Installation and process for the production of liquefied hydrogen

Abstract

The invention relates to an installation and a method for producing liquefied hydrogen comprising a gaseous hydrogen generator (2), a liquefier (7), a supply line (6) connecting an outlet of the gaseous hydrogen generator (2) to an inlet of the liquefier (7), the liquefier (7) comprising a refrigerator (8) with a cycle circuit (18) for cooling the gaseous hydrogen in the supply line (6), the installation (1) comprising a buffer storage (9) configured to store the compressed gaseous hydrogen between the gaseous hydrogen generator (2) and the liquefier (7), the liquefier (7) being configured to provide a cold power and / or the liquefaction capacity that can be modified between at least two levels (N1, N2), the installation (1) comprising a member (3) for determining the filling rate of the buffer storage (9),the installation (1) being configured to modify the cold power and / or liquefaction capacity of the liquefier (7) as a function of the filling rate of the buffer storage (9) determined by the determination member (3). Abstract figure: Fig. 1,

Description

Title of the invention: Installation and method for producing liquefied hydrogen

[0001] The invention relates to an installation and a method for producing liquefied hydrogen.

[0002] The invention relates more particularly to a liquefied hydrogen production installation comprising a gaseous hydrogen generator, for example an electrolyser, configured to produce gaseous hydrogen, a liquefier, a supply line connecting a gaseous hydrogen outlet of the gaseous hydrogen generator to an inlet of the liquefier, the liquefier comprising a cycle circuit refrigerator configured to provide cold power and cool the gaseous hydrogen from the supply line with a view to its liquefaction, the installation comprising a buffer storage configured to store the compressed gaseous hydrogen between the gaseous hydrogen generator and the liquefier.

[0003] The invention relates, for example, to the production of hydrogen with electrolysers powered electrically by renewable energy sources. This type of installation can be connected downstream to a gas network, to a liquefier, to an ammonia or methanol production unit. Control of these installations according to the electrical production capacities of the renewable energy source is essential. This control makes it possible in particular to reduce investments which may be buffer storage or additional equipment to manage intermittency. Such control also makes it possible to improve production capacities by avoiding losses and to reduce production costs by limiting the use of the electricity network.

[0004] Liquefiers have a relatively limited capacity to change their operating point (or "run"). That is to say, the cold power and / or the liquefaction capacity of the liquefier is difficult to modify.

[0005] A solution to deal with fluctuations in intermittent energy sources (and therefore in the production of hydrogen to be liquefied) therefore consists of providing buffer storage of gaseous hydrogen to enable the liquefier's supply circuit to be supplied.

[0006] These buffer storages can be arranged in series between the electrolyser and / or can be connected in parallel with the liquefier at the outlet of the electrolyser.

[0007] The control solutions for these installations are unsatisfactory.

[0008] An aim of the present invention is to overcome all or part of the drawbacks of the prior art noted above.

[0009] To this end, the according to the invention, moreover in accordance with the generic definition given in the preamble above, is essentially characterized in that the liquefier is configured to provide a cold power and / or the liquefaction capacity modifiable between at least two levels, the installation comprising a member for determining the filling rate of the buffer storage, the installation being configured to modify the cold power and / or liquefaction capacity of the liquefier as a function of the filling rate of the buffer storage determined by the determining member.

