JP2019173082A - Hydrogen production system - Google Patents

Abstract

To provide a hydrogen production system capable of efficiently and stably produce hydrogen using surplus power from power generation by unstable renewable energy, utilizing respective advantages of a water electrolysis cell and an SOEC.SOLUTION: There is provided a hydrogen production system 10 comprising a water electrolysis cell 2 that produces hydrogen by electrolyzing water using surplus power (D) supplied from renewable energy power generation (SH) such as photovoltaic power generation and wind power generation, and an SOEC3 that produces hydrogen by electrolyzing steam. The surplus power (D) actually supplied according to a forecasted power condition obtained by forecasting a power condition of the surplus power (D) beforehand, is divided into stable power (D1) of which an amount is maintained approximately constant during specified time t0 and an unstable power (D2) of which an amount changes during the specified time t0, to supply the water electrolysis cell 2 with the unstable power (D2) and to supply the SOEC3 with the stable power (D1).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hydrogen production system, and more particularly to a hydrogen production system that efficiently produces hydrogen from surplus power of renewable energy power generation such as solar power generation and wind power generation.

  In recent years, renewable energy power generation facilities such as solar power generation and wind power generation have been introduced. However, renewable energy power generation tends to fluctuate depending on the geographical conditions, weather conditions, etc. of each region, and a large amount of surplus power is generated by subtracting the usage amount from the power generation amount of renewable energy power generation. As means for temporarily storing this surplus power, a method and apparatus for electrolyzing water with surplus power to produce hydrogen and storing energy in the hydrogen state are known. Water electrolysis cell systems and solid oxide electrolysis cell (SOEC) systems have been researched and developed as methods and apparatuses for efficiently producing hydrogen from electric power.

  For example, as an example of the water electrolysis cell system, Patent Document 1 includes a plurality of cell stacks (C101, C102, C103, C104) in which a plurality of water electrolysis cells are stacked as shown in FIG. A water electrolysis apparatus 101 having a stack electrically connected in series or in parallel with each other via switches (S1 to S12), a power supply means 102 for supplying power to the water electrolysis apparatus 101, and the water electrolysis A voltage control unit 103 that variably controls the voltage of power supplied to the apparatus 101; and the water and the water electrolysis apparatus 101 according to the power supplied to the water electrolysis apparatus 101 so that the voltage and current acting on each cell stack are within a predetermined range. A hydrogen production facility 100 including a stack number control unit 104 that selects the number of cell stacks used in the electrolysis apparatus 101 is disclosed.

  According to the above configuration, the water electrolysis apparatus 101 is configured such that the voltage and current acting on each cell stack (C101, C102, C103, C104) are within a predetermined range in accordance with the increase or decrease of the power supplied to the water electrolysis apparatus 101. Since the number of cell stacks used is selected, the voltage and current acting on each cell stack can be kept within the normal range. As a result, an increase in Joule loss can be suppressed and a decrease in energy conversion efficiency can be prevented.

JP 2005-126792 A

  However, in the case of the water electrolysis apparatus 101, for example, in alkaline water electrolysis, an electrolytic solution composed of an aqueous solution of about 20 to 30% potassium hydroxide or the like is used, but a high-temperature alkaline electrolytic solution is applied to many austenitic stainless steels. There were problems such as the occurrence of stress corrosion cracking. Therefore, in ordinary alkaline water electrolysis, an electrolytic cell of about 70 to 90 ° C. is used, and compared with SOEC that electrolyzes high temperature (usually 600 ° C. or higher) water vapor, 20 to 30 at the same power. There was a disadvantage that only a small amount of hydrogen could be produced.

  On the other hand, SOEC has an advantage that hydrogen can be produced more efficiently than a water electrolysis cell, but a thin film such as zirconium oxide modified with yttrium or the like is used as a solid electrolyte, and the electrolysis cell is made of a thin ceramic. For this reason, there has been a disadvantage that the electrolytic cell is easily cracked with respect to start / stop and sudden load fluctuations (surplus power fluctuations). On the other hand, the water electrolysis cell can use a diaphragm and an electrode excellent in durability, and has an advantage that it is strong against start / stop and sudden load fluctuation (surplus power fluctuation).

  The present invention has been made in order to solve the above-mentioned problems. While taking advantage of each of the water electrolysis cell and the SOEC, hydrogen is efficiently and stably generated from the surplus power of the renewable energy power generation that is likely to fluctuate. An object of the present invention is to provide a hydrogen production system that can be produced.

