How to store carbon dioxide

Abstract

To provide a system and a method for storing carbon dioxide by utilizing a cleaning material by which water quality improvement and atmosphere quality improvement can be performed.SOLUTION: This method includes the steps in which: a carbonized product and a carbonized gas are generated by carbonizing biomass; an iron-containing carbonized product is produced by mixing an iron powder and / or an iron oxide powder in the carbonized product; the iron-containing carbonized product is brought into contact with a nitrogen oxide and / or a sulfur oxide and a carbon dioxide-containing gas; and the iron-containing carbonized product is brought into contact with water containing a phosphorus compound. Further, this method may include power generation using the carbonized gas.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One embodiment of the present invention relates to a system and method for storing carbon dioxide. [Background technology]

[0002] Adsorbents containing iron and carbon-based carbides prepared from biomass are capable of adsorbing phosphate ions derived from phosphoric acid. Therefore, they are known to be useful for improving water quality in bodies of water such as rivers, lakes, and oceans, and for recovering phosphorus from sludge dewatering separation liquid at sewage treatment plants. Furthermore, adsorbents with adsorbed phosphate ions can also be used as fertilizer. Therefore, by applying the adsorbent to soil after adsorbing phosphate ions, it is possible to effectively utilize the carbon dioxide fixed by plants and store the carbon dioxide in the soil. Therefore, adsorbents obtained from biomass play a central role in carbon sequestration for the fixation of greenhouse gases in the atmosphere (see Patent Document 1 and Non-Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-75706 [Non-patent literature]

[0004] [Non-Patent Document 1] Akira Shibata, "Simple carbonization of biomass and carbon storage vegetables for regional development" COOL VEGETM, Journal of the High Temperature Society, March 2011, Vol. 37, No. 2, pp. 37-42 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of one embodiment of the present invention is to provide a system and method for storing carbon dioxide. Alternatively, an object of one embodiment of the present invention is to provide a system and method for storing carbon dioxide using a purification material that can improve water quality and air quality. [Means for solving the problem]

[0006] One embodiment of the present invention is a method for storing carbon dioxide, which includes carbonizing biomass to produce a carbonized material and a dry distillation gas, mixing the carbonized material with iron powder and / or iron oxide powder to produce an iron-containing carbonized material, contacting the iron-containing carbonized material with a gas containing nitrogen oxides and / or sulfur oxides and carbon dioxide, and contacting the iron-containing carbonized material with water containing a phosphorus compound. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a conceptual diagram illustrating a system for storing carbon dioxide according to one embodiment of the present invention. [Figure 2] 1 is a flow chart illustrating a method for producing a purification material that can be used in a system and method according to one embodiment of the present invention. [Figure 3] 1 is a schematic perspective view of a cartridge for adsorbing phosphorus compounds in a system and method according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, various embodiments of the present invention will be described with reference to the drawings, etc. However, the present invention can be embodied in various forms without departing from the spirit of the present invention, and should not be construed as being limited to the description of the embodiments exemplified below.

[0009] One embodiment of the present invention is a system and method for improving water and air quality while storing carbon dioxide. A conceptual diagram of this system is shown in Figure 1. This system uses biomass as a starting material to generate energy and remove pollutants from water and air. Furthermore, this system aims to promote plant growth through soil improvement and reduce greenhouse gases such as carbon dioxide. The grown plants are used as food or materials, and biomass is regenerated as residue. This series of steps completes the cycle shown in Figure 1. A more detailed explanation is provided below.

[0010] 1. Carbonization First, this system uses biomass as a raw material to produce charcoal, which serves as a substrate for iron-containing charcoal (described below), which functions as a purification material. Biomass refers to a type of organic matter, including biologically derived substances and their metabolites. Examples of biomass include wood-derived materials. Specific examples include planks and columns of wood, thinnings, pruning waste, construction waste, powdered sawdust, and wooden molded products such as particle boats. There are no restrictions on the type of wood, and cedar, cypress, and bamboo are also suitable. Other examples of biomass include agricultural waste such as rice husks, bagasse, corn cobs and leaves, and agricultural by-products such as straw, wheat straw, and hay. Other examples include plants that are used to produce fibers, such as hemp, flax, cotton, sisal, abaca, and palm hair. Seaweed and other algae are also suitable. Other examples include food waste and silage made from animal waste.

