Method and system for producing hydrogen from a heat source, and plant comprising such a system

Abstract

The invention relates to a method for producing hydrogen by steam electrolysis, using the heat from a hot effluent (102) discharged by an industrial plant, the method comprising the following steps: - heat exchange, in a heat exchanger (106), between the hot effluent (102) and a flow of water (104) in order to produce a first flow of steam (108), - cogeneration of electricity (118) and a second flow of steam (116) by a cogeneration unit (110) supplied with the first flow of steam (108), and - electrolysis of at least part of the second flow of steam (116) in an electrolysis unit (120) powered by the electricity (118), in order to produce a hydrogen flow and an oxygen-rich flow. The invention further relates to a system (100) implementing such a method and to a plant implementing such a system.

Description

Method and system for producing hydrogen from a heat source, and installation comprising such a system

[0001] The present invention relates to a method and system for producing hydrogen by high-temperature electrolysis of water vapor. It also relates to an industrial installation comprising such a system.

[0002] The field of the invention is generally the field of the production of hydrogen by high-temperature electrolysis of water vapor, and in particular in a solid oxide electrolyzer operating at high temperature. State of the art

[0003] There are currently various techniques for producing hydrogen. One of these techniques is the electrolysis of water vapor in a solid oxide electrolyzer (SOEL). In short, water is heated to obtain water vapor at a temperature above 150°C. The water vapor is introduced into an electrolyzer maintained at a temperature between 700°C and 850°C and supplied with electric current to decompose the water vapor molecule H2O into molecules of H2 and O2 so as to obtain, at the outlet of the electrolyzer, a flow of hydrogen H2 and oxygen O2 from a given flow of water vapor at the inlet of the electrolyzer.

[0004] This solution requires an external energy input, on the one hand to obtain the water vapor at the desired temperature and on the other hand to supply the electrolyzer with current so as to break the H2O molecule. This degrades the overall efficiency of hydrogen production.

[0005] An aim of the present invention is to remedy at least one of the drawbacks of the state of the art.

[0006] Another aim of the invention is to propose a solution for producing hydrogen by electrolysis of water vapor having improved overall efficiency.

[0007] The invention proposes to achieve at least one of the aforementioned aims by a method for producing hydrogen by electrolysis of water vapor, using the heat of a hot effluent discharged by an industrial installation, said method comprising the following steps: heat exchange, in a heat exchanger, between said hot effluent and a flow of water to produce a first flow of water vapor, cogeneration of electricity and a second flow of water vapor by a cogeneration unit powered by said first flow of water vapor, and electrolysis of at least a portion of said second flow of water vapor in an electrolysis unit powered by said electricity, to produce a flow of hydrogen and an oxygen-rich flow.

[0008] Thus, in a conventional manner, the method according to the invention proposes to produce hydrogen from a flow of water vapor introduced into a water vapor electrolysis unit supplied with an electric current.

[0009] In an innovative manner, the invention proposes to cogenerate on the one hand the water vapor introduced into the electrolysis unit and on the other hand the current supplying said electrolysis unit, from a hot effluent discharged by an industrial installation, and therefore already existing. Thus, it is not necessary to provide an additional energy source to produce water vapor or a dedicated current source to supply the electrolysis unit.

[0010] In other words, the invention makes it possible to produce hydrogen by recovering the heat rejected by an industrial site. When the temperature of the hot effluent rejected by the industrial installation is sufficiently high, the invention makes it possible to generate hydrogen, in a completely autonomous manner, without requiring an external electrical source or an external source of water vapor.

[0011] Therefore, the invention allows hydrogen production with higher overall efficiency than current solutions.

[0012] In this application, "hot effluent" means a gaseous effluent or a liquid effluent discharged by an industrial installation. For example, the hot effluent may be a hot gaseous effluent, such as water vapor, combustion fumes, hot air, discharged by a nuclear site, a cement production site, a metallurgical site, etc. According to another example, the hot effluent may be a hot liquid effluent, such as oil or hot water produced by an industrial site.