In order to solve the above problems, a hydrogen production system according to the present invention has the following configuration.
(1) A water electrolysis cell that electrolyzes water by surplus power supplied from renewable energy power generation such as solar power generation or wind power generation to produce hydrogen and an SOEC that electrolyzes water vapor to produce hydrogen A hydrogen production system,
The power status of the surplus power is predicted in advance, and the surplus power that is actually supplied based on the predicted power status is between a stable power that maintains a substantially constant amount of power for a predetermined time and a predetermined time. Separated into unstable power that fluctuates,
The unstable power is supplied to the water electrolysis cell, and the stable power is supplied to the SOEC.

  In the present invention, the power status of surplus power is predicted in advance, and the surplus power actually supplied based on the predicted power status is maintained at a constant power and a predetermined time during which the power amount is maintained substantially constant for a predetermined time. In this case, the water electrolysis cell is supplied with unstable power and the SOEC is supplied with stable power. Therefore, the SOEC to which stable power is supplied While increasing the amount of hydrogen produced, it is possible to reduce or avoid the start / stop of SOEC and load fluctuations, thereby suppressing failure of the electrolysis cell. On the other hand, a water electrolysis cell to which unstable power is supplied reduces hydrogen production per electric power, but is resistant to starting and stopping and load fluctuations, and can stably produce hydrogen without failure. As a result, by utilizing the advantages of the water electrolysis cell and the SOEC, hydrogen can be efficiently and stably produced from surplus power of renewable energy power generation. The water electrolysis cell may be an alkaline water electrolysis cell or a solid polymer electrolysis cell.

  Therefore, according to the present invention, there is provided a hydrogen production system capable of efficiently and stably producing hydrogen from surplus power of renewable energy power generation that is likely to fluctuate while taking advantage of each of the water electrolysis cell and SOEC. can do.

(2) In the hydrogen production system described in (1),
The renewable energy power generation is performed in a plurality of regions, and surplus power for each region is collected through a power system.

  In the present invention, renewable energy power generation is performed in a plurality of regions, and surplus power for each region is aggregated via the power system. Therefore, surplus power for renewable energy power generation in each region is determined by the weather conditions of each region, etc. However, the combined surplus power obtained by integrating these can increase the stable power and decrease the unstable power due to the smoothing effect. Therefore, it is possible to further increase the amount of hydrogen produced by SOEC supplied with stable power.

(3) In the hydrogen production system described in (2),
Predicting the power status of the surplus power based on the weather information of each region, and predetermining a reference line for separating the stable power and the unstable power from the predicted power status every predetermined time Features.

  In the present invention, the power situation of surplus power is predicted based on the weather information of each region, and a reference line for separating stable power and unstable power from the predicted power situation is determined in advance every predetermined time. Thus, the difference between the surplus power to be supplied and the surplus power that is actually supplied can be reduced, and the stable power can be maximized within the allowable operating range for the start / stop of the SOEC or load fluctuation. In other words, the stable power supplied to the SOEC is divided at predetermined intervals set within the allowable operating range of the SOEC based on the weather information of each region, and the reference line that separates the stable power and the unstable power is maximized. The limit can be raised. As a result, hydrogen can be produced more efficiently and stably from surplus power that varies depending on weather conditions.

(4) In the hydrogen production system described in (3),
A power separation device that separates the stable power and the unstable power from the surplus power, supplies the separated stable power to the SOEC, and supplies the separated unstable power to the water electrolysis cell; and the power Another power supply device connected to the separation device,
The power output from the power supply device is supplemented to the power separation device as supplementary power to compensate for the shortage of power below the reference line in the stable power.

  In the present invention, a power separation device that separates stable power and unstable power from surplus power, supplies the separated stable power to the SOEC, and supplies the separated unstable power to the water electrolysis cell, and the power separation device. And a power supply device connected thereto, and supplementing the power output from the power supply device as supplementary power to the power separation device to compensate for the shortage of power below the reference line in the stable power, so that the electrolytic cell of SOEC It is possible to further reduce the damage caused by power fluctuations to avoid the failure and increase the amount of hydrogen produced by SOEC more stably.

(5) In the hydrogen production system described in any one of (1) to (4),
It has a heat storage device that stores various types of exhaust heat,
Water vapor supplied to the SOEC is heated by heat stored in the heat storage device.

