WO2023136148A1

WO2023136148A1 - Electrolysis system

Info

Publication number: WO2023136148A1
Application number: PCT/JP2022/048338
Authority: WO
Inventors: 友和戸澤; 邦裕中野
Original assignee: 株式会社カネカ
Priority date: 2022-01-12
Filing date: 2022-12-27
Publication date: 2023-07-20

Abstract

The present invention provides an electrolysis system capable of decomposing an electrolyte more efficiently than before. The system is configured to comprise: a solar cell; an electrolytic tank having a photocatalyst electrode, a counter electrode, and an electrolyte; a supply flow path for supplying the electrolyte to the electrolytic tank; and a heat transfer unit disposed partway in the supply flow path and transferring heat of the solar cell to the electrolyte passing through the supply flow path.

Description

electrolysis system

The present invention relates to an electrolytic system that decomposes an electrolytic solution such as water.

In recent years, with the spread of fuel cell modules, the demand for hydrogen raw materials used for the fuel electrodes of fuel cell modules is increasing.
As a method for producing a hydrogen raw material, a photocatalyst that decomposes water with sunlight to generate hydrogen is attracting attention (for example, Patent Document 1).
In the method of producing hydrogen raw materials using a photocatalyst, sunlight is received by an electrode coated with a photocatalyst (hereinafter also referred to as a photocatalyst electrode), and by applying a water decomposition voltage between the photocatalyst electrode and the counter electrode, Since water is decomposed and hydrogen can be generated without emitting carbon dioxide, the environmental impact is smaller than that of conventional hydrogen production methods using fossil fuels.

WO2019/216284

However, although electrolyzers using photocatalysts have a small environmental impact, the efficiency of water electrolysis is low, and further improvements in electrolysis efficiency have been sought.

Therefore, an object of the present invention is to provide an electrolysis system capable of decomposing an electrolytic solution more efficiently than before.

In order to solve the above-described problems, the inventors examined the following.
In a water electrolyzer using a photocatalyst, the voltage for electrolyzing water is insufficient, so a solar cell is often provided as an auxiliary power source to apply a voltage up to the electrolysis potential of water by the electromotive force of the solar cell.
The power generation efficiency of solar cells, for example, in the case of silicon solar cells, tends to decrease as the temperature rises, but under sunlight, the temperature of the solar cell tends to rise significantly compared to room temperature. .
On the other hand, in electrolysis devices using photocatalyst electrodes, for example, photocatalyst electrodes using metal oxides such as bismuth vanadate and iron oxide tend to improve charge carrier transport and increase electrolysis efficiency when the operating temperature is raised. be.
Therefore, the present inventor thought that the power generation efficiency of the solar cell and the electrolysis efficiency of the electrolyzer could both be improved by using the amount of heat generated by the solar cell to heat the electrolyzer.

One aspect of the present invention derived based on the above idea is a solar cell, an electrolytic cell having a photocatalyst electrode, a counter electrode, and an electrolytic solution, a supply channel for supplying the electrolytic solution to the electrolytic cell, and The electrolysis system includes a heat transfer section that is provided in the middle of the supply channel and that transfers heat from the solar cell to the electrolytic solution passing through the supply channel.

The "heat of solar cells" here includes not only the amount of heat generated by solar cells generating electricity, but also the amount of heat generated when heated by light such as sunlight.

According to this aspect, since the heat of the solar cell heats the electrolyte, the temperature of the electrolyte in the electrolytic cell can be raised while the solar cell is cooled by the electrolyte. Therefore, the electrolysis efficiency of the electrolytic solution in the electrolytic cell can be improved while improving the power generation efficiency of the solar cell.

A preferable aspect is that the electrolytic cell is arranged on the solar cell.

According to this aspect, the heat of the solar cell can be transferred to the electrolytic cell, so the electrolytic solution can be decomposed more efficiently.

A preferred aspect is that the solar cell applies a voltage between the photocatalyst electrode and the counter electrode.

According to this aspect, the power generated by the solar cell can be used for electrolysis in the electrolytic cell, so the energy efficiency when generating hydrogen can be improved.

Here, the absorption wavelength range of general photocatalysts is often 600 nm or less. That is, even if the photocatalyst is irradiated with light having a wavelength of more than 600 nm, the electrolysis efficiency does not change so much in many cases.
On the other hand, some solar cells can generate power over a wide wavelength range, even with light exceeding 600 nm.
Therefore, by separating the sunlight, irradiating the photocatalyst with short-wavelength light, and irradiating the solar cell with long-wavelength light, it is possible to reduce the energy loss of the sunlight and improve the overall energy efficiency. Thought.

A preferable aspect derived from this idea is that the electrolytic bath separates the transmitted light into short-wavelength light having a predetermined wavelength or less and long-wavelength light having a longer wavelength than the short-wavelength light. It is provided with a wavelength separating section that guides wavelength light to the photocatalyst electrode and guides long-wavelength light to the solar cell.

According to this aspect, the wavelength separator guides the light in the short wavelength region, which is easily absorbed by the photocatalyst electrode, to the photocatalyst electrode, and guides the light in the long wavelength region, which is hardly used in the electrolysis of the photocatalyst electrode, to the solar cell. can improve efficiency.

A more preferable aspect is to provide an antireflection film on the wavelength separation section.

According to this aspect, it is possible to prevent the light incident on the wavelength separation section from being reflected, and to confine the light to the electrolytic cell side.

