JP2017020053A - Water electrolysis device and energy storage-feed system using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water electrolysis device where a hydrogen gas and an oxygen gas are generated from anelectrode at different timings.SOLUTION: Provided is a water electrolysis device where water is electrolyzed to generate hydrogen and oxygen, containing: an electrolyte aqueous solution 107 including an intermediate product repeating oxidation-reduction reaction; an electrolytic electrode 103 where water is electrolyzed; an intermediate electrode 102 where the oxidation-reduction reaction of the intermediate product is performed; and an electrolytic tank 112 storing them. The oxidation-reduction potential of the intermediate product is higher than the hydrogen generation potential of the intermediate electrode 102 and the intermediate product, and also, the oxidation-reduction potential of the intermediate product is lower than the hydrogen generation potential of the electrolytic electrode 103.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a water electrolysis apparatus that generates hydrogen and oxygen by electrolyzing water.

  In recent years, depletion of resources and destruction of the environment are regarded as major problems on the earth, and there is a demand for the construction of a zero-emission society using renewable energy. Renewable energy power plants, such as wind and solar power generation, emit almost no carbon dioxide during power generation and are expected to grow significantly in the future. In addition, power plants suitable for local production and consumption of energy are expected to be introduced to remote islands, mountainous areas, remote areas such as remote areas where energy costs have been high. However, since renewable energy is unstable, it is difficult to supply it according to power demand. In order to solve this problem, the power supply / demand gap is generally compensated by thermal power plants and pumped-storage power generation, but it is not possible to install thermal power plants and pumped-storage power plants for adjustment on remote islands and mountainous areas. Difficult in terms of scale and cost. Therefore, hydrogen and storage batteries that can store electric power on a large scale have attracted attention.

  Regarding storage batteries for power storage, various types of components and operation methods such as lead storage batteries, lithium ion secondary batteries, NAS batteries, and redox flow batteries have been developed, such as home use, power plant use, and business use use. Depending on applications such as storage scale, measures against instantaneous interruption, power leveling for systems, and load leveling (use of nighttime power), a system with an appropriate device configuration and electric capacity has been proposed. However, due to the high cost per capacity, resource problems, difficulty in scaling up, etc., it has not reached a scale comparable to pumped-storage power generation.

  On the other hand, in a system for storing electric power using hydrogen produced by water electrolysis such as Patent Document 1, it is possible to convert electric power into hydrogen energy and store it relatively easily, and resources are inexhaustible. It is attracting attention again because it exists. However, when it is assumed that power is used, in order to maintain competitiveness compared to system power, etc., reduction of the equipment cost of the electrolyzer is an issue. In order to prevent the mixing of hydrogen gas and oxygen gas generated at the electrodes in the conventional water electrolysis device, the electrodes are completely separated by a low-gas-permeable partition wall, and the entire device including piping and tanks is also It is completely separated into two lines, hydrogen line and oxygen line. The partition wall material has the largest proportion of the equipment cost of the water electrolysis apparatus, and the reduction of the partition wall cost is strongly demanded. In addition, it is better that the hydrogen line and the oxygen line can be integrated in order to simplify the auxiliary devices.

JP 2013-136801 A

  As described above, ion exchange membranes are mainly used for the partition walls of the conventional water electrolysis apparatus, which is the main cause of the cost increase of the apparatus. There are products that use a porous membrane as a partition wall, but advanced technology is required to achieve sufficient low gas permeability and conductivity, and cost reduction is difficult. On the other hand, if a water electrolysis device that generates hydrogen gas and oxygen gas at different timings from the electrode can be realized, the mixing of hydrogen gas and oxygen gas can be ignored. Therefore, the device can be simplified and the cost can be reduced.

  An object of the present invention is to provide a water electrolysis apparatus in which hydrogen gas and oxygen gas are generated from electrodes at different timings.

  In order to solve the above problems, the gist of the present invention is as follows.