[0010] Furthermore, embodiments of the invention may include one or more of the following features: - the device for determining the filling rate of the buffer storage is configured to determine the filling rate of the buffer storage from among several predefined filling rates, the installation being configured to establish the cold power and / or the liquefaction capacity at determined levels corresponding respectively to the predefined filling rates of the buffer storage, - the installation is configured to relatively reduce the cooling power and / or the liquefaction capacity of the liquefier when the filling rate of the buffer storage decreases, - the installation is configured to relatively increase the cooling power and / or the liquefaction capacity of the liquefier when the filling rate of the buffer storage increases, - the installation is configured to modify the cold power and / or the liquefaction capacity according to the filling rate of the buffer storage determined by the determination device after a determined time delay, for example between one and ten hours, - the device for determining the filling rate of the buffer storage includes a pressure sensor, - the pressure sensor is configured to measure the pressure in the buffer storage and / or in a pipe connected to an outlet of the buffer storage, - the liquefier comprises a cycle circuit refrigerator in which a cycle gas flow rate is subjected to a determined thermodynamic cycle, the installation being configured to modify the cooling power and / or liquefaction capacity of the liquefier by modifying the flow rate and / or the quantity of cycle gas in the cycle circuit, - the installation is configured to reduce the cooling power and / or liquefaction capacity by reducing the flow rate and / or the quantity of cycle gas in the cycle circuit via at least one of: an evacuation pipe of cycle gas to the supply line, a cycle gas discharge line to a discharge zone, a member for liquefying at least part of the cycle gas in the cycle circuit, - the liquefier comprises a cycle circuit refrigerator in which a cycle gas flow is subjected to a determined thermodynamic cycle comprising compression and expansion, the installation being configured to modify the cooling power and / or liquefaction capacity of the liquefier by modifying the compression pressure level of the cycle gas in the cycle circuit, - the liquefier comprises several independent cycle circuit refrigerators each configured to provide respective cooling power to cool the gaseous hydrogen in the supply line for liquefaction and in that the installation is configured to modify the cooling power and / or liquefaction capacity of the liquefier by differentially modifying the cooling power and / or liquefaction capacity of the different refrigerators, - the member for determining the filling rate of the buffer storage comprises a programmable electronic data storage and processing member comprising a microprocessor, the member for determining the filling rate being configured to receive operating data from the gaseous hydrogen generator and for and / or data on the consumption of liquid hydrogen produced by the liquefier and to predict, from this data, a future filling rate of the buffer storage in a future time interval, for example between one and twenty-four hours, the installation being configured to modify the cold power and / or liquefaction capacity of the liquefier as a function of the future filling rate of the buffer storage determined by the determining member, - the hydrogen gas generator comprises an intermittent power supply provided by a renewable energy source, for example solar, the filling rate determining member being configured to receive weather forecast data and to predict, also from this data, the future filling rate of the buffer storage.

[0011] The invention also relates to a method for producing liquefied hydrogen using an installation conforming to any one of the preceding or following characteristics comprising the following steps: determining the filling rate of the buffer storage, and regulating the cold power and / or liquefaction capacity as a function of the determined filling rate of the buffer storage.

[0012] According to other possible particularities: - the determination of the filling rate of the buffer storage is measured, for example via a pressure measurement and / or estimated and / or predicted from operating data of the installation among: the hydrogen production capacity by gaseous hydrogen generator, a history of the hydrogen production capacity by gaseous hydrogen generator, meteorological data, current or future consumption of liquid hydrogen produced by the liquefier, - the step of regulating the cold power and / or liquefaction capacity of the liquefier comprises a modification of the cold power and / or liquefaction capacity of the liquefier which is carried out in response to a change in the filling rate of the buffer storage, the modification of the cold power and / or liquefaction capacity being carried out concomitantly and / or in advance of and / or after the change in the filling rate of the determined buffer storage, - the liquefier comprises a cycle circuit refrigerator in which a cycle gas flow rate is subjected to a determined thermodynamic cycle, the step of regulating the cooling power and / or the liquefaction capacity of the liquefier comprising at least one of: a modification of the flow rate and / or the quantity of cycle gas in the cycle circuit, for example a discharge of cycle gas outside the cycle circuit, a reduction in the quantity of gas in the cycle circuit by partial liquefaction of the cycle gas in a separator pot, a modification of the compression pressure of the cycle gas in the cycle circuit, - the method comprises a step of shutting down the installation in which the liquefier is shut down, followed by a step of restarting the installation and the liquefier, the method comprising, after restarting and before a step of regulating the cold power and / or liquefaction capacity of the liquefier, a determined time delay, for example between two and twelve hours, and / or a time delay as long as the filling rate of the buffer storage does not reach a determined threshold.

[0013] The invention may also relate to any alternative device or method comprising any combination of the above or below features within the scope of the claims.

[0014] Other features and advantages will appear on reading the description below, given with reference to the figures in which: Brief description of the figures

[0015] The invention will be better understood upon reading the following description given solely by way of example and made with reference to the accompanying drawings in which:

[0016] [Fig. 1] is a schematic and partial view illustrating the structure and operation of a first exemplary embodiment of the invention,

[0017] [Fig.2] is a schematic and partial view illustrating the structure and operation of a second exemplary embodiment of the invention. Detailed description

[0018] In all the figures, the same references refer to the same elements.

