Power reception device and energy system

Abstract

This power reception device is supplied with a first positive electrode fluid and a negative electrode fluid, and is capable of producing hydrogen by an electrolytic reaction of water. The negative electrode fluid contains a hydrogen storage alloy, and can be operated in a first state in which the hydrogen storage alloy stores hydrogen generated by the electrolytic reaction, and in a second state in which the hydrogen storage alloy generates hydrogen.

Description

Power receiving equipment and energy systems

[0001] This disclosure relates to power receiving equipment and energy systems.

[0002] Conventionally, a power receiving device is known that uses a liquid exchange type battery, where an electrolyte is circulated between the positive and / or negative electrodes, and charging is performed by utilizing the oxidation-reduction reaction of the active material contained in the electrolyte. In such a battery, fluctuations in the output of renewable energy can be absorbed by converting electrical energy, such as renewable energy, into chemical energy and storing it.

[0003] Patent Document 1 describes an energy system comprising a power generation device that uses renewable energy and a storage device that charges or supplies the electricity generated by the power generation device to a load.

[0004] Japanese Patent Publication No. 2021-83267

[0005] In energy systems like the one described in Patent Document 1, in order to prevent overcharging of the energy storage device, fine-tuned power control in response to fluctuations in the output of renewable energy, as well as devices for performing such power control, are required, which presents challenges such as the devices becoming large or complex.

[0006] Therefore, there is a need for a power receiving device and energy system that can respond to fluctuations in input power while having a simple device configuration.

[0007] The characteristic configuration of the power receiving device according to this disclosure is that a first positive electrode fluid and a negative electrode fluid are supplied, and hydrogen can be produced by the electrolytic reaction of water, wherein the negative electrode fluid contains a hydrogen storage alloy, and the device can operate in a first state in which the hydrogen storage alloy absorbs the hydrogen generated by the electrolytic reaction, and a second state in which the hydrogen storage alloy generates hydrogen.

[0008] According to this configuration, by operating the power receiving device in the first state, hydrogen can be absorbed and stored in the negative electrode fluid containing the hydrogen storage alloy. Furthermore, even if the power receiving device in this configuration becomes overcharged, for example, when the electrolytic reaction of water continues after the hydrogen storage alloy has absorbed the maximum amount of hydrogen it can absorb, no heat generation occurs in the power receiving device, and only hydrogen is generated, making it highly safe. For this reason, by operating the power receiving device in the second state, for example, by continuing the electrolytic reaction of water even after the amount of hydrogen absorbed by the hydrogen storage alloy exceeds the maximum amount of hydrogen storage, the power receiving device can be used as a hydrogen production device. In this way, because the power receiving device can operate in both the first and second states, it can respond to fluctuations in the input power and is a power receiving device that can absorb and produce hydrogen.

[0009] The characteristic configuration of the energy system according to this disclosure comprises a power receiving unit having the above-mentioned power receiving device, a power supply unit to which the negative electrode fluid and the second positive electrode fluid are supplied, and at least one of a hydrogen generating unit to which the negative electrode fluid is supplied, wherein the negative electrode fluid can be circulated between the power receiving unit and at least one of the power supply unit and the hydrogen generating unit, the power supply unit generates electricity using hydrogen absorbed in the hydrogen storage alloy contained in the negative electrode fluid, and the hydrogen generating unit generates hydrogen from the hydrogen storage alloy by heating or depressurizing the negative electrode fluid.

[0010] According to this configuration, by supplying hydrogen absorbed by the hydrogen storage alloy in the power receiving section to the power supply section, an oxidation-reduction reaction using hydrogen can be generated in the power supply section, thereby generating electricity. Furthermore, by generating hydrogen in the hydrogen generation section from the hydrogen absorbed by the hydrogen storage alloy in the power receiving section, the hydrogen absorbed by the hydrogen storage alloy can be used for hydrogen power generation, etc. Since the negative electrode fluid can be circulated between the power receiving section, the power supply section, and the hydrogen generation section, the negative electrode fluid containing the hydrogen storage alloy that has been supplied with hydrogen in the power supply section and the hydrogen generation section is returned to the power receiving section, thereby absorbing hydrogen again. In this way, the negative electrode fluid can be used as a hydrogen carrier, and the negative electrode fluid can be repeatedly reused as an energy system.

[0011] This is a schematic diagram of the energy system according to the first embodiment. This is a schematic diagram of the energy system according to the second embodiment. This is a schematic diagram of the energy system according to the second embodiment. This is a schematic diagram of the energy system according to the third embodiment.

[0012] Embodiments of the power receiving device and energy system relating to this disclosure will be described below with reference to the drawings. However, various modifications are possible without departing from the gist of the invention, and the invention is not limited to the embodiments described below.

[0013] [First Embodiment] [Overall Configuration] The energy system 100 according to the first embodiment will be described with reference to Figure 1. Figure 1 is a diagram showing the schematic configuration of the energy system 100. The energy system 100 includes a power receiving unit 1, a power supply unit 2, a first storage unit 3 (an example of a storage unit), a second storage unit 4 (an example of a storage unit), and a water tank 5. The power receiving unit 1 is connected to a power source 6, and performs an electrolytic reaction of water by receiving power from the power source 6. The power supply unit 2 is connected to a load 7, and performs a power generation reaction using the hydrogen produced in the power receiving unit 1, and supplies the generated electricity to the load 7.

