for example the second surface of a further cathode of a further electrolysis cell. The thickness of the reaction chamber and first and second gas collections chambers is preferably measured in a direction extending perpendicular to the fluid flow of electrolyte into the reaction chamber. The thickness of the first and / or second gas collection chamber is preferably at least five times, preferably at least ten times, the thickness of the reaction chamber. As the electrolyte together with generated, separated hydrogen gas stream or oxygen gas stream passes through the respective outlet, from the reaction chamber to the respective first or second gas collection chamber, there is a change in pressure (e.g. decreased pressure) due to the increased thickness of the gas collection chamber in comparison to the reaction chamber. This reduced pressure at the respective outlet causes the generated hydrogen or oxygen gas present in the electrolyte to be collected and separated from the electrolyte. The recovered electrolyte may then be returned to the fluid conduit of the locating member. The electrolyte is preferably an aqueous electrolyte. Suitable aqueous electrolyte include for example freshwater or seawater. According to a second aspect of the present invention, there is provided a method of producing separate streams of hydrogen gas and oxygen gas from an aqueous electrolyte using an electrolyser as herein described, the method comprising: providing a DC power source to the anode and cathode of the at least one electrolysis cell; introducing electrolyte through the fluid conduit and opening(s) of the locating member into the reaction chamber(s) of the electrolysis cell(s) in a flow direction extending substantially parallel to a first surface of a anode and a first surface of a cathode; obtaining a first stream of oxygen from the first gas collection chamber of the anode; and obtaining a second stream of hydrogen from the second gas collection chamber of the cathode. The electrolyte preferably flows from the locating member into the reaction chamber (for example from an opening provided by the respective anode and cathode) in a direction towards the periphery of the anode and cathode. Embodiments of the present invention will now be described in more detail in relation to the accompanying Figures: BRIEF DESCRIPTION Figure 1 is a schematic diagram of an electrolyser according to one embodiment of the present invention; Figure 2 is a schematic diagram of an electrolyser according to a second embodiment of the present invention; Figure 3 is a schematic diagram of an electrolyser according to a third embodiment of the present invention; Figure 4 is a perspective view of an electrolyser incorporating multiple cells according to a further embodiment of the present invention; Figure 5 is a cross-sectional view of a cell of the electrolyser of Figure 4; Figure 6 is an enlarged view of a portion of the cross-sectional view of Figure 5; Figure 7 is a further enlarged view of a portion of the cross-sectional view of Figure 5, Figure 8 is a plan view of an electrode of an electrolyser according to one embodiment of the present invention; and Figure 9 is a cross-sectional view of a portion of the of the electrolyser of Figure 4. DETAILED DESCRIPTION With reference to Figures 1 to 8, the electrolyser 10 comprises a hollow locating member 32 defining a fluid conduit for receiving an electrolyte. The hollow locating member comprises a plurality of openings 42 spaced apart from each other along the length (as measured between opposed ends thereof) of the locating member 32. The electrolyser 10 further comprises a fluid pump 26 configured in use to pump electrolyte into and through the fluid conduit of the hollow locating member 32 and out of the openings 42. The electrolyser 10 further comprises a stacked arrangement of electrolysis cells 12 received on the locating member 32. The stacked arrangement comprises a plurality of electrolysis cells 12 as shown in Figure 4, although only one such cell 12 is shown in Figures 1 to 3 for ease of understanding. In the stack arrangement of electrolysis cells of Figure 4 there are ten cells 12. It is however to be understood that the electrolyser may comprise any suitable number of electrolysis cells. Each electrolysis cell 12 comprises an anode 14 having a first side 11 and a second opposed side 13. Each side 11,13 is substantially planar. In the illustrated embodiment, the anode is substantially disc-shaped. It is however to be understood that the anode may have any suitable shape. The anode is composed of stainless steel (preferably high chrome stainless steel). The first side 11 of the anode 14 is