Resource circulation method

Abstract

To provide a resource circulation method which can efficiently utilize a large amount of residual crops generated in a farm field as a resource.SOLUTION: A resource circulation method includes: a residual crop collection step in which residual crops generated in a farm field are collected; an anaerobic treatment step in which the residual crops collected in the residual crop collection step are subject to methane fermentation; an energy utilization step in which a biogas generated in the anaerobic treatment step is utilized as an energy source; and a return step in which fermentation residues generated in the anaerobic treatment step are returned to the farm field.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention is a resource recycling method. By law Regarding. [Background technology]

[0002] Traditionally, the large amounts of rice straw generated during rice harvesting have been plowed into the soil as organic fertilizer or incinerated on the field. However, methane, which is generated when the plowed-in rice straw decomposes in the soil in an anaerobic atmosphere, is a greenhouse gas that has a significant impact on global warming. In addition, the soot and smoke generated when rice straw is incinerated on the field cause air pollution and odor problems. Therefore, how to dispose of large amounts of rice straw has become an issue. This issue is not limited to rice straw, but is also common to agricultural waste (referred to as "harvest residue" in this specification) generated after the harvest of grains harvested on the field, including wheat straw.

[0003] Patent Document 1 proposes a methane fermentation method in which straw crushed into pieces of 10 mm to 100 mm is subjected to methane fermentation in a fermentation liquid, biogas is recovered, and the fermented straw is recovered from the digestion liquid and used as bedding. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5567718 Summary of the Invention [Problem to be solved by the invention]

[0005] The methane fermentation method disclosed in Patent Document 1 is a very desirable technology from the viewpoint of effective utilization of biomass resources, but there is room for further improvement in terms of efficiently processing the large amounts of harvest residues generated in farm fields, including rice straw and wheat straw.

[0006] The object of the present invention is to develop a resource recycling method that can efficiently utilize the large amount of harvest residue generated in farm fields as a resource. The law The point is to provide. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, a first characteristic configuration of the resource circulation method according to the present invention includes a harvest residue collection step of collecting harvest residue generated in a farm field, and an anaerobic treatment step of methane fermenting the harvest residue collected in the harvest residue collection step. an energy utilization step in which the biogas produced in the anaerobic treatment step is utilized as an energy source; and a reduction step of returning the fermentation residue produced in the anaerobic treatment step to a farm field.

[0008] Harvest residue collected in the field is fermented into methane through an anaerobic treatment process, and the methane gas produced is recovered and used as energy.The fermentation residue is then returned to the field as compost or fertilizer, thereby recycling resources and reducing farming costs.

[0009] The second characteristic configuration of the present invention is, in addition to the first characteristic configuration described above, The energy utilization step is biogas power generation.

[0010] The third characteristic configuration of the present invention is, in addition to the first characteristic configuration described above, The method further includes a raw material storage step for storing the harvest residue between the harvest residue collection step and the anaerobic treatment step, and at least a portion of the harvest residue stored in the raw material storage step is supplied to the anaerobic treatment step.

[0011] When harvest seasons overlap, large amounts of harvest residue are collected from the fields. By temporarily storing such large amounts of harvest residue in the raw material storage process and supplying a portion of it to the anaerobic treatment process as needed, the harvest residue can be used efficiently, even outside of the harvest season.

[0012] Same number four The characteristic configuration of the above three In addition to the characteristic configuration of (1), the raw material storage step is a step of distributing and storing the harvest residue collected in the harvest residue collecting step in a plurality of storage locations.

[0013] Even when a large amount of harvest residue is collected at one time, by distributing the harvest residue across multiple storage locations, it is no longer necessary to secure a large area for storage, and by storing it in the nearest storage location, transportation costs can also be reduced.

[0014] The sixth characteristic configuration of the present invention is, in addition to any one of the first to fourth characteristic configurations described above, A fermentation residue storage step for storing the fermentation residue produced in the anaerobic treatment step is provided between the anaerobic treatment step and the reduction step, and at least a portion of the fermentation residue stored in the fermentation residue storage step is returned to a farm field.

