Systems, a dispersion unit and methods for underwater dispersion of hydrogen

Abstract

The invention relates to solutions for dispersing hydrogen resulting from leak or intentional release through a body of water (20). A dispersion unit (140) comprising a plurality of horizontally separated through-going openings (144) is arranged vertically above a hydrogen storage assembly (110) or an outlet fluidly connected to a hydrogen storage assembly (110) to disperse the leaked or released hydrogen (10) from and distribute the hydrogen vertically in the body of water (20) through the through-going openings (144).

Description

[0001] SYSTEMS, A DISPERSION UNIT AND METHODS FOR UNDERWATER DISPERSION OF HYDROGEN

[0002] Technical Field

[0003] The present disclosure relates to a system and an associated method for underwater storage of hydrogen.

[0004] Background

[0005] Storing large volumes of pressurized gas (such as hydrogen) in one or more tanks on the seabed, is advantageous in terms of safety. As there is no free oxygen or ignition source to set off a reaction the potential damages due to explosion and / or fire is basically eliminated under water. In addition, submerging the tanks in water ensures that the outside temperature variations are relatively small compared to storing pressurized tanks in air where the outside temperature variations may be significant.

[0006] One example of a submersible system for underwater storage of hydrogen is described in WO 2022194989 Al (Deep Purple AS). WO 2022194989 Al describes a solution which can be used as a back-up power system normally relying on intermittent power sources (e.g. renewable energy from wind or solar). Intermittent sources are locations that are not grid connected. Renewable energy from wind or solar is in nature intermittent and the power produced varies over time. For locations relying on power from intermittent sources, a hydrogen based energy storage unit can be used to stabilize the renewable power production or alternatively function as the main electric power source for the location. Such locations may be offshore platforms, remote islands, fish farms, coastal industry / cities, industrial use or other power users close to water / sea with varying demand for electricity.

[0007] The solution in WO 2022194989 Al is a submersible system comprising at least a first frame structure for horizontal storage of tanks with a positive buoyancy in water therein, wherein the first frame structure has a negative buoyancy in water and comprises at least two storage positions for supporting at least two tanks, wherein the storage positions are arranged side by side in one level and each storage position comprises at least one cradle for supporting the tanks from below, and wherein the system comprises a fastening device having a first and a second state, wherein: i. when in the first state, the fastening device is configured to permit positioning of a tank from above into the at least one cradle and; ii. when in the second state, the fastening device is configured to secure a tank positioned in the at least one cradle in a radial direction of the tank preventing movement of the tank in a vertical upward direction; and wherein a total buoyancy of the system when submerged in water, when tanks are positioned in each of the storage positions, is negative.

[0008] As light gases (such as hydrogen) are leaking subsea, all pressure expansion and velocity is lost in the water, and the gas rises to the surface due to gravity and generates a plume. The deeper the leakage, the wider plume. When the light gas rises above the water surface, it accelerates upwards due to its low weight. This effect creates turbulent flow mixing hydrogen and air. This turbulent flow is highly ignitable (ignitable in range 4%- 75% hydrogen) and explosive. Hydrogen concentration in this mixing zone (i.e. at the water surface) is dependent on hydrogen flow and size of plume (area on surface where hydrogen is coming up).

[0009] Referring to Figs. 1 A-1C, exemplified potential leaks from a hole of equal dimension and flow rate at water depths of 20m, 50m and 100m respectively. The smaller line above the x-axis shows the area of the explosive cloud (EC) of hydrogen and air mixture that is likely to ignite. The explosive cloud (EC) goes from having a height of around 25m in Fig. 1A, to around 10m in Fig. IB and to no ignitable cloud at all in Fig. 1C (the explosive cloud EC is thus not present in Fig. 1C). The hydrogen / air mixture at water surface (not shown) go from around 15% in Fig. 1A to below 4%, and is thus not possible to ignite in Fig. 1C.

[0010] A leakage of 1kg hydrogen per sec from a topside plant at no water depth at all may result in a massive explosion, and such plants will have exclusions zones of 100meters+ in all directions.

[0011] Summarized, it is clear that increasing the storage depth of the tanks greatly improves safety. This is a great benefit of subsea storage, but also a limiting factor as many of the potential use cases are close to shore or inland without access to such water depths.

[0012] It is therefore an objective of the invention to provide a solution which minimizes the risk of an explosive cloud of gas resulting from a leakage at a relatively shallow water depth, e.g. ~20 meters depth or shallower.

[0013] The present invention is directed to a solution that may solve or at least reduce at least one of the aforementioned problems or challenges.

[0014] Summary of the invention

[0015] The invention is defined in the attached claims.

[0016] The solution according to the invention reduce creation of an explosive cloud of hydrogen (H2) / air mixture at the surface should there be a leakage of hydrogen from a storage container subsea. The invention thus provides for the possibility of safely storing of hydrogen in subsea tanks at shallow waters in areas such as e.g. outside the coast, in lakes, rivers or artificial lakes or "pools" of water. The invention relates to a device to be arranged above a submerged gas storage system that distributes any eventual gas leakage or release from one point in the subsea gas storage system to a larger plume. I.e., the device increases the diameter of the gas leakage before the gas it travels upward in the body of water. By installing such device, the gas leakage is be spread out in the water to a much larger plume reducing the risk of explosion when being mixed with air when being mixed with the air above the surface of the water. The device is herein referred to as a dispersion unit. As used herein, the terms “water” or “body of water” shall be understood as including seawater, freshwater, any water with or without additives, or any liquid suitable for accommodating the dispersion unit and the hydrogen storage assembly.

[0017] As used herein the terms “submerged” and “underwater” are used interchangeably and have the same meaning. Both describe a position which is within a liquid, i.e. below a liquid surface.

[0018] The system for underwater storage of hydrogen according to the invention can be a backup power system for locations normally relying on intermittent power sources. The intermittent power sources may be e.g. wind or solar. Alternatively, the system can be for industrial usage, fuelling stations for land or sea traffic etc.

