2. Theresource recycling method according to claim l, further comprising, between the harvest residue collection step and the anaerobic treatment step, a raw material storage step of storing the harvest residues, wherein the method adjusts the amount ofthe harvest residues to be supplied to the gasification treatment step based on storage information about the harvest residues stored in the raw material storage step

3. Theresource recycling method according to claim I or 2, wherein the method retums a carbon-based byproduct produced in the gasification treatment step to the agricultural field together with the fermentation residues

FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. RESOURCE RECYCLING METHOD
2.
1. (A) KUBOTA CORPORATION
(B) Japan
(C) 1-2-47, Shikitsuhigashi, Naniwa-ku, Osaka-shi, Osaka 5568601 Japan
The following specification particularly describes the invention and the manner in which it is to be
performed.

2
DESCRIPTION
Technical Field
[0001] The present invention relates to aresource recycling method.
Background Art
[0002] A large amount of rice straw producedfrom rice harvest operations has conventionally
been plowed back into the soil of anagricultural field as an organic fertilizer or incineratedat the
agricultural field.However, methaneproduced from the decomposition of the plowed-back rice
straw in the soil in an anaerobic atmosphere and carbon dioxide produced fromthe
incinerationare greenhouse gases that have a large impact on global warming.As such, there is a
challenge in how to process the large amount of rice straw.Such a challenge is not exclusive to
rice straw, but is common to agricultural wastes (referred to herein as “harvest residues”)
produced after the harvest of grains harvested in agricultural fields, including wheat straw and
the like.
[0003] Patent Literature 1 proposes a methane fermentation method of causing straw crushed
into pieces of 10 mm to 100 mm to undergo methane fermentationin a fermentation liquidto
recover biogas and also recovering the straw after the fermentation from the digested solution to
utilize it as a bedding material.
Citation List
Patent Literature
[0004] Patent Literature 1: Japanese Patent No. 5567718
Summary of Invention
Technical Problem
[0005] The methane fermentation method disclosed in Patent Literature 1 is a very desirable
3
technique in terms of effective utilization of biomass resources, butthere is room for further
innovations in terms of efficiently processing a large amount of harvest residuesproduced in
agricultural fields, including rice straw and wheat straw.
[0006] It is an object of the present invention to provide aresource recycling method that can
efficiently utilize a large amount of harvest residues produced in agricultural fields as resources.
Solution to Problem
[0007] To achieve the above object, aresource recycling method is provided in accordance with
the present invention. As a first feature of the resource recycling method, the method comprises:
a harvest residue collection step of collectingharvest residuesproduced in an agricultural field; an
anaerobic treatment step ofcausing the harvest residues collected in the harvest residue collection
step to undergo methane fermentation; and a returningstepof returning fermentation residues
produced in the anaerobic treatment step to the agricultural field. The method further comprises
a gasification treatment step of gasifying the harvest residues collected in the harvest residue
collection step, and the method adjusts an amount of the harvest residues to be supplied to the
gasification treatment step based on information about demand for the fermentation residues.
[0008] Arequired amount of harvest residues is supplied to the anaerobic treatment step to yield
fermentation residues in an amount that is required in the returning step based on the information
about demand for the fermentation residues, and excess harvest residuesare supplied to the
gasification treatment step to generate a synthesis gas.
[0009] In addition to the first feature above, theresource recycling method has a second feature
thatthe method further comprises, between the harvest residue collection step and the anaerobic
treatment step, a raw material storage step of storing the harvest residues, and the method adjusts
the amount of the harvest residues to be supplied to the gasification treatment step based on
storage information about the harvest residues stored in the raw material storage step.
[0010] A large amount of harvest residues is collected from agricultural fields due to
overlapping harvest periods. Such a large amount of harvest residues is temporarily stored in the
raw material storage step, and if necessary, a portion of them is supplied to the anaerobic
4
treatment step while another portion of them is supplied to the gasification treatment step. This
allows for effective utilization of the harvest residuesas recycled resources.