[0011] Carbonization is carried out by heating biomass under conditions of low oxygen concentration. For example, carbonization is carried out by heating biomass under an inert gas atmosphere such as nitrogen gas or argon gas, an oxygen-free atmosphere, a low-oxygen atmosphere, a reducing atmosphere, or a reduced-pressure atmosphere. When carbonization is carried out under a reduced-pressure atmosphere, 10 2 Pa or more 10 5 Low vacuum state below 10 Pa -1 Pa or more 10 2 Medium vacuum state below 10 Pa -5 Pa or more 10 -1 High vacuum state below 10 Pa or-5 The carbonization can be carried out in an ultra-high vacuum of 100 Pa or less. When carbonization is carried out in a low-oxygen atmosphere, the oxygen concentration can be set to 0.01% to 3%, or 0.1% to 2%. The heating temperature for carbonization can be 400°C to 1200°C, 500°C to 1100°C, 600°C to 1000°C, or 600°C to 900°C. The heating time can be 10 minutes to 10 days, or 10 minutes to 5 hours.

[0012] Carbonization may be carried out using an internal combustion or external heat carbonization furnace, such as a batch-type closed charcoal furnace, a continuous rotary kiln, a rocking carbonization furnace, or a screw furnace.

[0013] Carbonization of biomass generates pyrolysis gas, and a porous carbonized material is produced with pores of various shapes and sizes, which are a complex mixture of pores due to the structure of the biomass and pores formed by the desorption of pyrolysis gas. The pores formed inside the carbonized material give the carbonized material a large specific surface area. Specifically, the specific surface area of ​​the carbonized material is 100 m 2 / g or more 900m 2 / g or less, 100m 2 / g or more 800m 2 / g or less, or 150m 2 / g or more 400m 2 The specific surface area may be measured by mercury intrusion porosimetry or a gas adsorption method such as the BJH method or the HK method.

[0014] 2. Energy generation using dry distillation gas The carbonization process produces pyrolysis gas, which primarily contains flammable or reducing gases, such as hydrogen, carbon monoxide, and alkanes, including methane, propane, and butane. The pyrolysis gas is extracted from the carbonization furnace at high temperatures (700 to 1300°C). Therefore, the thermal energy and flammability of the pyrolysis gas can be used as an energy source for hot water supply and power generation. For example, the pyrolysis gas can be introduced into a heat exchanger to extract thermal energy, which can then be used to generate hot water. Alternatively, the pyrolysis gas can be combusted and used to generate power. In this case, the pyrolysis gas can be used as fuel for gas turbine, gas engine, or dual-fuel engine power generation systems.

[0015] 3. Preparation of Iron-containing Carbide (1) Mixing and kneading In this system, iron (zero-valent iron) and / or an iron compound is further mixed with the carbide obtained by carbonization to prepare an iron-containing carbide. The flow for producing iron-containing carbide is shown in Figure 2. As shown in Figure 2, first, the carbide obtained by carbonizing biomass, a binder, and iron powder and / or iron oxide powder are mixed, and the resulting mixture is kneaded (mixed).

[0016] The iron powder may be iron powder that does not contain iron compounds, or iron powder that has iron compounds formed on its surface by oxidation of iron, such as divalent, trivalent, and / or mixed-valence iron compounds (a mixture of divalent and trivalent iron). In the latter case, the iron-containing carbide contains iron compounds, and examples of the iron compounds include iron hydroxide and iron oxide with divalent, trivalent, or mixed valences.

[0017] The iron oxide powder may be a powder of divalent, trivalent, or mixed valence iron oxide. The iron oxide powder may also contain iron hydroxide of divalent, trivalent, or mixed valence. As in the case of using surface-oxidized iron powder, the iron-containing carbide also contains the above-mentioned divalent, trivalent, or mixed valence iron oxide as the iron compound when using iron oxide powder.

