Degradation determination support device, water electrolysis device, and degradation determination support method

Abstract

A deterioration determination support device 40 includes: a first calculating unit 42 that acquires a dataset including a plurality of reaction condition values and voltages relating to water electrolysis reaction of a water electrolysis module 2, which have been measured in a first period, and in a second period following the first period, or derived from measured values, and uses the dataset and a predetermined calculation expression to calculate a parameter group for the calculation expression for each period; a second calculating unit 44 that substitutes predetermined reaction condition values into the calculation expression into which the parameter group is incorporated, and calculates a comparison object value for each period; and a third calculating unit 46 that calculates a degree of deterioration of the water electrolysis module 2 on the basis of difference between a first comparative object value calculated by the calculation expression into which the parameter group for the first period is incorporated, and a second comparative object value calculated by the calculation expression into which the parameter group for the second period is incorporated.

Description

[Technical Field]

[0001] The present invention relates to a deterioration determination support device, a water electrolysis device, and a deterioration determination support method. [Background technology]

[0002] In recent years, renewable energy sources such as wind and solar power have attracted attention as energy sources that can reduce carbon dioxide emissions during the generation process compared to energy obtained from thermal power generation. Electricity generated from renewable energy can be stored in stationary energy storage systems to smooth the output power. In recent years, water electrolysis modules, which produce hydrogen gas by electrolyzing water, have become increasingly popular as stationary energy storage systems. Examples of water electrolysis modules include solid polymer type water electrolysis modules, alkaline type water electrolysis modules, and solid oxide type water electrolysis modules, as disclosed in Patent Document 1, for example. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2018-165392 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Generally, water electrolysis modules, which are components of water electrolysis equipment, deteriorate under the influence of factors such as operating time, temperature, and the number of starts and stops, leading to a gradual decrease in hydrogen production efficiency. To ensure stable function as an energy storage system, it is desirable to understand the deterioration state of the water electrolysis module. On the other hand, switching from normal operation to deterioration detection operation in order to understand the deterioration state of the water electrolysis module can lead to a decrease in hydrogen gas production efficiency. Therefore, it is necessary to understand the deterioration state while continuing the normal operation state of the water electrolysis module. However, since reaction conditions can change moment by moment during normal operation, it has been difficult to determine the deterioration of the water electrolysis module.

[0005] This invention was made in view of these circumstances, and one of its objectives is to provide a technology that supports the determination of deterioration of a water electrolysis module during normal operation. [Means for solving the problem]

[0006] One aspect of the present invention is a deterioration determination support device. This device includes: a first calculation unit that acquires a dataset including multiple reaction condition values ​​and voltages related to the water electrolysis reaction of a water electrolysis module, measured or derived from measured values ​​during a first period and a second period following the first period, and calculates a set of parameters for a calculation formula for each period using the dataset and a predetermined calculation formula; a second calculation unit that calculates a comparison target value for each period by substituting predetermined reaction condition values ​​into a calculation formula incorporating the parameter set; and a third calculation unit that calculates the degree of deterioration of the water electrolysis module based on the difference between a first comparison target value calculated from a calculation formula incorporating the parameter set for the first period and a second comparison target value calculated from a calculation formula incorporating the parameter set for the second period.

[0007] Another aspect of the present invention is a deterioration determination support device. This device includes a first calculation unit that acquires a dataset including multiple reaction condition values ​​and voltages related to the water electrolysis reaction of a water electrolysis module, measured or derived from measured values ​​during a first period and a second period following the first period, and calculates a set of parameters for a calculation formula in each period using the dataset and a predetermined calculation formula, and a fourth calculation unit that calculates the degree of deterioration of the water electrolysis module based on the difference between at least one of the coefficients constituting the parameter set in the first period and the said coefficient in the second period.

[0008] Another aspect of the present invention is a water electrolysis apparatus. This system comprises a water electrolysis module and a degradation determination support apparatus according to any of the above aspects.

[0009] Another aspect of the present invention is a method for supporting degradation determination. This method includes acquiring a dataset containing multiple reaction condition values ​​and voltages related to the water electrolysis reaction of a water electrolysis module in a first period and a second period following the first period; calculating a set of parameters for the calculation formula in each period using the dataset and a predetermined calculation formula; substituting predetermined reaction condition values ​​into the calculation formula incorporating the set of parameters to calculate a comparison value in each period; and calculating the degree of degradation of the water electrolysis module based on the difference between a first comparison value calculated from the calculation formula incorporating the set of parameters in the first period and a second comparison value calculated from the calculation formula incorporating the set of parameters in the second period.

[0010] Any combination of the above components, as well as any conversion of the expressions of this disclosure between methods, apparatus, systems, etc., are also valid forms of this disclosure. [Effects of the Invention]

[0011] According to the present invention, it is possible to support the determination of deterioration of a water electrolysis module during normal operation. [Brief explanation of the drawing]

[0012] [Figure 1]This is a schematic diagram of a water electrolysis apparatus according to an embodiment. [Figure 2] This figure shows the current-voltage characteristics of a water electrolysis module. [Figure 3] This is a flowchart illustrating a method for supporting deterioration assessment, as an example. [Figure 4] Figure 4(A) shows the relationship between time and current in the water electrolysis operation test performed in the example. Figure 4(B) shows the corrected parameter group, various voltages, and degree of degradation in the example. [Modes for carrying out the invention]

[0013] The present invention will be described below with reference to the drawings, based on preferred embodiments. The embodiments are illustrative and not limit the technical scope of the present invention, and not all features or combinations thereof described in the embodiments are necessarily essential to the invention. Therefore, the content of the embodiments can be modified in many ways, such as changing, adding, or deleting components, as long as it does not depart from the spirit of the invention as defined in the claims. A new embodiment with modified designs will have the combined effects of both the embodiments and the variations. In the embodiments, such modifications are emphasized with notations such as "of this embodiment" or "in this embodiment," but modifications are also permitted for content without such notations. Any combination of the above components is also valid as an embodiment of the present invention. The same or equivalent components, members, and processes shown in each drawing are denoted by the same reference numerals, and redundant explanations are omitted as appropriate. Furthermore, the scale and shape of each part shown in each drawing are set for convenience to facilitate explanation and are not to be interpreted restrictively unless specifically mentioned. Furthermore, where terms such as "first," "second," etc., are used in this specification or claims, these terms do not indicate any order or importance, but are used to distinguish one configuration from another. In addition, some components that are not important for describing the embodiments are omitted from the drawings.

