Systems and methods for gas transfer and fuelling

Abstract

The system 110 comprises a fuel gas storage unit 112 comprising a plurality of storage vessels 202, 204, 206, 208 for storing fuel gas. Each storage vessel 202, 204, 206, 208 of the plurality of storage vessels 202, 204, 206, 208 is selectively fluidly connectable to at least one receiving vessel A. The system 110 comprises a compressor 114 for increasing the pressure of the fuel gas. The system comprises a controller which, in a first operation, sequentially fluidly connects the plurality of storage vessels 202, 204, 206, 208 to the at least one receiving vessel A, and, in a second operation, activates the compressor 114 to increase the pressure of the fuel gas. The compressor 114 may comprise an operating fluid delivery means 236 that delivers operating fluid to the fuel gas storage unit 112 or a dedicated fuel gas storage unit of the compressor 114.

Description

[0001] SYSTEMS AND METHODS FOR GAS TRANSFER AND FUELLING

[0002] The present disclosure is directed towards a system and method for transferring gas to at least one receiving vessel, and a system and method for fuelling at least one receiving vessel with a fuel gas such as hydrogen gas.

[0003] BACKGROUND

[0004] Fuel gases, such as hydrogen gas, are delivered to receiving vessels at high pressure. Receiving vessels may be fuel tanks such as vehicle fuel tanks.

[0005] Some example existing fuelling methods use gaseous compressors and intercoolers to deliver fuel gas at fuelling stations using large scale fuel gas storage units.

[0006] Some example existing fuelling methods rely on the pressure difference between the high-pressure storage vessels and the receiving vessel to deliver fuel gas. These existing methods are known as cascade-filling or pressure cascading. In pressure cascading, the storage unit has multiple storage vessels, and the receiving vessel is connected to, and pressure equilibrated with, the storage vessels (or groups thereof) in order of increasing pressure. This means that the receiving vessel is connected to the storage vessel with the lowest pressure first. Once pressure equilibrium is reached, the receiving vessel is connected to the storage vessel with the next lowest pressure and so on. In this way, the pressure of the receiving vessel increases as it is connected to subsequent storage vessels. Pressure cascading enables the highest pressure storage vessels to remain at high pressures which helps to provide a higher final pressure in the receiving vessel.

[0007] These existing methods are relatively inefficient and have issues such as over-heating and low percentage of fuel gas delivery.

[0008] The present disclosure is directed towards providing a more efficient and effective system for fuelling one or more receiving vessels with fuel gas.

[0009] SUMMARY

[0010] There is provided a system and method for fuelling as set out in the accompanying claims. Other features of the invention will be apparent from the dependent claims, and the description which follows.

[0011] According to a first aspect of the disclosure, there is provided a system for fuelling.

[0012] The system comprises a fuel gas storage unit comprising a plurality of storage vessels for storing fuel gas. Each storage vessel of the plurality of storage vessels is selectively fluidly connectable to at least one receiving vessel.

[0013] The system comprises a compressor for increasing the pressure of the fuel gas. The system comprises a controller configured to, in a first operation, sequentially fluidly connect the plurality of storage vessels to the at least one receiving vessel, and, in a second operation, activate the compressor to increase the pressure of the fuel gas.

[0014] Advantageous, in a first fuelling operation, the system uses a cascading approach to sequentially connect the storage vessels to the receiving vessel. In the first fuelling operation, fuel gas flows from the storage vessels to the receiving vessel until pressure equilibrium is reached. In a second fuelling operation, the compressor increases the pressure of the fuel gas. The fuel gas with increased pressure is able to flow to the receiving vessel. During or after the second operation, one or more of the storage vessels are fluidly connected to the at least one receiving vessel to allow for the fuel gas to flow to the at least one receiving vessel. Activating the compressor allows for extended fuel gas delivery from the fuel gas storage unit in situations such as when the storage vessels, as a result of the first fuelling operation, have reached pressure equilibrium with the receiving vessel.

[0015] The controller may be configured to perform the second operation after the first operation. The second operation may be performed at the same time as the first operation. The concurrent performance of the first and second operation may occur when it is determined to be beneficial such as due to there being a minimal pressure differential between the fuel gas storage unit and receiving vessel before refuelling has taken place. The concurrent performance of the first and second operation may also occur when a rapid refuelling is desired to take place.

[0016] The controller may be configured to transition from the first operation to the second operation in response to detecting a trigger condition. The trigger condition may be indicative of the first operation being unable to deliver subsequent fuel gas to the at least one receiving vessel due to pressure equilibrium being reached. The controller may automatically transition from the first operation to the second operation without user input.

[0017] The trigger condition may comprise the flow rate of fuel gas from one or more of the storage vessels falling below a threshold value.

[0018] The trigger condition may comprise the pressure in one or more of the plurality of storage vessels falling below a threshold value.

[0019] The compressor may comprise an operating fluid delivery means arranged to deliver an operating fluid such that the operating fluid is brought into contact with the fuel gas to increase the pressure of the fuel gas. The operating fluid therefore acts as a liquid piston.

[0020] Advantageously, a liquid piston compressor is used rather than a mechanical compressor. Liquid piston compressors require fewer component parts than mechanical compressor and are thus simpler to manufacture and have longer lifespans. In some examples, the liquid piston compressor is able to receive and discharge fuel gas at a range of atmospheric pressure and greater than 1000 bar and optionally between 30 and 700 bar with full variable compression ratio.

[0021] The operating fluid may be water. The operating fluid may be an ionic fluid. Other operating fluids may also be used.

[0022] The operating fluid delivery means may be arranged to deliver the operating fluid to the fuel gas storage unit to increase the pressure of fuel gas contained within one or more of the storage vessels of the fuel gas storage unit. The pressurised fuel gas can then be delivered to the at least one receiving vessel.

[0023] The storage vessels define an internal volume for storing fuel gas. The operating fluid may be delivered to the internal volume of one or more of the storage vessels of the fuel gas storage unit.

[0024] The operating fluid delivery means may be arranged to selectively deliver the operating fluid to at least one storage vessel of the fuel gas storage unit. The controller may be arranged to control the operating fluid delivery means to selectively deliver the operating fluid to at least one storage vessel of the fuel gas storage unit.

[0025] Advantageously, this means that operating fluid may be delivered to one or more of the storage vessels while not being delivered to other ones of the storage vessels. This can provide greater flexibility in terms of controlling the pressure in the storage vessels.

[0026] The fuel gas storage unit may be a first fuel gas storage unit. The compressor may comprise a second fuel gas storage unit for storing fuel gas. The second fuel gas storage unit may be fluidly connectable to the first fuel gas storage unit. The operating fluid delivery means may be arranged to deliver the operating fluid to the second fuel gas storage unit to increase the pressure of fuel gas contained within the second fuel gas storage unit.

[0027] Advantageously, the operating fluid is delivered to a separate (second) fuel gas storage unit. The second fuel gas storage unit typically has a smaller volume than the first fuel gas storage unit and so can be used to compress fuel gas more rapidly than if operating fluid were delivered to the first fuel gas storage unit. This allows for the system to compress smaller volumes of fuel gas more quickly for refuelling receiving vessels. Alternatively, the effective volume of the second storage unit is adjustable as required through delivery of the operating fluid prior to compression. The volumes of the storage units / vessels are completely flexible and adaptable to suit the specific circumstance from small containers of 100 litres to 100m3as exemplary values only.

[0028] The second fuel gas storage unit may be arranged to receive fuel gas from at least one storage vessel of the first fuel gas storage unit. The operating fluid delivery means may be arranged to deliver the operating fluid to the second fuel gas storage unit to increase the pressure of the fuel gas received from the at least one storage vessel of the first fuel gas storage unit.

[0029] The second fuel gas storage unit may define an internal volume for storing fuel gas. The operating fluid may be delivered to the internal volume of the second fuel gas storage unit.

[0030] The second fuel gas storage may comprise a plurality of storage vessels for storing fuel gas.

[0031] The second fuel gas storage unit may be arranged to deliver fuel gas to the at least one receiving vessel.

[0032] Advantageously, the second fuel gas storage unit can be used to increase the pressure of fuel gas receiving from the first fuel gas storage unit and can deliver the pressurised fuel gas to the receiving vessel even if pressure equilibrium between the receiving vessel and the first fuel gas storage unit has been reached.

[0033] The second fuel gas storage unit may be arranged to deliver fuel gas to at least one storage vessel of the first fuel gas storage unit.

[0034] Advantageously, the second fuel gas storage unit can be used to increase the pressure of fuel gas and return the pressurised fuel gas to the first fuel gas storage unit. This increases the pressure of the fuel gas and extends the delivery of fuel gas from the first fuel gas storage unit to the receiving vessel such as during pressure cascading.

[0035] The second fuel gas storage unit may be arranged to receive fuel gas from a first storage vessel of the first fuel gas storage unit. The operating fluid delivery means may be arranged to deliver the operating fluid to the second fuel gas storage unit to increase the pressure of the fuel gas received from the first storage vessel of the first fuel gas storage unit. The second fuel gas storage unit may be arranged to deliver the fuel gas to a second storage vessel of the first fuel gas storage unit. The pressure in the second vessel of the first fuel gas storage unit is increased while the pressure in the first vessel of the first fuel gas storage unit is decreased due to hydrogen gas being withdrawn therefrom.

[0036] The system may comprise a first circuit for the flow of fuel gas and a second circuit for the flow of fuel gas. The first circuit may enable fuel gas to flow from the first fuel gas storage unit to the second fuel gas storage unit. The first circuit may also enable fuel gas to flow from the second fuel gas storage unit to the at least one receiving vessel. The second circuit may enable fuel gas to flow from the first fuel gas storage unit to the at least one receiving vessel without flowing to the second fuel gas storage unit.

[0037] Advantageously, fuel gas can concurrently flow to the at least one receiving vessel (via the second circuit) and to the second fuel gas storage unit (via the first circuit) for compression prior to delivery to the at least one receiving vessel or transfer back to the first fuel gas storage unit. This enables faster refuelling as pressure cascading using some storage vessels can be simultaneously performed while fuel gas from other storage vessels is being boosted in pressure via the second fuel gas storage unit.

[0038] A first one or group of storage vessels of the first fuel gas storage unit may be fluidly connected to the first circuit and fluidly disconnected from the second circuit. A second one or group of storage vessels of the first fuel gas storage unit may be fluidly connected to the second circuit and fluidly disconnected from the first circuit. The controller may change which of the storage vessels are connected to the first circuit / second circuit through activation of flow control devices such as valves.

[0039] The system may comprise a plurality of flow control devices for controlling the flow of fuel gas from the vessels of the fuel gas storage unit to the at least one receiving vessel. The controller may be configured to control the flow control devices to selectively fluidly connect the plurality of storage vessels to the at least one receiving vessel.

[0040] The fuel gas may comprise hydrogen gas. The fuel gas may comprise methane gas, propane gas, hydrogen gas, carbon monoxide gas or a mixture of one or more of these gases. The fuel gas may be syngas which comprises a mixture of hydrogen gas and carbon monoxide gas.

[0041] The fuel gas storage unit may comprise at least three storage vessels for storing fuel gas. The fuel gas storage unit may comprise at least five storage vessels. The fuel gas storage unit may comprise at least ten storage vessels. The fuel gas storage unit may comprise at least twenty storage vessels for storing fuel gas.

[0042] The fuel gas storage unit may comprise between three and two hundred storage vessels. The fuel gas storage unit may comprise between three and one hundred and fifty storage vessels. The fuel gas storage unit may comprise between three and one hundred storage vessels. The fuel gas storage unit may comprise between three and fifty storage vessels. The fuel gas storage unit may comprise between three and twenty storage vessels. The fuel gas storage unit may comprise between three and ten storage vessels.

[0043] The fuel gas storage unit may comprise between five and two hundred storage vessels. The fuel gas storage unit may comprise between ten and two hundred storage vessels. The fuel gas storage unit may comprise between twenty and two hundred storage vessels. The fuel gas storage unit may comprise between fifty and two hundred storage vessels. The fuel gas storage unit may comprise between one hundred and two hundred storage vessels. The fuel gas storage unit may comprise between one hundred and fifty and two hundred storage vessels. The controller may selectively divide the plurality of storage vessels into a plurality of groups each comprising one or more storage vessels. In the first operation, the controller may be configured to sequentially fluidly connect the plurality of groups to the at least one receiving vessel.