A preferable aspect is that the electrolytic cell has a light-receiving portion for receiving light, and the counter electrode is positioned closer to the light-receiving portion than the photocatalyst electrode.

A preferred aspect is that it has at least two electrolytic cells, and the solar cell is positioned between the photocatalyst electrodes of the two electrolytic cells when the solar cells are viewed from above.

According to this aspect, one solar cell can heat two electrolytic cells at the same time.

A preferred aspect has a gas storage part, the electrolytic cell has an ion exchange part between the photocatalyst electrode and the counter electrode, and the ion exchange part divides the electrolytic cell into a space on the side of the photocatalyst electrode and the It is divided into a space on the counter electrode side, and the gas storage part communicates with the space on the counter electrode side and can store the gas flowing out from the space on the counter electrode side.

According to this aspect, the gas in the space on the counter electrode side can be stored in the gas storage part without being mixed with the gas in the space on the photocatalyst electrode side.

A more preferable aspect is to have a connecting portion that connects the gas storage portion and the electrolytic cell, and that the connecting portion is connected to the top side of the electrolytic cell rather than the counter electrode.

According to this aspect, it is easy to recover the gas in the space on the counter electrode side.

A preferred aspect has at least two electrolytic cells, the two electrolytic cells have an ion exchange section between the photocatalyst electrode and the counter electrode, and the ion exchange section directs the electrolytic cell to the photocatalytic electrode side. and the space on the counter electrode side, the two electrolytic cells are provided with a communication flow path in which the space on the photocatalyst electrode side communicates, and the two electrolytic cells are a first electrolytic cell and a first electrolytic cell. It has two electrolytic cells, and has an electrolytic solution supply unit that supplies the electrolytic solution to the space on the photocatalyst electrode side of the first electrolytic cell, and the communication flow path extends from the first electrolytic cell side to the second electrolytic cell in the middle. 2. A check valve is provided that allows only the movement of the electrolyte to the electrolytic cell side.

According to this aspect, by supplying the electrolytic solution to the space on the photocatalyst electrode side of the first electrolytic cell by the electrolytic solution supply unit, the electrolytic solution in the space on the photocatalytic electrode side of the first electrolytic cell is supplied to the space of the second electrolytic cell. It is extruded into the space on the side of the photocatalyst electrode. Therefore, the decomposed product obtained by decomposing the electrolytic solution on the photocatalyst electrode side can be concentrated in the second electrolytic cell.

By the way, as a method of heating an electrolytic cell by a solar cell, a method of heating via an electrolytic solution and a method of directly heating an electrolytic cell are conceivable.

Therefore, in one aspect of the present invention, a solar cell has an electrolytic cell having a photocatalyst electrode, a counter electrode, and an electrolytic solution, and the solar cell receives light that has passed through the electrolytic cell to generate power. A part or all of the generated electric power is supplied to the electrolytic cell, and the electrolytic cell is an electrolytic system that decomposes the electrolytic solution using the electric power supplied from the solar cell.

According to this aspect, since the electrolytic cell is positioned above the solar cell, the electrolytic cell is heated by the amount of heat generated by the solar cell, and the electrolysis efficiency of the electrolytic solution in the electrolytic cell can be improved.
According to this aspect, the solar cell receives the light that is attenuated by the photocatalyst electrode and transmitted. That is, since the solar cell receives light that has passed through the photocatalyst electrode, shadows and the like do not occur locally. etc. can be suppressed.

According to the electrolysis system of the present invention, the electrolytic solution can be decomposed more efficiently than before.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing of the electrolysis system of 1st Embodiment of this invention, (a) is sectional drawing of an electrolysis system, (b) is sectional drawing in a cross section different from (a). Note that (a) omits the electrolytic solution for easy understanding. 2 is an exploded perspective view of the electrolysis system of FIG. 1; FIG. 2 is an explanatory diagram of the flow of light when light is incident on the light receiving section in the electrolysis system of FIG. 1; FIG. FIG. 3 is a view in the direction of arrow A in FIG. 2 when the electrolysis system in FIG. 1 is installed with an inclination with respect to the horizontal plane. It is explanatory drawing of the electrolysis system of 2nd Embodiment of this invention, (a) is sectional drawing of an electrolysis system, (b) is sectional drawing in a cross section different from (a). Note that (a) omits the electrolytic solution for easy understanding. FIG. 6 is a side view when the electrolysis system of FIG. 5 is installed with an inclination with respect to the horizontal plane; It is explanatory drawing of the electrolysis system of 3rd Embodiment of this invention, (a) is sectional drawing of an electrolysis system, (b) is sectional drawing in a cross section different from (a). Note that (a) omits the electrolytic solution for easy understanding. FIG. 4 is a cross-sectional view of essential parts of an electrolysis system according to another embodiment of the present invention, omitting the electrolyte for ease of understanding;

Hereinafter, embodiments of the present invention will be described in detail.

The electrolysis system 1 of the first embodiment of the present invention includes, as shown in FIG. A liquid supply system 5, a gas recovery system 7,

solution communication channels

8a and 8b, and a solution recovery system 9 are provided.
The electrolysis system 1 uses the electric power generated by the solar cell 3 to electrolyze the

electrolytic solutions

25a and 25b in the electrolytic cell 2, and is capable of executing a hydrogen generation operation of generating hydrogen.

(Electrolyzer 2)
As shown in FIG. 1, the electrolytic cell 2 includes a cell main body 20, a photocatalyst electrode 21, a counter electrode 22, an ion exchange section 23, and

electrolytic solutions

25a and 25b.
In addition, as shown in FIG. 1A, the electrolytic cell 2 is divided into a first electrolytic space 26, which is a space on the photocatalyst electrode 21 side, and a second electrolytic space, which is a space on the counter electrode 22 side, by the ion exchange unit 23. 27 are divided.