[0014] Figure 1 is a schematic diagram of a water electrolysis apparatus according to an embodiment. The water electrolysis apparatus 1 comprises a water electrolysis module 2, a power supply 4, a first supply mechanism 6, a second supply mechanism 8, and a control device 10. In this disclosure, the water electrolysis module 2 may consist of a single cell, multiple cells, a stack of multiple cells connected together, multiple stacks, or a combination thereof.

[0015] The water electrolysis module 2 is an electrolytic cell that generates hydrogen by the electrolysis of water. In this embodiment, the water electrolysis module 2 is a solid polymer membrane type water electrolysis device that utilizes a solid ion exchange membrane. The water electrolysis module 2 has an oxygen generation electrode 12, an oxygen generation electrode chamber 14, a hydrogen generation electrode 16, a hydrogen generation electrode chamber 18, and a diaphragm 20.

[0016] The oxygen generation electrode 12 is defined as the anode, as it is the electrode where the oxidation reaction takes place. The oxygen generation electrode 12 has a catalyst layer 12a and a gas diffusion layer 12b. The catalyst layer 12a contains, for example, iridium (Ir) or platinum (Pt) as a catalyst. The catalyst layer 12a may also contain other metals or metal compounds. The catalyst layer 12a is positioned so as to be in contact with one of the main surfaces of the diaphragm 20. The gas diffusion layer 12b is composed of a conductive porous material or the like. Known materials can be used to constitute the gas diffusion layer 12b. The oxygen generation electrode 12 is housed in the oxygen generation electrode chamber 14. The space in the oxygen generation electrode chamber 14 excluding the oxygen generation electrode 12 constitutes a water and oxygen flow path.

[0017] The hydrogen generation electrode 16 is defined as the cathode, which is the electrode where the reduction reaction occurs. The hydrogen generation electrode 16 has a catalyst layer 16a and a gas diffusion layer 16b. The catalyst layer 16a contains, for example, platinum as a catalyst. The catalyst layer 16a may also contain other metals or metal compounds. The catalyst layer 16a is positioned in contact with the other main surface of the diaphragm 20. The gas diffusion layer 16b is made of a conductive porous material or the like. Known materials can be used to make up the gas diffusion layer 16b. The hydrogen generation electrode 16 is housed in the hydrogen generation electrode chamber 18. The space in the hydrogen generation electrode chamber 18 excluding the hydrogen generation electrode 16 constitutes a water and hydrogen flow path.

[0018] The oxygen generation electrode 12 and the hydrogen generation electrode 16 are separated by a diaphragm 20. The diaphragm 20 is positioned between the oxygen generation electrode 12 and the hydrogen generation electrode 16. In this embodiment, the diaphragm 20 is made of a proton exchange membrane (PEM), which is a type of solid polymer membrane. A PEM is a proton exchange membrane (H + The material is not particularly limited as long as it conducts fluorine, but examples include fluorine-based ion exchange membranes having sulfonic acid groups.

[0019] The reaction during water electrolysis in water electrolysis module 2 is as follows: Anode reaction during electrolysis: 2H2O → O2 + 4H + +4e - Cathode reaction during electrolysis: 4H + +4e - →2H2

[0020] At the oxygen generation electrode 12, water is electrolyzed to produce oxygen gas, protons, and electrons. The protons travel across the membrane 20 towards the hydrogen generation electrode 16. The electrons flow into the positive electrode of the power supply 4. The oxygen gas is discharged to the outside through the oxygen generation electrode chamber 14. At the hydrogen generation electrode 16, hydrogen gas is produced by the reaction of electrons supplied from the negative electrode of the power supply 4 with the protons that have traveled across the membrane 20. The hydrogen gas is discharged to the outside through the hydrogen generation electrode chamber 18.

[0021] Power supply 4 is a DC power supply that supplies power to the water electrolysis module 2. When power is supplied from power supply 4 to the water electrolysis module 2, a predetermined electrolytic voltage is applied between the oxygen generation electrode 12 and the hydrogen generation electrode 16 of the water electrolysis module 2, and an electrolytic current flows. Power supply 4 receives power from the power supply device 21 and supplies power to the water electrolysis module 2. The power supply device 21 in this embodiment is composed of a power generation device that generates electricity using renewable energy, such as a wind power generation device 22 or a solar power generation device 24. Note that the power supply device 21 is not limited to a power generation device that uses renewable energy, but may also be a grid power supply, or a storage device that stores electricity from a renewable energy power generation device or grid power supply, etc. It may also be a combination of two or more of these.

[0022] The first supply mechanism 6 supplies water to the oxygen generation electrode chamber 14. The first supply mechanism 6 includes a first circulation tank 26, a first circulation path 28, and a first circulation device 30. The first circulation tank 26 contains water that is supplied to the oxygen generation electrode chamber 14 and water that is recovered from the oxygen generation electrode chamber 14. For example, the first circulation tank 26 contains pure water.

[0023] The first circulation tank 26 and the oxygen generation electrode chamber 14 are connected by a first circulation path 28. The first circulation path 28 has a forward path section 28a for supplying water from the first circulation tank 26 to the oxygen generation electrode chamber 14, and a return path section 28b for recovering water from the oxygen generation electrode chamber 14 to the first circulation tank 26. The first circulation device 30 is installed, for example, in the middle of the forward path section 28a. When the first circulation device 30 is driven, water flows through the first circulation path 28 and circulates between the first circulation tank 26 and the oxygen generation electrode chamber 14. As the first circulation device 30, various pumps such as gear pumps and cylinder pumps, or gravity-fed devices can be used.

[0024] The first circulation tank 26 also functions as a gas-liquid separation unit. Since oxygen is generated by the electrode reaction in the oxygen generation electrode 12, the water recovered from the oxygen generation electrode chamber 14 contains gaseous oxygen and dissolved oxygen. The gaseous oxygen is separated from the water in the first circulation tank 26 and removed from the system. The water from which the oxygen has been separated is supplied again to the water electrolysis module 2. In addition, a gas-liquid separation unit may be provided separately from the first circulation tank 26.

[0025] The second supply mechanism 8 supplies water to the hydrogen generation electrode chamber 18. The second supply mechanism 8 includes a second circulation tank 32, a second circulation path 34, and a second circulation device 36. The second circulation tank 32 contains water that is supplied to the hydrogen generation electrode chamber 18 and water that is recovered from the hydrogen generation electrode chamber 18. For example, the second circulation tank 32 contains pure water.

[0026] The second circulation tank 32 and the hydrogen generation electrode chamber 18 are connected by a second circulation path 34. The second circulation path 34 has a forward path 34a for supplying water from the second circulation tank 32 to the hydrogen generation electrode chamber 18, and a return path 34b for recovering water from the hydrogen generation electrode chamber 18 to the second circulation tank 32. The second circulation device 36 is installed, for example, in the middle of the forward path 34a. Driven by the second circulation device 36, water flows through the second circulation path 34 and circulates between the second circulation tank 32 and the hydrogen generation electrode chamber 18. As the second circulation device 36, various pumps such as gear pumps and cylinder pumps, or gravity-fed devices can be used.