  A water electrolysis apparatus that electrolyzes water to generate hydrogen and oxygen, an aqueous electrolyte solution containing an intermediate product that repeats a redox reaction, an electrolytic electrode that electrolyzes water, and a redox reaction of the intermediate product An intermediate electrode and an electrolytic cell for accommodating these, the intermediate product has a higher redox potential than the hydrogen generation potential of the intermediate product and the intermediate product, and the intermediate product has a higher redox potential than the electrolytic electrode. It is characterized by being lower than the hydrogen generation potential.

  According to the present invention, it is possible to provide a water electrolysis system in which hydrogen gas and oxygen gas are generated from electrodes at different timings.

The figure which shows an example of a structure of the bipolar water electrolyzer of a present Example. The figure which shows an example of a structure of the tripolar type water electrolyzer of a present Example. The figure which shows the gas piping of a present Example. The block diagram of the renewable energy storage and supply system of a present Example.

  FIG. 1 shows an example of the configuration of a bipolar water electrolyzer 101 that is one embodiment of the present invention. In the water electrolysis apparatus 101 of the present embodiment, an electrolytic electrode 103 that electrolyzes water and an intermediate electrode 102 that performs an oxidation-reduction reaction of an intermediate product are installed inside an electrolytic cell 112 that contains an aqueous electrolyte solution 107. Yes. A partition wall 104 is provided between the intermediate electrode 102 and the electrolytic electrode 103 to prevent a reverse reaction of the generated gas. The aqueous electrolyte solution 107 contains an intermediate product that repeats a redox reaction.

  In the electrolysis apparatus having such a configuration, the intermediate product 102 has a higher redox potential than the intermediate product 102 and the intermediate product, and the intermediate product has a higher redox potential than the intermediate electrode 102. By making the relationship lower than the potential, hydrogen gas and oxygen gas can be generated from the electrolytic electrode 103 at different timings.

In a general water electrolyzer, when water is electrolyzed by applying a voltage between electrodes, oxygen is generated from the anode and hydrogen is generated from the cathode by the reactions of the formulas (1) and (2).
Anode: 2H ₂ O → O ₂ + 4H ⁺ + 4e ⁻ (1)
Cathode: 2H ⁺ + 2e ⁻ → H ₂ (2)

On the other hand, in the water electrolysis apparatus 101 of this embodiment, when a predetermined voltage is applied between the intermediate electrode 102 and the electrolytic electrode 103 by connecting the power source 108, an electric current flows between the two electrodes and the electrochemical reaction occurs. Progresses. First, on the surface of the electrolytic electrode 103, water is oxidized by the oxidation reaction of the formula (1) to generate oxygen gas 109. On the other hand, the reduction reaction proceeds on the surface of the intermediate electrode 102. At this time, since the oxidation-reduction potential of the intermediate product is higher than the hydrogen generation potential of the intermediate electrode 102 and the intermediate product, the intermediate product 102 is not the reduction reaction of the formula (2) but the oxidized product 105 of the intermediate product. The reduction reaction in which is reduced to the reductant 106 proceeds. For example, when zinc is used as an intermediate product, the reaction of the following formula (3) proceeds. Here, zinc ions (Zn ²⁺ ) are the oxidant 105, and zinc (Zn) is the reductant 106.
Intermediate electrode: Zn ²⁺ + 2e ⁻ → Zn (3)

After the predetermined amount of the intermediate product oxidant 105 is changed to the reductant 106, when the load 110 is connected to the water electrolysis apparatus 101 or the electrodes are short-circuited, the redox potential of the intermediate product is reduced to that of the electrolytic electrode 103. When the relationship is lower than the hydrogen generation potential, an oxidation reaction proceeds on the surface of the intermediate electrode 102 and a reduction reaction proceeds on the surface of the electrolytic electrode 103. At this time, an oxidation reaction in which the reductant 106 returns to the oxidant 105 proceeds on the surface of the intermediate electrode 102. For example, when zinc is used as an intermediate product, the reaction of the following formula (4) proceeds.
Intermediate electrode: Zn → Zn ²⁺ + 2e ⁻ (4)

  Electrons emitted from the reductant 106 flow from the intermediate electrode 102 through the load 110 to the electrolytic electrode 103, and hydrogen gas 111 is generated on the surface of the electrolytic electrode 103 by the reduction reaction of formula (2).

