WO2018012152A1 - Hydrogen generation system - Google Patents

Abstract

A hydrogen generation system (1) is provided with a support body (11) and a hydrogen generation device (21), the support body (11) being capable of being increased in temperature by solar heat, the hydrogen generation device (21) generating hydrogen gas by electrolysis of water, and the support body (11) and the hydrogen generation device (21) being connected so that heat of the support body (11) is transmitted to the hydrogen generation device (21).

Description

Hydrogen generation system

The present invention relates to a hydrogen generation system.
This application claims priority based on Japanese Patent Application No. 2016-140587 filed in Japan on July 15, 2016, the contents of which are incorporated herein by reference.

Conventionally, as an apparatus for generating hydrogen gas, for example, a hydrogen generation system using electrolysis of water as described in Non-Patent Documents 1 and 2 is known.
Since this type of hydrogen generation system is relatively large, it is placed in an environment where the outside air temperature is relatively low, such as indoors.

However, in this type of hydrogen generation system, the efficiency of generating hydrogen gas is low and there is room for improvement.

The present invention has been made in view of such problems, and an object of the present invention is to provide a hydrogen generation system with improved efficiency for generating hydrogen gas.

In order to solve the above problems, the present invention proposes the following means.
The hydrogen generation system of one embodiment of the present invention is a hydrogen generation system including a support and a hydrogen generation device, and the support can be heated by solar heat, and the hydrogen generation device supplies water. The support and the hydrogen generator are connected so that hydrogen gas is generated by electrolysis and heat of the support is transmitted to the hydrogen generator.
According to this aspect, the temperature of the support rises by being heated by solar heat (solar heat). By connecting the support and the hydrogen generator, the temperature of the water used in the hydrogen generator rises as the heat of the support is transmitted. In general, as the temperature of water increases, the overvoltage decreases and it becomes easier to electrolyze, so that the efficiency of generating hydrogen gas can be increased.

In the hydrogen generation system, the support may be a roof of a building.
According to this aspect, the roof of the building is less likely to be shielded from solar heat by other buildings or the like, and is easily heated. Therefore, the temperature of the water used for the hydrogen generator can be increased efficiently, and the efficiency of generating hydrogen gas can be further increased.

In the hydrogen generation system, the support is a solar power generation device that converts sunlight into electric power, and the hydrogen generation device is attached to a surface opposite to the light receiving surface of the solar power generation device. It may be.
According to this aspect, the hydrogen generator preferably has a high temperature of water to be used, but does not require sunlight. On the other hand, the solar power generation apparatus requires sunlight, but if the temperature is too high, the power conversion efficiency is lowered.
The solar power generation device receives sunlight at its light receiving surface and converts it into electric power. By installing a hydrogen generator on the surface opposite to the light-receiving surface of the solar power generator, the temperature of the water used in the hydrogen generator is increased by the heat of the solar power generator heated by solar heat, making hydrogen gas efficient Will occur. For example, when supplying water at room temperature to the hydrogen generator, the water takes away the heat of the solar power generator heated by solar heat, so the temperature of the solar power generator is lowered to convert the power in the solar power generator. Can be increased.

In the hydrogen generation system, the support may be at least one of a building floor, the building foundation, and a pavement.
In the hydrogen generation system, the support may be a building floor, foundation, or pavement.
In the hydrogen generation system, the support may be a building wall or a pillar.
In the hydrogen generation system, the support may be a movable roof or floor.

In the hydrogen generation system, the hydrogen generator may be in the form of a film.
According to this aspect, when the hydrogen generator is formed of a flexible material, the hydrogen generator can be easily bent. Therefore, the hydrogen generator can be easily installed in various shapes.

According to the hydrogen generation system of the present invention, the efficiency of generating hydrogen gas can be increased.

It is a perspective view of the house where the hydrogen generation system of one embodiment of the present invention is attached. It is a side view of the principal part of the hydrogen generation system. It is the schematic diagram which fractured | ruptured a part in the hydrogen generator of the hydrogen generation system. It is a figure showing the change of the required amount of each energy required for the electrolysis of water by the temperature of water. It is a side view of the principal part of the hydrogen generation system in the embodiment of the modification of the present invention.

