Apparatus for producing hydrogen gas using photocatalyst

Abstract

To enable compensating the reduction of a generation amount of hydrogen brought with the reduction of a degree of purity of water in a water tank 2 with respect to an apparatus 1 for producing hydrogen gas using a photocatalyst.SOLUTION: An apparatus for producing hydrogen gas includes: a water tank part 2 for storing water; a photocatalyst body 3 having a photocatalyst substance generating excitation electrons and positive holes when a photocatalyst body dispersed or arranged in water in the water tank is irradiated with light, causing a decomposition reaction of water for decomposing water molecules into hydrogen and oxygen, and generating hydrogen gas; a light source device 4 emitting light radiated to the photocatalyst body and initiating a water decomposition reaction; means 16a for detecting a degree of purity of water in the water tank; and means 16 for responding to the reduction of a degree of purity of water and compensating the reduction of a generation amount of hydrogen gas. The compensation of the reduction of a generation amount of hydrogen gas may be attained either by an increase in an amount of irradiation light, an increase in an amount of a photocatalyst body or exchange of water.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a hydrogen gas production device, and more particularly to a device that produces hydrogen gas by a water decomposition reaction using a photocatalyst. [Background technology]

[0002] Hydrogen gas, which is expected to be used as a clean next-generation fuel that does not produce carbon dioxide when burned, can be produced by a water decomposition reaction using light energy with a photocatalyst, and various technologies for producing hydrogen gas using a photocatalyst have been proposed. For example, Patent Document 1 proposes a hydrogen gas production device that includes a container for receiving water, a photocatalyst dispersed or disposed in the water within the container, the photocatalyst having a photocatalytic substance that, when irradiated with light, generates excited electrons and holes, causing a water decomposition reaction that decomposes water into hydrogen and oxygen and generates hydrogen gas, a light source that emits light that causes the water decomposition reaction when irradiated onto the photocatalyst, and a housing that supports the light source, the housing being placed in the water within the container, the water being heated by exhaust heat from the light source emitted from the surface of the housing, and the surface of the housing that comes into contact with the water being coated with the photocatalytic substance. Patent Document 2 discloses a method for operating a photocatalytic module that has a co-catalyst-supported water-splitting catalyst that splits water using light, and generates hydrogen and / or oxygen by supplying water to the water-splitting catalyst. When the activity of the photocatalyst decreases, a liquid of a metal-containing compound, which is a precursor of the co-catalyst, is placed in the module, and a photocatalytic co-catalyst is precipitated on the photocatalyst by light irradiation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2023-094488 [Patent Document 2] Patent Publication No. 2023-106958 Summary of the Invention [Problem to be solved by the invention]

[0004] An apparatus for producing hydrogen gas by storing water containing a dispersed or disposed photocatalyst in a water tank and irradiating the water with light from a light source such as an LED to induce a water splitting reaction is advantageous in that it can be installed anywhere. Furthermore, in a hydrogen gas production apparatus with such a configuration, the amount of hydrogen gas generated per unit time or per predetermined time (hereinafter simply referred to as the "hydrogen generation amount") varies depending on the intensity of the light irradiated onto the water. Therefore, the amount of hydrogen generated in the apparatus can be adjusted by adjusting the intensity of the irradiated light. Furthermore, since the amount of water in the water tank decreases as hydrogen gas is generated by the water splitting reaction, it is convenient for the hydrogen gas production apparatus to be equipped with a mechanism for continuously supplying water to the water tank (e.g., a water storage tank, piping and a pump for delivering water from the tank to the water tank) to enable continuous hydrogen gas production. Furthermore, if the hydrogen gas production apparatus is equipped with a mechanism for delivering water from the water tank and returning it to the water storage tank, allowing water to circulate between the water tank and the water storage tank, the condition of the water in the water tank can be managed. (See Figure 1).

