FUEL CELL ELECTRIC POWER GENERATION SYSTEM USING HYDROGEN

Abstract

SYSTEM FOR PRODUCING ELECTRIC ENERGY BY FUEL CELL USING HYDROGEN The invention relates to a system (2) for producing electrical energy comprising: - a fuel cell (22); - a first dihydrogen circuit (23); - a second air circuit (24); and - a sealed box (21) having a first interface (212) and a second interface (214) and delimiting an internal volume (210) in which the fuel cell is encapsulated, where at least a portion of the first circuit (23) passes through the sealed box at the first interface to power the fuel cell, and where at least a portion of the second air circuit (24) passes through the sealed box at the second interface to power the fuel cell.The implementation of such a sealed box makes it possible to collect dihydrogen leaks to ensure optimal safety of the environment outside the fuel cell by protecting it from any risk of ignition of the dihydrogen volume. Fig. 2.

Description

Title of the invention: FUEL CELL ELECTRIC POWER PRODUCTION SYSTEM USING HYDROGEN Technical field

[0001] The present invention relates to a fuel cell electrical energy production system using hydrogen and to a propulsion system powered by such an energy production system. The invention also relates to an aircraft comprising such a propulsion system. STATE OF THE PRIOR ART

[0002] In order to reduce the pollution caused by the use of kerosene when operating an aircraft, aircraft are being developed whose engines are powered by dihydrogen. More particularly, the dihydrogen is used to power a fuel cell in order to generate an electric current which will in turn run the aircraft engine. In order to simplify the understanding of the description, it is considered that a fuel cell may comprise a plurality of fuel cells. When the dihydrogen is distributed and used in the fuel cell stack, several types of leaks may occur.

[0003] First, leaks of hydrogen internal to the fuel cell may occur. Although these leaks may have a negative impact on the performance of the fuel cell, the hydrogen does not leak out of the fuel cell and therefore does not pose a risk to the environment external to the fuel cell.

[0004] However, other leaks of dihydrogen may present risks to the environment outside the fuel cell. Indeed, dihydrogen may leak outside the fuel cell, for example at the external joints of the fuel cell stack, at the membrane of a cell in the stack which may have a crack or which may be damaged. External leaks of dihydrogen may also occur through junctions, offsets or pores in the piping of the circuit for distributing dihydrogen to the fuel cell.

[0005] Finally, leakage of hydrogen external to the fuel cell can also occur by diffusion of hydrogen through the materials of the fuel cell (this is called molecular movement of hydrogen, or permeation). Such molecular movement can lead to the release of hydrogen outside the fuel cell.

[0006] However, all these leaks external to the fuel cell can lead to an increase in the concentration of dihydrogen in the environment outside the fuel cell and therefore create flammable conditions, which is obviously not satisfactory. Indeed, dihydrogen has a low ignition energy and can therefore ignite easily and quickly if it is in flammable concentrations (generally of the order of 4 to 74% concentration in the air). The fire or explosion of dihydrogen can cause significant damage, in particular to components which would be in the external environment close to the fuel cell, due to the large variations in temperature and pressure which would be generated.

[0007] For safety reasons, and in particular in the event of a leak of dihydrogen into the environment outside the fuel cell, it is necessary to provide a specific arrangement aimed at avoiding the creation of an inflammable mixture around the fuel cell. Statement of the invention

[0008] An object of the present invention is to provide a sealed enclosure for an electrical energy production system comprising a fuel cell which prevents leaks of dihydrogen to the environment outside the fuel cell and which manages these leaks in a simple, controlled and secure manner.

[0009] For this purpose, an electrical energy production system is proposed comprising:

[0010] - a fuel cell;

[0011] - a first circuit for supplying and distributing dihydrogen to said fuel cell fuel;

[0012] - a second circuit for supplying and distributing air to said fuel cell fuel.

[0013] According to the invention, the system comprises a sealed box having a first interface and a second interface and delimiting an internal volume in which said fuel cell is encapsulated, where at least a part of said first hydrogen supply and distribution circuit passes through said sealed box at the first interface to be in fluid communication with said fuel cell, and where at least a part of said second air supply and distribution circuit passes through said sealed box at the second interface to be in fluid communication with said fuel cell.

[0014] The implementation of such a sealed box makes it possible to collect dihydrogen leaks so as to ensure optimal safety of the components and other elements located around the fuel cell. Indeed, the environment outside the fuel cell is thus protected from any risk of ignition of the volume of dihydrogen coming from the fuel cell.

