A hydrogen storage system and method of use

Abstract

A hydrogen storage system 10 for producing, storing, releasing and utilising hydrogen, the system comprising: an electrolyser 12; a hydrogen storage bed 14 comprising a hydrogen storage material disposed therein; and a fuel cell 16. When the system assumes a loading condition, hydrogen is produced by the electrolyzer and loaded into the hydrogen storage bed. When the system assumes an unloading condition hydrogen stored in the H2 storage bed is unloaded and directed towards the fuel cell for producing electricity. A filter may be located between the storage bed and electrolyser, or between the storage bed and fuel cell. The storage bed material may comprise a hydridable metal, optionally depleted uranium. The storage bed may comprise a hydrogen storage body and a thermal transfer element comprising a fin element, e.g. a helical fin, that may allow the redistribution and expansion of the hydrogen storage material within the body.

Description

Field of the Invention

[0001] The present invention is directed towards a hydrogen storage system for producing, storing, releasing and utilising hydrogen. The present invention is also directed towards a method of using said hydrogen storage system. Background of the Invention

[0002] Increasingly, countries are trying to move away from using fossil fuels as a source of energy. Therefore, there is the need for alternative energy sources. Hydrogen is widely considered to be a promising source of sustainable energy as hydrogen has a relatively high density of energy per unit mass and can be produced without the need for fossil fuels.

[0003] Hydrogen has a low volumetric energy density, as such, one of the barriers to using hydrogen as a sustainable energy source is that of efficient storage. Furthermore, hydrogen production, storage and utilisation are usually performed as separate steps in separate systems. Therefore, hydrogen transport is often required. Consequently, as hydrogen develops as an energy commodity, there is industrial and governmental interest in developing methods for the efficient production, transport, storage, and utilisation of hydrogen.

[0004] Hydrogen is conventionally stored as either a compressed gas under higher pressure or as a cryogenic liquid. Neither of these storage solutions are currently conducive to large-scale application due to safety and efficiency issues: liquid hydrogen storage is costly and requires low storage temperatures; compressed hydrogen gas requires large storage tanks able to withhold significant internal pressure.

[0005] Hydrogen can also be stored in the solid-state, for example in metal hydride hydrogen storage reactors. However, there are still numerous technical problems with currently available metal hydride storage reactors. Currently available metal hydride storage reactors are relatively small scale and not suitable for storing large amounts of hydrogen to be useful as a sustainable energy source. Previous attempts to scale up currently available metal hydride storage reactors have been unsuccessful, primarily due to the difficulties in managing the heat flow into and out of the storage reactors required for loading and unloading of hydrogen, and the volumetric expansion of material in the reactor (hydrogen storage material) on uptake of hydrogen. Regarding management of heat flow, for example, metal hydrides often have extremely poor effective thermal conductivity, and this poor thermal conductivity means the heat released by the exothermic hydrogenation reaction, during the process of hydrogen storage, cannot be transferred or removed from the system in a timely and effective manner. This causes the internal temperature of the storage reactor to sharply rise over a short period of time, resulting in a sharp pressure increase, and a reduced or even non-existent hydrogen uptake rate. As a reactive material inside a hydrogen storage reactor takes up hydrogen, the hydride material (for example, the metal hydride) takes up significantly more volume than the precursor material. This volumetric expansion, if not well accommodated, can lead to structural weakness within the storage reactor. The volumetric expansion may also lead to increased material compression and stress generation within the storage reactor. This could result in internal deformation and / or bulging of the storage reactor. These issues are discussed in Kawamura (1982) and Masahiko (2012). The technical problems become increasingly difficult to address as the mass and size of the storage reactors increase. Conventional hydrogen storage systems, and their volumetric capacities can be found in Penzhorn (1990), Shmayda (2021) and Banos (2022). An overview of hydrogen storage technologies, and in particular, metal hydride hydrogen storage can be found in Yartys and Lototsky (2004). Safety concerns and boil-off issues of compressed and liquid hydrogen storage are discussed in Meng (2006), and Ramin and Growth (2019).

[0006] Whilst there are numerous different physical and chemical methods for storing hydrogen, there is the desire to develop a storage solution that is cost effective, safe, sustainable, reliable and has a relatively small footprint. Summary of the Invention

[0007] The present inventors have realised that a single hydrogen storage system where hydrogen is produced, stored, released, and utilised is warranted and desired. Furthermore, the inventors have identified that to enable hydrogen production, storage, and utilisation to be widely developed, the hydrogen storage system needs to be applicable on an industrial scale. The present inventors have found that a hydrogen storage bed described herein can store much larger quantities of hydrogen than has been provided for in previous hydrogen storage beds, and the hydrogen storage system described herein can be used to produce, store and use hydrogen on a much larger scale than has been achieved previously. The industrial scale quantity of hydrogen storage presents unique problems. These problems include: a) hydrogen storage material particulate contamination and release to the environment; b) handling of potentially pyrophoric substances such as metal / metal hydrides powders; c) handling of hydrogen in large quantities and d) scaling existing hydrogen storage systems. The present invention aims to address these challenges.

[0008] The present inventors have also identified that a desirable hydrogen storage system needs to: (1) accommodate a relatively large amount of hydrogen storage material such that it can operate on an industrially applicable scale; (2) be able to safely accommodate a full cycle of hydriding and dehydriding of the hydrogen storage material; (3) adequately protect any reactive hydrogen storage material inside the hydrogen storage system from degradation and environmental contamination, and therefore a reduced storage capacity of the hydrogen storage system; (4) effectively manage heat flow to enable efficient loading and unloading of hydrogen; (5) allow for safe operation during loading and unloading of the storage material; and (6) provide sufficient protection from hydrogen storage material contamination for the surrounding environment. These considerations are particularly important for industrial application of a hydrogen storage system.

[0009] In a first aspect, the invention provides a hydrogen storage system for producing, storing, releasing and utilising hydrogen, the hydrogen storage system comprising: an electrolyser; a hydrogen storage bed having a hydrogen storage material disposed therein; and a fuel cell; wherein the hydrogen storage system is configured to assume a loading condition and an unloading condition, wherein in the loading condition, hydrogen is produced by the electrolyser and loaded into the hydrogen storage bed by the hydrogen storage material, and wherein in the unloading condition, said hydrogen stored in the hydrogen storage bed is unloaded from the hydrogen storage bed and directed towards the fuel cell for use producing electricity.

[0010] The present inventors have surprisingly found that use of a hydrogen storage system according to the present invention is advantageous. The present inventors found that the provision of a hydrogen storage system with an electrolyser, fuel cell and a hydrogen storage bed allows for a full cycle of producing, storing and releasing hydrogen to be accommodated within a unitary system. The hydrogen produced by the electrolyser is the hydrogen loaded into the hydrogen storage beds during the loading condition, and subsequently unloaded from the hydrogen storage beds during the unloading condition for use by the fuel cell. The electrolyser, hydrogen storage bed and fuel cell are configured to be in fluid communication with one another, but are separable from one another (for example separable by valves). The components are interconnected by a series of pipes and valves. The hydrogen storage system described herein can accommodate a relatively large amount of hydrogen storage material such that it can operate on an industrially applicable scale, whilst adequately protecting the hydrogen storage material disposed therein from degradation and environmental contamination. The hydrogen storage system is modular and allows for the inclusion of a number of hydrogen storage beds. The present inventors found that hydrogen can be safely loaded and unloaded from the storage material using the claimed hydrogen storage system. Therefore, advantageously, the hydrogen storage system can be safely adapted to allow for different capacities of hydrogen to be stored.

[0011] The inventors have surprisingly found that the arrangement of the present invention allows for a non-linear increase in the footprint the hydrogen storage system. This is advantageous as it increases the efficiency of the hydrogen storage system. The modularity of the present invention allows for the hydrogen storage system to be scaled up, including in parallel, and for the hydrogen storage system to be able to accommodate for energy storage capacity increase. The present inventors have surprisingly found that the hydrogen storage system described herein can be used to deliver large quantities of hydrogen as a sustainable energy source. In particular, due to the configuration of the hydrogen storage bed system it has been found it is possible to efficiently load and unload hydrogen within the system.

[0012] Examples of hydrogen storage materials that may be used within the hydrogen storage system include magnesium; magnesium alloys; lanthanum pentanickel (LaNis); lanthanum alloys; zirconium cobolt (ZrCo); zirconium nickel (ZrNi); lithium; titanium; thorium; uranium, and rare earth elements.

[0013] In embodiments, the hydrogen storage system may further comprise at least one filter positioned between the hydrogen storage bed and the electrolyser. In embodiments, the hydrogen storage system may further comprise at least one filter positioned between the hydrogen storage bed and the fuel cell.

[0014] Hydrogen storage materials may break into micron and submicron sized particles after successive hydriding-dehydriding cycles. The small particles may be highly mobile and may migrate out of the hydrogen storage bed and into a gas loop of the hydrogen storage system if effective filtering is not in place.

[0015] The at least one filter may be an in-line filter. The use of at least one in-line filter ensures there is no unwanted migration of small particles of hydrogen storage material into certain loops of the hydrogen storage system. The least one in-line filter may be used alongside in-bed filters. The inclusion of both in-line and in-bed filters may be beneficial to ensure the migration of particles is mitigated.

[0016] The pore size of filters may affect the gas line conductance within the hydrogen storage system and the rate of unloading / loading of hydrogen. As such, the pore size may be determined on a case-by-case basis.

[0017] In embodiments, the hydrogen storage system may further comprise a buffer vessel positioned between the electrolyser and hydrogen bed and / or positioned between the hydrogen storage bed and the fuel cell. In embodiments, the hydrogen produced by the electrolyser may be stored in the buffer vessel prior to loading the hydrogen storage bed.

