GB2584324A

GB2584324A - Vehicle

Info

Publication number: GB2584324A
Application number: GB1907701.5A
Authority: GB
Inventors: Sperrin Luke; Abo Hamed Enass; Italiano Peter; O'donnell Kieran
Original assignee: H2GO Power Ltd
Current assignee: H2GO Power Ltd
Priority date: 2019-05-30
Filing date: 2019-05-30
Publication date: 2020-12-02
Anticipated expiration: 2039-05-30
Also published as: GB201907701D0; GB2584324B

Abstract

A vehicle 10, preferably an unmanned and/or autonomous vehicle for example an unmanned aerial vehicle comprises a set of structural components 100, 100A for force resistance, a propulsion system (600 fig 1) and/or an auxiliary power supply for electric power. A set of hydrogen storage devices (200, 200A fig 1) including heaters (300,300A fig 1) provides hydrogen gas to the propulsion system (600) and/or the auxiliary power supply. The hydrogen storage device (200A) comprises a pressure vessel 230A, having fluid inlet 210A and outlet 220A, and a thermally conducting network 240A coupled to a heater (300A). A hydrogen storage material in the vessel is at least partly in thermal contact with the thermally conducting network 240A. The network 240A has a lattice geometry and/or a fractal geometry in two and/or three dimensions. The hydrogen storage device (200A) provides a first structural component 100A of the set of structural components (100 fig 1). The invention is also applicable to land vehicle and watercraft.

Description

Vehicle

Field

[1] The present invention relates to hydrogen vehicles, particularly to hydrogen storage devices thereof and therefor.

Background to the invention

[2] Hydrogen is an environmentally-attractive alternative fuel to fossil fuels. Importantly, hydrogen can be produced without the use of fossil fuels, such as by the electrolysis of water using renewable energy. Hydrogen has a relatively high density of energy per unit mass and is effectively non-polluting since the main combustion product is water.

[3] Generally, hydrogen vehicles use hydrogen as onboard fuel for motive power. The propulsion systems of such hydrogen vehicles convert the chemical energy of hydrogen to mechanical energy, typically by either combusting the hydrogen in internal combustion engines or, more frequently, by reacting the hydrogen with oxygen in a fuel cell, to provide electrical power for electric motors.

[4] While hydrogen has wide potential application as a fuel, a major drawback in its utilization for vehicles has been lack of suitable storage. Conventionally, hydrogen is stored in a pressure vessel as a compressed gas under a high pressure, for example between 350 bar and 700 bar, or stored as a cryogenic liquid. However, storage of hydrogen as a compressed gas at high pressure generally involves use of large pressure vessels, limiting utilization in vehicles and/or presenting a safety risk. Further, liquid hydrogen is expensive to produce while storage of hydrogen as a liquid presents a serious safety problem and requires storage below 20 K, thus precluding utilization in vehicles, for example. Furthermore, utilization of such conventional storage, using conventional pressure vessels or liquid hydrogen, is limited by the associated infrastructure requirements, as mandated by safety and/or cost. In addition, such conventional storage typically has a relatively low hydrogen storage density, such that the conventional storage has a relatively high mass and/or large volume for a given amount of stored hydrogen, thereby increasing hydrogen consumption, decreasing range and/or reducing payload and/or load or cargo capacity of the vehicles, for example.

[5] Hence, there is a need to improve storage of hydrogen for hydrogen vehicles.

Summary of the Invention

[6] It is one aim of the present invention, amongst others, to provide a vehicle which at least partially obviates or mitigates at least some of the disadvantages of the prior art, whether identified herein or elsewhere. For instance, it is an aim of embodiments of the invention to provide a vehicle having an enhanced range and/or payload, compared with vehicles having conventional storage of hydrogen. For instance, it is an aim of embodiments of the invention to provide a hydrogen storage device for vehicles having improved safety, compared with conventional hydrogen storage.

[7] A first aspect provides a vehicle, preferably an unmanned and/or autonomous vehicle for example an unmanned aerial vehicle, UAV, the vehicle comprising: a set of structural components, arranged to provide, at least in part, a structure of the vehicle and to resist, at least in part, internal and/or external forces in one, two or three dimensions; a propulsion system, arranged to propel the vehicle, and/or an auxiliary power supply, arranged to provide electrical power to the vehicle; a set of hydrogen storage devices, including a first hydrogen storage device, and optionally a set of heaters including a first heater, wherein the set of hydrogen storage devices is arranged to provide hydrogen gas to the propulsion system and/or to the auxiliary power supply; wherein the first hydrogen storage device comprises: a pressure vessel, having a first fluid inlet and a first fluid outlet, comprising therein a thermally conducting network optionally thermally coupled to the first heater, wherein the pressure vessel is arranged to receive therein a hydrogen storage material in thermal contact, at least in part, with the thermally conducting network; and preferably, wherein the thermally conducting network has a lattice geometry and/or a fractal geometry in two and/or three dimensions; and wherein the first hydrogen storage device, preferably the pressure vessel and/or the thermally conducting network thereof, provides a first structural component of the set of structural components.

[8] A second aspect provides a charging station for charging a hydrogen storage device for a vehicle according to the first aspect.

[9] A third aspect provides a charging station assembly comprising a charging station according to the second aspect and a hydrogen storage device for a vehicle according to the first aspect.

[10] A fourth aspect provides a hydrogen storage device for a vehicle, preferably an unmanned and/or autonomous vehicle for example an unmanned aerial vehicle, UAV; wherein the vehicle comprises a set of structural components, arranged to provide, at least in part, a structure of the vehicle and to resist, at least in part, internal and/or external forces in one, two or three dimensions; and a propulsion system, arranged to propel the vehicle, and/or an auxiliary power supply, arranged to provide electrical power to the vehicle; wherein the hydrogen storage device is arranged to provide hydrogen gas to the propulsion system and/or to the auxiliary power supply and wherein the hydrogen storage device comprises: a pressure vessel, having a first fluid inlet and a first fluid outlet, comprising therein a thermally conducting network optionally thermally coupled to the first heater, wherein the pressure vessel is arranged to receive therein a hydrogen storage material in thermal contact, at least in part, with the thermally conducting network; and preferably, wherein the thermally conducting network has a lattice geometry and/or a fractal geometry in two and/or three dimensions; and wherein the hydrogen storage device, preferably the pressure vessel and/or the thermally conducting network thereof, provides a first structural component of the set of structural components.

Detailed Description of the Invention

[11] According to the present invention there is provided a vehicle, as set forth in the appended claims. Also provided is a charging station for a vehicle and a charging station assembly comprising a hydrogen storage device for a vehicle and a charging station. Other features of the invention will be apparent from the dependent claims, and the description that follows.

Vehicle [12] The first aspect provides a vehicle, preferably an unmanned and/or autonomous vehicle for example an unmanned aerial vehicle, UAV, the vehicle comprising: a set of structural components, arranged to provide, at least in part, a structure of the vehicle and to resist, at least in part, internal and/or external forces in one, two or three dimensions; a propulsion system, arranged to propel the vehicle, and/or an auxiliary power supply, arranged to provide electrical power to the vehicle; a set of hydrogen storage devices, including a first hydrogen storage device, and optionally a set of heaters including a first heater, wherein the set of hydrogen storage devices is arranged to provide hydrogen gas to the propulsion system, and/or to the auxiliary power supply; wherein the first hydrogen storage device comprises: a pressure vessel, having a first fluid inlet and a first fluid outlet, comprising therein a thermally conducting network optionally thermally coupled to the first heater, wherein the pressure vessel is arranged to receive therein a hydrogen storage material in thermal contact, at least in part, with the thermally conducting network; and preferably, wherein the thermally conducting network has a lattice geometry and/or a fractal geometry in two and/or three dimensions; and wherein the first hydrogen storage device, preferably the pressure vessel and/or the thermally conducting network thereof, provides a first structural component of the set of structural components.

[13] In this way, a range and/or payload of the vehicle is enhanced, since the hydrogen is stored in the hydrogen storage material, having a higher hydrogen storage density compared with conventional storage of hydrogen. That is, per unit mass and/or unit volume, the first hydrogen storage device may store more hydrogen compared with conventional high pressure storage and/or cryogenic storage. Hence, for a given amount of stored hydrogen, a mass and/or a size of the first hydrogen storage device is relatively reduced, enabling an increased payload and/or a decreased hydrogen consumption. Additionally and/or alternatively, for a given mass and/or volume of the first hydrogen storage device, an amount of stored hydrogen is relatively increased, enabling an increased range of the vehicle and/or an increased power output of the auxiliary power supply. In this way, a safety of hydrogen storage is improved, since the hydrogen is stored by the hydrogen storage material at a relatively low pressure, rather than as a highly compressed gas at a relatively high pressure or a cryogenic liquid. For example, the hydrogen stored by the hydrogen storage material may be stored at a pressure of just 5 bar while conventionally hydrogen may be stored as a compressed gas under a high pressure, for example between 350 bar and 700 bar. In this way, safety is improved since the hydrogen may be stored in the hydrogen storage device at a relatively lower pressure. For example, a hydrogen storage density of 30 g per litre for the hydrogen storage device is equivalent to storing hydrogen as a compressed gas at a pressure of about 700 bar. For example, a relatively higher hydrogen storage density of 50 g per litre for the hydrogen storage device is equivalent to storing hydrogen as a compressed gas at a pressure of about 1,300 bar, which is precluded for most or all vehicle scenarios, due to safety at least. Increasing the hydrogen storage density further to 100 g per litre for the hydrogen storage device is effectively beyond a practical limit for storing hydrogen as a compressed gas. In addition, since the hydrogen is stored at a relatively low pressure, a shape of the pressure vessel may be modified compared with a conventional high pressure cylindrical pressure vessel having dished ends, such that the hydrogen storage device may provide the first structural component. Furthermore, the range may be increased also compared with Li-ion polymer batteries, for a given mass, for example by up to 85% for a UAV and with a higher payload. In addition, a lifetime of the first hydrogen storage device may be increased compared with Li-ion polymer batteries, for example by a factor of 3, and/or a recharging time may be reduced, for example by a factor of 10. Additionally, a cost saving of more than 60% may be achieved using the first hydrogen storage device, compared with Li-ion polymer batteries. That is, by storing the hydrogen using the hydrogen storage material in the pressure vessel of the first hydrogen storage device, a hydrogen storage capacity is improved while a storage pressure is reduced, compared with conventional storage of hydrogen, thereby enhancing safety while increasing a range and/or a payload and/or decreasing a fuel consumption of the vehicle. Since the first hydrogen storage device provides the first structural component, the first hydrogen storage device thus is an integral part of a structure of the vehicle. In this way, a structural integrity of the vehicle is improved while a mass of the vehicle is reduced, thereby increasing a range and/or a payload and/or decreasing a fuel consumption of the vehicle.

Vehicle [14] In one example, the vehicle comprises and/or is a hydrogen vehicle, using hydrogen as onboard fuel, at least in part, for motive power. In one example, the vehicle is a hybrid hydrogen/electric vehicle using hydrogen as onboard fuel, at least in part, for motive power and stored electrical power, for example from batteries, at least in part, for motive power.

