Systems and methods for refueling and backup power generation

Abstract

A system and method are provided for such a hydrogen refueling station. The system includes a cryotank for storing liquid fuel having liquid and gas phases, a pump for supplying a first flow of the liquid fuel in liquid phase from the cryotank, a heat exchanger for converting at least a portion of the first flow to gaseous fuel, a dispenser for dispensing at least a portion of the gaseous fuel to a receiving fuel tank, a refrigeration unit integrated with the heat exchanger, and a backup power unit. The refrigeration unit and the heat exchanger exchange heat with each other, and the refrigeration unit provides cooling capacity to equipment in an environment where cooling is required. The backup power unit generates electrical power by using a second flow of the liquid fuel in the gaseous or liquid phase or both.

Description

Detailed Description of the Invention

[0001] [Technical Field] The present disclosure relates generally to methods and systems for storing, transporting, or dispensing liquid fuels or pressurized gases. More particularly, the disclosed subject matter relates to systems or refueling stations and methods for storing and refueling hydrogen.

[0002] [Background technology] Many automobiles are currently powered by internal combustion engines with fossil fuels. Due to limited supply and the negative environmental impacts associated with burning petroleum-derived fuels, vehicles powered by alternative, environmentally friendly fuels, such as hydrogen, are currently being developed. Fuel cells can be used to generate electrical power for automobiles by electrochemically reacting hydrogen fuel with an oxidizer, such as air. Other hydrogen-powered vehicles can be powered by the combustion of hydrogen. Fueling or refueling fuel cell vehicles (FCVs) and other hydrogen-powered vehicles with hydrogen presents different challenges than adding petroleum-based fuels, such as gasoline, to vehicles.

[0003] Summary of the Invention The present disclosure provides a system and method for refueling while also providing backup power and cooling capacity. For example, the system is a hydrogen refueling station.

[0004] According to some embodiments, such a system includes a cryotank configured to store liquid fuel therein, the liquid fuel having a liquid phase and a gas phase; a pump fluidly connected to the cryotank and configured to provide or pump a first flow of liquid fuel in the liquid phase from the cryotank; a heat exchanger; and a dispenser. The heat exchanger is connected to the pump and configured to convert at least a portion of the first flow of liquid fuel in the liquid phase into gaseous fuel. The dispenser is configured to distribute at least a portion of the gaseous fuel to a receiving fuel tank, for example, an on-board fuel tank in a vehicle. The system further includes a refrigeration unit integrated with the heat exchanger and a backup power unit. The refrigeration unit is configured to provide a heat load to the heat exchanger, and the heat exchanger is configured to provide a cooling load to the refrigeration unit. The refrigeration unit is configured to provide cooling capacity to equipment or an environment requiring cooling. The backup power unit is configured to receive a second flow of liquid fuel in the gaseous and / or liquid phase from the cryotank and generate electrical power.

[0005] In some embodiments, the liquid fuel comprises hydrogen. The system is a hydrogen refueling station. The pump is an immersible liquid pump disposed within the cryotank and configured to compress a first flow of the liquid fuel in a liquid phase.

[0006] In some embodiments, the system further includes a splitter, which can be disposed between the pump and the heat exchanger. The splitter is configured to divide the first flow of liquid fuel into a first portion and a second portion. The heat exchanger is configured to convert the first portion to a gaseous fuel. The system also includes a mixer configured to combine the gaseous fuel and the second portion to form a compressed gaseous fuel to be distributed. In some embodiments, the gaseous fuel or fuel to be distributed is compressed hydrogen having a pressure ranging from 25 MPa to 90 MPa and a temperature ranging from -50°C to ambient temperature.

[0007] In some embodiments, the backup power unit is configured to receive less than 30% by weight of the total storage capacity of the liquid fuel in the cryotank on any one day that backup power is needed. The backup power unit is configured to provide power to the data center, and the refrigeration unit is configured to provide cooling capacity to the data center.

[0008] In some embodiments, the backup power unit comprises one or more fuel cells or combustion engines for generating electrical power from a second stream of liquid fuel, either in a gas phase (also referred to as boil-off fuel) or a liquid phase, or both. The backup power unit may also be configured to further receive at least a portion of the gaseous fuel from a heat exchanger to generate electrical power. The internal combustion engine generates electrical power using a thermal cycle. Suitable examples of combustion engines include, but are not limited to, a reciprocating engine, a gas turbine, or a microturbine.

[0009] In some embodiments, the system further comprises a liquefier fluidly connected to the cryotank. The production unit may be fluidly connected to the liquefier. The liquefier compresses gas produced in the production unit into liquid fuel. The production unit comprises at least one electrolyzer for producing hydrogen gas from water. The at least one electrolyzer or the liquefier, or both, may be configured to be at least partially powered by solar or wind power. Instead of a production unit, the liquefier or cryotank may be integrated with a liquid hydrogen distribution network, and liquid hydrogen is transported from the storage vessel to a refueling station or a point of use, such as for industrial production (e.g., steel production).

[0010] In another aspect, the present disclosure also provides a method for refueling while also providing backup power and cooling capacity. The method includes: supplying liquid fuel having liquid and gas phases stored inside a cryotank; pumping a first flow of the liquid fuel in the liquid phase from the cryotank through a pump fluidly connected to the cryotank; converting at least a portion of the first flow of the liquid fuel in the liquid phase to gaseous fuel through a heat exchanger connected to the pump; and distributing at least a portion of the gaseous fuel to a receiving fuel tank. The method further includes providing cooling capacity from a refrigeration unit integrated with the heat exchanger to equipment requiring cooling; and generating electrical power using a backup power unit using a second flow of the liquid fuel in the gaseous and / or liquid phases from the cryotank.

[0011] In some embodiments, the liquid fuel includes or is hydrogen. A first flow of the liquid fuel in a liquid phase is pumped from the cryotank by compressing the liquid fuel using an immersible liquid pump disposed inside the cryotank. The method can further include supplying a heat load from the refrigeration unit to a heat exchanger and supplying a cooling load from the heat exchanger to the refrigeration unit.

[0012] In some embodiments, the method further includes splitting the first flow of liquid fuel into a first portion and a second portion. The first portion passes through a heat exchanger. The method further includes combining the gaseous fuel with the second portion to form a compressed gaseous fuel that is dispensed.