[0019] According to a first aspect of the disclosure it is described a system for underwater storage of hydrogen, wherein the system comprises a hydrogen storage assembly configured to be submerged in a body of water, wherein the system comprises a dispersion unit being submerged in the body of water, the dispersion unit comprising a plurality of horizontally separated through-going openings, wherein the dispersion unit is configured to disperse hydrogen leaking from the hydrogen storage assembly and release the hydrogen vertically in the body of water through the through-going openings.

[0020] The hydrogen storage assembly may comprise at least one hydrogen storage container and connecting hydrogen conduits. The connecting hydrogen conduits guiding or routing hydrogen between different hydrogen storage containers.

[0021] In other words, the dispersion unit is configured to dissipate or scatter the leaked hydrogen in the body of water, thus bringing the leaked hydrogen to become spread-out over a larger area when rising in the water column. As a result of the dispersion, the leaked hydrogen, when reaching the surface of the body of water, will be less likely to mix with ambient air to form an ignitable or combustible air-hydrogen mixture, the ignitable mixture typically having a mixing ratio of 4% to 75% hydrogen and 96% to 25% air.

[0022] In the mixing zone, i.e. the zone or region where the leaked hydrogen exits the body of water, hydrogen concentration is dependent on hydrogen mass flow, i.e. the size of the leak, and the area of the mixing zone, i.e. the area on the surface where the hydrogen is emerging. Whereas any dispersion of the leaked hydrogen will be beneficial as to mitigating the risk of a combustible hydrogen-air mixture arising, the dispersion unit should preferably be such that the rising hydrogen, when reaching the surface, is dissipated or scattered over an area resulting in a H2 / air mixture that is not ignitable, or at least significantly less ignitable.

[0023] The through-going openings may be arranged such that the hydrogen is released in the body of water in an evenly dispersed fashion.

[0024] When the system is in operation, the dispersion unit is preferably arranged vertically above the at least one hydrogen storage container. Thereby it is ensured that any hydrogen leaked from the storage container leaks towards the dispersion unit.

[0025] The dispersion unit may comprise a dispersion surface configured to be arranged horizontally or substantially horizontally in the body of water when the system is in operation.

[0026] The dispersion surface may be configured to face the hydrogen storage container to redirect any hydrogen leaked from the hydrogen storage container horizontally.

[0027] The dispersion surface may be planar or substantially planar.

[0028] The dispersion surface may be any one of quadrangular and circular.

[0029] Whereas a circular dispersion surface may be the most efficient as to dispersing the hydrogen, a quadrangular dispersion surface may be the most production-efficient form given that the plurality of hydrogen storage containers typically appears to be arranged in a rectangular block.

[0030] The plurality of through-going openings may be uniformly dispersed over the dispersion surface.

[0031] The plurality of through-going openings may each have an area within the range of 1 cm2 - 100 cm2.

[0032] A total area of the plurality of through-going openings may be within the range of 10 cm2 - 1000 cm2.

[0033] The dispersion unit may be configured to disperse the leaked hydrogen over a predefined horizontal area in the body of water.

[0034] Said predefined horizontal area may be any one of: at least 10 m2; at least 20 m2; at least 30 m2; and at least 40 m2.

[0035] The dispersion unit may be configured to trap said hydrogen leaking from the at least one hydrogen storage container prior to dispersing the leaked hydrogen in the body of water. The dispersion unit may comprise a downward facing skirt may extend along a periphery thereof.

[0036] The length of the skirt may vary and be dependent on the demands for the specific project.

[0037] According to a second aspect of the disclosure it is described a method of storing a pressurised hydrogen in a hydrogen storage assembly, comprising the steps of

[0038] - locating the hydrogen storage assembly in a body of water;

[0039] - providing a dispersion unit in the body of water vertically above the hydrogen storage assembly, wherein the dispersion unit comprises a plurality of horizontally separated through-going openings; and should a hydrogen leakage from the hydrogen storage assembly occur, dispersing the leaked hydrogen in the body of water through the through-going openings.

[0040] The hydrogen storage assembly may be located at a predefined depth within the range of 1 m-300 meters. The step of dispersing the leaked hydrogen horizontally in the body of water may comprise dispersing the leaked hydrogen over a predefined horizontal area in the body of water.

[0041] Said predefined horizontal area may be at least 1 m2.

[0042] The dispersion surface may have an aspect ratio between extension and thickness of any one of at least 0.5; at least 0.7; and at least 0.9.

[0043] In order to provide an efficient dispersion, the lateral extent of the dispersion surface should preferably be matched by its longitudinal extent.

[0044] Pressure (P) of trapped hydrogen is equal to the ambient water pressure.

[0045] 0 meters depth -> 1.0 bar

[0046] 10 meters depth -> 2.0 bar

[0047] 20 meters depth -> 3.0 bar

[0048] 50 meters depth -> 6.0 bar

[0049] 100 meters depth -> 11.3 bar

[0050] Typical pressure in storage tank: 0-350 bar

[0051] Volume of hydrogen at surface if released from tank with 35+ bar pressure at 100 meters depth

[0052] Vambient tank*Ptank P ambient

[0053] Leakage at 100 m At 100 m: Vioo=35O / l 1.3*Vtank=40*Vtank

[0054] At sea level: Vo=35O*Vtank

[0055] According to a third aspect of the disclosure, it is described a hydrogen dispersion system for guided release of hydrogen from a hydrogen storage assembly, wherein the hydrogen dispersion system comprises a hydrogen conduit fluidly connected to the hydrogen storage assembly, an outlet fluidly connected to the hydrogen conduit and a dispersion unit comprising a plurality of horizontally separated through-going openings, wherein the outlet and the dispersion unit are configured to be submerged in a body of water, and wherein the dispersion unit is configured to disperse hydrogen released from the outlet and release the hydrogen vertically in the body of water through the through-going openings.

[0056] The dispersion unit in the third aspect of the disclosure is preferably a dispersion unit as described in relation to the first and second aspects of the disclosure.

[0057] The hydrogen storage assembly may comprise at least one hydrogen storage container and connecting hydrogen conduits, and the at least one hydrogen storage container and connecting hydrogen conduits may be arranged at a surface location.