Hereinafter, an embodiment of a hydrogen generation system according to the present invention will be described with reference to FIGS. In all the drawings below, the thicknesses and dimensional ratios of the constituent elements are appropriately changed in order to make the drawings easy to see.
As shown in FIGS. 1 and 2, the hydrogen generation system 1 of the present embodiment includes a solar power generation device (support) 11 that can be heated by solar heat, and a hydrogen generation device 21 connected to the solar power generation device 11. And.
The solar power generation device 11 is attached to a roof 13 of a house (building) 12 via a support member 14. The support member 14 is configured, for example, by forming an angle 14a, which is a metal rod-like member, into a predetermined shape with a fastening member (not shown) such as a bolt.

The structure of the house 12 is not particularly limited, and may be one-story (one-story) or two or more stories. The configuration of the roof 13 may be a flat roof that is substantially flat with respect to the horizontal plane, or a gable roof, a dormitory roof, or the like having a slope inclined with respect to the horizontal plane.

The solar power generation device 11 is not particularly limited as long as it is a device that converts sunlight incident on the surface 11a that is a light receiving surface into electric power. The solar power generation device 11 converts, for example, sunlight into electric power using a DC voltage. As the solar power generation device 11, for example, a compound solar cell such as a dye-sensitized solar cell, or a silicon solar cell such as a single crystal or polycrystalline solar cell can be used. The solar power generation device 11 is formed in a plate shape.
The solar power generation device 11 is provided with a tab (not shown) for taking out the generated power to the outside.
The solar power generation device 11 is fixed to the support member 14 by a fastening member or the like (not shown) so that the surface 11a faces upward and faces the sun S. The surface 11a is a light receiving surface on which sunlight L described later is incident.

Although not shown, the tab of the solar power generator 11 is connected to a power conditioner provided in the house 12 through wiring. The power conditioner converts a DC voltage into an AC voltage and adjusts the voltage of the AC voltage. The power conditioner is connected to an outlet provided on the wall of the house 12.

The configuration of the hydrogen generator 21 is not particularly limited. The hydrogen generator 21 may be either an alkaline type or a PEM (Proton Exchange Membrane) type, but in the present embodiment, the hydrogen generator 21 will be described as an alkaline type.
As shown in FIG. 3, the hydrogen generator 21 includes an electrolytic cell 22, a diaphragm 23, a water supply pipe 24, and a gas-liquid separator 25. The electrolytic cell 22 includes two substrates 28 that are spaced apart from each other and a sealing material 29 that seals the periphery of the substrate 28 in a liquid-tight manner.
A diaphragm 23 is provided in the electrolytic cell 22. The electrolytic cell 22 is partitioned into an anode chamber 22a and a cathode chamber 22b by a diaphragm 23. The anode chamber 22a is provided with an anode 31, and the cathode chamber 22b is provided with a cathode 32. The anode 31 and the cathode 32 face each other with the diaphragm 23 interposed therebetween.
An electrolytic solution 34 is provided in the anode chamber 22a and the cathode chamber 22b.

The electrolytic cell 22 is connected to a gas-liquid separator 25 by a water supply pipe 24. The water supply pipe 24 includes a first branch pipe 24a and a second branch pipe 24b. The first branch pipe 24a is connected to the end of the anode chamber 22a, and the second branch pipe 24b is connected to the end of the cathode chamber 22b.
An oxygen exhaust pipe 35 is provided in the upper part of the cathode chamber 22b.
The gas-liquid separator 25 is connected to the water source 38 and the hydrogen storage unit 39.

The base material 28 is not particularly limited as long as it is an insulating material and is not modified by the electrolytic solution 34. For the substrate 28, for example, a resin plate, a resin film, or the like is used.
The diaphragm 23 should just be a film | membrane which has ion permeability and does not permeate | transmit hydrogen gas and oxygen gas. As the diaphragm 23, a conventionally known diaphragm is used, for example, a hydrocarbon-based anion exchange membrane or the like.

A conventionally known cathode is used for the anode 31. For the anode 31, for example, a platinum group such as Pt, Rh, Ir, Ni, Fe, etc., and alloys thereof are used.
A conventionally known anode is used as the cathode 32. For the cathode 32, Ni, Ru, Ir, Ti, Sn, Mo, Ta, Nb, V, Fe, Mn, Pt, Pd, Au, alloys thereof, and oxides thereof are used.
For the electrolytic solution 34, for example, an aqueous solution of an alkali metal hydroxide such as an aqueous NaOH solution or an aqueous KOH solution is used.
When an aqueous solution of an alkali metal hydroxide is used as the electrolytic solution 34, the content of the alkali metal hydroxide in the aqueous solution is preferably 0.1 to 50% by mass, and more preferably 1 to 40% by mass.

