JP2007239038A - Hydrogen supply method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrogen supply method free from loss of hydrogen in transportation or storage basically, suitable for long distant transportation or long term storage of hydrogen and for making the material balance of carbon dioxide substantially a closed system. <P>SOLUTION: The hydrogen supply method includes: a water electrolyzing step 1 for electrolyzing water to produce hydrogen and oxygen separately; a water soluble organic compound synthesizing step 2 for synthesizing a water soluble organic compound from a recovered carbon dioxide and hydrogen obtained in the water electrolyzing step 1; a water soluble organic compound aqueous solution preparing step 3 for preparing the aqueous solution of the synthesized water soluble organic compound; a water soluble organic compound aqueous solution electrolyzing step 4 for electrolyzing the prepared water soluble organic compound aqueous solution to produce hydrogen and carbon dioxide separately; and a carbon dioxide recovering step 5 for recovering the carbon dioxide produced in the water soluble organic compound aqueous solution electrolyzing step and supplying the recovered carbon dioxide to the water soluble organic compound synthesizing step. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hydrogen supply method using an aqueous solution of a water-soluble organic compound as a medium for transporting and storing hydrogen, and in particular, there is no loss of hydrogen during transportation and storage in principle, and at a high energy density. The present invention relates to a hydrogen supply method capable of transporting and storing hydrogen, suitable for long-distance transport and long-term storage of hydrogen, and capable of making the mass balance of carbon dioxide a substantially closed system.

  In recent years, development of fuel cells and cogeneration systems using hydrogen as fuel has been progressing. For example, an electric vehicle (hydrogen fuel cell vehicle) using a fuel cell that uses hydrogen as a fuel is traveling on a public road. Furthermore, in portable devices such as notebook personal computers and mobile phones, it has been studied to use a fuel cell using hydrogen as a power source. In order to popularize hydrogen fuel cell vehicles, establish a hydrogen supply method that supplies hydrogen to hydrogen fuel cell vehicles simply as fuel is supplied to gasoline and diesel vehicles at a gas station. There is a need. Accordingly, studies are being made on how to supply hydrogen to hydrogen fuel cell vehicles or hydrogen consuming equipment represented by hydrogen-based cogeneration systems.

  As one form of the hydrogen supply method, hydrogen is produced off-site, that is, hydrogen is produced at a place other than the hydrogen supply place, and the produced hydrogen is used as a high-pressure hydrogen (gas) or liquid hydrogen consumption site. Non-Patent Documents 1 and 2 disclose a method of supplying hydrogen to a hydrogen consuming device after transporting to a storage facility. This form of hydrogen supply method is intended to use by-product hydrogen generated in chemical plants, etc., so carbon dioxide, which is a global warming exhaust gas generated during hydrogen production, is collected at the hydrogen production site. It has the advantage of being recoverable. However, except for the case where a pipeline is laid from the hydrogen production site to the hydrogen consumption site to transport hydrogen, especially in the case of gas, hydrogen, which is a low energy density fuel, is transferred from the hydrogen production site using a tank lorry. It is necessary to transport to a consumption site, and there is a problem that energy loss accompanying transportation is large. Although liquid hydrogen has a higher energy density than high-pressure hydrogen, it requires extremely low temperatures for transportation and handling, is extremely cumbersome, and increases transportation and storage costs. Furthermore, the loss of hydrogen due to evaporation of liquid hydrogen cannot be ignored. In addition, since the construction of a pipeline for transporting hydrogen costs enormous costs, the hydrogen supply method involves producing hydrogen off-site and transporting it to the hydrogen consumption site in the current situation where hydrogen consumption is not very high. Is not realistic in terms of economy.