[0058] The surface location could be any location surrounded by air.

[0059] In order to prevent leakage directly to the surrounding air, the at least one hydrogen storage container and connecting hydrogen conduits may be encapsulated in a fluid-tight container. The hydrogen conduit is configured to vent leaked hydrogen from an inside of the container and out through the outlet.

[0060] Alternatively, there may be arranged a collection system above the hydrogen storage container(s) and the connecting hydrogen conduits. The hydrogen conduit is configured to vent leaked hydrogen from the funnel and out through the outlet. The hydrogen can be lead via the hydrogen conduit to the submerged outlet using gravity and / or a pump. The collection system may be in the form of a funnel or similar collection means.

[0061] In yet another alternative, the hydrogen storage container(s) and the connecting hydrogen conduits may be connected to a dump valve or a dump line. The dump valve can be fluidly connected to the hydrogen conduit and the outlet and, by opening the dump valve, hydrogen stored in the hydrogen storage container(s) and the connecting hydrogen conduits can be intentionally or controllably released through the outlet. The surface location may be onshore. Onshore could be any location on land. Alternatively, the surface location could also be on a floating unit such as a barge, or it could be a bottom-fixed offshore installation.

[0062] According to a fourth aspect of the disclosure it is described a method of guided release of hydrogen from a hydrogen storage assembly through a hydrogen dispersion system, wherein the hydrogen storage assembly comprises at least one hydrogen storage container and connecting hydrogen conduits and the hydrogen dispersion system comprises a hydrogen conduit fluidly connected to the hydrogen storage assembly, an outlet fluidly connected to the hydrogen conduit and a dispersion unit, and wherein the method comprising the steps of

[0063] - locating the at least one hydrogen storage container and the connecting hydrogen conduits at a surface location;

[0064] - locating the outlet in the body of water;

[0065] - providing the dispersion unit in the body of water vertically above the outlet, wherein the dispersion unit comprises a plurality of horizontally separated through- going openings; and

[0066] - should a hydrogen leakage from the at least one hydrogen storage container and / or the connecting hydrogen conduits occur, dispersing the leaked hydrogen in the body of water through the through-going openings.

[0067] The at least one hydrogen storage container and the connecting hydrogen conduits form part of the hydrogen storage assembly which is arranged at the surface location.

[0068] The at least one hydrogen storage container and connecting hydrogen conduits may be encapsulated in a fluid-tight container. The hydrogen conduit is configured to vent leaked hydrogen from an inside of the encapsulated fluid-tight container and out through the outlet.

[0069] According to a fifth aspect of the disclosure, it is described a method of guided release of hydrogen from a hydrogen storage assembly through a hydrogen dispersion system, wherein the hydrogen storage assembly comprises at least one hydrogen storage container and connecting hydrogen conduits and the hydrogen dispersion system comprises a hydrogen conduit fluidly connected to the hydrogen storage assembly, an outlet fluidly connected to the hydrogen conduit and a dispersion unit, and wherein the method comprising the steps of

[0070] - locating the at least one hydrogen storage container and the connecting hydrogen conduits at a surface location; locating the outlet in the body of water; - providing the dispersion unit in the body of water vertically above the outlet, wherein the dispersion unit comprises a plurality of horizontally separated through- going openings; and

[0071] - intentionally releasing hydrogen from the at least one hydrogen storage container and dispersing the released hydrogen in the body of water through the through-going openings.

[0072] There may be situations where it is desired to do emergency release, e.g. perform planned release, of hydrogen from the surface location in a safe way through the water column to disperse safely.

[0073] According to a sixth aspect of the disclosure it is described a system for underwater storage of hydrogen, wherein the system comprises a hydrogen storage assembly configured to be submerged in a body of water, wherein the system comprises a hydrogen outlet fluidly connected to the hydrogen storage assembly and a dispersion unit, the outlet and the dispersion unit being submerged in the body of water, wherein the dispersion unit comprises a plurality of horizontally separated through-going openings, and wherein the dispersion unit is configured to disperse hydrogen released from the outlet and release the hydrogen vertically in the body of water through the through-going openings.

[0074] The hydrogen storage assembly may comprise at least one hydrogen storage container and connecting hydrogen conduits, and the at least one hydrogen storage container and connecting hydrogen conduits may be submerged in the body of water.

[0075] The at least one hydrogen storage container and connecting hydrogen conduits may be encapsulated in a fluid-tight container. The hydrogen conduit may be configured to vent leaked hydrogen from an inside of the encapsulated fluid-tight container and out through the outlet.

[0076] According to a seventh aspect of the disclosure it is described a system for dispersion of hydrogen, wherein the system comprises at least one hydrogen source / supply with an outlet submerged in a body of water, wherein the system comprises a dispersion unit submerged in the body of water and wherein the dispersion unit comprises a plurality of horizontally separated through-going openings, wherein the dispersion unit is configured to disperse hydrogen released from the at least one hydrogen outlet and distribute the hydrogen vertically in the body of water through the through-going openings.

[0077] According to an eight aspect of the disclosure it is described a hydrogen storage and / or processing system comprising at least one section which is configured to be submerged in a body of water, wherein the hydrogen storage and / or processing system comprises a dispersion unit being submerged in the body of water, wherein the dispersion unit comprises a plurality of horizontally separated through-going openings, wherein the dispersion unit is configured to disperse hydrogen released from said section and distribute the released hydrogen vertically in the body of water through the through- going openings.

[0078] The section is typically a portion of the system where leaks could possibly occur. Such portions may be a submerged hydrogen storage container or piping or connection equipment between the hydrogen storage containers. Alternatively, said sections may be an outlet or an orifice at the end of a release pipe for controlled release of hydrogen from a land-based hydrogen storage and / or processing system.

[0079] According to a ninth aspect of the disclosure, it is described a dispersion unit for supporting intentional or unintentional underwater release of hydrogen from a hydrogen storage assembly, wherein the dispersion unit comprises a dispersion surface and a plurality of horizontally separated through-going openings, and wherein the dispersion unit is configured to be submerged in a body of water and located vertically above a hydrogen release location to disperse hydrogen released from the hydrogen storage assembly.

