Energy system

Abstract

To effectively use exhaust heat generated through an operation of a water electrolytic device while maintaining a temperature boundary layer of a hot water storage tank layer in an energy system having the water electrolytic device.SOLUTION: An energy system includes: a water electrolytic device; a water circuit that acquires heat generated through an operation of the water electrolytic device; and a hot water storage tank. In the hot water storage tank, an upper part thereof stores water in a first temperature region having a temperature equal to or higher than a predetermined temperature, and a lower part thereof stores water in a second temperature region having a temperature lower than the first temperature region. The water in the first temperature region and the water in the second temperature region are contiguous. Water in the water circuit supplied from a lower outlet is heated by using heat generated through the operation of the water electrolytic device, and the water in the water circuit is returned to the hot water storage tank via either an upper inlet or a lower inlet on the basis of a temperature of the water in the water circuit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an energy system. [Background technology]

[0002] In recent years, efforts to achieve the Sustainable Development Goals (SDGs) have been expanding. In response, energy systems that utilize renewable energy sources such as solar, wind, and geothermal power have been attracting attention, replacing the traditional method of generating electricity using fossil fuels such as oil, coal, and liquefied natural gas.

[0003] In this type of energy system, the amount of power generated fluctuates greatly depending on factors such as weather, season, and location. Furthermore, the power consumption of the consumer (load), such as homes and stores, also fluctuates. This can result in a surplus or shortage of power depending on the balance between power generation and power consumption. Therefore, efforts have recently been made to stabilize the power supply using fuel cells and water electrolysis devices. Patent Document 1 discloses a system that provides a stable power supply by controlling energy using fuel cells and water electrolysis devices.

[0004] Furthermore, Patent Document 2 discloses an energy control method in which water is heated using heat generated when a fuel cell generates electricity and stored in a hot water storage tank. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2019 / 103059 [Patent Document 2] Japanese Patent Publication No. 2020-099130 Summary of the Invention [Problem to be solved by the invention]

[0006] In a fuel cell cogeneration system, a temperature boundary layer is maintained in the hot water storage tank, taking advantage of the difference in specific gravity between high-temperature and low-temperature water, preventing temperature drops due to convection and storing high-temperature water in the upper layer.

[0007] On the other hand, from the perspective of durability, it is desirable to operate a water electrolysis device at a low temperature. In this case, the temperature generated during operation of the water electrolysis device is low, making it difficult to utilize exhaust heat. If exhaust heat is used to heat water as in the past, low-temperature water slightly heated by the heat generated during operation of the water electrolysis device will flow into the upper layer of the hot water storage tank. The mixing of the low-temperature water will lower the temperature of the water in the high-temperature layer, making it impossible to maintain the thermal boundary layer, and the high-temperature water will become unusable. [Means for solving the problem]

[0008] The present invention has been made in view of the above problems, and one of its objects is to effectively utilize the waste heat generated by the operation of the water electrolysis device in an energy system equipped with a water electrolysis device while maintaining the temperature boundary layer in the hot water storage tank.

[0009] According to one embodiment of the present invention, there is provided an energy system including: a water electrolysis device that generates hydrogen using electric power; a water circuit that acquires heat generated by operation of the water electrolysis device; and a hot water storage tank having an upper inlet that receives water supplied from the water circuit, an upper outlet that is located in the upper part and different from the upper inlet and discharges water, a lower outlet that is located in the lower part and supplies water to the water circuit, and a lower inlet that is located in the lower part and different from the lower outlet and receives water supplied from the water circuit, wherein the hot water storage tank stores water in a first temperature range that is equal to or higher than a predetermined temperature in the upper part and stores water in a second temperature range that is lower than the first temperature range in the lower part, the water in the first temperature range and the water in the second temperature range being arranged continuously, and the water in the water circuit that is supplied from the lower outlet is heated by heat generated by operation of the water electrolysis device, and the water in the water circuit is returned to the hot water storage tank via either the upper inlet or the lower inlet based on the temperature of the water in the water circuit.

[0010] According to this aspect, the water in the hot water storage tank can be heated using the exhaust heat from the water electrolysis device.

[0011] The above energy system may further include a heater that heats the water in the heated water circuit to the first temperature range.

