Hydrogen generation

Abstract

An apparatus 1 for generating hydrogen, which comprises a housing 10 with a first electrode 11 and a second electrode 12. Each of the electrodes is submersed in water located within the housing 10. Th

Description

This invention relates generally to hydrogen generation. More specifically, although not exclusively, this invention relates to an apparatus and a method for generating hydrogen from water. It is recognised that the increase in atmospheric carbon dioxide, at least in part, is caused by the use of fossil fuels as an energy source. In order to meet legal obligations on the emission of carbon dioxide it is essential that we reduce our reliance on this type of nonrenewable fuels, which produce pollutants and greenhouse gases when combusted. A promising alternative to the use of fossil fuels is hydrogen fuel. This is because hydrogen is considered to be a clean fuel which, when consumed in a fuel cell or engine, produces water. Consequently, this makes hydrogen fuel an attractive option for transportation, as well as for producing electricity and thermal energy to power our homes, in addition to many other applications. The most common methods for generating hydrogen include steam-methane reforming and electrolysis. In steam-methane reforming, high temperature steam under pressure is reacted with methane in the presence of a catalyst to produce hydrogen, carbon monoxide, and a small amount of carbon dioxide. In contrast, electrolysis of water splits water into its constituents using an electric current. Therefore, if the electricity used in the process is from a renewable source, then electrolysis of water to produce hydrogen is considered to be a clean and green process, because it does not produce carbon-containing emissions. Several different types of electrolysers for producing hydrogen are known. These include polymer electrolyte membrane (PEM) electrolysers, alkaline electrolysers, and solid oxide electrolysers. There is a need to increase the rate of hydrogen production from the electrolysis of water. There is also a need to reduce the complexity and expense of the components used in electrolysers of the prior art. There is also a need to provide electrolysers which can be used on different water sources (potable, rain, sea water for example). It is therefore a first non-exclusive object of the invention to provide an apparatus and method for generating hydrogen from water, which is at least one of more efficient, green, universally applicable to many water sources and cost effective. Accordingly, a first aspect of the invention provides an apparatus for generating hydrogen, the apparatus comprising a housing containing a first electrode and a second electrode for submersion within water located within the housing, the first electrode surrounding the second electrode, wherein the first electrode is of cylindrical form and the second electrode is of at least part conical or frusto-conical form, wherein the first electrode is preferably a or the anode and the second electrode is preferably a or the cathode. The housing may be fabricated from glass or from metal If the housing is formed of metal the electrodes may be electrically insulated from the housing. The second electrode may proximate to, for example may be in physical contact with, a glass body, for example a glass cylinder. It will be appreciated that the second electrode may be conical or frusto-conical, or at least a part of the second electrode may be conical or frusto-conical. In this regard, the walls of the second housing may taper inwardly from a base portion towards a top portion, the degree of taper may be constant or may vary between the base portion and the top portion. The housing may have a base portion and a top portion. The second electrode may taper outwardly from the base portion towards the top portion of the housing ( / .e. such that the top portion of the second electrode is proximate the base portion of the housing and the base portion of the electrode is located towards the top portion of the housing. The glass cylinder may be located between the housing (e.g. the top portion of the housing) and the second electrode (e.g. the base portion of the second electrode). The top portion of the housing may comprise a glass body receiving portion. The glass body may be secured to the top portion of the housing. In embodiments, the water may be fresh or pure or deionised water. Advantageously, the apparatus does not require the use of an electrolyte to generate hydrogen. However, a small amount of electrolyte (up to 1 w / w%) may be utilised to increase the efficiency of the reaction. In alternative embodiments, the water may be rain water. In embodiments, the glass may be borosilicate glass and may comprise or be heat tempered glass. Advantageously, the use of a housing fabricated from glass. We have found that glass, as opposed to say plastic, increases the effectiveness of hydrogen production. Without wishing or intending to be limited by any particular theory, we believe that a glass housing absorbs less of the generated energy. ... In embodiments, one