  As another form of the conventional hydrogen supply method, fuel such as desulfurized gasoline, liquefied petroleum gas (LP gas), natural gas (city gas), methanol, naphtha, etc. is used on the hydrogen consumption site, that is, on-site. Non-Patent Documents 3 to 7 disclose hydrogen supply methods in which hydrogen is produced by reforming, and the produced hydrogen is stored or pressurized and stored and then supplied to a hydrogen consuming device. Of these fuels, natural gas is mainly composed of methane and is widely used as city gas. For this reason, pipelines for transporting natural gas are also widely used. It can be supplied. Liquefied petroleum gas becomes liquid at a pressure of about 0.8 MPa at room temperature, and other fuels are liquid at room temperature and normal pressure, both of which have a higher energy density than hydrogen. It is possible to keep energy loss small even if transported with These hydrogen supply methods for reforming fuel on-site to produce hydrogen can efficiently produce hydrogen at the hydrogen consumption site, but carbon dioxide produced by reforming the fuel. In addition, it is necessary to separate and pressurize hydrogen from the reformed gas containing water vapor and the like, which has a problem of consuming a lot of energy. In addition, in order to obtain the heat required for fuel reforming by burning the exhaust gas containing carbon dioxide, water vapor, hydrogen, etc. after separating hydrogen from the reformed gas with air, the combustion exhaust gas containing carbon dioxide contains A large amount of nitrogen is contained, and if carbon dioxide is to be separated and recovered from the viewpoint of preventing global warming, a large-scale carbon dioxide separation and recovery device is required, and a large amount of energy is consumed for the separation and recovery of carbon dioxide. There is also a problem.

Furthermore, the recovered carbon dioxide cannot be left as it is, for example, it must be dumped underground or in the deep sea. Thus, in the conventional hydrogen supply method, the recovered carbon dioxide is treated separately. It is necessary, and the processing cost for it is also necessary.
Ryuichi Hirotani, “Off-site hydrogen supply station”, Clean Energy, Vol. 13, No. 8, pages 25-29 (2004), Nihon Kogyo Publishing Akihiko Hashimoto, “Liquid Hydrogen Storage Hydrogen Station”, Clean Energy, Vol. 13, No. 8, pp. 30-34 (2004), Nihon Kogyo Publishing Masayuki Hattori, “Desulfurized Gasoline Reforming Hydrogen Station”, Clean Energy, Vol. 13, No. 8, pp. 20-24 (2004), Nihon Kogyo Publishing Hiroki Yoshida, “Senju Hydrogen Station”, Clean Energy, Vol. 13, No. 9, pp. 22-26 (2004), Nihon Kogyo Publishing Tetsuya Mori et al., “Natural Gas Reforming Hydrogen Station (WE-NET)”, Clean Energy, Vol. 13, No. 9, pp. 27-31 (2004), Nihon Kogyo Publishing Takeshi Manabe, “Methanol reforming hydrogen station”, Clean Energy, Vol. 13, No. 9, pp. 32-36 (2004), Nihon Kogyo Publishing Masaki Ikematsu, “Naphtha reforming hydrogen supply station”, Clean Energy, Vol. 13, No. 9, pp. 37-40 (2004), Nihon Kogyo Publishing

  As described above, in the conventional hydrogen supply method using hydrogen gas or liquid hydrogen, there is a loss of hydrogen during transportation and storage, and the energy density of the transported and stored hydrogen is small, so that the cost for transportation and storage is low. There is a problem that it takes. On the other hand, the method of supplying hydrogen on-site by reforming hydrocarbons has a problem that it is difficult to efficiently recover carbon dioxide. Further, in these conventional hydrogen supply methods, carbon dioxide is by-produced for hydrogen production, but there is a fundamental problem of how to dispose of the by-produced carbon dioxide.

  Accordingly, an object of the present invention is to prevent hydrogen loss during transportation and storage in principle, and to transport and store hydrogen at a high energy density. And a hydrogen supply method capable of making the mass balance of carbon dioxide a substantially closed system.