  In the present invention, a heat storage device that stores various types of exhaust heat is provided, and the steam that is supplied to the SOEC is heated by the heat stored in the heat storage device. Can be used effectively as a part or as a whole. Therefore, it is possible to efficiently and stably produce hydrogen from surplus power of renewable energy power generation while improving energy efficiency in the hydrogen production system. Here, various types of exhaust heat correspond to exhaust heat from solid oxide fuel cells (SOFCs) that generate electricity using hydrogen produced by this system, cogeneration exhaust heat, factory exhaust heat, etc. However, there is no particular limitation as long as it is exhaust heat that can be acquired from within the system or in the vicinity of the system.

  According to the present invention, there is provided a hydrogen production system capable of efficiently and stably producing hydrogen from surplus power of renewable energy power generation that is likely to fluctuate, while taking advantage of each advantage of a water electrolysis cell and SOEC. Can do.

It is a system configuration conceptual diagram of a hydrogen production system concerning this embodiment. In the hydrogen production system shown in FIG. 1, it is the conceptual diagram which separated the surplus electric power actually supplied based on the estimated electric power situation into the stable electric power and the unstable electric power. FIG. 2 is a conceptual diagram of a configuration of a control device illustrated in FIG. 1. In the hydrogen production system shown in FIG. 1, it is the conceptual diagram which concentrated the surplus electric power of a different area on the power separator, and isolate | separated the synthetic | combination surplus power into the stable electric power and the unstable electric power. (A) shows surplus power in region A, (B) shows surplus power in region B, and (C) combines surplus power in region A and surplus power in region B. Indicates the combined surplus power. In the hydrogen production system shown in FIG. 1, it is a conceptual diagram in which stable power supplied from the power separation device to the SOEC based on weather information is divided by time within the allowable operating range of the SOEC. In the hydrogen production system shown in FIG. 1, it is the conceptual diagram which supplemented the electric power stored in the storage battery to the power separator, and supplemented the shortage of the electric power which is less than the reference line in stable electric power. In the hydrogen production system shown in FIG. 1, the combined surplus power to be aggregated in the power separator is calculated based on the weather information of each region, and the stable power supplied from the power separator to the SOEC is adjusted within the allowable operating range of the SOEC. FIG. FIG. 2 is a conceptual diagram of a system configuration in which a solid oxide fuel cell and a heat storage device that stores exhaust heat of the solid oxide fuel cell are added to the hydrogen production system shown in FIG. 1. It is a schematic block diagram of the hydrogen production facility described in patent document 1.

  Next, a hydrogen production system according to an embodiment of the present invention will be described in detail with reference to the drawings. Below, the structure of this hydrogen production system is demonstrated in detail, and the operating method is demonstrated.

<Configuration and operation method of this hydrogen production system>
The configuration and operation method of the hydrogen production system according to this embodiment will be described with reference to FIGS. FIG. 1 is a conceptual diagram of a system configuration of a hydrogen production system according to the present embodiment. FIG. 2 is a conceptual diagram in which the surplus power actually supplied based on the predicted power situation is separated into stable power and unstable power in the hydrogen production system shown in FIG. FIG. 3 shows a conceptual diagram of the configuration of the control device shown in FIG. FIG. 4 shows a conceptual diagram in which the surplus power in different regions is collected in the power separation device and the combined surplus power is separated into stable power and unstable power in the hydrogen production system shown in FIG. (A) shows surplus power in region A, (B) shows surplus power in region B, and (C) combines surplus power in region A and surplus power in region B. Indicates the combined surplus power. FIG. 5 shows a conceptual diagram in which the stable power supplied from the power separation device to the SOEC based on the weather information is divided into time intervals within the allowable operating range of the SOEC in the hydrogen production system shown in FIG. FIG. 6 shows a conceptual diagram in the hydrogen production system shown in FIG. 1 in which power stored in the storage battery is supplemented to the power separation device to compensate for the shortage of power below the reference line in stable power. In the hydrogen production system shown in FIG. 1, in the hydrogen production system shown in FIG. 1, the surplus power to be aggregated in the power separator is calculated based on the weather information of each region, and the stable power supplied from the power separator to the SOEC is allowed to operate the SOEC. The flowchart figure which adjusts within the range is shown.