[0019] In this detailed description, the following embodiments are examples. Although that the description refers to one or more embodiments, this does not mean that the features apply only to a single embodiment. Single features of different embodiments may also be combined and / or interchanged to provide other embodiments.

[0020] The liquefied hydrogen production installation 1 illustrated in [Fig.l] comprises a gaseous hydrogen generator 2, for example an electrolyser 2, configured to produce gaseous hydrogen, a liquefier 7 and a supply pipe 6 connecting a gaseous hydrogen outlet of the gaseous hydrogen generator 2 to an inlet of the liquefier 7.

[0021] The installation 1 comprises a buffer storage 9 configured to store the compressed hydrogen gas between the hydrogen gas generator 2 and the liquefier 7. In this example, the buffer storage 9 is arranged in series between the hydrogen gas generator 2 and the liquefier 7.

[0022] As illustrated, the installation 1 may comprise at least one compressor 10 of the gaseous hydrogen produced by the gaseous hydrogen generator 2 in order to fill the buffer storage 9.

[0023] The liquefier 7 comprising a refrigerator 8 with a cycle circuit 18 configured to provide cold power and cool the hydrogen gas in the supply line 6 for liquefaction.

[0024] The liquefier 7 is configured to provide cold power and / or liquefaction capacity that can be modified between at least two distinct levels (NI, N2).

[0025] The installation 1 comprises a member 3 for determining the filling rate of the buffer storage 9 and the installation 1 is configured to modify the cold power and / or liquefaction capacity of the liquefier 7 as a function of the filling rate of the buffer storage 9 determined by the determination member 3.

[0026] For example, the member 3 for determining the filling rate of the buffer storage 9 is configured to determine the filling rate of the buffer storage 9 from among several predefined filling rates and the installation 1 is configured to establish the cold power and / or the liquefaction capacity of the liquefier 7 at levels defined completed corresponding respectively to the predefined buffer storage filling rates 9.

[0027] The member 3 for determining the filling rate of the buffer storage 9 may comprise, for example, a pressure sensor measuring the pressure in the buffer storage 9.

[0028] The pressure sensor 3 is for example configured to measure the pressure in the buffer storage 9 and / or in a pipe connected to an outlet of the buffer storage 9.

[0029] A filling rate can be determined based on the measured pressure value.

[0030] For example, a filling rate of 0% can be defined for a minimum pressure upstream of a liquefier inlet valve (20 to 40 bar for example).

[0031] A filling rate of 100% can be defined for a maximum pressure upstream of a liquefier inlet valve (40 to 100 bar for example).

[0032] Thus, for example, the installation can be configured to relatively reduce the cold power and / or the liquefaction capacity of the liquefier 7 when the filling rate of the buffer storage 9 decreases.

[0033] Similarly, the installation can be configured to relatively increase the cold power and / or the liquefaction capacity of the liquefier 7 when the filling rate of the buffer storage 9 increases.

[0034] Thus, the operation of the liquefier 7 can be fixed according to the filling rate of the buffer storage 9 (filling rate measured for example by its pressure) with fixed action levels not depending on the actual production characteristics of the liquefier 7. For example, all or part of the following configurations can be provided with for example the following actions on the liquefier.

[0035] If the filling rate of the buffer storage(s) 9 is 70% or more, the operation of the liquefier 7 can be set at 100%.

[0036] If the filling rate of the buffer storage(s) 9 is 50% or more, the operation of the liquefier 7 can be set at 75%.

[0037] If the filling rate of the buffer storage(s) 9 is 35% or more, the operation of the liquefier 7 can be set at 50%.

[0038] If the filling rate of the buffer storage(s) 9 is 10% or more, the operation of the liquefier 7 can be set at 25%.

[0039] If the filling rate of the buffer storage(s) 9 is 2% or less, the operation of the liquefier 7 can be set to 0%.

[0040] The installation can be configured to limit the frequency or number of changes in operation of the liquefier, for example to avoid going back and forth around an operating point.

[0041] For example, the installation can be configured to modify the cooling power and / or the liquefaction capacity liquefier 7 only after a determined time delay, for example between one and ten hours (following a change in the filling rate of the buffer storage 9).