[0018] The iron powder and the iron oxide powder may have an average particle size of 20 μm to 500 μm or 50 μm to 200 μm, or may have an average particle size of the iron powder and the iron oxide powder that is the same or substantially the same. Furthermore, iron powder may be used that has a particle size distribution in which 1) the proportion of iron particles having a particle size in the range of 1 μm or more and less than 150 μm is 3% to 70% by mass, 2) the proportion of iron particles having a particle size in the range of 1 μm or more and less than 75 μm is 0% to 25% by mass, 3) the proportion of iron particles having a particle size in the range of 1 μm or more and less than 45 μm is 0% to 15% by mass, 4) the proportion of iron particles having a particle size in the range of 150 μm or more and less than 2000 μm is 30% to 99% by mass, and 5) the proportion of iron particles having a particle size in the range of 600 μm or more and less than 2000 μm is 0% to 15% by mass, and the sum of the proportion of iron particles in at least one of 1) to 3) and the proportion of iron particles in 4) or 5) is 100% by mass. Here, the average particle size of the iron powder is the average value obtained by analyzing an image obtained by observing the iron powder under a microscope and determining the particle sizes of multiple iron particles. The particle size of each iron particle can be, for example, the diameter of a circle inscribed in the projection of each iron particle in a microscope image or the length of one side of a square. Because the particle size of carbides is often larger than that of iron powder or iron oxide powder, the carbides may be crushed and / or classified to have particle sizes roughly the same as those of iron powder or iron oxide powder before mixing and kneading. The particle size distribution and circularity of the iron oxide powder may be similar to those of the iron powder.

[0019] There are no restrictions on the shape of the iron powder or iron oxide powder. For example, iron powder or iron oxide powder with an average circularity of 50 to 100, 70 to 95, or 80 to 90 may be used. Here, average circularity is one of the parameters that describe the shape of each particle contained in the powder. It is obtained by analyzing an image obtained by observing the powder under a microscope, determining the circularity of multiple particles, and averaging the results. For example, the circularity can be calculated by dividing the perimeter of a circle with an area equal to the area of ​​the projection surface of each particle in the microscope image by the perimeter of the projection surface of the particle. Alternatively, the circularity can be calculated by dividing the area of ​​the projection surface by the area of ​​a circle inscribed in the projection surface.

[0020] There are no restrictions on the type of binder, and organic and / or inorganic binders can be used. Examples of organic binders include one or more selected from the group consisting of molasses, blackstrap molasses, starch, dextrin, cornstarch, rice bran, polyvinyl alcohol, vinyl acetate-ethylene copolymers or their saponified forms, pulp waste liquor, lignin sulfonate, carboxymethyl cellulose, hydroxypropyl methyl cellulose, sodium alginate, phenolic resins, and tar pitch. Molasses, among others, is inexpensive, contains few harmful components, and has a high solid content, making it easy to mold the purification material. Examples of inorganic binders include cement, ground granulated blast furnace slag, fly ash, gypsum (calcium sulfate), calcined gypsum obtained by heating and dehydrating gypsum, and sodium silicate.

[0021] The amounts of carbide, binder, iron powder, and iron oxide powder may be appropriately adjusted so that the carbide content in the resulting iron-containing carbide is within the range of 20% by mass to 80% by mass, 40% by mass to 80% by mass, or 60% by mass to 80% by mass; the iron and iron compound content is within the range of 5% by mass to 35% by mass, 5% by mass to 25% by mass, or 5% by mass to 20% by mass; and the binder content is within the range of 5% by mass to 50% by mass, 15% by mass to 50% by mass, or 20% by mass to 50% by mass.

[0022] When mixing or kneading, water is added to the carbide, binder, and iron powder and / or iron oxide powder as needed. Adding water prevents dust from being generated and allows the carbide, iron powder, and iron oxide powder to be mixed more uniformly.

[0023] A kneader can be used to mix and knead these raw materials. Examples of kneaders that can be used include single-screw kneaders, twin-screw kneaders, mixing rolls, kneaders, and Banbury mixers. Alternatively, a kneader with both mixing and kneading functions can be used. In this case, the carbide, iron powder and / or iron oxide powder, and binder are added to the kneader, followed by mixing and kneading. Alternatively, mixing and kneading can be performed continuously. For example, the carbide and iron powder and / or iron oxide powder are added to the kneader and mixed, and then the binder is added to the kneader and kneaded. The binder can be added all at once, intermittently, or continuously. By mixing the carbide and iron powder and / or iron oxide powder and then adding the binder and kneading, it is possible to prevent aggregation of the carbide and iron powder and / or iron oxide powder and suppress foaming.