  As shown in FIGS. 1, 2, and 3, the hydrogen production system 10 according to this embodiment uses water generated by surplus power (D) supplied from renewable energy power generation (SH) such as solar power generation or wind power generation. A hydrogen production system comprising a water electrolysis cell 2 that electrolyzes hydrogen to produce hydrogen and an SOEC 3 that electrolyzes water vapor to produce hydrogen, predicting the power status of surplus power (D) in advance, The surplus power (D) that is actually supplied based on the predicted power status varies between the stable power (D1) in which the power amount is maintained substantially constant during the predetermined time t0 and the predetermined time t0. The power is separated into unstable power (D2), the unstable power (D2) is supplied to the water electrolysis cell 2, and the stable power (D1) is supplied to the SOEC3.

  Here, as a method for predicting the power status of surplus power (D) in advance, there is a method based on actual data of the previous day or the same period of the previous year as well as a method based on weather information described later. In addition, since a certain amount of error may occur between the power state of the surplus power (D) actually supplied and the predicted power state, the stable power (D1) and the unstable power (D2) are separated. The reference line KL is preferably set based on the lower limit value during the predetermined time t0 of the predicted power situation. However, the stable power (D1) may include a minute power fluctuation component (unstable part), or the unstable power (D2) may include a power stable component (stable part).

  Further, in the present hydrogen production system 10, surplus power (D) supplied from renewable energy power generation (SH) is separated into stable power (D1) and unstable power (D2), and unstable power (D2). Is supplied to the water electrolysis cell 2 and stable power (D1) is supplied to the SOEC 3, and a control device 7 is provided for controlling the power separation device 1, the water electrolysis cell 2, and the SOEC 3 respectively.

  For example, the control device 7 has the following configuration so as to predict the power state of surplus power (D) in advance and supply stable power (D1) from the power separation device 1 to the SOEC 3 based on the predicted power state. ing. That is, as shown in FIG. 3, the control device 7 divides the voltage and current waveforms in the current or past surplus power information provided from the power separation device 1 by a minute time Δt and converts them into digital voltages, respectively, to instantaneous voltage A / D conversion unit 71 that obtains instantaneous current obtained by multiplying them and instantaneous power that is multiplied by them, and instantaneous power that becomes the minimum value within a predetermined time t0 among the instantaneous powers cut out by A / D conversion unit 71 The storage unit 72 that stores the amplitude value d1 of ΔD as the reference line KL, and the surplus power (D that is actually supplied from the power system 4 based on the data of the predetermined time t0 and the reference line KL stored in the storage unit 72) ) Is instructed to the power separating apparatus 1 to separate the stable power (D1) composed of power components less than the reference line KL into the unstable power (D2) composed of power components greater than the reference line KL; With ing.

  As shown in FIGS. 1 and 3, the power separation device 1 supplies unstable power (D2) to the water electrolysis cell 2 based on the operation instruction of the operation instruction unit 73, and supplies stable power (D1). Supply to SOEC3. The control device 7 includes a weather information analysis unit 74 that analyzes weather information. Further, the storage unit 72 is supplied with data of the allowable operation range of the SOEC 3 with respect to start / stop and load fluctuation (for example, the minimum time interval for load switching, the allowable load fluctuation rate, etc.) and the power system 4 to the power separation device 1. The past performance data of surplus power (D) in each area is stored together with weather information.

  The water electrolysis cell 2 is an electrolysis cell that electrolyzes water at room temperature to about 80 ° C., and may be an alkaline water electrolysis cell or a solid polymer electrolysis cell. In the case of an alkaline water electrolysis cell, for example, a 20-30% potassium hydroxide aqueous solution is used as an electrolytic solution heated to room temperature or 70-80 ° C., and a separator made of a porous material or the like and nickel An anode electrode (anode) made of a system material or the like and a cathode electrode (cathode) made of a nickel or iron material or the like can be used. The water electrolysis cell 2 operates based on the operation instruction from the operation instruction unit 73.

  In the case of a polymer electrolyte cell, for example, pure water is heated to room temperature or about 60 to 80 ° C. and used, and consists of an electrolyte membrane made of a perfluorocarbon resin material and an iridium oxide material. An anode electrode (anode) and a cathode electrode (cathode) made of a platinum-based material or the like can be used. When unstable power (D2) is supplied between the anode electrode (anode) and the cathode electrode (cathode), water receives electrons on the cathode side to generate hydrogen. The oxide ions generated at that time move in the electrolytic solution or the inside of the electrolyte membrane to the anode side and emit electrons to generate oxygen.