[0042] For example, a minimum delay of six hours may be provided between two changes.

[0043] Similarly, in the event of start-up of the installation 1 (start-up and cooling of the liquefier 7), such start-up may only be possible after a delay of 6 hours and if the filling rate of the buffer storage 9 is greater than or equal to a threshold, for example 50%.

[0044] The liquefier 7 comprises for example at least one refrigerator 8 with a cycle circuit 18 in which a cycle gas flow rate is subjected to a determined thermodynamic cycle comprising an expansion. The installation 1 can be configured to modify the cooling power and / or liquefaction capacity of the liquefier 7 by modifying for example the flow rate and / or the quantity of cycle gas in the cycle circuit 18.

[0045] For example, the installation may be configured to reduce the cooling power and / or liquefaction capacity of the liquefier 7 by reducing the flow rate and / or the quantity of cycle gas in the cycle circuit 18. This may be achieved, for example, via at least one of: a cycle gas discharge pipe to the supply pipe 6, a cycle gas discharge pipe to a discharge zone, a member for liquefying at least a portion of the cycle gas in the cycle circuit 18.

[0046] In the case where the liquefier 7 comprises a refrigerator 8 with a cycle circuit 18 in which a cycle gas flow rate is subjected to a determined thermodynamic cycle comprising a compression 80 and an expansion, the installation can be configured to modify the cold power and / or liquefaction capacity of the liquefier 7 by modifying the compression pressure level 80 of the cycle gas in the cycle circuit 18.

[0047] Similarly, the liquefier may comprise several independent cycle circuit 18 refrigerators 8 (i.e. several “trains” in parallel) each configured to provide respective cold power to cool the gaseous hydrogen in the supply line 6 for its liquefaction; In this case, the installation 1 may be configured to modify the cold power and / or liquefaction capacity of the liquefier 7 by modifying in a differentiated manner the cold power and / or liquefaction capacity of the different refrigerators 8.

[0048] Thus, for example, in the case of a liquefier with several trains of refrigerators in parallel (three trains for example), the installation can be configured to modify the control of the operation of one or more trains, for example by reducing the power to 25% if the filling rate of the buffer storage falls below 20%.

[0049] To reduce the running time, the installation 1 can be provided, for example, to switch off the trains one after the other to maintain liquefaction capacity.

[0050] For example, if the filling rate of the buffer storage 9 falls below a first threshold (for example 15%), the trains (three for example) can each be set to a step of 25% of their maximum cold power.

[0051] Similarly, if the filling rate of the buffer storage 9 falls below a second threshold (for example 10%), a train can be stopped and the other trains (two for example) can each be set to a step of 25% of their maximum cold power.

[0052] Similarly, if the filling rate of the buffer storage 9 falls below a third threshold (for example 2%), a second train can be stopped and the remaining train can be set to a running of 25% of its maximum cold power.

[0053] A gradual restart of the installation can be done conversely by gradually starting up the liquefaction trains.

[0054] [Fig.2] illustrates a variant with a buffer storage 9 connected in parallel with the liquefier 7.

[0055] For example, a filling rate of 0% can be defined for a minimum pressure in the buffer storage 9 (20 to 40 bar for example).

[0056] A filling rate of 100% can be defined for a maximum pressure in the buffer storage 9 (40 to 250 bar for example). Operating cases can be predefined (50%, 75%, 100% filling rate or operation for example). This makes it possible to automatically modify the control values ​​of the installation 1 to achieve efficient operation.

[0057] For example, the decrease in cold power produced by the liquefier (operation) can be controlled with the measures below, preferably taken in isolation or in combination or sequentially in this order: - reduction of the cycle gas flow in the refrigerator(s) cycle, - reduction of the quantity of cycle fluid in the cycle circuit for reduce the high pressure in the cycle circuit (while maintaining the low pressure after expansion).

[0058] For example, in the case of a cycle gas consisting of or comprising hydrogen, a fraction of this cycle gas can be transferred into the supply circuit 6.

[0059] In the case of a cycle gas consisting of or comprising nitrogen (nitrogen cycle refrigerator), a fraction of this cycle gas can be evacuated to the outside (venting for example).