[0024] The kneading temperature can be set arbitrarily, for example, from 0° C. to 50° C., or from 10° C. to 40° C. The kneading time can also be set appropriately taking into consideration the mixing ratio and amount of the raw materials, the type of binder, the capacity of the kneader, etc., and can be set within the range of, for example, from 1 second to 1 hour, from 1 minute to 30 minutes, or from 1 minute to 15 minutes.

[0025] The above procedure yields a paste-like precursor containing a mixture of carbide, binder, and iron powder and / or iron oxide powder. When iron powder containing no iron compounds is used without iron oxide powder, some of the iron powder may be oxidized during this process, resulting in an iron-supported carbide containing compounds containing divalent, trivalent, or mixed-valent iron. Examples of iron compounds include iron hydroxide and iron oxide, as described above.

[0026] (2) Granulation As an optional step, the mixture of the obtained carbide, iron powder and / or iron oxide powder, and binder may be granulated and molded into a certain shape. The mixture can be molded using a granulator. Examples of granulators include compression granulators, extrusion granulators, roll granulators, blade granulators, melt granulators, and spray granulators.

[0027] When using an extrusion granulator, a paste-like mixture formed into a predetermined shape is extruded from a die attached to the granulator. The extruded mixture is cut to a predetermined length and formed into pellets with the extrusion direction as the height direction. The length of the precursor (the height of the pellet shape) can be adjusted by adjusting the extrusion speed and cutting speed of the mixture in the extrusion granulator (the rotation speed of the cutter in the case of a rotary cutting method). In addition, the diameter of the mixture (the diameter if the cross-sectional shape is circular) can be adjusted by adjusting the opening diameter of the die. Therefore, by using an extrusion granulator, a mixture having a pellet shape with controlled size (for example, an approximately cylindrical shape) can be obtained.

[0028] The size of the pellet shape can be set arbitrarily, for example, the length of each pellet can be 1 mm to 20 mm, 3 mm to 15 mm, or 6 mm to 12 mm. If the cross section is circular, the diameter of the pellet can be 1 mm to 20 mm, 2 mm to 10 mm, or 3 mm to 8 mm.

[0029] The cross-sectional shape of the mixture after molding (cross-section perpendicular to the longitudinal direction) is not limited to a circle. The cross-sectional shape of the mixture may be, for example, an ellipse or a polygon. That is, the mixture after molding may have not only a cylindrical shape but also an elliptical cylindrical or polygonal cylindrical pellet shape. The cross-sectional shape of the mixture can be changed by changing the opening shape of the die. This granulation process may be performed after the drying process described below.

[0030] (3) Drying As an optional step, the mixture after molding may be dried. The drying temperature and time are also appropriately selected depending on the amount of mixture and the amount of water contained. For example, the drying temperature may be selected from the range of 30°C or higher but lower than 400°C, 50°C or higher but lower than 300°C, or 100°C or higher but lower than 300°C. The humidity during drying may be 20% or higher but lower than 95%, or 50% or higher but lower than 90%. The drying time may also be appropriately selected from the range of 1 minute or higher but lower than 1 week, 1 hour or higher but lower than 3 days, or 3 hours or higher but lower than 1 day. The drying atmosphere may also be, for example, air, nitrogen, a rare gas such as argon, or a mixture of these. Biomass may also be carbonized in a separate batch, and drying may be performed using the thermal energy of the resulting dry distillation gas.

[0031] The above steps allow for the production of iron-containing carbide. This method does not require high-temperature firing. In other words, it is not necessary to heat the binder to a temperature (e.g., 400°C or higher) required for carbonizing the binder. This eliminates the need for the time and energy required for firing, making it possible to provide iron-containing carbide at lower cost.

[0032] 4.Removal of nitrogen oxides This system uses nitrogen oxides (NO x ) and sulfur oxides (SO xAir pollutants such as nitrogen oxides and / or sulfur oxides are removed by iron-containing carbides. Specifically, a gas containing nitrogen oxides and / or sulfur oxides is brought into contact with the iron-containing carbide to remove the air pollutants. The gas may further contain carbon dioxide. The carbides and binders used as raw materials for the iron-containing carbide contain oxides and salts (hydroxides, halides, sulfates, nitrates) of alkali metals and alkaline earth metals. When the carbides and binders are brought into contact with a gas containing carbon dioxide, at least some of these oxides and salts are converted to carbonates or bicarbonates (carbonation). In general, carbonates and bicarbonates of alkali metals and alkaline earth metals are less soluble in water than hydroxides, halides, sulfates, and nitrates. Therefore, by promoting carbonation, alkali metals and alkaline earth metals remain as carbonates or bicarbonates during the treatment of water with the iron-containing carbide (described later). This improves the shape stability of the iron-containing carbide in water and prevents its disintegration in water.