As shown in FIG. 2, the tank main body 20 is a box-shaped body having a prism portion 30, a bottom wall portion 31, and

side wall portions

32a and 32b.
As shown in FIG. 3, the prism unit 30 separates the transmitted light L1 into short-wavelength light L2 and long-wavelength light L3 based on a predetermined wavelength, guides the short-wavelength light L2 to the photocatalyst electrode 21, and converts the light L1 into long-wavelength light. It is a wavelength separator that guides L3 to the solar cell 3 .
The prism portion 30 constitutes the ceiling wall portion of the tank body portion 20 and is a light receiving portion that receives light.
As shown in FIGS. 2 and 3, the prism portion 30 has a first inclined portion 36 and a second inclined portion 37 with a bottom line portion 35 as a boundary. A concave groove 38 having a triangular shape is formed.
The

inclined portions

36 and 37 are provided with

gas recovery holes

40a and 40b as shown in FIG. 1(b).
The

gas recovery holes

40a and 40b are gas discharge holes for recovering the gas in the second electrolysis space 27, and are through holes penetrating with a vertical component.

The bottom wall portion 31 is a wall portion that constitutes the bottom portion of the tank body portion 20 and is a facing wall portion that faces the prism portion 30 with the ion exchange portion 23 interposed therebetween.
As shown in FIG. 1, the bottom wall portion 31 includes an electrolyte inlet 41, communication ports 42 (42a, 42b), and an outlet 43 as necessary.
The electrolytic solution introduction port 41 is an opening through which the electrolytic solution 25a is introduced.
The communication port 42 (42a, 42b) is an opening for communicating the first electrolysis space 26 of itself with the first electrolysis space 26 of the adjacent electrolytic cell 2. As shown in FIG.
The discharge port 43 is an opening through which the electrolytic solution 25a is discharged from the electrolytic cell 2 to the outside.

The

side wall portions

32a and 32b are connection walls that connect the prism portion 30 and the bottom wall portion 31, as shown in FIG.

The photocatalyst electrode 21 is an anode electrode that oxidizes the electrolytic solution 25a by receiving light to generate hydrogen peroxide.
The photocatalyst electrode 21 is formed by laminating a photocatalyst on a conductive substrate.
The conductive substrate is not particularly limited as long as it has conductivity. For example, a transparent conductive oxide substrate in which a transparent conductive oxide is laminated on a transparent substrate, a metal substrate, etc. can be used. .
The photocatalyst is not particularly limited as long as it has photocatalytic activity. Examples of photocatalysts include tungsten trioxide ( _WO3 ) catalysts, bismuth vanadate ( _BiVO4 ) catalysts, tin oxide ( _SnO2 ) catalysts, titanium oxide ( _TiO2 ) catalysts, hematite ( _Fe2O3 ) catalysts, and the like _. Available.

The counter electrode 22 is an electrode that forms a pair with the photocatalyst electrode 21 and faces the photocatalyst electrode 21 with the ion exchange portion 23 interposed therebetween. .
The counter electrode 22 is mesh-like and has a plurality of openings so that light can pass through in the thickness direction.

The ion exchange part 23 is a film-like body, and is a part that allows only specific ions to move in the thickness direction and restricts the movement of the remaining ions and electrons.
The ion exchange section 23 of the present embodiment is a cation exchange membrane that restricts or disables movement of anions and electrons, and allows movement of only cations. In addition, the ion exchange section 23 also serves as a blocking membrane that blocks the flow of gas in the thickness direction.
The material of the ion exchange section 23 is not particularly limited as long as hydrogen and oxygen do not cross over.
As the ion exchange section 23, for example, a polymer membrane such as a perfluoroalkylsulfonic acid polymer membrane such as Nafion (registered trademark) can be used.

The electrolytic solution 25a generates hydrogen peroxide by oxidation, and is specifically an aqueous solution containing water.
The electrolytic solution 25b generates hydrogen by reduction, and is specifically an aqueous solution containing water.
The electrolytic solution 25b may be the same electrolytic solution as the electrolytic solution 25a, or may be a different electrolytic solution.

(Solar cell 3)
The solar cell 3 is a photoelectric conversion device that converts light energy into electrical energy.
The solar battery 3 has a plurality of solar cells, and each solar cell is electrically connected in series and/or electrically connected in parallel.
The solar cell 3 of this embodiment includes a solar cell string in which a plurality of solar cells are connected in series.

(Antireflection film 4)
As shown in FIG. 1, the antireflection film 4 is provided across the prism portions 30 of the electrolytic baths 2a to 2c, and is a film that suppresses reflected light of light incident from the prism portion 30 into the electrolytic baths 2a to 2c. be.
In other words, the antireflection film 4 confines the light entering the electrolytic baths 2a to 2c from the prism portion 30 within the electrolytic baths 2a to 2c.

(Electrolyte solution supply system 5)
The electrolytic solution supply system 5 is a supply system for supplying the electrolytic solution 25a to each of the electrolytic cells 2a to 2c.
As shown in FIG. 1, the electrolyte supply system 5 includes an electrolyte supply unit 50 and electrolyte supply channels 51a to 51c. The electrolytic solution 25a can be supplied to each electrolytic bath 2a to 2c.