[0015] In addition, such a sealed enclosure protects the fuel cell from the surrounding environment, in particular by protecting the latter from debris or contaminants which could damage it.

[0016] Advantageously, said system further comprises a first housing fixed in a sealed manner with said first interface and a second housing fixed in a sealed manner with said second interface. Said first hydrogen supply and distribution circuit being housed in said first housing and said second air supply and distribution circuit being housed in the second housing.

[0017] According to a particular aspect, the system further comprises a fourth cooling circuit which is in fluid communication with said fuel cell for cooling said fuel cell, said fourth cooling circuit being at least partly encapsulated in said first housing or said second housing.

[0018] According to another particular aspect, the first interface and the second interface extend on either side of said fuel cell.

[0019] According to yet another particular aspect, said watertight box comprises a drainage orifice.

[0020] According to an exemplary embodiment, the system comprises a device for introducing compressed gas into said internal volume of said sealed box, said compressed gas being intended to maintain a pressure in said internal volume greater than the pressures of the different fluids contained in said fuel cell.

[0021] According to another exemplary embodiment, the system comprises a device for filling, with an electrically non-conductive liquid, the internal volume of said sealed box, said liquid creating an inert environment within said sealed box.

[0022] According to a particular aspect of this exemplary embodiment, said electrically non-conductive liquid is under pressure, where the pressure is greater than a pressure of dihydrogen in said fuel cell.

[0023] According to yet another exemplary embodiment, the system comprises a device for ventilating the internal volume of said watertight box.

[0024] According to another exemplary embodiment, the system comprises a device for reducing the pressure in the internal volume of said sealed box, said device being configured to maintain the pressure in said internal volume at a pressure lower than the limit pressure of flammability of dihydrogen.

[0025] The invention also relates to a propulsion system powered by electricity by at least one electrical energy production system as described previously.

[0026] The invention also relates to an aircraft comprising at least one propulsion system as described above. Brief description of the drawings

[0027] The characteristics of the invention mentioned above, as well as others, will appear more clearly on reading the following description of an exemplary embodiment and of these variants, said description being made in relation to the attached drawings, among which:

[0028] [Fig-1] is a top view of an aircraft according to the invention;

[0029] [Fig.2] is a perspective view of an electrical power generation system according to the invention; and

[0030] [Fig.3] is a perspective and partially sectional view of the system of [Fig.2].

[0031] DETAILED DESCRIPTION OF AN EXAMPLE OF EMBODIMENT

[0032] [Fig. 1] shows an aircraft 1 which has a fuselage 11 on either side of which a wing 12 is fixed. Under each wing 12 is fixed at least one propulsion system 13.

[0033] By convention, X is called the longitudinal direction of the aircraft 1, Y the transverse direction of the aircraft 1 which is horizontal when the aircraft 1 is on the ground, and Z the vertical direction or vertical height when the aircraft 1 is on the ground, these three directions X, Y and Z being orthogonal to each other.

[0034] On the other hand, the terms "front" and "rear" are to be considered in relation to a direction of advancement of the aircraft 1 during operation of the propulsion systems 13, this direction being represented schematically by the arrow F.

[0035] In the embodiment of the invention presented here, the propulsion system 13 may take the form of an electric motor comprising a propeller 131 mounted on the motor shaft of the electric motor which is supplied with electricity by a fuel cell. The fuel cell is here supplied with oxygen and dihydrogen in order to produce electricity.

[0036] The aircraft 1 further comprises at least one system 2 for producing electrical energy intended to supply the propulsion systems 13 of the aircraft 1. In [Fig.l], the system 2 is arranged in the wings 12 but it is easily understood that the system 2 could also be located in the engine nacelle, or in another part of the aircraft, such as the fuselage.

[0037] The system 2, illustrated in Figs. 2 and 3, comprises a fuel cell 22 using dihydrogen as fuel. Thus, the system 2 comprises a first circuit 23 for supplying and distributing dihydrogen (preferably in gaseous form) to the fuel cell 22 and a second circuit 24 for supplying and distributing air (preferably dioxygen) to the fuel cell 22. The dihydrogen and the air allow the fuel cell 22 to create electrical energy thanks to the chemical oxidation-reduction reaction which takes place between the anode and the cathode (not illustrated) of the fuel cell 22. Preferably, the system 2 further comprises a third circuit 26 for discharging water to the outside of the fuel cell 22. This water, resulting from the chemical oxidation-reduction reaction of the dihydrogen with the air, is thus discharged from the fuel cell 22 in order to ensure optimal operation of the latter.