[0013] According to examples of implementation, the hot effluent discharged can have a temperature of the order of 150°C to 900°C.

[0014] According to non-limiting embodiments, the second flow of water vapor may have a pressure of between 1.5 bara and 3.5 bara.

[0015] According to non-limiting embodiments, the second flow of water vapor has a temperature between 115°C and 750°C.

[0016] According to embodiments, the method according to the invention may comprise a step of preheating the water flow by a portion of the second water vapor flow generated by the cogeneration unit.

[0017] In this case, a part of the second stream of water vapor generated by the cogeneration unit is sent to the electrolysis unit and another part of said second stream of water vapor generated by the cogeneration unit is used in a heat exchanger, or in a deaerator, to preheat the stream of water.

[0018] According to a non-limiting example embodiment, the water flow can be preheated to a temperature between 105°C and 125°C.

[0019] According to non-limiting embodiments, the method according to the invention may comprise a generation, by the cogeneration unit, of a third flow of water vapor, the pressure of which is lower than or equal to that of the second flow of water vapor, said method further comprising a step of condensation, in a condenser, of said third flow of water vapor to produce a flow of water.

[0020] The third steam flow can have a pressure between 0.05 bara and 0.5 bara, and a steam content between 0.85 and 0.95.

[0021] Thus, in these embodiments, there are two streams of water vapor leaving the cogeneration unit: the second stream of water vapor leaving the cogeneration unit, part or all of which is sent to the electrolysis unit, and a third stream of water vapor sent to the condenser to produce water.

[0022] This embodiment makes it possible to adjust the quantity of water vapor sent to the electrolysis unit, while recovering the water vapor not sent to the electrolysis unit in the system according to the invention.

[0023] According to an advantageous feature, the water flow produced by the condenser can be used to produce the first flow of water vapor.

[0024] Thus, the invention makes it possible to recover this flow of water and not to reject it.

[0025] According to an advantageous characteristic, the condenser can be powered, in part or in full, by the electric current produced by the cogeneration unit during the cogeneration stage.

[0026] Thus, the invention does not require the use of an external electrical source to power the condenser.

[0027] According to embodiments, the method according to the invention may comprise a step of deaeration, in a deaerator, of the water flow upstream of the heat exchanger.

[0028] This step removes air from the water stream before it is supplied to the heat exchanger.

[0029] According to embodiments, the method according to the invention may comprise a step of increasing the pressure of the water flow upstream of the heat exchanger. This step makes it possible to produce the first steam flow at the expected pressure at the inlet of the cogeneration turbine.

[0030] Thus, the heat exchanger receives a flow of water which is already compressed. This flow of water is then heated in said heat exchanger to be transformed into the first flow of water vapor: this first flow of water vapor is then at a high pressure and temperature to then supply the cogeneration unit to produce an electric current and the second flow of water vapor, part or all of which is supplied to the electrolysis unit.

[0031] According to an exemplary embodiment, the water flow can be compressed to a pressure between 12 bara and 110 bara.

[0032] According to embodiments, the water flow may be compressed by a compression device which may be a pump.

[0033] According to embodiments, the water flow compression device can be powered by a portion of the electricity generated by the cogeneration unit.

[0034] Thus, the invention does not require the use of an external electrical source to power the compression device.

[0035] According to embodiments, the method according to the invention may further comprise storage of at least part of the electricity produced by the cogeneration unit.

[0036] Indeed, when the electricity generated by the cogeneration unit is in excess, it can be stored in a storage means for later use, for example in the system implementing the present invention. This stored electricity can be used for example to power one or more devices used for implementing the method according to the invention when the heat of the gaseous effluent decreases so that the cogeneration unit generates less electricity, or when the demand for hydrogen production increases, and more generally to balance the production of hydrogen and / or adapt to variations.

[0037] The electrical storage means can be of any type, such as for example one or more rechargeable batteries.