  In addition, unlike alkaline water electrolysis and solid polymer electrolysis, SOEC3 is an electrolysis cell that electrolyzes water vapor heated to a high temperature of about 600 to 800 ° C. using a solid oxide electrolyte. In addition, in SOEC3, for example, zirconium oxide (YSZ) stabilized with yttrium oxide ion conductor is used as an electrolyte membrane, and an anode electrode (anode) made of lanthanum strontium oxide or the like and a composite of nickel and YSZ A cathode electrode (cathode) made of nickel cermet or the like, which is a body, can be used. When stable power (D1) is supplied between the anode electrode (anode) and the cathode electrode (cathode), the water vapor supplied to the cathode side receives electrons to generate hydrogen. The oxide ions generated at that time move inside the electrolyte membrane to the anode side and emit electrons to generate oxygen.

  The operation of the SOEC 3 is performed based on the operation instruction of the operation instruction unit 73. However, since it is a high-temperature electrochemical reaction, it takes several hours to start from a stop state and reach a steady state in which hydrogen production is performed. In view of the particularity that ceramics, which is the main material of the electrolysis cell, are easily affected by the thermal cycle, it is basically preferable to operate continuously, unless it is necessary to stop the operation by periodic inspection. Further, when the SOEC 3 is restarted after the operation is stopped, it is preferable to first supply electric power from the commercial system to the SOEC 3 as a trial operation, and shift to full-scale operation of the hydrogen production system 10 when the operation is stabilized. .

  The hydrogen production system 10 further includes a hydrogen storage device 5 that stores hydrogen generated at the cathode electrode (cathode) of the water electrolysis cell 2 and hydrogen generated at the cathode electrode (cathode) of the SOEC 3. Examples of the hydrogen storage method of the hydrogen storage device 5 include a method of storing hydrogen in a tank in a high-pressure gas state, a method of storing hydrogen by storing it in a hydrogen storage alloy (for example, titanium magnesium, nickel magnesium, etc.), and the like. is there.

  In addition, as shown in FIG. 1, renewable energy power generation (SH) is performed in a plurality of regions (region A, region B, region C, region D, etc.), and surplus power (D) for each region is supplied to the power system 4. It is preferable that the power is separated into the power separation device 1 via For example, as shown in FIG. 4, the surplus power (DA, DB) of renewable energy power generation (SH) in each region (region A, region B) may vary depending on the geographical conditions, weather conditions, etc. of each region. Although there are many, the combined surplus power (DC) obtained by consolidating these into the power separation device 1 can increase the combined stable power (D1C) from the sum of the stable power (D1A, D1B) in each region due to the smoothing effect. In addition, the combined unstable power (D2C) can be reduced from the sum of unstable power (D2A, D2B) in each region. The power system 4 can use an existing power transmission / distribution system.

  In addition, as shown in FIGS. 1, 3, 5, and 7, the power status of surplus power (D) is predicted based on the weather information of each region, and the stable power (D11) and the unstabilized power (D11) are determined from the predicted power status. The reference lines (KL1, KL2, KL3, KL4) that separate the stable power (D21) are preferably determined in advance for each predetermined time (t1, t2, t3, t4). For example, according to the steps shown in FIG.

  That is, as the first step S1, weather information of each region (region A, region B, region C, region D, etc.) is input to the weather information analysis unit 74 of the control device 7 via the Internet or the like. Here, the weather information differs depending on the type of renewable energy power generation (SH). For example, in the case of solar power generation, information such as “sunshine, cloudy, rain” related to sunshine hours or sunshine hours is applicable. In the case of wind power generation, information such as average wind speed and direction is applicable. The meteorological information analysis unit 74 converts the meteorological information into an index that correlates with the power generation amount and consumption amount of the renewable energy power generation (SH). A sensor for detecting weather information in each region may be attached to a renewable energy power generation facility in each region.

  Next, as a second step S2, the meteorological information analysis unit 74 predicts surplus power (D) for each region from past performance data based on the indexed weather information, and predicts surplus power for each region. Estimate the combined surplus power. Further, as the third step S3, the meteorological information analysis unit 74 sets a predetermined power so as to maximize the stable power (D11) within the allowable operating range with respect to the start / stop of the SOEC3 or the load fluctuation with respect to the calculated surplus power. Times (t1, t2, t3, t4) and reference lines (KL1, KL2, KL3, KL4) are determined and notified to the driving instruction unit 73. The predetermined time (t1, t2, t3, t4) for maintaining the stable power (D11) substantially constant can be set for each reference line (KL1, KL2, KL3, KL4) proportional to the load of the SOEC3.