As shown in FIG. 1A, the electrolytic solution supply channel 51a is a channel that connects the electrolytic solution supply part 50 to the electrolytic solution introduction port 41 of the electrolytic cell 2a, and includes an on-off valve 55a and a heat transfer part 56a. ing.
The on-off valve 55a is a member that is provided in the middle of the flow direction of the electrolytic solution supply channel 51a, and opens and closes the circulation of the electrolytic solution 25a by opening and closing.
The heat transfer portion 56a is a portion that exchanges heat between the electrolytic solution 25a passing through the electrolytic solution supply channel 51a and the solar cell 3a. It is a portion that conducts heat to the electrolytic solution 25a.
That is, in the heat transfer portion 56a, it is possible to heat the electrolytic solution 25a with the heat generated by the solar cell 3a. In other words, in the heat transfer portion 56a, the solar cell 3a can be cooled with the electrolytic solution 25a.

The electrolytic solution supply channel 51b is a channel that connects the electrolytic solution supply part 50 to the electrolytic solution introduction port 41 of the electrolytic bath 2b, and includes an on-off valve 55b and a heat transfer part 56b.
The on-off valve 55b is a member that is provided in the middle of the flow direction of the electrolytic solution supply channel 51b, and opens and closes the circulation of the electrolytic solution 25a by opening and closing.
The heat transfer part 56b is a part that exchanges heat between the electrolytic solution 25b passing through the electrolytic solution supply channel 51b and the solar cell 3b. It is a portion that conducts heat to the electrolytic solution 25a.
That is, in the heat transfer portion 56b, it is possible to heat the electrolytic solution 25a with the heat generated by the solar cell 3b. In other words, in the heat transfer portion 56b, the solar cell 3b can be cooled with the electrolytic solution 25a.

The electrolytic solution supply channel 51c is a channel that connects the electrolytic solution supply part 50 to the electrolytic solution introduction port 41 of the electrolytic bath 2c, and includes an on-off valve 55c.
The on-off valve 55c is a member that is provided in the middle of the flow direction of the electrolytic solution supply channel 51c and opens and closes the circulation of the electrolytic solution 25a by opening and closing.

(Gas recovery system 7)
The gas recovery system 7 is a system for recovering the hydrogen generated in each of the electrolytic cells 2a to 2c, and as shown in FIG. there is

The gas storage unit 60 is a hydrogen storage unit that stores the hydrogen generated in each of the electrolytic cells 2a to 2c, and allows hydrogen to be discharged to an external device or the like and introduced from an external device or the like as necessary. .

The gas recovery channel 61 is a connection channel that connects the

gas recovery holes

40a and 40b of the respective electrolytic cells 2a to 2c and the gas storage section 60, and the hydrogen generated in the second electrolytic space 27 from the respective electrolytic cells 2a to 2c. is collected and introduced into the gas storage unit 60 .

(

Solution communication channels

8a and 8b)
As shown in FIG. 1B, the solution communication channel 8a is a channel that communicates between the adjacent first electrolytic space 26 of the first electrolytic bath 2a and the first electrolytic space 26 of the second electrolytic bath 2b. It connects the communication port 42b of the first electrolytic bath 2a and the communication port 42a of the second electrolytic bath 2b.
The solution communication channel 8b is a channel for communicating between the adjacent first electrolytic space 26 of the second electrolytic bath 2b and the first electrolytic space 26 of the third electrolytic bath 2c. and the communication port 42a of the third electrolytic cell 2c.
The

solution communication channels

8a and 8b are provided with

check valves

70a and 70b in the middle of the flow direction.
The check valve 70a allows only the movement of the electrolytic solution 25a from the side of the first electrolytic bath 2a to the side of the second electrolytic bath 2b.
The check valve 70b allows only the movement of the electrolytic solution 25a from the side of the second electrolytic bath 2b to the side of the third electrolytic bath 2c.

(Solution recovery system 9)
The solution recovery system 9 is a system for recovering the hydrogen peroxide produced in the electrolytic cells 2a-2c.
The solution recovery system 9 includes a solution storage section 80 , a solution recovery channel 81 and an on-off valve 82 .
The solution storage part 80 is a part for storing the hydrogen peroxide generated in each of the electrolytic cells 2a to 2c, and it is possible to discharge hydrogen to an external device or the like or introduce hydrogen from an external device or the like as necessary. .

The solution recovery channel 81 is a connection channel that connects the outlet 43 of the third electrolytic cell 2c and the solution storage unit 80, recovers hydrogen peroxide from the first electrolytic space 26 of the third electrolytic cell 2c, and recovers the solution. This is a part to be introduced into the storage part 80 .
The on-off valve 82 is a member that is provided in the middle of the solution recovery channel 81 in the flow direction and opens and blocks the flow of hydrogen peroxide.

Next, the positional relationship of each part of the electrolysis system 1 of this embodiment will be described.

In the electrolytic system 1, as shown in FIG. 1, electrolytic cells 2 (2a to 2c) are arranged in a straight line in a predetermined direction.
As shown in FIG. 4, the electrolytic bath 2 (2a to 2c) is inclined at an inclination angle θ1 with respect to the horizontal plane GL, the prism part 30 faces the light source such as the sun, and the gas recovery channel 61 side is inclined. The position of the end is higher than the position of the end on the side opposite to the gas recovery channel 61 .
The inclination angle θ1 is preferably 15 degrees or more and 45 degrees or less.