[0005] In the hydrogen gas production device described above, high-purity water is used for the water splitting reaction to prevent deterioration of the photocatalyst and other parts, but if the purity of the water in the water tank decreases, the amount of hydrogen generated decreases. Therefore, it would be advantageous to be able to compensate for the decrease in the amount of hydrogen generated when the water purity decreases.

[0006] Thus, a main object of the present invention is to provide a configuration in a hydrogen gas production device using a photocatalyst that can compensate for the decrease in the amount of hydrogen generated that accompanies a decrease in the purity of the water in the water tank. [Means for solving the problem]

[0007] According to one aspect of the present invention, the above problem is solved by a hydrogen gas production apparatus, a water tank portion for storing water; a photocatalyst dispersed or placed in the water in the water tank section, the photocatalyst having a photocatalytic substance that generates excited electrons and holes when irradiated with light, and causes a water decomposition reaction that decomposes water molecules into hydrogen and oxygen, thereby generating hydrogen gas; a light source device that emits light that is irradiated onto the photocatalyst to induce the water decomposition reaction; a water purity detection means for detecting the purity of the water in the water tank; a hydrogen generation amount compensation means for compensating for the decrease in the amount of hydrogen gas generated in response to a decrease in the purity of the water detected by the water purity detection means; This is achieved by an apparatus comprising:

[0008] In the above configuration, the "photocatalytic substance" may be a substance that, when irradiated with light, initiates a water decomposition reaction, reducing water to generate hydrogen gas. The "photocatalyst" may be particles of such a photocatalytic substance dispersed in water, or a component formed of the photocatalytic substance itself, or a substrate or matrix to which the photocatalytic substance is immobilized and disposed at any position in the water, or both (hereinafter, the term "photocatalyst" refers to the photocatalytic substance). The "light source device" may typically be any type of device that receives a supply of electric power and emits light that is absorbed by the photocatalytic substance to initiate a water decomposition reaction. The light emission wavelength of the light source device is preferably selected so that the quantum yield of the photocatalyst exceeds a predetermined threshold (which may be selected arbitrarily) so that the light irradiated onto the photocatalyst is efficiently absorbed by the photocatalyst to generate excited electrons and holes. In this regard, the quantum yield of a typical photocatalyst increases rapidly when the wavelength of the irradiated light falls below a certain wavelength. Therefore, the light source may be selected so that its emission wavelength is shorter than the wavelength at which the quantum yield of the photocatalyst increases sharply. Examples of photocatalysts that can be used in the present invention include SrTiO3 (strontium titanate), La2Ti2O7 (lanthanum titanate), Ga2O3 (gallium oxide), GaN (gallium nitride), NaTaO3 (sodium tantalate), and TiO2 (titanium oxide). These photocatalysts may be used with the addition of a co-catalyst, as appropriate. Various light-emitting diodes (LEDs) may be used as the light-emitting element of the light source device. Specifically, LEDs using indium gallium nitride (InGaN), diamond (ultraviolet), gallium nitride (GaN) / aluminum gallium nitride (AlGaN) (ultraviolet, blue), zinc selenide (blue), and zinc oxide (near-ultraviolet, purple, blue) may be used. The "water purity detection means" may be a means for detecting the purity of water using any method. Specifically, the water purity detection means may be a means for detecting the electrical conductivity of water, and may be configured to detect a decrease in water purity when the electrical conductivity of water exceeds a predetermined threshold. The "predetermined threshold" is the electrical conductivity corresponding to the purity at which a significant decrease in the amount of hydrogen generated occurs, and may be set appropriately by the user.The "hydrogen generation amount compensation means" may be a means for performing an operation in any manner that increases the amount of hydrogen generated.

[0009] In the device of the present invention, if the purity of the water in the water tank decreases due to the incorporation of impurities, dissolution or deterioration of device components, or other reasons, and the amount of hydrogen generated decreases, the device responds by increasing the amount of hydrogen generated, thereby compensating for the decrease in the amount of hydrogen generated due to the decrease in water purity.