[0011] In addition to the first or second feature above, theresource recycling method has a third
feature thatthe method returns a carbon-based byproduct produced in the gasification treatment
step to the agricultural field together with the fermentation residues.
[0012] Returning the carbon-based byproduct produced in the gasification treatment step to
agricultural fields together with the fermentation residues produced in the anaerobic treatment
step allows for efficient recycling and utilization of resources.
Advantageous Effects of Invention
[0013] As described above, the present invention can provide aresource recycling method that
can efficiently utilize a large amount of harvest residues produced in agricultural fields as
resources.
Brief Description of Drawings
[0014] FIG. 1 illustrates a method for processing harvest residues produced in agricultural
fields.
FIG. 2 illustrates a resource recycling method for harvest residues produced in
agricultural fields.
FIG. 3 isa characteristic diagram illustrating correlation between a length L of the harvest
residues (rice straw), a hydraulic retention time (HRT), and an amount to be treated.
Description of Embodiments
[0015] An anaerobic treatment method, a resource recycling method incorporating the anaerobic
treatment method, and a resource recycling management method of the present invention are
described below, by way of example with respect to rice straw, which is rice harvest
residuesproduced in agricultural fields.
[0016]
5
[Resource Recycling System]
FIG. 1 illustrates a resource recycling system 1 implementing the resource recycling
method of the present invention.
The resource recycling system 1 is constructed for each community farm or for multiple
community farms in the neighborhood. The resource recycling system 1 includes multiple
agricultural fields 2 where rice straw, or harvest residues 3, is produced,multiple storage
locations 5 for storing the harvest residues 3, a methane fermentation apparatus 6 forconducting
methane fermentation treatment mainly for the harvest residues 3, and a gasifier 9 forgenerating
a synthesis gas from the harvest residues 3.FIG. 1 shows a single methane fermentation
apparatus 6 and a single gasifier 9; however, in practice, multiple lines of methane fermentation
apparatuses 6 and/or multiple lines of gasifiers 9 may be dispersed or be consolidated in one
location, depending on the size of the harvest residues 3 to be received.
[0017] The resource recycling system 1 also includes a biogas power generator 8 for generating
electricity usingmethane gas (biogas) generated in the methane fermentation apparatus 6 as a
fuel.The electricity generated by the biogas power generator 8 is consumed as electrical energy
for the relevant area, and combustion waste heat producedin the biogas power generator 8 is
used as a heat source for the methane fermentation apparatus 6 and for greenhouses. Carbon
dioxide produced in the biogas power generator 8 is supplied to greenhouses as a raw material
gas for photosynthesis.
[0018] The methane fermentation apparatus 6 includes, among others, a methane fermentation
tank containing a fermentation liquid, a feeder for feeding the harvest residues 3 into the
methane fermentation tank, a mixing mechanism for mixing the harvest residues 3 and the
fermentation liquid, and a heating mechanism for adjusting the fermentation temperature. A
portion of the combustion waste heat produced during power generation is supplied to the
heating mechanism to heat the methane fermentation tankto about 55°C suitable for
athermophilic methane fermentation method, and organic substances are digested under
anaerobic conditions to generatethe biogas such as methane gas and carbon dioxide.
[0019] A fermentation residue tank 7 is provided near the methane fermentation apparatus 6 to
6
store fermentation residues produced in the methane fermentation apparatus 6, and the
fermentation residues stored in the fermentation residue tank 7 are returned to the agricultural
fields 2 as a compost or fertilizer.
[0020] The gasifier 9 includes a reaction tower into which the cut harvest residues 3 are fed.The
harvest residues 3 are fluidized and mixedwith high-temperature steam and oxygen gas inside
the reaction tower to causea water gas reaction and a water gas shift reaction,thereby generating
a synthesis gas containing hydrogen and carbon monoxide. Biochar consisting of silicacontaining carbon components is also generated as ash discharged with the synthesis gas.