[0013] In some embodiments, less than 30% by weight of the total liquid fuel storage capacity in the cryotank is supplied to the backup power unit on any one day when backup power is needed. The power generated by the backup power unit is supplied to a facility such as a data center from the backup power unit, and the cooling capacity from the refrigeration unit is used to cool the facility such as a data center. The backup power supply is provided intermittently. The cooling load can be supplied periodically daily.

[0014] In some embodiments, the power is generated via one or more fuel cells or combustion engines in the backup power unit. The method can further include supplying at least a portion of the gaseous fuel from the heat exchanger to the backup power unit to generate the power.

[0015] In some embodiments, the liquid fuel in the cryotank is supplied from a liquefier fluidly connected to the cryotank. The liquefier compresses gas produced in the production unit into liquid fuel. For example, the production unit includes at least one electrolyzer for producing hydrogen gas from water. In some embodiments, the at least one electrolyzer and / or the liquefier are at least partially powered by solar or wind power.

[0016] The systems and methods provided in the present disclosure offer many advantages, as described herein. For example, in some embodiments, the present disclosure provides a hydrogen refueling station for refueling vehicles while also providing backup power and cooling capacity for, for example, a data center. Compared to standalone storage options, the systems in the present disclosure significantly reduce losses from hydrogen boil-off used to generate backup power for the data center. Excess cooling load from the heat exchanger or vaporizer is efficiently and productively utilized. The system provides much higher cooling capacity, while the heat exchanger is used much more effectively when integrated with a refrigeration unit.

[0017] The present disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not necessarily to scale. On the contrary, dimensions of various structures have been arbitrarily increased or decreased for clarity. Like reference numerals refer to like features throughout the specification and drawings.

[0018] BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram illustrating a first exemplary system, such as a hydrogen refueling station, with a backup generator and a refrigeration unit, according to some embodiments.

[0019] FIG. 2 is a block diagram illustrating a second exemplary system, such as a hydrogen refueling station, including a backup generator for providing backup power to a data center and a refrigeration unit for providing cooling loads to the data center, according to some embodiments.

[0020] FIG. 3 is a block diagram illustrating a third exemplary system, such as a hydrogen refueling station, including a backup generator for providing backup power to a data center, a refrigeration unit for providing cooling loads to the data center, a hydrogen production unit, and a liquefaction device, according to some embodiments.

[0021] FIG. 4A is a flowchart illustrating an exemplary method that includes distributing a liquid fuel, such as hydrogen, providing backup power, and providing a cooling load, according to some embodiments.

[0022] FIG. 4B is a flow chart illustrating some steps that may be included in the exemplary method of FIG. 4A. [Mode for Carrying Out the Invention]

[0023] This description of exemplary embodiments is intended to be read in conjunction with the accompanying drawings, which are to be considered part of the entire written description. As used herein, relative terms such as "lower," "upper," "horizontal," "vertical," "above," "below," "up," "down," "top," and "bottom," as well as derivatives thereof (e.g., "horizontally," "downwardly," "upwardly," etc.), should be construed to refer to the orientation as then described or as shown in the drawings under discussion. These relative terms are for convenience of description and do not require that the devices be constructed or operated in a particular orientation. Terms relating to attachments, couplings, and the like, such as "connected" and "interconnected," unless expressly stated otherwise, refer to a relationship in which structures are fixed or attached to one another, both directly or indirectly through intervening structures, and through any movable or rigid attachment or relationship.

[0024] For purposes of the following description, it is to be understood that the embodiments described below may assume alternative variations and embodiments, and that the specific articles, compositions, and / or processes described herein are exemplary and should not be considered limiting.

[0025] In this disclosure, the singular forms "a," "an," and "the" include plural references, and reference to a specific numerical value includes at least that particular value unless the context clearly dictates otherwise. When values ​​are expressed as approximations by use of the antecedent "about," it is understood that the particular value forms another embodiment. As used herein, "about X" (where X is a numerical value) preferably refers to ±10% of the recited value. For example, the phrase "about 8" preferably refers to a value between 7.2 and 8.8, inclusive. Where present, all temperature ranges are inclusive and combinable. For example, if a temperature range of "1 to 5" is provided, the temperature range should be interpreted as including ranges such as "1 to 4," "1 to 3," "1 to 2," "1 to 2 and 4 to 5," "1 to 3 and 5," "2 to 5," etc. Additionally, when a list of options is provided in the affirmative, such list may be interpreted to mean that any of the options may be excluded, for example, by a negative limitation in the claims. For example, if a range of "1 to 5" is recited, the recited range may be interpreted to include situations in which any of 1, 2, 3, 4, or 5 is negatively excluded; thus, a recitation of "1 to 5" may be interpreted as "1 and 3 through 5, but not including 2," or simply as "not including 2." It is intended that any component, element, attribute, or step that is positively recited herein may be explicitly excluded in the claims, regardless of whether such component, element, attribute, or step is listed as an alternative or whether it is described alone.

[0026] Unless otherwise specified, the term "substantially" as used herein, such as "substantially the same," is understood to encompass parameters with an appropriate range of variation, for example, a variation of ±10% or ±15% of the parameter. In some embodiments, the range of variation is within ±10%.

[0027] The systems and methods described herein may be applicable to direct-fill refueling of liquid fuels, such as hydrogen. Unless otherwise specified, references made herein to “direct-fill” (or “direct”) are understood to refer to a continuous operation of the fuel supply or refueling process from a fueling station storage tank to a vehicle storage tank. For example, in a direct-fill system or process, liquid hydrogen may be removed from a storage tank, vaporized, and dispensed directly into a receiving tank on the vehicle. The gaseous hydrogen from the liquid state continuously flows into the receiving tank. The hydrogen is stored in the receiving tank on the vehicle in compressed gas form. The terms “direct fill” and “direct” are used interchangeably with respect to the fuel supply or refueling process. Existing technology includes intermediate cascade storage steps in which compressed gaseous hydrogen is stored after evaporation but before distribution to the vehicle's receiving tank.

[0028] Unless otherwise specified, liquid fuel, such as hydrogen, is stored in a storage tank and pumped in liquid form using a pump. The liquid fuel is vaporized in a heat exchanger to form gaseous fuel. The fuel between the pump and the heat exchanger may be in a supercritical state. At least a portion of the gaseous fuel is dispensed into a receiving tank within the vehicle. In this disclosure, the terms "fueling" and "refueling" are used interchangeably.

