Water electrolysis system and energy system

Abstract

The invention provides a water electrolysis system and an energy system. A water electrolysis system (10) is provided with: a water electrolysis device (48) having a membrane electrode structure (80) in which an electrolyte membrane (86) is sandwiched between an anode electrode (90) and a cathode electrode (88), the water electrolysis device (48) generating oxygen gas from the anode electrode by supplying water to the cathode electrode and electrolyzing the water; and a water supply device (52) that supplies water generated in conjunction with power generation by the fuel cell stack (16) to the anode electrode. Therefore, the water electrolysis system and the energy system which are more excellent can be provided.

Description

Technical Field

[0001] The present invention relates to a water electrolysis system and an energy system. Background Art

[0002] In recent years, in order to ensure that more people have access to affordable, reliable, sustainable, and advanced energy, technological development related to energy systems that help improve energy efficiency has been ongoing.

[0003] Japanese Patent Application Publication No. 2022-83098 describes an energy system comprising a water electrolysis system, a booster, and a fuel cell. The water electrolysis system includes a water electrolysis device having a membrane electrode structure (MES) formed by sandwiching an electrolyte membrane between an anode electrode and a cathode electrode. The water electrolysis device supplies water to the cathode electrode, electrolyzing the water to generate oxygen gas at the anode electrode. Summary of the Invention

[0004] Looking forward to better water electrolysis systems and energy systems.

[0005] The purpose of the present invention is to solve the above technical problems.

[0006] The first embodiment of the present invention is a water electrolysis system comprising a water electrolysis device and a water supply device, wherein the water electrolysis device comprises a membrane electrode structure (MES) formed by clamping an electrolyte membrane between an anode electrode and a cathode electrode, the water electrolysis device supplies water to the cathode electrode and electrolyzes the water to cause the anode electrode to generate oxygen, and the water supply device supplies water generated by power generation of a fuel cell stack to the anode electrode.

[0007] A second aspect of the present invention is an energy system including the water electrolysis system according to the first aspect and a fuel cell system including the fuel cell stack.

[0008] According to the present invention, a more excellent water electrolysis system and energy system can be provided.

[0009] The above-mentioned objects, features and advantages will be easily understood from the following description of the embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a schematic diagram of the structure of an energy system according to one embodiment of the present invention.

[0011] Figure 2 This is a cross-sectional view of a water electrolysis cell.

[0012] Figure 3It is a block diagram of the control device of the energy system.

[0013] Figure 4 This is a flowchart showing an example of a control method for an energy system. DETAILED DESCRIPTION

[0014] In a water electrolysis device, the anode electrode may be corroded by oxygen generated at the anode electrode. The present invention has been made in view of such a technical problem and provides a water electrolysis system and an energy system capable of suppressing corrosion of the anode electrode.

[0015] Figure 1 This is a schematic diagram of an energy system 12 according to one embodiment of the present invention. Energy system 12 is a circulating renewable energy system. Specifically, energy system 12 combines a fuel cell system 14 and a water electrolysis system 10. The fuel cell system 14 generates electricity and water through an electrochemical reaction between oxygen and hydrogen, while the water electrolysis system 10 generates oxygen and hydrogen by electrolyzing water. In energy system 12, the water electrolysis system 10 uses the water generated by the fuel cell system 14 to generate the oxygen and hydrogen required for the fuel cell system 14 to generate electricity.

[0016] Such an energy system 12 can be installed on the Earth or the surface of the Moon, for example, or can be mounted on an artificial satellite such as the International Space Station (ISS).

[0017] The fuel cell system 14 includes a fuel cell stack 16. The fuel cell stack 16 includes a plurality of power generation cells 18 and a pair of end plates 20. The plurality of power generation cells 18 are stacked one on top of the other. The pair of end plates 20 sandwich the plurality of power generation cells 18 from the stacking direction.

[0018] Detailed illustration of the power generation cell 18 is omitted. The power generation cell 18 comprises a membrane electrode assembly (MEA) and a pair of separators. The MEA is sandwiched between the pair of separators. The MEA comprises an electrolyte membrane, an anode electrode, and a cathode electrode. The power generation cell 18 generates electricity through an electrochemical reaction between hydrogen and oxygen. When power generation cell 18 generates electricity, water is produced at the cathode electrode.

[0019] The fuel cell system 14 further includes a hydrogen tank 22, a hydrogen supply path 24, and a hydrogen exhaust path 26. The hydrogen tank 22 is filled with high-pressure hydrogen. The hydrogen supply path 24 supplies the hydrogen filled in the hydrogen tank 22 to the fuel cell stack 16. An on-off valve 28 is provided in the hydrogen supply path 24. The on-off valve 28 opens and closes the hydrogen supply path 24. Hydrogen off-gas discharged from the fuel cell stack 16 flows through the hydrogen exhaust path 26. The hydrogen off-gas includes unreacted hydrogen that has not reacted in the power generation cell 18.

[0020] The fuel cell system 14 also includes an oxygen tank 30, an oxygen supply path 32, an oxygen exhaust path 34, a gas-liquid separator 36, a circulation path 38, and an oxygen pump 40. The oxygen tank 30 is filled with high-pressure oxygen. The pressure of the oxygen in the oxygen tank 30 is lower than the pressure of the hydrogen in the hydrogen tank 22. The oxygen supply path 32 supplies the oxygen filled in the oxygen tank 30 to the fuel cell stack 16. An on-off valve 42 is provided in the oxygen supply path 32. The on-off valve 42 opens or closes the oxygen supply path 32. The oxygen exhaust gas exhausted from the fuel cell stack 16 circulates in the oxygen exhaust path 34. The oxygen exhaust gas includes unreacted oxygen that has not reacted in the power generation cell 18. In addition, the oxygen exhaust gas includes water (water vapor) generated at the cathode electrode of the power generation cell 18.

[0021] The gas-liquid separator 36 is connected to the oxygen exhaust path 34. The gas-liquid separator 36 separates the oxygen waste gas into gas and liquid. That is, the gas-liquid separator 36 removes water vapor from the oxygen waste gas. The gas-liquid separator 36 has a storage portion 44 for storing water (liquid water) separated from the oxygen waste gas. The circulation flow path 38 connects the gas-liquid separator 36 and the oxygen supply path 32 to each other. The circulation flow path 38 guides the oxygen waste gas from which water vapor has been removed by the gas-liquid separator 36 to the oxygen supply path 32. The oxygen pump 40 is provided in the circulation flow path 38. The oxygen pump 40 transports the oxygen waste gas flowing in the circulation flow path 38 to the oxygen supply path 32.