[0021] The water gas reaction refers to an endothermic reaction in which carbon monoxide CO
and hydrogen H2 are generated from solid carbon C contained in the harvest residues 3 and
steam H2O in a high temperature environment at or above 500, as shown in the following
formula:
C+H2O → CO+H2
[0022] The water gas shift reaction refers to an exothermic reaction in which carbon dioxide
CO2 and hydrogen H2 are generated from carbon monoxide CO and steam H2O in a high
temperature environment at or above 800, as shown in the following formula:
CO+H2O → CO2+H2
[0023] The synthesis gas generated inthe gasifier 9 is purified by a gas purifier 10, and the
biochar containing carbon components removed from the synthesis gas is returned to the
agricultural fields 2 as a compost or fertilizer together with the fermentation residues described
above.
[0024] The resource recycling system 1 includes a synthesis gas power generator 11 that uses
the synthesis gas generated in the gasifier 9 as a fuel to generate electricity. The generated
electricity is supplied as electrical energy for the relevant area, and the combustion waste heat
produced in the synthesis gas power generator 11 is used as a heat source for the methane
fermentation apparatus 6 and for greenhouses. Carbon dioxide produced in the synthesis gas
power generator 11is supplied to greenhouses as a raw material for photosynthesis.
[0025] Instead of the synthesis gas power generator 11, the resource recycling system 1 may
7
include an FT synthesis apparatus that uses a synthesis gas consisting of carbon monoxide and
hydrogen as a raw material to synthesize liquid hydrocarbon as a fuel through a catalytic
reaction. The FT synthesis, which is an abbreviation for the Fischer-Tropsch synthesis, refers to
a series of synthesis reaction processes for synthesizing liquid hydrocarbon from carbon
monoxide and hydrogen through a catalytic reaction.
[0026] At the time of rice harvest, a large amount of rice straw remaining in the agricultural
fields 2 after the harvest, or the harvest residues 3, is, for example, packed into a cylindrical
shape and collected by a roll baler or the like. Accumulating such a large amount of harvest
residuesin one location and conducting methane fermentation treatment on it at one time is
physically difficult, including the cost of equipment, so even if a large amount of biogas is
temporarily obtained, it may not be effectively utilized. Accordingly, separate biogas storage
facilities are required.
[0027] Thus, multiple storage locations 5 are dispersed throughout the farming areas
constituting the community farm.The harvest residues 3 collected in each agricultural field2 are,
if necessary, cut by a chipper shredder or any other crusher that is used as a pre-treatment
apparatus4 and capable of cutting the residuesinto a predetermined size, before being
accumulated ina nearest storage location5. The above phrase “if necessary”means that such
cutting is performed to correspond to the hydraulic retention time (HRT) during methane
fermentation, which is adjusted according to various demand forecasts by a management device
20 (described below).
[0028] Various forms of storages are provided in the storage location 5, including a roofed
storage and an unroofed storage where the residues are stored open-air.The appropriate number
of methane fermentation apparatuses 6 and/or gasifiers 9 are provided according to the layout
and number of storage locations 5.
[0029] A management device 20, which is implemented by a cloud-based server equipped with
a memory device 21, is provided to manage the harvest residues 3 for each community farm or
for multiple community farms in the neighborhood. In addition to the storage locations and types
of storage, the management device 20 manages information such as the start of storage (rice
8
harvest time), cut lengths, varieties, and growers. The resource recycling system 1 is configured
such that a manager of the methane fermentation apparatus 6 and a manager of the gasifier 9 can
identify the management condition of the harvest residues 3 via respective terminals that can
communicate with the management device 20.
[0030] The resource recycling system 1 is configured such that the management device 20
creates a storage plan and a utilization plan for the harvest residues 3 based on annual demand
forecasts until the following year’s harvest, and based on the plans, the harvest residues 3
arestored dispersedly in the multiple storage locations 5 in different crushed conditions and
utilized. Uncrushed harvest residues 3 are stacked in cylindrical packages, and harvest residues
3 crushed into a predetermined size are stored in containers such as flexible container bags.
[0031] The resource recycling system 1 is configured such that the utilization plan created by
the management device 20 and information about the dispersed storage of the harvest residues 3
in the storage locations 5 based on the utilization plan are reported to operators including the
managers via respective terminals, and the operators including the managers can properly
process the harvest residues 3 based on the utilization plan.