[0015] By storing the fermentation residue produced in the anaerobic treatment process, it can be returned as compost or fertilizer to the necessary fields when needed. [Effects of the Invention]

[0016] As described above, according to the present invention, a resource recycling method is provided that can efficiently utilize the large amount of harvest residue generated in farm fields as a resource. The law It has become possible to provide. [Brief explanation of the drawings]

[0017] [Figure 1] An explanatory diagram showing how to process harvest residues generated in the field [Figure 2] An explanatory diagram of a resource recycling method for harvest residues generated in farm fields [Figure 3] A characteristic diagram showing the correlation between the length L of the harvest residue (rice straw) and the retention time (HRT) and throughput. DETAILED DESCRIPTION OF THE INVENTION

[0018] Below, we will explain the anaerobic treatment method of the present invention and the resource circulation method incorporating the anaerobic treatment method, using rice straw, which is the rice harvest residue generated in the field, as an example. The law explain.

[0019] [Resource recycling system] FIG. 1 illustrates a resource circulation system 1 in which the resource circulation method of the present invention is carried out. The resource circulation system 1 is constructed for each community farming operation or for multiple neighboring community farming operations, and includes multiple fields 2 where rice straw, which is harvest residue 3, is produced, multiple storage locations 5 for storing the harvest residue 3, a methane fermentation apparatus 6 that mainly processes the harvest residue 3 through methane fermentation, and a gasification apparatus 9 that produces synthetic gas from the harvest residue 3. While Figure 1 shows a single methane fermentation apparatus 6 and gasification apparatus 9, in practice, multiple methane fermentation apparatuses 6 and / or multiple gasification apparatuses 9 may be installed in separate locations or together in one place, depending on the scale of the harvest residue 3 to be received.

[0020] The system is also equipped with a biogas power generation system 8 that generates electricity using the methane gas (biogas) produced in the methane fermentation system 6 as fuel, and the electricity generated by the biogas power generation system 8 is consumed as electrical energy in the area, while the waste heat from combustion produced in the biogas power generation system 8 is used as a heat source for the methane fermentation system 6 and the greenhouse. In addition, the carbon dioxide produced in the biogas power generation system 8 is supplied to the greenhouse as raw gas for photosynthesis.

[0021] The methane fermentation device 6 is equipped with a methane fermentation tank containing a fermentation liquid, a feeding device that feeds the harvest residue 3 into the methane fermentation tank, a stirring mechanism that stirs the harvest residue 3 and the fermentation liquid, and a heating mechanism that adjusts the fermentation temperature. Part of the exhaust heat from combustion generated during power generation is supplied to the heating mechanism, where it is heated to approximately 55°C, which is suitable for high-temperature fermentation, and the organic matter is digested under anaerobic conditions to produce biogas such as methane gas and carbon dioxide.

[0022] A fermentation residue storage device 7 that stores the fermentation residue produced in the methane fermentation device 6 is provided near the methane fermentation device 6, and the fermentation residue stored in the fermentation residue storage device 7 is returned to the farm field 2 as compost or fertilizer.

[0023] The gasification equipment 9 is equipped with a reactor tower into which chopped harvest residue 3 is fed. Inside the reactor, the harvest residue 3 is stirred and flowed with high-temperature steam and oxygen gas, causing a water-gas reaction and a water-gas shift reaction, producing synthesis gas containing hydrogen and carbon monoxide. Biochar, consisting of carbon components including silica, is also produced as ash discharged along with the synthesis gas.

[0024] The water-gas reaction is an endothermic reaction in which carbon monoxide (CO) and hydrogen (H2) are produced from solid carbon (C) and water vapor (H2O) contained in the harvest residue 3 in a high-temperature environment of 500°C or higher, as shown in the following formula: C+H2O → CO+H2

[0025] The water-gas shift reaction is an exothermic reaction in which carbon dioxide CO2 and hydrogen H2 are produced from carbon monoxide CO and water vapor H2O in a high-temperature environment of 800°C or higher, as shown in the following formula: CO+H2O → CO2+H2

[0026] The synthesis gas produced in the gasification unit 9 is purified by the gas purification unit 10, and the biochar containing the carbon removed from the synthesis gas is returned to the farm field 2 as compost or fertilizer together with the fermentation residues mentioned above.

[0027] The system is equipped with a syngas power generation plant 11 that generates electricity using the syngas produced in the gasification plant 9 as fuel, and the generated electricity is supplied as electrical energy for the local area, and the combustion waste heat produced in the syngas power generation plant 11 is used as a heat source for the methane fermentation plant 6 and the greenhouse. In addition, the carbon dioxide produced in the syngas power generation plant 11 is supplied to the greenhouse as a raw material for photosynthesis.