  As described above, in the water electrolysis apparatus of the present embodiment, only oxygen gas is generated when a voltage is applied to the water electrolysis apparatus (during charging), and during discharge when the water electrolysis apparatus is connected to a load or a short circuit. Only hydrogen gas is generated. This is because an intermediate product that repeats changes from the oxidant 105 to the reductant 106 and from the reductant 106 to the oxidant 105 is used, and the electric power input to the water electrolysis apparatus is temporarily stored as the reductant 106 of the intermediate product. By doing so, it becomes possible to generate only one gas of oxygen or hydrogen at an arbitrary time inside the electrolytic cell. Furthermore, in the water electrolysis apparatus of the present embodiment, the power is stored as a reductant by the reduction reaction of the intermediate product when power is input, and then the power can be taken out by connecting the electrodes to a load. A water electrolysis apparatus having a discharge function is obtained.

  The intermediate product only needs to have a redox potential higher than the hydrogen generation potential. The intermediate product can be used as a water-soluble molecule such as an organic molecule or a metal complex. However, when both the oxidant and the reductant are water-soluble, the reverse reaction proceeds at the counter electrode, which is not desirable. Therefore, it is desirable that the reductant 106 that plays a role of storing input power is solid. In particular, a metal is more desirable because the density of the reductant is high and can be stably fixed to the surface of the intermediate electrode 102. Examples of the metal whose oxidation-reduction potential is higher than the hydrogen generation potential include zinc, iron, lead, tin, nickel, and alloys thereof. However, it is desirable to use zinc because of hydrogen generation as a side reaction and environmental problems.

  The intermediate electrode 102 that performs the oxidation-reduction reaction of the intermediate product only needs to have a hydrogen generation potential lower than the oxidation-reduction potential of the intermediate product and high adhesion to the deposited metal. At this time, the hydrogen generation overvoltage is preferably small. In addition, since metal ions are deposited on the intermediate electrode 102 during the reduction of the intermediate product, it is preferable that the adhesion with the deposited metal is high. From the viewpoint of adhesion to the deposited metal, it is preferable to use the same metal material as the intermediate product metal. When zinc is used as an intermediate product, it is desirable to use a zinc electrode as the intermediate electrode 102, but it is also possible to use copper, gold, or carbon in addition to zinc.

  The aqueous electrolyte solution 107 may be an aqueous solution containing metal ions that are intermediate products. In particular, an aqueous solution having high solubility of metal ions and high conductivity is desirable. Regarding the concentration of metal ions in the aqueous electrolyte solution 107, the higher the concentration, the greater the amount of stored power, which is preferable. However, the higher the concentration, the lower the conductivity of the aqueous electrolyte solution, so about 0.01 to 10 mol / liter. desirable. Further, ions other than metal ions may be added to improve conductivity. In general, an alkaline electrolyte aqueous solution used in water electrolysis may be used, but an aqueous solution containing metal ions such as a plating solution may be used.

  As the electrolytic electrode 103, one having a hydrogen generation potential higher than the oxidation-reduction potential of the intermediate product is used. In the case of the configuration of the bipolar water electrolysis apparatus 101, a material having a small hydrogen generation overvoltage and oxygen generation overvoltage is preferable, and a metal material containing at least one of platinum, rhodium, and nickel can be used. . It is desirable that the electrode has a high specific surface area in order to promote an electrochemical reaction. Therefore, shapes such as a porous body, a mesh, a punching metal, an expanded metal, and a nonwoven fabric are preferable. Further, roughening or high specific surface area plating may be applied.