[0014] [Power Receiving Unit] The power receiving unit 1 performs the electrolytic reaction of water by receiving power from the power source 6. The power source 6 is a renewable energy source such as solar power generation or wind power generation, and its output may fluctuate depending on the weather, etc. A power converter (not shown) may be placed between the power source 6 and the power receiving unit 1, but as will be described later, the power receiving unit 1 according to this embodiment can cope with power fluctuations, so it is possible to eliminate the power converter or simplify its configuration.

[0015] The power receiving unit 1 has a power receiving device capable of producing hydrogen by the electrolytic reaction of water. The power receiving device is composed of an electrolytic cell having a positive electrode to which a first positive electrode fluid is supplied, a negative electrode to which a negative electrode fluid is supplied, and an electrolyte separating the positive electrode and the negative electrode. The power receiving device is made up of multiple electrolytic cells electrically connected. The electrolyte is, for example, an anion exchange membrane, and in this case, the power receiving device has an anion exchange membrane (AEM) type electrolytic cell.

[0016] The first positive electrode fluid according to this embodiment is an alkaline aqueous solution, for example, an aqueous potassium hydroxide solution or an aqueous sodium hydroxide solution. Further, the negative electrode fluid according to this embodiment is an aqueous solution containing a hydrogen storage alloy. The negative electrode fluid is preferably a slurry-like aqueous solution. The hydrogen storage alloy is composed of an element (A) such as Ca, Mg, Ti, Zr, V, Nb, Pt, Pd, etc., which has a high affinity for hydrogen and easily reacts with hydrogen to form a hydride, and an element (B) such as Ni, Mn, Co, Al, Fe, etc., which has a low affinity for hydrogen and is difficult to react with hydrogen. Such a hydrogen storage alloy is, for example, LaNi ５ system, MmNi ５ system, CeNi ５ system typified by the AB ５ type, ZrMn ２ system, TiMn １．５ system, CaMgNi ２ system, YMgNi ２ system, LaMgNi ２ system, TiFe ２ system, ZrV ２ system, TiV ２ system, ZrFe ２ system, TiCr １．８ system, etc. of the AB ２ type, TiFe system, TiNi system, TiV system, HfNi system, etc. of the AB type, Mg ２ Ni system, Hf ２ Fe system, etc. of the A ２ B type, La-Mg-Ni ３ system, YNi ３ system, NdCo ３ system, GdFe ３ system, etc. of the AB ３ type, (La-Mg) ２ Ni ７ system, Pr ２ Ni ７ system, Ce ２ Co ７ system A ２ B ７The hydrogen storage alloy is a type of alloy. The hydrogen storage alloy is preferably in the form of a fine powder, with a particle size of 0.1 to 100 μm (0.1 μm to 100 μm). The concentration of the hydrogen storage alloy in the negative electrode fluid is preferably 20 to 30 vol%. The negative electrode fluid containing the fine powder of the hydrogen storage alloy becomes a slurry. The hydrogen storage alloy dispersed as a fine powder in the negative electrode fluid has a high specific surface area, which is thought to cause catalytic activity. Therefore, compared to cases where the negative electrode fluid is liquid or electrodes containing a hydrogen generation catalyst are used, the overvoltage required for the electrolysis of water can be reduced, and the power consumption of the power receiving device can be reduced. Also, if the concentration of the hydrogen storage alloy is 20 to 30 vol% (20 vol% to 30 vol%), the increase in electrical resistance is minimal. The negative electrode fluid may also contain a dispersant such as sodium polyacrylate to uniformly disperse the hydrogen storage alloy.

[0017] The power receiving unit 1 is connected to a water tank 5 where the first positive electrode fluid is stored via a first positive electrode flow path 51. Therefore, the first positive electrode fluid flows from the water tank 5 to the power receiving unit 1 via the first positive electrode flow path 51 and is supplied to the positive electrode of the power receiving device. A pump or the like that which supplies the first positive electrode fluid may be placed on the first positive electrode flow path 51. Although not shown in the figures, the power receiving unit 1 and the water tank 5 are also connected by a flow path other than the first positive electrode flow path 51, and the first positive electrode fluid that flows out of the power receiving unit 1 flows through this flow path and into the water tank 5.

[0018] Furthermore, the power receiving unit 1 is connected to the first storage unit 3 by the first negative electrode channel 21 and to the second storage unit 4 by the fourth negative electrode channel 24. Neutral electrode fluid flows through the first negative electrode channel 21 and the fourth negative electrode channel 24. In this embodiment, the negative electrode fluid stored in the second storage unit 4 flows into the power receiving unit 1 via the fourth negative electrode channel 24 and is supplied to the negative electrode of the power receiving device. The negative electrode fluid supplied to the power receiving device is used in the electrolytic reaction of water at the negative electrode, then flows out of the power receiving device, flows through the first negative electrode channel 21 and is supplied to the first storage unit 3.