[15] In one example, the vehicle is an aircraft, for example a fixed wing aircraft,a rotary wing aircraft (also known as rotorcraft) or an airship. Advantageously, a range and/or payload of the aircraft may be increased, as described previously, compared with conventional hydrogen storage, for example. Furthermore, a safety of the aircraft may be enhanced, thereby reducing risk due to collision and/or crash landing, for example. In one example, the vehicle is a watercraft, such as a surface watercraft, for example a boat, a ship or a hovercraft, or a submersible watercraft, for example a submarine. Advantageously, a range of the watercraft may be increased and/or a hydrogen consumption reduced, as described previously, compared with conventional hydrogen storage, for example. In one example, the vehicle is a land craft. In one example, the land craft is a two-wheeled vehicle such as a scooter or a motorbike, a three-wheeled vehicle, a four-wheeled vehicle such as an automobile, a van, a bus, a truck, a forklift truck, a military vehicle, or a vehicle having more than two axles, such as a lorry, a tram or a train. Advantageously, a range of the land craft may be increased and/or a hydrogen consumption reduced, as described previously, compared with conventional hydrogen storage, for example.

Unmanned and autonomous vehicles [16] The vehicle is preferably an unmanned and/or autonomous vehicle for example an unmanned aerial vehicle, UAV. Generally, an unmanned vehicle (also known as an uncrewed vehicle) is a vehicle without a person on board. An unmanned vehicle can either be a remote controlled vehicle (also known as a remote guided vehicle) or an autonomous vehicle, capable of sensing its environment and navigating autonomously. Unmanned vehicles includes unmanned ground vehicle (UGV), such as the autonomous car; unmanned aerial vehicle (UAV) (also known as a drone), unmanned surface vehicle (USV), for the operation on the surface of the water; unmanned underwater vehicle (UUV) sometimes known as underwater drone, for the operation underwater; remotely operated underwater vehicle (ROUV); autonomous underwater vehicle (AUV); and unmanned spacecraft, both remote controlled ("unmanned space mission') and autonomous ("robotic spacecraft" or "space probe').

Generally, autonomous vehicles are capable of sensing their environment and navigating autonomously. For example, autonomous cars (also known as self-driveing cars) combine a variety of sensors to perceive their surroundings, such as RADAR, LIDAR, SONAR, GPS, odometry and inertial measurement units, while advanced control systems interpret the sensory information to identify appropriate navigation paths, as well as obstacles.

[17] Preferably, the vehicle is a UAV. An unmanned aerial vehicle (UAV), commonly known as a drone, is an aircraft without a human pilot on board. UAVs are a component of an unmanned aircraft system (UAS); which include a UAV, a ground-based controller, and a system of communications between the two. The flight of UAVs may operate with various degrees of autonomy: either under remote control by a human operator or autonomously by onboard computers. Compared with manned aircraft, UAVs were originally used for missions too 'dull, dirty or dangerous' for humans. While they originated mostly in military applications, their use is rapidly expanding to commercial, scientific, recreational, agricultural, and other applications, such as policing, peacekeeping, and surveillance, product deliveries, aerial photography, smuggling, and drone racing. Civilian UAVs now vastly outnumber military UAVs.

UAVs typically fall into one of six functional categories (although multi-role airframe platforms are becoming more prevalent): target and decoy (providing ground and aerial gunnery a target that simulates an enemy aircraft or missile); reconnaissance (providing battlefield intelligence); combat (providing attack capability for high-risk missions); logistics (delivering cargo); research and development (improve UAV technologies); civil and/or commercial UAVs (for example, agriculture, aerial photography, data collection). In one example, the vehicle is a logistics and/or a civil and/or commercial UAV. UAVs may be classified according to gross take off weight (GTOVV): micro air vehicle (MA \O (the smallest UAVs that can weigh less than 1g); miniature UAV (also called SUAS) (approximately less than 25 kg); and heavier UAVs (i.e. 25 kg or more). In one example, the UAV is a miniature UAV or a heavier UAV. In one example, the UAV has a GTOW in a range from 2.5 kg to 2500 kg, preferably in a range from 5 kg to 500 kg, more preferably in a range from 10 kg to 125 kg, most preferably in a range from 12.5 kg to 50 kg; and/or a payload in a range from 0.5 kg to 500 kg, preferably in a range from 1 kg to 250 kg, more preferably in a range from 2 kg to 100 kg, most preferably in a range from 3 kg to 25 kg; and/or a flight time (i.e. a maximum flight duration) in a range from 0.5 hours to 24 hours, preferably in a range from 0.75 hours to 12 hours, more preferably in a range from 1 hour to 4 hours. Particularly, adoption of UAVs requires increased payload and/or flight time, as provided by the vehicle according to the first aspect.

Structural components [18] The vehicle comprises the set of structural components, arranged to provide, at least in part, the structure of the vehicle and to resist, at least in part, internal and/or external forces in one, two or three dimensions. That is, the set of structural components provide the structural integrity of the vehicle.

[19] Typically, the set of structural components of an aircraft includes an airframe comprising a fuselage and a fixed wing and/or a rotary wing. Fuselage components include stringers, longerons, ribs, bulkheads, frames and formers. The main component of a fixed wing is a wing spar. Typically, the set of structural components of a surface watercraft include a hull comprising a bottom, sides, a deck and/or a keel, and optionally a superstructure. Typically, the set of structural components of a submersible watercraft include a hull, for example a single hull or a double hull. Typically, the set of structural components of a land craft includes a chassis. The chassis, also known as a vehicle frame, is the main supporting structure of the vehicle and functions to, inter alia, support the vehicle's mechanical components and body, deal with static and dynamic loads, without undue deflection or distortion, vertical and torsional twisting transmitted by going over uneven surfaces, transverse lateral forces caused by road conditions, side wind, and steering the vehicle, torque from the engine and transmission, longitudinal tensile forces from starting and acceleration, as well as compression from braking and/or sudden impacts from collisions. In other words, the first structural component performs one or more of these functions. Types of chassis include unibody (also known as monocoque), ladder type frame, X-Type frame, off set frame, off set with cross member frame and perimeter frame.

Propulsion system and/or auxiliary power supply [20] The vehicle comprises the propulsion system, arranged to propel the vehicle, and/or the auxiliary power supply, arranged to provide electrical power to the vehicle. Typically, propulsion systems of hydrogen vehicles convert the chemical energy of hydrogen to mechanical energy, typically by either combusting the hydrogen in internal combustion engines or by reacting the hydrogen with oxygen in a fuel cell, to provide electrical power for electric motors. In one example, the propulsion system comprises a heat engine, for example an internal combustion engine, and/or a fuel cell. Fuel cells are preferred. Typically, auxiliary power supplies of vehicles provide electrical power for starter motors, engines or turbines, control and/or safety systems, heating, ventilation and air conditioning (HVAC) and/or backup power.

[21] In one example, the propulsion system and/or the auxiliary power supply comprises: a set of electrical generators, including a first electrical generator, configured to generate electricity using the hydrogen gas, selected from a group comprising a fuel cell and an electrical generator comprising a heat engine, for example an internal combustion engine. In this way, electrical power may be generated by the set of electrical generators, using the hydrogen gas released from the hydrogen storage material as a fuel. It should be understood that the set of electrical generators is coupled to the set of hydrogen storage devices via respective fluid couplings.

[22] In one example, the first electrical generator is an electrical generator comprising a heat engine, for example comprising an internal combustion engine arranged to combust the hydrogen and a generator, moved by the internal combustion engine. Other electrical generators and/or heat engines are known.

[23] In one example, the first electrical generator is the fuel cell, selected from a group comprising a proton exchange membrane fuel cell, PEMFC, an alkaline fuel cell, AFC, and a phosphoric acid fuel cell, PAFC. In this way, electrical power may be generated without moving parts, compactly, at relatively low temperatures and/or efficiently. PEMFCs, also known as polymer electrolyte membrane (PEM) fuel cells, are generally constructed from membrane electrode assemblies (MEA) which include electrodes, electrolyte, catalyst and gas diffusion layers. Typically, an ink of catalyst, carbon, and electrode are deposited onto a solid electrolyte and carbon paper is hot pressed on either side to protect the inside of the cell and also act as electrodes. The fundamental part of the PEMFC is a triple phase boundary (TPB) where the electrolyte, catalyst, and reactants mix and thus where cell reactions occur. The membrane must not be electrically conductive so half reactions do not mix. Generally, operating temperatures above 100 °C are desired so the water byproduct becomes steam and water management becomes less critical in PEMFC design. Suitable PEMFCs are available from Ballard Power Systems Inc. (Burnaby, Canada) such as the FCgen and FCvelocity series, and Horizon Fuel Cell Technologies (Singapore) such as the Aerostacks and H-Series. AFCs (also known as Bacon fuel cells) are cheap to manufacture and have efficiencies of up to 70%. PAFCs use liquid phosphoric acid as an electrolyte, are CO2 tolerant and have efficiencies of up to 70%. Since PAFCs typically operate at 150 to 200 °C, expelled steam may be used for air and water heating. Suitable PAFCs are available from Doosan Fuel Cell America, Inc. (CT, USA) and Fuji Electric Co. Ltd (Tokyo, Japan).

Hydrogen storage device [24] The vehicle comprises the set of hydrogen storage devices, including the first hydrogen storage device, and optionally the set of heaters including the first heater, wherein the set of hydrogen storage devices is arranged to provide hydrogen gas to the propulsion system and/or to the auxiliary power supply.

[25] In one example, the set of hydrogen storage devices includes M hydrogen storage devices, wherein M is a natural number of at least 1, for example 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more. In this way, a hydrogen storage capacity of the vehicle may be matched to a requirement, for example.

Hydrogen storage density [26] In one example, the first hydrogen storage device has a hydrogen storage density of at least 0.01 wt.%, at least 0.1 wt.%, at least 1.0 wt.%, at least 1.8 wt.%, preferably at least 2.4 wt.%, more preferably at least 3.3 wt.%, most preferably at least 5.5 wt.%, by wt.% of the first hydrogen storage vessel. In one example, the first hydrogen storage device has a hydrogen storage density of at most 50 wt.%, at most 40 wt.%, at most 30 wt.%, at most 25 wt.%, preferably at most 20 wt.%, more preferably at most 15 wt.%, most preferably at most 12.5 wt.%, by wt.% of the first hydrogen storage vessel. In this way, the hydrogen storage density may exceed energy storage in a Li-ion polymer battery (about 1.8 wt.% hydrogen storage density equivalent) and may exceed hydrogen storage density in a conventional compressed hydrogen cylinder at 300 bar, thereby increasing a range and/or a payload of the vehicle, as described previously.

Hydrogen storage density 1.8 wt9/0 2.4 wt9/0 3.3 wt.% 5.5 wt9/0 Core system 5.9 kg 5.9 kg 5.9 kg 5.9 kg Fuel cell 4.2 kg 4.2 kg 4.2 kg 4.2 kg H2 + tank (700 5.4 kg 4.1 kg 3.0 kg 1.8 kg bar) Payload 0.0 kg 1.3 kg 2.4 kg 3.6 kg Table 1: Example of increase in payload for a 15.5 kg gross take off weight (GTOVV) hexicopter (i.e. an aircraft) including a 2.2 kW fuel cell for various hydrogen storage densities, according to exemplary embodiments. A hydrogen storage density of 1.8 wt.% is equivalent to a Li-ion polymer battery while a hydrogen storage density of 5.5 wt.% is equivalent to a 700 bar compressed hydrogen cylinder.