[0012] According to this aspect, since water heated by exhaust heat is used, the amount of energy required to heat the water by the heater can be reduced.

[0013] In the above energy system, the water circuit may include a thermostatic valve that switches the flow path of the water circuit to guide water to either the upper inlet or the lower inlet based on the temperature of the heated water in the water circuit.

[0014] According to this aspect, by using a thermostat valve, it is possible to easily maintain the temperature boundary layer in the hot water storage tank layer, while effectively utilizing the waste heat generated by the operation of the water electrolysis device.

[0015] In the present invention, the term "temperature boundary layer" refers to a layer in a hot water storage tank where high-temperature water is located at the top (first temperature region) and low-temperature water is located at the bottom (second temperature region), creating a large temperature gradient due to the nature of water, which has a different specific gravity depending on the temperature. The water in the hot water storage tank is not physically or thermally isolated within a single space, and the first and second temperature regions are continuous. The first and second temperature regions may each have a non-uniform temperature distribution within the region. Because water movement may occur within the hot water storage tank due to the addition and removal of water, the term does not necessarily refer to a statically stable state of temperature distribution. In contrast, states in which the formation of the above-mentioned different temperature regions is disrupted due to convection occurring within the hot water storage tank, etc., are excluded.

[0016] In the above energy system, the hot water storage tank may include a bottom and a side at the lower part, the lower inlet may be provided at the side, and the lower outlet may be provided between the lower inlet and the bottom.

[0017] According to this aspect, it is possible to prevent low-temperature water in the hot water storage tank from flowing upward.

[0018] In the above energy system, the hot water storage tank may further include a city water inlet, and the city water inlet may be provided below the lower inlet.

[0019] According to this aspect, it is possible to prevent the temperature boundary layer inside the tank from being disturbed by city water, which is at a lower temperature than the water entering from the lower inlet.

[0020] The above energy system may further include a control device that controls the return of water to the water circuit from either the upper inlet or the lower inlet based on the temperature of the water in the water circuit.

[0021] According to this aspect, by using the control device, the temperature of the water in the water circuit can be determined and the path for returning the water to the hot water storage tank can be stably controlled.

[0022] In the above energy system, the water circuit includes a pump that adjusts the flow rate of water in the water circuit, and when the temperature of the heated water in the water circuit returning from the lower inlet to the hot water storage tank is higher than a predetermined temperature, the control device may control the operation of the pump to increase the amount of water flowing from the hot water storage tank into the water circuit.

[0023] According to this aspect, it is possible to reduce the temperature change in the low temperature layer of the hot water storage tank.

[0024] The above energy system may further include a pump arranged in the water circuit either upstream or downstream of the water electrolysis device, and a temperature sensor arranged downstream of the water electrolysis device, wherein the control device may control the pump to reduce the amount of water flowing into the water circuit when the temperature sensor detects a temperature equal to or lower than a predetermined temperature.

[0025] According to this aspect, it is possible to prevent the temperature of the water from dropping and reduce the amount of heat to be generated by the heater. [Effects of the Invention]

[0026] According to one embodiment of the present invention, in an energy system equipped with a water electrolysis device, it is possible to effectively utilize the waste heat generated by the operation of the water electrolysis device while maintaining the temperature boundary layer of the hot water storage tank. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is an overall configuration diagram of an energy system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing heat exchange between a water circuit and a water electrolysis device. [Figure 3] FIG. 4 is a schematic diagram showing the operation of a thermostat valve. [Figure 4]FIG. 4 is a schematic diagram showing the operation of a thermostat valve. [Figure 5] 1 is an overall configuration diagram of an energy system according to an embodiment of the present invention. [Figure 6] 1 is an overall configuration diagram of an energy system according to an embodiment of the present invention. [Figure 7] FIG. 2 is a block diagram of a control device according to an embodiment of the present invention. [Figure 8] FIG. 2 is a functional block diagram of a control unit according to an embodiment of the present invention. [Figure 9] 1 is a flowchart of a control method according to an embodiment of the invention. [Figure 10] 1 is an overall configuration diagram of an energy system according to an embodiment of the present invention. [Figure 11] 1 is a flowchart of a control method according to an embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, each embodiment of the invention disclosed in this application will be described with reference to the drawings. However, the present invention can be embodied in various forms without departing from the spirit of the invention, and should not be construed as being limited to the description of the embodiments exemplified below.