[0032] The demand forecasts include a forecast of the amount of electricity required to be
generated by the biogas power generator 8 or the synthesis gas power generator 11 for each
predetermined period, a forecast of the amount of heat required for a predetermined period when
the combustion waste heat produced from the combustor in the biogas power generator 8 or the
synthesis gas power generator 11 is used, and a forecast of the amount of fermentation residues
requiredfor a predetermined period when the fermentation residues from the methane
fermentation apparatus 6 are used as a compost or fertilizer.
[0033] For example, when the combustion waste heat produced from the combustor in the
biogas power generator 8 or the synthesis gas power generator 11 is used as a heat source for
greenhouses, forecasts of the amount and timing of heat required are stored in the memory
device 21. Also, for example, when the fermentation residues are returned to the agricultural
fields as a fertilizer based on the amount of fertilizer components in the fermentation residuesthat
is analyzed in advance, forecasts of when the fertilizer is to be applied as a base fertilizer, the
9
amount of fertilizer components required, and the amount of fermentation residues returned, as
well as forecasts of when the fertilizer is to be applied as an additional fertilizer, the amount of
fertilizer components required, and the amount of fermentation residues returned are stored in
the memory device 21. In the case of rice cultivation, it is necessary to apply the base fertilizer
mainly during soil puddling conducted in April and May and to apply the additional fertilizer
mainly around July. The just enough amount of fertilizer required to be applied at such times is
stored as a demand forecast in the memory device 21.
[0034]
[Resource Recycling Method]
As shown in FIG. 2, the resource recycling method operated by the resource recycling
system 1 is configured to execute, among others: a harvest residue collection step (SA1) of
collecting the harvest residues 3 produced in the agricultural fields 2; a demand forecasting step
(SA2) of forecasting the annual demand for recycled resources using the harvest residues; a raw
material storage step (SA3) of storing the harvest residues 3 dispersedly in multiple storage
locations 5 based on the forecast demand; an anaerobic treatment step (SA5) ofsupplying a
portion of the stored harvest residues 3 to the methane fermentation apparatus 6 to cause them to
undergo methane fermentation based on the demand situation (SA4); and a returningstep (SA8)
of returning the fermentation residues produced in the anaerobic treatment step to the agricultural
fields 2 as a compost or fertilizer.
[0035] The harvest residues 3 are caused to undergo methane fermentation in the anaerobic
treatment step (SA5), and the produced methane gas is recovered and used as a fuel for biogas
power generation (SA6), thus effectively utilizing the energy recovered from the harvest residues
3. The fermentation residues are also recovered (SA7) and returned to the agricultural fields 2 as
a compost or fertilizer (SA8). This recycling and utilization of resources can reduce the farming
cost.
[0036] When a large amount of harvest residues 3 is collected from the agricultural fields 2 due
to overlapping harvest periods, the harvest residues 3 can be temporarily stored in the storages in
the raw material storage step SA3, and if necessary (SA4), a portion of the harvest residues 3 can
10
be supplied to the anaerobic treatment step SA5. This allows for, for example, effective
utilization of the harvest residues 3 even outside the harvest periods.The harvest residues 3
collected fromthe agricultural fields 2 may be supplied directly to the anaerobic treatment step
SA5 without going through storages provided in the storage locations 5.
[0037] Preferably, the raw material storage step SA3 is configured to store the harvest residues 3
collected in the harvest residue collection step SA1 under different storage conditions
corresponding to the storage locations 5.This is because by varying the storage conditions for the
harvest residues 3 according to the storage locations 5 when storing the harvest residues 3
dispersedly in the multiple storage locations 5, even a large amount of harvest residues 3 can be
processed flexibly to meet anticipated future resource demands.