  In the water electrolysis apparatus of the present embodiment, only hydrogen gas can be generated at an arbitrary time, so that the partition wall 104 does not require low gas permeability. In order to prevent the reverse reaction of the generated gas, the partition wall 104 is necessary, but may be a porous film. Specifically, it is possible to use a low-cost partition wall used for plating or a storage battery such as a lead storage battery.

  Although the water electrolysis apparatus 101 of FIG. 1 is a bipolar type, the electrolytic electrode 103 may be divided into a hydrogen generation electrode and an oxygen generation electrode. FIG. 2 shows an example of the configuration of the tripolar water electrolyzer 201. An intermediate electrode 202 that performs an oxidation-reduction reaction of an intermediate product in an electrolytic cell 214 in which an aqueous electrolyte solution 208 is accommodated, an oxygen-generating electrolytic electrode 203 that generates oxygen by water oxidation reaction on one side, and the other An electrolytic electrode 204 for hydrogen generation that generates hydrogen by a reduction reaction of water is installed on the surface side. As in FIG. 1, a partition wall 205 is provided between the electrodes in order to prevent the reverse reaction of the generated gas. Further, the electrolyte aqueous solution 208 contains an intermediate product that repeats the redox reaction of the reductant 206 and the oxidant 207. A power source 209 and a load 210 are connected to the water electrolysis apparatus 201 in FIG. 2, and the connection is switched by switching the connection switches 211 and 212 respectively. When connecting to the power source 209, the connection switch 212 is turned on and the connection switch 211 is turned off. When connecting to the load 210, the connection switch 211 is turned on and the connection switch 212 is turned off. When a voltage is applied between the intermediate electrode 202 and the oxygen generating electrolytic electrode 203 by connecting to the power source 209, the reduction reaction of the intermediate product proceeds on the surface of the intermediate electrode 202 as in FIG. On the surface, oxygen 213 is generated by the reaction of the formula (1). On the other hand, when the intermediate electrode 202 and the hydrogen generating electrolytic electrode 204 are connected by the load 209 in a state where a predetermined amount of the reductant 207 is stored, the oxidation reaction of the intermediate product proceeds on the surface of the intermediate electrode 202 as in FIG. On the surface of the hydrogen generating electrolytic electrode 204, hydrogen 214 is generated by the reaction of the formula (2).

  In the case of the tripolar water electrolyzer 201, a hydrogen generation electrode 204 having a hydrogen generation potential higher than the oxidation-reduction potential of the intermediate product is used. The oxygen generating electrolytic electrode 203 is not particularly limited in relation to the redox potential of the intermediate product. Further, in the case of the bipolar type, it is preferable that both the hydrogen generation overvoltage and the oxygen generation overvoltage are small. However, in the case of the tripolar type, the oxygen generation electrolytic electrode 203 only needs to have a small oxygen generation overvoltage. The generation electrode 204 only needs to have a small hydrogen generation overvoltage. For this reason, compared with the bipolar water electrolyzer 101, the kind of material which can be used as an electrode increases. Examples of the material having a small hydrogen generation overvoltage include platinum, rhodium, nickel, and iron. Examples of the material having a small oxygen generation overvoltage include platinum, silver, rhodium, nickel, iron, manganese dioxide, cobalt, silver, carbon, and a phthalocyanine complex. In particular, the oxygen-generating electrolytic electrode 203 preferably has an area of about 10 to 1000 times the apparent surface area because gaseous oxygen has a low density. Specifically, a thin film electrode in which high specific surface area particles such as carbon black and metal powder are formed with a binder can be used.