[0029] In the drawings referred to in this embodiment, identical parts or parts having similar functions are denoted by the same or similar reference numerals (reference numerals with A, B, etc. added). Also, for convenience of explanation, the dimensional ratios in the drawings may differ from the actual ratios, and some components may be omitted from the drawings.

[0030] First Embodiment (1-1. Energy System 1 Configuration) Hereinafter, the energy system according to this embodiment will be described with reference to the drawings.

[0031] Fig. 1 is an overall configuration diagram of an energy system 1 according to this embodiment. As shown in Fig. 1, the energy system 1 includes a solar cell 10, a power conditioner 20, a load 30, a water electrolysis device 40, a hydrogen tank 50, a water circuit 60, a heater 70, and a hot water storage tank 80.

[0032] The solar cell 10 is a power supply source that generates electricity using sunlight. In this embodiment, the solar cell 10 may be any of silicon-based (single crystal, polycrystalline, amorphous), compound-based (III-V, CIS, CdTe), and organic-based (dye-sensitized, perovskite, organic semiconductor) solar cells.

[0033] The power conditioner 20 converts the direct current electricity generated by the solar cell 10 into alternating current, thereby allowing the electricity generated by the solar cell to be used by the water electrolysis device 40, the load 30, and other devices.

[0034] The load 30 refers to each device that consumes power. For example, the load 30 may be a television, an air conditioner, a lamp, a washing machine, a refrigerator, a personal computer, or any other type of electrical device.

[0035] The water electrolysis device 40 generates hydrogen by electrolysis of water. The generated hydrogen is stored in a hydrogen tank 50.

[0036] (1-2.Water circuit) The water circuit 60 is a water passage (piping) that circulates within the energy system 1. The water circuit 60 includes a pump 61 and a valve 63. The water circuit 60 can heat the water in the water circuit 60 using heat (waste heat) generated during operation of the water electrolysis device 40.

[0037] Here, heat exchange between the water electrolysis device 40 and a water circuit that provides heat generated during operation of the water electrolysis device 40 to the water circuit 60 will be described below. FIG. 2 is a schematic diagram showing heat exchange between the water circuit 60 and the water electrolysis device 40. As shown in FIG. 2, the water electrolysis device 40 includes a water electrolysis cell 41, a water electrolysis device water conduit 42, a pump 43, and a water tank 44. The water circuit 60 includes a heat recovery circuit 62. Water supplied from the water tank 44 is electrolyzed in the water electrolysis cell 41 via the pump 43, generating hydrogen and heat. The generated heat flows together with the water through the water electrolysis device water conduit 42 and comes into contact with the heat recovery circuit 62 of the water circuit 60, thereby increasing the temperature of the water in the water circuit 60 (for example, to 60°C). At this time, the temperature of the water electrolysis device 40 (water electrolysis device water conduit 42) decreases, and returns to its original temperature (40°C in this example) when it returns to the water tank 44. The configuration of the water electrolysis device 40 is not limited to this, and the pump 43 does not have to be provided.

[0038] The pump 61 is disposed either upstream or downstream of the water electrolysis device 40 on the water circuit 60. The pump 61 drives the water supplied from the hot water storage tank 80 (specifically, a water supply port 81 at the bottom of the hot water storage tank 80, which will be described later) to circulate through the water circuit 60. The pump 61 adjusts the amount of water flowing through the water circuit 60. There are no particular limitations on the type of pump 61.

[0039] The valve 63 is provided to change the flow of the water circuit 60. The valve 63 is provided in the water circuit 60 downstream of the water electrolysis device 40. In this example, a thermostatic valve is used as the valve 63. The operation of the valve 63 will be described later.

[0040] Heater 70 is provided in water circuit 60 between valve 63 and hot water outlet 85. Heater 70 heats the water in water circuit 60. The type of heater 70 is not particularly limited.