[0038] Assumable storage conditions include, for example, the cut length of the harvest residues
3 and the amount of storage. For example, when the anaerobic treatment needs to be done early,
harvest residues with a shorter cut length can be used to shorten the HRT, which can
consequentlyincrease the amount to be treated of the anaerobic treatment. Adjusting the amount
of storage and cut length of the harvest residues in this manner as a preprocess before storing
them in different storage locations can accommodate changes in when and how much the
anaerobic treatment is to be done. Whenthe harvest residues 3 are stored over a long period of
time, they can be stored in a long state without being cut, which, taking advantage of the storage
period, allows them to property mature under anaerobic conditions to facilitate methane
fermentation.
[0039] As shown in step SA4, if the management device 20 determines, based on the forecast
demand stored in the memory device 21 or an actual demand, that a large amount of additional
fertilizer will be needed in the near future, such as one month ahead, the harvest residues may be
managed such that those in the storage location 5 where the harvest residues with a shorter cut
length are accumulated are supplied to the nearest methane fermentation apparatus 6, and it may
be operated with a shorter HRT setting. The amount to be treated of the anaerobic treatment can
be thus adjusted, making it possible to obtain fermentation residues with high dissolved content
suitable for additional fertilizers in a short period of time.
11
[0040] If the management device 20 determines, based on the forecast demand stored in the
memory device 21 or an actual demand, that a large amount of base fertilizer will be needed in a
more distant future, such as several months ahead, the harvest residues may be managed such
that those in the storage location 5 where the harvest residues 3 with a longer cut length are
accumulated are supplied to the nearest methane fermentation apparatus 6 in advance, starting
from a time when there is enough time to ensure a sufficient HRT. Thus, the required amount of
fermentation residues with high organic content suitable for base fertilizers can be secured until
the time when they are needed.
[0041] Since the harvest residues 3 contain organic substances such as lignin, which is difficult
to decompose in anaerobic condition, and fertilizer ingredientssuch as silica components,
returning the harvest residues 3 to agricultural fields as a compost or fertilizer can effectively
restore the soil fertility. The harvest residues 3 have a high C/N ratio and lack elements
necessary for methane fermentation, which may make stable methane fermentation
impossible.In addition, the harvest residues 3 have small nitrogen and phosphorus components,
so that there is an imbalance in nutrients necessary for a compost or fertilizer. Accordingly, the
anaerobic treatment in step SA5 preferably involves feeding deficient components, such as
copper, iron, nickel, and cobalt,needed by methane fermentation bacteria, as well as nitrogen and
phosphorus components recovered from livestock manure and the like to the methane
fermentation apparatus 6 to cause methane fermentation, thereby adjusting the components of
the harvest residues 3 to make them a well-balanced compost or fertilizer.
[0042] As described above, the resource recycling method is configured to execute a
management step of managing storage information including the storage locations 5 and the
storage conditions to store the harvest residues 3 in the raw material storage step SA3, and
managing, based on the storage information, the timing and/or amount of supply of at least a
portion of the harvest residues to the anaerobic treatment step SA5.
[0043] The managementstep is executed by the above-described management device 20, which
informs the managers and operators in advance to pre-store the harvest residues in different
storage locations under different storage conditions depending on the timing when the anaerobic
12
treatment will be required and the amount to be treated required at that time. This facilitates the
management of the timing and amount to be treated of the subsequent anaerobic treatment.
[0044] The resource recycling method preferably further includes a fermentation residue storage
step of storing, in the fermentation residue tank 7, the fermentation residuesproduced in the
anaerobic treatment step SA5 and recovered in the fermentation residue recovery stepSA7, and
the method is preferably configured to return at least a portion of the fermentation residues
stored in the fermentation residue storage step to the agricultural fields 2 in the returning step
SA8.
[0045] Excess fermentation residues produced in the anaerobic treatment step SA5 are stored in
the fermentation residue tank 7, so that they can be returned as a compost or fertilizer to the
agricultural field 2 in need, when needed.The fermentation residues with mixed solid and liquid
components may be stored in that state, or the fermentation residues may undergo solid-liquid
separation to store solid and liquid components separately.
[0046] The resource recycling method further includes a gasification treatment step of gasifying
the harvest residues 3 collected in the harvest residue collection step SA1 in the gasifier 9 (SA9),
and the method is configured to adjust the amount of harvest residues supplied to the gasification
treatment step based on the information about demand for fermentation residues determined in
step SA4.