[0010] Specifically, in one embodiment of the device of the present invention, the hydrogen generation amount compensation means may be a means for controlling the amount of light emitted from the light source device, and may be configured to increase the amount of light emitted from the light source device in response to a decrease in the purity of the water. The increase in the amount of light emitted from the light source device is achieved by increasing the power or current supplied to the light source device. As the amount of light emitted from the light source device increases, the amount of light irradiated onto the photocatalyst increases, which causes more water decomposition reactions to occur and increases the amount of hydrogen generated, i.e., compensates for the decrease in the amount of hydrogen generated.

[0011] In another embodiment of the device of the present invention, the hydrogen generation amount compensation means may be a means for controlling the amount of photocatalyst dispersed or placed in the water in the water tank, and may be configured to increase the amount of photocatalyst in response to a decrease in water purity. Here, the increase in the amount of photocatalyst may be performed in any manner. When the photocatalyst is in the form of particles dispersed in the water, the amount of photocatalyst particles dispersed in the water in the water tank may be increased. In an embodiment, the photocatalyst particles may be dispersed in water outside the water tank, and the water may be pumped into the water tank. For example, if a mechanism for replenishing water from a water storage tank is provided, a larger amount of photocatalyst particles than usual may be dispersed in the replenishing water, and the water may be supplied to the water tank via a pump or the like. The increase in the amount of photocatalyst in the water in the water tank causes more water decomposition reactions to occur, increasing the amount of hydrogen generated, i.e., compensating for the decrease in hydrogen generation.

[0012] Furthermore, in yet another embodiment of the apparatus of the present invention, when the hydrogen gas production apparatus is provided with a drainage means for draining water from the water tank and a pure water addition means for adding pure water to the water tank, the hydrogen generation amount compensation means may be configured to cause the drainage means to drain the water from the water tank in response to a decrease in water purity, and then cause the pure water addition means to add pure water to the water tank. In such a configuration, if photocatalytic particles are dispersed in the water in the water tank, only the water may be drained without discharging the photocatalytic particles, and high-purity water may be supplied to the water tank using a mechanism for replenishing water from a water storage tank into the water tank. With this configuration, replacing the water in the water tank increases the purity of the water, thereby increasing the amount of hydrogen generation that had decreased due to the decrease in purity.

[0013] Furthermore, when a mechanism for replenishing water from the water storage tank to the water tank is provided as described above, the amount of photocatalyst per unit amount of water in the water tank can be reduced by using only water or water with a smaller amount of dispersed photocatalyst particles than usual as the replenishing water, which also makes it possible to control the amount of hydrogen generated to be reduced. [Effects of the Invention]

[0014] Thus, in the hydrogen gas production device of the present invention, when a decrease in the amount of hydrogen generated occurs due to a decrease in the purity of the water in the water tank, measures are taken to increase the amount of hydrogen generated to compensate for the decrease, and it is expected that this will make it possible to produce hydrogen gas that is not dependent on the purity of the water.

[0015] Other objects and advantages of the present invention will become apparent from the following description of preferred embodiments of the invention. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram illustrating the configuration of one aspect of a hydrogen gas production device to which this embodiment is applied. [Figure 2]Figure 2(A) is a flowchart showing the process of increasing the amount of light emitted from the light source device to compensate for the amount of hydrogen generated when the purity of water decreases in the hydrogen gas production apparatus of this embodiment. Figure 2(B) is a flowchart showing the process of increasing the amount of photocatalyst dispersed in water to compensate for the amount of hydrogen generated when the purity of water decreases in the hydrogen gas production apparatus of this embodiment. Figure 2(C) is a flowchart showing the process of replacing water to compensate for the amount of hydrogen generated when the purity of water decreases in the hydrogen gas production apparatus of this embodiment. Figure 2(D) is a flowchart showing the process of replenishing only water and reducing the amount of photocatalyst relative to the amount of water to reduce the amount of hydrogen generated in the hydrogen gas production apparatus of this embodiment. [Explanation of symbols]