It is preferable that the electrolytic cell 22 of the hydrogen generator 21 configured as described above is flexible in a film shape (sheet shape). As shown in FIG. 2, the electrolytic cell 22 is directly connected to the back surface (lower surface, the surface opposite to the front surface 11a of the solar power generation device 11) 11b of the solar power generation device 11 by a fastening member such as a bolt (not shown). Has been.

The gas-liquid separator 25 shown in FIG. 3 only needs to be capable of separating hydrogen in water. For example, the gas-liquid separator 25 includes a container such as a pressurized tank, a separation tower filled with a hydrogen adsorbent, and the like. Is used.
The water source 38 is not particularly limited, and for example, a water supply, an ion exchange water production device, a pure water production device, or the like is used as the water source 38.
The hydrogen storage unit 39 is not particularly limited, and a container capable of storing hydrogen, such as a pressurized tank or a cylinder filled with a hydrogen adsorbent, is used for the hydrogen storage unit 39.

The hydrogen generator 21 configured as described above operates as follows.
A DC voltage is applied between the anode 31 and the cathode 32. Water is allowed to flow from the water source 38 in the order of the gas-liquid separator 25 and the water supply pipe 24 to flow into the electrolytic cell 22. The water is at a room temperature of, for example, about 2 ° C. to 40 ° C. in the water source 38. The room temperature varies depending on the season such as summer or winter.
When a voltage is applied between the anode 31 and the cathode 32, the reaction of the following formula (1) occurs at the anode 31, and the reaction of the following formula (2) occurs at the cathode 32.
Anode: 4H ⁺ + 4e ⁻ → 2H ₂ (1)
Cathode: 4OH ⁻ → 2H ₂ O + O ₂ + 4e ⁻ (2)
As a result, water is electrolyzed, hydrogen gas is generated in the anode chamber 22a, and oxygen gas is generated in the cathode chamber 22b.

The oxygen gas generated in the cathode chamber 22b rises in the cathode chamber 22b and is discharged to the outside from the oxygen discharge pipe 35.
The hydrogen gas generated in the anode chamber 22a rises in the anode chamber 22a and flows into the water supply pipe 24 from the first branch pipe 24a.
The hydrogen gas that has flowed into the water supply pipe 24 aerates the water in the water supply pipe 24. When water is aerated with hydrogen gas, the partial pressure of carbon dioxide dissolved in the water decreases, and carbon dioxide is discharged from the water. Thus, the water supplied to the electrolytic cell 22 is previously aerated with hydrogen gas, and carbon dioxide is removed.
The carbon dioxide discharged from the water and the hydrogen gas aerated from the water flow through the water supply pipe 24 and flow into the gas-liquid separator 25.
The hydrogen gas that has flowed into the gas-liquid separator 25 is separated from the water by the gas-liquid separator 25 and flows into the hydrogen reservoir 39.

As shown in FIG. 2, the hydrogen generator 21 is preferably attached to the solar power generator 11 with the electrolytic cell 22 in contact with the back surface 11 b of the solar power generator 11. Since the electrolytic cell 22 is attached to the solar power generation device 11, the heat of the solar power generation device 11 is transmitted to the electrolytic cell 22, and the water in the electrolytic cell 22 is higher than room temperature, for example, 50 ° C to 95 ° C. Heated to a degree.
In addition, when the water supplied from the water source 38 is heated in the electrolysis tank 22, this water takes the heat of the solar power generation device 11 heated by solar heat.

Next, the operation of the hydrogen generation system 1 configured as described above will be described.
When sunlight L emitted by the sun S enters the surface 11a of the solar power generation device 11, the solar power generation device 11 generates electric power by a DC voltage. The solar power generation device 11 attached to the roof 13 of the house 12 is less likely to be blocked from sunlight L and solar heat by other buildings or the like.
The electric power generated by the solar power generation device 11 is sent to the power conditioner through the tab and the wiring of the solar power generation device 11. In the power conditioner, the electric power sent from the solar power generator 11 is converted into an alternating voltage and the voltage is adjusted. The converted electric power is sent to each outlet, and is used in an electrical product or the like connected to this outlet.