[0044] The controller may be operable to determine a required amount of fuel gas to be delivered to the at least one receiving vessel, and wherein the controller is operable to, in the first operation and / or second operation, deliver the required amount of fuel gas to the at least one receiving vessel.

[0045] Advantageously, rather than attempting to completely fill the receiving vessel, the controller can determine an amount of fuel gas required by the receiving vessel and deliver the required amount of fuel gas. The required amount of fuel gas may be less than the storage capacity of the receiving vessel. This conserves pressure in the fuel gas storage unit as high pressures are not necessarily required to fill or attempt to fill the receiving vessel completely.

[0046] The controller may be operable to determine the required amount of fuel gas to be delivered to the at least one receiving vessel based on a calculation of the expected fuel gas consumption for the at least one receiving vessel over a period of time.

[0047] Advantageously, the controller estimates the amount of fuel gas required for the receiving vessel based on an expected consumption of fuel gas by the receiving vessel over a period of time. The period of time may be arbitrary or may be specified by the user (e.g., 1 day).

[0048] The at least one receiving vessel may comprise a plurality of receiving vessels.

[0049] The controller may be operatable to determine a required amount of fuel gas to be delivered to each of the plurality of receiving vessels.

[0050] Advantageously, rather than attempting to completely fill each receiving vessel, the controller can determine an amount of fuel gas required by each receiving vessel and deliver the required amount of fuel gas. The required amount of fuel gas may be less than the storage capacity of the receiving vessel. This conserves pressure in the fuel gas storage unit as high pressures are not necessarily required to fill or attempt to fill the receiving vessel completely.

[0051] The controller may be operable to determine the required amount of fuel gas to be delivered to the plurality of receiving vessels based on a calculation of the expected fuel gas consumption for the plurality of receiving vessels over a period of time.

[0052] The controller may be operable to determine an order for fuelling the plurality of receiving vessels. Advantageously, the controller determines an order for fuelling the receiving vessels. The determined order can help optimise the number of receiving vessels filled with their required amounts of fuel gas, the utilisation of fuel gas storage in the fuel gas storage unit, and the energy consumption of the fuelling process.

[0053] The controller may be operable to determine the order for fuelling the plurality of receiving vessels based on a determined fuel gas storage pressure for each of the plurality of receiving vessels.

[0054] Fuel gas storage pressure refers to the pressure at which fuel gas is required to be stored in each of the receiving vessels. The fuel gas storage pressure can be determined from the calculation for how much fuel gas is required. In more detail, the amount of fuel gas identifies that mass of fuel gas required. Parameters such as the volume of the receiving vessels, expected storage temperature, and equations for real gas behaviour are used to convert the required mass of fuel gas to a storage pressure.

[0055] The determined order may prioritise receiving vessels having higher fuel gas storage pressures over receiving vessels having lower fuel gas storage pressures.

[0056] Advantageously, the controller determines an order for fuelling the receiving vessels that prioritises fuelling receiving vessels with higher fuel gas storage pressures. This helps ensure that these receiving vessels can be fuelled sufficiently while the pressure in the fuel gas storage unit is high. In turn, this approach reduces the amount of energy consumption required for fuelling as the initiation of the second operation mode can be delayed.

[0057] The determined order may specify fuelling the receiving vessels in order of decreasing fuel gas storage pressure.

[0058] Advantageously, the controller determines an order for fuelling which fuels the receiving vessels in order of decreasing fuel gas storage pressure. This helps ensure that the high pressure receiving vessels are fuelled first while the pressure in the fuel gas storage unit is high. In turn, this approach reduces the amount of energy consumption required for fuelling as the initiation of the second operation mode can be delayed.

[0059] The controller may be operable to fuel the plurality of receiving vessels according to the determined order.

[0060] According to a second aspect of the disclosure, there is provided a method of fuelling. The method comprises, in a first operation, sequentially fluidly connecting a plurality of storage vessels of a fuel gas storage unit to at least one receiving vessels so as to deliver fuel gas from the vessels to the at least one receiving vessel. The method comprises, in a second operation, activating a compressor to increase the pressure of the fuel gas. The second operation may be performed after the first operation. The second operation may be performed at the same time as the first operation. The concurrent performance of the first and second operations may occur when it is determined to be beneficial such as due to there being a minimal pressure differential between the fuel gas storage unit and receiving vessel before refuelling has taken place. The concurrent performance of the first and second operation may also occur when a rapid refuelling is desired to take place.

[0061] The method may transition from the first operation to the second operation in response to detecting a trigger condition. The trigger condition may be indicative of the first operation being unable to deliver subsequent fuel gas to the at least one receiving vessel due to pressure equilibrium being reached. The method may automatically transition from the first operation to the second operation without user input.

[0062] The trigger condition may comprise the flow rate of fuel gas from one or more of the storage vessels falling below a threshold value.

[0063] The trigger condition may comprise the pressure in one or more of the plurality of storage vessels falling below a threshold value.

[0064] Activating the compressor may comprise activating an operating fluid delivery means to deliver an operating fluid such that the operating fluid is brought into contact with the fuel gas to increase the pressure of the fuel gas. The operating fluid therefore acts as a liquid piston.

[0065] The operating fluid delivery means may deliver the operating fluid to the fuel gas storage unit to increase the pressure of fuel gas contained within one or more of the storage vessels of the fuel gas storage unit.

[0066] The fuel gas storage unit may be a first fuel gas storage unit. The compressor may comprise a second fuel gas storage unit for storing fuel gas. The second fuel gas storage unit may be fluidly connectable to the first fuel gas storage unit. The operating fluid delivery means may deliver the operating fluid to the second fuel gas storage unit to increase the pressure of fuel gas contained within the second fuel gas storage unit.

[0067] The second fuel gas storage unit may be arranged to receive fuel gas from at least one storage vessel of the first fuel gas storage unit.

[0068] The operating fluid delivery means may deliver the operating fluid to the second fuel gas storage unit to increase the pressure of the fuel gas received from the at least one storage vessel of the first fuel gas storage unit.

[0069] The second fuel gas storage unit may deliver fuel gas to the at least one receiving vessel. The second fuel gas storage unit may deliver fuel gas to at least one storage vessel of the first fuel gas storage unit.

[0070] The method may comprise determining a required amount of fuel gas to be delivered to the at least one receiving vessel in the first operation and / or second operation.

[0071] The determining of the required amount of fuel gas to be delivered to the at least one receiving vessel may be based on a calculation of the expected fuel gas consumption for the at least one receiving vessel over a period of time.

[0072] The at least one receiving vessel may comprise a plurality of receiving vessels.

[0073] The method may comprise determining a required amount of fuel gas to be delivered to each of the plurality of receiving vessels.

[0074] The method may comprise determining the required amount of fuel gas to be delivered to the plurality of receiving vessels based on a calculation of the expected fuel gas consumption for the plurality of receiving vessels over a period of time.

[0075] The method may comprise determining an order for fuelling the plurality of receiving vessels.

[0076] The determining of the order for fuelling the plurality of receiving vessels may be based on a determined fuel gas storage pressure for each of the plurality of receiving vessels.

[0077] The determined order may prioritise receiving vessels having higher fuel gas storage pressures.

[0078] The determined order may specify fuelling the receiving vessels in order of decreasing fuel gas storage pressure.

[0079] The method may comprise delivering fuel gas to the plurality of receiving vessels according to the determined order.

[0080] According to a third aspect of the disclosure, there is provided a method of fuelling.

[0081] The method comprises determining the required amount of fuel gas to be delivered to a plurality of receiving vessels.

[0082] The method comprises, for each of the plurality of receiving vessels, delivering fuel gas to the receiving vessel such that each of the plurality of receiving vessels receives their determined required amount of fuel gas. Determining the required amount of fuel gas may be based on a calculation of the expected fuel gas consumption for each of the plurality of receiving vessels over a period of time.

[0083] The method may further comprise determining an order for fuelling the plurality of receiving vessels based on a determined fuel gas storage pressure for each of the plurality of receiving vessels. The fuel gas may be delivered to the receiving vessels according to the determined order for fuelling.

[0084] The determined order may prioritise receiving vessels having higher fuel gas storage pressures.

[0085] The determined order may specify fuelling the receiving vessels in order of decreasing fuel gas storage pressure.

[0086] Delivering fuel gas to the receiving vessel may comprise, in a first operation, sequentially fluidly connecting a plurality of storage vessels of a fuel gas storage unit to the receiving vessels so as to deliver fuel gas from the vessels to the receiving vessel.

[0087] Delivering fuel gas to the receiving vessel may further comprises, in a second operation, activating a compressor to increase the pressure of the fuel gas.

[0088] According to a fourth aspect of the disclosure, there is provided a method of fuelling.

[0089] The method comprises determining an order for fuelling a plurality of receiving vessels based on a determined fuel gas storage pressure for each of the plurality of receiving vessels.

[0090] The method further comprises delivering fuel gas to the receiving vessels according to the determined order for fuelling.

[0091] The determined order may prioritise receiving vessels having higher fuel gas storage pressures.

[0092] The determined order may specify fuelling the receiving vessels in order of decreasing fuel gas storage pressure.

[0093] The method may further comprise determining the required amount of fuel gas to be delivered to the plurality of receiving vessels.

[0094] The method may further comprise for each of the plurality of receiving vessels, delivering fuel gas to the receiving vessel such that each of the plurality of receiving vessels receives their determined required amount of fuel gas. Determining the required amount of fuel gas may be based on a calculation of the expected fuel gas consumption for each of the plurality of receiving vessels over a period of time.

[0095] Delivering fuel gas to the receiving vessel may comprise, in a first operation, sequentially fluidly connecting a plurality of storage vessels of a fuel gas storage unit to the receiving vessels to as to deliver fuel gas from the vessels to the receiving vessel.

[0096] Delivering fuel gas to the receiving vessel may further comprises, in a second operation, activating a compressor to increase the pressure of the fuel gas.

[0097] Whilst the preceding aspects of the disclosure refer to systems and methods for fuelling, it will be readily appreciated that “fuelling” involves the transfer of gas from, for example, a storage unit e.g. a fuel gas storage unit, to a receiving vessel e.g. a tank of a vehicle. Accordingly, the fuelling system and methods of fuelling as described in the preceding aspects may also be suitably applied for the transfer of gases in applications other than fuelling, which involve the transfer of gas from a storage unit to at least one receiving vessel. As such, the system may be referred to as a gas transfer system. The above examples refer to the gas being a “fuel gas”, but this is not always required. The gas may not be a fuel gas in some examples.

[0098] According to a fifth aspect of the disclosure, there is provided a gas transfer system.

[0099] The gas transfer system may have any of, or all, the features of the system for fuelling of the first aspect but the gas transfer need not necessarily be used for fuelling and the gas need not necessarily be a fuel gas and may be a gas other than fuel gas.

[0100] The gas transfer system comprises a gas storage unit comprising a plurality of storage vessels for storing gas. Each storage vessel of the plurality of storage vessels is selectively fluidly connectable to at least one receiving vessel.

[0101] The gas transfer system comprises a compressor for increasing the pressure of the gas.

[0102] The gas transfer system comprises a controller configured to, in a first operation, sequentially fluidly connect the plurality of storage vessels to the at least one receiving vessel, and, in a second operation, activate the compressor to increase the pressure of the gas.

[0103] Advantageously, in a first transfer operation, the system uses a cascading approach to sequentially connect the storage vessels to the receiving vessel. In the first transfer operation, gas flows from the storage vessels to the receiving vessel until pressure equilibrium is reached. In a second transfer operation, the compressor increases the pressure of the gas. The gas with increased pressure is able to flow to the receiving vessel. During or after the second operation, one or more of the storage vessels are fluidly connected to the at least one receiving vessel to allow for the gas to flow to the at least one receiving vessel. Activating the compressor allows for extended gas delivery from the gas storage unit in situations such as when the storage vessels, as a result of the first transfer operation, have reached pressure equilibrium with the receiving vessel.

[0104] The controller may be configured to perform the second operation after the first operation. The second operation may be performed at the same time as the first operation. The concurrent performance of the first and second operation may occur when it is determined to be beneficial such as due to there being a minimal pressure differential between the gas storage unit and receiving vessel before filling has taken place. The concurrent performance of the first and second operation may also occur when a rapid filling is desired to take place.