[0027] The second circulation tank 32 also functions as a gas-liquid separation unit. Since hydrogen is generated by an electrode reaction in the hydrogen generation electrode 16, the water recovered from the hydrogen generation electrode chamber 18 contains gaseous hydrogen and dissolved hydrogen. The gaseous hydrogen is separated from the water in the second circulation tank 32 and removed from the system. The water from which the hydrogen has been separated is supplied again to the water electrolysis module 2. In addition, a gas-liquid separation unit may be provided separately from the second circulation tank 32.

[0028] The structure of the water electrolysis device 1 is not limited to that described above. For example, the water electrolysis module 2 may be an anion exchange membrane (AEM) type, an alkaline type, a solid oxide type, etc. Also, if the water electrolysis module 2 is a PEM type, the second supply mechanism 8 may be omitted. In this case, a pipe for removing hydrogen gas from the system is connected to the hydrogen generation electrode chamber 18. Alternatively, the system may be configured to send water from the oxygen generation electrode chamber 14 to the system without returning it to the first circulation tank 26. Furthermore, the water electrolysis module 2 may comprise multiple cells or multiple stacks. In this case, as an example, each cell or stack is oriented so that the oxygen generation electrode chamber 14 and the hydrogen generation electrode chamber 18 are aligned in the same direction, and is stacked with a conductive plate in between adjacent cells or stacks. This connects each cell or stack electrically in series. The conductive plate is made of a conductive material such as metal.

[0029] The control device 10 controls the operation of the water electrolysis apparatus 1. The control device 10 is implemented as a hardware component consisting of elements and circuits, including a computer's CPU and memory, and as a software component consisting of computer programs, etc. However, in Figure 1, it is depicted as a functional block realized through the coordination of these components. It will be obvious to those skilled in the art that this functional block can be realized in various ways through combinations of hardware and software.

[0030] The control device 10 receives input from a sensor 38 provided in the water electrolysis device 1, representing various reaction condition values ​​related to the water electrolysis reaction of the water electrolysis module 2. The sensor 38 repeatedly measures the values ​​of the various reaction conditions at predetermined intervals and sends the measurement results to the control device 10. The control device 10 or the degradation determination support device 40 (described later) stores the acquired measurement results in memory. If necessary, the control device 10 or the degradation determination support device 40 derives reaction condition values ​​from the values ​​measured by the sensor 38. Reaction conditions related to the water electrolysis reaction include voltage, current, water temperature, oxygen gas pressure, hydrogen gas pressure, etc. Hereinafter, in this disclosure, values ​​other than voltage will be referred to as "reaction condition values." The reaction condition values ​​and voltage together will be referred to as a "data set."

[0031] For example, the sensor 38 has a known voltmeter and measures the potentials of the oxygen generation electrode 12 and the hydrogen generation electrode 16, or the voltage of the water electrolysis module 2 (so-called stack voltage or cell voltage), and sends the results to the control device 10. The potentials of each electrode and the voltage of the water electrolysis module 2 can be detected by known methods. For example, when the sensor 38 detects the potential of each electrode, a reference electrode is provided in the diaphragm 20. The reference electrode is maintained at the reference electrode potential. For example, the reference electrode is a reversible hydrogen electrode (RHE). One terminal of the voltmeter is connected to the reference electrode, and the other terminal is connected to the electrode to be detected, so that the potential of the electrode relative to the reference electrode is detected. Also, when the sensor 38 detects the voltage of the water electrolysis module 2, one terminal of the voltmeter is connected to the oxygen generation electrode 12, and the other terminal is connected to the hydrogen generation electrode 16, so that the potential difference between the two electrodes, i.e., the voltage, is detected. When the sensor 38 detects voltage, the reference electrode can be omitted.

[0032] Furthermore, the sensor 38 has a known ammeter and measures the current flowing between the oxygen generation electrode 12 and the hydrogen generation electrode 16 and sends the measured value to the control device 10. The sensor 38 also has a known thermometer and measures the temperature of the water flowing through the water electrolysis module 2 and sends the measured value to the control device 10. The temperature of the water flowing through the water electrolysis module 2 may be estimated by, for example, the temperature of the water in the first supply mechanism 6, such as in the first circulation tank 26, or by the temperature of the water in the second supply mechanism 8, such as in the second circulation tank 32, or by the average value of these, etc.

[0033] Furthermore, the sensor 38 has a known pressure gauge and measures the pressure of the oxygen gas and hydrogen gas generated in the water electrolysis module 2 and sends the measured values ​​to the control device 10. The pressure of the oxygen gas generated in the water electrolysis module 2 is, for example, the pressure of the oxygen gas in the oxygen generation electrode chamber 14. The pressure of the hydrogen gas generated in the water electrolysis module 2 is, for example, the pressure of the hydrogen gas in the hydrogen generation electrode chamber 18.

[0034] The control device 10 controls the output of the power supply 4, the driving of the first supply mechanism 6 and the second supply mechanism 8, etc., based on the measurement results of the sensor 38. The control device 10 also has a degradation determination support device 40. Similar to the control device 10, the degradation determination support device 40 is implemented as a hardware configuration consisting of elements and circuits such as a computer CPU and memory, and as a software configuration consisting of a computer program, etc., but in Figure 1 it is depicted as a functional block realized by the cooperation of these. Note that the water electrolysis device 1 may be equipped with the degradation determination support device 40 independently of the control device 10. Specifically, the degradation determination support device 40 may be attached externally to the water electrolysis device 1. Also, the degradation determination support device 40 may be connected to the water electrolysis device 1 via a telecommunications line by wired, wireless, or a combination thereof.

[0035] The degradation determination support device 40 acquires a dataset including multiple reaction condition values ​​and voltages related to the water electrolysis reaction using a sensor 38, etc., and obtains a parameter group using this dataset and a predetermined calculation formula. A comparison value is obtained by substituting the predetermined reaction condition values ​​into the calculation formula incorporating this parameter group. The degree of degradation of the water electrolysis module 2 is calculated based on the difference between the first comparison value calculated from the calculation formula incorporating the parameter group in the first period and the second comparison value calculated from the calculation formula incorporating the parameter group in the second period, which is after the first period. The calculated degree of degradation can be used as an indicator to judge the degradation state of the water electrolysis module 2. The predetermined reaction condition values ​​can be set as appropriate based on experiments, simulations, etc. The degradation determination support device 40 comprises a first calculation unit 42, a second calculation unit 44, a third calculation unit 46, a notification unit 48, and an operation support unit 50.