  The hydrogen supply method of the present invention was obtained from a predetermined energy source in a hydrogen supply method using a water-soluble organic compound aqueous solution as a medium for transporting and storing hydrogen and having a carbon dioxide mass balance substantially closed. Water electrolysis process in which water is electrolyzed by electricity to separate and produce hydrogen and oxygen, and water-soluble organic compound synthesis process to synthesize water-soluble organic compound from recovered carbon dioxide and hydrogen obtained in water electrolysis process And a water-soluble organic compound aqueous solution preparation step for preparing a water-soluble organic compound aqueous solution having a predetermined concentration by mixing water and a water-soluble organic compound synthesized in the water-soluble organic compound synthesis step, and a predetermined energy source. The water-soluble organic compound aqueous solution prepared in the water-soluble organic compound aqueous solution preparation step is electrolyzed by the generated electric power to separate and produce hydrogen and carbon dioxide. A compound aqueous solution electrolysis step, and a carbon dioxide recovery step of recovering carbon dioxide generated in the water-soluble organic compound aqueous solution electrolysis step and supplying the recovered carbon dioxide to the water-soluble organic compound synthesis step as recovered carbon dioxide. It is characterized by that.

  In the present invention, the water-soluble organic compound synthesis step and the water-soluble organic compound aqueous solution preparation step are not provided, but instead, the water-soluble organic compound aqueous solution is synthesized from the recovered carbon dioxide and the hydrogen obtained in the water electrolysis step. A water-soluble organic compound aqueous solution synthesis step may be provided, and in the water-soluble organic compound aqueous solution electrolysis step, the water-soluble organic compound aqueous solution synthesized in the water-soluble organic compound aqueous solution synthesis step may be electrolyzed.

  In the present invention, the water-soluble organic compound is, for example, at least one compound selected from the group consisting of methanol, ethanol, and 2-propanol.

  In this invention, you may further provide the process of supplying the hydrogen produced | generated by the water-soluble organic compound aqueous solution electrolysis process to the hydrogen supply destination. The supply destination of hydrogen is typically a device that consumes hydrogen, such as a hydrogen fuel cell vehicle, various portable devices having a fuel cell using hydrogen as a fuel, and a cogeneration system using hydrogen as a fuel. is there.

  By using an aqueous solution of a water-soluble organic compound as a medium for storing and transporting hydrogen, in principle there is no loss of hydrogen during transport and storage, and transport and storage of hydrogen at a high energy density is prevented. In particular, it enables long-distance transportation and long-term storage of hydrogen. Further, the mass balance of carbon dioxide can be made a substantially closed system, global warming due to the release of carbon dioxide can be prevented, and the labor and cost for disposal of carbon dioxide can be reduced.

  Next, a preferred embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a process diagram showing a hydrogen supply method according to a first embodiment of the present invention.

  In the hydrogen supply method of the present embodiment, first, electric power generated using renewable natural energy such as sunlight, wind power, wave power, ocean temperature difference, hydropower, geothermal heat, etc. obtained at a specific site, or nuclear power is used. In the water electrolysis step 1, water is electrolyzed using the generated electric power to generate hydrogen and oxygen. These electric powers are effective in preventing global warming because they do not generate carbon dioxide during the power generation process.

  Next, in the water-soluble organic compound synthesizing step 2, hydrogen generated in the water electrolysis step 1 is reacted with recovered carbon dioxide described later to synthesize a water-soluble organic compound, and if necessary, the water-soluble organic compound Isolate. In the hydrogen supply method of this embodiment, the aqueous solution of the water-soluble organic compound is used as a medium for storing and transporting hydrogen when supplying hydrogen to a hydrogen supply destination.

When methanol (CH ₃ OH) is used as the water-soluble organic compound, in the water-soluble organic compound synthesis step 2, methanol and water are generated from hydrogen and recovered carbon dioxide by the exothermic reaction shown in the formula (1).

3H ₂ + CO ₂ → CH ₃ OH + H ₂ O (1)
The generated methanol may be separated into water and supplied to the next aqueous water-soluble organic compound aqueous solution preparation step 3 in the form of high-concentration methanol, or the next aqueous water-soluble organic compound aqueous solution preparation step in the form of an aqueous methanol solution as it is. 3 may be supplied.