[0017] 1...hydrogen gas production device, 2...water tank section, 3...water, 3a...optical medium, 4...light source device, 5...light emitting element (LED), 6...power source, 7...current controller, 8...current control indicator, 9...produced gas collection pipe, 10...water storage tank, 11...water supply pipe, 12...pump, 13...water circulation pipe, 14...water tank water level gauge, 15...water circulation controller, 16...hydrogen generation amount compensation controller (computer device), 16a...electrical conductivity sensor, 17...tank water level gauge, 18...photocatalyst supply pipe, 18a...photocatalyst supply controller, 19...pure water supply pipe, 19a...pure water supply controller, 20...tank drain pipe, 20a...filter, 21...tank drain controller BEST MODE FOR CARRYING OUT THE INVENTION

[0018] Hydrogen gas production equipment configuration 1, in a hydrogen gas production device 1 to which this embodiment is applied, water 3 containing a photocatalyst is stored in a water tank section 2, which may be of any shape, and excitation light that induces a water decomposition reaction in the photocatalyst 3a in the water 3 is emitted from a light emitting element 5 supported by a light source device 4, whereby water molecules are decomposed into hydrogen and oxygen in the photocatalyst 3a, producing hydrogen gas H2 and oxygen gas O2. The produced hydrogen gas H2 and oxygen gas O2 are sent to a hydrogen separator (not shown) through a collection pipe 9, where the oxygen gas O2 and hydrogen gas H2 are separated and may be stored in a storage tank or the like (not shown). In the configuration of the hydrogen gas production device 1, the photocatalyst 3a contained in the water 3 may be formed from any photocatalytic material that can be used to produce hydrogen gas through a water-splitting reaction using light, as listed in the Summary of the Invention section, and may be particles dispersed in the water, or a member formed from the photocatalytic material itself, or a substrate or matrix on which the photocatalytic material is fixed and placed at any position in the water, or both. The light-emitting element 5 used in the light source device 4 is typically a light-emitting diode as listed in the Summary of the Invention section, and may be any element that emits light that triggers a water-splitting reaction in the photocatalyst 3a used.

[0019] Furthermore, in the case of the hydrogen gas production apparatus 1 to which this embodiment is applied, as shown in the figure, a water storage tank 10 for storing water is provided separately from the water tank section 2, and the water w stored in the water storage tank 10 is supplied into the water tank section 2 by a pump 12 through a water supply pipe 11, and the water 3 in the water tank section 2 can be delivered to the water storage tank 10 through a water circulation pipe 13. More specifically, in one embodiment, the amount of water in the water tank section 2 decreases as the water decomposition reaction progresses, so the water level in the water tank section 2 is monitored by a water level gauge 14 of any type, and the amount of water supplied from the water storage tank 10 to the water tank section 2 can be adjusted by controlling the operation of the pump 12 in the water supply pipe 11 in response to the detection value of the water level gauge 14 to maintain the water level appropriately. Alternatively, the amount of water circulated from the water storage tank 10 to the water tank section 2 can be adjusted by operating a water circulation controller 15 that controls the amount of water delivered through the water circulation pipe 13. The photocatalyst (photocatalyst particles) may also be dispersed in the water w stored in the water storage tank 10, and may be circulated between the water tank part 2 and the water storage tank 10 together with the water as appropriate.

[0020] Furthermore, the hydrogen gas production device 1 of this embodiment may be configured to increase or decrease the amount of hydrogen generated by several methods. Specifically, first, the current controller 7 controls the magnitude of the current supplied from the power source 6 to the light emitting element 5 of the light source device 4, thereby adjusting the amount of light irradiated onto the photocatalyst 3a in the water in the water tank section 2, making it possible to adjust the amount of hydrogen generated (the greater the amount of light, the greater the amount of hydrogen generated). Control instructions to the current controller 7 may be given from a current control indicator 8 as appropriate.