[0036] The first calculation unit 42 acquires a dataset containing multiple reaction condition values ​​and voltages measured by the sensor 38 or derived from measured values. Then, it calculates a set of parameters using the dataset and a predetermined calculation formula.

[0037] First, a voltage calculation formula is defined in advance as a predetermined calculation formula. The defined calculation formula is stored in the degradation determination support device 40. Note that the calculation formula stored in the degradation determination support device 40 may be rewritable from an external source. Alternatively, the degradation determination support device 40 may define the voltage calculation formula itself.

[0038] Figure 2 shows the current-voltage characteristics of the water electrolysis module 2. Note that Figure 2 shows the current-voltage characteristics approximately. As shown in Figure 2, the voltage V (electrolysis voltage) of the water electrolysis module 2 is equal to the equilibrium potential u of the water electrolysis reaction and the activation overpotential η of the oxygen evolution reaction. act (so-called oxygen overpotential) and the resistive overpotential η of the diaphragm 20 IR It can be defined as the sum of these values. Note that voltage V may be the cell voltage, the sum of multiple cell voltages, the average value of multiple cell voltages, the stack voltage, the sum of multiple stack voltages, or the average value of multiple stack voltages.

[0039] Therefore, the voltage calculation formula can be expressed as in Equation (1). Below, the voltage calculated by the voltage calculation formula is referred to as the calculated voltage V sim and is called so. (1) V sim =u + η act + η IR In Equation (1), only the anodic reaction is considered. Also, the resistance losses and concentration overvoltages caused by factors other than the separator 20 are ignored. Note that the voltage calculation formula may be added with an activation overvoltage term η act_ H2 of the hydrogen generation reaction, a concentration overvoltage term η conc , a temperature correction term (the difference between the water temperature during circulation and the water temperature during the electrode reaction), etc.

[0040] The equilibrium potential u of the water electrolysis reaction can be calculated from Equation (2), that is, the Nernst equation, as an example.

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[0041] T, P_H2, and P_O2 correspond to the reaction condition values ​​measured by sensor 38. P_H2O corresponds to the reaction condition value derived from these reaction condition values. Note that the equilibrium potential u may be calculated using a function of other measured values. Alternatively, the equilibrium potential u may be calculated by equation (3) ignoring the pressure term, or it may be a constant as shown in equation (4). (3) u = 1.23 - a(T - 298.15) (4) u=1.23

[0042] Activation overpotential η of the oxygen evolution reaction act For example, it can be calculated from equation (5). (5) η act =f(T,i) In equation (5), T is the absolute temperature of the water flowing through the water electrolysis module 2. i is the current density flowing through the water electrolysis module 2. That is, the activation overpotential η act This is an estimated value calculated using a function f of the absolute temperature T of water and the current density i. The current density i is derived by calculation from the current value measured by the sensor 38. Note that the activation overpotential η act This can be calculated using a function of other measured values, or it can be a constant.

[0043] Activation overpotential η act One example of a function f used to calculate this is a function based on the Butler-Volmer equation, namely, the activation overpotential η. act This can be calculated from equation (6).

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[0044] Furthermore, the activation overpotential η act Another example of a function f that calculates the activation overpotential η is a function based on Tafel's equation, namely, the activation overpotential η. act This can be calculated from equation (7).

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[0045] Resistive overvoltage η IR For example, it can be calculated from equation (8). (8) η IR =r(T)i In equation (8), r is the resistance of the diaphragm 20, T is the absolute temperature of the water flowing through the water electrolysis module 2, and i is the current density flowing through the water electrolysis module 2. That is, the resistive overpotential η IR This is an estimated value calculated based on the resistance value r, which is a function of the absolute temperature T of water, and the current density i. Note that when defining the function of resistance value r, other measured values ​​or a constant may be used.

[0046] Resistive overvoltage η IR As a concrete example of the calculation using equation (8), we can give equation (9).

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[0047] The denominator on the right-hand side of equation (9) represents the proton conductivity that contributes to the film resistance. In equation (9), this part is expressed using the Arrhenius equation, but as an alternative example, it can also be expressed using equation (10).

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[0048] Also, the resistive overvoltage η IR This can also be expressed as in equation (11), where the resistance value r is a constant independent of temperature. (11) η IR =r×i In equation (11), i is the current density. r is the resistance of the diaphragm 20 and is a constant. The resistance value r is determined by measurement or other means.

[0049] The first calculation unit 42 acquires multiple data sets for each period from the output value of the sensor 38. This data set includes various reaction condition values ​​to be substituted into the calculation formula and the measured voltage V measured by the sensor 38. obsThe following are included as components. In this embodiment, the above-described voltage calculation formula is used, so the reaction condition values ​​include current, water temperature, hydrogen generation pressure, and oxygen generation pressure. The first calculation unit 42 substitutes the reaction condition values ​​in these multiple data sets into the voltage calculation formula to calculate the voltage V sim Along with the above, the calculated voltage V sim The measured voltage V obs The parameter set is adjusted to approximate the desired result.

[0050] In this embodiment, the first period is the period during which the water electrolysis module 2 is presumed to be undegraded. This makes it possible to determine the lifespan of the water electrolysis module 2 with higher accuracy. For example, a predetermined period immediately after the start of use of the water electrolysis module 2 can be estimated as the period during which the water electrolysis module 2 is undegraded. The period during which the water electrolysis module 2 is undegraded can be appropriately set based on experiments, simulations, etc. The second period is the period during which the degradation state of the water electrolysis module 2 is to be measured.

[0051] The coefficients in each calculation formula may change as the water electrolysis module 2 deteriorates. In other words, since the coefficients in the calculation formulas are physical properties of each component of the water electrolysis module 2, the appropriate values ​​may change depending on the state of the water electrolysis module 2. The first calculation unit 42 calculates the calculation voltage V for each period. sim The measured voltage V obs The coefficients in each calculation formula are corrected to approximate the target. This correction only needs to be performed on at least one coefficient. Specifically, the activation overpotential η act For the term, for example, if equation (6) is used, then α, i0, and E exc You can correct one of the following and substitute the literature value for the remaining coefficient. Also, the resistive overvoltage η IR For the term, for example, when equation (9) is used, σ and E pro You may correct one of the following coefficients and substitute the literature value for the remaining coefficient. When calculating the coefficient in the first period, you may use the literature value as the initial value for the coefficient.