[0038] According to the invention, the system 2 comprises a sealed box 21 having a first interface 212 and a second interface 214. The interfaces 212 and 214 are in this example in the form of walls. The box 21 delimits an internal volume 210 in which the fuel cell 22 is encapsulated. At least a portion of the first hydrogen supply and distribution circuit 23 passes through the sealed box 21 at the first interface 212 to be in fluid communication with the fuel cell 22, so as to allow the supply and distribution of hydrogen to the fuel cell 22. In the same way, at least a portion of the second air supply and distribution circuit 24 passes through the sealed box 21 at the second interface 214 to be in fluid communication with the fuel cell 22, so as to allow the supply and distribution of air to the fuel cell 22.The watertight box 21 may have sealing means at the interfaces 212 and 214 at the locations where the first 22 and second 23 circuits pass through in order to ensure perfect sealing of the watertight box 21.

[0039] The implementation of such a sealed box 21 makes it possible to collect a volume of dihydrogen which could possibly leak out of the fuel cell 22, for one of the reasons described previously for example. The sealed box 21, by collecting this volume of dihydrogen, ensures optimal safety of the components and other elements located in the vicinity of the fuel cell 22. Indeed, the environment outside the fuel cell 22 is thus protected from any risk of ignition of the volume of dihydrogen coming from the fuel cell 22.

[0040] In addition, such a sealed box 21 protects the fuel cell 22 from the surrounding environment so as to ensure optimal operation of the fuel cell 22. Thus, the fuel cell 22 is protected from debris or contaminants (particularly liquids) which could damage the fuel cell 22.

[0041] Furthermore, the implementation of the sealed box 21 around the fuel cell 22 makes it possible to protect the latter during maintenance of the system 2, and in particular during assembly, handling or maintenance of the fuel cell 22. The sealed box 21 also provides mechanical support for the stack of the fuel cell 22.

[0042] The interfaces 212 and 214 (as well as the other interfaces described below) also make it easier to connect the systems or accessories necessary for the operation of the fuel cell 22 without impacting the sealing of the sealed box 21.

[0043] More particularly, and as illustrated in [Fig. 3], the system 2 comprises a first housing 230 fixed in a sealed manner with the first interface 212 and a second housing 240 fixed in a sealed manner with the second interface 214. The first hydrogen supply and distribution circuit 23 is housed in the first housing 230 while the second air supply and distribution circuit 24 is housed in the second housing 240.

[0044] Thus, the first 230 and second 240 housings respectively encapsulate the first hydrogen supply and distribution circuit 23 and the second air supply and distribution circuit 24.

[0045] In other words, the first housing 230 makes it possible to encapsulate, preferably in a sealed manner, the first hydrogen supply and distribution circuit 23. In this way, the first housing can, if necessary, collect a volume of hydrogen which could possibly leak out of the first hydrogen supply and distribution circuit 23, thus ensuring optimal safety of the components and other elements located in the vicinity of the fuel cell 22. Indeed, the environment outside the fuel cell 22 is thus protected from any risk of ignition of the volume of hydrogen coming from the fuel cell 22.

[0046] In the same way, the second housing 240 makes it possible to encapsulate, preferably in a sealed manner, the second air supply and distribution circuit 24.

[0047] Consequently, the dihydrogen and the air are supplied at the level of independent, i.e. separate, housings, which makes it possible to limit the risks of creating an inflammable mixture around the fuel cell 22 in the event of a leak of these fluids.

[0048] The regulation devices 234 (such as purge valves, sensors, etc.) of the first 23 and second 24 circuits are preferably encapsulated within the housings 230 and 240 so as to collect fluid leaks that may come from these devices or from their connections with the corresponding circuit. In this way, the safety of the system 2 is optimized.

[0049] In a variant (not illustrated), the regulation devices 234 can be connected directly to the housings 230 and 240 which then have interfaces, preferably sealed, with these devices.

[0050] In order to ensure optimal operation of the fuel cell 22, the system 2 comprises a fourth cooling circuit 27 which is in fluid communication with the fuel cell 22 to cool the fuel cell 22. The fourth cooling circuit 27 is preferably at least partly encapsulated in the first housing 230 or the second housing 240.