As shown in FIG. 1, the

electrolytic cells

2a and 2b have the photocatalyst electrode 21 arranged on the first electrolytic space 26 side and the counter electrode 22 arranged on the second electrolytic space 27 side.
The photocatalyst electrode 21 faces the counter electrode 22 with the ion exchange portion 23 interposed therebetween, and is positioned below the counter electrode 22 .

The

solar cells

3a and 3b are placed on the

heat transfer portions

56a and 56b so that their back surfaces are in contact with each other, and the light receiving surfaces face upward.
The solar cell 3a is provided at the boundary between the first electrolytic bath 2a and the second electrolytic bath 2b. When the solar cell 3a is viewed from above, the photocatalyst electrode 21 of the first electrolytic bath 2a and the second electrolytic bath 2b are located between the photocatalyst electrodes 21 of the That is, the solar cell 3a has the

bottom walls

31, 31 of the

electrolytic vessels

2a, 2b above, and is in contact with the

bottom walls

31, 31 of the

electrolytic vessels

2a, 2b in this embodiment.
The solar cell 3b is provided at the boundary between the second electrolytic cell 2b and the third electrolytic cell 2c. When the solar cell 3b is viewed from above, the photocatalyst electrode 21 of the second electrolytic cell 2b and the third electrolytic cell 2c are located between the photocatalyst electrodes 21 of the That is, the solar cell 3b has the

bottom walls

31, 31 of the

electrolytic cells

2b, 2c above, and is in contact with the

bottom walls

31, 31 of the

electrolytic cells

2b, 2c in this embodiment.

Next, the operation of generating hydrogen by the electrolysis system 1 of this embodiment will be described.

First, in the electrolytic solution supply system 5 shown in FIG. 1A, the electrolytic solution 25a is supplied from the electrolytic solution supply unit 50 to the electrolytic cells 2a to 2c through the electrolytic solution supply channels 51a to 51c, and the first electrolysis is performed. The space 26 is filled with the electrolytic solution 25a. Further, an electrolytic solution 25b is supplied from an electrolytic solution supply unit (not shown) through an electrolytic solution supply flow path (not shown) to each of the electrolytic cells 2a to 2c to fill the second electrolytic space 27 with the electrolytic solution 25b.

When incident light L1 such as sunlight is incident from the prism portion 30, the incident light L1 is separated into short wavelength light L2 and long wavelength light L3 at the prism portion 30 as shown in FIG. 21 and the long-wavelength light L3 is guided to the solar cell 3 .
Specifically, the short-wavelength light L2 dispersed by the prism portion 30 mainly passes through the opening of the counter electrode 22, passes through the ion exchange portion 23, and reaches the photocatalyst electrode 21. FIG. Further, the long-wavelength light L3 split by the prism portion 30 is mainly transmitted through the ion exchange portion 23 and then through the bottom wall portion 31 to reach the light receiving surface of the solar cell 3 .
Then, photocharge separation occurs on the photocatalyst electrode 21 that receives the light, photovoltaic force is generated on the solar cell 3 at the same time, the first electrolytic solution 25a is decomposed on the photocatalyst electrode 21 to generate hydrogen peroxide, and the counter electrode 22 Above, the second electrolytic solution 25b is decomposed to generate hydrogen.

At this time, the hydrogen generated on the counter electrode 22 moves upward and is stored in the gas storage section 60 via the gas recovery channel 61 from the

gas recovery holes

40a and 40b.
On the other hand, the oxygen generated on the photocatalyst electrode 21 is released from vent holes (not shown) in the electrolytic cells 2a to 2c, and when hydrogen peroxide is generated, it is mixed with the first electrolytic solution 25a, resulting in a two-liquid mixed state. Become.

Here, a hydrogen peroxide concentration operation is performed as required.
Specifically, a fresh first electrolytic solution 25a is supplied from the electrolytic solution supply unit 50 shown in FIG. 1(a) to the first electrolytic cell 2a. When the first electrolytic solution 25a is supplied to the first electrolytic cell 2a, part of the first electrolytic solution 25a and part of hydrogen peroxide are extruded into the fresh electrolytic solution 25a as shown in FIG. 1(b). It flows into the adjacent second electrolytic cell 2b via the solution communication channel 8a.
When part of the first electrolytic solution 25a and part of the hydrogen peroxide are introduced into the second electrolytic bath 2b, part of the first electrolytic solution 25a and part of the hydrogen peroxide in the second electrolytic bath 2b are It is pushed out and flows into the adjacent third electrolytic cell 2c through the solution communication channel 8b shown in FIG. 1(b). Then, part of the first electrolytic solution 25a and part of the hydrogen peroxide are introduced into the third electrolytic bath 2c.
As a result, the hydrogen peroxide is concentrated in the third electrolytic cell 2c, and at the timing when the hydrogen peroxide is concentrated by a predetermined amount or more, the on-off valve 82 is opened, and the solution recovery flow path 81 is discharged from the third electrolytic cell 2c. The hydrogen peroxide is discharged to the solution storage unit 80 through the .

According to the electrolysis system 1 of the present embodiment, the heat of the solar cells 3 heats the first electrolytic solution 25a. The temperature of the electrolytic solution 25a can be raised. Therefore, while improving the power generation efficiency of the solar cell 3, the electrolysis efficiency of the first electrolytic solution 25a in the

electrolytic baths

2a and 2b can be improved.

According to the electrolysis system 1 of the present embodiment, the electrolytic cell 2 is arranged on the solar cell 3, and the heat generated in the solar cell 3 can be transferred to the electrolytic cell 2, so that the

electrolytic solutions

25a and 25b can be efficiently generated. can be decomposed.