Comparative example Example Li-ion polymer battery Hydrogen storage density 5.5 wt.% Li-ion polymer battery 9.6 kg -Core system 5.9 kg 5.9 kg Fuel cell - 4.2 kg H2 + tank (700 bar) - 1.8 kg Payload 0.0 kg 3.6 kg Table 2: Comparison of a 15.5 kg gross take off weight (GTOVV) hexicopter (i.e. an aircraft) for a 1 hour flight time: a Li-ion polymer 6S16P (2.5 Ah/cell) system comparative example compared with a 2.2 kW fuel cell and a hydrogen storage density of 5.5 wt.% according to an exemplary embodiment. The hydrogen-fuelled aircraft has a 3.6 kg payload while the Li-ion polymer powered aircraft has a zero payload for the 1 hour flight duration.

Hydrogen storage capacity [27] In one example, the first hydrogen storage device has a hydrogen storage capacity in a range from 1 g to 2,500 g, preferably in a range from 5 g to 1,000 g, more preferably in a range from 20 g to 500 g. Typically, 1 kg hydrogen may provide about 16.65 kWh of electrical energy, assuming a 50% efficiency in converting from chemical energy of the hydrogen to electrical energy, for example via a fuel cell. In this way, the first hydrogen storage device may provide an amount of electrical energy, via a fuel cell for example, in a range from 0.01665 kWh to 41.625 kWh, preferably in a range from 0.08325 kWh to 16.65 kWh, more preferably in a range from 0.333 kWh to 8.325 kWh.

Pressure vessel [28] The first hydrogen storage device comprises the pressure vessel, having the first fluid inlet and the first fluid outlet. In contrast to conventional pressure vessels for storage of compressed hydrogen gas, the pressure vessel is designed according to a relatively low operating pressure of at most 100 bar, preferably at most 75 bar, more preferably at most 50 bar, even more preferably at most 25 bar, most preferably at most 10 bar. Generally, a conventional pressure vessel for high pressure storage of hydrogen (i.e. 350 bar to 700 bar) is cylindrical, having dished ends. In contrast, since the pressure vessel is designed according to a relatively low operating pressure, a shape of the pressure vessel may be varied, while still maintaining an integrity and/or safety factor thereof. For example, the pressure vessel may be cuboidal such as a square based prism, thereby increasing space utilisation and/or enabling stacking thereof. For example, the pressure vessel may shaped aerodynamically (for example, for aircraft and land craft) or hydrodynamically (for water craft), such that the pressure vessel may provide and/or conform with an outer surface of the vehicle. In one example, the first hydrogen storage device, for example the pressure vessel, has at most two planes of symmetry, preferably having a shape arranged to reduce drag (i.e. shaped aerodynamically or hydrodynamically), in use. In one example, the pressure vessel has a moment of inertia I > 1/2 MR2 about its central axis, where M is the mass of the pressure vessel and R is the mean radius of the pressure vessel, normal to the central axis. It should be understood that the moment of inertia 1 is determined for the empty pressure vessel shell i.e. not including the thermally conducting network, the hydrogen storage material, hydrogen, the first inlet and the first outlet. In one example, the pressure vessel comprises an insulating layer, arranged to thermally insulate the pressure vessel. In this way, control of a temperature of the pressure vessel is improved. In one example, the pressure vessel comprises a double wall (i.e. an inner pressure wall and an outer wall, for example an outer skin). In this way, a gap between the double wall may provide an insulating layer and/or comprise an insulating layer. In one example, one or more components of the vehicle are arranged in the gap within the double wall. In one example, the outer wall may be shaped aerodynamically or hydrodynamically and/or the inner wall is cylindrical, having dished ends. In this way, a wall thickness of the inner wall may be reduced for a given operating pressure, while the outer wall reduces drag. In addition, the outer wall may provide a physical buffer, reducing damage to the inner wall. In one example, the pressure vessel comprises a passageway arranged, for example axially, to receive the first heater therein. In one example, the passageway is a blind passageway. In one example, the passageway is a through passageway. In one example, the first heater comprises a Joule heater, for example a cartridge heater, and/or a recirculating heater, for example recirculating liquid, and the pressure vessel is arranged, for example comprising a passageway, to interchangeably receive the Joule heater and the recirculating heater therein and/or thereon. For example, the pressure vessel may comprise a through passageway, arranged to receive a cartridge heater inserted therein through an end of the passageway and the opposed end of the passageway may be closed, for example with an insulating plug.

Alternatively, the cartridge heater and the plug may be removed and fluid couplings instead fitted to the ends, such that a recirculating liquid, such as heated coolant (i.e. a heating fluid) from a fuel cell to heat the thermally conducting network, may be pumped therethrough. In this way, flexibility for heating and/or cooling the thermally conducting network is provided. In one example, the first hydrogen storage device comprises a passageway, wherein the first hydrogen storage device is arrangeable in: a first configuration to receive a Joule heater in the passageway; and a second configuration to receive a flow of a liquid through the passageway. [29] It should be understood that the first fluid inlet and the first fluid outlet are for the inlet of hydrogen into the pressure vessel and outlet of hydrogen from the pressure vessel, respectively, such as provided, at least in part, by a perforation (i.e. an aperture, a passageway, a hole) through a wall of the pressure vessel. In one example, the first fluid inlet and the first fluid outlet are a gas inlet and a gas outlet, respectively. In one example, the first fluid inlet and the first fluid outlet are provided by and/or via the same perforation. In one example, the pressure vessel has a plurality of gas inlets and/or gas outlets, including the first gas inlet and the first gas outlet respectively. In one example, the first fluid inlet and the first fluid outlet comprise releasable couplings, thereby providing coupling thereto and uncoupling therefrom, for example repeatedly, of corresponding couplings. Suitable releasable couplings (also known as fittings or connectors) include push-fit fittings, bayonet fittings, quick connect fittings, cylinder connections to BS341 or DIN 477, hose end fittings, pipe end fittings, tube end fittings and screw fittings. Other releasable couplings are known. In one example, the first hydrogen storage device comprises one or more of a thermocouple, a thermowell, a valve, a flashback arrestor, a filter such as a sorbent protection filter, a pressure sensor and a mass flow controller (MFC), for example inline with the first releasable fluid inlet coupling. A valve is generally movable between an open position in which hydrogen can enter or exit the vessel, and a closed position in which the vessel is sealed. In one example, the valve is electrically and/or pneumatically actuatable. In this way, the valve may be actuated remotely, for example via a controller. In one example, the MFC is electrically actuatable. In this way, the MFC may be actuated remotely, for example via a controller, to control flow of hydrogen therethrough.

Hydrogen storage material [30] The pressure vessel is arranged to receive therein the hydrogen storage material in thermal contact, at least in part, with the thermally conducting network.

[31] As an alternative to storage of hydrogen as a compressed gas or as a liquid, certain metals and alloys permit reversible storage and release of hydrogen (i.e. hydrogen storage materials). These hydrogen storage materials, due to their high hydrogen-storage efficiency, including low hydrogen loss during cycling and/or reduced heat loss between cycles (thermal efficiency), are considered superior to conventional methods of hydrogen storage. Particularly, by storing hydrogen as a solid hydride, a greater volumetric storage density may be achieved than possible for hydrogen as a compressed gas or as a liquid. In addition, hydrogen storage as a solid hydride presents a reduced safety risk compared with storing hydrogen as a compressed gas or as a liquid.

[32] For example, solid-phase metal or alloy materials can store large amounts of hydrogen by absorbing hydrogen with a high density and by forming a metal hydride under a specific temperature/pressure or electrochemical conditions, and hydrogen can be released by changing these conditions.

[33] Generally, an efficiency of exchange of hydrogen into and out of such storage materials may be enhanced or inhibited by their respective heat transfer capabilities. Particularly, hydriding (also known as hydrogen absorption) is exothermic while dehydriding (also known as hydrogen desorption) is endothermic. Therefore, moving heat within such storage materials or maintaining preferred temperature profiles across and through volumes of such storage materials becomes a crucial factor in such metal or alloy hydride hydrogen storage materials. As a general matter, release of hydrogen from the crystal structure of a metal hydride requires input of some level of energy, normally heat. Placement of hydrogen within the crystal structure of a metal, metal alloy, or other storage system generally releases energy, normally heat, providing a highly exothermic reaction of hydriding or placing hydrogen atoms within the crystal structure of the hydrideable alloy.

[34] The heat released from hydriding of hydrogen storage metals or alloys may be removed. Heat ineffectively removed can cause the hydriding process to slow down or terminate. This becomes a serious problem which prevents fast charging. During fast charging, the hydrogen storage material is quickly hydrogenated and considerable amounts of heat are produced. The hydrogen storage device described herein, particularly the thermally conducting network, provides for effective removal of the heat caused by the hydriding of the hydrogen storage alloys to facilitate fast charging of the hydride material. Approaches to this issue have been reported, for example in US 2003/0209149 and in "Heat transfer techniques in metal hydride hydrogen storage: A review", Afzal et al., International Journal of Hydrogen Energy, 2017, 42(52), 30661-30682.

[35] The hydrogen storage devices described herein allow for rapid charging and discharging of hydrogen gas while may also be relatively compact. Typically, heat is applied to discharge hydrogen gas, and heat is released and needs to be absorbed (for example, cooling applied) during hydrogen charging. The hydrogen storage devices allow for rapid heating and/or cooling, particularly via the thermally conducting network, which means less heat is wasted to the surroundings during operation, since the charging and discharging times are relatively short. The hydrogen storage devices also enable highly targeted heating, which avoids unnecessary heat loss and associated wasted energy.

[36] The hydrogen storage material in the device of the invention can be a compound that is a metal hydride. Typically, the elemental metal reacts with hydrogen to form a metal hydride,

for example:

Mg + H2 -> MgH2 [37] Generally, this reaction may be driven forwards by increasing hydrogen pressure.

[38] Release of hydrogen occurs when heat is applied to the hydride. For example, for magnesium hydride and at 1 bar of pressure, MgH2 decomposes to Mg metal and hydrogen at 287 °C: In one example, the hydrogen storage material comprises an.AE.,..J-AQy, A In one example, the hydrogen storage material comprises an the hydrogen storage material comprises 7.m /-MgH2 -/ Mg + H2 [39] In one example, the hydrogen storage material comprises one or more selected from: a rc:0..r.:: tor Etx.,-:::.nr,:e ancliczr hydrogen storage the hydrogen storage material material comprises an Ae,:ak,,i, an AB!A comprises o hydride hydride:.NBFB, hydride:1*:,<H) hydride (0%.:H2). hydride(E3H0 f.froup:::-.; hydride hydride hydride n3 hydride hydride;S:H: : In one example, the hydrogen storage material comprises one or more metal hydrides selected from MgH2, NaAIH4, LiAIH4, LiH, LaNi5H6, TiFeH2, palladium hydride PdHX, LiNH2, LiBH4 and NaBH4.