[0041] Hot water storage tank 80 is a tank that stores water (in this case, hot water above a predetermined temperature). Hot water storage tank 80 includes a water supply port 81 (also referred to as the "lower outlet"), a return port 83 (also referred to as the "lower inlet"), a hot water storage port 85 (also referred to as the "upper inlet"), and a hot water supply port 87 (also referred to as the "upper outlet"). Hot water storage tank 80 extends vertically from upper portion 80a to lower portion 80b. Hot water storage tank 80 includes a side portion 80b1 and a bottom portion 80b2 in lower portion 80b.

[0042] The water supply port 81 is provided on a side 80b1 of the lower part 80b of the hot water storage tank 80. The return port 83 is provided at a different position from the water supply port 81 on the side 80b1 of the lower part 80b of the hot water storage tank 80. In this example, the return port 83 is provided above the water supply port 81. In other words, the water supply port 81 is provided between the return port 83 and the bottom 80b2. The hot water storage port 85 is provided on the upper part 80a of the hot water storage tank 80. The hot water supply port 87 is provided at a different position from the hot water storage port 85 in the upper part 80a of the hot water storage tank 80.

[0043] In this embodiment, the water supply port 81 supplies water to the water circuit 60. The hot water storage port 85 receives high-temperature water (80°C in this example) generated by the heat generated by the operation of the water electrolysis device 40 and heated by the heater 70. The return port 83 receives water at a lower temperature than the water flowing into the hot water storage port 85. This allows the hot water storage tank 80 to store water in a high-temperature layer (also referred to as the "first temperature range") having a temperature above a predetermined temperature (e.g., 80°C) in its upper portion, and water in a low-temperature layer (also referred to as the "second temperature range") (e.g., 30°C or lower) in its lower portion. No partition is provided between the water in the high-temperature layer and the water in the low-temperature layer. In other words, the water in the high-temperature layer and the water in the low-temperature layer are provided continuously. The hot water supply port 87 discharges high-temperature water from the hot water storage tank 80 to an external flow path different from the water circuit 60.

[0044] (1-3. Operation of valve 63) 3 and 4 are schematic cross-sectional views of valve 63 (thermostat valve). As shown in Fig. 3 and 4, valve 63 includes a main body 631, a valve element 632, an elastic portion 633, and a temperature sensing portion 634. Temperature sensing portion 634 functions as an actuator that expands or contracts depending on the temperature.

[0045] Here, the operation of valve 63 will be described. Valve 63 changes the position of valve body 632 depending on the temperature of the water in water circuit 60. When temperature sensing portion 634 senses a temperature below a predetermined temperature (for example, 40°C), tip 634a of temperature sensing portion 634 contracts, and elastic portion 633 enters an extended state. At this time, first protrusion 632a of valve body 632 blocks upper hole 631a of main body 631, which is connected to hot water storage port 85. This causes low-temperature water in water circuit 60 to flow through lower hole 631b to return port 83.

[0046] On the other hand, when temperature sensing unit 634 senses a temperature equal to or higher than a predetermined temperature, tip 634a of temperature sensing unit 634 extends, pressing the elastic portion and changing the position of valve body 632. At this time, second protrusion 632b of valve body 632 blocks lower hole 631b of main body 631 that connects to return port 83. This causes high-temperature water in water circuit 60 to flow through upper hole 631a to hot water storage port 85. In other words, by using valve 63 (thermostatic valve), the flow path of water circuit 60 can be switched to guide the water to either hot water storage port 85 or return port 83 based on the temperature of the water in water circuit 60.

[0047] In this embodiment, water in the water circuit 60 supplied from the water supply port 81 of the hot water storage tank 80 is heated by heat (exhaust heat) generated by the operation of the water electrolysis device 40. Based on the temperature of the water in the water circuit 60, the water in the water circuit 60 is returned to the hot water storage tank 80 via either the hot water storage port 85 or the return port 83. At this time, the heater 70 further heats the water in the water circuit 60, which has been heated by the exhaust heat from the water electrolysis device 40, until it reaches a higher temperature. As a result, the water in the water circuit 60 that enters the upper part (hot water storage port 85) of the hot water storage tank 80 becomes high-temperature water (hot water). As a result, high-temperature water is present in the upper part of the hot water storage tank 80 and low-temperature water is present in the lower part, maintaining a temperature boundary layer within the hot water storage tank 80. Therefore, by using this embodiment, in an energy system equipped with a water electrolysis device, it is possible to effectively utilize the exhaust heat generated by the operation of the water electrolysis device while maintaining a temperature boundary layer in the hot water storage tank layer.