[0052] For example, the dataset acquired during each period includes reaction condition values ​​at multiple time points and the measured voltage V at those time points. obs This includes combinations of the following. The first calculation unit 42 calculates these multiple reaction condition values ​​and the measured voltage V obs The coefficients in the voltage calculation formula are corrected using a combination of these. The coefficient correction can be performed using known correction methods, such as curve fitting using the least squares method. As a result, the first calculation unit 42 calculates a group of parameters for each period that includes the corrected coefficients as components. If only some of the coefficients are corrected, the parameter group will also include coefficients that are treated as literature values, etc.

[0053] The second calculation unit 44 calculates the comparison value for each period by substituting predetermined reaction condition values ​​into each of two calculation formulas that incorporate the parameter groups for each period. The predetermined reaction condition values ​​are not values ​​included in the dataset, but can be set appropriately based on experiments, simulations, etc. As a comparison value, for example, the calculated voltage V sim , activation overpotential η act , resistive overvoltage η IR These are some examples.

[0054] The third calculation unit 46 calculates the degree of deterioration based on the difference between a first comparison value calculated from a calculation formula incorporating the parameter group in the first period and a second comparison value calculated from a calculation formula incorporating the parameter group in the second period. This degree of deterioration corresponds to the progress of the deterioration state of the water electrolysis module 2 in the second period, relative to the deterioration state of the water electrolysis module 2 in the first period. In another embodiment, the fourth calculation unit (not shown) may calculate the degree of deterioration by directly comparing at least one of the coefficients constituting the parameter group for each period, without using comparison values.

[0055] The calculated voltage V is used as the comparison value. sim When using this method, the calculated voltage V is obtained from the calculation formula that incorporates the parameter group in the first period. sim Calculate 1. Also, calculate the voltage V from the calculation formula incorporating the parameter group in the second period. simCalculate 2. Then, the two calculated voltages V sim The first degree of deterioration, d1, is calculated based on the difference.

[0056] Specifically, the second calculation unit 44 substitutes predetermined reaction condition values ​​into the voltage calculation formula incorporating the parameter group in the first period, and calculates the voltage V sim Calculate 1. Also, substitute the same reaction condition values ​​into the voltage calculation formula incorporating the parameter group in the second period to calculate the voltage V. sim The third calculation unit 46 calculates the first degree of deterioration d1 using, for example, equation (12). (12) d1=(V sim 2-V sim 1) / V sim 1

[0057] Furthermore, the second calculation unit 44 of this embodiment uses the parameter group for each period to calculate the activation overvoltage η for the first period. act Activation overpotential η during periods 1 and 2 act The second calculation unit calculates the second. Then, the third calculation unit 46 calculates the two activation overvoltages η act Based on the differences, the second degree of degradation d2 of water electrolysis module 2 is calculated.

[0058] Specifically, the second calculation unit 44 calculates the activation overvoltage η in the voltage calculation formula incorporating the parameter group in the first period. act Substitute the predetermined reaction condition values ​​into the term and obtain the activation overpotential η act Calculate 1. Also, the activation overpotential η in the voltage calculation formula incorporating the parameter group in the second period. act Substitute the same reaction condition values ​​into the term and obtain the activation overpotential η act The third calculation unit 46 calculates the second degree of deterioration d2 using, for example, equation (13). (13) d2=(η act 2-η act 1) / η act 1

[0059] By calculating this second degree of degradation d2, it becomes possible to determine the degradation state of the catalyst layer 12a of the oxygen generation electrode 12. Therefore, the degradation state of the water electrolysis module 2 can be estimated in more detail.

[0060] Furthermore, the second calculation unit 44 of this embodiment uses the parameter group for each period to calculate the resistance overvoltage η of the first period. IR Resistive overpotential η in periods 1 and 2 IR The second calculation unit calculates the second value. Then, the third calculation unit 46 calculates the second value. IR Based on the differences, the third degree of degradation d3 of water electrolysis module 2 is calculated.

[0061] Specifically, the second calculation unit 44 calculates the resistance overvoltage η in the voltage calculation formula incorporating the parameter group in the first period. IR Substitute the predetermined reaction condition values ​​into the term and obtain the resistance overpotential η IR Calculate 1. Also, the resistance overvoltage η in the voltage calculation formula incorporating the parameter group in the second period. IR Substitute the same reaction condition values ​​into the term and obtain the resistance overpotential η IR The third calculation unit 46 calculates the third degree of deterioration d3 using, for example, equation (14). (14) d3=(η IR 2-η IR 1) / η IR 1

[0062] By calculating this third degree of degradation d3, it becomes possible to determine the degradation state of the diaphragm 20. Therefore, the degradation state of the water electrolysis module 2 can be estimated in more detail.

[0063] The third calculation unit 46 can quantitatively determine the degree of deterioration of the water electrolysis module 2 based on each of the first deterioration degree d1, the second deterioration degree d2, and the third deterioration degree d3, or based on a combination of two or more of them, or both. For example, threshold values ​​d10 to d30 for each of the first deterioration degree d1 to the third deterioration degree d3, which serve as a guideline for replacing the water electrolysis module 2, are set in advance and stored in the deterioration determination support device 40. The threshold values ​​d10 to d30 can be set as appropriate based on experiments, simulations, etc. Then, the third calculation unit 46 can determine the remaining lifespan t of the water electrolysis module 2 using, for example, equation (15). d In other words, it is possible to calculate when the water electrolysis module 2 needs to be replaced.

number

[0064] The notification unit 48 notifies the user that it is time to replace the water electrolysis module 2 when at least one of the first deterioration levels d1 to the third deterioration level d3 exceeds a threshold. The notification method is not particularly limited, and known methods such as generating a notification sound or lighting a notification light can be used. The notification unit 48 may also notify the user when two or more of the first deterioration levels d1 to the third deterioration level d3 exceed a threshold, or when all deterioration levels exceed a threshold. Furthermore, if the water electrolysis device 1 is equipped with multiple water electrolysis modules 2, the replacement time for each water electrolysis module 2 can be determined individually by calculating the first deterioration level d1 to the third deterioration level d3 for each water electrolysis module 2. The notification unit 48 may also be omitted.

[0065] The operation support unit 50 compares the ratio of the second degree of degradation d2 to the threshold value d20 (d2 / d20) and the ratio of the third degree of degradation d3 to the threshold value d30 (d3 / d30). For example, if d2 / d20 > d3 / d30, the operation support unit 50 instructs the control device 10 to set operating conditions to avoid operation that causes degradation of the catalyst layer 12a of the oxygen generation electrode 12. On the other hand, if d3 / d30 > d2 / d20, the operation support unit 50 instructs the control device 10 to set operating conditions to avoid operation that causes degradation of the diaphragm 20. The ratio of the third degree of degradation d3 to the threshold value d30 (d3 / d30) may also be expressed as d3 / d30 + C by adding a constant C. These measures can be used to extend the lifespan of the water electrolysis module 2. The operating method for suppressing the degradation of the catalyst layer 12a and the diaphragm 20 can be set appropriately based on experiments, simulations, etc. Note that the operation support unit 50 may be omitted.