[0029] As used herein, when an element or component is described as being "connected to," "coupled to," "coupled with," or "in contact with" another element or component, it may be directly connected to, directly coupled to, or in direct contact with the particular element or component, or intervening elements or components may be connected to, coupled to, or in contact with the particular element or component. When an element or component is referred to as being "directly connected to," "directly coupled to," "directly coupled with," or "in direct contact with" another element, there are no intervening elements or components present.

[0030] As used herein, the term "thermally connected to" or "thermally connected with" should be understood to mean that components are connected directly or through intervening components, and that the components may be in direct contact with each other or that the intervening components may be in contact with the components, such that heat can be transferred between the components. As used herein, the term "fluidly connected to" or "fluidly connected with" should be understood to mean that a component is connected with a pipe or line and configured to have a flow of gas or liquid through the component. As used herein, the term "electronically connected" or "electrically connected" should be understood to encompass an electrical connection using a wired or wireless connection.

[0031] The term "ambient temperature" as used herein is understood as the temperature of ambient conditions, for example room temperature of 20-22°C.

[0032] U.S. Patent No. 6,753,105 discloses a fuel cell system including a reservoir for a cryogenic medium, such as liquid hydrogen, for supplying fuel; a fuel cell unit including at least one fuel cell connected to receive fuel from the reservoir; a cooling circuit for cooling the fuel cell unit; and a heating circuit including at least one first heat exchanger for heating the cryogenic medium provided from the reservoir to the fuel cell unit. Waste heat from the fuel cell is used to provide energy to the heat exchanger to vaporize the cryogenic medium. This system is suitable for mobile applications, where the size and weight of the system are reduced by integrating the fuel cell waste heat with the heat exchanger.

[0033] U.S. Patent Application Publication No. 2020 / 0158288 discloses a system and method for dispensing liquefied gases, such as hydrogen and natural gas, as fuel. A heat exchanger within the system uses only the fuel itself without external cooling to manage the final dispense temperature, and the fueling station does not include a storage subsystem located between the pump and the dispenser. The heat exchanger can be a vaporizer, using steam, gas, ambient air, or other heating source to heat the liquid fuel, or an electric heater.

[0034] In these heat exchangers used in existing fuel cell systems or refueling stations, the heat exchangers either do not provide the cooling load or the cooling load is lost to the environment and wasted.

[0035] Existing technologies for supporting data center power demands are primarily diesel generators, batteries for backup power, and electricity from the grid for primary power. While hydrogen and fuel cells have been discussed for data center applications, such applications face significant technical and economic challenges. See Technical Report No. NREL / TP-5400-75355, "Hydrogen and Fuel Cells for Data Center Applications Project Meeting: Workshop Report," by G. Saur et al., National Renewable Energy Laboratory, Golden, CO (USA), 2019. For example, significant amounts of hydrogen storage would be required. Development of a large-scale hydrogen infrastructure would be necessary. The underlying technical challenges and associated prohibitive costs are identified as barriers to the use of hydrogen fuel cells for data center applications.

[0036] In "A review of thermal management and innovative cooling strategies for data centers," by C. Nadjahi et al., in the journal "Sustainable Computing: Informatics and Systems," 2018, Vol. 19, pp. 14-28, different cooling options for data centers were evaluated. Promising cooling technologies include natural cooling, liquid cooling, two-phase technology, and built-in envelope cooling. Typical systems use ambient air or absorption chillers to supply the cooling load. Maximum cooling capacity cannot go below -50°C. Liquid hydrogen is not used to cool data centers.

[0037] The present disclosure provides a system and method for refueling that also provides backup power and cooling capacity. For example, the system is a hydrogen refueling station. Both the backup power and cooling capacity are supplied to a site or facility that needs them, such as a data center. In such a system or station, no significant storage of liquid fuel, such as liquid hydrogen, is required. Liquid hydrogen can have a cooling capacity as low as -200°C.

[0038] Combining a liquid hydrogen refueling station (LHRS) with an operation requiring cooling and backup power (e.g., a data center) offers the advantage of productive use of excess cooling load from the LHRS, improves the effectiveness of the LH2 vaporization process against atmospheric heating, and provides an effective means of storing LH2 for long periods of time without the boil-off limitations associated with tanks dedicated to storing LH2 for backup power. The system and method also have other important advantages as described herein.

[0039] 1-3, like items are indicated by like reference numerals, and for brevity, the description of the structure given above with reference to the preceding figures will not be repeated. The method described in FIGS. 4A-4B will be described with reference to the exemplary structure described in FIGS. 1-3.

[0040] 1, an exemplary system 100 includes a cryotank 10, a pump 40, at least one heat exchanger 60, and at least one dispenser 72. The exemplary system also includes a refrigeration unit 90, and / or a backup power unit 110.

[0041] The cryotank 10 is configured to store a liquid fuel 12 therein. The cryotank 10 may be an insulated tank suitable for storing the liquid fuel 12, such as liquid hydrogen, at low temperatures and pressures. The liquid fuel 12 includes a liquid phase 14 and a gas phase 16 (boil-off fuel). In some embodiments, the liquid fuel 12 includes or is hydrogen. An exemplary system described herein is a hydrogen refueling station.

[0042] The pump 40 is fluidly connected to the cryotank 10 and configured to supply or pump a first flow 42 of liquid fuel in a liquid phase from the cryotank 10. In some embodiments, the pump 40 is an immersed liquid pump that is disposed inside the cryotank 10 and configured to compress the liquid fuel 12, increase its pressure, and pump the first flow 42 of liquid fuel in a liquid phase from the cryotank 10. In some embodiments, the first flow 42 is also in a supercritical state.

[0043] A heat exchanger 60, also referred to as a vaporizer, is connected to the pump 10 and configured to convert at least a portion of the first stream 42 of liquid fuel in a liquid phase into gaseous fuel 54. The gaseous fuel 54 may be a compressed gas at a desired pressure and temperature.

[0044] The dispenser 72 is configured to dispense at least a portion of the gaseous fuel 54 into a receiving fuel tank (not shown), for example, an on-board fuel tank within a vehicle.

[0045] The refrigeration unit 90 is configured to provide a heat load to the heat exchanger 60, and the heat exchanger 60 is configured to provide a cooling load to the refrigeration unit 90. The refrigeration unit 90 is configured to provide cooling capacity to a facility or environment where cooling is required. In some embodiments, the refrigeration unit may also include an accumulator 80. The cooling load generated by the heat exchanger 60 is used as a source of low temperature for the accumulator 80 of the refrigeration unit 90. The accumulator 80 then provides the heat load to the heat exchanger 60. The accumulator 80 for the heat load may include a liquid or solid medium.