  Next, as 4th step S4, the driving | operation instruction | indication part 73 and predetermined time (t1, t2, t3, t4) and the reference lines (KL1, KL2, and the like) which distinguish stable electric power (D11) and unstable electric power (D21). KL3 and KL4) are instructed to the power separation device 1 and the operation of the SOEC 3 and the water electrolysis cell 2 is instructed. Further, as the fifth step S5, the power separation device 1 is supplied from the power system 4 based on the designated predetermined time (t1, t2, t3, t4) and the reference line (KL1, KL2, KL3, KL4). The surplus power (D) is separated into stable power (D11) and unstable power (D21), stable power (D11) is supplied to the SOEC 3, and unstable power (D21) is supplied to the water electrolysis cell 2. The SOEC 3 produces hydrogen with stable power, and the water electrolysis cell 2 produces hydrogen with unstable power.

  In the operation of the SOEC 3, it is preferable that the power level for a predetermined time is basically determined according to the prediction in advance and is made to operate at a constant level with respect to the determined power level so as to avoid the adverse effects of sudden load fluctuations. Therefore, as shown in FIG. 5, even when the stable portion of the actual surplus power (D) exceeds the predicted reference lines (KL3, KL4), the stable power (D11) supplied from the power separation device 1 to the SOEC 3 ) Is not changed. In this case, the unstable power (D21) including the stable portion exceeding the reference lines (KL3, KL4) is supplied to the water electrolysis cell 2 in principle. However, a part or all of the surplus power (D) exceeding the reference lines (KL3, KL4) may be supplied to the storage battery 6 described later. Further, the predetermined time (t1, t2, t3, t4) for predicting the stable portion of surplus power (D) and the reference lines (KL1, KL2, KL3, KL4) may be reviewed every day, month or season. You may go every time.

  As shown in FIG. 1 and FIG. 6, the power separation device 1 is connected to a storage battery 6 that can be charged and discharged as another power supply device, and the power stored in the storage battery 6 is supplemented with power (D3). It is preferable to supplement the power separation device 1 to compensate for the shortage of power below the reference line KL5 in the stable power (D12). The control device 7 gives an instruction to replenish the power separating device 1 with the power stored in the storage battery 6. Here, the shortage of power to be replenished means an unstable portion of power below the reference line KL5, but is not necessarily near the lower limit value of surplus power (D) shown in FIG. For example, for each reference line (KL1, KL2, KL3, KL4) shown in FIG. 5, the power stored in the storage battery 6 is supplemented so that the unstable portion of the surplus power (D) does not fall below each reference line. It is preferable to replenish the power separation device 1 as (D3). In addition, the storage battery 6 can use a well-known lithium ion secondary battery.

  In addition, the A / D conversion unit 71 of the control device 7 constantly monitors the change of the actual surplus power (D) from the surplus power information provided from the power separation device 1, and the stable portion of the surplus power (D) or It is determined whether the unstable part is above or below the reference line KL. As shown in FIG. 5, when the stable portion of the surplus power (D) exceeds the reference lines KL3 and KL4, and the charging state of the storage battery 6 is equal to or lower than the charging upper limit, the A / D conversion unit 71 The operation instructing unit 73 that has received the determination instructs the power separation device 1 to preferentially supply power to the storage battery 6. On the other hand, when it is not necessary to charge the storage battery 6, the operation instruction unit 73 of the control device 7 generates unstable power (D21) including a stable portion of surplus power (D) that exceeds the reference lines KL3 and KL4. The power separator 1 is instructed to supply the water electrolysis cell 2.

  Next, another hydrogen production system 10B according to the present embodiment will be described with reference to FIG. FIG. 8 shows a conceptual diagram of a system configuration in which a solid oxide fuel cell and a heat storage device for storing exhaust heat of the solid oxide fuel cell are added to the hydrogen production system shown in FIG.