[0028] An FT synthesis unit that synthesizes liquid hydrocarbons to be used as fuel using a catalytic reaction from a synthesis gas composed of carbon monoxide and hydrogen as a raw material may be provided instead of the synthesis gas power generation unit 11. FT synthesis is an abbreviation for Fischer-Tropsch synthesis, and refers to a series of synthesis reaction processes that synthesize liquid hydrocarbons from carbon monoxide and hydrogen using a catalytic reaction.

[0029] When the rice harvest season arrives, the large amount of rice straw remaining in the post-harvest field 2, i.e., harvest residue 3, is collected in cylindrical packs using a roll baler, for example. It is physically difficult, including the cost of equipment, to collect such a large amount of harvest residue in one place and subject it to methane fermentation all at once, and even if a large amount of biogas is produced temporarily, it may not be able to be used effectively, so a separate biogas storage facility is required.

[0030] Therefore, multiple storage locations 5 are provided in a dispersed manner throughout the farming areas that make up the community-based farming, and the harvest residue 3 collected in each field 2 is cut into pieces of a predetermined size using a crusher that can cut the residue into pieces as needed, such as a chipper shredder, used as a pre-treatment device 4, and then accumulated in the nearest storage location 5. "As needed" means that the storage location 5 is adjusted to correspond to the raw material retention time (HRT) during methane fermentation, which is adjusted according to various demand forecasts by the management device 20, which will be described later.

[0031] The storage areas 5 are provided in various forms, such as storage areas with roofs and storage areas without roofs where waste is stored in the open. An appropriate number of methane fermentation devices 6 and / or gasification devices 9 are provided depending on the layout and number of the storage areas 5.

[0032] Each community farming operation, or each of multiple neighboring community farming operations, is provided with a management device 20, which is a cloud-based server equipped with a storage device 21, to manage the harvest residue 3. The management device 20 manages information such as the storage location and storage format, as well as the start date of storage (rice harvesting time), cutting length, variety, and grower. The manager of the methane fermentation device 6 and the manager of the gasification device 9 are configured to be able to grasp the management status of the harvest residue 3 via a terminal device that can communicate with the management device 20.

[0033] The management device 20 creates a storage plan and utilization plan for the harvest residue 3 based on the annual demand forecast until the next harvest, and based on this plan, the harvest residue 3 is dispersed and stored in different crushed states in multiple storage locations 5 for utilization. Uncrushed harvest residue 3 is piled up in cylindrical packaging, and harvest residue 3 crushed to a predetermined size is stored in flexible container bags or the like.

[0034] The utilization plan by the management device 20 and information on the distributed storage of harvest residue 3 in storage locations 5 based on the utilization plan are notified to workers including the manager via terminal devices, so that the workers including the manager can appropriately process the harvest residue 3 based on the utilization plan.

[0035] The demand forecast includes a predicted value of the amount of power required for each specified period by the biogas power generation plant 8 or the synthetic gas power generation plant 11, a predicted value of the amount of heat required for a specified period when using the waste heat from combustion generated from the combustor provided in the biogas power generation plant 8 or the synthetic gas power generation plant 11, and a predicted value of the amount required for a specified period when using the fermentation residue from the methane fermentation plant 6 as compost or fertilizer.

[0036] For example, when combustion waste heat generated from a combustor provided in the biogas power generation plant 8 or the synthetic gas power generation plant 11 is used as a heat source for a greenhouse, predicted values ​​of the required amount of heat and the required time are stored in the storage device 21. Also, for example, when the fermentation residue is to be returned to a field as fertilizer based on the amount of fertilizer components in the fermentation residue analyzed in advance, predicted values ​​of the time to apply fertilizer as base fertilizer, the amount of fertilizer components required, and the amount of fermentation residue to be returned are stored in the storage device 21, as well as predicted values ​​of the time to apply fertilizer as top-dressing, the amount of fertilizer components required, and the amount of fertilizer residue to be returned. In the case of rice cultivation, base fertilizer needs to be applied mainly during plowing from April to May, and top-dressing needs to be applied mainly around July. The amount of fertilizer needed to apply just the right amount during such periods is stored in the storage device 21 as a predicted value of demand.

[0037] [Resource circulation method] As shown in Figure 2, the resource circulation method operated by the resource circulation system 1 is configured to carry out a harvest residue collection process (SA1) for collecting harvest residues 3 generated in a field 2, a demand forecasting process (SA2) for predicting the annual demand for renewable resources using the harvest residues, a raw material storage process (SA3) for storing the harvest residues 3 in multiple storage locations 5 based on the demand forecast, an anaerobic treatment process (SA5) for supplying a portion of the stored harvest residues 3 to a methane fermentation device 6 for methane fermentation based on the demand situation (SA4), and a reduction process (SA8) for returning the fermentation residues generated in the anaerobic treatment process to the field 2 as compost or fertilizer.