[0080] The hydrogen storage assembly can be located submerged directly below the dispersion unit or at another location, surface or submerged but with an outlet located submerged below the dispersion unit

[0081] The hydrogen release location can be a leakage point of the hydrogen storage assembly or an hydrogen outlet connected to hydrogen storage assembly.

[0082] The dispersion unit is configured to release the hydrogen vertically in the body of water through the through-going openings.

[0083] According to a tenth aspect of the disclosure, it is described a system for storage of hydrogen, wherein the system comprises a hydrogen storage assembly and a dispersion unit, wherein the dispersion unit being submerged in a body of water, the dispersion unit comprising a plurality of horizontally separated through-going openings, wherein the dispersion unit is configured to disperse hydrogen leaking from the hydrogen storage assembly and release the hydrogen vertically in the body of water through the through- going openings.

[0084] According to the tenth aspect of the disclosure, the hydrogen storage assembly is submerged in the same body of water, i.e. the same water basin, as the dispersion unit.

[0085] For example, the system may comprise an onshore tank holding the body of water, and both the hydrogen storage assembly and the dispersion unit are arranged in the body of water. It is clear that the body of water can be treated by addition of other liquids for antifouling or anti-freeze. If there is an onshore basin, chemicals such as e.g. chlorine or antibacterial substances, pH increasing / decreasing substances, coolant etc. can be added to the body of water. When the outside temperature drops to 0°C or below, the coolant may be added to the water in order to prevent the water in the basin from freezing. Since ice may damage the components in the basin, coolant (antifreeze / cooling liquid) may be added in order to prevent this. The cooling liquid or coolant may be any of glycerol, ethylene glycol or other known liquids.

[0086] The dispersion unit may be secured or connected to the hydrogen storage assembly.

[0087] Alternatively, the dispersion unit may be integrated in a roof of the hydrogen storage assembly.

[0088] In an alternative example of the tenth aspect of the disclosure, the storage assembly may be submerged in a first body of water and the dispersion unit may be submerged in a second body of water, the second body of water being different from the first body of water.

[0089] According to an eleventh aspect of the disclosure it is described a system for underwater storage of hydrogen, wherein the system comprises a hydrogen storage assembly, and wherein the system comprises a dispersion unit being submerged in a body of water, the dispersion unit comprising a plurality of horizontally separated through-going openings, wherein the dispersion unit is configured to disperse hydrogen which is leaking or hydrogen which is being intentionally released from the hydrogen storage assembly, and release the hydrogen vertically in the body of water through the through-going openings.

[0090] According to the eleventh aspect of the disclosure, the hydrogen storage assembly may be arranged in the same body of water or in another body of water than the dispersion unit. For example, the dispersion unit can be arranged in a first body of water and the hydrogen storage assembly can be arranged in a second body of water (which is different from the first body of water).

[0091] According to a twelfth aspect of the disclosure, it is described a method of dispersing pressurised hydrogen from a hydrogen storage assembly of a hydrogen storage system as defined in the tenth aspect, comprising the steps of:

[0092] - providing the hydrogen storage assembly;

[0093] - providing the dispersion unit in the body of water; and

[0094] - dispersing hydrogen which is leaking from, or which is being intentionally released from, the hydrogen storage assembly in the body of water through the through-going openings.

[0095] Above-discussed preferred and / or optional features of each aspect of the invention / disclosure may be used, alone or in appropriate combination, in the other aspects of the invention / disclosure. The claimed invention is specified in the independent claims of this application. Advantageous adaptations and versions of the claimed invention are specified in the independent claims.

[0096] Description of the drawings

[0097] Following drawings are appended to facilitate the understanding of the claimed invention:

[0098] Figs. 1A-1C show exemplified potential leaks from a hole having a diameter of 15 mm and a mass flow rate of 1 kg / s at different water depths are shown, where:

[0099] Fig. 1 A indicates that at 20 meters water depth there will be a large explosive cloud of hydrogen / air mix on surface that is likely to ignite;

[0100] Fig. IB indicates that at 50 meters water depth the size of the explosive cloud is reduced and improved compared to Fig. 1 A;

[0101] Fig. 1C indicates that at 100 meters water depth there is no cloud at all and thus it is not possible to ignite the cloud;

[0102] Fig. 2 is a perspective view from above of a system for underwater storage of hydrogen, where the system comprises hydrogen storage containers and a dispersion unit with a quadrangular dispersion surface, where the dispersion unit is arranged above the hydrogen storage containers for dispersion of a leakage of hydrogen through a plurality of through-going openings in the dispersion unit;

[0103] Fig. 3 is a perspective view from above of a system for underwater storage of hydrogen, where the system comprises hydrogen storage containers and a dispersion unit with a quadrangular dispersion surface and with a downward facing skirt extending along a periphery thereof, where the dispersion unit is arranged above the hydrogen storage containers for dispersion of a leakage of hydrogen through a plurality of through-going openings in the dispersion unit;

[0104] Fig. 4 is a side view of the system in Fig. 3;

[0105] Fig. 5 is a perspective view from below a dispersion unit with a downward facing skirt extending along a periphery thereof;

[0106] Fig. 6 is a side perspective view of a system for underwater storage of hydrogen, where the system comprises hydrogen storage containers and a dispersion unit with a circular dispersion surface with a downward facing skirt extending along a periphery thereof, where the dispersion unit is arranged above the hydrogen storage containers for dispersion of a leakage of hydrogen through a plurality of through-going openings in the dispersion unit; Fig. 7 is a perspective view from below into an interior of the dispersion unit of Fig. 6 to illustrate the circular dispersion surface;

[0107] Fig. 8 is a side view of a dispersion system for guided release of hydrogen from a hydrogen storage assembly, wherein the dispersion system comprises a hydrogen conduit fluidly connected to the hydrogen storage assembly, an outlet fluidly connected to the hydrogen conduit and a dispersion unit comprising a plurality of horizontally separated through-going openings, wherein the hydrogen storage assembly comprises a hydrogen storage container arranged on a surface location encapsulated in a fluid-tight container;