  In the third water-soluble organic compound aqueous solution preparation step 3, which is the third step, the water-soluble organic compound synthesized in the next water-soluble organic compound synthesis step 2 or the water-soluble organic compound synthesis step 2 like methanol in the next water-soluble organic compound synthesis step 2. What was synthesize | combined in the form of aqueous solution adjusts the density | concentration of the water-soluble organic compound in water-soluble organic compound aqueous solution to a predetermined density | concentration by mixing water-soluble organic compound aqueous solution with water. The water-soluble organic compound aqueous solution prepared at the water-soluble organic compound aqueous solution preparation step 3 is transported to the hydrogen consumption site and stored.

  In the fourth water-soluble organic compound aqueous solution electrolysis step 4, the water-soluble organic compound aqueous solution transported and stored at the hydrogen consumption site described above is electrolyzed using midnight power to separate hydrogen and carbon dioxide. To generate. When methanol is used as the water-soluble organic compound, hydrogen and carbon dioxide are separated and formed by the electrochemical reaction shown in the formulas (2) and (3) in the water-soluble organic compound aqueous solution electrolysis step 4. .

CH ₃ OH + H ₂ O → CO ₂ + 6H ⁺ + 6e ⁻ (2)
_{^{6H + + 6e - → 3H 2}} (3)
Equation (2) is a reaction at the anode, and equation (3) is a reaction at the cathode. The electrolysis reaction of an aqueous methanol solution is a combination of formulas (2) and (3), and as shown in formula (4), methanol and water react to produce carbon dioxide and hydrogen. It becomes.

CH ₃ OH + H ₂ O → CO ₂ + 3H ₂ (4)
As shown in FIG. 2, the electrolysis voltage of the methanol aqueous solution is 30 to 42% of the electrolysis voltage of water. Since the electrolysis power is determined by the electrolysis voltage, considering the electrolysis power necessary for obtaining the same number of moles of hydrogen, the electrolysis power in the case of electrolysis of aqueous methanol solution is 30 to 42%. Therefore, the hydrogen supply method of this embodiment does not cause an increase in energy cost accompanying an increase in energy consumption. FIG. 2 shows the relationship between the electrolysis voltage and the electrolysis current when electrolysis of an aqueous methanol solution and electrolysis of water are performed. The concentration of the methanol aqueous solution was 17 mol / l (molar ratio of methanol to water was 1: 1). As shown in FIG. 3, it was confirmed that in the electrolysis of the aqueous methanol solution, hydrogen was produced at a theoretical production rate commensurate with the electrolysis current.

  Hydrogen generated in the water-soluble organic compound aqueous solution electrolysis step 4 is supplied to a hydrogen consuming device and consumed. On the other hand, the carbon dioxide generated in the water-soluble organic compound aqueous solution electrolysis step 4 is supplied to the carbon dioxide recovery step 5.

  In the carbon dioxide recovery step 5 as the fifth step, the carbon dioxide generated in the water-soluble organic compound aqueous solution electrolysis step 4 is recovered and supplied to the water-soluble organic compound synthesis step 2 as recovered carbon dioxide. As described above, the recovered carbon dioxide is used in the water-soluble organic compound synthesis step 2 to react with the hydrogen generated in the water electrolysis step 1 to synthesize the water-soluble organic compound.

  According to this embodiment, hydrogen can be transported from a hydrogen production site to a hydrogen consumption site in the form of a water-soluble organic compound aqueous solution such as a methanol aqueous solution, and hydrogen can be transported to a hydrogen consumption site as it is. In comparison, hydrogen transport and hydrogen storage at high energy density are possible. Therefore, the hydrogen supply method of this embodiment is suitable for long-distance transportation and long-term storage of hydrogen.