[0021] Furthermore, in the device 1 of this embodiment described above, a configuration may be provided for additionally supplying photocatalyst PC to the water stored in the water storage tank 10, so that the amount of hydrogen generated can be increased by increasing the amount of photocatalyst in the water tank portion 2. More specifically, the water storage tank 10 may be provided with a delivery pipe 18 that delivers the photocatalyst PC to the water storage tank 10, and a photocatalyst supply controller 18a that adjusts the amount of photocatalyst PC circulating therethrough, and the photocatalyst supply controller 18a may be configured to timely execute an operation to introduce the photocatalyst PC into the water storage tank 10 through the delivery pipe 18. The supply of the photocatalyst PC may be achieved by delivering photocatalyst particles dispersed in water to the delivery pipe 18.

[0022] Furthermore, the device 1 of this embodiment may be provided with a configuration for replenishing pure water to the water storage tank 10 and a configuration for draining only water from the water storage tank 10, thereby enabling the amount of photocatalytic material per unit volume of water in the water tank portion 2 or the concentration of the photocatalyst to be adjusted, or the purity of the water, to increase or decrease the amount of hydrogen generation. More specifically, as shown in the figure, the configuration for replenishing pure water to the water storage tank 10 may involve replenishing pure water to the water storage tank 10 through a pure water replenishing pipe 19. The replenishing amount may be controlled by a pure water replenishing controller 19a. Meanwhile, the configuration for draining only water from the water storage tank 10 may involve providing a filter 20a at the end of the tank side of the tank drain pipe 20 that allows only water to pass through but does not allow the photocatalyst to pass through, allowing the water in the tank 10 to be drained as needed through the tank drain pipe 20. The amount of water drained through the tank drain pipe 20 may be controlled by a tank drainage controller 21. With these configurations, when pure water is supplied from the pure water supply pipe 19 without draining the water in the tank 10, the amount of photocatalytic substance per volume of water in the water tank 2 and the water storage tank 10 or the photocatalyst concentration decreases, resulting in a reduced amount of hydrogen generation. Furthermore, when pure water is not supplied and only drained from the tank 10, the amount of photocatalytic substance per volume of water in the water tank 2 and the water storage tank 10 or the photocatalyst concentration increases, resulting in an increased amount of hydrogen generation. Furthermore, when pure water is replenished after draining the water from the tank 10, the water in the water tank 2 and the water storage tank 10 is exchanged. As a result, when the amount of hydrogen generation has decreased due to a decrease in the purity of the water, exchanging the water increases the purity of the water and restores the amount of hydrogen generation.

[0023] Furthermore, the device 1 of the present embodiment is provided with a configuration for detecting water purity. When the detected water purity decreases and the hydrogen generation rate decreases, one of the configurations for adjusting the hydrogen generation rate is used to increase the hydrogen generation rate to compensate for the decrease in the hydrogen generation rate. Any method may be used for detecting the water purity. Typically, the electrical conductivity sensor 16a detects the water's electrical conductivity. When the electrical conductivity exceeds a predetermined threshold, which may be set as appropriate, the hydrogen generation rate compensation controller 16, which may be a computer device, determines that the water purity has decreased. When the hydrogen generation rate compensation controller 16 determines that the water purity has decreased, it operates to instruct the current control indicator 8, photocatalyst supply controller 18a, pure water replenishment controller 19a, and tank drainage controller 21 to increase the amount of light irradiated from the light source device 4, add a photocatalyst, or replace the water, as described below.

[0024] Operation of the device As described above, in the apparatus 1 of this embodiment, when a decrease in water purity is detected from the electrical conductivity of the water or the like, some measure is taken to compensate for the decrease in the amount of hydrogen generated due to the decrease in water purity, thereby achieving the production of hydrogen gas that is not dependent on the purity of the water. Below, the measures to compensate for the decrease in the amount of hydrogen generated will be explained in order.