[0038] According to embodiments, the method according to the invention may further comprise storage of at least part of the heat from the hot effluent upstream of the heat exchanger.

[0039] Indeed, when the heat of the hot effluent discharged by the industrial installation is greater than that necessary for the production of the first stream of water vapor, at least part of the excess heat can be stored in a heat storage means for later use, for example in the system implementing the present invention. This stored excess heat can be used for example to supply the process according to the invention when the heat of the gaseous effluent decreases, or when the demand for hydrogen production increases, and more generally to balance the production of hydrogen and / or cope with variations.

[0040] The thermal storage medium may be of any type, such as, for example, an insulated tank of heat transfer fluid heated by a heat exchanger. Such a heat transfer fluid may, for example, be oil or any other fluid.

[0041] According to another aspect of the present invention, there is provided a system for producing hydrogen by electrolysis of water vapor, using the heat of a hot effluent discharged by an industrial installation, said system comprising: at least one heat exchanger for producing a first flow of water vapor by heat exchange between said hot effluent and said flow of water, a unit for cogeneration of electricity on the one hand and a second flow of water vapor on the other hand, from said first flow of water vapor, and at least one unit for electrolysis of at least a portion of said second flow of water vapor, powered by at least a portion of said electricity, to produce a flow of hydrogen.

[0042] The system according to the invention has the same advantages as those described above with reference to the method according to the invention and which will not be repeated here for the sake of brevity.

[0043] According to embodiments, the cogeneration unit may comprise at least one steam turbine coupled to at least one electric generator.

[0044] The steam turbine receives the first pressurized and very hot gas stream to turn the turbine, which in turn drives the generator to produce electricity. The steam turbine provides the second steam stream whose pressure has been reduced, for example to a pressure between 1.5 bara and 3.5 bara and a temperature between 115°C and 160°C.

[0045] As indicated above with reference to the method according to the invention, according to embodiments, the cogeneration unit, and in particular the steam turbine, can provide at the output a third steam flow whose pressure has been reduced even more, compared to the second water vapor flow.

[0046] According to exemplary embodiments, the third flow of water vapor may for example be at a pressure between 0.05 bara and 0.5 bara and at a temperature between 30°C and 80°C, for a vapor content of less than 0.95.

[0047] According to embodiments, the system according to the invention may further comprise a condenser for producing a water stream by condensation of the third water vapor stream.

[0048] According to an advantageous characteristic, the water flow produced by the condenser can be used to produce, at least in part, the first flow of water vapor.

[0049] According to an advantageous characteristic, the condenser can be powered, in part or in full, by the electric current produced by the cogeneration unit.

[0050] According to embodiments, the electrolysis unit may comprise at least one high-temperature water vapor electrolyzer, for example an electrolyzer operating, i.e. carrying out electrolysis of water vapor, at a temperature between 700°C and 850°C.

[0051] According to embodiments, the electrolysis unit may comprise at least one solid oxide electrolyzer.

[0052] In particular, the electrolysis unit may comprise several solid oxide electrolysers arranged in series.

[0053] At least one electrolyzer may comprise one or more electrolysis modules, each comprising at least one stack of solid oxide electrolysis cells.

[0054] According to embodiments, the system according to the invention may further comprise at least one deaerator for deaerating the water upstream of the heat exchanger.

[0055] According to embodiments, the system according to the invention may further comprise a compression device for increasing the pressure of the water flow upstream of the heat exchanger.

[0056] According to an exemplary embodiment, the water flow can be compressed to a pressure between 12 bara and 110 bara.

[0057] According to embodiments, the compression device may be a pump, or any other compression device.

[0058] According to advantageous embodiments, the water flow compression device can be supplied with electricity by part of the electricity generated by the cogeneration unit.

[0059] Of course, the system according to the invention may comprise, in terms of technical means, any combination of one or more of the characteristics described above with reference to the method according to the invention, and which are not all repeated in detail below, for the sake of conciseness.