[0018] During loading, a buffer vessel ensures that there is sufficient supply of hydrogen to the hydrogen storage beds. During unloading, a buffer vessel allows for gas pressure relief into a larger volume. Providing for gas pressure relief reduces the risk of component failure within the hydrogen storage system due to pressure and / or temperature build up while improving the overall kinetics of the hydrogen storage system. In embodiments, the hydrogen storage system may comprise a low-pressure buffer vessel and a high-pressure buffer vessel. A low-pressure buffer vessel may beneficially be used as an expansion volume to allow for the gas to cool down to room temperature during unloading, for example, hydrogen may be unloaded at a pressure in the range of about 0.01 MPa to about 0.4 MPa. The high-pressure volume may advantageously prepare the gas for loading, or for use by the fuel cell, for example, the hydrogen may be pressurised in the range of about 2 MPa to about 6MPa. The buffer vessel configuration provides a delay between the electrolyser and hydrogen storage beds, as well as between the hydrogen storage beds and fuel cell, which ensures the safe operation of the hydrogen storage system.

[0019] In embodiments, the hydrogen storage system may further comprise a gas purification system arranged downstream of the electrolyser and prior to the hydrogen storage bed.

[0020] The purity of gas produced by the electrolyser, entering the hydrogen storage system effects the operational lifetime of the hydrogen storage system, as the purity effects the degradation of the hydrogen storage material over time. Higher purity gas results in a reduced rate of degradation, and a higher operational lifetime of the hydrogen storage system.

[0021] In embodiments, the hydrogen storage bed material comprises a hydridable metal, i.e., a metal that can form a metal hydride, optionally wherein the hydridable metal is a depleted uranium. The hydrogen storage bed material may comprise a hydridable metal alloy in some embodiments.

[0022] An advantage of employing depleted uranium as a hydrogen storage material is that a nuclear waste material may be made use of in the supply of a sustainable energy source.

[0023] The present inventors have surprisingly found that depleted uranium can be successfully used as a hydrogen storage material within the hydrogen storage system described herein. Depleted uranium has previously been used in the fusion energy sector at a relatively small scale for storing deuterium and tritium - the heavy isotopes of hydrogen. If hydrogen is stored as uranium trihydride (UHa) using depleted uranium, the storage capacity per volume of depleted uranium in its polycrystalline form is about 2.1 times that of hydrogen in its liquid form. Practically, this means that depleted uranium can store more than twice as much hydrogen for the same volume as that of hydrogen when stored as liquid under cryogenic conditions. Furthermore, the use of an otherwise waste material is advantageous from a sustainability point of view, as depleted uranium is a waste material that is somewhat difficult to dispose of. However, there are difficulties in handling depleted uranium, such as the volumetric expansion during conditioning and phase transformations, as well as the thermal and pressure management during hydrogen absorption and desorption. Previously, only relatively small amounts of depleted uranium have been able to be safely incorporated within a hydrogen storage system. Therefore, the inventors realised the need to increase the range of applications of a hydrogen storage system and to improve loading and unloading kinetics. The present invention overcomes many of the problems associated with the handling of depleted uranium. The invention also provides the necessary safety and contamination controls required for handling depleted uranium. Therefore, the present inventors have found that much larger quantities of depleted uranium can be safely stored in the present hydrogen storage system described herein than in previous systems. For example, at least about 250 kg of depleted uranium can be utilised in the hydrogen storage system described herein. For example, at least about 3.25 kg of hydrogen may be stored by the hydrogen storage system described herein.

[0024] In embodiments, the hydrogen storage system comprises a plurality of hydrogen storage beds.

[0025] The provision of more than one hydrogen storage bed allows the energy storage capacity of the hydrogen storage system to be increased in a modular manner. Advantageously, the hydrogen storage beds will be isolatable from one another. This will provide for more efficient maintenance of the hydrogen storage system. It also allows for the energy storage capacity of the hydrogen storage system to be modified on a case-by-case basis, such that it can be customised to particular energy storage needs.

[0026] In embodiments, the plurality of hydrogen storage beds is arranged in parallel.

[0027] Arrangement of the hydrogen storage beds in parallel may allow for more efficient maintenance of the hydrogen storage system. A parallel configuration provides an efficient way of isolating the hydrogen storage beds within the hydrogen storage system from one another.

[0028] In embodiments, the hydrogen storage bed comprises: a hydrogen storage body; and a thermal transfer element comprising a fin element configured to allow the redistribution and expansion of the hydrogen storage material within the hydrogen storage body during hydrogen loading and unloading of the hydrogen storage material.

[0029] The present inventors have surprisingly found that the use of hydrogen storage bed having a thermal transfer element according to the present invention is advantageous. The present inventors found that by providing a hydrogen storage bed comprising a thermal transfer element arranged within a hydrogen storage body as described herein, the thermal transfer element comprising at least one fin element configured to allow the redistribution and expansion of a hydrogen storage material within the hydrogen storage body during hydrogen loading and unloading of the hydrogen storage material, allows for redistribution of the hydrogen storage material within the hydrogen storage body during expansion of the hydrogen storage material on uptake of hydrogen while also providing efficient transfer of thermal energy to and from the hydrogen storage material. Therefore, the hydrogen storage bed described herein provides for improved storage of hydrogen. The hydrogen storage bed described herein can store greater amounts of hydrogen than the prior art while also avoiding localised strain build up against the hydrogen storage body due to the volumetric expansion upon hydriding of a hydrogen storage material as well as providing for efficient transfer of thermal energy as required during hydriding and dehydriding of the hydrogen storage material.

[0030] Deformation of a hydrogen storage body is a problem that has been observed for hydrogen storage beds that provide for strict compartmentalization of hydrogen storage material. Deformation has also been observed for hydrogen storage beds where the hydrogen storage material was initially loaded unevenly between two adjacent compartments. The present inventors surprisingly found that the provision of a thermal transfer element according to the present invention alleviates these problems by allowing for redistribution of the hydrogen storage material during hydriding and dehydriding without deforming the hydrogen storage body.

[0031] Furthermore, the present inventors surprisingly found that the invention allows for much larger amounts of hydrogen storage material to be utilised than previously shown. For example, the present inventors have found that the hydrogen storage beds described herein can store at least 10 times the amount of hydrogen compared to existing hydrogen storage beds. This is beneficial as it may increase the energy storage capacity of the hydrogen storage system. The hydrogen storage bed and methods described herein may also provide benefits in relation to improving the efficiency and reducing the production costs of the storage of hydrogen, mitigating health and safety issues when using expensive, rare, toxic or even radioactive hydrogen storage materials. As such, the use of such a hydrogen storage bed within the hydrogen storage system is beneficial.

[0032] The present inventors have identified that not only have hydrogen storage beds of the prior art been difficult or impossible to provide at larger scale, but also that there are problems associated with releasing hydrogen quickly enough to be useful as a sustainable energy source. Therefore, the present inventors have identified that as well as providing a hydrogen storage bed which can accommodate increased volumes of hydrogen compared to existing hydrogen storage beds, it is desirable to provide an improved hydrogen storage bed which is able to transfer thermal energy quickly and efficiently to allow hydrogen to be released from a hydrogen storage material as quickly as possible. The present inventors have surprisingly found that the hydrogen storage bed described herein can be used to deliver large quantities of hydrogen as a sustainable energy source. In particular, due to the configuration of the hydrogen storage bed described herein allowing for redistribution and expansion of a hydrogen storage material within the hydrogen storage body during hydrogen loading and unloading of the hydrogen storage material, it has been found to be possible to provide thermal energy to the hydrogen storage material in the hydrogen storage bed efficiently in order that hydrogen may be efficiently (and quickly) unloaded from the hydrogen storage material.

[0033] In embodiments, the fin element comprises a single fin element. The fin element may extend along the longitudinal extent of the thermal transfer element in a continuous manner. Alternatively, a plurality of fin elements may be used in a continuous or discontinuous manner. The fin element(s) may be shaped to allow for the redistribution and expansion of a hydrogen storage material within the hydrogen storage body during hydrogen loading and unloading of the hydrogen storage material.

[0034] In embodiments, the fin element is a helical fin element, i.e., the fin element has a helical shape and is arranged along the thermal transfer element in a helical manner. The present inventors have found that providing a thermal transfer element with a helical fin element is advantageous in accommodating volumetric expansion of a hydrogen storage material while also providing for efficient thermal transfer.

[0035] In embodiments, the helical fin element has a helix angle in the range of about 1° to about 80°, for example in the range of about 2° to about 70°, about 1° to about 60°, about 5° to about 50°, about 10° to about 40°, about 10° to about 30°, about 10° to about 25°, about 15° to about 25°, or in the range of about 20° to about 30°. The helix angle is measured from the normal to the axis of the thermal transfer element.

[0036] In embodiments, the fin element of the thermal transfer element is a continuous solid helical fin element. Alternatively, a plurality of fin elements may be used in a continuous or discontinuous manner. The fin element(s) may be shaped to allow for the redistribution and expansion of a hydrogen storage material within the hydrogen storage body during hydrogen loading and unloading of the hydrogen storage material.

[0037] In embodiments, the fin element is formed from a thermally conductive material, for example a material exhibiting excellent thermal conductivity. The specifical material employed for the fin element is not particularly limited. Examples of suitable materials for construction of the fin element include copper and copper alloys. However, other thermally conducting material may be used, such as many different metals including titanium and palladium.

[0038] In embodiments, the fin element may be arranged in a non-helical manner.

[0039] In embodiments, the thermal transfer element is removable from the hydrogen storage body.

[0040] In embodiments, the hydrogen storage body has an internal diameter, and the thermal transfer member has an outer most diameter, and the outer most diameter of the thermal transfer element is at least about 80% of the internal diameter of the hydrogen storage body, for example at least about 85%, at least about 90%, at least about 95%, or at least about 98% of the internal diameter of the hydrogen storage body. In some embodiments, the outer most diameter of the thermal transfer element is in the range of about 80% to about 100% of the internal diameter of the hydrogen storage body, for example in the range of about 90% to about 100% of the internal diameter of the hydrogen storage body.

[0041] In embodiments, the thermal transfer element may be fixable or fixed relative to the hydrogen storage body.