[0046] The backup power unit 110 is configured to receive a second flow 46 of liquid fuel 12 in the vapor phase 16 and / or liquid phase 14 from the cryotank 10 and generate electrical power.

[0047] In some embodiments, the exemplary system 100 further includes a splitter 50, which can be disposed between the pump 40 and the heat exchanger 60. The splitter 50 is fluidly connected to the pump 40. The splitter 50 is configured to split the first flow of liquid fuel 42 into a first portion 51 and a second portion 52. The heat exchanger 60 is configured to convert the first portion 51 into a gaseous fuel 54 while the first portion 51 passes through the heat exchanger 60. The exemplary system 100 also includes a mixer 70 configured to combine the gaseous fuel 54 and the second portion 52 to form a distributed fuel. The distributed fuel can be a compressed gaseous fuel or a liquid fuel. In some embodiments, the distributed gaseous fuel or fuel is compressed hydrogen having a pressure ranging from 25 MPa to 90 MPa and a temperature ranging from −50° C. to ambient temperature.

[0048] In some embodiments, the backup power unit 110 comprises one or more fuel cells or combustion engines for generating electrical power from the second stream 46 of liquid fuel, either in the gas phase (also referred to as boil-off fuel) or liquid phase, or both. In some embodiments, the backup power unit 110 may also optionally be configured to further receive at least a portion of the gaseous fuel 54 passing through the heat exchanger 60 to generate electrical power. The internal combustion engine generates electrical power using a thermal cycle. Suitable examples of combustion engines include, but are not limited to, reciprocating engines, gas or microturbines, and hydrogen turbines.

[0049] As an example, exemplary system 100 is designed to integrate a liquid hydrogen refueling station (LHRS) having a capacity of one ton per day (tpd) with a refrigeration unit 90 and a backup power unit 110 (or subsystem).

[0050] The refrigeration unit 90 can operate continuously or discontinuously. The LHRS can, but need not, dispense standard H2. If the LHRS dispenses H2 discontinuously, the cooling load can be stored for subsequent use by the refrigeration unit 90. This can be accomplished, for example, by cooling the accumulator 80 through a liquid (or solid block) that is stored in an insulated tank until use. The accumulator 80 can be used as a cold sink by the refrigeration unit 90 regardless of the schedule on which the cooling load is delivered to the accumulator 80.

[0051] In FIG. 1, the dotted box surrounding the H2 stream (i.e., second stream 46) from the cryotank 10 and backup power unit or generator 110 indicates temporary operation for backup power as needed. The H2 extracted from the cryotank can be either gaseous or liquid. In both cases, the hydrogen needs to be warmed to near ambient conditions. This can be done in a separate heat exchanger or integrated into heat exchanger 60 (vaporizer). The cooling load can be included in the cooling load generated by the LHRS during normal operation. Alternatively, heating of second hydrogen stream 46 can be done in a manner that does not generate cooling load for refrigeration. In some embodiments, this is a preferred option to reduce cost or system complexity, as backup power operation may be intermittent. The generator can be a fuel cell, a hydrogen-powered combustion engine, or a hydrogen turbine.

[0052] 2, an exemplary system 200 is shown. The components of exemplary system 200 are the same as the components of exemplary system 100, except that exemplary system 200 includes a data center 120, a backup power unit 110 is configured to provide power to data center 120, and a refrigeration unit 90 is configured to provide cooling capacity to data center 120.

[0053] Backup power and cooling capacity can also be provided to other utilities, such as distribution centers (eg, for HVAC or refrigeration).

[0054] In some embodiments, the backup power unit 110 is configured to receive less than 30% by weight (eg, less than 20% by weight, or less than 10% by weight) of the total storage capacity of the liquid fuel in the cryotank 10 in a day.

[0055] As an example, exemplary system 200 is designed to integrate a liquid hydrogen refueling station (LHRS) with a capacity of 1 ton per day (tpd) with a micro-data center. The system includes the integration of an LHRS that distributes a total of 1 tpd to refueling medium duty vehicles (MDVs) or heavy duty vehicles (HDVs) (at 35 MPa) and a 50 kW data center. The size of 1 tpd is comparable to the size of existing hydrogen refueling stations. For example, an MDV delivery van has a tank capacity of approximately 10-20 kg. An HDV transit bus has a tank capacity of 30-60 kg. A 1 tpd station can serve an MDV fleet of approximately 50-100 vehicles or a transit bus fleet of approximately 16-33 vehicles.

[0056] An LHRS serving an MDV van or HDV bus must supply a pre-cooled fill, which is compressed hydrogen gas at a temperature ranging from -40°C to 0°C. Pre-cooling offsets the heat of compression generated during filling of the on-board vehicle storage tank, shortening the time required to complete the fill. LH2 is at a temperature between -253°C (20K) and -243°C (30K), depending on the pressure in the cryotank. A liquid hydrogen refueling station must supply sufficient heat to vaporize the liquid and raise the temperature of the gas to the range of -40°C to 0°C. The combination of latent and sensible heat required to operate the station is shown in Table 1. Results were calculated using data from the NIST Reference Fluid Thermodynamic and Transport Properties Database (REFPROP). [Table 1]

[0057] The required liquid hydrogen vaporization load depends on the liquid state (start temperature) and end temperature. For an LHRS fueled at -40°C, the required heat load is 3463 kJ / kg, but this load increases to 4382 kJ / kg for an ambient temperature fill at 25°C (Table 1). Conversely, this heat load is also the available cooling load when integrated with cooling applications such as data centers.

[0058] Using an exemplary value of 4000 kJ / kg, the total heating and cooling load available from a 1 tpd station is 4 GJ / d, or 1111 kWhth. If energy is stored in accumulator 80 and extracted at a steady rate, 46.3 kWth of cooling power is steadily available (at temperatures below 0°C).

[0059] The cooling load in a data center varies based on its design. One cooling load estimate suggests that 20-30% of total data center power consumption is associated with operating cooling equipment. The availability of low-temperature cooling load does not replace the need for power to operate fans, blowers, and other equipment.