[0019] The power receiving device of the power receiving unit 1 is supplied with the first positive electrode fluid and the negative electrode fluid through the first positive electrode flow path 51 or the fourth negative electrode flow path 24. Therefore, when power is supplied from the power source 6 to the power receiving unit 1 and a voltage is applied to the power receiving device, the reaction represented by the following formula 1 occurs at the negative electrode, and the reaction represented by the following formula 2 occurs at the positive electrode. In formula 1, M is a hydrogen storage alloy, and MH is a metal hydride. As shown in formula 1, the hydrogen atoms generated by the electrolysis of water penetrate into the hydrogen storage alloy and are stored in the hydrogen storage alloy by generating a metal hydride. At the positive electrode, water molecules H ２ O and oxygen molecules O ２ are generated.

[0020] M + H ２ O + e - →MH + OH － (Formula 1) 4OH － →O ２ + 2H ２ O + 4e － (Formula 2)

[0021] On the other hand, when hydrogen is generated exceeding the maximum hydrogen storage amount, which is the maximum amount of hydrogen that the hydrogen storage alloy can store, the hydrogen storage alloy cannot store hydrogen. Therefore, the hydrogen generated exceeding the maximum hydrogen storage amount becomes hydrogen molecules and is discharged from the power receiving device. Thus, by continuing the electrolysis reaction even after the hydrogen generation amount exceeds the maximum hydrogen storage amount, hydrogen can be produced by the power receiving device. That is, the power receiving device can operate in a first state in which the hydrogen storage alloy stores hydrogen generated by the electrolysis reaction and a second state in which the hydrogen storage alloy generates hydrogen. In the first state, hydrogen can be stored in the hydrogen storage alloy, and in the second state, hydrogen can be produced by the power receiving device. The hydrogen produced by the power receiving device may be collected by a collection device (not shown) and stored in a storage device or the like. Also, this hydrogen may be stored in a hydrogen storage alloy different from the hydrogen storage alloy in the power receiving device.

[0022] The oxygen generated at the positive electrode is discharged from the power receiving device. The energy system 100 may have a recovery mechanism for recovering the oxygen and water vapor contained in the discharged hydrogen.

[0023] In general secondary batteries such as lithium-ion batteries, it was necessary to control the power input to the power receiving device so that the positive electrode fluid and the negative electrode fluid would not enter an overcharged state by continuously applying a voltage to the battery even after being fully charged. However, even if overcharging occurs (transition from the first state to the second state) due to fluctuations in the power of the power source 6 or the like in the power receiving device of the present embodiment, only hydrogen is generated from the power receiving device in the second state, and there is no need to respond to fluctuations in the output of the power source 6, and the utilization efficiency is high. Further, even if a high voltage is applied to the power receiving device due to fluctuations in the output of the power source 6 and hydrogen is generated in an amount greater than the amount occluded in the hydrogen occluding alloy, the hydrogen can be collected as hydrogen molecules. In the first state, the hydrogen occluding alloy may occlude the generated hydrogen. Thus, the power receiving device according to the present embodiment can stably convert power into electrochemical energy even when using renewable energy with large fluctuations in output or the like as the power source 6. For this reason, it is possible to eliminate a power converter or the like for responding to power fluctuations or to simplify its configuration.

[0024] 〔Power feeding unit〕 The power feeding unit 2 has a power generation cell that converts chemical energy into electrical energy. The power generation cell has a positive electrode to which a second positive electrode fluid is supplied, a negative electrode to which a negative electrode fluid containing water and a hydrogen occluding alloy is supplied, and an electrolyte that separates the positive electrode and the negative electrode. The electrolyte is, for example, an anion exchange membrane. In this case, the power receiving device has a power generation cell of the anion exchange membrane (AEM) type. The power feeding unit 2 is a combination of a plurality of power generation cells electrically connected.

[0025] As shown in FIG. 1, the power feeding unit 2 is connected to the first storage unit 3 by the second negative electrode flow path 22 and is connected to the second storage unit 4 by the third negative electrode flow path 23. A negative electrode fluid flows through the second negative electrode flow path 22 and the third negative electrode flow path 23. In the present embodiment, the negative electrode fluid stored in the first storage unit 3 is supplied to the power feeding unit 2 via the second negative electrode flow path 22. After the supplied negative electrode fluid is used for a power generation reaction at the negative electrode, it flows out of the power feeding unit 2, flows through the third negative electrode flow path 23, and is supplied to the second storage unit 4.

[0026] In the power receiving unit 1, the negative electrode fluid containing a hydrogen-absorbing alloy with absorbed hydrogen flows through the first negative electrode channel 21, the first storage unit 3, and the second negative electrode channel 22 and is supplied to the negative electrode of the power supply unit 2. Since the power supply unit 2 operates at a temperature of approximately 20°C to 60°C, evaporation of water in the negative electrode fluid is suppressed. At the negative electrode of the power supply unit 2, hydrogen is supplied from the hydrogen-absorbing alloy in the negative electrode fluid, and the reaction shown in equation 3 below occurs. In addition, a second positive electrode fluid is supplied to the positive electrode of the power supply unit 2. The second positive electrode fluid is not particularly limited as long as it is a fluid containing an active material that carries out oxidation-reduction reactions involving hydrogen, for example, air or oxygen can be used. When oxygen is used as the second positive electrode fluid, the reaction shown in equation 4 below occurs at the positive electrode. As a result, an electromotive force is generated between the positive and negative electrodes, and power is generated. The power generated in the power supply unit 2 is used by the load 7. A power converter may be placed between the power supply unit 2 and the load 7, but since the energy system 100 according to this embodiment can cope with power fluctuations, its configuration may be simplified, or a power converter may not be placed at all. In addition, because water is generated at the negative electrode by the power generation reaction of the power supply unit 2, the viscosity of the negative electrode fluid flowing out of the power supply unit 2 is lower than the viscosity of the negative electrode fluid flowing into the power supply unit 2.