[0022] The fuel cell system 14 may include components other than the components described above. Specifically, the fuel cell system 14 may include, for example, a cooling device for circulating a cooling medium through the fuel cell stack 16 .

[0023] The water electrolysis system 10 includes a gas-liquid separator 46, a water electrolysis device 48, a pressure-boosting device 50, and a water supply device 52. The gas-liquid separator 46 of the water electrolysis system 10 and the gas-liquid separator 36 of the fuel cell system 14 are connected to each other via a connecting path 54. An on-off valve 56 is provided on the connecting path 54. The on-off valve 56 opens and closes the connecting path 54. Water stored in the storage section 44 of the gas-liquid separator 36 of the fuel cell system 14 is supplied to the gas-liquid separator 46 via the connecting path 54. The gas-liquid separator 46 includes a cathode-side storage section 58 for storing water. The water stored in the cathode-side storage section 58 is supplied to the cathode electrode 88 of the water electrolysis device 48, which will be described later.

[0024] The water electrolysis device 48 generates oxygen and hydrogen by electrolyzing water (pure water). The water electrolysis device 48 is, for example, a solid polymer water electrolysis device. Alternatively, the water electrolysis device 48 may be an alkaline water electrolysis device or a solid oxide water electrolysis device.

[0025] The water electrolysis device 48 includes a water electrolysis stack 60, a water electrolysis power source 62, a water electrolysis supply path 64, a water electrolysis discharge path 66, and an oxygen supply path 68. The water electrolysis stack 60 includes a plurality of water electrolysis cells 70 and a pair of end plates 72. The plurality of water electrolysis cells 70 are stacked one on top of the other. The pair of end plates 72 sandwich the plurality of water electrolysis cells 70 in the stacking direction.

[0026] Figure 2 : is a cross-sectional view of the water electrolysis cell 70. Figure 2 In FIG. 1 , the X direction is the stacking direction of the plurality of water electrolysis cells 70. Figure 2 As shown, in the water electrolysis cell 70, water is supplied to the cathode electrode 88. The water electrolysis cell 70 electrolyzes water to cause the anode electrode 90 to generate oxygen and the cathode electrode 88 to generate hydrogen.

[0027] The water electrolysis cell 70 is a differential pressure type water electrolysis cell, in which the pressure of oxygen in the anode electrode 90 is higher than the pressure of water in the cathode electrode 88. Alternatively, the water electrolysis cell 70 may be an isobaric type water electrolysis cell, in which the pressure of oxygen in the anode electrode 90 is substantially equal to the pressure of water in the cathode electrode 88. In the water electrolysis device 48, for example, the anode electrode 90 can generate oxygen at a pressure of 14.8 MPa.

[0028] In the water electrolysis cell 70, the water supply manifold 74, the water discharge manifold 76, and the oxygen discharge manifold 78 are provided so as to penetrate the water electrolysis cell 70 in the X direction. The water supply manifolds 74 of the multiple water electrolysis cells 70 are connected to each other. The water discharge manifolds 76 of the multiple water electrolysis cells 70 are connected to each other. The oxygen discharge manifolds 78 of the multiple water electrolysis cells 70 are connected to each other.

[0029] The water supply manifold 74 and the water discharge manifold 76 are provided at positions spaced apart from each other on the outer periphery of the water electrolysis cell 70. The oxygen discharge manifold 78 is provided in the center of the water electrolysis cell 70. The oxygen discharge manifold 78 is located between the water supply manifold 74 and the water discharge manifold 76. The water supply manifold 74 supplies water to the cathode electrode 88. The water discharge manifold 76 discharges water flowing through the cathode electrode 88 and hydrogen generated at the cathode electrode 88 to the outside. The oxygen discharge manifold 78 discharges oxygen generated at the anode electrode 90 to the outside.

[0030] The water electrolysis cell 70 includes a membrane electrode structure 80, a pair of separators 82, and a frame member 84. The membrane electrode structure 80 is sandwiched between the pair of separators 82. The frame member 84 is formed into a ring shape so as to surround the membrane electrode structure 80. A sealing member 87 is provided between the frame member 84 and the separator 82 to prevent the fluid (water and hydrogen) from flowing out. Figure 2The separator 82 located in the X1 direction of the membrane electrode assembly 80 in the pair of separators 82 is referred to as the "first separator 82a", and the separator 82 located in the X2 direction of the membrane electrode assembly 80 in the pair of separators 82 is referred to as the "second separator 82b".

[0031] The membrane electrode assembly 80 is formed into a ring shape. The membrane electrode assembly 80 includes an electrolyte membrane 86, a cathode electrode 88, and an anode electrode 90. The electrolyte membrane 86 is sandwiched between the cathode electrode 88 and the anode electrode 90. The electrolyte membrane 86 is an ion exchange membrane. Specifically, the electrolyte membrane 86 is, for example, an anion exchange membrane (AEM). Alternatively, the electrolyte membrane 86 may be a proton exchange membrane (PEM). The electrolyte membrane 86 prevents oxygen generated at the anode electrode 90 from passing to the cathode electrode 88.

[0032] The cathode electrode 88 includes a cathode catalyst layer 92, a protective sheet 94, and a cathode power supply 96. The cathode catalyst layer 92 is bonded to one surface 86a (the surface facing the X1 direction) of the electrolyte membrane 86. The cathode power supply 96 also serves as a gas diffusion layer for supplying water to the cathode catalyst layer 92. The cathode power supply 96 includes a portion formed by a porous member. The protective sheet 94 is disposed between the cathode catalyst layer 92 and the cathode power supply 96. The protective sheet 94 prevents the electrolyte membrane 86 from being damaged by the high-pressure oxygen generated at the anode electrode 90 being pressed against the cathode power supply 96. A plurality of through holes 98 are formed in the protective sheet 94.

[0033] The outer diameter of the anode electrode 90 is smaller than that of the cathode electrode 88. The anode electrode 90 includes an anode catalyst layer 100 and an anode power supply 102. The anode catalyst layer 100 is bonded to the other surface 86b (the surface facing the X2 direction) of the electrolyte membrane 86. The anode power supply 102 also serves as a gas diffusion layer for conducting oxygen generated in the anode catalyst layer 100. The anode power supply 102 includes a portion formed of a porous member.