nickel plated. It is however to be understood that the anode may be made of any suitable materials and / or coatings. Each electrolysis cell 12 further comprises a cathode 16 having a first side 15 and a second opposed side 17. Each side 15,17 is substantially planar. In the illustrated embodiment, the cathode is substantially disc-shaped. It is however to be understood that the cathode may have any suitable shape. In the illustrated embodiment, the first side of the anode 15 is positioned adjacent the first side of the 11 anode. The cathode is composed of stainless steel (preferably high chrome stainless steel). It is however to be understood that the cathode may be made of any suitable material. Each electrolysis cell 12 is positioned along the locating member 32 such that the first sides 11,15 of the anode 14 and cathode 16 extend substantially perpendicular to the longitudinal axis of the locating member 32. A reaction chamber 18 is defined between the first sides 11,15 of the anode 14 and cathode 16. The reaction chamber 18 is in fluid communication with the at least one opening 42 of the hollow locating member 32. A permanent magnet 30 is positioned adjacent the second side 13 of the anode 14. The magnet 30 is of uniform thickness and is bonded to the anode 14 on its reverse side. The magnet has a thickness of around 5mm and each electrode 14 and 16 has a thickness of around 2mm (not shown to scale). A first gas collection chamber 34a is positioned adjacent the second side 13 of the anode 14. The first gas collection chamber 34a is in fluid communication with the reaction chamber 18. A second gas collection chamber 34b is positioned adjacent the second side 17 of the cathode 16. The second gas collection chamber 34b is in fluid communication with the reaction chamber 18. Each gas collection chamber 34a, 34b is located on an opposing side of the reaction chamber 18. The thickness of the reaction chamber 18 (as measured between the first surfaces 11,15 of the anode 14 and cathode 16) is less than the thicknesses of the first and second gas collection chambers 34a, 34b (as measured between the second surface of the anode and opposing side wall, and the second surface of the cathode and opposing side wall). Preferably, the thickness of the reaction chamber 18 is 1 mm. In the illustrated embodiment, the first and second gas collection chambers 34a, 34b have a thickness of about 25mm. The first and second gas collection chambers approximately have the same thickness. The electrolyser 10 further comprises a power supply for providing a DC power source 28 to the anode 14 and cathode 16 of each electrolysis cell 12. The reaction chamber 18 is annular in shape. The reaction chamber 18 comprises a fluid inlet 19 for receiving electrolyte from the openings 42 of the locating member 32, and an outlet 21. In the illustrated embodiment, the outlet 21 comprises a T-shaped channel 22 comprising a first outlet 22a and a second outlet 22b at opposing ends thereof in communication with the reaction chamber 18 and each of the gas collection chambers 34a, 34b. The electrolyser further comprises two end caps 29 that are located at respective ends of the stack and a plurality of spaced apart tie rods 38. Each tie rod 38 is connected to each end cap 39. The tie rods and end caps maintain the cells in position. Insulating spacers may be positioned between the respective first surfaces 11,15 of the anode and cathode of each cell 12 to provide a predetermined spacing therebetween to define the reaction chamber. A flow diverter 44 may be positioned between the electrodes 14 and 16 to create a laminar flow of the electrolyte. As shown in Figure 9, the flow diverter 44 extends through the inlet 19 into the reaction chamber 18 in a direction extending substantially parallel to the plane defined by the first surface of the anode or cathode. The flow diverter 44 is substantially centrally located between the anode 14 and cathode 16 of a cell. The insulating spacers are configured to locate the flow diverter 44 in a predetermined location with respect to the inlet 19. Under supersaturation conditions, the flow diverter leverages the Segre-Silberberg effect, whereby the fluid velocity gradient helps to pin bubbles close to the electrode surface boundary layer minimising hydrogen and oxygen crossover. As can be seen most clearly in Figure 6, a transfer ring 40 is positioned within each cell 12 adjacent the locating member 32. The transfer ring 40 in the illustrated embodiment is located adjacent the opening provided by each of the anode 14 and cathode 14 positioned adjacent the locating member 32. The transfer ring 40 is configured in use to provide a