[0033] Therefore, the gas containing air pollutants may be the atmosphere or exhaust gas from facilities that emit large amounts of carbon dioxide (such as chemical plants, waste incineration facilities, thermal power plants, and various other factories). The exhaust gas does not need to be denitrified or desulfurized. Alternatively, exhaust gas from vehicles may be used, or, as shown in Figure 1, exhaust gas produced when carbonized gas is combusted to generate electricity. By using such gases, not only can substances that cause air pollution be removed, but carbon dioxide, which acts as a greenhouse gas, can also be efficiently fixed.

[0034] 5. Fixation of phosphorus compounds This system uses iron-containing carbides, which have been treated with gases containing air pollutants, to adsorb and immobilize phosphorus compounds contained in water (water to be treated) from various bodies of water, thereby improving water quality. The contact between the iron-containing carbides and the water to be treated can be carried out continuously or batchwise. In the latter case, as shown in FIG. 3, a cartridge 100 having a mesh-like housing 102 filled with iron-containing carbides 106 can be used to bring the water to be treated into contact with the iron-containing carbides 106. The mesh size can be, for example, 0.1 mm to 50 mm or 0.5 mm to 20 mm. If the housing 102 does not have sufficient weight, a weight 104 can be attached to the housing 102 to ensure that it is securely placed in the water to be treated. Instead of the weight 104, anchors (not shown) can be attached to the housing 102 to secure it to the bottom of a river or lake, a septic tank, or an advanced treatment tank. In this way, by filling the cartridge 100 with iron-containing carbide 106 and bringing the water to be treated into contact with iron-containing carbide 106, it becomes easier to handle the iron-containing carbide 106. Furthermore, as described above, when the gas containing air pollutants contains carbon dioxide, carbonation can prevent the iron-containing carbide 106 from disintegrating in water, so that the disintegrated iron-containing carbide 106 does not flow out of the mesh-like casing 102, and the iron-containing carbide 106 can be reliably collected.

[0035] Although not shown in Fig. 1, the water to be treated may be treated before treating the gas containing air pollutants with iron-containing carbides. Alternatively, the gas containing air pollutants may be treated again after treating the gas containing air pollutants with iron-containing carbides and the water to be treated.

[0036] 5. Fertilizer production Because phosphorus compounds function as nutrients that promote the growth of various plants, iron-containing carbides with immobilized phosphorus compounds can function as fertilizers. Therefore, iron-containing carbides can be used as phosphorus-containing fertilizers after purifying air containing air pollutants and treating water to be treated. Furthermore, when carbon dioxide is present in the gas containing air pollutants, the alkali metal and alkaline earth salts contained in the carbide are carbonated, as are the alkali metal and alkaline earth salts contained in the binder. In particular, when cement or ground granulated blast furnace slag is used as a binder, these contain large amounts of calcium hydroxide and calcium oxide. Therefore, applying iron-containing carbides to soil without carbonation increases the soil pH. However, when iron-containing carbides come into contact with carbon dioxide, the calcium hydroxide and calcium oxide are converted to calcium carbonate or calcium bicarbonate. Furthermore, residual basic salts such as calcium hydroxide and calcium oxide can be removed during treatment with the water to be treated, thereby preventing an increase in soil pH.

[0037] In the production of fertilizer from iron-containing carbide, the iron-containing carbide is first crushed. Crushing can be performed using a crusher. There are no restrictions on the structure or type of crusher, and examples include a vibration mill, jet mill, ball mill, roller mill, rod mill, hammer mill, impact mill, rotary mill, pin mill, pin-disk mill, or planetary mill. Crushing the iron-containing carbide using a crusher increases the surface area, which in turn promotes the release of phosphorus compounds fixed on the iron-containing carbide.

[0038] The crushed iron-containing carbide may be classified to have a particle size suitable for use as a fertilizer. There are no restrictions on the structure or type of classifier, and either a dry classifier or a wet classifier may be used. Examples of classifiers include air classifiers, gravity field classifiers, inertial field classifiers, and centrifugal field classifiers.