[0105] The controller may be configured to transition from the first operation to the second operation in response to detecting a trigger condition. The trigger condition may be indicative of the first operation being unable to deliver subsequent gas to the at least one receiving vessel due to pressure equilibrium being reached. The controller may automatically transition from the first operation to the second operation without user input.

[0106] The trigger condition may comprise the flow rate of gas from one or more of the storage vessels falling below a threshold value.

[0107] The trigger condition may comprise the pressure in one or more of the plurality of storage vessels falling below a threshold value.

[0108] The compressor may comprise an operating fluid delivery means arranged to deliver an operating fluid such that the operating fluid is brought into contact with the gas to increase the pressure of the gas. The operating fluid therefore acts as a liquid piston.

[0109] Advantageously, a liquid piston compressor is used rather than a mechanical compressor. Liquid piston compressors require fewer component parts than mechanical compressor and are thus simpler to manufacture and have longer lifespans. In some examples, the liquid piston compressor is able to receive and discharge gas at a range of atmospheric pressure and greater than 1000 bar and optionally between 30 and 700 bar with full variable compression ratio. The operating fluid may be water. The operating fluid may be an ionic fluid. Other operating fluids may also be used.

[0110] The operating fluid delivery means may be arranged to deliver the operating fluid to the gas storage unit to increase the pressure of gas contained within one or more of the storage vessels of the gas storage unit. The pressurised gas can then be delivered to the at least one receiving vessel. The operating fluid delivery means may be operable to deliver an operating fluid such that the operating fluid is brought into contact with the gas so as to sustain the pressure of the pressurised gas during transfer.

[0111] The storage vessels define an internal volume for storing gas. The operating fluid may be delivered to the internal volume of one or more of the storage vessels of the gas storage unit.

[0112] The operating fluid delivery means may be arranged to selectively deliver the operating fluid to at least one storage vessel of the gas storage unit. The controller may be arranged to control the operating fluid delivery means to selectively deliver the operating fluid to at least one storage vessel of the gas storage unit.

[0113] Advantageously, this means that operating fluid may be delivered to one or more of the storage vessels while not being delivered to other ones of the storage vessels. This can provide greater flexibility in terms of controlling the pressure in the storage vessels.

[0114] The gas storage unit may be a first gas storage unit. The compressor may comprise a second gas storage unit for storing gas. The second gas storage unit may be fluidly connectable to the first gas storage unit. The operating fluid delivery means may be arranged to deliver the operating fluid to the second gas storage unit to increase the pressure of gas contained within the second gas storage unit.

[0115] Advantageously, the operating fluid is delivered to a separate (second) gas storage unit. The second gas storage unit typically has a smaller volume than the first gas storage unit and so can be used to compress gas more rapidly than if operating fluid were delivered to the first gas storage unit. This allows for the system to compress smaller volumes of gas more quickly for filling receiving vessels. Alternatively, the effective volume of the second storage unit is adjustable as required through delivery of the operating fluid prior to compression. The volumes of the storage units / vessels are completely flexible and adaptable to suit the specific circumstance from small containers of 100 litres to 100m3as exemplary values only.

[0116] The second gas storage unit may be arranged to receive gas from at least one storage vessel of the first gas storage unit.

[0117] The operating fluid delivery means may be arranged to deliver the operating fluid to the second gas storage unit to increase the pressure of the gas received from the at least one storage vessel of the first gas storage unit.

[0118] The operating fluid delivery means may be arranged to deliver the operating fluid to the second gas storage unit so as to sustain the pressure of the pressurised gas being withdrawn from the second gas storage unit. The second gas storage unit may define an internal volume for storing gas. The operating fluid may be delivered to the internal volume of the second gas storage unit.

[0119] The second gas storage may comprise a plurality of storage vessels for storing gas.

[0120] The second gas storage unit may be arranged to deliver gas to the at least one receiving vessel.

[0121] Advantageously, the second gas storage unit can be used to increase the pressure of gas received from the first gas storage unit and can deliver the pressurised gas to the receiving vessel even if pressure equilibrium between the receiving vessel and the first gas storage unit has been reached.

[0122] The second gas storage unit may be arranged to deliver gas to at least one storage vessel of the first gas storage unit.

[0123] Advantageously, the second gas storage unit can be used to increase the pressure of gas and return the pressurised gas to the first gas storage unit. This increases the pressure of the gas and extends the delivery of gas from the first gas storage unit to the receiving vessel such as during pressure cascading.

[0124] The second gas storage unit may be arranged to receive gas from a first storage vessel of the first gas storage unit. The operating fluid delivery means may be arranged to deliver the operating fluid to the second gas storage unit to increase the pressure of the gas received from the first storage vessel of the first gas storage unit. The second gas storage unit may be arranged to deliver the gas to a second storage vessel of the first gas storage unit. The pressure in the second vessel of the first gas storage unit is increased while the pressure in the first vessel of the first gas storage unit is decreased due to gas being withdrawn therefrom.

[0125] The system may comprise a first circuit for the flow of gas and a second circuit for the flow of gas. The first circuit may enable gas to flow from the first gas storage unit to the second gas storage unit. The first circuit may also enable gas to flow from the second gas storage unit to the at least one receiving vessel. The second circuit may enable gas to flow from the first gas storage unit to the at least one receiving vessel without flowing to the second gas storage unit.

[0126] Advantageously, gas can concurrently flow to the at least one receiving vessel (via the second circuit) and to the second gas storage unit (via the first circuit) for compression prior to delivery to the at least one receiving vessel or transfer back to the first gas storage unit. This enables faster filling as pressure cascading using some storage vessels can be simultaneously performed while gas from other storage vessels is being boosted in pressure via the second gas storage unit. A first one or group of storage vessels of the first gas storage unit may be fluidly connected to the first circuit and fluidly disconnected from the second circuit. A second one or group of storage vessels of the first gas storage unit may be fluidly connected to the second circuit and fluidly disconnected form the first circuit. The controller may change which of the storage vessels are connected to the first circuit / second circuit through activation of flow control devices such as valves.

[0127] The system may comprise a plurality of flow control devices for controlling the flow of gas from the vessels of the gas storage unit to the at least one receiving vessel. The controller may be configured to control the flow control devices to selectively fluidly connect the plurality of storage vessels to the at least one receiving vessel.

[0128] The gas may comprise hydrogen gas. The gas may comprise methane gas, propane gas, hydrogen gas, carbon monoxide gas, ammonia gas, oxygen gas, nitrogen gas, helium gas, argon gas, compressed air, or a mixture of one or more of these gases. The gas may be syngas which comprises a mixture of hydrogen gas and carbon monoxide gas.

[0129] The gas storage unit may comprise at least three storage vessels for storing gas. The gas storage unit may comprise at least five storage vessels. The gas storage unit may comprise at least ten storage vessels. The gas storage unit may comprise at least twenty storage vessels for storing gas.

[0130] The gas storage unit may comprise between three and two hundred storage vessels. The gas storage unit may comprise between three and one hundred and fifty storage vessels. The gas storage unit may comprise between three and one hundred storage vessels. The gas storage unit may comprise between three and fifty storage vessels. The gas storage unit may comprise between three and twenty storage vessels. The gas storage unit may comprise between three and ten storage vessels.

[0131] The gas storage unit may comprise between five and two hundred storage vessels. The gas storage unit may comprise between ten and two hundred storage vessels. The gas storage unit may comprise between twenty and two hundred storage vessels. The gas storage unit may comprise between fifty and two hundred storage vessels. The gas storage unit may comprise between one hundred and two hundred storage vessels. The gas storage unit may comprise between one hundred and fifty and two hundred storage vessels.

[0132] The gas storage unit and compressor may be located at a gas production site. Where the gas storage unit and compressor are located at a gas production site, the at least one receiving vessel may comprise any one of a mobile storage tank or an on-site storage tank.

[0133] The controller may selectively divide the plurality of storage vessels into a plurality of groups each comprising one or more storage vessels. In the first operation, the controller may be configured to sequentially fluidly connect the plurality of groups to the at least one receiving vessel. The controller may be operable to determine a required amount of gas to be delivered to the at least one receiving vessel, and wherein the controller is operable to, in the first operation and / or second operation, deliver the required amount of gas to the at least one receiving vessel.

[0134] Advantageously, rather than attempting to completely fill the receiving vessel, the controller can determine an amount of gas required by the receiving vessel and deliver the required amount of gas. The required amount of gas may be less than the storage capacity of the receiving vessel. This conserves pressure in the gas storage unit as high pressures are not necessarily required to fill or attempt to fill the receiving vessel completely.

[0135] The controller may be operable to determine the required amount of gas to be delivered to the at least one receiving vessel based on a calculation of the expected gas consumption for the at least one receiving vessel over a period of time.

[0136] Advantageously, the controller estimates the amount of gas required for the receiving vessel based on an expected consumption of-gas by the receiving vessel over a period of time. The period of time may be arbitrary or may be specified by the user (e.g., 1 day).

[0137] The at least one receiving vessel may comprise a plurality of receiving vessels.

[0138] The at least one receiving vessel may comprise a receiving vessel configured for transportation of gas for subsequent use by an end consumer or may comprise a receiving vessel configured to store gas for subsequent use by an end consumer.

[0139] The controller may be operatable to determine a required amount of gas to be delivered to each of the plurality of receiving vessels.

[0140] Advantageously, rather than attempting to completely fill each receiving vessel, the controller can determine an amount of gas required by each receiving vessel and deliver the required amount of gas. The required amount of gas may be less than the storage capacity of the receiving vessel. This conserves pressure in the gas storage unit as high pressures are not necessarily required to fill or attempt to fill the receiving vessel completely.

[0141] The controller may be operable to determine the required amount of fuel gas to be delivered to the plurality of receiving vessels based on a calculation of the expected gas consumption for the plurality of receiving vessels over a period of time.

[0142] The controller may be operable to determine an order for filling the plurality of receiving vessels. Advantageously, the controller determines an order for filling the receiving vessels. The determined order can help optimise the number of receiving vessels filled with their required amounts of gas, the utilisation of gas storage in the gas storage unit, and the energy consumption of the filling process.

[0143] The controller may be operable to determine the order for filling the plurality of receiving vessels based on a determined gas storage pressure for each of the plurality of receiving vessels.

[0144] Gas storage pressure refers to the pressure at which gas is required to be stored in each of the receiving vessels. The gas storage pressure can be determined from the calculation for how much gas is required. In more detail, the amount of gas identifies that mass of gas required. Parameters such as the volume of the receiving vessels, expected storage temperature, and equations for real gas behaviour are used to convert the required mass of fuel gas to a storage pressure.

[0145] The determined order may prioritise receiving vessels having higher gas storage pressures over receiving vessels having lower fuel gas storage pressures.

[0146] Advantageously, the controller determines an order for filling the receiving vessels that prioritises fuelling receiving vessels with higher gas storage pressures. This helps ensure that these receiving vessels can be fuelled sufficiently while the pressure in the gas storage unit is high. In turn, this approach reduces the amount of energy consumption required for filling as the initiation of the second operation mode can be delayed.

[0147] The determined order may specify filling the receiving vessels in order of decreasing gas storage pressure.

[0148] Advantageously, the controller determines an order for filling which fills the receiving vessels in order of decreasing gas storage pressure. This helps ensure that the high pressure receiving vessels are filled first while the pressure in the gas storage unit is high. In turn, this approach reduces the amount of energy consumption required for filling as the initiation of the second operation mode can be delayed.

[0149] The controller may be operable to fill the plurality of receiving vessels according to the determined order.

[0150] According to a sixth aspect of the present disclosure, there is a method of transferring gas.

[0151] The method comprises, in a first operation, sequentially fluidly connecting a plurality of storage vessels of a gas storage unit to at least one receiving vessel so as to deliver gas from the vessels to the at least one receiving vessel. The method comprises, in a second operation, activating a compressor to increase the pressure of the gas.

[0152] The second operation may be performed after the first operation. The second operation may be performed at the same time as the first operation. The concurrent performance of the first and second operations may occur when it is determined to be beneficial such as due to there being a minimal pressure differential between the gas storage unit and receiving vessel. The concurrent performance of the first and second operation may also occur when a rapid filling is desired to take place.

[0153] The method may transition from the first operation to the second operation in response to detecting a trigger condition. The trigger condition may be indicative of the first operation being unable to deliver subsequent gas to the at least one receiving vessel due to pressure equilibrium being reached. The method may automatically transition from the first operation to the second operation without user input.