[0051] In this way, the coolant is conveyed to the fuel cell by one of the housings 230, 240. Thus, potential coolant leaks in the vicinity of the fuel cell 22 can be collected by the housing in which the fourth cooling circuit 27 is housed (the first housing 230 in this example). The fuel cell 22 is then protected from this potentially contaminating liquid which could damage it, or at the very least reduce its performance.

[0052] Preferably, the first housing 230 comprises a third interface 232 fluidly connecting the first hydrogen supply and distribution circuit 23 to a hydrogen supply source. The third interface 232 therefore has a connection allowing hydrogen to pass through the latter so that hydrogen is supplied to the first hydrogen supply and distribution circuit 23. The third interface may have sealing means in order to ensure perfect sealing of the first housing 230 and thus limit the risks of hydrogen leaks in the vicinity of the fuel cell 22.

[0053] More preferably, the first interface 212 and the second interface 214 extend on either side of the fuel cell 22. In this example, the housings 230 and 240 are arranged on opposite sides, i.e. opposite faces, of the fuel cell 22. Thus, the risk of simultaneous leaks of a volume of dihydrogen and a volume of air in the same volume is limited, which makes it possible to limit the risks of creating an inflammable mixture around the fuel cell 22 in the event of leakage of these fluids.

[0054] In this example, the sealed box 21 comprises a drainage orifice 216, located in the lower part of the sealed box 21, which allows the evacuation of any fluid, and in particular liquid, during maintenance operations of the fuel cell 22. This makes it possible to limit the risks, in particular of overpressure in the sealed box 21, for the maintenance operators. The drainage orifice 216 may further comprise a spring-loaded valve or one that moves according to the internal pressure in the sealed box 21.

[0055] According to an exemplary embodiment, the system 2 comprises a device 32 for introducing compressed gas into the internal volume 210 of the sealed box 21. The compressed gas introduced into the internal volume is intended to maintain a pressure in the internal volume 210 higher than the pressures of the different fluids contained in the fuel cell 22. Generally, the fluids contained in the fuel cell 22 are mainly dihydrogen and air. In this way, the gas pressure in the internal volume 210 prevents the dihydrogen from escaping from the fuel cell. fuel cell 22 so as to maintain an inert environment. In the event of a leak from the fuel cell 22, it is then the compressed gas introduced into the internal volume of the box which will migrate inside the fuel cell 22 to prevent the dihydrogen from escaping from the fuel cell 22.

[0056] Preferably, the gas introduction device 32 is coupled to pressure sensors implemented within the internal volume 210 of the sealed box 21 so as to detect a drop in pressure within the internal volume 210. Such a drop in pressure would then indicate a leak within the fuel cell 22 (translated by a migration of the compressed gas into the fuel cell 22) or a failure of the sealed box 21. Thus, as soon as a drop in pressure within the internal volume 210 is detected, it is possible to stop and / or purge the introduction device 32 before the flammability conditions are reached.

[0057] More preferably, hydrogen concentration sensors are implemented within the internal volume 210 of the sealed box 21 so as to detect variations in the concentration of hydrogen within the internal volume 210 (due for example to diffusion, as described previously). Thus, it is possible to trigger or request the stopping of the supply of hydrogen to the fuel cell 22 before the flammability conditions are reached.

[0058] It is possible to provide that the compressed gas is supplied at a low flow rate making it possible to attenuate the diffusion of dihydrogen from the fuel cell 22 to the sealed box 21, in particular when a determined quantity of compressed gas is allowed to flow through a ventilation outlet (not illustrated) of the sealed box 21.

[0059] The compressed gas introduced by the introduction device 32 into the internal volume 210 may be air or an inert gas, such as nitrogen.

[0060] To do this, the compressed gas introduced into the internal volume 210 can be supplied by a compressed gas cylinder, in particular nitrogen, which is sized to ensure a sufficient supply of compressed gas to allow the supply of hydrogen to the fuel cell to be stopped in the event of a leak from the latter.

[0061] The compressed gas can also be supplied by a compressor which uses ambient air or air from the second air supply and distribution circuit 24 of the system 2.

[0062] Optionally, the stacks of the fuel cell 22 may be surrounded by a sealed barrier, for example in the form of a rubber or polymer sleeve, in order to prevent the penetration of compressed gas into the stacks of the fuel cell 22, and in particular at the anode and the cathode.

[0063] It should be noted that the introduction device 32 can also be implemented for the first housing 230 in which the first hydrogen supply and distribution circuit 23 is housed in order to prevent hydrogen from leaking out of the first circuit 23 for supplying and distributing dihydrogen. In this way, all of the components using dihydrogen are encapsulated and pressurized in order to optimally protect the fuel cell 22.