or both of the electrodes, e.g. both the anode and / or the cathode, are fabricated from materials that are conductive and resistant to oxidation. In embodiments, the anode is fabricated from stainless steel, e.g. 316L stainless steel which may be coated with a protective coating. In embodiments, the cathode may be fabricated from or coated with a Nobel metal (e.g. rhenium, ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, copper and gold), preferably selected from copper, silver, gold or platinum. The cathode may be formed of stainless steel and coated with a second metal. In embodiments, the anode may be fabricated from a mesh material. In embodiments, the mesh material may be an unwelded mesh with a grid spacing from 20 to 100 US Mesh, preferably from 40 to 60 US mesh (corresponding to 425 to 250pm). In embodiments, the cathode, may be fabricated from a solid (i.e. unperforated) sheet material into its frusto-conical form. In embodiments the surface of the cathode may be patterned or textured, for example by sandblasting, to increase the surface area for reaction. Advantageously, increasing the surface area for reaction increases the hydrogen production efficiency of the cathode. In embodiments, the frusto-conical cathode has a thickness : lower inner diameter: upper inner diameter ratio of 1 mm : 24 mm : 48 mm. In embodiments, the cathode may have a length from the opening to the base of the frusto-conical shape. The length may be between 4 to 10cm, e.g. 5 to 7cm, e.g. 5.7cm. In embodiments, the opening of the frusto-conical cathode may be from 2 to 10cm in diameter, e.g. 5cm. In embodiments, the base of the frusto-conical cathode may be from 1 to 5cm in diameter, e.g. 2.5cm. The Uppermost inner diameter of the second electrode may be from 35 to 65 mm, say from 40 to 50 mm, for example 48mm, The lowermost inner diameter of the second electrode may be from 15 to 35, say from 20 to 30 mm, for example 24mm. The , the thickness of the second electrode may be from 0.5 to 2mm thick, for example 1 mm. The lowermost part of the second electrode may be fitted with a conductive member, for example a washer, for example a stainless steel washer. The conductive member may be mounted in place by a bolt and nut (or other conductive connection means), e.g. a 6mm threaded bolt and nut. The nut may provide the connection point for the power source. In embodiments, the housing may have a height from the upper edge to the base, in use. The height may be at least three times the height of the mesh. Advantageously, this allows precipitation of any steam residue so that there is less moisture in the gas phase. In embodiments, the housing may be cylindrical or cuboidal (including of rectangular cross section). In embodiments, the housing may comprise an opening. In embodiments, the opening may be circular. The opening may have a maximum transverse dimension, e.g. a diameter, of from 5 to 10cm, e.g. 7.0cm. In embodiments, the housing may have a thickness. In embodiments, the thickness of the housing may be from 1.0 mm - 5.0 mm, e.g. 3.0 mm. In embodiments, the operating temperature of the apparatus may be from 40°C to 60°C e.g. 45°C to 55°C. Advantageously, the specific geometry provided by the configuration and shape of the first and second electrodes contained within the housing of the apparatus provides the conditions for more efficient hydrogen generation from water. Without wishing to be bound by theory, the inventors believe that the combination of the first, e.g. mesh, electrode surrounding the frusto-conical shape of the second electrode provides an advantageous acoustical output, leading to more efficient hydrogen generation via sonification. In embodiments, one or both of the electrodes may be suspended within the housing. In embodiments, one or both of the electrodes may be suspended within and / or secured to the housing. In embodiments, the apparatus may comprise a means to suspend and / or secure one or both electrodes to the housing. In embodiments, the means may be or comprise a bolt. In embodiments, a first bolt may secure the first electrode to the housing. In embodiments, a second bolt may secure the second electrode to the housing. In embodiments, the housing may comprise one or more opening(s) for receiving means to suspend and / or secure the first and / or second electrode to the housing, e.g. using one or more bolts. In embodiments, the opening(s) may be located at the base of the housing, in use. In embodiments, the housing may comprise a first opening for securing the first electrode to the housing. In embodiments, the housing may comprise a second opening for securing the second electrode to the housing. In embodiments, the one or more opening(s) may have a diameter from 0.5 to 1.5cm, e.g. 0.6cm. In embodiments, the electrodes, e.g. the anode and / or cathode, of the housing may be electrically connected to a source of electricity, wherein the electrical connection is configured to energise the electrodes and thereby generate hydrogen. In embodiments, the electrical connection may be provided by the means to suspend and / or secure one or both electrodes