[0154] The trigger condition may comprise the flow rate of gas from one or more of the storage vessels falling below a threshold value.

[0155] The trigger condition may comprise the pressure in one or more of the plurality of storage vessels falling below a threshold value.

[0156] Activating the compressor may comprise activating an operating fluid delivery means to deliver an operating fluid such that the operating fluid is brought into contact with the gas to increase the pressure of the gas. The operating fluid therefore acts as a liquid piston.

[0157] The operating fluid delivery means may deliver the operating fluid to the gas storage unit to increase the pressure of gas contained within one or more of the storage vessels of the gas storage unit.

[0158] The gas storage unit may be a first gas storage unit. The compressor may comprise a second gas storage unit for storing gas. The second gas storage unit may be fluidly connectable to the first gas storage unit. The operating fluid delivery means may deliver the operating fluid to the second gas storage unit to increase the pressure of gas contained within the second gas storage unit.

[0159] The second gas storage unit may be arranged to receive gas from at least one storage vessel of the first gas storage unit.

[0160] The operating fluid delivery means may deliver the operating fluid to the second gas storage unit to increase the pressure of the gas received from the at least one storage vessel of the first gas storage unit.

[0161] The second gas storage unit may deliver gas to the at least one receiving vessel.

[0162] The second gas storage unit may deliver gas to at least one storage vessel of the first gas storage unit.

[0163] The method may comprise determining a required amount of gas to be delivered to the at least one receiving vessel in the first operation and / or second operation. The determining of the required amount of gas to be delivered to the at least one receiving vessel may be based on a calculation of the expected gas consumption for the at least one receiving vessel over a period of time.

[0164] The at least one receiving vessel may comprise a plurality of receiving vessels.

[0165] The method may comprise determining a required amount of gas to be delivered to each of the plurality of receiving vessels.

[0166] The method may comprise determining the required amount of gas to be delivered to the plurality of receiving vessels based on a calculation of the expected gas consumption for the plurality of receiving vessels over a period of time.

[0167] The method may comprise determining an order for filling the plurality of receiving vessels.

[0168] The determining of the order for filling the plurality of receiving vessels may be based on a determined gas storage pressure for each of the plurality of receiving vessels.

[0169] The determined order may prioritise receiving vessels having higher gas storage pressures.

[0170] The determined order may specify filling the receiving vessels in order of decreasing gas storage pressure.

[0171] The method may comprise delivering gas to the plurality of receiving vessels according to the determined order.

[0172] According to a seventh aspect of the present disclosure, there is provided a gas production and delivery system for delivery of gas to an end consumer, the gas production and delivery system comprising one or more gas transfer systems.

[0173] The gas production and delivery system comprises a gas production system. The gas production system may be a hydrogen gas production system.

[0174] The, or each, gas transfer system may have any of, or all, the features of the system for fuelling of the first aspect but need not necessarily be used for fuelling and the gas need not necessarily be a fuel gas and may be a gas other than fuel gas.

[0175] The gas production and delivery system may comprise a gas transfer system arranged to transfer gas to at least one receiving vessel configured for transportation of gas for subsequent use by an end consumer. The at least one receiving vessel configured for transportation of gas for use by an end consumer may comprise a mobile storage tank. The gas transfer system arranged to transfer gas to at least one receiving vessel configured for transportation of gas for subsequent use by an end consumer may be located at a hydrogen gas production site. The gas transfer system arranged to transfer gas to at least one receiving vessel configured for transportation of gas for subsequent use by an end consumer may be arranged to receive gas from a gas production system, such as hydrogen gas production system.

[0176] The gas production and delivery system may comprise a gas transfer system arranged to transfer gas to at least one receiving vessel configured to store gas for subsequent use by an end consumer. The gas stored in the at least one receiving vessel configured to store gas for subsequent use by an end consumer may be fuel gas. The at least one receiving vessel configured to store gas for subsequent use by an end consumer may comprise a storage tank. The storage tank may be located at the hydrogen gas production site and may comprise an on-site storage tank. The storage tank may be a vehicle storage tank for storage of fuel gas.

[0177] BRIEF DESCRIPTION OF THE DRAWINGS

[0178] Examples of the present disclosure will now be described with reference to the accompanying drawings, in which:

[0179] Figure 1 shows a schematic diagram of an example hydrogen gas production and delivery system according to aspects of the present disclosure;

[0180] Figures 2 and 3 show schematic diagrams of example fuelling systems for delivering hydrogen gas according to aspects of the present disclosure.

[0181] Figure 4 shows a schematic diagram for an example control system for controlling a fuelling system according to aspects of the present disclosure.

[0182] Figures 5 and 6 show flow diagrams of example methods of fuelling according to aspects of the present disclosure.

[0183] Figure 7 shows a schematic diagram of another example fuelling system for delivering hydrogen gas according to aspects of the present disclosure.

[0184] DETAILED DESCRIPTION

[0185] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the disclosure as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.

[0186] The terms and words used in the following description and claims are not limited to the bibliographical meanings, but are merely used by the inventor to enable a clear and consistent understanding of the disclosure. Accordingly, it should be apparent to those skilled in the art that the following description of various embodiments of the disclosure is provided for illustration purpose only and not for the purpose of limiting the disclosure as defined by the appended claims and their equivalents.

[0187] It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

[0188] The following examples refer to fuel gas in the form of hydrogen gas. The skilled person will appreciate that the present disclosure is not limited to hydrogen gas and other fuel gases may be used. Example fuel gasses include methane gas, propane gas, hydrogen gas, ammonia gas, carbon monoxide gas or a mixture of one or more of these gases. The fuel gas may be syngas which comprises a mixture of hydrogen gas and carbon monoxide gas.

[0189] Furthermore, whilst the following examples refer to fuel gases and fuelling systems, it will be readily appreciated by the skilled person that the example fuelling systems described herein may be equally advantageous in other scenarios requiring the transfer of gases for purposes other than fuelling, for example, the transfer of gases for use in industrial processes. Accordingly, the fuelling systems may also be applied as transfer systems for the transfer of gases and as such, the skilled person will also appreciate that the present disclosure is not limited to the transfer of fuel gases for fuelling, the term “fuel gas” merely indicating the intended purpose of the gas. The systems described herein may therefore be used for transferring any gas, including gases such as oxygen, nitrogen, helium, argon and compressed air in addition to the above-mentioned gases, regardless of whether these above- mentioned gases are intended for fuelling purposes or otherwise.

[0190] Figure 1 shows an example system 100 according to aspects of the present disclosure for the production and delivery of hydrogen gas to end consumers.

[0191] A hydrogen gas production system 102 produces hydrogen gas. Hydrogen gas can be produced in a variety of ways including steam reforming of natural gas or biomass, partial oxidation of methane, coal gasification, biomass gasification, biomass pyrolysis, methane pyrolysis with carbon capture, pressure swing adsorption to recovery hydrogen gas from a gas stream, and electrolysis of water.

[0192] The produced hydrogen gas typically has a low pressure. Generally, produced hydrogen gas has a pressure of less than 30 bar, the pressure may be less than 20 bar, and the pressure may be less than 15 bar. The pressure of the hydrogen gas may be in the region of 5 bar to 15 bar. However, some methods of hydrogen production such as hydrogen electrolysis and pressure swing adsorption may result in higher hydrogen gas pressures.

[0193] The hydrogen gas produced by the hydrogen gas production system 102 is compressed to reach a higher pressure for transport and delivery to an end consumer. The hydrogen gas compressor 104 compresses the hydrogen gas to a desired higher pressure. The hydrogen gas compressor 104 is located at the hydrogen gas production site.

[0194] In this example, the hydrogen gas is compressed by the hydrogen gas compressor 104 to a pressure of between 250 bar and 350 bar. Other and even higher pressures may be achieved.

[0195] The hydrogen gas compressor 104 in this example is a multi-stage compression system. A first stage of the compression system boosts the pressure of the hydrogen gas to an initial pressure typically of about 50 bar. The pressurised hydrogen gas is delivered to a hydrogen gas storage unit where it undergoes a further stage of compression to reach the desired high pressure. A multi-stage compression system is not required in all examples.

[0196] The compressed hydrogen gas is delivered to a mobile storage tank 106. The mobile storage tank 106 is mobile in the sense that it can be moved from the hydrogen gas production site to a hydrogen storage site or other location like a hydrogen fuelling site. The mobile storage tank 106 is typically transported by a fuel tanker which may be any form of vehicle used to transport hydrogen fuel as known in the art. The mobile storage tank 106 in this example has a volume of between 30 m3 and 50 m3 for storing hydrogen gas. Other capacities of mobile storage tank 106 are within the scope of the present disclosure. The mobile storage tank 106 may be arranged to store hydrogen gas at a pressure of between 250 bar and 350 bar. The pressure of the hydrogen gas stored in the mobile storage tank is not limited to this pressure range. Other and even higher pressures may be used.

[0197] The mobile storage tank 106 typically comprises a plurality of pressure vessels (e.g., cylinders) for storing hydrogen gas.. The mobile storage tank 106 may also comprise a housing such as a shipping container which allows for easy transport and storage of the mobile storage tank 106. The number of pressure vessels in the mobile storage tank 106 will depend on the application and level of mobility desired. Some mobile storage tanks 106 may have a hundred or more pressure vessels and be transported by tanker while other mobile storage tanks 106 comprise less than a hundred pressure vessels and can be transported by smaller vehicles.

[0198] The mobile storage tank 106 may have between 2 and 500 pressure vessels. The mobile storage tank 106 may have between 5 and 500 pressure vessels. The mobile storage tank 106 may have between 10 and 500 pressure vessels. The mobile storage tank 106 may have between 12 and 500 pressure vessels. The mobile storage tank 106 may have between 20 and 500 pressure vessels. The mobile storage tank 106 may have between 50 and 500 pressure vessels. The mobile storage tank 106 may have between 100 and 500 pressure vessels. The mobile storage tank 106 may have between 200 and 500 pressure vessels. The mobile storage tank 106 may have between 2 and 200 pressure vessels. The mobile storage tank 106 may have between 2 and 100 pressure vessels. The mobile storage tank 106 may have between 2 and 50 pressure vessels. The mobile storage tank 106 may have between 2 and 20 pressure vessels. The mobile storage tank 106 may have between 2 and 12 pressure vessels. The mobile storage tank 106 may have between 2 and 10 pressure vessels. The mobile storage tank 106 may have between 2 and 5 pressure vessels.

[0199] It will be appreciated that a plurality of mobile storage tanks 106 may be located at the hydrogen gas production site and may be filled by the hydrogen gas compressor 104. The plurality of mobile storage tanks 106 may be filled at the same time.

[0200] In this example, the mobile storage tank 106 is transported by the fuel tanker to a hydrogen fuelling site. Fuel tankers typically have a capacity of between 30 m3 and 70 m3 for storing hydrogen gas and can store between 500 kg and 1500 kg of hydrogen gas. Fuel tankers are normally containerised, multitube, high-pressure tanks.

[0201] At the hydrogen fuelling site, the system 100 further comprises a hydrogen gas fuelling system 110. The hydrogen gas fuelling system 110 comprises a fuel gas storage unit 112 (main storage tank 112). The hydrogen gas is transferred from the mobile storage tank 106 to the main storage tank 112 using a transfer compressor 108.

[0202] In some examples, the transfer compressor 108 is a dedicated compressor system. The dedicated compressor system comprises a hydrogen gas storage unit that receives hydrogen gas from the mobile storage tank 106 and delivers the hydrogen gas to the storage tank 1 12.

[0203] In some examples, the mobile storage tank 106 is used as the fuel gas storage unit for the transfer compressor 108. In effect, the mobile storage tank 106 is used as the compression cylinder. This approach reduces the complexity of gas delivery from the storage tanks as fewer components are required.

[0204] The main storage tank 1 12 located at the hydrogen fuelling site may have a larger capacity than the mobile storage tank 106. The main storage tank 112 may have a volume of between 100 m3 and 500 m3. The main storage tank 112 may be arranged to store hydrogen gas at a pressure of between 300 bar and 500 bar. Other and even higher pressures may be used.