[0034] A support member 104 is formed between the first separator 82a and the cathode power supply 96 to support the membrane electrode assembly 80. A communication path 106 is formed in the support member 104. The communication path 106 guides water introduced from the water supply passage 74 into the cathode power supply 96. Furthermore, the communication path 106 guides the mixed fluid of water and hydrogen gas in the cathode power supply 96 to the water discharge passage 76.

[0035] A load applying mechanism 108 is provided between the second separator 82b and the anode power supply 102 to apply force to the anode power supply 102 in the X1 direction. The load applying mechanism 108 includes, for example, a leaf spring 110, a leaf spring retaining portion 112, and a conductive sheet 114. An annular member 116 is provided between the second separator 82b and the outer periphery of the electrolyte membrane 86. The annular member 116 is in liquid-tight and air-tight contact with the other surface 86b of the electrolyte membrane 86.

[0036] An annular sealing member 118 is disposed between the annular member 116 and the load applying mechanism 108. The sealing member 118 is in liquid-tight and air-tight contact with the second separator 82b and the electrolyte membrane 86, respectively. A space (anode chamber 120) for accommodating the anode electrode 90 is formed inside the sealing member 118. The load applying mechanism 108 is disposed in the anode chamber 120.

[0037] like Figure 1 As shown, the water electrolysis power supply 62 is a DC power supply. The water electrolysis power supply 62 applies a voltage between the cathode power supply 96 and the anode power supply 102 (see Figure 1 and Figure 2 ).

[0038] The water electrolysis supply path 64 connects the cathode side storage unit 58 and the water electrolysis stack 60. The water electrolysis supply path 64 is connected to the water supply communication hole 74 (see Figure 2 ) is connected. The water electrolysis supply path 64 guides the water stored in the cathode-side storage section 58 to the water electrolysis stack 60. A water pump 122 is provided in the water electrolysis supply path 64. The water pump 122 delivers the water flowing through the water electrolysis supply path 64 to the water electrolysis stack 60.

[0039] The water electrolysis discharge path 66 connects the gas-liquid separator 46 and the water electrolysis stack 60. The water electrolysis discharge path 66 is connected to the water discharge communication hole 76 (see Figure 2 ). The water electrolysis discharge path 66 directs a mixed fluid of hydrogen generated at the cathode electrode 88 of the water electrolysis cell 70 and unelectrolyzed water to the gas-liquid separator 46. The gas-liquid separator 46 separates the mixed fluid introduced from the water electrolysis discharge path 66 into gas and liquid. The water separated from the mixed fluid is stored in the cathode-side storage unit 58.

[0040] The oxygen supply path 68 supplies the oxygen generated in the water electrolysis stack 60 to the fuel cell system 14. The oxygen supply path 68 is connected to the oxygen discharge communication hole 78 (see Figure 2). The oxygen delivery path 68 includes an oxygen outlet path 124, a first branch path 126, and a second branch path 128. The oxygen outlet path 124 is connected to the water electrolysis stack 60. The first branch path 126 and the second branch path 128 branch off from the oxygen outlet path 124. The first branch path 126 is connected to the oxygen tank 30 of the fuel cell system 14. The second branch path 128 is connected to the oxygen supply path 32 of the fuel cell system 14.

[0041] A backpressure valve 130 is provided in the first branch path 126. The backpressure valve 130 opens when the pressure of the oxygen gas extracted from the water electrolysis stack 60 is greater than a predetermined oxygen pressure threshold. The backpressure valve 130 closes when the pressure of the oxygen gas extracted from the water electrolysis stack 60 is less than the oxygen pressure threshold. An on-off valve 132 is provided in the second branch path 128. The on-off valve 132 opens or closes the second branch path 128.

[0042] The water electrolysis device 48 may include components other than the components described above.

[0043] The boosting device 50 includes a boosting stack 134, a boosting power supply 136, a boosting supply path 138, a boosting discharge path 140, and a hydrogen transport path 142. The boosting stack 134 boosts the pressure of the hydrogen generated by the water electrolysis device 48. The boosting stack 134 includes a plurality of boosting cells 144 and a pair of end plates 146. The plurality of boosting cells 144 are stacked one on top of the other. The pair of end plates 146 sandwich the plurality of boosting cells 144 in the stacking direction.

[0044] Detailed illustration of the boost battery 144 is omitted. In the boost battery 144, while supplying humidified hydrogen to the anode electrode, the boost power supply 136 applies a voltage between the anode power supply of the anode electrode and the cathode power supply of the cathode electrode. Accordingly, hydrogen ions are generated at the anode electrode, and the hydrogen ions pass through the electrolyte membrane (ion exchange membrane) of the boost battery 144 and are guided to the cathode electrode. At the cathode electrode, hydrogen gas is generated by combining hydrogen ions. The electrolyte membrane of the boost battery 144 prevents the hydrogen gas generated at the cathode electrode from passing through the anode electrode. In the boost device 50, high-pressure hydrogen gas can be generated at the cathode electrode. In the boost device 50, for example, the hydrogen gas can be pressurized to 70 MPa. That is, the pressure of the hydrogen gas pressurized by the boost device 50 is higher than the pressure of the oxygen gas generated by the water electrolysis device 48.

[0045] The boost supply path 138 connects the gas-liquid separator 46 and the boost stack 134. The boost supply path 138 directs the hydrogen gas, from which water has been removed by the gas-liquid separator 46, to the boost stack 134. A hydrogen pump 147 is provided on the boost supply path 138. The hydrogen pump 147 delivers the hydrogen gas flowing through the boost supply path 138 to the boost stack 134. Furthermore, the hydrogen gas supplied from the boost supply path 138 to the boost stack 134 contains an appropriate amount of water vapor. This water vapor humidifies the electrolyte membrane of the boost cell 144.

[0046] The pressurized discharge path 140 connects the gas-liquid separator 46 and the pressurized stack 134 . The pressurized discharge path 140 guides unreacted hydrogen gas from the pressurized stack 134 to the gas-liquid separator 46 together with water vapor.