[0108] Fig. 9 is a side view of a dispersion system for guided release of hydrogen from a hydrogen storage assembly, wherein the dispersion system comprises a hydrogen conduit fluidly connected to the hydrogen storage assembly, an outlet fluidly connected to the hydrogen conduit and a dispersion unit comprising a plurality of horizontally separated through-going openings, wherein the hydrogen storage assembly comprises a submerged hydrogen storage container;

[0109] Fig. 10 is a side view of a dispersion system for guided release of hydrogen from a hydrogen storage assembly, wherein the dispersion system comprises a hydrogen conduit fluidly connected to the hydrogen storage assembly, an outlet fluidly connected to the hydrogen conduit and a dispersion unit comprising a plurality of horizontally separated through-going openings, wherein the hydrogen storage assembly comprises a hydrogen storage container arranged on a surface location with a collection system in the form of a funnel arranged above the hydrogen storage container;

[0110] Fig. 11 is a side view of a dispersion system for guided release of hydrogen from a hydrogen storage assembly, wherein the dispersion system comprises a hydrogen conduit fluidly connected to the hydrogen storage assembly, an outlet fluidly connected to the hydrogen conduit and a dispersion unit comprising a plurality of horizontally separated through-going openings, wherein the hydrogen storage assembly comprises a hydrogen storage container arranged on a surface location with a dump valve or dump line connected to the hydrogen conduit;

[0111] Fig. 12 is a side view of a system comprising an onshore tank holding the body of water, and wherein the hydrogen storage assembly and the dispersion unit are submerged in the body of water;

[0112] It should be understood, however, that the drawings are not intended to limit the claimed invention to the subject-matter depicted in the drawings.

[0113] In the drawings, like reference numerals have been used to indicate common parts, elements or features unless otherwise explicitly stated or implicitly understood by the context.

[0114] Detailed description In the following, one or more specific embodiments of the invention will be described in more detail with reference to the drawings. However, it is specifically intended that the invention is not limited to the embodiments and illustrations contained herein but includes modified forms of the embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementationspecific decisions must be made to achieve the developer’s specific goals, such as compliance with system and / or business-related constraints, which may vary from one implementation of the invention to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication and manufacture for the skilled person having the benefit of this disclosure.

[0115] Fig. 2 is a perspective view from above of a system 100 for underwater storage of hydrogen, where the system 100 comprises hydrogen storage containers 120 and a dispersion unit 140 with a quadrangular dispersion surface 142, where the dispersion unit 140 is arranged above the hydrogen storage containers 120 for dispersion of a leakage of hydrogen 10 through a plurality of through-going openings 144 in the dispersion unit 140. The leakage of hydrogen 10 will rise vertically upwards in the surrounding body of water since hydrogen is lighter than water. In other words, the dispersion unit 140 is configured to dissipate or scatter the leaked hydrogen 10 in the body of water, thus bringing the leaked hydrogen 10 to become spread-out over a larger area when rising in the water column. As a result of the dispersion, the dispersed hydrogen 14, when reaching the surface of the body of water, will be less likely to mix with ambient air to form an ignitable or combustible air-hydrogen mixture, the ignitable mixture typically having a mixing ratio of 4% to 75% hydrogen and 96% to 25% air.

[0116] In Figs. 2,3,4 and 6, reference number 10 indicates the hydrogen leaking from one or more of the hydrogen storage containers 120 and connecting hydrogen conduits 130 whereas reference number 14 indicates the hydrogen leakage after it has been dispersed by the dispersion unit 140. The connecting hydrogen conduits 130 guiding or routing hydrogen between different hydrogen storage containers 120.

[0117] In the mixing zone, see Figs.lA-lC, i.e. the zone or region where the leaked hydrogen 10 / 14 exits the body of water, hydrogen concentration is dependent on hydrogen mass flow, i.e. the size of the leak, and the area of the mixing zone, i.e. the area on the surface where the hydrogen is emerging.

[0118] Whereas any dispersion of the leaked hydrogen will be beneficial as to mitigating the risk of a combustible hydrogen-air mixture arising, the dispersion unit should preferably be such that the leaked dispersed hydrogen 14, when reaching the surface, is dissipated or scattered over an area resulting in a H2 / air mixture that is not ignitable, or at least significantly less ignitable.

[0119] The through-going openings 144 may be arranged such that the hydrogen 14 is released in the body of water in an evenly dispersed fashion.

[0120] As shown, when the system 100 is in operation, the dispersion unit 140 is arranged vertically above the at least one hydrogen storage container 120. Thereby it is ensured that any hydrogen leaked from the storage containers 120 leaks towards the dispersion unit 140.

[0121] The dispersion unit 140 comprises a dispersion surface 142 which is shown as being arranged horizontally or substantially horizontally in the body of water 20 when the system 100 is in operation. The dispersion surface 142 is on an underside of the dispersion unit 140 facing the hydrogen storage containers 120 to redirect any leaked hydrogen 10 from the hydrogen storage containers 120 horizontally.

[0122] In Fig. 2 the dispersion surface 142 shown is planar. The dispersion unit 140 is configured to disperse the leaked hydrogen 14 over a predefined horizontal area Aspersion in the body of water 20. In order to provide an efficient dispersion, the lateral extent of the dispersion surface 142 should preferably be matched by its longitudinal extent.

[0123] The plurality of through-going openings 144 are preferably uniformly dispersed over the dispersion surface 142. The plurality of through -going openings 144 each have an area, Aopening.

[0124] Fig. 3 is a perspective view from above of a system 100 for underwater storage of hydrogen, where the system 100 comprises hydrogen storage containers 120 and a dispersion unit 140 with a quadrangular dispersion surface 142 and with a downward facing skirt 145 extending along a periphery thereof, where the dispersion unit 140 is arranged above the hydrogen storage containers 120 for dispersion of a leakage of hydrogen 14 through a plurality of through-going openings 144 in the dispersion unit 140.