[0025] (1) Increase in the amount of light irradiated When compensating for a decrease in the amount of hydrogen generated by increasing the amount of irradiated light, as shown in FIG. 2(A), after hydrogen gas production starts (step 0), the electrical conductivity σ is detected (step 1), and it is determined whether the electrical conductivity σ exceeds a predetermined threshold σo (step 2). The predetermined threshold σo is a value above which the decrease in the amount of hydrogen generated due to a decrease in water purity becomes significant, and may be determined through experiments, etc. Here, if the electrical conductivity σ is below the predetermined threshold σo, it is determined that the purity of the water has not decreased, and hydrogen gas production continues as is until the amount of hydrogen gas produced P reaches the planned amount Po (step 5). The amount of hydrogen gas produced P can be measured by any method. On the other hand, if the electrical conductivity σ>σo holds, it is determined that the purity of the water has decreased. To compensate for the resulting decrease in the amount of hydrogen generated, the hydrogen generation amount compensation controller 16 controls the current control indicator 8 to appropriately set the current ΔI to be input to the light source device 4. LED Then, an instruction is given to increase the current input to the light source device 4 (step 3). This increases the amount of light irradiated onto the photocatalyst in the water in the water tank, thereby increasing the amount of hydrogen generated. Note that once the electrical conductivity σ>σo is established and the current input to the light source device 4 is increased, if the electrical conductivity σ further decreases, the current input to the light source device 4 may be further increased. For this reason, when the current is increased, the predetermined threshold σo in step 2 may also be further increased by an amount (Δσ) that may be set appropriately (step 4). As a result, if the purity of the water further decreases and the electrical conductivity σ further decreases, the current input to the light source device 4 is further increased, thereby compensating for the decrease in the amount of hydrogen generated.

[0026] (2) Additional supply of photocatalyst 2(B), when compensating for the decrease in the amount of hydrogen generated by additionally supplying photocatalyst, as in the case of FIG. 2(A), after hydrogen gas production starts (step 10), the electrical conductivity σ is detected (step 11), and it is determined whether the electrical conductivity σ exceeds a predetermined threshold σ (step 12). If the electrical conductivity σ is below the predetermined threshold σ, it is determined that the purity of the water has not decreased, and hydrogen gas production continues under the same conditions until the amount of hydrogen gas produced P reaches the planned amount Po (step 15). If the electrical conductivity σ exceeds the predetermined threshold σ, the hydrogen generation amount compensation controller 16 determines that the purity of the water has decreased. To compensate for the resulting decrease in the amount of hydrogen generated, the hydrogen generation amount compensation controller 16 instructs the photocatalyst supply controller 18a to add photocatalyst (particles) to the water in the tank 10 to be supplied to the water tank 2, thereby increasing the amount of hydrogen generated. Furthermore, even in this embodiment, if the electrical conductivity σ > σo is established once and a photocatalyst is added, and then the electrical conductivity σ further decreases, a further photocatalyst may be added and a process to again compensate for the decrease in the amount of hydrogen generated may be executed. For this reason, when additional photocatalyst is supplied, the predetermined threshold σo in step 12 may also be increased by an amount (Δσ) that may be set appropriately (step 14). As a result, when the purity of the water further decreases and the electrical conductivity σ further decreases, the amount of photocatalyst in the water is further increased, thereby compensating for the decrease in the amount of hydrogen generated.

[0027] (3) Water change In yet another aspect of this embodiment, when the purity of the water in the water tank 2 and the tank 10 decreases, the purity of the water is restored by replacing the water, thereby compensating for the decrease in the amount of hydrogen generated. Specifically, as shown in FIG. 2(C), after hydrogen gas production starts (step 20), the electrical conductivity σ is detected (step 21), and it is determined whether the electrical conductivity σ exceeds a predetermined threshold σo (step 22). If the electrical conductivity σ is below the predetermined threshold σo, it is determined that the purity of the water has not decreased, and hydrogen gas production continues in this state until the hydrogen gas production amount P reaches the planned amount Po (step 25). On the other hand, if the electrical conductivity σ exceeds the predetermined threshold σo and it is determined that the purity of the water has decreased, the hydrogen generation rate compensation controller 16 first instructs the tank drain controller 21 to drain the water from the tank 10 by an amount Δw that may be set appropriately through the tank drain pipe 20 (step 23). After this drainage, the pure water replenishment controller 19a is instructed to replenish the water from the tank 10 by an amount ΔH2O that may be set appropriately through the pure water replenishment pipe 19 (step 24). This operation drains the water with reduced purity from the tank 10, and then replenishes it with pure water. This replaces the water with reduced purity in the tank 10 and the water tank portion 2 with pure water of high purity, which is expected to restore the hydrogen generation rate to the level before the decrease in water purity. This water exchange may be performed every time the electrical conductivity σ exceeds the predetermined threshold σo.