[0047] Arequired amount of harvest residues is supplied to the anaerobic treatment step SA5 to
yield fermentation residues in an amount that is required in the returning step SA8 based on the
information about demand for fermentation residues determined in step SA4, and excess harvest
residues 3 are supplied to the gasification treatment step SA9 to generate a synthesis gas.The
generated synthesis gas is supplied to the synthesis gas power generator 11 to generate electricity
(SA10).
[0048] The resource recycling method is preferably configured to adjust the amount of harvest
residues supplied to the gasification treatment step SA9 based on the storage information about
the harvest residues 3 stored in the raw material storage step SA3.
[0049] A large amount of harvest residues 3 collected in the same period is temporarily stored in
13
the raw material storage step SA3, and if necessary, a portion of them is supplied to the
anaerobic treatment step SA5 while another portion of them is supplied to the gasification
treatment step SA9. This allows for effective utilization of the harvest residues 3 as recycled
resources.
[0050] For the gasification treatment step SA9, the harvest residues 3 as the raw material need to
be cut into small pieces. Accordingly, the management device 20 is configured to manage the
harvest residues 3 such that those to be supplied to the gasification treatmentstep are cut into a
predetermined size by the pre-treatment apparatus4 in step SA3 in advance before they are
accumulated in a predetermined storage location 5.
[0051] The resource recycling method is configured to recover biochar (SA11), which is a byproduct from the gasification treatment step SA9 based on carbon separated in the gas purifier
10, and return it to the agricultural fields 2 together with a compost or fertilizer, which is the
fermentation residues (SA8). This allows for efficient recycling and utilization of resources.
[0052]
[Resource Recycling Management Method]
The resource recycling management method according to the present invention is
configured to execute: a harvest residue collection step (SA1) of collecting the harvest residues 3
produced in the agricultural fields 2; an anaerobic treatment step (SA5) ofcausing the harvest
residuescollected in the harvest residue collection stepto undergo methane fermentation; a
returning step (SA8) of returning at least a portion of fermentation residues produced in the
anaerobic treatment step to the agricultural fields; and a resource recycling management step
(SA4) of adjusting the amount to be treated in the anaerobic treatment step based on the amount
and timing of the harvest residues 3obtained in the harvest residue collection step (SA1) and the
return amount required in the returning step (SA8).
[0053] The resource recycling management method further includes a raw material storage step
(SA3) of storing the harvest residues 3. The resource recycling management step (SA4) is
configured to adjust the storage locations and storage conditions for the raw material in the raw
material storage step (SA3) based on the amount and timing of the harvest residues obtained in
14
the harvest residue collection step (SA1) and the return amount required in the returning step
(SA8). The resource recycling management step (SA4) is executed by the above-described
management device 20 and memory device 21.
[0054]
[Anaerobic Treatment Method]
The above-described resource recycling method incorporates an anaerobic treatment
method of the present invention. That is, the anaerobic treatment method is configured to cause
the raw material including the harvest residues 3 produced in the agricultural fields 2 to undergo
methane fermentation to utilize fermentation residues produced from the methane fermentation
as a compost or fertilizer and to utilize biogas produced from the methane fermentation as an
energy source. The anaerobic treatment method is also configured to adjust the cut length of the
harvest residues 3 to be supplied to the methane fermentation apparatus 6 based on the
information about demand for the compost etc. or the energy source managed by the
management device 20.
[0055] As already explained above, the time required for methane fermentation is important in
terms of matching the demand for methane gas and fermentation residues. Hence, the cut length
of the harvest residues 3 is adjusted according to the forecast demand for methane gas and
fermentation residues. This enables adjustment of the HTR, which is the time required for
methane fermentation, allowing for effective utilization of the organic resources of the harvest
residues 3.
[0056] Specifically, it is preferable that the cut length or average cut length of the harvest
residues 3 to be supplied tothe methane fermentation is adjusted to be short in response to an
increase in demand for the compost etc. or the energy source.