[0060] In particular, the system according to the invention may comprise: an electrical storage means for storing part of the electricity generated by the cogeneration unit, and / or a thermal storage means for storing part of the heat from the hot effluent, in particular arranged upstream of the exchanger.

[0061] Such storage means make it possible to cope with: a fluctuation / variation in the heat and / or the quantity of hot effluent discharged by the industrial installation; and / or a fluctuation / variation in the demand for hydrogen produced in the electrolysis unit. Thus, it is possible to smooth and balance the operation of the system according to the invention when such fluctuations / variations occur.

[0062] According to another aspect of the present invention, there is provided an installation comprising:an industrial installation producing a hot effluent, anda hydrogen production system according to the invention coupled to said industrial installation, and using said hot effluent to produce hydrogen.

[0063] The industrial facility can be of any type, such as a nuclear facility, a metallurgical facility, a cement plant, a steel mill, a chemical production facility, a waste treatment facility, a recycling facility, etc.

[0064] Preferably, the hydrogen production system is located on the same site as the industrial facility. Description of figures and embodiments

[0065] Other advantages and characteristics will appear on examining the detailed description of non-limiting embodiments, and the appended drawings in which: FIGURES 1-3 are schematic representations of three non-limiting exemplary embodiments of a system according to the invention; and is a schematic representation of a non-limiting exemplary embodiment of an installation according to the invention.

[0066] It is understood that the embodiments which will be described below are in no way limiting. In particular, it is possible to imagine variants of the invention comprising only a selection of characteristics described below isolated from the other characteristics described, if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention compared to the state of the prior art. This selection includes at least one preferably functional characteristic without structural details, or with only part of the structural details if it is this part which is only sufficient to confer a technical advantage or to differentiate the invention compared to the state of the prior art.

[0067] In particular, all the variants and embodiments described can be combined with each other if there is no technical obstacle to this combination.

[0068] In the figures and in the rest of the description, the elements common to several figures retain the same reference.

[0069] This is a schematic representation of a non-limiting exemplary embodiment of a system according to the present invention.

[0070] The system 100 may be used to produce hydrogen using a hot effluent 102 discharged from an industrial site or facility, and a water stream 104.

[0071] The hot effluent 102 may have a temperature between 150°C and 900°C.

[0072] The hot effluent 102 may be gaseous or liquid.

[0073] The hot effluent 102 may be discharged from an industrial facility of any type, such as, for example, a cement plant, a steel mill, a nuclear facility, a facility producing chemicals, a waste treatment facility, etc.

[0074] The system 100 comprises a heat exchanger 106 in which a heat exchange is carried out between the hot effluent 102 and the water flow 104. This heat exchanger can be of any type, and in particular an economizer, a vaporizer, etc. Preferably, the heat exchanger is selected and arranged so as to maximize the heat exchange between the hot effluent 102 and the water flow 104. Thus, most, or even almost all, of the heat from the hot effluent is recovered and transferred to the water flow 104.

[0075] At the outlet of the heat exchanger 106, a first flow 108 of water vapor is obtained.

[0076] According to embodiments, the first stream of water vapor 108 has a temperature between 150°C and 750°C.

[0077] According to embodiments, the first flow of water vapor 108 is at a pressure between 12 and 110 bara.

[0078] The first stream of water vapor 108 is supplied to a cogeneration unit 110. The cogeneration unit 110 may be of any type. According to a non-limiting exemplary embodiment, the cogeneration unit 110 is formed by a steam turbine 112 coupled to a generator 114.

[0079] The cogeneration unit 110 makes it possible to generate, from the first flow of water vapor 108: on the one hand a second flow of water vapor 116, and on the other hand an electric current 118.

[0080] In particular, in the case where the cogeneration unit 110 comprises a steam turbine 112 and a generator 114, the first stream of water vapor 108 drives the steam turbine 112, which, in turn, drives a generator 114.