  Further, in the water-soluble organic compound aqueous solution electrolysis step 4 at the hydrogen consumption site, hydrogen and carbon dioxide are separated and generated from the water-soluble organic compound aqueous solution at a low power compared to conventional water electrolysis. Is possible. For this reason, according to the present embodiment, the hydrogen generated in the water-soluble organic compound aqueous solution electrolysis step 4 can be easily supplied to the hydrogen consuming device, and the generated carbon dioxide is recovered to the hydrogen generation site. By transporting and reacting again with hydrogen, it can be used to produce water-soluble organic compounds. As a result, the mass balance of carbon dioxide can be made a substantially closed system, and the release of carbon dioxide that causes global warming can be suppressed.

  Next, a hydrogen supply method according to a second embodiment of the present invention will be described with reference to FIG. The hydrogen supply method of the second embodiment is the same as the hydrogen supply method of the first embodiment shown in FIG. 1, but the first is that a water-soluble organic compound aqueous solution preparation step is not provided. This is different from the method of the embodiment.

  First, in the water electrolysis process 1, using electric power generated using renewable natural energy such as sunlight, wind power, wave power, ocean temperature difference, hydropower, geothermal heat, etc. obtained at a specific site, or using nuclear power Using the generated power, water is electrolyzed to generate hydrogen and oxygen. These electric powers are effective in preventing global warming because they do not generate carbon dioxide during the power generation process.

  Next, in the case of using methanol as the water-soluble organic compound in the first embodiment by reacting hydrogen generated in the water electrolysis step 1 with the recovered carbon dioxide described later in the water-soluble organic compound aqueous solution synthesis step 6 A water-soluble organic compound aqueous solution is synthesized in the same manner as described above. The water-soluble organic compound aqueous solution synthesized in the water-soluble organic compound aqueous solution synthesis step 6 is transported to the hydrogen consumption site and stored.

  In the third water-soluble organic compound aqueous solution electrolysis step 4, the water-soluble organic compound aqueous solution transported and stored at the hydrogen consumption site described above is electrolyzed using midnight power to separate hydrogen and carbon dioxide. To generate. Hydrogen generated in the water-soluble organic compound aqueous solution electrolysis step 4 is supplied to a hydrogen consuming device and consumed. On the other hand, the carbon dioxide generated in the water-soluble organic compound aqueous solution electrolysis step 4 is supplied to the carbon dioxide recovery step 5.

  In the carbon dioxide recovery step 5 as the fourth step, the carbon dioxide generated in the water-soluble organic compound aqueous solution electrolysis step 4 is recovered and supplied to the water-soluble organic compound aqueous solution synthesis step 6 as recovered carbon dioxide. As described above, the recovered carbon dioxide is used in the water-soluble organic compound aqueous solution synthesis step 6 to react with the hydrogen generated in the water electrolysis step 1 to synthesize the water-soluble organic compound.

  Also in this embodiment, as in the case of the first embodiment, hydrogen can be transported from a hydrogen generation site to a hydrogen consumption site in the form of a water-soluble organic compound aqueous solution such as a methanol aqueous solution. Compared with the case of transporting to a hydrogen consumption site as it is, hydrogen transport and hydrogen storage at a high energy density are possible. Therefore, the hydrogen supply method of this embodiment is suitable for long-distance transportation and long-term storage of hydrogen. Further, in the water-soluble organic compound aqueous solution electrolysis step 4 at the hydrogen consumption site, hydrogen and carbon dioxide are separated and generated from the water-soluble organic compound aqueous solution at a low power compared to conventional water electrolysis. Is possible. For this reason, according to the present embodiment, the hydrogen generated in the water-soluble organic compound aqueous solution electrolysis step 4 can be easily supplied to the hydrogen consuming device, and the generated carbon dioxide is recovered to generate a hydrogen generation site. It can be used for synthesizing an aqueous solution of a water-soluble organic compound by being transported to a hydrogen atom and reacted again with hydrogen. As a result, the mass balance of carbon dioxide can be made a substantially closed system, and the release of carbon dioxide that causes global warming can be suppressed.