[0039] The crushed and classified iron-containing carbide may be mixed with other fertilizer components. Examples of such fertilizer components include one or more selected from nitrogen, potassium, calcium, magnesium, manganese, silica, and boron. Specific examples of materials include oil cake, flavored chicken manure, fish meal, bone meal, rice bran, bat guano, compost, wood ash, lime, and chemical fertilizer. These fertilizer components are mixed with the iron-containing carbide using a mixer. There are no limitations on the structure or type of the mixer; a free-fall mixer, forced mixer, Y-branch mixer, agitator mixer, or paddle mixer can be selected as desired.

[0040] 6. Soil improvement and plant growth The resulting fertilizer is spread on the soil to help plants grow. There are no restrictions on the method of spreading the fertilizer into the soil; for example, a gravity-drop spreader such as a ground sower or a diffusion-type spreader that uses compressed air can be used. There are also no restrictions on the application method; either a stripe-type spreader or an all-over-area spreader can be used. It is preferable to spread the fertilizer within 30 cm of the soil surface. Spreading the fertilizer promotes plant growth. In other words, carbon dioxide from the atmosphere is fixed through plant photosynthesis, creating resources that can be used as food and materials.

[0041] As described above, in this system, atmospheric carbon dioxide is fixed by photosynthesis in plants to form organic matter, and the biomass generated through its utilization and metabolism is carbonized to produce charcoal and pyrolysis gas (Figure 1, (1)). The pyrolysis gas is used as an energy source (2), while the charcoal is converted into iron-containing carbides that function as a purification material (3). This purification material can remove air pollutants from the atmosphere or from exhaust gases generated by burning pyrolysis gas (4) and can also fix phosphorus compounds in water (5). The purification material is converted into fertilizer, contributing to plant growth (7), and is ultimately returned to the ground as carbon, thereby storing carbon dioxide underground. Through this series of processes, this system contributes to purifying the air and reducing carbon dioxide emissions.

[0042] As described above, iron-containing carbides can remove or immobilize water and air pollutants. Therefore, this system can contribute to environmental conservation by improving water and air quality. Furthermore, when producing the raw material for iron-containing carbides, thermal and electrical energy is generated from the dry distillation gas produced by carbonizing biomass. The exhaust gas generated during this process can be purified using iron-containing carbides. Therefore, this system can be said to contribute to energy generation without placing a significant burden on the environment. Furthermore, iron-containing carbides that remove or immobilize water and air pollutants can also function as fertilizer to promote plant growth without increasing soil pH. Therefore, this system can also be said to contribute to the development of agriculture and forestry.

[0043] The above-described embodiments of the present invention can be combined as appropriate as long as they are not mutually inconsistent. A product in which a person skilled in the art appropriately adds or deletes components or modifies the design based on each embodiment is also included within the scope of the present invention as long as it includes the gist of the present invention.

[0044] Even if there are other effects and advantages different from those brought about by the above-described embodiments, those that are clear from the description in this specification or that can be easily predicted by a person skilled in the art are naturally understood to be brought about by the present invention. [Explanation of symbols]

[0045] 100: cartridge, 102: housing, 104: weight, 106: iron-containing carbide

Claims

1. carbonizing the biomass to produce char and carbonization gas; mixing the carbide with iron powder and / or iron oxide powder to produce an iron-containing carbide; contacting the iron-containing carbide with a first gas containing nitrogen oxides and / or sulfur oxides and carbon dioxide; and A method for storing carbon dioxide, comprising contacting the iron-containing carbide with water containing a phosphorus compound.

2. The method of claim 1 further comprising generating electricity using the carbonized gas.

3. The method of claim 2 , wherein the first gas is an exhaust gas produced in the power generation.

4. The method of claim 1 , further comprising spreading the iron-containing carbide contacted with the water on soil.

5. The method of claim 1 , wherein the contact with the water occurs after the contact with the first gas.

6. The method of claim 5, further comprising contacting the iron-containing carbide with the water containing the phosphorus compound and then contacting the iron-containing carbide with a second gas containing nitrogen oxides and carbon dioxide.

7. The method of claim 1 , wherein the mixing with the iron powder and / or iron oxide powder is performed by mixing the carbide, a binder, and the iron powder and / or iron oxide powder.

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