[0060] Data centers vary in size and design. For example, using existing technology, a 50 kW micro data center can contain several servers and a backup system with five minutes of power, followed by 24 to 48 hours of operation from a diesel generator. A 20-30 MW-sized hyperscale data center can contain multiple racks, each designed to operate equipment with a cumulative electrical load of 30 to 100 kW. Backup power in hyperscale data centers is similarly configured with short-term battery power to provide UPS service, followed by diesel generators up to 20 MW in size. At the 20-30 MW scale, a supply of 55 to 130 tons of H2 is required to support 48 to 72 hours of backup power, along with the power generation capacity to use this fuel.

[0061] A cooling load of approximately 57.9 kW can improve the operation of a data center by replacing the chiller in the refrigeration cycle. This displaces a portion of the electrical load, resulting in more energy-efficient operation of the data center. For micro data centers, LHRS cooling can support the entire data center. For larger data centers, the LHRS cooling load can be integrated into a single rack. This benefit is scalable in proportion to the relative scale of the LHRS and data center.

[0062] For the refrigeration system or unit 90, the coefficient of performance is 2 to 4. This means that 57.9 kWth reduces the data center's power usage by 15 to 25 kW. Data centers report energy savings in terms of power utilization efficiency (PUE) (PUE = total power / IT power), aiming to get this parameter as close to 1 as possible. IT power (Power.IT) refers to the power used for information technology. Consolidation of the refrigeration unit 90 has a direct benefit to the PUE because it reduces the numerator as the power needed for cooling (P.cooling) is reduced. If 20% of a 50 kW data center's total power demand is cooling load, this means that the IT power is 40 kW, the P.cooling is 10 kW, and the PUE is 1.25. With the cooling consolidation proposed here, the PUE can approach 1.0, and fan and circulator pump power are the only consumption associated with managing the cooling in the data center.

[0063] Additionally, such a refueling station (LHRS) with a capacity of one ton per day (tpd) is also integrated with the backup power unit 110 for the micro-data center 120. The backup power needs of a data center vary depending on the size of the data center. For example, for liquid hydrogen needed for power generation, a 50 kW micro-data center requires 75 kg / day, 2-3 days / year, up to approximately 300 kg / year. A 20-30 MW data center requires 30 tpd for 2-3 days, up to approximately 100 t / year. If standalone storage tanks are used, the cost of LH2 storage becomes prohibitive because the standalone tanks incur boil-off losses to the point that productively used hydrogen has an unaffordable high cost base.

[0064] Using the systems and methods described herein, a 1 tpd refueling station needs to have a tank capable of handling daily operations. A tank capacity equivalent to several days is a design practice. An 18,000-gallon tank can hold approximately 4000 kg of H2. Drawing LH2 from a tank of this size for backup power operation in a 50 kW data center results in an incremental usage of less than 1% of the daily usage. A 1 tpd station can support larger backup operations, especially in fuel cell-enabled data centers that do not require standby power generation equipment, because the data center racks can be powered by H2. Backup power for several racks in a large data center can be accommodated using this station. The integration in this disclosure provides an advantage in productive use of H2 over standalone tanks for backup operation. The boil-off loss value relates to the refueling application, not the standby time for backup power.

[0065] 3, an exemplary system 300 is shown. The exemplary system 300 is similar to the exemplary system 200, except that the exemplary system 300 includes a production unit 130 and a liquefaction device 140.

[0066] In some embodiments, the exemplary system 300 further includes a liquefier 140 fluidly connected to the cryotank 10. The production unit 130 may be fluidly connected to the liquefier 140. The liquefier 140 is configured to compress gas produced in the production unit 130 into liquid fuel 12. The production unit 130 includes at least one electrolyzer for producing hydrogen gas from water. The at least one electrolyzer and / or the liquefier may be configured to be at least partially powered by solar or wind power 150. Instead of the production unit 130, the liquefier 140 or the cryotank 10 may be integrated with a liquid hydrogen distribution network, where liquid hydrogen is transported from the storage vessel to a refueling station or a point of use, such as for industrial production (e.g., steel production).

[0067] As Example 3, an exemplary system 300 is designed. A liquefaction site with an 8 tpd LHRS is integrated with a hyperscale data center for cooling and backup power. The LHRS is integrated with an upstream hydrogen production liquefaction system (i.e., production unit 130 and liquefaction unit 140) and data center 120. Data center 120 is connected to both refrigeration unit 90 and backup power unit 110.

[0068] Compared to Example 2, exemplary system 300 or Example 3 operates on a larger scale. The cryotank can hold over 100 tons of liquid H. Upstream H generation and liquefaction occurs at a 30 tpd scale, the LHRS distributes H for vehicle refueling at an 8 tpd scale, and the data center uses refrigeration loads at a 370 kWth scale and backup power at a 20 MW scale.

[0069] Integration in such a system provides synergistic benefits. Additional features may be included. For example, H2 production can be implemented at a 30 tpd scale using electrolyzers powered by renewable energy (approximately 60 MW required for 30 tpd). Liquefaction in multiple 30 tpd facilities can be operated at this scale. An 8 tpd scale LHRS using H2 produced by electrolysis and liquefaction can be implemented using the exemplary system 300. This scale is envisioned for a Class 8 truck refueling depot.

[0070] The exemplary system 300 can be used for a 20 MW hyperscale data center with the potential need for hydrogen-derived backup power. In the exemplary system 300, the data center 120 can be configured to operate on H2 for prime power. The backup H2 fuel supply can be obtained from a liquefier-supplied cryotank. The prime power H2 fuel supply can be generated independently of the LH2 supply for backup power generation generated by the liquefier 140. While fuel for backup power is stored as LH2 for temporary use as needed, daily use of LH2 is for refueling purposes. LH2 accumulates over time in the cryotank 10, and the size of the cryotank allows for temporary use of the stored LH2 for backup power. This configuration overcomes the prior art limitation of severe boil-off loss values ​​for LH2 stored as backup fuel.

[0071] The size of the cryotank 10 can be determined based on backup power requirements. In some embodiments, the flow of the second stream 46 for backup power generation is less than 20% or 10% of the total hydrogen in the cryotank 10. In some embodiments, the size of the cryotank 10 is less than 4 tons of LH2 (18,000 gal) and meets regulatory standards. In some embodiments, the size of the cryotank is greater than 99 tons of LH2. Larger tanks can be installed at the liquefaction system site.