[0027] MH+OH － →M+H ２ O+e － (Formula 3) O ２ +2H ２ O+4e － →4OH － (Formula 4)

[0028] The negative electrode fluid flowing out from the power supply unit 2 flows through the third negative electrode channel 23, the second storage unit 4, and the fourth negative electrode channel 24 before flowing into the power receiving unit 1. In other words, in the energy system 100 according to this embodiment, the negative electrode fluid is configured to circulate between the power receiving unit 1 and the power supply unit 2. The hydrogen storage alloy contained in the negative electrode fluid absorbs hydrogen in the power receiving unit 1, and the power supply unit 2 supplies hydrogen, thereby creating a system capable of storing and transporting hydrogen converted from electrical energy. Therefore, the negative electrode fluid functions as a carrier of hydrogen (energy).

[0029] [Storage Section] In this embodiment, the energy system 100 is configured to allow the negative electrode fluid to circulate between the power receiving section 1 and the power supply section 2 via a first storage section 3 and a second storage section 4. The first storage section 3 stores the negative electrode fluid containing a hydrogen storage alloy that has absorbed hydrogen at the power receiving section 1, and the second storage section 4 stores the negative electrode fluid containing a hydrogen storage alloy to which hydrogen has been supplied at the power supply section 2. By storing the negative electrode fluid in the first storage section 3 and the second storage section 4 in this way, it is possible to increase the hydrogen storage capacity (battery capacity) of the energy system 100. The first storage section 3 and the second storage section 4 preferably have containers that are alkali-resistant and pressure-resistant.

[0030] [Second Embodiment] Next, the energy system 100 according to the second embodiment will be described with reference to Figures 2 and 3. As shown in Figures 2 and 3, the power receiving unit 1 according to the second embodiment includes a hydrogen storage power receiving device 11 and a hydrogen generation power receiving device 12. Both the hydrogen storage power receiving device 11 and the hydrogen generation power receiving device 12 are connected to the power supply 6 via a power converter (not shown). The hydrogen storage power receiving device 11 is connected to the first storage unit 3 via a first negative electrode channel 21, to the second storage unit 4 via a fourth negative electrode channel 24, and to the water tank 5 via a second positive electrode channel 52 and a fourth positive electrode channel 54. The hydrogen generation power receiving device 12 is connected to the first storage unit 3 via a fifth negative electrode channel 25 and a sixth negative electrode channel 26, and to the water tank 5 via a third positive electrode channel 53 and a fifth positive electrode channel 55.

[0031] Furthermore, control valves 31, 32, 33, and 34 are arranged on the second positive electrode channel 52, the third positive electrode channel 53, the fourth negative electrode channel 24, and the fifth negative electrode channel 25, respectively. The opening and closing operations of the control valves 31, 32, 33, and 34 are controlled by a control unit (not shown) provided in the energy system 100. The control unit is composed of a microcontroller including a processor and semiconductor memory. The other configurations of the second embodiment are the same as those of the first embodiment, so their description is omitted.

[0032] Figure 2 shows the flow of the first positive electrode fluid and negative electrode fluid when the hydrogen storage power receiving device 11 is operating, indicated by thick lines. In Figure 2, the control valve 33 located on the fourth negative electrode flow path 24 is open, the control valve 34 located on the fifth negative electrode flow path 25 is closed, the control valve 31 located on the second positive electrode flow path 52 is open, and the control valve 32 located on the third positive electrode flow path 53 is closed. At this time, the hydrogen storage power receiving device 11 is supplied with negative electrode fluid stored in the second storage unit 4 via the fourth negative electrode flow path 24, and the first positive electrode fluid stored in the water tank 5 is supplied via the second positive electrode flow path 52. Therefore, when a voltage is applied to the hydrogen storage power receiving device 11 by the power supply 6, hydrogen is generated by the electrolytic reaction of water, and the hydrogen storage alloy contained in the negative electrode fluid supplied from the second storage unit 4 absorbs the hydrogen. Thus, the hydrogen storage power receiving device 11 is operated in a first state in which the hydrogen storage alloy absorbs the hydrogen generated by the electrolytic reaction. The mode in which the hydrogen storage power receiving device 11 is operated in the first state is referred to as the first operating mode.