According to the electrolysis system 1 of the present embodiment, part or all of the electromotive force generated by the solar cell 3 is applied between the photocatalyst electrode 21 and the counter electrode 22, so that the energy efficiency when generating hydrogen can be improved.

According to the electrolysis system 1 of the present embodiment, the short-wavelength light L2, which is easily absorbed by the photocatalyst electrode 21, is guided to the photocatalyst electrode 21 by the prism part 30, and the long-wavelength light L3, which is hardly used in the electrolysis of the photocatalyst electrode 21, is transferred to the solar cell. 3, energy efficiency can be improved.

According to the electrolysis system 1 of the present embodiment, since the antireflection film 4 is provided on the prism portion 30, the light incident on the prism portion 30 can be prevented from being reflected and emitted to the outside. It can be contained on two sides.

According to the electrolysis system 1 of this embodiment, since the solar cell 3 is positioned at the boundary between the adjacent

electrolytic cells

2, 2, a single solar cell 3 can heat the plurality of

electrolytic cells

2, 2 at the same time. Moreover, each light that has passed through the adjacent

electrolytic cells

2 , 2 can be collected in the solar cell 3 .

According to the electrolysis system 1 of the present embodiment, the first electrolysis space 26 and the second electrolysis space 27 are separated by the ion exchange section 23, so the gas in the first electrolysis space 26 and the gas in the second electrolysis space 27 can be stored in the gas storage unit 60 without being mixed.

According to the electrolysis system 1 of the present embodiment, the gas recovery channel 61 is connected to the prism portion 30 forming the top portion of the counter electrode 22, so the gas generated in the second electrolysis space 27 is lighter than air. In this case, the gas in the second electrolysis space 27 can be easily recovered.

According to the electrolysis system 1 of the present embodiment, the electrolytic solution supply unit 50 supplies the electrolytic solution 25a to the first electrolytic space 26 of the first electrolytic bath 2a, thereby of the electrolytic solution 25a is pushed into the first electrolytic space 26 of the second electrolytic cell 2b. Therefore, hydrogen peroxide, which is a decomposition product of the electrolytic solution 25a decomposed on the photocatalyst electrode 21 side, can be concentrated in the adjacent second electrolytic cell 2b.

According to the electrolysis system 1 of the present embodiment, since the electrolytic cell 2 is positioned above the solar cell 3, the electrolytic cell 2 is heated by the amount of heat generated by the solar cell 3, and the electrolytic solution 25a in the

electrolytic cell

2 , 25b can be improved.

According to the electrolysis system 1 of the present embodiment, the electrolytic cell 2 is inclined so that the gas recovery channel 61 side is at a higher position, so hydrogen generated at the counter electrode 22 tends to gather on the gas recovery channel 61 side.

Next, an electrolysis system 100 according to a second embodiment of the present invention will be described. In addition, about the structure similar to the electrolysis system 1 of 1st Embodiment, the same code|symbol is attached|subjected and description is abbreviate|omitted. The same shall apply hereinafter.

The electrolysis system 100 of the second embodiment includes, as shown in FIG. 107, a solution recovery system 9, and a malfunction detection means (not shown).

As shown in FIG. 5, the electrolytic baths 102a to 102c include a bath body 120, a photocatalyst electrode 21, a counter electrode 22, an ion exchange portion 23, and

electrolytic solutions

25a and 25b.
The tank main body 120 is a box-shaped body including a prism portion 30, a bottom wall portion 131, and

side wall portions

32a and 32b.
The bottom wall portion 131 has an electrolyte inlet 41 and, if necessary, an outlet 43 .

A side wall portion 32b of the first electrolytic cell 102a is provided with a liquid passage hole 145b and a gas communication hole 146b.
Liquid passage holes 145a and 145b and

gas communication holes

146a and 146b are provided in the

side walls

32a and 32b of the second electrolytic cell 102b.
A side wall portion 32a of the third electrolytic cell 102c is provided with a liquid passage hole 145a and a gas communication hole 146a, and a side wall portion 32b is provided with a gas recovery hole 140. As shown in FIG.
The liquid passage hole 145a is a through hole through which liquid can pass, and forms a communication hole that is continuous with the liquid passage hole 145b of the adjacent electrolytic cell 102 .
The gas communication hole 146a is a through hole through which gas can pass, and forms a communication hole that is continuous with the gas communication hole 146b of the adjacent electrolytic cell 102 .
The gas recovery hole 140 is a gas discharge hole for recovering gas in the second electrolysis space 27 of the third electrolytic cell 102c.

The electrolytic solution supply system 105 is composed of an electrolytic solution supply channel 51a, and a heat transfer portion 56a of the electrolytic solution supply channel 51a is provided across the plurality of

solar cells

3a and 3b.

The gas recovery system 107 is a system that recovers hydrogen from the gas recovery holes 140 of the third electrolytic cell 2c and introduces it into the gas storage section 60, and is composed of the gas storage section 60 and the gas recovery channel 61.

The malfunction detection means forcibly executes a safety ensuring operation, which will be described later, when a malfunction occurs in the electrical system of the electrolysis system 100 due to an external factor such as an earthquake or a power failure.
The failure detection means is, for example, a current detection device or a voltage detection device, and the electrolysis system 100 forcibly executes a safety ensuring operation when an abnormality occurs in current or voltage.

Next, the positional relationship of each part of the electrolysis system 100 of this embodiment will be described.