[0060] In the case of a change in pressure within the refrigerator cycle, for example in the case of a nitrogen cycle and / or a hydrogen cycle, the refrigerator cor respondent can be controlled to change at least one pressure value (relatively low, medium or high) in the cycle.

[0061] For example, the member for determining the filling rate of the buffer storage 9 may comprise a programmable electronic member 4 for storing and processing data comprising a microprocessor.

[0062] Similarly, the control (modification) of the operation of the refrigerator 7 as described above can be carried out by this programmable electronic data storage and processing unit 4 (and / or another unit of the same type).

[0063] For example, such an electronic device can implement the control actions of the installation 1 described above.

[0064] The member 3 for determining the filling rate can be configured to receive operating data from the gaseous hydrogen generator 2 and for and / or data on the consumption of liquid hydrogen produced by the liquefier 7 and to predict, from this data, a future filling rate of the buffer storage 9 in a future time interval, for example between one and twenty-four hours. The installation 1 can be configured to modify the cold power and / or liquefaction capacity of the liquefier 7 as a function of the future filling rate of the buffer storage 9 determined by the determining member 3.

[0065] According to this predictive approach, the operation of the liquefier 7 can be set as a function of the filling rate of the buffer storage 9 in a determined future, for example in 12 hours. The filling state of the buffer storage 9 can be calculated for example based on the production of hydrogen by the electrolyser in the next 12 hours by estimating the future production using different parameters, for example, the weather or any other forecasting and / or historical method.

[0066] The amount of hydrogen available can be calculated from the available electricity and the efficiency of the electrolyser and the compression of this hydrogen produced by the electrolyser.

[0067] Similarly, the consumption of gaseous hydrogen by downstream user units can be estimated. For example, the quantity of liquefied hydrogen consumed (and / or used for the production of ammonia or methanol) can be calculated based on a current load level.

[0068] The installation 1 can for example be controlled in the following way.

[0069] If the filling rate of the buffer storage 9 in a predefined future (for example 12 hours) is greater than a maximum threshold (for example 100% or more), the cold power and / or the liquefaction capacity of the liquefier 7 is increased (in advance). A new prediction / simulation can be carried out with these new operating conditions.

[0070] On the other hand, if the filling rate of the buffer storage 9 in a predefined future (e.g. 12h) is lower than a minimum threshold (e.g. 0%), the cooling power and / or the liquefaction capacity of liquefier 7 is reduced (in advance). A new prediction / simulation can be carried out with these new operating conditions.

[0071] In other cases, the filling rate of the buffer storage 9 in a predefined future (for example 12h) is in an acceptable range (for example 5-80% for example), the cold power and / or the liquefaction capacity of the current liquefier 7 is unchanged.

[0072] Different cold power and / or liquefaction capacity of the liquefier 7 can be predefined for example 25%, 50%, 75% and 100%. Using such predefined load levels allows for a quick and efficient changeover.

[0073] Similarly, a minimal downtime of the installation 1 can be provided to avoid shutdowns / restarts and limit the impact on critical equipment.

[0074] For example, after stopping the liquefier in particular, a specific time delay can be provided before a new restart, for example 24 hours.

[0075] Furthermore, such a restart may be subject to at least one necessary precondition. For example, a minimal downtime (e.g. 6h) and a sufficient filling rate of the buffer storage 9 (e.g. at least 25% for a future duration, e.g. 12h).

[0076] The following condition may also be provided: the future production of hydrogen by the source 2 is at least a fraction (for example 50%) of the quantity of hydrogen required to operate the installation 1 (for example of cold power and / or the liquefaction capacity of the liquefier 7 at a determined level, for example 25% for a determined future duration, for example 16h or 6h).

[0077] The installation 1 can also operate according to a mixed or hybrid operating mode. That is to say, a prediction of gaseous hydrogen production can be used to control the installation (the operation of the liquefier) ​​but the operating parameters are re-evaluated and modified if necessary on the basis of actual data on the filling of the buffer storage 9. This makes it possible to limit the periods of shutdown.

[0078] For example, a hydrogen production prediction for 6 hours can be made to calculate the available hydrogen and add it to the quantity. A safety reserve (for example 10% of the maximum filling rate) can be subtracted from the quantity available in the buffer storage 9.

[0079] The average value obtained from the quantity of available hydrogen determines the new operation of the liquefier (for example among 25%, 50%, 75%, 100%). Preferably the change of operation is carried out after a time delay (for example 6 hours).