[0047] The hydrogen delivery path 142 delivers hydrogen generated at the cathode electrode of the boost cell 144 to the fuel cell system 14. The hydrogen delivery path 142 includes a hydrogen outlet path 148, a first branch path 150, and a second branch path 152. The hydrogen outlet path 148 is connected to the boost stack 134. The first branch path 150 and the second branch path 152 branch off from the hydrogen outlet path 148. The first branch path 150 is connected to the hydrogen storage tank 22 of the fuel cell system 14. The second branch path 152 is connected to the hydrogen supply path 24 of the fuel cell system 14.

[0048] A backpressure valve 154 is provided in the first branch path 150. When the pressure of the hydrogen gas extracted from the booster stack 134 is greater than or equal to a predetermined hydrogen pressure threshold, the backpressure valve 154 opens the first branch path 150. When the pressure of the hydrogen gas extracted from the booster stack 134 is less than the hydrogen pressure threshold, the backpressure valve 154 closes the first branch path 150. An on-off valve 156 is provided in the second branch path 152. The on-off valve 156 opens or closes the second branch path 152.

[0049] The boosting device 50 may include components other than the components described above.

[0050] The water supply device 52 supplies water generated by the fuel cell stack 16 to the anode electrode 90 of the water electrolysis device 48. Furthermore, the pressure inside the anode electrode 90, to which the generated water is supplied, is higher than the pressure inside the cathode electrode 88. The water supply device 52 includes a pressing device 158, a water inlet path 160, a water supply path 162, a hydrogen gas inlet path 164, and a discharge path 166. The pressing device 158 includes a cylindrical portion 168 and a piston 170. The piston 170 is slidably disposed within the cylindrical portion 168 along its inner circumference. The piston 170 divides the interior space of the cylindrical portion 168 into a first chamber 172a and a second chamber 172b. The first chamber 172a is an anode-side storage portion 174 capable of storing water to be supplied to the anode electrode 90 of the water electrolysis cell 70. The second chamber 172b is a pressurized chamber 176 capable of introducing hydrogen gas pressurized by the pressure-boosting device 50.

[0051] The outer circumferential surface of piston 170 is in liquid-tight and air-tight contact with the inner circumferential surface of cylindrical portion 168. An annular groove 178 is formed on the outer circumferential surface of piston 170. An inert gas, such as nitrogen, is enclosed in annular groove 178. This prevents mixing of water in anode-side storage portion 174 and hydrogen in pressurized chamber 176.

[0052] The water inlet path 160 connects the storage section 44 and the barrel 168 of the fuel cell system 14. The water inlet path 160 introduces the water stored in the storage section 44 of the fuel cell system 14 into the anode side storage section 174. In addition, when introducing the water into the anode side storage section 174, it is also possible to pressure-feed it by a pump not shown. In addition, the gas in the pressurization chamber 176 can be discharged through the discharge valve 188 to reduce the pressure in the pressurization chamber 176, thereby moving the piston 170 toward the pressurization chamber 176 to expand the space in the anode side storage section 174 while introducing water. An ion exchange device 180 and an on-off valve 182 are provided on the water inlet path 160. The ion exchange device 180 removes impurities from the water introduced from the storage section 44 of the fuel cell system 14. The on-off valve 182 opens or closes the water inlet path 160.

[0053] The water supply path 162 connects the cylindrical portion 168 and the water electrolysis stack 60. The water supply path 162 is connected to the anode chamber 120 of each water electrolysis cell 70 (see Figure 2 ) is connected. That is, the water supply path 162 can supply the water (pure water) stored in the anode side storage portion 174 to the anode electrode 90 (refer to Figure 2 ) is guided. An on-off valve 184 is provided in the water supply path 162. The on-off valve 184 opens or closes the water supply path 162.

[0054] The hydrogen inlet passage 164 connects the hydrogen transport passage 142 (hydrogen outlet passage 148) and the cylindrical portion 168. The hydrogen inlet passage 164 guides the hydrogen gas flowing through the hydrogen transport passage 142 to the pressurized chamber 176 of the cylindrical portion 168. An on-off valve 186 is provided on the hydrogen inlet passage 164. The on-off valve 186 opens and closes the hydrogen inlet passage 164.

[0055] Discharge path 166 discharges hydrogen gas from pressurized chamber 176 to the outside. Discharge path 166 is provided with a discharge valve 188. Discharge valve 188 opens or closes discharge path 166. Discharge valve 188 opens when the pressure in pressurized chamber 176 exceeds a predetermined pressure threshold. Discharge valve 188 closes when the pressure in pressurized chamber 176 falls below the pressure threshold.

[0056] The water supply device 52 may include components other than the components described above.

[0057] In the water electrolysis system 10, the water supply device 52 and the water electrolysis stack 60 are arranged so that the potential energy of the anode-side storage unit 174 is higher than the potential energy of the anode electrode 90 of the water electrolysis cell 70. Specifically, the height of the anode-side storage unit 174 in the direction of gravity is higher than the height of the water electrolysis cell 70 in the direction of gravity. This allows the water stored in the anode-side storage unit 174 to be directed to the anode electrode 90 of the water electrolysis cell 70 using its potential energy.

[0058] In the following description, the above-mentioned on-off valves 28 , 42 , 56 , 132 , 156 , 182 , 184 , and 186 may be simply referred to as “on-off valves 190 ”.

[0059] Figure 3 FIG. 1 is a block diagram of the control device 194 of the energy system 12. Figure 3 As shown, energy system 12 further includes sensors 192 and a control device 194. Sensors 192 detect various information about energy system 12. Detection signals from sensors 192 are sequentially transmitted to control device 194. Sensors 192 include, for example, a water level sensor for measuring the amount of water in anode-side storage 174. Sensors 192 also include a voltage sensor for measuring the voltage between cathode power supply 96 and anode power supply 102 of water electrolysis cell 70.

[0060] The control device 194 includes a computing unit 196 and a storage unit 198. The computing unit 196 is composed of a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). In other words, the computing unit 196 is composed of processing circuitry.

[0061] The calculation unit 196 includes a control unit 200 , an information acquisition unit 202 , and a determination unit 204 . The control unit 200 , the information acquisition unit 202 , and the determination unit 204 can be realized by the calculation unit 196 executing a program stored in the storage unit 198 .

[0062] Furthermore, at least a portion of the control unit 200, information acquisition unit 202, and determination unit 204 may be implemented using an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array). Furthermore, at least a portion of the control unit 200, information acquisition unit 202, and determination unit 204 may be implemented using an electronic circuit including discrete components.