[0072] According to some embodiments, the present disclosure provides a system that is a hydrogen refueling station with an integrated system for refrigeration and backup power. The system or station includes a cryotank 10 containing liquid hydrogen (LH), a liquid pump 40 configured to compress a flow of LH from the cryotank 10, a heat exchanger 60 configured to vaporize the compressed hydrogen output from the liquid pump 40, a mixer 70, a dispenser 72, and a refrigeration unit 90. The mixer 70 is configured to combine the vaporized hydrogen output from the heat exchanger 60 with the LH flow from the cryotank 10 to produce a compressed hydrogen stream having a pressure of 25 to 90 MPa and a temperature between -50°C and ambient temperature. The dispenser 72 can deliver the compressed hydrogen stream from the mixer 70 to an onboard hydrogen storage tank at a pressure range of 35 to 70 MPa (inclusive) and a temperature range of -40°C to ambient temperature. Refrigeration unit 90 is integrated with heat exchanger 60 to provide a heat load to the LH2 stream and a cooling load to refrigeration unit 90 at a temperature between -40°C and ambient temperature. The system or station also includes a backup power unit 110 that can be powered by hydrogen from cryotank 10. The backup power unit's daily hydrogen usage is less than 30% of the full capacity of cryotank 10. Optionally, refrigeration unit 90 provides cooling capacity to a data center, and the cooling load is at least 10% of the daily cooling load used by the data center. Optionally, backup power unit 110 provides backup power to data center 120.

[0073] Referring to Figure 4A, an exemplary method 400 is shown. Such a method may be used for refueling while also providing backup power and cooling capacity. Figure 4B illustrates several steps that may be included in the exemplary method 400.

[0074] 4A, in step 402, liquid fuel 12 is provided inside cryotank 10. Liquid fuel 12 includes a liquid phase 14 and a gas phase 16. In some embodiments, the liquid fuel includes or is hydrogen.

[0075] In some embodiments, the liquid fuel 12 in the cryotank is provided from a liquefier 140 fluidly connected to the cryotank 10. The liquefier 140 compresses gas produced in the production unit 130 into liquid fuel 10. For example, the production unit 130 includes at least one electrolyzer for producing hydrogen gas from water. In some embodiments, the at least one electrolyzer or the liquefier 140, or both, are at least partially, e.g., at least 50%, powered by solar or wind power.

[0076] In step 404, a first stream 42 of liquid fuel 12 is pumped from the cryotank 10 through a pump 40 fluidly connected to the cryotank 10. The first stream 42 of liquid fuel 12 may be in a supercritical state. In some embodiments, the pump is a submersible liquid pump located inside the cryotank 10. The first stream 42 of liquid fuel 12 is pumped from the cryotank 10 by compressing the liquid fuel 12 using the submersible liquid pump.

[0077] In step 406, at least a portion of the first stream 42 of liquid fuel 12 is converted to gaseous fuel 54 via heat exchanger 60. Heat exchanger 60 is thermally connected to the first stream 42 of liquid fuel.

[0078] In step 408, at least a portion of the gaseous fuel 54 is dispensed to a receiving fuel tank, such as an on-board vehicle storage tank. As described herein with respect to mixer 70, the dispensed fuel may be compressed gaseous fuel or liquid fuel. For heavy vehicles, light vehicles, and rail, the fuel is dispensed as compressed gaseous fuel. For liquid tanks and silo compression tanks, the fuel is dispensed as a liquid.

[0079] In step 410, cooling power is provided to a facility in need thereof from the refrigeration unit 90 integrated with the heat exchanger 60. The cooling power may be provided in the form of a cooling medium, such as a cold gas or fluid. The refrigeration unit 90 may be thermally connected to the heat exchanger 60. The refrigeration unit 90 and the heat exchanger 60 may exchange heat with each other. The process of step 410 may include steps 412 and 414 of FIG. 4B. In step 412, a heat load is provided from the refrigeration unit 90 to the heat exchanger 60 to vaporize liquid fuel. In step 414, a cooling load is provided from the heat exchanger 60 to the refrigeration unit 90. As described above, the refrigeration unit 90 may include the accumulator 80. The refrigeration unit 90 is configured to provide the heat load to the heat exchanger to convert liquid fuel in a liquid or supercritical state to gaseous fuel 54, and the heat exchanger 90 is configured to provide the cooling load to the refrigeration unit 90 to cool a facility, such as a data center. In some embodiments, the refrigeration unit 90 provides cooling capacity to meet at least 10%, for example, 10%, 20%, 30%, 40%, 50%, 60%, or 70% of the data center's cooling load.

[0080] 4B , in some embodiments, the exemplary method 400 further includes steps 416 and 418. In step 416, the first stream 42 of liquid fuel 12 is separated into a first portion 51 and a second portion 52 via a splitter 50. The first portion 51 passes through a heat exchanger 60 (i.e., a vaporizer). In step 418, the gaseous fuel 54 and the second portion 52 are combined in a mixer 70 to form a dispensed fuel. The dispensed fuel can be a compressed gaseous fuel or a dispensed liquid fuel. In some embodiments, the dispensed fuel is a compressed H2 stream having a pressure of 25 MPa to 90 MPa and a temperature of −50° C. to ambient temperature. A dispenser 72 can deliver the compressed H2 stream from the mixer 70 to an on-board hydrogen storage tank at a pressure of 35 MPa to 70 MPa (inclusive) and a temperature of −40° C. to ambient temperature. The cooling load from heat exchanger 60 to refrigeration unit 90 is from -50°C to ambient temperature.

[0081] 4A , in step 420, electrical power is generated in the backup power unit 110 using a second stream 46 of the liquid fuel 12. The second stream 46 may be in the gas phase, liquid phase, or both from the cryotank 10. In some embodiments, after passing through the heat exchanger 60 and being used for cooling, at least a portion of the gaseous fuel 54 may also be supplied to the backup power unit 110 to generate electrical power. In some embodiments, electrical power is generated through one or more fuel cells or combustion engines in the backup power unit 110. Suitable examples of combustion engines include, but are not limited to, reciprocating engines, and gas turbines or microturbines.

[0082] In some embodiments, less than 30% by weight of the total storage capacity of the liquid fuel 12 in the cryotank 10 is provided to the backup power unit 110 over the course of a day when backup power is needed. For example, less than 20% or 10% by weight of the liquid fuel 12 stored in the cryotank 10 is used for backup power generation over the course of a day when backup power is needed. In some embodiments, the power generated by the backup power unit 110 is provided to the data center 120. The power generated by the backup power unit 110 can also be supplied to other components in the system, such as the refrigeration unit 90, the pump 40, the heat exchanger 60, and the dispenser 72, when additional power is needed. The cooling capacity from the refrigeration unit 90 is used to cool the data center 120.