  As shown in FIG. 8, the other hydrogen production system 10 </ b> B preferably includes a heat storage device 9 that stores various types of exhaust heat, and heats the steam supplied to the SOEC 3 by the heat stored in the heat storage device 9. Specifically, in addition to the hydrogen production system 10 described above, a solid oxide fuel cell (SOFC) 8 that generates power using hydrogen stored in the hydrogen storage device 5, and a solid oxide type A heat storage device 9 that stores the exhaust heat of the fuel cell (SOFC) 8 may be provided, and steam supplied to the SOEC 3 may be heated by heat stored in the heat storage device 9. In addition, about the structure which is common in the hydrogen production system 10 mentioned above, the same code | symbol is attached | subjected and the description is omitted here.

  That is, the solid oxide fuel cell (SOFC) 8 generates reaction heat when it generates power using the hydrogen stored in the hydrogen storage device 5. This reaction heat is recovered as exhaust heat and stored in the heat storage device 9. By heating the water vapor supplied to the SOEC 3 by the heat stored in the heat storage device 9, the thermal energy generated when the solid oxide fuel cell (SOFC) 8 generates power is heated to supply the water vapor supplied to the SOEC 3. The energy efficiency of the entire hydrogen production system can be improved.

  As the solid oxide fuel cell (SOFC) 8 and the heat storage device 9, known ones can be used. In addition to the exhaust heat of the solid oxide fuel cell (SOFC) 8, various exhaust heat includes exhaust heat (for example, cogeneration exhaust heat, factory exhaust heat, etc.) that can convert at least water into water vapor at about 120 ° C. If the exhaust heat can be acquired from within the system or the vicinity of the system, there is no particular limitation.

<Effect>
As described above in detail, according to the hydrogen production systems 10 and 10B according to the present embodiment, the power state of surplus power (D) is predicted in advance, and actually supplied based on the predicted power state. The amount of power fluctuates between the stable power (D1, D11, D12) in which the surplus power (D) is maintained substantially constant for a predetermined time (t0 to t4) and the predetermined time (t0 to t4). It is separated into unstable power (D2, D21, D22), unstable power (D2, D21, D22) is supplied to the water electrolysis cell 2, and stable power (D1, D11, D12) is supplied to the SOEC3. Since it is supplied, SOEC3 to which stable power (D1, D11, D12) is supplied increases the amount of hydrogen produced per electric power, while avoiding start-stop and load fluctuations of SOEC3 and suppressing failure of the electrolysis cell (SOEC3) it can. On the other hand, the water electrolysis cell 2 to which unstable power (D2, D21, D22) is supplied is resistant to start-up and load fluctuations, although the amount of hydrogen produced per electric power is reduced. Can be manufactured. As a result, hydrogen can be efficiently and stably produced from surplus power (D) of renewable energy power generation (SH) by taking advantage of the advantages of water electrolysis cell 2 and SOEC 3.

  Therefore, according to the present embodiment, hydrogen is efficiently and stably produced from surplus power (D) of renewable energy power (SH) that is likely to fluctuate, while taking advantage of each of the advantages of the water electrolysis cell 2 and the SOEC 3. A hydrogen production system 10, 10 </ b> B that can be provided can be provided.

  Further, according to the present embodiment, renewable energy power generation (SH) is performed in a plurality of regions (region A, region B, region C, region D, etc.), and surplus power (D) for each region is supplied to the power grid 4. The surplus power (D) of renewable energy power generation (SH) in each region is often different depending on the weather conditions of each region, etc., but the combined surplus power (DC) that aggregates these is The leveling effect can increase the stable power (D1C) and decrease the unstable power (D2C). Therefore, the amount of hydrogen produced by the SOEC 3 to which the stable power (D1C) is supplied can be further increased.

  Further, according to the present embodiment, the power status of surplus power (D) is predicted based on the weather information of each region (region A, region B, region C, region D, etc.), and stable power is determined from the predicted power status. Since the reference lines (KL1, KL2, KL3, KL4) for separating (D11) and the unstable power (D21) are determined in advance for each predetermined time (t1, t2, t3, t4), the surplus power to be predicted (D ) And the surplus power (D) actually supplied can be reduced, and the stable power (D11) can be maximized within the allowable operating range with respect to the start / stop of the SOEC 3 or load fluctuation. That is, the stable power (D11) to be supplied to the SOEC 3 is divided and divided every predetermined time (t1, t2, t3, t4) set within the allowable operating range of the SOEC 3 based on the weather information of each region. The reference lines (KL1, KL2, KL3, KL4) that separate (D11) and the unstable power (D21) can be increased to the maximum. As a result, hydrogen can be produced more efficiently and stably from surplus power (D) that varies depending on weather conditions.