[0033] The negative electrode fluid containing the hydrogen-absorbing alloy that has absorbed hydrogen in the hydrogen-absorbing power receiving device 11 flows through the first negative electrode channel 21 and into the first storage section 3, where it is stored. The negative electrode fluid stored in the first storage section 3 flows through the second negative electrode channel 22 and is supplied to the power supply section 2, where it is used in the power generation reaction, and then flows through the third negative electrode channel 23 and into the second storage section 4, where it is stored. Thus, in the first operating mode, the negative electrode fluid circulates between the power receiving section 1 and the power supply section 2 via the first negative electrode channel 21, the first storage section 3, the second negative electrode channel 22, the second storage section 4, the third negative electrode channel 23, and the fourth negative electrode channel 24. In addition, the first positive electrode fluid that flows out from the hydrogen-absorbing power receiving device 11 flows through the fourth positive electrode channel 54 and into the water tank 5, where it is stored. The first positive electrode fluid circulates between the water tank 5 and the power receiving unit 1 via the second positive electrode channel 52 and the fourth positive electrode channel 54.

[0034] Figure 3 shows the flow of the first positive electrode fluid and negative electrode fluid when the hydrogen generation power receiving device 12 is operating, indicated by thick lines. In Figure 3, control valve 33 is closed, control valve 34 is open, control valve 31 is closed, and control valve 32 is open. At this time, the hydrogen generation power receiving device 12 is supplied with negative electrode fluid stored in the first storage unit 3 via the fifth negative electrode flow path 25, and the first positive electrode fluid stored in the water tank 5 is supplied via the third positive electrode flow path 53. When a voltage is applied to the hydrogen generation power receiving device 12 by the power supply 6, hydrogen is generated by the electrolytic reaction of water. However, the hydrogen storage alloy contained in the negative electrode fluid supplied from the first storage unit 3 has already absorbed hydrogen, so it cannot absorb hydrogen beyond its maximum hydrogen storage capacity. For this reason, any hydrogen generated in the hydrogen generation power receiving device 12 that exceeds the maximum hydrogen storage capacity of the hydrogen storage alloy is discharged outside the hydrogen generation power receiving device 12. Thus, the hydrogen generation power receiving device 12 is operated in a second state in which an amount of hydrogen exceeding the maximum hydrogen storage capacity is generated by the hydrogen storage alloy. The mode in which the hydrogen generation power receiving device 12 is operated in the second state is referred to as the second operating mode.

[0035] The negative electrode fluid flows out of the hydrogen generation power receiving device 12, circulates through the sixth negative electrode channel 26, and flows into the first storage unit 3. In other words, in the second operating mode, the negative electrode fluid circulates between the hydrogen generation power receiving device 12 and the first storage unit 3 via the fifth negative electrode channel 25 and the sixth negative electrode channel 26. Also, the first positive electrode fluid that flows out of the hydrogen generation power receiving device 12 circulates through the fifth positive electrode channel 55 and flows into the water tank 5, where it is stored. In the second operating mode, the first positive electrode fluid circulates between the water tank 5 and the power receiving unit 1 via the third positive electrode channel 53 and the fifth positive electrode channel 55.

[0036] The control unit switches between the first and second operating modes of the energy system 100. Specifically, when hydrogen is absorbed into the hydrogen storage alloy in the negative electrode fluid, the energy system 100 is set to the first operating mode by controlling the opening and closing operations of control valves 31 and 33 so that they are open and control valves 32 and 34 are closed. When hydrogen is produced in the power receiving unit 1, the energy system 100 is set to the second operating mode by controlling the opening and closing operations of control valves 31 and 33 so that they are closed and control valves 32 and 34 are open. By the control unit switching between the first and second operating modes, it becomes possible to actively produce hydrogen in the power receiving unit 1, for example, when there is a large power supply from the power source 6 or when the power demand at the load 7 is low.

[0037] [Third Embodiment] The energy system 100 according to the third embodiment will be described with reference to Figure 4. As shown in Figure 4, the energy system 100 according to the third embodiment is equipped with a hydrogen generation unit 8 instead of a power supply unit 2. The hydrogen generation unit 8 generates hydrogen by heating or depressurizing a negative electrode fluid containing a hydrogen storage alloy that has absorbed hydrogen. The hydrogen generation unit 8 may be, for example, a power generation facility that generates electricity by burning hydrogen, a fuel cell similar to the power supply unit 2, or a storage facility that stores the generated hydrogen. The electricity generated using the hydrogen generated in the hydrogen generation unit 8 may be supplied to factories or homes for use. The other configurations of the third embodiment are the same as those of the second embodiment, so their description will be omitted.

[0038] As shown in Figure 4, the negative electrode fluid stored in the first storage unit 3 is transported to the hydrogen generation unit 8 by transport equipment such as cars or ships. The negative electrode fluid containing the hydrogen storage alloy, to which hydrogen has been supplied in the hydrogen generation unit 8, is transported to the second storage unit 4 by transport equipment and stored in the second storage unit 4. The negative electrode fluid returned to the second storage unit 4 is supplied to the power receiving unit 1, thereby re-absorbing hydrogen generated by the electrolytic reaction. In this way, the negative electrode fluid can circulate between the power receiving unit 1 and the hydrogen generation unit 8 via the first storage unit 3 and the second storage unit 4, and is repeatedly used as a hydrogen (energy) carrier. Compared to transporting liquid hydrogen, transporting the negative electrode fluid containing the hydrogen storage alloy does not require explosion-proof treatment of transport equipment, thus enabling reductions in transport costs and improvements in safety. Furthermore, this makes it possible to construct an energy system 100 near a power source 6, such as renewable energy, and supply a negative electrode fluid containing hydrogen to a location away from the power source 6, thereby enabling the supply of clean energy generated in suburban areas to cities and other locations.