[0083] In the present system and method, the refueling process may be performed periodically, the cooling load may be generated periodically from the refueling station, and the backup power may be generated temporarily.

[0084] In some embodiments, the systems provided herein may further include one or more control units or central units (not shown in FIGS. 1-3 ) for controlling the process steps and fuel quantities at each step or through each component. The control unit may be electronically connected to relevant components in the system. For example, it may control the amounts of the first fuel stream 42, the second fuel stream 46, the first portion 51, and the second portion 52. It may also control the amounts and ratios of the gaseous fuel 54 and the second portion 52 for blending. The control unit may include one or more processors and at least one tangible, non-transitory, machine-readable medium encoded with one or more programs executed by the one or more processors. The control unit is configured to coordinate with each component to control operations for vehicle refueling, data center cooling, and backup power replenishment.

[0085] The methods and systems described herein may be implemented, at least in part, in the form of computer-implemented processes and apparatuses for performing those processes. The disclosed methods may also be embodied, at least in part, in the form of a tangible, non-transitory, machine-readable storage medium encoded with computer program code. The medium may include, for example, RAM, ROM, CD-ROM, DVD-ROM, BD-ROM, hard disk drive, flash memory, or any other non-transitory, machine-readable storage medium, or any combination of these media. When the computer program code is loaded into and executed by a computer, the computer becomes an apparatus for performing the method. The methods may also be embodied, at least in part, in the form of a computer into which the computer program code is loaded and / or executed, such that the computer becomes an apparatus for performing the method. When implemented on a general-purpose processor, the computer program code segments configure the processor to create specific logic circuits. Alternatively, the methods may be embodied, at least in part, in a digital signal processor formed with an application-specific integrated circuit for performing the method. The computer or control unit may be remotely controlled using a cloud-based system.

[0086] The systems and methods provided in the present disclosure offer many advantages, as described herein. For example, in some embodiments, the present disclosure provides a hydrogen refueling station for refueling vehicles while also providing backup power and cooling capacity for, for example, a data center. Compared to standalone storage options, the systems disclosed in the present disclosure significantly reduce the relative losses due to hydrogen boil-off used to generate backup power for the data center. Liquid hydrogen stored in cryotanks is used effectively. Excess cooling load from the heat exchanger or vaporizer is utilized efficiently and productively. The system provides much higher cooling capacity, while the heat exchanger is used much more effectively when integrated with the refrigeration unit.

[0087] Tank size can be determined by refueling operations and backup power requirements. While boil-off can still occur due to heat leakage into the tank, coupling to a refueling station reduces boil-off for productive use. As an illustrative example, if only a backup power unit is used, the tank can hold 10 tons of H2 and lose 9 tons to boil-off over the course of a year, leaving only 1 ton for valuable use in backup power generation. Using the system and method described above, the storage tank can be the same size, but the LH2 is used for production purposes. Assuming the tank is refilled weekly, the tank will hold approximately 520 tons of LH2 per year. Even with the same amount of boil-off, at least 511 tons will be used for production purposes. Furthermore, if the boil-off gas is used more frequently to generate electricity, boil-off losses can be further reduced.

[0088] The present system and method also provide the following advantages: For example, the operation of a liquid hydrogen refueling station (LHRS) is improved by more efficient operation of the heat exchanger 60 (vaporizer). The heat provided by the accumulator 80 improves the operability of the heat exchanger 70. For example, a forced-draft vaporizer used as a heat exchanger can accumulate ice on the heat transfer surfaces due to freezing of moisture from the air. The ice layer reduces the heat transfer coefficient, resulting in the need to increase airflow through the system or adjust the controls of the LHRS. The use of an active heat supply from the accumulator 80 in the refrigeration unit 90 circumvents this limitation and expands the operating window of the LHRS.

[0089] In another embodiment, the system and method provides for productive use of excess cooling load from heat exchanger 60 during LHRS operation. Excess cooling load from normal operation of the LHRS is used for productive cooling purposes. This reduces the net energy demand from the external cooling process.

[0090] Additionally, the system and method provide for the efficient use of cryotank boil-off for LHRS and data center operations. The backup power unit 110 can utilize the hydrogen stored in the cryotank 10. The cryotank 10 is sized for LHRS operation. In accordance with common practice, the cryotank 10 can be sized to contain liquid hydrogen for at least three days of operation, for example. A station with a fuel supply capacity of one ton per day would use a cryotank with a capacity of at least three tons of LH2.

[0091] A typical boil-off rate for an industrial-grade cryotank is approximately 1% / day, which indicates a boil-off loss value of approximately 40 kg / day for a tank with a 4-ton capacity (18,000 gallon tank). A 60%-efficient polymer electrolyte membrane (PEM) fuel cell can generate electricity at a rate of 20 kWh / kg, so a daily boil-off flow of 40 kg / day can sustain an average power generation rate of 33 kW. This power can be used to support LHRS operation, normal downstream loads from integration with other systems (e.g., refrigeration or backup power clients), or both. If the relative H2 demand for backup power is less than the normal daily demand, the LHRS system can operate in parallel with backup power generation for at least one day.

[0092] Backup power can be provided intermittently, for example, less frequently than daily. When backup power is needed, additional H2 can be extracted to provide fuel for power generation (dotted box in Figure 1). In the example of a 4-ton capacity tank, 30% of the limit corresponds to 1200 kg of H2, which can support daily demands up to 1.7 MW, providing sufficient installed fuel cell capacity. Alternatively, incremental H2 extraction from the cryotank can be used to operate other power generation equipment, including but not limited to combustion turbines, microturbines, or reciprocating engines, to generate electricity. Net power depends on the efficiency of the power conversion device. A 400 kWe hydrogen microturbine system at 40% efficiency could use 30 kg / h to generate the desired output.

[0093] The daily 30% usage limit of cryotank capacity provides a period of opportunity for refilling the cryotank 10 or restoring primary power. For data center backup, a 2-3 day backup fuel supply is required. If an extended outage is anticipated, re-fueling or backup power operations can be coordinated over one or more days to optimize use of stored LH2.