[0048] Second Embodiment In this embodiment, an example will be described in which the hot water storage tank 80 has a city water inlet.

[0049] Fig. 5 is an overall configuration diagram of an energy system 1A according to this embodiment. As shown in Fig. 5, the energy system 1A includes a solar cell 10, a power conditioner 20, a load 30, a water electrolysis device 40, a hydrogen tank 50, a water circuit 60, a heater 70, and a hot water storage tank 80A.

[0050] The hot water tank 80A includes a city water inlet 82 in addition to a water supply inlet 81 ("lower outlet"), a return inlet 83 ("lower inlet"), a hot water storage inlet 85 ("upper inlet"), and a hot water supply inlet 87 ("upper outlet").

[0051] City water inlet 82 supplies city water at room temperature to hot water storage tank 80 to ensure a sufficient amount of water in hot water storage tank 80. City water inlet 82 is preferably located below return port 83 (lower inlet) of hot water storage tank 80. This creates a stepped temperature range for the water contained in hot water storage tank 80. This prevents the city water, which is colder than the water entering from return port 83, from disrupting the temperature boundary layer inside hot water storage tank 80.

[0052] <Third embodiment> In this embodiment, an example will be described in which the flow of water in a water circuit is controlled using a control device instead of a thermostat valve.

[0053] (3-1. Configuration of Energy System 1B) 6 is an overall configuration diagram of an energy system 1B according to this embodiment. As shown in FIG. 6, the energy system 1B includes a solar cell 10, a power conditioner 20, a load 30, a water electrolysis device 40, a hydrogen tank 50, a water circuit 60B, a heater 70, a hot water storage tank 80, and a control device 90.

[0054] The water circuit 60B includes a pump 61 , a valve 65 , a valve 67 and a temperature sensor 68 .

[0055] The valve 65 (SV1) is provided before the return port 83. The valve 67 (SV2) is provided before the heater .

[0056] The temperature sensor 68 is provided in the water circuit 60B downstream of the water electrolysis device 40. The temperature sensor 68 measures the temperature of the water in the water circuit that has been heated by the heat generated by the operation of the water electrolysis device 40.

[0057] The control device 90 is connected to the solar cell 10, each device in the water circuit 60B, and each device in the energy system 1B. Figure 7 is a block diagram of the control device 90. The control device 90 has at least a control unit 901, a memory unit 903, a display unit 905, and a communication unit 907. In this embodiment, the control device 90 controls the water in the water circuit 60B to be returned to the hot water storage tank from either the hot water storage outlet 85 or the return outlet 83, based on the temperature of the water in the water circuit 60B.

[0058] The control unit 901 controls the operation of each device in the energy system 1. The control unit 901 includes, for example, a processor equipped with an arithmetic processing device exemplified by a CPU (Central Processing Unit) and memories exemplified by a ROM (Read On Memory) and a RAM (Random Access Memory). The control unit 901 monitors the temperature of water in the water circuit 60B and the temperature of water in the hot water storage tank 80, and controls each device.

[0059] The storage unit 903 may be a memory, a semiconductor memory such as an SSD (Solid State Drive), a magnetic recording medium (magnetic tape, magnetic disk, etc.), an optical recording medium, a magneto-optical recording medium, or a storage element that can store data. The storage unit 903 has a function of storing a control program and various information used in the control program.

[0060] The display unit 905 displays the control information under the control of the control unit 901. At this time, the display unit 905 may display the control information via a GUI (Graphical User Interface). Note that the display unit 905 does not necessarily have to be provided depending on the mode of the control device 90.

[0061] The communication unit 907 includes a communication module, and transmits and receives information to and from each device under the control of the control unit 901. The communication unit 907 may be wireless or wired.

[0062] In addition to the control unit 901, storage unit 903, display unit 905, and communication unit 907, the control device 90 may also include an operation unit (buttons, switches, keyboard, etc.) and an alarm unit (light, buzzer, etc.).

[0063] Fig. 8 is a functional block diagram of the control unit 901. As shown in Fig. 8, the control unit 901 includes an acquisition unit 9011, a determination unit 9013, and an operation instruction unit 9015 as functional units.