  The hydrogen supply method according to the preferred embodiment of the present invention has been described above. However, in the hydrogen supply method according to the present invention, as a medium for transporting and storing hydrogen, instead of an aqueous methanol solution, another aqueous organic compound is used. An aqueous solution can also be used. The water-soluble organic compound used in the present invention is not particularly limited as long as it is a water-soluble organic compound, but among them, an organic compound that dissolves in an arbitrary ratio with respect to water is preferable. Also preferred are organic compounds whose constituent elements are hydrogen, carbon, and optionally oxygen. Specific examples of water-soluble organic compounds that can be used in the present invention include water-soluble alcohols, organic acids, ketones, amines, nitroalkanes, ethers (including cyclic ethers), aldehydes, or derivatives thereof. Can be mentioned. Alcohols, organic acids, ketones, amines, nitroalkanes, ethers, and aldehydes preferably have about 1 to 20 carbon atoms. The cyclic ether preferably has a 4- to 6-membered ring skeleton, and the number of carbon atoms in the cyclic ether is preferably about 5 to 10.

  Examples of the water-soluble alcohol include methanol, ethanol, normal propanol, isobropanol (2-propanol), normal butanol, isobutanol, sec-butanol, tert-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 1-hexanol, 2-hexanol, 3-hexanol, 5-methyl-1-hexanol, isoamyl alcohol (3-methyl-1-butanol), sec-isoamyl alcohol (3-methyl- 2-butanol), isoundecylene alcohol, isooctanol, isopentanol, isogeranol, isohexanol, 2,4-dimethyl-1-pentanol, 2,4,4-trimethyl-1-pentanol, etc. Monovalent alcohol with 1-20 atoms , Dihydric alcohols such as ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,2-propanediol, 1,2-pentanediol, or butanetriol, glycerin, di Examples thereof include polyhydric alcohols having 3 to 10 carbon atoms such as glycerin.

  Examples of the water-soluble organic acid include acetic acid and propionic acid. Examples of the water-soluble ketone include acetone, methyl ethyl ketone, cyclohexanone, cyclooctanone, cyclodecanone, and isophorone. Examples of the water-soluble amine include methylamine and ethylamine. Examples of the nitroalkane having water solubility include nitroethane. Examples of the water-soluble ether include dimethyl ether, diethyl ether, polyoxyethylene phenyl ether, polyoxyethylene octyl phenyl ether, and the like. Examples of the water-soluble cyclic ether include tetrahydrofuran, 1,4-dioxane, 1,3-dioxane and the like. Examples of the water-soluble aldehyde include formaldehyde and acetaldehyde.

  Other water-soluble organic compounds that can be used in the present invention include esters such as ethyl acetate, ethylene glycol alkyl ethers such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve, and acetates thereof, ethyl carbitol, butyl carbitol, and the like. Diethylene glycol alkyl ethers and acetates thereof, propylene glycol alkyl ethers and acetates thereof, monohydric alcohols having 4 to 30 carbon atoms, phenolic compounds having 6 to 30 carbon atoms, alkylene having 6 to 30 carbon atoms An active hydrogen-containing compound composed of a polyamine having 2 to 6 carbon atoms (2 to 4 nitrogen atoms) such as glycol, polyhydric alcohol having 6 to 30 carbon atoms, ethylenediamine, diethylenepolyamine, etc. Water-soluble liquid alkylene oxide adducts with added pyrene oxide (1 to 10 moles of ethylene oxide), water-soluble polymers such as polyvinyl alcohol, various sugars such as saccharose and glucose, water-soluble polymers such as methyl cellulose and water-soluble starch Examples thereof include saccharides or derivatives thereof.

  Especially, as a water-soluble organic compound used by this invention, a C3-C10 polyhydric alcohol, a C1-C20 monohydric alcohol, and a C3-C20 ketone are preferable, Furthermore, Alcohols such as methanol, ethanol and 2-propanol are more preferable. As the water-soluble organic compound used in the present invention, only one kind of compound as described above may be used alone, or two or more kinds of compounds as described above may be used in combination. In the present invention, the water-soluble organic compound aqueous solution may contain other components as long as the water-soluble organic compound as described above is contained.