[0081] The second flow of water vapor 116 supplied at the outlet of the cogeneration unit has a pressure lower than that of the first flow of water vapor 108. According to a non-limiting example, the second flow of water vapor has a pressure of between 1.5 bara and 3.5 bara.

[0082] The second water vapor flow 116 may be at a temperature lower than or equal to that of the first water vapor flow 108. According to a non-limiting example, the second water vapor flow has a temperature between 115°C and 750°C.

[0083] At least a portion, or all, of the second steam stream 116 provided by the cogeneration unit 110 is used to power an electrolysis unit 120. Optionally, a portion of the second steam stream may be used to reheat the water stream 104, as described later.

[0084] The electrical power supplied by the cogeneration unit 110, and in particular by the generator 114, varies depending on the quantity and pressure of the first flow of water vapor 108, as well as the characteristics of the cogeneration unit 110.

[0085] At least a portion, or all, of the electrical current 118 provided by the cogeneration unit 110 may be used to power an electrolysis unit 120. Optionally, a portion of the electrical current 118 may be used to power one or more components of the system 100, as described later.

[0086] The system 100 further comprises a device 122 for compressing the water flow 104 before it is supplied to the heat exchanger 106. This compression device 122 may be of any type. According to a non-limiting exemplary embodiment, the compression device 122 is a pump driven by an electric motor.

[0087] The compression device 122 has the function of increasing the pressure of the water flow 104 supplied to the heat exchanger. According to an exemplary embodiment, the compression device 122 is sized / configured to obtain a water flow having a pressure between 12 bara and 110 bara.

[0088] Optionally, the compression device 122, for example the electric motor actuating the pump, can be powered by part of the current 118 supplied by the cogeneration unit 10. Of course, alternatively, the compression device 122 can be powered by an external electrical source, when the current generated by the cogeneration unit 110 is not sufficient.

[0089] Optionally, the system 100 may further include a deaerator 124, or degasser, for removing oxygen or other gases dissolved in the water stream 104.

[0090] In the example shown, the deaerator 124 is arranged upstream of the compression device 122.

[0091] Optionally, a portion 126 of the second water vapor stream 116 may be used to preheat the water stream 104.

[0092] For example, a heat exchange can be carried out, in a heat exchanger, between the portion 126 of the second water vapor flow 116 and the water flow 104 to preheat said water flow 104.

[0093] In the example shown, the portion 126 of the second water vapor flow 116 is injected into the deaerator 124 where this portion 126 of water vapor mixes with the water flow 104 and therefore preheats said water flow 104.

[0094] Optionally, the cogeneration unit 110, and in particular the steam turbine 112, can provide at the output a third flow of water vapor 128, the pressure of which is lower than that of the second flow of water vapor 116. For example, the third flow of water vapor 128 can have a pressure of between 0.05 bara and 0.5 bara, for a steam content which can be between 0.85 and 0.95.

[0095] This third stream of water vapor 128 can be introduced into a condenser 130 to be transformed into water.

[0096] This condenser 130 can optionally be powered by part of the current 118 generated by the cogeneration unit 110. Of course, alternatively, the condenser 130 can be powered by an external electrical source.

[0097] Some or all of the water obtained at the outlet of the condenser 130 can be reused in the system 100, to form at least part of the water flow 104 supplied to the heat exchanger 106. In the non-limiting example shown in FIGURE 1, all of the water obtained at the outlet of the condenser 130 is introduced into the deaerator 124 to be added to the water flow 104. Thus, the water flow supplied to the heat exchanger 106 comprises the water flow 104, and possibly: the water recovered at the outlet of the condenser 130, and / or the water coming from the portion 126 of the second water vapor flow 116.

[0098] Optionally, the system 100 may comprise a means 132 for storing at least part of the electricity 118 produced by the cogeneration unit 110. Such a storage means 132 may for example comprise one or more rechargeable batteries.