As shown in FIG. 6, the electrolytic cells 102a to 102c are inclined at an inclination angle θ2 with respect to the horizontal plane GL, the prism portion 30 faces the light source such as the sun, and the end portion on the side of the gas recovery hole 140 is positioned is higher than the position of the end opposite to the gas recovery hole 140 . That is, the third electrolytic bath 102c side is higher than the first electrolytic bath 102a side.
The inclination angle θ2 is preferably 15 degrees or more and 45 degrees or less.

Next, the hydrogen generation operation in the electrolysis system 100 of the second embodiment will be described.

First, in the electrolytic solution supply system 105, the electrolytic solution 25a is supplied from the electrolytic solution supply part 50 through the electrolytic solution supply channel 51a to the first electrolytic cell 102a, and then through the

liquid passage holes

145a and 145b to the remaining electrolytic cells 102b. , 102c is supplied with the electrolytic solution 25a.

When the incident light L1 such as sunlight is incident from the prism portion 30, the incident light L1 is separated into the short wavelength light L2 and the long wavelength light L3 by the prism portion 30 in the same manner as the hydrogen generation operation in the first embodiment. The light L2 is guided to the photocatalyst electrode 21, the long-wavelength light L3 is guided to the solar cell 3, the first electrolyte solution 25a is decomposed on the photocatalyst electrode 21 to generate hydrogen peroxide, and the second electrolysis is performed on the counter electrode 22. The liquid 25b is decomposed to generate hydrogen.

At this time, the hydrogen generated on the counter electrode 22 of each of the electrolytic cells 102a to 102c is tilted with respect to the horizontal plane GL at the predetermined tilt angle θ2 as shown in FIG. b) moves toward the gas recovery hole 140 through the

gas communication holes

146a and 146b, and is stored in the gas storage section 60 through the gas recovery channel 61. FIG.
On the other hand, the hydrogen peroxide generated on the photocatalyst electrode 21 is mixed with the first electrolytic solution 25a, and the hydrogen peroxide is concentrated. When the hydrogen peroxide is concentrated to a predetermined amount or more, the on-off valve 82 is opened to discharge the hydrogen peroxide from the solution recovery channel 81 to the solution storage section 80 .

According to the electrolysis system 100 of the second embodiment, since the position of the end on the side of the gas recovery hole 140 is higher than the position of the end on the side opposite to the gas recovery hole 140, the first electrolytic cell 102a can flow to the third electrolytic cell 102c side through the hydrogen generated in . Therefore, hydrogen can be automatically recovered without installing piping or the like in the electrolytic baths 102a to 102c.

Next, the electrolysis system 200 of the third embodiment will be described.

As shown in FIG. 7, the electrolysis system 200 of the third embodiment includes a plurality of electrolytic cells 202a to 202c, a plurality of solar cells 3a to 3c, an antireflection film 4, an electrolyte supply system 205, and a gas recovery system. 107, a solution recovery system 9, and a malfunction detection means (not shown).

As shown in FIG. 7, the electrolytic baths 202a to 202c include a bath body 220, a photocatalyst electrode 21, a counter electrode 22, an ion exchange portion 23, and

electrolytic solutions

25a and 25b.
The tank body portion 220 includes a ceiling side wall portion 230, a bottom wall portion 131, and

side wall portions

32a and 32b.
Unlike the prism section 30, the ceiling side wall section 230 guides the transmitted light as it is without separating it.

As shown in FIG. 7, the electrolyte supply system 205 includes an electrolyte supply unit 50 and electrolyte supply channels 51a to 51c. The electrolytic solution 25a can be supplied to each of the electrolytic cells 202a-202c.
The electrolytic solution supply channel 51c of the electrolytic solution supply system 205 is a channel connected from the electrolytic solution supply part 50 to the electrolytic solution introduction port 41 of the electrolytic bath 202c, and unlike the first embodiment, the on-off valve 55c and the transmission A heating section 56c is provided.

Next, the positional relationship of each part of the electrolysis system 200 of this embodiment will be described.

In the electrolysis system 200, the electrolysis vessels 202a to 202c and the solar cells 3a to 3c overlap when viewed from above from the ceiling side walls 230 of the electrolysis vessels 202a to 202c.
The areas of the solar cells 3a to 3c are smaller than the areas of the photocatalyst electrodes 21 of the electrolytic cells 202a to 202c, and are entirely covered with the photocatalyst electrodes 21. FIG. That is, the solar cells 3a to 3c receive light transmitted through the photocatalyst electrode 21. FIG.

According to the electrolysis system 200 of the third embodiment, the solar cells 3a to 3c and the photocatalyst electrode 21 overlap each other, and the solar cells 3a to 3c mainly receive the light transmitted through the photocatalyst electrode 21. That is, since the solar cells 3a to 3c receive the light that has been attenuated by the photocatalyst electrode 21 and transmitted, shadows or the like do not occur locally on the solar cells 3a to 3c, and the plurality of solar cells are connected in series. Even when the solar cell 3 is used, the generation of hot spots can be suppressed, and the overall power generation efficiency can be improved. Also, since the occurrence of hot spots can be suppressed, installation of bypass diodes or the like in the solar cells 3a to 3c can be omitted.

In the above-described embodiment, the case where the prism section 30 is used as the wavelength separating section has been described, but the present invention is not limited to this. The wavelength separator may be a fisheye lens or the like as long as it can separate the long wavelength light L3 and the short wavelength light L2.