MgH2, NaAIH4, LiAIH4, LiH and/or LaNi51-16 are preferred. In one example, the hydrogen storage material comprises a mixture of two or more of these metal hydrides. These different metal hydrides may have different storage and/or release rates. Hence, a mixture of two or more of these metal hydrides may be selected for desired storage and/or release rates, for example under different conditions, and/or to provide relatively more constant storage and/or release rates under different conditions. In one example, the hydrogen storage material comprises a dopant such as a catalyst and/or an additive. For example, Ti and/or Zr may be used as catalytic dopants to improve kinetics of hydrogen storage and/or release, such as of sodium alanate. Although alkali metal alanates were known as non-reversible 'chemical hydrides', catalysed reversibility offers the possibility of a new family of low-temperature hydrides. For example, the alkali metal alanate-complex hydride, NaAIH4, readily releases and absorbs hydrogen when doped with a TiCl3 or Ti-alkoxide catalysts. There is currently ongoing research looking into optimisation of these catalysts in terms of their type, doping process and mechanistic understanding. Generally any appropriate transition or rare-earth metal can be used as catalysts, for example Ti, Zr, V, Mn, Fe, Ni, Co, Cr, Nb, Ge, Ce, La, Nd, Pd, Pr, Zn, Al, Ag, Ga, In and/or Cd. Additives include C, which improves thermal transfer of the hydrogen storage material. In one example, the hydrogen storage material is provided as particles (for example, in a powder form). In one example, the particles are microparticles, having a D50 or a D90 of at most 500 pm, at most 250 pm, at most 100 pm or at most 50 pm. In one example, the particles are microparticles having a D50 or a D10 of at least 1 pm, at least 5 pm, at least pm or at least 25 pm. In one example, the particles are nanoparticles having a D50 or a D90 of at most 500 nm, at most 250 nm, at most 100 nm or at most 50 nm. In one example, the particles are nanoparticles having a D50 or a D10 of at least 1 nm, at least 5 nm, at least 10 nm or at least 20 nm. In one example, the particles are a mixture of particles of different sizes, for example a mixture of microparticles and nanoparticles, thereby having a bimodal particle size distribution. In this way, a packing efficiency for example a density and/or a surface area of the particles may be increased, thereby increasing storage of hydrogen and/or a rate of storage of hydrogen respectively. In one example, the hydrogen storage material is processed, for example by attrition such as ball milling, to reduce a particle size thereof and/or a particle size distribution thereof and/or to incorporate a dopant and/or an additive.

[40] In one example, the pressure vessel comprises a lid (also known as a cover or a blanking plate, for example for an access hatch or an aperture in a wall of the pressure vessel) sealing coupled thereto and/or thereon, thereby providing a sealed pressure vessel around the thermally conducting network. The hydrogen storage material is advantageously added, generally in powder form, before the lid is sealing coupled to the pressure vessel. For example, if the hydrogen storage material is in powder form, the powder may be poured between arms of the thermally conducting network and optionally, into a foam to partially (i.e. at least 25%, preferably at least 35%, more preferably at least 45% by volume of voids), in a majority (i.e. at least 50%, preferably at least 60%, more preferably at least 70%, most preferably at least 80% by volume of voids), substantially (i.e. at least 90%, preferably at least 95%, more preferably at least 97.5% by volume of voids) and/or completely fill the pressure vessel. By filling the voids substantially with the powder, a hydrogen storage capacity is increased. Conversely, by filling the voids partially with the powder, heat transfer with the thermally conducting network may be improved. This filling may generally be carried out in an inert atmosphere environment, such as under argon, or other inert gas, before sealing the lid on the pressure vessel. Depending on the scale of manufacture, this may be carried out in a glove box. Slight agitation, for example vibration, can be advantageous, to ensure the powder percolates through the thermally conducting network and/or foam. In one example, the hydrogen storage device comprises an agitator, for example a vibrator, mechanically coupled to the pressure vessel and/or the thermally conductive network, arranged to agitate, for example vibrate, the pressure vessel and/or the thermally conductive network to thereby increase a filling efficiency of the pressure vessel with the hydrogen storage material.

[41] In use, during storage of hydrogen, hydrogen may be received into the pressure vessel of the first hydrogen storage device via the first fluid inlet, for example from a hydrogen gas generator, as described below. Preferably, the first hydrogen storage device is initially in a fully discharged state. When the hydrogen comes into contact with the hydrogen storage material, a temperature of the hydrogen storage material increases due to the exothermic absorption (i.e. hydriding) reaction of the hydrogen storage, as described previously. Heat from the exothermic reaction is conducted via the thermally conducting network, thereby attenuating the increase in the temperature. Optionally, a first cooler may be activated to further attenuate the increase in the temperature and subsequently, deactivated when a set low temperature threshold is reached (for example 20 °C). A valve inline with the first fluid inlet may be opened, to admit the hydrogen, and closed, to contain the hydrogen, for example when a pressure within the pressure vessel reaches, for example stabilises, at predetermined operating pressure (for example 10 bar). Depending on a type of hydrogen storage material, kinetics of absorption may be different and thus this step of storage of the hydrogen may be modified accordingly. For example, to accelerate storage of hydrogen, absorption thereof may be preferred at higher temperatures, for example of at least 100 °C, to favour kinetics of hydriding.

[42] In use, during release of hydrogen (i.e. desorption), a reverse process to storage occurs. A valve inline with the first fluid outlet may be opened, to allow exit of the hydrogen therethrough, for example to an electrical generator. As hydrogen is released from the hydrogen storage material, the temperature thereof decreases due to the endothermic desorption, as described previously. The first heater heats the thermally conducting network and hence the hydrogen storage material, for example as activated by a temperature measurement of the thermally conducting network using a thermocouple. The first heater may be deactivated once a set high temperature threshold is reached (for example 80 °C). The valve may be then closed when the pressure reaches, for example stabilises at, a predetermined pressure is reached (for example 1 bar).

Thermally conducting network [43] The pressure vessel comprises therein the thermally conducting network thermally coupled to the first heater. In one example, a face of the thermally conducting network is in thermal contact (and hence thermally coupled to) the first heater. In one example, the first heater is integrally formed with and/or in the thermally conducting network, at least in part. For example, the first heater may be embedded within (i.e. internal to) the thermally conducting network.

[44] The thermally conducting network may be formed from any suitable thermally conducting material for example a metal such as aluminium, copper, respective alloys thereof such as brass or bronze alloys of copper and/or stainless steel. Preferred materials also do not react with and/or are not embrittled by hydrogen and/or the hydrogen storage material, while having sufficient strength to maintain a structural integrity of the thermally conducting network. In one example, the thermally conducting network comprises a coating to reduce reaction with and/or embrittlement by hydrogen.

[45] Preferably, the thermally conducting network has a lattice geometry and/or a fractal geometry in two and/or three dimensions.

[46] In one example, the thermally conducting network has a lattice geometry and/or a fractal geometry in two and/or three dimensions (i.e. mutually orthogonal dimensions). It should be understood that such geometries comprise a plurality of nodes, having thermally conducting arms (i.e. generally elongated members) therebetween, with voids (i.e. gaps, space) between the arms. Such geometries, particularly the fractal geometry, provide relatively high surface area to volume ratios, enables especially efficient heat transfer to and from the hydrogen storage material. In one example, the fractal geometry is selected from a group consisting of a Gosper Island, a 3D H-fractal, a Quadratic Koch Island, a Quadratic Koch surface, a Von Koch surface, a Koch Snowflake, a Sierpinski carpet, a Sierpinski tetrahedron, a Mandelbox, a Mandelbulb, a Dodecahedron fractal, a Icosahedron fractal, a Octahedron fractal, a Menger sponge and a Jerusalem cube. Certain fractal geometries, such as Gosper islands, allow for a plurality of individual repeat unit blocks to be fabricated and then assembled together in a tessellation (i.e. assembled together with no overlaps or gaps). This enables a plurality of channels to be provided in the thermally conducting network through the hydrogen storage device, whereby each channel has a high surface area, is of the same construction but does not leave wasted space between repeat units. In one example, an effective density (also known as lattice volume ratio) of the lattice geometry is uniform in one, two or three dimensions (i.e. mutually orthogonal dimensions). In one example, an effective density of the lattice geometry is non-uniform in one, two or three dimensions (i.e. mutually orthogonal dimensions). It should be understood that a uniform effective density in a particular dimension provides a constant void fraction, between arms of the lattice geometry, in the particular dimension. Conversely, it should be understood that a non-uniform effective density in a particular dimension provides a non-constant void fraction, between arms of the lattice geometry, in the particular dimension. A higher effective density will lead to faster heat conduction due to a higher thermally conducting material content. For example, the effective density may increase or decrease in the particular dimension, for example radially. In this way, the thermally conducting network may be designed, for example optimised, for a particular pressure vessel geometry so as to improve, for example optimise, heat transfer to and/or from the hydrogen storage material via the thermally conducting network. In one example, an effective density of the lattice geometry is uniform in a first dimension, for example axially, and non-uniform in mutually orthogonal second and third dimensions, for example radially. While the surface area to volume ratios of lattice geometries, for example square lattice geometries such as three-dimensional cages, are relatively lower than of fractal geometries having the same volumes, forming and/or fabrication of lattice geometries is relatively less complex and/or costly and hence may be preferred. In one example, the lattice geometry is Bravais lattice for example a triclinic lattice such a primitive triclinic lattice; a monoclinic lattice such as a primitive triclinic lattice or a base-centred triclinic lattice; an orthorhombic lattice such as a primitive orthorhombic lattice a base-centred orthorhombic lattice, a body-centred orthorhombic lattice or a face-centred orthorhombic lattice; a tetragonal lattice such as a primitive tetragonal lattice or a body-centred tetragonal lattice; a hexagonal lattice such as a primitive hexagonal lattice or a rhombohedral primitive lattice; or a cubic lattice such as a primitive cubic lattice, a body-centred cubic lattice or a face-centred cubic lattice. Other lattices are known. Hence, these Bravais lattices, for example define a plurality of regularly-arranged nodes having thermally conducting arms therebetween. In one example, the thermally conducting arms have a cross sectional dimension (for example a diameter or a width) in a range from 0.1 mm to 10 mm, preferably in a range from 0.25 mm to 5 mm, more preferably in a range from 0.5 mm to 2.5 mm and/or a length in range from 0.5 mm to 50 mm, preferably in a range from 1 mm to 25 mm, more preferably in a range from 2 mm to 10 mm. In this way, heat transfer of the thermally conducting network may be controlled by selecting an effective density and/or a surface area of the thermally conducting network.

[47] In one example, the thermally conducting network is formed, at least in part, by 3D printing (i.e. additive manufacturing), for example by selective laser melting (SLM), thereby enabling forming of complex shapes in three dimensions having internal voids, for example. In one example, the thermally conducting network is formed, at least in part, by casting such as investment casting, moulding such as injection moulding and extrusion. Other additive manufacturing processes are known. In one example, the thermally conducting network is formed, at least in part, by fabrication and/or machining such as milling, turning or drilling. Other subtractive manufacturing processes are known. In one example, the thermally conducting network comprises fluidically interconnected passageways therein, for flow therethough of a fluid, such as a heating fluid and/or a coolant, preferably a liquid for example a recirculating liquid. In this way, heating and/or cooling of the thermally conducting network may be accelerated.