[0099] Thus, the excess electricity 118 generated can be stored in the storage means 132 for subsequent use, for example in the system 100. Such storage of electricity makes it possible to smooth out any variations: in the quantity of electricity generated by the cogeneration unit 110; and / or in the quantity of electricity consumed by the system 100, and in particular by the electrolysis unit 120, in particular to adapt to a variation in the quantity of hydrogen to be produced.

[0100] In the example shown in the, the electricity storage means 132 is positioned between the cogeneration unit 110 and the electrolysis unit 120. Of course, this example is not limiting and the electricity storage means can be positioned elsewhere in the system 100.

[0101] Optionally, the system 100 may comprise a means 134 for storing at least a portion of the heat from the hot effluent 102.

[0102] Indeed, when the heat of the hot effluent 102 discharged by the industrial installation is greater than that necessary for that used in the system 100, at least a portion of the excess heat can be stored in the heat storage means 134, for subsequent use, for example in the system 100. This stored excess heat can be used for example to supply the system 100 when the heat of the hot effluent 102 decreases, or when the demand for hydrogen production increases, and more generally to balance the production of hydrogen.

[0103] The thermal storage means 134 may be of any type, such as for example a reservoir of heat transfer fluid heated by a heat exchanger. Such a heat transfer fluid may for example be oil or any other fluid.

[0104] In the example shown in the, the heat storage means 134 is positioned upstream of the heat exchanger 106. Of course, this example is not limiting and the heat storage means 134 can be positioned elsewhere in the system, for example upstream, or downstream, of the cogeneration unit 120.

[0105] The electrolysis unit 120 may comprise at least one solid oxide electrolyser, SOEL, in particular a SOEL operating at high temperature, for example at a temperature between 700°C and 850°C. Preferably, the electrolysis unit 120 comprises several solid oxide electrolysers arranged in series.

[0106] The electrolysis unit 120 takes as input: part or all of the second stream of water vapor 116, and part or all of the generated electric current 118; to produce hydrogen by electrolysis of the water vapor.

[0107] In the example shown in the, the electrolysis unit 120 takes as input a portion 136 of the second stream of water vapor 116, and a portion 138 of the electric current. The water vapor is subjected to an electrolysis reaction with the current 138, breaking the water vapor molecule to produce, at the output: a first output stream enriched in, or consisting of, hydrogen in the form of dihydrogen, H2, and a second output stream enriched in, or consisting of, oxygen in the form of dioxygen, O2,

[0108] Optionally, as shown in the, the electrolysis unit 120 may take an air flow as an inlet, in particular to balance the pressure within the electrolyser(s). In this case, the second outlet flow may further comprise nitrogen and possibly other components found in the air flow given at the inlet of the electrolysis unit 120.

[0109] This is a schematic representation of another non-limiting exemplary embodiment of a system according to the present invention.

[0110] The system 200 may be used to produce hydrogen using a hot effluent 102 discharged from an industrial site or facility, and a water stream 104.

[0111] The system 200 of the includes all the elements of the system 100 of the except the electricity storage element 132 and the heat storage element 134.

[0112] According to an alternative not shown, a system according to the invention may comprise one of the storage elements 132 and 134.

[0113] This is a schematic representation of another non-limiting exemplary embodiment of a system according to the present invention.

[0114] The system 300 may be used to produce hydrogen using a hot effluent 102 discharged from an industrial site or facility, and a water stream 104.

[0115] The system 300 of thecomprises all the elements of the system 200 of the with the exception of the deaerator 124 and the condenser 130. In the system 300, the second stream of water vapor 116 is entirely supplied to the electrolysis unit 120, and the cogeneration unit 110 does not supply a third stream of water vapor.

[0116] According to an alternative not shown, a system according to the invention may comprise the deaerator 124 or the condenser 130.

[0117] This is a schematic representation of a non-limiting example of an installation according to the invention.

[0118] The installation 400 comprises a system 402 according to the invention for producing hydrogen by electrolysis of water vapor. The system 402 may for example be any one of the systems 100, 200 or 300 described above.