[0064] The compressed gas introduction device 32 can also be used when the aircraft is powered down in order to prevent leaks of dihydrogen which could remain in the dihydrogen supply system of the fuel cell 22 after power down.

[0065] Furthermore, the introduction device 32 can also be used to purge the internal volume 210 of the box (and possibly the first housing 230 when it implements such a device) when a leak is detected or during maintenance operations.

[0066] According to another exemplary embodiment, the system 2 comprises a device 34 for filling, with an electrically non-conductive liquid, the internal volume 210 of the sealed box 21. The electrically non-conductive liquid filling the internal volume 210 makes it possible to create an inert environment (without gaseous oxygen) within the sealed box 21 in order to limit the risks of creating flammable conditions of the dihydrogen. In this way, the dihydrogen leaking from the fuel cell 22 will flow into the liquid so as to be collected and isolated for subsequent treatment. Indeed, the dihydrogen will move, in view of the difference in density, in the liquid to one or more dihydrogen collection points, arranged in the upper part of the sealed box 21 for example.The volume of dihydrogen present in the internal volume 210 of the watertight box 21 can then be evacuated, for example by means of a single-way valve arranged at the collection points. In a variant, the dihydrogen can be evacuated by a recirculation system (not shown) of the fluids present in the internal volume 210.

[0067] Thus, it is possible to prevent and limit leaks of dihydrogen from the fuel cell 22.

[0068] In a variant, the electrically non-conductive liquid can be maintained at a pressure higher than the pressures of the various fluids (and in particular the pressure of the dihydrogen) contained in the fuel cell 22. This can prevent the dihydrogen from leaking out of the fuel cell 22 or force the fluid (and therefore the dihydrogen) to move towards a collection point and then evacuate it.

[0069] Preferably, the liquid used is electrically non-conductive in order to limit the risks of short circuit associated with the fuel cell 22. It is preferable that the liquid has a low density so as to limit the mass of the system 2. More preferably, the liquid must have a sufficiently low freezing point and a sufficiently high boiling point to cover the temperature range of operation of the fuel cell 22 and thus avoid failures of the system 2.

[0070] Optionally, the liquid used is a refrigerant liquid which therefore also makes it possible to maintain or manage the temperature of the fuel cell 22. In this case, the filling device 34 can be part of a more general liquid cooling system, for example that of the propulsion system 13 of the aircraft 1.

[0071] In a variant, the liquid may come from a separate and independent reservoir.

[0072] According to yet another exemplary embodiment, the system 2 comprises a ventilation device 36 for the internal volume 210 of the sealed box 21. This ventilation device 36 makes it possible to guarantee that the concentration of dihydrogen in the internal volume 210 remains lower than the flammable concentrations of dihydrogen during normal operation.

[0073] In this way, the impact of dihydrogen leaks out of the fuel cell is reduced.

[0074] Preferably, the sealed box 21 also comprises one or more vents 218 each having a mechanism which allows the pressure to be released in the event of high pressure in the sealed box 21, in particular in the event of a failure of the fuel cell 22 resulting in an explosion or a fire, for example. The mechanism may comprise a rupture disc (“frangible dise or burst dise” in English) or a pressure-activated valve, for example.

[0075] Preferably, the ventilation flow rate is sized for normal operation of the fuel cell 22, or to ventilate minor leaks (for example the case of the diffusion of dihydrogen).

[0076] Preferably, dihydrogen concentration sensors are implemented within the internal volume 210 of the sealed box 21 so as to detect variations in the concentration of dihydrogen within the internal volume 210. Thus, it is possible to trigger or request the stopping of the supply of dihydrogen to the fuel cell 22 before the flammability conditions are reached.

[0077] More preferably, a fire detection system can be implemented within the internal volume 210 of the sealed box 21 so as to trigger or request the stopping of the supply of dihydrogen to the fuel cell 22. Such a fire detection system can in particular comprise pressure sensors which make it possible to detect whether an explosion has occurred.

[0078] Preferably, the sealed box 21 is sized to withstand pressure increases that may be caused by the bursting of a dihydrogen supply pipe, a fire, or an explosion in particular, so as to protect the external environment of the sealed box 21. Also, the sealed box 21 is manufactured from materials resistant to dihydrogen fires and have a sufficient resistance to allow the supply of hydrogen to the fuel cell 22 to be stopped before the sealed box 21 is damaged.