[0038] By fermenting the harvest residue 3 into methane in the anaerobic treatment process (SA5), and then recovering the generated methane gas and using it as fuel for biogas power generation (SA6), the energy recovered from the harvest residue 3 can be effectively utilized.Furthermore, the fermentation residue can be recovered (SA7) and returned to the field 2 as compost or fertilizer (SA8), thereby achieving a circular utilization of resources and reducing farming costs.

[0039] Furthermore, when a large amount of harvest residue 3 is collected from the field 2 due to overlapping harvest seasons, the harvest residue 3 can be temporarily stored in a storage facility in the raw material storage process of step SA3, and as needed (SA4), a portion of the harvest residue 3 can be supplied to the anaerobic treatment process of step SA5, thereby enabling the harvest residue 3 to be used efficiently until, for example, a time outside the harvest season. Note that the harvest residue 3 collected in the field 2 may also be supplied directly to the anaerobic treatment process of step SA5 without going through a storage facility in the storage location 5.

[0040] The raw material storage step of step SA3 is preferably configured to store the harvest residue 3 collected in the harvest residue collection step of step SA1 under different storage conditions corresponding to the storage location 5. When the harvest residue 3 is distributed and stored in multiple storage locations 5, by varying the storage conditions of the harvest residue 3 according to the storage location 5, even large amounts of harvest residue 3 can be flexibly processed in accordance with the expected future demand for resources.

[0041] Possible storage conditions include, for example, the cutting length and storage volume of the harvest residue 3. For example, if anaerobic treatment needs to be carried out early, the HRT can be shortened by using harvest residue with a short cutting length, thereby increasing the amount of treatment that can be carried out by anaerobic treatment. In this way, by adjusting the storage volume and cutting length of the harvest residue and storing it in different storage locations as a pretreatment, it is possible to respond to changes in the timing and treatment volume of anaerobic treatment. For long-term storage, storing the harvest residue 3 in an uncut state for a long period of time allows the storage period to be used to properly compost under anaerobic conditions to facilitate methane fermentation.

[0042] As shown in step SA4, when the management device 20 determines, based on the demand forecast stored in the memory device 21 or the actual demand, that a large amount of top dressing will be required in the near future, such as one month from now, the harvest residue stored in the storage area 5 where short-cut harvest residue is accumulated is supplied to the nearest methane fermentation device 6, which is operated with a short HRT setting.As a result, the amount of processing that can be performed anaerobically can be adjusted, and management can be performed so that fermentation residue with a high soluble content suitable for top dressing can be obtained in a short period of time.

[0043] Furthermore, if the management device 20 determines, based on the demand forecast stored in the memory device 21 or actual demand, that a large amount of base fertilizer will be needed in the distant future, such as several months from now, the harvest residues 3 in the storage area 5 where long cut lengths of harvest residues 3 are accumulated can be supplied to the nearest methane fermentation device 6 in advance from a time when sufficient HRT can be secured, thereby managing the amount of fermentation residues containing a large amount of organic matter suitable for base fertilizer to be secured until the time when they are needed.

[0044] Because the harvest residue 3 contains organic matter such as lignin, which is difficult to decompose in an anaerobic environment, and fertilizer-effective components such as silica, it can be returned to the field as compost or fertilizer to effectively restore soil fertility. However, because the harvest residue 3 has a high C / N ratio and lacks elements necessary for methane fermentation, there is a risk that stable methane fermentation will not be achieved. Furthermore, the low nitrogen and phosphorus content will result in an imbalance in the nutrients necessary for compost or fertilizer. Therefore, in the anaerobic treatment of step SA5, it is preferable to adjust the components to produce a balanced compost or fertilizer by replenishing the methane fermentation apparatus 6 with the copper, iron, nickel, cobalt, and other elements necessary for methane fermentation bacteria, and by replenishing the nitrogen and phosphorus components using livestock manure or other materials before methane fermentation.

[0045] As described above, the resource circulation method is configured to manage storage information including the storage location 5 for storing the harvest residue 3 and storage conditions in the raw material storage process of step SA3, and to execute a management process to manage the timing and / or amount of supplying at least a portion of the harvest residue to the anaerobic treatment process of step SA5 based on the storage information.