[48] In one example, the thermally conducting network is thermally coupleable to an external surface of the vehicle. In this way, the external surface may provide a heat sink so as to remove heat from the thermally conducting network and hence cool the hydrogen storage material, for example during charging.

[49] In one example, the thermally conducting network is thermally coupleable to the propulsion system and/or to the auxiliary power supply. In this way, excess heat from the propulsion system and/or the auxiliary power supply may be supplied to the thermally conducting network and hence heat the hydrogen storage material, for example during release.

[50] In one example, the thermally conducting network is alternately thermally coupleable to an external surface of the vehicle and to the propulsion system and/or to the auxiliary power supply. In this way, charging and release of the hydrogen storage material may be improved. Foam

[51] In one example, the hydrogen storage device comprises a thermally-conducting foam, for example a metal foam, attached to (i.e. thermally coupled to, in thermal contact with) the thermally conducting network. The inventors have found that such a foam aids heat transfer to and from the hydrogen storage material. It is known that such a foam has a high internal surface area. In one example, the foam comprises and/or is an open-celled foam, preferably an open-celled metal foam (also known as a metal sponge. Open-cell metal foams are generally manufactured by foundry or powder metallurgy. In the powder method, "space holders" are used; they occupy the pore spaces and channels. In casting processes, foam is typically cast with an open-celled polyurethane foam skeleton. The inventors have found that the hydrogen storage material may be placed in the spaces (i.e. voids, lumens, pores, cells) in the foam and the hydrogen storage material retains its ability to store and release hydrogen whilst at the same time benefiting from the enhanced rate of thermal transfer brought about by the high surface area of the foam. It should be understood that a foam pore size (i.e. cell size) is larger than a size of the hydrogen storage material, for example particles thereof. In one example, a ratio of the foam pore size to a particle size is at least 5:1, for example at least 10:1, for example 20:1, wherein sizes (i.e. foam pore size and particle size) are measurements in one dimension, for example diameter. In one example, the foam comprises and/or is a metal foam, preferably an open-celled metal foam, formed from aluminium, copper, stainless steel, nickel or zinc (or combination alloys including those metals). Aluminium foam is especially preferred. The thermally conducting network preferably contains metal foam in the spaces in the network. The voids in the metal foam contain the hydrogen storage material. It has been found that the metal foam in the fractal network provides excellent transfer of heat to and from the thermoelectric heater/cooler and the hydrogen storage material.

Unfilled volume [52] In one example, the hydrogen storage device is arranged to be oriented horizontally or vertically, in use. In one example, the thermally conducting network partially fills an internal volume of the pressure vessel, of at least 50 %, preferably of at least 60%, more preferably of at least 70% by volume of the pressure vessel, thereby defining an unfilled volume above the thermally conducting network. In one example, the unfilled volume acts as a buffer, providing a reservoir of hydrogen during charging and similarly during release, for example to account for kinetics thereof In one example, the pressure vessel comprises a mesh or a perforated sheet, arranged to cover an open area of the thermally conducting network (i.e. not thermally coupled to the pressure vessel, for example), to thereby retain the hydrogen storage material in the voids defined within the thermally conducting network.

Heater [53] The power supply optionally comprises the set of heaters including the first heater. In one example, the power supply comprises the set of heaters including the first heater and the thermally conducting network is thermally coupled to the first heater. By heating the first heater, heat is transferred to the thermally conducting network thermally coupled thereto. In turn, heat is transferred to the hydrogen storage material in thermal contact, at least in part, with the thermally conducting network. In this way, the hydrogen storage material is heated by the first heater, via the thermally conducting network, thereby causing hydrogen to be released from the hydrogen storage material. In one example, the first heater is positioned inside the pressure vessel. In one example, the first heater is positioned outside of the pressure vessel.

Positioning the first heater outside the pressure vessel simplifies certain aspects of the assembly of the device and allows simpler access for electrical wiring. In one example, the first heater comprises and/or is a thermoelectric heater and/or a Joule heater. Other heaters are known. In one example, the power supply comprises a thermocouple connected to the first heater, for example via a proportional-integral-derivative (PID) control. In this way, a temperature of the first heater may be controlled. In one example, the first heater comprises and/or is a cartridge heater or an insertion heater. Generally, cartridge heaters are elongated cylinders including electrical resistive wire, for example embedded in magnesium oxide. Suitable cartridge heaters and insertion heaters are available from Watlow (MO, USA). In one example, the first heater is inserted into a passageway formed in and/or provided by the thermally conducting network. In one example, the first heater is integrated into the thermally conducting network, for example integrally formed therewith. In this way, a heating efficiency of the thermally conducting network is improved. In one example, the power supply comprises a battery, preferably a rechargeable battery for example a Li-ion polymer battery, arranged to provide electrical power to the first heater.

[54] In one example, the first hydrogen storage device comprises a set of heater/coolers, including the set of heaters, including a first heater/cooler, comprising the first heater. By cooling the first heater/cooler, heat is transferred from the thermally conducting network thermally coupled thereto. In turn, heat is transferred from the hydrogen storage material in thermal contact, at least in part, with the thermally conducting network. In this way, the hydrogen storage material is cooled by the first heater/cooler, via the thermally conducting network, thereby allowing hydrogen to be stored in the hydrogen storage material. In other words, the first heater/cooler can, in a space-efficient manner, enable heat to be removed from the hydrogen storage material during the hydrogen storage phase, and heat to be supplied to the hydrogen storage material during hydrogen release. In one example, the first heater/cooler is positioned inside the pressure vessel. In one example, the first heater/cooler is positioned outside of the pressure vessel. Positioning the first heater/cooler outside the pressure vessel simplifies certain aspects of the assembly of the device and allows simpler access for electrical wiring. Thermoelectric heater and/or cooler devices can be very closely controlled (i.e. accurately, precisely and/or responsively), which providing control to a high degree of accuracy, precision and/or short response times. The heater of the first heater/cooler may be as described above with respect to the first heater. In one example, the cooler of the first heater/cooler comprises and/or is a heat sink, optionally with active cooling by air propelled by a fan or by a cooling fluid (e.g. water) being propelled by a pump. In one example, the first heater/cooler comprises and/or is a Peltier device or other device that makes use of thermoelectric cooling and heating. Devices of this type are commonly referred to as a Peltier heat pump, a solid state refrigerator, or a thermoelectric cooler (TEC). A thermoelectric heater and cooler device may be used together with a heat sink with optional active cooling (e.g. active cooling by air propelled by a fan or active cooling by a cooling fluid (e.g. water) being propelled by a pump). Application of heat or removal of heat on the side of the thermoelectric device that is not thermally coupled to the thermally conducting network enhances the ability of the thermoelectric device to heat and cool the thermally conducting network. In one example, the first heater/cooler (e.g. a thermoelectric heater and cooler) is in thermal contact with the thermally conducting network. As the two are in thermal contact, heat can efficiently be passed from one to the other. The heat can pass in either direction -heating the thermally conducting network or cooling it. The contact between the heater/cooler module and the thermally conducting network need not be direct physical contact. In some embodiments, there are intervening materials, such as a wall of the pressure vessel. In such an embodiment, the intervening material must continue to allow for good thermal contact between the heater/cooler module and the thermally conducting network, such that heat can pass efficiently from one to the other. Suitable thermoelectric heater and/or cooler devices are known to the person skilled in the art and they are available commercially from most electronics suppliers, such as CUI Inc (OR, USA). In one example, the first hydrogen storage device comprises one or more of thermoelectric heaters and/or coolers on a base to provide a Peltier heater/cooler assembly, wherein the thermally conducting network is thermally coupled (for example, attached) to the Peltier heater/cooler assembly. For example, the thermally conducting network may be 3D printed onto the heater/cooler assembly. Optionally, foam (for example metal foam, as described below) may be attached to the thermally conducting network, for example by application of an appropriate amount of compression. Alternatively, the foam may be attached by a physical bond for example by soldering, brazing and/or welding the thermally conducting network and foam together. In such an arrangement, it is preferred for the solder and/or filler to have high thermal conductivity, which is the case for most solder and filler materials.

[55] In one example, the first heater comprises a Joule heater and/or a recirculating heater, preferably wherein the first hydrogen storage device, for example the pressure vessel, is arranged to interchangeably receive the Joule heater and the recirculating heater therein and/or thereon, as described above.

First structural component [56] The first hydrogen storage device, preferably the pressure vessel and/or the thermally conducting network thereof, provides the first structural component of the set of structural components. In this way, the first hydrogen storage device, preferably the pressure vessel and/or the thermally conducting network thereof, stores hydrogen and contributes to a structural integrity of the vehicle. In one example, the propulsion system and/or the auxiliary power supply is coupled, for example releasably coupled, to the first hydrogen storage device. In this way, the first hydrogen storage device may be uncoupled from the propulsion system and/or from the auxiliary power supply, for example for charging and the propulsion system and/or the auxiliary power supply recoupled to another first hydrogen storage device. In one example, a second structural component of the set of structural components is coupled, for example releasably coupled, to the first hydrogen storage device. In this way, modularity of the vehicle and/or upgradeability of the vehicle may be provided. In one example, the first hydrogen storage device comprises a major portion, for example by volume and/or by mass, of the vehicle, for example at least 50 %, at least 55 %, at least 60 % or at least 65 % by volume and/or by mass of the vehicle. In this way, the vehicle may be built around the first hydrogen storage device.

[57] In one example, the vehicle is an aircraft, for example a fixed wing aircraft or a rotary wing aircraft, and wherein the first structural component defines an airframe, a fuselage, a fixed wing and/or a part thereof, as described above. In one example, the hydrogen storage device provides a first structural component, particularly a fixed wing, of the set of structural components of the vehicle. In one example, a wall of the pressure vessel of the hydrogen storage device provides an aerofoil, thereby defining upper, lower, leading and trailing edges, of the fixed wing. In one example, the pressure vessel comprises a tube having a circular cross-section, arranged to receive a first heater therein, providing a wing spar. In one example, the thermally conducting network has a lattice geometry in three-dimensions. In one example, the thermally conducting network is formed, at least in part, by 3D printing. In one example, the thermally conducting network is thermally coupled to an external surface of the vehicle by being thermally coupled to an internal surface of the pressure vessel. In one example, the thermally conducting network is thermally coupled to the tube, providing the wing spar. In one example, the lattice geometry is a body-centred cubic lattice.

[58] In one example, the vehicle is a watercraft, such as a surface watercraft or a submersible watercraft, and wherein the first structural component defines a hull or part thereof, as described above.

[59] In one example, the vehicle is a land craft and wherein the first structural component defines a chassis or part thereof, as described above.