[0039] Furthermore, storage facilities for storing negative electrode fluid may be provided between the first storage unit 3 and the hydrogen generation unit 8, and / or between the hydrogen generation unit 8 and the second storage unit 4. Storing negative electrode fluid near the hydrogen generation unit 8 allows for the supply and storage of hydrogen in accordance with the supply and demand of the hydrogen generation unit 8. It also allows for the supply of negative electrode fluid from the storage facility to multiple hydrogen generation units 8. In addition, the negative electrode fluid may be transported from the storage facility to retail and supplied to hydrogen engine vehicles, fuel cell vehicles, etc., which are examples of hydrogen generation units 8. At retail, along with the supply of negative electrode fluid, negative electrode fluid containing hydrogen storage alloy supplied from hydrogen engine vehicles, etc., is recovered.

[0040] [Other Embodiments] (a) In the embodiments described above, the energy system 100 is provided with a first storage section 3 and a second storage section 4, but there may be only one storage section between the power receiving section 1 and the power supply section 2 or hydrogen generation section 8. That is, in one storage section, a negative electrode fluid containing a hydrogen storage alloy that has absorbed hydrogen in the power receiving section 1 flows in from the first negative electrode channel 21, and a negative electrode fluid containing a hydrogen storage alloy supplied with hydrogen in the power supply section 2 or hydrogen generation section 8 flows in from the third negative electrode channel 23, and these may be mixed and stored. Even if negative electrode fluids with different amounts of hydrogen absorbed by the hydrogen storage alloys flow in, they are homogenized in the storage section, so that the negative electrode fluid stored in the storage section can be transported to a supply destination, and the number of storage sections can be reduced. In addition, one storage section may be provided with a partition that can separate and store the negative electrode fluid that has flowed out from the power receiving section 1 and the negative electrode fluid that has flowed out from the power supply section 2 or hydrogen generation section 8. This makes it possible to separate and store negative electrode fluids with different hydrogen storage capacities while reducing the number of storage units. Furthermore, in the above-described embodiment, the energy system 100 does not necessarily have a storage unit. In this case, a flow path can be formed between the power receiving unit 1, the power supply unit 2, and the hydrogen generating unit 8 so that the negative electrode fluid can circulate between them, or it can be transported between them by transport equipment.

[0041] (b) In the second embodiment, the control unit switches between the first operating mode and the second operating mode, but the opening and closing operations of the control valves 31, 32, 33, and 34 may be controlled to perform the first operating mode and the second operating mode simultaneously. That is, by opening the control valves 31, 32, 33, and 34 and supplying the negative electrode fluid to both the hydrogen storage power receiving device 11 and the hydrogen generation power receiving device 12, hydrogen storage in the hydrogen storage alloy and hydrogen production in the power receiving unit 1 may be performed simultaneously. This makes it possible to produce the negative electrode fluid as an energy carrier and to produce hydrogen at the same time, so that the power input from the power supply 6 can be used efficiently.

[0042] (c) In the first embodiment, by applying a high voltage to the power receiving unit 1, hydrogen absorption by the hydrogen storage alloy may be suppressed and hydrogen may be discharged from the power receiving unit 1. That is, the energy system 100 in the first embodiment may be configured to switch between a first operating mode and a second operating mode depending on the magnitude of the voltage applied to the power receiving unit 1. This makes it possible to switch between the first operating mode and the second operating mode with a single power receiving device, thus making it possible to miniaturize the energy system 100. In addition, in the second and third embodiments, hydrogen may be generated in the hydrogen storage alloy contained in the negative electrode fluid by applying a high voltage to the hydrogen generation power receiving device 12. That is, the second state in which the power receiving device generates hydrogen in the hydrogen storage alloy may be not only when the power receiving device is overcharged, but also when a high voltage is applied to the power receiving device.

[0043] (d) In the first embodiment, the negative electrode fluid stored in the first storage unit 3 and the negative electrode fluid flowing out from the power supply unit 2 flow through the channels (second negative electrode channel 22 and third negative electrode channel 23). However, the negative electrode fluid may be transported between the first storage unit 3 and the second storage unit 4 and the power supply unit 2 by transport equipment. In addition, in each embodiment, the negative electrode fluid may be transported between the power receiving unit 1 and the first storage unit 3 and the second storage unit 4 by transport equipment. In other words, the negative electrode fluid may be transported by transport equipment in at least a portion of the space between the power receiving unit 1 and the power supply unit 2 and the hydrogen generation unit 8.

[0044] (e) The energy system 100 may include both a power supply unit 2 and a hydrogen generation unit 8. By generating electricity in the power supply unit 2 near the power receiving unit 1 while transporting surplus hydrogen to the hydrogen generation unit 8, it becomes possible to supply hydrogen produced in the power receiving unit 1 according to demand.

[0045] (f) Although the hydrogen storage power receiving device 11 and the hydrogen generation power receiving device 12 are included as components of the energy system 100, they may be separated from the power supply unit 2 and the hydrogen generation unit 8 and used as a hydrogen production device.