[0205] The main storage tank 112 typically comprises a plurality of pressure vessels (e.g., cylinders) for storing hydrogen gas. At least 200 pressure vessels may be provided in some examples. The main storage tank 112 may also comprises a housing such as one or multiple shipping containers or a fixed structure. The hydrogen gas fuelling system 110 further comprises a compressor 114 as explained in greater detail below. The compressed hydrogen gas is delivered to end consumers (e.g., vehicle tanks) using the hydrogen gas fuelling system 110.

[0206] Valves 116 are provided to control the flow of hydrogen gas around the hydrogen fuel delivery system 100.

[0207] In some examples, the hydrogen gas is not transferred to a main storage tank at the hydrogen fuelling site. Instead, the mobile storage tank 106 is stored at the hydrogen fuelling site. The mobile storage tank 106 is stored with other mobile storage tanks to form a stacked hydrogen gas storage structure. The mobile storage tank 106 in this example may be a containerised unit. It will be appreciated that in this example, a transfer compressor is not required. In this example, the mobile storage tank 106 forms part of the hydrogen gas fuelling system 110.

[0208] In an example, between 5 and 20 mobile storage tanks are stored together to form the stacked hydrogen storage structure. The stacked hydrogen storage structure may have a volume of between 100 m3 and 500 m3 and may store hydrogen gas at a pressure of between 250 bar and 350 bar.

[0209] In some examples, the hydrogen is produced, stored and delivered to end consumers at the same location. The compressed hydrogen gas is not delivered to mobile storage tanks, but is instead transferred directly to an on-site main storage tank 112 using a transfer compressor 108.

[0210] In some examples, the compressed hydrogen gas is transferred to a pipeline system for transfer from the hydrogen gas production site to the fuelling site. The delivery pressure for pipeline transport may be in the region of 10 bar to 100 bar. At the fuelling site, the hydrogen gas is transferred from the pipeline system to a main storage tank 112 using a transfer compressor 108. At the fuelling site, the hydrogen gas is further compressed by the transfer compressor 108 to a higher pressure such as in the range of 300 bar to 500 bar.

[0211] The above example hydrogen gas delivery systems all use hydrogen gas compression at various stages of the delivery process. Hydrogen gas is initially compressed to a high pressure at the production site using compressor system 104. Transfer compressor 108, when provided, is used to deliver (i.e., pump) hydrogen gas to the main storage tank 112. Fuel compressor 114 is used to deliver (i.e., pump) hydrogen gas from storage to the end consumer.

[0212] The present disclose is directed towards providing improves systems and method for delivering the fuel gas to the end consumer at the fuelling site. At the fuelling site, the hydrogen gas is stored in a storage tank (also referred to as a storage unit) that may be a main storage tank 112 as described above or one or more mobile storage tanks as also described above. Figure 2 shows the hydrogen gas fuelling system 110 in isolation.

[0213] The hydrogen gas fuelling system 110 comprises a fuel gas storage unit 112 (e.g., main storage tank 112) that defines an internal volume for storing hydrogen gas. The fuel gas storage unit 112 comprises a plurality (four in this example) of storage vessels 202, 204, 206, 208 for storing the hydrogen gas. The storage vessels 202, 204, 206, 208 are in the form of cylinders and may be referred to as compressor cylinders. The cylinders are vertically aligned along their axis in this example but may be oriented in any way such that the gas outlet is disposed above the level of the operating fluid.

[0214] The plurality of storage vessels 202, 204, 206, 208 may be grouped into a plurality of groups each comprising one or more of the plurality of vessels 202, 204, 206, 208.

[0215] The example of Figure 2 shows a simplified fuel gas storage unit 112 comprising four storage vessels 202, 204, 206, 208. In practice, a greater number of storage vessels may be provided. For example, typically twenty or more storage vessels are provided which may be grouped into a smaller number of banks. Typically, each bank comprises five or fewer storage vessels.

[0216] Each of the storage vessels 202, 204, 206, 208 comprises a gas outlet 210, 212, 214, 216 connected to pipework 218 that enables hydrogen gas to be delivered from the storage vessels 202, 204, 206, 208 to at least one receiving vessel A (e.g., a vehicle tank).

[0217] Flow control devices in the form of valves 220, 222, 224, 226 are provided to selectively fluidly connect the storage vessels 202, 204, 206, 208 to the at least one receiving vessel A. Selectively fluidly connecting the storage vessels 202, 204, 206, 208 to the at least one receiving vessel A means that a storage vessel or group of storage vessels can be fluidly connected to the at least one receiving vessel A while other storage vessels are fluidly isolated from the at least one receiving vessel A.

[0218] Each of the valves 220, 222, 224, 226 is associated with one of the storage vessels 202, 204, 206, 208 in this example. In some examples, the valves 220, 222, 224, 226 may each be associated with one group of vessels.

[0219] A further shut-off valve 228 is provided to control the flow of fuel gas from the fuel gas storage unit 112 to allow for the selective delivery of fuel gas.

[0220] The fuel gas storage unit 1 12 further comprises a fluid inlet 230 via which an operating fluid may be delivered to the fuel gas storage unit 112. The operating fluid is delivered to the fuel gas storage unit 112 via the fluid inlet so as to decrease the available volume in the fuel gas storage unit 112 for the fuel gas to thereby cause the fuel gas to compress and the pressure of the fuel gas to increase. It will be appreciated that the operating fluid may be delivered to each of the plurality of storage vessels 202, 204, 206, 208. A single fluid inlet 230 may be operatively connected to the plurality of storage vessels 202, 204, 206, 208 or a plurality of fluid inlets may be provided each associated with one or more of the cylinders 506.

[0221] The operating fluid may be water or may be an ionic fluid. Other forms of operating fluid may be used. The fuel gas storage unit 1 12 further comprises a plurality of fluid outlets 232 via which the operating fluid may be withdrawn from the fuel gas storage unit 112. Each of the plurality of fluid outlets 232 is associated with one (or more) of the storage vessels 202, 204, 206, 208. It will be appreciated that the operating fluid may be withdrawn from each of the plurality of storage vessels 202, 204, 206, 208. Instead of a plurality of fluid outlets 232, a single fluid outlet may be provided.

[0222] The operating fluid is delivered to the base of each of the storage vessels 202, 204, 206, 208. As operating fluid is delivered to the storage vessels 202, 204, 206, 208, the level of the operating fluid 234 in each of the storage vessels 202, 204, 206, 208 rises to decrease the available volume for hydrogen gas within the storage vessels 202, 204, 206, 208. The operating fluid 234 acts as a liquid piston.

[0223] In the example shown in Figure 2, each of the storage vessels 202, 204, 206, 208 contains a different level of operating fluid 234. This is because the storage vessels 202, 204, 206, 208 had different pressure levels prior to the delivery of operating fluid 234. The operating fluid 234 flows preferentially to the vessel with the lowest pressure first.

[0224] The gas outlets 210, 212, 214, 216 are positioned towards the top of the fuel gas storage unit 112. The fluid inlet 230 is positioned towards the base of the fuel gas storage unit 112. The fluid outlets 232 are positioned towards the base of the fuel gas storage unit 112 and, in this example, are positioned on the bottom system of the fuel gas storage unit 112.

[0225] The system 100 further comprises a compressor 114 for compressing fuel gas. The compressor 114 114 comprises a fluid delivery means 236 for delivering the operating fluid to the fuel gas storage unit 112 via the fluid inlet 230. A fluid reservoir 238 is also provided to store the operating fluid. The fluid deliver means 236 is a pump in this example and may be, for example, a centrifugal pump or positive displacement pump. The operating fluid is typically delivered at high pressure.

[0226] A controller (not shown) is provided to control the operation of the system 110.

[0227] In an example fuelling operation, the controller controls the system to perform a multi-stage process to dispense fuel to the at least one receiving vessel.

[0228] A first stage of the process is a pressure cascade process where the storage vessels 202, 204, 206, 208 are selectively fluidly connected to the at least one receiving vessel A to allow for the fuel gas stored at high pressure in the storage vessels 202, 204, 206, 208 to be delivered to the at least one receiving vessel A. During the pressure cascade process the fluid delivery means 236 is not activated.

[0229] The controller selectively fluidly connects the storage vessels 202, 204, 206, 208 to the at least one receiving vessel A via operation of the valves 220, 222, 224, 226. The controller selectively opens / closes the valves 124, 126, 128, 130 to selectively fluidly connect the plurality of storage vessels 202, 204, 206, 208 to the at least one receiving vessel A such that the plurality of storage vessels 202, 204, 206, 208 are individually, or in groups, connected to the at least one receiving vessel A.

[0230] In a pressure cascade process, the controller connects the storage vessels 202, 204, 206, 208 to the at least one receiving vessel A in a sequence. The sequence typically starts by connecting the storage vessel (or group of storage vessels) with the lowest pressure (e.g., storage vessel 202) to the at least one receiving vessel A. The other storage vessels are not fluidly connected to the at least one receiving vessel A and are thus fluidly isolated from the at least one receiving vessel A and the storage vessel 202. Gas will flow from the storage vessel 202 to the at least one receiving vessel A until pressure equilibrium is reached. The controller then connects the storage vessel (or group of storage vessels) with the next lowest pressure (e.g., storage vessel 204) to the at least one receiving vessel A. The other storage vessels are not fluidly connected to the at least one receiving vessel A and are thus fluidly isolated from the at least one receiving vessel A and the storage vessel 204. Gas will flow from the storage vessel 202 to the at least one receiving vessel A until pressure equilibrium is reached. This process can be repeated by sequentially connecting the storage vessels 202, 204, 206, 208 in order of increasing pressure.

[0231] Significantly, after the pressure cascade process, the controller commences a second stage of the fuelling process. The second stage of the fuelling process can commence once the pressure cascade process is no longer able to dispense the full amount of hydrogen gas required. This occurs when there is no longer the required pressure differential between the storage vessels 202, 204, 206, 208 and the at least one receiving vessel A. That is, the storage vessels 202, 204, 206, 208 and the at least one receiving vessel A are substantially at pressure equilibrium.

[0232] In the second stage of the fuelling process, the controller controls the fluid delivery means 236 to deliver operating fluid into the base of the storage vessels 202, 204, 206, 208 via the fluid inlet 230 so as to decrease the available volume for hydrogen gas within the storage vessels 202, 204, 206, 208. This causes the pressure of the hydrogen gas stored within the fuel gas storage unit 112 to increase. As the pressure of the hydrogen gas stored within the fuel gas storage unit 112 is increased, hydrogen gas is able to flow from the fuel gas storage unit 112 to the at least one receiving vessel A.

[0233] Advantageously, operation of the fluid delivery means 236 in the second stage of the fuelling process boosts the pressure of the hydrogen gas within the fuel gas storage unit 112 and extends the delivery of hydrogen gas. Moreover, as the fluid delivery means 236 is activated after the pressure cascade process the energy input to achieve the fuel dispensing process is minimised. This approach allows the contents of each storage vessel 202, 204, 206, 208 to be almost completely dispensed which may not be achievable using pressure cascading alone.

[0234] The fluid delivery means 236 may be controlled to deliver operating fluid at a controlled rate so as to maintain a desired delivery pressure and flow rate.

[0235] In the second stage of the fuelling process, the controller is not required to sequentially connect the storage vessels 202, 204, 206, 208 to the at least one receiving vessel although the controller may sequentially connect the storage vessels 202, 204, 206, 208 if desired. That is, pressure cascading may be used in conjunction with the operation of the fluid delivery means 236 but is not required.

[0236] The controller may transition from the first stage of the fuelling process to the second stage of the fuelling process in response to a trigger condition. The trigger condition is indicative of the first stage of the fuelling process being no longer able to deliver the required fuel gas to the at least one receiving vessel A. The trigger condition may comprise the flow rate of fuel gas from one or more of the storage vessels 202, 204, 206, 208 falling below a threshold value. The trigger condition may comprise the pressure in one or more of the plurality of storage vessels 202, 204, 206, 208 falling below a threshold value.

[0237] In the example of Figure 2, the compressor 1 14 is not a stand-alone system and instead uses the fuel gas storage unit 112 as the compressor tank. This means that the operating fluid is delivered to the fuel gas storage unit 112. This is not required in all examples. For example, a dedicated storage unit for compression may be provided as shown in the example of Figure 3. While the dedicated storage unit for compression increases the complexity of the system, it has benefits in terms of being able to more rapidly boost the pressure of the hydrogen gas. The dedicated storage unit can have a smaller volume than the fuel gas storage unit 112 which enables faster compression of hydrogen gas for refuelling. The example of Figure 2 enables the pressure of a large volume of hydrogen gas to be boosted at the same time which is typically not needed for most refuelling applications where only a small quantity of the hydrogen gas within the fuel gas storage unit 112 needs to be delivered to the receiving vessel. The example of Figure 3 therefore enables a small quantity of hydrogen gas to be rapidly boosted in pressure for delivery to the receiving vessel.