[0042] In some embodiments, the outer most diameter of the thermal transfer element being less than the internal diameter of the hydrogen storage body has been found to be useful to provide a volumetric expansion region between the thermal transfer element and the hydrogen storage body. In some embodiments, the provision of such a volumetric expansion region is not required. For example, in some embodiments, the thermal transfer member may contact, for example directly contact, the inner wall of the hydrogen storage body. The diameter of the hydrogen storage body may be tailored to the desired hydrogen storage material being used in the hydrogen storage bed. The outer most diameter of the thermal transfer element may also be tailored relative to the diameter of the hydrogen storage body. The outer most diameter of the thermal transfer element may also be tailored relative to the desired hydrogen storage material being used in the hydrogen storage bed.

[0043] The present inventors have found that the provision of a thermal transfer element as described herein allows for the prevention of pressure build up that can result from volumetric expansion of the hydrogen storage material upon hydriding. The thermal transfer element may also facilitate the redistribution of hydrogen storage material throughout the hydrogen storage body on hydriding and dehydriding of the hydrogen storage material. The diameter of the hydrogen storage body and / or the configuration of the thermal transfer element may be optimised for different hydrogen storage materials such that the hydrogen storage bed can safely accommodate the volumetric change of specific hydrogen storage materials. The volume within the hydrogen storage bed is preferably large enough for the hydrogen storage material to expand freely, if it is not, the hydrogen storage material will be compacted inducing stress to the hydrogen storage bed.

[0044] In embodiments, the thermal transfer element is made from any suitable material with good thermal conductivity. Examples of suitable materials include Aluminium, which is light with good mechanical properties in hydrogen environments, good thermal conductivity, and corrosion resistance. Other suitable materials include copper, which also has a good thermal conductivity, a high temperature limit, low permeability and solubility to hydrogen. Copper also has a high eutectic point, which can be beneficial for reduced stress-corrosion cracking.

[0045] In embodiments, the hydrogen storage body is lined with a hydrogen diffusion liner, the hydrogen diffusion liner formed from a material suitable for preventing hydrogen ingress into the hydrogen storage body. Any material suitable for reducing or preventing hydrogen ingress may be used. Examples of suitable materials for reducing or preventing hydrogen ingress include metals comprising one or more elements selected from: copper, silver, gold and niobium.

[0046] Hydrogen ingress can lead to material failure, as hydrogen ingress may cause mechanical damage such as a loss in ductility and tensile strength. Hydrogen ingress is particularly problematic for steel. Therefore, when the hydrogen storage body comprises a steel pressure vessel, the provision of a hydrogen diffusion liner may be particularly beneficial.

[0047] In embodiments, the hydrogen storage system further comprises a primary flange and a secondary flange configured to seal either end of the hydrogen storage body. In some embodiments, the hydrogen storage system further comprises a capping plate configured to engage with the primary flange to seal an end of the hydrogen storage body. In embodiments, the capping plate supports the thermal transfer element. In some embodiments, the thermal transfer element may be formed as an integral part of the hydrogen storage body, for example using a sweating process, in such embodiments, the thermal transfer element may not be supported by the capping plate, as the support may be unnecessary.

[0048] Many of the hydrogen storage materials that are likely to be used in the hydrogen storage bed of the present invention are air sensitive. Furthermore, the pyrophoricity and explosive behaviour of hydrogen gas in air (under sudden exposure) needs to be taken into account, alongside the potentially pyrophoric behaviourof any of the hydrogen storage materials. As such, it is beneficial to have a flange at either end of the hydrogen storage body to create a seal. Having a flange at either end may increase the ease of loading the hydrogen storage bed. Many hydrogen storage materials, such as uranium, have a strong affinity to air and oxygen. Therefore, many hydrogen storage materials will readily react with nitrogen, oxygen, and water to form nitrides, oxides, oxy-hydride and oxynitride phases. The rate of degradation will be reduced if the hydrogen storage bed is leak-tight. Therefore, the presence of a primary flange and a secondary flange may aid in extending the operational lifetime of the hydrogen storage bed. Additionally, the present invention may allow for maintenance of the hydrogen storage bed without exposing the hydrogen storage material to the atmosphere. This may be particularly beneficial as it may increase the ease of maintenance of the hydrogen storage bed, for example the ease of maintenance of the heating and cooling system.

[0049] In some embodiments, the hydrogen storage bed further comprising a secondary vessel, the hydrogen storage body positioned within the secondary vessel.

[0050] In embodiments, a length of the secondary vessel may be greater than a length of the hydrogen storage body so as to provide a primary thermal bridging reduction region.

[0051] In embodiments, an external diameter of the hydrogen storage body may be less than an internal diameter of the secondary vessel so as to provide a secondary thermal bridging reduction region.

[0052] The provision of a primary and / or secondary thermal bridging reduction region may be advantageous, as it reduces the direct physical contact between the hydrogen storage body and the secondary vessel, and thus thermal transfer. The thermal bridging reduction region allows for tolerance for thermal expansion of the hydrogen storage body during use. The thermal expansion bridging region may allow for the secondary vessel to remain at a lower temperature than the hydrogen storage body when in use. For example, the hydrogen storage body during hydrogen storage may reach temperatures of up to about 500 °C, whilst the secondary vessel may remain at a temperature of less than about 100 °C.

[0053] In a second aspect, the present invention provides a method of using a hydrogen storage system for storing and releasing hydrogen, the method comprising the steps of: a) providing a hydrogen storage system as described herein; b) producing hydrogen from the electrolyser; c) loading the hydrogen storage bed with hydrogen; d) unloading the hydrogen from the hydrogen storage bed; and e) providing the fuel cell with the hydrogen.

[0054] In embodiments, hydrogen produced by the electrolyser is directed towards a buffer vessel prior to loading the hydrogen storage bed with the hydrogen.

[0055] In embodiments, hydrogen unloaded from the hydrogen storage bed is directed towards a buffer vessel prior to providing the fuel cell with the hydrogen.

[0056] The present invention allows for a full process of producing hydrogen, storing hydrogen and utilising hydrogen within a unitary system, with the storage of the hydrogen including a full cyclic process of hydriding and dehydriding. It is advantageous to provide the whole process in one system as it improves efficiency, reduces the need for transportation and reduces the risk of safety concerns.

[0057] In an aspect, the present invention provides a unitary hydrogen storage system for producing, storing, releasing and using hydrogen, the unitary hydrogen storage system comprising: an electrolyser; a hydrogen storage bed having a hydrogen storage material disposed therein; and a fuel cell; wherein the hydrogen storage system is configured to assume a loading condition and an unloading condition, wherein in the loading condition, hydrogen is produced by the electrolyser and loaded into the hydrogen storage bed by the hydrogen storage material, and wherein in the unloading condition, said hydrogen stored in the hydrogen storage bed is unloaded from the hydrogen storage bed and directed towards the fuel cell for use producing electricity.

[0058] The hydrogen storage system of the invention also allows for the separation of individual hydrogen storage beds without the hydrogen storage system being compromised by contamination. This may be particularly beneficial as the hydrogen storage bed may contain radioactive, pyrophoric materials due to the nature of metal hydrides, so ease of maintenance is desired.

[0059] The hydrogen storage system, and method of use described herein may also provide benefits in relation to reducing the production costs, or mitigating health and safety issues when using expensive, rare, toxic or even radioactive hydrogen storage materials. Brief Description of the Figures

[0060] The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which:

[0061] Figure 1 shows a schematic representation of a representative embodiment of a hydrogen storage system in accordance with the first aspect of the invention;

[0062] Figure 2 shows a schematic representation of a representative embodiment of a hydrogen storage system in accordance with the first aspect of the invention;

[0063] Figure 3 shows a side perspective view of a representative embodiment of a hydrogen storage bed in accordance with the first aspect of the invention;

[0064] Figure 4 shows the hydrogen storage system of Figure 2 in use, during electrolyser operation and in a loading condition; and

[0065] Figure 5 shows the hydrogen storage system of Figure 2 in use, during an unloading condition. Detailed Description

[0066] The invention provides a hydrogen storage system for producing, storing, releasing and utilising hydrogen. In embodiments, there is provided a hydrogen storage system that uses depleted uranium as a hydrogen storage material within the hydrogen storage system.

[0067] Unless otherwise stated, any feature described herein can be combined with any aspect or any other feature described herein.

[0068] Directional terms such as "entrance" or "exit" and "before" or "after" are relative to the direction of hydrogen flow through the hydrogen storage system unless otherwise stated.

[0069] Hydrogen embrittlement and mechanical / thermal fatigue is a concern when designing a hydrogen storage system. The hydrogen storage system will circulate hydrogen under variable pressure, and hydrogen embrittlement and mechanical / thermal fatigue increases the risk of component failure. The component failure may be, for example, loss of vacuum, leakage and / or air ingress. Hydrogen rated components will therefore be used for the hydrogen storage system.

[0070] Referring to Figure 1, there is indicated is a hydrogen storage system 10, which is suitable for producing, storing, releasing and utilising hydrogen. The hydrogen storage system 10 comprises an electrolyser 12, a hydrogen storage bed 14 and a fuel cell 16.

[0071] The electrolyser 12, hydrogen storage bed 14 and fuel cell 16 are interconnected. Piping and a series of valves 18 are used to transport hydrogen produced by the electrolyser 12 to the hydrogen storage bed(s) 14 during a loading condition, and to transport hydrogen from the hydrogen storage bed(s) 14 to the fuel cell 16 during an unloading condition. Preferably, the piping used is stainless steel (preferably 316 L stainless steel due to this being a highly durable, corrosion and oxidation resistant material with high melting point (about 1454 °C), and a high tensile strength (about 621 MPa)). The valves 18 can be used to section parts of the hydrogen storage system 10 into loops. The valves 18 are preferably automatic. Furthermore, the valves 18 are preferably pneumatic. Pneumatically actuated valves 18 may be set at a threshold pressure which is considerably lower than the pressure that the hydrogen storage system 10 can withstand without failing. This may increase the safety of the hydrogen storage system 10.