On the other hand, the temperature of the solar power generation device 11 is increased by the heat generated by the sun S (solar heat).
The water used for the hydrogen generator 21 is heated by the heat of the solar power generator 11 and the temperature rises. In general, as the temperature of water rises, the overvoltage decreases and it becomes easier to electrolyze, so that hydrogen gas is likely to be generated.
Since the electrolytic cell 22 is in contact with the solar power generation device 11, the water in the electrolytic cell 22 is efficiently heated by the heat of the solar power generation device 11 through the electrolytic cell 22.
The hydrogen gas generated in the anode chamber 22 a of the electrolytic cell 22 flows through the water supply pipe 24 as described above, is processed by the gas-liquid separator 25, and is stored in the hydrogen storage unit 39. Oxygen gas generated in the cathode chamber 22b of the electrolytic cell 22 is discharged from the oxygen discharge pipe 35 to the outside.

Note that the hydrogen generation system 1 configured as described above is a hydrogen / power generation system because it generates not only hydrogen gas but also electric power.

(Example)
Hereinafter, examples of the present invention will be specifically described and described in detail. However, the present invention is not limited to the following examples.
In the above-described hydrogen generation system, the following was used.
-The negative electrode and the positive electrode were nickel foam (nickel foam) manufactured by Nilaco Corporation.
The electrolyte solution was a 30 wt% KOH aqueous solution.
The temperature of the water in the electrolytic cell was set to a constant temperature, and the current flowing between the cathode and the anode was set to 100 mA / cm ² . After stabilizing in this state for 1 hour, overvoltage was measured.
When the water temperature was set to 25 ° C., 50 ° C., 70 ° C., and 90 ° C. and stabilized, the overvoltages were 2.38 V, 2.29 V, 2.15 V, and 2.08 V, respectively.
From this, it has been confirmed that the overvoltage of water decreases as the temperature rises, and electrolysis easily occurs.

4 disclosed in Lei Bi, Samir Boulfrad et al., “Steam electrolysis by solid oxide electrolysis cells (SOECs) with proton-conducting oxides” Chem. Soc. Rev., 2014, 43, p.8255-8270 The simulation result is shown. The horizontal axis of FIG. 4 represents the temperature of water, and the vertical axis represents the energy required to electrolyze 1 mol (mol) of water.

A line L6 indicated by a dotted line is electric energy necessary for electrolysis of water. A line L7 indicated by an alternate long and short dash line is heat energy necessary for electrolysis of water. A line L8 indicated by a solid line is the sum of the value of the line L6 and the value of the line L7. When the temperature is less than 100 ° C., the water is in a liquid state, and when the temperature exceeds 100 ° C., the water becomes steam.
The higher the water temperature, the much less electrical energy is required. On the other hand, the higher the water temperature, the greater the required thermal energy, offsetting the amount of total energy required.

From the line L8 representing the total energy required for water electrolysis, energy efficiency is obtained as shown in Table 1. The energy efficiency when the water temperature is 50 ° C. is 15.6%, and the energy efficiency when the water temperature is 85 ° C. is 17.0%.
In FIG. 4, the energy efficiency when the water temperature is T.degree. C. is the value of the line L7 (thermal energy) when the water temperature is T.degree. C. and the line L8 when the water temperature is T.degree. It is a value divided by the value of (total energy).
From the above, it was found that the energy efficiency of water increases as the temperature increases.

Note that the energy efficiency shown in Table 1 is obtained when the heat source operates at an efficiency of 100%. Since the efficiency of heaters and water heaters that are actually used as heat sources is lower than 100%, the energy efficiency of the hydrogen generation system of this embodiment is considered to be equal to or higher than the energy efficiency values shown in Table 1. In general, as the efficiency of the heat source approaches 100%, the cost of the heat source increases.

As described above, according to the hydrogen generation system 1 of the present embodiment, the temperature of the solar power generation device 11 rises by being heated by solar heat (solar heat). By connecting the solar power generation device 11 and the hydrogen generation device 21, the temperature of the water used for the hydrogen generation device 21 rises due to the transfer of heat from the solar power generation device 11. In general, as the temperature of water rises, the overvoltage decreases and it becomes easier to electrolyze, so that the efficiency of generating hydrogen gas in the hydrogen generation system 1 can be increased.
The reduction of the water overvoltage enables the hydrogen generation system 1 to operate at a high current density.