[0063] Storage unit 198 is composed of volatile memory (not shown) and non-volatile memory (not shown). Examples of volatile memory include RAM (Random Access Memory). Volatile memory serves as working memory for the processor, temporarily storing data required for processing or calculations. Examples of volatile memory include ROM (Read Only Memory) and flash memory. Non-volatile memory serves as a processor for storage, storing programs, tables, maps, and the like. At least a portion of storage unit 198 may be provided in the aforementioned processor, integrated circuit, or the like.

[0064] The control unit 200 is responsible for overall control of the energy system 12. The control unit 200 controls the on-off valve 190, the oxygen pump 40, the water pump 122, the hydrogen pump 147, the water electrolysis power supply 62, and the boost power supply 136. The information acquisition unit 202 acquires information measured by the sensor 192.

[0065] Next, the operation of the energy system 12 will be described. Figure 4 This is a flowchart showing an example of a control method of the energy system 12 .

[0066] like Figure 4 As shown, in step S1, the control unit 200 activates the energy system 12. Specifically, the control unit 200 activates the fuel cell system 14. That is, the control unit 200 controls the on-off valve 42 to open the oxygen supply path 32, and controls the on-off valve 28 to open the hydrogen supply path 24. When the on-off valve 42 is open, the oxygen filled in the oxygen tank 30 is introduced into the fuel cell stack 16 via the oxygen supply path 32. When the on-off valve 28 is open, the hydrogen filled in the hydrogen tank 22 is introduced into the fuel cell stack 16 via the hydrogen supply path 24.

[0067] In the fuel cell stack 16, each power generation cell 18 generates electricity through the electrochemical reaction of oxygen and hydrogen. Unreacted hydrogen that is not used for power generation is discharged to the hydrogen exhaust path 26 as hydrogen waste gas. Unreacted oxygen that is not used for power generation is discharged to the oxygen exhaust path 34 as oxygen waste gas together with water generated along with power generation. The oxygen waste gas discharged to the oxygen exhaust path 34 is separated into gas and liquid by the gas-liquid separator 36. The water (liquid water) separated from the oxygen waste gas is stored in the storage unit 44. In addition, the control unit 200 guides the oxygen waste gas from which water has been removed from the gas-liquid separator 36 to the oxygen supply path 32 by driving the oxygen pump 40.

[0068] Furthermore, the control unit 200 activates the water electrolysis system 10. Specifically, the control unit 200 drives the water pump 122 and controls the water electrolysis power supply 62 to apply a voltage between the cathode power supply 96 and the anode power supply 102 of the water electrolysis cell 70. When the water pump 122 is driven, the water stored in the cathode-side reservoir 58 is supplied to the water supply manifold 74 of the water electrolysis stack 60 via the water electrolysis supply path 64. The water supplied to the water supply manifold 74 is then guided toward the cathode catalyst layer 92 via the communication path 106 of the support member 104, the interior of the cathode power supply 96, and the through-hole 98 of the protective sheet 94.

[0069] When the electrolyte membrane 86 is an anion exchange membrane, hydrogen gas and hydroxide ions are generated by electrolysis of water in the cathode catalyst layer 92. The hydroxide ions pass through the anion exchange membrane and are guided to the anode catalyst layer 100. In the anode catalyst layer 100, the hydroxide ions combine to generate oxygen gas and water.

[0070] When electrolyte membrane 86 is a proton exchange membrane, water directed to cathode catalyst layer 92 passes through the proton exchange membrane and is directed to anode catalyst layer 100. In anode catalyst layer 100, water is electrolyzed to generate oxygen and hydrogen ions. The hydrogen ions pass through the proton exchange membrane and are directed to cathode catalyst layer 92. In cathode catalyst layer 92, the hydrogen ions combine to generate hydrogen gas.

[0071] Oxygen generated in the anode catalyst layer 100 is guided to the oxygen supply path 68 through the oxygen discharge passage 78. Furthermore, in the oxygen supply path 68, the first branch path 126 is closed by the backpressure valve 130, and the second branch path 128 is closed by the on-off valve 132. This allows oxygen to be stored in a closed space, thereby increasing the pressure of the oxygen generated in the water electrolysis stack 60. When the pressure of the oxygen generated in the water electrolysis stack 60 exceeds the oxygen pressure threshold, the backpressure valve 130 opens, and oxygen is filled into the oxygen storage tank 30. Alternatively, the controller 200 can supply the oxygen generated in the water electrolysis stack 60 to the oxygen supply path 32 by opening the on-off valve 132.

[0072] The mixed fluid of hydrogen gas generated in the cathode catalyst layer 92 and unelectrolyzed water returns to the gas-liquid separator 46 via the water discharge passage 76 and the water electrolysis discharge path 66. The mixed fluid is separated into gas and liquid in the gas-liquid separator 46. The water separated from the mixed fluid is stored in the cathode-side storage unit 58.

[0073] Furthermore, the control unit 200 drives the hydrogen pump 147 and controls the boost power supply 136 to apply a voltage between the cathode power supply and the anode power supply of the boost battery 144. When the hydrogen pump 147 is driven, the hydrogen gas in the gas-liquid separator 46 is supplied to the anode electrode of the boost battery 144 via the boost supply path 138. In the boost battery 144, the hydrogen ions generated at the anode electrode pass through the electrolyte membrane and are guided to the cathode electrode, where they combine with the hydrogen ions to generate hydrogen gas.

[0074] The hydrogen generated at the cathode electrode is guided to the hydrogen delivery path 142. In addition, in the hydrogen delivery path 142, the first branch path 150 is closed by the back pressure valve 154, and the second branch path 152 is closed by the on-off valve 156. In addition, the hydrogen inlet path 164 is closed by the on-off valve 186. Accordingly, hydrogen can be stored in a closed space, so that the pressure of the hydrogen generated in the booster stack 134 can be increased. When the pressure of the hydrogen generated in the booster battery 144 reaches above the hydrogen pressure threshold, the back pressure valve 154 opens, and hydrogen is filled into the hydrogen storage tank 22. In addition, the control unit 200 can also supply the hydrogen pressurized by the booster stack 134 to the hydrogen supply path 24 by opening the on-off valve 156.