[0072] The electrolyser 12 separates water into hydrogen and oxygen. Any suitable electrolyser 12 may be utilised. Examples of suitable electrolysers 12 include alkaline, solid oxide or proton exchange membrane electrolysers. The electrolyser 12 preferably supplies hydrogen at a rate in the range of about 0.5 kg.h1 to about 2.0 kg.h1, for example about 0.75 kg.h 1 to about 1.5 kg.h'1, for example about 1.0 kg.h1 to about 1.25 kg.h1. Although example numerical ranges have been provided, the rate at which the electrolyser 12 supplies hydrogen is dependent on storage capacity of the hydrogen storage system 10, and in some cases on the number of hydrogen storage bed(s) 14 within the hydrogen storage system 10. The rate at which the electrolyser 12 supplies hydrogen may also be dependent on the capacity of the hydrogen storage bed(s) 14 within the hydrogen storage system 10.

[0073] The electrolyser 12 preferably supplies hydrogen at a pressure in the range of about 0.7 MPa to about 2 MPa, for example, about 0.75 MPa to about 1.9 MPa, about 0.8 MPa to about 1.8 MPa. For example, in a preferred embodiment, the electrolyser 12 preferably supplies hydrogen at about 0.8 MPa. Example numerical ranges have been provided, but the pressure at which the electrolyser 12 supplies hydrogen to the hydrogen storage system 10 is specific to the setup of the hydrogen storage bed(s) 14, for example, it may be dependent on the number of hydrogen storage bed(s) 14.

[0074] As best shown in Figure 2, in which an embodiment of the present embodiment is depicted, a purification system 20 is arranged directly after the electrolyser 12. The purification system 20 removes moisture and oxygen from the output of the electrolyser 12. A purification inlet valve 18a is positioned between the electrolyser 12 and purification system 20 to control the input into the purification system 20. The purification system 20 may, for example, be based on a palladium diffusion process, a silica desiccant system, or any other suitable purification system. The purification system 20 increases the purity of the hydrogen gas flowing to the hydrogen storage bed(s) 14. The purity of hydrogen gas that is produced by the electrolyser 12 and subsequently permitted into the rest of the hydrogen storage system 10 will dictate the operational lifetime of the hydrogen storage system 10 by directly affecting the degradation of the hydrogen storage material overtime. High purity hydrogen gas slows degradation and increases the operational lifetime of the hydrogen storage bed(s) 14.

[0075] In the embodiment shown in figure 2, a gas purity sensor 22 is arranged directly after the purification system 20. The gas purity sensor 22 analyses the components of the hydrogen gas stream following from the electrolyser 12. The analysis is preferably continuous. Preferably, there may be a control system in communication with the gas sensor. The control system being configured to inform an operator of the nature of any contamination present within the hydrogen gas stream. A gas purity inlet valve 18b is positioned after the purification system 20 to control the input of the hydrogen gas stream, from the purification system 20, into the gas purity sensor 22. A gas purity outlet valve 18c is positioned after the gas purity sensor 22. The gas purity outlet valve 18c controls the output of the hydrogen gas stream that exits the gas purity sensor 22. This is beneficial because if the gas purity sensor 22 senses the hydrogen gas stream is contaminated, the gas purity outlet valve 18c may be closed, to isolate the electrolyser 12 of the hydrogen storage system 10 and to prevent contaminated hydrogen gas from entering the rest of the hydrogen storage system 10. The gas purity sensor 22 is also advantageous as it allows for a fast response and resolution of any contamination present within the hydrogen gas stream. Although the analysis of the hydrogen gas stream is described as preferably continuous, it is envisaged that the analysis may be performed at set intervals, or random intervals, of time, however this is thought to be less beneficial, as less 'real-time' data will be produced.

[0076] The hydrogen storage system 10 of the depicted embodiment further comprises two buffer vessels 24a, 24b. The two buffer vessels 24a, 24b are arranged in parallel. The two buffer vessels 24a, 24b can preferably hold the same volume of hydrogen. Each buffer vessel 24a, 24b has a buffer valve 18d to allow for hydrogen introduction and release. Each buffer vessel 24a, 24b has a pressure transducer 26 and a thermocouple 28. The pressure transducer 26 and thermocouple 28 measure the pressure and temperature respectively of the gas within each buffer vessel 24a, 24b. Preferably, the measurements are taken continuously. It is envisaged that the measurements may be taken at set intervals, or random intervals, of time, however this is thought to be less beneficial, as less 'real-time' data will be produced.

[0077] The two buffer vessels 24a, 24b are connected through multiple valves 18. A pump 30 is disposed between the two buffer vessels 24a, 24b. The pump is preferably a hydrogen pump 30. One of the buffer vessels 24a is preferably low-pressure. One of the buffer vessels 24b is preferably high-pressure.

[0078] During hydrogen storage bed(s) 14 loading, at least one of the buffer vessels 24a, 24b acts as a buffer volume for securing sufficient supply of hydrogen to the hydrogen storage beds 14. During unloading, the low-pressure buffer vessel 24a provides gas pressure relief by acting as an expansion volume to allow the gas to cool down to room temperature. This reduces the risk of component failure within the hydrogen storage bed(s) 14 owing to pressure and temperature build-up. The gas pressure relief into at least one of the buffer vessels 24a, 24b also improves the kinetics of the hydrogen storage system 10. Both buffer vessels 24a, 24b may provide a lag between the electrolyser 12, fuel cell 16 and hydrogen storage bed(s) 14 to help secure safe operation of the hydrogen storage system 10.

[0079] In certain embodiments, the hydrogen storage system 10 may comprise a plurality of hydrogen storage bed(s) 14. In the depicted embodiment, the hydrogen storage system 10 comprises six hydrogen storage bed(s) 14. Each hydrogen storage bed 14 may have in the range of about 30 kg to about 180 kg of hydrogen storage material, for example, in the range of about 35 kg to about 170 kg of hydrogen storage material, in the range of about 40 kg to about 160 kg of hydrogen storage material or in the range of about 45 kg to about 140 kg of hydrogen storage material. For example, in one embodiment, the hydrogen storage bed 14 may have about 43 kg of hydrogen storage material. The hydrogen storage system 10 is a modular system and as such the capacity of the hydrogen storage system 10 is dependent on the setup. As such, the value provided herein are by way of example. For example, the total capacity of the hydrogen storage system 10 may be in the range of 30 kg to about 500 kg of hydrogen storage material, in the range of about 240 kg to about 300 kg of hydrogen storage material or in the range of about 252 kg to about 282 kg of hydrogen storage material. For example, in one embodiment, the hydrogen storage bed 14 may have about 258 kg of hydrogen storage material. The hydrogen storage material is preferably a metal hydride. In the depicted embodiment, five of the hydrogen storage beds 14 are used for hydrogen storage and are configured to store the same volume of hydrogen storage material. In some embodiments, one of the hydrogen storage beds 14 may be used as a buffer bed module. The buffer bed may be configured to store a larger volume of hydrogen storage material than a hydrogen storage bed 14. For example, the buffer bed module may be able to store four times are much hydrogen storage material when compared to the other hydrogen storage beds 14 in the hydrogen storage system 10. Each hydrogen storage bed 14, including the buffer bed module 32, may be isolatable from the other hydrogen storage beds 14. In other embodiments, all of the hydrogen storage beds 14 may be used for hydrogen storage.

[0080] A hydrogen storage bed is shown in Figure 3, each hydrogen storage bed 14 comprises a hydrogen storage body 44 and a thermal transfer element 46. The thermal transfer element 46 comprises a fin element 48 configured to allow the redistribution and expansion of a hydrogen storage material within the hydrogen storage body 44 during hydrogen loading and unloading of the hydrogen storage material. The thermal transfer element 46 is positionable within the hydrogen storage body 44. The fin element 48 in the depicted embodiment is helical. The helical fin element 48 has a helix angle in the range of about 1° to about 80°. The thermal transfer element 46 may be fixable or fixed relative to the hydrogen storage body 44. The thermal transfer element 46 may be removable from the hydrogen storage body 44.

[0081] In embodiments the thermal transfer element 46 may comprise a core 50, for example a tubular core, for supporting and / or heating the fin element 48 of the thermal transfer element 46. In embodiments, the core of the thermal transfer element 46 is hollow, for example, to allow for insertion of a heating element into the core 50. The heating element allows for control of heating requirements during unloading / discharging of the hydrogen storage bed 14. In a preferred embodiment, the heating element may be formed as a cartridge heater. In some embodiments, more than one heater element may be inserted into the tubular core 50. Also, although not depicted, at least one thermocouple may be placed into the at least one thermocouple guide to monitor the thermal profile of the hydrogen storage bed. The heating element may be controlled using a heater controller.

[0082] Each hydrogen storage bed 14 preferably has a dynamic cooling system. The dynamic cooling system circulates cooling gas and adjusts the supply of hydrogen to the hydrogen storage beds. The dynamic cooling system preferably uses nitrogen as the cooling gas. Although the use of nitrogen is described, it is envisaged that argon, or an alternative inert gas, and / or compressed air could be used as the cooling gas.

[0083] The hydrogen storage beds 14 depicted in Figure 2 are arranged in parallel. The hydrogen storage beds 14 are all interconnected to form a hydrogen storage gas loop 34. The hydrogen storage gas loop 34 has a loading valve 18e and an unloading valve 18f arranged at the entrance and exit of the hydrogen storage gas loop 34 respectively. The loading valve 18e when in an opened condition allows for hydrogen to be introduced into the hydrogen storage loop 34. The unloading valve 18f when in an opened condition allows for hydrogen to be released from the hydrogen storage loop 34. In the depicted embodiment, the hydrogen storage beds 14 are orientated horizontally for effective and uniform heat distribution of the hydrogen storage material.

[0084] Each hydrogen storage bed 14 of the depicted embodiment has a minor inlet valve 18g and a minor outlet valve 18h that controls the hydrogen inlet and outlet to / from an individual hydrogen storage bed 14. In some embodiments, the minor inlet valve 18g and minor outlet valve 18h may be the same valve. Each hydrogen storage bed 14 also has a major inlet valve 18i positioned after the minor inlet valve 18g and minor outlet valve 18h and before the hydrogen storage bed 14. Each hydrogen storage bed 14 also has a pressure transducer 26. The minor inlet valve 18g and minor outlet valve 18h are preferably arranged in parallel. The minor inlet valve 18g and minor outlet valve 18h connect each hydrogen storage bed 14 to the hydrogen gas loop 34. The major valve 18i and pressure transducer 26 are preferably arranged in series.