  Next, FIG. 3 shows an example of gas piping of the water electrolysis apparatus according to the embodiment of the present invention. According to the water electrolysis apparatus of the present invention, it is possible to take out either hydrogen or oxygen into the electrolytic cell at an arbitrary time. For this reason, a flow path for extracting gas from each of the hydrogen electrode side and the oxygen electrode side, which has conventionally been separated by a stack structure in space, was necessary. In the water electrolysis apparatus of the present embodiment, as shown in FIG. As described above, it is only necessary to connect one flow path for taking out the gas to the electrolytic cell, and piping can be reduced. Moreover, it becomes possible to collect | recover, without mixing hydrogen and oxygen by switching piping by a three-way valve according to the kind of generated gas.

  According to the present invention, oxygen is generated from the electrolytic electrode when power is input, and the reduction reaction of the intermediate product proceeds at the intermediate electrode. When connected to a load, the reduced product of the intermediate product is oxidized, and hydrogen is generated at the electrolytic electrode. At this time, a voltage equal to the potential difference between the redox potential of the intermediate product and the hydrogen generation potential of the electrolytic electrode is applied to the load, and a current proportional to the amount of hydrogen generation flows. That is, electric power can be taken out simultaneously with hydrogen production. Since the amount of generated power is proportional to the potential difference between the redox potential of the intermediate product and the hydrogen generation potential at the electrolytic electrode, it is desirable to use zinc as the intermediate product and platinum or nickel and their alloys as the electrolytic electrode. .

  Next, FIG. 4 shows an example of a renewable energy storage / supply system including a water electrolyzer having a charge / discharge function of the present invention. Electric power generated by a renewable energy power generation unit such as a wind power generator or solar power generation is converted into a desired power form by the power conversion unit and supplied to a power consumer such as a grid power network. Here, since the power generated by the renewable energy power generation unit fluctuates, if it is directly connected to the grid power grid, a load is applied to the grid, causing a failure such as a power failure. For this reason, only the electric power according to a demand is sent to a system, and surplus electric power is converted into hydrogen by inputting into a water electrolysis device, and is stored as hydrogen energy. Hydrogen produced by the water electrolyzer is added to organic molecules with high energy density and stored in a tank as organic hydride in the reactor of the fuel storage control unit. On the other hand, when the amount of power generated by the renewable energy power generation unit is insufficient with respect to the power demand, hydrogen is taken out by the dehydrogenation reaction of the organic hydride stored in the tank, and the engine generator of the power generation unit is used using hydrogen. Then, power is generated by a turbine or the like to supply the insufficient power.

Here, since the water electrolysis apparatus of this embodiment has a charge / discharge function, it is possible to supply power from the water electrolysis apparatus when power is insufficient. Thereby, it is possible to have a function of leveling electric power derived from renewable energy. The charge / discharge switching of the water electrolysis apparatus is controlled by the control unit, for example, by monitoring the power generation amount of the renewable energy power generation unit. Further, the water electrolysis apparatus of the present embodiment has a feature that hydrogen is generated at the time of discharging, not at the time of power input, unlike the conventional water electrolysis apparatus. For this reason, when power is insufficient, it is possible to supply power from the water electrolyzer and also supply hydrogen generated in the water electrolyzer directly to the power generation unit. In addition, as a system operation method, during the generation of electricity by the renewable energy power generation unit, the oxygen generation reaction and the reduction reaction of the intermediate product proceed to store power, and when the renewable energy power generation unit is not generating power, the intermediate generation It is also possible to supply power by advancing the hydrogen generation reaction and the intermediate product oxidation reaction using the energy stored as the reduced product.
(Evaluation 1)
A water electrolysis apparatus having the configuration shown in FIG. 1 was produced and evaluated for characteristics. The intermediate electrode 102 was made of a copper mesh, and the electrolytic electrode 103 was made of nickel expanded metal having a high specific surface area. As the aqueous electrolyte solution 107, an aqueous potassium hydroxide solution in which zinc sulfate was dissolved was used. A porous polyethylene thin film was used for the partition 104.