[0064] The acquisition unit 9011 has a function of acquiring various information in the energy system 1. Specifically, the acquisition unit 9011 acquires the temperature of the water in the water circuit 60B. The acquisition unit 9011 may acquire the various information at any time, or at predetermined time intervals.

[0065] The determining unit 9013 has a function of determining whether a predetermined condition is satisfied. For example, the determining unit 9013 determines whether the temperature of the water in the water circuit 60B exceeds a set value (threshold value).

[0066] The operation instruction unit 9015 has a function of instructing the operation of each device. For example, the operation instruction unit 9015 instructs the operation of the heater 70, the operation of the pump 61, and the opening or closing of the valves 65 and 67.

[0067] (3-2. Energy control method) Next, a description will be given of an energy control method using the control device 90. Fig. 9 is a flowchart of the energy control method.

[0068] First, the control device 90 acquires the temperature T1 measured by the temperature sensor 68 (step S101). At this time, it is determined whether T1 is equal to or higher than a predetermined temperature (40°C in this example) (step S103). If the measured temperature T1 is lower than the predetermined temperature (step S103; No), the control device 90 instructs the control device 90 to close the valve 67 (SV2) and open the valve 65 (SV1) (step S105). As a result, the water in the water circuit 60B that has been heated by the heat generated by the operation of the water electrolysis device 40 flows into the hot water storage tank 80 from the return port 83.

[0069] If the measured temperature T1 is equal to or higher than the predetermined temperature (step S103; Yes), the control device 90 issues an instruction to open the valve 67 (SV2) and close the valve 65 (SV1) (step S107).

[0070] Next, the control device 90 instructs the heater 70 to operate (step S109). Based on the instruction, the heater 70 operates, and the water in the water circuit 60B is further heated by the heater 70. The water in the water circuit 60B that has passed through the heater 70 flows into the hot water outlet 85. As a result, the water in the water circuit 60B that flows into the hot water outlet 85 of the hot water storage tank 80 becomes high-temperature water (hot water). As a result, high-temperature water exists at the top of the hot water storage tank 80 and low-temperature water exists at the bottom, and the temperature boundary layer within the hot water storage tank 80 is maintained.

[0071] Finally, if the control process is to be continued (step S120; Yes), the process returns to step S101. If the control process is not to be continued (step S120; No), the control process ends. By using this embodiment, in an energy system equipped with a water electrolysis device, it is possible to effectively utilize the exhaust heat generated by the operation of the water electrolysis device while using the control device and maintaining the temperature boundary layer in the hot water storage tank layer.

[0072] <Fourth embodiment> In this embodiment, an example will be described in which the control device of the third embodiment is used and the operation of the pump is controlled based on the temperature of water flowing into the hot water storage tank.

[0073] (4-1. Configuration of Energy System 1C) 10 is an overall configuration diagram of an energy system 1C according to this embodiment. As shown in FIG. 10, the energy system 1C includes a solar cell 10, a power conditioner 20, a load 30, a water electrolysis device 40, a hydrogen tank 50, a water circuit 60C, a heater 70, a hot water storage tank 80, and a control device 90.

[0074] The water circuit 60C includes a pump 61, a valve 65, a valve 67 and a temperature sensor 68 as well as temperature sensors 691 and 692.

[0075] Temperature sensor 691 is provided in water circuit 60C before return port 83 of hot water storage tank 80. Temperature sensor 692 is provided before hot water storage port 85. Temperature sensor 692 measures the temperature of water in water circuit 60C heated by heater 70. The output of heater 70 is adjusted by power conditioner 20.

[0076] (4-2. Energy control methods) Next, a description will be given of an energy control method using the control device 90. Fig. 11 is a flowchart of the energy control method.

[0077] First, the control device 90 acquires the temperature T1 measured by the temperature sensor 68 (step S101). At this time, it is determined whether T1 is equal to or higher than a predetermined temperature (40°C in this example) (step S103). If the measured temperature T1 is lower than the predetermined temperature (step S103; No), the control device 90 instructs the control device 90 to close the valve 67 (SV2) and open the valve 65 (SV1) (step S105). As a result, the water in the water circuit 60C that has been heated by the heat generated by the operation of the water electrolysis device 40 flows toward the return port 83.