[0085] Each major valve 18i provides direct access to each hydrogen storage bed 14. An intermediary zone is preferably formed between the minor inlet valve 18g, minor outlet valve and the major valve 18i. The minor inlet valve 18i when in an opened condition allows for hydrogen to be introduced to the intermediary hydrogen zone. The minor outlet valve 18h when in an opened condition allows for hydrogen to be released from the intermediary zone.

[0086] The intermediary zone may be beneficial for providing increased safety in, for example, the event of a valve 18 failure. The intermediary zone also allows for ease of isolation of the hydrogen storage bed 14 from the rest of the hydrogen storage system 10. This may be particularly beneficial for maintenance of each hydrogen storage bed 14. The provision of major and minor valves 18 decreases the risk of hydrogen storage material degradation and / or particulate release.

[0087] The hydrogen storage bed gap loop 34 of the depicted embodiment is connected to the low-pressure buffer vessel 24a and the high-pressure buffer vessel 24b. An in-line filter 36, a gas purity sensor 22, a pressure transducer 26 and a thermocouple 28 are positioned in series directly before the flow of hydrogen into loading valve 18e, and directly after the flow of hydrogen through the unloading valve 18f. Valves 18 are positioned between the in-line filters 36 and gas purity sensors 22, and between the gas purity sensors 22 and the pressure transducers 26 and thermocouple 28. The valves 18 allow for ease of isolation of sections of the hydrogen storage system 10. As previously mentioned, the measurement and analysis of the hydrogen gas is preferably continuous, however continuous measurement is not essential.

[0088] In the depicted embodiment, a pressure regulator 38 is also arranged in between the hydrogen storage loop 34 and the buffer vessels 24a, 24b. Multiple pressure regulators 38 may be used. Flow meters, which are not shown, may also be arranged in between the hydrogen storage loop 34 and the low and high pressure buffer vessels 24a, 24b.

[0089] Pressure and temperature are preferably monitored and continuously logged across the hydrogen storage system 10 to ensure normal operation under the unloading and loading of hydrogen. In some embodiments, a number of thermocouples 28 may be fitted in various areas of the hydrogen storage system 10. Thermocouples 28 may be fitted across the hydrogen storage loop 34 to monitor the temperature of the hydrogen gas that is given-off during unloading. The thermocouples 34 may also monitor the cooling routine of the hydrogen as it expands and pressurises to the low and high-pressure buffer vessels 24a, 24b, respectively. The gas pressure profile of the hydrogen storage system 10 under the various processes may dictate and inform parameters of the hydrogen storage system 10 such as hydrogen gas flow during loading, temperature of unloading, kinetics of loading / unloading and the hydrogen conversion to electricity.

[0090] In a preferred embodiment, the hydrogen storage system 10 relies on hydrogen energy storage through the formation and phase transformation of metal hydride powders. In-line filtering is important to mitigate circulation of highly mobile hydrogen storage material particulates from the hydrogen storage bed 14 gas loop. Effective filtering of any fine particulates within the hydrogen storage system 10 is therefore desired. Each in-line filter 36 positioned in series with the loading valve 18e and an unloading valve 18f respectively may be configured to contain any fine powder that is produced during hydriding and dehydriding. The in-line filters 36 may have a filter pore size in the range of from about 5 pm to about 50 pm, for example, from about 10 pm to about 40 pm, from about 10 pm to about 30 pm. For example, in one embodiment, the in-line filter 36 may have a filter pore size of about 15 pm.

[0091] Filter characteristics affect the filtering efficiency of the system and also the loading / unloading rate. There are three main parameters that characterize the filters: a) filter face area; b) filter thickness; and c) filter pore size. A decreasing filter pore size improves the trapping efficiency for the particulates. Gas line conductance which relates to hydrogen gas circulation in the hydrogen storage system is greatly affected by the diameter of the filters with increasing diameter (reduced filter porosity) leading to higher line conductance and, thus, an increase in the loading rate. Larger face filter areas and thinner filters may also improve the kinetics of hydrogen absorption.

[0092] An additional secondary in-line filter40 may be positioned throughout the hydrogen storage system 10, as in the depicted embodiment. In some embodiments, multiple additional secondary inline filters may be utilised. The secondary in-line filter 40 preferably has a filter pore size smaller than the filter pore size of the in-line filters 36. For example, the secondary in-line filter 40 may have a filter pore size in the range of from about 0.1 to about 15 pm. For example, in one embodiment, the secondary in-line filter 40 may have a filter pore size of 0.5 pm. The secondary in-line filter 40 is preferably removable from the hydrogen storage system 10 to allow for periodic recovery and maintenance. The secondary in-line filter 40 is preferably a high-efficiency particulate absorbing (HEPA) filter. More preferably, the secondary in-line filter 40 is a paper HEPA filter.

[0093] Furthermore, further filters may be added prior to any release of hydrogen, for example, prior to any ventilation system and prior to the fuel cell 16. Any further filters used preferably have a filter pore size smaller than the filter pore size of the in-line filters 36 and smaller than the filter pore size of the secondary in-line filters 40.

[0094] The fuel cell 16 in the depicted embodiment is connected to the two buffer vessels 24a, 24b and pump 30. The fuel cell 16 and the low-pressure buffer vessel 24a in the depicted embodiment are connected via a series of valves 18. Between the high-pressure buffer vessel 24b and the fuel cell 16 is a pressure regulator 38. A pressure regulator inlet valve 18j is positioned in between the high-pressure buffer vessel 24b and the pressure regulator 38. A pressure regulator outlet valve 18k may be positioned in between the pressure regulator 38 and the fuel cell 16.

[0095] A pressure regulator 38 between the buffer vessels 24a, 24b and the hydrogen storage bed 14 hydrogen storage gas loop 34 may allow for stabilisation of pressure to a desired value during absorption. This may lead to improved hydrogen recovery kinetics. A pressure regulator 38 positioned between the buffer vessels 24a, 24b and the fuel cell 16 may enable the hydrogen to electrical energy conversion to occur at an optimum rate.

[0096] Although not depicted, in a preferred embodiment the hydrogen storage bed 14 has uranium as the hydrogen storage material. In an even more preferred embodiment, the hydrogen storage bed 14 has depleted uranium as the hydrogen storage material.

[0097] The purity of the gas within the hydrogen storage system 10 may also be measured continuously using at least one gas purity sensor 22. The use of at least one gas purity sensor 22 is advantageous as if contamination is detected, parts of the hydrogen storage system 10 may be isolated and repaired / maintained.

[0098] A source of contamination and component failure may be the infiltration of fine particulates in joints and connections of the hydrogen storage system. The range of filters 36, 40 may be used to ensure that migration of any particulates into the gas loop and into components is mitigated. In an event of filter failure, a second filter on the line may effectively trap any particulates that might be released.

[0099] Although not depicted, safety interlocks connected to the gas sensors across the loop may ensure that the beds are isolated immediately after any air introduction.

[00100] Furthermore, in some embodiments, additional pumps may be part of the hydrogen storage system to aid with loading and unloading of the hydrogen storage beds.

[00101] Method of Use

[00102] A generalised method of use of an embodiment of the hydrogen storage bed 14 will now be described.

[00103] Firstly, a hydrogen storage system 10 is provided. Electrical energy is provided to the electrolyser 12 to separate water into hydrogen and oxygen. The hydrogen storage bed 14 is subsequently loaded with hydrogen generated by the electrolyser 12. After a desired period of time, the hydrogen is unloaded from the hydrogen storage bed 14. The unloaded hydrogen is provided to the fuel cell 16. The fuel cell 16 utilises the unloaded hydrogen to produce electrical energy. Optionally, the hydrogen may be passed through an in-line filter 36 prior to loading and after unloading the hydrogen from / to the hydrogen storage bed(s) 14. The desired period of time may be dictated by the specific use case.

[00104] A method of use of a specific embodiment of the hydrogen storage system 10 will now be described.

[00105] Figure 4 illustrates an embodiment of the hydrogen storage system 10 during electrolyser 12 operation, and during loading of the hydrogen storage beds 14. The dashed lines depict the flow of hydrogen allowed by the opened valves 18. The electrolyser 12 produces hydrogen for the loading process of the hydrogen storage beds 14. During this process, electrical energy is used to drive the electrolyser 12 to produce hydrogen and oxygen through water separation. The rate of hydrogen production can be adjusted depending on the energy storage capacity of the hydrogen storage system 10.

[00106] The hydrogen produced by the electrolyser 12 produced is then passed through a purification system 20 to remove any water and oxygen. The hydrogen produced is preferably 99.999 % purity hydrogen, or of higher purity.

[00107] The hydrogen then passes through the gas purity sensor to ensure that no contaminants are carried into the hydrogen storage gas loop. The hydrogen stream is then directed to a low-pressure buffer vessel 24a, through valves 18, 18a, 18b, 18c, 18d connecting the electrolyser and the low-pressure buffer vessel 24a. During this process the pressure, the temperature and purity of the gas are preferably continuously monitored.

[00108] When there is no requirement for hydrogen to be produced, the electrolyser 12 is shut down.

[00109] Figure 4 illustrates an embodiment of the hydrogen storage system 10 during a loading condition. The hydrogen that is produced and stored in the low-pressure buffer vessel is directed to the hydrogen storage bed(s) through a pressure regulator 38 and through the opening of intermediary valves 18, 18d, 18e. The pressure regulator 38 will be set to an appropriate pressure for hydrogen loading, and the hydrogen will be introduced to the hydrogen storage beds 14 through opening of the minor inlet valve 18g and major valve 18i. The appropriate pressure is preferably 50 kPa to 250 kPa. Once the hydrogen is introduced to the hydrogen storage beds 14, hydriding will take place. Hydriding is exothermic and as such the temperature of the hydrogen storage beds 14 will increase. The temperature of the hydrogen storage beds 14 is controlled using a dynamic cooling system. The dynamic cooling system circulates cooling gas and adjusts the supply of hydrogen to the hydrogen storage beds 14. The dynamic cooling system preferably uses nitrogen as the cooling gas. Although the use of nitrogen is described, it is envisaged that argon, or an alternative inert gas, or compressed air could be used as the cooling gas.