[0079] The ventilation device 36 ventilates a gas, which may be air or an inert gas, such as nitrogen.

[0080] Thus, the gas of the ventilation device 36 can be supplied by a gas bottle or by a compressor which uses ambient air or air from the second air supply and distribution circuit 24 of the system 2.

[0081] The gas of the ventilation device 36 may, when it uses ambient air, include a filter and / or a dehumidifier.

[0082] The ventilation device 36 may be substituted or supplemented by fans for operations on the aircraft 1 when it is on the ground.

[0083] According to yet another exemplary embodiment, the system 2 comprises a device 38 for reducing the pressure in the internal volume 210 of the sealed box 21. The device 38 is configured to maintain the absolute pressure in the internal volume 210 at a pressure lower than the flammability limit pressure of the dihydrogen and to evacuate the dihydrogen leaks. To do this, the device 38 may for example comprise a vacuum pump.

[0084] Preferably, the target absolute pressure within the sealed box 21 is approximately 1 mbar.

[0085] More preferably, the vacuum pump can withstand flammable conditions in the event of a hydrogen leak.

[0086] Preferably, the device 38 is coupled to pressure sensors implemented within the internal volume 210 of the sealed box 21 so as to detect a drop in the absolute pressure within the internal volume 210. Such a drop in pressure could indicate that the vacuum condition is deteriorating or is lost so as to trigger or request the stopping of the hydrogen supply to the system.

Claims

Claims

1. System (2) for producing electrical energy comprising: - a fuel cell (22); - a first circuit (23) for supplying and distributing dihydrogen to said fuel cell (22);- a second circuit (24) for supplying and distributing air to said fuel cell (22), characterized in that it comprises a sealed box (21) having a first interface (212) and a second interface (214) and delimiting an internal volume (210) in which said fuel cell (22) is encapsulated, where at least a portion of said first circuit (23) for supplying and distributing dihydrogen passes through said sealed box (21) at the first interface (212) to be in fluid communication with said fuel cell (22), and where at least a portion of said second circuit (24) for supplying and distributing air passes through said sealed box (21) at the second interface (214) to be in fluid communication with said fuel cell (22).;

2. System (2) according to claim 1, characterized in that it comprises a first housing (230) fixed in a sealed manner with said first interface (212) and a second housing (240) fixed in a sealed manner with said second interface (214), and in that said first hydrogen supply and distribution circuit (23) is housed in said first housing (230), and where said second air supply and distribution circuit (24) is housed in the second housing (240).

3. System (2) according to claim 2, characterized in that it further comprises a fourth cooling circuit (27) which is in fluid communication with said fuel cell (22) for cooling said fuel cell (22), said fourth cooling circuit (27) being at least partly encapsulated in said first housing (230) or said second housing (240).

4. System (2) according to any one of claims 1 to 3, characterized in that the first interface (212) and the second interface (214) extend on either side of said fuel cell (22).

5. System (2) according to any one of claims 1 to 4, characterized in that said sealed box (21) comprises a drainage orifice (216).

6. System (2) according to any one of claims 1 to 5, characterized in that it comprises a device (32) for introducing compressed gas into said internal volume (210) of said sealed box (21), said compressed gas being intended to maintain a pressure in said internal volume (210) higher than the pressures of the different fluids contained in the fuel cell (22).

7. System (2) according to any one of claims 1 to 5, characterized in that it comprises a device (34) for filling, with an electrically non-conductive liquid, the internal volume (210) of said sealed box (21), said liquid creating an inert environment within said sealed box (21).

8. System (2) according to claim 7, characterized in that said electrically non-conductive liquid has a pressure greater than a dihydrogen pressure in said fuel cell (22).

9. System (2) according to any one of claims 1 to 5, characterized in that it comprises a device (36) for ventilating the internal volume (210) of said sealed box (21).

10. System (2) according to any one of claims 1 to 5, characterized in that it comprises a device (38) for reducing the pressure in the internal volume (210) of said sealed box (21), said device (38) being configured to maintain the pressure in said internal volume (210) at a pressure lower than the limit pressure of flammability of dihydrogen.

11. System (13) for electric propulsion of an aircraft (1), characterized in that it is supplied with electricity by at least one system (2) for producing electrical energy according to any one of claims 1 to 10.

12. Aircraft (1) comprising at least one electric propulsion system (13) according to claim 11.

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