  It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications are made without departing from the spirit of the present invention.

It is process drawing which shows the hydrogen supply method of the 1st Embodiment of this invention. It is a graph which shows the relationship between the electrolysis voltage at the time of performing the electrolysis of methanol aqueous solution, and the electrolysis of water. It is a graph which shows the relationship between the hydrogen production | generation rate and electrolysis current in the electrolysis of methanol aqueous solution. It is process drawing which shows the hydrogen supply method of the 2nd Embodiment of this invention.

Explanation of symbols

1 Water electrolysis process 2 Water-soluble organic compound synthesis process 3 Water-soluble organic compound aqueous solution preparation process 4 Water-soluble organic compound aqueous solution electrolysis process 5 Carbon dioxide recovery process 6 Water-soluble organic compound aqueous solution synthesis process

Claims (5)

In a hydrogen supply method using a water-soluble organic compound aqueous solution as a medium for transporting and storing hydrogen, and having a mass balance of carbon dioxide as a substantially closed system,
A water electrolysis process in which water is electrolyzed with electric power obtained from a predetermined energy source, and hydrogen and oxygen are separated and generated;
A water-soluble organic compound synthesis step of synthesizing a water-soluble organic compound from the recovered carbon dioxide and the hydrogen obtained in the water electrolysis step;
A water-soluble organic compound aqueous solution preparation step of preparing the water-soluble organic compound aqueous solution having a predetermined concentration by mixing the water-soluble organic compound synthesized in the water-soluble organic compound synthesis step and water;
Electrolysis of the water-soluble organic compound aqueous solution prepared in the water-soluble organic compound aqueous solution preparation step with electric power obtained from a predetermined energy source to separate and generate hydrogen and carbon dioxide to produce water-soluble organic compound aqueous solution electrolysis Process,
A carbon dioxide recovery step of recovering the carbon dioxide generated in the water-soluble organic compound aqueous solution electrolysis step, and supplying the recovered carbon dioxide as the recovered carbon dioxide to the water-soluble organic compound synthesis step;
The hydrogen supply method characterized by having.   The hydrogen supply method according to claim 1, wherein the water-soluble organic compound synthesized in the water-soluble organic compound synthesis step is at least one compound selected from the group consisting of methanol, ethanol, and 2-propanol. In a hydrogen supply method using a water-soluble organic compound aqueous solution as a means for transporting and storing hydrogen, and having a mass balance of carbon dioxide as a substantially closed system,
A water electrolysis process in which water is electrolyzed with electric power obtained from a predetermined energy source, and hydrogen and oxygen are separated and generated;
A water-soluble organic compound aqueous solution synthesis step for synthesizing a water-soluble organic compound aqueous solution from the recovered carbon dioxide and the hydrogen obtained in the water electrolysis step;
A water-soluble organic compound aqueous solution in which the water-soluble organic compound aqueous solution synthesized in the water-soluble organic compound aqueous solution synthesis step is electrolyzed with electric power obtained from a predetermined energy source to generate hydrogen and carbon dioxide separately. An electrolysis process;
A carbon dioxide recovery step of recovering the carbon dioxide generated in the water-soluble organic compound aqueous solution electrolysis step, and supplying the recovered carbon dioxide as the recovered carbon dioxide to the water-soluble organic compound aqueous solution synthesis step;
The hydrogen supply method characterized by having.   The hydrogen supply according to claim 3, wherein the water-soluble organic compound aqueous solution synthesized in the water-soluble organic compound aqueous solution synthesis step is an aqueous solution of at least one compound selected from the group consisting of methanol, ethanol, and 2-propanol. Method.   The hydrogen supply method according to any one of claims 1 to 4, further comprising a step of supplying hydrogen generated in the water-soluble organic compound aqueous solution electrolysis step to a hydrogen supply destination.

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