Controller [60] In one example, the vehicle comprises a controller configured to control the first heater based, at least in part, on a power output of the propulsion system and/or of the auxiliary power supply. In this way, release of hydrogen from the hydrogen storage material may be pre-emptively controlled, for example increased, so as to fulfil the predicted rate of energy usage by the propulsion system and/or by the auxiliary power supply, thereby reducing latency of the release of the hydrogen. Conversely, release of hydrogen from the hydrogen storage material may be pre-emptively controlled, for example decreased, so as to still fulfil the predicted rate of energy usage by the propulsion system and/or by the auxiliary power supply, thereby reducing surplus hydrogen release. In one example, the controller is configured to control the set of heaters, as described with respect to the first heater, collectively and/or independently. In this way, respective heaters of the first set of heaters may be controlled in unison and/or individually, thereby improving granularity of control.

[61] In one example, the controller is configured to control the first heater based, at least in part, on a predicted rate of power output of the propulsion system and/or of the auxiliary power supply. In this way, the rate of hydrogen release may be matched to the rate and/or the predicted rate of usage of energy usage by the propulsion system and/or of the auxiliary power supply, thereby reducing hydrogen consumption, since surplus hydrogen release may be avoided.

[62] In one example, the controller is configured to control a cooler, as described previously, based, at least in part, on a predicted rate of energy usage by the propulsion system and/or by the auxiliary power supply. In this way, release of hydrogen from the hydrogen storage material may be pre-emptively controlled, as described with respect to the first heater mutatis mutandis.

[63] In one example, the controller is configured to determine, for example calculate or estimate, a predicted energy usage by the propulsion system and/or by the auxiliary power supply (i.e. predicted power demand). For example, the controller may determine the predicted rate of energy usage by the propulsion system and/or by the auxiliary power supply by learning energy requirements of the vehicle, for example by applying machine learning algorithms to the vehicle's energy usage. In one example, the controller is configured to obtain the energy requirements of the vehicle by measuring the vehicle's energy usage.

[64] In one example, the controller is configured to iteratively determine the predicted rate of energy usage by the propulsion system and/or by the auxiliary power supply, for example using a feedback loop, [65] In one example, the controller is configured to determine, for example calculate or estimate, the predicted rate of energy usage by the propulsion system and/or by the auxiliary power supply using a generalized linear model (GLM), a random forest, logistic regression, a support vector machine, K-nearest neighbours, a decision tree, AdaBoost, XGBoost, a neural network for example a convolutional neural network, time-series classification, a recurrence plot, a linear mixed model, or an ensemble of two or more thereof. XGBoost and GLM are preferred. For example, the controller may comprise a computer device including 32 x 2.4 GHz processors and 32 GB RAM and computations may be performed with R using GLM and/or XGBoost; alternatively and/or additionally with Python, using Keras, Theanos and/or TensorFlow.

[66] In this way, by determining a predicted rate of energy usage by the propulsion system and/or by the auxiliary power supply, the controller may control the power supply dynamically, responsive to changes in an actual rate of energy usage by the propulsion system and/or by the auxiliary power supply, for example using a feedback loop. In this way, the rate of hydrogen gas generation may be matched to the rate and/or the predicted rate of usage of electrical power and/or the availability of energy for electrolysis, thereby improving an efficiency of hydrogen consumption.

Charging station [67] The second aspect provides a charging station for charging a hydrogen storage device for a vehicle according to the first aspect. In one example, the charging station is arranged to charge a plurality of hydrogen storage devices, for example simultaneously. In one example, the charging station comprises a manifold coupleable to a plurality of hydrogen storage devices. In one example, the charging station comprises a cooling system, arranged to cool a hydrogen storage device during charging thereof. In one example, the cooling system comprises a fan, a bath, a cooling jacket and/or a recirculating coolant system.

Vehicle assembly [68] The third aspect provides a charging station assembly comprising a charging station according to the second aspect and a hydrogen storage device for a vehicle according to the first aspect.

Hydrogen storage device [69] The fourth aspect provides a hydrogen storage device for a vehicle, preferably an unmanned and/or autonomous vehicle for example an unmanned aerial vehicle, UAV; wherein the vehicle comprises a set of structural components, arranged to provide, at least in part, a structure of the vehicle and to resist, at least in part, internal and/or external forces in one, two or three dimensions; and a propulsion system, arranged to propel the vehicle, and/or an auxiliary power supply, arranged to provide electrical power to the vehicle; wherein the hydrogen storage device is arranged to provide hydrogen gas to the propulsion system and/or to the auxiliary power supply and wherein the hydrogen storage device comprises: a pressure vessel, having a first fluid inlet and a first fluid outlet, comprising therein a thermally conducting network optionally thermally coupled to the first heater, wherein the pressure vessel is arranged to receive therein a hydrogen storage material in thermal contact, at least in part, with the thermally conducting network; and preferably, wherein the thermally conducting network has a lattice geometry and/or a fractal geometry in two and/or three dimensions; and wherein the hydrogen storage device, preferably the pressure vessel and/or the thermally conducting network thereof, provides a first structural component of the set of structural components.

[70] The hydrogen storage device and/or the vehicle may be as described with respect to the first aspect.

Definitions [71] Throughout this specification, the term "comprising" or "comprises" means including the component(s) specified but not to the exclusion of the presence of other components. The term "consisting essentially of or "consists essentially of means including the components specified but excluding other components except for materials present as impurities, unavoidable materials present as a result of processes used to provide the components, and components added for a purpose other than achieving the technical effect of the invention, such as colourants, and the like.

[72] The term "consisting of or "consists of means including the components specified but excluding other components.

[73] Whenever appropriate, depending upon the context, the use of the term "comprises" or "comprising" may also be taken to include the meaning "consists essentially of or "consisting essentially of', and also may also be taken to include the meaning "consists of or "consisting of'.

[74] The optional features set out herein may be used either individually or in combination with each other where appropriate and particularly in the combinations as set out in the accompanying claims. The optional features for each aspect or exemplary embodiment of the invention, as set out herein are also applicable to all other aspects or exemplary embodiments of the invention, where appropriate. In other words, the skilled person reading this specification should consider the optional features for each aspect or exemplary embodiment of the invention as interchangeable and combinable between different aspects and exemplary embodiments.

Brief description of the drawings

[75] For a better understanding of the invention, and to show how exemplary embodiments of the same may be brought into effect, reference will be made, by way of example only, to the accompanying diagrammatic Figures, in which: [76] Figure 1 is a CAD exploded, perspective view of a vehicle according to an exemplary embodiment; [77] Figure 2 is a CAD axial cross-section of a hydrogen storage device of the vehicle of Figure 1, arranged in a first configuration; [78] Figure 3 is a CAD axial cross-section of the hydrogen storage device of the vehicle of Figure 1, arranged in a second configuration; [79] Figure 4 schematically depicts a cutaway, perspective view of a simulation of the of the hydrogen storage device of the vehicle of Figure 1; [80] Figure 5 is a graph of flight time as a function of payload for exemplary embodiments and for a comparative example; [81] Figure 6A is a schematic axial cross-section of a hydrogen storage device for a vehicle according to an exemplary embodiment and Figures 6B to 6D are schematic transverse cross-sections of the hydrogen storage device of Figure 6A; [82] Figures 7A to 7C schematically depict thermally conducting networks for a hydrogen storage device for a vehicle according to an exemplary embodiment; [83] Figure 8A is a photograph of a foam for a hydrogen storage device for a vehicle according to an exemplary embodiment; and Figure 8B is a schematic view of a hydrogen storage device for a vehicle according to an exemplary embodiment, in more detail; [84] Figure 9A is a plan elevation view of a hydrogen storage device for a vehicle according to an exemplary embodiment; and Figure 9B is a side cross-sectional view of the hydrogen storage device of Figure 9A; [85] Figure 10 is a CAD cutaway perspective view of a hydrogen storage device for a vehicle according to an exemplary embodiment; [86] Figure 11 is a CAD axial cross-section of the hydrogen storage device of Figure 10; [87] Figure 12 is a CAD radial cross-section of the hydrogen storage device of Figure 10; [88] Figure 13 is an alternative CAD radial cross-section of the hydrogen storage device of Figure 10; [89] Figure 14 is a CAD cutaway perspective view of a hydrogen storage device for a vehicle according to an exemplary embodiment; [90] Figure 15 is a CAD axial cross-section of the hydrogen storage device of Figure 14; [91] Figure 16 is a CAD radial cross-section of a thermally conducting network of the hydrogen storage device of Figure 14; [92] Figure 17 schematically depicts Bravais lattices for a thermally conducting network; [93] Figure 18 is a CAD perspective view of a hydrogen storage device for a vehicle according to an exemplary embodiment; [94] Figure 19 is a CAD axial cross-section of the hydrogen storage device of Figure 18; [95] Figure 20 is a CAD axial cross-section of a hydrogen storage device for a vehicle according to an exemplary embodiment; [96] Figure 21 is a CAD perspective view of a vehicle according to an exemplary embodiment; [97] Figure 22 is a CAD perspective view of the vehicle of Figure 21, in more detail; [98] Figure 23 is a CAD cutaway perspective view of a vehicle according to an exemplary embodiment; [99] Figure 24 is a CAD perspective cross-section view of hydrogen storage device for a vehicle according to an exemplary embodiment; [100] Figure 25 is a CAD cross-section view of the hydrogen storage device for a vehicle of Figure 24; and [101] Figure 26 is a CAD perspective view of a charging station assembly according to an exemplary embodiment.

Detailed Description of the Drawings

Figure 1 is a CAD exploded, perspective view of a vehicle 10 according to an exemplary embodiment. In this example, the vehicle 10 is an unmanned aerial vehicle (UAV), particularly a quad copter. The vehicle 10 comprises: a set of structural components 100, arranged to provide, at least in part, a structure of the vehicle 10 and to resist, at least in part, internal and external forces in one, two or three dimensions; a propulsion system 600 (comprising four propulsion sub-systems 600A, 600B, 600C, 600D), arranged to propel the vehicle 10; a set of hydrogen storage devices 200, including a first hydrogen storage device 200A, and optionally a set of heaters 300 including a first heater 300A, wherein the set of hydrogen storage devices 200 is arranged to provide hydrogen gas to the propulsion system 600; wherein the first hydrogen storage device 200A comprises: a pressure vessel 230A, having a first fluid inlet 210A and a first fluid outlet 220A, comprising therein a thermally conducting network 240A (not shown) thermally coupled to the first heater 300A, wherein the pressure vessel 230A is arranged to receive therein a hydrogen storage material in thermal contact, at least in part, with the thermally conducting network 240A; and preferably, wherein the thermally conducting network 240A has a lattice geometry in three dimensions; and wherein the first hydrogen storage device 200A, particularly the pressure vessel thereof, provides a first structural component 100A of the set of structural components 100. In this example, the vehicle 10 does not comprise an auxiliary power supply 700, which is additional and/or alternative to the propulsion system 600.

[102] In this example, the propulsion system 600 is releasably coupled to the first hydrogen storage device 200A. In this example, the first hydrogen storage device 200 comprises a set of 4 female coupling members arranged to receive corresponding male coupling members of detachable rotor arms (i.e. the four propulsion sub-systems 600A, 600B, 600C, 600D) of the vehicle 10. In this example, the first hydrogen storage device 200A comprises a major portion, of at least 65 % by mass of the vehicle.