[0057] The methane fermentation process is controlled by operating conditions such as the
temperature, hydraulic retention time (HRT), and organic load. By adjusting the cut length or
average cut length of the harvest residuesto be supplied tothe methane fermentation to be short,
the HRT can be shortened, which allows for properly responding to an increase in demand for
the compost etc. or the energy source.
15
[0058] By knowing the relationship between the length of the harvest residues 3 and the HRT
required for methane fermentation in advance, the cut length of the harvest residues 3 can be
properly adjusted to a value consistent with the target HRT based on this relationship.FIG. 3
shows the relationship between the length L of the rice straw as the harvest residues 3 and the
HRT. As a characteristic of the relationship, the shorter the length L of the rice straw, the shorter
the HRT, and the HRT gradually saturates as the length L of the rice straw increases.For
example, if the length L of the rice straw is a few millimeters, the HRT can be adjusted to about
20 days, and if the length L of the rice straw is a dozen millimeters, the HRT can be adjusted to
about 40 days.
[0059] The anaerobic treatment method is configured to store the harvest residues 3 separately
in multiple cut lengths and, based on the information about the demand for the compost etc. or
the energy source, select or load the harvest residues 3 such that those with a predetermined cut
length are supplied to the methane fermentation.
[0060] By storing the harvest residues 3 separately in multiple cut lengths, those with a
predetermined cut length can be selected or loaded from them. This allows the HRT to be
adjusted to be consistent with the information about demand for the compost etc. or the energy
source.
[0061] In the above example, a portion of the harvest residues 3packed into a cylindrical shape
and collected by a roll baler or the like is pulverized by a pulverizer in advance before being
stored in the storage location 5. However, they may be crushed or cut into a required size using
a crusher when they are subjected to the methane fermentation treatment.
[0062] In the above embodiment, a portion of the harvest residues issupplied to the gasifier 9.
However, they may be supplied to any other apparatus capable of supplying waste heat and/or
electricity and/or returning the products to the agricultural fields, and such apparatuses may
include, for example, an apparatus that processes the harvest residues by heating, such as an
incinerator, a pyrolysis furnace, and a carbonization furnace.
[0063] While the rice straw has been discussed as an example of the harvest residues 3, any
agricultural waste produced after the harvest of grains harvested in agricultural fields may be
16
used. As such, the rice straw may contain rice hulls, and wheat straw, cornstalks, etc. may also
be used.
[0064] It will be appreciated that any of theabove-described embodiments is only an example of
the present invention. The above descriptions are not limiting the present invention, and the
embodiments may be varied as suited, as long as such variations provide the functions and
effects of the present invention as well.
Reference Signs List
[0065] 1: Resource recycling system
2: Agricultural field
3: Harvest residue (rice straw)
4: Pre-treatment apparatus
5: Storage location
6: Methane fermentation apparatus
7: Fermentation residue tank
8: Biogas power generator
9: Gasifier
10: Gas purifier
11: Synthesis gas power generator
20: Management device
21: Memory device

We Claim:
l. Aresource recycling method comprising:
a harvest residue collection step ofcollectingharvest residuesproduced in an agricultural
field;
an anaerobic treatment step ofcausing the harvest residues collected in the harvest
residue collection step to undergo methane fermentation; and
a retumingstepof retuming fermentation residues produced in the anaerobic treatment
step to the a$icultural field, wherein
the method further comprises a gasification tr€atment step of gasirying the harvest
residues collected in the harvest residue collection step, and
the method adjusts an amount ofthe harvest residues to be supplied to the gasification
treatment step based on information about demand for the fermentation residues.

2. Theresource recycling method according to claim l, further comprising, between the
harvest residue collection step and the anaerobic treatment step, a raw material storage step of
storing the harvest residues, wherein
the method adjusts the amount ofthe harvest residues to be supplied to the gasification
treatment step based on storage information about the harvest residues stored in the raw material
storage step

3. Theresource recycling method according to claim I or 2, wherein the method retums a
carbon-based byproduct produced in the gasification treatment step to the agricultural field
together with the fermentation residues