[0075] In this energy system 12, water is present in the anode electrode 90 during the operation of the water electrolysis device 48. However, depending on the operating conditions of the water electrolysis cell 70, the anode electrode 90 sometimes lacks water and dries out. In particular, in the pressure-differential water electrolysis cell 70, the water in the anode electrode 90 is pushed by high-pressure oxygen and flows to the cathode electrode 88 via the electrolyte membrane 86, so the anode electrode 90 is prone to drying out. When the anode electrode 90 dries out, the anode electrode 90 (anode power supply 102) is sometimes corroded by oxygen. In addition, components provided in the anode chamber 120 (for example, the load applying mechanism 108) are sometimes corroded. In this embodiment, the corrosion of such anode electrode 90 and the like is suppressed.

[0076] After the energy system 12 is started up, the process proceeds to step S2.

[0077] In step S2, determination unit 204 determines whether the water level in anode-side storage unit 174 is less than a predetermined first water level threshold. Information acquisition unit 202 acquires the water level in anode-side storage unit 174 based on the detection signal from sensor 192. The first water level threshold is appropriately set based on the total capacity of the anode chambers 120 of the plurality of water electrolysis cells 70. If determination unit 204 determines that the water level in anode-side storage unit 174 is less than the first water level threshold (YES in step S2), the process proceeds to step S3.

[0078] In step S3, water is supplied to the anode-side storage unit 174. Specifically, the controller 200 controls the on-off valve 182 to open the water inlet path 160. The water stored in the storage unit 44 of the fuel cell system 14 is then pushed by the oxygen exhaust gas in the gas-liquid separator 36 and directed to the anode-side storage unit 174 via the water inlet path 160. The water directed to the anode-side storage unit 174 is pure water from which impurities have been removed by the ion exchange device 180. When water is introduced to the anode-side storage unit 174, the hydrogen gas in the pressurization chamber 176 is compressed by the piston 170 and discharged to the outside via the discharge path 166. Furthermore, the hydrogen gas flowing through the discharge path 166 is discharged diluted with nitrogen. For example, when the water level in the anode-side storage unit 174 reaches a first water level threshold, the controller 200 controls the on-off valve 182 to close the water inlet path 160. This allows the water level in the anode-side storage unit 174 to be maintained above the first water level threshold. The process then transitions to step S6.

[0079] When the determination unit 204 determines that the water amount in the anode-side storage unit 174 is equal to or greater than the first water amount threshold value (No in step S2 ), the process proceeds to step S4 .

[0080] In step S4, determination unit 204 determines whether the water level in cathode-side storage unit 58 is less than a second water level threshold. Information acquisition unit 202 acquires the water level in cathode-side storage unit 58 based on the detection signal from sensor 192. The second water level threshold is appropriately set based on the size of water electrolysis stack 60, the size of storage unit 44, and other factors. If determination unit 204 determines that the water level in cathode-side storage unit 58 is less than the second water level threshold (YES in step S4), the process proceeds to step S5.

[0081] In step S5, water is supplied to the cathode side storage section 58. Specifically, the control section 200 controls the on-off valve 56 to open the connection path 54. As a result, the water stored in the storage section 44 of the fuel cell system 14 is pushed by the oxygen exhaust gas in the gas-liquid separator 36 and guided to the cathode side storage section 58 via the connection path 54. For example, when the amount of water in the cathode side storage section 58 reaches the second water amount threshold, the control section 200 controls the on-off valve 56 to close the connection path 54. Accordingly, the amount of water in the cathode side storage section 58 can be made to be above the second water amount threshold. Thereafter, the process moves to step S6.

[0082] In step S6, the determination unit 204 determines whether the anode electrode 90 of the water electrolysis cell 70 is dry or potentially dry. Specifically, the determination unit 204 determines whether the anode electrode 90 of the water electrolysis cell 70 is dry or potentially dry based on, for example, the voltage or resistance between the cathode power supply 96 and the anode power supply 102 of the water electrolysis cell 70. When water is not introduced into the anode-side storage unit 174, water is easily supplied to the cathode electrode 88 of the water electrolysis cell 70, while the anode electrode 90 is supplied only with water that has permeated the electrolyte membrane 86. Therefore, the main cause of the increase in the voltage or resistance between the cathode power supply 96 and the anode power supply 102 of the water electrolysis cell 70 is the anode electrode 90. Therefore, it is easy to determine whether the anode electrode 90 of the water electrolysis cell 70 is dry or potentially dry based on, for example, the operating time of the water electrolysis stack 60. The anode electrode 90 being in a dry state refers to a state in which the moisture content in the anode electrode 90 is less than a predetermined moisture content threshold value.

[0083] If the determination unit 204 determines that the anode electrode 90 of the water electrolysis cell 70 is dry or likely to be dry (YES in step S6), the process proceeds to step S7. On the other hand, if the determination unit 204 determines that the anode electrode 90 of the water electrolysis cell 70 is not dry or likely to be dry (NO in step S6), the process proceeds to step S8.

[0084] In step S7, water is supplied to the anode electrode 90 of the water electrolysis cell 70. Specifically, the controller 200 controls the on-off valve 186 to open the hydrogen gas inlet path 164 and controls the on-off valve 184 to open the water supply path 162. As a result, the high-pressure hydrogen gas, pressurized by the booster stack 134, flows from the hydrogen gas inlet path 164 into the pressurization chamber 176, pressing the piston 170 toward the anode-side reservoir 174. The water pressed by the piston 170 flows from the anode-side reservoir 174 via the water supply path 162 to the anode chamber 120 of the water electrolysis cell 70. This supplies water to the anode electrode 90. In other words, the anode chamber 120 is filled with water. Furthermore, if the pressure of the hydrogen gas, pressurized by the booster stack 134, is higher than the pressure of the oxygen gas within the anode chamber 120 of the water electrolysis cell 70, the pressure of the hydrogen gas in the pressurization chamber 176 can cause the piston 170 to move. Furthermore, when the pressure of the hydrogen gas boosted by the booster stack 134 and the pressure of the oxygen gas in the water electrolysis cell 70 are similar, a pressure difference can be generated by reducing the electrolysis rate of the water electrolysis cell 70 .

[0085] When water supply to the anode electrode 90 of the water electrolysis cell 70 is completed, the controller 200 controls the on-off valve 186 to close the hydrogen gas introduction path 164 and controls the on-off valve 184 to close the water supply path 162. Thereafter, the process proceeds to step S8.