[0046] The configurations disclosed in the above embodiments (including other embodiments, the same applies hereinafter) can be applied in combination with configurations disclosed in other embodiments, provided that this does not create a conflict. Furthermore, the embodiments disclosed herein are illustrative, and the embodiments of this disclosure are not limited thereto and can be modified as appropriate without departing from the purpose of this disclosure.

[0047] In the embodiment described above, the following configuration can be envisioned: (1) The power receiving device is supplied with a first positive electrode fluid and a negative electrode fluid, and is capable of producing hydrogen by the electrolytic reaction of water, wherein the negative electrode fluid contains a hydrogen storage alloy, and the device can operate in a first state in which the hydrogen storage alloy absorbs the hydrogen generated by the electrolytic reaction, and a second state in which the hydrogen storage alloy generates hydrogen.

[0048] According to this configuration, by operating the power receiving device in the first state, hydrogen can be absorbed and stored in the negative electrode fluid containing the hydrogen storage alloy. Furthermore, even if the power receiving device in this configuration becomes overcharged, for example, when the electrolytic reaction of water continues after the hydrogen storage alloy has absorbed the maximum amount of hydrogen it can absorb, only hydrogen is generated in the power receiving device, making it highly safe. For this reason, by operating the power receiving device in the second state, for example, by continuing the electrolytic reaction of water after the amount of hydrogen absorbed by the hydrogen storage alloy exceeds the maximum amount of hydrogen storage, the power receiving device can be used as a hydrogen production device. In this way, because the power receiving device can operate in both the first and second states, it can respond to fluctuations in the input power and is a power receiving device that can absorb and produce hydrogen.

[0049] (2) In the power receiving device of (1), the negative electrode fluid is preferably in slurry form.

[0050] With this configuration, compared to when electrolysis of water is performed with an electrode to which a hydrogen generation catalyst is attached, hydrogen generation by operating the power receiving device in the second state is possible because the hydrogen storage alloy is dispersed as a fine powder in the negative electrode fluid, and because it has a high surface area, the hydrogen storage alloy itself acts as a catalyst, which can reduce overvoltage and thus reduce power consumption.

[0051] (3) In the power receiving device of (1) or (2), the negative electrode fluid is preferably a hydrogen storage alloy with a concentration of 20 to 30 vol%.

[0052] This configuration allows the negative electrode fluid to maintain a slurry-like state in which hydrogen storage alloys are dispersed in the liquid, while suppressing an excessive increase in electrical resistance. As a result, the overvoltage required for the electrolysis of water is reduced, and the increase in electrical resistance is suppressed, thus further reducing power consumption.

[0053] (4) In any of the power receiving devices described in (1) to (3), the particle size of the hydrogen storage alloy is preferably 0.1 to 100 μm.

[0054] With this configuration, the hydrogen storage alloy has a high specific surface area, making it easier for the catalytic action of the hydrogen storage alloy itself to occur. This makes it easier to lower the overvoltage required for water electrolysis, and thus easier to reduce power consumption.

[0055] (5) An energy system 100 comprising a power receiving unit 1 having a power receiving device of any of (1) to (4), a power supply unit 2 to which a negative electrode fluid and a second positive electrode fluid are supplied, and at least one of a hydrogen generating unit 8 to which a negative electrode fluid is supplied, wherein the negative electrode fluid can be circulated between the power receiving unit 1 and at least one of the power supply unit 2 and the hydrogen generating unit 8, the power supply unit 2 generates electricity using hydrogen supplied from a hydrogen storage alloy contained in the negative electrode fluid, and the hydrogen generating unit 8 generates hydrogen from the hydrogen storage alloy by heating or depressurizing the negative electrode fluid.

[0056] According to this configuration, by supplying hydrogen absorbed by the hydrogen storage alloy in the power receiving unit 1 to the power supply unit 2, an oxidation-reduction reaction using hydrogen can be generated in the power supply unit 2, thereby generating electricity. Furthermore, by generating hydrogen in the hydrogen generation unit 8 from the hydrogen absorbed by the hydrogen storage alloy in the power receiving unit 1, the hydrogen absorbed by the hydrogen storage alloy can be used for hydrogen power generation, etc. Since the negative electrode fluid can circulate between the power receiving unit 1, the power supply unit 2, and the hydrogen generation unit 8, the negative electrode fluid containing the hydrogen storage alloy that has been supplied with hydrogen in the power supply unit 2 and the hydrogen generation unit 8 is returned to the power receiving unit 1, thereby absorbing hydrogen again. In this way, the negative electrode fluid can be used as a hydrogen carrier, and the negative electrode fluid can be repeatedly reused as an energy system.

[0057] In the energy system 100 of (6)(5), it is preferable that the system further includes a storage section (first storage section 3, second storage section 4) for storing negative electrode fluid, and that the negative electrode fluid can be circulated between the power receiving section 1 and at least one of the power supply section 2 and the hydrogen generation section 8 via the storage section (first storage section 3, second storage section 4).

[0058] With this configuration, a negative electrode fluid containing a hydrogen storage alloy that has reached its maximum hydrogen storage capacity can be stored in the storage unit. By supplying a fixed amount of negative electrode fluid from the storage unit to the power supply unit 2 or the hydrogen generation unit 8, a constant amount of power can be supplied regardless of fluctuations in the output of the power supply 6, or a fixed amount of hydrogen can be generated.