fluid pathway for electrolyte as it passes from the locating member 32 to an inlet of the reaction chamber 18. The purpose of the transfer ring 40 is to direct the flow of the electrolyte into the reaction chamber 18 of each cell 12. In use, the fluid pump 26 provides pressure to an electrolyte (for example water), thereby forcing electrolyte through the locating member 32 out of the opening 42 and into the reaction chamber 18 of the corresponding electrolysis cell 12. In one embodiment, the electrolyte flows through the locating member 32, out of the openings 42 and into the transfer ring 40 which directs the electrolyte into the reaction chamber 18. The electrolyte is driven through the reaction chamber 18 in a direction extending substantially parallel to the plane defined by the first surfaces 11,15 of the anode 14 and cathode 16 from the locating member 32 towards the periphery of the anode 14 and cathode 16. The power supply 28 provides current across the anode 14 and cathode 16 causing electrolysis of the electrolyte within the reaction chamber 18 to produce hydrogen and oxygen. The electrochemical reactions occurring at the cathode and anode are given by: Cathode 2¾^ + 2«" f Anode 02 -f 4e The electrolytic reactions described above are heterogeneous reactions, meaning that they take place at the boundary between the electrode and the electrolyte. At this interface there exists a galvanic potential gradient in the boundary layer, and this two-phase layer has a dramatic effect on the efficiency of the conversion process. The magnetic field produced by the magnet 30 at the anode 14 polarises the electrolyte, thereby increasing conversion efficiency by attracting hydroxide anions towards the anode, repelling hydrogen cations and by increasing the polarization coherence of H2O electrons (alignment of the dipoles of the water molecules in the direction of the magnetic field), by slowing their speed of rotation (spin), and by stabilizing their molecular structure, thus reducing kinetic losses. The positioning of the magnet 30 (and the resulting magnetic field) in relation to the two gas collection chambers 34a, 34b and the T-shaped channel 22 tends to result in the hydrogen and oxygen gases present within the electrolyte to be separated into two distinct flows on leaving the reaction chamber 18, with the hydrogen gas enriched electrolyte exiting away from the magnet 30 and into the second gas collection chamber 34b and the oxygen gas enriched electrolyte exiting toward the magnet 30 and into the first gas collection chamber 34a. This assists in the recovery of the gases from the electrolyte as they separate into two streams on leaving the reaction chamber 18 and are then processed separately. The electrolyte is preferably water and the contaminants present in water can be a problem for electrolysers as they can adhere to and / or clog up the reaction chamber and / or adhere to the cathode and / or anode thereby reducing the efficiency of the gas production at the surface of the cathode and / or anode. The magnetic field produced by the magnet 30 aids in the removal of contaminants from the reaction chamber 18 via the flow of the electrolyte. As shown in more detail in Figures 5 to 7, the fluid electrolyte passes through the reaction chamber 18 in a direction extending substantially parallel to the first surfaces 11, 15 of the anode 14 and cathode 16, with the generated hydrogen and oxygen gases present therein, and exits the reaction chamber 18 via fluid outlet 21. The fluid diverter (if present) helps to provide laminar flow of the electrolyte as it passes through the reaction chamber and to aid separation of the hydrogen gas containing stream and the oxygen gas containing stream. The fluid electrolyte together with hydrogen passes through the outlet 22a of the cathode 16. The fluid electrolyte together with oxygen passes through the outlet 22b of the anode 14. The electrolyser 10 therefore provides separate, distinct gas streams: a hydrogen gas stream and an oxygen gas stream generated by electrolysis of the aqueous electrolyte. The respective gas may then be separated from the electrolyte. In one embodiment, the electrolyser 10 comprises a return path for the electrolyte to be returned to the fluid conduit of the locating member 32. In particular, each gas collection chamber provides a return fluid conduit for returning the electrolyte to the locating member 32. In one embodiment, the returned electrolyte may be reintroduced into an reaction chamber of an electrolysis cell. The method may be a continuous process in which the pump continuously introduces electrolyte into the reaction chamber of the electrolysis cell.