[0125] Most of the features of the system 100 in Fig. 3 are common with the system 100 in Fig. 2 except that the dispersion unit 140 in Fig. 3 comprises a downward facing skirt 145 extending along a periphery thereof. The skirt 145 renders possible trapping of leaked hydrogen 10 from at least one of the hydrogen storage containers 120 prior to dispersing the leaked hydrogen 14 in the body of water 20. The length of the skirt 145 may vary and be dependent on the demands for the specific project.

[0126] Fig. 4 is a side view of the system in Fig.3. Fig. 5 is a perspective view from below of a dispersion unit 140 with a downward facing skirt 145 extending along a periphery thereof. As shown in the figure, the skirt 145 is also provided with through-going openings 144 for dispersion of leaked hydrogen.

[0127] Fig. 6 is a side perspective view of a system 100 for underwater storage of hydrogen, where the system 100 comprises hydrogen storage containers 120 and a dispersion unit 140 with a circular dispersion surface (not shown since it is inside the dispersion unit 140) with a downward facing skirt 145 extending along a periphery thereof, where the dispersion unit 140 is arranged above the hydrogen storage containers 120 for dispersion of a leakage of hydrogen 14 through a plurality of through-going openings 144 in the dispersion unit 140.

[0128] Most of the features of the system 100 in Fig. 6 are common with the system 100 in Fig. 4 except that the dispersion surface (see Fig. 7) Fig. 6 is circular. As shown in Fig. 6, the skirt 145 may have through-going openings 144, however it is apparent for the skilled person that the skirt 145 do not have through-going openings 144 and that all the leaked hydrogen 10 is dispersed by the through -going openings 144 in the dispersion surface 142.

[0129] Fig. 7 is a perspective view from below into an interior of the dispersion unit 140 of Fig. 6 to illustrate the circular dispersion surface 142.

[0130] Referring to Figs. 2-6, it is further described a method of storing a pressurised hydrogen storage container 120, comprising the steps of: locating the storage container 120 in a body of water 20 at a predefined depth; providing a dispersion unit 140 in the body of water 20 vertically above the storage container 120, wherein the dispersion unit 140 comprises a plurality of horizontally separated through-going openings 144; and should a hydrogen leakage 10 from the storage container 120 occur, dispersing the leaked hydrogen 14 in the body of water 20 through the through-going openings 144.

[0131] The step of dispersing the leaked hydrogen horizontally in the body of water 20 may comprise dispersing the leaked hydrogen 14 over a predefined horizontal area Aspersion in the body of water 20.

[0132] Fig. 8 is a side view of a dispersion system for guided release of hydrogen from a hydrogen storage assembly 110, wherein the dispersion system comprises a hydrogen conduit 205 fluidly connected to the hydrogen storage assembly 110, an outlet 200 fluidly connected to the hydrogen conduit 205 and a dispersion unit 140 comprising a plurality of horizontally separated through-going openings 144, wherein the hydrogen storage assembly 110 comprises a hydrogen storage container 120 arranged on a surface location 2 encapsulated in a fluid-tight container. The storage container 120 as such is not shown in Fig. 8, but is arranged inside the box with reference no. 110. In order to prevent leakage directly to the surrounding air, the at least one hydrogen storage container 120 and connecting hydrogen conduits 130 (not shown in Fig. 8, see e.g. Fig. 2) may be encapsulated in a fluid-tight container. The hydrogen conduit 205 is configured to vent leaked hydrogen from an inside of the container, via the hydrogen conduit 205 and out through the outlet 200.

[0133] As illustrated in Fig. 8, the outlet 200 and parts of the hydrogen conduit 205 are submerged in the body of water 20. The dispersion unit 140 is configured to disperse hydrogen 14 released 10 from the outlet 200 and release the hydrogen vertically in the body of water 20 through the through-going openings 144 of the dispersion unit 140.

[0134] With reference to Fig. 8 it is described a method of guided release of hydrogen from a hydrogen storage assembly 110 through a hydrogen dispersion system, wherein the hydrogen storage assembly 110 comprises at least one hydrogen storage container 120 and connecting hydrogen conduits 130 and the hydrogen dispersion system comprises a hydrogen conduit 205 fluidly connected to the hydrogen storage assembly 110, an outlet 200 fluidly connected to the hydrogen conduit 205 and a dispersion unit 140, and wherein the method comprising the steps of locating the at least one hydrogen storage container 120 and the connecting hydrogen conduits 130 at a surface location 2; locating the outlet 200 in the body of water 20; providing the dispersion unit 140 in the body of water 20 vertically above the outlet 200, wherein the dispersion unit 140 comprises a plurality of horizontally separated through-going openings 144; and should a hydrogen leakage 10 from the at least one hydrogen storage container 120 and the connecting hydrogen conduits 130 occur, dispersing the leaked hydrogen 14 in the body of water 20 through the through-going openings 144.

[0135] Further referring to Fig. 8, it is described a method of guided release of hydrogen from a hydrogen storage assembly 110 through a hydrogen dispersion system, wherein the hydrogen storage assembly 110 comprises at least one hydrogen storage container 120 and connecting hydrogen conduits 130 and the hydrogen dispersion system comprises a hydrogen conduit 205 fluidly connected to the hydrogen storage assembly 110, an outlet 200 fluidly connected to the hydrogen conduit 205 and a dispersion unit 140, and wherein the method comprising the steps of locating the at least one hydrogen storage container 120 and the connecting hydrogen conduits 130 at a surface location 2; locating the outlet 200 in the body of water 20; providing the dispersion unit 140 in the body of water 20 vertically above the outlet 200, wherein the dispersion unit 140 comprises a plurality of horizontally separated through-going openings 144; and intentionally releasing hydrogen from the at least one hydrogen storage container 120 and dispersing the released hydrogen 14 in the body of water 20 through the through- going openings 144. As described above, the system can thus be used both for handling unintentional leaks of hydrogen stored at the surface location and for intentional, planned or controlled release of hydrogen from the surface location as there may be situations where it is desired to do emergency release, e.g. perform planned release, of hydrogen from the surface location 2 in a safe way through the water column to disperse safely.