[0046] The management process is carried out by the management device 20 described above, and by informing the manager or worker in advance that the waste should be stored in different storage locations under different storage conditions depending on the time when anaerobic treatment is required and the amount of treatment required at that time, it becomes easier to manage the timing and amount of anaerobic treatment thereafter.

[0047] It is preferable that the method further comprises a fermentation residue storage step in which the fermentation residue produced in the anaerobic treatment step of step SA5 and recovered in the fermentation residue recovery step of step SA7 is stored in a fermentation residue storage device 7, and that at least a portion of the fermentation residue stored in the fermentation residue storage step is returned to the field 2 in a reduction step of step SA8.

[0048] By storing the excess fermentation residue generated in the anaerobic treatment process in step SA5 in the fermentation residue storage device 7, it can be returned as compost or fertilizer to the required field 2 at the required time. The fermentation residue containing a mixture of solid and liquid components may be stored in that state, or the solid and liquid components may be separated and stored separately.

[0049] Furthermore, the resource circulation method further includes a gasification process in which the harvest residue 3 collected in the harvest residue collection process of step SA1 is gasified in a gasification device 9 (SA9), and is configured to adjust the amount of harvest residue supplied to the gasification process based on demand information for fermentation residue in step SA4.

[0050] In step SA4, the required amount of harvest residue is supplied to the anaerobic treatment process in step SA5 so that the amount of fermentation residue required for the reduction process in step SA8 is obtained based on the demand information for fermentation residue, and the surplus harvest residue 3 is supplied to the gasification treatment process in step SA9 to produce synthesis gas. The produced synthesis gas is supplied to the synthesis gas power generation system 11 to generate electricity (SA10).

[0051] The resource circulation method is preferably configured to adjust the amount of harvest residue to be supplied to the gasification treatment step in step SA9 based on storage information of the harvest residue 3 stored in the raw material storage step in step SA3.

[0052] By temporarily storing large amounts of harvest residue 3 collected at the same time in the raw material storage process of step SA3, and supplying a portion of it to the anaerobic treatment process of step SA5 and a portion of it to the gasification treatment process of step SA9 as needed, the harvest residue 3 can be efficiently utilized as a renewable resource.

[0053] In the gasification process of step SA9, the harvest residue 3 used as the raw material must be finely chopped. Therefore, the management device 20 is configured to manage the harvest residue 3 to be supplied to the gasification process in step SA3 by cutting it into a predetermined size using a pre-treatment device 4 and then accumulating it in a predetermined storage location 5.

[0054] Then, biochar, a by-product primarily composed of carbon, produced in the gasification process in step SA9 and separated in the gas purification device 10, is recovered (SA11) and returned to the farm field 2 together with compost or fertilizer, which is the fermentation residue (SA8), thereby enabling efficient recycling of resources.

[0055] [Resource circulation management method] The resource circulation management method according to the present invention is configured to carry out a harvest residue collection process (SA3) for collecting harvest residue 3 generated in a farm field 2, an anaerobic treatment process (SA5) for methane fermentation of the harvest residue collected in the harvest residue collection process, a reduction process (SA8) for returning at least a portion of the fermentation residue generated in the anaerobic treatment process to the farm field, and a resource circulation management process (SA4) for adjusting the amount of treatment in the anaerobic treatment process based on the amount and timing of harvest residue 3 obtained in the harvest residue collection process (SA1) and the amount of reduction required in the reduction process (SA8).

[0056] The resource circulation management method further includes a raw material storage step (SA3) for storing the harvest residue 3, and the resource circulation management step (SA4) is configured to adjust the storage location and storage conditions of the raw material in the raw material storage step (SA3) based on the amount and timing of the harvest residue obtained in the harvest residue collection step (SA1) and the reduction amount required in the reduction step (SA8). The resource circulation management step (SA4) is executed by the management device 20 and the memory device 21 described above.

[0057] [Anaerobic treatment method] The resource circulation method described above incorporates the anaerobic treatment method of the present invention. That is, the anaerobic treatment method is configured to subject raw materials, including harvest residues 3 generated in a farm field 2, to methane fermentation, use the fermentation residue resulting from the methane fermentation as compost or fertilizer, and use the biogas produced by the methane fermentation as an energy source, and is configured to adjust the cutting length of the harvest residues 3 to be supplied to the methane fermentation device 6 based on demand information for compost or the energy source managed by a management device 20.