[0119] The installation 400 further comprises an industrial installation 404, coupled to the system 402 and providing the hot effluent 102.

[0120] Preferably, the industrial facility 404 and the system 402 are located on the same site or at least in close proximity to each other. Alternatively, the industrial facility 404 and the system 402 may be located on sites remote from each other.

[0121] The industrial installation 404 may be any type of industrial installation discharging a hot effluent, in liquid or gaseous form. According to non-limiting examples, the industrial installation may be a cement plant, a steel mill, a nuclear installation, a facility producing chemical products, a waste treatment facility, etc.

[0122] Of course, the invention is not limited to the examples which have just been described.

Claims

A method for producing hydrogen by electrolysis of water vapor, using the heat of a hot effluent (102) discharged by an industrial installation (404), said method comprising the following steps: heat exchange, in a heat exchanger (106), between said hot effluent (102) and a water flow (104) to produce a first flow of water vapor (108), cogeneration of electricity (118) and a second flow of water vapor (116) by a cogeneration unit (110) powered by said first flow of water vapor (108), and electrolysis of at least a portion of said second flow of water vapor (116) in an electrolysis unit (120) powered by said electricity (118), to produce a flow of hydrogen and an oxygen-rich flow. Method according to the preceding claim, characterized in that it comprises a step of preheating the water flow (104) by a part (126) of the second water vapor flow (116) generated by the cogeneration unit (110). Method according to any one of the preceding claims, characterized in that it comprises a generation, by the cogeneration unit, of a third flow of water vapor, the pressure of which is less than or equal to that of the second flow of water vapor, said method further comprising a step of condensation, in a condenser (130), of said third flow of water vapor to produce a flow of water. Method according to any one of the preceding claims, characterized in that it comprises a step of deaeration, in a deaerator (124), of the water flow (104) upstream of the heat exchanger (106). Method according to any one of the preceding claims, characterized in that it comprises a step of increasing the pressure of the water flow (104) upstream of the heat exchanger (106). Method according to any one of the preceding claims, characterized in that it further comprises storage of at least part of the electricity (118) produced by the cogeneration unit (110). Method according to any one of the preceding claims, characterized in that it further comprises storage of at least part of the heat of the hot effluent (102) upstream of the heat exchanger (106). System (100; 200; 300) for producing hydrogen by electrolysis of water vapor, using the heat of a hot effluent (102) discharged by an industrial installation (404), said system (100; 200; 300) comprising: at least one heat exchanger (106) for producing a first stream of water vapor (108) by heat exchange between said hot effluent (102) and said stream of water (104), a cogeneration unit (110) for the production of electricity (118) on the one hand and a second stream of water vapor (116) on the other hand, from said first stream of water vapor (108), and at least one electrolysis unit (120) for at least a portion of said second stream of water vapor (116), powered by at least a portion of said electricity (118), to produce a stream of hydrogen. System (100;200;300) according to the preceding claim, characterized in that the cogeneration unit (110) comprises at least one steam turbine (112) coupled to at least one electric generator (114). System (100;200;300) according to any one of claims 8 to 10, characterized in that it further comprises a condenser (130) for producing a flow of water by condensation of a third flow of water vapor (128) supplied by the cogeneration unit. System (100;200;300) according to any one of claims 8 or 9, characterized in that the electrolysis unit (120) comprises at least one solid oxide electrolyser. System (100;200;300) according to any one of claims 8 to 11, characterized in that it further comprises at least one deaerator (124) for deaerating the water upstream of the heat exchanger (106). System (100;200;300) according to any one of claims 8 to 12, characterized in that it comprises a compression device (122) for increasing the pressure of the water flow (104) upstream of the heat exchanger (116). Installation (400) comprising:an industrial installation (404) producing a hot effluent (102), anda hydrogen production system (402) according to any one of claims 8 to 13 coupled to said industrial installation (404), and using said hot effluent (102) to produce hydrogen.

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