[0059] (7) In the energy system 100 of (6), a control unit is further provided to control the flow state of the negative electrode fluid, and the storage unit has a first storage unit 3 for storing the negative electrode fluid that has flowed out from the power receiving unit 1 and a second storage unit 4 for storing the negative electrode fluid that has flowed out from at least one of the power supply unit 2 and the hydrogen generation unit 8, and the power receiving unit 1 has at least one hydrogen generation power receiving device 12 which is supplied with the negative electrode fluid stored in the first storage unit 3 and operated in a second state, and a hydrogen storage power receiving device 11 which is supplied with the negative electrode fluid that has been stored in the second storage unit 4 and operated in a first state, and it is preferable that the control unit switches between a state in which the negative electrode fluid stored in the first storage unit 3 is supplied to the hydrogen generation power receiving device 12 and a state in which the negative electrode fluid stored in the second storage unit 4 is supplied to the hydrogen storage power receiving device 11.

[0060] With this configuration, the operating mode of the energy system 100 can be controlled by supplying the negative electrode fluid stored in the second storage unit 4 to the hydrogen storage power receiving device 11 when hydrogen storage is desired, and by supplying the negative electrode fluid stored in the first storage unit 3 to the hydrogen generation power receiving device 12 when hydrogen production is desired. This makes it possible, for example, to actively produce hydrogen in the power receiving unit 1 when there is no need to generate electricity in the power supply unit 2 or when the demand for hydrogen generation unit 8 is low, or to actively absorb hydrogen into the hydrogen storage alloy when a decrease in the amount of electricity input to the power receiving unit 1 is expected.

[0061] In any of the energy systems 100 of (8), (5), to (7), it is preferable that the negative electrode fluid can be transported by transport equipment between the power receiving unit 1 and at least one of the power supply unit 2 and the hydrogen generation unit 8.

[0062] According to this configuration, by transporting the negative electrode fluid stored in the storage unit to the power supply unit 2 and the hydrogen generation unit 8, that is, by using the negative electrode fluid as a hydrogen carrier, the negative electrode fluid and the hydrogen contained in it can be used at a location far from the power receiving unit 1. Furthermore, it becomes possible to reduce transportation costs and improve safety.

[0063] This disclosure is applicable to power receiving equipment and energy systems.

[0064] 1: Power receiving unit, 2: Power supply unit, 3: First storage unit, 4: Second storage unit, 8: Hydrogen generation unit, 11: Power receiving device for hydrogen storage, 12: Power receiving device for hydrogen generation, 100: Energy system

Claims

1. A power receiving device to which a first positive electrode fluid and a negative electrode fluid are supplied, and which is capable of producing hydrogen by an electrolytic reaction of water, wherein the negative electrode fluid contains a hydrogen storage alloy, and the power receiving device is capable of operating in a first state in which the hydrogen storage alloy absorbs the hydrogen generated by the electrolytic reaction, and a second state in which the hydrogen storage alloy generates hydrogen.

2. The power receiving device according to claim 1, wherein the negative electrode fluid is in slurry form.

3. The power receiving device according to claim 1, wherein the negative electrode fluid has a hydrogen storage alloy concentration of 20 to 30 vol%.

4. The power receiving device according to claim 1, wherein the particle size of the hydrogen storage alloy is 0.1 to 100 μm.

5. An energy system comprising: a power receiving unit having a power receiving device according to any one of claims 1 to 4; a power supply unit to which the negative electrode fluid and a second positive electrode fluid are supplied; and at least one of a hydrogen generating unit to which the negative electrode fluid is supplied, wherein the negative electrode fluid is circulating between the power receiving unit and at least one of the power supply unit and the hydrogen generating unit; the power supply unit generates electricity using hydrogen supplied from the hydrogen storage alloy contained in the negative electrode fluid; and the hydrogen generating unit generates hydrogen from the hydrogen storage alloy by heating or depressurizing the negative electrode fluid.

6. The energy system according to claim 5, further comprising a storage section for storing the negative electrode fluid, wherein the negative electrode fluid can be circulated between the power receiving section and at least one of the power supply section and the hydrogen generating section via the storage section.

7. The energy system according to claim 6, further comprising a control unit for controlling the flow state of the negative electrode fluid, wherein the storage unit has a first storage unit for storing the negative electrode fluid discharged from the power receiving unit and a second storage unit for storing the negative electrode fluid discharged from at least one of the power supply unit and the hydrogen generation unit, the power receiving unit has at least one hydrogen generation power receiving device to which the negative electrode fluid stored in the first storage unit is supplied and which is operated in the second state, and a hydrogen storage power receiving device to which the negative electrode fluid stored in the second storage unit is supplied and which is operated in the first state, and the control unit switches between a state in which the negative electrode fluid stored in the first storage unit is supplied to the hydrogen generation power receiving device and a state in which the negative electrode fluid stored in the second storage unit is supplied to the hydrogen storage power receiving device.

8. The energy system according to claim 5, wherein the negative electrode fluid is transportable between the power receiving unit and at least one of the power supply unit and the hydrogen generating unit by transport equipment.

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