[0238] Figure 3 shows another example fuel delivery system 110 according to aspects of the present disclosure. The system 110 is similar to the system 110 of Figure 2 and like reference numerals are used to indicate like components.

[0239] In the example of Figure 3, the compressor 1 14 is separate from the fuel gas storage unit 112. In more detail, the fuel gas storage unit 112 is a first fuel gas storage unit 112 of the system and the compressor 114 comprises a second fuel gas storage unit 302. The second fuel gas storage unit 302 comprises a plurality (two in this example) of storage vessels 304, 306. The storage vessels 304, 306 are in the form of cylinders and may be referred to as compressor cylinders. The cylinders are vertically aligned along their axis. The storage vessels 304, 306 may have a smaller capacity than the storage vessels 202, 204, 206, 208 (Figure 2) of the first fuel gas storage unit 112.

[0240] Each of the storage vessels 304, 306 comprises a gas outlet 308, 310 connected to pipework 218 that enables hydrogen gas to be delivered from the storage vessels 304, 306 to at least one receiving vessel A (e.g., a vehicle tank).

[0241] Flow control devices in the form of valves 312, 314 are provided to selectively fluidly connect the storage vessels 304, 306 to the at least one receiving vessel A. Each of the valves 312, 314 is associated with one of the storage vessels 304, 306. Additional valves 228, 316, 318 are provided to control the flow of fuel gas in the pipework 218.

[0242] The second fuel gas storage unit 302 further comprises a fluid inlet 320 via which an operating fluid may be delivered to the second fuel gas storage unit 302. The operating fluid is delivered to the second fuel gas storage unit 302 via the fluid inlet 320 so as to decrease the available volume in the second fuel gas storage unit 302 for the fuel gas to thereby cause the fuel gas to compress and the pressure of the fuel gas to increase. It will be appreciated that the operating fluid may be delivered to each of the plurality of storage vessels 304, 306. A single fluid inlet 320 may be operatively connected to the plurality of storage vessels 304, 306 or a plurality of fluid inlets may be provided each associated with one or more of the storage vessels 304, 306.

[0243] The operating fluid may be water or may be an ionic fluid. Other forms of operating fluid may be used.

[0244] The second fuel gas storage unit 112 further comprises a plurality of fluid outlets 322 via which the operating fluid may be withdrawn from the second fuel gas storage unit 302. Each of the plurality of fluid outlets 322 is associated with one (or more) of the storage vessels 304, 306. It will be appreciated that the operating fluid may be withdrawn from each of the plurality of storage vessels 304, 306. Instead of a plurality of fluid outlets 322, a single fluid outlet may be provided.

[0245] The operating fluid is delivered to the base of each of the storage vessels 304, 306. As operating fluid is delivered to the storage vessels 304, 306, the level of the operating fluid in each of the storage vessels 304, 306 rises to decrease the available volume for hydrogen gas within the storage vessels 304, 306. The operating fluid acts as a liquid piston. In the example shown in Figure 3, each of the storage vessels 304, 306 contains a different level of operating fluid. This is because the storage vessels 304, 306 had different pressure levels prior to the delivery of operating fluid.

[0246] The gas outlets 308, 310 are positioned towards the top of the second fuel gas storage unit 302. The fluid inlet 320 is positioned towards the base of the second fuel gas storage unit 302. The fluid outlets 322 are positioned towards the base of the second fuel gas storage unit 302 and, in this example, are positioned on the bottom system of the second fuel gas storage unit 302.

[0247] The compressor 1 14 comprises a fluid delivery means 236 for delivering the operating fluid to the second fuel gas storage unit 302 via the fluid inlet 320. A fluid reservoir 238 is also provided to store the operating fluid. The fluid delivery means 236 is a pump in this example and may be, for example, a centrifugal pump or positive displacement pump. The operating fluid is typically delivered at high pressure.

[0248] A controller is provided to control the operation of the system 110.

[0249] In an example fuelling operation, the controller controls the system to perform a multi-stage process to dispense fuel to the at least one receiving vessel. The fuelling operation is similar to the fuelling operation of Figure 2.

[0250] A first stage of the process is a pressure cascade process where the storage vessels 202, 204, 206, 208 (Figure 2) of the first fuel gas storage unit 1 12 are selectively fluidly connected to the at least one receiving vessel A to allow for the fuel gas stored at high pressure in the storage vessels 202, 204, 206, 208 to be delivered to the at least one receiving vessel. During the pressure cascade process the fluid delivery means 236 is not activated. The valves 312, 314 are closed and the second fuel gas storage unit 302 is fluidly isolated from the first fuel gas storage unit 1 12.

[0251] The controller selectively fluidly connects the storage vessels 202, 204, 206, 208 (Figure 2) to the at least one receiving vessel A via operation of the valves 220, 222, 224, 226 (Figure 2). The controller selectively opens / closes the valves 220, 222, 224, 226 to selectively fluidly connect the plurality of storage vessels 202, 204, 206, 208 the at least one receiving vessel A such that the plurality of storage vessels 202, 204, 206, 208 are individually, or in groups, connected to the at least one receiving vessel A.

[0252] In a pressure cascade process, the controller connects the storage vessels 202, 204, 206, 208 to the at least one receiving vessel A in a sequence. The sequence typically starts by connecting the storage vessel (or group of storage vessels) with the lowest pressure (e.g., storage vessel 202) to the at least one receiving vessel A. The other vessels are not fluidly connected to the at least one receiving vessel A and are thus fluidly isolated from the at least one receiving vessel A and the storage vessel 202. Gas will flow from the storage vessel 202 to the at least one receiving vessel A until pressure equilibrium is reached. The controller then connects the vessel (or group of vessels) with the next lowest pressure (e.g., storage vessel 204) to the at least one receiving vessel A. The other vessels are not fluidly connected to the at least one receiving vessel A and are thus fluidly isolated from the at least one receiving vessel A and the storage vessel 204. Gas will flow from the storage vessel 202 to the at least one receiving vessel A until pressure equilibrium is reached. This process can be repeated by sequentially connecting the storage vessels 202, 204, 206, 208 in order of increasing pressure.

[0253] Significantly, after the pressure cascade process, the controller commences a second stage of the fuelling process. The second stage of the fuelling process can commence once the pressure cascade process is no longer able to dispense the full amount of fuel gas required. This occurs when there is no longer the required pressure differential between the storage vessels 202, 204, 206, 208 and the at least one receiving vessel A. That is, the storage vessels 202, 204, 206, 208 and the at least one receiving vessel A are substantially pressure equilibrium.

[0254] In the second stage of the fuelling process, the controller fluidly connects the second fuel gas storage unit 302 to the first fuel gas storage unit 112. The second fuel gas storage unit 302 receives hydrogen gas from the first fuel gas storage unit 1 12. The controller controls the fluid delivery means 236 to deliver operating fluid to the base of the storage vessels 304, 306 of the second fuel gas storage unit 302 so as to decrease the available volume for hydrogen gas within the storage vessels 304, 306. This causes the pressure of the hydrogen gas stored within the second fuel gas storage unit 302 to increase.

[0255] In some examples, the pressurised hydrogen gas is transferred back to the first fuel gas storage unit 112. This enables the pressure of hydrogen gas to be boosted and allows for extended delivery of hydrogen gas to the at least one receiving vessel A via the first fuel gas storage unit 112.

[0256] The second fuel gas storage unit 302 may receive hydrogen gas from a storage vessel of the first fuel gas storage unit 112 having a low pressure and may transfer pressurized hydrogen gas to a storage vessel of the first fuel gas storage unit 1 12 having a higher pressure. In this way, pressure is boosted in one or more of the vessels of the first fuel gas storage unit 1 12 while pressure is decreased in the one or more vessels from which the hydrogen gas was withdrawn. In this arrangement it will be appreciated that there is a transfer of mass between storage vessels in the fuel gas storage unit 112. The first fuel gas storage unit 1 12 can be used to deliver fuel to the at least one receiving vessel A using pressure cascading as described above for the first stage of the fuelling process.

[0257] In some examples, the pressurised hydrogen gas is transferred from the second fuel gas storage unit 302 to the at least one receiving vessel. As the pressure of the hydrogen gas stored within the second fuel gas storage unit 302 is increased, hydrogen gas is able to flow from the fuel gas storage unit 302 to the at least one receiving vessel A. It will be appreciated that the controller may transition between controlling the second fuel gas storage unit 302 to transfer hydrogen gas to the first fuel gas storage unit 112 and controlling the second fuel gas storage unit 302 to transfer hydrogen gas to the at least one receiving vessel A. The controller may transition between these different hydrogen gas transfer operations in order to optimise delivery, maximise filling, and minimise energy consumption.

[0258] It will be appreciated that vales 316, 318, and 218 are used to selectively isolate / fluidly connect the first fuel gas storage unit 112 / second fuel gas storage unit 302 / at least one receiving vessel at different times during the fuel dispensing process.

[0259] Advantageously, operation of the fluid delivery means 236 in the second stage of the fuelling process boosts the pressure of the hydrogen gas such that it can be delivered to the at least one receiving vessel A once the first stage of the fuel delivery process is unable to achieve the desired fuel dispensing. This allows for the extension of the delivery of gas whilst minimising the energy input to achieve the fuel dispensing process. This approach allows the contents of each storage vessel 202, 204, 206, 208 to be almost completely dispensed.

[0260] The fluid delivery means 236 may be controlled to deliver operating fluid at a controlled rate so as to maintain a desired delivery pressure and flow rate.

[0261] In the second stage of the fuelling process, the controller is not required to sequentially connect the storage vessels 202, 204, 206, 208 to the at least one receiving vessel although the controller may sequentially connect the storage vessels 202, 204, 206, 208 if desired.

[0262] The controller may transition from the first stage of the fuelling process to the second stage of the fuelling process in response to a trigger condition. The trigger condition is indicative of the first stage of the fuelling process being no longer able to deliver the required fuel gas to the at least one receiving vessel A. The trigger condition may comprise the flow rate of fuel gas from one or more of the vessels 202, 204, 206, 208 falling below a threshold value. The trigger condition may comprise the pressure in one or more of the plurality of vessels 202, 204, 206, 208 falling below a threshold value.

[0263] The above examples show the system 1 10 delivering fuel gas to a single receiving vessel A. It will be appreciated that the system 110 can be used for fuelling a plurality of receiving vessels. The receiving vessels may be simultaneously connected to the system 110 or may be connected to the system 110 at different times.

[0264] In addition to the above stages of the fuelling process, the controller may also use algorithms to determine a fuelling routine for fuelling the plurality of receiving vessels. The fuelling routine may determine the amount of hydrogen gas to be delivered to each of the receiving vessels and the sequence of fuelling the receiving vessels. The fuelling routine may be used in conjunction with the first stage and / or second stage of the fuelling process as described in the examples of Fig. 2 and Fig. 3. The fuelling routine can beneficially increase the delivery of hydrogen gas and to fuel more receiving vessels from the fuel gas storage unit whilst using the same quantity of gas.

[0265] The fuelling routine is particularly useful for on-site applications where hydrogen gas storage units are typically mobile and relatively small.

[0266] The controller may determine a fuelling routine based on the duty cycle and expected hydrogen gas consumption of the receiving vessels to determine a required fill level of the receiving vessels. In many situations, the receiving vessel may not need to be completely filled with hydrogen gas to perform their desired operations. By only partially filling at least some of the receiving vessels, the storage pressure of those receiving vessels is reduced. Moreover, the fuelling routine may prioritise filling receiving vessels that require high pressure hydrogen gas prior to filling receiving vessels that require lower pressure hydrogen gas. In this way, the pressure cascade filling process is able to fill a greater number of receiving vessels using the same volume of hydrogen gas.

[0267] The controller in determining the fuelling routine, receives a number of input data streams which are used by the controller to make decision around fuelling amounts and fuelling sequence.