to the housing, e.g. one or more bolts. In embodiments, AC power may be used. In embodiments, DC power may be used. In embodiments, the apparatus may comprise plural housings wherein each housing contains a first electrode and a second electrode for submersion within water located within the housing, the first electrode surrounding the second electrode, wherein the first electrode is of cylindrical form and the second electrode is of frusto-conical form, wherein the first electrode is a anode and the second electrode is a cathode, and the housing is fabricated from glass. In embodiments, the apparatus may further comprise a tank. In embodiments, one or plural housing(s) may be located within the tank. In embodiments, the tank may comprise an inlet for receipt of water, e.g. pure or deionised water and / or potable water. In embodiments, the tank may comprise an outlet for generated hydrogen. In embodiments, the apparatus may comprise a means for desalinating sea water, e.g. via reverse osmosis or evaporation, to produce fresh or pure or deionised water for use generating hydrogen. In embodiments, the apparatus may comprise a means for irradiating water, with a magnetic field prior to the water, contacting the electrodes. Advantageously, irradiating water with a magnetic field prior to the water contacting the electrodes improves the efficiency of dissociation of the water molecules into hydrogen and oxygen, as less energy is required to overcome the activation energy. In embodiments, the apparatus may comprise a means for providing ultrasonic energy to the water located within the housing, e.g. an ultrasonic generator. In embodiments, the means for providing ultrasonic energy may be or comprise an ultrasonic horn, an ultrasonic probe, and / or one or more piezoelectric transducers. However, we have found that a separate means for providing ultrasonic energy may not be required as ultrasonic energy may be generated by energising the electrodes, thereby causing vibrations within one or other of the electrodes to generate ultrasonic vibration. Advantageously, ultrasonic energy provides acoustic vibrations to the water, which, we believe, increase the conversion efficiency of water to hydrogen. Without wishing to be bound by theory, the inventors believe this is because the ultrasonic vibrations cause microbubbles to grow and rapidly collapse, causing shock and extremely high bubble temperatures. The energy caused by the cavitation is believed to be sufficient to break the bonds between the hydrogen and oxygen molecules in the water. This increases the rate of reaction. A further aspect of the invention provides a combination of an internal combustion engine and a reactor as set out able, at least a portion of the gaseous output from the reactor being fed to the engine. A further aspect of the invention provides a method for generating hydrogen from water, e.g. fresh or pure or deionised water, the method comprising providing an apparatus according to the invention, submerging the first and second electrode in water, e.g. fresh or pure or deionised water, and energising the first and second electrode to generate hydrogen. In embodiments, the method may comprise irradiating water, with a magnetic field prior to the water contacting the electrodes. Advantageously, irradiating water with a magnetic field prior to the water contacting the electrodes improves the efficiency of dissociation of the water molecules into hydrogen and oxygen, as less energy is required to overcome the activation energy. Advantageously, the method does not require the use of an electrolyte to generate hydrogen, although a small amount of electrolyte (e.g. up to 1 w / w%) may be added. In embodiments, the method may be performed at neutral, or near neutral, pH (e.g. pH 7). Advantageously, the apparatus is able to produce hydrogen from water without addition of a electrolyte and / or without the use of a catalyst. Advantageously, the apparatus and method according to the invention provide for an increased rate of hydrogen generation from the electrolysis of water, as well as improved efficiency. This provides a clean and green process for generating hydrogen. More advantageously, the electrodes may be fabricated from inexpensive materials, e.g. stainless steel, which are more cost effective than other electrode materials that have been used in the prior art. Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in any way and / or combination, unless such features are incompatible. For the avoidance of doubt, the terms “may”, “and / or”, “e.g.”, “for example” and any similar term as used herein should be interpreted as non-limiting such that any feature so-described need not be present. Indeed, any combination of optional features is expressly envisaged without departing from the scope of the invention, whether or not these are expressly claimed. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner. It will be further appreciated that the terms top, bottom, right, left and so on are intended to provide indications of relative spatial positions and are not intended to provide a strict limitation with respect to spatial orientation. Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is diagram of an apparatus comprising a housing according to the invention; Figure 2 is an apparatus comprising plural housings according to the invention; Figure 3A is a diagram of a second apparatus according to the invention; Figure 3B is a diagram of the internal components of the second apparatus; Figure 3C is a sectional view of Figure 3B; and Figure 3D provides further details of some of the components of the second apparatus. Referring now to Figure 1, there is shown an apparatus 1 for generating hydrogen, according to the invention. The apparatus 1 comprises a housing 10, a first electrode 11, a second electrode 12, a first electrical connection 13, and a second electrical connection 14. The housing 11 further comprises a first and second opening 15, 16 for receiving the first and second electrical connection 13, 14 respectively. In this embodiment, the first electrode 11 is the anode and the second electrode 12 is the cathode. The first electrical connection 13 is connected to the first electrode 11 and the second electrical connection 14 is connected to the second electrode 12. The first electrode 11 and the second electrode 12 are located within the housing 10. In use, the housing 10 contains a fluid F, e.g. fresh or pure or deionised water, and the electrodes 11,12 are submerged within the water F. The first and second electrical connection 13, 14 are each provided as a bolt. The bolts 13, 14 enable the first and second electrodes 11, 12 to be suspended within, and secured to, the housing 11 respectively. The first electrode 11 is in cylindrical form and the second electrode 12 is of frusto-conical form. It is shown that the first electrode 11 surrounds the second electrode 12. In other words, the frusto-conical shape of the second electrode 12 is located within the cylindrical form of the first electrode 11. In this embodiment, the first electrode 11 is fabricated from a mesh made from stainless steel, e.g. 316L stainless steel. In this embodiment, the second electrode 12 is fabricated from a sheet of stainless steel, e.g. 316L stainless steel. The mesh is 60 US mesh size. The housing 10 is fabricated from glass. In this embodiment, the glass is heat tempered glass. In this embodiment, the housing 10 has a height H of 18.5cm and a diameter D of 7.5 cm. The second electrode 12 has a length L of 5.7cm. The diameter D1 of the base B of the second electrode 12 is 2.5 cm, and the diameter D2 of the opening O of the second electrode 12 is 5 cm. The openings 15, 16 each have a diameter of 0.6 cm. In use, the housing 10 is filled with a fluid F, e.g. fresh or pure or deionised water. The first and second electrical connections 13,14 are connected to a source of electricity to energise the electrodes 11, 12. The water, is split to produce hydrogen gas (not shown), primarily by the energy caused by cavitation and secondarily by electrochemical splitting. Advantageously, the use of fresh or pure or deionised water means that an electrolyte is not required for the generation of hydrogen. More advantageously, the specific geometry provided by the configuration and shape of the first and second electrodes contained within the housing of the apparatus provides the conditions for more efficient hydrogen generation from water. Without wishing to be bound by theory, the inventors believe that the combination of the first, e.g. mesh, electrode surrounding the frusto-conical shape of the second electrode means that when the electrodes are energised, ultrasonic vibrations are generated. This causes microbubbles to grow and rapidly collapse, causing shock and extremely high bubble temperatures. The energy caused by the cavitation breaks the bonds between the hydrogen and oxygen molecules in the water to produce hydrogen gas. Referring now to Figure 2, there is shown an apparatus 2 according to a second embodiment of the invention. The apparatus 2 comprises a tank 21, a water inlet 22, and a hydrogen outlet 23. In this embodiment, plural housings 10 are located within the tank 21. Each housing 10 contains a first electrode 11, a second electrode 12, a first electrical connection 13, and a second electrical connection 14, according to the housing 10 of the apparatus 1 shown in Figure 1. In this embodiment, the first electrode 11 is the anode and the second electrode 12 is the cathode. In the apparatus 2, eight housings 10 are shown, but more or less housings 10 may be present. In use, water, e.g. fresh or pure or deionised water, is supplied to the tank 21 via the water inlet 22. The first and second electrical connections 13, 14 of each housing 10 are connected to a source of electricity to energise the electrodes 11, 12. The electrochemical splitting of the water occurs to produce hydrogen gas (not shown). The hydrogen is removed from the apparatus 2 via the hydrogen outlet 23. The hydrogen may be piped to a scrubber (not shown) to remove contaminants. Referring now to Figure 3A, there is shown a diagram of a second apparatus 3 according to a third embodiment of the invention. The