[0080] The invention allows effective adaptation of the installation to cope with fine- interruptions of intermittent energy sources (and therefore of the production of hydrogen to be liquefied).

[0081] Preferably, high load operation of the liquefier (close to maximum power) is only permitted if the filling rate of the buffer storage 9 is sufficient (for example at least 90%).

[0082] Starting from a high or maximum power, if the filling rate of the buffer storage 9 falls below a level (for example 50%), the operation of the liquefier can be reduced (for example to 75%) as long as the filling rate does not rise again (for example above 95%).

[0083] If the installation 1 operates at reduced load (for example minimum) and the filling rate is lower than a level necessary to ensure a determined duration of hydrogen autonomy (for example one hour), the installation can be shut down.

[0084] A restart is only possible, for example, if the following conditions are met: the filling rate is sufficient for operation for a determined duration (for example, 12 hours) at a determined rate (minimal or reduced, for example) and the quantity of hydrogen produced by source 2 predicted for the times to come (next 6 hours, for example) is greater (for example, by 50%) than the quantity necessary for this operation at reduced rate.

[0085] An example of operation may include the following steps: - estimation of hydrogen production in the following hours (for example 12 hours), this estimation can be based on meteorological data and a state or history of electricity production produced by one or more renewable energy sources - measurement or calculation of the filling rate of the buffer storage 9.

Claims

Claims

1. Liquefied hydrogen production plant comprising a gaseous hydrogen generator (2), for example an electrolyzer (2), configured to produce gaseous hydrogen, a liquefier (7), a supply line (6) connecting a gaseous hydrogen outlet of the gaseous hydrogen generator (2) to an inlet of the liquefier (7), the liquefier (7) comprising a refrigerator (8) with a cycle circuit (18) configured to supply cold power and cool the gaseous hydrogen from the supply line (6) for liquefaction thereof, the plant (1) comprising a buffer storage (9) configured to store the compressed gaseous hydrogen between the gaseous hydrogen generator (2) and the liquefier (7), the liquefier (7) being configured to supply cold power and / or the liquefaction capacity modifiable between at least two levels (NI, N2),the installation (1) comprising a member (3) for determining the filling rate of the buffer storage (9), the installation (1) being configured to modify the cold power and / or liquefaction capacity of the liquefier (7) as a function of the filling rate of the buffer storage (9) determined by the determining member (3).,

2. Installation according to the preceding claim, characterized in that the member (3) for determining the filling rate of the buffer storage (9) is configured to determine the filling rate of the buffer storage (9) from among several predefined filling rates and in that the installation (1) is configured to establish the cold power and / or the liquefaction capacity (7) at determined levels corresponding respectively to the predefined filling rates of the buffer storage (9).

3. Installation according to any one of the preceding claims, characterized in that the installation (1) is configured to relatively reduce the cold power and / or the liquefaction capacity of the liquefier (7) when the filling rate of the buffer storage (9) decreases.

4. Installation according to any one of the preceding claims, characterized in that the installation (1) is configured to relatively increase the cold power and / or the liquefaction capacity of the liquefier (7) when the filling rate of the buffer storage (9) increases.

5. Installation according to any one of the preceding claims, characterized in that it is configured to modify the cold power and / or the liquefaction capacity of the liquefier (7) as a function of the filling rate of the buffer storage (9) determined by the determination member (3) after a determined time delay, for example between one and ten hours.

6. Installation according to any one of the preceding claims, characterized in that the member (3) for determining the filling rate of the buffer storage (9) comprises a pressure sensor.

7. Installation according to the preceding claim, characterized in that the pressure sensor (3) is configured to measure the pressure in the buffer storage (9) and / or in a pipe connected to an outlet of the buffer storage (9).

8. Installation according to any one of the preceding claims, characterized in that the liquefier (7) comprises a refrigerator (8) with a cycle circuit (18) in which a cycle gas flow rate is subjected to a determined thermodynamic cycle, the installation (1) being configured to modify the cooling power and / or liquefaction capacity of the liquefier (7) by modifying the flow rate and / or the quantity of cycle gas in the cycle circuit (18).