[00110] After loading of the hydrogen storage beds 14 is complete, each hydrogen storage bed 14 is isolated from the rest of the hydrogen storage system 10, by the closure of the minor inlet valve 18g and the major valve 18i, the minor outlet valve 18h being closed through the entire process. The loading valve 18e is also closed. Any remaining gas in the high-pressure buffer vessel 24b is then evacuated and collected or isolated.

[00111] Figure 5 illustrates an embodiment of the hydrogen storage system 10 during an unloading condition. In the unloading condition, hydrogen is delivered to the fuel cell 16 in its gaseous form when requested. For the hydride to decompose and hydrogen to be given-off, the temperature in the hydrogen storage beds 14 can be raised to about 325 to about 480°C. The temperature in the hydrogen storage beds 14 is raised through the use of the heating element within the thermal transfer element 46 of each individual hydrogen storage bed 14. When the temperature range is reached, hydrogen pressure is introduced in the hydrogen storage beds 14. The pressure value is directly related to the temperature, and is expected to be in the range of about 10 kPa to about 400 kPa, for example, in a range of about 70 kPa to about 150 kPa or in the range of about 90 kPa to about 125 kPa. Hydrogen gas is directed to the low-pressure buffer vessel 24a through the opening of valves 18, for example, the unloading valve 18f. The hydrogen gas is then pressurized by the pump 30 and directed to the high-pressure buffer vessel 24b. When unloading is completed, or no more hydrogen is required, the heating element within the thermal transfer element in the hydrogen storage bed 14 may be switched off and the hydrogen storage beds 14 cooled down. The hydrogen storge beds 14 are then isolated from the hydrogen storage system 10. Any remaining hydrogen gas in the hydrogen storage system 10 is pressurised in the high-pressure buffer vessel 24a, this includes evacuation of the low-pressure buffer vessel 24a. After the low-pressure buffer vessel 24a is evacuated and the hydrogen is driven-off to the high-pressure buffer vessel 24b, the valves 18 connecting the two buffer vessels 24a, 24b are closed. The high-pressure buffer vessel 24b is then isolated, and any remaining gas in the line is ventilated or collected, for example, the remaining hydrogen gas may be directed back to the hydrogen storage beds 14 to be stored (absorbed by the metal hydride) for future use.

[00112] The unloading and electricity production condition are preferably in unison and complementary. During electricity production, the hydrogen in the high-pressure buffer vessel 24b is directed through a pressure regulator 38. The pressure regulator 38 being configured at a desirable pressure for fuel cell 16 operation. If no more hydrogen is unloaded from the hydrogen storage beds, it is expected that hydrogen pressure in the high-pressure buffer vessel 24b reduces down to the operating pressure of the fuel cell. The high-pressure buffer vessel 24b can be isolated by closure of valves 18, and any remaining hydrogen gas in the line may be ventilated or collected, for example, the remaining hydrogen gas may be directed back to the hydrogen storage beds 14 to be stored (absorbed by the metal hydride) for future use.

[00113] Safety Considerations

[00114] The following paragraphs discuss some of the safety features of the hydrogen storage system 10.

[00115] The electrolyser 12 is preferably configured to switch-off in an emergency event. For example, an emergency event such as an electrical failure, inadvertent hydrogen / oxygen mixing, water supply failure. Furthermore, if contamination is detected in the low-pressure buffer vessel 24a side of the hydrogen storage system 10 (leak, incomplete evacuation of vessel etc.), the gas purity sensor 22 may preferably have a safety interlock to automatically close valves 18 and switch off the electrolyser 12 mitigating any further contamination and mixing of hydrogen and oxygen in the hydrogen storage system loop 34. Another interlock may be fitted to switch the electrolyser 12 off if high-pressure is detected on the low-pressure buffer vessel 24a side of the hydrogen storage system 10. A pressure relief valve may also open to ventilate the hydrogen storage system 10 in an event of pressure buildup.

[00116] As the hydrogen storage system 10 requires handling of flammable hydrogen gas, a collection cylinder 42 could be used to discharge the hydrogen storage system of hydrogen, if the hydrogen is not loaded back to the hydrogen storage beds 14. Any discharge of hydrogen to the surrounding environment would have to be conducted in a controlled manner permitting progressive pressure relief of the hydrogen storage system 10. The exiting gas will be passed through at least one filter to not allow any particulate contamination to escape in the environment.

[00117] Loading Condition

[00118] Three safety interlocks may be utilised for the loading condition. The safety interlocks are preferably associated with different valves. In an embodiment, the three safety interlocks are associated with the minor inlet valve 18g, minor outlet valve 18h and major inlet valve 26 of each hydrogen storage bed 14. The interlock valve may be used as a safety interlock for at least the following circumstances. Firstly, the safety interlocks may isolate the individual hydrogen storage bed 14 from the rest of the hydrogen storage system 10 if the system becomes contaminated. This may be beneficial as it may reduce the contamination and subsequent degradation of the hydrogen storage bed. This reduction may help to mitigate storage capacity reduction. Secondly, the safety interlocks may be used to isolate the hydrogen storage bed 14 in the event of a regulator failure. This may be advantageous as it may help to ensure pressurisation of a hydrogen storage bed 14 does not result in component failures. Thirdly, the interlocks may be of use if the temperature in the bed exceeds a temperature threshold due to failure in the cooling system. The safety interlocks may be used to restrict the supply of hydrogen to the hydrogen storage bed. Restricting the supply of hydrogen may compromise the hydriding reaction and thus the generation of heat. In a preferable embodiment, the temperature rise in the hydrogen storage bed 14 is not expected to exceed the dehydriding temperature (about 480°C) and, thus, the components of the hydrogen storage bed 14 will preferably be able to accommodate such an increase and not induce any failures.

[00119] Unloading Condition

[00120] During the unloading condition, there is a risk of overheating and, thus, over pressurizing the hydrogen storage bed(s) since dissociation pressure increases with temperature during dehydriding. The thermal transfer element of each hydrogen storage bed 14 is preferably rated to maximise output at full line voltage that corresponds to a maximum acceptable temperature in the hydrogen storage bed(s) 14. In one embodiment the maximum acceptable temperature may be about 500°C. Hydrogen that is produced during unloading will leave the hydrogen storage bed(s) under temperature but is expected to lose energy in the form of heat during circulation and expansion in the low-pressure buffer vessel 24a. A heat exchanger system for the unloaded hydrogen may also be used within the hydrogen storage system 10, if required. A temperature interlock may be set so the low-pressure buffer vessel buffer valve 18d only opens after the hydrogen gas temperature is below about 80°C . A heat exchanger in the buffer vessel 24a, 24b may be utilised to ensure effective cooling of gas. The valves 18 which connect the hydrogen storage bed(s) 14 with the rest of the hydrogen storage system 10 may also automatically open to relieve any pressure increase in the hydrogen storage bed(s) 14, for example, any pressure increase greater than about 0.6 MPa, any pressure increase greater than about 0.4 MPa, any pressure increase greater than about 0.2 MPa or any pressure increase greater than about 0.1 MPa. If the pressure valve fails to open or is blocked and pressurization is detected within the bed, a pressure interlock may trigger the thermal transfer element to be switched off to stop any hydrogen generation. Another pressure interlock may be configured to close the valve to the high-pressure buffer vessel when pressure approaches a pre-determined value, for example, when pressure approaches about 9.5 MPa, when pressure approaches about 8.5 MPa, when pressure approaches about 7.5 MPa, or when pressure approaches about 6.5 MPa. This is to ensure that hydrogen in the vessel does not exceed a preferable operational pressure range, for example of 0 to about 10 MPa or of 0 to about 6 MPa. The high-pressure buffer vessel valve 18d may automatically open again when the pressure in the high-pressure buffer vessel 24b decreases below that threshold.

[00121] In the event of an emergency, the hydrogen gas may need to be evacuated from the high-pressure buffer vessel 24b, or the low-pressure buffer vessel 24a. The hydrogen may be passed through a filter before evacuation. The remaining gas from both the low and high-pressure buffer vessels 24a, 24b may also be loaded again to the hydrogen storage bed 14 instead of being evacuated or isolated in the buffer vessels 24a, 24b. This may be achieved by following the steps of the loading process described earlier. This may be preferable as it may result in no energy being lost in the hydrogen storage system 10.

[00122] Fuel Cell

[00123] The fuel cell 16 may be configured to switch-off in an emergency event. These emergency events include, but are not limited to: electrical failures; hydrogen / air mixing; and lack of air supply. The fuel cell 16 may turn itself off or switch to a standby mode. If the pressure regulator 38 fails, valves 18 will automatically close and the overpressure in the hydrogen storage system could either be relieved through opening of valves 18 or the hydrogen can be redirected for collection.

[00124] In an event of an emergency due to abnormal operation, hydrogen gas may need to be evacuated from pipes of the hydrogen storage system 10 and the high-pressure buffer vessel 24b. While evacuating, hydrogen may be ventilated progressively in air if in small quantity or collected within a pressure cylinder 42 and be re-used. High-pressure buffer vessel 24b evacuation occurs through opening of valves 18.

[00125] Similarly to the high-pressure buffer vessel, the low-pressure buffer vessel 24a may require evacuation. Evacuation of the low-pressure buffer vessel 24a side will occur by opening valves 18. Any solid contamination of the gas may betrapped by filters 40 before exiting the hydrogen storage system 10 and the gas may be collected and re-used, for example, the remaining hydrogen gas may be directed back to the hydrogen storage beds 14 to be stored (absorbed by the metal hydride) for future use. Examples

[00126] The following illustrates an example of the hydrogen storage system and related aspects described herein. Thus, these examples should not be considered to restrict the present disclosure, but are merely in place to teach how to carry out the methods of the present disclosure.