[0028] (4) Reduction of hydrogen generation The apparatus of this embodiment may further perform a process to reduce the amount of hydrogen generated if it is excessive. Specifically, as shown in FIG. 2(D), after hydrogen gas production begins (step 30), it is determined whether the amount of hydrogen gas generated per unit time, Vp, is higher than a predetermined value, Vo, which may be set as appropriate (step 31). If Vp > Vo, a suitable amount of pure water, ΔH2O, is supplied through the pure water supply pipe 19 (step 32). The amount of hydrogen gas generated per unit time, Vp, can be detected by any method, such as a hydrogen gas sensor. This reduces the amount of photocatalyst relative to the amount of water in the water tank portion 2, thereby reducing the amount of hydrogen generated. The water level in the tank 10 may be detected by the tank water level gauge 17. When the water level, Hw, in the tank exceeds a suitable predetermined value, Ho, an appropriate amount, Δw, of water in the tank 10 may be drained through the tank drain pipe 20 (step 34). Even when the above process is performed, the production of hydrogen gas may be continued until the production amount P of hydrogen gas reaches the planned amount Po.

[0029] Thus, according to the hydrogen gas production device of the present embodiment, whether or not the purity of the water in the water tank has decreased is detected, and when the purity of the water has decreased, one of the above-mentioned measures is taken to compensate for the resulting decrease in the amount of hydrogen generated, and the amount of hydrogen generated is increased, thereby enabling the production of hydrogen gas that is not dependent on the purity of the water.

[0030] The above description has been made in relation to the embodiments of the present invention, but it will be apparent that many modifications and changes will be readily apparent to those skilled in the art, and the present invention is not limited to the above-described exemplary embodiments, but can be applied to various devices without departing from the concept of the present invention.

Claims

1. A hydrogen gas production apparatus, a water tank portion for storing water; a photocatalyst dispersed or placed in the water in the water tank section, the photocatalyst having a photocatalytic substance that generates excited electrons and holes when irradiated with light, and causes a water decomposition reaction that decomposes water molecules into hydrogen and oxygen, thereby generating hydrogen gas; a light source device that emits light that is irradiated onto the photocatalyst to induce the water decomposition reaction; a water purity detection means for detecting the purity of the water in the water tank; a hydrogen generation amount compensation means for compensating for the decrease in the amount of hydrogen gas generated in response to a decrease in the purity of the water detected by the water purity detection means; An apparatus comprising:

2. 2. The apparatus of claim 1, wherein the hydrogen generation amount compensation means is a means for controlling the amount of light emitted from the light source device and is configured to increase the amount of light emitted from the light source device in response to a decrease in the purity of the water.

3. 2. The device of claim 1, wherein the hydrogen generation amount compensation means is a means for controlling the amount of the photocatalyst dispersed or placed in the water in the water tank, and is configured to increase the amount of the photocatalyst in response to a decrease in the purity of the water.

4. 2. The apparatus of claim 1, further comprising a drainage means for draining water from the water tank and a pure water adding means for adding pure water to the water tank, wherein the hydrogen generation amount compensating means is configured to cause the drainage means to drain the water from the water tank in response to a decrease in the purity of the water, and then cause the pure water adding means to add pure water to the water tank.

5. 2. The apparatus of claim 1, wherein the water purity detection means is a means for detecting the electrical conductivity of the water, and is configured to detect that the purity of the water has decreased when the electrical conductivity exceeds a predetermined threshold.

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