apparatus 3 comprises a tank 30 with a lid 31 and a base 32. The tank 30, including the lid 31 and the base 32, are fabricated from stainless steel. In an exemplary embodiment, the tank 30 has a height H of 24 cm extending between the base 32 and the lid 31. The lid 31 has a length L of 36 cm and a width Wof 18 cm. The base 32 has a length L’ of 30 cm and a width W which is less than the width W of the lid 31. A plurality of apertures A are provided which extend through the lid 31. The apertures A are positioned around the periphery of the lid, overhanging the tank 30. Three threaded bolts TB extend through the lid 31 into the tank 30. Referring now to Figure 3B, there is shown a diagram of some of the internal components of the second apparatus. Like components are denotated by the same references as in Figure 3A. Each threaded bolt TB extending through the lid 31 of the tank 30, secures an internally-threaded circular lid 33 to the internal surface of the lid 31 (i.e. the surface facing the base 32). The lids 33 are also secured in place by a layer of silicon adhesive between the base of each lid 33 and the internal surface of the lid 31 of the tank 30. Positioned directly opposite each lid 33 and bolted to the base of the tank 32 are three electrodes 112. The electrodes 112 are of conical form. In this embodiment, these three electrodes 112 are cathodes. Figure 3C, shows a sectional view of Figure 3B with more of the internal components of the second apparatus 3 shown. Figure 3D shows details of some of the components of the second apparatus. Referring to Figures 3C and 3D, the second apparatus 3 comprises three first electrodes 111 of cylindrical form. Each of the first electrodes 111 surround one of the conical electrodes 112, to form three working electrode pairs, positioned within the tank 30. In this embodiment, each first electrode 111 is an anode and each second electrode 112 is a cathode, Each individual electrode is electrically connected to an electrical connection (not shown) which extend through openings in the tank 30. These electrical connections are provided via stainless steel bolts which extend through the base 32 of the tank 30, allowing the first 111 and second electrodes 112 to be suspended within, and secured to, the tank 30 respectively. In use, the tank 30 contains a fluid F e.g. fresh or pure or deionised water and the electrodes 111, 112 are submerged within the fluid F. This fluid is introduced into the tank 30 via an inlet (not shown). The first electrodes 111 are in cylindrical form and the second electrodes 112 are in frusto-conical form. It is shown that a first electrode 111 surrounds each of the second electrodes 112. In other words, the frusto-conical shape of each of the second electrodes 112 is located within the cylindrical form of one of the first electrodes 111. In this embodiment, a glass cylinder 35 is received in each of the circular threaded lids 33, secured to the tank lid 31. Each glass cylinder 35 partially surrounds each of the second electrodes 112, and is partially surrounded by one of the first electrodes 111, such that the distance between the lid 33 and the top of the second electrode 112 is 18 cm. In this embodiment, the glass is heat tempered glass. In this embodiment, the first electrodes 111 are fabricated from a mesh made from stainless steel, e.g. 216L stainless steel. In this embodiment, the second electrodes 112 are fabricated from a sheet of stainless steel, e.g. 316L stainless steel. The mesh is 60 US mesh size. In this embodiment, the first electrodes 111 have a length L1 of 7 cm. The second electrodes 112 have a length L2 of 5.7 cm. The diameter D1’ of the base B’ of the second electrodes 112 are 2.5 cm, and the diameter D2’ of the opening O’ of the second electrodes 112 are 5 cm. The openings in the stainless steel bolts which extend through the base of the 32 of the tank 30 each have a diameter of 0.6 cm. The out put from the reactors of the invention ( / .e. the generated gas) can be added to an internal combustion engine. We believe that the gaseous output of the reactor can be used to reduce fuel consumption of an IC engine. Advantageously the gas can be added to the engine without further treatment. Advantageously, the apparatus and method according to the invention provide for an increased rate of hydrogen generation from the electrolysis of water, as well as improved efficiency. This provides a clean and green process for generating hydrogen. More advantageously, the electrodes may be fabricated from inexpensive materials, e.g. 5 stainless steel, which are more cost effective than other electrode materials that have been used in the prior art. It will be appreciated by those skilled in the art that several variations to the aforementioned embodiments are envisaged without departing from the scope of the invention. 10 It will also be appreciated by those skilled in the art that any number of combinations of the aforementioned features and / or those shown in the appended drawings provide clear advantages over the prior art and are therefore within the scope of the invention described herein.