[0066] Figure 3 is a flowchart of a degradation determination support method for one example. In this method, it is first determined whether a predetermined calculation formula is already defined (S101). If the calculation formula is not defined (N in S101), the predetermined calculation formula is defined (S102). The determination of whether the calculation formula is already defined and the definition of the calculation formula may be performed by the user of the degradation determination support device 40 or by the degradation determination support device 40.

[0067] Next, the dataset for the first period is acquired (S103). The dataset is provided by the sensor 38. If a calculation formula is defined (Y in S101), the formula definition process is skipped and the dataset for the first period is acquired. Subsequently, the parameter set for the first period is calculated using the defined calculation formula and the acquired dataset (S104). The parameter set for the first period is provided by the degradation determination support device 40. The arrival of the first period, in other words, the timing of the calculation of the parameter set for the first period, may be given by an external instruction from the user or the like, or by a program pre-set in the degradation determination support device 40.

[0068] Next, it is determined whether the second period, for which measurement of the degradation state of the water electrolysis module 2 is desired, has been reached (S105). If the second period has not been reached (N in S105), the determination process of whether or not the second period has been reached (S105) is repeated. If the second period has been reached (Y in S105), the data set for the second period is acquired (S106). The data set is provided by the sensor 38 and the degradation determination support device 40. Subsequently, the parameter set for the second period is calculated using the defined calculation formula and the acquired data set (S107). The parameter set for the second period is provided by the degradation determination support device 40. The timing of reaching the second period, in other words, the timing of calculating the parameter set for the second period, may be given by an external instruction from the user, etc., or by a program pre-set in the degradation determination support device 40.

[0069] Next, the first and second comparison values ​​are calculated using a calculation formula incorporating the parameter group for the first period and a calculation formula incorporating the parameter group for the second period (S108). Then, the degree of deterioration of the water electrolysis module 2 is calculated based on the difference between the first and second comparison values ​​(S109). The degree of deterioration is provided by the deterioration determination support device 40. The calculated degree of deterioration is notified to the user. This allows the user to understand when to replace the water electrolysis module 2. In addition, operation control of the water electrolysis module 2 is performed according to the degree of deterioration.

[0070] Next, it is determined whether the water electrolysis module 2 has been replaced (S110). If the water electrolysis module 2 has been replaced (Y in S110), this flow ends. Then, a new flow for the degradation determination support method is executed for the replaced water electrolysis module 2. In the new flow, the calculation formula defined in the previous flow is reused (Y in S101). Note that the calculation formula may be redefined each time the flow is executed, or it may be redefined at any time. If the water electrolysis module 2 has not been replaced (N in S110), the process from determining whether the second period has been reached (S105) to calculating the degree of degradation (S109) is repeated. Note that the replacement of the water electrolysis module 2 is performed by the user. The determination of whether or not it has been replaced is made by the degradation determination support device 40.

[0071] As described above, the water electrolysis apparatus 1 according to this embodiment comprises a water electrolysis module 2 and a degradation determination support device 40. The degradation determination support device 40 comprises a first calculation unit 42, a second calculation unit 44, and a third calculation unit 46.

[0072] According to this embodiment, the hydrogen production efficiency of the water electrolysis module can be stabilized, thereby stabilizing its function as an energy storage system, by promptly replacing the deteriorated water electrolysis module 2 or controlling the operating state according to the degree of deterioration. The deterioration of the water electrolysis module 2 can be determined based on the electrolysis voltage, which increases with deterioration. In conventional deterioration determination methods, the reaction conditions (temperature and current) of the water electrolysis module 2 were fixed to specific conditions, and the deterioration was determined from the voltage at that time. However, the operation of fixing the reaction conditions of the water electrolysis module 2 and measuring the voltage is different from the operation during normal operation of the water electrolysis module 2, and may interfere with hydrogen production by the water electrolysis module 2. Therefore, a method for determining the deterioration of the water electrolysis module 2 without interfering with the normal operation of the water electrolysis module 2 is desired.

[0073] In contrast, in this embodiment, a dataset of the water electrolysis module 2 during normal operation is acquired over time. This dataset includes the reaction condition values ​​substituted into the calculation formula and the measured voltage V used for coefficient correction. obs This includes the following. Next, the calculated voltage V obtained by substituting the reaction condition values ​​into the calculation formula is sim The measured voltage V obs The coefficients in each calculation formula are corrected to approximate the target value, and a set of parameters for each period is obtained. Next, the first and second comparison values ​​are calculated using the parameter set for the first period and the parameter set for the second period. Then, the degree of degradation of the water electrolysis module 2 is calculated according to the difference between the first and second comparison values.

[0074] The comparison value calculated by the method described above includes information about the deterioration state of the water electrolysis module 2 during that period. Furthermore, this comparison value is independent of the operating conditions of the water electrolysis module 2. Therefore, it is possible to estimate the deterioration state of the water electrolysis module 2 with higher accuracy while maintaining normal operation of the water electrolysis module 2 without performing any special operation for deterioration determination. Thus, the deterioration determination support device 40 and deterioration determination support method according to this embodiment can support the deterioration determination of the water electrolysis module 2 during normal operation. In addition, since the timing of replacement of the water electrolysis module 2 can be determined more accurately, the increase in effort and cost due to unnecessary replacement can be suppressed.

[0075] Furthermore, the water electrolysis module 2 of this embodiment includes an oxygen generation electrode 12, a hydrogen generation electrode 16, and a diaphragm 20 separating these electrodes. The calculation formula used to calculate the parameter group is the equilibrium potential u of the water electrolysis reaction and the activation overpotential η of the oxygen generation reaction. act , and the resistance overvoltage η of the diaphragm 20 IR Adding this, the calculated voltage V sim This is the formula for calculating it.