[0136] Fig. 9 is a side view of a dispersion system for guided release of hydrogen from a hydrogen storage assembly, wherein the dispersion system comprises a hydrogen conduit fluidly connected to the hydrogen storage assembly, an outlet fluidly connected to the hydrogen conduit and a dispersion unit comprising a plurality of horizontally separated through-going openings, wherein the hydrogen storage assembly comprises a submerged hydrogen storage container. The solution in Fig. 9 is similar to the solution described in relation to Fig. 8, with the exception that the at least one hydrogen storage container 120 and connecting hydrogen conduits 130 (not shown in Fig. 9, see e.g. Fig. 2) are submerged. Said at least one hydrogen storage container 120 and connecting hydrogen conduits 130 (not shown in Fig. 9, see e.g. Fig. 2) may be encapsulated in a fluid-tight container (see box with reference number 110 in Fig. 9). The hydrogen conduit 205 is configured to vent leaked hydrogen from an inside of the container, via the hydrogen conduit 205 and out through the outlet 200. Although the hydrogen storage container(s) 120 in Fig. 9 is submerged, it may be situations where it is desirable to handle a potential leakage at another location. Such situations may be e.g. if the hydrogen storage container 120 is stored closed to shore and / or populated coast areas. Then it may be desired to guide the leak to a more remote subsea location further away from the populated area.

[0137] As shown in Fig. 9, the outlet 200 and the hydrogen conduit 205 are submerged in the body of water 20. The dispersion unit 140 is configured to disperse hydrogen 14 released 10 from the outlet 200 and release the hydrogen vertically in the body of water 20 through the through-going openings 144 of the dispersion unit 140.

[0138] Fig. 10 is a side view of a dispersion system for guided release of hydrogen from a hydrogen storage assembly 110, wherein the dispersion system comprises a hydrogen conduit 205 fluidly connected to the hydrogen storage assembly 110, an outlet 200 fluidly connected to the hydrogen conduit 205 and a dispersion unit 140 comprising a plurality of horizontally separated through -going openings 144, wherein the hydrogen storage assembly 110 comprises a hydrogen storage container 120 arranged on a surface location 2 with a collection system in the form of a funnel 210 arranged above the hydrogen storage container 120. The hydrogen conduit 205 is configured to vent leaked hydrogen from the funnel 210 and out through the outlet 200. The hydrogen can be lead via the hydrogen conduit 205 to the submerged outlet 200 using gravity and / or a pump 215.

[0139] Fig. 11 the hydrogen storage container(s) and the connecting hydrogen conduits may be connected to a dump valve 220. The dump valve 220 can be fluidly connected to the hydrogen conduit 205 and the outlet 200 and, by opening the dump valve 220, hydrogen stored in the hydrogen storage container(s) 120 and the connecting hydrogen conduits can be intentionally released 10 through the outlet 200.

[0140] Fig. 12 is a side view of a system 100 arranged on a surface location 2. The system 100 comprising an onshore tank 30 holding the body of water 20. The hydrogen storage assembly 110 and the dispersion unit 140 are submerged in the body of water 20. In other words, the hydrogen storage assembly 110 and the dispersion unit 140 are submerged in an onshore basin 30. The hydrogen storage assembly 110 comprising a frame supporting the hydrogen storage containers 120. In the land- based submerged storage of the storage assembly 110 and the dispersion unit 140 in Fig. 12, the dispersion unit 140 is shown as being integrated in an upper part or a roof of the frame of hydrogen storage assembly 110.

[0141] In the preceding description, various aspects of the invention have been described with reference to the illustrative embodiment. For purposes of explanation, specific numbers, systems and configurations were set forth in order to provide a thorough understanding of the apparatus and its workings. However, this description is not intended to be construed in a limiting sense. Various modifications and variations of the illustrative embodiments, which are apparent to person skilled in the art to which the disclosed subject-matter pertains, are deemed to lie within the scope of the present invention as defined by the following claims.

[0142] LIST OF REFERENCE NUMBERS

[0143] 1 surface of body of water

[0144] 2 surface location

[0145] 10 release / leakage of hydrogen

[0146] 14 dispersed hydrogen

[0147] 20 body of water

[0148] 30 onshore tank / onshore basin

[0149] 100 system

[0150] 110 hydrogen storage assembly

[0151] 111 frame

[0152] 120 storage container

[0153] 130 connecting hydrogen conduits

[0154] 140 dispersion unit

[0155] 142 dispersion surface

[0156] 144 through-going openings

[0157] 145 skirt

[0158] 200 outlet

[0159] 205 release pipe

[0160] 210 funnel

[0161] 215 pump

[0162] 220 dump valve / dump line

[0163] Aopening area of each through-going opening

[0164] Adispersion horizontal area of dispersion unit

[0165] EC Explosive cloud

Claims

CLAIMS1. A system (100) for underwater storage of hydrogen, wherein the system (100) comprises a hydrogen storage assembly (110) configured to be submerged in a body of water (20), characterised in that the system (100) comprises a dispersion unit (140) being submerged in the body of water (20), the dispersion unit (140) comprising a plurality of horizontally separated through-going openings (144), wherein the dispersion unit (140) is configured to disperse hydrogen (14) leaking (10) from the hydrogen storage assembly (110) and release the hydrogen vertically in the body of water (20) through the through-going openings (144).

2. The system according to claim 1, wherein the hydrogen storage assembly (110) comprises at least one hydrogen storage container (120) and connecting hydrogen conduits (130).

3. The system (100) according to claim 1 or 2, wherein the dispersion unit (140) comprises a dispersion surface (142) configured to be arranged horizontally or substantially horizontally in the body of water (20) when the system (100) is in operation.

4. The system (100) according to claim 3, wherein the dispersion surface (142) is planar or substantially planar.

5. The system (100) according to any one of claims 3 or 4, wherein the dispersion surface (142) is any one of quadrangular and circular.

6. The system (100) according to any one of claims 3-5, wherein the plurality of through-going openings (144) are uniformly dispersed over the dispersion surface (142).