[0078] Next, temperature sensor 691 detects the temperature of the incoming water in circuit 60C (step S111). At this time, control device 90 determines whether detected temperature T2 is equal to or higher than a predetermined temperature (step S113). If detected temperature T2 is higher than the predetermined temperature (for example, the difference between temperature T1 and temperature T2 is within 15°C; specifically, 25°C when the set temperature of temperature T1 is 40°C) (step S113; Yes), control device 90 controls the operation of pump 61 to increase the outflow rate from hot water storage tank 80 (step S115). This allows the temperature of the water in circuit 60C to decrease. As a result, the temperature of the water entering hot water storage tank 80 decreases, preventing the water that has entered the low-temperature layer from flowing toward the high-temperature layer.

[0079] If the measured temperature T1 is equal to or higher than a predetermined temperature (step S103; Yes), the control device 90 issues a command to open the valve 67 (SV2) and close the valve 65 (SV1) (step S107). As a result, the water in the water circuit 60C, heated by the heat generated by the operation of the water electrolysis device 40, flows toward the hot water outlet 85. Next, the temperature sensor 692 detects the temperature (T3) of the water flowing through the water circuit 60C (step S1083). At this time, the control device 90 determines whether the detected temperature T3 is equal to or higher than a predetermined temperature (step S113). If the detected temperature T3 is lower than the predetermined temperature (e.g., 60°C) (step S1083; No), the control device 90 controls the operation of the pump 61 to reduce the amount of water flowing out of the hot water storage tank 80 (step S1085). This increases the temperature of the water in the water circuit 60C, thereby reducing the amount of heating by the heater 70.

[0080] Next, the control device 90 instructs the heater 70 to operate (step S109). As a result, the water in the water circuit 60C is further heated by the heater 70. At this time, the control device 90 adjusts the output of the heater 70 (the amount of fluctuation ΔP in P (kwh)) using the acquired temperature T3 (step S117). Specifically, the output is adjusted based on Equation 1.

number

[0081] The water in the water circuit 60C that has passed through the heater 70 flows in through the hot water outlet 85. As a result, the water in the water circuit 60C that is returned to the hot water outlet 85 of the hot water storage tank 80 becomes high-temperature water (hot water). As a result, high-temperature water exists at the top of the hot water storage tank 80 and low-temperature water exists at the bottom, and the temperature boundary layer within the hot water storage tank 80 is maintained.

[0082] Finally, if the temperature T2 is lower than the predetermined temperature (step S113; No), and the control process is to be continued after step S115 or step S117 (step S120; Yes), the process returns to step S101. If the control process is not to be continued (step S120; No), the control process ends. By using this embodiment, in an energy system equipped with a water electrolysis device, it is possible to effectively utilize the exhaust heat generated by the operation of the water electrolysis device while maintaining the temperature boundary layer in the hot water storage tank layer using the control device.

[0083] Although the present embodiment shows an example in which temperature sensor 691 and temperature sensor 692 are used, the present invention is not limited to this. For example, temperature sensor 68 may have the function of temperature sensor 691.

[0084] Furthermore, in this embodiment, when the temperature T2 is lower than a predetermined temperature (step S113; No), the control device 90 may control the operation of the pump 61 to reduce the outflow rate from the hot water storage tank 80. For example, when a heater is provided in the hot water storage tank 80 to heat the water in the hot water storage tank, a decrease in the temperature of the water in the water circuit 60C is prevented, and the amount of heating by the heater can be reduced.

[0085] (Variation) Within the scope of the concept of the present invention, a person skilled in the art may conceive of various modifications and alterations, and it is understood that these modifications and alterations also fall within the scope of the present invention. For example, to the above-described embodiments, a person skilled in the art may appropriately add, delete, or modify components, or add, omit, or change conditions of processing, and these modifications are also included within the scope of the present invention as long as they include the gist of the present invention.

[0086] Although an example using a solar cell has been described in one embodiment of the present invention, the present invention is not limited to this. The present invention can also be applied to a power generation device that generates electricity using other renewable energy sources such as wind power generation and geothermal power generation as a power supply source other than a solar cell.