  First, when 2.3 V was passed between the intermediate electrode 102 and the electrolytic electrode 103 as input power from the power source 108, an oxidation current flowed through the electrolytic electrode 103, and oxygen bubbles were generated from the electrode surface. Further, a reduction current flowed through the intermediate electrode 102, and the intermediate electrode 102 turned gray. This confirmed that oxygen generation and zinc precipitation proceeded.

Thereafter, the input of electric power was stopped, and the electrolytic electrode 103 and the intermediate electrode 102 were short-circuited. As a result, a reduction current flowed through the electrolytic electrode 103 and hydrogen bubbles were generated from the surface of the electrolytic electrode 103.
In addition, a reduction current flowed through the intermediate electrode 102, and the intermediate electrode 102 returned to copper color. From this, it was confirmed that hydrogen gas was generated on the surface of the electrolytic electrode 103 by the zinc dissolution reaction.
From the above results, it was confirmed that hydrogen gas and oxygen gas were generated from the electrolytic electrode 103 at different timings, and hydrogen and oxygen could be extracted individually.
(Evaluation 2)
A water electrolysis apparatus having the configuration shown in FIG. 1 was manufactured, and after inputting electric power in the same manner as in Evaluation 1, the characteristics were evaluated by connecting an electronic load. When the current was applied at a current density of 10 mA / cm ² , the intermediate electrode 102 returned to copper color as in Evaluation 1, and hydrogen bubbles were generated from the surface of the electrolytic electrode 103. The voltage between the intermediate electrode 102 and the electrolytic electrode 103 was 0.45V. From this result, it can be confirmed that in the water electrolysis apparatus having the configuration shown in FIG. 1, after the input power is stored as the reductant 106, the power is taken out between the intermediate electrode 102 and the electrolytic electrode 103 by connecting a load. It was.
(Evaluation 3)
A water electrolysis apparatus having the configuration shown in FIG. 2 was produced and evaluated for characteristics. The intermediate electrode 202 was made of a copper mesh, the electrolytic electrode was made of titanium expanded metal carrying iridium on the oxygen generating electrode 203, and the platinum mesh was used for the hydrogen generating electrode 204. As the electrolyte aqueous solution 208, a sodium sulfate aqueous solution in which zinc sulfate was dissolved was used. A porous polyethylene thin film was used for the partition wall 205.

  First, when 2.3 V was passed between the intermediate electrode 202 and the oxygen generation electrode 203 as input power from the power source 209, an oxidation current flowed through the oxygen generation electrode 203, and oxygen bubbles were generated from the electrode surface. Further, a reduction current flowed through the intermediate electrode 202, and the color changed to gray. This confirmed that oxygen generation and zinc precipitation proceeded.

Thereafter, the input of electric power is stopped, an electronic load is connected between the hydrogen generation electrode 204 and the intermediate electrode 202, and energization is performed at a current density of 10 mA / cm ^{2. As} a result, a reduction current flows through the hydrogen generation electrode 204, Hydrogen bubbles were generated from the surface of the generation electrode 204. Further, a reduction current flowed through the intermediate electrode 202, and the intermediate electrode 102 returned to a copper color. The voltage between the intermediate electrode 202 and the hydrogen generation electrode 204 was 0.6V. From this result, it is confirmed that the tripolar water electrolyzer in FIG. 2 also takes out hydrogen and oxygen individually by arbitrarily changing the wiring connection and obtains power between the intermediate electrode and the hydrogen generating electrode. did it.