[0268] The inputs include the expected duty cycle. This may be obtained from a user or through analysis of historic hydrogen gas consumption data for receiving vessels. The duty cycle relates to the demand profile for hydrogen gas throughout a day (or other time period). The duty cycle will differ depending on the refuelling application. For example, when refuelling a bus fleet, duty cycle will depend on the bus routes, fuel consumption, total run time, and when it is possible to refuel due to the bus schedules. For heavy goods vehicle fleets, the duty cycle will depend on the vehicle routes, fuel consumption, total run time, and access to refuelling stations along the routes. For non-road mobile machinery, the duty cycle will depend on the expected uptime, aggregate size and type, rate of mass processing required, and the opportunity for midday refuelling or next day refuelling. It will of course be appreciated that these parameters are in no way exhaustive and are given as examples only.

[0269] The inputs include hydrogen gas availability received from the fuel gas storage unit(s). Hydrogen gas availability may vary in real time as hydrogen gas is dispensed to vehicles so this input may be repeatedly updated.

[0270] The inputs include prioritisation data for receiving vessels based on pre-determined priority ranking or through calculated priority based on a cost function.

[0271] Other inputs may be provided such as the availability of refuelling supplies. In addition, data mining activities may be completed using Al and ML tools to identify refuelling and hydrogen gas consumption trends to support optimised operation. The controller schedules refuelling for receiving vessels to support maximum uptime and utilisation of available hydrogen gas using the input data streams.

[0272] The controller determines how much hydrogen gas is required for each receiving vessel. The controller determines when refuelling will be required for each receiving vessel.

[0273] The controller optimises the hydrogen gas fill percentage for each receiving vessel based on the duty requirements. That is, the controller determines the required amount of hydrogen gas to be delivered to each receiving vessel. The determination is based on a calculation of the expected fuel gas consumption for the each of the receiving vessels over a period of time.

[0274] By way of example, there may be a number of vehicles at a construction site requiring hydrogen gas. The controller may determine that expected amount of hydrogen gas required by each of the vehicles for a given day on the construction site and may thus determine the required fill percentage for each of the vehicles. Some of the vehicles may only be used intermittently during the day and thus may have a hydrogen gas fill percentage of less than 100%.

[0275] The controller also determines an order for fuelling the plurality of receiving vessels. The order is determined based on the determined fuel gas storage pressure for each of the plurality of receiving vessels. The determined order prioritises filling receiving vessels requiring higher fuel gas storage pressures first. The determined order specifies fuelling the receiving vessels in order of decreasing fuel gas storage pressure.

[0276] Prioritising fuelling high pressure receiving vessels first helps ensure that these receiving vessels can be sufficiently refuelled. If these receiving vessels are fuelled later in the process (such as after lower pressure receiving vessels), then they hydrogen gas pressure in the fuel gas storage unit may be insufficient to reach the required storage pressure for the receiving vessel.

[0277] The controller may also adjust this order based on operability factors such as availability of assets for refuelling, continuity of critical operations, asset prioritisation amongst others. The optimisation may therefore be constrained by real-world factors, and it may not be possible or desirable to fuelling vessels strictly based on fuel gas storage pressure.

[0278] The controller may then optionally monitor fuel gas consumption relative to forecast and adjust refuelling schedule for this instance, or for future instances accordingly.

[0279] The fuelling routine can be used in conjunction with the first stage of the fuelling process (pressure cascade) to enable higher hydrogen gas utilisation and to enable more receiving vessels to be fuelled from a single fuel gas storage unit. The fuelling routine can be used in conjunction with the second stage of the fuelling process (activation of fluid deliver means) to increase the hydrogen gas utilisation and enable more receiving vessels to be fuelled from a single fuel gas storage unit.

[0280] Figure 4 shows a control system 400 used to control and / or monitor the operation of fuelling system 110 according to aspects of the present disclosure. In the Figure, solid lines indicate control signals and dashed lines indicate feedback and / or sensor signals.

[0281] The control system 400 typically comprises a master system controller 402 (“controller”) which is typically implemented by one or more suitable programmed or configured hardware, firmware and / or software controllers, e.g., comprising one or more suitable programmed or configured microprocessor, microcontroller or other processor, for example an IC processor such as an ASIC, DSP or FPGA (not illustrated). The controllers may be distributed and some or more of the operations may be performed remotely such as using web-hosted applications.

[0282] In preferred examples, the control system 400 communicates control information to other components of the system such as valves, operating fluid delivery means 236 and coolant fluid delivery means 424. Process settings may be received via a process setting interface unit 404. The process settings may specify environmental conditions, for example in relation to temperature(s), flow rate(s), and / or pressure(s). Information about the receiving vessels may be receiving via a database 422 storing receiving vessel specification information. The receiving vessel specification information may include one or more of the list of vehicles / assets, the storage volume of each vessel / asset, the maximum storage pressure of each vessel / asset, the minimum storage pressure of each vessel / asset, the refuelling constraints in terms of time and / or maximum temperature, the duty cycle, the refuelling time window, and the criticality of the equipment.

[0283] In the example shown in Figure 4, a gas flow control module 406 generates control signals for controlling the gas flow rate, a temperate control module 408 generates control signals for controlling the temperature, a pressure control module 410 generates control signals for controlling the pressure. The control signals are supplied to a control and actuation loom 412 which routes the control signals to the desired components of the fuelling system.

[0284] The control system 400 may also receive feedback information from other components such as sensors (e.g. incorporated into the fuel gas storage unit 112), measurement devices (e.g. incorporated into the fuel gas storage unit 112), valves, and / or fluid delivery means 236, 424 in response to which the control system 400 may issue control information to one or more relevant components. The feedback information is received via a feedback and sensor loom 414 in this example.

[0285] The control system 400 may perform analysis of the measurements or other information provided. This analysis may be carried out automatically in real time by the control system 400. Alternatively, or in addition, analysis of the system measurements and performance may be made by an operator in real time or offline. The operator may make adjustments to the operation of the system by providing control instructions via the process settings interface 404.

[0286] A safety control module 416 may be provided, which may receive alarm signals from one or more alarm sensors (not shown), e.g., gas sensors, temperature sensors, leak detectors or emergency stops that may be included in the fuelling system 1 10. The safety control module 416 provides alarm information to the master controller 402 based on the alarm signals received from the alarm sensors. The safety control module 416 may also control an alarm and shutdown module 418 to generate an alarm for the operator and / or shutdown the operation of the fuelling system 110.

[0287] In preferred examples, the control system 400, and more particularly the master controller 802 is configured to implement system modelling logic, e.g.., by supporting mathematical modelling software or firmware 420, for enabling the control system 400 to mathematically model the behaviour of the fuelling system 110, depending on the process settings and / or on feedback signals received from one or more system components during operation of the fuelling system 1 10.

[0288] Optionally, the control system 400 is configured to implement Model Predictive Control (MPC). Using MPC, the control system 400 causes the control action of the control modules 406, 408, 410, 416 to be adjusted before a corresponding deviation from a relevant process set point actually occurs. This predictive ability, when combined with traditional feedback operation, enables the control system 400 to make adjustments that are smoother and closer to the optimal control action values that would otherwise be obtained. A control model can be written in Matlab, Simulink, or Labview by way of example and executed by the master controller 402. Advantageously, MPC can handle MIMO (Multiple Inputs, Multiple Outputs) systems.

[0289] The coolant fluid delivery means 424 can be used to deliver a coolant fluid to the fuel gas storage unit. Example implementations of coolant fluid delivery means are described in UK Patent Application Publication No. 2613202 A the disclosures of which are herein incorporated by reference.

[0290] Figure 5 shows an example method of fuelling according to aspects of the present disclosure. Step 502 of the method comprises performing a first operation in which a plurality of storage vessels of a fuel gas storage unit are sequentially fluidly connected to at least one receiving vessels to as to deliver hydrogen gas from the vessels to the at least one receiving vessel. Step 504 comprises performing a second operation in which a compressor is activated to increase the pressure of the hydrogen gas.

[0291] Figure 6 shows an example method of fuelling according to aspects of the present disclosure. Step 602 comprises determining an amount of hydrogen gas to be delivered to a plurality of receiving vessels based on a calculation of the expected hydrogen gas consumption for each of the plurality of receiving vessels over a period of time. Step 604 comprises determining an order for fuelling the plurality of receiving vessels based on a hydrogen gas storage pressure for each of the plurality of receiving vessels. Step 606 comprises delivering, for each of the receiving vessels, hydrogen gas to the receiving vessel such that the receiving vessel receives their determined amount of hydrogen gas. The hydrogen gas is delivered to the plurality of receiving vessels according to the determined order for fuelling.

[0292] Figure 7 shows a variation of the fuel delivery system 110 of Figure 3. The fuel delivery system 110 comprises the first fuel gas storage unit 112 and second fuel gas storage unit 302 as described above in relation to Figure 3. Operating fluid is delivered to the second fuel gas storage unit 302 via the fluid delivery means 236 and fluid reservoir 238 as explained above in relation to Figure 3. A detailed explanation is omitted as it can be found above in relation to Figure 3.

[0293] In the example of Figure 7, the pipework 218 comprises two fuel gas circuits.

[0294] A first of the circuits comprises pipework 702 that flows from a first set of gas outlets 210, 212, 214, 216 of the first fuel gas storage unit 1 12 to the compressor 114 and on to the at least one receiving vessel A. For the first circuit, a valve 704 selectively fluidly connects / disconnects the gas flow from the at least one receiving vessel A.

[0295] A second of the circuits comprises pipework 706 that flows from a second set of gas outlets 708, 710, 712, 714 of the first fuel gas storage unit 112 to the at least one receiving vessel A. The second circuit bypasses the compressor 114. A valve 716 selectively fluidly connects / disconnects the gas flow from the at least one receiving vessel A.

[0296] In the example of Figure 7, hydrogen gas can flow concurrently via the first circuit and the second circuit. In this way, hydrogen gas can be dispensed from the first fuel gas storage unit 112 to the at least one receiving vessel A via pressure cascading using the second circuit. At the same time, hydrogen gas can be delivered from the first fuel gas storage unit 112 to the compressor 114 via the first circuit for compression prior to transfer to the receiving vessel A or return to the first fuel gas storage unit 112 as explained above in reference to Figure 3. At any one time, some of the storage vessels of the first fuel gas storage unit 112 may be fluidly connected to the first circuit while other storage vessels of the first fuel gas storage unit are fluidly connected to the second circuit.

[0297] The operation of the valves 220, 222, 224, 226 (Figure 2) coupled to the first set of fluid gas outlets 210, 212, 214, 216 and the valves 718, 720, 722, 724 coupled to the second set of fluid gas outlets 708, 710, 712, 714 determine which of circuits the storage vessels of the first fuel gas storage unit 112 are fluidly connected to. Depending on the operation of the valves, some of the vessels of the first fuel gas storage unit 1 12 may be fluidly connected to the second circuit for fuel dispensing via pressure cascade while other vessels of the first fuel gas storage unit 112 are fluidly connected to the first circuit to allow for fuel gas to compressed via compressor 1 14. The controller (not shown) controls the operation of the valves and can change the state of individual valves and groups of valves over time such that the vessels can vary between being fluidly connected to the first circuit and the second circuit.

[0298] Comparative Examples

[0299] In the following examples a fuel gas storage unit comprising four storage vessels was used. The fuel gas storage unit has 200 kg capacity and has a pressure of 500 bar when full. Of the 200 kg capacity, 193 kg of hydrogen gas is available for fully filling thirteen receiving vessels (vehicle tanks). The receiving vessels each have 16.5 kg capacity and have a pressure of 350 bar when full. 14.8 kg of hydrogen gas is required to fill the receiving vessel from a minimum pressure of 30 bar.

[0300] In Example 1 , the first operation mode (pressure cascading) is used only.

[0301] In Example 2, the first operation mode (pressure cascading) and second operation mode (compression) are used.

[0302] In Example 3, the first operation mode (pressure cascading) is used in combination with the fuelling routine as described above. The fuelling routine optimises the hydrogen gas fill percentage for each receiving vessel based on the duty requirements and optimises the order of the refuelling process based on factors such as the required pressure of each of the receiving vessels.

[0303] In Example 4, the first operation mode (pressure cascading) and second operation mode (compression) are used in combination with the fuelling routine.

[0304] The below table outlines the results of fuelling receiving vessels using Examples 1 , 2, 3 and 4. The energy required per kg delivered to application assumes a 200 mile round trip from the hydrogen gas production site to the fuelling site and includes transportation, compression at the depot (where the fuel gas storage unit is filled up), and compression at the fuelling site.