[0076] The embodiments may be specified by the items described below. [Item 1] Obtain a data set including a plurality of reaction condition values and voltages related to the water electrolysis reaction of the water electrolysis module (2) measured or derived from the measured values in the first period and the second period after the first period, and use the data set and a predetermined calculation formula to calculate a parameter group of the calculation formula for each period. The first calculation unit (42); A second calculation unit (44) that substitutes a predetermined reaction condition value into the calculation formula incorporating the parameter group to calculate a comparison target value for each period; Based on the difference between the first comparison target value calculated from the calculation formula incorporating the parameter group in the first period and the second comparison target value calculated from the calculation formula incorporating the parameter group in the second period, a third calculation unit (46) that calculates the degree of deterioration of the water electrolysis module (2). A deterioration determination support device (40). [Item 2] The water electrolysis module (2) has an oxygen generation electrode (12), a hydrogen generation electrode (16), and a diaphragm (20) that separates the oxygen generation electrode (12) and the hydrogen generation electrode (16). The calculation formula is an equation that adds the equilibrium potential (u) of the water electrolysis reaction, the activation overvoltage (η act ) of the oxygen generation reaction, and the resistance overvoltage (η IR ) of the diaphragm (20) to calculate the voltage (V sim ). The deterioration determination support device (40) according to Item 1. [Item 3] The comparison target value is any one of the voltage (V sim ), the activation overvoltage (η act ), and the resistance overvoltage (η IR ), or a combination of two or more. The deterioration determination support device (40) according to Item 2. [Item 4] Obtain a data set including a plurality of reaction condition values and voltages related to the water electrolysis reaction of the water electrolysis module (2) measured or derived from the measured values in the first period and the second period after the first period, and use the data set and a predetermined calculation formula to calculate a parameter group of the calculation formula for each period. The first calculation unit (42); The system comprises a fourth calculation unit that calculates the degree of deterioration of the water electrolysis module (2) based on the difference between at least one coefficient constituting a set of parameters in the first period and that coefficient in the second period. Deterioration determination support device (40). [Item 5] The first period is the period during which the water electrolysis module (2) is presumed to be in an undegraded state. A device (40) for supporting the determination of any of items 1 to 4. [Item 6] Water electrolysis module (2), A deterioration determination support device (40) according to any of items 1 to 5, Water electrolysis device (1). [Item 7] A dataset containing multiple reaction condition values ​​and voltages related to the water electrolysis reaction of the water electrolysis module (2) was acquired during the first period and the second period following the first period. Using the dataset and a predetermined formula, the parameters of the formula for each period are calculated. By substituting predetermined reaction condition values ​​into a calculation formula incorporating a set of parameters, the comparative values ​​for each period are calculated. This includes calculating the degree of degradation of the water electrolysis module (2) based on the difference between the first comparison value calculated from a formula incorporating the parameter set in the first period and the second comparison value calculated from a formula incorporating the parameter set in the second period. Deterioration determination support method. [Item 8] A renewable energy fluctuation absorption system equipped with a water electrolysis device (1) as described in item 6. [Item 9] A third calculation unit (46) calculates the replacement timing of the water electrolysis module (2) based on the degree of deterioration of the water electrolysis module (2), The system includes an alarm unit (48) that notifies the water electrolysis module (2) of the time when it is time to replace it. Maintenance system for water electrolysis module (2). [Item 10] A third calculation unit (46) calculates the degree of deterioration of the water electrolysis module (2), A driving support unit (50) that indicates the operating conditions of the water electrolysis module (2) based on the calculated degree of deterioration. A driving support system for the water electrolysis module (2).

Example

[0077] Hereinafter, embodiments of the present invention will be described. However, the embodiments are merely examples for preferably explaining the present invention and do not limit the present invention in any way.

[0078] 3 Nm 3 A water electrolysis operation test was carried out for 3 days using a PEM water electrolysis module of / h. FIG. 4(A) is a diagram showing the relationship between time and current in the water electrolysis operation test conducted in the example. As shown in FIG. 4(A), the current was kept constant during the water electrolysis operation test. Also, the first 40 minutes after the start of the water electrolysis operation test was set as the first period (k1), and the last 40 minutes before the end was set as the second period (k2). Parameter groups for each period were calculated using the data sets obtained in each of the first period and the second period, the voltage calculation formula, and the curve fitting method by the least squares method. <>

[0079] <> In the voltage calculation formula, equation (6) was used for the term of the activation overvoltage η act . The coefficient to be corrected among the coefficients related to the activation overvoltage η act was taken as the exchange current density i0. The charge transfer coefficient α and the activation energy E exc of electron transfer were substituted with literature values. α = 0.7, E exc = 53,000 J / mol. Also, equation (9) was used for the term of the resistance overvoltage η IR . The coefficient to be corrected among the coefficients related to the resistance overvoltage η IR was taken as the proton conductivity σ. The activation energy E pro of proton transfer was substituted with a literature value. E pro = 10,000 J / mol. <><>

[0080] <><> Substitute a predetermined reaction condition value into the voltage calculation formula incorporating the parameter groups generated for each period, and the voltage V sim (V1_ST,sim), activation overvoltage η act(V2_ST,sim) and resistive overvoltage η IR (V3_ST,sim) was calculated. The predetermined reaction conditions were set to a current of 1200A, a water temperature of 30°C, a hydrogen generation pressure of 0.6MPaG, and an oxygen generation pressure of 0.595MPaG. The resulting calculated voltage V sim , activation overpotential η act and resistive overvoltage η IR Based on this, the first degree of deterioration d1, the second degree of deterioration d2, and the third degree of deterioration d3 were calculated. The results are shown in Figure 4(B).

[0081] Figure 4(B) shows the corrected parameter set, various voltages, and degradation levels in the example. As shown in Figure 4(B), the activation overpotential η act The increase was approximately 10mV(V2_ST,sim(k2)-V2_ST,sim(k1)). Also, the resistive overvoltage η IR The increase was approximately 35 mV(V3_ST,sim(k2)-V3_ST,sim(k1)). The second degree of degradation d2 was 0.038, and the third degree of degradation d3 was 0.055. From these results, it was found that the deterioration of the diaphragm 20 progressed more rapidly than the deterioration of the catalyst layer 12a of the oxygen generation electrode 12 during the water electrolysis operation test. In summary, it was shown that the deterioration determination support device 40 and deterioration determination support method according to this disclosure can quantify the deterioration state of the water electrolysis module 2, and thus support deterioration determination. [Industrial applicability]

[0082] This invention can be used in a deterioration determination support device, a water electrolysis device, and a deterioration determination support method. [Explanation of symbols]

[0083] 1 Water electrolysis device, 2 Water electrolysis module, 12 Oxygen generation electrode, 16 Hydrogen generation electrode, 20 Diaphragm, 38 Sensor, 40 Degradation judgment support device, 42 First calculation unit, 44 Second calculation unit, 46 Third calculation unit.