[0087] In one embodiment of the present invention, the water in the hot water storage tank 80 may be used as part of the water circuit 60C and circulated to the hydrogen tank 50. This allows the hydrogen tank 50 to be heated, and the hydrogen release pressure to be increased.

[0088] In one embodiment of the present invention, the water in the hot water storage tank 80 may be used as part of the water circuit and circulated through the water electrolysis device 40. This can improve the efficiency of the water electrolysis device 40 at the start of operation.

[0089] In one embodiment of the present invention, instead of the heater 70, heating may be performed by a gas burner such as a gas water heater, or by a heat pump water heater. [Explanation of symbols]

[0090] 1 Energy system, 10 Solar cell, 20 Power conditioner, 30 Load, 40 Water electrolysis device, 41 Water electrolysis cell, 42 Water channel for water electrolysis device, 43 Pump, 44 Water tank, 50 Hydrogen tank, 60, 60B, 60C Water circuit, 61 Pump, 62 Heat recovery circuit, 63 Valve, 65 Valve, 67 Valve, 68 Temperature sensor, 70 Heater, 80 Hot water storage tank, 80a Top, 80b Bottom, 80b1 Side, 80b2 Bottom, 8 1···Water inlet, 82···City water inlet, 83···Return port, 85···Hot water storage port, 87···Hot water supply port, 90···Control device, 631···Main body, 631a···Upper hole, 631b···Lower hole, 632···Valve body, 632a···First protrusion, 632b···Second protrusion, 633···Elastic portion, 634···Temperature sensing portion, 634a···Tip, 691···Temperature sensor, 692···Temperature sensor, 901···Control portion, 903···Memory portion, 905···Display portion, 907···Communication portion, 9011···Acquisition portion, 9013···Determination portion, 9015···Operation instruction portion

Claims

1. a water electrolysis device that generates hydrogen using electricity; a water circuit for acquiring heat generated by the operation of the water electrolysis device; a hot water storage tank having an upper inlet provided in an upper portion thereof for receiving water supplied from the water circuit, an upper outlet provided in the upper portion at a position different from the upper inlet and for discharging water, a lower outlet provided in the lower portion thereof for supplying water to the water circuit, and a lower inlet provided in the lower portion at a position different from the lower outlet and for receiving water supplied from the water circuit, The hot water storage tank stores water in a first temperature range having a temperature equal to or higher than a predetermined temperature in the upper portion thereof, and stores water in a second temperature range having a temperature lower than that of the first temperature range in the lower portion thereof, The water in the first temperature range and the water in the second temperature range are provided continuously, heating the water in the water circuit supplied from the lower outlet by heat generated by operation of the water electrolysis device; the water in the water circuit is returned to the hot water storage tank via either the upper inlet or the lower inlet based on the temperature of the water in the water circuit; Energy system.

2. a heater for heating the water in the heated water circuit to the first temperature range; The energy system of claim 1 .

3. the water circuit includes a thermostatic valve; the thermostatic valve switches the flow path of the water circuit to direct water to either the upper inlet or the lower inlet based on the temperature of the water in the heated water circuit. The energy system of claim 1 .

4. the hot water storage tank includes a bottom and sides in the lower portion; The lower inlet is provided in the side portion, The lower outlet is provided between the lower inlet and the bottom. The energy system of claim 1 .

5. The hot water storage tank further includes a city water inlet, The city water inlet is provided below the lower inlet. The energy system of claim 4.

6. a control device that controls the return of water to the water circuit from either the upper inlet or the lower inlet based on the temperature of the water in the water circuit; The energy system of claim 1 .

7. the water circuit includes a pump that adjusts the flow rate of water in the water circuit; When the temperature of the heated water in the water circuit returning from the lower inlet to the hot water storage tank is higher than a predetermined temperature, the control device controls the operation of the pump to increase the amount of water flowing from the hot water storage tank into the water circuit; The energy system of claim 6.

8. a pump disposed in the water circuit either upstream or downstream of the water electrolysis device; a temperature sensor disposed downstream of the water electrolysis device; When the temperature sensor detects a temperature equal to or lower than a predetermined temperature, the control device controls the water circuit to reduce the flow rate. The energy system of claim 6.

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