[0305] Examples 2 and 4 achieve the highest percentage of delivery of hydrogen gas from the fuel gas storage unit to the receiving vessels. The second operation mode therefore enables higher fuel utilisation.

[0306] Examples 3 and 4 achieve the highest number of useable receiving vessel (vehicle fills). Notably, the fuelling routine determines a required amount of hydrogen gas to be delivered to each receiving vessel. This means that the receiving vessels are not required to be filled completely and are instead filled based on an estimation of the amount of hydrogen gas required by the receiving vessel. This allows more receiving vessels to be filled. Examples 2, 3 and 4 require more compression energy but require less energy per kg of hydrogen gas delivered to the receiving vessels. Examples 2, 3, and 4 are therefore more energy efficient per kg of hydrogen gas delivered and have a lower cost per kg delivered.

[0307] All of Examples 2, 3, and 4 achieve benefits over the use of pressure cascading alone as per Example 1.

[0308] The above examples demonstrate that the second operation mode achieves greater percentage of fuel gas delivery, greater number of useable vehicle fills, and reduced energy costs compared to pressure cascading alone.

[0309] The above examples demonstrate that the fuelling routine achieves greater percentage of fuel gas delivery, greater number of useable vehicle fills, and reduced energy costs compared to pressure cascading alone.

[0310] The above examples demonstrate that the combination of the first operation mode, the second operation mode, and the fuelling routine provide the best performance in terms of fuel gas delivery, useable vehicle fills, and energy costs.

[0311] At least some of the example embodiments described herein may be constructed, partially or wholly, using dedicated special-purpose hardware. Terms such as ‘component,’ ‘module’ or ‘unit’ used herein may include, but are not limited to, a hardware device, such as circuitry in the form of discrete or integrated components, a Field Programmable Gate Array (FPGA) or Application Specific Integrated Circuit (ASIC), which performs certain tasks or provides the associated functionality. In some embodiments, the described elements may be configured to reside on a tangible, persistent, addressable storage medium and may be configured to execute on one or more processors. These functional elements may in some embodiments include, by way of example, components, such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. Although the example embodiments have been described with reference to the components, modules and units discussed herein, such functional elements may be combined into fewer elements or separated into additional elements.

[0312] Various combinations of optional features have been described herein, and it will be appreciated that described features may be combined in any suitable combination. In particular, the features of any one example embodiment may be combined with features of any other embodiment, as appropriate, except where such combinations are mutually exclusive. Throughout this specification, the term “comprising” or “comprises” means including the component(s) specified but not to the exclusion of the presence of others.

[0313] All of the features disclosed in this specification (including any accompanying claims, abstract 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 least some of such features and / or steps are mutually exclusive.

[0314] Each feature disclosed in this specification (including any accompanying claims, abstract 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.

[0315] 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, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

CLAIMS1 . A system for fuelling comprising: a fuel gas storage unit comprising a plurality of storage vessels for storing fuel gas, each storage vessel of the plurality of storage vessels being selectively fluidly connectable to at least one receiving vessel; a compressor for increasing the pressure of the fuel gas; a controller configured to, in a first operation, sequentially fluidly connect the plurality of storage vessels to the at least one receiving vessel, and, in a second operation, activate the compressor to increase the pressure of the fuel gas.

2. A system as claimed in claim 1 , wherein the controller is configured to perform the second operation after the first operation.

3. A system as claimed in claim 1 or 2, wherein the controller is configured to transition from the first operation to the second operation in response to detecting a trigger condition.

4. A system as claimed in claim 3, wherein the trigger condition comprises the flow rate of fuel gas from one or more of the storage vessels falling below a threshold value.

5. A system as claimed in claim 3 or 4, wherein the trigger condition comprises the pressure in one or more of the plurality of storage vessels falling below a threshold value.

6. A system as claimed in any preceding claim, wherein the compressor comprises an operating fluid delivery means arranged to deliver an operating fluid such that the operating fluid is brought into contact with the fuel gas to increase the pressure of the fuel gas.

7. A system as claimed in claim 6, wherein the operating fluid delivery means is arranged to deliver the operating fluid to the fuel gas storage unit to increase the pressure of fuel gas contained within one or more of the storage vessels of the fuel gas storage unit.

8. A system as claimed in claim 6, wherein the fuel gas storage unit is a first fuel gas storage unit wherein the compressor comprises a second fuel gas storage unit for storing fuel gas, the second fuel gas storage unit being fluidly connectable to the first fuel gas storage unit, and wherein the operating fluid delivery means is arranged to deliver the operating fluid to the second fuel gas storage unit to increase the pressure of fuel gas contained within the second fuel gas storage unit.

9. A system as claimed in claim 8, wherein the second fuel gas storage unit is arranged to receive fuel gas from at least one storage vessel of the first fuel gas storage unit.

10. A system as claimed in claim 9, wherein the operating fluid delivery means is arranged to deliver the operating fluid to the second fuel gas storage unit to increase the pressure of the fuel gas received from the at least one storage vessel of the first fuel gas storage unit.

11. A system as claimed in any of claims 8 to 10, wherein the second fuel gas storage unit is arranged to deliver fuel gas to the at least one receiving vessel.

12. A system as claimed in any of claims 8 to 11 , wherein the second fuel gas storage unit is arranged to deliver fuel gas to at least one storage vessel of the first fuel gas storage unit.

13. A system as claimed in claim 12, wherein the second fuel gas storage unit is arranged to receive fuel gas from a first storage vessel of the first fuel gas storage unit, the operating fluid delivery means is arranged to deliver the operating fluid to the second fuel gas storage unit to increase the pressure of the fuel gas received from the first storage vessel of the first fuel gas storage unit, and wherein the second fuel gas storage unit is arranged to deliver the fuel gas to a second storage vessel of the first fuel gas storage unit.

14. A system as claimed in any preceding claim, wherein the fuel gas comprises hydrogen gas.

15. A system as claimed in any preceding claim, wherein the controller is operable to determine a required amount of fuel gas to be delivered to the at least one receiving vessel, and wherein the controller is operable to, in the first operation and / or second operation, deliver the required amount of fuel gas to the at least one receiving vessel.

16. A system as claimed in claim 15, wherein the controller is operable to determine the required amount of fuel gas to be delivered to the at least one receiving vessel based on a calculation of the expected fuel gas consumption for the at least one receiving vessel over a period of time.

17. A system as claimed in any preceding claim, wherein the at least one receiving vessel comprises a plurality of receiving vessels.

18. A system as claimed in claim 17, wherein the controller is operable to determine a required amount of fuel gas to be delivered to each of the plurality of receiving vessels.

19. A system as claimed in claim 17 or 18, wherein the controller is operable to determine an order for fuelling the plurality of receiving vessels.

20. A system as claimed in claim 19, wherein the controller is operable to determine the order for fuelling the plurality of receiving vessels based on a determined fuel gas storage pressure for each of the plurality of receiving vessels.

21. A system as claimed in claim 20, wherein the determined order prioritises receiving vessels having higher fuel gas storage pressures over receiving vessels having lower fuel gas storage pressures.

22. A system as claimed in claim 21 , wherein the determined order specifies fuelling the receiving vessels in order of decreasing fuel gas storage pressure.

23. A system as claimed in any of claims 19 to 22, wherein the controller is operable to fuel the receiving vessels according to the determined order.

24. A method of fuelling comprising: in a first operation, sequentially fluidly connecting a plurality of storage vessels of a fuel gas storage unit to at least one receiving vessels to as to deliver fuel gas from the vessels to the at least one receiving vessel; and in a second operation, activating a compressor to increase the pressure of the fuel gas.

25. A method of fuelling comprising: determining an amount of fuel gas to be delivered to a plurality of receiving vessels based on a calculation of the expected fuel gas consumption for each of the plurality of receiving vessels over a period of time; determining an order for fuelling the plurality of receiving vessels based on a fuel gas storage pressure for each of the plurality of receiving vessels; and delivering, for each of the receiving vessels, fuel gas to the receiving vessel such that the receiving vessel receives their determined amount of fuel gas, wherein the fuel gas is delivered to the plurality of receiving vessels according to the determined order for fuelling.

26. A gas transfer system comprising: a gas storage unit comprising a plurality of storage vessels for storing gas, each storage vessel of the plurality of storage vessels being selectively fluidly connectable to at least one receiving vessel; a compressor for increasing the pressure of the gas; a controller configured to, in a first operation, sequentially fluidly connect the plurality of storage vessels to the at least one receiving vessel, and, in a second operation, activate the compressor to increase the pressure of the gas.

27. A gas transfer system as claimed in claim 26, wherein the controller is configured to perform the second operation after the first operation.

28. A gas transfer system as claimed in claim 26 or claim 27, wherein the controller is configured to transition from the first operation to the second operation in response to detecting a trigger condition.

29. A gas transfer system as claimed in claim 28, wherein the trigger condition comprises the flow rate of gas from one or more of the storage vessels falling below a threshold value.

30. A gas transfer system as claimed in claim 28 or 29, wherein the trigger condition comprises the pressure in one or more of the plurality of storage vessels falling below a threshold value.

31. A gas transfer system as claimed in any one of claims 26 to 30, wherein the compressor comprises an operating fluid delivery means arranged to deliver an operating fluid such that the operating fluid is brought into contact with the gas to increase the pressure of the gas.

32. A gas transfer system as claimed in claim 31 , wherein the operating fluid delivery means is arranged to deliver the operating fluid to the gas storage unit to increase the pressure of gas contained within one or more of the storage vessels of the gas storage unit.

33. A gas transfer system as claimed in claim 31 , wherein the gas storage unit is a first gas storage unit wherein the compressor comprises a second gas storage unit for storing gas, the second gas storage unit being fluidly connectable to the first gas storage unit, and wherein the operating fluid delivery means is arranged to deliver the operating fluid to the second gas storage unit to increase the pressure of gas contained within the second gas storage unit.

34. A gas transfer system as claimed in claim 33, wherein the second gas storage unit is arranged to receive gas from at least one storage vessel of the first gas storage unit.

35. A gas transfer system as claimed in claim 34, wherein the operating fluid delivery means is arranged to deliver the operating fluid to the second gas storage unit to increase the pressure of the gas received from the at least one storage vessel of the first gas storage unit.

36. A gas transfer system as claimed in any of claims 33 to 35, wherein the second gas storage unit is arranged to deliver gas to the at least one receiving vessel.

37. A gas transfer system as claimed in any of claims 33 to 36, wherein the second gas storage unit is arranged to deliver gas to at least one storage vessel of the first gas storage unit.

38. A gas transfer system as claimed in claim 37, wherein the second gas storage unit is arranged to receive gas from a first storage vessel of the first gas storage unit, the operating fluid delivery means is arranged to deliver the operating fluid to the second gas storage unit to increase the pressure of the gas received from the first storage vessel of the first gas storage unit, andwherein the second gas storage unit is arranged to deliver the gas to a second storage vessel of the first fuel gas storage unit.

39. A gas transfer system as claimed in any one of claims 26 to 38, wherein the gas comprises a fuel gas.

40. A gas transfer system as claimed in any one of claims 26 to 39, wherein the at least one receiving vessel comprises a receiving vessel configured for transportation of gas for subsequent use by an end consumer or a receiving vessel configured to store gas for subsequent use by an end consumer.

41. A gas production and delivery system for delivery of gas to an end consumer, the gas production and delivery system comprising one or more gas transfer systems according to any one of claims 26 to 39.

42. A gas production and delivery system as claimed in claim 41 , wherein one of the one or more gas transfer systems is arranged to transfer gas to at least one receiving vessel configured for transportation of gas for subsequent use by an end consumer.

43. A gas production and delivery system as claimed in claim 41 or claim 42, wherein one of the one or more gas transfer systems is arranged to transfer gas to at least one receiving vessel configured to store gas for subsequent use by an end consumer.

44. A gas production and delivery system as claimed in claim 43, wherein the gas stored in the at least one receiving vessel configured to store gas for subsequent use by an end consumer is fuel gas.

45. A method of transferring gas comprising: in a first operation, sequentially fluidly connecting a plurality of storage vessels of a gas storage unit to at least one receiving vessel so as to deliver gas from the vessels to the at least one receiving vessel; and in a second operation, activating a compressor to increase the pressure of the gas.

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