In the above-described embodiment, hydrogen peroxide is mainly generated from the electrolytic solution 25a on the photocatalyst electrode 21, but the present invention is not limited to this. Oxygen may be generated from the electrolyte solution 25a on the photocatalyst electrode 21 by adjusting the voltage between the photocatalyst electrode 21 and the counter electrode 22 .
In this case, the generated oxygen gas may be collected and used, or may be naturally discharged into the atmosphere by providing a vent hole.

In the first embodiment described above, in the gas recovery system 7, one gas recovery channel 61 branches to the

gas recovery holes

40a and 40b of the respective electrolytic cells 2, and the

gas recovery holes

40a and 40b of the respective electrolytic cells 2 and Although the gas storage unit 60 is connected by the gas recovery channel 61, the present invention is not limited to this. Each electrolytic cell 2 may be provided with a gas recovery channel 61 , and the gas recovery channel 61 of each electrolytic cell 2 may be connected to form a channel to the gas storage section 60 .

In the above-described embodiment, the counter electrode 22 is provided on the prism portion 30 side with respect to the photocatalyst electrode 21, but the present invention is not limited to this. The photocatalyst electrode 21 may be provided on the side of the prism portion 30 with respect to the counter electrode 22 as shown in FIG. That is, the photocatalyst electrode 21 may be arranged on the light receiving side with respect to the counter electrode 22 . By doing so, the photosensitive photocatalyst electrode is arranged at a position close to the sunlight, and the transmission loss of light due to the ion exchange section 23 and the like can be reduced.

As long as the above-described embodiments are within the technical scope of the present invention, each constituent member can be freely replaced or added between the embodiments.

1, 100, 200

electrolytic system

2, 102, 202

electrolytic cell

2a, 102a, 202a first

electrolytic cell

2b, 102b, 202b second

electrolytic cell

2c, 102c, 202c third

electrolytic cell

3, 3a-3c solar cell 4

reflection Prevention films

8a, 8b Solution communication channel (communication channel)
21 Photocatalyst electrode 22 Counter electrode 23 Ion exchange part 25a First electrolytic solution 25b Second electrolytic solution 26 First electrolytic space (space on the side of the photocatalytic electrode)
27 Second electrolytic space (space on the counter electrode side)
30 prism part (wavelength separation part, light receiving part)
51a to 51c Electrolyte solution supply channel (supply channel)
56a, 56b heat transfer section 60 gas storage section 61 gas recovery channel (connection section)
70a, 70b check valve

Claims

a solar cell;
an electrolytic cell having a photocatalyst electrode, a counter electrode, and an electrolytic solution;
a supply channel for supplying the electrolytic solution to the electrolytic cell;
An electrolysis system, comprising: a heat transfer section provided in the middle of the supply channel for transferring heat of the solar cell to the electrolytic solution passing through the supply channel.
The electrolytic system according to claim 1, wherein the electrolytic cell is arranged on the solar cell.
The electrolysis system according to claim 1 or 2, wherein the solar cell applies a voltage between the photocatalyst electrode and the counter electrode.
The electrolytic cell separates the transmitted light into short-wavelength light having a predetermined wavelength or less and long-wavelength light having a longer wavelength than the short-wavelength light, guides the short-wavelength light to the photocatalyst electrode, and directs the light to the long-wavelength light. The electrolysis system according to any one of claims 1 to 3, comprising a wavelength separator that directs light to the solar cell.
The electrolysis system according to claim 4, comprising an antireflection film on the wavelength separator.
The electrolytic bath has a light receiving portion that receives light,
The electrolysis system according to any one of claims 1 to 5, wherein the counter electrode is positioned closer to the light receiving section than the photocatalyst electrode.
having at least two electrolytic cells;
The electrolysis system according to any one of claims 1 to 6, wherein the solar cell is positioned between the photocatalyst electrodes of the two electrolytic cells when the solar cell is viewed from above.
having a gas reservoir,
The electrolytic cell has an ion exchange part between the photocatalyst electrode and the counter electrode,
The ion exchange unit divides the electrolytic cell into a space on the side of the photocatalyst electrode and a space on the side of the counter electrode,
The electrolysis system according to any one of claims 1 to 7, wherein the gas storage part communicates with the space on the counter electrode side and can store the gas flowing out from the space on the counter electrode side.
Having a connection portion that connects the gas storage portion and the electrolytic cell,
9. The electrolysis system according to claim 8, wherein the connecting portion is connected to the top side of the electrolytic cell relative to the counter electrode.
having at least two electrolytic cells;
The two electrolytic cells have an ion exchange part between the photocatalyst electrode and the counter electrode,
The ion exchange unit divides the electrolytic cell into a space on the side of the photocatalyst electrode and a space on the side of the counter electrode,
The two electrolytic cells are provided with a communication channel in which the space on the side of the photocatalyst electrode communicates,
The two electrolytic cells are a first electrolytic cell and a second electrolytic cell,
Having an electrolytic solution supply unit that supplies the electrolytic solution to the space on the photocatalyst electrode side of the first electrolytic cell,
10. The communication channel according to any one of claims 1 to 9, wherein a check valve that allows only movement of the electrolytic solution from the first electrolytic cell side to the second electrolytic cell side is provided in the middle of the communication channel. electrolytic system.
Having an electrolytic cell having a photocatalyst electrode, a counter electrode and an electrolytic solution on the solar cell,
The solar cell receives light that has passed through the electrolytic cell to generate power, and supplies part or all of the generated power to the electrolytic cell,
The electrolytic system, wherein the electrolytic cell uses power supplied from the solar cell to decompose the electrolytic solution.