7. The system (100) according to any of the preceding claims, wherein the dispersion unit (140) is configured to disperse the leaked hydrogen over a predefined horizontal area (Aspersion) in the body of water (20).

8. The system (100) according to claim 7, wherein said predefined horizontal area (Adispersion) is any one of: at least 10 m2; at least 20 m2; at least 30 m2; and at least 40 m2.

9. The system (100) according to any one of preceding claims, wherein the dispersion unit (140) is configured to trap said hydrogen (10) leaking from the hydrogen storage assembly (110) prior to dispersing the leaked hydrogen in the body of water (20).

10. The system (100) according to claim 9, wherein the dispersion unit (140) comprises a downward facing skirt (145) extending along a periphery thereof.

11. A dispersion unit (140) for supporting intentional or unintentional underwater release of hydrogen from a hydrogen storage assembly (110), characterized in that the dispersion unit (140) comprises a dispersion surface (142) and a plurality of horizontally separated through-going openings (144), and wherein the dispersion unit (140) is configured to be submerged in a body of water (20) and located vertically above a hydrogen release location (10) to disperse (14) hydrogen released from the hydrogen storage assembly (110).

12. A method of storing a pressurised hydrogen in a hydrogen storage assembly (110), comprising the steps of:- locating the hydrogen storage assembly (110) in a body of water (20);- providing a dispersion unit (140) in the body of water (20) vertically above the hydrogen storage assembly (110), wherein the dispersion unit (140) comprises a plurality of horizontally separated through-going openings (144); and- should a hydrogen leakage (10) from the hydrogen storage assembly (110) occur, dispersing the leaked hydrogen (14) in the body of water (20) through the through-going openings (144).

13. The method according to claim 12, wherein the hydrogen storage assembly (110) is located at a predefined depth within the range of 1 m-300 m.

14. The method according to any one of claims 12 or 13, wherein the step of dispersing the leaked hydrogen horizontally in the body of water (20) comprises dispersing the leaked hydrogen (14) over a predefined horizontal area (Aspersion) in the body of water (20).

15. The method according to claim 14, wherein said predefined horizontal area (Adispersion) is at least 1 m2.

16. A hydrogen dispersion system for guided release of hydrogen from a hydrogen storage assembly (110), characterised in that the hydrogen dispersion system comprises a hydrogen conduit (205) fluidly connected to the hydrogen storage assembly (110), an outlet (200) fluidly connected to the hydrogen conduit (205) and a dispersion unit (140) comprising a plurality of horizontally separated through- going openings (144), wherein the outlet (200) and the dispersion unit (140) are configured to be submerged in a body of water (20), and wherein the dispersion unit (140) is configured to disperse hydrogen (14) released (10) from the outlet (200) and release the hydrogen vertically in the body of water (20) through the through-going openings (144).

17. The hydrogen dispersion system according to claim 16, wherein the hydrogen storage assembly (110) comprises at least one hydrogen storage container (120) and connecting hydrogen conduits (130), wherein the at least one hydrogen storagecontainer (120) and connecting hydrogen conduits (130) are arranged at a surface location (2).

18. The hydrogen dispersion system according to claim 17, wherein the surface location (2) is onshore.

19. A method of guided release of hydrogen from a hydrogen storage assembly (110) through a hydrogen dispersion system, wherein the hydrogen storage assembly (110) comprises at least one hydrogen storage container (120) and connecting hydrogen conduits (130) and the hydrogen dispersion system comprises a hydrogen conduit (205) fluidly connected to the hydrogen storage assembly (110), an outlet (200) fluidly connected to the hydrogen conduit (205) and a dispersion unit (140), and wherein the method comprising the steps of:- locating the at least one hydrogen storage container (120) and the connecting hydrogen conduits (130) at a surface location (2);- locating the outlet (200) in the body of water (20);- providing the dispersion unit (140) in the body of water (20) vertically above the outlet (200), wherein the dispersion unit (140) comprises a plurality of horizontally separated through-going openings (144); and- should a hydrogen leakage (10) from the at least one hydrogen storage container (120) and / or the connecting hydrogen conduits (130) occur, dispersing the leaked hydrogen (14) in the body of water (20) through the through-going openings (144).

20. A method of guided release of hydrogen from a hydrogen storage assembly (110) through a hydrogen dispersion system, wherein the hydrogen storage assembly (110) comprises at least one hydrogen storage container (120) and connecting hydrogen conduits (130) and the hydrogen dispersion system comprises a hydrogen conduit (205) fluidly connected to the hydrogen storage assembly (110), an outlet (200) fluidly connected to the hydrogen conduit (205) and a dispersion unit (140), and wherein the method comprising the steps of:- locating the at least one hydrogen storage container (120) and the connecting hydrogen conduits (130) at a surface location (2);- locating the outlet (200) in the body of water (20);- providing the dispersion unit (140) in the body of water (20) vertically above the outlet (200), wherein the dispersion unit (140) comprises a plurality of horizontally separated through-going openings (144); and- intentionally releasing hydrogen from the at least one hydrogen storage container (120) and dispersing the released hydrogen (14) in the body of water (20) through the through-going openings (1 4).

21. A system (100) for underwater storage of hydrogen, wherein the system (100) comprises a hydrogen storage assembly (110) configured to be submerged in a body of water (20), characterised in that the system (100) comprises a hydrogen outlet (200) fluidly connected to the hydrogen storage assembly (110) and a dispersion unit (140), the outlet (200) and the dispersion unit (140) being submerged in the body of water (20), wherein the dispersion unit (140) comprising a plurality of horizontally separated through-going openings (144), and wherein the dispersion unit (140) is configured to disperse hydrogen (14) released from the outlet (200) and release the hydrogen vertically in the body of water (20) through the through-going openings (144).

22. The system (100) according to claim 21, wherein the hydrogen storage assembly (HO) comprises at least one hydrogen storage container (120) and connecting hydrogen conduits (130), wherein the at least one hydrogen storage container (120) and connecting hydrogen conduits (130) are submerged in the body of water (20).

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