[103] Figure 2 is a CAD axial cross-section of a hydrogen storage device 200A of the vehicle 10 of Figure 1, arranged in a first configuration. Figure 3 is a CAD axial cross-section of the hydrogen storage device 200A of the vehicle 10 of Figure 1, arranged in a second configuration. In this example, the first hydrogen storage device 200A comprises a passageway 250A, wherein the first hydrogen storage device 200A is arrangeable in: a first configuration to receive a Joule heater in the passageway 250A; and a second configuration to receive a flow of a liquid through the passageway 250A. In the first configuration, a cartridge heater (not shown) is insertable into the passageway 250A through an end thereof and the opposed end of the passageway 250A is closed, with an insulating plug 260A. In the second configuration, the cartridge heater and the plug 260A are removed and fluid couplings 270A, 280A instead fitted to the ends, such that a recirculating liquid, such as coolant from a fuel cell, may be pumped therethroug h. [104] In this example, the hydrogen storage device 200A is arranged to be oriented horizontally, in use. In this example, the pressure vessel 230A is generally cylindrical, having dished ends. In this example, the passageway, provided by a tube having a circular cross-section, extends between the dished ends longitudinally, offset from an axis of the pressure vessel 230A. In this example, the thermally conducting network 240A partially fills an internal volume of the pressure vessel 230A, particularly a region of the internal volume extending across about 75% of a diameter the pressure vessel, thereby completely surrounding the tube, such that an unfilled volume UV above the thermally conducting network 240A is defined. In this example, the thermally conducting network 240A is thermally coupled to at least a part of an internal surface of the pressure vessel 230A and an external surface of the tube. In this example, the unfilled volume UV acts as a buffer, providing a reservoir of hydrogen during charging and similarly during release, for example to account for kinetics thereof.

[105] Figure 4 schematically depicts a cutaway, perspective view of a simulation, particularly by finite element analysis (FEA) the hydrogen storage device of the vehicle of Figure 1. In this example, the pressure vessel is generally cylindrical, having a wall thickness of 2 mm, and hemispherical dished ends, having a wall thickness of 1.5 mm. In this example, the pressure vessel is formed from a material having a yield stress at 100° C of 181 MPa. In this example, a maximum stress at an operating pressure of 20 bar is 61 MPa, giving a safety factor of about 3. In this example, a maximum stress at an operating pressure of 5 bar is 15.2 MPa, giving a safety factor of about 11.9. Also shown is the deformed pressure vessel 230A' and deformed passageway 240A', following simulated yield.

[106] Figure 5 is a graph of flight time as a function of payload for exemplary embodiments and for a comparative example. In this example, the vehicle is a hexicopter UAV, as described with respect to Table 1. The comparative example is powered by a Li-ion polymer 6S16P (2.5 Ah/cell) system, as described with respect to Table 2. As the hydrogen storage density is increased, longer flight times and higher payloads may be achieved compared with the comparative example.

[107] Figure 6A is a schematic axial cross-section of a hydrogen storage device 200 for a power supply 100 according to an exemplary embodiment and Figures 6B to 6D are schematic transverse cross-sections of the hydrogen storage device 200 of Figure 6A.

[108] Figure 6 shows a hydrogen storage device 200 for the power supply 100. The hydrogen storage device 200 comprises a hollow metal cylinder (outer cylindrical vessel wall (1)) and along with two metallic end-caps (2), providing the pressure vessel. Inside this volume exists the hydrideable metal/metal alloy (5), an aluminium fractal structure (4) with metallic foam in contact with it (not shown in figure). Both end-caps (2) contain an internal cavity for the location of multiple peltier devices (6) and heat/cold sinks (7). In the outer cylindrical vessel wall (1), there are three gas inlets (10) and three gas outlets (11) allow for heating/cooling gas (air) access to this internal cap cavity to add/remove heat. There is also an electronic entry/exit point (12) in the outer cylindrical vessel wall (1). In one of the end-caps four ports (holes) are included, allowing access into the pressure vessel; they are a hydrogen gas inlet (8), a hydrogen gas outlet (9), a pressure sensor connection (15) and a temperature sensor connection (14). The end-caps are held in place and form a seal through a thread and o-ring arrangement (3). The end-caps can be removed for easy access to the pressure vessel. The end-caps have covers (13) which can be removed for easy access to the heating/cooling gas containment volume within them. That is, the hydrogen storage device 200 comprises the pressure vessel 1, having the first fluid inlet 8 and the first fluid outlet 9, comprising therein a thermally conducting network 4 optionally thermally coupled to the first heater (not shown), wherein the pressure vessel 1 is arranged to receive therein a hydrogen storage material (not shown) in thermal contact, at least in part, with the thermally conducting network 4, wherein the first fluid inlet 8 and/or the first fluid outlet 9 are in fluid communication with the first releasable fluid inlet coupling (not shown) and/or the first releasable fluid outlet coupling (not shown), respectively; and preferably, wherein the thermally conducting network 4 has a lattice geometry and/or a fractal geometry in two and/or three dimensions.

[109] Figures 7A to 7C schematically depict thermally conducting networks for a hydrogen storage device for a power supply according to an exemplary embodiment.

[110] Figure 7 shows there are shown three alternative fractal networks (A) Gosper Island; (B) Snowflake' design; and (C) Koch Snowflake for the thermally conducting network of the hydrogen storage device 200. The 2D radially symmetric fractal patterns extend axially. Axial cross-sections, midpoint radial cross-sections and perspective views for the fractal networks are shown.

[111] Figure 8A is a photograph of a foam for a hydrogen storage device for a power supply according to an exemplary embodiment; and Figure 8B is a schematic view of a hydrogen storage device for a power supply according to an exemplary embodiment, in more detail.

[112] Figure 8A shows a photograph of voids (i.e. open space) in a metal foam, particularly aluminium foam. The aluminium foam is produced from 6101 aluminium alloy, retaining 99% purity of the parent alloy. The foam has a reticulated structure in which cells (i.e. pores) are open and have a dodecahedral shape. The foam has a bulk density of 0.2 g/cm3; a porosity of 93% porosity and about 8 pores/cm.

[113] Figure 8B schematically depicts a metal hydride powder included and/or in contact with a metal foam which in turn is thermally coupled to a thermally conducting network.

[114] Figure 9A is a plan elevation view of a hydrogen storage device 200' for a power supply according to an exemplary embodiment and Figure 9B is a side cross-sectional view of the hydrogen storage device 200' of Figure 9A.

[115] Figures 9A and 9B schematically depict a compact design of a hydrogen storage device 200'. The hydrogen storage device 200' comprises a hydrogen gas containment volume formed from a cuboid-based container vessel (1) with square-planar lid (2). The lid (2) is secured through the use of four axial-corner screws in screw fixings (7) and it is sealed by an 0-ring (3) positioned between the vessel (1) and the lid (2). The hydrogen containment volume has within it a hydrideable metal/metal alloy (5) and metal foam (not shown). On one surface there is a thermally conducting network (4) having a flat square-based fractal geometry, that acts to dissipate heat radially. A Peltier device (6), thermally coupled to the thermally conducting network (4) and outside of the vessel (1) acts as a heater/cooler. Two holes (8) and (9) located through the lid (2) and the thermally conducting network (4) act as a hydrogen gas inlet (8) and outlet (9), respectively. That is, the hydrogen storage device 200' comprises the pressure vessel 1, having the first fluid inlet 8 and the first fluid outlet 9, comprising therein a thermally conducting network 4 optionally thermally coupled to the first heater (not shown), wherein the pressure vessel 1 is arranged to receive therein a hydrogen storage material (not shown) in thermal contact, at least in part, with the thermally conducting network 4, wherein the first fluid inlet 8 and/or the first fluid outlet 9 are in fluid communication with the first releasable fluid inlet coupling (not shown) and/or the first releasable fluid outlet coupling (not shown), respectively; and preferably, wherein the thermally conducting network 4 has a lattice geometry and/or a fractal geometry in two and/or three dimensions.

[116] Figure 10 is CAD cutaway perspective view of a hydrogen storage device 200" for a power supply according to an exemplary embodiment. Figure 11 is CAD axial cross-section of the hydrogen storage device 200"of Figure 10. Figure 12 is a CAD radial cross-section of the hydrogen storage device 200"of Figure 10. The hydrogen storage device 200"comprises a pressure vessel 201", having a first fluid inlet 208" and a first fluid outlet 209", comprising therein a thermally conducting network 204" optionally thermally coupled to the first heater (not shown), wherein the pressure vessel 201" is arranged to receive therein a hydrogen storage material (not shown) in thermal contact, at least in part, with the thermally conducting network 204", wherein the first fluid inlet 208" and/or the first fluid outlet 209" are in fluid communication with the first releasable fluid inlet coupling (not shown) and/or the first releasable fluid outlet coupling (not shown), respectively; and preferably, wherein the thermally conducting network 204" has a lattice geometry and/or a fractal geometry in two and/or three dimensions.

[117] In this example, the pressure vessel 201" is generally cylindrical, having a generally dished first end and a necked second end opposed thereto, and having a single aperture providing both the first fluid inlet 208" and the first fluid outlet 209". In other words, the pressure vessel 201" is bottle-shaped. An inner wall portion 2011" of the pressure vessel 201" provides an axial cylindrical, elongate blind passageway 210", arranged to receive a first heater 206" (not shown), that extends from the first end towards the second end and that is coaxial with an outer wall portion 2010" of the pressure vessel 201". A second blind passageway in the first end is arranged to receive a thermocouple (not shown).

[118] In this example, the pressure vessel has an internal volume of about 500 cm3, therepby providing a hydrogen storage capacity of about 25 g H2. In this example, . [119] In this example, the thermally conducting network 204" has a lattice geometry in three dimensionsln this example, an effective density of the lattice geometry is uniform in a first dimension, particularly axially, and non-uniform in mutually orthogonal second and third dimensions, particularly radially. Particularly, the effective density decreases radially outwards, such that there is faster heat transfer proximal the passageway 210" and hence the first heater. In this example, the thermally conducting network 204" is formed from an aluminium alloy. Alternatively, the thermally conducting network 204" may be formed from copper, respective alloys thereof such as brass or bronze alloys, and/or stainless steel, as described previously.

[120] Figure 13 is an alternative CAD radial cross-section for the hydrogen storage device 200" of Figure 10. In this example, a node density (i.e. number of nodes per unit volume) of the lattice geometry, generally otherwise similar to the lattice geometry of Figure 12 mutatis mutandis, is relatively lower than that of the lattice geometry of Figure 12. A cross-sectional area of the arms is relatively larger than that of Figure 12.

[121] Figure 14 is a CAD cutaway perspective view of a hydrogen storage device 200"' for a vehicle according to an exemplary embodiment. Figure 15 is a CAD axial cross-section of the hydrogen storage device 200"' of Figure 14. In this example, the pressure vessel 201"' has an internal volume of about 50 cm3, thereby providing a hydrogen storage capacity of about 2.5 g H2.

[122] Figure 16 is a CAD radial cross-section of a thermally conducting network of the hydrogen storage device of Figure 14. Generally, the lattice geometry is as described with respect to Figure 13.

[123] Figure 17 schematically depicts Bravais lattices for a thermally conducting network, as described above.