Claims

1. An electrolyser providing a hydrogen gas containing stream and a separate oxygen gas containing stream from an aqueous electrolyte, the electrolyser comprising:a hollow locating member defining a fluid conduit for receiving an electrolyte, in which the hollow locating member comprises at least one opening,a fluid pump configured in use to pump electrolyte into and through the fluid conduit of the hollow locating member;a stacked arrangement received on the locating member, in which the stacked arrangement comprises at least one electrolysis cell, each electrolysis cell comprising: an anode having a first side and a second opposed side;a cathode having a first side and a second opposed side, in which the first side of the anode is positioned adjacent the first side of the cathode;a reaction chamber defined between the first side of the anode and the first side of the cathode, in which the reaction chamber is in fluid communication with the at least one opening of the hollow locating member;a magnet positioned adjacent the second side of the anode;a first gas collection chamber positioned adjacent the second side of the anode, in which the first gas collection chamber is in fluid communication with the reaction chamber; anda second gas collection chamber positioned adjacent the second side of the cathode, in which the second gas collection chamber is in fluid communication with the reaction chamber; anda power supply for providing a DC power source to the anode and cathode of each electrolysis cell.

2. An electrolyser as claimed in claim 1, in which the stacked arrangement is located substantially centrally on the locating member.

3. An electrolyser as claimed in either of claims 1 and 2, in which each of the anode and cathode provides at least one opening configured in use to receive the locating member therethrough.

4. An electrolyser as claimed in claim 3, in which the opening of the anode is aligned with the opening of the cathode.

5. An electrolyser as claimed in any preceding claim, further comprising a spacer located between the cathode and anode to provide the reaction chamber.

6. An electrolyser as claimed in any preceding claim, in which the locating member is perforated, and in which each opening is in fluid communication with an annular spacing of an electrolysis cell of the stacked arrangement.

7. An electrolyser as claimed in any preceding claim, further comprising a flow tube configured in use to provide electrolyte to the reaction chamber.

8. An electrolyser as claimed in claim 7, in which the flow tube extends into the reaction chamber in a direction extending substantially parallel to the plane defined by the first sides of the anode and cathode.

9. An electrolyser as claimed in any preceding claim, in which the reaction chamber further comprises at least one outlet in fluid communication with the first gas collection chamber and / or second gas collection chamber.

10. An electrolyser as claimed in claim 9, in which the reaction chamber comprises a first outlet in fluid communication with the first gas collection chamber.

11. An electrolyser as claimed in either of claims 9 and 10, further comprising a second outlet in fluid communication with the second gas collection chamber.

12. An electrolyser as claimed in any one of claims 9 to 11, in which the outlet is T-shaped comprising a first outlet in fluid communication with the first gas collection chamber, and a second outlet in fluid communication with the second gas collection chamber.

13. An electrolyser as claimed in any preceding claim, in which the anode of the or each electrolysis cell is annular in shape.

14. An electrolyser as claimed in any preceding claim, in which the cathode of the or each electrolysis cell is annular in shape.

15. An electrolyser as claimed in any preceding claim, in which the anode comprises stainless steel.

16. An electrolyser as claimed in claim 15, in which the first side of the anode is nickel plated.

17. An electrolyser as claimed in any preceding claim, in which the cathode comprises stainless steel.

18. An electrolyser as claimed in any preceding claim, in which the stacked arrangement comprises a plurality of electrolysis cells.

19. An electrolyser as claimed in claim 18, in which the first gas collection chamber is in communication with a first anode of a first electrolysis cell and a second anode of an adjacent 5 electrolysis cell.

20. An electrolyser as claimed in either of claims 18 and 19, in which the second gas collection chamber is in communication with a second cathode of a first electrolysis cell and a second cathode of an adjacent electrolysis cell.

21. An electrolyser as claimed in any preceding claim, in which the first and / or second gas 10 collection chamber(s) is in communication with the locating member to return electrolyte to the fluid conduit.

22. An electrolyser as claimed in any preceding claim, in which the magnet is a permanent magnet, (disc shaped)23. An electrolyser as claimed in any preceding claim, in which the first gas collection 15 chamber has a thickness which is greater than the reaction chamber.

24. An electrolyser as claimed in any preceding claim, in which the second gas collection chamber has a thickness which is greater than the reaction chamber.

25. A method of producing separate streams of hydrogen and oxygen from an aqueous electrolyte using an electrolyser as herein described, the method comprising20 providing a DC power source to the anode and cathode of the at least one electrolysiscell;introducing electrolyte through the fluid conduit and opening(s) of the locating member into the reaction chamber(s) of the electrolysis cell(s) in a flow direction extending substantially parallel to a first surface of a anode and a first surface of a cathode;25 obtaining a first stream of oxygen from the first gas collection chamber of the anode;andobtaining a second stream of hydrogen from the second gas collection chamber of the cathode.

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