9. Installation according to the preceding claim, characterized in that it is configured to reduce the cold power and / or liquefaction capacity of the liquefier (7) by reducing the flow rate and / or the quantity of cycle gas in the cycle circuit (18) via at least one of: a cycle gas discharge pipe to the supply pipe (6), a cycle gas discharge pipe to a discharge zone, a member for liquefying at least part of the cycle gas in the cycle circuit (18).

10. Installation according to any one of the preceding claims, characterized in that the liquefier (7) comprises a refrigerator (8) with a cycle circuit (18) in which a cycle gas flow is subjected to a determined thermodynamic cycle comprising a compression (80) and an expansion, the installation (1) being configured to modify the cold power and / or liquefaction capacity of the liquefier (7) by modifying the compression pressure level (80) of the cycle gas in the cycle circuit (18).

11. Installation according to any one of the preceding claims, characterized in that the liquefier comprises several refrigerators (8) with independent cycle circuits (18) each configured to provide respective cold power to cool the gaseous hydrogen in the supply line (6) for its liquefaction and in that the installation (1) is configured to modify the cold power and / or liquefaction capacity of the liquefier (7) by modifying in a differentiated manner the cold power and / or liquefaction capacity of the different refrigerators (8).

12. Installation according to any one of the preceding claims, characterized in that the member (3) for determining the filling rate of the buffer storage (9) comprises a programmable electronic member (4) for storing and processing data comprising a microprocessor, the member (3) for determining the filling rate being configured to receive operating data from the gaseous hydrogen generator (2) and for and / or data on the consumption of liquid hydrogen produced by the liquefier (7) and to predict, from these data, a future filling rate of the buffer storage (9) in a future time interval, for example between one and twenty-four hours, the installation (1) being configured to modify the cold power and / or liquefaction capacity of the liquefier (7) as a function of the future filling rate of the buffer storage (9) determined by the determining member (3).

13. Installation according to the preceding claim, characterized in that the hydrogen gas generator (2) comprises an intermittent electrical power supply provided by a renewable energy source, for example solar, and in that the member (3) for determining the filling rate is configured to receive weather forecast data and to predict, also from this data, the future filling rate of the buffer storage (9).

14. Method for producing liquefied hydrogen using an installation according to any one of the preceding claims comprising the following steps: - determining the filling rate of the buffer storage (9), - regulating the cold power and / or liquefaction capacity of the liquefier (7) as a function of the filling rate of the determined buffer storage (9).

15. Method according to the preceding claim, characterized in that the determination of the filling rate of the buffer storage (9) is measured, for example via a pressure measurement and / or estimated and / or predicted at from operating data of the installation among: the hydrogen production capacity per generator (2) of gaseous hydrogen, a history of the hydrogen production capacity per generator (2) of gaseous hydrogen, meteorological data, current or future consumption of liquid hydrogen produced by the liquefier (7).

16. Method according to any one of claims 14 or 15, characterized in that the step of regulating the cold power and / or liquefaction capacity of the liquefier (7) comprises a modification of the cold power and / or liquefaction capacity of the liquefier (7) which is carried out in response to a change in the filling rate of the buffer storage (9), the modification of the cold power and / or liquefaction capacity being carried out concomitantly and / or in advance and / or after the change in the filling rate of the determined buffer storage (9).

17. Method according to any one of claims 14 to 16, characterized in that the liquefier (7) comprises a refrigerator (8) with a cycle circuit (18) in which a cycle gas flow rate is subjected to a determined thermodynamic cycle, the step of regulating the cooling power and / or the liquefaction capacity of the liquefier (7) comprising at least one of: a modification of the flow rate and / or the quantity of cycle gas in the cycle circuit (18), for example a discharge of cycle gas outside the cycle circuit (18), a reduction of the quantity of gas in the cycle circuit (18) by partial liquefaction of the cycle gas in a separator pot, a modification of the compression pressure (80) of the cycle gas in the cycle circuit (18).

18. Method according to any one of claims 14 to 17, comprising a step of shutting down the installation in which the liquefier (7) is shut down, followed by a step of restarting the installation (1) and the liquefier (7), the method comprising, after restarting and before a step of regulating the cold power and / or liquefaction capacity of the liquefier (7), a determined time delay, for example between two and twelve hours, and / or a time delay as long as the filling rate of the buffer storage (9) does not reach a determined threshold.

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