[00127] Example 1 - Hydrogen Storage Bed

[00128] In this example, the hydrogen storage bed comprises a hydrogen storage body and a thermal transfer element. The thermal transfer element comprises a fin element configured to allow the redistribution and expansion of a hydrogen storage material within the hydrogen storage body during hydrogen loading and unloading of the hydrogen storage material. The thermal transfer element is positionable within the hydrogen storage body. The thermal transfer element is fixable relative to the hydrogen storage body. The thermal transfer element is a helical fin element. In use, the thermal transfer element is positioned within the hydrogen storage body. In this example, the hydrogen storage bed is orientated horizontally for effective and uniform heat distribution of the metal hydride. A horizontal direction may help provide improved thermal management such that the hydrogen storage bed is more easily managed and maintained. The hydrogen storage bed stores about 43 kg of depleted uranium. Each hydrogen storage bed has a theoretical hydrogen capacity of 0.539 kg.

[00129] An example of a hydrogen storage bed is shown in figure 3. In this specific example, the hydrogen storage bed has a length to diameter (L / D) aspect ratio of 6. This L / D aspect ratio, without wishing to be bound by theory, is thought to be beneficial compared to lower L / D aspect ratios due to the hydrogen gas transport being more efficient in the axial direction than through a radial direction limited by a porous hydrogen storage material.

[00130] Example 2 - UHa Powder Preparation

[00131] The formation of a metallic uranium powder from a precursor metallic coupon was examined by the inventors. Powderisation was achieved by repeated cycles of hydride (UH3) formation and then hydride thermal decomposition; termed as 'hydriding and dehydriding'. After each cycle a small mass of particulate material was extracted for electron microscopy analysis to understand how the size and morphology of the arising powder changed from one cycle to the next.

[00132] Particulate uranium was produced in-situ on the gas rig by performing a series of hydriding and dehydriding cycles on a piece of uranium metal. The procedure was the same whether hydrogen or deuterium was used as the reacting gas, and the term 'hydriding' is used as the catch all term for both unless otherwise stated.

[00133] Metal preparation: The uranium coupons used were relatively large (about 3 g). Therefore, inside a glovebox these were cut to 0.3 g samples to reduce the quantity of material used.

[00134] The metal was cleaned of its surface oxide by submerging it for one minute in 10% nitric acid diluted with deionised water. This was then washed in ethanol, dried, weighed and then gasket sealed in a reaction cell (with thermocouple attachment). The reaction cell ('bed') was placed in a clam-shell furnace, attached to the gas control rig, and evacuated ready for H2 / D2 exposure.

[00135] Gases: The gas used was either: H2,99.9997% supplied by Air Products or; D2 99.8% supplied by Isotec.

[00136] Hydriding-dehydriding: With the sample under vacuum, the furnace was then set to 240 °C to maintain a pressure of about 55000 Pa in the reaction cell from a fixed volume of H2 in the reservoir lines. From monitoring of the reservoir pressure, it could be seen that hydriding was complete when the pressure no longer decreased. The pressure controller was closed, the cell evacuated and sealed, and the furnace set to 500 °C. Dehydriding was observed to have begun when gas pressure in the cell started to rise and to have completed when the pressure had plateaued. The cell was then reevacuated, sealed to check for any further pressure increase indicative of any unreleased hydrogen, reopened to the vacuum and the furnace switched off. This cycle was repeated up to 10 times to ensure the complete comminution of the sample.

[00137] As described the starting material was solid coupons that then went through numerous hydriding and dehydriding cycles to produce a fine uranium particulate. It is considered that for uranium storage beds used for larger-scale hydrogen storage, a similar conditioning process should be used to prepare each 'bed' module for operation. By starting with precursor pellets of solid-uranium metal bed preparation is rapid and can be performed safely in a glove box or even air due to the low surface area of the uranium metal.

[00138] Once bed powderisation was completed, the resulting powder material was found to be very volatile. Characterisation of powders had to occur post reaction.

[00139] Comparison of particulates produced from increasing numbers of hydriding-dehydriding cycles indicated that after seven cycles the characteristics of the residual powders remained effectively the same in terms of particle size, morphology, and surface area. This is an important conclusion for hydrogen storage application as it demonstrates an effective 'conditioning' sequence for uranium hydrogen storage beds, when starting from solid uranium metal pellets.

[00140] Example 3 - Hydrogen Storage System

[00141] In an example, a hydrogen storage system is assembled. The example will be described in the context of Figure 2, with reference numerals used to aid understanding. In a specific example, the hydrogen storage system 10 could be built using 0.5 inch (1.3 cm) stainless steel piping from Swagelok Ltd. Having a large diameter of pipe may be beneficial as it will allow for a higher hydrogen flow and circulation across the loop.

[00142] An alkaline electrolyser (AE) 12 provided by McPhy could be utilised to decompose water into hydrogen and oxygen using electricity. The electrolyser 12 would supply hydrogen at a maximum rate of 1.2 kg.h1 at 0.8 MPa.

[00143] The hydrogen produced would pass through an in-line gas purifier 20 to ensure no contaminants are carried into the gas loop.

[00144] Two 150 litre buffer vessel volumes 24a, 24b could be used. One of the buffer vessel volumes could be a low-pressure buffer vessel 24a, one of the buffer vessel volumes could be a high-pressure buffer vessel 24b.

[00145] A proton exchange membrane (PEM) fuel cell 16 could be provided by Powidian to convert hydrogen to electricity. To operate the fuel cell 16, the hydrogen pressure would be between 1 MPa and 1.8 MPa at a temperature of >60°C. The fuel cell 16 would be configured to accept a hydrogen flow at a rate of up to 1.5 kg. h1.

[00146] The hydrogen storage system 10 of the example comprises of six hydrogen storage beds 14 as described in Example 1, with each hydrogen storage bed 14 containing about 43 kg depleted uranium. The hydrogen storage beds 14 are able to be isolated from each other and from the hydrogen storage gas loop 34. This is beneficial as allows for more efficient maintenance of the hydrogen storage system 10.

[00147] Pressure regulators 38 would be used in the hydrogen storage system 10. The regulators would ensure that hydrogen was supplied at the desired pressure for any given operation scenario. These include hydrogen loading, hydrogen filling and supplying hydrogen to the fuel cell for electricity production. Pressure transducers 26 and thermocouples 28 would measure the pressure and temperature of the gas in the hydrogen storage system 10 while gas purity sensors 22 in the form of a hydrogen purity sensor would befitted to detect and monitor the purity of hydrogen. Two hydrogenrated dry scroll pumps 30 would be used in the hydrogen storage system. The first scroll pump 30 would pressurize hydrogen gas circulating from the low-pressure buffer vessel. The second scroll pump 30 would evacuate the gas line when needed. Three barriers of filtering would be placed in the gas loop between the powder sample in the hydrogen storage beds 14 and the surrounding environment to secure effective containment and trapping of the generated powder. A first 5 pm inline stainless steel filter 36 would be an integral part of the primary containment for each bed. A second 15 pm in-line stainless steel filter 40 would be fitted, alongside an additional 0.5 pm filter which would be placed in the exit point of the gas stream, for example, on a ventilation or evacuation route. Pneumatically-actuated automatic valves 18 would be used in the Example hydrogen storage system 10. These pneumatically-actuated valves 18 would be controlled in a LabView architecture environment where complete automation of the system was achieved. The hydrogen storage system would adopt and integrate safety pressure and temperature interlocks and fail-safe mechanisms, integrated with the valves, would allow the system to account for any abnormal operation.

[00148] During a simulated use of the example hydrogen storage system, electrical energy would be driven to the alkaline electrolyser 12 to produce hydrogen and oxygen through water separation. 99.999 % purity hydrogen produced by the alkaline electrolyser 12 would then be passed through an in-line purifier 20. The hydrogen would be directed towards the low-pressure buffer vessel 24a. The pressure, temperature and purity of the hydrogen gas would be monitored at all times.

[00149] During loading, the hydrogen produced and stored in the low-pressure buffer vessel 24b would be directed to pressure regulator 38 through the opening of valves 18. The pressure regulator 38 would be set to the appropriate pressure (about 0.05 MPa to about 0.25 MPa) and the hydrogen would be introduced to the hydrogen storage beds 14 through the opening of valves 18. Hydriding would take place immediately after hydrogen introduction, and since the phenomenon is highly exothermic, the temperature within the bed would increase. Temperature rise would be controlled through nitrogen cooling (dynamic circulation) and through adjusting the supply of hydrogen to the system.

[00150] After loading is completed, the bed would be isolated from the hydrogen storage gas loop. Remaining gas in the low-pressure buffer vessel 24b would be isolated in the buffer vessel. The quantity of the remaining hydrogen gas in the low-pressure buffer vessel would be minimized through equalling the amount of moles of hydrogen required for full loading of the beds to that produced from the electrolyser. Three safety interlocks, as described above, would be part of the hydrogen storage system process.

[00151] The unloading process would deliver the hydrogen in its gaseous form when requested by the operator. For the hydride to decompose and hydrogen to be given-off, the temperature in the hydrogen storage bed(s) would be raised to about 400 to about 450 °C. When this temperature range was reached, hydrogen pressure would be introduced in the hydrogen storage bed(s). The pressure value is directly related to the temperature of the system, and would be in the of range between about 0.05 MPa to 0.4 MPa. Hydrogen gas would be directed to the low-pressure buffer vessel 24a through the opening of valves 18. The gas would then be pressurized and directed to the high-pressure buffer vessel. Once unloading was completed or there were no more hydrogen requirements, the heaters in the hydrogen storage beds 14 would be switched off and the hydrogen in the hydrogen storage beds 14 would be cooled down, stopping any hydrogen generation. The valve 18e would be then closed and the remaining gas in the loop would be pressurized into the high-pressure buffer vessel 24b, and the low-pressure buffer vessel 24a would be evacuated. After this, all valves 18 would be closed. Any remaining gas in the line would be ventilated or collected for example, the remaining hydrogen gas may be directed back to the hydrogen storage beds 14 to be stored (absorbed by the metal hydride) for future use.