[0094] As another advantage, the present system and method reduce boil-off losses of H2 used for backup power compared to stand-alone storage options. Storage of fuel for a system with a backup power unit 110 does not incur boil-off losses beyond the operational losses associated with LHRS operation. Storage of LH2 for the backup power unit 110 is considered impractical by those skilled in the art due to the high boil-off losses associated with the transient usage profile of backup power systems such as those published by G Saur et al. With transient backup power demands, a portion of the fuel for the backup power unit 110 is lost as boil-off. The less frequent the demand, the more fuel is lost. Integration of LH2 with a cryotank 10 for an LHRS whose primary use is for refueling demands reduces the boil-off losses associated with an LH2-fueled backup power system.

[0095] While the present subject matter has been described with respect to exemplary embodiments, it is not limited thereto. Rather, the appended claims should be construed broadly to include other modifications and embodiments that may occur to those skilled in the art. [Brief explanation of the drawings]

[0096] [Figure 1] FIG. 1 is a block diagram illustrating a first exemplary system, such as a hydrogen refueling station, including a backup generator and a refrigeration unit, according to some embodiments. [Figure 2] FIG. 10 is a block diagram illustrating a second exemplary system, such as a hydrogen refueling station, including a backup generator for providing backup power to a data center and a refrigeration unit for providing a cooling load to the data center, according to some embodiments. [Figure 3] FIG. 10 is a block diagram illustrating a third exemplary system, such as a hydrogen refueling station, including a backup generator for providing backup power to a data center, a refrigeration unit for providing cooling loads to the data center, a hydrogen production unit, and a liquefaction device, according to some embodiments. [Figure 4A] 1 is a flowchart illustrating an exemplary method that includes distributing a liquid fuel, such as hydrogen, providing backup power, and providing a cooling load, according to some embodiments. [Figure 4B] 4B is a flowchart illustrating some steps that may be included in the example method of FIG. 4A.

Claims

1. a cryotank configured to store a liquid fuel therein, the liquid fuel including a liquid phase and a gas phase; a pump fluidly connected to the cryotank and configured to pump a first flow of the liquid fuel in the liquid phase from the cryotank; a heat exchanger connected to the pump and configured to convert at least a portion of the first flow of the liquid fuel in the liquid phase into a gaseous fuel; a dispenser configured to dispense at least a portion of the gaseous fuel into a receiving fuel tank; a refrigeration unit integrated with the heat exchanger, the refrigeration unit configured to provide a heat load to the heat exchanger and the heat exchanger configured to provide a cooling load to the refrigeration unit; a backup power unit configured to receive a second flow of the liquid fuel in the vapor phase, the liquid phase, or both, from the cryotank and generate electrical power; a splitter disposed between the pump and the heat exchanger and configured to split the first flow of the liquid fuel into a first portion and a second portion; the heat exchanger is configured to convert the first portion to the gaseous fuel; a mixer configured to combine the gaseous fuel and the second portion to form a compressed gaseous or liquid fuel to be dispensed; the pump is an immersible liquid pump disposed within the cryotank and configured to compress the first flow of the liquid fuel in the liquid phase; The backup power unit is further configured to receive at least a portion of the gaseous fuel from the heat exchanger to generate the electrical power.

2. The system of claim 1 , wherein the liquid fuel comprises hydrogen.

3. The system of claim 1 , wherein the gaseous fuel is compressed hydrogen having a pressure ranging from 25 MPa to 90 MPa and a temperature ranging from −50° C. to ambient temperature.

4. The system of claim 1 , wherein the backup power unit is configured to receive less than 30% by weight of the total storage capacity of the liquid fuel in the cryotank in one day.

5. The system of claim 1 , wherein the backup power unit is configured to receive no more than 20% by weight of the total storage capacity of the liquid fuel in the cryotank in one day.

6. the backup power unit is configured to supply the power to a data center; The system of claim 1 , wherein the refrigeration unit is configured to provide cooling capacity to the data center.

7. 2. The system of claim 1, wherein the backup power unit comprises one or more fuel cells or combustion engines for generating the electrical power from the second stream of the liquid fuel in the gas phase, the liquid phase, or both.

8. a liquefaction device fluidly connected to the cryotank; and a production unit fluidly connected to the liquefaction device; The system of claim 1 , wherein the liquefier is configured to compress gas produced in the production unit into the liquid fuel.

9. the production unit comprises at least one electrolyzer for producing hydrogen gas from water; 10. The system of claim 8, wherein the at least one electrolyzer or the liquefaction device or both are configured to be at least partially powered by solar or wind power.

10. supplying a liquid fuel stored inside a cryotank, the liquid fuel including a liquid phase and a gas phase; pumping a first flow of the liquid fuel in the liquid phase from the cryotank through a pump fluidly connected to the cryotank; converting at least a portion of the first flow of the liquid fuel in the liquid phase to a gaseous fuel through a heat exchanger connected to the pump; distributing at least a portion of the gaseous fuel to a receiving fuel tank; a step of supplying cooling capacity from a refrigeration unit integrated with the heat exchanger to equipment requiring cooling; generating electrical power in a backup power unit using a second flow of the liquid fuel in the vapor phase, the liquid phase, or both, from the cryotank; The method comprises: further dividing the first flow of the liquid fuel into a first portion and a second portion, the first portion passing through the heat exchanger; combining the gaseous fuel with the second portion to form a dispensed compressed gaseous or liquid fuel; the first flow of the liquid fuel in the liquid phase is pumped from the cryotank by compressing the liquid fuel using an immersed liquid pump located inside the cryotank; The method further includes delivering at least a portion of the gaseous fuel from the heat exchanger to the backup power unit to generate the electrical power.

11. The method of claim 10 , wherein the liquid fuel comprises hydrogen.

12. The method of claim 10, further comprising the steps of: supplying a heat load from the refrigeration unit to the heat exchanger; and supplying a cooling load from the heat exchanger to the refrigeration unit.

13. 11. The method of claim 10, wherein less than 30% by weight of the total storage capacity of the liquid fuel in the cryotank is supplied to the backup power unit on any day that backup power is needed.

14. The method of claim 10 , wherein the backup power unit provides power to a data center and the cooling capacity from the refrigeration unit is used to cool the data center.

15. The method of claim 10 , wherein the electrical power is generated via one or more fuel cells or combustion engines in the backup power unit.

16. the liquid fuel in the cryotank is supplied from a liquefaction device fluidly connected to the cryotank; 11. The method of claim 10, wherein the liquefier is configured to compress gas produced in a production unit into the liquid fuel.

17. the production unit comprises at least one electrolyzer for producing hydrogen gas from water; 17. The method of claim 16, wherein the at least one electrolyzer or the liquefaction device or both are at least partially powered by solar or wind power.

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