[0086] In step S8, the determination unit 204 determines whether the operation of the water electrolysis system 10 has been stopped. Upon receiving the operation stop signal of the water electrolysis system 10, the control unit 200 stops the operation of the water electrolysis system 10. If the determination unit 204 determines that the operation of the water electrolysis system 10 has not been stopped (No in step S8), the process proceeds to step S2. If the determination unit 204 determines that the operation of the water electrolysis system 10 has been stopped (Yes in step S8), the process proceeds to step S9.

[0087] In step S9, the determination unit 204 determines whether the anode chamber 120 is full of water. Specifically, the determination unit 204 determines whether the anode chamber 120 of the water electrolysis cell 70 is full of water based on the voltage or resistance between the cathode power supply 96 and the anode power supply 102 of the water electrolysis cell 70. Alternatively, the determination unit 204 may determine whether the anode chamber 120 of the water electrolysis cell 70 is full of water based on, for example, the operating time of the water electrolysis stack 60. The state in which the anode chamber 120 is not full of water refers to a state in which the amount of water in the anode chamber 120 is less than a predetermined water level threshold.

[0088] If the determination unit 204 determines that the anode chamber 120 is not filled with water (No in step S9), the process proceeds to step S10. On the other hand, if the determination unit 204 determines that the anode chamber 120 is filled with water (Yes in step S9), the process proceeds to step S11.

[0089] When the operation of the water electrolysis system 10 is stopped, the hydrogen gas cannot be pressurized by the booster 50, and therefore, the water stored in the anode side storage unit 174 cannot be pressed by the piston 170. In addition, no oxygen is produced in the anode chamber 120 of the water electrolysis cell 70. In this case, in step S10, water is supplied to the anode chamber 120 of the water electrolysis cell 70 using potential energy. Specifically, the control unit 200 controls the on-off valve 184 to open the water supply path 162. Accordingly, the water stored in the anode side storage unit 174 can fall to the anode chamber 120 via the water supply path 162 by potential energy (gravity). Therefore, the anode chamber 120 can be filled with water. After this, transfer to step S11.

[0090] In step S11, the control unit 200 stops the operation of the fuel cell system 14. According to this structure, the contact state between oxygen and the anode electrode 90 can be suppressed in the stopped state, and the anode electrode 90 of the water electrolysis cell 70 can be suppressed from being corroded by oxygen even in the stopped state. Figure 4 The indicated processing is completed.

[0091] According to this embodiment, since water generated by the fuel cell stack 16 is supplied to the anode electrode 90 of the water electrolysis cell 70, the contact area between the water and the anode electrode 90 can be increased. In other words, the contact area between oxygen and the anode electrode 90 can be reduced. This can suppress corrosion of the anode electrode 90 of the water electrolysis cell 70 by oxygen. Therefore, a more advanced water electrolysis system 10 and energy system 12 can be provided.

[0092] Regarding the above-mentioned embodiment, the following supplementary notes are also disclosed.

[0093] (Note 1) The water electrolysis system (10) of the present invention comprises a water electrolysis device (48) and a water supply device (52), wherein the water electrolysis device (48) comprises a membrane electrode structure (80), the membrane electrode structure (80) being formed by clamping an electrolyte membrane (86) between an anode electrode (90) and a cathode electrode (88), the water electrolysis device (48) causing the anode electrode to generate oxygen by supplying water to the cathode electrode and electrolyzing the water; and the water supply device (52) supplies water generated by power generation of a fuel cell stack (16) to the anode electrode.

[0094] This structure supplies water generated by the fuel cell stack to the anode electrode of the water electrolysis device, thereby increasing the contact area between the water and the anode electrode. In other words, it reduces the contact area between the oxygen and the anode electrode. This prevents oxygen corrosion of the anode electrode of the water electrolysis device. Consequently, a more advanced water electrolysis system can be provided.

[0095] (Note 2) According to the water electrolysis system according to Supplementary Note 1, the pressure of the oxygen gas in the anode electrode may be higher than the pressure of the water in the cathode electrode.

[0096] According to this structure, hydrogen generated on the cathode electrode side is less likely to move to the anode electrode side through the electrolyte membrane, and higher-purity oxygen can be generated.

[0097] (Note 3) According to the water electrolysis system described in Note 1 or 2, the water supply device may also have an anode side storage part (174), and the anode side storage part (174) is used to store water generated as the fuel cell stack generates electricity, and the water stored in the anode side storage part is supplied to the anode electrode during the operation of the water electrolysis device.

[0098] According to this structure, during the operation of the water electrolysis device, the pressure difference between the anode electrode side and the cathode electrode side can be used to suppress the deterioration caused by insufficient moisture in the anode electrode and increased resistance value due to the water passing through the electrolyte membrane being pushed back to the cathode electrode side.

[0099] (Note 4) According to the water electrolysis system described in Note 3, the water supply device may also have a water inlet path (160), and the water inlet path (160) connects the storage part (44) and the anode side storage part to each other, wherein the storage part (44) is used to store water obtained by gas-liquid separation of oxygen waste gas discharged from the fuel cell stack.

[0100] According to this configuration, water stored in the storage portion of the fuel cell stack is guided to the anode-side storage portion via the water introduction path, thereby preventing oxygen off-gas from the fuel cell stack from flowing into the anode-side storage portion together with the water.

[0101] (Note 5) The water electrolysis system according to Note 3 or 4 may also include a boosting device (50), wherein the boosting device (50) includes a boosting cell (144) that is introduced into the hydrogen generated at the cathode electrode and boosts the pressure of the introduced hydrogen, and during the operation of the water electrolysis device, the water supply device pressurizes the water stored in the anode side storage portion to the anode electrode through the pressure of the hydrogen boosted by the boosting device.

[0102] According to this configuration, the water stored in the anode-side storage unit can be supplied to the anode electrode of the water electrolysis device using the pressure of the hydrogen gas boosted by the boosting device.

[0103] (Note 6) According to the water electrolysis system according to Supplementary Note 5, the pressure of the hydrogen gas that can be boosted by the boosting device may be higher than the pressure of the oxygen gas that can be generated at the anode electrode.

[0104] According to this configuration, the water stored in the anode-side storage portion can be smoothly pressure-fed to the anode electrode of the water electrolysis device using the pressure of the hydrogen gas boosted by the boosting device.

[0105] (Note 7) According to the water electrolysis system described in Note 5 or 6, the water supply device may also have a cylinder (168), a piston (170) and a water supply path (162), wherein the cylinder (168) has the anode side storage part; the piston (170) is arranged in the cylinder to press the water stored in the anode side storage part; the water supply path (162) is used to guide the water stored in the anode side storage part to the anode electrode, and the hydrogen gas pressurized by the boosting device presses the piston, and the water stored in the anode side storage part is pressed to the anode electrode via the water supply path.