[00152] During the process, there may be a risk of overheating and, thus, over pressurizing the beds since dissociation pressure increases with temperature during dehydriding. The heaters of each bed would be rated to maximize their output at full line voltage up to about 500 °C. Thus, any heater failure would have only increased the temperature to this level which is the maximum acceptable temperature in the bed.

[00153] Hydrogen produced during unloading would leave the hydrogen storage bed(s) under temperature, but heat energy would be lost during circulation and expansion in the low-pressure buffer vessel 24a. A temperature interlock would be set such that valves to the low-pressure buffer vessel 24a could only open once the hydrogen gas temperature was below about 80 °C. A heat exchanger in high-pressure buffer vessel 24b would be used to ensure effective cooling of the hydrogen gas. Pressure interlocks would be used to ensure there was no pressure increase in the bed higher than about 0.6 MPa. If the pressure valve were to fail to open or were blocked and pressurization is detected within the bed, a pressure interlock would switch the heaters off to stop any hydrogen generation. No pressure increase higher than about 0.2 MPa would be expected in the bed (s) even under full line voltage and a blocked valve since the dissociation pressure at about 500 °C is about 0.2 MPa. Another pressure interlock would be configured to close valves 18 when pressure in high-pressure buffer 24b approached about 9.5 MPa. This would be to ensure that hydrogen in the vessel does not exceed the desired operational pressure range (about 0 MPa to about 10 MPa). This valve would have automatically opened again when the pressure in the vessel decreases below that threshold.

[00154] The unloading and electricity production processes would be synchronized. During electricity production the hydrogen from in pressure in high-pressure buffer 24b would be directed towards the fuel cell 16, though the pressure regulator 38 . Hydrogen would be consumed to produce electricity at a variable rate between 0.15 to 1.5 kg. h1 (average 0.98kg.h1). When no more hydrogen is to be unloaded from the DU beds, the hydrogen pressure in the high-pressure buffer vessel 24b would be reduced down to 1 MPa. The high-pressure buffer 24b would be then isolated and the remaining gas would be either ventilated or evacuated and collected for example, the remaining hydrogen gas may be directed back to the hydrogen storage beds 14 to be stored (absorbed by the metal hydride) for future use.

[00155] In this example, a COTS fuel cell 16 could be used. The fuel cell 16 would be configured to account for electrical failures, hydrogen / air mixing, lack of air supply, etc. and switch itself off or remain on standby made.

[00156] If pressure regulators 38 were to fail, valves 18 would be configured to automatically close, and the overpressure in the line could either be relieved through opening of valves 18 or the hydrogen could have been redirected for evacuation and collection.

[00157] For effective hydrogen storage material containment, thin, stainless steel filters would be used. A 5 pm pore size would be used for the gas flow ports and a 15 pm filter would be used close to the gas loop of each bed.

[00158] The scroll pump used would be hydrogen rated and able to accommodate a complete evacuation of the 150 litre vessel at 10 MPa without overheating. Conclusions

[00159] This study presents a new approach to hydrogen production, storage and use, offering improved hydrogen storage efficiency, by providing a full production of in situ generation of hydrogen and use of hydrogen, alongside hydrogen storage beds with improved volumetric expansion capabilities which could be particularly advantageous for use in larger scale applications. The system and methods described herein allow for a full cycle of producing, storing and releasing hydrogen to be accommodated within a unitary system.

[00160] The present inventors have found the present hydrogen storage system is capable of accommodating a relatively large amount of hydrogen storage material such that it can operate on an industrially applicable scale, safely accommodating a full cycle of hydriding and dehydriding of the hydrogen storage material, adequately protecting any reactive hydrogen storage material inside the hydrogen storage system from degradation and environmental contamination, and therefore a reduced storage capacity of the hydrogen storage system; effectively managing heat flow to enable efficient loading and unloading of hydrogen, allowing for safe operation during loading and unloading of the storage material; and providing sufficient protection from hydrogen storage material contamination for the surrounding environment.

[00161] The present inventors have surprisingly found the present hydrogen storage system can accommodate a relatively large amount of hydrogen storage material such that it can operate on an industrially applicable scale. They have also found that the system that can accommodate a full cycle of hydriding and dehydriding of the hydrogen storage material, whilst protecting any reactive hydrogen storage material inside the hydrogen storage system from degradation and environmental contamination. The hydrogen storage system also was found to effectively manage heat flow to enable efficient loading and unloading of hydrogen and to allow safe operation of the hydrogen storage solution during loading and unloading of the storage material. The modular nature of the hydrogen storage system was also surprisingly found to provide sufficient protection from metal / metal hydride contamination for the surrounding environment.

[00162] The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

[00163] While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

[00164] For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations.

[00165] Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[00166] Throughout this specification, including the claims which follow, unless the context requires otherwise, the word "comprise" and "include", and variations such as "comprises", "comprising", and "including" will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[00167] It must be noted that, as used in the specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from "about" one particular value, and / or to "about" another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or 5 to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent "about," it will be understood that the particular value forms another embodiment. The term "about" in relation to a numerical value is optional and means for example + / -10%.

Claims

1. A hydrogen storage system for producing, storing, releasing and utilising hydrogen, the hydrogen storage system comprising:an electrolyser;a hydrogen storage bed having a hydrogen storage material disposed therein; anda fuel cell;wherein the hydrogen storage system is configured to assume a loading condition and an unloading condition,wherein in the loading condition, hydrogen is produced by the electrolyser and loaded into the hydrogen storage bed by the hydrogen storage material, andwherein in the unloading condition, said hydrogen stored in the hydrogen storage bed is unloaded from the hydrogen storage bed and directed towards the fuel cell for use producing electricity.

2. A hydrogen storage system as claimed in claim 1, further comprising at least one filter positioned between the hydrogen storage bed and the electrolyser.

3. A hydrogen storage system as claimed in claim 1 or claim 2, further comprising at least one filter positioned between the hydrogen storage bed and the fuel cell.

4. A hydrogen storage system as claimed in any one of the preceding claims, further comprising a buffer vessel positioned between the electrolyser and hydrogen bed and / or positioned between the hydrogen storage bed and the fuel cell.

5. A hydrogen storage system as claimed in claim 4, wherein the hydrogen produced by the electrolyser is stored in the buffer vessel prior to loading the hydrogen storage bed.

6. A hydrogen storage system as claimed in any one of the preceding claims, further comprising a gas purification system arranged downstream of the electrolyser and prior to the hydrogen storage bed.

7. A hydrogen storage system as claimed in any one of the preceding claims, wherein the hydrogen storage bed material comprises a hydridable metal, optionally wherein the hydridable metal is a depleted uranium.

8. A hydrogen storage system as claimed in any one of the preceding claims, comprising a plurality of hydrogen storage beds.

9. A hydrogen storage system as claimed in claim 8, wherein the plurality of hydrogen storage beds is arranged in parallel.

10. A hydrogen storage system as claimed in any one of the preceding claims, wherein the hydrogen storage bed comprises:a hydrogen storage body; anda thermal transfer element comprising a fin element configured to allow the redistribution and expansion of the hydrogen storage material within the hydrogen storage body during hydrogen loading and unloading of the hydrogen storage material.

11. A hydrogen storage system as claimed in claim 10, wherein the fin element is a helical fin element.

12. A hydrogen storage system as claimed in claim 11, wherein the helical fin element has a helix angle in the range of about 1° to about 80°.

13. A hydrogen storage system as claimed in any one of claims 10 to 12, wherein the hydrogen storage body is lined with a hydrogen diffusion liner, the hydrogen diffusion liner formed from a material suitable for preventing hydrogen ingress into the hydrogen storage body.

14. A method of using a hydrogen storage system for storing and releasing hydrogen, the method comprising the steps of:a) providing a hydrogen storage system as claimed in any one of claims 1 to 13;b) producing hydrogen from the electrolyser;c) loading the hydrogen storage bed with the hydrogen;d) unloading the hydrogen from the hydrogen storage bed; ande) providing the fuel cell with the hydrogen.

15. The method as claimed in claim 14, wherein hydrogen produced by the electrolyser is directed towards a buffer vessel prior to loading the hydrogen storage bed with the hydrogen.

16. The method as claimed in any one of claims 14 or 15, wherein hydrogen unloaded from the 5 hydrogen storage bed is directed towards a buffer vessel prior to providing the fuel cell with the hydrogen.Application No: GB2406055.0Examiner: Dr Andrew WilliamsClaims searched: 1-16Date of search: 26 June 2024Patents Act 1977: Search Report under Section 17Documents considered to be relevant:Category Relevant to claims Identity of document and passage or figure of particular relevance X 1-16 JPH0672701 A (NUCLEAR FUEL IND LTD) WPI abstract, accession number: 1994-123997; figure 1; paragraphs 0008-0018. X 1-16 WO 2005 / 027305 Al (HYDROGENICS CORP) Figure 2; paragraphs 0030-0069. X 1-16 US 2024 / 0018670 Al (SPIROS) Figure 13; paragraphs 0052-0084, 0171-0191. X 1-16 CN 104037434 A (ZHONGYING CHANGJIANG INTERNAL INVEST GUARANTEE CO LTD) WPI abstract, accession number: 2014-V78021; figure 1; paragraphs 0008-0035, 0040. X 1-16 CN 115589028 A (UNIV QUZHOU) WPI abstract, accession number: 2023-08490E; figure 1; paragraphs 0077-0088.Categories:X Document indicating lack of novelty or inventive step A Document indicating technological background and / or state of the art. Y Document indicating lack of inventive step if P Document published on or after the declared priority date but combined with one or more other documents of same category. before the filing date of this invention. & Member of the same patent family E Patent document published on or after, but with priority date earlier than, the filing date of this application.Field of Search:International Classification:Subclass Subgroup Valid From C01B 0003 / 00 01 / 01 / 2006 C01B 0003 / 50 01 / 01 / 2006 C25B 0001 / 04 01 / 01 / 2021 HO IM 0008 / 065 01 / 01 / 2016 HO IM 0008 / 0656 01 / 01 / 2016

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