Claims

1. An apparatus for generating hydrogen, the apparatus comprising a housing containing a first electrode and a second electrode, each of the first and second electrode being for submersion within water located within the housing, the first electrode surrounding the second electrode, wherein the first electrode is of cylindrical form and the second electrode is of at least part-conical or frusto-conical form, wherein the first electrode is preferably an anode and the second electrode is preferably a cathode.

2. Apparatus according to Claim 1, wherein either the housing is fabricated from or comprises glass or a glass body is provided within the housing, or both.

3. Apparatus according to Claim 2, wherein the glass is selected from borosilicate glass and heat tempered glass.

4. Apparatus according to Claim 1, 2 or 3, wherein the housing is of cylindrical or cuboidal form.

5. Apparatus according to any preceding Claims, wherein the housing has a lowermost portion and an uppermost portion and the distance between the lowermost portion and uppermost portion is at least three times greater than the height of the anode.

6. Apparatus according to any preceding Claim, wherein the anode is fabricated from a metal, for example stainless steel, e.g. 316L stainless steel which metal may be coated with a protective coating.

7. Apparatus according to any preceding Claim, wherein the anode comprises a mesh material, and wherein the mesh material may be an unwelded mesh and / or with a mesh size of from 20 to 100 US Mesh, preferably from 40 to 60 US mesh.

8. Apparatus according to any preceding Claim, wherein the cathode is formed from or comprises (e.g. coated with) one or more metals selected from rhenium,ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, copper and gold, preferably selected from copper, silver, gold or platinum.

9. Apparatus according to any preceding Claim, wherein the cathode is formed of stainless steel and coated with a second metal.

10. Apparatus according to any preceding Claim, wherein the cathode is fabricated from a solid (i.e. unperforated) sheet material.

11. Apparatus according to any preceding Claim, wherein the surface of the cathode is patterned or textured.

12. Apparatus according to any preceding Claim, wherein the anode and the cathode are retained away from the walls of the housing.

13. Apparatus according to any preceding Claim, further comprising leads to connect the anode and cathode to a source of electricity, and wherein said leads extend through the housing.

14. A plant for generating hydrogen, the plant comprising one of more sets of apparatus according to any preceding Claim.

15. A plant according to Claim 13, comprising a tank, said one or more sets of apparatus being located within the tank.

16. A plant according to Claim 14 or 15, further comprising means to introduce water in to the tank.

17. A plant according to any of Claims 14, 15 or 16, further comprising means for extracting hydrogen from the tank.

18. A plant according to any of Claims 14 to 17, further comprising a source of electrical power and means to connect the anode and cathode of the or each of said one or more sets of apparatus to the source of electrical power.

19. A combination of an internal combustion engine and apparatus according to any one of Claims 1 to 13, the internal combustion engine and the apparatus being in fluid communication.5 20. A method of generating hydrogen from water, e.g. fresh or pure or deionised water,the method comprising providing an apparatus according to any of Claims 1 to 12, submerging the first and second electrode in water, water, and connecting the first and second electrode to a source of electricity to generate hydrogen.io 21. A method according to Claim 19, further comprising adding up to 1 w / w% of electrolyte to the water.

22. A method according to Claim 19 or 20 the method comprising one or more of operating the apparatus within a temperature range of 30 to 70°C, say 40 to 60°C is and ensuring the water is at neutral, or near neutral, pH (e.g. pH 6 to 8).

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