[124] Figure 18 is a CAD perspective view of a hydrogen storage device 200B for a vehicle according to an exemplary embodiment, generally as described with respect to the hydrogen storage device 200A. Figure 19 is a CAD axial cross-section of the hydrogen storage device 200B of Figure 18. In this example, the hydrogen storage device 200B is arranged to be oriented horizontally, in use. In this example, the pressure vessel 230B is generally cylindrical, having dished ends. In this example, a passageway 250B, provided by a tube having a circular cross-section, extends between the dished ends longitudinally, offset from an axis of the pressure vessel 230A. In this example, the thermally conducting network 240B partially fills an internal volume of the pressure vessel, particularly a region of the internal volume extending across about 75% of a diameter the pressure vessel, thereby completely surrounding the tube, such that an unfilled volume above the thermally conducting network 240B is defined. In this example, the thermally conducting network 240B is thermally coupled to at least a part of an internal surface of the pressure vessel 230B and an external surface of the tube. In this example, the unfilled volume acts as a buffer, providing a reservoir of hydrogen during charging and similarly during release, for example to account for kinetics thereof.

[125] Figure 20 is a CAD axial cross-section of a hydrogen storage device 240C for a vehicle according to an exemplary embodiment, generally as described with respect to Figures 18 and 19, having a relatively longer axial length and a relatively smaller diameter.

[126] Figure 21 is a CAD perspective view of a vehicle 20 according to an exemplary embodiment, generally as described with respect to the vehicle 10. Figure 22 is a CAD perspective view of the vehicle 20 of Figure 21, in more detail. In this example, the vehicle 20 is a quad copter UAV. In this example, the propulsion system is releasably coupled, using mechanical fasteners, to the first hydrogen storage device. In this example, the first hydrogen storage device has at most two planes of symmetry, particularly having a shape arranged to reduce drag (i.e. shaped aerodynamically), in use. In this example, a fuel cell and a controller are releasably coupled, using mechanical fasteners, to the first hydrogen storage device, particularly to an external surface thereof.

[127] Figure 23 is a CAD cutaway perspective view of a vehicle 30 according to an exemplary embodiment, generally as described with respect to the vehicle 10. In this example, the vehicle 30 is a quad copter UAV. In this example, the pressure vessel comprises a double wall (i.e. an inner pressure wall and an outer wall). In this example, the outer wall is shaped aerodynamically. In this example, the inner wall is cylindrical, having dished ends. In this example, one or more components, particularly a fuel cell and a controller, of the vehicle 30 are arranged in the gap within the double wall.

[128] Figure 24 is a CAD perspective cross-section view of hydrogen storage device 200C for a vehicle according to an exemplary embodiment. Figure 25 is a CAD cross-section view of the hydrogen storage device 200C of Figure 24.

[129] In this example, the hydrogen storage device 200C provides a first structural component 100C, particularly a fixed wing, of the set of structural components 100 of the vehicle, wherein the vehicle is a fixed wing aircraft. In this example, a wall of the pressure vessel 230C of the hydrogen storage device 200C provides an aerofoil, thereby defining upper, lower, leading and trailing edges, of the fixed wing. In this example, the pressure vessel 230C comprises a tube 260C having a circular cross-section, arranged to receive a first heater therein, providing a wing spar. In this example, the thermally conducting network 240C has a lattice geometry in three-dimensions. In this example, the thermally conducting network is formed, at least in part, by 3D printing. In this example, the thermally conducting network 240C is thermally coupled to an external surface of the vehicle by being thermally coupled to an internal surface of the pressure vessel. In this example, the thermally conducting network 240C is thermally coupled to the tube 260C. In this example, the lattice geometry is a body-centred cubic lattice.

[130] Figure 26 is a CAD perspective view of a charging station assembly 1 according to an exemplary embodiment. The charging station assembly 1 comprises a charging station 2 and a hydrogen storage device 200. In this example, the charging station 2 is arranged to receive eight hydrogen storage devices, arranged in a bank of 4 x 2 hydrogen storage devices. In this example, the charging station 2 is arranged to charge a plurality of hydrogen storage devices 200, for example simultaneously. In this example, the charging station 2 comprises a manifold 3 coupleable to the plurality of hydrogen storage devices 200. In this example, the charging station 2 comprises a cooling system 4, arranged to cool a hydrogen storage device during charging thereof. In this example, the cooling system 2 comprises a plurality of fans.

Alternatives [131] Although a preferred embodiment has been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims and as described above.

Summary

[132] In summary, a vehicle, preferably an unmanned and/or autonomous vehicle for example an unmanned aerial vehicle, UAV, is described. The vehicle comprises: a set of structural components, arranged to provide, at least in part, a structure of the vehicle and to resist, at least in part, internal and external forces in one, two or three dimensions; a propulsion system, arranged to propel the vehicle, and/or an auxiliary power supply, arranged to provide electrical power to the vehicle; a set of hydrogen storage devices, including a first hydrogen storage device, and optionally a set of heaters including a first heater, wherein the set of hydrogen storage devices is arranged to provide hydrogen gas to the propulsion system and/or to the auxiliary power supply; wherein the first hydrogen storage device comprises: a pressure vessel, having a first fluid inlet and a first fluid outlet, comprising therein a thermally conducting network optionally thermally coupled to the first heater, wherein the pressure vessel is arranged to receive therein a hydrogen storage material in thermal contact, at least in part, with the thermally conducting network; and preferably, wherein the thermally conducting network has a lattice geometry and/or a fractal geometry in two and/or three dimensions; and wherein the first hydrogen storage device, preferably the pressure vessel and/or the thermally conducting network thereof, provides a first structural component of the set of structural components. By storing the hydrogen using the hydrogen storage material in the pressure vessel of the hydrogen storage device, a hydrogen storage capacity is improved while a storage pressure is reduced, compared with conventional storage of hydrogen, thereby enhancing safety while increasing a range and/or a payload and/or decreasing a fuel consumption of the vehicle. Since the hydrogen storage device provides the first structural component, a structural integrity of the vehicle is improved while a mass of the vehicle is reduced, thereby increasing a range and/or a payload and/or decreasing a fuel consumption of the vehicle.

Disclosure

[133] Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

[134] All of the features disclosed in this specification (including any accompanying claims and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at most some of such features and/or steps are mutually exclusive.

[135] Each feature disclosed in this specification (including any accompanying claims, and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[136] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

CLAIMS1. A vehicle, preferably an unmanned and/or autonomous vehicle for example an unmanned aerial vehicle, UAV, the vehicle comprising: a set of structural components, arranged to provide, at least in part, a structure of the vehicle and to resist, at least in part, internal and/or external forces in one, two or three dimensions; a propulsion system, arranged to propel the vehicle, and/or an auxiliary power supply, arranged to provide electrical power to the vehicle; a set of hydrogen storage devices, including a first hydrogen storage device, and optionally a set of heaters including a first heater, wherein the set of hydrogen storage devices is arranged to provide hydrogen gas to the propulsion system and/or to the auxiliary power supply; wherein the first hydrogen storage device comprises: a pressure vessel, having a first fluid inlet and a first fluid outlet, comprising therein a thermally conducting network optionally thermally coupled to the first heater, wherein the pressure vessel is arranged to receive therein a hydrogen storage material in thermal contact, at least in part, with the thermally conducting network; and preferably, wherein the thermally conducting network has a lattice geometry and/or a fractal geometry in two and/or three dimensions; and wherein the first hydrogen storage device, preferably the pressure vessel and/or the thermally conducting network thereof, provides a first structural component of the set of structural components.
2. The vehicle according to any previous claim, wherein the propulsion system and/or the auxiliary power supply comprises: a set of electrical generators, including a first electrical generator, configured to generate electricity using the hydrogen gas, selected from a group comprising a fuel cell and an electrical generator comprising a heat engine.
3. The vehicle according to claim 2, wherein the first electrical generator is the fuel cell, selected from a group comprising a proton exchange membrane fuel cell, PEMFC, an alkaline fuel cell, AFC, and a phosphoric acid fuel cell, PAFC.
4. The vehicle according to any previous claim, wherein the vehicle is an aircraft, for example a fixed wing aircraft or a rotary wing aircraft, and wherein the first structural component defines an airframe, a fuselage, a fixed wing and/or a part thereof
5. The vehicle according to any of claims 1 to 3, wherein the vehicle is a watercraft, such as a surface watercraft or a submersible watercraft, and wherein the first structural component defines a hull or part thereof.
6. The vehicle according to any of claims 1 to 3, wherein the vehicle is a land craft and wherein the first structural component defines a chassis or part thereof.
7. The vehicle according to any previous claim, wherein the thermally conducting network is thermally coupleable to an external surface of the vehicle.
8. The vehicle according to any previous claim, wherein the thermally conducting network is thermally coupleable to the propulsion system and/or to the auxiliary power supply.
9. The vehicle according to any previous claim, comprising: a controller configured to control the first heater based, at least in part, on a power output of the propulsion system and/or of the auxiliary power supply.
10. The vehicle according to claim 9, wherein: the controller is configured to control the first heater based, at least in part, on a predicted rate of power output of the propulsion system and/or of the auxiliary power supply.
11. The vehicle according to any previous claim, wherein the first hydrogen storage device has a hydrogen storage density of at least 0.01 wt.%, at least 1.8 wt.%, preferably at least 2.4 wt.%, more preferably at least 3.3 wt.%, most preferably at least 5.5 wt.%, by wt.% of the first hydrogen storage vessel.
12. The vehicle according to any previous claim, wherein the propulsion system and/or the auxiliary power supply and the set of hydrogen storage devices and mutually releasably coupled.
13. The vehicle according to any previous claim, wherein the first hydrogen storage device has at most two planes of symmetry, preferably having a shape arranged to reduce drag, in use.
14. The vehicle according to any previous claim, wherein the first heater comprises a Joule heater and/or a recirculating heater, preferably wherein the first hydrogen storage device, for example the pressure vessel, is arranged to interchangeably receive the Joule heater and the recirculating heater therein and/or thereon.
15. A charging station for charging a hydrogen storage device for a vehicle according to any of claims 1 to 14.
16. A charging station assembly comprising a hydrogen storage device for a vehicle according to any of claims 1 to 14 and a charging station according to claim 15.
17. A hydrogen storage device for a vehicle, preferably an unmanned and/or autonomous vehicle for example an unmanned aerial vehicle, UAV; wherein the vehicle comprises a set of structural components, arranged to provide, at least in part, a structure of the vehicle and to resist, at least in part, internal and/or external forces in one, two or three dimensions; and a propulsion system, arranged to propel the vehicle, and/or an auxiliary power supply, arranged to provide electrical power to the vehicle; wherein the hydrogen storage device is arranged to provide hydrogen gas to the propulsion system and/or to the auxiliary power supply and wherein the hydrogen storage device comprises: a pressure vessel, having a first fluid inlet and a first fluid outlet, comprising therein a thermally conducting network optionally thermally coupled to the first heater, wherein the pressure vessel is arranged to receive therein a hydrogen storage material in thermal contact, at least in part, with the thermally conducting network; and preferably, wherein the thermally conducting network has a lattice geometry and/or a fractal geometry in two and/or three dimensions; and wherein the hydrogen storage device, preferably the pressure vessel and/or the thermally conducting network thereof, provides a first structural component of the set of structural components.