DESCRIPTION OF SYMBOLS 101 Hydrogen generator 102 Intermediate electrode 103 Electrode electrode 104 Partition 105 Intermediate product oxidant 106 Intermediate product reductant 107 Electrolyte aqueous solution 108 Power supply 109 Oxygen gas 110 Load 111 Hydrogen gas 112 Electrolyzer

Claims (12)

A water electrolyzer that electrolyzes water to generate hydrogen and oxygen,
An aqueous electrolyte solution containing an intermediate product that repeats the oxidation-reduction reaction, an electrolytic electrode that electrolyzes water, an intermediate electrode that performs an oxidation-reduction reaction of the intermediate product, and an electrolytic cell that accommodates these,
Hydroelectricity characterized in that the redox potential of the intermediate product is higher than the hydrogen generation potential of the intermediate electrode and the intermediate product, and the redox potential of the intermediate product is lower than the hydrogen generation potential of the electrolytic electrode. Disassembly equipment.   2. The water electrolysis apparatus according to claim 1, wherein the redox of the intermediate product is dissolution and precipitation of a metal.   The water electrolysis apparatus according to claim 2, wherein the metal to be dissolved and precipitated is zinc, iron, or lead alone or an alloy.   4. The water electrolysis apparatus according to claim 3, wherein the aqueous electrolyte solution contains metal ions, and the concentration of metal ions is in the range of 0.01 to 10 mol / liter.   3. The water electrolysis apparatus according to claim 2, wherein when hydrogen is generated, electric power having a voltage corresponding to a potential difference between a hydrogen overvoltage of the electrolytic electrode and a redox potential of the intermediate product is supplied. .   2. The water electrolysis apparatus according to claim 1, wherein there is one pipe connected to the electrolytic cell for taking out gas generated in the water electrolysis apparatus.   The water electrolyzer according to claim 1, further comprising a porous partition wall between the electrodes.   2. The water electrolysis apparatus according to claim 1, wherein the electrolysis electrode has two electrodes: an oxygen generation electrolysis electrode that generates oxygen by water oxidation reaction and a hydrogen generation electrolysis electrode that generates hydrogen by water reduction reaction A water electrolysis apparatus comprising: A water electrolyzer that electrolyzes water to generate hydrogen and oxygen,
An aqueous electrolyte solution containing an intermediate product that repeats the oxidation-reduction reaction, an electrolytic electrode that electrolyzes water, an intermediate electrode that performs an oxidation-reduction reaction of the intermediate product, and an electrolytic cell that accommodates these,
Water electrolysis characterized in that the intermediate electrode is zinc, the intermediate product is zinc or zinc ions, and the electrolytic electrode is a metal containing at least one of platinum, rhodium, nickel, and iron. apparatus. A water electrolyzer that electrolyzes water to generate hydrogen and oxygen,
An aqueous electrolyte solution containing an intermediate product that repeats the oxidation-reduction reaction, an electrolytic electrode that electrolyzes water, an intermediate electrode that performs an oxidation-reduction reaction of the intermediate product, and an electrolytic cell that accommodates these,
When oxygen is generated at the electrolytic electrode, the reduction reaction of the intermediate product proceeds at the intermediate electrode. When hydrogen is generated at the electrolytic electrode, the oxidation reaction of the intermediate product proceeds at the intermediate electrode. A hydrogen generator, wherein oxygen or hydrogen is generated at different timings inside. Renewable energy power generation means for converting renewable energy into electric energy, water electrolysis apparatus for electrolyzing water using the power generated by the renewable energy power generation means, and manufactured by the water electrolysis apparatus In an energy storage and supply system comprising a hydrogen-based power generation means for generating power using hydrogen,
The energy storage / supply system according to claim 1, wherein the water electrolysis apparatus is the water electrolysis apparatus according to claim 1.   12. The energy storage / supply system according to claim 11, wherein when the renewable energy power generation means generates power, the water electrolysis device causes an oxygen generation reaction and an intermediate product reduction reaction to proceed, and the renewable energy power generation facility generates power. An energy storage / supply system characterized in that when the water electrolysis device is not operating, the hydrogen electrolysis device and the intermediate product oxidation reaction are allowed to proceed to supply electric power from the water electrolysis device.