Claims

1. A first calculation unit acquires a dataset including multiple reaction condition values ​​and measured voltages related to the water electrolysis reaction of a water electrolysis module, measured or derived from measured values ​​during a first period and a second period following the first period, and calculates a set of parameters for the calculation formula for each period using the dataset and a predetermined calculation formula. A second calculation unit calculates comparison values ​​for each period by substituting predetermined reaction condition values ​​into the calculation formula incorporating the aforementioned parameter group, The system includes a third calculation unit that calculates the degree of deterioration of the water electrolysis module based on the difference between a first comparison value calculated from a calculation formula incorporating the parameter group in the first period and a second comparison value calculated from a calculation formula incorporating the parameter group in the second period. The water electrolysis module comprises an electrode for generating oxygen, an electrode for generating hydrogen, and a diaphragm separating the oxygen-generating electrode and the hydrogen-generating electrode. The above calculation formula calculates the voltage by adding the equilibrium potential of the water electrolysis reaction, the activation overpotential of the oxygen evolution reaction, and the resistance overpotential of the diaphragm. The first calculation unit calculates a calculated voltage by substituting the reaction condition value into the calculation formula, corrects at least one coefficient included in the calculation formula so that the calculated voltage approaches the measured voltage, and calculates the parameter group including the corrected coefficient as a component. The second calculation unit substitutes predetermined reaction condition values ​​into the calculation formula incorporating the parameter group for the first period to calculate the first comparison target value, the calculated voltage (V ｓｉｍ 1) is calculated, and the predetermined reaction condition values ​​are substituted into the calculation formula incorporating the parameter group for the second period, and the calculated voltage (V) is used as the second comparison value. ｓｉｍ 2) is calculated, and the third calculation unit calculates (12): d1 = (V ｓｉｍ 2-V ｓｉｍ 1) / V ｓｉｍ Use 1 to calculate the first degree of deterioration (d1), The activation overvoltage (η ａｃｔ ), in the calculation formula incorporating the parameter group in the first period, is substituted with a predetermined reaction condition value, and the activation overvoltage (η ａｃｔ 1) as the first comparison target value is calculated. The activation overvoltage (η ａｃｔ ), in the calculation formula incorporating the parameter group in the second period, is substituted with the predetermined reaction condition value, and the activation overvoltage (η ａｃｔ 2) as the second comparison target value is calculated. The third calculation unit calculates the second degradation degree (d2) using the formula (13): d2 = (η ａｃｔ 2 - η ａｃｔ 1) / η ａｃｔ 1, and The second calculation unit calculates the resistance overvoltage (η) in the calculation formula incorporating the parameter group in the first period. ＩＲ Substitute the predetermined reaction condition value into the term of ) and obtain the resistance overvoltage (η) as the first comparison target value. ＩＲ 1) Calculate the resistance overvoltage (η) in the calculation formula incorporating the parameter group in the second period. ＩＲ Substitute the predetermined reaction condition value into the term of the second comparison target value, and obtain the resistance overvoltage (η ＩＲ 2) is calculated, and the third calculation unit calculates (14): d3 = (η ＩＲ 2-η ＩＲ 1) / η ＩＲ Perform at least one of the following: calculate the third degree of degradation (d3) using 1. Deterioration determination support device.

2. Performing two or more of the following: calculation of the first degree of deterioration (d1), calculation of the second degree of deterioration (d2), and calculation of the third degree of deterioration (d3). The deterioration determination support device according to claim 1.

3. The first period is the period during which the water electrolysis module is presumed to be in an undegraded state. A deterioration determination support device according to claim 1 or 2.

4. Water electrolysis module, A deterioration determination support device according to any one of claims 1 to 3, comprising Water electrolysis equipment.

5. A dataset is obtained that includes a plurality of reaction condition values ​​and measured voltages related to the water electrolysis reaction of the water electrolysis module, measured or derived from measured values ​​during a first period and a second period following the first period, Using the aforementioned dataset and a predetermined calculation formula, the parameter set of the calculation formula for each period is calculated. By substituting predetermined reaction condition values ​​into the calculation formula incorporating the aforementioned parameter group, the comparison values ​​for each period are calculated. This includes calculating the degree of deterioration of the water electrolysis module based on the difference between a first comparison value calculated from a calculation formula incorporating the parameter group in the first period and a second comparison value calculated from a calculation formula incorporating the parameter group in the second period. The water electrolysis module comprises an electrode for generating oxygen, an electrode for generating hydrogen, and a diaphragm separating the oxygen-generating electrode and the hydrogen-generating electrode. The above calculation formula calculates the voltage by adding the equilibrium potential of the water electrolysis reaction, the activation overpotential of the oxygen evolution reaction, and the resistance overpotential of the diaphragm. The calculation of the parameter group includes substituting the reaction condition values ​​into the calculation formula to calculate the calculated voltage, correcting at least one coefficient included in the calculation formula so that the calculated voltage approaches the measured voltage, and calculating the parameter group that includes the corrected coefficient as a component. In calculating the comparison value, a predetermined reaction condition value is substituted into the calculation formula incorporating the parameter group for the first period, and the calculated voltage (V) is used as the first comparison value. ｓｉｍ 1) is calculated, and the predetermined reaction condition values ​​are substituted into the calculation formula incorporating the parameter group for the second period, and the calculated voltage (V) is used as the second comparison value. ｓｉｍ 2) Calculate the above degree of deterioration, and in the calculation of the degree of deterioration, (12) equation: d1 = (V ｓｉｍ 2-V ｓｉｍ 1) / V ｓｉｍ Use 1 to calculate the first degree of deterioration (d1), In calculating the comparison value, the activation overvoltage (η) in the calculation formula incorporating the parameter group in the first period ａｃｔ Substitute the predetermined reaction condition value into the term ) and obtain the activation overpotential (η) as the first comparison value. ａｃｔ 1) Calculate the activation overvoltage (η) in the calculation formula incorporating the parameter group in the second period. ａｃｔ Substitute the predetermined reaction condition value into the term ) and obtain the activation overpotential (η) as the second comparison value. ａｃｔ 2) Calculate the above degree of deterioration, and in the calculation of the degree of deterioration, (13) equation: d2 = (η ａｃｔ 2-η ａｃｔ 1) / η ａｃｔ To calculate the second degree of deterioration (d2) using 1, and In calculating the comparison value, the resistance overvoltage (η) in the calculation formula incorporating the parameter group in the first period ＩＲ Substitute the predetermined reaction condition value into the term of ) and obtain the resistance overvoltage (η) as the first comparison target value. ＩＲ 1) Calculate the resistance overvoltage (η) in the calculation formula incorporating the parameter group in the second period. ＩＲ Substitute the predetermined reaction condition value into the term of the second comparison target value, and obtain the resistance overvoltage (η ＩＲ 2) Calculate the above degree of deterioration, and in the calculation of the degree of deterioration, (14) equation: d3 = (η ＩＲ 2-η ＩＲ 1) / η ＩＲ Perform at least one of the following: calculate the third degree of degradation (d3) using 1. Deterioration determination support method.

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