Although it is preferable that the temperature of the water to be used is high, the hydrogen generator 21 does not require sunlight. On the other hand, the solar power generation device 11 needs sunlight, but if the temperature is too high, the power conversion efficiency is lowered.
The solar power generation device 11 receives sunlight L at its light receiving surface and converts it into electric power. By attaching the hydrogen generation device 21 to the back surface 11b of the solar power generation device 11, the temperature of the water used for the hydrogen generation device 21 is increased by the heat of the solar power generation device 11 heated by solar heat, and hydrogen gas is efficiently used. Occurs.
For example, when normal temperature water is supplied to the hydrogen generator 21, this water takes heat of the solar power generator 11 heated by solar heat. Therefore, the temperature of the solar power generator 11 is lowered to reduce the temperature of the solar power generator 11. Power conversion efficiency can be increased.

Since the hydrogen generator 21 is installed on the roof 13, the installation space can be used effectively, and the hydrogen generator 21 can be installed without affecting the design of the house 12.
Since the hydrogen generator 21 is in the form of a flexible film, the hydrogen generator 21 can be easily bent, and the hydrogen generator 21 can be easily installed by being deformed into various shapes. Since the hydrogen generator 21 can be easily deformed, the installation space can be effectively utilized and the design of the hydrogen generator 21 can be improved.
The hydrogen generating device 21 can be made light and light. The film-like hydrogen generator 21 is a continuous production method (a so-called Roll to process in which each step is processed while pulling out a roll-shaped substrate on one end side, and the roll-shaped roll is wound on the other end side. In this case, the cost required for manufacturing the hydrogen generator 21 can be reduced.

As mentioned above, although one embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and modifications, combinations, and deletions within a scope that does not depart from the gist of the present invention. Etc. are also included.
For example, in the said embodiment, although the support body was the solar power generation device 11, the support body is not limited to this. For example, as in the hydrogen generation system 2 shown in FIG. The roof 13 of the house 12 is less likely to be shielded from solar heat by other buildings or the like, and easily rises in temperature. Therefore, the temperature of the water used for the hydrogen generator 21 can be increased efficiently, and the efficiency of generating hydrogen gas can be further increased.

When the support is the roof 13 of the house 12, the building is not limited to the house 12, but may be a warehouse, a factory, a car park, or the like. Supports that can be heated by solar heat are building exterior walls (walls), floors (edges), pillars, windows, attics, concrete foundations, concrete and asphalt pavements, automobiles, ships (mobiles). There is no particular limitation as long as it can be heated by solar heat, such as a roof, a deck (floor), etc., and can attach the electrolytic cell 22 of the hydrogen generator 21.
Examples of the support made of concrete include a roof of a building, an outer wall (wall), a pillar, a floor and the like in addition to the above.
The hydrogen generator 21 may not be formed into a film but may be formed thick.

The hydrogen generation system of the present invention can be widely applied to a hydrogen generation system in which a hydrogen generator is attached to a support.

1, 2 Hydrogen generation system 11 Solar power generator (support)
11a Surface (light-receiving surface)
11b Back surface (surface opposite to light receiving surface)
12 Housing (Building)
13 Roof (support)
21 Hydrogen generator

Claims (7)

1. A hydrogen generation system comprising a support and a hydrogen generator,
   The support can be heated by solar heat,
   The hydrogen generator generates hydrogen gas by electrolyzing water,
   A hydrogen generation system in which the support and the hydrogen generator are connected so that heat of the support is transferred to the hydrogen generator.
2. The hydrogen generation system according to claim 1, wherein the support is a roof of a building.
3. The support is a solar power generation device that converts sunlight into electric power,
   The hydrogen generation system according to claim 1, wherein the hydrogen generation device is attached to a surface opposite to a light receiving surface of the solar power generation device.
4. 2. The hydrogen generation system according to claim 1, wherein the support is at least one of a building floor, a foundation of the building, and a pavement.
5. The hydrogen generation system according to claim 1, wherein the support is a wall or a pillar of a building.
6. The hydrogen generation system according to claim 1, wherein the support is a roof or a floor of a moving body.
7. The hydrogen generation system according to any one of claims 1 to 6, wherein the hydrogen generator is in the form of a film.

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