  Further, according to the present embodiment, the stable power (D12) and the unstable power (D22) are separated from the surplus power (D), the separated stable power (D12) is supplied to the SOEC 3, and the separated unstable power (D12) is supplied. The power separation device 1 that supplies (D22) to the water electrolysis cell 2 and another power supply device 6 connected to the power separation device 1 are provided, and the power separation device 1 is supplemented with the power output from the power supply device 6 Replenished as power (D3) to compensate for the shortage of power below the reference line KL5 in stable power (D12), thus reducing damage caused by power fluctuations to the electrolytic cell of SOEC3 and avoiding its failure, The amount of hydrogen produced by the SOEC 3 can be increased more stably.

  Further, according to the present embodiment, the heat storage device 9 that stores various types of exhaust heat is provided, and the water vapor that is supplied to the SOEC 3 is heated by the heat stored in the heat storage device 9, so the water vapor that supplies various types of exhaust heat energy to the SOEC 3 is supplied. It can be effectively used as a part or all of the heat energy to be heated. Therefore, hydrogen can be efficiently and stably produced from surplus power (D) of renewable energy power generation (SH) while improving energy efficiency in the hydrogen production system 10B.

<Modification>
The embodiment described above can be changed without changing the gist of the present invention. For example, according to the present embodiment, the power separation device 1 is connected to the storage battery 6 that is configured to be chargeable / dischargeable as another power supply device, and the power stored in the storage battery 6 is used as supplementary power (D3). The separation device 1 is replenished to compensate for the shortage of power below the reference line KL5 in the stable power (D12). However, the device for replenishing supplementary power (D3) to the power separation device 1 is not necessarily limited to the storage battery 6. For example, another power generation facility is connected to the power separation device 1, and the power generation facility generates power. You may comprise so that electric power may be supplemented to the power separation apparatus 1 as supplementary electric power (D3), and the shortage of the electric power which is less than the reference line KL5 in stable electric power (D12) may be supplemented.

  The present invention can be used, for example, as a hydrogen production system that efficiently produces hydrogen from surplus power of renewable energy power generation such as solar power generation and wind power generation.

1 Power separation device 2 Water electrolysis cell 3 SOEC
4 Power system 5 Hydrogen storage device 6 Storage battery (other power supply devices)
7 Control device 8 Solid oxide fuel cell 9 Heat storage device 10, 10B Hydrogen production system D Surplus power (surplus power)
DC combined surplus power (combined surplus power)
D1, D11, D12 Stable power D2, D21, D22 Unstable power D3 Replenishment power SH Renewable energy generation t0, t1, t2 Predetermined time t3, t4 Predetermined time

Claims (5)

Hydrogen production comprising a water electrolysis cell that electrolyzes water with surplus power supplied from renewable energy power generation such as solar power generation and wind power generation to produce hydrogen and SOEC that electrolyzes water vapor to produce hydrogen A system,
The power status of the surplus power is predicted in advance, and the surplus power that is actually supplied based on the predicted power status is between a stable power that maintains a substantially constant amount of power for a predetermined time and a predetermined time. Separated into unstable power that fluctuates,
The hydrogen production system, wherein the unstable power is supplied to the water electrolysis cell, and the stable power is supplied to the SOEC. The hydrogen production system according to claim 1,
The hydrogen production system characterized in that the renewable energy power generation is performed in a plurality of regions, and surplus power for each region is collected through a power system. In the hydrogen production system according to claim 2,
Predicting the power status of the surplus power based on the weather information of each region, and predetermining a reference line for separating the stable power and the unstable power from the predicted power status every predetermined time Characteristic hydrogen production system. In the hydrogen production system according to claim 3,
A power separation device that separates the stable power and the unstable power from the surplus power, supplies the separated stable power to the SOEC, and supplies the separated unstable power to the water electrolysis cell; and the power Another power supply device connected to the separation device,
A hydrogen production system, wherein the power output from the power supply device is supplemented to the power separation device as supplementary power to compensate for a shortage of power below the reference line in the stable power. In the hydrogen production system according to any one of claims 1 to 4,
It has a heat storage device that stores various types of exhaust heat,
A hydrogen production system, wherein water vapor supplied to the SOEC is heated by heat stored in the heat storage device.

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