[0058] As explained above, the time required for methane fermentation is important in terms of matching the demand for methane gas and fermentation residue. Therefore, by adjusting the cutting length of the harvest residue 3 to match the predicted demand for methane gas and fermentation residue, it becomes possible to adjust the HRT, which is the time required for methane fermentation, and to make effective use of the organic resource that is the harvest residue 3.

[0059] Specifically, when the demand for compost or the like or energy sources increases, it is preferable to adjust the cutting length or average cutting length of the harvest residue 3 to be supplied to methane fermentation so as to be shorter.

[0060] The methane fermentation process is controlled by operating conditions such as temperature, feedstock retention time (HRT), organic matter load, etc. By adjusting the chopping length or average chopping length of the harvest residue fed to methane fermentation to be shorter, the HRT can be shortened, which allows for an appropriate response to increased demand for compost, etc. or energy sources.

[0061] If the relationship between the length of the harvest residue 3 and the HRT required for methane fermentation is understood in advance, it becomes possible to appropriately adjust the cutting length of the harvest residue 3 based on this relationship to a value consistent with the target HRT. Figure 3 shows the relationship between the length L of the rice straw (harvest residue 3) and the HRT. The shorter the rice straw length L, the shorter the HRT, and as the rice straw length L increases, the HRT gradually saturates. For example, if the rice straw length L is a few mm, the HRT can be adjusted to about 20 days, and if the rice straw length L is a dozen or so mm, the HRT can be adjusted to about 40 days.

[0062] The harvest residue 3 is stored in separate cutting lengths, and based on demand information for compost or energy sources, the cutting length of the harvest residue to be supplied to methane fermentation is selected or blended to a predetermined length.

[0063] If the harvest residue 3 is stored in advance in separate cutting lengths, it is possible to select or mix the harvest residue so that the cutting length is a specified length, thereby adjusting the HRT to match the demand information for compost, etc. or energy sources.

[0064] In the above example, a portion of the harvest residue 3 collected in cylindrical packaging using a roll baler or the like is crushed in advance using a crushing device and stored in the storage area 5, but it is also possible to crush or cut the residue to the required size using a crushing device when subjecting it to methane fermentation processing.

[0065] In the above-described embodiment, a portion of the harvest residue is supplied to the gasification device 9, but other devices may be used as long as they are capable of supplying waste heat and / or electricity and / or returning the products to the field, such as incinerators, pyrolysis furnaces, carbonization furnaces, and other devices that process harvest residue by heating.

[0066] Although rice straw has been used as an example of harvest residue 3, it can be any agricultural waste generated after harvesting grains in the field, and rice straw may contain rice husks, or wheat straw or corn stalks, etc.

[0067] The various embodiments described above are examples of the present invention, and the scope of the present invention is not limited by the description. It goes without saying that the present invention can be appropriately modified and designed within the scope in which the effects of each invention are achieved. [Explanation of symbols]

[0068] 1: Resource circulation system 2: Field 3: Harvest residue (rice straw) 4: Pre-treatment device 5: Storage location 6: Methane fermentation equipment 7: Fermentation residue storage device 8: Biogas power generation equipment 9: Gasifier 10: Gas purification equipment 11: Synthetic gas power generation unit 20: Management device 21: Storage device

Claims

1. A harvest residue collecting step of collecting harvest residue generated in the field; an anaerobic treatment step of methane fermenting the harvest residue collected in the harvest residue collecting step; an energy utilization step in which the biogas produced in the anaerobic treatment step is utilized as an energy source; a reduction step of returning the fermentation residue produced in the anaerobic treatment step to a farm field; A resource recycling method including:

2. A resource circulation method as described in claim 1, wherein the energy utilization process is biogas power generation.

3. The method further includes a raw material storage step of storing the harvest residue between the harvest residue collection step and the anaerobic treatment step, 2. The resource recycling method according to claim 1, wherein at least a portion of the harvest residue stored in the raw material storage step is supplied to the anaerobic treatment step.

4. 4. The resource circulation method according to claim 3, wherein the raw material storage step is a step of storing the harvest residue collected in the harvest residue collecting step in a plurality of storage locations.

5. 5. The resource circulation method according to claim 1, further comprising a fermentation residue storage step for storing the fermentation residue produced in the anaerobic treatment step between the anaerobic treatment step and the reduction step, wherein at least a portion of the fermentation residue stored in the fermentation residue storage step is returned to a farm field.

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