[0106] According to this configuration, the structure of the water supply device can be simplified.

[0107] (Note 8) The water electrolysis system according to any one of Notes 3 to 7 may also be provided with a cathode side storage section (58), wherein the cathode side storage section (58) stores water for supplying to the cathode electrode, and when the amount of water in the anode side storage section is less than a predetermined water amount threshold, the water generated by the power generation of the fuel cell stack is supplied to the anode side storage section instead of being supplied to the cathode side storage section, and when the amount of water in the anode side storage section is above the water amount threshold, the water generated by the power generation of the fuel cell stack is supplied to the cathode side storage section.

[0108] With this configuration, water generated by the fuel cell stack during power generation can be used for water electrolysis in the water electrolysis device. Furthermore, water generated by the fuel cell stack during power generation is preferentially supplied to the anode-side storage portion over the cathode-side storage portion, thereby preventing a shortage of water supplied to the anode electrode of the water electrolysis device.

[0109] (Note 9) According to any one of Supplementary Notes 3 to 8, the water supply device may supply the water stored in the anode-side storage unit to the anode electrode during a stop of the water electrolysis device.

[0110] According to this configuration, it is possible to suppress the anode electrode from being corroded by oxygen during the operation stop of the water electrolysis device.

[0111] (Note 10) According to any one of Supplementary Notes 5 to 7, the water supply device may supply the water stored in the anode-side storage portion to the anode electrode using potential energy during a stop of the water electrolysis device.

[0112] According to this configuration, even when hydrogen cannot be generated due to the stop of the operation of the water electrolysis device, the water stored in the anode-side storage portion can be supplied to the anode electrode using potential energy.

[0113] (Note 11) According to the water electrolysis system described in Note 9 or 10, the water supply device may also fill the anode chamber (120) containing the anode electrode with water stored in the anode side storage part during the operation stop of the water electrolysis device.

[0114] According to this configuration, it is possible to suppress the anode electrode and the like accommodated in the anode chamber from being corroded by oxygen during the operation stoppage of the water electrolysis device.

[0115] (Note 12) The energy system (12) of the present invention comprises the water electrolysis system according to any one of Supplementary Notes 1 to 11, and a fuel cell system (14) comprising the fuel cell stack.

[0116] According to this structure, a better energy system can be provided.

[0117] The present invention has been described in detail, but the present invention is not limited to the above-mentioned embodiments. These embodiments can be supplemented, replaced, changed, partially deleted, etc. in a manner that does not deviate from the scope of the present invention or in a manner that does not deviate from the scope of the present invention derived from the contents recorded in the technical solution and its equivalents. In addition, these embodiments can also be implemented in combination. For example, in the above-mentioned embodiment, the order of each action and the order of each processing are shown as an example, but are not limited to this. In addition, the same applies when numerical values or mathematical formulas are used in the description of the above-mentioned embodiment.

Claims

1. A water electrolysis system, characterized in that: It has a water electrolysis device and a water supply device, wherein, The water electrolysis device includes a membrane electrode structure formed by sandwiching an electrolyte membrane between an anode electrode and a cathode electrode, and the water electrolysis device generates oxygen gas at the anode electrode by supplying water to the cathode electrode. The water supply device supplies water generated as the fuel cell stack generates power to the anode electrode.

2. The water electrolysis system according to claim 1, characterized in that The pressure of oxygen in the anode electrode is higher than the pressure of water in the cathode electrode.

3. The water electrolysis system according to claim 1, characterized in that The water supply device includes an anode-side storage portion for storing water generated as the fuel cell stack generates power. The water stored in the anode-side storage portion is supplied to the anode electrode during operation of the water electrolysis device.

4. The water electrolysis system according to claim 3, characterized in that The water supply device includes a water introduction path connecting a storage portion for storing water and the anode-side storage portion, wherein the water is water obtained by gas-liquid separation of oxygen off-gas discharged from the fuel cell stack.

5. The water electrolysis system according to claim 3, characterized in that: The device further comprises a boosting device including a boosting cell for introducing hydrogen gas generated at the cathode electrode and boosting the pressure of the introduced hydrogen gas. During operation of the water electrolysis device, the water supply device pressure-feeds the water stored in the anode-side storage portion to the anode electrode using the pressure of the hydrogen gas boosted by the boosting device.

6. The water electrolysis system according to claim 5, characterized in that The pressure of the hydrogen gas that can be boosted by the boosting device is higher than the pressure of the oxygen gas that can be generated by the anode electrode.

7. The water electrolysis system according to claim 5, characterized in that The water supply device comprises a cylinder, a piston and a water supply path, wherein: The cylindrical portion has the anode-side storage portion; The piston is disposed in the cylinder portion and is used to press the water stored in the anode side storage portion; The water supply path is used to guide the water stored in the anode-side storage portion to the anode electrode. The hydrogen gas pressurized by the pressure-increasing device presses the piston, whereby the water stored in the anode-side storage portion is pressure-sent to the anode electrode via the water supply path.

8. The water electrolysis system according to claim 3, characterized in that The device further comprises a cathode-side storage portion for storing water to be supplied to the cathode electrode. When the amount of water in the anode-side storage portion is less than a predetermined water amount threshold, water generated by power generation of the fuel cell stack is supplied to the anode-side storage portion but not to the cathode-side storage portion. When the amount of water in the anode-side storage section is equal to or greater than the water amount threshold, water generated by power generation by the fuel cell stack is supplied to the cathode-side storage section.

9. The water electrolysis system according to claim 3, characterized in that: The water supply device supplies the water stored in the anode-side storage portion to the anode electrode during a period in which the operation of the water electrolysis device is stopped.

10. The water electrolysis system according to claim 5, characterized in that: The water supply device supplies the water stored in the anode-side storage portion to the anode electrode using potential energy during a stop of the water electrolysis device.

11. The water electrolysis system according to claim 9, characterized in that: During the operation stop of the water electrolysis device, the water supply device supplies the water stored in the anode-side storage portion to the anode chamber accommodating the anode electrode, thereby filling the anode chamber with water.

12. An energy system, characterized in that: have: The water electrolysis system according to any one of claims 1 to 11; and A fuel cell system having the fuel cell stack.

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